JP5758181B2 - Dry desulfurization method and apparatus - Google Patents

Description

The present invention relates to a dry desulfurization method and apparatus. Specifically, the present invention relates to exhaust gas discharged from combustion furnaces, incinerators, pyrolysis furnaces, melting furnaces, etc., such as coal, sewage sludge, industrial wastewater sludge, various industrial wastes, biomass or municipal waste. The present invention relates to a dry desulfurization method and apparatus used for purification. The present invention particularly relates to a dry desulfurization method and apparatus capable of removing acidic gas, particularly sulfur oxide (SO _x ) contained in exhaust gas, at low temperature and dry.

  For example, in a waste (garbage) incinerator, the input garbage is burned with combustion air in the incinerator. The combustion exhaust gas from the incinerator is guided to the boiler through the top of the furnace. In the boiler, this exhaust gas heats the feed water to generate high-temperature and high-pressure steam. The exhaust gas that has been heat-recovered by generating steam in the boiler is discharged from the chimney after the temperature is lowered and various solid substances such as incineration fly ash and acid gases are removed by a bag filter.

Here, in bag filter, when purifying exhaust gas, HCl, and neutralizing agents such as slaked lime to neutralize the acid gas components of the SO _X or the like, as well as the reaction aid such diatomaceous earth is blown into the exhaust gas. The reaction aid is for forming a stable cake layer on the filter cloth surface of the bag filter. This cake layer is removed along with the acid gas component. Backwashing is performed when the cake layer becomes thick and the pressure loss rises to a predetermined value. That is, backwashing is performed at a certain frequency. Such a method is one method of dry desulfurization and has been widely used in municipal waste incinerators.

  On the other hand, with regard to attempts to employ dry desulfurization in coal-fired furnaces and coal-mixed furnaces, desulfurization agents that have been researched and developed for that purpose have not been widely used because of cost bottlenecks (Cited Document 1: Special Reference). Kaihei 1-284323). Only the active coke method has been put into practical use, but it is difficult to regenerate, and this is also not cost-effective (Cited document 2: Japanese Patent Laid-Open No. 58-213614).

  Moreover, in the dry desulfurization of the sewage sludge incinerator, in-furnace desulfurization in which a desulfurizing agent is supplied to a high temperature zone around 850 ° C. is the mainstream, and dry desulfurization at a low temperature has not been achieved (cited document 3: Japanese Patent Laid-Open No. 2001-248817). Issue gazette).

Further, in the municipal waste incinerator described above, when a Ca (calcium) alkaline reagent is supplied to neutralize and remove HCl (hydrogen chloride) by a method using a bag filter, SO _X (sulfur oxidation) is simultaneously performed. The method of removing a thing) is prevailing. Here, in the municipal waste incinerator, the SO _X concentration in the exhaust gas is as low as 50 to 60 ppm. In contrast, SO _X concentration is much higher coal-furnace coal co-firing furnace or the exhaust gas from sewage sludge incinerator, be blown reactants by applying this method in large quantities, sufficient SO _X concentration It could not be reduced.

For the same reason, dry desulfurization has not been performed on industrial furnace wastewater sludge having a medium SO _X concentration or combustion furnace exhaust gas for various industrial wastes.

  Attempts have also been made to use sodium-based desulfurization agents such as baking soda. However, chemicals such as baking soda are expensive and are not worth the cost.

JP-A-1-284323 JP 58-213614 A JP 2001-248817 A

As a result of intensive studies on the above circumstances, the present inventors have used a Ca (calcium) -based alkaline agent, for example, Ca (OH) ₂ (slaked lime) as a reactant, and have a high concentration (200 to 800 ppm). The inventors have come up with a dry desulfurization method and apparatus capable of removing SO _X. That is, an object of the present invention is to provide a dry desulfurization method and apparatus capable of dry desulfurization of exhaust gas having a high SO _X concentration without using an expensive reactant. As a result of diligent research on why desulfurization is limited when using an inexpensive ordinary reactant such as slaked lime, the present inventors have found that Cl components such as HCl and Cl ₂ (chlorine and / or chlorine compounds) in the exhaust gas are present. It was discovered that the desulfurization reaction abruptly attenuates when the amount of SOx is below a certain level (Cl / SO _X is 0.5 or less in molar ratio). Therefore, by devising a configuration that compensates for this Cl from exhaust gas or reaction products, it is possible to dry-desulfurize exhaust gas having a high SO _X concentration without adding an expensive reactant from the outside. is there.

In order to achieve the above object, the dry desulfurization method according to the present invention performs dry desulfurization of exhaust gas having a high SO _X concentration and containing gas components such as HCl and Cl ₂ (chlorine and / or chlorine compounds). / SO _X is a dry desulfurization method for dry desulfurization of one or more exhaust gases with a molar ratio of Cl / SO _X > 0.8, preferably in the exhaust gas introduced into the first stage bag filter Then, a Ca (calcium) -based alkaline agent is added, and after passing through the first stage dry desulfurization step and the first stage dry desulfurization step, Cl 2 is added to the exhaust gas introduced into the second stage bag filter. In this step, a Ca (calcium) alkaline agent is added and the second-stage dry desulfurization is carried out, while the charge ratio Cl / SO _X to the second-stage bag filter is a molar ratio. a Cl _/ SO X> 0.5 Characterized in that it comprises a step which is adapted to urchin adjusted.
In the dry deflowing method according to the present invention, in one embodiment thereof, by bypassing a part of the exhaust gas introduced into the first stage bag filter and bypassing the second stage bag filter, Cl can be replenished to the exhaust gas introduced into the second stage bag filter.

In the dry deflowing method according to the present invention, in one embodiment, sodium bicarbonate may be added to the second-stage bag filter in addition to the Ca (calcium) alkaline agent.
Further, in the dry desulfurization method according to the present invention, in its one embodiment, the first stage SO _X concentration meter provided on the downstream of the bag filter of, based on the detection result by the HCl concentration meter, the first stage By bypassing the exhaust gas from the bag filter, the amount of exhaust gas bypassed to the second stage bag filter is determined.

In the dry desulfurization method according to the present invention, in one embodiment, the SO _X concentration detected by the SO _X densitometer provided downstream of the second stage bag filter is less than the planned value. In addition, the supply amount of the Ca (calcium) -based alkaline agent to the second-stage bag filter is controlled.
Further, in the dry desulfurization method according to the present invention, in one embodiment, a part of the bag filter collecting ash discharged from the lower part of the first stage bag filter is extracted, and the second stage bag filter is It is supposed to be supplied in the exhaust gas upstream.

  In the dry desulfurization method according to the present invention, in one embodiment, at least one selected from waste fuel, alkaline earth metal chloride, and alkali chloride is introduced into an upstream combustion furnace. .

  In the dry desulfurization method according to the present invention, in one embodiment, before the exhaust gas that has passed through the first-stage bag filter is introduced into the second-stage bag filter, The collected ash (collected ash) is input and bypassed from the first-stage bag filter so that exhaust gas is not supplied.

The dry desulfurization apparatus according to the present invention has a high SO _X concentration and contains gas components such as HCl and Cl ₂ (chlorine and / or chlorine compounds), and the abundance ratio Cl / SO _X is expressed as a molar ratio of Cl / SO _X > 0.8 is preferably a dry desulfurization apparatus for dry desulfurization of one or more exhaust gases, wherein the exhaust gas to be introduced is charged with a Ca (calcium) -based alkaline agent to perform the first-stage dry desulfurization. A second-stage bag filter and a second-stage dry desulfurization in which a Ca (calcium) -based alkaline agent is added to the exhaust gas introduced through the first-stage dry desulfurization while supplying Cl. A stage-stage bag filter, and the constitution is such that the charging ratio Cl / SO _X to the second-stage bag filter is adjusted so that the molar ratio Cl / SO _X > 0.5. Features.
In the dry desulfurization apparatus according to the present invention, in one embodiment, the second stage bag filter is bypassed by bypassing the exhaust gas that has passed through the first stage bag filter to the second stage bag filter. It is possible to replenish Cl to the exhaust gas introduced into.

In the dry desulfurization apparatus according to the present invention, in one embodiment, the second stage bag filter may be charged with sodium bicarbonate in addition to the Ca (calcium) alkaline agent.
In the dry desulfurization apparatus according to the present invention, in one embodiment, an SO _X concentration meter and an HCl concentration meter are provided downstream of the first stage bag filter, and detection is performed by the SO _X concentration meter and the HCl concentration meter. Based on the result, the bypass amount of the exhaust gas bypassed to the second-stage bag filter is determined by bypassing the first-stage bag filter.

Further, a dry desulfurization apparatus according to the present invention, in its one embodiment, includes an SO _X concentration meter on the downstream of the bag filter of the second stage, the SO _X concentration detected by the SO _X concentration meter, plan The supply amount of the Ca (calcium) alkaline agent to the second-stage bag filter is controlled so as to be lower than the value.
Further, in the dry desulfurization apparatus according to the present invention, in one embodiment, a part of the bag filter collected ash discharged from the lower part of the first stage bag filter is extracted, and the second stage bag filter is A line for supplying exhaust gas into the exhaust gas is provided upstream.

In the dry desulfurization apparatus according to the present invention, in one embodiment, at least one selected from waste fuel, alkaline earth metal chloride, and alkali metal chloride is introduced into an upstream combustion furnace. Yes.

  In the dry desulfurization apparatus according to the present invention, in one embodiment, before the exhaust gas that has passed through the first-stage bag filter is introduced into the second-stage bag filter, It has a line for charging the collected ash and does not supply exhaust gas by bypass.

According to the present invention, without using an expensive reagent, the dry desulfurization process and apparatus in which the SO _X concentration is high exhaust gas to be able to dry desulfurization is provided.

It is a conceptual diagram which shows 1st Embodiment about the apparatus for implementing the dry-type desulfurization method which concerns on this invention. And desulfurization rate is a graph showing the correlation between the Cl / SO _X in a molar ratio. It is a conceptual diagram which shows 2nd Embodiment about the apparatus for implementing the dry-type desulfurization method which concerns on this invention. It is a conceptual diagram which shows 3rd Embodiment about the apparatus for implementing the dry-type desulfurization method which concerns on this invention. It is a conceptual diagram which shows 4th Embodiment about the apparatus for implementing the dry-type desulfurization method which concerns on this invention. It is a conceptual diagram which shows 5th Embodiment about the apparatus for implementing the dry-type desulfurization method which concerns on this invention. It is a conceptual diagram which shows 6th Embodiment about the apparatus for implementing the dry-type desulfurization method which concerns on this invention. It is a conceptual diagram which shows 7th Embodiment about the apparatus for implementing the dry desulfurization method which concerns on this invention.

Hereinafter, a dry desulfurization method and apparatus according to the present invention will be described with reference to the embodiments shown in the accompanying drawings.
First Embodiment FIG. 1 conceptually shows a first embodiment of an apparatus for carrying out the dry desulfurization method according to the present invention. While explaining the configuration of the apparatus according to the first embodiment, the dry desulfurization method according to the first embodiment will be explained at the same time.
The dry desulfurization apparatus according to the first embodiment includes a first stage bag filter 1 and a second stage bag filter 2.

The exhaust gas is introduced into the first stage bag filter 1 located on the upstream side.
In the present invention, including this embodiment, coal, sewage sludge, industrial wastewater sludge, various industrial wastes, biomass, municipal waste, etc. are discharged from combustion furnaces, incinerators, pyrolysis furnaces, melting furnaces, etc. Exhaust gas to be treated. Further, in the present invention, among such exhaust gases, those having a particularly high SO _X concentration are treated. Regarding the exhaust gas to be treated in the present invention, the range of SO _X concentration is specifically assumed to be 200 to 800 ppm.
Still further, the exhaust gas introduced into the first-stage bag filter 1 has an abundance ratio Cl / SO _X of Cl / SO _X > 0.8 in molar ratio or such an abundance ratio. Are adjusted in advance. The abundance ratio is more preferably a molar ratio of Cl / SO _X > 1.
Moreover, the temperature range of the exhaust gas used as such a process target is 150-240 degreeC, More preferably, it is 160-220 degreeC.

The first-stage bag filter 1 is charged (blown) with a Ca (calcium) alkaline agent from the line 3. This Ca (calcium) alkaline agent is added as a neutralizing agent for neutralizing acidic gas components such as HCl and SO _X. The Ca (calcium) alkaline agent is generally Ca (OH) ₂ (slaked lime).

Furthermore, in general, a reaction aid such as diatomaceous earth is introduced (injected) into the exhaust gas introduced into the first stage bag filter 1 in addition to the neutralizing agent.
The reaction aid is for forming a stable cake layer on the filter cloth surface of the bag filter. This cake layer is removed along with the acid gas component. That is, in the first-stage bag filter 1, a stable cake layer is formed on the filter cloth surface by the reaction aid. On the other hand, the neutralizing agent reacts with HCl and SO _X in the exhaust gas and is taken into this cake layer. The cake layer is separated from the filter cloth at an appropriate timing and collected. As a result, the acidic gas component is removed.

  The exhaust gas that has passed through the first stage bag filter 1 is introduced into the second stage bag filter 2. Similarly, the same neutralizing agent from line 5 and the same reaction aid from line 6 are also introduced into this exhaust gas. In addition, a part of the exhaust gas that bypasses the first stage bag filter 1 is introduced into the exhaust gas from the bypass line 7.

Even in the second-stage bag filter 2, a stable cake layer is formed on the surface of the filter cloth by the reaction aid. On the other hand, the neutralizing agent reacts with HCl and SO _X in the exhaust gas and is taken into this cake layer. The cake layer is separated from the filter cloth at an appropriate timing and collected. As a result, the acidic gas component is removed.

Desulfurization is performed by the above removal procedure.
Here, the exhaust gas introduced into the first-stage bag filter 1 has an abundance ratio Cl / SO _X in a molar ratio of Cl / SO _X > 0.8, more preferably Cl / SO _X > 1. Intended for things. This is because, as described above, the presence of Cl is indispensable for SOx to undergo a solid-gas reaction with the Ca-based alkaline agent in the cake layer of the bag filter. At least the presence of Cl is the following experiment. From the facts, it was found that at least a Cl / SO _X ratio of 0.8 or more is necessary for high-efficiency desulfurization.
In this connection, FIG. 2 shows characteristics conceptually showing the knowledge obtained by the present inventors.
In FIG. 2, the vertical axis represents the desulfurization rate, and the horizontal axis represents the abundance ratio (Cl / SO _X ). As understood from this figure, when the molar ratio is Cl / SO _X > 0.8 and the desulfurization rate is 70 to 80%, and the molar ratio is Cl / SO _X > 1, the desulfurization is performed. The rate reaches 90%. On the other hand, when this molar ratio is 0.5 or less, the desulfurization reaction is rapidly attenuated, and it can be seen that 0.5 is the critical point. Here, the desulfurization rate is a desulfurization rate under the conditions of exhaust gas temperature: 160 ° C., filtration rate: 0.8 m / min, SOx: 100 to 500 ppm, and Ca (OH) ₂ equivalent ratio: 2.5. .
In addition, by setting the abundance ratio to Cl / SO _x > 4, it is possible to expect a flow rate of 95 to 98%. The larger the abundance ratio Cl / SO _X is, the higher the desulfurization rate is expected. However, since a desulfurization rate of 95 to 98% is expected by setting Cl / SO _X > 4, the upper limit of the adoption can be set to Cl / SO _X = 5, for example. Practically, if the exhaust gas introduced into the first-stage bag filter 1 is operated in the range of 0.8 <Cl / SO _X <2.5, stable desulfurization performance can be maintained.
With respect to the facts observed in FIG. 2, it is speculated that Ca reacts with Cl and the CaCl ₂ particles formed promptly promote the reaction between SO _X and Ca by some mechanism. The However, this is because the desulfurization rate in a system in which Cl is not present is less than 10%.

Desulfurization in the first-stage bag filter 1 is performed according to the tendency conceptually shown in FIG.
For example, in the case of exhaust gas in which 1000 ppm of HCl and 500 ppm of SO _X are present, the molar ratio is Cl / SO _X = 2. It is assumed that HCl can be reduced to 20 ppm and SO _x can be reduced to 50 ppm at the outlet of the first-stage bag filter 1. In such exhaust gas at the outlet stage, the molar ratio (Cl / SO _x ) is less than 0.5, and the desulfurization rate is reduced.

Therefore, as described above, a part of the exhaust gas bypassing the first stage bag filter 1 is introduced into the second stage bag filter 2 from the bypass line 7.
If the bypass rate is 10%, the molar ratio Cl / SO _X is 1.2 at the inlet of the second stage bypass filter, Cl / SO _X > 0.5 is satisfied, and the desulfurization rate is maintained within a suitable range. can do. Thus, HCl: 2 ppm or less and SO _x : 10 ppm can be set at the outlet of the second stage Baghfi 2. In this way, the SO _X concentration can be made extremely low.
In general, it is preferable that Cl / SO _X > 0.5 to 2.0 at the inlet of the second-stage bag filter 2.

Second Embodiment FIG. 3 conceptually shows a second embodiment of an apparatus for carrying out the dry desulfurization method according to the present invention.
In the second embodiment, the apparatus configuration is substantially the same as that of the first embodiment. The difference from the first embodiment is that sodium bicarbonate is added to the second stage bag filter in addition to the Ca (calcium) alkaline agent.
This method can be adopted when it is required to perform special depth desulfurization. The ratio of sodium bicarbonate added is in the range of 0.1 to 0.5 (quantity basis) with respect to the total of the Ca (calcium) alkaline agent and sodium bicarbonate.

Third Embodiment FIG. 4 conceptually shows a third embodiment of an apparatus for carrying out the dry desulfurization method according to the present invention.
In the third embodiment, an SO _X concentration meter 8 and an HCl concentration meter 9 are installed downstream of the first-stage bag filter 1 with respect to the apparatus configuration of the first or second embodiment. ing. In the third embodiment, the bypass amount of the exhaust gas from the line 7 is determined based on the detection results of these densitometers 8 and 9 so that the molar ratio Cl / SO _X is maintained within a predetermined range. The control valve 10 is controlled.
By maintaining the molar ratio Cl / SO _X in the exhaust gas introduced into the second stage bag filter 2 in the range of 0.5 to 2.0, a high desulfurization rate can be obtained.

Fourth Embodiment FIG. 5 conceptually shows a fourth embodiment of an apparatus for carrying out the dry desulfurization method according to the present invention.
In the fourth embodiment, a SO _X densitometer 11 is provided downstream of the second stage bag filter 2 with respect to the apparatus configuration of any one of the first to third embodiments. The SO _X concentration meter 8, the HCl concentration meter 9, and the control valve 10 can be provided according to the first to third embodiments, and are omitted in the drawing.
In the fourth embodiment, SO _X concentration meter 11 SO _X concentration detected by the, to be below the planned value by controlling the opening degree of the control valve 12, Ca to bag filter 2 of the second stage ( Control the supply of calcium) alkaline agent.
Thereby, a stable high desulfurization rate can be obtained.

Fifth Embodiment FIG. 6 conceptually shows a fifth embodiment of an apparatus for carrying out the dry desulfurization method according to the present invention.
In the fifth embodiment, with respect to the apparatus configuration of any one of the first to fourth embodiments, a part of the bag filter collected ash discharged from the lower part of the first stage bag filter 1 is extracted, The exhaust gas is supplied into the exhaust gas upstream of the second stage bag filter 2. For this purpose, a supply line 13 is provided. Utilizing CaCl ₂ contained in the collecting ash, thereby, have decided to reduce the amount of Ca (calcium) based alkaline agent.
Note that the SO _X concentration meters 8 and 11, the HCl concentration meter 9, and the control valves 10 and 12 can be provided according to the first to fourth embodiments, and are omitted in the drawing.

Sixth Embodiment FIG. 7 conceptually shows a sixth embodiment of an apparatus for carrying out the dry desulfurization method according to the present invention.
In the sixth embodiment, in the apparatus configuration according to any one of the first to fifth embodiments, an upstream combustion furnace 14 includes an RDF (Refuse Derived Fuel), an alkaline earth metal chloride. , And at least one selected from alkali metal chlorides .
This makes it possible to supplement the concentration of HCl gas.
FIG. 7 representatively shows only those corresponding to the embodiment of FIG.

Seventh Embodiment FIG. 8 conceptually shows a seventh embodiment of an apparatus for carrying out the dry desulfurization method according to the present invention.
In the seventh embodiment, the bypass line 7 provided in the first embodiment is not provided, and only the collected ash supply line 13 is provided. In the seventh embodiment, by utilizing the reaction product CaCl ₂ contained in the collecting ash, charged ratio Cl / SO _X into the second stage of the bag filter is the molar ratio Cl / SO _X Adjust so that> 0.5.
Even in the seventh embodiment, the SO _X concentration meter and the HCl concentration meter are provided downstream of the first stage bag filter, and a control valve is provided to perform the same control as in the third embodiment. Can do. Further, by providing the SO _X densitometer downstream of the second-stage bag filter and providing a control valve, the same control as in the fourth embodiment can be performed.

1 First-stage bag filter 2 Second-stage bag filter 3, 4, 5, 6, 7 Line 8, 11 SO _X concentration meter 9 HCl concentration meter 10, 12 Control valve
13 Collected ash supply line 14 Combustion furnace

Claims (16)

A dry desulfurization method for dry desulfurization of an exhaust gas having an SO _X concentration of 200 to 800 ppm and containing chlorine and / or a chlorine compound as a gas component, wherein the exhaust gas introduced into the first-stage bag filter includes Ca A step of introducing an alkaline agent and performing the first stage of dry desulfurization;
The step of performing the second stage of dry desulfurization through the step of performing the first stage of dry desulfurization, supplying the Ca-based alkaline agent to the exhaust gas introduced into the second stage of the bag filter while supplying Cl. And the step of adjusting the charging ratio Cl / SO _X to the second-stage bag filter so that the molar ratio is Cl / SO _X > 0.5. Dry desulfurization method.   By bypassing a part of the exhaust gas introduced into the first stage bag filter and bypassing the second stage bag filter, the exhaust gas introduced into the second stage bag filter is supplied with Cl. The dry desulfurization method according to claim 1, wherein the dry desulfurization method is performed.   The dry desulfurization method according to claim 1 or 2, wherein sodium bicarbonate is added to the second stage bag filter in addition to the Ca-based alkaline agent. Based on the detection results of the SO _X concentration meter and the HCl concentration meter provided downstream of the first stage bag filter, the first stage bag filter is bypassed and bypassed to the second stage bag filter. The dry desulfurization method according to any one of claims 1 to 3, wherein an exhaust gas bypass amount is determined. Supply amount of Ca-based alkaline agent to the second stage bag filter so that the SO _X concentration detected by the SO _X densitometer provided downstream of the second stage bag filter is lower than the planned value. The dry desulfurization method according to claim 1, wherein the method is controlled.   The bag filter collecting ash discharged from the lower part of the first stage bag filter is extracted and supplied to the exhaust gas upstream of the second stage bag filter. Either dry desulfurization method. The dry desulfurization method according to any one of claims 1 to 6, wherein at least one selected from waste fuel, alkaline earth metal chloride, and alkali metal chloride is charged into an upstream combustion furnace. Exhaust gas having passed through the bag filter of the first stage, before it is introduced into the bag filter of the second stage, the exhaust gas, to put the bag filter collecting ash discharged from the bag filter of the first stage The dry desulfurization method according to claim 1, wherein A dry desulfurization apparatus for dry desulfurization of an exhaust gas having an SO _X concentration of 200 to 800 ppm and containing chlorine and / or a chlorine compound as a gas component, and a Ca (calcium) alkaline agent is contained in the introduced exhaust gas The Ca (calcium) -based alkaline agent is added to the first stage bag filter that is supplied and the first stage dry desulfurization and the exhaust gas introduced through the first stage dry desulfurization while supplying Cl. A second-stage bag filter that performs second-stage dry desulfurization, and the charging ratio Cl / SO _X to the second-stage bag filter is such that the molar ratio Cl / SO _X > 0.5. A dry desulfurization apparatus, characterized by being configured to adjust to   The replenishment of Cl to exhaust gas introduced into the second-stage bag filter by bypassing the first-stage bag filter and bypassing the second-stage bag filter. 9 Dry desulfurization equipment.   The dry desulfurization apparatus according to claim 9 or 10, wherein the second stage bag filter is charged with sodium bicarbonate in addition to a Ca (calcium) alkaline agent. An SO _X concentration meter and an HCl concentration meter are provided downstream of the first stage bag filter, and an exhaust gas bypass amount is determined based on a detection result by the SO _X concentration meter and the HCl concentration meter. The dry desulfurization apparatus in any one of 9-11. A SO _X concentration meter is provided downstream of the second stage bag filter, and Ca (calcium) to the second stage bag filter is set so that the SO _X concentration detected by the SO _X concentration meter is lower than the planned value. The dry desulfurization apparatus according to claim 9, wherein the supply amount of the alkaline agent is controlled.   10. A line for extracting a part of the bag filter collected ash discharged from the lower part of the first stage bag filter and supplying it into the exhaust gas upstream of the second stage bag filter is provided. ~ 13 dry desulfurization equipment. The dry desulfurization apparatus according to any one of claims 9 to 14, wherein at least one selected from waste fuel, alkaline earth metal chloride, and alkali metal chloride is charged into an upstream combustion furnace. The exhaust gas that has passed through the first stage bag filter is provided with a line for collecting collected ash before being introduced into the second stage bag filter, and the exhaust gas is not supplied by bypass. Dry desulfurization equipment.

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