System and Method for Obtaining Combinations of Coal and Biomass Solid Fuel Pellets with High Caloric Content

Abstract

The invention is a new solid fuel combining coal and biomass and the process for making such fuel. The coal must be selected and prepared to be the correct sizes and quality, including the moisture content and levels of pollutants. Biomass must be selected and prepared by grinding and through a heating process in order to remove moisture and partially char the biomass. The biomass may be selected based on its percentage volume of carbon and hydrogen. A third material, binder is prepared in volumes to associate with the coal and biomass. The coal, biomass and binder are mixed in appropriate quantities and may be delivered to an extrusion, press pellet or briquetting machine that forms the mixture into an appropriate size and shape for the intended combustion situation. The resultant solid fuel has had desired properties for efficient burning and emission levels in the furnace for which it is designed.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

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STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

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REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISK APPENDIX

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BACKGROUND OF THE INVENTION

The present invention is in the technical field solid fuels. More particularly, the present invention is in the technical field utilizing a combination of materials to produce a fuel with high caloric content in the form of small briquettes or pellets, which, upon combustion, emit minimal amounts of pollutants.

Conventional solid fuels, such as coal, biomass, and waste carboniferous materials, typically contain impurities and additional hazardous pollutants in the form of chemicals or chemical compounds varying from non-negligibly small, to minute amounts. These impurities, pollutants, or hazardous ingredients make solid fuels more costly to transport, reducing their efficiency of combustion, and causing hazardous emissions. The capture of these impurities, pollutants, or hazardous ingredients post combustion, requires complex processing and excess costs as the impurities, pollutants, or hazardous ingredients are widely disbursed in the combustion gases. Further, the coal, biomass or waste carboniferous material typically is not in suitable physical form for transport or introduction to a furnace. Often, during transportation or handling of coal and biomass, undesirable particulate or dust pollution is emitted and, while the coal, biomass or waste carboniferous material is too small to be held on the stoker grate used to introduce fuel to the furnace of a boiler. Failure to capture and contain this waste results in undesirable, as well as illegal contamination and pollution of the surroundings.

The typical practice of attempting to ignite coal and biomass in separate burners of the same furnace, where the two components are not intimately combined prior to ignition, is inefficient with unintended/undesirable results. The combustion of heterogeneous solid fuels leads to altered flame temperature profiles, slagging, combustion inefficiency, increased ash, in addition to problems with grindability, fuel flow, and corrosion.

Numerous natural and synthetic substances have been used as binders for forming/producing pellets and briquettes of coal. U.S. Pat. No. 3,966,427 teaches how to make coal briquettes using bitumen or bitumen emulsions as binders. Additional art is described in U.S. Pat. No. 5,244,473 which teaches that a binder for coal fines can be made from a phenol-aldehyde resin mixed with a polyisocyanate in the presence of a catalyst. U.S. Pat. No. 5,009,671 teaches that coal briquettes can be made by using a starch binder mixed with molasses and water. Further relevant art is described in U.S. Pat. No. 4,862,485, which teaches means for forming coal pellets by mixing coal particles with polyvinyl alcohol, calcium oxide and/or magnesium oxide and water. U.S. Pat. No. 4,738,685 teaches how to cold press coal fines with molasses, an inorganic hardening agent such as calcium carbonate, calcium phosphate, iron oxide, aluminum oxide and optionally with an acid. Additional teachings relevant, though differing from the present application can be found in U.S. Pat. Nos. 4,618,347, 4,586,936. 4,169,711 and U.S. Pat. No. 5,916,826. Patent application No. 20100162619 describes a method using a Mallard process at a pressure of 5 bar at an elevated temperature for compacting biofuels together with some limited amount of peat or lignite

The present application describes unique and novel systems and methods for obtaining calorically rich combustible briquettes, relatively free of contaminants, consisting of coal and biomass which are new and novel, not featured in the aforementioned references. The biomass can consist of algae, switch grass, wood matter, such as sawdust and/or wood chips, as well as manure to mention a number of useful components, however not limited to such biomass materials.

BRIEF SUMMARY OF THE INVENTION

The present invention is a new solid fuel combining coal and biomass, and other selected carboniferous solids into a homogenous, caloric high value solid fuel. The coal must be selected and prepared to have the correct size and quality, including the moisture content and levels of pollutants. Biomass must also be selected and prepared to have the appropriate be size and quality, including moisture content and levels of pollutants. An essential factor is that the biomass be selected based on its percentage relative to volume of carbon and hydrogen. A third additional material that can be used is a binder, prepared in appropriate volumes so as to efficiently bind the coal and biomass. The coal, biomass and binder are mixed in appropriate proportions that may be delivered to a machine that forms the mixture into extrusions, pellets or briquettes, with the resultant solid fuel having more desired properties for efficient burning with substantially reduced levels of emissions. Emissions are effectively removed and captured by the kilns used in the present process. The pollutant gases can also be reprocessed since many have commercial value.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a flow chart indicating the steps for producing the compressed pellets or briquettes of coal and biomass. Described are the loading, processing, and unloading of the final pellet/briquette product.

FIG. 2 is a block diagram of the various components used to form the final coal-biomass product. Here, a binder can be used to aid in combining the coal and biomass, but the use of a binder is an option.

FIG. 3a is a shredding or chipping machine to cut the biomass into small pieces in order to be able to combine them with the crushed coal.

FIG. 3b shows a crusher that is used to create small pieces of coal from the original coal input.

FIG. 3c shows a kiln, a first such kiln used to prepare the coal by eliminating some of the moisture and unwanted polluting volatiles of the coal, a second such kiln used to prepare the biomass where the kiln removes moisture and volatiles.

FIG. 3d is a duct for liquefying valuable hydrocarbons emitted in heating coal in the first kiln.

FIG. 3e illustrates the mixing machine for combining the crushed coal after processing in the first kiln, the coal then known as coal char, the shredded biomass and the liquefied hydrocarbons emanating from a duct connected to the first kiln, with the liquefied hydrocarbons acting as a binder between the coal char and biomass.

FIG. 3f is a schematic of the briquetting machine which receives the mixture of coal, biomass, and the liquefied hydrocarbons, the latter acting as a binder. The briquetting machine compresses the material from the mixer through one or more dies to produce brick, briquettes or pellets.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the flow chart FIG. 1, the coal-biomass process begins with coal 101 loaded into a raw coal crusher 102 to reduce coal to any desired size. The coal may be as small as ¼ inch in any dimension. Once crushed or ground, the coal contents pass from crusher 102 to the first kiln 103. The average temperature of the kiln is on the order of 500 C. which drives off moisture and certain volatiles, some of which are contaminants, the contaminant volatiles entrained or sequestered in a clean up station, while other volatiles are in the form of useful gaseous hydrocarbons. The valuable hydrocarbon gases are driven off from kiln 103 and can be transferred to clean coal tar duct 104 where the hydrocarbon gases are liquefied. This is an optional but useful step in the overall process. In all cases, the solid contents of kiln 103 are transferred to the coal biomass mixer 106. For the case where duct 104 is used to produce liquefied hydrocarbons, the liquid from 104 is transferred to mixer 106.

Biomass 109 consisting of for example of tree thinning, forest waste, algae, crops grown for fuel, or waste from agriculture, food, or drink processing, is loaded into the biomass shredder/shredding machine 110 shown in FIG. 3a. After shredding, the contents of 110 are transferred to second kiln 111 where the biomass is heated to specified temperatures, usually on the order of 230 C., to remove unwanted moisture (water) and unwanted gases including Hg, Cl, and the like.

The contents of second kiln 111 are further transferred to the coal and biomass mixer 106 where the two sources of fuel are thoroughly mixed. In the preferred embodiment, clean coal tar from duct 104 is also transferred to the mixer 106 to act as a binder between the coal char from first kiln 103 and the biomass entering the mixer 106 from second kiln 111. The contents of the binder material from duct 104 will generally consist of coal tar, bitumen, or emulsions of such materials. Once the material in the coal and biomass mixer consisting of coal char, biomass and the liquefied coal tar from duct 104, is thoroughly combined, the content is transferred to the briquette or extruder device 107. The extruder device 107 produces the finished coal-biomass product 108 in the form of pellets or briquettes.

FIG. 2 is a block diagram showing the components used in the formation of coal and biomass briquettes or pellets. The entrance of coal 206 into coal crusher 207 is followed by the entrance of the crushed coal into the first kiln 208b. The output from the first heated kiln 208b in the form of coal char is transferred to mixer 204. In addition, in an alternate preferred embodiment, the hydrocarbon volatiles from first kiln 208b can be transferred to duct 209 where the duct temperature allows useful hydrocarbon gases to liquefy. The liquefied hydrocarbons are then also transferred to mixer 204 from duct 209. Biomass 201 enters shredder 202 where it is cut into suitable sizes to then be transferred to second kiln 203. The heat from kiln 203 releases volatiles and water vapor, both of which are entrained in two separate cleanup stations. The dried biomass is then transferred to mixer 204. In the preferred embodiment the contents of mixer 204 are coal char from first kiln 208b, liquefied hydrocarbons from duct 209 and biomass from second kiln 203. After thorough mixing in mixer 204, the contents of mixer 204 are transferred to the briquetting machine 205 then the output in the form of coal-biomass briquettes are collected in output container 210.

Referring now to 202 in FIG. 3a, biomass 326 enters the proximal end of shredder 202 through a fixedly attached open flange 326a at the proximal end of 202. A motor driven piston 327 extends within the interior of shredder 202 with cutting blades 327a attached to the lower portion of piston 327. A motor, not shown explicitly in FIG. 3a drives piston. 327 and thereby blades 327a to shred biomass 326 into small portions, on the order of ¼ to 2 inch lengths. The shredded biomass is carried from the proximal end of shredder 202 to the distal end by a conveyor belt 328 in order to remove the biomass from shredder 202 through the distal end with a fixedly attached open flange.

FIG. 3b describes coal crusher 207 where coal 206 enters the proximal end of crusher 207 and is transported from proximal to distal end of 207 by moving belt 302. The crushed coal is illustrated by 301 while the crushing mechanisms are a piston 303 extending into the interior of 207, driven in an up and down motion by a motor not explicitly shown. The crushed coal exits through 304a to which is fixedly attached open flange 304.

FIG. 3c illustrates the first kiln 208b and second kiln 203. Both kilns are functionally identical but with possible variations in their dimensions and the operational temperatures required for the present invention. The biomass exiting the distal end of shredder 202 enters second kiln 203 while crushed coal from the distal end of 207 enters first kiln 208b. The contents of each kiln 203 and 208b during pyrolysis is indicating by 310, consisting in kiln 208b of coal, coal char and coal volatiles, and kiln 203 of biomass and biomass volatiles. Both first and second kilns, 208b and 203 respectively, have a proximal and distal end, each with fixedly attached open flanges 307 and 311a respectively. In first kiln 208b, crushed coal enters through the fixedly attached open flange 307a by way of an airlock 307, the airlock preventing oxygen/air from entering first kiln 208b and second kiln 203. The proximal end of first kiln 208b is maintained at temperatures in the range 175 to 250 C. while the distal end is maintained at a temperature at a range of ˜350-500 C. The proximal and distal ends of second kiln 203 are maintained at a temperature range of 100-150 C. at the proximal end and a temperature range of 200-275 C. at the distal end. Temperatures are controlled by heat coils 309b wrapped around outer kiln shell 305, coils 309b attached to a control power unit (not shown) to provide heat to coils 309b. The crushed coal in kiln 208b and the shredded biomass in kiln 203 are transported from proximal to distal ends of kilns 208b and 203 respectively by means of rotation of kiln core 305 of kilns 208b and 203 by action of a helical steel rail fixedly attached to the inner kiln core 305. In first kiln 208b, hydrocarbon gases evolved in heated kiln core 305 from the crushed coal which transforms to coal char due to the heating in first kiln 208b, exit by way of airlock 308 and through the fixedly attached open flange 311a. The proximal end of both first and second kilns 208b and 203 respectively, have a low temperature volatile cleanup station 309, functioning mainly to trap water vapor, disposed at their proximal ends and a high temperature cleanup station 309a to capture high temperature volatiles such as mercury, sulfur and chlorine, mounted at the distal ends.

Referring now to FIG. 3d, the hydrocarbon gases 320 of first kiln 208b are directed, in one embodiment to duct 209 through the fixedly attached open flange 320a of duct 209. The temperature of duct 209 is maintained at 200-350 C. at the distal end and between 175-250 C. at the proximal distal end of duct. Duct temperature is sensed through a temperature sensor 321 which sends a signal to a master control unit (not shown). Sensor 321, in conjunction with the control unit determines the power to heating coils 321a and thereby the temperature of duct 209, with heat coils 321a wrapped to be in intimate contact with the outer surface of duct 209. Legs 323 and 324 supporting duct 209 are of two different lengths so that duct 209 is slanted thereby allowing the liquefied gases in duct 209 to flow by gravity into mixer 204 shown in FIG. 3e via the fixedly attached open flange 325a attached to the distal end of duct 209 and into one proximal opening with a fixedly attached open flange 313c of mixer 204 shown in FIG. 3e.

In an alternate embodiment, the gases and coal char of first kiln 208b are directed through the fixedly attached open flange at the distal end of first kiln 208b to the mixer 204 shown in FIG. 3 through a proximal 313a opening and a fixedly attached open flange at the proximal end of mixer 204.

The biomass from shredder 202 is directed through the open flange fixedly attached to the distal end of shredder 202 where low temperature volatiles are taken up or entrained and treated in cleanup station 309 and high temperature volatiles are taken up or entrained by the high temperature volatile cleanup station 309a. The heat treated shredded biomass is transferred to an open end with a fixedly attached open flange of mixer 204 shown in FIG. 3e. Mixer 204 has internally mounted rotating blades 314 to achieve the mixing where mixing combines the coal char from first kiln 208b, the liquefied hydrocarbons from duct 209 and the biomass from second kiln 203, the coal char entering through proximal opening 313, biomass from second kiln 208 through proximal opening 313b and the liquefied hydrocarbons through proximal opening 313c, where each proximal opening has a fixedly attached open flange.

After mixing of biomass, coal char and liquefied hydrocarbons in mixer 204, the contents of 204 pass through the distal end of mixer 204 where the distal opening is fixedly attached to an open flange and enter the briquetting device 205 shown in FIG. 3f though a proximal opening with a fixedly attached open flange 316. Device 205 has a rotating screw 317 which carries the mixture of biomass, coal char and liquefied hydrocarbons from the proximal end to its distal end of 205. At the distal end of 205 a die 318 is fixedly attached causing the material carried by rotating screw 317 to be extruded into briquettes bricks or pellets, depending on the particular geometry of die 318. The extruded product is collected in container 210.

While the foregoing written description of the invention enables one of ordinary skill to make and use what is considered presently to be the best mode thereof, those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. The invention should therefore not be limited by the above described embodiment, method, and examples, but by all embodiments and methods within the scope and spirit of the invention as claimed.

Claims

1. A system for pyrolyzing coal, coal char and biomass to yield high caloric fuel, the system comprising: a crusher comprising open proximal and distal ends, said crusher further comprising an open flange fixedly connected to said distal end of said crusher and further comprising means for shaping coal to specified sizes; a shredder comprising open proximal and distal ends, further comprising an open flange fixedly connected to said distal end, said shredder further comprising means for threshing said biomass into specified sizes; a first and a second kiln wherein said first and second kiln each comprise an open proximal input end and a distal open output end, said kilns further comprising an open flange fixedly connected to said proximal and distal end, said first and second kilns further comprising means for controlling respective temperatures of each of said kilns; a duct comprising an open proximal input and distal output end, said duct further comprising an open flange fixedly connected to said proximal distal end, said duct further comprising means for controlling said duct temperature; a mixer comprising at least one open proximal end and one open distal end, said mixer further comprising an open flange fixedly connected to said each proximal and distal ends, said mixer further comprising means for mixing and joining contents within said mixer; a forming machine comprising an open proximal end, further comprising an open flange fixedly connected to said proximal end, and further comprising at least one die fixedly attached to said distal end of said forming machine, said forming machine further comprising means for casting coal, coal char and biomass entering said forming machine from said mixer into geometrical shapes of specified sizes.

2. A system as in claim 1 wherein said proximal end of said crusher receives coal at its proximal end.

3. A system as in claim 1 wherein said first kiln receives coal from said crusher said kiln further comprising a moving belt mounted in the interior of said first kiln providing means for moving said coal from the proximal to the distal end of said first kiln.

4. A system as in claim 1 wherein the temperature of the proximal end of said first kiln is in the temperature range 150-200 C., said distal end of first kiln is in the range 350-500 C.

5. A system as in claim 1 wherein said heated first kiln provides sufficient thermal energy for gases to be driven off from said coal, said gases selected from the group consisting of water vapor, mercury, chlorine, sulfur and hydrocarbons, with the remaining heated solid transformed to coal char.

6. A system as in claim 1 wherein said first kiln comprises means for entraining water vapor near its proximal end in a clean up station, further comprising means for entraining high temperature volatile gases at the distal end in a cleanup station, said gases selected from the group consisting of mercury, chlorine and sulfur at the s distal end of said first kiln.

7. A system as in claim 1 wherein said duct receives hydrocarbon gases from said first kiln wherein said duct comprises means for maintaining the temperature at the proximal end of said duct in the temperature range 150-200 C. and at the distal end of said duct in the temperature range 250-375 C. said temperatures causing caloric hydrocarbons gases to liquefy.

8. A system as in claims 1 and 6 wherein hydrocarbon gases heated in said first kiln are transferred at the distal end of said first kiln to at least one of said proximal openings of said duct and one of said proximal openings of said mixer, wherein said solid heated coal in said first kiln is converted to coal char and wherein said char is transferred to a second opening at the proximal end of said mixer.

9. A system as in claim 1 wherein said mixer comprises a set of rotating blades with means for mixing contents transferred to its interior from said first and second kilns and said duct, said mixer further comprising up to 3 proximal input openings, each opening comprising a fixedly attached open flange, said mixer comprising one distal output end with a fixedly attached open flange.

10. A system as in claim 1 wherein said forming device receives contents from said mixer, said forming device comprising a rigid duct further comprising a proximal open end and further comprising an interior mounted rotating screw extending the length of said duct, said screw rotation providing means for extruding contents of said forming device through a die mounted at the distal end of said device.

11. A system as in claim 10 wherein the extruded output of said forming device is in the shape of at least one of pellets, bricks and briquettes.

12. A system as in claim 1 wherein said open flange at distal end of said coal crusher is fixedly attached to said open flange at proximal end of first kiln, and further wherein open flange at distal end of first kiln is rigidly attached to one of an open flange at proximal end of said mixer and one of said open flange at proximal end of duct, and further wherein said open flange at distal end of said duct is fixedly attached to one of said open flanges at proximal end of said mixer, and further wherein said open flange at distal end of said mixer is fixedly attached to said open flange at proximal end of forming machine.

13. A system as in claim 1 wherein said biomass is loaded into said shredder, said shredder comprising a proximal and distal end, said shredder further comprising a piston with cutting blades extending into the interior of said shredder and further comprising a motor that drives said piston in an up-down motion causing shredding of said biomass.

14. A system as in claim 1 wherein said distal flange of said crusher is fixedly attached to said proximal flange of said second kiln, and further wherein said distal flange of said second kiln is fixedly attached to one of said proximal end flanges of said mixer.

15. A system as in claim 1 wherein a second kiln receives said biomass from said shredder, said second kiln further comprising a moving rotary belt mounted within the interior of said kiln, said belt spanning the length of said kiln and wherein said belt transports said shredded biomass from said proximal end to said distal end of said second kiln, said second kiln further comprising a temperature control unit wherein said proximal end of second kiln is maintained at a temperature range 100-150 C. and said distal end of said kiln in the temperature range 200-230 C.,

16. A second kiln as in claim 14 further comprising means for entraining gases emanating from said heated shredded biomass.

17. A system as in claim 1 wherein said distal flange of said crusher is fixedly attached to said proximal flange of said second kiln, and further wherein said distal flange of said second kiln is fixedly attached to one of said proximal end flanges of said mixer.

18. A method for producing a high caloric coal—biomass fuel, comprising the steps of: loading coal into a first kiln; heating said kiln, passing the heated hydrocarbon gases from said first kiln to a condensation duct; transferring said condensed gases from said duct to a mixer, passing the solid coal char of said first kiln to said mixer; the method further comprising loading biomass into a second heated kiln; directing the heated contents from said second heated kiln into said mixer.

19. A method as in claim 18 comprising the mixing of said biomass, hydrocarbons and solid char; removing said mixed contents from said mixer to a briquette forming device wherein said forming device converts the contents of said mixer into at least one of briquettes, bricks and pellets.