CA2631210A1 - Cooling system for carpet/wood ash - Google Patents
Cooling system for carpet/wood ash Download PDFInfo
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- CA2631210A1 CA2631210A1 CA002631210A CA2631210A CA2631210A1 CA 2631210 A1 CA2631210 A1 CA 2631210A1 CA 002631210 A CA002631210 A CA 002631210A CA 2631210 A CA2631210 A CA 2631210A CA 2631210 A1 CA2631210 A1 CA 2631210A1
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- waste product
- ash
- inert gas
- storage unit
- nitrogen
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J1/00—Removing ash, clinker, or slag from combustion chambers
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
- F23G7/00—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals
- F23G7/10—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals of field or garden waste or biomasses
- F23G7/105—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals of field or garden waste or biomasses of wood waste
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J2900/00—Special arrangements for conducting or purifying combustion fumes; Treatment of fumes or ashes
- F23J2900/01003—Ash crushing means associated with ash removal means
Abstract
A method and system transfer, cool, store, and load an ash waste product of a gasification process. Hot ash is moved toward a storage silo via one or more augers and/or conveyors. Ash may be sent through a means for reducing the size of any ash chucks, such as roller crushers. The ash may be transferred via a first auger affixed with a glycol/water indirect cooling means. The ash may then be transferred to a second auger, also having a glycol/water indirect cooling means, but further being operable to blanket the ash with an inert gas, such as slightly pressurized nitrogen.
Then, the ash may be transferred to a storage silo via a continuous flow bucket conveyor. The silo and conveyor may be operable to maintain the ash blanketed with inert gas. Subsequently, the ash may be unloaded from the silo, such as into a vehicle, via a retractable spout.
Then, the ash may be transferred to a storage silo via a continuous flow bucket conveyor. The silo and conveyor may be operable to maintain the ash blanketed with inert gas. Subsequently, the ash may be unloaded from the silo, such as into a vehicle, via a retractable spout.
Description
COOLING SYSTEM FOR CARPET/WOOD ASH
PRIORITY AND CROSS-REFERENCE TO RELATED APPLICATION
[00011 This application claims the benefit of the filing date under 35 U.S.C.
119(e) of Provisional U.S. Patent Application Serial No. 60/938,310, filed on May 16, 2007, entitled "Cooling System for Carpet/Wood Ash," which is incorporated by reference in its entirety herein.
FIELD OF THE INVENTION
[00021 The present invention relates generally to the production of energy.
More particularly, the invention relates to a method and system for transferring, cooling, storing, and unloading ash generated from a gasification process or other thermal conversion process.
BACKGROUND OF THE INVENTION
10003] Thermal conversion processes may generate waste products that are difficult to dispose of. An exemplary thermal conversion process is gasification.
Gasification is the process of converting solid carbonaceous or other biomass fuel into a synthetic gas. In this process, the resultant "synthetic" gas may be burned to produce steam.
100041 The gasification process may produce ash. The ash may drop from the bottom of the gasifier and contain a high amount of carbon, which makes the ash somewhat combustible. The ash may contain varying quantities of calcium oxide, which reacts exothermically with water. The ash may exit the gasifier at high temperatures, as the gasifier temperature may be at least 1600 F. In typical biomass gasification systems, the ash may be sprayed with water to reduce the temperature of the ash. Due to the high carbon content of the ash, the ash may smolder and/or ignite if not sufficiently moistened and/or cooled.
[0005] Several problems may result from known water spray ash handling systems, including those identified directly below.
[00061 1. When water is sprayed on the ash, a mud-like slurry may be created.
The mud may build up on various pieces of equipment, including the inside of an ash or other waste product storage silo, and eventually harden. The build up of mud may reduce the effective size of the conveyance and storage equipment, as well as clog rotating or moving equipment.
[00071 2. When water is sprayed onto the ash, an exothermic reaction may occur, re-igniting unconsumed carbon in the ash stream.
[ooosl 3. When water is not added to the system, clumps of ash, which may include carbon, calcium oxide and pieces of melted biomass fuel (such as melted carpet fibers in one aspect that uses waste carpet as a biomass fuel), may continue to smolder after introduction into the ash silo. This may re-ignite other unconsumed carbon in the ash stream.
[00091 4. When ash is unloaded from the silo into a covered truck: (a) large amounts of hot ash may become airborne, creating a severe dust hazard and greatly reducing visibility during the ash unloading process; (b) the hot, moist air from the wetted ash may emerge from the truck openings, creating a hazardous stream of very hot gases (the steam itself may be a burn hazard for system operators, and the steam may further reduce visibility while unloading the ash from the silo into the truck); and (c) during ash unloading, ash may ignite, both in the silo and as it passed from the silo into the truck receptacle, creating a burn hazard during the ash unloading process.
BRIEF SUMMARY
[00101 The present embodiments provide a method and system for the transferring, cooling, storing, and unloading a waste product of a thermal conversion process. For example, the method and system may accept an ash waste product of a gasification process. The hot ash received may be moved toward a storage silo via one or more augers and/or conveyors. The ash may be sent through a means for reducing the size of any ash chucks, such as roll or roller crushers. The ash may be initially transferred via a first auger affixed with an indirect glycol/water cooling means. The ash may then be transferred to a second auger, also having an indirect glycol/water cooling means, but further being operable to blanket the ash with an inert gas, such as slightly pressurized nitrogen. The second auger may transfer the ash to a continuous bucket conveyor that in turn delivers the ash to a storage silo.
Both the silo and bucket conveyor also may be operable to maintain the ash blanketed with inert gas.
[0011] Subsequently, the ash may be unloaded from the silo, such as into a vehicle receptacle, via a retractable spout. Various relief values may be employed to ensure safe operation. In one embodiment, the gasification process accepts only carpet waste and wood as fuel. For instance, a gasification system may convert industrial carpet waste and wood flour/wastes into production steam, such as disclosed by U.S.
Application Serial No. 11/052,634, filed February 7, 2005, which is incorporated herein by reference in its entirety. The carpet may be shredded, mixed with wood flour and/or other waste, and gasified.
[00121 In one aspect, a method transfers a waste product generated from a thermal conversion process. The method includes transferring and/or storing a waste product of a gasification process under a blanket of inert gas.
[00131 In another aspect, a method transfers a waste product generated from a thermal conversion process. The method includes crushing a waste product of a thermal conversion process with a roller crusher, blanketing the waste product with an inert gas, and transferring the waste product with a continuous bucket conveyor to a storage unit.
[00141 In another aspect, a system transfers a waste product generated from a thermal conversion process. The system includes a roller crusher operable to crush a waste product of a thermal conversion process and means for blanketing the waste product with an inert gas.
[00151 Advantages of the present invention will become more apparent to those skilled in the art from the following description of the preferred embodiments of the invention which are shown and described by way of illustration. As will be realized, the invention is capable of other and different embodiments, and its details are capable of modification in various respects. Accordingly, the drawings and description are to be regarded as illustrative in nature and not as restrictive.
BRIEF DESCRIPTION OF THE DRAWINGS
100161 FIGS. 1 and 1 a are a schematic illustration of an exemplary ash transfer, cooling, storage, and unloading system;
[00171 FIGS. 2 and 2a are a schematic illustration of another exemplary ash transfer, cooling, storage, and unloading system;
[0018] FIG. 3 is a schematic illustration of an exemplary nitrogen generation and storage system; and [00191 FIG. 4 is a block diagram flowchart of one embodiment of a method for transferring, cooling, storing, and unloading a waste product generated from a thermal conversion process.
DETAILED DESCRIPTION
[00201 The present embodiments provide a method and system for transferring, cooling, storing, and unloading a waste product of a thermal conversion process. In one embodiment, the thermal conversion process is a gasification process and the waste product is ash generated from gasification. In another embodiment, the biomass fuel used during the gasification process is a mixture of carpet waste and wood flour, such as described by U.S. Application Serial No. 11/052,634.
1. Exemplary Thermal Conversion Process and Biomass Fuels 100211 The process of gasification may be used to generate steam, such as application steam for use by turbines. Gasification is the thermal conversion of a solid biomass fuel into a hot (over 1,000 F) synthesis gas that contains combustible gases, such as methane, hydrogen, carbon monoxide, and/or other gases. In the process of gasification, or the conversion of a solid biomass fuel into a gas, there may be an insufficient amount of oxygen to completely burn the biomass.
[00221 The purpose of gasification and the resultant process conditions may be significantly different than the purpose and operating conditions of an incinerator. In an incinerator, the intent may be to totally burn the solid feed within the confines of the incinerator. On the other hand, the intent of gasification may be to produce a gas for use external to a gasifier, as well as controlling the gasifier emissions to improve any impact on the environment. Additionally, ash generated from gasification as a by-product that is subsequently disposed in an engineered landfill may be biologically inert depending upon which gasification process is used, or at least not a significant source of toxins. Gasification may result in significant material reduction, such that required landfill space is reduced. Accordingly, the process of gasification may have multiple environmental benefits.
[0023] In one aspect, a fabric material having a backing, such as carpet, may be used as a biomass fuel for gasification. The term "carpet" as used herein may encompass any item that has been manufactured from at least two different types of material, one material being a fabric or other covering and another material being a synthetic material, such as rubber or a polymer. For instance, carpet in this context may include standard floor carpet, floor mats, wall coverings, rugs, and the like, as well as industrial carpet waste and segregated, used post-consumer carpet waste.
[0024] Carpet waste may be provided to the system in the form of bales. In general, bales are the end product of a compaction process that is used to decrease the volume that a material occupies by increasing the density and weight. Bales are typically bound with bands or wire to keep the baled material from separating.
Bales may be rectangular, square, round, or have other shapes. Baled carpet may enhance the ease of the delivery and movement of the waste carpet. Landfill owners and/or operators may also provide incentives for baling of carpet to reduce the volume requirement of the landfill. Alternatively, the carpet is loose or not compacted.
[00251 The carpet waste may be shredded and substantially or mostly separated into carpet fines and carpet fibers. The carpet fines may have value as a raw material to the carpet manufacturer, and the carpet fines are detrimental to a gasification process since there is little available heating value. Therefore, the removal and storage of carpet fines may have economic, environmental and/or process efficiency value. The primarily carpet fines may be moved within a first waste product stream to a first silo for storage. The primarily carpet fibers may be used as a biomass fuel, either alone or mixed with another biomass fuel component. The biomass fuel may be utilized by a gasifier to produce synthetic gas and generate hot ash as a by-product.
Subsequently, the synthetic gas may be used to produce electricity, such as via either a combustion turbine or a synthetic gas burner and a boiler.
[0026] The ash produced from gasification may be moved within a second waste product stream to a second silo for storage. The first and second waste product streams may be distinct such that the primarily carpet fines, isolated to the first waste product stream, and the ash, isolated to the second waste product stream, remain separated at least until the ash cools down to approximately the melting point of the carpet fines.
[00271 Using carpet waste as a biomass fuel for gasification may produce a number of benefits. For example, the use of waste carpet to generate application steam may reduce reliance upon other sources of energy, such as coal and natural gas, which are limited in supply. Moreover, expending a significant portion of waste carpet as a fuel during gasification may reduce the total volume of waste carpet products that ultimately are deposited in landfills. Therefore, the present invention may provide environmental benefits that conventional steam generation processes or carpet disposal methods lack.
[00281 Exemplary schematics of a gasification system are shown in U.S.
Application Serial No. 11/052,634.
II. Exemplary Transfer, Cooling, Storing, and Unloading System [00291 The present embodiments relate to a method and system that may safely transfer, cool, store and unload ash free of or without a water spray. In an initial ash auger, ash may be indirectly cooled using a screw auger with a central channel through which a cooled glycol/water mix is passed The ash may then pass through a roll or roller crusher, which breaks up smoldering embers. A rotary air lock may allow the downstream components of the system to be pressurized with nitrogen or other inert gas A second cooling auger may transfer the ash into a continuous bucket elevator, which may directly or indirectly move the ash toward or into a storage silo.
The second ash cooling auger, bucket elevator and silo may be blanketed with an inert gas, such as nitrogen.
100301 The two augers used to convey the ash from the gasifier to the silo may both be indirectly cooled with a glycol/water mix. Conventional glycol/water indirect cooled screw augers are known in the material handling industry and may be used.
[0031] The first glycol/water indirect cooled auger may be kept at ambient or slightly negative pressure. The first auger may be designed to cool the ash enough such that the ash may be discharged into a rotary air lock and/or roller crusher. In one aspect, the first auger may feed the rotary air lock, and then the roller crusher.
Alternatively, the equipment order may be changed, such that the roller crusher may be positioned before and come first within the system, followed by the rotary air lock.
[0032] The purpose of the roller crusher may be to break up any smoldering embers, allowing the embers to be extinguished by a nitrogen, or other inert gas, blanketing system before reaching the silo. The roller crusher may be a dual roll crusher and consist of a pair of steel rollers, separated by a gap of approximately 1/4"
inch. Alternatively, the roller crusher may use either a larger or smaller gap. One of the rollers may be fixed, and the other roller may be mounted on a rigid spring such that some relief or movement is provided in the event that non-crushable material or items, such as a steel bolt, were to move through the system.
100331 The roller crusher may be placed prior to the air lock. If the roller crusher is placed in the nitrogen-pressurized area, then both rollers may have to be fixed in place. For example, if one roller is allowed to move, then nitrogen may leak out along the shaft of that roller. By placing the roller crusher outside (before) the nitrogen pressurized zone of the ash system, the second roller may be moveable without nitrogen leakage concerns.
[0034] After the roller crusher, the ash may move through a rotary air lock.
The remainder of the ash conveyance, storage and unloading system may be at least slightly pressurized with nitrogen, or other inert gas, to eliminate and/or reduce smoldering and/or combustion of the ash. Nitrogen, or another inert gas, may be introduced into the system at various points along the system. In one aspect, nitrogen is introduced into the second glycol/water indirect cooled screw conveyer, the bucket elevator, and the silo.
[0035] Once the ash passes through the rotary air lock, the ash may be conveyed to the bucket elevator by the second glycol/water indirect cooled screw conveyor/auger. The second conveyor may further cool the ash.
[0036] The bucket elevator may be a continuous flow bucket elevator, rather than a centrifugal bucket elevator. A centrifugal bucket elevator may move very quickly and sling the product out of the buckets and into the discharge chute. This process may churn up the ash and increase the possibility of ash combustion. On the other hand, a continuous bucket elevator may move much more slowly, tipping over the full buckets and allowing gravity to empty them. The continuous bucket elevator may minimize the amount of ash that will become airborne in the silo, as well as reduce the likelihood of combustion within the silo.
[0037] The present embodiments also include a modified silo unloading process and equipment to ensure that the ash may be safely discharged from the silo into an enclosed truck. The silo unloading process may be free of, i.e., not use, a final water spray when the ash moved from the silo into a truck receptacle below. Instead, the system and method may include a retractable discharge spout with an annular vent space. The retractable tube-within-a-tube may extend from the bottom of the silo to the truck. The dry ash may fall into the truck via the center tube of the spout. An annular space surrounding the tube may suck a mixture of nitrogen and air out of the truck as the ash falls, providing pressure relief. The use of this type of retractable discharge spout may eliminate the previous problem of dust blowing up out of the truck as the ash was loaded into it. A bag-house dust collector may remove the ash from this air stream. Nitrogen may be used to pulse or shake the bags, so that the protective nitrogen blanket extends all the way to the bag house.
[0038] Prior to ash unloading, the enclosed truck container may be purged with nitrogen for a period of time, such as for approximately ten minutes. The nitrogen purge may ensure that there is little oxygen in the truck receptacle when the ash is loaded into it. The nitrogen purge and accompanying oxygen removal may reduce the likelihood of any remaining embers or hot spots igniting the ash when the truck receptacle is filled.
[0039] This ash cooling system may work well for any ash that, for whatever reason, cannot be easily cooled with a water spray system. Powdery ash, that would create a plaster-like coating on equipment when moistened, or ash that otherwise has chemical or physical constraints that may eliminate the possibility of a water spray system, could benefit from this ash cooling method.
[0040] Therefore, the present embodiments may use a unique combination of equipment that provides for and includes: (1) a roller crusher, (2) nitrogen blanketing of an ash system, either completely or a portion thereof, (3) a continuous bucket conveyor, and (4) a retractable ash spout. The present embodiments may implement this equipment simultaneously and in various combinations to handle an ash cooling and storage situation.
III. Exemplary Ash Storage and Transfer [0041] Figure 1 illustrates an exemplary waste product transfer, cooling, storage, and loading system 100. The system 100 may include an ash conveyor 102, a first auger 104, a second auger 106, a continuous bucket conveyor 108, a storage silo 110, and a nitrogen supply system 122. The system may include additional, fewer, or alternate components.
[0042] The ash conveyor 102 may accept ash produced from a gasification process and transfer the ash to a first auger 104. The first auger 104 may be a first ash screw auger. A cooled water/glycol mix may pass through the center of the screw, thus cooling the ash that is moved through the auger 104.
[0043] The air lock 118 may separate the nitrogen-pressured portion of the ash system from the slightly negatively pressurized gasification unit and first ash cooling screw auger 104. The air lock 118 may be repositioned to be above or below the roller crusher 120. The roller crusher 120 may reduce or eliminate any chunks of smoldering ash. Figures 1 and 1 a together illustrate that the sequencing of the air lock 118 and roller crusher 120 may be interchangeable. In a preferred embodiment, the roller crusher 120 is positioned prior to or upstream of the air lock 118.
[0044] After passing through the air lock 118 and roller crusher 120, the ash may be transferred to a second auger 106. The second auger 106 may be a second ash screw auger. Like the first auger 104, a cooled water/glycol mix passes through the center of the screw, thus cooling the ash that is moved through the second auger 106.
Alternatively, the cooled glycol/water mix may pass through an outer jacket or sleeve associated with the second auger 106. The second auger 106 may be slightly pressurized with nitrogen, such as up to a few inches of water column to displace oxygen, to smother any burning embers. In one aspect, nitrogen is used as a non-flamable gas. Other inert gases may be used, such as carbon dioxide, neon, helium, argon, krypton, xenon, radon, noble gases, or other gases operable to displace oxygen.
The term inert gas used herein shall include noble gas. Any non-flamable gas operable to displace oxygen may be used.
[0045] As shown, a cooling glycol/water supply 114 and cooling glycol/water return 116 may be provided. The supply 114 may send cooling glycol/water into a center sleeve (or alternatively an exterior jacket around the interior) of either the first 104 or second 106 augers, or both. The return 116 may receive spent cooling glycol/water from the first 104 and/or second 106 auger. Nitrogen 122, or other inert/noble gas, may be supplied to the second auger 106.
[0046] The second auger 106 may transfer ash or other waste products to a continuous-flow ash bucket elevator 108. The bucket elevator 108 may be slightly pressured with nitrogen (or other inert or noble gases). Explosion panels may be installed on the sides of the elevator 108, to allow for safe pressure relief in the event of a high-pressure incident.
[0047] A pressure relief valve 124 may be positioned at the top of the bucket elevator 108. The relief valve 124 may allow for safe pressure relief in the event of a high-pressure incident.
[0048] The ash may be transferred to an ash silo 110 via the bucket elevator directly, or indirectly via an intermediate conveyor/auger 132. The ash silo 110 may be slightly pressured with nitrogen via the nitrogen supply 122. The ash silo 110 may have an emergency pressure relief valve 130 located at or near the top of the silo 110.
The relief valve 130 may ensure that, if there was a high-pressure incident in the silo 110, the pressure would vent safely through the top of the silo 110.
[0049] The silo 110 may have a secondary pressure relief valve 128 at or near the top of the silo 110 that may relieve the silo pressure if the silo pressure was abnormally high, but not high enough to trigger an emergency venting via the primary emergency pressure relief valve 130. The silo 110 may have a dust collector 126 at or near the top of the ash silo I 10. The dust collector 126 may operate to protect the pressure relief valve 128 at the top of the silo 110.
[0050] The silo 110 may have a set of three vibratory shakers 132 that facilitate the movement of the ash from the silo 110. The bottom of the silo 110 may have an air lock 134 that allows for the silo 110 to be pressurized, and prevents the nitrogen supplied from the nitrogen supply 122 from escaping through an unloading spout when the unloading spout 134 is not in operation.
[0051] The bottom of the silo 110 may be associated with the ash unloading spout 134. The unloading spout 134 may allow for clean, safe and easy discharge of the ash, or other waste products, from the silo into an ash or other container 112. The unloading spout 134 may be retractable and may include an annular vent space.
In one embodiment, the spout 134 may function as a retractable tube-within-a-tube and may extend from the bottom of the silo to the truck receptacle during use. The dry ash may fall into the truck receptacle via a center tube of the spout 134. The annular space surrounding the center tube may vent gases, such as a mixture of nitrogen and air, out of the truck receptacle as the ash falls, providing pressure relief and dissipation of gasses into the atmosphere.
[0052] The unloading spout 134 may have an associated dust collector 136. The dust collector 136 may capture the relief air that passes through the unloading spout 134, and removes airborne particulate from the relief air.
[0053] The nitrogen supply 122 line may include various fire suppression techniques that consume nitrogen. These may include nitrogen lines extending to various dust collector bags. Because the dust collector(s) may be in the nitrogen-pressurized area, it may be preferable to use compressed nitrogen for bag cleaning, instead of compressed air.
100541 One nitrogen supply 1221ine may go toward a truck purge, operable to fill the ash container with nitrogen prior to ash unloading. Note that this line may receive high or low pressure nitrogen. Another nitrogen supply 122 line may go to a roller crusher, to pressurize the roller crusher and ash cooling auger with nitrogen.
Another nitrogen supply 122 line may go to the bottom of the ash bucket elevator, to pressurize the bucket elevator and ash cooling auger with nitrogen. A number of nitrogen supply 1221ines, such as four or more, may go to the ash silo 110 to pressurize the ash silo 110 with nitrogen.
100551 In one embodiment, the ash conveyor 102, the first auger 104, the second auger 106, the rotary air lock 118, the dual roller crusher 120, and the bucket elevator 108 may be operable to transfer ash at a rate of 2,000 lbs/hr. The roller crusher 120 may use a 20 horse power, 1,800 rpm motor. The rotary air lock 118 may use a 1.5 horse power, 1,800 rpm motor. The first and second augers 104, 106 may each use a horse power, 1,800 rpm motor. The bucket elevator 108 may use a 3 horse power, 1,800 rpm motor. The ash silo 110 may have a 12 feet diameter and 25 feet length, providing for 3,000 cubic feet of storage. The discharge air lock 134 may be operable to discharge ash at a rate of 28,0001b/hr. The discharge rotary air lock 134 may use a 2 horse power, 1,800 rpm motor. The vibratory dust collectors 132 may have associated 1.0 horse power, 3,500 rpm motors.
100561 Figure 2 illustrates another exemplary waste product transfer, cooling, storage, and unloading system 200. Specifically, Figure 2 shows another exemplary view of the physical positions of the different pieces of equipment, and how the transfer, cooling, storing, and unloading system components may be incorporated into/interconnected with a gasification system. The system 200 may include a storage unit 202, a conveyor 204, a gasifier 206, a startup burner 208, a vent stack 210, a duct 212, a cyclone 214, a second conveyor 216, a first auger 218, an air lock 220, a roller crusher 222, a second auger 224, a continuous conveyor 226, a storage unit 228, a second air lock 230, and an unloading spout 232. The system may include an interconnected inert gas system (not shown). The system may include additional, fewer, or alternate components.
[00571 A biomass fuel may be stored in the storage unit 202 and transferred via a conveyor 204 into a gasifier 206 interconnected with a startup burner 208. The gasifier 206 may have a vent stack 210 and ducting 212 leading to a cyclone 214.
The cyclone 214 may be operable to deliver an ash waste product into a conveyor or auger 216. The conveyor or auger 216 may transfer the ash to a first auger 218 associated with an air lock 220 and roll crusher 222. Figures 2 and 2a together illustrate that the sequencing of the air lock 220 and roller crusher 222 may be interchangeable. In a preferred embodiment, the roller crusher 222 is positioned prior to the air lock 220.
[00581 After the ash exits the first auger 218 and passes thru the roll crusher 222, the ash may be sent to the second auger 224. Downstream of the air lock 220, the system may be operable to blanket the ash with nitrogen or another inert gas.
The second auger 224 may deliver the ash to the bucket elevator 226, which in turns may transfer the ash to the silo 228. The silo 228 may have a second air lock 230 such that the silo 228 may be operable to expose the ash within the silo 228 to slightly pressurized nitrogen or another inert gas. The bottom of the silo 228 may be associated with a retractable unloading sprout 232.
[0059] The first auger 218, second auger 224, retractable spout 232, and other components shown in Figure 2 may correspond to the components shown and described above with respect to Figure 1. Other components may be used.
IV. Exemplary Nitrogen System [0060] Figure 3 illustrates an exemplary nitrogen generation and storage system 300. The system 300 may include a nitrogen generator 302, a dryer/filter 304, a receiver 306, a trap 308, a compressor 310, and a tank 312. The nitrogen system may include additional, fewer, or alternate components. Although Figure 3 represents the layout of nitrogen-generating equipment associated with one aspect of the present embodiments, it should be noted that any method of generating nitrogen or any other inert gas may used. For instance, inert gas may be purchased from a supplier and stored within a storage tank interconnected with the waste product transferring, cooling, storing, and unloading system for subsequent use.
100611 A compressor 310 may be used to generate compressed air supplied to the nitrogen generation system. Compressed air generated may pass through a dryer and/or a filter 304 to remove moisture and/or impurities. Compressed air generated and dried may be temporarily collected in a receiver 306. The receiver 306 may have a trap or drain 308 to further remove moisture and/or impurities from the system. The nitrogen generator 302 may convert the compressed dry air into nitrogen gas.
The storage tank 312 may feed the nitrogen supply 122 lines of Figure 1 and may be associated with various valves for bringing the nitrogen supply system on and off line.
V. Exemplary Method [00621 Figure 4 illustrates an exemplary method of transferring, cooling, storing, and unloading a waste product of a thermal conversion process 400. The method may include roller crushing a waste product 402, blanketing the waste product within at least a portion of the system with an inert gas 404, transferring the waste product within the system toward a storage unit via a continuous bucket conveyor 406, and/or unloading the waste product from the storage unit via a retractable spout 408.
The method may be accomplished using the embodiments and components discussed with respect to Figures 1-3 above. The method may include additional, fewer, or alternate steps.
[00631 In one aspect, the method may provide for the transfer, as well as the cooling, storing, and/or unloading, of a gasification waste product with the waste product being blanketed with an inert gas. The method may include crushing the waste product with a roller crusher, such that extinguishing smolders within the waste product is facilitated by the inert gas displacing oxygen in the vicinity of the waste product. After which, the method may include (1) transferring the waste product with a continuous bucket conveyor to a storage unit and (2) subsequently, unloading the waste product from the storage unit via a retractable spout. The waste product may be unloaded from the storage unit into a mobile receptacle, such as a truck or railcar.
The mobile receptacle may under another blanket of inert gas before, during, and/or after unloading.
[0064] The method may include applying the blanket of inert gas to the waste product in one or more glycol/water mix indirectly cooled augers that cool the waste product as the waste product is being transferred. In one embodiment of the method, the inert gas is nitrogen. Other gasses may be used.
[0065] Another embodiment of the method may include crushing a waste product of a thermal conversion process with a roller crusher, blanketing the waste product with an inert gas, and/or transferring the waste product with a continuous bucket conveyor to a storage unit. The method may include unloading the waste product from the storage unit via a retractable spout. The blanket of inert gas may be applied to the waste product in a glycol/water mix indirect cooled auger that cools the waste product as it is being transferred. Alternatively or in addition, the waste product may be placed under a blanket of inert gas during unloading from the storage unit and/or during storage in the storage unit such that the waste product is prevented from re-igniting during unloading and/or storage as oxygen in the vicinity of the waste product is displaced from any smolders or embers of the waste product.
[0066] The method and system may use means for blanketing the waste product with an inert gas, such as one or more conveyors and/or augers operable to transfer the waste product and blanket the waste product with an inert gas, a storage unit being operable to blanket the waste product with an inert gas, and/or a mobile receptacle being operable to blanket the waste product with an inert gas.
[0067] Although the above embodiments are described, there are many possible equipment configurations which may be designed and utilized. For example, the synthetic gas produced by the gasifier shown in Figure 2 may be fired in one or two stages and the flue gas directed to a boiler to produce medium or high-pressure steam.
The high-pressure steam may then be used to drive steam turbines for the production of electricity. Alternatively, the combustion of cleaned synthetic gas in a combustion turbine also may generate electricity.
[00681 In one aspect, the method may use carpet waste and wood flour as a biomass fuel during a gasification process. The method may include sizing a fabric material having a backing, such as by shredding, cutting, tearing, or grinding the fabric material, separating the shredded or sized fabric material into constituent fabric and backing components, storing the backing component in a first storage unit, storing the fabric component in a third storage unit, optionally storing another biomass fuel component fuel component in a fourth storage unit, optionally mixing the fabric component with another biomass fuel component, gasifying the fabric component, and storing the ash generated from gasification as a by-product in a second storage unit. The method may have other variations, including those with fewer, additional, or alternate steps.
[00691 In one embodiment, carpet or another fabric material having a backing is used as a biomass fuel component, such as disclosed by U.S. Application Serial Number 11/052,634, which is incorporated herein by reference in its entirety.
The fabric material is shredded and substantially separated into constituent backing and fabric components. The backing component is stored in a first storage unit.
The fabric component may be mixed with another biomass fuel component before introduction into a gasifier. The gasifier produces synthetic gas, which is subsequently used to produce steam. The hot ash generated as a by-product of gasification is stored in a second storage unit. Each waste product may be confined to a distinct waste path such that the waste products remain isolated from each other, at least until the ash cools down to approximately the melting point of the backing component.
[00701 In another embodiment, the method may include providing fabric material having a backing, such as carpet, as a biomass fuel for gasification, shredding or sizing the carpet into pieces approximately one square inch in size, and substantially separating or sizing the shredded carpet into primarily carpet fibers and primarily carpet fines, such as by a vibratory separator or a step separator.
Subsequently, the primarily carpet fines may be moved by one or more additional conveyors to a first storage unit and the primarily carpet fibers may be moved to and stored in an intermediate storage unit.
[00711 The method may further include providing the separated carpet fibers as a biomass fuel to a gasifier and producing synthetic gas from gasification and generating ash as a by-product. The method also may include moving the ash generated from gasification to a second storage unit, such as a silo. The ash may be moved by at least one additional conveyor. The first and second storage unit may each be part of a distinct waste product path such that the separated carpet fines and ash are isolated from each other for a period of time. As a result, neither waste product is contaminated by or affected by the other waste product, at least until the ash cools to or below the melting point of the carpet fines.
[00721 The method may include mixing the separated carpet fibers with one or more additional biomass fuel components before the introduction of the biomass fuel into the gasifier. Any additional biomass fuel component may be pre-sized and not require any cutting or shredding. For example, the available additional biomass fuel components may include agricultural residues or wood-based fuels, such as pellets, wood chips, wood flour, or sawdust. The additional biomass fuel components may be stored in a third storage unit before mixture with the carpet fibers and subsequent introduction into the gasifier.
[0073] The method may include cooling and scrubing the synthetic gas produced by gasification, burning the synthetic gas in a burner, and heating a boiler to generate application steam via the burner. The method also may include preheating the boiler feedwater by using an economizer. Alternatively, the synthetic gas may be used by a combustion turbine or another utility to generate electricity.
[00741 While the preferred embodiments of the invention have been described, it should be understood that the invention is not so limited and modifications may be made without departing from the invention. The scope of the invention is defined by the appended claims, and all devices that come within the meaning of the claims, either literally or by equivalence, are intended to be embraced therein.
[0075) It is therefore intended that the foregoing detailed description be regarded as illustrative rather than limiting, and that it be understood that it is the following claims, including all equivalents, that are intended to define the spirit and scope of this invention.
PRIORITY AND CROSS-REFERENCE TO RELATED APPLICATION
[00011 This application claims the benefit of the filing date under 35 U.S.C.
119(e) of Provisional U.S. Patent Application Serial No. 60/938,310, filed on May 16, 2007, entitled "Cooling System for Carpet/Wood Ash," which is incorporated by reference in its entirety herein.
FIELD OF THE INVENTION
[00021 The present invention relates generally to the production of energy.
More particularly, the invention relates to a method and system for transferring, cooling, storing, and unloading ash generated from a gasification process or other thermal conversion process.
BACKGROUND OF THE INVENTION
10003] Thermal conversion processes may generate waste products that are difficult to dispose of. An exemplary thermal conversion process is gasification.
Gasification is the process of converting solid carbonaceous or other biomass fuel into a synthetic gas. In this process, the resultant "synthetic" gas may be burned to produce steam.
100041 The gasification process may produce ash. The ash may drop from the bottom of the gasifier and contain a high amount of carbon, which makes the ash somewhat combustible. The ash may contain varying quantities of calcium oxide, which reacts exothermically with water. The ash may exit the gasifier at high temperatures, as the gasifier temperature may be at least 1600 F. In typical biomass gasification systems, the ash may be sprayed with water to reduce the temperature of the ash. Due to the high carbon content of the ash, the ash may smolder and/or ignite if not sufficiently moistened and/or cooled.
[0005] Several problems may result from known water spray ash handling systems, including those identified directly below.
[00061 1. When water is sprayed on the ash, a mud-like slurry may be created.
The mud may build up on various pieces of equipment, including the inside of an ash or other waste product storage silo, and eventually harden. The build up of mud may reduce the effective size of the conveyance and storage equipment, as well as clog rotating or moving equipment.
[00071 2. When water is sprayed onto the ash, an exothermic reaction may occur, re-igniting unconsumed carbon in the ash stream.
[ooosl 3. When water is not added to the system, clumps of ash, which may include carbon, calcium oxide and pieces of melted biomass fuel (such as melted carpet fibers in one aspect that uses waste carpet as a biomass fuel), may continue to smolder after introduction into the ash silo. This may re-ignite other unconsumed carbon in the ash stream.
[00091 4. When ash is unloaded from the silo into a covered truck: (a) large amounts of hot ash may become airborne, creating a severe dust hazard and greatly reducing visibility during the ash unloading process; (b) the hot, moist air from the wetted ash may emerge from the truck openings, creating a hazardous stream of very hot gases (the steam itself may be a burn hazard for system operators, and the steam may further reduce visibility while unloading the ash from the silo into the truck); and (c) during ash unloading, ash may ignite, both in the silo and as it passed from the silo into the truck receptacle, creating a burn hazard during the ash unloading process.
BRIEF SUMMARY
[00101 The present embodiments provide a method and system for the transferring, cooling, storing, and unloading a waste product of a thermal conversion process. For example, the method and system may accept an ash waste product of a gasification process. The hot ash received may be moved toward a storage silo via one or more augers and/or conveyors. The ash may be sent through a means for reducing the size of any ash chucks, such as roll or roller crushers. The ash may be initially transferred via a first auger affixed with an indirect glycol/water cooling means. The ash may then be transferred to a second auger, also having an indirect glycol/water cooling means, but further being operable to blanket the ash with an inert gas, such as slightly pressurized nitrogen. The second auger may transfer the ash to a continuous bucket conveyor that in turn delivers the ash to a storage silo.
Both the silo and bucket conveyor also may be operable to maintain the ash blanketed with inert gas.
[0011] Subsequently, the ash may be unloaded from the silo, such as into a vehicle receptacle, via a retractable spout. Various relief values may be employed to ensure safe operation. In one embodiment, the gasification process accepts only carpet waste and wood as fuel. For instance, a gasification system may convert industrial carpet waste and wood flour/wastes into production steam, such as disclosed by U.S.
Application Serial No. 11/052,634, filed February 7, 2005, which is incorporated herein by reference in its entirety. The carpet may be shredded, mixed with wood flour and/or other waste, and gasified.
[00121 In one aspect, a method transfers a waste product generated from a thermal conversion process. The method includes transferring and/or storing a waste product of a gasification process under a blanket of inert gas.
[00131 In another aspect, a method transfers a waste product generated from a thermal conversion process. The method includes crushing a waste product of a thermal conversion process with a roller crusher, blanketing the waste product with an inert gas, and transferring the waste product with a continuous bucket conveyor to a storage unit.
[00141 In another aspect, a system transfers a waste product generated from a thermal conversion process. The system includes a roller crusher operable to crush a waste product of a thermal conversion process and means for blanketing the waste product with an inert gas.
[00151 Advantages of the present invention will become more apparent to those skilled in the art from the following description of the preferred embodiments of the invention which are shown and described by way of illustration. As will be realized, the invention is capable of other and different embodiments, and its details are capable of modification in various respects. Accordingly, the drawings and description are to be regarded as illustrative in nature and not as restrictive.
BRIEF DESCRIPTION OF THE DRAWINGS
100161 FIGS. 1 and 1 a are a schematic illustration of an exemplary ash transfer, cooling, storage, and unloading system;
[00171 FIGS. 2 and 2a are a schematic illustration of another exemplary ash transfer, cooling, storage, and unloading system;
[0018] FIG. 3 is a schematic illustration of an exemplary nitrogen generation and storage system; and [00191 FIG. 4 is a block diagram flowchart of one embodiment of a method for transferring, cooling, storing, and unloading a waste product generated from a thermal conversion process.
DETAILED DESCRIPTION
[00201 The present embodiments provide a method and system for transferring, cooling, storing, and unloading a waste product of a thermal conversion process. In one embodiment, the thermal conversion process is a gasification process and the waste product is ash generated from gasification. In another embodiment, the biomass fuel used during the gasification process is a mixture of carpet waste and wood flour, such as described by U.S. Application Serial No. 11/052,634.
1. Exemplary Thermal Conversion Process and Biomass Fuels 100211 The process of gasification may be used to generate steam, such as application steam for use by turbines. Gasification is the thermal conversion of a solid biomass fuel into a hot (over 1,000 F) synthesis gas that contains combustible gases, such as methane, hydrogen, carbon monoxide, and/or other gases. In the process of gasification, or the conversion of a solid biomass fuel into a gas, there may be an insufficient amount of oxygen to completely burn the biomass.
[00221 The purpose of gasification and the resultant process conditions may be significantly different than the purpose and operating conditions of an incinerator. In an incinerator, the intent may be to totally burn the solid feed within the confines of the incinerator. On the other hand, the intent of gasification may be to produce a gas for use external to a gasifier, as well as controlling the gasifier emissions to improve any impact on the environment. Additionally, ash generated from gasification as a by-product that is subsequently disposed in an engineered landfill may be biologically inert depending upon which gasification process is used, or at least not a significant source of toxins. Gasification may result in significant material reduction, such that required landfill space is reduced. Accordingly, the process of gasification may have multiple environmental benefits.
[0023] In one aspect, a fabric material having a backing, such as carpet, may be used as a biomass fuel for gasification. The term "carpet" as used herein may encompass any item that has been manufactured from at least two different types of material, one material being a fabric or other covering and another material being a synthetic material, such as rubber or a polymer. For instance, carpet in this context may include standard floor carpet, floor mats, wall coverings, rugs, and the like, as well as industrial carpet waste and segregated, used post-consumer carpet waste.
[0024] Carpet waste may be provided to the system in the form of bales. In general, bales are the end product of a compaction process that is used to decrease the volume that a material occupies by increasing the density and weight. Bales are typically bound with bands or wire to keep the baled material from separating.
Bales may be rectangular, square, round, or have other shapes. Baled carpet may enhance the ease of the delivery and movement of the waste carpet. Landfill owners and/or operators may also provide incentives for baling of carpet to reduce the volume requirement of the landfill. Alternatively, the carpet is loose or not compacted.
[00251 The carpet waste may be shredded and substantially or mostly separated into carpet fines and carpet fibers. The carpet fines may have value as a raw material to the carpet manufacturer, and the carpet fines are detrimental to a gasification process since there is little available heating value. Therefore, the removal and storage of carpet fines may have economic, environmental and/or process efficiency value. The primarily carpet fines may be moved within a first waste product stream to a first silo for storage. The primarily carpet fibers may be used as a biomass fuel, either alone or mixed with another biomass fuel component. The biomass fuel may be utilized by a gasifier to produce synthetic gas and generate hot ash as a by-product.
Subsequently, the synthetic gas may be used to produce electricity, such as via either a combustion turbine or a synthetic gas burner and a boiler.
[0026] The ash produced from gasification may be moved within a second waste product stream to a second silo for storage. The first and second waste product streams may be distinct such that the primarily carpet fines, isolated to the first waste product stream, and the ash, isolated to the second waste product stream, remain separated at least until the ash cools down to approximately the melting point of the carpet fines.
[00271 Using carpet waste as a biomass fuel for gasification may produce a number of benefits. For example, the use of waste carpet to generate application steam may reduce reliance upon other sources of energy, such as coal and natural gas, which are limited in supply. Moreover, expending a significant portion of waste carpet as a fuel during gasification may reduce the total volume of waste carpet products that ultimately are deposited in landfills. Therefore, the present invention may provide environmental benefits that conventional steam generation processes or carpet disposal methods lack.
[00281 Exemplary schematics of a gasification system are shown in U.S.
Application Serial No. 11/052,634.
II. Exemplary Transfer, Cooling, Storing, and Unloading System [00291 The present embodiments relate to a method and system that may safely transfer, cool, store and unload ash free of or without a water spray. In an initial ash auger, ash may be indirectly cooled using a screw auger with a central channel through which a cooled glycol/water mix is passed The ash may then pass through a roll or roller crusher, which breaks up smoldering embers. A rotary air lock may allow the downstream components of the system to be pressurized with nitrogen or other inert gas A second cooling auger may transfer the ash into a continuous bucket elevator, which may directly or indirectly move the ash toward or into a storage silo.
The second ash cooling auger, bucket elevator and silo may be blanketed with an inert gas, such as nitrogen.
100301 The two augers used to convey the ash from the gasifier to the silo may both be indirectly cooled with a glycol/water mix. Conventional glycol/water indirect cooled screw augers are known in the material handling industry and may be used.
[0031] The first glycol/water indirect cooled auger may be kept at ambient or slightly negative pressure. The first auger may be designed to cool the ash enough such that the ash may be discharged into a rotary air lock and/or roller crusher. In one aspect, the first auger may feed the rotary air lock, and then the roller crusher.
Alternatively, the equipment order may be changed, such that the roller crusher may be positioned before and come first within the system, followed by the rotary air lock.
[0032] The purpose of the roller crusher may be to break up any smoldering embers, allowing the embers to be extinguished by a nitrogen, or other inert gas, blanketing system before reaching the silo. The roller crusher may be a dual roll crusher and consist of a pair of steel rollers, separated by a gap of approximately 1/4"
inch. Alternatively, the roller crusher may use either a larger or smaller gap. One of the rollers may be fixed, and the other roller may be mounted on a rigid spring such that some relief or movement is provided in the event that non-crushable material or items, such as a steel bolt, were to move through the system.
100331 The roller crusher may be placed prior to the air lock. If the roller crusher is placed in the nitrogen-pressurized area, then both rollers may have to be fixed in place. For example, if one roller is allowed to move, then nitrogen may leak out along the shaft of that roller. By placing the roller crusher outside (before) the nitrogen pressurized zone of the ash system, the second roller may be moveable without nitrogen leakage concerns.
[0034] After the roller crusher, the ash may move through a rotary air lock.
The remainder of the ash conveyance, storage and unloading system may be at least slightly pressurized with nitrogen, or other inert gas, to eliminate and/or reduce smoldering and/or combustion of the ash. Nitrogen, or another inert gas, may be introduced into the system at various points along the system. In one aspect, nitrogen is introduced into the second glycol/water indirect cooled screw conveyer, the bucket elevator, and the silo.
[0035] Once the ash passes through the rotary air lock, the ash may be conveyed to the bucket elevator by the second glycol/water indirect cooled screw conveyor/auger. The second conveyor may further cool the ash.
[0036] The bucket elevator may be a continuous flow bucket elevator, rather than a centrifugal bucket elevator. A centrifugal bucket elevator may move very quickly and sling the product out of the buckets and into the discharge chute. This process may churn up the ash and increase the possibility of ash combustion. On the other hand, a continuous bucket elevator may move much more slowly, tipping over the full buckets and allowing gravity to empty them. The continuous bucket elevator may minimize the amount of ash that will become airborne in the silo, as well as reduce the likelihood of combustion within the silo.
[0037] The present embodiments also include a modified silo unloading process and equipment to ensure that the ash may be safely discharged from the silo into an enclosed truck. The silo unloading process may be free of, i.e., not use, a final water spray when the ash moved from the silo into a truck receptacle below. Instead, the system and method may include a retractable discharge spout with an annular vent space. The retractable tube-within-a-tube may extend from the bottom of the silo to the truck. The dry ash may fall into the truck via the center tube of the spout. An annular space surrounding the tube may suck a mixture of nitrogen and air out of the truck as the ash falls, providing pressure relief. The use of this type of retractable discharge spout may eliminate the previous problem of dust blowing up out of the truck as the ash was loaded into it. A bag-house dust collector may remove the ash from this air stream. Nitrogen may be used to pulse or shake the bags, so that the protective nitrogen blanket extends all the way to the bag house.
[0038] Prior to ash unloading, the enclosed truck container may be purged with nitrogen for a period of time, such as for approximately ten minutes. The nitrogen purge may ensure that there is little oxygen in the truck receptacle when the ash is loaded into it. The nitrogen purge and accompanying oxygen removal may reduce the likelihood of any remaining embers or hot spots igniting the ash when the truck receptacle is filled.
[0039] This ash cooling system may work well for any ash that, for whatever reason, cannot be easily cooled with a water spray system. Powdery ash, that would create a plaster-like coating on equipment when moistened, or ash that otherwise has chemical or physical constraints that may eliminate the possibility of a water spray system, could benefit from this ash cooling method.
[0040] Therefore, the present embodiments may use a unique combination of equipment that provides for and includes: (1) a roller crusher, (2) nitrogen blanketing of an ash system, either completely or a portion thereof, (3) a continuous bucket conveyor, and (4) a retractable ash spout. The present embodiments may implement this equipment simultaneously and in various combinations to handle an ash cooling and storage situation.
III. Exemplary Ash Storage and Transfer [0041] Figure 1 illustrates an exemplary waste product transfer, cooling, storage, and loading system 100. The system 100 may include an ash conveyor 102, a first auger 104, a second auger 106, a continuous bucket conveyor 108, a storage silo 110, and a nitrogen supply system 122. The system may include additional, fewer, or alternate components.
[0042] The ash conveyor 102 may accept ash produced from a gasification process and transfer the ash to a first auger 104. The first auger 104 may be a first ash screw auger. A cooled water/glycol mix may pass through the center of the screw, thus cooling the ash that is moved through the auger 104.
[0043] The air lock 118 may separate the nitrogen-pressured portion of the ash system from the slightly negatively pressurized gasification unit and first ash cooling screw auger 104. The air lock 118 may be repositioned to be above or below the roller crusher 120. The roller crusher 120 may reduce or eliminate any chunks of smoldering ash. Figures 1 and 1 a together illustrate that the sequencing of the air lock 118 and roller crusher 120 may be interchangeable. In a preferred embodiment, the roller crusher 120 is positioned prior to or upstream of the air lock 118.
[0044] After passing through the air lock 118 and roller crusher 120, the ash may be transferred to a second auger 106. The second auger 106 may be a second ash screw auger. Like the first auger 104, a cooled water/glycol mix passes through the center of the screw, thus cooling the ash that is moved through the second auger 106.
Alternatively, the cooled glycol/water mix may pass through an outer jacket or sleeve associated with the second auger 106. The second auger 106 may be slightly pressurized with nitrogen, such as up to a few inches of water column to displace oxygen, to smother any burning embers. In one aspect, nitrogen is used as a non-flamable gas. Other inert gases may be used, such as carbon dioxide, neon, helium, argon, krypton, xenon, radon, noble gases, or other gases operable to displace oxygen.
The term inert gas used herein shall include noble gas. Any non-flamable gas operable to displace oxygen may be used.
[0045] As shown, a cooling glycol/water supply 114 and cooling glycol/water return 116 may be provided. The supply 114 may send cooling glycol/water into a center sleeve (or alternatively an exterior jacket around the interior) of either the first 104 or second 106 augers, or both. The return 116 may receive spent cooling glycol/water from the first 104 and/or second 106 auger. Nitrogen 122, or other inert/noble gas, may be supplied to the second auger 106.
[0046] The second auger 106 may transfer ash or other waste products to a continuous-flow ash bucket elevator 108. The bucket elevator 108 may be slightly pressured with nitrogen (or other inert or noble gases). Explosion panels may be installed on the sides of the elevator 108, to allow for safe pressure relief in the event of a high-pressure incident.
[0047] A pressure relief valve 124 may be positioned at the top of the bucket elevator 108. The relief valve 124 may allow for safe pressure relief in the event of a high-pressure incident.
[0048] The ash may be transferred to an ash silo 110 via the bucket elevator directly, or indirectly via an intermediate conveyor/auger 132. The ash silo 110 may be slightly pressured with nitrogen via the nitrogen supply 122. The ash silo 110 may have an emergency pressure relief valve 130 located at or near the top of the silo 110.
The relief valve 130 may ensure that, if there was a high-pressure incident in the silo 110, the pressure would vent safely through the top of the silo 110.
[0049] The silo 110 may have a secondary pressure relief valve 128 at or near the top of the silo 110 that may relieve the silo pressure if the silo pressure was abnormally high, but not high enough to trigger an emergency venting via the primary emergency pressure relief valve 130. The silo 110 may have a dust collector 126 at or near the top of the ash silo I 10. The dust collector 126 may operate to protect the pressure relief valve 128 at the top of the silo 110.
[0050] The silo 110 may have a set of three vibratory shakers 132 that facilitate the movement of the ash from the silo 110. The bottom of the silo 110 may have an air lock 134 that allows for the silo 110 to be pressurized, and prevents the nitrogen supplied from the nitrogen supply 122 from escaping through an unloading spout when the unloading spout 134 is not in operation.
[0051] The bottom of the silo 110 may be associated with the ash unloading spout 134. The unloading spout 134 may allow for clean, safe and easy discharge of the ash, or other waste products, from the silo into an ash or other container 112. The unloading spout 134 may be retractable and may include an annular vent space.
In one embodiment, the spout 134 may function as a retractable tube-within-a-tube and may extend from the bottom of the silo to the truck receptacle during use. The dry ash may fall into the truck receptacle via a center tube of the spout 134. The annular space surrounding the center tube may vent gases, such as a mixture of nitrogen and air, out of the truck receptacle as the ash falls, providing pressure relief and dissipation of gasses into the atmosphere.
[0052] The unloading spout 134 may have an associated dust collector 136. The dust collector 136 may capture the relief air that passes through the unloading spout 134, and removes airborne particulate from the relief air.
[0053] The nitrogen supply 122 line may include various fire suppression techniques that consume nitrogen. These may include nitrogen lines extending to various dust collector bags. Because the dust collector(s) may be in the nitrogen-pressurized area, it may be preferable to use compressed nitrogen for bag cleaning, instead of compressed air.
100541 One nitrogen supply 1221ine may go toward a truck purge, operable to fill the ash container with nitrogen prior to ash unloading. Note that this line may receive high or low pressure nitrogen. Another nitrogen supply 122 line may go to a roller crusher, to pressurize the roller crusher and ash cooling auger with nitrogen.
Another nitrogen supply 122 line may go to the bottom of the ash bucket elevator, to pressurize the bucket elevator and ash cooling auger with nitrogen. A number of nitrogen supply 1221ines, such as four or more, may go to the ash silo 110 to pressurize the ash silo 110 with nitrogen.
100551 In one embodiment, the ash conveyor 102, the first auger 104, the second auger 106, the rotary air lock 118, the dual roller crusher 120, and the bucket elevator 108 may be operable to transfer ash at a rate of 2,000 lbs/hr. The roller crusher 120 may use a 20 horse power, 1,800 rpm motor. The rotary air lock 118 may use a 1.5 horse power, 1,800 rpm motor. The first and second augers 104, 106 may each use a horse power, 1,800 rpm motor. The bucket elevator 108 may use a 3 horse power, 1,800 rpm motor. The ash silo 110 may have a 12 feet diameter and 25 feet length, providing for 3,000 cubic feet of storage. The discharge air lock 134 may be operable to discharge ash at a rate of 28,0001b/hr. The discharge rotary air lock 134 may use a 2 horse power, 1,800 rpm motor. The vibratory dust collectors 132 may have associated 1.0 horse power, 3,500 rpm motors.
100561 Figure 2 illustrates another exemplary waste product transfer, cooling, storage, and unloading system 200. Specifically, Figure 2 shows another exemplary view of the physical positions of the different pieces of equipment, and how the transfer, cooling, storing, and unloading system components may be incorporated into/interconnected with a gasification system. The system 200 may include a storage unit 202, a conveyor 204, a gasifier 206, a startup burner 208, a vent stack 210, a duct 212, a cyclone 214, a second conveyor 216, a first auger 218, an air lock 220, a roller crusher 222, a second auger 224, a continuous conveyor 226, a storage unit 228, a second air lock 230, and an unloading spout 232. The system may include an interconnected inert gas system (not shown). The system may include additional, fewer, or alternate components.
[00571 A biomass fuel may be stored in the storage unit 202 and transferred via a conveyor 204 into a gasifier 206 interconnected with a startup burner 208. The gasifier 206 may have a vent stack 210 and ducting 212 leading to a cyclone 214.
The cyclone 214 may be operable to deliver an ash waste product into a conveyor or auger 216. The conveyor or auger 216 may transfer the ash to a first auger 218 associated with an air lock 220 and roll crusher 222. Figures 2 and 2a together illustrate that the sequencing of the air lock 220 and roller crusher 222 may be interchangeable. In a preferred embodiment, the roller crusher 222 is positioned prior to the air lock 220.
[00581 After the ash exits the first auger 218 and passes thru the roll crusher 222, the ash may be sent to the second auger 224. Downstream of the air lock 220, the system may be operable to blanket the ash with nitrogen or another inert gas.
The second auger 224 may deliver the ash to the bucket elevator 226, which in turns may transfer the ash to the silo 228. The silo 228 may have a second air lock 230 such that the silo 228 may be operable to expose the ash within the silo 228 to slightly pressurized nitrogen or another inert gas. The bottom of the silo 228 may be associated with a retractable unloading sprout 232.
[0059] The first auger 218, second auger 224, retractable spout 232, and other components shown in Figure 2 may correspond to the components shown and described above with respect to Figure 1. Other components may be used.
IV. Exemplary Nitrogen System [0060] Figure 3 illustrates an exemplary nitrogen generation and storage system 300. The system 300 may include a nitrogen generator 302, a dryer/filter 304, a receiver 306, a trap 308, a compressor 310, and a tank 312. The nitrogen system may include additional, fewer, or alternate components. Although Figure 3 represents the layout of nitrogen-generating equipment associated with one aspect of the present embodiments, it should be noted that any method of generating nitrogen or any other inert gas may used. For instance, inert gas may be purchased from a supplier and stored within a storage tank interconnected with the waste product transferring, cooling, storing, and unloading system for subsequent use.
100611 A compressor 310 may be used to generate compressed air supplied to the nitrogen generation system. Compressed air generated may pass through a dryer and/or a filter 304 to remove moisture and/or impurities. Compressed air generated and dried may be temporarily collected in a receiver 306. The receiver 306 may have a trap or drain 308 to further remove moisture and/or impurities from the system. The nitrogen generator 302 may convert the compressed dry air into nitrogen gas.
The storage tank 312 may feed the nitrogen supply 122 lines of Figure 1 and may be associated with various valves for bringing the nitrogen supply system on and off line.
V. Exemplary Method [00621 Figure 4 illustrates an exemplary method of transferring, cooling, storing, and unloading a waste product of a thermal conversion process 400. The method may include roller crushing a waste product 402, blanketing the waste product within at least a portion of the system with an inert gas 404, transferring the waste product within the system toward a storage unit via a continuous bucket conveyor 406, and/or unloading the waste product from the storage unit via a retractable spout 408.
The method may be accomplished using the embodiments and components discussed with respect to Figures 1-3 above. The method may include additional, fewer, or alternate steps.
[00631 In one aspect, the method may provide for the transfer, as well as the cooling, storing, and/or unloading, of a gasification waste product with the waste product being blanketed with an inert gas. The method may include crushing the waste product with a roller crusher, such that extinguishing smolders within the waste product is facilitated by the inert gas displacing oxygen in the vicinity of the waste product. After which, the method may include (1) transferring the waste product with a continuous bucket conveyor to a storage unit and (2) subsequently, unloading the waste product from the storage unit via a retractable spout. The waste product may be unloaded from the storage unit into a mobile receptacle, such as a truck or railcar.
The mobile receptacle may under another blanket of inert gas before, during, and/or after unloading.
[0064] The method may include applying the blanket of inert gas to the waste product in one or more glycol/water mix indirectly cooled augers that cool the waste product as the waste product is being transferred. In one embodiment of the method, the inert gas is nitrogen. Other gasses may be used.
[0065] Another embodiment of the method may include crushing a waste product of a thermal conversion process with a roller crusher, blanketing the waste product with an inert gas, and/or transferring the waste product with a continuous bucket conveyor to a storage unit. The method may include unloading the waste product from the storage unit via a retractable spout. The blanket of inert gas may be applied to the waste product in a glycol/water mix indirect cooled auger that cools the waste product as it is being transferred. Alternatively or in addition, the waste product may be placed under a blanket of inert gas during unloading from the storage unit and/or during storage in the storage unit such that the waste product is prevented from re-igniting during unloading and/or storage as oxygen in the vicinity of the waste product is displaced from any smolders or embers of the waste product.
[0066] The method and system may use means for blanketing the waste product with an inert gas, such as one or more conveyors and/or augers operable to transfer the waste product and blanket the waste product with an inert gas, a storage unit being operable to blanket the waste product with an inert gas, and/or a mobile receptacle being operable to blanket the waste product with an inert gas.
[0067] Although the above embodiments are described, there are many possible equipment configurations which may be designed and utilized. For example, the synthetic gas produced by the gasifier shown in Figure 2 may be fired in one or two stages and the flue gas directed to a boiler to produce medium or high-pressure steam.
The high-pressure steam may then be used to drive steam turbines for the production of electricity. Alternatively, the combustion of cleaned synthetic gas in a combustion turbine also may generate electricity.
[00681 In one aspect, the method may use carpet waste and wood flour as a biomass fuel during a gasification process. The method may include sizing a fabric material having a backing, such as by shredding, cutting, tearing, or grinding the fabric material, separating the shredded or sized fabric material into constituent fabric and backing components, storing the backing component in a first storage unit, storing the fabric component in a third storage unit, optionally storing another biomass fuel component fuel component in a fourth storage unit, optionally mixing the fabric component with another biomass fuel component, gasifying the fabric component, and storing the ash generated from gasification as a by-product in a second storage unit. The method may have other variations, including those with fewer, additional, or alternate steps.
[00691 In one embodiment, carpet or another fabric material having a backing is used as a biomass fuel component, such as disclosed by U.S. Application Serial Number 11/052,634, which is incorporated herein by reference in its entirety.
The fabric material is shredded and substantially separated into constituent backing and fabric components. The backing component is stored in a first storage unit.
The fabric component may be mixed with another biomass fuel component before introduction into a gasifier. The gasifier produces synthetic gas, which is subsequently used to produce steam. The hot ash generated as a by-product of gasification is stored in a second storage unit. Each waste product may be confined to a distinct waste path such that the waste products remain isolated from each other, at least until the ash cools down to approximately the melting point of the backing component.
[00701 In another embodiment, the method may include providing fabric material having a backing, such as carpet, as a biomass fuel for gasification, shredding or sizing the carpet into pieces approximately one square inch in size, and substantially separating or sizing the shredded carpet into primarily carpet fibers and primarily carpet fines, such as by a vibratory separator or a step separator.
Subsequently, the primarily carpet fines may be moved by one or more additional conveyors to a first storage unit and the primarily carpet fibers may be moved to and stored in an intermediate storage unit.
[00711 The method may further include providing the separated carpet fibers as a biomass fuel to a gasifier and producing synthetic gas from gasification and generating ash as a by-product. The method also may include moving the ash generated from gasification to a second storage unit, such as a silo. The ash may be moved by at least one additional conveyor. The first and second storage unit may each be part of a distinct waste product path such that the separated carpet fines and ash are isolated from each other for a period of time. As a result, neither waste product is contaminated by or affected by the other waste product, at least until the ash cools to or below the melting point of the carpet fines.
[00721 The method may include mixing the separated carpet fibers with one or more additional biomass fuel components before the introduction of the biomass fuel into the gasifier. Any additional biomass fuel component may be pre-sized and not require any cutting or shredding. For example, the available additional biomass fuel components may include agricultural residues or wood-based fuels, such as pellets, wood chips, wood flour, or sawdust. The additional biomass fuel components may be stored in a third storage unit before mixture with the carpet fibers and subsequent introduction into the gasifier.
[0073] The method may include cooling and scrubing the synthetic gas produced by gasification, burning the synthetic gas in a burner, and heating a boiler to generate application steam via the burner. The method also may include preheating the boiler feedwater by using an economizer. Alternatively, the synthetic gas may be used by a combustion turbine or another utility to generate electricity.
[00741 While the preferred embodiments of the invention have been described, it should be understood that the invention is not so limited and modifications may be made without departing from the invention. The scope of the invention is defined by the appended claims, and all devices that come within the meaning of the claims, either literally or by equivalence, are intended to be embraced therein.
[0075) It is therefore intended that the foregoing detailed description be regarded as illustrative rather than limiting, and that it be understood that it is the following claims, including all equivalents, that are intended to define the spirit and scope of this invention.
Claims (21)
1. A method of transferring a waste product generated from a thermal conversion process, the method comprising:
transferring and/or storing a waste product of a gasification process under a blanket of inert gas.
transferring and/or storing a waste product of a gasification process under a blanket of inert gas.
2. The method of claim 1, the method comprising crushing the waste product with a roller crusher, such that extinguishing smolders within the waste product is facilitated by the inert gas displacing oxygen in the vicinity of the waste product.
3. The method of claim 1, the method comprising transferring the waste product with a continuous bucket conveyor to a storage unit.
4. The method of claim 3, the method comprising unloading the waste product from the storage unit via a retractable spout.
5. The method of claim 3, the method comprising unloading the waste product from the storage unit into a mobile receptacle, the mobile receptable being under a second blanket of inert gas.
6. The method of claim 1, wherein the blanket of inert gas is applied to the waste product in a glycol/water mix indirect cooled auger that cools the waste product as it is being transferred.
7. The method of claim 1, wherein the inert gas is nitrogen.
8. The method of claim 1, the method comprising:
shredding a fabric material having a backing;
separating the shredded fabric material into primarily fabric and primarily backing components;
gasifying the primarily fabric component in a gasifier, the gasifier producing steam; and generating ash as the waste product of the gasification process.
shredding a fabric material having a backing;
separating the shredded fabric material into primarily fabric and primarily backing components;
gasifying the primarily fabric component in a gasifier, the gasifier producing steam; and generating ash as the waste product of the gasification process.
9. A method of transferring a waste product generated from a thermal conversion process, the method comprising:
crushing a waste product of a thermal conversion process with a roller crusher;
blanketing the waste product with an inert gas; and transferring the waste product with a continuous bucket conveyor to a storage unit.
crushing a waste product of a thermal conversion process with a roller crusher;
blanketing the waste product with an inert gas; and transferring the waste product with a continuous bucket conveyor to a storage unit.
10. The method of claim 9, the method comprising unloading the waste product from the storage unit via a retractable spout.
11. The method of claim 9, wherein the blanket of inert gas is applied to the waste product in a glycol/water mix indirect cooled auger that cools the waste product as it is being transferred.
12. The method of claim 9, wherein the waste product is placed under a blanket of inert gas during unloading from the storage unit.
13. The method of claim 9, wherein the waste product is placed under a blanket of inert gas during storage in the storage unit.
14. The method of claim 9, wherein the inert gas is nitrogen.
15. The method of claim 9, wherein the thermal conversion process is a gasification process that accepts a combination of primarily carpet fabric material and wood flour as a biomass fuel and the waste product is ash generated from the gasification process.
16. The method of claim 9, the method comprising:
shredding a fabric material having a backing;
separating the shredded fabric material into primarily fabric and primarily backing components;
gasifying the primarily fabric component in a gasifier, the gasifier producing steam;
generating ash from gasification as the waste product.
shredding a fabric material having a backing;
separating the shredded fabric material into primarily fabric and primarily backing components;
gasifying the primarily fabric component in a gasifier, the gasifier producing steam;
generating ash from gasification as the waste product.
17. A system for transferring a waste product generated from a thermal conversion process, the system comprising:
a roller crusher operable to crush a waste product of a thermal conversion process; and means for blanketing the waste product with an inert gas.
a roller crusher operable to crush a waste product of a thermal conversion process; and means for blanketing the waste product with an inert gas.
18. The system of claim 17, the system comprising:
a continuous bucket conveyor operable to transfer the waste product to a storage unit; and a retractable spout operable to unload the waste product from the storage unit.
a continuous bucket conveyor operable to transfer the waste product to a storage unit; and a retractable spout operable to unload the waste product from the storage unit.
19. The system of claim 17, wherein the thermal conversion process is a gasification process that accepts a waste carpet fabric and wood flour mixture as a biomass fuel, the waste product is ash generated from the gasification process, and the inert gas is nitrogen.
20. The system of claim 17, wherein the means for blanketing the waste product with an inert gas includes one or more conveyors and/or augers operable to transfer the waste product and blanket the waste product with nitrogen.
21. The system of claim 17, wherein the means for blanketing the waste product with an inert gas includes a storage unit being operable to blanket the waste product with nitrogen.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US93831007P | 2007-05-16 | 2007-05-16 | |
| US60/938,310 | 2007-05-16 | ||
| US12/117,886 US20080282944A1 (en) | 2007-05-16 | 2008-05-09 | Cooling system for carpet/wood ash |
| US12/117,886 | 2008-05-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2631210A1 true CA2631210A1 (en) | 2008-11-16 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002631210A Abandoned CA2631210A1 (en) | 2007-05-16 | 2008-05-14 | Cooling system for carpet/wood ash |
Country Status (3)
| Country | Link |
|---|---|
| US (1) | US20080282944A1 (en) |
| CN (1) | CN101428711A (en) |
| CA (1) | CA2631210A1 (en) |
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|---|---|---|---|---|
| CN102502197A (en) * | 2011-12-02 | 2012-06-20 | 师宗东方红锌业有限公司 | Special zinc powder production feeder provided with pressure release valve |
| WO2014152070A1 (en) * | 2013-03-14 | 2014-09-25 | Synthesis Energy Systems, Inc. | Method and apparatus for recycling ash fines |
| US10190065B2 (en) * | 2013-03-15 | 2019-01-29 | Mark E. Koenig | Feed delivery system and method for gasifier |
| CN109812832A (en) * | 2017-11-21 | 2019-05-28 | 吴鲜家 | High-effect combustion control system and its method |
| CN107758380B (en) * | 2017-11-25 | 2020-05-15 | 广州芬豪香精有限公司 | A prevent stifled device for spices processing transportation |
| WO2020121397A1 (en) * | 2018-12-11 | 2020-06-18 | 太平洋セメント株式会社 | Method for distributing pellet-form wood biomass fuel, distribution base for pellet-form wood biomass fuel |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3848813A (en) * | 1973-03-09 | 1974-11-19 | Us Interior | Continuous process for mechanically separating materials contained in urban refuse |
| US4517905A (en) * | 1983-02-10 | 1985-05-21 | Prm Energy Systems, Inc. | Particulate waste product combustion system |
| US5535945A (en) * | 1995-02-27 | 1996-07-16 | Basf Corportion | Carpet recycling process and system |
| US5681952A (en) * | 1995-12-08 | 1997-10-28 | Alliedsignal Inc. | Process for depolymerizing nylon-containing waste to form caprolactam |
| US6945484B1 (en) * | 2000-02-02 | 2005-09-20 | Robert Terzini | Method and apparatus for processing municipal waste |
| US6467708B1 (en) * | 2000-02-02 | 2002-10-22 | Robert Terzini | Method of processing municipal waste |
-
2008
- 2008-05-09 US US12/117,886 patent/US20080282944A1/en not_active Abandoned
- 2008-05-14 CA CA002631210A patent/CA2631210A1/en not_active Abandoned
- 2008-05-16 CN CNA2008101277340A patent/CN101428711A/en active Pending
Also Published As
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|---|---|
| US20080282944A1 (en) | 2008-11-20 |
| CN101428711A (en) | 2009-05-13 |
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