JP7214594B2 - Exhaust gas treatment device and exhaust gas treatment method - Google Patents

Description

TECHNICAL FIELD The present invention relates to an exhaust gas treatment apparatus and an exhaust gas treatment method.

Exhaust gas containing mercury may be generated when general waste such as municipal waste is incinerated. For example, in the apparatus of Patent Document 1, only when the mercury concentration in the exhaust gas exceeds a predetermined concentration, the mercury adsorbent is introduced into the flue on the upstream side of the dust collector to remove the mercury in the exhaust gas.

Patent Document 2 discloses that the oxidation of elemental mercury to mercuric chloride by hydrochloric acid and the capture of mercuric chloride by particulate matter deposited on the filter material of the filter change depending on the temperature. ing. It also states that in an example in which no adsorbent (for example, activated carbon) is introduced, a mercury capture rate of about 98% is achieved when the flue gas is cooled to about 138°C. In Patent Document 3, in an incinerator, when the mercury-containing fly ash deposited on the heat exchange device is brushed off, the mercury concentration in the flue gas discharged from the chimney is reduced by introducing a mercury-removing agent into the flue gas. A method for keeping the amount below the regulation value is disclosed.

Japanese Unexamined Patent Application Publication No. 2014-213308 JP 2012-223758 A JP 2019-27672 A

By the way, when the mercury concentration in the flue gas generated in the incinerator rises, it is possible to reduce the mercury concentration in the flue gas by increasing the supply amount of the mercury adsorbent in the flue gas treatment device. An excessive increase in the amount of supply increases the cost of exhaust gas treatment. Therefore, there is a demand for a method that can appropriately reduce the mercury concentration of the exhaust gas in the exhaust gas treatment apparatus without excessively increasing the supply amount of the mercury adsorbent.

The present invention has been made in view of the above problems, and an object of the present invention is to appropriately reduce the mercury concentration of exhaust gas in an exhaust gas treatment apparatus.

The invention according to claim 1 is an exhaust gas treatment apparatus, comprising: an adsorbent supply unit that supplies a mercury adsorbent to the exhaust gas in an exhaust gas passage through which exhaust gas generated in a combustion chamber flows; and the mercury adsorbent in the exhaust gas passage. an adsorbent collection unit that collects the an upstream mercury concentration meter that measures the mercury concentration of the exhaust gas as an upstream mercury concentration, and pressure wave cleaning, water injection cleaning, shot cleaning, or fly ash deposited on the heat exchange part can be removed by a cleaning operation using steam generated in the heat exchange part, and the fly ash removal is performed based on the upstream mercury concentration. and the fly ash removal unit executes the cleaning operation when the upstream mercury concentration is above a predetermined threshold .

The invention according to claim 2 is the exhaust gas treatment apparatus according to claim 1, wherein the upstream mercury concentration meter measures the zero-valent mercury concentration of the exhaust gas as the upstream mercury concentration.

According to a third aspect of the present invention, there is provided an exhaust gas treatment apparatus, comprising: an adsorbent supply unit that supplies a mercury adsorbent to the exhaust gas in an exhaust gas passage through which the exhaust gas flows; a mercury concentration meter for measuring the mercury concentration of the exhaust gas; and an exhaust gas temperature adjustment unit capable of performing a temperature reduction process to temporarily lower the temperature of the exhaust gas flowing into the adsorbent trapping unit. and a control unit that causes the exhaust gas temperature control unit to perform the temperature reduction process when the mercury concentration is above a predetermined threshold , the heat generated between the exhaust gas generated in the combustion chamber and a predetermined fluid. A heat exchange section for exchanging is disposed between the combustion chamber and the adsorbent collection section in the exhaust gas path, and the exhaust gas temperature adjustment section removes fly ash deposited in the heat exchange section. It has a fly ash removal section .

The invention according to claim 4 is the exhaust gas treatment apparatus according to claim 3 , wherein the fly ash removal unit is pressure wave cleaning, water injection cleaning, shot cleaning, or steam generated in the heat exchange unit. The fly ash deposited on the heat exchange portion is removed by a cleaning operation by cleaning using a.

The invention according to claim 5 is the exhaust gas treatment apparatus according to claim 3 or 4 , wherein the mercury concentration meter is positioned on the upstream side in the flow direction of the exhaust gas with respect to the adsorbent collection unit. Measure mercury concentration.

The invention according to claim 6 is the exhaust gas treatment apparatus according to claim 5 , wherein the mercury concentration meter measures the concentration of zero-valent mercury in the exhaust gas.

The invention according to claim 7 is the exhaust gas treatment apparatus according to any one of claims 3 to 6 , wherein the adsorbent collecting unit collects the mercury adsorbent with a plurality of filter cloth groups. In addition, the backwashing operation for each of the plurality of filter cloth groups wipes off the mercury adsorbent from the filter cloth groups, and the control unit normally performs the backwashing operation for the plurality of filter cloth groups. are sequentially executed at a set cycle, and when the abnormality occurs, the mercury concentration of the exhaust gas on the upstream side in the flow direction of the exhaust gas with respect to the adsorbent collection unit is changed from a value equal to or greater than a second threshold value to less than the second threshold value. , the backwashing operation is started at a cycle shorter than the set cycle.

According to an eighth aspect of the present invention, there is provided an exhaust gas treatment method in an exhaust gas treatment apparatus, wherein the exhaust gas treatment apparatus includes an adsorbent supply unit that supplies a mercury adsorbent to the exhaust gas in an exhaust gas passage through which the exhaust gas flows; an adsorbent collecting unit for collecting the mercury adsorbent, and an exhaust gas temperature adjusting unit capable of performing a temperature reduction process for temporarily lowering the temperature of the exhaust gas flowing into the adsorbent collecting unit, The exhaust gas treatment method comprises: a) measuring the mercury concentration of the exhaust gas; and b) causing the exhaust gas temperature control unit to perform the temperature reduction process when the mercury concentration is above a predetermined threshold. and a heat exchange section that exchanges heat between the exhaust gas generated in the combustion chamber and a predetermined fluid is disposed between the combustion chamber and the adsorbent collection section in the exhaust gas path, In the step b), fly ash deposited on the heat exchange section is removed by the exhaust gas temperature control section .

According to the present invention, by improving the adsorption performance of the mercury adsorbent when the mercury concentration in the exhaust gas generated in the combustion chamber increases, the mercury concentration in the exhaust gas can be appropriately reduced in the exhaust gas treatment apparatus.

It is a figure which shows the structure of an incineration facility. It is a figure which shows the flow of operation|movement of an exhaust gas processing apparatus. FIG. 4 is a diagram showing equilibrium adsorption amounts of mercury adsorbents at a plurality of exhaust gas temperatures; It is a figure which shows the structure of a bag filter. FIG. 5 is a diagram showing another example of the operation of the exhaust gas treatment device; It is a figure which shows an example of the change of an upstream mercury concentration. FIG. 4 is a diagram showing the equilibrium adsorption amount of the mercury adsorbent during adsorption and desorption. FIG. 5 is a diagram showing another example of the operation of the exhaust gas treatment device; FIG. 5 is a diagram showing another example of the operation of the exhaust gas treatment device;

FIG. 1 is a diagram showing the configuration of an incineration facility 1 according to one embodiment of the present invention. The incineration facility 1 is a facility for incinerating waste such as municipal waste. The incineration facility 1 includes an incinerator 2 , a flue 3 , an exhaust gas treatment device 4 and a chimney 51 . The flue 3 connects the incinerator 2 and the chimney 51 . In FIG. 1, the flue 3 is indicated by a thick solid line. The flue 3 is provided with a temperature reducing tower 44 and a bag filter 42 of the exhaust gas treatment device 4, which will be described later. An induced draft fan (not shown) is also provided in the flue 3 . Exhaust gas (combustion gas) generated in the incinerator 2 is discharged to the flue 3 by the induced draft fan and guided to the chimney 51 via the temperature reducing tower 44 and the bag filter 42 . In practice, the flue 3 is also provided with a denitration device and the like. In the following description, the inside of the chimney 51 is also regarded as part of the flue 3 .

The incinerator 2 has a combustion chamber 21 and an exhaust path 23 . In the combustion chamber 21, combustion of waste and combustion of combustible gas generated from the waste are performed. The exhaust path 23 connects the combustion chamber 21 and the flue 3 , and the exhaust gas generated in the combustion chamber 21 is guided to the flue 3 through the exhaust path 23 . The exhaust path 23 and the flue 3 are exhaust gas paths through which the exhaust gas generated in the combustion chamber 21 flows.

The exhaust gas treatment device 4 includes a heat exchange section 49 and a fly ash removal section 48 . A heat exchange section 49 and a fly ash removal section 48 are provided in the discharge path 23 of the incinerator 2 . The heat exchange section 49 is a boiler and has a plurality of boiler tubes (heat transfer tubes). In the heat exchange section 49, heat exchange is performed between the exhaust gas and a predetermined fluid flowing through the boiler tubes. The fluid is typically water, and the steam generated by the boiler is used for power generation, for example. Of course, the fluid may be other than water.

The fly ash removing section 48 has a plurality of pressure wave generating sections 481 . The plurality of pressure wave generators 481 are provided at positions facing the plurality of boiler tubes in the discharge passage 23 . The pressure wave generator 481 in the present embodiment generates a pressure wave toward the inside of the discharge passage 23 by, for example, rapidly combusting a mixed gas of methane and oxygen. The pressure wave generator 481 is provided with tanks filled with methane and oxygen, and can immediately generate pressure waves upon receiving a command from the controller 40, which will be described later.

Here, the exhaust gas generated in the combustion chamber 21 contains fly ash, and the fly ash is deposited on the plurality of boiler tubes of the heat exchange section 49 . Boiler tubes with accumulated fly ash have reduced heat recovery efficiency. In addition, the boiler tubes may be corroded by the chlorine component contained in the accumulated fly ash. In the discharge path 23, the pressure wave generated by the pressure wave generator 481 propagates to the boiler tube, and fly ash is removed (swept off) from the boiler tube. In this manner, the fly ash removing section 48 can perform a cleaning operation for removing the fly ash deposited on the heat exchanging section 49 by pressure wave cleaning. The pressure wave generator 481 is also called a shock pulse soot blower. As will be described later, the fly ash removing unit 48 may be capable of performing a cleaning operation by a method other than pressure wave cleaning.

The exhaust gas treatment device 4 further includes a control unit 40 , a temperature reducing tower 44 , an adsorbent supply unit 41 , a bag filter 42 , an upstream mercury densitometer 45 and a downstream mercury densitometer 46 . It should be noted that the air supply unit 47 indicated by a dashed block in FIG. 1 is a structure used in another example described later.

The control unit 40 is, for example, a computer including a CPU, etc., and is responsible for overall control of the exhaust gas treatment device 4 . The control unit 40 may also serve as the control unit of the incineration facility 1 . A bag filter 42 is provided in the flue 3 . A portion 31 of the flue 3 located on the upstream side of the bag filter 42 in the flow direction of the exhaust gas (hereinafter referred to as the "upstream flue 31") includes an inlet for the upstream mercury concentration meter 45, a temperature reduction A column 44 and an inlet for the adsorbent supply 41 are provided. An inlet for a downstream mercury concentration meter 46 is provided in a portion 32 of the flue 3 located downstream in the flow direction with respect to the bag filter 42 (hereinafter referred to as "downstream flue 32"). In FIG. 1 , the inlet of the downstream mercury concentration meter 46 is provided in the chimney 51 .

The temperature reducing tower 44 reduces the temperature of the exhaust gas by spraying water on the exhaust gas flowing therein. Under normal conditions, the temperature of the exhaust gas discharged from the temperature reducing tower 44 is, for example, approximately 170°C. The adsorbent supply unit 41 has, for example, a table feeder or the like, and supplies (injects) powdered mercury adsorbent into the exhaust gas flowing through the upstream flue 31 . A mercury sorbent is, for example, activated carbon. Impregnated activated carbon obtained by impregnating the surface of activated carbon with iodine or sulfur, for example, may be used as the mercury adsorbent. The exhaust gas treatment device 4 may be provided with an alkaline chemical supply unit that supplies an alkaline chemical to the exhaust gas flowing through the upstream flue 31 . The alkaline chemical is a chemical for desalting and desulfurization, such as powdery slaked lime.

The bag filter 42 is of a filtration type, and collects fly ash contained in the exhaust gas with a filter cloth. Mercury adsorbent supplied by the adsorbent supply unit 41 is also collected by the filter cloth. Fly ash and mercury sorbents deposit on the filter cloth. The bag filter 42 is an adsorbent collecting portion that collects the mercury adsorbent. Inside the bag filter 42, when the exhaust gas passes through the filter cloth, the mercury adsorbent deposited on the filter cloth adsorbs mercury contained in the exhaust gas. Adsorption of mercury in the mercury adsorbent also occurs in the upstream flue 31 . The mercury adsorbent may further adsorb dioxins and the like contained in the exhaust gas. In addition, when the already-described alkaline chemical is supplied, the alkaline chemical is also collected by the filter cloth. A reaction between the acid gas (hydrogen chloride, sulfur oxides, etc.) contained in the exhaust gas and the alkaline agent on the filter cloth causes the acid gas to be removed from the exhaust gas. As will be described later, in the bag filter 42 , fly ash and mercury adsorbent deposited on the filter cloth are brushed off and discharged from the bag filter 42 by backwashing operation using compressed air.

The upstream mercury densitometer 45 and the downstream mercury densitometer 46 take in a part of the flue gas flowing through the flue 3 and analyze it to obtain the measured value of the mercury concentration in the flue gas. As described above, the inlet of the upstream mercury concentration meter 45 is arranged on the upstream side (upstream flue 31) of the bag filter 42 in the flow direction of the exhaust gas, and the inlet of the upstream mercury concentration meter 45 is arranged on the downstream side of the bag filter 42 (downstream flue 32), the inlet of the downstream mercury concentration meter 46 is arranged. In other words, the upstream mercury concentration meter 45 measures the mercury concentration of the exhaust gas on the upstream side of the bag filter 42 in the flow direction of the exhaust gas, and the downstream mercury concentration meter 46 measures the downstream side of the bag filter 42 in the flow direction. Measure the mercury concentration of exhaust gas at

Here, the mercury contained in the exhaust gas mainly includes zero-valent atomic mercury (hereinafter referred to as "zero-valent mercury"), and bivalent mercury (hereinafter referred to as mercury compounds such as mercury chloride). It exists as "divalent mercury"). In addition, the upstream mercury concentration meter 45 and the downstream mercury concentration meter 46 are provided with a concentration acquisition unit that acquires a measured value of mercury concentration based on zero-valent mercury by an ultraviolet absorption method or the like.

The downstream mercury concentration meter 46 further includes a reduction catalyst that reduces the divalent mercury contained in the exhaust gas to zero-valent mercury, and the concentration of zero-valent mercury contained in the gas after reduction (that is, the zero-valent mercury originally contained in the exhaust gas) It is the total concentration of valent mercury and zero-valent mercury obtained by reducing divalent mercury, hereinafter referred to as "total mercury concentration") is measured as the downstream mercury concentration. In the exhaust gas treatment device 4 , the downstream mercury concentration is continuously measured by the downstream mercury concentration meter 46 .

On the other hand, the upstream mercury concentration meter 45 does not include a reducing catalyst, and the concentration of zerovalent mercury originally contained in the exhaust gas is taken as the upstream mercury concentration in a state where the divalent mercury contained in the exhaust gas is not reduced to zerovalent mercury. Measure. The upstream mercury concentration meter 45 can quickly measure the upstream mercury concentration by omitting the time required to reduce divalent mercury to zero-valent mercury. In the exhaust gas treatment device 4 , the upstream mercury concentration is continuously measured by the upstream mercury concentration meter 45 .

Depending on the design of the exhaust gas treatment device 4, a reduction catalyst may be provided in the upstream mercury concentration meter 45, and the total mercury concentration may be measured as the upstream mercury concentration. In the measurement of the total mercury concentration, since both zero-valent mercury and divalent mercury are detected, it is possible to accurately measure the upstream mercury concentration. Similarly, the downstream mercury concentration meter 46 may measure the zero-valent mercury concentration as the downstream mercury concentration. Further, the upstream mercury concentration meter 45 and the downstream mercury concentration meter 46 may be capable of selectively measuring the zero-valent mercury concentration and the total mercury concentration.

Next, normal operation of the exhaust gas treatment device 4 will be described. As described above, the operation of the exhaust gas treatment device 4 is controlled by the controller 40 . First, in the adsorbent supply unit 41 , the amount of mercury adsorbent supplied is controlled based on (the measured value of) the upstream mercury concentration in the upstream mercury concentration meter 45 . For example, when the upstream mercury concentration is relatively high, the supply amount of the mercury sorbent is increased, and when the upstream mercury concentration is relatively low, the supply amount of the mercury sorbent is decreased. When the mercury adsorbent is activated carbon, the activated carbon also adsorbs dioxins. Therefore, it is preferable that a predetermined amount or more of the mercury adsorbent is always supplied to the flue 3 while the exhaust gas flows through the flue 3 . In the exhaust gas treatment device 4 , the mercury concentration in the exhaust gas flowing through the downstream flue 32 can be reduced by controlling the amount of mercury adsorbent supplied by the adsorbent supply unit 41 . In the exhaust gas treatment device 4 , the supply amount of the mercury adsorbent may be controlled based on the downstream mercury concentration in the downstream mercury concentration meter 46 .

In addition, in the fly ash removing section 48 during normal operation, a cleaning operation for removing the fly ash deposited on the heat exchanging section 49 by pressure wave cleaning is performed at regular intervals (timer control). Further, the amount of ash deposition may be estimated from the relationship between the amount of heat input to the exhaust gas heat-exchanged in the heat exchange unit 49 and the amount of heat received by the steam, and when the amount of ash deposition is equal to or greater than a predetermined value, the cleaning operation may be performed. (calorie control). By executing the cleaning operation, it is possible to improve the efficiency of heat recovery in the boiler tubes and suppress corrosion of the boiler tubes.

Next, the operation of the exhaust gas treatment device 4 at the time of abnormality when the upstream mercury concentration is high will be described. FIG. 2 is a diagram showing the operation flow of the exhaust gas treatment device 4 in the event of an abnormality. As described above, the upstream mercury concentration meter 45 continuously measures the upstream mercury concentration in the upstream flue 31 (step S11). When the upstream mercury concentration reaches or exceeds a predetermined first threshold value (step S12), the fly ash removal section 48 performs a cleaning operation (step S13). In the following description, the cleaning operation in step S13 will be referred to as a "forced cleaning operation" in order to distinguish it from the normal cleaning operation that is performed at regular intervals.

By executing the forced cleaning operation, the fly ash deposited on the plurality of boiler tubes is removed, thereby improving the heat recovery efficiency in the heat exchange section 49 . As a result, the temperature of the exhaust gas passing through the heat exchange section 49 and flowing into the flue 3 is lowered, and the temperature of the exhaust gas flowing into the bag filter 42 is also lowered. In this way, the forced cleaning operation is temperature reduction processing that temporarily lowers the temperature of the exhaust gas flowing into the bag filter 42 . Further, the fly ash removal section 48 is an exhaust gas temperature adjustment section capable of performing temperature reduction processing. The temperature of the exhaust gas flowing into the bag filter 42 when the temperature reduction process is performed is lower than the average temperature of the exhaust gas during normal operation. The lower limit of the temperature of the exhaust gas in the temperature reduction process is not particularly limited, but is, for example, 130°C, preferably 140°C at the temperature sensor provided near the inlet of the bag filter 42 .

Here, the relationship between the exhaust gas temperature and the equilibrium adsorption amount of the mercury adsorbent will be described. FIG. 3 is a diagram showing the equilibrium adsorption amount of the mercury adsorbent at a plurality of exhaust gas temperatures. The three lines in FIG. 3 show the relationship between the gas-phase mercury concentration and the equilibrium adsorption amount obtained from an adsorption experiment in which a simulated exhaust gas containing mercury is passed through a mercury adsorbent for a predetermined period of time. The temperature of the simulated exhaust gas is assumed to be 150°C, 170°C and 190°C, respectively. As shown in FIG. 3, all three lines indicate that the equilibrium adsorption amount increases as the vapor phase mercury concentration increases. Also, when comparing at the same vapor phase mercury concentration, the lower the temperature of the simulated exhaust gas, the larger the equilibrium adsorption amount.

In the exhaust gas treatment device 4, as described above, when there is an abnormality in which the upstream mercury concentration is equal to or higher than the first threshold value, the fly ash removal unit 48 A forced cleaning operation is executed by . As a result, the temperature of the exhaust gas flowing through the upstream flue 31 is temporarily lowered, and the adsorption performance (equilibrium adsorption amount of mercury) of the mercury adsorbent deposited on the filter cloth of the bag filter 42 is improved. As a result, the mercury concentration in the exhaust gas flowing into the downstream flue 32 is lower than when the forced cleaning operation is not performed.

If the forced cleaning operation at the time of abnormality is performed immediately after the cleaning operation at the normal time, the fly ash accumulated in the plurality of boiler tubes has already been removed. The temperature of the exhaust gas entering the road 31 may not drop. Therefore, it is preferable that the forced cleaning operation at the time of abnormality is performed after, for example, five minutes or more have passed since the cleaning operation at the normal time. Further, as will be described later, it is possible to reduce the temperature by increasing the spray amount of water in the temperature reducing tower 44 or by supplying air from the air supply unit 47 to the upstream flue 31. . Therefore, the temperature reduction process by the temperature reduction tower 44 or the air supply unit 47 may be performed when the forced cleaning operation in the abnormal state is performed immediately after the normal cleaning operation.

The adsorbent supply unit 41 controls the supply amount of the mercury adsorbent based on the upstream mercury concentration even in the event of an abnormality. Therefore, together with the reduction in the temperature of the exhaust gas flowing into the bag filter 42, the mercury concentration in the exhaust gas in the exhaust gas treatment device 4 can be more reliably reduced. In other words, it is possible to appropriately reduce the mercury concentration in the exhaust gas without excessively increasing the supply amount of the mercury adsorbent in the event of an abnormality. In the adsorbent supply unit 41, the supply amount of the mercury adsorbent is lower than the supply amount determined based on the upstream mercury concentration during the period in which the temperature of the exhaust gas flowing into the bag filter 42 is lowered by the forced cleaning operation. It may be reduced, or it may be constant at a predetermined supply amount. Further, a temperature sensor may be provided near the inlet of the bag filter 42 in the upstream flue 31, and the supply amount of the mercury adsorbent may be determined based on the temperature and the upstream mercury concentration obtained by the temperature sensor.

When a certain amount of time has passed since the forced cleaning operation was performed and fly ash accumulates in the boiler tubes, the temperature of the exhaust gas flowing through the upstream flue 31 rises. After a predetermined time has passed since the previous forced cleaning operation, the upstream mercury concentration is maintained at or above the first threshold, or when the upstream mercury concentration rises from a value below the first threshold to at or above the first threshold again. , a forced cleaning operation is executed (steps S12 and S13).

As described above, in the exhaust gas treatment device 4, the heat exchange section 49 is provided between the combustion chamber 21 and the bag filter 42 in the exhaust gas path through which the exhaust gas generated in the combustion chamber 21 flows. Then, in an abnormal state where the upstream mercury concentration is equal to or higher than the first threshold value, the fly ash removal unit 48 performs a forced cleaning operation on the heat exchange unit 49 . As a result, the temperature of the exhaust gas flowing into the bag filter 42 can be temporarily lowered, and the adsorption performance of the mercury adsorbent deposited on the filter cloth can be improved. As a result, in the exhaust gas treatment device 4, the mercury concentration in the exhaust gas can be appropriately reduced without excessively increasing the supply amount of the mercury adsorbent. In addition, the upstream mercury concentration meter 45 measures the zero-valent mercury concentration of the exhaust gas as the upstream mercury concentration, so that an increase in the mercury concentration of the exhaust gas in the upstream flue 31 can be quickly detected, and forced cleaning can be performed. Actions can be performed at appropriate times.

In the fly ash removing section 48, instead of the pressure wave generating section 481, a steam type soot blower can be used. In the steam type soot blower, fly ash accumulated in the heat exchange section 49 is removed by injecting steam from a nozzle toward the boiler tubes of the heat exchange section 49 . On the other hand, in a steam type sootblower, it takes time to generate steam (which can be regarded as warming up), so immediately after the upstream mercury concentration becomes equal to or higher than the first threshold, that is, immediately after an abnormality occurs. Moreover, it is difficult to perform a forced cleaning operation. Therefore, from the viewpoint of starting the forced cleaning operation without delay based on the upstream mercury concentration, immediately after receiving a command from the control unit 40, the fly ash removing unit 48 capable of executing the cleaning operation (hereinafter referred to as such a The fly ash removing unit 48 is preferably referred to as a “highly responsive fly ash removing unit 48”).

An example of the highly responsive fly ash removing unit 48 is the fly ash removing unit 48 capable of performing the cleaning operation by pressure wave cleaning as described above. Another example of the highly responsive fly ash removing unit 48 is a fly ash removing unit 48 that can perform a cleaning operation by water jet cleaning or shot cleaning. In the water jet cleaning, fly ash deposited on the heat exchange section 49 is removed by jetting water from a spray nozzle toward the boiler tubes of the heat exchange section 49 . In the shot cleaning, a large number of steel balls are scattered and dropped from above the heat exchange section 49, and fly ash deposited on the heat exchange section 49 is removed by the impact of the steel balls. The steel balls are recovered below the heat exchanging section 49 and transported above the heat exchanging section 49 for reuse. Also, in a steam type soot blower, when steam generated in the heat exchange section 49 is used, a highly responsive fly ash removal section 48 can be realized. In this case, by using a steam accumulator, the cleaning operation may be immediately performed without depending on the current amount of steam generated in the heat exchange section 49 .

As described above, in the preferred exhaust gas treatment apparatus 4, the pressure wave cleaning, the water jet cleaning, the shot cleaning, or the cleaning operation using the steam generated in the heat exchange section 49 removes the fly deposited on the heat exchange section 49. A fly ash removal unit 48 capable of removing ash is utilized. As a result, the forced cleaning operation can be immediately executed based on the upstream mercury concentration, and the adsorption performance of the mercury adsorbent can be improved when the mercury concentration in the exhaust gas increases. As a result, in the exhaust gas treatment device 4, the mercury concentration in the exhaust gas can be rapidly lowered.

In the exhaust gas treatment device 4 of FIG. 1 , the temperature reduction process for temporarily lowering the temperature of the exhaust gas flowing into the bag filter 42 may be performed by means other than the fly ash removal unit 48 . For example, in the temperature reduction tower 44, the temperature reduction process can be executed by temporarily increasing the spray amount of water in an abnormal state than in normal times. Further, when a semi-dry reaction tower is provided in the incineration facility 1, the amount of water in the semi-dry reaction tower may be temporarily increased in the event of an abnormality. Furthermore, by supplying air to the upstream side flue 31 (that is, mixing the exhaust gas with air) from the air supply unit 47 indicated by the dashed block in FIG. It is also possible to lower it. As described above, in the exhaust gas treatment device 4 , the exhaust gas temperature adjustment section capable of performing temperature reduction processing may be realized by a configuration other than the fly ash removal section 48 .

The details of the construction of bag filter 42 and the preferred operation of bag filter 42 will now be described. FIG. 4 is a diagram showing the configuration of the bag filter 42. In FIG. 4, the control section 40 is also shown in blocks. The bag filter 42 includes a casing 421 , a plurality of filter cloth rows 422 and a backwash section 43 . The casing 421 is connected to the upstream flue 31 . A plurality of filter cloth rows 422 are provided inside the casing 421 . Each filter cloth row 422 is a filter cloth group including a plurality of filter cloths. Each filter cloth is, for example, bag-shaped (typically, bottomed cylindrical). In the filter cloth row 422, a plurality of filter cloths are arranged in a line. The internal spaces of the plurality of filter cloths in the plurality of filter cloth rows 422 are connected to the downstream flue 32 . Exhaust gas flowing through the upstream flue 31 passes through one of the filter cloths included in the plurality of filter cloth rows 422 and flows into the downstream flue 32 . Fly ash, mercury adsorbent, and the like contained in the exhaust gas are collected by a plurality of filter cloth rows 422 . Fly ash, mercury adsorbent, etc. are deposited on the filter cloth. As described above, the bag filter 42 is an adsorbent collecting portion that collects mercury adsorbent.

The backwash section 43 includes an air compressor 431 , a compressed air pipe 432 and a plurality of valves 434 . The air compressor 431 generates compressed air (pulse jet). The air compressor 431 is connected to one end of the compressed air pipe 432 . The other end of the compressed air pipe 432 branches into a plurality of branch pipes 433 . A plurality of valves 434 are provided in the plurality of branch pipes 433 respectively. Each branch pipe 433 has a plurality of nozzles, and the plurality of nozzles face the internal spaces of the plurality of filter cloths included in one filter cloth row 422, respectively. As will be described later, compressed air generated by the air compressor 431 is blown through the branch pipe 433 into the internal spaces of the plurality of filter cloths included in the filter cloth row 422 . The plurality of branch pipes 433 respectively correspond to the plurality of filter cloth rows 422 .

In the bag filter 42, fly ash, mercury adsorbent, and the like deposited on the filter cloths of each filter cloth row 422 are brushed off by backwashing operation using compressed air. Specifically, in the backwash operation for each filter cloth row 422, the valve 434 of the branch pipe 433 corresponding to the filter cloth row 422 is opened, and the remaining valves 434 are closed, and the air compressor 431 compresses the compressed air. It feeds into the air tube 432 . Thereby, compressed air is blown toward the internal spaces of the plurality of filter cloths included in the filter cloth row 422 . In other words, compressed air is supplied to each filter cloth of the filter cloth row 422 from the downstream side to the upstream side in the flow direction of the exhaust gas. As a result, the fly ash and the mercury adsorbent deposited on the filter cloth row 422, that is, the substances collected by the filter cloth row 422 are shaken off. Compressed gas other than air may be used in the backwash section 43 . Alternatively, fly ash, mercury adsorbent, and the like may be removed from the filter cloth rows 422 by other methods.

Next, normal operation of the bag filter 42 will be described. In the bag filter 42 , the backwashing operation is sequentially performed on the plurality of filter cloth rows 422 at regular intervals (for example, intervals of several tens of minutes, hereinafter referred to as “set intervals”). Typically, when the backwashing operation is performed on one filter cloth row 422, the backwashing operation is performed on the next filter cloth row 422 in the arrangement order of the filter cloth rows 422 after the set cycle has elapsed. executed. The order in which the backwashing operation is performed on the plurality of filter cloth rows 422 may be other than the arrangement order. Also, in the vicinity of the bag filter 42, the differential pressure between the upstream flue 31 and the downstream flue 32 is measured. When the (measured value of) the differential pressure is equal to or greater than a predetermined value, backwashing is performed on the next filter cloth row 422 even before the set cycle has elapsed since the backwashing operation on one filter cloth row 422. Action is performed. As described above, in the bag filter 42, the backwashing operation based on the set period and the backwashing operation based on the differential pressure are performed as normal operations.

Next, the operation of the bag filter 42 when the upstream mercury concentration is high will be described. FIG. 5 is a diagram showing another example of the operation of the exhaust gas treatment device 4. As shown in FIG. Steps S11 to S13 in FIG. 5 are the same as steps S11 to S13 in FIG. When the upstream mercury concentration reaches or exceeds a predetermined first threshold value (steps S11, S12), a forced cleaning operation is performed by the fly ash removal section 48 (step S13). Further, the control unit 40 determines that the condition for confirming the execution of forced backwashing (hereinafter referred to as "condition for confirming the execution of forced backwashing") is established when the upstream mercury concentration becomes equal to or higher than the first threshold value. be done. Forced backwashing is a process of executing a backwashing operation in a cycle shorter than the set cycle. Immediately after the upstream mercury concentration becomes equal to or higher than the first threshold value, forced backwashing is not performed because conditions for starting execution of forced backwashing, which will be described later, are not satisfied. As described above, in the exhaust gas treatment apparatus 4, the temperature drop of the exhaust gas due to the forced cleaning operation suppresses the rise of (the measured value of) the mercury concentration on the downstream side.

FIG. 6 is a diagram showing an example of changes in upstream mercury concentration. In the example of FIG. 6, the upstream mercury concentration becomes equal to or higher than the first threshold value V1 at time T1. After the condition for confirming execution of forced backwashing is satisfied, the control unit 40 determines whether the upstream mercury concentration has changed from a value equal to or greater than the second threshold value V2 to less than the second threshold value V2, that is, starts execution of forced backwashing. It is confirmed whether or not the execution start condition to be executed is satisfied. Although the second threshold V2 is greater than the first threshold V1 here, the second threshold V2 may be less than or equal to the first threshold V1. When the upstream mercury concentration is zero-valent mercury concentration, the second threshold value V2 is, for example, 3 to 100 μg/m ³ N. If the upstream mercury concentration is the total mercury concentration, the second threshold V2 is, for example, 30-500 μg/m ³ N.

In the example of FIG. 6, the upstream mercury concentration continues to increase even immediately after time T1 when it becomes equal to or higher than the first threshold value V1, and becomes equal to or higher than the second threshold value V2. At this point, the conditions for starting the execution of forced backwashing are not met, so forced backwashing is not started. In other words, forced backwashing is not performed when the upstream mercury concentration is high. After that, a period in which the upstream mercury concentration is equal to or higher than the second threshold value V2 continues for some time, and at time T2, the upstream mercury concentration becomes less than the second threshold value V2 (step S14). As a result, the condition for starting the execution of forced backwashing is established, and forced backwashing is started (step S15).

In forced backwashing, the backwashing operation is sequentially performed on all or part of the plurality of filter cloth rows 422 at a shorter cycle (shorter interval) than the set cycle. As a result, the mercury adsorbent that adsorbs a large amount of mercury deposited on the filter cloth rows 422 when the upstream mercury concentration is high (abnormal state) is quickly wiped off. With a mercury adsorbent that adsorbs a large amount of mercury, mercury is likely to be desorbed as the upstream mercury concentration decreases. A backwash is performed. As a result, desorption of mercury from the mercury adsorbent on the filter cloth row 422 and an increase in downstream mercury concentration are prevented or suppressed.

In forced backwashing, for example, the backwashing operation is performed on 1/10 or more of the plurality of filter cloth rows 422 in the bag filter 42 . Preferably, half or more of the plurality of filter cloth rows 422 are subjected to the backwashing operation, and more preferably, the backwashing operation is performed to all of the plurality of filter cloth rows 422 . In the following description, it is assumed that the backwashing operation is performed on all of the plurality of filter cloth rows 422 in forced backwashing. The backwashing operation in forced backwashing may be performed one or more rounds for the plurality of filter cloth rows 422 . The cycle of the backwashing operation in forced backwashing is determined, for example, within a range in which the air compressor 431 can repeatedly generate a predetermined amount of compressed air. The cycle of the backwashing operation is, for example, 1/2 or less of the set cycle, preferably 1/5 or less, and more preferably 1/10 or less.

The recovered ash (fly ash, mercury adsorbent, etc.) that is removed from the filter cloth rows 422 in the forced backwash is stored in a discharge reservoir (not shown). For example, in the discharge reservoir, mercury removal treatment is performed to volatilize the mercury contained in the recovered ash (mercury adsorbed by the mercury adsorbent) by heating the recovered ash supplied in the forced backwash. Subsequently, a chelating treatment is performed by mixing a chelating agent with the recovered ash, and then the recovered ash is discarded. If the collected ash contains a large amount of mercury, mercury may be eluted from the collected ash during the chelating process. Mercury is prevented from being eluted in the chelate treatment of .

After the forced backwash is completed, the bag filter 42 is returned to normal operation. In the bag filter 42, the backwashing operation is performed on the filter cloth row 422 next to the filter cloth row 422 on which the last backwashing operation in the forced backwashing has been performed, after the set cycle has elapsed from the last backwashing operation. be done. In addition, in the bag filter 42, the backwashing operation based on the set cycle and the backwashing operation based on the differential pressure may be performed in the same manner as in the normal time.

Next, an exhaust gas treatment apparatus of a comparative example will be described. In the exhaust gas treatment apparatus of the comparative example, forced backwashing is performed immediately after the upstream mercury concentration reaches or exceeds the first threshold value V1. In forced backwashing, the backwashing operation for the plurality of filter cloth rows 422 is sequentially performed in a short cycle. Therefore, the amount of mercury adsorbent deposited on the plurality of filter cloth rows 422 is temporarily reduced. On the other hand, immediately after the upstream mercury concentration becomes equal to or higher than the first threshold value, the upstream mercury concentration tends to increase, and the upstream mercury concentration is high. Therefore, exhaust gas having a high mercury concentration passes through the filter cloth rows 422 on which almost no mercury adsorbent is deposited, resulting in a significant increase in downstream mercury concentration.

On the other hand, in the exhaust gas treatment device 4, when the upstream mercury concentration becomes equal to or higher than the first threshold (that is, after the conditions for confirming the execution of forced backwash are satisfied), the upstream mercury concentration becomes equal to or higher than the second threshold. When the value becomes less than the second threshold value, the backwashing operation (forced backwashing) is started at a cycle shorter than the set cycle in which the backwashing operation is sequentially performed on the plurality of filter cloth rows 422 in normal times. . As a result, it is possible to suppress an increase in the downstream mercury concentration due to passage of the exhaust gas having a high mercury concentration through the filter cloth row 422 on which the mercury adsorbent is not deposited.

FIG. 7 is a diagram showing the relationship between the gas-phase mercury concentration and the equilibrium adsorption amount. As in FIG. 3, the solid line in FIG. 7 indicates the relationship between the gas-phase mercury concentration and the equilibrium adsorption amount obtained from an adsorption experiment in which a simulated exhaust gas containing mercury is passed through a mercury adsorbent for a predetermined period of time. The curve of The dashed line in FIG. 7 indicates the relationship between the gas-phase mercury concentration and the equilibrium adsorption amount obtained from a desorption experiment in which a simulated exhaust gas containing no mercury is passed through a mercury adsorbent for a predetermined period of time. curve on the far side”. As shown in FIG. 7, both the curve on the adsorption side and the curve on the desorption side increase the equilibrium adsorption amount as the vapor phase mercury concentration increases. Also, when comparing at the same equilibrium adsorption amount, the vapor phase mercury concentration indicated by the curve on the desorption side is lower than the vapor phase mercury concentration indicated by the curve on the adsorption side. Therefore, a mercury adsorbent that has adsorbed an equilibrium adsorption amount of mercury at a certain mercury concentration starts desorbing mercury at a mercury concentration lower than the mercury concentration.

As described above, in the mercury adsorbent, mercury is more likely to desorb as the upstream mercury concentration decreases. However, in reality, it takes a certain amount of time for the mercury adsorbent to adsorb the equilibrium adsorption amount of mercury, and as shown in FIG. , desorption of mercury starts at a mercury concentration lower than the mercury concentration. Therefore, as shown in FIG. 6, even if the upstream mercury concentration decreases after the upstream mercury concentration reaches a maximum at time T3, mercury is not desorbed immediately after time T3. In the exhaust gas treatment device 4, an appropriate second threshold value V2 for starting forced backwashing before the desorption amount of mercury from the mercury adsorbent becomes large is set in advance based on experiments or the like. Forced backwash is started when the mercury concentration becomes less than the second threshold value V2. As a result, when the mercury concentration on the upstream side is high, the mercury adsorbed by the mercury adsorbent on the filter cloth row 422 desorbs from the mercury adsorbent as the mercury concentration on the upstream side decreases. It becomes possible to suppress the increase. Further, when the temperature of the exhaust gas is maintained to be lowered by the forced cleaning operation until the forced backwash is performed, it is possible to more reliably suppress the detachment of mercury from the mercury adsorbent. .

In preferred forced backwashing, short-cycle backwashing operations are sequentially performed on half or more of the plurality of filter cloth rows 422 . This makes it possible to more reliably suppress an increase in the downstream mercury concentration due to desorption of mercury from the mercury adsorbent on the filter cloth rows 422 . More preferably, the short cycle backwashing operation is performed for all of the plurality of filter cloth rows 422 . As a result, it is possible to further suppress an increase in the downstream mercury concentration.

In the bag filter 42, the group of filter cloths to be backwashed at the same time does not necessarily have to be a plurality of filter cloths arranged in a row (filter cloth row). It may be an assembly of a plurality of arranged filter cloths. Also, depending on the design of the bag filter 42, one filter cloth may be regarded as a group of filter cloths, which is the execution unit of the backwashing operation.

In the example of FIG. 5, when the upstream mercury concentration becomes equal to or higher than the first threshold value and the forced cleaning operation is executed (steps S12 and S13), it is determined that the conditions for confirming the execution of forced backwash are met. Satisfaction of the conditions for confirming execution of backwashing may be determined using a third threshold value different from the first threshold value related to the execution of the forced cleaning operation.

In the example of FIG. 8, a third threshold that is smaller than the first threshold is set, and when the upstream mercury concentration becomes equal to or higher than the third threshold, it is determined that the execution confirmation condition for forced backwashing has been established (step S12a). Subsequently, the upstream mercury concentration is compared with the first threshold value and the second threshold value, and when the upstream mercury concentration becomes equal to or higher than the first threshold value (step S12), a forced cleaning operation is performed by the fly ash removing unit 48 (step S13). After that, when the upstream mercury concentration becomes less than the second threshold value (step S14), the condition for starting the execution of forced backwashing is satisfied, and forced backwashing is started (step S15). Further, when comparing the upstream mercury concentration with the first threshold and the second threshold, the upstream mercury concentration may fall below the second threshold without increasing to the first threshold (step S12) (step S12b). In this case, forced backwashing is performed without performing forced cleaning operation (step S15).

In the example of FIG. 9, a third threshold that is larger than the first threshold is set, and when the upstream mercury concentration reaches or exceeds the first threshold (step S12), a forced cleaning operation is performed by the fly ash removal unit 48 (step S13). Subsequently, the upstream mercury concentration is compared with the third threshold value and the second threshold value, and when the upstream mercury concentration becomes equal to or higher than the third threshold value, it is determined that the execution confirmation condition for forced backwashing has been established (step S14a). After that, when the upstream mercury concentration becomes less than the second threshold value (step S14), the condition for starting the execution of forced backwashing is satisfied, and forced backwashing is started (step S15). Further, when comparing the upstream mercury concentration with the third and second thresholds, the upstream mercury concentration may fall below the second threshold (step S14b) without increasing to the third threshold (step S14a). In this case, returning to step S12, the upstream mercury concentration is compared with the first threshold.

Various modifications are possible in the exhaust gas treatment device 4 .

Depending on the design of the exhaust gas treatment device 4, when the downstream mercury concentration measured by the downstream mercury concentration meter 46 is at or above a predetermined threshold value, the temperature is reduced by the exhaust gas temperature adjustment unit (for example, the fly ash removal unit 48). Processing may be performed. Also in this case, the mercury concentration of the exhaust gas can be appropriately reduced in the exhaust gas treatment device 4 . In addition, when the upstream mercury concentration becomes less than the second threshold in the abnormal state detected based on the downstream mercury concentration (when the abnormal state is detected, the upstream mercury concentration is equal to or higher than the second threshold) , and after that, when the mercury concentration on the upstream side is already less than the second threshold value when an abnormal time is detected.), the forced reverse of the bag filter 42 Washing may be initiated. As a result, it is possible to suppress an increase in the downstream mercury concentration due to passage of the exhaust gas having a high mercury concentration through the filter cloth row 422 on which the mercury adsorbent is not deposited.

On the other hand, from the viewpoint of quickly detecting an increase in the mercury concentration of the exhaust gas generated in the combustion chamber 21, an upstream mercury concentration meter that measures the mercury concentration of the exhaust gas between the combustion chamber 21 and the bag filter 42 in the exhaust gas path 45 is preferably used for detection of anomalies.

Another bag filter may be arranged between the incinerator 2 and the adsorbent supply unit 41 in the exhaust gas treatment apparatus 4 of FIG. 1 . In this case, the other bag filter collects fly ash contained in the exhaust gas, and the bag filter 42 mainly collects the mercury adsorbent supplied to the flue 3 by the adsorbent supply unit 41 .

If the upstream mercury concentration meter 45 can measure the mercury concentration of the exhaust gas on the upstream side in the flow direction of the exhaust gas with respect to the bag filter 42, the intake port of the upstream mercury concentration meter 45 is provided at an arbitrary position. can be Similarly, if the downstream mercury concentration meter 46 can measure the mercury concentration of the exhaust gas downstream in the flow direction of the exhaust gas with respect to the bag filter 42, the inlet of the downstream mercury concentration meter 46 can be placed at any position. (For example, it may be provided in the downstream flue 32 other than the chimney 51).

The exhaust gas treatment device 4 may be used in equipment other than the incineration equipment 1 .

The configurations in the above embodiment and each modified example may be combined as appropriate as long as they do not contradict each other.

3 Flue 4 Exhaust gas treatment device 21 Combustion chamber 23 Discharge channel 40 Control unit 41 Adsorbent supply unit 42 Bag filter 44 Temperature reduction tower 45 Upstream mercury concentration meter 46 Downstream mercury concentration meter 47 Air supply unit 48 Fly ash removal unit 49 Heat exchange unit 422 Filter cloth rows S11 to S15, S12a, S12b, S14a, S14b Step

Claims (8)

An exhaust gas treatment device,
an adsorbent supply unit that supplies a mercury adsorbent to the exhaust gas in an exhaust gas path through which the exhaust gas generated in the combustion chamber flows;
an adsorbent collection unit that collects the mercury adsorbent in the exhaust gas path;
a heat exchanging portion disposed between the combustion chamber and the adsorbent collecting portion in the exhaust gas path and performing heat exchange between the exhaust gas and a predetermined fluid;
an upstream mercury concentration meter that measures the mercury concentration of the exhaust gas as an upstream mercury concentration between the combustion chamber and the adsorbent collecting portion in the exhaust gas path;
Pressure wave cleaning, water injection cleaning, shot cleaning, or cleaning operation using steam generated in the heat exchange section can remove fly ash accumulated in the heat exchange section, and the upstream mercury concentration A fly ash removal unit that performs the cleaning operation based on
with
The exhaust gas treatment apparatus , wherein the fly ash removal unit performs the cleaning operation when the upstream mercury concentration is above a predetermined threshold . The exhaust gas treatment apparatus according to claim 1,
The exhaust gas treatment apparatus, wherein the upstream mercury concentration meter measures the zero-valent mercury concentration of the exhaust gas as the upstream mercury concentration. An exhaust gas treatment device,
an adsorbent supply unit that supplies a mercury adsorbent to the exhaust gas in an exhaust gas path through which the exhaust gas flows;
an adsorbent collection unit that collects the mercury adsorbent in the exhaust gas path;
a mercury concentration meter for measuring the mercury concentration of the exhaust gas;
an exhaust gas temperature adjustment unit capable of executing a temperature reduction process for temporarily lowering the temperature of the exhaust gas flowing into the adsorbent collection unit;
a control unit that causes the exhaust gas temperature adjustment unit to perform the temperature reduction process when the mercury concentration is above a predetermined threshold value;
with
A heat exchange section that exchanges heat between the exhaust gas generated in the combustion chamber and a predetermined fluid is disposed between the combustion chamber and the adsorbent collection section in the exhaust gas path,
The exhaust gas treatment apparatus, wherein the exhaust gas temperature control unit has a fly ash removal unit that removes fly ash deposited on the heat exchange unit . The exhaust gas treatment apparatus according to claim 3 ,
The fly ash removal unit removes the fly ash accumulated in the heat exchange unit by pressure wave cleaning, water injection cleaning, shot cleaning, or cleaning operation using steam generated in the heat exchange unit. An exhaust gas treatment device characterized by: The exhaust gas treatment device according to claim 3 or 4 ,
The exhaust gas treatment apparatus, wherein the mercury concentration meter measures the mercury concentration of the exhaust gas on the upstream side in the flow direction of the exhaust gas with respect to the adsorbent collecting section. The exhaust gas treatment apparatus according to claim 5 ,
The exhaust gas treatment apparatus, wherein the mercury concentration meter measures the concentration of zero-valent mercury in the exhaust gas. The exhaust gas treatment apparatus according to any one of claims 3 to 6 ,
The adsorbent collecting unit collects the mercury adsorbent with a plurality of filter cloth groups, and shakes off the mercury adsorbent from the filter cloth groups by backwashing each of the plurality of filter cloth groups,
The control unit sequentially performs the backwashing operation on the plurality of filter cloth groups at a set cycle under normal conditions, and in the abnormal condition, the flow direction of the exhaust gas with respect to the adsorbent collection unit. When the mercury concentration of the exhaust gas on the upstream side changes from a value equal to or greater than a second threshold value to less than the second threshold value, the exhaust gas treatment apparatus starts the backwash operation at a cycle shorter than the set cycle. . An exhaust gas treatment method in an exhaust gas treatment apparatus,
The exhaust gas treatment device is
an adsorbent supply unit that supplies a mercury adsorbent to the exhaust gas in an exhaust gas path through which the exhaust gas flows;
an adsorbent collection unit that collects the mercury adsorbent in the exhaust gas path;
an exhaust gas temperature adjustment unit capable of executing a temperature reduction process for temporarily lowering the temperature of the exhaust gas flowing into the adsorbent collection unit;
with
The exhaust gas treatment method is
a) measuring the mercury concentration of the exhaust gas;
b) a step of causing the exhaust gas temperature adjustment unit to perform the temperature reduction process when the mercury concentration is abnormally equal to or higher than a predetermined threshold;
with
A heat exchange section that exchanges heat between the exhaust gas generated in the combustion chamber and a predetermined fluid is disposed between the combustion chamber and the adsorbent collection section in the exhaust gas path,
The exhaust gas treatment method , wherein in the step b), the fly ash deposited on the heat exchange unit is removed by the exhaust gas temperature control unit .

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