Exhaust gas treatment equipment, exhaust gas treatment method, incineration equipment, and melting equipment

Abstract

To provide an exhaust gas treatment device that simplifies the structure and reduces equipment and maintenance costs. [Solution] An exhaust gas treatment device equipped with a dust collector in a flue, comprising: a chemical supply unit that supplies chemicals to the exhaust gas from upstream of the filter member of the dust collector; and a dust ash supply unit that supplies dust ash collected by the dust collector to the exhaust gas from upstream of the filter member of the dust collector, wherein the dust collector is equipped with a hopper unit at the bottom for storing dust ash, and the bottom of the hopper unit is equipped with a first discharge unit and a second discharge unit for discharging dust ash, wherein the dust ash discharged from the first discharge unit is transported to the dust ash supply unit by a transport mechanism, and the dust ash discharged from the second discharge unit is transported to the outside by a transport mechanism.

Description

Technical Field

[0001] The present invention relates to an exhaust gas treatment apparatus provided with a dust collector in a flue, an exhaust gas treatment method, an incineration facility provided with the exhaust gas treatment apparatus, and a melting facility.

Background Art

[0002] Patent Document 1 discloses an exhaust gas treatment apparatus including a dust collector provided in a flue through which exhaust gas flows, a chemical supply unit that supplies an exhaust gas treatment chemical to a chemical supply position between a source of the exhaust gas and the dust collector in the flue, and a dust collection ash conveyance unit that conveys the dust collection ash collected by the dust collector to a dust collection ash supply position between the source and the dust collector in the flue along an auxiliary path different from the flue by a conveyor, and a dust collection ash heating unit provided in the auxiliary path for heating the dust collection ash.

[0003] In the exhaust gas treatment apparatus, the dust collection ash conveyance unit is provided in the auxiliary path and includes a dust collection ash storage unit for storing the dust collection ash. From the dust collection ash storage unit, a fixed amount of the dust collection ash is taken out per unit time by a metering supply unit and supplied into the conveyor, and the dust collection ash is configured to be conveyed by the conveyor in a lump state.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, since the exhaust gas treatment apparatus disclosed in Patent Document 1 was configured to store the dust collection ash collected by the dust collector in a dust collection ash storage unit provided in an auxiliary path and then take it out by a metering supply unit, complicated maintenance work corresponding to a complicated apparatus configuration was required.

[0006] Furthermore, in order to avoid the deliquescence of the collected ash, it was necessary to provide a heating mechanism not only for the auxiliary passage but also for the ash storage section located within the auxiliary passage. This presented a challenge, as it increased not only the equipment costs but also the maintenance costs.

[0007] The object of the present invention is to provide an exhaust gas treatment device, an exhaust gas treatment method, an incineration device, and a melting device that can simplify the structure and reduce equipment costs and maintenance costs, in view of the above-mentioned conventional problems. [Means for solving the problem]

[0008] To achieve the above objective, the first characteristic configuration of the exhaust gas treatment apparatus according to the present invention is an exhaust gas treatment apparatus equipped with a dust collector in a flue, comprising: a chemical supply unit that supplies chemicals to the exhaust gas from upstream of the filtration member of the dust collector; and a dust ash supply unit that supplies the dust ash collected by the dust collector to the exhaust gas from upstream of the filtration member of the dust collector, wherein the dust collector is equipped with a hopper unit at the bottom for storing the dust ash, and the bottom of the hopper unit is equipped with a first discharge unit and a second discharge unit for discharging the dust ash, wherein the dust ash discharged from the first discharge unit is transported to the dust ash supply unit by a transport mechanism, and the dust ash discharged from the second discharge unit is transported to the outside by a transport mechanism.

[0009] As exhaust gas treated with chemicals supplied from the chemical supply unit passes through the dust collector, the chemicals are collected along with the exhaust gas. The collected ash, filtered by the dust collector's filtration element, falls into the hopper section below and is stored there. Because the collected ash is stored in the hopper section of the dust collector, which is kept at a high temperature by the passage of exhaust gas, the collected ash does not deliquesce and is smoothly transported from the first discharge section at the bottom of the hopper section to the dust ash supply section by a transport mechanism. Any excess collected ash is then transported outside from the second discharge section by a transport mechanism.

[0010] The second characteristic configuration is that, in addition to the first characteristic configuration described above, it is equipped with a heating mechanism for heating the dust collected ash stored in the hopper section.

[0011] By equipping the hopper with a heating mechanism, the deliquescence of collected dust ash can be suppressed more reliably, and since the dust collector is preheated by the heat contained in the exhaust gas, the energy required for further heating can also be reduced.

[0012] The third characteristic configuration is that, in addition to the first characteristic configuration described above, the dust collection ash supply unit is configured to supply the dust collection ash via a rotary valve.

[0013] When supplying dust ash from the dust collection ash supply unit to a flue maintained under negative pressure, the inflow of outside air may interfere with exhaust gas treatment. In such cases, however, supplying the dust ash via a rotary valve from upstream of the dust collector's filtration component can effectively prevent the inflow of outside air into the flue and other components.

[0014] The fourth characteristic configuration is that, in addition to any of the first to third characteristic configurations described above, the hopper section is equipped with a detection mechanism for detecting the amount of dust collected ash stored, and a control unit is provided that adjusts the amount of dust collected ash to be discharged to the outside from the second discharge section by the discharge mechanism based on the amount of dust collected ash stored as detected by the detection mechanism.

[0015] Based on the amount of collected ash stored, as detected by the detection mechanism, the control unit adjusts the amount of collected ash discharged from the second discharge unit via the transport mechanism, thereby enabling a stable circulation and supply of collected ash from the first discharge unit. For example, when the amount of collected ash stored becomes small, the amount of collected ash discharged from the second discharge unit is suppressed, and the collected ash can be preferentially circulated and supplied from the first discharge unit.

[0016] The fifth characteristic configuration is that, in addition to the fourth characteristic configuration described above, the control unit is configured to change the reference amount of the collected ash stored in accordance with the change in the amount of collected ash conveyed by the conveying mechanism.

[0017] When the amount of collected ash being transported increases, the amount of collected ash discharged from the second discharge section can be suppressed by raising the standard for the amount of collected ash stored in the hopper section. Conversely, when the amount of collected ash being transported decreases, the amount of collected ash discharged from the second discharge section can be increased by lowering the standard for the amount of collected ash stored in the hopper section.

[0018] The first characteristic configuration of the exhaust gas treatment method according to the present invention is an exhaust gas treatment method using a dust collector provided in a flue, comprising: a chemical supply step of supplying a chemical from a chemical supply unit to the exhaust gas from upstream of the filter member of the dust collector; a dust ash supply step of supplying the dust ash collected by the dust collector to the exhaust gas from upstream of the filter member of the dust collector via a dust ash supply unit; a dust ash storage step of storing the dust ash in a hopper unit provided at the bottom of the dust collector; a dust ash circulation step of discharging the dust ash stored in the hopper unit from a first discharge unit provided in the hopper unit and transporting it to the dust ash supply unit via a transport mechanism; and a dust ash discharge step of discharging the dust ash stored in the hopper unit from a second discharge unit provided in the hopper unit and discharging it to the outside via a transport mechanism.

[0019] The second characteristic configuration is that, in addition to the first characteristic configuration described above, it further includes a heat retention step in which the hopper section and the conveying mechanism are kept at a predetermined temperature using a heating element.

[0020] The third characteristic configuration is that, in addition to the first or second characteristic configuration described above, when the storage level of the collected ash stored in the hopper reaches a first level, the collected ash circulation step and the collected ash discharge step are executed; when the storage level reaches a second level lower than the first level, the collected ash discharge step is stopped; and when the storage level reaches a third level lower than the second level, the collected ash circulation step is stopped.

[0021] The characteristic configuration of the incineration facility according to the present invention is that it includes an incinerator for incinerating waste and a flue for guiding the exhaust gas generated in the incinerator, and the flue is provided with an exhaust gas treatment device having the first to third characteristic configurations.

[0022] The characteristic configuration of the melting facility according to the present invention is that it includes a melting furnace for melting waste and a flue for guiding the exhaust gas generated in the melting furnace, and the flue is provided with an exhaust gas treatment device having the first to third characteristic configurations.

Effect of the Invention

[0023] As described above, according to the present invention, it has become possible to provide an exhaust gas treatment device, an exhaust gas treatment method, an incineration facility, and a melting facility that can simplify the structure and suppress the equipment cost and maintenance cost.

Brief Description of the Drawings

[0024] [Figure 1] It is an explanatory diagram showing the configuration of a waste incineration facility equipped with an exhaust gas treatment device. [Figure 2] It is an explanatory diagram of a control unit that performs control of the circulating supply of dust collected ash.

Embodiment for Carrying Out the Invention

[0025] Hereinafter, the exhaust gas treatment device according to the present invention will be described based on the drawings. FIG. 1 shows a waste incineration facility 100 incorporating an exhaust gas treatment device according to the present invention. The waste incineration facility 100 includes a stoker-type incinerator 1 for incinerating waste such as municipal waste, and equipment such as an economizer 2, a desuperheater 3, a dust collector 4, and a scrubber 5 are arranged in order in the flue of the incinerator 1. The combustion exhaust gas generated in the incinerator 1 is drawn by an induced draft fan 6 toward the flue, and after being treated by these facilities, it is exhausted from a chimney 7. That is, the incinerator 1 and the flue are maintained at a negative pressure.

[0026] The incinerator 1 is configured such that municipal waste, which is fed into the waste hopper 11, is fed into the furnace chamber 13 by a push-in mechanism 12, and is agitated and transported by a stoker mechanism 14 provided in the furnace chamber 13, while being incinerated by primary combustion air supplied by a push-in blower via a wind box 15 provided at the bottom, and the incineration residue falls from the terminal end into the ash pit 16 and is collected as incineration bottom ash.

[0027] Unburned gases generated in the furnace chamber 13 are completely combusted in the secondary combustion region 17 formed in the space above it by secondary combustion air supplied to that region, and are discharged into the flue as high-temperature exhaust gas. A waste heat boiler 18 is provided in the secondary combustion region 17, where steam is generated by the heat of combustion, and the steam, which is further superheated in a superheater 19, is supplied to a generator and the like.

[0028] The high-temperature exhaust gas discharged into the flue is heat-exchanged with feedwater to the boiler by the economizer 2, then cooled in the cooling tower 3, and after fly ash is collected in the dust collector 4, it is further washed in the flue scrubbing tower 5.

[0029] The exhaust gas treatment device according to the present invention comprises a dust collector 4 and its peripheral equipment, a chemical supply unit 20, a dust collection ash circulation supply mechanism 30, and a control unit 60 that controls the chemical supply unit 20 and the circulation supply mechanism 30 to perform exhaust gas purification treatment.

[0030] As the dust collector 4, a bag filter is used, configured such that multiple cylindrical filter cloths 42, which function as filtering members, are arranged in an up-and-down position inside the casing 40, and exhaust gas flowing in from the exhaust gas introduction duct 4A passes through the filter cloths 42 and flows out from the exhaust gas discharge duct 4B connected to the top of the casing 40.

[0031] The exhaust gas introduction duct 4A is installed in an inclined position with its downstream side sloping toward the lower part of the casing 40 of the dust collector 4 from the cooling tower 3, and the chemical supply unit 20 is provided on the upstream side of the exhaust gas introduction duct 4A.

[0032] The chemical supply unit 20 is a mechanism that supplies chemicals (neutralizing agents) for neutralizing acidic gases such as hydrogen chloride and SOx contained in the exhaust gas by a dry treatment method, and includes a chemical storage tank 21, a chemical quantitative dispenser 22 for dispensing the chemical stored in the chemical storage tank 21, and a blower 23 for introducing the chemical dispensed by the chemical quantitative dispenser 22 into the exhaust gas introduction duct 4A via a chemical input duct. In this embodiment, slaked lime is used as the neutralizing agent, but other alkaline chemicals such as sodium carbonate or baking soda can also be used.

[0033] In the space above the filter cloth 42, there is a fly ash removal mechanism 43 equipped with a gas nozzle that injects pulse jet gas for removing fly ash toward the upper opening of the filter cloth 42. The mechanism is configured to inject pulse jet gas from the gas nozzle when the filter cloth 42 becomes clogged, causing the fly ash adhering to the filter cloth 42 to fall downward as collected ash.

[0034] A tapering inclined wall is formed below the casing 40, and a hopper section 44 with a rectangular parallelepiped-shaped side wall is provided below the inclined wall. The side wall is equipped with a heating mechanism 45 in which a plurality of U-shaped heaters are arranged to heat the stored dust ash. Fly ash that falls downward by the fly ash removal mechanism 43 is stored in the hopper section 44 as dust ash, and the hopper section 44 is equipped with a first discharge section 32 and a second discharge section 35, which consist of a screw conveyor that discharges the dust ash supplied via a table feeder 46 provided at the bottom of the hopper section 44.

[0035] The collected ash discharged from the first discharge section 32 is transported to the collected ash supply section 31 by a transport mechanism 33 consisting of a flight conveyor. The collected ash discharged from the second discharge section 35 is transported to a fly ash storage tank 37 located outside the exhaust gas treatment device by an unloading mechanism 36 consisting of a flight conveyor. Panel heaters and insulating materials are wrapped around the casings of the screw conveyor that constitutes the first discharge section 32 and the flight conveyor that constitutes the transport mechanism 33 to suppress the deliquescence of the collected ash being transported, and the temperature is controlled to a predetermined temperature.

[0036] The dust collection ash supply unit 31 is equipped with a rotary valve and supplies the dust collection ash, which has been collected by the dust collector 4 and transported by the transport mechanism 33, to the exhaust gas from the flue upstream of the dust collector 4. The dust collection ash circulation supply mechanism 30 is composed of the first discharge unit 32, the transport mechanism 33, and the dust collection ash supply unit 31 described above.

[0037] The dust ash supplied from the end of the conveying mechanism 33 is supplied to the flue via a rotary valve provided in the dust ash supply unit 31, thereby maintaining negative pressure in the flue. In addition, the negative pressure in the flue is maintained between the screw conveyor, which is the first discharge unit 32 located between the table feeder 46 and the starting end of the conveying mechanism 33, by blocking outside air with screw blades that come into contact with the inner wall of the casing.

[0038] Furthermore, if the casing 40 of the dust collector 4 has a tapering inclined wall formed below it that extends long in the depth direction of the paper, forming a boat-bottom shape, and the hopper section 44 is formed by the space partitioned by the inclined wall, then the above-mentioned table feeder 46 may be provided at the bottom of the end region that has been transported to one side by a fly ash transport mechanism such as a screw conveyor mechanism or a scraping mechanism.

[0039] By supplying collected ash to the exhaust gas introduction duct 4A, which is positioned at an inclination, the collected ash does not accumulate in the exhaust gas introduction duct 4A but flows into the dust collector 4 along with the exhaust gas flowing along the inclination of the exhaust gas introduction duct 4A.

[0040] The exhaust gas inlet 4A and exhaust gas discharge duct 4B are equipped with pressure sensors Pi and Po, and hydrogen chloride gas sensors Si and So, which are examples of acidic gas sensors, respectively, to detect the pressure of the exhaust gas. The detection signals from each sensor are input to the exhaust gas purification control unit 60. The pressure sensors Pi and Po, which detect the pressure on the upstream and downstream sides of the filter cloth 42, can also be installed inside the dust collector 4.

[0041] As shown in Figure 2, the control unit 60 comprises three functional blocks: a neutralizing agent supply control unit 62, a circulation supply amount control unit 64, and a fly ash removal control unit 66. Each of these can be configured using a programmable logic controller (PLC) consisting of switches and relay circuits, or it can be configured using electronic circuits such as a microcomputer and a control program.

[0042] The neutralizing agent supply control unit 62 controls the chemical supply unit 20 so that the required amount of neutralizing agent is supplied, calculated based on at least the acidic gas concentration in the exhaust gas of the dust collector 4, and in this embodiment, the hydrogen chloride gas concentration detected by the hydrogen chloride gas sensor So installed in the exhaust gas discharge duct 4B.

[0043] Furthermore, the neutralizing agent supply control unit 62 may adjust the amount of neutralizing agent supplied by taking into account the hydrogen chloride gas concentration detected by the hydrogen chloride gas sensor Si provided in the exhaust gas inlet unit 4A.

[0044] The fly ash removal control unit 66 calculates the differential pressure between the exhaust gas inlet pressure detected by the pressure sensor Pi in the exhaust gas introduction section 4A and the exhaust gas outlet pressure detected by the pressure sensor Po in the exhaust gas discharge duct 4B as an index for evaluating the degree of clogging of the filter cloth 42. When this differential pressure exceeds a predetermined threshold, it outputs a fly ash removal nozzle drive signal to remove the fly ash adhering to the filter cloth 42, and injects pulsed compressed gas from the gas nozzles constituting the fly ash removal mechanism 43. Air or exhaust gas that has passed through the dust collector 4 can be used as the compressed gas.

[0045] Here, it is preferable to divide the gas nozzles into multiple groups, and when the differential pressure exceeds a threshold, compressed gas is injected from one of the groups in synchronization with the gas nozzle drive signal, and then when the differential pressure exceeds the threshold again, compressed gas is injected from another group of gas nozzles, thereby sweeping away the fly ash from each group. This is because if the system is controlled to inject compressed gas simultaneously from all gas nozzles when the differential pressure exceeds the threshold, there is a risk that the acidic gas concentration will rise suddenly.

[0046] The circulation supply control unit 64 adjusts the amount of fly ash circulated via the circulation supply mechanism 30 using the operating cycle of the fly ash removal mechanism 43, that is, the injection cycle of the pulse jet gas, as an indicator. The amount of fly ash circulated is adjusted by the transport speed of the screw conveyor constituting the first discharge unit 32, the transport speed of the flight conveyor constituting the transport mechanism 33, and the rotation speed of the rotary valve provided in the dust collection ash supply unit 31 so that it is maintained in the boundary region where the pulse jet gas injection cycle changes from an upward phase where it becomes longer to a downward phase where it becomes shorter. This control is intended to reduce the consumption of neutralizing agent by improving reaction efficiency by allowing unreacted portions of the neutralizing agent supplied by the neutralizing agent supply control unit 62, which have missed their reaction opportunity, to function again as neutralizing agent.

[0047] Furthermore, the circulation supply control unit 64 detects the amount of collected ash stored using a detection mechanism 34 provided in the hopper section 44, and adjusts the amount of collected ash discharged from the second discharge section 35 based on the amount of collected ash stored using the detection mechanism 34. A paddle-type level sensor, a vibration-type level sensor, or the like are preferably used as the detection mechanism 34.

[0048] Based on the amount of dust collected ash stored as detected by the detection mechanism 34, the control unit adjusts the amount of dust collected ash discharged from the second discharge unit 35, thereby enabling a stable circulation supply of dust collected ash from the first discharge unit 32. For example, when the amount of dust collected ash stored becomes small, the amount of dust collected ash discharged from the second discharge unit 35 is suppressed, and dust collected ash can be preferentially circulated and supplied from the first discharge unit 32.

[0049] For example, when the dust collection ash storage level in the hopper section 4 reaches a high level H, the discharge of dust collection ash from the second discharge section 35 begins; when it reaches a low level L, the discharge of dust collection ash from the second discharge section 35 stops; and when it reaches an even lower limit low level LL, the circulation supply of dust collection ash from the first discharge section 32 stops. If the level is above the limit low level LL, the circulation supply of dust collection ash is performed continuously.

[0050] Furthermore, the circulation supply control unit 64 controls the standard for the amount of collected ash stored in accordance with the change in the amount of collected ash conveyed by the conveying mechanism 33.

[0051] When the amount of dust collected by the conveying mechanism 33 increases, the amount of dust collected by the second discharge section 35 can be suppressed by raising the standard for the amount of dust collected by the hopper section 44. Conversely, when the amount of dust collected by the conveying mechanism decreases, the amount of dust collected by the second discharge section 35 can be increased by lowering the standard for the amount of dust collected by the hopper section. The values ​​of the high level H, low level L, and limit low level LL mentioned above, or the rotation speed of the screw conveyor constituting the second discharge section 35 can be used as the standard for the amount of dust collected by the hopper section 33.

[0052] By the way, if the dust collector 4 is stopped for maintenance, the first discharge section 32 is reversed, and the collected ash is discharged to the fly ash storage tank 37 via the conveying mechanism 36 through the rotary valve. At the same time, the conveying mechanism 33 and the collected ash supply section 31 are activated to feed all the collected ash in the path into the exhaust gas introduction duct 4A. After all the collected ash in the hopper section 44 is discharged to the fly ash storage tank 37 from the second discharge section 35, the dust collector 4 is stopped. This prevents the collected ash from accumulating and solidifying in the circulation supply mechanism 30 or the exhaust gas introduction duct 4A.

[0053] In the embodiments described above, an exhaust gas treatment device incorporated into a waste incineration facility equipped with a stoker-type incinerator was explained. However, the exhaust gas treatment device according to the present invention may be incorporated into a waste incineration facility equipped with an incinerator other than a stoker-type incinerator, such as a fluidized bed incinerator.

[0054] In the embodiment described above, an example was explained in which the chemical is supplied to the upstream side of the exhaust gas introduction duct 4A by the chemical supply unit 20. However, the chemical may also be configured to be supplied inside the dust collector 4 on the upstream side of the filter cloth 42, which is a filtration member.

[0055] In the embodiment described above, a bag filter using a filter cloth 42 as the filtration member was described as the dust collector 4, but a dust collector using porous ceramic as the filtration member may also be used.

[0056] In the embodiments described above, an exhaust gas treatment device incorporated into a waste incineration facility was described, but the exhaust gas treatment device according to the present invention may be incorporated into a waste melting facility equipped with a melting furnace such as a rotary surface melting furnace.

[0057] The exhaust gas treatment apparatus described above is one embodiment of the present invention, and the technical scope of the exhaust gas treatment apparatus of the present invention is not limited by this description. It goes without saying that the design can be appropriately biased within the range in which the effects of the present invention are achieved. [Explanation of Symbols]

[0058] 1: Incinerator 4: Dust collector 4A: Exhaust gas intake duct 4B: Exhaust gas discharge duct 20: Pharmaceutical Supply Department 21: Drug storage tank 22: Drug Quantitative Dispenser 23: Blower 30: Dust collection ash circulation and supply mechanism 31: Dust ash supply section 32: 1st discharge section 33: Conveying mechanism 34: Detection mechanism 35:Second discharge section 36: Unloading mechanism 37: Fly ash storage tank 40: Casing 42: filter cloth 43: Fly Ash Removal Mechanism 44: Hopper section for dust collection ash (fly ash) 46: Table Feeder 60: Control Unit 62: Neutralizing agent supply control unit 64: Circulation supply control unit 66: Fly Ash Removal Control Unit 100: Waste Incineration Equipment

Claims

1. An exhaust gas treatment device equipped with a dust collector in the flue, A chemical supply unit that supplies chemicals to the exhaust gas from upstream of the filtration member of the dust collector, A dust collection ash supply unit that supplies the dust collection ash collected by the dust collector to the exhaust gas from upstream of the filter member of the dust collector, Equipped with, The dust collector is equipped with a hopper section at the bottom where the collected dust ash is stored. The bottom of the hopper section is provided with a first discharge section and a second discharge section for discharging collected dust and ash. The dust collected from the first discharge unit is transported by the transport mechanism to the dust collected ash supply unit. An exhaust gas treatment device configured such that the collected ash discharged from the second discharge section is transported to the outside by a transport mechanism.

2. The exhaust gas treatment apparatus according to claim 1, further comprising a heating mechanism in the hopper section for heating the stored dust ash.

3. The exhaust gas treatment apparatus according to claim 1, wherein the dust collection ash supply unit is configured to supply the dust collection ash via a rotary valve.

4. The hopper section is equipped with a detection mechanism for detecting the amount of collected dust ash stored. The exhaust gas treatment apparatus according to any one of claims 1 to 3, further comprising a control unit that adjusts the amount of dust collected ash to be discharged to the outside from the second discharge unit by the discharge mechanism based on the amount of dust collected ash stored by the detection mechanism.

5. The exhaust gas treatment apparatus according to claim 4, wherein the control unit is configured to change the reference amount of the dust collected ash stored in accordance with the change in the amount of dust collected ash conveyed by the conveying mechanism.

6. A method for treating exhaust gas using a dust collector installed in the flue, A chemical supply step in which chemicals from the chemical supply unit are supplied to the exhaust gas from the upstream side of the filtration member of the dust collector, A dust collection ash supply step, in which the dust collection ash collected by the dust collector is supplied to the exhaust gas from upstream of the filter member of the dust collector via a dust collection ash supply unit, Equipped with, A dust collection ash storage step is provided in a hopper section located at the bottom of the dust collector, A dust collection ash circulation step in which the dust collection ash stored in the hopper section is discharged from a first discharge section provided in the hopper section and transported to the dust collection ash supply section via a transport mechanism, A dust collection ash discharge step involves discharging the dust collection ash stored in the hopper section from a second discharge section provided in the hopper section and discharging it to the outside via a transport mechanism. A method for treating exhaust gases, including the treatment of such gases.

7. The exhaust gas treatment method according to claim 6, further comprising a heat retention step of maintaining the hopper section and the conveying mechanism at a predetermined temperature using a heating element.

8. When the storage level of the collected ash stored in the hopper reaches a first level, the collected ash circulation step and the collected ash discharge step are executed. When the storage level reaches a second level lower than the first level, the dust collection ash discharge step is stopped. The exhaust gas treatment method according to claim 6 or 7, wherein the dust collection ash circulation step is stopped when the storage level reaches a third level lower than the second level.

9. An incineration facility comprising an incinerator for incinerating waste and a flue for guiding exhaust gas generated in the incinerator, wherein the flue is equipped with an exhaust gas treatment device according to any one of claims 1 to 3.

10. A melting apparatus comprising a melting furnace for melting waste and a flue for guiding exhaust gas generated in the melting furnace, wherein the flue is equipped with an exhaust gas treatment device according to any one of claims 1 to 3.

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