JP2009000662A - Method and apparatus for treating exhaust gas of waste treatment equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To certainly and effectively reduce the concentration of dioxins in the exhaust gas of waste treatment equipment by an inexpensive constitution and to conserve the amount to be used of activated carbon therefor. <P>SOLUTION: A first bag filter 16 and a second bag filter 22 are successively provided on the downstream side of a waste treatment furnace 10. The first bag filter 16 filters dust in the exhaust gas and receives the supply of activated carbon to adsorb dioxins away by this activated carbon. The second bag filter 22 receives the supply of activated carbon separately from the first bag filter 16 to further adsorb dioxins away. The activated carbon supplied to the second bag filter 22 is recovered by an activated carbon circulating and supplying device 30 to be circulated and supplied to the first bag filter 16. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technique for treating exhaust gas generated in a waste treatment facility including a waste incinerator or a waste melting furnace, and can particularly contribute to a reduction in dioxin concentration.

Nitrogen oxides, dioxins (polychlorinated dibenzo-para-dioxin and polychlorinated dibenzo-furan) are included in the exhaust gas from waste treatment facilities equipped with waste treatment furnaces such as waste incinerators and waste melting furnaces. Contains harmful substances. As an exhaust gas treatment method for removing such substances, a method described in Patent Document 1 is known. In this method, the exhaust gas discharged from the incinerator is cooled, and then the dust in the exhaust gas is removed by an electric dust collector or a bag filter, and powdered activated carbon is added to the gas after the dust collection. An adsorption step of adsorbing dioxins in the gas to the activated carbon by passing the adsorption bag filter. In the dust collection step, neutralization and removal of the acid gas is performed by adding slaked lime to the exhaust gas supplied to the electric dust collector or the like.
Japanese Patent Laid-Open No. 11-76758

  In recent years, regulations on dioxins concentration (especially toxicity equivalent concentration: TEQ) in the exhaust gas have been strengthened, and the reduction thereof has become an important issue. As a solution to this, it is conceivable to increase the amount of activated carbon added on the upstream side of the adsorption bag filter described in Patent Document 1. However, even if the amount of the activated carbon added is increased, the amount of activated carbon that can contribute to the adsorption of the dioxins is limited, and it is difficult to expect an effective reduction of the dioxins. Moreover, the increase of the said addition amount increases the required amount of activated carbon, and causes the increase in cost.

  In Patent Document 1, as a method for reducing the amount of activated carbon used, a part of the activated carbon discharged from the adsorption bag filter is recycled to the adsorption bag filter, and the remainder is incinerated and removed in an incinerator. Reuse method to do is described. However, when the concentration of dioxins in the exhaust gas is relatively high, it is difficult to apply the recycling method. Specifically, in this case, the activated carbon discharged from the adsorption bag filter adsorbs a considerable amount of the dioxins and is not suitable for reuse (that is, should be incinerated) and almost absorbs the dioxins. However, it is practically difficult to extract only the latter activated carbon for reuse.

  In view of such circumstances, an object of the present invention is to provide an exhaust gas treatment method and apparatus for a waste treatment facility that can effectively and reliably reduce the concentration of dioxins while suppressing the amount of activated carbon used.

  As a means for solving the above problems, the present invention is a method for treating exhaust gas generated by incineration, thermal decomposition, or melting of waste in a waste treatment facility, wherein The dust is removed from the exhaust gas by introducing the activated carbon and the exhaust gas into a first bag filter having a filter cloth to which activated carbon that adsorbs the dioxins in the exhaust gas can be attached. And a first adsorption step for adhering the activated carbon to the filter cloth of the first bag filter and adsorbing the dioxins in the exhaust gas to the activated carbon; and a second filter cloth having a filter cloth to which the activated carbon adsorbing the dioxins can adhere. Activated carbon different from the activated carbon introduced into the first bag filter and gas discharged from the first bag filter into the bag filter A second adsorption step for adhering the other activated carbon to the filter cloth of the second bag filter and adsorbing the dioxins in the gas to the activated carbon, and adhering to the filter cloth of the second bag filter A circulating supply step of recovering the activated carbon and supplying it to the first bag filter. In the first adsorption step, the activated carbon supplied by the circulation supply step is introduced into the first bag filter and the first bag filter It is attached to the filter cloth of the bag filter.

  In this method, exhaust gas generated by pyrolysis treatment of waste is introduced into the first bag filter together with activated carbon, whereby dust in the exhaust gas is captured by the filter cloth of the first bag filter, and The activated carbon adheres to the filter cloth and adsorbs dioxins in the exhaust gas. The gas discharged from the first bag filter after the dioxins are removed by adsorption in this way is further introduced into the next second bag filter together with activated carbon different from the activated carbon used in the first bag filter. Another activated carbon adheres to the filter cloth of the second bag filter and further adsorbs dioxins remaining in the gas. Such multiple adsorption of dioxins effectively reduces the concentration of dioxins in the gas finally discharged from the second bag filter.

  Furthermore, the activated carbon adhering to the filter cloth of the second bag filter is recovered and supplied to the first bag filter, thereby reducing the total amount of activated carbon necessary for the exhaust gas treatment. In addition, since the dioxins in the gas introduced into the second bag filter are in a very small amount, and therefore, the dioxins adsorbed on the activated carbon recovered from the second bag filter are also in a very small amount, It is possible to easily use the first bug filter for reuse without sorting.

  This method is further effective by including a gas purification step of further reducing dioxin in the gas discharged from the first bag filter and then introducing the gas into the second bag filter. This gas purification step further reduces the amount of dioxins contained in the activated carbon recovered from the second bag filter, and further enhances the dioxin adsorption effect on the first bag filter by the activated carbon.

  Specifically, in the gas purification step, a process for reheating the gas discharged from the first bag filter and a reaction for decomposing nitrogen oxides and dioxins in the reheated exhaust gas are performed using a catalyst. What includes the process to promote is suitable. This step effectively reduces the concentration of dioxins in the gas introduced into the second bag filter.

  In the circulation supply step, the activated carbon recovered from the second bag filter may be sent as it is to the first bag filter. The circulation supply step includes a step of storing the activated carbon in a storage tank, and a step of storing the first bag filter from the storage tank. It is more preferable to include a step of supplying activated carbon to the substrate and adjusting a supply flow rate thereof. Such a process makes it possible to stably supply the required amount of activated carbon to the first bag filter despite the temporal variation in the amount of activated carbon recovered from the second bag filter.

  The present invention is also an apparatus for treating exhaust gas generated by incineration, thermal decomposition, or melting of waste, which is provided in a waste treatment facility, and removes dust from the exhaust gas. A first bag filter having a filter cloth capable of adhering activated carbon that adsorbs dioxins in the exhaust gas, and dioxins in the exhaust gas discharged from the gas purification device provided downstream of the first bag filter A second bag filter having a filter cloth capable of adhering activated carbon that adsorbs the activated carbon, and collecting the activated carbon adhering to the filter cloth of the second bag filter and supplying the activated carbon to the first bag filter, thereby supplying the first activated carbon to the first bag filter. And circulation supply means for adhering to the filter cloth of the bag filter.

  The apparatus includes a gas purification device that is provided between the first bag filter and the second bag filter and further reduces dioxins in the gas sent from the first bag filter to the second bag filter. More preferable.

  The gas purification device includes a reheater that reheats the gas discharged from the first bag filter, and nitrogen in the exhaust gas that is provided downstream of the reheater and reheated by the reheater. What contains a catalyst reaction tower provided with the catalyst which accelerates | stimulates the reaction for decomposing | disassembling an oxide and dioxins is suitable.

  The circulation supply means includes a storage tank for storing activated carbon recovered from the second bag filter, and a supply amount adjusting unit that changes a flow rate of activated carbon supplied from the storage tank to the first bag filter. More preferably, it contains

  As described above, according to the present invention, in addition to introducing activated carbon into the first bag filter, by introducing activated carbon into the second bag filter separately from the activated carbon, the second bag filter is finally used. The concentration of dioxins in the discharged gas can be effectively and reliably reduced, and the content of dioxins in the activated carbon recovered from the second bag filter can be reduced. Therefore, the amount of activated carbon necessary for reducing the dioxin concentration can be easily reduced by supplying activated carbon recovered from the second bag filter to the first bag filter.

  FIG. 1 shows the overall configuration of a waste treatment facility according to an embodiment of the present invention. The waste treatment facility includes a waste treatment furnace 10, a waste heat boiler 12, a temperature reducing tower 14, a first bag filter 16, a reheater 18 and a catalytic reaction tower 20 in order from the front side. A gas purifying device, a second bug filter 22, an induction blower 24, and a chimney 26. The exhaust gas discharged from the waste treatment furnace 10 passes through the components in order by the suction force of the induction blower 24 and is discharged from the chimney 26 to the outside of the system.

  The waste treatment furnace 10 is for incinerating, pyrolyzing, or melting the waste carried by a conveyor (not shown). As this waste treatment furnace 10, a well-known treatment furnace such as a waste incinerator, a waste melting furnace, or a gasification melting furnace can be applied as it is. From the waste treatment furnace 10, high temperature exhaust gas containing harmful substances such as dioxins and nitrogen oxides is discharged.

  In the present invention, the kind of waste to be treated in the waste treatment furnace is not limited. The treatment target includes various kinds of waste such as municipal waste, sewage sludge, and PCB contaminants.

  The waste heat boiler 12 collects heat of the high-temperature exhaust gas discharged from the waste treatment furnace 10 and supplies it to another engine. The temperature reducing tower 14 cools the exhaust gas by spraying cooling water onto the exhaust gas discharged from the waste heat boiler 12. The waste heat boiler 12 and the temperature reducing tower 14 lower the temperature of the exhaust gas to a temperature suitable for use of the first bag filter 16 at the subsequent stage.

  The first bug filter 16 functions as a dust collector that prevents troubles such as clogging at a later stage by capturing dust contained in the exhaust gas. Further, the first bag filter 16 also functions as a dioxin removal device by introducing activated carbon supplied by an activated carbon circulation supply device 30 described later into the bag filter 16.

  The first bug filter 16 has the same configuration as the second bug filter 22 described in detail later. Specifically, a housing having an appropriate shape and a filter cloth (bug) disposed inside the housing are provided. The said filter cloth consists of a woven fabric or a nonwoven fabric, and the said activated carbon can adhere to the said surface while the said dust is capture | acquired.

  The activated carbon and slaked lime as a desalting agent are blown into the upstream side of the first bag filter 16. These activated carbon and slaked lime are introduced into the first bag filter 16 together with the exhaust gas, and attached to the surface of the filter cloth, such as dioxins, sulfur oxides, hydrogen chloride, mercury, etc. in the exhaust gas. Adsorption is performed. If the purpose is mainly to remove dioxins, the slaked lime blowing may be omitted. As a desalting agent that replaces the slaked lime, a sodium system such as baking soda may be used. Further, bentonite or the like may be separately supplied as a reaction aid for improving the reactivity.

  The reheater 18 and the catalytic reaction tower 20 purify the exhaust gas by using a chemical reaction. Specifically, the reheater 18 reheats the gas discharged from the outlet of the first bag filter 16. The target temperature is set to a temperature at which the reaction in the subsequent catalytic reaction tower 20 can be activated, specifically about 170 to 230 ° C. The catalyst reaction tower 20 is loaded with a catalyst for promoting a reaction for decomposing dioxins in the reheated exhaust gas into carbon dioxide gas, water, or the like. The gas purified by the catalytic reaction tower 20 is introduced into the second bag filter 22 at the subsequent stage.

  The second bag filter 22 has basically the same configuration as the first bag filter 16 and includes a filter cloth (bug) to which activated carbon can adhere. However, activated carbon (unused activated carbon) different from activated carbon introduced into the first bag filter 16 (that is, activated carbon supplied by the activated carbon circulation supply device 30) is introduced into the second bag filter 22. .

  Similar to the first bag filter 16, a desalting agent such as slaked lime or baking soda, or a reaction aid such as bentonite may be introduced into the second bag filter 22, as in the case of the first bag filter 16. In addition, the second bag filter 22 may be introduced with a chemical having dioxin adsorption performance similar to activated carbon.

  The activated carbon circulation supply device 30 collects the activated carbon adhering to the filter cloth provided in the housing of the second bag filter 22 and supplies it to the first bag filter 16 side. Specifically, the activated carbon circulation supply device 30 includes an activated carbon recovery device provided in the second bag filter 16, a storage tank 32 for receiving and storing activated carbon recovered by the activated carbon recovery device, and the second A storage pipe 34 for introducing the activated carbon recovered from the bag filter 22 into the storage tank 32; a supply pipe 36 for supplying the activated carbon stored in the storage tank 32 to the first bag filter 16; In addition, a flow rate adjusting valve 38 provided in the middle of the supply pipe 36 and a blower 33 that forms an air flow for conveyance in each of the pipes 34 and 36 as shown in FIG.

  FIG. 2 shows the internal structure of the second bag filter 22. The second bag filter 22 has a housing 40 of an appropriate size, and in this housing 40, a large number of filtering bags 42, a support plate 44, an activated carbon removal device 46, and an activated carbon recovery device 48. It comprises.

  The support plate 44 has a plurality of through holes and is fixed to the upper portion of the housing 40 in a horizontal posture. Each of the filtration bags 42 is formed of the filter cloth, has a shape that extends vertically and opens upward, and each of the support plates 44 is located at a position where the opening matches the through hole of the support plate 44. Fixed to.

  The housing 40 has a gas inlet 41 at a position lower than the filtration bag body 42 and a gas outlet at a position higher than the support plate 44. The gas discharged from the catalytic reaction tower 20 is introduced into the housing 40 through the gas inlet 41 together with activated carbon blown into the catalyst reaction tower 20, passes through the filter cloth of each filtering bag body 42, and then from the gas outlet. Discharged. When the gas passes through the filter cloth, the filter cloth captures a small amount of dust in the gas, and the activated carbon adheres to the surface of the filter cloth. This activated carbon adsorbs a small amount of dioxins in the gas.

  The removal device 46 is provided on the upper portion of the housing 40, and removes activated carbon (and slight dust) adhering to the surface of the filter cloth from the surface by gas pressure. Specifically, the discharge device 46 includes a plurality of gas blowing pipes 50 arranged above the support plate 44, a supply header 52 to which these gas blowing pipes 50 are commonly connected, and the supply header. And a plurality of gas injection ports arranged in the tube length direction are provided at the bottom of each gas outlet tube 50.

  The pump 54 discharges high-pressure gas, and the high-pressure gas is blown downward from the gas injection port of the pipe through the supply header 52 and each gas blowing pipe 50 to the support plate 44. By performing such gas spraying at regular time intervals (for example, 10 minutes), the activated carbon is periodically removed.

  In the illustrated example, compressed air is employed as the high-pressure gas, but the type of the gas is not particularly limited. Moreover, it replaces with gas spraying, or with the said spraying, the said activated carbon may be discharged by adding a vibration to each bag body 42, for example.

  The activated carbon recovery device 48 is provided at the bottom of the housing 40 and recovers the activated carbon that has been wiped off from the filter cloth. Specifically, the activated carbon recovery device 48 includes a conveying screw 56 that extends horizontally along the bottom of the housing 40 and a motor 58 that rotates the conveying screw 56 about its own axis. The conveying screw 56 is rotationally driven by the motor 58 to convey the activated carbon dropped on the bottom portion of the housing 40 to the activated carbon discharge port 60 provided on the bottom portion.

  The configuration of the first bug filter 16 is the same as that shown in FIG. However, the removing device provided in the first bag filter 16 removes not only the activated carbon but also a considerable amount of dust captured by the filter cloth.

  As shown in FIG. 3, the storage pipe 34 connects the activated carbon discharge port 60 of the second bag filter 22 and the inlet of the storage tank 32. The blower 33 forms an air flow from the activated carbon outlet 60 toward the inlet of the storage tank 32 in the storage pipe 34, so that the activated carbon discharged from the activated carbon outlet 60 is stored in the storage tank 32. To introduce.

  The storage tank 32 includes a tank body 62, a filter 64 provided at the inlet of the storage tank 32, and a discharge conveyor 66 connected to the bottom of the tank body 32. The tank body 62 receives activated carbon carried through the storage pipe 34 and the filter 64 and temporarily stores the activated carbon. The discharge conveyor 66 sequentially extracts activated carbon stored in the tank body 62 from the bottom of the tank body 62 and discharges the activated carbon from the activated carbon discharge port 68 of the storage tank 32.

  The supply pipe 36 connects the activated carbon discharge port 68 of the storage tank 32 and the upstream pipe of the first bag filter 16. The blower 33 forms an air flow from the activated carbon discharge port 68 toward the upstream side of the first bag filter 16 in the supply pipe 36, so that the blower 33 is contained in the exhaust gas supplied into the first bag filter 16. Activated carbon (circulated activated carbon) discharged from the activated carbon discharge port 68 is blown.

  The flow rate adjusting valve 38 corresponds to a supply amount adjusting unit that changes the flow rate of the activated carbon supplied from the storage tank 32 to the first bag filter 16. The flow rate control valve 38 is opened and closed in response to an external operation (for example, manual operation or input of an electric signal), thereby changing the air flow rate in the supply pipe 36, thereby supplying the supply flow rate of the activated carbon. Adjust.

  The gas for circulating and transporting the activated carbon is not limited to air. For example, nitrogen gas may be used. The means for transporting the activated carbon may be a scraper conveyor or other transport machine. Even in that case, it is more preferable to supply a cooling gas such as nitrogen or low-temperature air to the activated carbon. Thereby, ignition of activated carbon during conveyance and a decrease in adsorption performance due to oxidation of activated carbon are suppressed.

  Next, an exhaust gas treatment method performed in this apparatus will be described.

  The waste gas generated by incineration, thermal decomposition, or melting of waste in the waste treatment furnace 10 is cooled by the waste heat boiler 12 and the temperature-decreasing tower 14, and then the first bag filter 16 together with activated carbon and slaked lime. Introduced in. As the activated carbon, activated carbon (circulated activated carbon) supplied by the activated carbon circulation supply device 30 is used during normal operation, but unused activated carbon may be used when the device is started up.

  In the first bag filter 16, the filter cloth forming the filtration bag body captures dust in the exhaust gas, and the activated carbon adheres to the surface of the filter cloth. This activated carbon adsorbs and removes a considerable amount of dioxins from the exhaust gas, and greatly reduces the concentration of dioxins in the exhaust gas. The slaked lime contributes to the removal of sulfur oxides, hydrogen chloride and the like in the exhaust gas.

  A preferable inlet temperature for the first bag filter 16 to perform a dioxin removing function is 170 ° C. or lower. However, since the first bag filter 16 is not necessarily required to have a very small amount of dioxins, there is no problem even if the inlet temperature is about 200 ° C. Therefore, even when gas cooling is required on the downstream side of the catalytic reaction tower 20, the degree of cooling is small, and the heat loss can be kept low.

  Although the outlet temperature of the first bag filter 16 is lower than the inlet temperature, the exhaust gas discharged from the outlet of the first bag filter 16 is reheated to a target temperature, for example, about 170 to 230 ° C. by the reheater 18. After being heated, it is introduced into the catalytic reaction tower 20. The catalyst loaded in the catalytic reaction tower 20 promotes a reaction for decomposing dioxins in the exhaust gas into carbon dioxide gas or water. Furthermore, when ammonia is added to the gas, the nitrogen oxide is also decomposed and removed by the reaction between the ammonia and the nitrogen oxide in the gas.

  Although the reaction in the catalytic reaction tower 20 further reduces the dioxin concentration, the reduction degree is not always stable. For example, when reheating by the reheater 18 causes resynthesis of dioxins in the exhaust gas, or when a predetermined dioxin decomposition rate cannot be obtained due to deterioration of the catalyst in the catalytic reaction tower 20 or the like. The dioxins concentration at the outlet of the catalytic reaction tower 20 may be higher than usual.

  However, in this apparatus, the second bag filter 22 at the subsequent stage exhibits a dioxin removal function, thereby ensuring the final dioxin concentration, that is, the dioxin concentration in the gas emitted from the chimney 26 to the atmosphere. Keep it below the specified value. Specifically, activated carbon is blown into the second bag filter 22 together with the exhaust gas, and this activated carbon adheres to the surface of the filter cloth forming the filtration bag 42 (FIG. 2), and dioxins in the exhaust gas are removed. Further, it is removed by adsorption. Since the activated carbon used here is an unused activated carbon different from the activated carbon blown into the first bag filter 16, the dioxins are effective even if the amount of dioxins contained in the gas is very small. Is removed by adsorption.

  Since the dioxins adsorbed by the activated carbon in the second bag filter 22 are extremely small, the activated carbon is suitable for reuse. For example, the entire amount of the collected activated carbon can be reused.

  In the exhaust gas treatment apparatus according to this embodiment, the entire amount of the activated carbon is provided for reuse in the first bag filter 16 by the activated carbon circulation supply device 30. Specifically, the activated carbon adhering to the filtering bag body 42 in the second bag filter 22 is wiped off by periodic gas spraying by the dropping device 46, and is removed from the activated carbon recovery device 48 (a part is removed). The entire amount is introduced into the storage tank 32 through the storage pipe 34 and stored therein. Then, it is supplied from the storage tank 32 to the upstream side of the first bag filter 16.

  Such circulation of activated carbon eliminates the need to supply new activated carbon to the upstream side of the first bag filter 16, thereby contributing to a reduction in consumption of the activated carbon. Furthermore, as described above, since the entire amount of the activated carbon can be supplied to the first bag filter 16 without extracting a part of the recovered activated carbon, it contributes to simplification of the activated carbon circulation device 30.

  The storage of the activated carbon in the storage tank 32 stabilizes the supply amount of the activated carbon to the first bag filter 16. For example, even if the activated carbon recovery operation by the gas blowing in the second bag filter 22 is intermittently performed at a certain time interval, the storage tank 32 for storing the recovered activated carbon has the first tank The activated carbon can be continuously supplied to the one bag filter 16 through the supply pipe 36 at a constant flow rate. Furthermore, it is also possible to adjust the activated carbon circulation supply amount according to the fluctuation of the dioxin concentration in the exhaust gas by operating the flow rate adjustment valve 38 provided in the middle of the supply pipe 36. This adjustment allows further savings in the consumption of the activated carbon.

  The storage tank 32 can be omitted. In that case, the activated carbon recovered by the second bag filter 22 is supplied to the upstream side of the first bag filter 16 as it is. Further, even when the storage tank 22 is provided, the total amount of activated carbon stored in the tank 22 may not be supplied to the upstream side of the first bag filter 16, for example, a part of the activated carbon may be supplied to the second bag filter. 22 may be distributed upstream, or the surplus may be diverted to other equipment or disposed of.

  In the first bag filter 16 as well, activated carbon (and trapped dust) is removed and collected. However, since the activated carbon contains a considerable amount of dioxins, the activated carbon is disposed of, for example, by being put into the waste treatment furnace 10. That is, in the present invention, the activated carbon is individually introduced into the first bag filter 16 and the second bag filter 22, respectively, so that the final dioxin concentration can be reliably lowered below the regulation value, and in addition, the dioxin. Activated carbon (active carbon recovered by the second bag filter 22) that is suitable for reuse with a very small amount of carbon and activated carbon that is adsorbed a lot of dioxins and is preferably disposed of (by the first bag filter 16). It is possible to automatically perform separation from the recovered activated carbon).

  A wet cleaning tower may be provided as a gas purification device between the first bag filter 16 and the reheater 18. In the wet cleaning tower, absorption of hydrogen chloride and sulfur oxide in the exhaust gas is performed by contact between the exhaust gas and a predetermined absorbing chemical (generally sodium hydroxide). The disposition of the wet cleaning tower makes it possible to omit the injection of slaked lime upstream of the first bag filter 16.

  The number of bag filters used in the present invention may be three or more. Specifically, in addition to the first bug filter 16 and the second bug filter 22, another upstream or downstream side of the first bug filter 16 or another upstream or downstream side of the second bug filter 22 is provided. A bug filter may be added.

  In addition, when the dioxin removing function of the first bag filter 16 is very high, the gas processing device including the reheater 18 and the catalytic reaction tower 20 can be omitted. However, the presence of this gas processing device further reduces the amount of dioxins contained in the activated carbon recovered from the second bag filter 22.

  The waste treatment facility shown in FIG. 1 is operated under the following temperature conditions.

  Outlet temperature of the first bag filter 16 (inlet temperature of the reheater 18): 170 to 200 ° C.

  Outlet temperature of the reheater 18 (inlet temperature of the catalytic reaction tower 20): 170 to 230 ° C.

  The outlet temperature of the catalytic reaction tower 20 (the inlet temperature of the second bag filter 22): 180 ° C. or lower.

Supply flow rate of activated carbon to the second bag filter 22: 10 to 200 mg / Nm ³ .

Circulating supply flow rate of activated carbon to the first bag filter 16: 10 to 200 mg / Nm ³ .

Operation under the above conditions stabilizes the final concentration of dioxins (concentration at the outlet of the second bag filter 22) in a range of 0.01 ng-TEQ / Nm ³ or less in terms of toxicity.

  When the set temperature of the second bag filter 22 is set to a low temperature of 170 ° C. or lower, a diagram for cooling the exhaust gas between the catalytic reaction tower 20 and the second bag filter 22 is shown. An approximate exhaust gas cooling device is preferably provided.

It is a flowchart of the waste disposal facility which concerns on embodiment of this invention. It is a cross-sectional perspective view of the bag filter contained in the waste treatment facility. It is a flowchart of the activated carbon circulation supply apparatus contained in the waste treatment facility.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Waste treatment furnace 16 1st bag filter 18 Reheater 20 Catalytic reaction tower 22 2nd bag filter 30 Activated carbon circulation supply apparatus 32 Storage tank 33 Blower 34 Storage pipe 36 Supply pipe 38 Flow control valve (Supply amount adjustment part) )
48 Activated carbon recovery equipment

Claims (8)

A method for treating exhaust gas generated by incineration, pyrolysis, or melting of waste in a waste treatment facility,
By introducing the activated carbon and the exhaust gas into the first bag filter having a filter cloth capable of removing dust from the exhaust gas and capable of adhering activated carbon that adsorbs dioxins in the exhaust gas, A first adsorption step of removing dust and adhering the activated carbon to the filter cloth of the first bag filter to adsorb dioxins in the exhaust gas to the activated carbon;
By introducing activated carbon different from activated carbon introduced into the first bag filter and gas discharged from the first bag filter into the second bag filter having a filter cloth to which activated carbon adsorbing dioxins can adhere. A second adsorption step of adhering the other activated carbon to the filter cloth of the second bag filter and adsorbing the dioxins in the gas to the activated carbon;
A circulation supply step of collecting activated carbon adhering to the filter cloth of the second bag filter and supplying the activated carbon to the first bag filter;
In the first adsorption step, the activated carbon supplied in the circulation supply step is introduced into the first bag filter and adhered to the filter cloth of the first bag filter, and the exhaust gas treatment method for a waste treatment facility is characterized in that . In the waste gas treatment method of the waste treatment facility according to claim 1,
An exhaust gas treatment method for a waste treatment facility, further comprising a gas purification step of further reducing dioxins in the gas discharged from the first bag filter and then introducing the gas into the second bag filter. The exhaust gas treatment method for a waste treatment facility according to claim 2,
The gas purification step includes a process of reheating the gas discharged from the first bag filter, and a process of promoting a reaction for decomposing nitrogen oxides and dioxins in the reheated exhaust gas with a catalyst. An exhaust gas treatment method for a waste treatment facility, comprising: In the exhaust gas treatment method of the waste treatment facility according to any one of claims 1 to 3,
The circulation supply step includes a step of storing activated carbon collected from the second bag filter in a storage tank, and a step of supplying activated carbon from the storage tank to the first bag filter and adjusting a supply flow rate thereof. An exhaust gas treatment method for a waste treatment facility. An apparatus for treating exhaust gas generated by waste incineration, thermal decomposition, or melting, provided in a waste treatment facility,
A first bag filter having a filter cloth capable of removing dust from the exhaust gas and capable of adhering activated carbon that adsorbs dioxins in the exhaust gas;
A second bag filter having a filter cloth provided on the downstream side of the first bag filter and capable of adhering activated carbon that adsorbs dioxins in the exhaust gas discharged from the gas purification device;
And circulating supply means for collecting the activated carbon adhering to the filter cloth of the second bag filter and supplying the activated carbon to the filter cloth of the first bag filter by supplying the activated carbon to the first bag filter. Waste gas treatment equipment for waste treatment equipment. In the exhaust gas treatment apparatus of the waste treatment facility according to claim 5,
Disposal characterized by comprising a gas purification device provided between the first bag filter and the second bag filter and further reducing dioxins in the gas sent from the first bag filter to the second bag filter. Waste gas treatment equipment for waste treatment facilities. In the exhaust gas treatment apparatus of the waste treatment facility according to claim 6,
The gas purification device includes a reheater that reheats the gas discharged from the first bag filter, and nitrogen oxidation in exhaust gas that is provided downstream of the reheater and reheated by the reheater. And a catalytic reaction tower including a catalyst for promoting a reaction for decomposing substances and dioxins. In the exhaust gas treatment apparatus for a waste treatment facility according to any one of claims 5 to 7,
The circulation supply means includes a storage tank for storing activated carbon recovered from the second bag filter, and a supply amount adjusting unit that changes the flow rate of activated carbon supplied from the storage tank to the first bag filter. An exhaust gas treatment apparatus for a waste treatment facility.

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