US20130245353A1 - Dry ash collector - Google Patents
Dry ash collector Download PDFInfo
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- US20130245353A1 US20130245353A1 US13/890,685 US201313890685A US2013245353A1 US 20130245353 A1 US20130245353 A1 US 20130245353A1 US 201313890685 A US201313890685 A US 201313890685A US 2013245353 A1 US2013245353 A1 US 2013245353A1
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- Prior art keywords
- ash
- zone
- seal
- collector
- water
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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
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J1/00—Removing ash, clinker, or slag from combustion chambers
- F23J1/02—Apparatus for removing ash, clinker, or slag from ash-pits, e.g. by employing trucks or conveyors, by employing suction devices
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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
- F23J2700/00—Ash removal, handling and treatment means; Ash and slag handling in pulverulent fuel furnaces; Ash removal means for incinerators
- F23J2700/003—Ash removal means for incinerators
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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
- F23J2900/01005—Mixing water to ash
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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
- F23J2900/01006—Airlock sealing associated with ash removal means
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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
- F23J2900/01021—Removing ashes from the ash pit using reciprocating means, e.g. pushers
Definitions
- the present invention relates to a dry ash collector which is a component of a commercial waste processing unit.
- Municipal waste is combusted at high temperatures to oxidize the organic content of the waste, leaving the inorganic content of the waste, also known as the ash content, to be collected and removed from the process for downstream processing or disposal.
- One or more waste combustion furnaces are used to combust the waste.
- aspects of the present invention relate to an ash collector which can be connected to the furnace to receive the ash content of the waste following combustion.
- conventional ash collectors wet ash collectors
- the hot ash is immersed in a bath of water to cool the ash (it initially enters the ash collector at temperatures between 300° and 800° F.).
- AshTech Corporation of Cleveland, Ohio and Clyde Bergemann of South Yorkshire, UK offer a commercial submerged chain conveyor system for removing bottom ash from stoker/grate furnaces that handle municipal solid waste.
- These systems consist of a water filled trough equipped with a submerged chain conveyor.
- the conveyor flights drag ash along an inclined trough wherein water from the ash is drained back into the trough and dewatered ash is dropped off for disposal.
- embodiments of the present invention feature lower water usage than the Ashtec system, because the Ashtec system still relies upon waste immersion system, and while drying the bottom ash in the inclined trough may help remove some of the excess moisture from the refuse, the Ashtec system does not utilize the novel spraying or sensing technology of the present invention.
- the Integrated Pollution Prevention and Control, “Reference Document on the Best Available Techniques for Waste Incineration” August 2006 also discloses and describes a prior art water-sealed based ash collection. See FIG. 2.5 for example.
- POPS illustrates a typical schematic of facility using water quench tank for bottom ash http://www.pops.int/documents/meetings/bat_bep/2nd_session/inf10/EGB2_INF10_munwaste_i ncineration.pdf
- Solid Waste Management 2005, describes some of the problems with current incineration technology. For example, the book explains that ash produced by incineration is hot and must be cooled prior to disposal. The normal method of cooling is quenching in water. After quenching, the ash is dewatered to facilitate storage or landfilling on the incinerator site or transport to a remote disposal site.
- the ash collector may have a shallow water pool to minimize the generation of fly ash.
- the water pool maintains 6 inches to 12 inches of water. Preferably about 6-8 inches of water are maintained to provide fly ash suppression without saturating a majority of the ash.
- the water pool is typically placed in the container of the ash zone, and height of the ash zone may be 8 feet, meaning that a filled ash zone has about 6 inches of saturated ash or about 6.25 percent saturated ash and about 93.75 percent unsaturated ash. Water levels may be maintained by the controller so that they are too low to form a water seal.
- wet ash collectors primarily use a pool of water to cool the ash, while certain embodiments of the present invention use water sprayers.
- wet ash collectors use the pool of water to generate a seal to allow for the generation of negative pressure in the reception zone, whereas certain embodiments of the invention use the ash itself to create the negative pressure seal.
- Most combustions systems feature a negative pressure source (such as a vacuum) in the system.
- the negative pressure may be created by an induction draft fan for example. This negative pressure helps keeps fly ash from exiting the system, and it generally pulls combustion gases and air born particles through the boiler and downstream conditioning equipment and out the stack.
- the ash collector reduces the flow of gases from the beach area to the furnace and maintains a seal in between the beach area and the furnace while removing ash from system. Even though ash is passed through the seal, the ash seal can be maintained.
- the stack emits heat, water vapor, carbon dioxide, oxygen and other gases into the atmosphere.
- Certain configurations of ash collectors provide an air tight seal at the ash collection zone to maintain negative pressure in the reception zone by preventing air from entering the reception zone and the furnace through the ash collector.
- Prior art systems accomplished this using a water seal. Mechanical valves and other similar mechanisms cannot provide constant sealing, because they would need to be opened to allow ash to fall through them (thus breaking the seal.)
- Prior art systems using a water seal also benefit from the water providing the second function of cooling the refuse at the cost of increasing the water content of the ash.
- One of the purposes of the ash seal is to prevent air flow from the beach area into the furnace. Combustion in the furnace is usually carefully controlled. If a seal is not present in the ash collector, gas may be drawn by the negative pressure source through the ash zone into the furnace disrupting the controlled combustion.
- aspects of the present invention feature an ash seal which is used to maintain negative pressure in the reception zone and other areas of the ash collector.
- ash is allowed to fall and accumulate in the ash zone filling a container until the ash level meets a level specified by a controller.
- the controller may use an ash sensor to determine ash levels in the container.
- air cannot pass through the ash zone because the ash blocks the air flow.
- ash will also partially fill the beach area, further blocking the passage of air through the ash collector. Because the ash blocks or substantially blocks the flow of air in the ash collector, negative pressure may be maintained in the reception zone.
- FIG. 1 is a prior art wet bottom ash collector in combination with a grate and a furnace.
- FIG. 2 is an embodiment of dry bottom ash collector in combination with a waste refuse combustion system.
- aspects of the present invention relate to an ash collector 100 for a combustion system 1 having a furnace 20 .
- Methods of collecting bottom ash, and using an ash collector are also presented.
- FIG. 2 there is an intake 200 , a chute 205 , a combustor 210 , a grate 10 , under fire air chambers 215 - 217 , air chamber 220 , moving grate 10 , a furnace 20 , a super heater 225 , super heater fly ash collectors 230 - 232 , an economizer 235 , a scrubber 245 , a baghouse 250 , baghouse fly ash collectors 255 - 257 , a negative pressure source 165 , a stack 255 , an economizer fly ash collector 240 , an ash collector port 160 , an exhaust fan 170 , a fly ash and scrubber solids removal conveyor 260 (used for removing the fly ash and scrubber
- FIG. 1 depicts a prior art combustion system containing a grate 10 , a furnace 20 , and a wet ash collector 30 . Details concerning the grate, furnace and other components depicted are described in US Application Publication 2010/0288173, filed May 18, 2009, herein incorporated by reference in its entirety. Although the liquid used to cool the ash is often water (for reasons of cost, availability, etc) other fluids may be used in the present invention.
- the arrows on FIG. 2 denote the direction of gas flow.
- Municipal waste in the chute 205 and combustor 210 provide a waste seal 101 for maintaining the negative pressure from the negative pressure source 165 .
- An ash seal 102 is formed in the ash zone, preventing the negative pressure source from drawing air and fly ash back into the furnace. Drawing fly ash back into the furnace is undesirable because increasing the fly ash in the system 1 , increases fouling and erosion of components like the super heater 225 and economizer 235 , air inleakage from the beach area 43 negatively affects combustion control and reduces heat transfer efficiency. and increases the load on the negative pressure source.
- FIG. 2 shows a combustion system utilizing a dry ash collector 100 .
- the ash collector 100 may contain heat sensors 110 , sprayers 120 , an ash collector port 160 , a ram 150 , a pool 141 , a negative pressure source 165 , a water level detector 140 , and an ash detector 130 .
- the ash collector 100 may also contain several zones including a reception zone 41 , an ash zone 42 , a beach area 43 , and a collection zone 44 .
- a zone can be a mechanical housing formed by panels or walls to form a geometric shape having an internal volume for housing ash and system components such as the heat sensor or sprayer.
- Heat sensors 110 and sprayers 120 may be positioned in any of the zones, but the embodiment of FIG. 2 shows the heat sensors 110 in the receiving zone 41 and beach area 43 , with sprayers 120 in the reception zone 41 , ash zone 42 , and collection zone 44 . As shown in the embodiment of FIG. 2 , the ram 150 , ash detector or ash level sensor 130 , and a water sensor or water level detector 140 are in the ash zone 42 .
- the system may also be controlled by one or more controllers or regulators 402 , which can control and receive data from components such as the heat sensors 110 , sprayers or spray nozzles 120 , ash detector 130 , water level detector 140 , ram, or exhaust fan 170 .
- controller 402 may be connected to the ash detector for increasing the ash in the ash zone 42 if the ash level in the ash zone is too low to maintain the ash seal by for example increasing the speed of the grate or decreasing the speed of the ram. Controller 402 may have a wired or wireless connection to these components. Controller 402 may contain a microprocessor, computer logic, memory, and software instructions for causing the controller to receive input from components and to cause the controller 402 to send instructions to the components. In some embodiments, controller 402 can also control other elements of the system such as the speed of the grate 10 (or a second ram which pushes items on the grate), the temperature of the furnace 20 , etc.
- the ash collector 100 may still comprise a small amount of water at the bottom of the ash zone 42 .
- One purpose of having a small pool of water 141 is to trap smaller particles which have a tendency to fall through larger particles and collect at the bottom of the ash collector and may become airborne. Without this water, the flyable ash may become airborne when the ash exits the ash discharger.
- a water level detector 140 monitors the amount of water in the ash zone 42 , and may send information to the controller 402 regarding the water level. If the controller 402 determines water levels are too low, the controller may cause the sprayer (particularly sprayers in the ash zone 42 ) to inject more water into the ash zone 42 .
- the sprayers may be connected to a fluid source or water reservoir (not illustrated) for providing fluid or water to the sprayers.
- a drain may also be added to the ash zone to remove excess water.
- the water level may range from being only a few inches to about twelve inches depending on the type of waste being combusted. This lower water level helps prevent the ash from collecting excess weight.
- Some embodiments of the present invention may not contain a water bath 141 , but if they do, water levels are kept to a maximum depth of less than 12 inches, and preferably less than 6 inches to avoid soaking too much ash with water.
- the heat sensors 110 may be thermocouples.
- the heat sensors 110 can be used to determine the temperature of ash both in the receiving zone 41 and the beach area 43 (according the FIG. 2 embodiment.)
- the controller 402 may change the amount, speed, and/or direction of the spray of water to reduce the temperature of the ash if it exceeds a predetermined temperature. Similarly if the temperature of the ash is below a certain level, the controller may change the amount, speed, and/or direction of the spray to avoid adding unnecessary water to the system.
- controllers may alternatively employ equations which directly determine speed, volume, and angle of the ejected water by considering temperature data received by the sensors. Additionally, the controller 402 can also take into account the speed of the grate (or speed of a ram pushing refuse on the grate), temperature inside the furnace 20 , and amount of ash falling into the reception zone 41 . The amount of ash falling into the reception zone 41 per unit of time is called the ash flow rate. This value may be computed by the controller 402 by for example noting how fast ash is removed from the ash zone 42 .
- the amount of ash in the ash zone 42 (as measured by the ash detector 130 ) can be used to determine the ash flow rate entering the reception zone 41 .
- the ash flow rate may also be used by the controller to approximate the temperature of ash falling into the reception zone.
- the sole or primary determination of how much and how fast to spray may be determined by the controller's analysis of the ash flow rate. Temperature information received from the temperature sensors 110 may then be analyzed by the controller to fine tune the amount or direction of the sprayers' ejection of water.
- the ash sensor 130 may use infrared radiation to detect the amount of ash in the ash zone 42 . It is important to maintain a sufficient amount of ash in the ash zone to prevent air inleakage into the furnace 20 from the ash collector 100 and assist in maintaining negative pressure in the reception zone 41 and other areas. To with, the controller 402 may increase the speed of the grate or decrease the speed or movement rate (ash moved per minute) of the ram to maintain the ash seal 102 . In the prior art system (see FIG. 1 ), a water bath was used to maintain an air tight seal. This led to the immersion of the ash, as the ash entered the water, cooling the ash in process. Here ( FIG. 2 ), the ash itself provides the seal.
- Ash from the bottom of the ash zone 42 can be moved up the beach area by a ram 150 , screw, or moving grate.
- the ram 150 may be hydraulically or mechanically controlled and directed to push the bottom ash up the beach ramp. Some of the excess water may run back down the ramp into the ash zone 42 .
- Temperature sensors 110 may be provided to measure the temperature of the ash in the beach area 43 . If the controller 402 determines the ash in the beach area is too hot, it may cause the sprinklers 120 to add additional water to the ash. However, in most configurations, the primary purpose of the sprinklers in the collection zone is suppress the formation of any fly ash.
- Ash and gases that are not suppressed may be drawn through the ash collector port 160 , where the gas may be distributed to the scrubber 245 and baghouse 250 . It is preferable to keep the ash in the ash collector, because increasing the fraction of fly ash passed through the scrubber and baghouse can increase costs and wear of these components. this can reduce overall system performance by increasing the rate of fouling for heat transfer surfaces and burdening the capacity of the flue gas removal equipment including the baghouse 250 and negative pressure source.
- Ash falling through the reception zone 41 may contain uneven temperatures.
- the ash in the center of the reception zone may be hotter and more difficult to expose to water.
- the reception zone may be a housing 8 feet wide by 4 feet deep by 16 feet long. If the sprayers 110 and 120 are positioned along the perimeter of the housing walls, special techniques will need to be employed to make sure that all ash is sprayed with water otherwise uneven cooling of the ash may occur.
- the controller 420 may change the direction of the sprayers, the pressure of the water emitted by the sprayers, spray interval, or flow rate of water exiting through the sprayers to maintain a desired temperature range of the ash in the ash zone.
- Various size nozzles may be used based on ash temperature.
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Abstract
Description
- This application is a continuation of U.S. patent application Ser. No. 13/040,076, filed Mar. 3, 2011.
- The present invention relates to a dry ash collector which is a component of a commercial waste processing unit. In these units, municipal waste is combusted at high temperatures to oxidize the organic content of the waste, leaving the inorganic content of the waste, also known as the ash content, to be collected and removed from the process for downstream processing or disposal. One or more waste combustion furnaces are used to combust the waste. Aspects of the present invention relate to an ash collector which can be connected to the furnace to receive the ash content of the waste following combustion. In conventional ash collectors (wet ash collectors), the hot ash is immersed in a bath of water to cool the ash (it initially enters the ash collector at temperatures between 300° and 800° F.). Because of the high heat capacity of the ash, other cooling approaches, such as direct contact with cool air, or indirect heat exchange with cooling water, are impractical and uneconomical. A second reason a water bath is used to collect ash from waste combustion furnaces is to provide a water seal for the furnace to prevent uncontrolled air from entering the furnace. Thus prior art ash collectors utilize immersion cooling (placing the ash in a bath of water) to cool off the ash. The problem with immersion cooling of the ash is the ash becomes saturated with water. This of course makes the recovered ash stream much heavier (can be as much as 30% heavier) due to the residual water content that remains with the ash. Since the price the municipal waste facilities need to pay to dispose of the recovered ash is often determined (at least in part) by the weight of the ash, reducing the weight of the ash could generate cost savings to the municipal waste facility.
- AshTech Corporation of Cleveland, Ohio and Clyde Bergemann of South Yorkshire, UK offer a commercial submerged chain conveyor system for removing bottom ash from stoker/grate furnaces that handle municipal solid waste. These systems consist of a water filled trough equipped with a submerged chain conveyor. The conveyor flights drag ash along an inclined trough wherein water from the ash is drained back into the trough and dewatered ash is dropped off for disposal. The company's web site: http://www.ashtechcorp.com/SubmergedChainConveyorSystems.htm claims that it can provide systems with low water use with zero water discharge. However, embodiments of the present invention feature lower water usage than the Ashtec system, because the Ashtec system still relies upon waste immersion system, and while drying the bottom ash in the inclined trough may help remove some of the excess moisture from the refuse, the Ashtec system does not utilize the novel spraying or sensing technology of the present invention. The Integrated Pollution Prevention and Control, “Reference Document on the Best Available Techniques for Waste Incineration” August 2006 also discloses and describes a prior art water-sealed based ash collection. See FIG. 2.5 for example.
- In most plants in the United States, Europe and Japan the (bottom) ash is quenched in a water trough at the discharge end of the grate. Walter R. Niessen, “Combustion and Incineration Processes—Applications in Environmental Engineering”, Fourth Edition, CRC Press, 2010. As explained by Stockholm Convention on Persistent Organic Pollutants (POPS), mass burn water wall incinerators are the dominant form of incinerator found at large municipal waste combustion facilities. POPS illustrates a typical schematic of facility using water quench tank for bottom ash http://www.pops.int/documents/meetings/bat_bep/2nd_session/inf10/EGB2_INF10_munwaste_i ncineration.pdf Solid Waste Management, 2005, describes some of the problems with current incineration technology. For example, the book explains that ash produced by incineration is hot and must be cooled prior to disposal. The normal method of cooling is quenching in water. After quenching, the ash is dewatered to facilitate storage or landfilling on the incinerator site or transport to a remote disposal site. See Part II, Chapter 13, as well as the title page: http://www.unep.or.jp/ietc/publications/spc/solid_waste_management/Vol_I/19-Chapter13.pdf and http://www.unep.or.jp/ietc/publications/spc/solid_waste_management/. The problems associated with conventional water based cooling systems have been known in the art for some time, and until Applicant's proposed solution has eluded inventors. For example, a paper by Cappola and Sunk describes that in a conventional Waste-To-Energy (WTE) power plant, bottom ash is typically discharged into a water quenching tank. The water level provides a seal and prevents ambient air from entering the combustion chamber. Also quenching the bottom ash with water stops combustion immediately and prevents fugitive emissions. However, one of the disadvantages of quenching are the high concentration of water in the ash (up to 30-40%) leading to unnecessary costs of transporting and landfilling water. Furthermore, the wet ash tends to bind like cement and form accretions that adhere on metals thus lowering the value of WTE metals and resulting in the loss of small ferrous and non-ferrous metal pieces. http://www.seas.columbia.edu/earth/wtert/sofos/nawtec/nawtec15/nawtec15-3202.pdf.
- Aspects of the present invention provide an apparatus, system, and method for adequately cooling bottom ash without immersing the bottom ash in a bath of water. In some embodiments, the ash collector may have a shallow water pool to minimize the generation of fly ash. The water pool maintains 6 inches to 12 inches of water. Preferably about 6-8 inches of water are maintained to provide fly ash suppression without saturating a majority of the ash. The water pool is typically placed in the container of the ash zone, and height of the ash zone may be 8 feet, meaning that a filled ash zone has about 6 inches of saturated ash or about 6.25 percent saturated ash and about 93.75 percent unsaturated ash. Water levels may be maintained by the controller so that they are too low to form a water seal. One way the prior art ash collectors (wet ash collectors) and the invention (dry ash collector) differ is the wet ash collectors primarily use a pool of water to cool the ash, while certain embodiments of the present invention use water sprayers. In addition, wet ash collectors use the pool of water to generate a seal to allow for the generation of negative pressure in the reception zone, whereas certain embodiments of the invention use the ash itself to create the negative pressure seal.
- Most combustions systems (including certain embodiments of the present invention) feature a negative pressure source (such as a vacuum) in the system. The negative pressure may be created by an induction draft fan for example. This negative pressure helps keeps fly ash from exiting the system, and it generally pulls combustion gases and air born particles through the boiler and downstream conditioning equipment and out the stack. The ash collector reduces the flow of gases from the beach area to the furnace and maintains a seal in between the beach area and the furnace while removing ash from system. Even though ash is passed through the seal, the ash seal can be maintained. The stack emits heat, water vapor, carbon dioxide, oxygen and other gases into the atmosphere. Certain configurations of ash collectors (including certain embodiments of the present invention) provide an air tight seal at the ash collection zone to maintain negative pressure in the reception zone by preventing air from entering the reception zone and the furnace through the ash collector. Prior art systems accomplished this using a water seal. Mechanical valves and other similar mechanisms cannot provide constant sealing, because they would need to be opened to allow ash to fall through them (thus breaking the seal.) Prior art systems using a water seal also benefit from the water providing the second function of cooling the refuse at the cost of increasing the water content of the ash. One of the purposes of the ash seal is to prevent air flow from the beach area into the furnace. Combustion in the furnace is usually carefully controlled. If a seal is not present in the ash collector, gas may be drawn by the negative pressure source through the ash zone into the furnace disrupting the controlled combustion.
- Rather than relying upon water to provide the seal, aspects of the present invention feature an ash seal which is used to maintain negative pressure in the reception zone and other areas of the ash collector. To form the ash seal, ash is allowed to fall and accumulate in the ash zone filling a container until the ash level meets a level specified by a controller. The controller may use an ash sensor to determine ash levels in the container. When the container is filled, air cannot pass through the ash zone because the ash blocks the air flow. In some configurations, ash will also partially fill the beach area, further blocking the passage of air through the ash collector. Because the ash blocks or substantially blocks the flow of air in the ash collector, negative pressure may be maintained in the reception zone.
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FIG. 1 is a prior art wet bottom ash collector in combination with a grate and a furnace. -
FIG. 2 is an embodiment of dry bottom ash collector in combination with a waste refuse combustion system. - At a very high level, aspects of the present invention relate to an
ash collector 100 for a combustion system 1 having a furnace 20. Methods of collecting bottom ash, and using an ash collector are also presented. Starting from the left ofFIG. 2 , there is an intake 200, a chute 205, acombustor 210, a grate 10, under fire air chambers 215-217,air chamber 220, moving grate 10, a furnace 20, a super heater 225, super heater fly ash collectors 230-232, an economizer 235, a scrubber 245, abaghouse 250, baghouse fly ash collectors 255-257, a negative pressure source 165, a stack 255, an economizer fly ash collector 240, an ash collector port 160, an exhaust fan 170, a fly ash and scrubber solids removal conveyor 260 (used for removing the fly ash and scrubber solids frombaghouse 250 while maintaining the negative pressure seal), a conditioner 265 (used to moisten the fly ash with water to prevent dusting), a super heater fly ash conveyor 270, and adry ash collector 100.FIG. 1 depicts a prior art combustion system containing a grate 10, a furnace 20, and a wet ash collector 30. Details concerning the grate, furnace and other components depicted are described in US Application Publication 2010/0288173, filed May 18, 2009, herein incorporated by reference in its entirety. Although the liquid used to cool the ash is often water (for reasons of cost, availability, etc) other fluids may be used in the present invention. - The arrows on
FIG. 2 denote the direction of gas flow. Generally speaking, all gas flows towards the negative pressure source. Municipal waste in the chute 205 andcombustor 210 provide awaste seal 101 for maintaining the negative pressure from the negative pressure source 165. An ash seal 102 is formed in the ash zone, preventing the negative pressure source from drawing air and fly ash back into the furnace. Drawing fly ash back into the furnace is undesirable because increasing the fly ash in the system 1, increases fouling and erosion of components like the super heater 225 and economizer 235, air inleakage from the beach area 43 negatively affects combustion control and reduces heat transfer efficiency. and increases the load on the negative pressure source. -
FIG. 2 shows a combustion system utilizing adry ash collector 100. As shown inFIG. 2 , theash collector 100 may containheat sensors 110, sprayers 120, an ash collector port 160, aram 150, a pool 141, a negative pressure source 165, a water level detector 140, and anash detector 130. Theash collector 100 may also contain several zones including a reception zone 41, an ash zone 42, a beach area 43, and a collection zone 44. A zone can be a mechanical housing formed by panels or walls to form a geometric shape having an internal volume for housing ash and system components such as the heat sensor or sprayer.Heat sensors 110 and sprayers 120 may be positioned in any of the zones, but the embodiment ofFIG. 2 shows theheat sensors 110 in the receiving zone 41 and beach area 43, with sprayers 120 in the reception zone 41, ash zone 42, and collection zone 44. As shown in the embodiment ofFIG. 2 , theram 150, ash detector orash level sensor 130, and a water sensor or water level detector 140 are in the ash zone 42. The system may also be controlled by one or more controllers or regulators 402, which can control and receive data from components such as theheat sensors 110, sprayers or spray nozzles 120,ash detector 130, water level detector 140, ram, or exhaust fan 170. For example, the controller 402 may be connected to the ash detector for increasing the ash in the ash zone 42 if the ash level in the ash zone is too low to maintain the ash seal by for example increasing the speed of the grate or decreasing the speed of the ram. Controller 402 may have a wired or wireless connection to these components. Controller 402 may contain a microprocessor, computer logic, memory, and software instructions for causing the controller to receive input from components and to cause the controller 402 to send instructions to the components. In some embodiments, controller 402 can also control other elements of the system such as the speed of the grate 10 (or a second ram which pushes items on the grate), the temperature of the furnace 20, etc. - Although embodiments of the
ash collector 100 are referred to as a dry ash collector, the ash collector may still comprise a small amount of water at the bottom of the ash zone 42. One purpose of having a small pool of water 141 is to trap smaller particles which have a tendency to fall through larger particles and collect at the bottom of the ash collector and may become airborne. Without this water, the flyable ash may become airborne when the ash exits the ash discharger. A water level detector 140 monitors the amount of water in the ash zone 42, and may send information to the controller 402 regarding the water level. If the controller 402 determines water levels are too low, the controller may cause the sprayer (particularly sprayers in the ash zone 42) to inject more water into the ash zone 42. The sprayers may be connected to a fluid source or water reservoir (not illustrated) for providing fluid or water to the sprayers. A drain may also be added to the ash zone to remove excess water. The water level may range from being only a few inches to about twelve inches depending on the type of waste being combusted. This lower water level helps prevent the ash from collecting excess weight. Some embodiments of the present invention may not contain a water bath 141, but if they do, water levels are kept to a maximum depth of less than 12 inches, and preferably less than 6 inches to avoid soaking too much ash with water. - The
heat sensors 110 may be thermocouples. Theheat sensors 110 can be used to determine the temperature of ash both in the receiving zone 41 and the beach area 43 (according theFIG. 2 embodiment.) The controller 402 may change the amount, speed, and/or direction of the spray of water to reduce the temperature of the ash if it exceeds a predetermined temperature. Similarly if the temperature of the ash is below a certain level, the controller may change the amount, speed, and/or direction of the spray to avoid adding unnecessary water to the system. - Some controllers may alternatively employ equations which directly determine speed, volume, and angle of the ejected water by considering temperature data received by the sensors. Additionally, the controller 402 can also take into account the speed of the grate (or speed of a ram pushing refuse on the grate), temperature inside the furnace 20, and amount of ash falling into the reception zone 41. The amount of ash falling into the reception zone 41 per unit of time is called the ash flow rate. This value may be computed by the controller 402 by for example noting how fast ash is removed from the ash zone 42. If the
ram 150 moves the bottom ash at a constant speed, the amount of ash in the ash zone 42 (as measured by the ash detector 130) can be used to determine the ash flow rate entering the reception zone 41. The ash flow rate may also be used by the controller to approximate the temperature of ash falling into the reception zone. In other embodiments, the sole or primary determination of how much and how fast to spray may be determined by the controller's analysis of the ash flow rate. Temperature information received from thetemperature sensors 110 may then be analyzed by the controller to fine tune the amount or direction of the sprayers' ejection of water. - The
ash sensor 130 may use infrared radiation to detect the amount of ash in the ash zone 42. It is important to maintain a sufficient amount of ash in the ash zone to prevent air inleakage into the furnace 20 from theash collector 100 and assist in maintaining negative pressure in the reception zone 41 and other areas. To with, the controller 402 may increase the speed of the grate or decrease the speed or movement rate (ash moved per minute) of the ram to maintain the ash seal 102. In the prior art system (seeFIG. 1 ), a water bath was used to maintain an air tight seal. This led to the immersion of the ash, as the ash entered the water, cooling the ash in process. Here (FIG. 2 ), the ash itself provides the seal. Ash from the bottom of the ash zone 42 can be moved up the beach area by aram 150, screw, or moving grate. Theram 150 may be hydraulically or mechanically controlled and directed to push the bottom ash up the beach ramp. Some of the excess water may run back down the ramp into the ash zone 42.Temperature sensors 110 may be provided to measure the temperature of the ash in the beach area 43. If the controller 402 determines the ash in the beach area is too hot, it may cause the sprinklers 120 to add additional water to the ash. However, in most configurations, the primary purpose of the sprinklers in the collection zone is suppress the formation of any fly ash. Ash and gases that are not suppressed, may be drawn through the ash collector port 160, where the gas may be distributed to the scrubber 245 andbaghouse 250. It is preferable to keep the ash in the ash collector, because increasing the fraction of fly ash passed through the scrubber and baghouse can increase costs and wear of these components. this can reduce overall system performance by increasing the rate of fouling for heat transfer surfaces and burdening the capacity of the flue gas removal equipment including thebaghouse 250 and negative pressure source. - Ash falling through the reception zone 41 may contain uneven temperatures. The ash in the center of the reception zone may be hotter and more difficult to expose to water. To explain this in more detail, in an exemplary deployment of the disclosed technology, the reception zone may be a housing 8 feet wide by 4 feet deep by 16 feet long. If the
sprayers 110 and 120 are positioned along the perimeter of the housing walls, special techniques will need to be employed to make sure that all ash is sprayed with water otherwise uneven cooling of the ash may occur. To help prevent uneven cooling, the controller 420 may change the direction of the sprayers, the pressure of the water emitted by the sprayers, spray interval, or flow rate of water exiting through the sprayers to maintain a desired temperature range of the ash in the ash zone. Various size nozzles may be used based on ash temperature.
Claims (20)
Priority Applications (1)
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US13/890,685 US20130245353A1 (en) | 2011-03-03 | 2013-05-09 | Dry ash collector |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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US13/040,076 US20120226089A1 (en) | 2011-03-03 | 2011-03-03 | Dry ash collector |
US13/890,685 US20130245353A1 (en) | 2011-03-03 | 2013-05-09 | Dry ash collector |
Related Parent Applications (1)
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US13/040,076 Continuation US20120226089A1 (en) | 2011-03-03 | 2011-03-03 | Dry ash collector |
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US20130245353A1 true US20130245353A1 (en) | 2013-09-19 |
Family
ID=45852749
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US13/040,076 Abandoned US20120226089A1 (en) | 2011-03-03 | 2011-03-03 | Dry ash collector |
US13/890,685 Abandoned US20130245353A1 (en) | 2011-03-03 | 2013-05-09 | Dry ash collector |
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US13/040,076 Abandoned US20120226089A1 (en) | 2011-03-03 | 2011-03-03 | Dry ash collector |
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US (2) | US20120226089A1 (en) |
WO (1) | WO2012119149A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2019174068A (en) * | 2018-03-29 | 2019-10-10 | 川崎重工業株式会社 | Incineration ash cooling device |
Families Citing this family (3)
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KR101991865B1 (en) * | 2017-11-22 | 2019-06-21 | (주)유성 | Apparetus combustion ash chamber with anti-scattering ashes switch |
CN111649347A (en) * | 2020-06-19 | 2020-09-11 | 陕西科技大学 | Environment-friendly automatic slag discharging device for decoupling coal-fired hot-blast stove |
CN114904632B (en) * | 2022-03-02 | 2023-11-10 | 江苏绿景环保设备有限公司 | Broken anti-blocking system for slag hole of salt-containing waste liquid furnace and processing technology thereof |
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US5915308A (en) * | 1996-01-18 | 1999-06-29 | Siemens Aktiengesellschaft | Discharge apparatus |
WO2008023393A1 (en) * | 2006-08-22 | 2008-02-28 | Magaldi Power S.P.A. | Extraction and air/water cooling system for large quantities of heavy ashes |
US8701573B2 (en) | 2009-05-18 | 2014-04-22 | Convanta Energy Corporation | Gasification combustion system |
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- 2011-03-03 US US13/040,076 patent/US20120226089A1/en not_active Abandoned
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US4790250A (en) * | 1987-01-30 | 1988-12-13 | Westinghouse Electric Corp. | Dry ash handling system for an incinerator |
US4976206A (en) * | 1988-10-11 | 1990-12-11 | W+E Umwelttechnik Ag | Mechanism for the removal of slag in incineration plants |
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JP2019174068A (en) * | 2018-03-29 | 2019-10-10 | 川崎重工業株式会社 | Incineration ash cooling device |
JP7199818B2 (en) | 2018-03-29 | 2023-01-06 | 川崎重工業株式会社 | Incinerated ash cooler |
Also Published As
Publication number | Publication date |
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US20120226089A1 (en) | 2012-09-06 |
WO2012119149A1 (en) | 2012-09-07 |
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