DIRECT HIGH TEMPERATURE SLUDGE ENERGY RECUPERATOR TRANSFORMER MODULE

Abstract

Systems and processes for processing sludge and other natural waste are provided. In one example, the sludge or natural waste may be dried into a powder using high-temperature gas to absorb moisture from the sludge, causing the high-temperature gas to become an at least partially saturated gas. The at least partially saturated gas may pass through a scrubber before being heated in an air-heater and used in the moisture absorption process. The heat for the air-heater may be provided by a burner operable to burn the dried powder obtained from the sludge. The heated gas may be used to pre-heat the saturated gas and may be used to dry additional sludge.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Australian Patent application number 2010905078, filed Nov. 16, 2010, entitled “Direct High Temperature SERT Module (Sewage Energy Recuperator Transformer),” which is incorporated by reference herein in its entirety.

BACKGROUND

1. Field

This application relates generally to the treatment of semi-solid waste materials containing organic solids and, more specifically, to processing municipal sewage sludge, agricultural waste, and other natural waste materials containing organic material (hereinafter referred to as “sludge”) for use as a source of energy.

2. Related Art

Many systems and processes have been developed to treat and dispose of sludge. For example, many systems and processes include removing moisture from the sludge and removing or stabilizing contaminants that may be harmful to the environment or that may pose substantial health risks if not dealt with properly when released into the environment. The moisture removed from the sludge is referred to herein as “waste water.” Many of these treatment systems and processes for removing moisture and contaminants from the sludge produce harmful byproducts of their own that require special handling for disposal.

The residual semi-solid material that results from waste and wastewater treatments, animal waste, and the like, is often referred to as “sludge.” In this application, the term “sludge” is also used to refer to agricultural food stock waste. Sludge, regardless of its origin, may be categorized based on the amount of treatment that it has undergone. For example, sludge that has not yet been decomposed by anaerobic bacteria is often referred to as “undigested sludge,” while sludge that has been decomposed by anaerobic bacteria is often referred to as “digested sludge.” Typically, undigested sludge and raw/fresh animal or food stock waste have higher calorific values, while digested sludge and aged animal or food stock waste typically has a lower calorific value in comparison.

More specifically, there are two main types of waste treatment methods—anaerobic and aerobic. In anaerobic systems, microbes, in the absence of oxygen, are used to break down the raw waste or undigested sludge to form methane gas and other byproducts that may be used and must be properly disposed of. A typical length of time required to process waste using an anaerobic treatment system may be about twelve to twenty days.

A treatment plant utilizing an aerobic treatment process, however, may be able to treat raw, highly contaminated waste or undigested sludge in a single day. Typically, these systems utilize pre-treatment by anaerobic digestion, which may be carried out in an enclosed low-pressure vessel to break down the waste to allow methane gas to be extracted and prospectively used.

Sludge of all types, for example, undigested sludge, digested sludge, activated sludge, raw or fresh waste, aged waste, and the like (all of which are hereinafter referred to as “sludge”) includes more than 90% waste/moisture and will typically undergo a dewatering process in which a portion of the moisture may be removed and the liquid directed (i) back to and commingled with wastewater for treatment prior to disposal or discharge, or (ii) to holding lagoons where it will evaporate or migrate into the groundwater table. The dewatered sludge may be more efficiently processed since all types of sludge require processing before disposal.

Thus, systems and processes for the treating and disposing of sludge are desired.

SUMMARY

In one exemplary embodiment, a system for processing dewatered sludge is provided. In some examples, the system may include either a mill or grinder operable to receive high-temperature gas, receive sludge, and reduce the moisture content of the sludge to break the sludge into a dried powder in the presence of the high-temperature gas, wherein the high-temperature gas absorbs at least a portion of the moisture content of the sludge to become at least partially saturated gas. The system may further include a first separator operable to separate the dried powder from the at least partially saturated gas and a condenser operable to reduce a moisture content of the at least partially saturated gas by reducing the temperature below the vaporization point of the at least partially saturated gas. The system may further include a heater operable to heat the reduced-temperature gas to generate heated gas, a second separator operable to separate at least a portion of ash from the heated gas, wherein the second separator is further operable to direct a first portion of the heated gas to the mill or grinder to be used in the mill or grinder as the high-temperature gas to dry the sludge as it is milled or grinded, and an output system operable to discharge the ash and, in one example, to discharge a second portion of the heated gas from the system or, in another example, to recover heat from this heated gas by using the recovered heat to pre-heat the ambient air that is used in the burner and/or pre-heat the sludge prior to it entering the grinder or mill.

In some examples, the sludge may include digested sludge, undigested sludge, fresh animal waste, aged animal waste, or agricultural food waste. In some examples, the concentration of inert gas in the high-temperature gas may be sufficient to reduce the chance of combustion or explosion. In yet other examples, the high-temperature gas may have a temperature sufficient to deodorize and sterilize the process gas.

In some examples, the heater may include an air-heater jacket operable to receive the reduced-temperature gas from the first condenser, wherein the air-heater jacket is further operable to cause the reduced-temperature gas to travel over at least a portion of a surface of the heater. In other examples, the air-heater jacket may be replaced with a separate pre-heater.

In some examples, the heater may include a burner operable to burn a mixture of ambient air and at least a portion of the dried powder as fuel. The burner may be further operable to burn an oil or gas, separately or in combination with the dried powder fuel. The system may further include a mixing valve operable to combine the mixture of ambient air and one or more of the above described fuels with a portion of the heated gas not directed to the grinder or mill by the tapping duct. The weight of the ambient air may be equal to a weight of the second portion of the heated gas that is discharged by the output system.

In some examples, the first condenser may be operable to receive water at a first temperature, the water to be used to reduce the temperature of the at least partially saturated gas, wherein the first condenser may be further operable to output the water at a second temperature that is higher than the first temperature.

In some examples, the output system includes a water-mist-cooling system operable to reduce a temperature of the second portion of the heated gas to form cooled gas. The output system may further include a third separator operable to separate at least a portion of ash contained in the cooled gas from the cooled gas, wherein the third separator is further operable to discharge the ash separated from the cooled gas from the system. The output system may further include a second condenser operable to reduce a moisture content of the cooled gas by reducing a temperature of the cooled gas to form a reduced moisture gas and a fan operable to discharge the reduced moisture gas from the system. In some examples, warmed water from the second condenser may be used to pre-heat the sludge before entering the grinder or mill.

In another exemplary embodiment, another system for processing dewatered sludge is provided. In some examples, the system may include a mill or grinder operable to receive high-temperature gas, receive sludge, and reduce a moisture content of the sludge by breaking the sludge into a dried powder in the presence of the high-temperature gas, wherein the high-temperature gas absorbs at least a portion of the moisture content of the sludge to form at least partially saturated gas. The system may further include a first separator operable to separate the dried powder from the at least partially saturated gas and a condenser operable to reduce a moisture content of the at least partially saturated gas by reducing a temperature of the at least partially saturated gas to form a reduced-temperature gas. The system may further include a pre-heater operable to pre-heat the reduced-temperature gas to form pre-heated gas, a heater operable to heat the pre-heated gas to further heat the heated gas, and a second separator operable to separate at least a portion of ash from the heated gas. The system may further include a first tapping duct operable to recirculate at least a portion of the heated gas by directing the at least a portion of the heated gas to the mill or grinder, wherein the at least a portion of the heated gas is to be used in the mill or grinder as the high-temperature gas.

In some examples, the first tapping duct may be operable to recirculate a majority of the heated gas received at the tapping duct. In other examples, the high-temperature gas may have a temperature sufficient to deodorize and sterilize the process gas.

In some examples, the pre-heater may be operable to pre-heat the reduced-temperature gas using at least a portion of the heated gas that is not directed to the mill or grinder by the tapping duct. In other examples, the portion of the heated gas that is not directed to the mill or grinder may be either utilized to pre-heat the sludge before it is milled/grinded or removed from the system.

In some examples, the heater may include a burner operable to combust a mixture of ambient air and at least a portion of the dried powder, oil, or gas. In other examples, the heater may include an air-heater jacket operable to receive the pre-heated gas from the pre-heater, wherein the air-heater jacket is further operable to cause the pre-heated gas to travel over at least a portion of a surface of the heater.

In some examples, the system may further include a mixing valve operable to combine the mixture of ambient air and the at least a portion of the dried powder or other fuel with a portion of the heated gas not directed to the mill or grinder by the first tapping duct. In other examples, the system may further include a second tapping duct operable to direct, to the mixing valve, the portion of the heated gas not directed to the mill or grinder.

In other exemplary embodiments, processes and computer-readable storage mediums are provided for processing sludge using the systems described above.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates a block diagram of an exemplary system for treating sludge.

FIG. 2 illustrates a block diagram of another exemplary system for treating sludge.

FIG. 3 illustrates a block diagram of another exemplary system for treating sludge.

FIG. 4 illustrates a block diagram of another exemplary system for treating sludge.

FIG. 5 illustrates a block diagram of another exemplary system for treating sludge.

FIG. 6 illustrates a block diagram of another exemplary system for treating sludge.

FIG. 7 illustrates a block diagram of another exemplary system for treating sludge.

FIG. 8 illustrates an exemplary dual fuel burner and air heater.

FIG. 9 illustrates an exemplary process for treating sludge.

FIG. 10 illustrates an exemplary computing system that may be used to control a sludge treatment system.

DETAILED DESCRIPTION

The following description is presented to enable a person of ordinary skill in the art to make and use the various embodiments. Descriptions of specific devices, techniques, and applications are provided only as examples. Various modifications to the examples described herein will be readily apparent to those of ordinary skill in the art, and the general principles defined herein may be applied to other examples and applications without departing from the spirit and scope of the various embodiments. Thus, the various embodiments are not intended to be limited to the examples described herein and shown, but are to be accorded the scope consistent with the claims.

FIG. 1 illustrates a block diagram of an exemplary treatment system 100. As an overview, treatment system 100 may be used to treat sludge by converting waste/sludge into a powder having a high calorific value that is suitable for combustion in suspension or that may be used as a fertilizer. The treatment system 100 may be capable of processing various types of sludge, for example, digested sludge, undigested sludge, raw waste, fresh waste, aged waste, or combinations thereof. Treatment system 100 may also be used to treat agricultural food wastes, which are herein included in the term “sludge.”

Treatment system 100 may include a storage unit 1 for holding sludge. In some examples, storage unit 1 may be used to store sludge that has been dewatered to have an approximate 15% to 25% solids content. However, it should be appreciated that sludge having other content ratios may be used. Storage unit 1 may include any type of standard storage system suitable for storing sludge. The volume of storage unit 1 may depend on the location of treatment system 100 and “feed stock.” For instance, if treatment system 100 is situated at a municipal wastewater treatment plant or large-scale agricultural operation with an adequate continuous supply of sludge and onsite dewatering, storage unit 1 may be used only as a surge bin having a two to three hour sludge capacity since the treatment system 100 may be fed by the plant's sludge dewatering equipment. If, however, the treatment system 100 is at a treatment plant where the supply of sludge is not adequate for efficient operation of the system on a continuous basis, such as at a hog farm, cattle ranch, farm, or dairy with sludge being trucked in from other sites, the storage unit 1 may have a volume allowing storage of a 24-hour or more running capacity of wet sludge (e.g., between about 15%-25% solids). However, it should be appreciated that, irrespective of the examples cited, a storage unit 1 having any desired capacity may be used.

Treatment system 100 may further include a grinder or mill 2 in which the moisture may be removed from the sludge that has been dewatered (either at the treatment site or offsite). The grinder or mill 2 may also be used to process the sludge to a uniform, or at least substantially uniform, size. In some examples, the feed stock of sludge may be pre-heated with process water of any temperature via a heat exchanger (similar to sludge pre-heater 61 shown in FIG. 2). In some examples, treatment system 100 may receive high-temperature gas and sludge from storage unit 1. Prior to entering grinder or mill 2, the high-temperature gas and either the sludge or pre-heated sludge may be combined at mixing duct 3. Mixing duct 3 may be the point at which wet sludge or wet pre-heated sludge is introduced to the system and mixed with hot drying gas. Here, evaporative cooling may take place as these two products are exposed to one another. Mixing duct 3 may be made of a material capable of withstanding both the high-temperature of the gas and the potentially corrosive nature of either the wet sludge or drying gas. For example, mixing duct 3 may be made of stainless steel or other appropriate material.

In some examples, the sludge may be transferred from storage unit 1 using an auger actuated moving floor system or an alternate means that is capable of delivering an accurate, modulated supply of sludge to the grinder or mill 2. For example, the auger may be capable of delivering previously dewatered, but otherwise wet, sludge. The main feed auger may have a length sufficient to feed sludge from a storage unit 1, which may be located separate from, but adjacent to, the grinder or mill 2. As mentioned above, in some examples the sludge may be pre-heated by process water using a water-to-sludge heat exchanger (not shown) before entering grinder or mill 2.

After being combined at mixing duct 3, the combined high-temperature and reduced moisture gas and sludge (pre-heated sludge or non-pre-heated sludge) may be transferred to grinder or mill 2. The grinder or mill 2 may include a simplex or duplex design and may be configured to pulverize the sludge into a fine powder with a moisture content of less than about 10%. In some examples, grinder or mill 2 may be operable to process on the order of 60 tons of wet sludge (15%-25% solids) over a 24-hour period by flash drying and milling or grinding the sludge to a fine powder with a moisture content of less than 10%, for example, 3%-5%. However, the treatment system may be of any capacity (size) and may reduce the moisture of the sludge to any amount.

In some examples, the grinder or mill 2 may receive high-temperature gas having a temperature sufficient to deodorize and sterilize the process gas. It should be appreciated that this temperature may vary depending on the specific application. The use of high-temperature gas in grinder or mill 2 enables increased moisture pickup per unit weight of dry gas. As a result, the throughput of grinder or mill 2 may be increased in spite of reduced heat input to the grinder or mill 2. Due to the evaporative cooling that occurs within the grinder or mill 2, the temperature of the gas stream may be reduced before exiting the grinder or mill 2. Since the gas may be recirculated exhaust from the dual fuel burner 13, it may be low in oxygen and high in inert gasses (nitrogen and carbon dioxide), thereby reducing the chances of unwanted combustion during drying.

In some examples where grinder or mill 2 includes a duplex mill design, grinder or mill 2 may include an initial stage having one or more macerators for breaking up the sludge in the presence of the high-temperature and low-moisture gas to cause the high-temperature gas to draw moisture from the sludge by evaporative cooling. The duplex grinder or mill 2 may further include an attrition stage having multiple stages of rotating blades arranged such that each side of the duplex grinder or mill 2 may contain blades that revolve in opposite directions (i.e., turning into each other) to form an intensive field of particles traveling at velocities high enough to keep the milled sludge in suspension. In some examples, the arrangement of circulating blades may include a boss carrying these blades such that each stage will have a split phase to ensure that the gas flow carrying the particles intercepts each blade to achieve higher velocity of the particles without shock. Shock may be prevented or reduced by ensuring that the blade rotation is brought together at the same or similar velocity. In some examples, each casing of the duplex design may be fitted with grinding bars arranged to have a slight lead in the production of gas flow from the inlet to the outlet of the grinder or mill 2 to obviate blockage and particles being built up and lodged between the grinding bars.

Treatment system 100 may further include gas-solids separator 4 for separating particulate from the conveying gas received from grinder or mill 2. In some examples, gas-solids separator 4 may be configured to receive the dried powder formed from the sludge and the gas stream carrying the sludge moisture from grinder or mill 2. Gas-solids separator 4 may be configured to separate the dried powder from the at least partially saturated gas flow and deposit the separated powder in a dry fuel bin 5. In some examples, gas-solids separator 4 may be made from a material capable of withstanding high gas temperatures and corrosive materials, such as stainless steel or other appropriate materials, and may be operable to remove at least 90% of the solids from the gas stream. Solids may be dropped via a rotary valve into the dry fuel bin 5 or by any other means.

In some examples, gas-solids separator 4 may be a cellular-type separator. In these examples, the inlet to each individual cell may be fitted with a multiple blade spinner arranged to spin the gases and convey the particles to the outlet of the cell. The particles may, for example, be deposited into dry fuel bin 5 while the clean conveying gas may pass to a condensing-type scrubber 7. For instance, while any percentage of gas and moisture may be utilized, in some examples, about 75% of the gas and moisture received from grinder or mill 2 may pass directly over to condensing-type scrubber 7, while the remaining percentage of the gas and moisture may be vented off a secondary side of gas-solids separator 4 to high-efficiency cyclones 6. In other examples, the remaining percentage of the gas and moisture may instead be used to pre-heat the ambient air supply entering the dual fuel burner 13 via an air-to-air heat exchanger (not shown).

In some examples, cyclones 6 may include a Stairmand-type high-efficiency cyclone to clean the vented gas at the secondary side of gas-solids separator 4. Specifically, two cyclones, each made from temperature and corrosion-resistant materials (e.g., stainless steel), may be used to separate the particles from the conveying gas of the vented gas stream and may discharge the solids to dry fuel bin 5. The cleaned gas may then rejoin the main gas stream entering condensing-type scrubber 7. While the above examples were described using Stairmand-type cyclones, other similar cyclone separators or other gas solids separators capable of functioning effectively and safely in the operating temperatures may be used to clean the gas vented from the gas-solids separator 4.

As mentioned above, once separated from the gas stream, the dried powder, which is now a biofuel, may be stored in dry fuel bin 5. In some examples, dry fuel bin 5 may be isolated from the separators by, for example, rotary valves. Additionally, as described in greater detail below, in some examples, dry fuel bin 5 may include an auger that meters the dried powder through a venturi (e.g., fuel venturi 15) to the dual fuel burner 13 at a rate sufficient to provide enough heat for air heater 12. It should be appreciated that any rate may be used depending on the fuel mixture and other objectives of the system. Dry fuel bin 5 may also include an output auger for removing excess dried powder from treatment system 100 at system exit 33 for use in other systems or processes, for example, as a fuel. In some examples, dry fuel bin 5 may also include a safety system to prevent dust explosions. The safety system may reduce the possibility of dust explosions by, for example, injecting an inert gas, such as nitrogen or carbon dioxide, into dry fuel bin 5. Dry fuel bin 5 may be made of a material capable of withstanding high temperatures, such as stainless steel or other appropriate materials.

As mentioned above, treatment system 100 may further include a condensing-type scrubber 7 for removing moisture and leftover particulate from the at least partially saturated gas produced by gas-solids separator 4 and cyclones 6. The shell of condensing-type scrubber 7 may be made from a high-temperature and corrosion-tolerant material, such as stainless steel or other appropriate materials. Condensing-type scrubber 7 may receive the at least partially saturated gas leaving gas-solids separator 4 and cyclones 6, as well as water from an ambient water source 8. The moisture in the at least partially saturated gas may be removed by lowering the temperature of this gas to below its vaporization point by the lower-temperature ambient water, causing it to condense out of the gas stream. As the moisture condenses into water, it may collect carry-over particulate remaining in the gas stream and carry the particulate out of the system through system exit 10. Additionally, after the ambient water from ambient water source 8 is used to cool the gas stream, the warmed ambient water may exit the system through system exit 9. In other examples, as shown in FIG. 2, instead of exiting the system through system exit 9, the warmed ambient water may be used to pre-heat the sludge/feed stock before it enters grinder or mill 2.

In some examples, the at least partially saturated gas received from gas-solids separator 4 and cyclones 6 may be passed over a series of tubes that are cooled by the flow of water from ambient water source 8, causing the gas temperature to drop. As the cooled temperature is lower than the dew point of the moisture, the moisture will condense out of this gas. In some examples, condensing-type scrubber 7 may include multiple layers of ripple-fin tube coils. These tubes may be cooled by water fed from an ambient water source 8 at a rate controlled to reduce the temperature of the incoming gas to a tepid temperature.

Treatment system 100 may further include system circulation fan 11 for drawing the cooled gas or air from condensing-type scrubber 7 and circulating it through the jacket 50 of air heater 12. In some examples, circulating fan 11 may be made from temperature and corrosion-tolerant materials, such as stainless steel or other appropriate materials, and may circulate 100% of the weight of gas that passes through treatment system 100. In some examples, the gas may be drawn from condensing-type scrubber 7 by system circulating fan 11 and may then be passed to the jacket 50 of air heater 12. The use of a single fan for the recirculation of gas in treatment system 100 provides ease of control, although the system may utilize more than one fan or no fans at all. System circulation fan 11 may include a speed control that may be adjusted based on the fuel used.

In some examples, the gas circulated by system circulation fan 11 may be passed to the air-heater 12 where it may be heated to a temperature and for a duration sufficient to deodorize and sterilize the process gas by dual fuel burner 13. In other examples, the gas may not be deodorized or sterilized. Air-heater 12 may include two shells that form a jacket 50. The jacket 50 may allow less insulation to be used on the outer surface of air-heater 12, and also pre-heats incoming gas before entering the inner shell of air-heater 12. Alternatively, an air-heater design (described in greater detail below) including ceramic or other refractory tiles may be used for the air-heating portions of the process.

Gas from system circulation fan 11 may enter the jacket 50 of air-heater 12 at the end opposite the dual fuel burner 13. The gas may then pass through the jacket 50 wherein the gas may twist as it passes over the surface of the inner shell of air-heater 12 towards the dual fuel burner 13 end of the jacket 50. This may cool the inner shell of air-heater 12 while heating the circulating gas prior to entering the inner shell of air-heater 12. The resultant lower-temperature of the inner shell of air-heater 12 may not result in “clinker” formation. In some examples, the gas passing through the jacket 50 may be heated to a temperature of about 300° C. prior to entering air-heater 12. The gas may then pass into the inner shell of air-heater 12 where it may be heated by the dual fuel burner 13 to a temperature sufficient for the length of the heating chamber so that the gas may be adequately heated for the specific treatment application.

Air-heater 12 may be made from temperature and corrosion-tolerant materials, such as high-temperature stainless steel, ceramic lining, or other appropriate materials, and may operate at a through air velocity equal to several times the floating velocity of the ash particles to prevent particulate deposit in the heater (i.e., “clinker”). Using a high-temperature stainless steel, ceramic lining, or other similar material may allow a smooth internal shell to be presented to the gases and may limit the reduction in velocity over the shell that may occur when more conventional insulation is employed. Additionally, the diameter and length of the air-heater 12 can be designed to keep the gas velocity greater than the floating velocity of the ash particles while not adversely affecting the flame velocity to overheat the flame-producing clinker from the ash.

As mentioned above, dual fuel burner 13 may be used to heat the gas in air-heater 12. The dual fuel burner 13 may utilize any or a combination of multiple fuels. The primary source may be the dried powder biofuel supplied from the dry fuel storage unit 5. The secondary source may be a supplementary fuel source 18, such as gas or oil. The amount of fuel supplied to dual fuel burner 13 may be controlled to maintain a desired outlet temperature for grinder or mill 2. Additionally, the dual fuel burner 13 may be able to supply 100% of the heat required on either biofuel or supplementary fuel alone. In some examples, dual fuel burner 13 may include a separate light-up burner, which may be fired by either oil or gas for light-up purposes. In some examples, the separate light-up burner may be used to maintain the system temperature in a stand-by mode during times when sludge is not available for the process.

The dual fuel burner 13 may be supplied with biofuel and air from a combustion supply fan 14. In some examples, combustion supply fan 14 draws ambient air from the atmosphere through a primary air supply inlet 16 and fuel venturi 15. In some examples, this ambient air for dual fuel burner 13 may be pre-heated by exhaust air from the gas-solids separator 4 via an air-to-air heat exchanger (not shown). The fuel venturi 15 may include a venturi valve arranged to mix the ambient air from primary air supply inlet 16 with dried power from dry fuel bin 5 or supplemental fuel from supplementary fuel source 18. Primary air supply inlet 16 may include an air-to-air heat exchanger system (not shown), as well as a filter and grill fitted with an integral adjustable baffle to control downstream pressure. Combustion supply fan 14 may include a dust handling fan and may supply the dual fuel burner 13 with the mix of ambient air and the dried powder metered from the dry fuel storage unit 5. In some examples, combustion supply fan 14 may include a variable speed drive to control the airflow to dual fuel burner 13.

In some examples, the weight of ambient air that enters dual fuel burner 13 through primary air supply inlet 16 may be equal to approximately 10%-40% of that entering dual fuel burner 13. In these examples, the remaining air entering dual fuel burner 13 may enter through secondary air supply inlet 17. Primary and secondary air supply inlets 16 and 17 may each include a filter and grill fitted with an integral adjustable baffle to control the amount of air entering treatment system 100 and the downstream pressure.

Since the output of dual fuel burner 13 is mixed with the gas circulating through treatment system 100, the concentration of inert gas (e.g., CO₂ and nitrogen) may increase, advantageously maintaining the temperature of air-heater 12 to below the softening point of the ash content of the sludge.

Treatment system 100 may further include a grit arrestor 19 for receiving the heated gas from air-heater 12 and for removing ash from the gas stream. In some examples, gases leaving air-heater 12 may contain a high percentage of grit because the dried powder may have the inorganic material content of its feed stock. In some examples, grit arrestor 19 may be similar in design to gas-solids separator 4, except that it may include an increased number of cells and may be manufactured from materials that are both corrosion and temperature-tolerant.

In some examples, a significant percentage of the gas entering grit arrestor 19 may be cleaned and directed to mixing duct 3 and grinder or mill 2. Ash and the remaining gas may be vented off the secondary side of grit arrestor 19 to be used to pre-heat the ambient air going to the dual fuel burner 13 (as described below with respect to FIG. 2) or may be vented off the secondary side of grit arrestor 19 to an output system to be surplussed from the treatment system 100. Specifically, the ash and the gas entering grit arrestor 19 may be directed to an output system having a water-mist-cooling system 20, ash cyclones 22, terminal condensing scrubber 24, terminal fan 28, and final discharge stack 29. In other examples, a portion of the cleaned gas output by grit arrestor 19 may be directed to a hot wind box by a gas diverter valve (similar to hot wind box 63 and gas diverter valve 65 shown in FIG. 2) to pre-heat the ambient air from secondary air supply inlet 16.

Water-mist-cooling system 20 may include nozzles, pumps, and monitoring equipment for generating a water spray to reduce the temperature of the received gas to a temperature sufficient to re-vaporize the moisture in the partially saturated gas drawn out of the feed stock. The water spray may be generated using water from a filtered ambient water supply 21.

The cooled gas from water-mist-cooling system 20 may be directed to ash cyclones 22. Ash cyclones 22 may be similar or identical to cyclones 6, and may be used to remove ash from treatment system 100 via ash reticulation 23. Ash reticulation 23 may include an augur to remove ash from the system to dry fuel bin 5.

The gas exiting ash cyclones 22 can be directed to terminal condensing scrubber 24. Terminal condensing scrubber 24 may be similar or identical to condensing-type scrubber 7 and may be used to condense moisture out of the gas received from ash cyclones 22. For instance, terminal condensing scrubber 24 may direct the gas received from ash cyclones 22 over a series of tubes that are cooled by the flow of water from ambient water source 25, causing the gas temperature to drop below its vaporization point. As the moisture condenses into water, it may collect carry-over particulate remaining in the gas stream and carry the particulate out of the system through system exit 27. Additionally, in some examples, the warmed ambient water from ambient water source 25 may exit the system through system exit 26. In other examples, as shown in FIG. 2, the warmed ambient water from terminal condensing scrubber 24 may be used to pre-heat the sludge/feed stock before it enters grinder or mill 2.

Treatment system 100 may further include a terminal fan 28 for drawing the surplussed gas through the ash cyclones 22 and terminal condensing scrubber 24. The output of terminal fan 28 may be discharged from the system through final discharge stack 29.

In some examples, the weight of gas that enters treatment system 100 from the atmosphere through primary and secondary air supply inlets 16 and 17 may be equal to the weight of gas that is removed from the system at final discharge stack 29. As a result, a constant weight of gas circulating through the system may be maintained.

FIG. 2 illustrates a block diagram of another exemplary treatment system 200. Treatment system 200 may be similar to treatment system 100, with the differences discussed in greater detail below. Reference numbers for components of treatment system 200 that are the same as those used for components in treatment system 100 indicate that a similar component may be used in treatment system 200.

Specifically, system 200 may include gas diverter valve 65 for diverting a portion (e.g., 25%) of the gas cleaned by grit arrestor 19 to hot wind box 63 to be used to pre-heat the ambient air from secondary air supply inlet 16 before it enters dual fuel burner 13. The remaining portion of the gas cleaned by grit arrestor 19 may be directed to mixing duct 3 and grinder or mill 2. Additionally, as mentioned above, the warmed ambient water from condensing-type scrubber 7 and terminal condensing scrubber 24 may instead be directed to sludge pre-heater 61 to be used to pre-heat the sludge/feed stock before it enters grinder or mill 2.

FIG. 3 illustrates a block diagram of another exemplary treatment system 300. Treatment system 300 may be similar to treatment system 100, with the differences discussed in greater detail below. Reference numbers for components of treatment system 300 that are the same as those used for components in treatment system 100 indicate that a similar component may be used in treatment system 300.

Unlike treatment system 100, treatment system 300 may not include cyclones 6, and may instead direct the output of gas-solids separator 4 to condensing-type scrubber 7. Additionally, unlike treatment system 100, treatment system 300 may include pre-heater 40. In some examples, the gas may be drawn from condensing-type scrubber 7 by system circulation fan 11 and may then be passed to pre-heater 40.

Pre-heater 40 may heat the gas stream from condensing-type scrubber 7 through the use of a special duct arranged to pre-heat moisture-free gases. Pre-heater 40 may be made from temperature and corrosion-tolerant materials, such as stainless steel or other appropriate materials. The pre-heated gas may then pass to the air-heater 12 where it may be heated by dual fuel burner 13. Unlike the air-heater 12 used in treatment system 100, the air-heater 12 used in treatment system 300 may not include an air-heater jacket 50. Thus, in some examples, the pre-heated air from pre-heater 40 may flow directly into the inner chamber of air-heater 12. In some examples, the shell of air-heater 12 may be insulated using white wool fiber or another insulating material.

Unlike treatment system 100, treatment system 300 may not include secondary air supply inlet 17. Thus, 100% of the air for dual fuel burner 13 enters the burner through combustion fan 14. Additionally, unlike treatment system 100 in which the excess ash and gas may be directed from grit arrestor 19 to water-mist-cooling system 20, in some examples, excess ash removed by the grit arrestor 19 of treatment system 300 may be removed from the system at system exit 42.

In treatment system 300, the gas exiting grit arrestor 19 may be directed to tapping duct 43. In some examples, tapping duct 43 may be configured to direct a majority (e.g., more than 50% and, in some examples, between 70%-75%) of the gas that leaves grit arrestor 19 to mixing duct 3 and the input of grinder or mill 2. There, the recirculated gas may provide the heat used to dry the sludge in grinder or mill 2. The remaining gas from grit arrestor 19 may be diverted by tapping duct 43 towards mixing valve 41, where the diverted gas may be combined with filtered air or ambient air from atmosphere 44. In some examples, mixing valve 41 may include a venturi valve. In some examples, combining the diverted gas stream with the filtered or ambient air from atmosphere 44 may cause the temperature of the diverted gas stream to be lowered. This gas stream may then be drawn around the outside of the pre-heater 40 duct arrangement by terminal fan 28 to pre-heat the gas within pre-heater 40. The gas stream drawn around the outside of pre-heater 40 may have its temperature reduced before being discharged to the atmosphere via final discharge stack 29. In some examples, the gas stream drawn around the outside of pre-heater 40 may pass through an additional scrubber to reduce emissions and recover additional energy in the form of heated water before being discharged to the atmosphere via final discharge stack 29. Alternatively, in other examples, the gas stream drawn around the outside of pre-heater 40 may be used to pre-heat the ambient air entering dual fuel burner 13.

In other examples, a portion of the cleaned gas output of grit arrestor 19 may be directed to a hot wind box by a gas diverter valve (similar to hot wind box 63 and gas diverter valve 65 shown in FIG. 2) to pre-heat the ambient air from secondary air supply inlets 16. The remaining portion of the cleaned gas output of grit arrestor 19 may be directed to tapping duct 43.

In other examples, treatment system 300 may include a heat exchanger (similar to sludge pre-heater 61 shown in FIG. 2) to pre-heat the dewatered sludge before entering grinder or mill 2.

In some examples, the weight of gas that enters treatment system 300 from primary air supply inlet 16 may be equal to the weight of gas that is tapped off the system at tapping duct 43 to be cooled and released from treatment system 300 into the atmosphere via final discharge stack 29. As a result, a constant weight of gas may be maintained in treatment system 300.

FIG. 4 illustrates a block diagram of another exemplary treatment system 400. Treatment system 400 may be similar to treatment system 300, except that air-heater 12 may include an air-heater jacket 50 similar to that described above with respect to treatment systems 100 and 200. Thus, in some examples, hot gas from the pre-heater 40 may enter an air-heater jacket 50 where it may circulate around the outside of air-heater 12 before entering the inner chamber of air-heater 12. In some examples, the gas passing through jacket 50 may be heated to an intermediate temperature after exiting jacket 50 and prior to entering air-heater 12. The gas may then pass into the inner shell of air-heater 12 where it is further heated by the dual fuel burner 13. In some examples, the gas may be heated by dual fuel burner 13 to a temperature and for a duration sufficient to deodorize and sterilize the process gas when deodorizing or sterilizing are desired.

In other examples, a portion of the cleaned gas output of grit arrestor 19 may be directed to a hot wind box by a gas diverter valve (similar to hot wind box 63 and gas diverter valve 65 shown in FIG. 2) to pre-heat the ambient air from secondary air supply inlets 16. The remaining portion of the cleaned gas output of grit arrestor 19 may be directed to tapping duct 43.

In other examples, treatment system 400 may include a heat exchanger (similar to sludge pre-heater 61 shown in FIG. 2) to pre-heat the dewatered sludge before entering grinder or mill 2.

FIG. 5 illustrates a block diagram of another exemplary treatment system 500. Treatment system 500 may be similar to treatment system 300, except that a tap may be taken off the duct 51 between the mixing valve 41 and pre-heater 40. The gas diverted at duct 51 may be directed to a dual fuel air supply mixing valve 52 where it may be mixed with the ambient air carrying the dried powder from fuel venturi 15. By combining the gas from duct 51 with the ambient air carrying the dried powder from fuel venturi 15, the ambient air may be pre-heated prior to entering dual fuel burner 13. This may increase the efficiency of the burner 13 while reducing the oxygen level of the air to the burner 13 to avoid the production of clinker from the fuel's ash.

In other examples, a portion of the cleaned gas output of grit arrestor 19 may be directed to a hot wind box by a gas diverter valve (similar to hot wind box 63 and gas diverter valve 65 shown in FIG. 2) to pre-heat the ambient air from secondary air supply inlets 16. The remaining portion of the cleaned gas output of grit arrestor 19 may be directed to tapping duct 43.

In other examples, treatment system 500 may include a heat exchanger (similar to sludge pre-heater 61 shown in FIG. 2) to pre-heat the dewatered sludge before entering grinder or mill 2.

FIG. 6 illustrates a block diagram of another exemplary treatment system 600. Treatment system 600 may be similar to treatment system 300, except that air-heater 12 may include an air-heater jacket 50 as shown in treatment systems 100, 200, and 400. Additionally, treatment system 600 may include a tap taken off duct 51 as shown in treatment system 500.

In other examples, a portion of the cleaned gas output of grit arrestor 19 may be directed to a hot wind box by a gas diverter valve (similar to hot wind box 63 and gas diverter valve 65 shown in FIG. 2) to pre-heat the ambient air from secondary air supply inlets 16. The remaining portion of the cleaned gas output of grit arrestor 19 may be directed to tapping duct 43.

In other examples, treatment system 600 may include a heat exchanger (similar to sludge pre-heater 61 shown in FIG. 2) to pre-heat the dewatered sludge before entering grinder or mill 2.

FIG. 7 illustrates a block diagram of another exemplary treatment system 700. Treatment system 700 may be similar to treatment system 100, except that exemplary treatment system 700 may not include cyclones 6 and may instead direct the output of gas-solids separator 4 to condensing-type scrubber 7. Additionally, unlike the air-heater 12 used in treatment system 100, the air-heater 12 used in treatment system 700 may not include an air-heater jacket 50. Thus, in some examples, the output from condensing-type scrubber 7 may flow directly into the inner chamber of air-heater 12. Treatment system 700 may further include system exit 42 for removing excess ash from the system instead of outputting the ash to water-mist-cooling system 20 as is done in system 100. Furthermore, in system 700, the output of grit arrestor 19 can be directed to tap 70 where a portion of the output may be directed to water-mist-cooling system 20. The remaining portion of the output is directed to mixing duct 3 and grinder or mill 2. Finally, system 700 may not include ash cyclones 22. Thus, the output of water-mist-cooling system 20 may instead be directed to terminal condensing scrubber 24.

In other examples, a portion of the cleaned gas output of grit arrestor 19 may be directed to a hot wind box by a gas diverter valve (similar to hot wind box 63 and gas diverter valve 65 shown in FIG. 2) to pre-heat the ambient air from secondary air supply inlets 16. The remaining portion of the cleaned gas output of grit arrestor 19 may be directed to tap 70.

In other examples, treatment system 700 may include a heat exchanger (similar to sludge pre-heater 61 shown in FIG. 2) to pre-heat the dewatered sludge before entering grinder or mill 2.

FIG. 8 illustrates an exemplary dual fuel burner and air heater that may be used as dual fuel burner 13 and air heater 12 in the examples provided above. Ducted gas from system circulation fan 11 may be brought into the burner through wye 801. A portion of the ducted air may enter burner 13 and may be controlled by an actuated damper. The remainder of the ducted air may be directed down the other branch of wye 801 into a collection box for even distribution around combustion chamber 803. In this way, the amount of air and fuel into burner 13 can be controlled more precisely to complete combustion without having to control combustion with additional air.

In some examples, the inside of combustion chamber 803 may be lined with refractory tiles or another insulating material. Additionally, the combustion chamber 803 may be centered inside the air heater shell. Air heater 12 may further include a bellows-type expansion joint having rods externally preventing the shell from expanding and keeping expansion even.

FIG. 9 illustrates an exemplary process 900 for treating sludge. At block 901, the moisture content of the dewatered sludge may be reduced. In some examples, this may be done using grinder or mill 2 as described above. For instance, sludge may be broken up in the presence of hot air to form a powder having a moisture content of less than about 10%. The hot air may absorb at least a portion of the moisture contained in the sludge. In some examples, the dewatered sludge may be pre-heated before entering the grinder or mill 2 using, for example, sludge pre-heater 61.

At block 903, the dried powder may be separated from the at least partially saturated gas generated at block 901. In some examples, this may be done using gas-solids separator 4 as described above. For instance, gas-solids separator 4 may be operable to separate the powder from the at least partially saturated gas generated by grinder or mill 2 and deposit the separated powder into a dry fuel bin 5. In some examples, gas-solids separator 4 may be a cellular type separator and may include one or more Stairmand-type cyclones to clean gas vented to the secondary side of gas-solids separator 4.

At block 905, the moisture content of the at least partially saturated gas may be reduced by reducing the temperature of the at least partially saturated gas. In some examples, this may be done using condensing-type scrubber 7 as described above. For instance, the at least partially saturated gas may be passed through a series of tubes that are cooled by ambient water received from a water source 8. As the at least partially saturated gas cools below the dew point of the gas moisture, at least a portion of the moister condenses out of the gas. In some examples using pre-heated sludge, the ambient water exiting condensing-type scrubber 7 may be used to pre-heat the dewatered sludge.

At block 907, the reduced-temperature gas generated at block 905 may be pre-heated. In some examples, the reduced-temperature gas generated at block 905 may be pre-heated using a jacket formed around an air-heater. For example, the reduced-temperature gas may be heated using jacket 50 of air-heater 12. Alternatively or in addition, in some examples, the reduced-temperature gas generated at block 905 may be pre-heated using pre-heater 40 as described above. For instance, the gas cooled by condensing-type scrubber 7 may be heated using a special duct arrangement operable to heat the reduced-temperature gas. In some examples, the reduced-temperature gas may be pre-heated using gas that was previously heated by air-heater 12.

At block 909, the pre-heated gas may be heated. In some examples, this may be done using air-heater 12 and dual fuel burner 13 as described above. For instance, dual fuel burner 13 may be operable to burn the powder dried at grinder or mill 2, gas or oil from a supplementary fuel source 18, or combinations thereof.

At block 911, at least a portion of the ash contained in the heated gas may be removed. In some examples, this may be done using a grit arrestor 19 as described above. In particular, grit arrestor 19 may have a design similar to that of gas-solids separator 4 and may be operable to remove at least a portion of the ash contained in the gas heated by air-heater 12.

At block 913, at least a portion of the heated gas may be directed to a mill. In some examples, this may be done by directing a portion of the output of grit arrestor 19 to mixing duct 3 and grinder or mill 2, as described above. For example, in some examples, grit arrestor 19 may be operable to direct a majority (e.g., 70%-75%) of the gas that enters grit arrestor 19 to mixing duct 3 and grinder or mill 2. In other examples, a portion of the gas cleaned by grit arrestor 19 may be directed to grinder or mill 2 while the remaining portion of the cleaned gas may be directed to hot wind box 63 to pre-heat the ambient air from secondary air supply inlets 16. Ash and the remaining gas may be vented off the secondary side of grit arrestor 19 to be surplussed from the system. Specifically, the ash the remaining gas from grit arrestor 19 may be directed to water-mist-cooling system 20, ash cyclones 22, terminal condensing scrubber 24, and discharged from the system through final discharge stack 29. In some examples, the warmed ambient water from condensing scrubber 24 may be used to pre-heat the sludge from storage unit 1 at sludge pre-heater 61.

In other examples, a portion of the cleaned gas output of grit arrestor 19 may be directed to hot wind box 63 by gas diverter valve 65 to pre-heat the ambient air from secondary air supply inlets 16.

In other examples, at least a portion of the heated gas may be directed to grinder or mill 2 by tapping duct 43 as described above. In particular, tapping duct 43 may be operable to recirculate a majority (in some examples, at least 70%) of the gas heated by air-heater 12 by directing the heated gas to grinder or mill 2 to be used to dry sludge. In some examples, the remaining heated gas may be diverted to pre-heater 40 to pre-heat the reduced-temperature gas generated by condensing-type scrubber 7. In other examples, the diverted gas may be used to pre-heat the reduced-temperature gas generated by condensing-type scrubber 7 and the mixture of ambient gas and fuel supplied to dual fuel burner 13.

It should be appreciated that while the blocks of process 900 are provided in a particular order, the blocks can be performed in any order and process 900 can include all or a portion of the blocks listed above.

Those skilled in the art will recognize that the operations of some variations may be implemented using hardware, software, firmware, or combinations thereof, as appropriate. For example, some processes can be carried out using processors or other digital circuitry under the control of software, firmware, or hard-wired logic. (The term “logic” herein refers to fixed hardware, programmable logic and/or an appropriate combination thereof, as would be recognized by one skilled in the art, to carry out the recited functions.) Software and firmware can be stored on computer-readable storage media. Some other processes can be implemented using analog circuitry, as is well known to one of ordinary skill in the art. Additionally, memory or other storage, as well as communication components, may be employed in embodiments of the apparatus and methods described herein.

FIG. 10 illustrates a typical computing system 1000 that may be employed to carry out processing functionality in some variations of the process. For instance, computer system 1000 may be used to control one or more elements of the exemplary treatment systems described above. Those skilled in the relevant art will also recognize how to implement the apparatus and methods described herein using other computer systems or architectures. Computing system 1000 may represent, for example, a desktop, laptop, or notebook computer, hand-held computing device (PDA, cell phone, palmtop, etc.), mainframe, supercomputer, server, client, or any other type of special or general purpose computing device as may be desirable or appropriate for a given application or environment. Computing system 1000 can include one or more processors, such as a processor 1004. Processor 1004 can be implemented using a general or special purpose processing engine such as, for example, a microprocessor, controller, or other control logic. In this example, processor 1004 is connected to a bus 1002 or other communication medium.

Computing system 1000 can also include a main memory 1008, preferably random access memory (RAM) or other dynamic memory, for storing information and instructions to be executed by processor 1004. Main memory 1008 also may be used for storing temporary variables or other intermediate information during execution of instructions to be executed by processor 1004. Computing system 1000 may likewise include a read-only memory (“ROM”) or other static storage device coupled to bus 1002 for storing static information and instructions for processor 1004.

The computing system 1000 may also include information storage mechanism 1010, which may include, for example, a media drive 1012 and a removable storage interface 1020. The media drive 1012 may include a drive or other mechanism to support fixed or removable storage media, such as a hard disk drive, a floppy disk drive, a magnetic tape drive, an optical disk drive, a CD or DVD drive (R or RW), or other removable or fixed media drive. Storage media 1018, may include, for example, a hard disk, floppy disk, magnetic tape, optical disk, CD or DVD, or other fixed or removable medium that is read by and written to media drive 1012. As these examples illustrate, the storage media 1018 may include a computer-readable storage medium having stored therein particular computer software or data.

In some variations, information storage mechanism 1010 may include other similar instrumentalities for allowing computer programs or other instructions or data to be loaded into computing system 1000. Such instrumentalities may include, for example, a removable storage unit 1022 and an interface 1020, such as a program cartridge and cartridge interface, a removable memory (for example, a flash memory or other removable memory module) and memory slot, and other removable storage units 1022 and interfaces 1020 that allow software and data to be transferred from the removable storage unit 1022 to computing system 1000.

In some variations, computing system 1000 can also include a communications interface 1024. Communications interface 1024 can be used to allow software and data to be transferred between computing system 1000 and external devices. Non-limiting examples of communications interface 1024 can include a modem, a network interface (such as an Ethernet or other NIC card), a communications port (such as for example, a USB port), a PCMCIA slot and card, a PCI interface, etc. Software and data transferred via communications interface 1024 are in the form of signals which can be electronic, electromagnetic, optical, or other signals capable of being received by communications interface 1024. These signals are provided to communications interface 1024 via a channel 1028. This channel 1028 may carry signals (e.g., signals to and from sensors or controllers) and may be implemented using a wireless medium, wire or cable, fiber optics, or other communications medium. Some examples of a channel include a phone line, a cellular phone link, an RF link, a network interface, a local or wide area network, and other communications channels.

The terms “computer program product” and “computer-readable storage medium” may be used generally to refer to non-transitory storage media, such as, for example, memory 1008, storage device 1018, or storage unit 1022. These and other forms of computer-readable storage media may be involved in providing one or more sequences of one or more instructions to processor 1004 for execution. Such instructions, generally referred to as “computer program code” (which may be grouped in the form of computer programs or other groupings), when executed, enable the computing system 1000 to perform features or functions of embodiments of the apparatus and methods, described herein.

In some variations where the elements are implemented using software, the software may be stored in a computer-readable storage medium and loaded into computing system 1000 using, for example, removable storage drive 1012 or communications interface 1024. The control logic (in this example, software instructions or computer program code), when executed by the processor 1004, causes the processor 1004 to perform the functions of the apparatus and methods, described herein.

It will be appreciated that, for clarity purposes, the above description has described embodiments of the apparatus and methods described herein with reference to different functional units and processors. However, it will be apparent that any suitable distribution of functionality between different functional units, processors, or domains may be used without detracting from the apparatus and methods described herein. For example, functionality illustrated to be performed by separate processors or controllers may be performed by the same processor or controller. Hence, references to specific functional units are only to be seen as references to suitable means for providing the described functionality, rather than as indicative of a strict logical or physical structure or organization.

While specific components and configurations are provided above, it will be appreciated by one of ordinary skill in the art that other components variations may be used. Additionally, although a feature may appear to be described in connection with a particular embodiment, one skilled in the art would recognize that various features of the described embodiments may be combined. Moreover, aspects described in connection with an embodiment may stand alone.

Furthermore, although individually listed, a plurality of means, elements, or method steps may be implemented by, for example, a single unit or processor. Additionally, although individual features may be included in different claims, these may possibly be advantageously combined, and the inclusion in different claims does not imply that a combination of features is not feasible and/or advantageous. Also, the inclusion of a feature in one category of claims does not imply a limitation to this category, but rather the feature may be equally applicable to other claim categories, as appropriate.

Claims

1. A system for processing dewatered sludge, the system comprising:

at least one of a mill or grinder operable to:

receive high-temperature gas;

receive sludge; and

reduce a moisture content of the sludge by breaking the sludge into a dried powder in the presence of the high-temperature gas, wherein the high-temperature gas absorbs at least a portion of the moisture content of the sludge to form at least partially saturated gas;

a first separator operable to separate the dried powder from the at least partially saturated gas;

a first condenser operable to reduce a moisture content of the at least partially saturated gas by reducing a temperature of the at least partially saturated gas to form a reduced-temperature gas;

a heater operable to heat the reduced-temperature gas to form a heated gas;

a second separator operable to separate at least a portion of ash contained in the heated gas from the heated gas, wherein the second separator is further operable to direct a first portion of the heated gas to the at least one of the mill or grinder to be used as the high-temperature gas; and

an output system operable to discharge the ash and a second portion of the heated gas from the system.

2. The system of claim 1, wherein the sludge comprises at least one of digested sludge, undigested sludge, fresh animal waste, aged animal waste, or agricultural food waste.

3. The system of claim 1, wherein the heater comprises an air-heater jacket operable to receive the reduced-temperature gas from the first condenser, and wherein the air-heater jacket is further operable to cause the reduced-temperature gas to travel over at least a portion of a surface of the heater.

4. The system of claim 1, wherein the heater comprises a burner operable to burn a mixture of ambient air and at least a portion of the dried powder.

5. The system of claim 4, wherein the burner is further operable to burn a gas or oil.

6. The system of claim 4, further comprising a hot wind box, wherein a portion of an output of the second separator is used to pre-heat the ambient air in the hot wind box.

7. The system of claim 1, wherein the first condenser is operable to receive water at a first temperature, the water to be used to reduce the temperature of the at least partially saturated gas, and wherein the first condenser is further operable to output the water at a second temperature that is higher than the first temperature.

8. The system of claim 1, wherein the first portion of the heated gas comprises a majority of the heated gas.

9. The system of claim 1, wherein the output system comprises:

a water-mist-cooling system operable to reduce a temperature of the second portion of the heated gas to form cooled gas;

a third separator operable to separate at least a portion of ash contained in the cooled gas from the cooled gas, wherein the third separator is further operable to discharge the ash separated from the cooled gas from the system;

a second condenser operable to reduce a moisture content of the cooled gas by reducing a temperature of the cooled gas to form a reduced moisture gas; and

a fan operable to discharge the reduced moisture gas from the system.

10. The system of claim 9 further comprising a sludge pre-heater, wherein an output of the second condenser is used to pre-heat the sludge in the sludge pre-heater.

11. A system for processing dewatered sludge, the system comprising:

at least one of a mill or grinder operable to:

receive high-temperature gas;

receive sludge; and

reduce a moisture content of the sludge by breaking the sludge into a dried powder in the presence of the high-temperature gas, wherein the high-temperature gas absorbs at least a portion of the moisture content of the sludge to form at least partially saturated gas;

a first separator operable to separate the dried powder from the at least partially saturated gas;

a condenser operable to reduce a moisture content of the at least partially saturated gas by reducing a temperature of the at least partially saturated gas to form a reduced-temperature gas;

a pre-heater operable to pre-heat the reduced-temperature gas to form pre-heated gas;

a heater operable to heat the pre-heated gas to form heated gas;

a second separator operable to separate at least a portion of ash contained in the heated gas from the heated gas; and

a first tapping duct operable to recirculate at least a portion of the heated gas by directing the at least a portion of the heated gas to the at least one of the mill or grinder, wherein the at least a portion of the heated gas is to be used in the at least one of the mill or grinder as the high-temperature gas.

12. The system of claim 11, wherein the sludge comprises at least one of digested sludge, undigested sludge, fresh animal waste, aged animal waste, or agricultural food waste.

13. The system of claim 11, wherein the heater comprises an air-heater jacket operable to receive the pre-heated gas from the pre-heater, and wherein the air-heater jacket is further operable to cause the pre-heated gas to travel over at least a portion of a surface of the heater.

14. The system of claim 11, wherein the first tapping duct is operable to recirculate a majority of the heated gas received at the tapping duct.

15. The system of claim 11, wherein the pre-heater is operable to pre-heat the reduced-temperature gas using at least a portion of the heated gas that is not directed to the at least one of the mill or grinder by the tapping duct.

16. The system of claim 15, wherein the at least a portion of the heated gas that is not directed to the at least one of the mill or grinder is removed from the system.

17. The system of claim 11, wherein the heater comprises a burner operable to burn a mixture of ambient air and at least a portion of the dried powder.

18. The system of claim 17, wherein the burner is further operable to burn a gas or oil.

19. The system of claim 17, further comprising a mixing valve operable to combine the mixture of ambient air and the at least a portion of the dried powder with a portion of the heated gas not directed to the at least one of the mill or grinder by the first tapping duct.

20. The system of claim 19, further comprising a second tapping duct operable to direct, to the mixing valve, the portion of the heated gas not directed to the at least one of the mill or grinder.

21. A method for processing dewatered sludge, the method comprising:

reducing, in at least one of a mill or grinder, a moisture content of a dewatered sludge by breaking the dewatered sludge into a dried powder in the presence of high-temperature gas, wherein the high-temperature gas absorbs at least a portion of the moisture content of the dewatered sludge to form at least partially saturated gas;

separating the dried powder from the at least partially saturated gas;

reducing a moisture content of the at least partially saturated gas by reducing a temperature of the at least partially saturated gas to form a reduced-temperature gas;

pre-heating the reduced-temperature gas to form pre-heated gas;

heating the pre-heated heated gas to form heated gas;

separating at least a portion of ash contained in the heated gas from the heated gas; and

recirculating at least a portion of the heated gas by directing the at least a portion of the heated gas to the at least one of the mill or grinder, wherein the at least a portion of the heated gas is to be used in the at least one of the mill or grinder as the high-temperature gas.

22. The method of claim 21, wherein a majority of the heated gas is recirculated to the at least one of the mill or grinder.

23. The method of claim 21, wherein separating the dried powder from the at least partially saturated gas is performed using a first cyclone separator, and wherein separating at least a portion of the ash contained in the heated gas from the heated gas is performed using a second cyclone separator.

24. The method of claim 21, wherein heating the pre-heated heated gas is performed using a burner operable to burn a mixture of ambient air and at least a portion of the dried powder.

25. The method of claim 24, further comprising combining the mixture of ambient air and the at least a portion of the dried powder with a portion of the heated gas not directed to the at least one of the mill or grinder.

26. The method of claim 24, wherein a weight of the ambient air is equal to a weight of the portion of the heated gas that is not directed to the at least one of the mill or grinder.

27. The method of claim 21, wherein heating the pre-heated gas is performed using a heater comprising an air-heater jacket, and wherein the air-heater jacket is operable to cause the pre-heated gas to travel over at least a portion of a surface of the heater.

28. The method of claim 21 further comprising pre-heating the dewatered sludge before reducing, in the at least one of the mill or grinder, the moisture content of a sludge by breaking the sludge into the dried powder in the presence of high-temperature gas.