Process for Preparing Torrefied Biomass Material Using a Combustible Liquid

Info

Publication number: 20160152911
Type: Application
Filed: Jul 17, 2014
Publication Date: Jun 2, 2016
Inventors: Brent Wiren (Vancouver), Paul Adams (Vancouver), J. Moon (Vancouver), John Goodwin (Vancouver), Larry Brent Taylor (Vancouver)
Application Number: 14/905,745

Abstract

A process for preparing torrefied densified biomass and/or torrefied densified biosolids comprising about 2% to about 25% w/w combustible liquid is disclosed. The process involves densifying biomass and/or biosolids, or providing a densified biomass and/or densified biosolids, and submerging the densified material in a hot combustible liquid for about 2 to about 120 minutes until the densified material is torrefied. The combustible liquid may be derived from any source exemplified by an oil such as those derived from plant, marine and animal sources, or alternatively, a petroleum product. The combustible liquid is heated to a temperature in the range of about 160° C. to about 320° C. prior to submersion of the densified biomass material. Also disclosed is a biomass torrefied densified biomass and/or torrefied densified biosolid comprising about 2% to about 25% w/w combustible liquid.

Description

Description

TECHNICAL FIELD

The present disclosure pertains to torrefied biomass and/or biosolids, and in particular, to a torrefied densified biomass and/or torrefied densified biosolid comprising a combustible liquid and processes for preparing such torrefied densified biomass and/or biosolids using a combustible liquid.

BACKGROUND

Biomass and biosolids are becoming important sources of energy as the supply of fossil fuels decreases. Burning of petroleum, coal and other fossil fuels also leads to pollutants and greenhouse gases being released into the air and water. Biomass and biosolids are renewable, produce significantly fewer greenhouse gases than fossil fuels and are widely available. Raw biomass and biosolids, however, generally have a low density resulting in inefficient storage and transportation. The low energy densities and higher moisture contents of raw biomass and biosolids also hampers the widespread use of raw biomass and biosolids as a source of thermal energy or as a coal replacement.

Torrefaction of raw biomass and biosolids has been developed recently to turn the biomass and biosolids into a charcoal-like state by slow-heating the biomass and biosolids in an oxygen-free or low-oxygen environment to a maximum temperature of about 300° C. The lack of oxygen prevents the biomass and/or biosolids from burning, and instead, the material is torrefied. Slow-heating biomass and biosolids also leads to loss of mass due to the volatile organic compounds (VOCs) within the raw biomass and biosolids being gassified. Torrefaction also causes chemical changes to the cellular structures of the material, resulting in a partial loss of mass and a loss in mechanical strength and elasticity. Torrefaction, therefore, also produces a product that has increased friability and grindability. Furthermore, torrefied material is hydrophobic and therefore, stays dry and is insensitive to atmospheric humidity. This reduces the risk of rotting, overheating, and auto-ignition of the materials when stored.

Prior art torrefaction processes generally involve one of high-pressure steam, high temperature inert gas or superheated steam in the heat treatment processes. Other torrefaction processes using gas or pressure or vacuum methods may also be used. Most of these prior technologies, however, fail to efficiently and practically convert biomass into torrefied wood in a simple, easy, quick, practical, safe, uniform and economic way. In particular, using any type of inert gas or steam involves large containment systems with large amounts of surface area, high equipment costs, high energy costs, slow treatment rates, and low overall operating efficiencies with resultant high production costs. The systems and equipment are complex and large for containing the inert gas or steam heat transfer medium, and often require heavyweight materials given the high operating pressures required with steam. Furthermore, these systems often require more than an hour to torrefy biomass. Consequently, the prior technologies also have challenges with scalability.

Recent torrefaction processes have also used bio-liquids (such as, vegetable oils, soybean oils, canola oils or animal tallow), paraffinic hydrocarbons, oil, molten salts or paraffin, to heat and torrefy biomass. Some of these technologies, however, involve intricately designed housings for holding the liquids and torrefying the biomass, and require the biomass to pass through a plurality of pools, rivers or liquid compartments holding the liquids during the torrefaction process. These processes, therefore, may require additional engineering efforts, complicated designs and large volumes of the torrefying liquids. Moreover, these processes often involve a pre-heating stage and/or a drying stage prior to the torrefaction treatment, thus, being costly to operate and time-consuming.

SUMMARY

The exemplary embodiments of the present disclosure generally pertain to a torrefied densified biomass and/or biosolid comprising a combustible liquid and processes for preparing the torrefied densified biomass and/or biosolid using a combustible liquid exemplified by hydrocarbons, such as plant-derived oils, marine-derived oils, animal-derived oils, petroleum products and bitumen-based products.

An exemplary process for preparing a torrefied densified biomass and/or torrefied densified biosolids of the present disclosure is disclosed herein, in which a combustible liquid is used for torrefying a densified biomass material and/or densified biosolid material. The exemplary process may comprise one of two starting materials: (i) the initial starting material may be raw biomass and/or biosolids that undergo densification prior to heating in the combustible liquid; or (ii) the initial starting material may be densified biomass and/or densified biosolids that are readily available in the marketplace.

An exemplary process of the present disclosure generally comprises the steps of densifying raw biomass and/or biosolids; submerging the densified material into a combustible liquid heated to a temperature in a range of about 160° C. to about 320° C.; and torrefying the densified material in the heated combustible liquid for about 2 minutes to about 120 minutes to produce a torrefied densified biomass and/or biosolid. The resulting torrefied densified material comprises about 2% to about 25% w/w combustible liquid. The densified biomass and/or biosolids may be directly transferred from the densifying process into the combustible liquid to minimize any loss of heat gained by the biomass/biosolids densification. This may increase efficiency of the process as the heated densified biomass and/or densified biosolids will require less heating in the combustible liquid.

The process may further comprise a drying step post-densification or prior to transferring the densified material into the combustible liquid. Drying may be done in conjunction with densification.

The starting feedstock may also comprise commercially available densified biomass and/or densified biosolids. With such feedstocks, the initial densification step disclosed herein is not required.

The biomass material to be torrefied may comprise any type of material derived from living or recently living organisms, and are exemplified by plant biomass such as sugar-cane bagasse, corn stover, rice straw, wheat straw, bamboo, switchgrass, and hemp. The biomass material may also comprise wood biomass such as softwood, hardwood, sawdust, hog fuel and wood byproducts. The biosolids may be recovered from sewage or wastewater during a sewage treatment process, alternatively obtained from municipal sewage treatment processes, alternatively obtained from industrial waste streams exemplified by fruit and vegetable processing plants and fibre processing plants, or alternatively, may be agricultural wastes from livestock and poultry production. The biomass and/or biosolids may also be any combination of the feedstocks described herein.

The exemplary processes disclosed herein may also be continuous processes, semi-continuous processes, or batch processes. In such processes, the supply of biomass material to a pelleter or briquetter may be continuous or semi-continuous or in batches. Alternatively, if commercially available densified biomass and/or densified biosolids are used, then the supply of such densified material to the combustible liquid may be continuous or semi-continuous or in batches.

The combustible liquid preferably comprises a hydrocarbon exemplified by plant-derived oils, marine-derived oils, animal-derived oils, petroleum products and bitumen-based products that are heatable to a temperature of up to about 320° C. The combustible liquid may be derived from any source such as, for example, an oil derived from a plant source, a marine source, an animal source, a petroleum product and a bitumen-based product. For example, the combustible liquid may be canola oil, linseed oil, sunflower oil, safflower oil, corn oil, peanut oil, palm oil, soybean oil, rapeseed oil, cottonseed oil, palm kernel oil, coconut oil, sesame seed oil, olive oil, animal tallow, fish oil, liver oil, and mixtures thereof. Alternatively, the combustible liquid may be a petroleum-based oil or a bitumen-based oil, such as, for example, a synthetic motor oil or engine oil exemplified by 5W-30 and 10W-30 engine oil; a chainsaw bar oil; a chain oil; transmission fluid oils and fluids exemplified by automatic transmission fluids (ATF); hydraulic fluids; gear oils; diesel fuel; paraffin wax; paraffin oil; kerosene, stove oil; and mixtures thereof

The torrefied densified biomass and/or biosolid disclosed herein and obtained from the processes described herein may absorb between about 2% and 25% w/w combustible liquid during the torrefaction process, and may have a heat energy value of about 6,000 BTU per pound on a bone dry basis to about 13,000 BTU per pound on a bone dry basis, or any amount therebetween. The heat energy value may also be expressed in gigajoules per metric tonne (GJ/t), with the torrefied densified biomass and/or biosolid obtained from the processes described herein having a heat energy value of about 22 GJ/t on a bone dry basis to about 27 GJ/t on a bone dry basis, or any amount therebetween.

The torrefied densified biomass and/or biosolid disclosed herein and obtained from the processes described herein may also comprise a carbon content of about 50 carbon % on a bone dry basis to about 65 carbon % on a bone dry basis and may also be hydrophobic in nature.

The exemplary processes disclosed herein may also include a gas collection and condenser system for collecting and separating VOCs, vapours and steam expelled and/or generated during the densification, drying and torrefaction processes, for condensation and separation into reusable energy sources.

DESCRIPTION OF THE DRAWINGS

The present disclosure will be described in conjunction with reference to the following drawings in which:

FIG. 1 is a schematic flowchart showing an exemplary process for preparing a torrefied densified biomass material and/or a torrefied densified biosolid material;

FIG. 2 is schematic flowchart showing a second exemplary process for preparing a torrefied densified biomass material and/or a torrefied densified biosolid material;

FIG. 3 is a schematic flowchart showing an exemplary process for densification and torrefaction of a biomass feedstock;

FIG. 4 is a schematic flowchart showing an exemplary process for densification and torrefaction of a hog fuel feedstock;

FIG. 5(A) is a perspective top-side view of an exemplary embodiment of a torrefusion reactor for use in a continuous, semi-continuous or batch throughput torrefaction process of the present disclosure, showing torrefied pellets being transported out of a combustible liquid; FIG. 5(B) is a perspective top-side view of an exemplary alternative embodiment of a torrefusion reactor for use in a continuous, semi-continuous or batch throughput torrefaction process of the present disclosure, with densified biomass and/or densified biosolids being loaded in a densified biomass/biosolids metering bin;

FIG. 6(A) is a perspective top-side view of the torrefusion reactor shown in FIG. 5(B), showing torrefied pellets being transported out of a combustible liquid; and FIG. 6(B) is a perspective top-side view of the torrefusion reactor shown in FIG. 5(B), showing the direction of rotation of the conveyor of the torrefusion reactor as densified biomass and/or densified biosolids proceed through the continuous, semi-continuous or batch throughput torrefaction process of the present disclosure;

FIG. 7 is a chart showing physicochemical changes that occur in a biomass feedstock over a period of time during processing with an exemplary torrefaction process disclosed herein;

FIG. 8 is a graph showing the heat value of biomass feedstock that has been processed with an exemplary torrefaction process disclosed herein, wherein the biomass feedstock has been processed at different temperatures for different periods of time;

FIG. 9 is a graph showing the heat value of biomass feedstock that has been processed with an exemplary torrefaction process disclosed herein, wherein the biomass feedstock has been processed at different temperatures for different periods of time;

FIG. 10 is a graph showing the carbon content of a biomass feedstock that has been processed with an exemplary torrefaction process disclosed herein, wherein the biomass feedstock has been processed at different temperatures for different periods of time;

FIG. 11 is a graph showing the mass of biomass feedstock and the oil absorption by biomass feedstock that has been processed for different time periods using canola oil as the combustible liquid;

FIG. 12 is a graph showing the mass of biomass feedstock and the oil absorption by biomass feedstock that has been processed for different time periods using paraffin wax as the combustible liquid;

FIG. 13 is a graph showing a comparison between the total losses of combustible liquids canola oil and paraffin wax in an exemplary torrefaction process according to the present disclosure;

FIG. 14 is a graph showing a comparison between the reductions in weight of biomass feedstock (in %) when canola oil or paraffin wax are used as the combustible liquids in an exemplary torrefaction process according to the present disclosure;

FIG. 15 is a graph showing comparisons of water absorption by biomass feedstocks that have been processed at different temperatures for different periods of time in an exemplary torrefaction process according to the present disclosure;

FIG. 16 is a graph showing comparisons of water absorption by biomass feedstocks that have been processed for increasing time periods and at increasing time periods with an exemplary torrefaction process of the present disclosure;

FIG. 17 is a graph showing total oil absorptions by biomass feedstock processed with different types of oil as combustible liquids with an exemplary torrefaction process of the present disclosure;

FIG. 18 is a graph showing total oil absorptions by biomass feedstock processed with different types of oil as combustible liquids with an exemplary torrefaction process of the present disclosure; and

FIG. 19 is a perspective side view of a small-scale torrefusion reactor suitable for use in some of the exemplary torrefaction processes disclosed herein.

DETAILED DESCRIPTION

The exemplary embodiments of the present disclosure pertain to torrefied densified biomass and/or torrefied densified biosolids comprising a combustible liquid exemplified by hydrocarbons. Some exemplary embodiments pertain to processes for preparing a torrefied densified biomass and/or torrefied densified biosolids comprising a combustible liquid. Suitable combustible liquids are exemplified by plant-derived oils, marine-derived oils, animal-derived oils, petroleum-based products and bitumen-based products.

The exemplary torrefaction processes disclosed herein require a reduced energy consumption as compared to prior art processes, while improving process efficiency and feedstock throughput. Energy exemplified by VOCs and steam, produced during the process, may be recycled through the system to heat the combustible liquid, and/or to create pellets for torrefaction, and/or to torrefy the densified biomass. It was surprisingly found that minimal oil is actually absorbed by the densified biomass during the present torrefaction processes. Accordingly, the combustible liquids used during the torrefaction steps may be repeatedly recycled and reused to process additional biomass feedstocks, thus reducing input costs. Furthermore, any type of oil may be used for these processes, including less valuable and cheaper oils that may have high contents of unsaturated fats, thereby even further reducing input costs. It is to be noted that use of a densified material as a biomass feedstock will reduce torrefaction processing time, as demonstrated in the Examples provided herein.

The torrefaction processes disclosed herein also do not require a vast amount of space to operate and are easily assembled and used, especially given that the various steps of the process do not need to occur within a wholly connected system. The dryer, densifier, receiving container for torrefaction, and cooling system may all be stored separately and set up in independent locations.

Moreover, the torrefaction processes disclosed herein provide an improved quality of torrefied densified biomass as the residual oil on the surface of the torrefied densified biomass reduces the amount of dust and other combustible materials on the biomass' surface. The torrefied densified biomass produced by the exemplary processes is therefore hydrophobic. Accordingly, the exemplary processes produce a torrefied densified product that is easily transportable and shippable as it does not create an explosion hazard. The torrefied densified product can readily be used as a biofuel.

Suitable biomass feedstocks for exemplary processes and products disclosed herein include harvested plant materials exemplified by hardwood trees and softwood trees which may have been processed into chips and/or sawdust and/or pellets, including briquettes, and/or debris and wood waste from wood-processing operations, fibrous annual or perennial crops such as Salix, switchgrass, corn stover, straws produced from harvesting of cereals and/or oilseed crops; or material obtained from waste streams produced from fruit processing plants or vegetable processing plants or cereals processing plants or oilseeds processing plants, or obtained from bagasse from sugar cane. Also suitable are biosolids materials. As used herein, “biosolids” means any solid or semisolid organic material recovered from sewage or wastewater during a sewage treatment process, obtained from municipal sewage treatment processes, or alternatively, may be agricultural wastes from livestock and poultry production.

The use of biomass materials has been limited as biomass generally has a lower energy content and lower energy density compared to traditional fossil fuels. The present disclosure pertains to a densified or pelletized biomass material, including biomass densified into briquettes, as the starting material for torrefaction to increase the starting energy of the raw biomass material (for example, pelletized or otherwise densified biomass, such as briquettes, on a dry basis, can have an energy value of up to 40 lbs/cu ft, as compared to 8 lbs/cu ft for loose biomass material). As understood in the art, densification is a process for increasing the density of the biomass, and many forms of densified biomass are readily available, such as wood pellets and briquettes. Moreover, various procedures for densifying biomass are known in the art and may be employed in the present process, such as, but not limited to, extrusion, briquetting, pelleting and agglomeration.

The term “densified” as used herein means a biomass material that has been compressed to increase its density. The densified biomass material will be understood to be various shaped modules of biomass, with the individual pieces having uniform shapes or non-non-uniform shapes.

The term “pelletized” as used herein means a biomass material that has been compacted or concentrated into pellets, or pressed into briquettes. The pellets may be of any shape such as those exemplified by cubes, pellets, pucks, briquettes, and synthetic logs, wherein the individual pieces have uniform shapes or non-non-uniform shapes. The briquettes may also be of any shape such as exemplified by squares, rectangles, triangles, quadrilaterals, or any regular polygon (such as, for example, pentagons, heptagons, octagons and the like) or alternatively irregular polygons. The individual pieces may have uniform shapes or non-uniform shapes, asymmetric shapes or symmetric shapes.

Hereinafter, the term “densified” shall refer to densified and pelletized materials collectively, including, without limitation, pellets and briquettes, which retain some moisture content, such as, for example, an initial moisture content in the densified biomass and/or biosolids material of at least about 1%. The densified biomass and/or biosolids material may also have an initial moisture content of at least about 1.5%, at least about 2%, at least about 2.5%, at least about 3%, at least about 3.5%, at least about 4%, at least about 4.5%, at least about 5%, at least about 5.5%, at least about 6%, at least about 6.5%, at least about 7%, at least about 7.5%, at least about 8%, at least about 8.5%, at least about 9%, at least about 9.5%, at least about 10%, at least about 11%, at least about 12%, at least about 13%, at least about 14%, at least about 15%, at least about 16%, at least about 17%, at least about 18%, at least about 19%, at least about 20%, or any moisture content therebetween.

The term “densification” used herein shall refer to densification, pelletization and briquetting processes. Furthermore, the densified biomass material may also be referred to as “pellets,” “cubes” or “briquettes” herein. However, it should be understood that the densified biomass referred to herein does not include charcoal briquettes which are already torrefied and therefore cannot be torrefied any further.

As used herein, the term “wet basis” or “As Received Basis” refers to actual values or chemical measurements of a sample of densified biomass material or a sample of torrefied densified biomass, as obtained from an analysis of the sample, and includes, without limitation, moisture content, % ash, % volatile matter, % fixed carbon, % sulphur, % carbon, % nitrogen, % oxygen, and calorific values, such as heat energy values in Btu/lb, GJ/t, Kcal/kg.

As used herein, the term “dry basis” refers to theoretical values that are calculated from the “wet basis” or “as received basis” values to provide results for a sample of densified biomass material or a sample of torrefied densified biomass as if there was no moisture in the sample (i.e., if it was bone dry; total heat value as though dry). Accordingly, as used herein, the term “bone dry basis” refers to the theoretical value for a sample of densified biomass material or a sample of torrefied densified biomass with zero detectable moisture content.

The torrefaction processes of the present disclosure generally pertain to immersion of densified biomass material into a combustible liquid maintained at a temperature in the range of about 160° C. to about 320 C, for a period of time in the range of about 2 minutes to about 120 minutes, for about 5 minutes to about 120 minutes, for about 8 minutes to about 90 minutes, for about 10 minutes to about 60 minutes, for about 12 minutes to about 45 minutes, or for about 15 minutes to about 30 minutes.

As used herein, the term “combustible liquid” means the liquid for contacting and immersing therein the densified biomass material, and then torrefying the densified biomass material in the combustible liquid. The term “combustible liquid” may comprise a hydrocarbon-based oil exemplified by plant-derived oils, marine-derived oils, animal-derived oils, petroleum products and bitumen-based products, and may also comprise a synthetic fuel or a synthetic oil. Suitable plant-derived oils are exemplified by canola oil, linseed oil, sunflower oil, safflower oil, corn oil, peanut oil, palm oil, soybean oil, rapeseed oil, cottonseed oil, palm kernel oil, coconut oil, sesame seed oil, olive oil, and mixtures of plant-derived oils. Suitable animal-derived oils are exemplified by animal tallow, fryer greases, and liver oil among others, and mixtures thereof. Suitable marine-derived oils are exemplified by whale oil, seal oil, fish oil, algal oils, and mixtures of marine-derived oils. Suitable petroleum products are exemplified by synthetic motor oil and engine oils such as exemplified by 5W-30 and 10W-30 engine oils, chainsaw bar oil, chain oil, transmission fluid oils and fluids such as automatic transmission fluids (ATF), hydraulic fluids, gear oils, diesel fuel, paraffin wax, paraffin oil, kerosene, and stove oil, among others, and mixtures thereof. A suitable synthetic fuel or synthetic oil may be produced by a Fischer Tropsch conversion process and is exemplified by pyrolysis oil and the like. The combustible liquid may also be any combinations of plant-derived oils, marine-derived oils, animal-derived oils, petroleum products and synthetic fuels or oils. The combustible liquid used in the present disclosure may further be heatable to a temperature of up to 320° C. As used herein, the combustible liquid is for heating densified biomass material in an oxygen-free environment to torrefy the densified material without igniting it, rather than for the infusion of densified biomass material with the combustible liquid or alternatively, for causing a significant increase in absorption of combustible liquid by densified biomass material.

The products of the torrefaction processes disclosed herein are torrefied/densified biomass and/or biosolids material that retain a portion of the combustible liquid and have a high degree of hydrophobicity. The torrefied densified biomass and/or biosolid obtained from the processes described herein may absorb between about 2% and about 25% w/w combustible liquid during the torrefaction process, or any amount therebetween. For example, without limitation, the amount of combustible liquid absorbed and retained within torrefied densified biomass may be about 2% to about 25% w/w combustible liquid, or any amount therebetween; about 2% to about 24% w/w combustible liquid, or any amount therebetween; about 2% to about 23% w/w combustible liquid, or any amount therebetween; about 2% to about 22% w/w combustible liquid, or any amount therebetween; about 2% to about 21% w/w combustible liquid, or any amount therebetween; about 2% to about 20% w/w combustible liquid, or any amount therebetween; about 2% to about 19% w/w combustible liquid, or any amount therebetween; about 2% to about 18% w/w combustible liquid, or any amount therebetween; about 2% to about 17% w/w combustible liquid, or any amount therebetween; such as, for example, 3% w/w combustible liquid, 4% w/w combustible liquid, 5% w/w combustible liquid, 6% w/w combustible liquid, 7% w/w combustible liquid, 8% w/w combustible liquid, 9% w/w combustible liquid, 10% w/w combustible liquid, 11% w/w combustible liquid, 12% w/w combustible liquid, 13% w/w combustible liquid, 14% w/w combustible liquid, 15% w/w combustible liquid, 16% w/w combustible liquid, or any amount therebetween.

Those skilled in the art would understand that the biomass and/or biosolid materials of the present disclosure have a range of heat energy values. Those skilled in the art would know that exemplary energy values of the densified biomass and/or biosolids may range from about 4,300 BTU per pound to about 12,800 BTU per pound, depending on the feedstock and the moisture content of the feedstock. For example, a skilled person in the art would known that wood generally has an energy content of about 6,400 BTU per pound with 20% moisture (air dry basis) to about 7,600 to about 9,600 BTU per pound on a bone dry basis (or about 15 GJ/t with 20% moisture to about 18-22 GJ/t on a bone dry basis), and that agricultural residues, such as switchgrass, have an energy content of about 4,300 BTU per pound to about 7,300 BTU per pound (or about 10-17 GJ/t), depending on the moisture content of the agricultural residue. In addition, those skilled in the art would known that charcoal has an energy content of about 12,800 BTU per pound. Accordingly, a skilled person would appreciate that the range of heat energy values following torrefaction can also vary, with those biomass and/or biosolid material having a lower initial heat energy value producing an end product having a lower heat energy value compared to a biomass and/or biosolid material having a higher initial heat energy value. In addition, as described herein, different factors can be varied, such as, without limitation, the density of the densified biomass, the temperature of the combustible liquid, the submersion time of the densified biomass in the combustible liquid, and the type of combustible liquid used, to obtain a particular heat energy value for a torrefied densified biomass and/or biosolid material of the present disclosure.

The torrefied densified biomass and/or biosolid of the present disclosure may accordingly have a heat energy value of about 6,000 BTU per pound on a bone dry basis to about 13,000 BTU per pound on a bone dry basis, or any heat energy value therebetween, for example, from about 6,000 BTU per pound on a bone dry basis to about 12,000 BTU per pound on a bone dry basis, or any heat energy value therebetween; from about 6,000 BTU per pound on a bone dry basis to about 11,000 BTU per pound on a bone dry basis, or any heat energy value therebetween; from about 6,000 BTU per pound on a bone dry basis to about 10,000 BTU per pound on a bone dry basis, or any heat energy value therebetween; from about 6,000 BTU per pound on a bone dry basis to about 9,000 BTU per pound on a bone dry basis, or any heat energy value therebetween; from about 9,000 BTU per pound on a bone dry basis to about 13,000 BTU per pound on a bone dry basis, or any heat energy value therebetween, such as, for example, about 9,500 BTU per pound on a bone dry basis; about 10,000 BTU per pound on a bone dry basis; about 10,500 BTU per pound on a bone dry basis; about 11,000 BTU per pound on a bone dry basis; about 11,500 BTU per pound on a bone dry basis; about 12,000 BTU per pound on a bone dry basis; about 12,500 BTU per pound on a bone dry basis on a bone dry basis; about 13,000 BTU per pound, or any heat energy value therebetween. The heat energy value may also be expressed in terms of gigajoules per metric tonne (GJ/t). The torrefied densified biomass and/or biosolid may therefore comprise a heat energy value of about 22 GJ/t on a bone dry basis to about 27 GJ/t on a bone dry basis, or any heat energy value therebetween, for example, from about 22 GJ/t on a bone dry basis to about 26.5 GJ/t on a bone dry basis or any heat energy value therebetween; from about 22 GJ/tt on a bone dry basis to about 26 GJ/t on a bone dry basis or any heat energy value therebetween; from about 22 GJ/t on a bone dry basis to about 26 GJ/t on a bone dry basis or any heat energy value therebetween; from about 22 GJ/t on a bone dry basis to about 25 GJ/t on a bone dry basis or any heat energy value therebetween; from about 22 GJ/t on a bone dry basis to about 24 GJ/t on a bone dry basis or any heat energy value therebetween; or from about 22 GJ/t on a bone dry basis to about 23 GJ/t on a bone dry basis or any heat energy value therebetween.

Furthermore, the torrefied densified biomass disclosed herein may have a carbon content of about 50 carbon % on a bone dry basis to about 65 carbon % on a bone dry basis, or any amount therebetween. For example, without limitation, the carbon content of the torrefied densified biomass may be about 51 carbon % on a bone dry basis, 52 carbon % on a bone dry basis, 53 carbon % on a bone dry basis, 54 carbon % on a bone dry basis, 55 carbon % on a bone dry basis, 56 carbon % on a bone dry basis, 57 carbon % on a bone dry basis, 58 carbon % on a bone dry basis, 59 carbon % on a bone dry basis, 60 carbon % on a bone dry basis, 61 carbon % on a bone dry basis, 62 carbon % on a bone dry basis, 63 carbon % on a bone dry basis, 64 carbon % on a bone dry basis, 65 carbon % on a bone dry basis, or any amount therebetween.

The torrefied end products are easily grindable into particulate and/or powdered forms that are particularly suitable for use as fuels for generation of power and/or heat. Furthermore, the torrefied material is easily transported and stored and are hydrophobic in nature.

A schematic flowchart is shown in FIG. 1 that illustrates an exemplary process of the present disclosure for preparing a torrefied densified biomass and/or biosolid material having a higher energy density value as compared to a non-torrefied biomass material. In this embodiment, the starting raw biomass material 2 is not densified and the process for preparing the torrefied densified biomass material includes initial steps of drying and densifying raw biomass material 2 into densified biomass material 20. For the torrefaction process, a receiving container 10 is filled with a combustible liquid 12, as described above. Combustible liquid 12 is heated up to a temperature in a range of about 160° C. to about 320° C., and densified biomass material 20 is immersed in the hot combustible liquid 12 in receiving container 10. Densified biomass material 20 is completely submerged in the hot combustible liquid 12 to create an “oxygen-free” environment. The hot combustible liquid 12 may be maintained at a temperature in a range of about 160° C. to about 320° C., or any temperature therebetween. Alternatively, the temperature of the hot combustible liquid 12 may be varied during the process between about 160° C. and about 320° C. Whether combustible liquid 12 is maintained at a certain temperature or varied during the process, the temperature of densified biomass 20 is increased from its initial temperature to a temperature in a range of about 160° C. to about 320° C., or any temperature therebetween. During this heating process, most of the moisture is driven out of densified biomass 20 and densified biomass 20 takes in heat energy in an endothermic reaction. Densified biomass 20 also undergoes chemical and structural changes and expels some VOCs contained within densified biomass 20. The resulting torrefied densified biomass 30 is removed from receiving container 10 and cooled in a cooling system 32.

Any type of densification process described in the art may be used in the present process to produce a densified biomass material 20 for torrefaction. For example, densifier 5 may be a pelletizer, as known in the art, and may comprise an extrusion process for producing pellets (including, for example, a pellet mill extruder, a screw extruder), a hammer mill, a piston press, a wheel press or a briquetter for pressing biomass into a briquette, or may involve agglomeration. Densification may also include the addition of pellet binders during the densification process to ensure that pellet quality is maintained. The densification process may also involve pre-heating and melting of the raw biomass material 2 through mechanical action and friction and heat, resulting in a significant reduction of volume, elimination of some moisture and air, and an increase in temperature of the biomass. After raw biomass material 2 is densified, the resulting densified biomass 20 proceeds through the torrefaction process.

The present disclosure also provides that a dryer 7 may be used to reduce the moisture content in raw biomass material 2 before and/or after densification and before torrefaction. Those skilled in the art will appreciate that any dryer known in the art may be used, such as, for example, the Altentech™ Biovertidryer™ (available from Altentech™ Power Inc., Vancouver, BC, Canada), together with densifier 5. The drying process may be useful in further heating of the densified biomass material 20 prior to torrefaction, thereby increasing the efficiency of the torrefaction process.

Dryer 7 and/or densifier 5 (or a combined dryer/densifier) may be located near receiving container 10 containing combustible liquid 12. With such an arrangement, densified biomass 20 may be directly transferred from densifier 5 and/or dryer 7 (or a combined dryer/densifier) to receiving container 10 without cooling the densified biomass 20 in-between. Those skilled in the art will appreciate that through the action of densifiers and melding raw material into a compact product, densifiers produce significant heat, thus resulting in a heated densified product. Dryers known in the art also use significant heat to extract moisture from raw biomass, thus further increasing the heat of a densified product. Accordingly, densified biomass 20 is at a temperature greater than ambient temperature immediately following densification and/or drying. Transfer of densified biomass 20 directly from densifier 5 and/or dryer 7 (or a combined dryer/densifier) to receiving container 10 may assist in further reducing the costs of torrefying biomass and increase the efficiency of the process as the initial temperature of densified biomass 20 entering combustible liquid 12 is higher than ambient temperature. Alternatively, the densified biomass 20 may be cooled before transferring from densifier 5 and/or dryer 7 (or a combined dryer/densifier) to receiving container 10.

Importantly, the present disclosure provides for densification prior to contact with any type of oil; that is, raw biomass material 2 is densified prior to contacting any oil of the combustible liquid (or densified biomass 20 is used as the starting material). Those skilled in the art will appreciate that fat and oil may interfere with steam absorption and reduce pelletability. Fats and oils may be used during pelleting, but generally to lubricate the die and ensure a smooth start-up after the die cools off. Oil is mixed with raw biomaterial following densification to purge the die prior to shutdown and is not for actual pelletization of the biomass. In fact, oil-saturated biomass from a pellet press may be saved following pelletization for reuse in a subsequent shutdown sequence (see, for example, Kofman, P D. “The production of wood pellets.” Coford Connects, Processing/Products No. 10, pages 1-6, 2012). Accordingly, the present disclosure provides an improved torrefied densified biomass as compared to prior art processes which coat biomass with oil prior to densification.

Receiving container 10 may be any type of container that can be heated to a temperature of up to about 320° C. and can hold hot combustible liquid at a temperature of up to about 320° C. for extended periods of time. It is, therefore, understood that receiving container 10 be of a simple design. For example, receiving container 10 may be a commercially available deep fryer exemplified by a PITCO® fryer (PITCO is a registered trademark of Pitco Frialator, Inc., Burlington, Vt., U.S.A.), a VULCAN® fryer (VULCAN is a registered trademark of Vulcan-Hart Corporation, Chicago, Ill., U.S.A.), a FRYMASTER® (FRYMASTER is a registered trademark of Frymaster LLC, Shreveport, La., U.S.A.), a Southbend fryer, or a DEAN® fryer (DEAN is a registered trademark of Frymaster LLC, Shreveport, La., U.S.A.); or, receiving container 10 may be any sized drum, tank, pot or other container that can be heated directly from below to a temperature of about 320° C., and that can hold a combustible liquid at a temperature of about 320° C. for extended periods of time. Receiving container 10 is also sufficiently sized to receive the desired amount of densified biomass 20 together with the combustible liquid 12.

Combustible liquid 12 may be heated using a heat source directly below receiving container 10 or using an external heat source to heat the combustible liquid 12, which can be transferred into receiving container 10 once it reaches its operating temperature. The external heat source may be, for example, a nuclear reactor with modest thermal output, a furnace that burns coal or natural gas, or a portion of the produced biocoal, with or without additional heat exchangers.

It is understood that, to minimize costs of the exemplary processes described herein, the size of receiving container 10 and the amount of combustible liquid 12 used may be limited to a size and amount that is sufficient to completely submerge the particular quantity of densified biomass 20 to be torrefied. Moreover, smaller amounts of combustible liquid may also be used if densified biomass 20 comprises smaller-sized pellets or briquettes. Accordingly, the exemplary processes described herein may be varied in order to make the process more efficient and less costly, and can be adjusted according to a user's needs.

As described above, combustible liquid 12 may be heated to a temperature in a range of about 160° C. to about 320° C., or any temperature therebetween, and the combustible liquid 12 may be maintained at this temperature during the torrefaction process. By way of further example, the temperature that combustible liquid 12 may be heated to and maintained at can vary in a range of between about 180° C. to about 320° C., or any temperature therebetween; between about 180° C. to about 300° C., or any temperature therebetween; between about 200° C. to about 320° C., or any temperature therebetween; between about 200° C. and about 310° C., or any temperature therebetween; between about 200° C. and about 300° C., or any temperature therebetween; between about 200° C. and about 290° C., or any temperature therebetween; between about 200° C. and about 280° C., or any temperature therebetween; between about 200° C. and about 270° C., or any temperature therebetween; between about 200° C. and about 260° C., or any temperature therebetween; between about 200° C. and about 250° C., or any temperature therebetween; between about 200° C. and about 240° C., or any temperature therebetween; between about 220° C. and about 300° C., or any temperature therebetween; between about 220° C. and about 290° C., or any temperature therebetween; between about 220° C. and about 280° C., or any temperature therebetween; between about 220° C. and about 270° C., or any temperature therebetween; between about 220° C. and about 260° C., or any temperature therebetween; between about 220° C. and about 250° C., or any temperature therebetween; between about 220° C. and about 240° C., or any temperature therebetween; or can be about 162° C., 165° C., 168° C., 170° C., 172° C., 175° C., 178° C., 180° C., 181° C., 182° C., 183° C., 184° C., 185° C., 186° C., 187° C., 188° C., 189° C., 190° C., 191° C., 192° C., 193° C., 194° C., 195° C., 196° C., 197° C., 198° C., 199° C., 200° C., 201° C., 202° C., 203° C., 204° C., 205° C., 206° C., 207° C., 208° C., 209° C., 210° C., 211° C., 212° C., 213° C., 214° C., 215° C., 216° C., 217° C., 218° C., 219° C., 220° C., 221° C., 222° C., 223° C., 224° C., 225° C., 226° C., 227° C., 228° C., 229° C., 230° C., 231° C., 232° C., 233° C., 234° C., 235° C., 236° C., 237° C., 238° C., 239° C., 240° C., 241° C., 242° C., 243° C., 244° C., 245° C., 248° C., 250° C., 252° C., 255° C., 258° C., 260° C., 262° C., 264° C., 266° C., 268° C., 270° C., 272° C., 274° C., 276° C., 278° C., 280° C., 282° C., 284° C., 286° C., 288° C., 290° C., 292° C., 294° C., 296° C., 298° C., 300° C., 302° C., 304° C., 306° C., 308° C., 310° C., 312° C., 314° C., 316° C., 318° C., 320° C., or any temperature therebetween.

It is further contemplated that the temperature of combustible liquid 12 may be heated in a step-wise fashion. This step-wise heating may be done in a single receiving container 10 such that the same combustible liquid is heated to an initial temperature and then heated to an increased temperature for torrefying densified biomass 20. Using a single receiving container reduces any costs that would be associated with transferring densified biomass 20 between multiple receiving containers 10, using multiple volumes of combustible liquid 12, and heating multiple volumes of combustible liquid 12.

Combustible liquid 12 may be heated to an initial lower temperature prior to loading with densified biomass 20. Once densified biomass 20 is submerged within combustible liquid 12 at the lower initial temperature for a certain period of time, combustible liquid 12 may be heated to a higher temperature for torrefaction. Such a step-wise heating of combustible liquid 12 and densified biomass 20 may result in a more efficient and less costly process, as the initial lower temperature may be used for heating densified biomass 20 from its starting temperature to a higher temperature and for releasing the majority of the moisture from densified biomass 20; the higher temperature, on the other hand, may be used for a shorter period of time for torrefying densified biomass 20. Accordingly, less energy may be required as a higher temperature would be required for a shorter period of time. By way of example, combustible liquid 12 may be initially heated to a temperature in a range of about 110° C. to about 200° C., or any temperature therebetween, such as, but not limited to, about 110° C., 112° C., 114° C., 116° C., 118° C., 120° C., 122° C., 124° C., 126° C., 128° C., 130° C., 132° C., 134° C., 136° C., 138° C., 140° C., 142° C., 144° C., 148° C., 150° C., 151° C., 152° C., 153° C., 154° C., 155° C., 156° C., 157° C., 158° C., 159° C., 160° C., 161° C., 162° C., 163° C., 164° C., 165° C., 166° C., 167° C., 168° C., 169° C., 170° C., 171° C., 172° C., 173° C., 174° C., 175° C., 176° C., 177° C., 178° C., 179° C., 180° C., 182° C., 185° C., 188° C., 190° C., 192° C., 195° C., 198° C., 200° C., or any temperature therebetween. Densified biomass 20 may be submerged within the lower temperature for about 2 minutes to about 30 minutes, or any amount of time therebetween, such as 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15, 15.5, 16, 16.5, 17, 17.5, 18, 18.5, 19, 19.5, 20, 20.5, 21, 21.5, 22, 22.5, 23, 23.5, 24, 24.5, 25, 25.5, 26, 26.5, 27, 27.5, 28, 28.5, 29, 29.5, 30 minutes, or any amount of time therebetween. Following the initial period of the heat treatment, combustible liquid 12, containing densified biomass 20 submerged therein, may be further heated to a temperature of about 180° C. to about 320° C., or any temperature therebetween, such as, but not limited to, about 181° C., 182° C., 183° C., 184° C., 185° C., 186° C., 187° C., 188° C., 189° C., 190° C., 191° C., 192° C., 193° C., 194° C., 195° C., 196° C., 197° C., 198° C., 199° C., 200° C., 201° C., 202° C., 203° C., 204° C., 205° C., 206° C., 207° C., 208° C., 209° C., 210° C., 211° C., 212° C., 213° C., 214° C., 215° C., 216° C., 217° C., 218° C., 219° C., 220° C., 221° C., 222° C., 223° C., 224° C., 225° C., 226° C., 227° C., 228° C., 229° C., 230° C., 231° C., 232° C., 233° C., 234° C., 235° C., 236° C., 237° C., 238° C., 239° C., 240° C., 241° C., 242° C., 243° C., 244° C., 245° C., 248° C., 250° C., 252° C., 255° C., 258° C., 260° C., 262° C., 264° C., 266° C., 268° C., 270° C., 272° C., 274° C., 276° C., 278° C., 280° C., 282° C., 284° C., 286° C., 288° C., 290° C., 292° C., 294° C., 296° C., 298° C., 300° C., 302° C., 304° C., 306° C., 308° C., 310° C., 312° C., 314° C., 316° C., 318° C., 320° C., or any temperature therebetween. Densified biomass 20 may be torrefied in the higher temperature for about 2 minutes to about 60 minutes, or any amount of time therebetween, such as 2.5 minutes, 3 minutes, 3.5 minutes, 4 minutes, 4.5 minutes, 5 minutes, 5.5 minutes, 6 minutes, 6.5 minutes, 7 minutes, 7.5 minutes, 8 minutes, 8.5 minutes, 9 minutes, 9.5 minutes, 10 minutes, 10.5 minutes, 11 minutes, 11.5 minutes, 12 minutes, 12.5 minutes, 13 minutes, 13.5 minutes, 14 minutes, 14.5 minutes, 15 minutes, 15.5 minutes, 16 minutes, 16.5 minutes, 17 minutes, 17.5 minutes, 18 minutes, 18.5 minutes, 19 minutes, 19.5 minutes, 20 minutes, 20.5 minutes, 21 minutes, 21.5 minutes, 22 minutes, 22.5 minutes, 23 minutes, 23.5 minutes, 24 minutes, 24.5 minutes, 25 minutes, 25.5 minutes, 26 minutes, 26.5 minutes, 27 minutes, 27.5 minutes, 28 minutes, 28.5 minutes, 29 minutes, 29.5 minutes, 30 minutes, 32 minutes, 34 minutes, 36 minutes, 38 minutes, 40 minutes, 42 minutes, 44 minutes, 46 minutes, 48 minutes, 50 minutes, 52 minutes, 54 minutes, 56 minutes, 58 minutes, 60 minutes, or any amount of time therebetween.

The present disclosure contemplates densified biomass material 20 being loaded directly into receiving container 10. Alternatively, densified biomass material 20 may be loaded into a holder 22, which is then immersed within receiving container 10.

To allow direct contact of densified biomass material 20 with combustible liquid 12 when holder 22 is used in the exemplary process, holder 22 may be any type of holder that can fit the densified feedstock to be torrefied and fit within receiving container 10 and that is porous to combustible liquid 12 in receiving container 10, but not to the densified feedstock. As such, holder 22 prevents densified biomass 20 or torrefied densified biomass 30 contained in holder 22 from falling outside holder 22, while allowing combustible liquid 12 to flow through holder 22 to heat and torrefy densified biomass 20. For example, without limitation, holder 22 may be a wire-strainer type basket or wire mesh basket or other type of basket with perforations within its outer walls. It is understood that holder 22 can withstand the heat of combustible liquid 12 and can be heated to a temperature of up to about 320° C. for extended periods of time.

Given that densified biomass 20 is completely submerged within combustible liquid 12, which is heated to a temperature in a range of about 160° C. to about 280° C., or any temperature therebetween, densified biomass 20 is heated up to a temperature in a range of about 160° C. to about 320° C., or any temperature therebetween, by completion of the torrefaction process. By way of further example, the temperature of torrefied densified biomass 30 at the end of the exemplary process can vary in a range of between about 180° C. to about 320° C., or any temperature therebetween; between about 180° C. to about 300° C., or any temperature therebetween; between about 200° C. and about 320° C., or any temperature therebetween; between about 200° C. and about 310° C., or any temperature therebetween; between about 200° C. and about 300° C., or any temperature therebetween; between about 200° C. and about 290° C., or any temperature therebetween; between about 200° C. and about 280° C., or any temperature therebetween; between about 200° C. and about 270° C., or any temperature therebetween; between about 200° C. and about 260° C., or any temperature therebetween; between about 200° C. and about 250° C., or any temperature therebetween; between about 200° C. and about 240° C., or any temperature therebetween; between about 220° C. and about 300° C., or any temperature therebetween; between about 220° C. and about 290° C., or any temperature therebetween; between about 220° C. and about 280° C., or any temperature therebetween; between about 220° C. and about 270° C., or any temperature therebetween; between about 220° C. and about 260° C., or any temperature therebetween; between about 220° C. and about 250° C., or any temperature therebetween; between about 220° C. and about 240° C., or any temperature therebetween; or can be about 162° C., 165° C., 168° C., 170° C., 172° C., 175° C., 178° C., 180° C., 181° C., 182° C., 183° C., 184° C., 185° C., 186° C., 187° C., 188° C., 189° C., 190° C., 191° C., 192° C., 193° C., 194° C., 195° C., 196° C., 197° C., 198° C., 199° C., 200° C., 201° C., 202° C., 203° C., 204° C., 205° C., 206° C., 207° C., 208° C., 209° C., 210° C., 211° C., 212° C., 213° C., 214° C., 215° C., 216° C., 217° C., 218° C., 219° C., 220° C., 221° C., 222° C., 223° C., 224° C., 225° C., 226° C., 227° C., 228° C., 229° C., 230° C., 231° C., 232° C., 233° C., 234° C., 235° C., 236° C., 237° C., 238° C., 239° C., 240° C., 241° C., 242° C., 243° C., 244° C., 245° C., 248° C., 250° C., 252° C., 255° C., 258° C., 260° C., 262° C., 264° C., 266° C., 268° C., 270° C., 272° C., 274° C., 276° C., 278° C., 280° C., 282° C., 284° C., 286° C., 288° C., 290° C., 292° C., 294° C., 296° C., 298° C., 300° C., 302° C., 304° C., 306° C., 308° C., 310° C., 312° C., 314° C., 316° C., 318° C., 320° C., or any temperature therebetween. One of skill in the art will appreciate that the temperature of torrefied densified biomass 30 at the end of the torrefaction process, prior to removal from receiving container 10, will depend on the starting raw material, the time that densified biomass 20 is submerged within heated combustible liquid 12, the type of combustible liquid 12 used, and the temperature of combustible liquid 12.

During submersion of the densified biomass 20 within combustible liquid 12 and during the torrefaction process, densified biomass 20 absorbs combustible liquid 12 such that the resulting torrefied densified biomass 30 retains some absorbed combustible liquid 12. The amount of combustible liquid 12 absorbed by the densified biomass 20 and retained in the post-torrefaction densified biomass 30 depends upon several different factors including, for example, the physico-chemical properties of the starting feedstock, the density of the densified biomass 20, the amount of starting feedstock, the submersion time of the densified biomass 20 in the combustible liquid 12, the combustible liquid 12 used, and the temperature of the combustible liquid 12. As will be illustrated and described further in Examples 4 and 5, the absorption of combustible liquid 12 by densified biomass 20 does not occur at a constant rate. Combustible liquid 12 is initially absorbed at a higher rate compared to absorption rates occurring later in the torrefaction process. For example, the rate of absorption at the beginning of the torrefaction process may be between about 9% to about 18% w/w combustible liquid per mass of the input bone dry densified biomass, or any rate therebetween such as, without limitation, about 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, or any rate therebetween. Following the initial higher rate of absorption of the combustible liquid 12, the absorption rate decreases and remains at a fairly constant rate for a period of time during the torrefaction process. This lower rate occurring during the mid-portion of the torrefaction process may be between about 6% to about 14% w/w combustible liquid per mass of the input bone dry densified biomass, or any rate therebetween such as, without limitation, about 7%, 8%, 9%, 10%, 11%, 12%, 13%, or any rate therebetween. It was discovered that if densified biomass 20 is submersed in combustible liquid 12 for longer periods of time, rate of absorption of the combustible liquid 12 by the densified biomass 20 decreases substantially. For example, the rate of absorption during later periods of the torrefaction process may be between about 2% to about 10% w/w combustible liquid per mass of the densified biomass of the initial rate of absorption, or any rate therebetween such as, without limitation, about 3%, 4%, 5%, 6%, 7%, 8%, 9%, or any rate therebetween. The rate of absorption of combustible liquid 12 by densified biomass 20 may also fall to a negative rate if the densified biomass 20 is submersed within combustible liquid 12 for an extensive period of time. It appears that some of the combustible liquid 12 absorbed by the densified biomass 20 during the earlier stages of the torrefaction process may be released from torrefied densified biomass 30 as the torrefaction process is maintained for increasingly extended periods of time. As disclosed above, the time ranges during which the rate of absorption occurs at higher rates, constant rates, lower rates of absorption, or negative rates; i.e., loss of the combustible liquid by torrefied densified biomass 20 will depend on one or more of the temperature of the combustible liquid 12, the physico-chemical properties of the starting feedstock, the amount of starting feedstock, the combustible liquid 12, the type of combustible liquid 12 used, and other factors. However, it is apparent that the rate of absorption of combustible liquid 12 by densified biomass 20 varies during the torrefaction process, such that, the rate of absorption is initially higher, subsequently diminishing over time and, eventually, potentially resulting in loss of some combustible liquid 12 absorbed earlier in the process. Based on these findings, the duration of the torrefaction process may be varied to obtain torrefied densified biomass 30 with different amounts of combustible liquid 12 absorbed therein.

The amount of time that densified biomass 20 is submerged within combustible liquid 12 may vary depending on different variables, such as for example, the properties of the starting feedstock, including its size and initial temperature, the size of receiving container 10, the amount of the starting feedstock for torrefaction, the amount of combustible liquid 12, the type of combustible liquid 12, and the physico-chemical properties of torrefied densified biomass 30 that is desired, such as the mass, amount of oil contained therein, carbon content, hydrophobic nature and the heat energy value (BTU per pound or GJ/t). By way of example, the submersion time of densified biomass 20 in combustible liquid 12 may vary from about 2 minutes to about 120 minutes, or any amount of time therebetween; such as for example, from about 2 minutes to about 110 minutes, or any amount of time therebetween; from about 2 minutes to about 100 minutes, or any amount of time therebetween; from about 2 minutes to about 90 minutes, or any amount of time therebetween; from about 2 minutes to about 80 minutes, or any amount of time therebetween; from about 2 minutes to about 75 minutes, or any amount of time therebetween; from about 2 minutes to about 70 minutes, or any amount of time therebetween; from about 2 minutes to about 65 minutes, or any amount of time therebetween; from about 2 minutes to about 60 minutes, or any amount of time therebetween; from about 2 minutes to about 55 minutes, or any amount of time therebetween; from about 2 minutes to about 50 minutes, or any amount of time therebetween; from about 2 minutes to about 45 minutes, or any amount of time therebetween; from about 2 minutes to about 40 minutes, or any amount of time therebetween; from about 2 minutes to about 35 minutes, or any amount of time therebetween; from about 2 minutes to about 30 minutes, or any amount of time therebetween; from about 2 minutes to about 25 minutes, or any amount of time therebetween; from about 2 minutes to about 20 minutes, or any amount of time therebetween; from about 5 minutes to about 60 minutes, or any amount of time therebetween; from about 5 minutes to about 55 minutes, or any amount of time therebetween; from about 5 minutes to about 50 minutes, or any amount of time therebetween; from about 5 minutes to about 45 minutes, or any amount of time therebetween; from about 5 minutes to about 40 minutes, or any amount of time therebetween; from about 5 minutes to about 35 minutes, or any amount of time therebetween; from about 5 minutes to about 30 minutes, or any amount of time therebetween; from about 5 minutes to about 25 minutes, or any amount of time therebetween; from about 5 minutes to about 20 minutes, or any amount of time therebetween; from about 5 minutes to about 15 minutes, or any amount of time therebetween; or about 2 minutes, 2.5 minutes, 3 minutes, 3.5 minutes, 4 minutes, 4.5 minutes, 5 minutes, 5.5 minutes, 6 minutes, 6.5 minutes, 7 minutes, 7.5 minutes, 8 minutes, 8.5 minutes, 9 minutes, 9.5 minutes, 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes, 15 minutes, 16 minutes, 17 minutes, 18 minutes, 19 minutes, 20 minutes, 21 minutes, 22 minutes, 23 minutes, 24 minutes, 25 minutes, 26 minutes, 27 minutes, 28 minutes, 29 minutes, 30 minutes, 32 minutes, 34 minutes, 36 minutes, 38 minutes, 40 minutes, 42 minutes, 44 minutes, 46 minutes, 48 minutes, 50 minutes, 52 minutes, 54 minutes, 56 minutes, 58 minutes, 60 minutes, or any amount of time therebetween.

Following submersion of densified biomass 20 in combustible liquid 12 for the time desired, torrefied densified biomass 30 is retrieved from receiving container 10. If densified biomass 20 is directly loaded into receiving container 10, any type of utensil may be used to retrieve torrefied densified biomass 30 from receiving container 10. Preferably, the utensil used will limit the amount of combustible liquid 12 that is removed with torrefied densified biomass 30, as the present process contemplates reuse of the combustible liquid 12. By way of example, the utensil may be a perforated-type of utensil, such as, without limitation, a slotted spoon, or may be a pair of forceps, tweezers, tongs, or the like. If holder 22 is used to load densified biomass 20 into receiving container 10, then holder 22, along with torrefied densified biomass 30 contained therein, is removed from receiving container 10.

To minimize the amount of combustible liquid 12 that is removed along with torrefied densified biomass 30, and thereby, be able to reuse as much combustible liquid 12 as possible, torrefied densified biomass 30, or holder 22 containing torrefied densified biomass 30, may be held above receiving container 10 for about 15 seconds to about 150 seconds, or any time therebetween, to drain torrefied densified biomass 30 of combustible liquid 12 and drip combustible liquid 12 into receiving container 10 for reuse. For example, without limitation, torrefied densified biomass 30, or holder 22, may be held above receiving container 10 for about 15 seconds, 16 seconds, 17 seconds, 18 seconds, 19 seconds, 20 seconds, 21 seconds, 22 seconds, 23 seconds, 24 seconds, 25 seconds, 26 seconds, 27 seconds, 28 seconds, 29 seconds, 30 seconds, 31 seconds, 32 seconds, 33 seconds, 34 seconds, 35 seconds, 36 seconds, 37 seconds, 38 seconds, 39 seconds, 40 seconds, 41 seconds, 42 seconds, 43 seconds, 44 seconds, 45 seconds, 48 seconds, 50 seconds, 52 seconds, 55 seconds, 58 seconds, 60 seconds, 65 seconds, 70 seconds, 75 seconds, 80 seconds, 85 seconds, 90 seconds, 95 seconds, 100 seconds, 105 seconds, 110 seconds, 115 seconds, 120 seconds, 125 seconds, 130 seconds, 135 seconds, 140 seconds, 145 seconds, 150 seconds, or any amount of time therebetween. If time permits, a skilled person will appreciate that torrefied densified biomass 30, or holder 22, may be held above receiving container 10 for longer periods of time to maximize the amount combustible liquid 12 retained in receiving container 10. Accordingly, the exemplary process described herein maximizes retention of oil or combustible liquid 12 in receiving container 10, rather than absorption into the torrefied densified biomass, to reduce costs of replenishing the oil for torrefaction with each cycle.

The exemplary process further provides a cooling step, wherein torrefied densified biomass 30 is placed in a cooling system 32 to cool torrefied densified biomass 30 to near-ambient temperatures until it can be safely handled for packaging, storing, use, or transportation. Cooling system 32 may be, for example, a cold water bath with the water at a sufficiently cold temperature to cool torrefied densified biomass 30 to a near-ambient temperature. For example, without limitation, the cold water bath may have water at a temperature of about 0° C. to about 100° C., or any temperature therebetween, such as, without limitation, about 0° C., 2° C., 4° C., 6° C., 8° C., 10° C., 12° C., 14° C., 16° C., 18° C., 20° C., 22° C., 24° C., 26° C., 28° C., 30° C., 32° C., 34° C., 36° C., 38° C., 40° C., 42° C., 44° C., 46° C., 48° C., 50° C., 52° C., 54° C., 56° C., 58° C., 60° C., 62° C., 64° C., 68° C., 70° C., 72° C., 74° C., 76° C., 78° C., 80° C., 82° C., 84° C., 86° C., 88° C., 90° C., 92° C., 94° C., 96° C., 98° C., 100° C., or any temperature therebetween. Torrefied densified biomass 30 may be immersed in the cold water bath for about 0.5 to about 20 minutes, or any amount of time therebetween, such as, without limitation, 0.5 minutes, 1 minutes, 2 minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes, 15 minutes, 16 minutes, 17 minutes, 18 minutes, 19 minutes, 20 minutes, or any amount of time therebetween. It is understood that torrefied densified biomass 30 may be left in the cold water bath for longer periods of time, and the amount of time will vary depending on a number of factors, such as, the size of torrefied densified biomass 30, the size and temperature of the cold water bath, the starting temperature of torrefied densified biomass 30 (i.e., its temperature at the point it is retrieved from receiving container 10), and the desired temperature of the torrefied densified biomass 30 for handling. The torrefaction process produces a hydrophobic torrefied biomass. Accordingly, cooling torrefied densified biomass 30 in water does not generally result in significant absorption of water or an increase in weight of the torrefied densified biomass 30. However, the amount of water absorbed by the torrefied densified biomass 30 is relative to the amount of time that densified biomass 20 is retained in hot combustible liquid 12 and the temperature of combustible liquid 12. It is further contemplated that torrefied densified biomass may also be cooled in a step-wise fashion, such that an initial cold water bath with water at a temperature between about 50° C. to about 100° C., or any temperature therebetween, is used, followed by a cold water bath at a temperature between about 0° C. to about 50° C., or any temperature therebetween. This step-wise cooling may increase the efficiency of the cooling step and thereby reduce costs and increase throughput.

Torrefied densified biomass 30 may be placed directly into cooling system 32 without holder 22, or holder 22 containing torrefied densified biomass 30 therein may be placed into cooling system 32. Accordingly, torrefied densified biomass 30 may be extracted from the cold water bath in a manner similar to how it is retrieved from receiving container 10, as described above. The use of a cooling system 32, such as a cold water bath, does not require significant energy or resources to operate, thus providing a further cost-savings and efficiency. Furthermore, collection of any steam expelled during the cooling process may also be used in other stages of the process, as described in more detail below.

Further, as mentioned above, the amount of combustible liquid 12 absorbed and retained within torrefied densified biomass 30 may be varied depending on various factors, including the duration of the torrefaction process and submersion of densified biomass 20 within combustible liquid 12, the temperature of the combustible liquid 12, the properties of the starting feedstock, the amount of the starting feedstock, and the type of combustible liquid 12 used, amongst other factors. Consequently, the heat energy value of torrefied densified biomass 30 may also be tailored by adjusting the variables, such as the duration of the torrefaction process and submersion of densified biomass 20 within combustible liquid 12, the temperature of the combustible liquid 12, the properties of the starting feedstock, the amount of the starting feedstock, and the combustible liquid 12 used, amongst other factors.

Another exemplary process of the present disclosure is shown in FIG. 2. In this embodiment, the starting raw biomass material is densified such that no densification step is required prior to immersion in combustible liquid 12. Densified biomass 20 can be any biomass material that is readily commercially available as a densified biomass product. Other than the initial starting material, the remaining steps of this embodiment are the same as those described in relation to FIG. 1.

As shown in FIGS. 1 and 2, a gas collection and condenser system 40 comprising a plurality of pipes may be used for connecting to receiving container 10 and cooling system 32. System 40 may comprise a series of inlets and outlets, with an inlet disposed in each of receiving container 10 and cooling system 32 above the liquid level of combustible liquid 12 and the cooling water in cooling system 32, respectively. The inlet disposed in receiving container 10 is for collecting VOCs and steam, and the inlet disposed in cooling system 32 is for collecting steam upon cooling of the torrefied densified biomass. An inlet may also be disposed in densifier 5 or dryer 7 (or a combined dryer/densifier) to capture any steam that is expelled during the densification and drying processes. The mixture of VOCs and steam may be further processed and condensed in system 40. The mixture may be separated into bio-liquids and gases that contain CO, CO₂and perhaps also H₂, CH₄and other trace volatiles. The gases may be burnt to help heat the combustible liquid 12 in receiving container 10 or to provide energy for dryer 7 or densifier 5 (or a combined dryer/densifier). If the gases are used in the exemplary processes, outlets of system 40 will be disposed within the heat sources for heating combustible liquid 12 and within the dryer 7 and densifier 5 (or a combined dryer/densifier) to assist in operating these machines. Alternatively, the gases may be used or sold separately as feedstock for other chemical synthesis processes. The bio-liquids obtained from the non-volatile vapors and steam may be reused in cooling system 32 or potentially in a steam generator or boiler for heating combustible liquid 12. The present disclosure, therefore, provides for a heat exchange system that results in a more energy-efficient process.

It is further contemplated that the exemplary processes described herein may be continuous, semi-continuous or batch processes. With a continuous, semi-continuous or batch process, the various steps of the process may be connected by a conveyor-type system or other type of system to allow continuous transporting of densified biomass 20 or holder 22 containing densified biomass 20 therein through the present processes as described herein. The present disclosure therefore contemplates a system for carrying out the exemplary torrefaction processes disclosed herein. In such a system, a conveyor or other type of transport system may be used to carry the raw biomass material, whether densified to begin with or not, through the processes described in FIGS. 1 and 2. Accordingly, the raw biomass material 2 is brought from the densifier 5/dryer 7 or receiving container 10 through the process to the cooling system 32, where the torrefied densified biomass 30 is retrieved and available for handling, transport, use, shipping, etc. Any type of continuous system, semi-continuous system or batch system contemplated herein is a straight-line, simple to design, easily operatable and efficient system, with limited complexity and engineering required.

The exemplary processes described herein may further comprise a step of cleaning the torrefied densified biomass 30. This step of cleaning may comprise a screening process, wherein a screening device is used to separate fines and any other waste particles from torrefied densified biomass 30. Alternatively, this step of cleaning may comprise a washing step, wherein torrefied densified biomass 30 is washed in a water bath to remove residual combustible oil adhering to the outer surface of the torrefied densified biomass 30. The cleaning of the torrefied densified biomass 30 may also comprise both a screening step and a washing step.

Another embodiment of the present disclosure relates to an exemplary process 100 illustrated in FIG. 3 wherein a selected biomass or biosolids feedstock is delivered to a pellet press or briquetter 105 wherein the feedstock is densified and extruded as pellets or pressed into briquettes (i.e., densified biomass 20) which are transferred by a pellet feed conveyer 110 into a torrefusion reactor 115. The supply of the selected biomass or biosolids feedstock to pellet press or briquetter 105 may be continuous, semi-continuous or in batches, thereby resulting in a continuous, semi-continuous or batch throughput process 100. The torrefusion reactor 115 contains a volume of heated combustible oil 12 wherein the pellets 20 are submerged and torrefied for a selected period of time. The combustible oil 12 contained in the torrefusion reactor 115, is maintained at a temperature from the range of about 160° C. to about 320° C. The torrefusion reactor 115 has components that controllably maintain the pellets 20 submerged in the heated combustible oil 12 while controllably conveying the submerged pellets 20 from the input end to the output end of the torrefusion reactor 115. The submerged pellets 20 are torrefied during their transport from the input end to the output end of the torrefusion reactor 115 via conveyor 110 (or any other suitable conveyor belt that allows continuous or semi-continuous transport of the pellets through the process 100). The duration of time for transport of the submerged pellets 20 from the input end to the output end of the torrefusion reactor 115 can be controllably varied from about 2 minutes to about 120 minutes (or longer if so desired). After leaving the output end of the torrefusion reactor 115, the torrefied pellets are conveyed on conveyor 110 (or any other suitable conveyor belt that allows continuous or semi-continuous transport of the pellets through the process 100) to a cooler 120 from which they are conveyed into and through a screening device 125 which separates fines from the torrefied pellets. Finally, the screened torrefied pellets are conveyed into a finished product bin 130 via conveyor 110 (or any other suitable conveyor belt that allows continuous or semi-continuous transport of the pellets through the process 100).

Heat and gases produced during torrefaction of the pellets in the torrefusion reactor 115 are collected in a torgas collection hood 160 under a vacuum force created by torgas fan 170 which conveys the heat and torrefaction gases to the torgas burner 145. The torgas burner 145 combines and combusts the torrefaction gases to produce heated air which is then conveyed to the hot side of an air-to-oil heat exchanger 150. The torgas burner 145 and thermal energy from the external burner is combined prior to the heat exchanger 150. The combustible oil contained within the torrefusion reactor 115 is maintained at a selected temperature by constant circulation by an oil pump 152 through an oil filter 154 and into the cool side of the air-to-oil heat exchanger 150 wherein it is heated by the heated air incoming from the torgas burner 145. The heated combustible oil is then conveyed back into the torrefusion reactor 115. The air-to-oil heat exchanger 150 is vented 158 to the atmosphere. Optionally, the screened fines 135 may also be conveyed to a burner 140 for production of thermal energy, and the thermal energy then routed to a torgas burner 145.

Another embodiment of the present disclosure relates to an exemplary process 200 illustrated in FIG. 4 wherein a selected biomass or biosolids feedstock is delivered to a pellet press or briquetter 202 wherein the feedstock is densified and extruded as pellets or pressed into briquettes which are transferred by a pellet feed conveyer 205 into a torrefusion reactor 210. The supply of the selected biomass or biosolids feedstock to pellet press or briquetter 202 may be continuous, semi-continuous or in batches, thereby resulting in a continuous, semi-continuous or batch throughput process 200. The torrefusion reactor 210 contains a volume of heated combustible oil wherein the pellets are submerged and torrefied for a selected period of time. The combustible oil contained in the torrefusion reactor 210, is maintained at a temperature from the range of about 160° C. to about 320° C. The torrefusion reactor 210 has components that controllably maintain the pellets submerged in the heated combustible oil while controllably conveying the submerged pellets from the input end to the output end of the torrefusion reactor 210 via conveyer 205 or another conveyor belt that allows continuous or semi-continuous transport of the pellets through the process 200. The submerged pellets are torrefied during their transport from the input end to the output end of the torrefusion reactor 210. The duration of time for transport of the submerged pellets from the input end to the output end of the torrefusion reactor 210 can be controllably varied from about 2 minutes to about 120 minutes (or longer if so desired). After leaving the output end of the torrefusion reactor 210, the torrefied pellets are conveyed by conveyor 205 (or any other suitable conveyor belt that allows continuous or semi-continuous transport of the pellets through the process 200) into a water bath cooler 215 which receives a constant supply of fresh water 212. Residual combustible oil adhering to the surface of the torrefied pellets conveyed from the torrefusion reactor 210 is washed away from the torrefied pellets into the wash water which is then separated from the washed torrefied pellets. The washed torrefied pellets are conveyed into a finished product bin 220 by conveyor 205 (or any other suitable conveyor belt that allows continuous or semi-continuous transport of the pellets through the process 200).

Heat and gases produced during torrefaction of the pellets in the torrefusion reactor 210 are collected in a torgas collection hood 250 under a vacuum force created by a torgas fan 255 which conveys the heat and torrefaction gases to a torgas burner 260. The torgas burner 260 combines and combusts the torrefaction gases with a supply of thermal energy from an external burner 262 to produce heated air which is then conveyed to the hot side of an air-to-oil heat exchanger 235. The combustible oil contained within the torrefusion reactor 210 is maintained at a selected temperature by constant circulation by an oil pump 225 through an oil filter 230 and into the cool side of the air-to-oil heat exchanger 235 wherein it is heated by the heated air incoming from the torgas burner 260. The heated combustible oil is then conveyed back into the torrefusion reactor 210. The air-to-oil heat exchanger 235 is vented 237 to the atmosphere.

Either fresh water or the wash water from the water bath cooler 215 is optionally routed to equipment 275 that can receive an incoming biomass feedstock from a hopper referred to in FIG. 4 as a “raw salty hog” 270, that may need desalinization processing. Such biomass feedstocks are exemplified by hog fuel wastestreams produced from processing of harvested logs that have been transported on and/or stored on saltwater waterways, which may require desalinization. The wash water is blended with the biomass feedstock in desalting and dewatering equipment 275. The salinized wash water recovered from the desalting and dewatering equipment may optionally be disposed of as an effluent 272, while the desalted and dewatered biomass feedstock is conveyed to the pellet press 202 for densification and extrusion as pellets.

Representative illustrations of a small scale torrefusion reactor for use as torrefusion reactor 115, 210 are shown in FIGS. 5(A), 5(B), 6(A) and 6(B). Torrefusion reactor 115, 210 may comprise a mechanism for continuously or semi-continuously conveying densified biomass 20 through the reactor 115, 210, or for conveying densified biomass 20 in batches through the reactor 115, 210, such as by way of conveyor 110, 205 (or any other suitable conveyor belt that allows continuous or semi-continuous transport of the densified biomass 20 through process 100, 200). Conveyor 110, 205 may be hand-operated, electronically-operated, battery-operated, solar-operated, or otherwise powered to convey densified biomass 20 into and through the torrefusion reactor 115, 210 and torrefied densified biomass 30 out of the torrefusion reaction 115, 210. As shown in FIGS. 5(B), 6(A) and 6(B), the torrefusion reaction may comprise holder 22 or other type of intake hopper/feeder that operates as a densified biomass/biosolids metering bin and comprises a notch, slit, hole, space or any other type of opening 280 at the point of contact with conveyor 110, 205 between the bottom of holder 22 and conveyor 110, 205, such that the densified biomass 20 may be gravity fed from the holder 22 onto the moving conveyor 110, 205 as the conveyor moves. The throughput of the densified biomass 20 onto conveyer 110, 205 and through process 100, 200 may be controlled by adjusting the size of the notch, slit, hole, space or other type of opening 280 in or at the bottom of holder 22 and/or by adjusting the amount, size, weight and thickness of the bed of densified biomass 20 placed in holder 22. The direction of rotation of conveyor 110, 205 is shown in FIG. 6(B). Arrow (A) represents the direction of rotation of conveyor 110, 205 to carry the densified biomass 20 into the combustible liquid for a certain period of time and then conveying the torrefied densified biomass 30 out of the combustible liquid. Arrow (B), shown in shadow, indicates that conveyor 110, 205 may be an endless conveyor belt that can continuously or semi-continuously move densified biomass 20 through the torrefaction processes disclosed herein. It will be understand that in a full-scale, operational throughput process, this conveyor 110, 205 may continue to convey the torrefied densified biomass 30 into water bath cooler 215. An exemplary size for a small scale torrefusion reactor 115, 210 is shown in Table A below.

TABLE A Torrefusion Reactor Size Reactor Length (feet) 36 Reactor Width (feet) 5 Conveyor Thickness (inches) 4 Retention/Submersion time (minutes) 15 Bulk Density (lbs/ft³) 40 Fill Factor (%) 100% Mass of Conveyor Mat (lbs/ft³) 2,400 Mass of Conveyor Mat (MT) 1.09 Conveyor Cycles per Hour 4 Input per Hour (MT) 4.355 Output per Hour @ 80% (MT) 3.484 Operating Hours per Day 24.00 Operating Hours per Week 7.00 Operating Weeks per Year 50.00 Uptime (%) 80 Total Capacity (input) (MT/annum) 29,262 Total Capacity (output) (MT/annum) 23,410

Torrefied densified biomass 30 produced by the processes described herein comprises about 2% to about 25% w/w combustible liquid following torrefaction (i.e., torrefied densified biomass 30 absorbs about 2% to about 25% w/w combustible liquid during the process), or any amount therebetween. For example, without limitation, the amount of combustible liquid 12 absorbed and retained within torrefied densified biomass 30 may be about 2% to about 25% w/w combustible liquid, or any amount therebetween; about 2% to about 24% w/w combustible liquid, or any amount therebetween; about 2% to about 23% w/w combustible liquid, or any amount therebetween; about 2% to about 22% w/w combustible liquid, or any amount therebetween; about 2% to about 21% w/w combustible liquid, or any amount therebetween; about 2% to about 20% w/w combustible liquid, or any amount therebetween; about 2% to about 19% w/w combustible liquid, or any amount therebetween; about 2% to about 18% w/w combustible liquid, or any amount therebetween; about 2% to about 17% w/w combustible liquid, or any amount therebetween; such as, for example, 3% w/w combustible liquid, 4% w/w combustible liquid, 5% w/w combustible liquid, 6% w/w combustible liquid, 7% w/w combustible liquid, 8% w/w combustible liquid, 9% w/w combustible liquid, 10% w/w combustible liquid, 11% w/w combustible liquid, 12% w/w combustible liquid, 13% w/w combustible liquid, 14% w/w combustible liquid, 15% w/w combustible liquid, 16% w/w combustible liquid, or any amount therebetween.

Torrefied densified biomass 30 produced by the processes of the present disclosure may further have a heat energy value of about 6,000 BTU per pound on a bone dry basis to about 13,000 BTU per pound on a bone dry basis, or any heat energy value therebetween, for example, from about 6,000 BTU per pound on a bone dry basis to about 12,000 BTU per pound on a bone dry basis, or any heat energy value therebetween; from about 6,000 BTU per pound on a bone dry basis to about 11,000 BTU per pound on a bone dry basis, or any heat energy value therebetween; from about 6,000 BTU per pound on a bone dry basis to about 10,000 BTU per pound on a bone dry basis, or any heat energy value therebetween; from about 6,000 BTU per pound on a bone dry basis to about 9,000 BTU per pound on a bone dry basis, or any heat energy value therebetween; or from about 9,000 BTU per pound on a bone dry basis to about 13,000 BTU per pound on a bone dry basis, or any heat energy value therebetween; such as, for example, about 9,500 BTU per pound on a bone dry basis; about 10,000 BTU per pound on a bone dry basis; about 10,500 BTU per pound on a bone dry basis; about 11,000 BTU per pound on a bone dry basis; about 11,500 BTU per pound on a bone dry basis; about 12,000 BTU per pound on a bone dry basis; about 12,500 BTU per pound on a bone dry basis; about 13,000 BTU per pound on a bone dry basis, or any heat energy value therebetween. Alternatively, torrefied densified biomass 30 may comprise a heat energy value of about 22 GJ/t on a bone dry basis to about 27 GJ/t on a bone dry basis, or any heat energy value therebetween, for example, from about 22 GJ/t on a bone dry basis to about 26.5 GJ/t on a bone dry basis or any heat energy value therebetween; from about 22 GJ/t on a bone dry basis to about 26 GJ/t on a bone dry basis or any heat energy value therebetween; from about 22 GJ/t on a bone dry basis to about 26 GJ/t on a bone dry basis or any heat energy value therebetween; from about 22 GJ/t on a bone dry basis to about 25 GJ/t on a bone dry basis or any heat energy value therebetween; from about 22 GJ/t on a bone dry basis to about 24 GJ/t on a bone dry basis or any heat energy value therebetween; or from about 22 GJ/t on a bone dry basis to about 23 GJ/t on a bone dry basis, or any heat energy value therebetween.

The torrefied densified biomass 30 produced by the processes disclosed herein may also have a carbon content of about 50 carbon % on a bone dry basis to about 65 carbon % on a bone dry basis, or any amount therebetween. For example, without limitation, the carbon content of the torrefied densified biomass 30 may be about 51 carbon % on a bone dry basis, 52 carbon % on a bone dry basis, 53 carbon % on a bone dry basis, 54 carbon % on a bone dry basis, 55 carbon % on a bone dry basis, 56 carbon % on a bone dry basis, 57 carbon % on a bone dry basis, 58 carbon % on a bone dry basis, 59 carbon % on a bone dry basis, 60 carbon % on a bone dry basis, 61 carbon % on a bone dry basis, 62 carbon % on a bone dry basis, 63 carbon % on a bone dry basis, 64 carbon % on a bone dry basis, 65 carbon % on a bone dry basis, or any amount therebetween.

As disclosed above, the amount of combustible liquid 12 absorbed and retained within torrefied densified biomass 30 may vary depending on one or more factors exemplified by the duration of the torrefaction process, submersion of densified biomass 20 within the combustible liquid 12, the temperature of the combustible liquid 12, the physico-chemical properties of the starting feedstock, the amount of the starting feedstock, and the type of combustible liquid 12 used, amongst other factors. Consequently, the heat energy value of torrefied densified biomass 30 and any other physico-chemical property of the torrefied densified biomass 30, such as the carbon content, or the hydrophobic nature of the torrefied densified biomass 30, may also be tailored by adjusting the one or more variables such as the duration of the torrefaction process, submersion of densified biomass 20 within combustible liquid 12, the temperature of the combustible liquid 12, the properties of the starting feedstock, the amount of the starting feedstock, and the type of combustible liquid 12 used, amongst other factors.

EXAMPLES

The following examples are provided to enable a better understanding of the disclosure described herein.

Example 1 Materials and Methods

In this example, a small test unit was designed for testing purposes. The test unit consisted of: a small container for holding a combustible liquid, such as vegetable oil; a gas burner, on which to place the small container; and a wire basket with a contour of the small container, such that the wire basket fit within the inner walls of the small container. In addition, a small scale capable of measuring up to 10 kgs in 0.001 kg increments and a thermocouple and temperature gauge was used for weight and temperature calculations, respectively.

For this example, 10 kilograms of densified softwood pellets made from a blend of spruce, pine and fir were tested. The 10 kilograms were divided into 1 kilogram samples (using the small scale for measuring), and 1 sample was set aside for testing purposes. As an initial step, the small container was placed on a scale and the net weight of the empty small container was measured. Vegetable oil was then poured into the small container and the total weight of the small container plus vegetable oil was measured, thereby providing a net weight for the vegetable oil. One kilogram of unheated oil was set aside for additional measurements.

Once the measurements of the vegetable oil were complete, the gas burner was turned on to a temperature of about 270° C., and the temperature of the vegetable oil in the small container was monitored using the thermocouple and temperature gauge. After the temperature of the vegetable oil was stabilized at about 260° C. to about 270° C., a 1-Kg sample of densified wood pellets was loaded into the wire strainer basket and submerged in the heated vegetable oil in the small container for about 5 minutes. The wire strainer basket with the densified wood pellets contained therein was then removed from the vegetable oil in the small container, and allowed to drain and drip dry over the small container for 5 minutes. The torrefied densified biomass was retrieved from the wire strainer basket and its weight measured, without submersing in a cold water, to avoid any water absorption by the torrefied densified biomass and contamination of the results. The net weight loss or gain of the sample was then calculated by comparing to the starting weight of the densified wood pellets, on a dry basis. The net weight of the used oil was also measured by measuring the small container containing the used oil and subtracting the weight of the small container. Oil loss by absorption and mass loss of pellets was calculated. This process was repeated another 8 times, each with a 1 kilogram sample of densified wood pellets. The total weight of the small container containing the oil was measured prior to each experiment. One kilogram of the used vegetable oil in the small container was collected for additional testing purposes.

The resulting torrefied densified biomass from all 9 test experiments were collected and mixed together to form a sample batch. One kilogram of the sample batch was collected for testing.

Results:

The results from two sample batches prepared according to the process described for Example 1 are shown in Table 1. The test results indicated that with about 5 minutes in a vegetable oil heated to about 260° C. to about 270° C., densified wood pellets increased in weight by an average of about 10% and increased in BTU value by an average of 15%. In addition, the torrefied wood pellets were found to be hydrophobic and to have increased grindability (i.e., high Hardgrove Grindability Index) as compared to untorrefied wood pellets. “Hardgrove Grindability Index” (“HGI”) is a measure for grindability of coal. Grindability is indicated using the unit ° H, for example, “40° H” or “55° H.” A higher HGI value indicates a more easily pulverized or more grindable product.

As shown in Table 1 below, the lower heating value (LHV) of two sample batches of torrefied pellets obtained from the process were 23.11 and 22.76 GJ/ton, respectively. This represents an increase in LHV of approximately 14.8% for sample 1 and approximately 16.1% for sample 2. Those skilled in the art will know that an average LHV for wood pellet fuel ranges from a low of 18.14 GJ/ton to a high of 19.72 GJ/ton, making torrefied wood pellets of the disclosed process to be approximately 17.5% higher in heat value compared to good quality biofuel.

TABLE 1 Starting Densified Wood Torrefied Wood Pellet Torrefied Wood Pellet Pellet #1 #1 #2 As Received As Received As Received Measurements Basis Dry Basis Basis Dry Basis Basis Dry Basis Weight 1 kg 1 kg 1 kg % Moisture* 7.00 0 2.78 0 0.59 0 Calorific Value (Gross) Btu/lb 8336 8963 9786 10066 9934 9993 Kcal/kg 4631 4979 5437 5592 5519 5552 GJ/ton 19.39 20.85 22.76 23.41 23.11 23.24 % Carbon 55.46 55.79 % Hydrogen 6.58 6.62 (excludes H in 36.92 moisture) % Nitrogen 0.09 0.09 % Sulphur 0.02 0.02 % Ash 0.56 0.56 % Oxygen 36.70 36.92 % Hydrogen 6.65 — (includes H in moisture) *“% Moisture” for the “Torrefied Wood Pellets” refers to the amount of water in the torrefied wood pellets immediately after the torrefaction process (i.e., after drip drying for 5 minutes). “Starting Densified Wood Pellet” is the sample that was initially set aside for testing purposes.

Example 2 Materials and Methods

In this example, a coastal hemlock briquette was quartered and each quarter was used for testing. Three of the quarters were used in the torrefaction process and one quarter was set aside. The initial weight of the quartered briquettes used in the torrefaction process is set out in Table 2 below.

The small test unit, as described above for Example 1, was used in this example. As an initial step, the small container was placed on a scale and the net weight of the empty small container was measured. Vegetable oil was then poured into the small container and the total weight of the small container plus vegetable oil was measured, thereby providing a net weight for the vegetable oil. One kilogram of unheated oil was set aside for additional measurements.

After the measurements of the vegetable oil were complete, the gas burner was turned on to a temperature of about 260° C., and the temperature of the vegetable oil in the small container was monitored. After the temperature of the vegetable oil was stabilized at about 260° C., a quarter briquette sample was loaded into the wire strainer basket and submerged in the heated vegetable oil in the deep fryer for about 7.5 minutes. The wire strainer basket with the quarter briquette sample contained therein was then removed from the vegetable oil in the small container and allowed to drain over the deep fryer for 5 minutes. The torrefied densified biomass was then retrieved from the wire strainer basket and its weight measured, without submersing in a cold water, to avoid any water absorption by the torrefied densified biomass and contamination of the results. The net weight loss or gain of the sample was then calculated by comparing to the starting weight of the densified wood pellets, on a dry basis. The net weight of the used oil was also measured by measuring the small container containing the used oil and subtracting the weight of the small container. Oil loss by absorption and mass loss of pellets was calculated. This process was then repeated another 2 times for the other 2 quarter briquette samples, with the exception that 1 quarter briquette was torrefied for about 10 minutes, and the other for about 15 minutes. The total weight of the small container containing the oil was measured prior to each experiment. One kilogram of the used vegetable oil in the small container was collected for additional testing purposes. The resulting torrefied densified biomass from each experiment was collected for testing.

Results:

The results for Example 2 are shown in Table 2. The test results indicated that all quarter briquette samples increased in weight, on average, by about 10% as compared to the original weight of the respective quarter briquette, representing the approximate amount of oil absorbed by the samples. In addition, the torrefied wood pellets were found to be hydrophobic and to have increased grindability (i.e., high Hardgrove scale score) as compared to untorrefied wood pellets.

TABLE 2 Quartered Briquettes Experiment Sample 1 Sample 2 Sample 3 Starting Weight (g) 139.85 140.85 149.60 Finished Weight (g) 156.40 155.25 165.75 Net Increase in Weight (%) 10.58% 9.28% 9.74% Starting Temp. of Oil (° C.) 222.00 269.00 266.00 Ending Temp. of Oil (° C.) 266.00 270.00 267.00 Retention Time in Oil (mins) 15.00 7.50 10.00

Example 3 Materials and Methods

In this example, 2 1-Kg samples of densified softwood pellets made from a blend of spruce, pine and fir were tested in the small test unit described above in Example 1.

As an initial step, the small container was placed on a scale and the net weight of the empty small container was measured. Vegetable oil was then poured into the small container and the total weight of the small container plus vegetable oil was measured, thereby providing a net weight for the vegetable oil. One kilogram of unheated oil was set aside for additional measurements.

After the measurements of the vegetable oil were complete, the gas burner was turned on to a temperature of about 250° C. to about 260° C., and the temperature of the vegetable oil in the small container was monitored. After the temperature of the vegetable oil was stabilized at about 250° C. to about 260° C., a 1-kilogram sample of densified wood pellets was loaded into the wire strainer basket and submerged in the heated vegetable oil in the small container for about 20 minutes for the first sample. The wire strainer basket with the densified wood pellets contained therein was then removed from the vegetable oil in the small container and allowed to drain over the deep fryer for 5 minutes. The torrefied densified biomass was then retrieved from the wire strainer basket and its weight measured, without submersing in a cold water bath, to avoid any water absorption by the torrefied densified biomass and contamination of the results. The net weight loss or gain of the sample was then calculated by comparing to the starting weight of the densified wood pellets, on a dry basis. The net weight of the used oil was also measured by measuring the small container containing the used oil and subtracting the weight of the small container. Oil loss by absorption and mass loss of pellets was calculated.

After the above process, the second 1-kg sample was loaded into the wire strainer basket and submerged in the heated vegetable oil in the small container for about 30 minutes. The wire strainer basket with the densified wood pellets contained therein was then removed from the small container and allowed to drain over the deep fryer for 5 minutes. The net weight loss or gain of the sample was then calculated by comparing to the starting weight of the densified wood pellets, on a dry basis. The net weight of the used oil was also measured by measuring the small container containing the used oil and subtracting the weight of the small container. Oil loss by absorption and mass loss of pellets was calculated. One kilogram of the used vegetable oil in the deep fryer was collected for additional testing purposes.

Results:

It was found that with 20 minutes in a vegetable oil heated to about 260° C. to about 270° C., torrefied pellets had a net loss of weight of about 2.20%. With 30 minutes in heated vegetable oil, it was found that torrefied pellets had a net weight loss of about 6.16%. In addition, the torrefied wood pellets were hydrophobic and had increased grindability (i.e., high Hardgrove scale score) as compared to untorrefied wood pellets.

Without wishing to be bound by theory, it is thought that some oil absorption occurs during the first few minutes of torrefaction, which may result in a net increase in weight of the biomass. Following the first few minutes, the biomass is increasingly torrefied, thereby expelling VOCs and losing weight, resulting in a torrefied densified biomass that has a net weight loss as compared to the initial starting material.

Example 4 Materials and Methods

In this example, 4 different samples of densified softwood pellets made from a blend of spruce, pine and fir, each weighing about 0.5 kg, were tested using the small test unit described in Example 1. Vegetable oil was heated to 220° C. to about 240° C. in the small container. The weight of the small container was measured before it was filled with oil and after it was filled with oil to determine the weight of the oil prior to the torrefaction process. One of the 4 different samples was submerged in the oil for a pre-determined amount of time, and then allowed to drip dry over the small container for about 5 minutes. The small container containing the oil was measured again following the torrefaction process to determine the amount of oil absorbed by the sample. This procedure was repeated for the three other samples.

Results

The results indicated that there was less absorption with more time in the heated oil, as described above in Example 3. As shown in Table 3 below, sample 1, which was torrefied for about 10 minutes in the hot vegetable oil, showed about 9.6% oil absorption, and sample 2, which was torrefied for about 15 minutes in the hot vegetable oil, showed about 6.7% oil absorption.

TABLE 3 Oil Absorption During Torrefaction Sample 1 Sample 2 Sample Weight - at start 0.5 0.5 Moisture Content* 4% 4% Sample Weight - at start; bone dry basis 0.4808 0.4808 Sample Weight - at end 0.45 0.474 Process Time 15 10 Change in Weight of Sample −6% −1% Oil Weight - at start 2.968 2.926 Oil Weight - at end 2.936 2.88 % Absorption of Oil by Sample 6.6556% 9.5674% (bone dry basis starting weight) *“Moisture Content” refers to the amount of water (in %) in the torrefied wood pellets immediately after the torrefaction process (i.e., after drip drying for 5 minutes).

Example 5 Materials and Methods

In this example, 4 different samples of densified softwood pellets made from a blend of spruce, pine and fir were tested, with each sample having a starting weight of 250 grams (0.250 kg). Each sample was tested using the method as described above in Example 1 and the temperature, time and weight parameters as specified below in Table 4.

Results

The results indicated that the rate of absorption of the oil by the pellets varied over time. As shown in Table 4 below, sample 1, which was torrefied for about 15 minutes in the hot vegetable oil, showed about 14.31% oil absorption per mass input of bone dry pellets; sample 2, which was torrefied for about 30 minutes in the hot vegetable oil, showed about 14.00% oil absorption per mass input of bone dry pellets; sample 3, which was torrefied for about 45 minutes in the hot vegetable oil, showed about 13.88% oil absorption per mass input of bone dry pellets; and sample 4, which was torrefied for about 60 minutes in the hot vegetable oil, showed about 11.87% oil absorption per mass input of bone dry pellets.

As shown in FIG. 7, the oil absorption initially occurred at a higher rate during the first few minutes of torrefaction, after which the rate of absorption decreased and then remained at a constant rate for a period of time. As the torrefaction period progressed further, the rate of absorption stopped and then showed negative values indicating that oil was expelled from the torrefied biomass during the extended periods of torrefaction. In this example, the highest rate of absorption occurred during the first 15 minutes of torrefaction after which, the rate of absorption of oil slowed and then remained at a constant rate through 45 minutes of torrefaction, after which time, it appears that the densified biomass began expelling oil previously absorbed by the densified biomass.

FIG. 7 also shows that the heat value of the torrefied pellets following the torrefaction process increased substantially between 0 and 15 minutes of the torrefaction process, then to increased slowly and fairly consistently between 15 minutes and 45 minutes of torrefaction, and eventually began to decrease after 45 minutes of torrefaction. The “heat value of samples—at end” in Table 4 and “heat value of finished product” in FIG. 7 is the total of the torrefied biomass plus the absorbed oil. Accordingly, the results of this example suggest that as pelleted biomass torrefies, the biomass expels oil (less oil in the finished product means less heat value in the finished product derived from oil). Since there is a net gain in heat value of the torrefied pellets over the long term, even with the expulsion of oil, the biomass itself is gaining heat value during the process and it is not simply due to oil absorption.

TABLE 4 Oil Absorption and Heat Value for Different Submersion Times in Canola Oil Heated to 270° C. Sample 1 Sample 2 Sample 3 Sample 4 Submersion time 15 30 45 60 (minutes) Sample Weight - at start 250.00 250.20 250.80 250.45 (g) Moisture content (%) 1.82 1.82 1.82 1.82 Sample Weight - at start; 245.45 245.65 246.24 245.89 bone dry basis (g) Sample Weight - at 247.5 242.2 236.15 233.5 end (g) Oil Weight - at start (g) 650 612.4 572.4 651.7 Oil Weight - at end (g) 612.4 573.35 531.7 612.6 Gross Oil Used (g) 37.6 39.05 40.7 39.1 Oil Evaporation (g) 2.47 4.65 6.52 9.90 Net Oil Absorbed (g) 35.13 34.40 34.18 29.20 % Absorption of Oil 14.31 14.00 13.88 11.87 by Sample (bone dry basis starting weight) Heat Value of Samples - 18.00 18.00 18.00 18.00 at start (GJ/T @ 5% MC) Heat Value of Samples - 24.10 24.56 24.85 24.75 at end (GJ/T) *“Moisture Content” refers to the amount of water (in %) in the torrefied wood pellets immediately after the torrefaction process (i.e., after drip drying for 5 minutes).

Example 6 Materials and Methods

In this example, 20 kilograms of densified softwood pellets made from a blend of spruce, pine and fir (SPF wood pellets) were tested. The 20 kilograms were divided into 1 kilogram samples, and all 20 of the 1 kilogram samples were tested using the method as to described above in Example 1 for a specific temperature (i.e., either 240, 245, 250, 255, 250, 265 or 270° C.) and for a specific submersion time (i.e., either 10, 15, 20, 25 or 30 minutes) at each temperature, with the exception that a PITCO® commercial deep fryer was used for the process (rather than a small container with a gas burner). In addition, each sample was cooled in a water bath following the torrefaction process for 5 minutes, then removed from the cold water bath and allowed to drain for 5 minutes before collecting the sample in a large tub. The method was repeated for the 20 1-kg samples for each different temperature and submersion time condition. Accordingly, for each temperature and submersion time combination, the method was repeated 20 times with a 1-kg sample each time. In addition, 10 1-kg samples were tested using the method as described above in Example 1 at 280° C. for 30 minutes and 6 1-kg samples were tested using the method as described above in Example 1 at 290° C. for 30 minutes; that is, the method was repeated 10 times for the temperature-time combination of 280° C. for 30 minutes, and the method was repeated 6 times for the temperature-time combination of 290° C. for 30 minutes, and the results for each temperature-time combination were averaged.

The resulting torrefied densified biomass from the different test experiments for each temperature-time condition were collected and mixed together to form a sample batch. One kilogram of the sample batch was collected for testing. The resulting 1-kg sample batch was to analyzed to determine the heat values of the torrefied pellets after each temperature-time condition.

Results

The data for this Example 6 are shown in Tables 5-13 and reflected in FIGS. 8 and 9. This Example 6 substantiates the findings in Example 5 (Table 4 and FIG. 7). The results indicated that the submersion/retention time in the heated canola oil and the temperature of the heated oil substantially correlated with the heat value of the torrefied wood pellet at the end of the process. As shown in Tables 5-13 below, generally, the higher the temperature of the canola oil and the longer the time retained in the heated canola oil, the greater the heat value of the torrefied pellets following the torrefaction process.

The highest heat energy value was obtained when densified pellets were submersed in 290° C. canola oil for 30 minutes (26.04 GJ/t on a bone dry basis) and the lowest heat energy value was obtained when densified pellets were submersed in 240° C. canola oil for 10 minutes (22.78 GJ/t on a bone dry basis). All heat energy values for the torrefied pellets were greater than the heat energy value calculated for densified biomass that was not torrefied (i.e., 20.49 GJ/t on a bone dry basis). Torrefying pellets at 250° C. produced a slightly higher heat energy value than when torrefying pellets at 255° C. at every time point measured. Moreover, a submersion time of 20 minutes produced the highest heat energy value when using canola oil at a temperature of 265° C. This data, therefore, indicated that the torrefaction process may be tailored as desired by varying the temperature of the canola oil and the time submersed in the heated oil.

TABLE 5 Heat Value of Torrefied Wood Pellets Before and After Torrefusion at 240° C. Before Torrefusion Torrefusion Torrefusion for 10 mins. for 15 mins. Wet Dry Wet Dry Wet Dry Measurements Basis Basis Basis Basis Basis Basis Weight 1 kg 1 kg 1 kg % Moisture* 5.66 0 6.05 0 4.92 0 % Ash 0.42 0.44 0.38 0.41 0.37 0.39 % Volatile 79.99 84.79 79.81 84.95 81.19 85.39 Matter % Fixed 13.93 14.77 13.76 14.64 13.52 14.22 Carbon % Sulphur 0.03 0.04 0.02 0.02 0.02 0.02 Calorific Value (Gross) Btu/lb 8309 8807 9202 9794 9437 9925 Kcal/kg 4616 4893 5112 5441 5243 5514 GJ/T 19.33 20.49 21.4 22.78 21.95 23.09 % Carbon 47.76 50.62 51.48 54.8 52.32 55.03 % Nitrogen 0.068 0.073 0.032 0.034 0.019 0.020 % Oxygen 40.36 42.78 35.75 38.05 35.97 37.83 Torrefusion Torrefusion Torrefusion for 20 mins. for 25 mins. for 30 mins. Wet Dry Wet Dry Wet Dry Measurements Basis Basis Basis Basis Basis Basis Weight 1 kg 1 kg 1 kg % Moisture* 5.2 0 4.12 0 3.31 0 % Ash 0.34 0.36 0.37 0.38 0.35 0.36 % Volatile 80.26 84.66 81.28 84.77 81.4 84.19 Matter % Fixed 14.2 14.98 14.23 14.85 14.94 15.45 Carbon % Sulphur 0.01 0.01 0.01 0.01 0.01 0.01 Calorific Value (Gross) Btu/lb 9505 10026 9646 10060 9791 10127 Kcal/kg 5281 5570 5359 55.89 5440 5626 GJ/T 22.11 23.32 22.44 23.4 22.77 23.55 % Carbon 52.65 55.53 53.19 55.47 53.85 55.69 % Nitrogen 0.035 0.037 0.036 0.038 0.044 0.045 % Oxygen 35.36 37.31 35.80 37.35 35.91 37.13 *“% Moisture” with respect to the “Torrefied Wood Pellets” on a “Wet Basis” refers to the amount of water (in %) in the sample following cooling in the water bath for 5 minutes and then draining for 5 minutes, as described in the Methods.

TABLE 6 Heat Value of Torrefied Wood Pellets Before and After Torrefusion at 245° C. Before Torrefusion Torrefusion Torrefusion for 10 mins. for 15 mins. Wet Dry Wet Dry Wet Dry Measurements Basis Basis Basis Basis Basis Basis Weight 1 kg 1 kg 1 kg % Moisture* 5.66 0 7.28 0 6.76 0 % Ash 0.42 0.44 0.32 0.34 0.35 0.37 % Volatile 79.99 84.79 79.1 85.31 78.77 84.48 Matter % Fixed 13.93 14.77 13.3 14.35 14.12 15.15 Carbon % Sulphur 0.03 0.04 0.01 0.01 0.01 0.01 Calorific Value (Gross) Btu/lb 8309 8807 9260 9987 9360 10039 Kcal/kg 4616 4893 5145 5548 5200 5577 GJ/T 19.33 20.49 21.54 23.23 21.77 23.35 % Carbon 47.76 50.62 51.01 55.01 51.69 55.44 % Nitrogen 0.068 0.073 0.040 0.043 0.040 0.043 % Oxygen 40.36 42.78 35.10 37.87 34.84 37.37 Torrefusion Torrefusion Torrefusion for 20 mins. for 25 mins. for 30 mins. Wet Dry Wet Dry Wet Dry Measurements Basis Basis Basis Basis Basis Basis Weight 1 kg 1 kg 1 kg % Moisture* 4.9 0 5.17 0 4.87 0 % Ash 0.41 0.43 0.41 0.43 0.39 0.41 % Volatile 80.82 84.98 79.91 84.27 80.1 84.2 Matter % Fixed 13.87 14.59 14.51 15.3 14.64 15.39 Carbon % Sulphur 0.01 0.01 0.02 0.02 0.02 0.02 Calorific Value (Gross) Btu/lb 9583 10076 9619 10144 9702 10198 Kcal/kg 5324 5598 5344 5635 5390 5666 GJ/T 22.29 23.44 22.37 23.59 22.57 23.72 % Carbon 52.99 55.72 52.99 55.88 53.04 55.75 % Nitrogen 0.037 0.039 0.036 0.038 0.032 0.033 % Oxygen 35.32 37.14 34.99 36.90 35.28 37.09 *“% Moisture” with respect to the “Torrefied Wood Pellets” on a “Wet Basis” refers to the amount of water (in %) in the sample following cooling in the water bath for 5 minutes and then draining for 5 minutes, as described in the Methods.

TABLE 7 Heat Value of Torrefied Wood Pellets Before and After Torrefusion at 250° C. Before Torrefusion Torrefusion Torrefusion for 10 mins. for 15 mins. Wet Dry Wet Dry Wet Dry Measurements Basis Basis Basis Basis Basis Basis Weight 1 kg 1 kg 1 kg % Moisture* 5.66 0 5.83 0 6.42 0 % Ash 0.42 0.44 0.36 0.38 0.38 0.41 % Volatile 79.99 84.79 79.43 84.35 79.35 84.8 Matter % Fixed 13.93 14.77 14.38 15.27 13.85 14.79 Carbon % Sulphur 0.03 0.04 0.02 0.02 0.02 0.02 Calorific Value (Gross) Btu/lb 8309 8807 9411 9994 9459 10107 Kcal/kg 4616 4893 5228 5552 5255 5615 GJ/T 19.33 20.49 21.89 23.25 22 23.51 % Carbon 47.76 50.62 51.67 54.87 51.96 55.52 % Nitrogen 0.068 0.073 0.040 0.042 0.038 0.041 % Oxygen 40.36 42.78 35.79 38.01 34.89 37.29 Torrefusion Torrefusion Torrefusion for 20 mins. for 25 mins. for 30 mins. Wet Dry Wet Dry Wet Dry Measurements Basis Basis Basis Basis Basis Basis Weight 1 kg 1 kg 1 kg % Moisture* 7.93 0 5.32 0 4.91 0 % Ash 0.4 0.43 0.4 0.42 0.41 0.43 % Volatile 78.03 84.75 79.89 84.39 79.71 83.83 Matter % Fixed 13.64 14.82 14.39 15.19 14.97 15.74 Carbon % Sulphur 0.02 0.02 0.02 0.02 0.01 0.01 Calorific Value (Gross) Btu/lb 9447 10261 9735 10283 9849 10358 Kcal/kg 5248 5701 5408 5713 5472 5754 GJ/T 21.97 23.87 22.64 23.92 22.91 24.09 % Carbon 51.48 55.91 52.93 55.91 53.61 56.38 % Nitrogen 0.034 0.037 0.034 0.036 0.036 0.038 % Oxygen 33.93 36.85 34.90 36.85 34.59 36.38 *“% Moisture” with respect to the “Torrefied Wood Pellets” on a “Wet Basis” refers to the amount of water (in %) in the sample following cooling in the water bath for 5 minutes and then draining for 5 minutes, as described in the Methods.

TABLE 8 Heat Value of Torrefied Wood Pellets Before and After Torrefusion at 255° C. Before Torrefusion Torrefusion Torrefusion for 10 mins. for 15 mins. Wet Dry Wet Dry Wet Dry Measurements Basis Basis Basis Basis Basis Basis Weight 1 kg 1 kg 1 kg % Moisture* 5.66 0 8.63 0 9.5 0 % Ash 0.42 0.44 0.39 0.42 0.37 0.41 % Volatile 79.99 84.79 77.87 85.23 76.01 83.99 Matter % Sulphur 0.03 0.04 0.01 0.01 0.01 0.02 Calorific Value (Gross) Btu/lb 8309 8807 9130 9992 9059 10011 Kcal/kg 4616 4893 5072 5551 5033 5561 GJ/T 19.33 20.49 2124 23.24 21.07 23.28 % Carbon 47.76 50.62 51.14 55.97 51.07 56.43 % Nitrogen 0.068 0.073 0.066 0.073 0.067 0.074 % Oxygen 40.36 42.78 33.58 36.77 32.83 36.28 Torrefusion Torrefusion Torrefusion for 20 mins. for 25 mins. for 30 mins. Wet Dry Wet Dry Wet Dry Measurements Basis Basis Basis Basis Basis Basis Weight 1 kg 1 kg 1 kg % Moisture* 7.17 0 6.86 0 6.77 0 % Ash 0.44 0.48 0.51 0.55 0.41 0.44 % Volatile 78.75 84.84 78.09 83.84 78.49 84.2 Matter % Sulphur 0.02 0.02 0.01 0.01 0.02 0.03 Calorific Value (Gross) Btu/lb 9437 10166 9447 10143 9564 10259 Kcal/kg 5243 5648 5248 5635 5313 5700 GJ/T 21.95 23.65 21.97 23.59 22.25 23.86 % Carbon 52.63 56.69 52.96 56.87 53.5 57.38 % Nitrogen 0.063 0.067 0.061 0.065 0.062 0.067 % Oxygen 33.37 35.94 33.30 35.73 32.86 35.23 *“% Moisture” with respect to the “Torrefied Wood Pellets” on a “Wet Basis” refers to the amount of water (in %) in the sample following cooling in the water bath for 5 minutes and then draining for 5 minutes, as described in the Methods.

TABLE 9 Heat Value of Torrefied Wood Pellets Before and After Torrefusion at 260° C. Before Torrefusion Torrefusion Torrefusion for 10 mins. for 15 mins. Wet Dry Wet Dry Wet Dry Measurements Basis Basis Basis Basis Basis Basis Weight 1 kg 1 kg 1 kg % Moisture* 5.66 0 10.01 0 7.62 0 % Ash 0.42 0.44 0.39 0.44 0.39 0.42 % Volatile 79.99 84.79 76.06 84.52 78.25 84.7 Matter % Sulphur 0.03 0.04 0.01 0.01 0.01 0.01 Calorific Value (Gross) Btu/lb 8309 8807 8989 9989 9475 10256 Kcal/kg 4616 4893 4994 5550 5264 5698 GJ/T 19.33 20.49 20.91 23.24 22.04 23.86 % Carbon 47.76 50.62 50.81 56.47 52.5 56.83 % Nitrogen 0.068 0.073 0.068 0.075 0.064 0.069 % Oxygen 40.36 42.78 32.59 36.19 33.13 35.87 Torrefusion Torrefusion Torrefusion for 20 mins. for 25 mins. for 30 mins. Wet Dry Wet Dry Wet Dry Measurements Basis Basis Basis Basis Basis Basis Weight 1 kg 1 kg 1 kg % Moisture* 9.13 0 6.92 0 6.59 0 % Ash 0.37 0.41 0.39 0.42 0.4 0.43 % Volatile 75.83 83.44 77.91 83.7 77.42 82.89 Matter % Sulphur 0.01 0.01 0.02 0.02 0.02 0.03 Calorific Value (Gross) Btu/lb 9376 10318 9677 10397 9771 10461 Kcal/kg 5209 5732 5376 5776 5428 5812 GJ/T 21.81 24 22.51 24.18 22.73 24.33 % Carbon 51.92 57.14 53.42 57.39 53.87 57.68 % Nitrogen 0.063 0.070 0.069 0.074 0.058 0.062 % Oxygen 32.34 35.58 32.86 35.31 32.71 35.00 *“% Moisture” with respect to the “Torrefied Wood Pellets” on a “Wet Basis” refers to the amount of water (in %) in the sample following cooling in the water bath for 5 minutes and then draining for 5 minutes, as described in the Methods.

TABLE 10 Heat Value of Torrefied Wood Pellets Before and After Torrefusion at 265° C. Before Torrefusion Torrefusion Torrefusion for 10 mins. for 15 mins. Wet Dry Wet Dry Wet Dry Measurements Basis Basis Basis Basis Basis Basis Weight 1 kg 1 kg 1 kg % Moisture* 5.66 0 8.35 0 9.44 0 % Ash 0.42 0.44 0.38 0.41 0.39 0.43 % Volatile 79.99 84.79 77.45 84.51 75.58 83.46 Matter % Sulphur 0.03 0.04 0.02 0.02 0.01 0.01 Calorific Value (Gross) Btu/lb 8309 8807 9341 10193 9326 10298 Kcal/kg 4616 4893 5190 5663 5181 5721 GJ/T 19.33 20.49 21.73 23.71 21.69 23.95 % Carbon 47.76 50.62 51.67 56.38 51.66 57.05 % Nitrogen 0.068 0.073 0.068 0.074 0.064 0.071 % Oxygen 40.36 42.78 33.35 36.39 32.34 35.71 Torrefusion Torrefusion Torrefusion for 20 mins. for 25 mins. for 30 mins. Wet Dry Wet Dry Wet Dry Measurements Basis Basis Basis Basis Basis Basis Weight 1 kg 1 kg 1 kg % Moisture* 7.53 0 7.06 0 6.76 0 % Ash 0.37 0.4 0.38 0.41 0.4 0.43 % Volatile 77.2 83.49 76.74 82.57 77.25 82.86 Matter % Sulphur 0.01 0.01 0.01 0.01 0.01 0.01 Calorific Value (Gross) Btu/lb 9759 10554 9763 10504 9823 10535 Kcal/kg 5422 5863 5424 5836 5457 5853 GJ/T 22.7 24.55 22.71 24.43 22.85 24.51 % Carbon 53.85 5824 53.87 57.96 54.33 58.27 % Nitrogen 0.063 0.068 0.062 0.067 0.053 0.057 % Oxygen 31.88 34.46 32.31 34.76 32.10 34.42 *“% Moisture” with respect to the “Torrefied Wood Pellets” on a “Wet Basis” refers to the amount of water (in %) in the sample following cooling in the water bath for 5 minutes and then draining for 5 minutes, as described in the Methods.

TABLE 11 Heat Value of Torrefied Wood Pellets Before and After Torrefusion at 270° C. Before Torrefusion Torrefusion Torrefusion for 10 mins. for 15 mins. Wet Dry Wet Dry Wet Dry Measurements Basis Basis Basis Basis Basis Basis Weight 1 kg 1 kg 1 kg % Moisture* 5.66 0 9.36 0 10.12 0 % Ash 0.42 0.44 0.34 0.38 0.36 0.4 % Volatile 79.99 84.79 76.4 84.3 75.3 83.77 Matter % Fixed 13.93 14.77 13.90 15.32 14.22 15.83 Carbon % Sulphur 0.03 0.04 0.03 0.03 0.03 0.03 Calorific Value (Gross) Btu/lb 8309 8807 9347 10313 9347 10399 Kcal/kg 4616 4893 5193 5729 5193 5777 GJ/T 19.33 20.49 21.74 23.99 21.74 24.19 % Carbon 47.76 50.62 51.74 57.08 51.82 57.65 % Nitrogen 0.068 0.073 0.149 0.164 0.139 0.155 % Oxygen 40.36 42.78 32.31 35.66 31.47 35.03 Torrefusion Torrefusion Torrefusion for 20 mins. for 25 mins. for 30 mins. Wet Dry Wet Dry Wet Dry Measurements Basis Basis Basis Basis Basis Basis Weight 1 kg 1 kg 1 kg % Moisture* 8.26 0 7.28 0 7.2 0 % Ash 0.41 0.44 0.38 0.41 0.38 0.41 % Volatile 75.32 82.11 77.14 83.2 76.3 82.23 Matter % Fixed — — 15.20 16.39 16.12 17.36 Carbon % Sulphur 0.01 0.01 0.03 0.03 0.03 0.03 Calorific Value (Gross) Btu/lb 9623 10490 9858 10631 9918 10688 Kcal/kg 5346 5828 5477 5906 5510 5938 GJ/T 22.38 24.4 22.93 24.73 23.07 24.86 % Carbon 53.39 58.19 54.39 58.66 54.85 59.11 % Nitrogen 0.068 0.074 0.134 0.145 0.134 0.144 % Oxygen 31.64 34.51 31.50 33.98 31.09 33.50 *“% Moisture” with respect to the “Torrefied Wood Pellets” on a “Wet Basis” refers to the amount of water (in %) in the sample following cooling in the water bath for 5 minutes and then draining for 5 minutes, as described in the Methods.

TABLE 12 Heat Value of Torrefied Wood Pellets Before and After Torrefusion at 280° C. Before Torrefusion Torrefusion for 30 mins. Measurements Wet Basis Dry Basis Wet Basis Dry Basis Weight 1 kg 1 kg % Moisture* 5.66 0 9.05 0 % Ash 0.42 0.44 0.41 0.45 % Volatile Matter 79.99 84.79 73.75 81.09 % Fixed Carbon 13.93 14.77 16.79 18.46 % Sulphur 0.03 0.04 0.03 0.03 Calorific Value (Gross) Btu/lb 8309 8807 9913 10900 Kcal/kg 4616 4893 5507 6056 GJ/T 19.33 20.49 23.06 25.35 % Carbon 47.76 50.62 54.62 60.06 % Nitrogen 0.068 0.073 0.138 0.152 % Oxygen 40.36 42.78 29.60 32.54 *“% Moisture” with respect to the “Torrefied Wood Pellets” on a “Wet Basis” refers to the amount of water (in %) in the sample following cooling in the water bath for 5 minutes and then draining for 5 minutes, as described in the Methods.

TABLE 13 Heat Value of Torrefied Wood Pellets Before and After Torrefusion at 290° C. Before Torrefusion Torrefusion for 30 mins. Measurements Wet Basis Dry Basis Wet Basis Dry Basis Weight 1 kg 1 kg % Moisture* 5.66 0 10.03 0 % Ash 0.42 0.44 0.43 0.47 % Volatile Matter 79.99 84.79 71.15 79.08 % Fixed Carbon 13.93 14.77 18.39 20.45 % Sulphur 0.03 0.04 0.03 0.03 Calorific Value (Gross) Btu/lb 8309 8807 10071 11194 Kcal/kg 4616 4893 5595 6219 GJ/T 19.33 20.49 23.42 26.04 % Carbon 47.76 50.62 55.91 62.15 % Nitrogen 0.068 0.073 0.143 0.159 % Oxygen 40.36 42.78 27.31 30.35 *“% Moisture” with respect to the “Torrefied Wood Pellets” on a “Wet Basis” refers to the amount of water (in %) in the sample following cooling in the water bath for 5 minutes and then draining for 5 minutes, as described in the Methods.

Example 7 Materials and Methods

The same method as described in Example 6 was used in this example, including the different submersion times in the heated canola oil (i.e., either 10, 15, 20, 25 or 30 minutes) and the different temperatures of the canola oil used in the process (i.e., either 240, 245, 250, 255, 250, 265 or 270° C.; and submersing for 30 minutes at 280° C. or 290° C.).

In this example, the resulting data was analyzed to determine the carbon content of the torrefied pellets after each temperature-time combination.

Results

The data for this Example 7 are shown in Tables 5-13 above and in FIG. 10. The results indicated that the carbon percentage of the torrefied wood pellets at the end of the torrefaction process generally increased with an increase in submersion/retention time in heated canola oil and with an increase in the temperature of the heated oil. As shown in FIG. 10, there was a general upward trend in the carbon content of the torrefied wood pellets with an increase in temperature of the canola oil. There was also substantial correlation between carbon content and submersion time in heated oil.

The highest carbon content was obtained when the densified wood pellets were submersed in 290° C. canola oil for 30 minutes (62.15 carbon % on a bone dry basis) and the lowest carbon content was obtained when the densified wood pellets were submersed in 240° C. canola oil for 10 minutes (54.80 carbon % on a bone dry basis). The carbon content for all torrefied pellets was greater than the carbon percentage calculated for densified biomass that was not torrefied (i.e., 50.62 carbon % on a bone dry basis).

Example 8 Materials and Methods

The amount of evaporation of the different types of combustible liquids were tested. Each combustible liquid was tested once using the following evaporation test. The small test unit as described above for Example 1 was used for this test. The small container was placed on the scale and the net weight of the empty small container was measured. A volume of oil was measured out and poured into the small container and a lid placed on top of the small container. The gas burner was then turned on to 270° C., and the temperature of the oil was monitored. Once the desired temperature of 270° C. was reached, the small container with the vegetable oil was removed from the gas burner and the small container with the vegetable oil was calculated. The small container with the vegetable oil was then put back on the gas burner and allowed to heat for 30 minutes at 270° C. The weight of the small container with the vegetable oil was measured after 30 minutes of heating and the reduction in weight caused by evaporation recorded.

The different combustible liquids tested were: canola oil, sunflower oil, corn oil, peanut oil, bar and chain oil, 5W30 oil, automatic transmission fluid, hydraulic fluid AW32, gear oil 80W90, and paraffin wax.

Results

The results indicated that evaporation of each of the different combustible liquids after heating at 270° C. for 30 minutes was negligible. Accordingly, evaporation of the combustible liquids was not taken into account when calculating oil absorption by torrefied densified biomass following a torrefaction process.

Example 9 Materials and Methods

This Example 9 was performed in order to compare the oil absorption by densified pellets when using canola oil as the combustible liquid versus paraffin wax as the combustible liquid.

In this example, densified softwood pellets made from a blend of spruce, pine and fir (SPF wood pellets) were tested. A 250 gram sample of SPF wood pellets was weighed out and a wire sieve for holding the densified material was separately weighed. The sample of densified material was then loaded into the wire sieve and the total weight of the sieve plus densified material was measured and then set aside for testing purposes. The small test unit described in Example 1 was used for this example. As an initial step, the small container was placed on a scale and the net weight of the small container was measured. A volume of oil (either canola oil or paraffin wax) was measured out and poured into the small container and the total weight of the small container plus oil was measured, thereby providing a net weight for the oil.

Once the measurements of the oil were complete, the gas burner was turned on to a specific temperature (either 250° C., 260° C. or 270° C.), and the temperature of the oil was monitored.

After the temperature of the oil was stabilized at the desired temperature, the following weights were measured: (a) the weight of the small container plus the heated oil; (b) the weight of the small container plus the heated oil plus the lid for the small container plus a temperature probe inserted into the small container; and (c) the weight of the small container plus the heated oil plus the lid for the small container plus a temperature probe inserted into the small container plus the 250 gram sample of densified material loaded in the wire sieve and placed on top of the small container (i.e., not yet submerged in the small container).

Upon completion of the above measurements, the wire sieve containing the densified material was submerged in the heated oil and the small container covered with a lid. The densified material was submerged in the heated oil for a specific amount of time (either 15 or 30 minutes). After submersion for the desired time, the gas burner was turned off and the total weight of the small container, oil, lid, temperature probe, sieve and densified material was measured (with the sieve and densified material still submerged in the oil). The wire sieve with the densified material contained therein was then removed from the small container and oil, and allowed to drain over the small container for about five minutes. The drained wire sieve with the densified material contained therein was weighed, and the densified material was subsequently weighed separately. With the sieve and densified material removed, the total weight of the small container, oil, lid and temperature probe was weighed and then the total weight of the small container plus oil was subsequently weighed separately.

The bone dry weight of the torrefied pellets was then calculated (i.e., to provide a bone dry basis for the torrefied pellets), and then the bone dry weight of the pellets was compared to the loss of oil and a % oil absorption calculated.

The above process was completed twice for each temperature, time and oil combination (i.e., two test runs done for each different type of oil being tested at each different temperature and submersion time), with each process starting with a 250 gram sample of densified pellets.

Results

As shown in FIG. 11, when canola oil was used as the combustible liquid for the torrefaction process, oil absorption by the densified biomass tended to generally increase when the temperature of the canola oil was increased from 250° C. to 260° C., but then declined slightly when torrefied at a temperature of 270° C. There also appeared to be a general decrease in weight of the torrefied densified biomass with increased temperature; however, carrying out the torrefaction process at 260° C. for 30 minutes caused an increase in weight (i.e., +11.48 g compared to starting weight, which amounted to a weight of 249.35 g) as compared to carrying out the process at 250° C. for 30 minutes (+8.53 g compared to starting weight, which amounted to an end weight of 246.4 g). This increase in weight corresponded with an increase in oil absorption for this temperature-time condition (i.e., an oil absorption of 21.02% per mass input of bone dry pellets at 260° C. for 30 minutes, as compared to an oil absorption of 16.65% at 250° C. for 30 minutes), which suggested that the weight increase is due to the increased oil absorption when torrefying at 260° C. for 30 minutes. The slight decline in oil absorption when a temperature of 270° C. was used (i.e., 16.86% oil absorption at 15 minutes and 17.11% at 30 minutes) also corresponded to a decrease in the weight of the torrefied densified biomass at this temperature (i.e., −1.28 g at 15 minutes and −5.47 g at 30 minutes), further suggesting that oil absorption is correlated with the weight of the resulting torrefied densified biomass. This data also correlated with the data obtained from Examples 3 and 5.

FIG. 12 shows that similar results were obtained when paraffin wax was used as the combustible liquid. Oil absorption by the densified biomass tended to generally increase when the temperature of the paraffin wax was increased from 250° C. to 260° C., but then declined when torrefied at a temperature of 270° C. The rate of increase in the oil absorption was greater for paraffin wax than for canola oil when increasing the temperature from 250° C. to 260° C. and when increasing the submersion time at each temperature point. As with canola oil, there also appeared to be a general decrease in weight of the torrefied densified biomass with increased temperature. However, there did not seem to be a correlation between the weight of the torrefied densified biomass at the end of the process and the oil absorbed by the torrefied densified biomass as seen with canola oil.

FIG. 13 and Tables 14 and 15 below illustrate that generally more canola oil was lost during the torrefaction process when canola oil was used as the combustible liquid. The amount of oil loss was generally similar when using either canola oil or paraffin wax, except when torrefying at 250° C. The amount of paraffin wax lost when torrefying at 250° C. for 15 minutes was significantly less with paraffin wax. Furthermore, the rate of loss of oil between 15 minutes of torrefaction and 30 minutes of torrefaction at 250° C. when paraffin wax was used as the combustible liquid seemed to be significantly greater than when canola oil was used.

As shown in FIG. 14, when using canola oil as the combustible liquid rather than paraffin wax, the reduction in weight of the torrefied pellet as compared to the starting biomass differed. For both, as shown in Tables 14 and 15 and described above, the weight of the torrefied pellets generally tended to decrease with increased temperature. However, with canola oil, the weight of the torrefied pellets was greater than the starting densified pellets when the torrefaction process was carried out at 250° C. and 260° C. There was only a reduction in weight as compared to the starting densified pellets when torrefying at 270° C. With paraffin wax, the end weight of the torrefied pellet was generally less than the starting weight of the densified pellet, except when torrefying at 250° C. for 15 minutes. Paraffin wax generally led to a greater reduction in weight at all time points and temperatures. Without wishing to be bound by theory, these results may be due to the biomass absorbing less paraffin wax during the torrefaction process than when canola oil is used. Less absorption of the paraffin wax may be as a result of the longer molecular chain of paraffin wax and perhaps a greater evaporation rate of paraffin wax.

TABLE 14 Canola Oil Absorption by Pellets and Weight Reduction of Pellets During Torrefaction at Different Temperatures and Submersion Times Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Sample 6 Submersion Time (mins.) 15 30 15 30 15 30 Temperature (° C.) 250 250 260 260 270 270 Sample Weight - at start; 250.00 250.00 250.00 250.00 250.00 250.00 wet basis (g) Moisture Content (%)* 4.85 4.85 4.85 4.85 4.85 4.85 Sample Weight - at start; 237.88 237.88 237.88 237.88 237.88 237.88 bone dry basis (g) Sample Weight - at end; 251.30 246.40 244.48 249.35 236.60 232.40 bone dry basis (g) Change in Weight - bone dry +13.43 +8.53 +6.60 +11.48 −1.28 −5.47 basis (g) Pot + Oil Weight - at start 2,390.20 2,350.75 2,355.40 2,359.20 2,352.90 2,346.70 (g) Pot + Oil Weight - at end (g) 2,356.20 2,311.15 2,318.10 2,309.20 2,312.80 2,306.00 Change in Pot + Oil Weight −34.00 −39.60 −37.30 −50.00 −40.10 −40.70 (g) Reduction in Pellet Weight 5.64 3.58 2.78 4.82 −0.54 −2.30 Start to Finish (%) % Oil Absorption by Sample 14.29% 16.65% 15.68% 21.02% 16.86% 17.11% Including Evaporation (bone dry basis) *“Moisture Content” refers to the amount of water in the samples immediately after the torrefaction process (i.e., after drip drying for 5 minutes).

TABLE 15 Paraffin Wax Absorption by Pellets and Weight Reduction of Pellets During Torrefaction at Different Temperatures and Submersion Times Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Sample 6 Submersion Time (mins.) 15 30 15 30 15 30 Temperature (° C.) 250 250 260 260 270 270 Sample Weight - at start; 250.00 250.00 250.00 250.00 250.00 250.00 wet basis (g) Moisture Content (%)* 4.85 4.85 4.85 4.85 4.85 4.85 Sample Weight - at start; 237.88 237.88 237.88 237.88 237.88 237.88 bone dry basis (g) Sample Weight - at end; 242.60 234.95 231.40 230.75 219.15 210.95 bone dry basis (g) Change in Weight - bone dry +4.72 −2.93 −6.47 −7.13 −18.73 −26.93 basis (g) Pot + Oil Weight - at start 2,185.10 2,222.35 2,183.30 2,212.05 2,252.75 2,214.60 (g) Pot + Oil Weight - at end (g) 2,178.60 2,186.40 2,151.30 2,162.85 2,219.20 2,176.45 Change in Pot + Oil Weight 6.50 35.95 32.00 49.20 33.55 38.15 (g) Reduction in Pellet Weight 1.99 −1.23 −2.72 −3.00 −7.87 −11.32 Start to Finish (%) % Oil Absorption by Sample 3 15 13 21 14 16 Including Evaporation (bone dry basis) *“Moisture Content” refers to the amount of water in the samples immediately after the torrefaction process (i.e., after drip drying for 5 minutes).

Example 10 Materials and Methods

The torrefied pellets from Example 6, which proceeded through the torrefaction process at different temperatures (240° C., 245° C., 250° C., 255° C., 260° C., 265° C., 270° C., 280° C. or 290° C.) for different submersion times (10, 15, 20, 25 or 30 minutes), were tested to determine the hydrophobic nature of the torrefied pellets. To do this, a 953.63 gram sample from each batch of processed torrefied densified biomass corresponding to a specific temperature-time condition was measured out and submersed in water for two weeks (i.e., 14 days). Once removed from the water, the samples were allowed to drain in a sieve for 5 minutes, and then each sample was weighed to measure the change in weight of the sample. This measurement was compared to the weight of the water, and the amount of water absorbed by each sample was calculated.

Results

The data in Table 16 indicated that as the temperature of the torrefaction process increased (i.e., the temperature of the heated canola oil), the hydrophobic nature of the resulting product increased. This data is represented in FIGS. 15 and 16, which show that the amount of water absorbed by the torrefied densified pellets following the torrefaction process correlated with the temperature of the torrefaction process. When torrefied at higher temperatures (such as 270° C., 280° C. or 290° C.) rather than at lower temperatures (such as 240° C.), the resulting torrefied densified pellets absorbed less water into the pellets.

The submersion time in the heated canola oil appeared to be less material to the hydrophobic nature of the resulting product; however, the results indicated that generally for shorter submersion times (e.g., 10 minutes), more water was absorbed by the resulting torrefied densified pellets compared to when longer submersion times were used for the torrefaction process (e.g., 30 minutes).

TABLE 16 Water Absorption Following Torrefaction Torrefaction Process Gross Weight of Net Torrefied Water temperature time Weight of Container Weight of Sample Absorbed Sample (° C.) (minutes) Water (g) (g) Water (g) Weight (g) (g) 1 240 10 1,536.50 46.37 1490.13 953.63 536.50 2 240 15 1,437.20 46.37 1390.83 953.63 437.20 3 240 20 1,397.50 46.37 1351.13 953.63 397.50 4 240 25 1,391.50 46.37 1345.13 953.63 391.50 5 240 30 1,394.00 46.37 1347.63 953.63 394.00 6 245 10 1,448.35 46.37 1401.98 953.63 448.35 7 245 15 1,377.20 46.37 1330.83 953.63 377.20 8 245 20 1,377.85 46.37 1331.48 953.63 377.85 9 245 25 1,336.45 46.37 1290.08 953.63 336.45 10 245 30 1,335.70 46.37 1289.33 953.63 335.70 11 250 10 1,421.80 46.37 1375.43 953.63 421.80 12 250 15 1,337.90 46.37 1291.53 953.63 337.90 13 250 20 1,305.20 46.37 1258.83 953.63 305.20 14 250 25 1,319.70 46.37 1273.33 953.63 319.70 15 250 30 1,285.55 46.37 1239.18 953.63 285.55 16 255 10 1358.10 46.37 1311.73 953.63 358.10 17 255 15 1286.25 46.37 1239.88 953.63 286.25 18 255 20 1291.85 46.37 1245.48 953.63 291.85 19 255 25 1260.05 46.37 1213.68 953.63 260.05 20 255 30 1243.35 46.37 1196.98 953.63 243.35 21 260 10 1294.50 46.37 1248.13 953.63 294.50 22 260 15 1290.30 46.37 1243.93 953.63 290.30 23 260 20 1232.85 46.37 1186.48 953.63 232.85 24 260 25 1227.95 46.37 1181.58 953.63 227.95 25 260 30 1223.95 46.37 1177.58 953.63 223.95 26 265 10 1281.10 46.37 1234.73 953.63 281.10 27 265 15 1224.85 46.37 1178.48 953.63 224.85 28 265 20 1225.40 46.37 1179.03 953.63 225.40 29 265 25 1208.25 46.37 1161.88 953.63 208.25 30 265 30 1207.40 46.37 1161.03 953.63 207.40 31 270 10 1236.80 46.37 1190.43 953.63 236.80 32 270 15 1184.40 46.37 1138.03 953.63 184.40 33 270 20 1192.30 46.37 1145.93 953.63 192.30 34 270 25 1164.10 46.37 1117.73 953.63 164.10 35 270 30 1167.80 46.37 1121.43 953.63 167.80 36 280 30 1161.60 46.37 1115.23 953.63 161.60 37 290 30 1149.90 46.37 1103.53 953.63 149.90

Example 11 Materials and Methods

In this example, both densified softwood pellets made from a blend of spruce, pine and fir (SPF wood pellets) and densified hog fuel were tested. A 250 gram sample of either SPF wood pellets or densified hog fuel was weighed out and a wire sieve for holding the densified material was separately weighed. The sample of densified material was then loaded into the wire sieve and the total weight of the sieve plus densified material was measured and then set aside for testing purposes using the small test unit described in Example 1.

As an initial step, the small container was placed on a scale and the net weight of the empty small container was measured. A volume of oil (one of the following: sunflower oil, corn oil, peanut oil, canola oil, bar and chain oil, 5W30 oil, automatic transmission fluid, hydraulic fluid AW32, gear oil 80W90, or paraffin wax) was measured out and poured into the small container and the total weight of the small container plus oil was measured, thereby providing a net weight for the oil.

Once the measurements of the oil were complete, the gas burner was turned on to the testing temperature of 270° C., and the temperature of the oil was monitored.

After the temperature of the oil was stabilized at 270° C., the following weights were measured: (a) the weight of the small container plus the heated oil; (b) the weight of the small container plus the heated oil plus the lid for the small container plus a temperature probe inserted into the small container; and (c) the weight of the small container plus the heated oil plus the lid for the small container plus a temperature probe inserted into the small container plus the 250 gram sample of densified material loaded in the wire sieve and placed on top of the small container (i.e., not yet submerged in the small container).

Upon completion of the above measurements, the wire sieve containing the densified material was submerged in the heated oil and the small container covered with a lid. The densified material was submerged in the heated oil for 30 minutes. After the 30 minute submersion time, the small container was turned off and the total weight of the small container, oil, lid, temperature probe, sieve and densified material was measured (with the sieve and densified material still submerged in the oil). The wire sieve with the densified material contained therein was then removed from the small container and oil, and allowed to drain over the small container for 5 minutes, except in the case of hog fuel, which was allowed to drain for 10 minutes. The drained wire sieve with the densified material contained therein was weighed, and the densified material was subsequently weighed separately. With the sieve and densified material removed, the total weight of the small container, oil, lid and temperature probe was weighed and then the total weight of the small container plus oil was subsequently weighed separately.

The bone dry weight of the torrefied pellets was then calculated, and then the bone dry weight of the pellets was compared to the loss of oil (net of evaporation of the oil) and calculated as a percentage loss of canola oil.

The above process was done twice for each different type of oil used (i.e., two test runs done for each different type of oil being tested), with each process starting with a 250 gram sample of densified pellets.

Results

The data from this example are shown in Table 17 and FIG. 17 for the plant-derived oils, and in Table 18 and FIG. 18 for the petroleum-based oils. These results indicated that torrefaction of the densified biomass in the plant-derived oils generally tended to result in less oil absorption by the resulting torrefied densified biomass, when compared to torrefaction of the densified biomass in the petroleum-based oils.

Amongst the plant-derived oils, torrefaction of SPF pellets in sunflower oil at 270° C. for 30 minutes resulted in the least amount of oil being absorbed by the densified biomass (on average about 11.38% oil absorption). Canola oil resulted in the most oil absorption by the torrefied densified biomass after torrefaction in canola oil at 270° C. for 30 minutes (on average about 12.12% oil absorption).

Amongst the petroleum-based oils, paraffin wax followed by 5W30 motor oil resulted in the least amount of oil absorption by the torrefied densified biomass (on average about 16.48% and 17.10% oil absorption, respectively). Gear oil (80W90) resulted in the most oil absorption by the torrefied densified biomass after torrefaction in the gear oil at 270° C. for 30 minutes (on average about 24.32% oil absorption).

The data in Tables 17 and 18 also indicated that torrefaction in plant-derived oils resulted in a generally lower average net loss in weight of the biomass as compared to torrefaction in petroleum-based oils. Amongst the plant-derived oils, torrefaction in peanut oil resulted in the lowest average net loss in weight (i.e., a net loss in weight of about 7.70 g) and torrefaction in sunflower oil resulted in the highest average net loss in weight (i.e., a net loss in weight of about 10.85 g). Amongst the petroleum-based oils, torrefaction in bar and chain oil and hydraulic fluid (AW32) resulted in the lowest average net losses in weight (i.e., net losses in weight of about 10.70 g and 10.60 g, respectively) and torrefaction in automatic transmission fluid (ATF) resulted in the highest average net loss in weight (i.e., a net loss in weight of about 17.23 g).

As shown in Tables 17 and 18, when hog fuel was used as the starting densified biomass, significantly greater oil absorption occurred by the hog fuel biomass in plant-derived oils (canola oil) and petroleum-based oils (paraffin wax) and a significantly greater average net loss in weight occurred when the hog fuel biomass was torrefied in plant-derived oils (canola oil) and petroleum-based oils (paraffin wax).

TABLE 17 Oil Absorption and Net Loss of Mass for Different Plant-derived Oils Oil Net Loss Average Oil Average Net Combustible Densified Absorption in Weight Absorption Loss in Sample Liquid Biomass (%) (g) (%) Weight (g) 1 Sunflower oil SPF pellets 10.81 12.25 11.38 10.85 2 Sunflower oil SPF pellets 11.96 9.45 1 Corn oil SPF pellets 11.25 9.15 11.88 9.33 2 Corn oil SPF pellets 12.52 9.50 1 Peanut oil SPF pellets 12.02 7.35 11.76 7.70 2 Peanut oil SPF pellets 11.50 8.05 1 Canola oil SPF pellets 10.93 12.05 12.12 10.58 2 Canola oil SPF pellets 13.30 9.10 1 Canola oil Hog fuel 213.40 74.00 239.27 88.23 2 Canola oil Hog fuel 265.13 102.45

TABLE 18 Oil Absorption and Net Loss of Mass for Different Petroleum-Based Oils Oil Net Loss in Average Oil Average Net Combustible Densified Absorption Weight Absorption Loss in Sample Liquid Biomass (%) (g) (%) Weight (g) 1 Bar and Chain oil SPF pellets 19.71 11.00 20.39 10.70 2 Bar and Chain oil SPF pellets 21.07 10.40 1 5W30 motor oil SPF pellets 19.18 14.25 17.10 13.25 2 5W30 motor oil SPF pellets 15.02 12.25 1 Automatic SPF pellets 22.70 18.20 20.90 17.23 transmission fluid 2 Automatic SPF pellets 19.10 16.25 transmission fluid 1 Hydraulic fluid SPF pellets 25.72 9.05 19.99 10.60 (AW32) 2 Hydraulic fluid SPF pellets 14.26 12.15 (AW32) 1 Gear oil (80W90) SPF pellets 34.09 13.70 24.32 12.93 2 Gear oil (80W90) SPF pellets 14.55 14.75 1 Paraffin wax SPF pellets 15.35 14.50 16.48 14.48 2 Paraffin wax SPF pellets 17.61 14.45 1 Paraffin wax Hog fuel 230.89 73.15 231.00 65.80 2 Paraffin wax Hog fuel 231.10 58.45

Example 12 Materials and Methods

In this example, 2 kilograms of densified softwood pellets made from a blend of spruce, pine and fir (SPF wood pellets) were tested. The 2 kilograms were divided into 1 kilogram samples, and each 1 kilogram sample was tested using the method as described above in Example 1 in a combustible liquid (either a plant-derived oil or a petroleum-based oil) heated to a temperature of 270° C. for 30 minutes. The method was repeated for the 2 1-kg samples for each different type of oil. Accordingly, for each type of oil, the method was to repeated twice with a 1-kg sample each time. The resulting torrefied densified biomass from both test experiments for each type of oil were collected and mixed together to form a sample batch. One kilogram of the sample batch was collected for testing.

In this example, the resulting 1-kg sample batch was analyzed to determine the heat energy values of the torrefied pellets after each temperature-time condition.

The plant-derived oils used in this example included peanut oil, sunflower oil and corn oil. The petroleum-based oils used in this example included automatic transmission fluid, gear oil 80W90, motor oil (5W30), bar and chain oil, and hydraulic fluid AW32.

Results

The results shown in Tables 19 and 20 below indicated that the petroleum-based oils generally tended to result in torrefied densified biomass having slightly higher heat energy values than the densified biomass that was torrefied in plant-derived oils. For example, the heat energy values for torrefied densified biomass processed in petroleum-based oils were approximately 26 gigajoules per metric tonne (GJ/t); whereas the heat energy values for biomass processed in plant-derived oils were approximately about 24-25 GJ/t. This difference may be due to greater oil absorption by petroleum-processed biomass, as shown in Example 10 above.

The results further indicated that all of the plant-derived oils produced torrefied products with approximately similar heat energy values, and all of the petroleum-based oils similarly produced torrefied products with approximately similar heat energy values.

TABLE 19 Heat Value of Torrefied Wood Pellets After Torrefusion at 270° C. for 30 Minutes in Plant-derived Oils Sunflower oil Corn Oil Peanut Oil Wet Dry Wet Dry Wet Dry Measurements Basis Basis Basis Basis Basis Basis Weight 1 kg 1 kg 1 kg % Moisture* 1.04 0 0.78 0 1.52 0 % Ash 0.47 0.48 0.44 0.44 0.43 0.44 % Volatile Matter 80.96 81.81 80.69 81.32 80.22 81.46 % Fixed Carbon 17.53 17.71 18.09 18.24 17.83 18.10 % Sulphur 0.02 0.02 0.02 0.02 0.02 0.02 Calorific Value (Gross) Btu/lb 10615 10727 10616 10699 10426 10587 Kcal/kg 5897 5959 5898 5944 5792 5881 GJ/T 24.69 24.95 24.69 24.89 24.25 24.62 % Carbon 58.27 58.88 58.63 59.09 57.72 58.61 % Nitrogen 0.15 0.15 0.14 0.14 0.13 0.13 % Oxygen 33.34 33.69 33.29 33.56 33.53 34.04 *“% Moisture” refers to the amount of water in the samples immediately after the torrefaction process (i.e., after drip drying for 5 minutes).

TABLE 20 Heat Value of Torrefied Wood Pellets After Torrefusion at 270° C. for 30 Minutes in Petroleum-Based Oils Automatic Bar & Chain AW32 Transmission Gear Oil Motor Oil Oil Hydraulic Oil Fluid 80W90 5W30 Wet Dry Wet Dry Wet Dry Wet Dry Wet Dry Measurements Basis Basis Basis Basis Basis Basis Basis Basis Basis Basis Weight 1 kg 1 kg 1 kg 1 kg 1 kg % Moisture* 0.72 0 0.94 0 1.32 0 0.71 0 0.81 0 % Ash 0.44 0.45 0.57 0.57 0.50 0.51 0.72 0.73 0.68 0.68 % Volatile 80.00 80.58 80.14 80.90 79.98 81.06 77.67 78.23 79.32 79.97 Matter % Fixed 18.84 18.97 18.35 18.53 18.20 18.43 20.90 21.04 19.19 19.35 Carbon % Sulphur 0.03 0.03 0.08 0.08 0.04 0.04 0.13 0.13 0.04 0.04 Calorific Value (Gross) Btu/lb 10983 11062 11088 11194 10951 11098 11318 11399 10892 10981 Kcal/kg 6102 6146 6160 6219 6084 6166 6288 6333 6051 6100 GJ/T 25.55 25.73 25.79 26.04 25.47 25.81 26.33 26.51 25.33 25.54 % Carbon 59.57 60.00 60.01 60.58 59.50 60.30 60.64 61.07 59.18 59.66 % Nitrogen 0.15 0.15 0.13 0.13 0.16 0.16 0.16 0.16 0.16 0.16 % Oxygen 32.19 32.42 31.27 31.57 31.59 32.01 30.72 30.94 32.30 32.58 *“% Moisture” refers to the amount of water in the samples immediately after the torrefaction process (i.e., after drip drying for 5 minutes).

Example 13 Materials and Methods

A small scale torrefusion reactor was constructed in order to test the continuous/semi-continuous process disclosed herein. The reactor consists of a conveyor belt that can continuously or semi-continuously convey pellets through combustible liquid held in a large metal tank. The combustible liquid was heated with a temperature control. The pellets were delivered onto the conveyor belt of the reactor, where a hopper would be located, and then conveyed along the conveyor belt into, through and then out of the combustible liquid. The reactor is shown in FIG. 19.

Results

The reactor shown in FIG. 19 was used to torrefy wood pellets and demonstrated that a continuous/semi-continuous process could be used to torrefy pellets. Densified pellets were delivered onto the conveyor belt in hot combustible liquid (on the right-hand side of FIG. 19) and conveyed through the combustible liquid and out the other end (i.e., on the left-hand side of FIG. 19). The pellets were fully submersed as they conveyed along the conveyor belt through the combustible liquid and were delivered on the other end as a torrefied densified biomass.

Claims

1. A torrefied densified biomass prepared by torrefying a densified biomass feedstock in a combustible liquid, the torrefied densified biomass comprising about 2% to about 25% w/w of the combustible liquid.

2. The torrefied densified biomass of claim 1, wherein the combustible liquid is a plant-derived oil.

3. The torrefied densified biomass of claim 2, wherein the plant-derived oil is canola oil, linseed oil, sunflower oil, safflower oil, corn oil, peanut oil, palm oil, soybean oil, rapeseed oil, cottonseed oil, palm kernel oil, coconut oil, sesame seed oil, olive oil, or a combination thereof.

4. The torrefied densified biomass of claim 1, wherein the combustible liquid is a petroleum-based oil or a bitumen-based oil.

5. The torrefied densified biomass of claim 4, wherein the petroleum-based oil or a bitumen-based oil is a synthetic motor oil, a synthetic engine oil, a hydraulic fluid, a transmission fluid, an automatic transmission fluid, a chainsaw bar and chain oil, a gear oil, a diesel fuel, a paraffin wax, or a combination thereof.

6. The torrefied densified biomass of claim 1, wherein the densified biomass feedstock is derived from a plant material.

7. The torrefied densified biomass of claim 6, wherein the plant material is wood waste from wood-processing operations, sawdust, wood chips, straw, bagasse, waste streams from plant processing operations, processed from crops, or a combination thereof.

8. The torrefied densified biomass of claim 1, wherein the densified biomass feedstock comprises biosolids.

9. The torrefied densified biomass of claim 1, having a heat energy value of about 6,000 BTU per pound to about 13,000 BTU per pound.

10. The torrefied densified biomass of claim 1, having a heat energy value of about 22 gigajoules per metric tonne (GJ/T) to about 27 GET on a bone dry basis.

11. The torrefied densified biomass of claim 1 having a carbon content of about 54 carbon % to about 63 carbon % on a bone dry basis.

12. A process for preparing a torrefied densified biomass, comprising the steps of:

(a) densifying a supply of a biomass feedstock to obtain a densified biomass material;

(b) submerging the densified biomass material in a combustible liquid, the combustible liquid at a temperature between about 160° C. and about 320° C.;

(c) torrefying the densified biomass material in the combustible liquid for about 2 minutes to about 120 minutes to produce the torrefied densified biomass; and

(d) recovering the torrefied densified biomass;

wherein the torrefied densified biomass comprises about 2% to about 25% w/w of the combustible liquid.

13. A process for preparing a torrefied densified biomass, comprising the steps of:

(a) providing a supply of densified biomass material;

(b) submerging the densified biomass material in a combustible liquid, the combustible liquid at a temperature between about 160° C. and about 320° C.;

(c) torrefying the densified biomass material in the combustible liquid for about 2 minutes to about 120 minutes to produce the torrefied densified biomass; and

(d) recovering the torrefied densified biomass;

wherein the torrefied densified biomass comprises about 2% to about 20% w/w of the combustible liquid.

14. A process for producing torrefied pellets, comprising the steps of:

(a) densifying a supply of a biomass feedstock and extruding therefrom densified pellets;

(b) conveying the densified pellets into and through an input end of a torrefusion reactor;

(c) submerging the densified pellets in a combustible liquid contained within the torrefusion reactor, the combustible liquid having a temperature between about 160° C. and about 320° C.;

(d) conveying the submerged densified pellets from the input end to an output end of the torrefusion reactor for a period of time from about 2 minutes to about 120 minutes, wherein the densified pellets are torrefied and heat and gases are produced during torrefaction;

(e) discharging the torrefied pellets from the output end of the torrefusion reactor and conveying the torrefied pellets into and through a cooler; and

(f) cleaning the cooled torrefied pellets to produce cleaned torrefied pellets, the cleaned torrefied pellets comprising about 2% to about 20% w/w of the combustible liquid.

15. The process of any of claims 12-14, wherein the supply is provided continuously, or semi-continuously, or in batches.

16. The process of claim 14, wherein the cleaning step (f) comprises a screening process to separate fines from the cooled torrefied pellets.

17. The process of claim 14, wherein the cooler of step (e) is a water cooler and the cleaning step (f) comprises washing the cooled torrefied pellets in water contained within the water cooler to remove residual combustible liquid from outer surfaces of the cooled torrefied pellets.

18. The process of any of claims 12-14, further comprising the steps of:

(a) combining in a torgas heater the torrefusion gases and heat produced during torrefusion, and combusting therein to produced heated air; and

(b) using the heated air to heat the combustible liquid contained within the torrefusion reactor.

19. The process of claim 16, further comprising the steps of:

(a) producing thermal energy from the separated fines;

(b) combining in a torgas burner the thermal energy with the torrefusion gases and heat produced during torrefusion;

(c) combusting the combined thermal energy and torrefusion gases and heat in the torgas burner to produce heated air; and

(d) heating the combustible liquid contained within the torrefusion reactor using the heated air.

20. The process of claim 16, wherein the wash water is used to desalinate a biomass feedstock.