JP2019027672A - Processing apparatus for flue gas - Google Patents

Abstract

To stably keep hydrargyrum concentration in flue gas discharged from a smokestack at a regulation value or less.SOLUTION: There is provided a processing apparatus for flue gas. The processing apparatus comprises: a combustion furnace 12; heat exchange apparatuses 17, 18, 19, 20 for heat exchange of exhaust gas generated by the combustion furnace 12; ash removal apparatuses 21, 22, 23 for sweeping hydrargyrum containing ash accumulated in the heat exchange apparatuses 17, 18, 19, 20; a charge apparatus 38 for hydrargyrum removal agent charging the hydrargyrum removal agent into the flue gas; a controlling apparatus 45 controlling the charge apparatus 38 for the hydrargyrum removal agent to charge the hydrargyrum removal agent upon sweeping operation of the hydrargyrum containing ash by the ash removal apparatuses 21, 22, 23; and a recovery apparatus 33 recovering hydrargyrum removal agent absorbing hydrargyrum due to use for hydrargyrum removal from the flue gas.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a combustion exhaust gas treatment apparatus, and more particularly to a combustion exhaust gas treatment apparatus for removing mercury from combustion exhaust gas.

  Waste and coal may contain mercury. Therefore, from the viewpoint of preventing air pollution, the flue gas generated when burning waste and coal is monitored if the mercury concentration in the flue gas is monitored and the mercury concentration in the flue gas increases abnormally. It is necessary to detect and deal with it early.

  For example, in a waste incinerator, waste that is incinerated on a daily basis contains almost no mercury. For this reason, the mercury concentration in the combustion exhaust gas does not normally reach a problematic level even without special mercury countermeasures. However, when waste containing mercury is put into an incinerator and burned, it becomes an abnormal time when the amount of mercury in the combustion exhaust gas rises rapidly. Therefore, it is sufficient to detect mercury abnormalities at an early stage and to take special mercury removal measures only when abnormalities are detected to remove mercury from combustion exhaust gas.

  As an apparatus that has taken such measures, there is one described in Patent Document 1. In the apparatus described in Patent Document 1, when a mercury continuous analyzer for detecting the concentration of mercury contained in the exhaust gas flowing through the flue and the mercury concentration detected by the mercury continuous analyzer exceed a predetermined concentration, And means for opening a path for introducing activated carbon for adsorption of mercury into the flue.

JP-A-9-308817

  However, for example, in a waste incinerator, detection of mercury concentration with a continuous mercury analyzer takes time even when the mercury concentration in the combustion exhaust gas suddenly increases. For this reason, there is a problem that it takes a long time to put the mercury-adsorbing drug after the detection.

  In addition, when the mercury concentration in the combustion exhaust gas suddenly rises, it is difficult to control the timing at which the mercury-adsorbing chemical is introduced because the mercury concentration exceeds the regulation value irregularly and rapidly.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve such problems and to keep the mercury concentration discharged from the chimney stably below a regulation value.

In order to achieve this object, the flue gas treatment apparatus of the present invention comprises:
A combustion furnace;
A heat exchange device for exchanging heat from the flue gas generated in the combustion furnace;
A fly ash removal device for removing mercury-containing fly ash deposited on the heat exchange device;
A mercury-removing agent injection device for introducing a mercury-removing agent into combustion exhaust gas;
A control device for controlling the mercury-removing chemical to be introduced into the combustion exhaust gas by the mercury-removing chemical charging device when the mercury-containing fly ash is dropped off by the fly ash removing device;
And a recovery device that recovers the mercury-removing chemical that has taken in mercury from the combustion exhaust gas by being used for mercury removal.

  According to the apparatus for treating flue gas of the present invention, the apparatus for introducing a mercury removing chemical is for pouring a dry chemical that adsorbs mercury in the flue gas into the flue gas, and the recovery apparatus adsorbs mercury. It is preferable that the dust collecting device collects the dry chemical.

  According to the combustion exhaust gas treatment apparatus of the present invention, the mercury removal chemical input device is for supplying cleaning water to which the wet chemical adsorbing mercury in the combustion exhaust gas is added into the combustion exhaust gas, and the recovery device is It is preferable that the cleaning device recovers the wet chemical adsorbing mercury.

  According to the combustion exhaust gas treatment apparatus of the present invention, when the control device wipes off the mercury-containing fly ash deposited on the heat exchange device by the fly ash removal device, the amount of mercury removal agent introduced into the combustion exhaust gas Is preferably increased as compared with the case where the payout is not performed.

  According to the combustion exhaust gas treatment device of the present invention, the control device further includes an alkaline chemical charging device for charging an alkaline chemical into the combustion exhaust gas, and the control device removes mercury-containing fly ash deposited on the heat exchange device by the fly ash removal device. It is preferable that the amount of alkali chemicals introduced into the combustion exhaust gas is reduced when the amount is removed compared to when the amount is not removed.

  According to the present invention, when the mercury-containing fly ash deposited on the heat exchange device for exchanging heat from the combustion exhaust gas generated in the combustion furnace is removed by the fly ash removal device, Since the removal chemical is introduced into the combustion exhaust gas, mercury contained in the combustion exhaust gas accompanying the maintenance of the heat exchange device can be effectively removed (recovered) from the combustion exhaust gas. Therefore, according to the present invention, the mercury concentration discharged from the chimney can be stably kept below the regulation value.

It is a figure which shows the structure of the processing apparatus of the combustion exhaust gas of embodiment of this invention. It is a figure which shows the structure of the heat exchange apparatus in FIG. It is a figure which shows the example of the detection result of mercury concentration. It is a figure which shows the structure of the processing apparatus of the combustion exhaust gas of other embodiment of this invention. It is a figure which shows the structure of the processing apparatus of the combustion exhaust gas of other embodiment of this invention.

(First embodiment)
FIG. 1 shows a treatment apparatus for combustion exhaust gas from a waste incinerator 11 as an example of an incinerator. The waste incinerator 11 includes an incinerator 12, a first flue 13, a second flue 14, a third flue 15, and a gas discharge port 16 provided at the downstream end of the third flue 15. Prepare. A superheater boiler pipe 17 is installed in the third flue 15 as a heat exchange device.

  FIG. 2 shows the detailed structure of the superheater boiler tube 17. In the illustrated example, the superheater boiler pipe 17 includes a first superheater boiler pipe 18, a second superheater boiler pipe 19, and a third superheater in order from the upstream side to the downstream side in the third flue 15. A boiler pipe 20. And the 1st-3rd soot blower 21, 22, 23 is installed in connection with the 1st-3rd superheater boiler pipes 18, 19, and 20, respectively. In FIG. 1, 24, 25, and 26 are on-off valves for the first to third soot blowers 21, 22, and 23 in FIG. 27 is a soot blower control device for controlling the operation of each on-off valve 24, 25, 26.

  In FIG. 1, an exhaust gas path 31 is a flue from the waste incinerator 11 to the chimney 32. In the exhaust gas path 31, a bag filter 33 that exhibits a dust collecting function is installed as a recovery device. In the illustrated apparatus, an inlet 34 for a mercury removing agent is provided upstream of the bag filter 33 in the exhaust gas path 31. The mercury removing chemical tank 35 is a tank for storing the mercury removing chemical, and the stored mercury removing chemical is supplied to the combustion exhaust gas in the exhaust gas path 31 via the supply path 36 and the inlet 34. It is possible to throw in (spray). The feed path 36 is provided with a rotary valve 37 for adjusting the feed amount. The mercury removing chemical agent charging device 38 includes a mercury removing chemical tank 35, a rotary valve 37, and a feeding path 36.

  As the mercury removal agent, activated carbon, iodine-attached activated carbon, and sulfur-attached activated carbon, which are dry chemicals, are preferably used.

  The inlet 34 in the exhaust gas path 31 is provided on the downstream side of the gas outlet 16 of the garbage incinerator 11 and upstream of the bag filter 33. The first exhaust gas sampling port 41 is provided on the downstream side of the gas discharge port 16 of the garbage incinerator 11 and on the upstream side of the input port 34. The first mercury analyzer 42 communicates with the sampling port 41 and can detect the concentration of mercury in the sampled exhaust gas.

  A second exhaust gas sampling port 43 is provided downstream of the bag filter 33 in the exhaust gas path 31. The second mercury analyzer 44 communicates with the sampling port 43 and can detect the concentration of mercury in the sampled exhaust gas. The second mercury analyzer 44 may be installed on the downstream side of the bag filter 33 in the exhaust gas path 31, and is preferably installed in the chimney 32.

  As the first and second mercury analyzers 42 and 44, various devices (atomic mercury meter, form-specific mercury meter, total mercury meter) can be used. Among these, as the first mercury analyzer 42, the one described in International Publication No. 2016/136714 can be suitably used. The mercury analyzer described in this international publication detects the amount of zero-valent atomic mercury contained in the sampling gas, and the amount of divalent mercury constituting the mercury compound such as soluble mercury salt contained in the sampling gas is By detecting only the amount of zero-valent atomic mercury and not detecting the amount of divalent mercury, it is possible to detect an increase in the amount of mercury more quickly than accurate measurement of the amount of mercury. It is what I did.

  The control device 45 can input detection signals from the first and second mercury analyzers 42 and 44 and can output a control signal to the rotary valve 37 in order to adjust the rotational speed of the rotary valve 37. is there. The control device 45 can exchange signals with the soot blower control device 27.

Next, the operation of the combustion exhaust gas processing apparatus configured as described above will be described. In the waste incinerator 11, the waste that is routinely incinerated as described above contains almost no mercury (for example, a mercury concentration of 0 to 30 μg / m ³ N). Therefore, normally, by making the rotational speed of the rotary valve 37 slightly by the control device 45, a small amount of mercury-removing agent is always added to the combustion exhaust gas (for example, activated carbon 10 to 50 mg / m ³ N). It ’s enough.

However, when waste containing mercury is put into the incinerator 11 and burned, it becomes an abnormal time when the amount of mercury in the combustion exhaust gas rapidly rises. This is quickly detected by the first mercury analyzer 42, and the rotational speed of the rotary valve 37 is increased so that the required amount of mercury-removing chemical is increased and introduced into the exhaust gas. Similarly, when the second mercury analyzer 44 detects a mercury amount that exceeds the specified value, the rotational speed of the rotary valve 37 is similarly increased and a required amount of mercury-removing chemical is introduced into the exhaust gas. That is, feedforward control is performed based on the detection result of the first mercury analyzer 42, and feedback control is performed based on the detection result of the second mercury analyzer 44. Although it is possible to perform only one of these controls, mercury in the exhaust gas can be more reliably removed by the chemical by using both in combination. When the drug is activated carbon, mercury is adsorbed and removed by the activated carbon. Specifically, these controls can be PID control or other appropriate control forms.

  A chemical such as activated carbon that has adsorbed mercury is subjected to filtering processing in the bag filter 33, and is recovered from the exhaust gas in the bag filter 33. The mercury-containing drug collected by the bag filter 33 is appropriately discharged out of the system. Specifically, in the bag filter 33, combustion fly ash, a mercury removing agent, a reaction product of the agent and mercury, and the like are collected and deposited on the filter as a dust layer. Then, for example, the constituents of the dust layer are wiped off as dust ash by backwashing using compressed air at predetermined time intervals. The dust ash that has been removed is discharged outside the system in principle. Alternatively, since the dust collection ash that has been removed contains unused exhaust gas treatment chemicals, the dust collection ash may be transported upstream of a bag filter as a dust collector by air conveyance or conveyor conveyance and reused.

  By the way, in the 3rd flue 15 of the waste incinerator 11, garbage is incinerated by the incinerator 12 of the waste incinerator 11 by the 1st-3rd superheater boiler pipes 18, 19, and 20 shown by FIG. The fly ash generated at the time of accumulation accumulates. And as for each superheater boiler pipe | tube 18,19,20, while fly ash accumulates, while heat recovery efficiency falls, there exists a possibility that piping may be corroded by the chlorine component contained in accumulation fly ash. For this reason, it is necessary to perform the work of periodically removing the accumulated fly ash by the soot blowers 21, 22, and 23. The scraping work by the soot blowers 21, 22, 23 is performed by blowing steam to the superheater boiler tubes 18, 19, 20. By carrying out this operation for about 30 minutes to 1 hour, the deposited fly ash can be removed.

  Further, when mercury-containing material is incinerated in the incinerator 12, mercury may be contained in the accumulated fly ash of the superheater boiler tubes 18, 19, and 20. For this reason, when deposit fly ash is removed, the mercury-containing fly ash that has been removed is discharged from the gas discharge port 16 of the waste incinerator 11 to the exhaust gas path 31.

As a result of the above-described deposit fly ash removal operation, the mercury concentration detected by the first mercury analyzer 42 and the second mercury analyzer 44 increases (for example, 30 to 1000 μg / m ³ N). Accordingly, in the same manner as described above, a large amount of mercury-removing chemical is introduced into the exhaust gas from the input device 38 (for example, 50 to 500 mg / m ³ N), thereby collecting the mercury scattered during the deposited fly ash removal operation. be able to. For example, it is possible to adopt a configuration in which a large amount of mercury removing chemical is introduced into the exhaust gas from the input device 38 only when the operation of removing the accumulated fly ash from the second and third superheater boiler tubes 19 and 20 is included. . Note that a large amount of mercury-removing agent is contained in the exhaust gas from the charging device 38 regardless of the mercury concentration detected by the first mercury analyzer 42 and the second mercury analyzer 44 at the time of deposit fly ash removal work. May be input. If the mercury concentration measured by the first mercury analyzer 42 and the second mercury analyzer 44 does not increase, it is determined that mercury is not contained in the deposited fly ash, and the charging device 38 It is not necessary to put a large amount of mercury removing chemicals into the exhaust gas.

  FIG. 3 shows an example of detection results of mercury concentration by the first and second mercury analyzers 42 and 44. The horizontal axis represents time, and the vertical axis represents mercury concentration. When the soot blowers 21, 22, and 23 carry out the operation of dropping the deposited fly ash, the mercury concentration rapidly increases in the exhaust gas path 31, and this is the case as shown in the first mercury analyzer 42 and the second mercury analyzer. 44.

  In the above description, a case has been described in which the mercury concentration in the exhaust gas path 31 at the time of carrying out the dropping operation is detected and controlled by the first mercury analyzer 42 or the second mercury analyzer 44. However, according to the present invention, for example, it is also possible to control using only the mercury concentration detection result by one of the mercury analyzers 42 or 44. Alternatively, when the mercury concentration in the exhaust gas path 31 at the time of carrying out the dropping operation can be predicted by an empirical rule or the like, an amount of mercury removing agent corresponding to the predicted value of the concentration is exhausted without detecting the mercury concentration. It is also possible to adopt a method of putting in the path 31. As the collecting device, in addition to the bag filter 33, an appropriate dry dust collecting device or the like can be used.

  In the above description, the first to third soot blowers 21, 22, and 23 have been described as fly ash removal devices for removing mercury-containing fly ash deposited on the first to third superheater boiler tubes 18, 19, and 20. . However, the fly ash removal device may be any as long as the deposited fly ash can be removed, and the fly ash removal device may be deposited by, for example, hitting the surface of the superheater boiler tube with a hammer or applying a shock wave. It may be one that removes fly ash.

  The soot blower control device 27 and the control device 45 can be configured by a single control device.

(Second Embodiment)
FIG. 4 shows a flue gas treatment apparatus according to another embodiment of the present invention. Here, in addition to the apparatus configuration shown in FIG. 1, an apparatus 51 for introducing an alkaline chemical into exhaust gas is provided. The charging device 51 includes a charging port 52 provided upstream of the bag filter 33 in the exhaust gas path 31, an alkaline chemical tank 53 for storing alkaline chemicals, and a supply path from the alkaline chemical tank 53 to the charging port 52. 54 and a rotary valve 55 provided in the supply path 54. The first acid gas concentration detection device 56 communicates with a first sampling gas port 57 provided in a portion of the exhaust gas path 31 upstream of the input port 52. The second acid gas concentration detection device 58 communicates with a second sampling gas port 59 provided in a portion of the exhaust gas passage 31 on the downstream side of the bag filter 33. As the first and second acid gas concentration detection devices 56 and 58, for example, the concentration of hydrogen chloride is detected, and a known appropriate device can be used in detail. Detection signals from the detection devices 56 and 58 are sent to the control device 45, and the control signal from the control device 45 is used for adjusting the rotational speed of the rotary valve 55.

  The combustion exhaust gas may contain, for example, the above-described hydrogen chloride as an acidic gas. Therefore, the concentrations of the first and second acid gas concentrations are detected by the detection devices 56 and 58, and the control device 45 normally controls the rotational speed of the rotary valve 55 by feedback control or feedforward control. , Alkaline chemicals are always added to the combustion exhaust gas. That is, the control of the amount of the alkaline chemicals is performed by feedforward control based on the detection result of the first acid gas component concentration detection device 56, and feedback control is performed based on the detection result of the second acid gas component concentration detection device 58. Do. These controls can be performed only in either one, but by using both in combination, the acidic gas component in the exhaust gas can be more reliably removed by the chemical. Specifically, these controls can be PID control or other appropriate control forms.

  The alkaline agent causes a neutralization reaction with the acidic gas component, and the reaction product is collected by the bag filter 33. As the alkaline agent, calcium hydroxide (slaked lime), sodium hydrogencarbonate (bicarbonate), dolomite hydroxide, and the like can be suitably used.

  By the way, the mercury contained in the combustion exhaust gas from the waste incinerator 11 is divalent mercury about 70 to 90% by mass upstream of the bag filter 33, which is a dust collector, and the rest is 0 valence, according to the form of mercury. It is supposed to exist in the form of mercury. Of these, divalent mercury reacts with hydrogen chloride contained in the combustion exhaust gas to produce mercury chloride that is easily collected by the bag filter.

  However, if the combustion exhaust gas contains a large amount of alkali chemicals, the alkali chemicals reduce hydrogen chloride in the combustion exhaust gas, so the hydrogen chloride contained in the combustion exhaust gas reacts with divalent mercury and the bag filter The production of mercury chloride which is easily collected by the water.

  In particular, if a large amount of alkali chemicals is contained in the combustion exhaust gas and the dust layer deposited on the bag filter, the mercury adsorption reaction by the mercury removing chemicals cannot be actively performed. Specifically, a part of the adsorption reaction of mercury by the mercury removing agent is performed in the dust layer deposited on the bag filter 33. A part of the reaction between the alkaline chemical and the acidic gas component is also performed in the dust layer deposited on the bag filter 33. Accordingly, when the dust layer deposited on the bag filter 33 contains a large amount of alkali chemicals, the alkaline chemicals reduce the hydrogen chloride in the dust layer, so that the hydrogen chloride contained in the combustion exhaust gas reacts with divalent mercury. This hinders the generation of mercury chloride that is easily collected by the bag filter. For this reason, when a lot of alkali chemicals are contained in the dust layer, the mercury adsorption reaction by the mercury removing chemicals is not actively performed.

  Therefore, before the accumulated fly ash of the first to third superheater boiler tubes 18, 19, 20 shown in FIG. 2 is removed by the soot blowers 21, 22, 23, the dust layer deposited on the bag filter 33 is It is preferable to use a dust layer for a soot blower with more mercury removal agents and fewer alkali agents than usual. As a method for specifically reducing the amount of the alkaline agent input, for example, a method of changing the set value of the second mercury analyzer 44 for feedforward control and feedback control to reduce the amount of the alkali agent to be specifically reduced can be considered. It is done.

  When the amount of alkali chemicals to be charged is particularly small, the alkaline chemicals are charged while monitoring the detection results of the first acidic gas component concentration detection device 56 and the second acidic gas component concentration detection device 58. It is confirmed that there is no problem even if the amount is reduced (the exhaust gas regulation value of the chimney 32 is not exceeded).

  The sampling gas port 57 for the first acid gas component concentration detection device 56 only needs to be installed on the upstream side of the bag filter 33 as a dust collector in the exhaust gas path 31, for example, illustration is omitted. It is preferable to be installed between the temperature reducing tower and the bag filter 33, and more preferably upstream from the temperature reducing tower. The sampling port 59 for the second acid gas component concentration detection device 58 may be installed on the downstream side of the bag filter 33 in the exhaust gas path 31, and is preferably installed in the chimney 32.

(Third embodiment)
FIG. 5 shows a combustion exhaust gas processing apparatus according to still another embodiment of the present invention. This processing apparatus is a wet type processing apparatus in which a chelating agent is charged instead of the dry processing apparatus described so far. In this wet processing apparatus, a cleaning device 61 as a recovery device is provided in the exhaust gas path 31. The cleaning device 61 includes a mercury removing chelate tank 62 that stores a mercury removing chelating agent serving as a mercury removing agent charging device, and an alkali that stores an alkaline agent (for example, a liquid alkaline agent such as caustic soda water). A medicine tank 63 is also provided. The mercury removing chelating agent 62 in the mercury removing chelating tank 62 and the alkaline agent in the alkaline agent tank 63 are in the form of washing water containing the chelating agent and the alkaline agent, and the valve 64 whose opening degree is adjusted by the controller 45. , 65 to be supplied to the cleaning device 61. Note that the cleaning water of the cleaning device 61 is continuously replaced with an appropriate amount of new cleaning water to recover mercury contained in the cleaning water.

  When the mercury removing chelating agent stored in the mercury removing chelating tank 62 is supplied to the cleaning device 61, it can take in mercury in the combustion exhaust gas and form a chelate complex. In the cleaning device 61, the acidic gas in the combustion exhaust gas is removed by adding the alkaline chemical from the alkaline chemical tank 63 to the cleaning water and introducing it into the combustion exhaust gas. Also in the system shown in FIG. 5, the first to third superheater boiler pipes 18, 19, 20 are provided by the first to third soot blowers 21, 22, 23, as in the case of the processing apparatus shown in FIG. 4. Before the accumulated fly ash is removed, it is preferable to add a washing water for a soot blower in which the chelating agent for removing mercury is increased and the alkali chemicals are decreased.

(Other)
In any of the above-described embodiments, an activated carbon adsorption tower can be installed on the downstream side of the bag filter 33 along the exhaust gas path 31.

  In the above, the waste incinerator was illustrated as a generation source of combustion exhaust gas from which mercury should be removed. However, the present invention is not limited to this, and can also be applied to combustion exhaust gas from other devices such as a coal combustion device.

  In any of the above-described embodiments, an auxiliary agent for adjusting the thickness of the dust layer in the bag filter 33 can be introduced at any position upstream of the bag filter 33 or the exhaust gas path 31. A configuration can be employed. As the auxiliary agent, “Bag Ace (registered trademark)” manufactured by Hitachi Zosen, activated carbon, or the like can be preferably used.

  In each of the above-described embodiments, the rotary valve is exemplified as an input device for various drugs. However, any device that can control the supply amount of the drug may be used, and an apparatus that supplies the drug cut out by the table feeder by air conveyance with a blower. Etc. can be used.

  In addition, each structure demonstrated above can be suitably combined in the range which is not mutually contradictory. For example, the recovery device may be a combustion exhaust gas processing device including both a dry processing device and a wet processing device.

11 Waste incinerator 12 Incinerator 17 Superheater boiler tube (heat exchange device)
18 1st superheater boiler pipe (heat exchange device)
19 Second superheater boiler tube (heat exchange device)
20 3rd superheater boiler pipe (heat exchange device)
21 First soot blower (fly ash removal device)
22 Second soot blower (fly ash removal device)
23 Third soot blower (fly ash removal device)
27 Soot blower control device 33 Bag filter (collection device)
38 Mercury Removal Agent Input Device 42 First Mercury Analyzer 44 Second Mercury Analyzer 45 Controller

Claims (5)

A combustion furnace;
A heat exchange device for exchanging heat from the flue gas generated in the combustion furnace;
A fly ash removal device for removing mercury-containing fly ash deposited on the heat exchange device;
A mercury-removing agent injection device for introducing a mercury-removing agent into combustion exhaust gas;
A control device for controlling the mercury-removing chemical to be introduced into the combustion exhaust gas by the mercury-removing chemical charging device when the mercury-containing fly ash is dropped off by the fly ash removing device;
A recovery device that recovers mercury-removing chemicals that have taken in mercury from combustion exhaust gas by being used for mercury removal;
An apparatus for treating combustion exhaust gas, comprising: The mercury removal chemical injection device is used to input a dry chemical that adsorbs mercury in the combustion exhaust gas into the combustion exhaust gas.
The recovery device is composed of a dust collector that recovers the dry chemical adsorbed with mercury.
The apparatus for treating a flue gas according to claim 1. The mercury removal chemical injection device is for supplying cleaning water to which the wet chemical that adsorbs mercury in the combustion exhaust gas is added to the combustion exhaust gas.
The recovery device is composed of a cleaning device that recovers the wet chemical adsorbed with mercury.
The apparatus for treating a combustion exhaust gas according to claim 1 or 2. When the mercury-containing fly ash deposited on the heat exchange device is wiped off by the fly ash removal device, the control device is less than the amount of the mercury removal chemical input into the combustion exhaust gas when the removal is not performed. To increase,
The apparatus for treating a combustion exhaust gas according to any one of claims 1 to 3, wherein: Further equipped with an alkali chemical injection device for introducing an alkaline chemical into the combustion exhaust gas,
The control device reduces the amount of alkali chemicals injected into the combustion exhaust gas when the mercury-containing fly ash deposited on the heat exchange device is removed by the fly ash removal device, compared to when the removal is not performed. Is,
The apparatus for treating a combustion exhaust gas according to any one of claims 1 to 4, characterized in that:

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