JP2023017514A - Exhaust gas treatment facility and exhaust gas treatment method - Google Patents

Abstract

To provide an exhaust gas treatment facility which can remove an acidic gas component in an exhaust gas without causing drainage and decrease the temperature of the exhaust gas, and thus can efficiently separate and collect carbon dioxide in the exhaust gas.SOLUTION: An exhaust gas treatment facility 30A for treating an exhaust gas generated by combustion comprises: an acidic gas removal device 31 to remove an acidic gas component contained in the exhaust gas by dry treatment; a temperature decrease device 33 to decrease the temperature, by non-wet treatment, of the exhaust gas from which the acidic gas is removed by the acidic gas removal device 31; and a CO2 separation and collection device 35 to separate and collect carbon dioxide from the exhaust gas whose temperature is decreased by the temperature decrease device 33.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to an exhaust gas treatment facility and an exhaust gas treatment method for treating exhaust gas generated by combustion.

For example, when separating and recovering carbon dioxide in coal-fired power plants, waste incineration facilities, biomass power plants, etc., the acid gas components (HCl, SOx, etc.) contained in the flue gas generated by combustion are must be removed until The acidic gas components in the exhaust gas may impair the absorption performance and absorption operation of carbon dioxide, so they need to be removed before separation and recovery of carbon dioxide. When separating and recovering carbon dioxide contained in the exhaust gas, it is necessary to reduce the temperature of the exhaust gas so that the carbon dioxide is easily absorbed or adsorbed.

A wet method is known as a means for removing acid gases in exhaust gas and for reducing the temperature of the exhaust gas (see, for example, Patent Document 1).

In the wet method disclosed in Patent Document 1, exhaust gas from which dust has been removed by a dust collector is introduced into an exhaust gas scrubber (wet scrubber), and the exhaust gas is scrubbed with washing water sprayed and circulated in this exhaust gas scrubber, Acid gas components are absorbed in a large amount of wash water, and an alkaline agent such as caustic soda is added to neutralize the wash water that has absorbed the acid gas components, thereby removing the acid gas components from the exhaust gas and reducing the temperature of the exhaust gas. It is to do.

JP-A-2003-88726

In the wet method as described above, the acid gas and the cleaning water come into contact with each other in the exhaust gas scrubbing apparatus, so it is necessary to use a corrosion-resistant material as a constituent material of the apparatus, resulting in an expensive apparatus. In addition, a large amount of washing water will be used, and moreover, the washing water contains neutralized salts generated by the reaction between the acidic gas components in the exhaust gas and caustic soda, etc. If a closed wastewater system cannot be used, it will be discharged. After diluting to a possible state, it will be discharged into sewage or rivers. Therefore, a waste liquid treatment facility is required separately, and the installation cost and running cost of the waste liquid treatment facility increase. Even if it is possible to have a closed drainage system, for example, cleaning water containing neutralized salt will be blown into the combustion furnace or the exhaust gas desuperheating tower. Combustion efficiency is lowered, and as a result, power generation efficiency is lowered in facilities where a power generation device is installed in a combustion furnace.

The present invention has been made in view of the above problems, and is capable of removing acidic gas components in exhaust gas without generating waste liquid, and reducing the temperature of exhaust gas, thereby It is an object of the present invention to provide an exhaust gas treatment facility and an exhaust gas treatment method capable of efficiently separating and recovering carbon dioxide.

The characteristic configuration of the exhaust gas treatment equipment according to the present invention for solving the above problems is as follows:
An exhaust gas treatment facility for treating exhaust gas generated by combustion,
an acid gas removal device for removing acid gas components contained in exhaust gas by dry treatment;
a temperature reduction device for reducing the temperature of the exhaust gas from which the acid gas has been removed by the acid gas removal device by non-wet treatment;
a CO ₂ separation and recovery device for separating and recovering carbon dioxide from the exhaust gas whose temperature has been reduced by the temperature reducing device;
It is to prepare

According to the exhaust gas treatment equipment of this configuration, the acidic gas component contained in the exhaust gas is removed by dry treatment by the acidic gas removal device, and the exhaust gas from which the acid gas has been removed is reduced in temperature by non-wet treatment by the temperature reducing device. be. Here, both the removal of acid gas components by dry treatment and the temperature reduction by non-wet treatment are treatments that do not use liquids such as water, so there is no waste liquid, and a conventional wet scrubber was adopted. There is no need for a waste liquid treatment facility that is required in some cases. Therefore, it can be applied to the treatment of exhaust gas in, for example, biomass power generation facilities, which may be located in mountains where it is difficult to discharge the waste liquid. In addition, according to the exhaust gas treatment equipment of this configuration, the acidic gas components that inhibit the absorption of carbon dioxide are removed from the exhaust gas, and the temperature of the exhaust gas is reduced so that the carbon dioxide is easily absorbed or adsorbed. Carbon dioxide in the exhaust gas can be efficiently separated and recovered by the CO ₂ separation and recovery device.

In the exhaust gas treatment equipment according to the present invention,
It is preferable that the acid gas removal device is configured to remove dust and/or harmful substances contained in the exhaust gas in addition to the acid gas components by dry treatment.

According to the exhaust gas treatment equipment of this configuration, in addition to the acid gas component, dust that may impede the absorption performance and absorption operation of carbon dioxide and / or the absorbed carbon dioxide can be an obstacle in utilizing it. can remove potentially hazardous substances.

In the exhaust gas treatment equipment according to the present invention,
The temperature reducing device is
a heat exchanger that indirectly transfers the heat of exhaust gas from which acid gas components have been removed by the acid gas removal device to a heat medium to recover the heat;
air adding means for adding air to the exhaust gas whose heat has been recovered by the heat exchanger;
is preferably provided.

According to the exhaust gas treatment equipment of this configuration, the heat of the exhaust gas is indirectly transferred to the heat medium and recovered in the heat exchanger, thereby reducing the temperature of the exhaust gas. Air is added to the reduced temperature exhaust gas by the air addition means to further reduce the temperature. In this way, the temperature of the exhaust gas can be reliably reduced by the non-wet treatment that does not use a liquid such as water.

In the exhaust gas treatment equipment according to the present invention,
The heat exchanger reduces the temperature of the exhaust gas in a temperature range where moisture in the exhaust gas does not condense,
The air adding means is preferably configured to add air to the exhaust gas whose temperature has been reduced by the heat exchanger to reduce the temperature while preventing condensation.

According to the exhaust gas treatment equipment of this configuration, the heat exchanger reduces the temperature of the exhaust gas in a temperature range in which the moisture in the exhaust gas does not condense. Air is added to the reduced temperature exhaust gas by the air addition means. This makes it possible to further reduce the temperature of the exhaust gas while preventing condensation. In this way, carbon dioxide can be more easily absorbed or adsorbed, and the carbon dioxide recovery efficiency can be improved.

In the exhaust gas treatment equipment according to the present invention,
It is preferable to further include a reheater for heating the exhaust gas to which air has been added by the air adding means.

According to the exhaust gas treatment equipment of this configuration, the exhaust gas to which air has been added by the air addition means is heated by the reheater, so that condensation of moisture in the exhaust gas can be reliably prevented.

Next, the characteristic configuration of the exhaust gas treatment method according to the present invention for solving the above problems is as follows:
An exhaust gas treatment method for treating exhaust gas generated by combustion,
an acid gas removal step of removing acid gas components contained in exhaust gas by dry treatment;
a temperature reduction step of reducing the temperature of the exhaust gas from which the acid gas component has been removed by the acid gas removal step by non-wet treatment;
a CO ₂ separation and recovery step of separating and recovering carbon dioxide from the exhaust gas whose temperature has been reduced by the temperature reduction step;
to include

According to the exhaust gas treatment method of this configuration, the acidic gas component contained in the exhaust gas is removed by the dry treatment in the acidic gas removing step, and the exhaust gas from which the acidic gas has been removed is reduced in temperature by a non-wet treatment in the temperature reducing step. be. Here, both the removal of acid gas components by dry treatment and the temperature reduction by non-wet treatment are treatments that do not use liquids such as water, so there is no waste liquid, and a conventional wet scrubber was adopted. There is no need for a waste liquid treatment facility that is required in some cases. Therefore, it can be applied to the treatment of exhaust gas in, for example, biomass power generation facilities, which may be located in mountains where it is difficult to discharge the waste liquid. In addition, according to the exhaust gas treatment method of this configuration, the acidic gas component that inhibits the absorption of carbon dioxide is removed from the exhaust gas, and the temperature of the exhaust gas is reduced so that the carbon dioxide is easily absorbed or adsorbed. Carbon dioxide in exhaust gas can be efficiently separated and recovered by the CO ₂ separation and recovery process.

In the exhaust gas treatment method according to the present invention,
In the acid gas removal step, it is preferable to remove dust and/or harmful substances contained in the exhaust gas in addition to the acid gas components by dry treatment.

According to the exhaust gas treatment method of this configuration, in addition to the acid gas component, dust that may impede the absorption performance and absorption operation of carbon dioxide and / or absorbed carbon dioxide can be an obstacle to utilization. can remove potentially hazardous substances.

In the exhaust gas treatment method according to the present invention,
The temperature reduction step is
a heat recovery step of indirectly transferring the heat of the exhaust gas from which the acid gas component has been removed by the acid gas removal step to a heat medium to recover the heat;
an air addition step of adding air to the exhaust gas from which heat has been recovered in the heat recovery step;
is preferably included.

According to the exhaust gas treatment method of this configuration, in the heat recovery step, the heat of the exhaust gas is indirectly transferred to the heat medium and recovered, thereby reducing the temperature of the exhaust gas. In the air addition step, air is added to the reduced temperature exhaust gas to further reduce the temperature. In this way, the temperature of the exhaust gas can be reliably reduced by the non-wet treatment that does not use a liquid such as water.

In the exhaust gas treatment method according to the present invention,
In the heat recovery step, the temperature of the exhaust gas is reduced in a temperature range in which moisture in the exhaust gas does not condense,
In the air addition step, it is preferable to reduce the temperature while preventing condensation by adding air to the reduced temperature exhaust gas.

According to the exhaust gas treatment method of this configuration, in the heat recovery step, the temperature of the exhaust gas is reduced in a temperature range in which moisture in the exhaust gas does not condense. In the air addition step, air is added to the reduced temperature exhaust gas. This makes it possible to further reduce the temperature of the exhaust gas while preventing condensation. In this way, carbon dioxide can be more easily absorbed or adsorbed, and the carbon dioxide recovery efficiency can be improved.

In the exhaust gas treatment method according to the present invention,
It is preferable to further include a reheating step of heating the exhaust gas to which air has been added in the air adding step.

According to the exhaust gas treatment method of this configuration, since the exhaust gas to which air has been added in the air addition step is heated in the reheating step, condensation of moisture in the exhaust gas can be reliably prevented.

FIG. 1 is a block diagram showing a schematic configuration of a biomass power generation facility equipped with exhaust gas treatment equipment according to the first embodiment of the present invention. FIG. 2 is a block diagram showing a schematic configuration of a biomass power generation facility equipped with exhaust gas treatment equipment according to a second embodiment of the present invention. FIG. 3 is a diagram showing another embodiment of the acid gas removal device.

The present invention will be described below with reference to the drawings. In the following embodiments, an exhaust gas treatment facility in a biomass power generation facility will be described as an example. However, the present invention is not intended to be limited to the embodiments described below or the configurations described in the drawings. The biomass fuel to be burned in the biomass power generation facility is bio-derived fuel extracted from natural organic resources such as plants and agricultural products other than fossil fuels. Specifically, as biomass fuels, for example, waste wood, thinned wood, branches and leaves, bark, driftwood, grasses, household waste, sludge, livestock manure, energy crops (agricultural crop by-products), and recycled fuels made from these raw materials (pellets and chips) and the like.

[First embodiment]
<Overall composition>
FIG. 1 is a block diagram showing a schematic configuration of a biomass power generation facility 1A equipped with an exhaust gas treatment facility 30A according to the first embodiment of the present invention. A biomass power generation facility 1A shown in FIG. 1 includes a biomass power generation facility 10 and an exhaust gas treatment facility 30A.

<Biomass power generation equipment>
The biomass power generation facility 10 includes a combustion furnace 11 for burning biomass fuel, a steam generator 13 arranged in order from the upstream side to the downstream side along the flow path of exhaust gas generated by combustion in the combustion furnace 11, and an economizer. 15, an air preheater 17, and a power generating device 19 that uses the steam generated by the steam generator 13 to generate power.

[Combustion Furnace]
As the combustion furnace 11, the type of furnace is not limited as long as it can burn biomass fuel, but examples thereof include a stoker type combustion furnace and a fluidized bed type combustion furnace.

A stoker-type combustion furnace is a combustion furnace in which a stoker arranged in the furnace is moved, combustion air is sent from the bottom of the stoker, and biomass fuel is dried, burned, and post-burned. Here, the stoker includes, for example, a stepped stoker and a traveling stoker. A stepped stoker is a structure in which movable grates and fixed grates are alternately arranged in a stepped manner, and includes a drying stoker forming a drying stage, a combustion stoker forming a combustion stage, and a post combustion stage forming a post-combustion stage. Combustion stokers are divided in order from the upstream side toward the downstream side in the biomass fuel feeding direction. On the other hand, a traveling stoker is an annular fire in which a plurality of fire grates are rotatably and annularly connected to a driving wheel and a driven wheel which are arranged at a predetermined interval in the direction in which the biomass fuel is moved in the furnace. It is constructed by winding a grid body around it. In the traveling stoker, the ring-shaped grate body is driven to revolve, and the biomass fuel received by the ring-shaped grate body from the fuel injector is moved and burned on the ring-shaped grate body. . A fluidized bed combustion furnace is a combustion furnace that burns biomass fuel while dispersing and supplying pressurized air from the lower part of a particle layer of silica sand, etc., to fluidize the silica sand, etc. that has accumulated heat. be.

[Steam generator]
The steam generator 13 has a casing into which the exhaust gas discharged from the combustion furnace 11 is introduced, and a large number of heat transfer tubes for heat exchange. It is configured to generate steam by heat exchange with the exhaust gas flowing outside the heat tube. The generated steam is introduced into the power generator 19 and used for power generation.

[Coal saver]
The economizer 15 has a casing into which the exhaust gas discharged from the steam generator 13 is introduced, and a large number of heat transfer tubes for heat exchange are arranged in the casing. The water supplied to the steam generator 13 is heated by heat exchange between the water supplied to the steam generator 13 and the exhaust gas flowing outside the heat transfer tubes.

[Air preheater]
The air preheater 17 has a casing into which exhaust gas discharged from the economizer 15 is introduced, and a large number of heat transfer tubes for heat exchange. The air from the pit is heated by heat exchange between the air from the pit and the exhaust gas flowing outside the heat transfer tube, and the heated air from the refuse pit is supplied as primary combustion air to the combustion furnace 11. is configured as

<Exhaust gas treatment equipment>
The exhaust gas treatment facility 30A includes an acid gas removal device 31 that removes acid gas components contained in the exhaust gas by a dry process, and a temperature reduction device that reduces the temperature of the exhaust gas from which the acid gas has been removed by the acid gas removal device 31 by a non-wet process. 33, a reheater 34 that heats the exhaust gas whose temperature has been reduced by the temperature reducing device 33 as necessary, and carbon dioxide from the exhaust gas that has been heated as necessary by the reheater 34 after the temperature has been reduced by the temperature reducing device 33. and a CO ₂ separation and recovery device 35 for separating and recovering the CO 2 . Here, with respect to the acid gas removal device 31, the "dry process" is a process that does not use a liquid such as water, and is a reaction between the acid gas component in the exhaust gas and the neutralizing agent supplied in the exhaust gas. The product (or the adsorbent that adsorbs the acid gas components) is treated to be discharged in a dry state, the acid gas components in the exhaust gas are decomposed by a catalyst, and the activated carbon packed in the packed tower (adsorption tower) It refers to removing the acidic gas components in the exhaust gas by adsorbing them to an adsorbent such as activated coke or activated coke. On the other hand, with respect to the temperature reducing device 33, the “non-wet treatment” means that a liquid such as water may be used as a heat medium in the heat exchanger 60, which will be described later. This refers to processing to prevent the generation of waste liquid containing dissolved components of the exhaust gas.

<Acid gas removal device>
The acid gas removal device 31 is mainly composed of a dust collector 41 and a neutralizing agent supply device 43, and can remove not only acid gas components in the exhaust gas but also dust contained in the exhaust gas by dry processing. can.

[Dust collector]
The dust collecting device 41 is configured by incorporating a required filter cloth in a casing and equipping a dusting device, although a detailed description thereof is omitted. The interior of the casing is vertically partitioned by a cage plate, and in the interior of the casing, a pre-filtration exhaust gas chamber is formed below the cage plate, and a post-filtration exhaust gas chamber is formed above the cage plate. ing. The pre-filtration exhaust gas chamber is connected to the air preheater 17 via a duct 51 . The filtered exhaust gas chamber is connected through a duct 53 to a heat exchanger 60 which will be described later. The cage plate is provided with a required number of openings for suspending the filter cloth, and from each opening, the filter cloth is suspended and supported so as to be arranged in the pre-filtration exhaust gas chamber. The filter cloth is a cylindrical bag, and one closed end (lower end) is inserted into the pre-filtration exhaust gas chamber, while the other open end (upper end) is inserted into the post-filtration exhaust gas chamber. The filter cloth is arranged so as to face each other, and an aggregate is incorporated in the inside of the filter cloth to maintain its cylindrical shape. When the differential pressure between the upstream side and the downstream side of the exhaust gas flow path in the dust collector 41 reaches a predetermined value or more, or at regular intervals regardless of the value of the differential pressure, the blow-off device removes the air from the air compressor. Compressed air is sprayed from the required spray nozzles through piping to the inner surface of the filter cloth to be wiped off (backwashed) to remove dust adhering to the outer surface of the filter cloth. etc. can be blown away. The dust collector 41 is not limited to a device called a bag filter using a filter cloth as described above. For example, a cyclone (multi-cyclone) type dust collector using centrifugal force, A louver type classifier that classifies particles by utilizing the difference in inertial force acting on particles may be employed, or these may be used in combination with a bag filter.

A duct 51 connecting the dust collector 41 and the air preheater 17 has an upstream vertical duct portion 51a extending vertically on the upstream side.

<Neutralizing agent supply device>
The neutralizing agent supply device 43 includes a chemical tank 45 and a feeder 47. The neutralizing agent (for example, JIS special slaked lime, highly reactive slaked lime, baking soda chemical, etc.) stored in the chemical tank 45 is supplied to the feeder 47. By supplying the neutralizing agent to the upstream vertical duct portion 51a by means of It is configured.

In the acidic gas removing device 31, the neutralizing agent is supplied from the neutralizing agent supplying device 43 to the upstream vertical duct portion 51a, thereby causing the acidic gas contained in the exhaust gas to react with the neutralizing agent, thereby generating a reaction. The substance (neutralized salt) can be collected together with the dust in the dust collector 41 to remove the acid gas component to an acceptable concentration.

<Temperature reduction device>
The temperature reducing device 33 is mainly composed of a heat exchanger 60 and air adding means 70 .

<Heat exchanger>
In the heat exchanger 60, for example, a heat medium such as air or water is caused to flow inside a heat transfer tube made of a material with excellent heat conductivity such as metal, and the exhaust gas is brought into contact with the outside of the heat transfer tube. It is a device that collects heat by indirectly transmitting it to the heat medium through heat transfer tubes.

<Air addition means>
The air addition means 70 adds air to the exhaust gas flowing inside the duct 55 connecting the heat exchanger 60 and the reheater 34, and mainly includes a blower 71, an air supply pipe 73, a flow rate adjustment damper 75, and a damper control unit 77 . The blower 71 and the duct 55 are connected by an air supply pipe 73 . A flow control damper 75 is interposed in the air supply pipe 73 . The damper control section 77 transmits a predetermined control signal to the flow rate adjustment damper 75 . As a result, the amount of air supplied from the blower 71 to the exhaust gas flowing through the duct 55 via the air supply pipe 73 is controlled.

<Reheater>
The reheater 34 is configured to indirectly heat the exhaust gas to which the air has been added by the air addition means 70 using a heat medium.

< _CO2 separation and recovery equipment>
Examples of the CO ₂ separation and recovery device 35 include devices using a chemical absorption method, a membrane separation method, a physical absorption method, a solid absorption method, and the like. The CO ₂ separation and recovery device 35 based on the chemical absorption method uses, for example, an amine absorbent, and separates only CO ₂ by chemically bonding CO ₂ molecules in the exhaust gas with amine in the amine absorbent. configured to retrieve. The CO ₂ separation and recovery device 35 based on the membrane separation method uses a solid thin film having a separation function, and is configured to separate and recover CO ₂ from the exhaust gas by utilizing its permeation selectivity. The CO ₂ separation and recovery device 35 based on the physical absorption method is configured to separate and recover CO ₂ in exhaust gas by dissolving it in liquid. The CO ₂ separation and recovery device 35 using a solid absorption method uses zeolite, activated carbon, or the like as an adsorbent for physical adsorption, or uses an inorganic porous material supporting alkali metals or amines as an adsorbent for chemical adsorption. It is configured to separate and recover CO ₂ by adsorbing it on an adsorbent.

In the biomass power generation facility 1A configured as described above, exhaust gas generated by combustion of biomass fuel in the combustion furnace 11 is sequentially introduced into the steam generator 13, the economizer 15, and the air preheater 17. . The steam generator 13 generates high-pressure steam through heat exchange with the exhaust gas, the economizer 15 heats the water supplied to the steam generator 13 using residual heat of the exhaust gas, and the air preheater 17 Air from a waste pit (not shown), which is provided as primary combustion air for the combustion furnace 11, is heated using residual heat of exhaust gas. High-pressure steam generated by the steam generator 13 is introduced into the power generator 19 . In the power generator 19, the steam turbine is rotated at high speed by the high-pressure steam, and power is generated by a generator connected to the steam turbine.

According to the exhaust gas treatment equipment 30A of the present embodiment, the acid gas components contained in the exhaust gas are removed by the dry treatment by the acid gas removal device 31, and the exhaust gas from which the acid gas has been removed is subjected to non-wet treatment by the temperature reduction device 33. The temperature is reduced by Here, both the removal of acid gas components by dry treatment and the temperature reduction by non-wet treatment are treatments that do not use liquids such as water, so there is no waste liquid, and a conventional wet scrubber was adopted. There is no need for a waste liquid treatment facility that is required in some cases. Therefore, it can be applied to the use of exhaust gas treatment in the biomass power generation facility 1A, which may be located in mountains where it is difficult to discharge the waste liquid. In addition, according to the exhaust gas treatment facility 30A of the present embodiment, the acid gas component that inhibits the absorption of carbon dioxide is removed from the exhaust gas, and the temperature of the exhaust gas is reduced so that carbon dioxide is easily absorbed or adsorbed. Therefore, the carbon dioxide in the exhaust gas can be efficiently separated and recovered by the CO ₂ separation and recovery device 35 .

Next, the exhaust gas treatment method of the present invention will be described. The exhaust gas treatment method of the present invention is carried out, for example, in a biomass power generation facility 1A equipped with the exhaust gas treatment equipment 30A of the present embodiment described above, and includes an acid gas removal step, a temperature reduction step, and a reheating step. , and a CO ₂ separation and recovery step.

<Acid gas removal step>
The exhaust gas discharged from the air preheater 17 has a temperature of about 160° C., for example, and contains 10 to 20% carbon dioxide, 15 to 20% moisture, and acid gas components. Exhaust gas discharged from the air preheater 17 is introduced into the dust collector 41 via the duct 51 . The neutralizing agent supplied by the feeder 47 of the neutralizing agent supply device 43 is fed into the upstream vertical duct portion 51a of the duct 51 by gravity flow. The neutralizing agent sent into the upstream vertical duct portion 51a is mixed with the exhaust gas and supplied to the upstream side of the dust collector 41 along with the exhaust gas. A reaction product (neutralized salt) produced by the reaction between the acid gas contained in the exhaust gas and the neutralizing agent is collected by the dust collector 41 together with dust. In this way, the acidic gas component, which is a hindrance to the carbon dioxide separation and recovery step in the CO ₂ separation and recovery device 35 in the subsequent stage, is removed to an allowable concentration.

<Temperature reduction process (heat recovery process)>
The exhaust gas from which the dust and acid gas components have been removed in the dust collector 41 is introduced into the heat exchanger 60, and in the heat exchanger 60, heat exchange with a heat medium such as water or air flowing through the heat transfer tubes causes The temperature is reduced in a temperature range where the moisture inside does not condense, for example, the temperature is reduced to about 70 to 80°C.

<Temperature reduction process (air addition process)>
Air is added by the air adding means 70 to the exhaust gas, which has been cooled to about 70 to 80° C. in the heat exchanger, in order to reduce the temperature while preventing condensation by diluting moisture in the exhaust gas. At this time, the damper control unit 77 controls the temperature of the exhaust gas after addition of air to be about 50° C. so that the moisture content is lower than the saturated moisture content of 12% at a temperature of 50° C., for example, about 7.5 to 10%. , a predetermined control signal is sent to the flow control damper 75 to control the supply amount of the air added to the exhaust gas flowing inside the duct 55, for example, so that the ratio of the exhaust gas and the added air is 1:1. do. The "saturated water content" is the volume fraction of the saturated water vapor content in the exhaust gas.

<Reheating process>
Then, if necessary, a reheating step is performed in which the reheater 34 heats the exhaust gas to which air has been added in the air adding step. As a result, it is possible to more reliably prevent condensation of moisture in the exhaust gas.

<CO ₂ separation and recovery process>
As described above, after air is added and reheated as necessary, the exhaust gas contains about 5.0 to 7.5% CO ₂ , and the reheater 34 and the CO ₂ separation and recovery device 35 is introduced into the CO ₂ separation and capture device 35 via a duct 58 connecting the . In the CO ₂ separation and recovery device 35, carbon dioxide contained in the exhaust gas is separated and recovered by, for example, a chemical absorption method, a membrane separation method, a physical absorption method, a solid absorption method, or the like.

According to the exhaust gas treatment method of the present embodiment, the acidic gas component contained in the exhaust gas is removed by dry treatment by the acidic gas removal device 31, and the exhaust gas from which the acid gas has been removed is subjected to non-wet treatment by the temperature reducing device 33. The temperature is reduced. Here, both the removal of acid gas components by dry treatment and the temperature reduction by non-wet treatment are treatments that do not use liquids such as water, so there is no waste liquid, and a conventional wet scrubber was adopted. There is no need for a waste liquid treatment facility that is required in some cases. Therefore, it can be applied to the use of exhaust gas treatment in the biomass power generation facility 1A, which may be located in mountains where it is difficult to discharge the waste liquid. In addition, according to the exhaust gas treatment method of the present embodiment, the acid gas component that inhibits the absorption of carbon dioxide is removed from the exhaust gas, and the temperature of the exhaust gas is reduced so that the carbon dioxide is easily absorbed or adsorbed. , the carbon dioxide in the exhaust gas can be efficiently separated and recovered by the CO ₂ separation and recovery process.

In the temperature reducing device 33, the heat of the exhaust gas is indirectly transferred to the heat medium and recovered in the heat exchanger 60, thereby reducing the temperature of the exhaust gas. Air is added by the air addition means 70 to the reduced temperature exhaust gas to further reduce the temperature. In this way, the temperature of the exhaust gas can be reliably reduced by the non-wet treatment that does not use a liquid such as water.

In the heat exchanger 60, the temperature of the exhaust gas is reduced in a temperature range where moisture in the exhaust gas does not condense. Air is added to the reduced temperature exhaust gas by the air adding means 70 . This makes it possible to further reduce the temperature of the exhaust gas while preventing condensation. In this way, carbon dioxide can be more easily absorbed or adsorbed, and the carbon dioxide recovery efficiency can be improved.

[Second embodiment]
FIG. 2 is a block diagram showing a schematic configuration of a biomass power generation facility 1B equipped with an exhaust gas treatment facility 30B according to the second embodiment of the present invention. In the second embodiment, the same or similar parts as those in the first embodiment are denoted by the same reference numerals in the drawings, and detailed description thereof will be omitted. I will explain mainly.

The biomass power generation facility 1A according to the first embodiment shown in FIG. 1 is configured so that the entire amount of exhaust gas from the combustion furnace 11 is treated by the exhaust gas treatment facility 30A to separate and recover carbon dioxide. On the other hand, in the biomass power generation facility 1B according to the second embodiment shown in FIG. 2, part of the exhaust gas from the combustion furnace 11 is extracted and treated by the exhaust gas treatment equipment 30B to separate and recover carbon dioxide. ing. The exhaust gas treatment equipment 30A in the first embodiment processes the entire amount of exhaust gas from the combustion furnace 11, whereas the exhaust gas treatment equipment 30B in the second embodiment processes part of the exhaust gas from the combustion furnace 11. Although there is a difference that both are basically the same configuration.

In the biomass power generation facility 1B of FIG. A cylinder 23 is provided. Air preheater 17 and dust collector 21 are connected by duct 25 , and dust collector 21 and exhaust stack 23 are connected by duct 27 . Exhaust gas after being subjected to heat exchange in the air preheater 17 is introduced into the dust collector 21 via the duct 25, and the exhaust gas after being dust-removed by the dust collector 21 is passed through the duct 27 and the exhaust pipe 23. is discharged out of the system via In the biomass power generation facility 1B, a duct 51 is connected so as to branch off from the duct 27, and part of the exhaust gas that has been dust-removed by the dust collector 21 is drawn out through the duct 51 and supplied to the exhaust gas treatment facility 30B. configured to be introduced into

As described above, the exhaust gas treatment facility and the exhaust gas treatment method of the present invention have been described based on a plurality of embodiments, but the present invention is not limited to the configurations described in the above embodiments and is within the scope of the invention , the configuration can be changed as appropriate.

(Another embodiment 1)
FIG. 3(a) is an explanatory view of an acidic gas removing device 31A according to another embodiment 1. FIG. The acidic gas removal device 31A shown in FIG. 83, and a dust collector 41 disposed on the downstream side. The adsorbent supply device 83 has an adsorbent (for example, dioxin, heavy metals, etc.) that adsorbs harmful substances ( for example, activated carbon). The adsorbent supply device 83 includes an adsorbent tank 85 and a feeder 87, and supplies the adsorbent stored in the adsorbent tank 85 to the upstream vertical duct portion 51a by the feeder 87, thereby supplying the adsorbent. It is configured so that the adsorbent can be supplied to the upstream side of the dust collector 41 by sending it into the upstream vertical duct portion 51a under natural flow. The acid gas removal device 31A can remove dust and harmful substances contained in the exhaust gas in addition to acid gas components by dry treatment.

(Another embodiment 2)
FIG. 3(b) is an explanatory view of an acidic gas removing device 31B according to another embodiment 2. FIG. The acid gas removing device 31B shown in FIG. 3(b) includes a neutralizing agent supply device 43, a dust collector 41, and an adsorption tower 91 interposed in a duct 53. As shown in FIG. The adsorption tower 91 is filled with an adsorbent (for example, activated carbon) that adsorbs harmful substances. In the acidic gas removal device 31B, the adsorption tower 91 is arranged downstream of the dust collector 41 in order to maintain the adsorption performance of the adsorption tower 91 for as long as possible, and the dust is removed in the dust collector 41. It is configured to introduce the exhaust gas after being desorbed into the adsorption tower 91 . The acid gas removal device 31B can remove dust and harmful substances contained in the exhaust gas in addition to acid gas components by dry treatment.

(Another embodiment 3)
FIG. 3(c) is an explanatory diagram of an acidic gas removing device 31C according to another embodiment 3. As shown in FIG. The acidic gas removing device 31C shown in FIG. The adsorption tower 93 is filled with an adsorbent (for example, activated carbon) that adsorbs acidic gas components and harmful substances. The acid gas removal device 31C can remove harmful substances by dry treatment in addition to acid gas components.

As an aspect of the acid gas removal device of the present invention, for example, like the acid gas removal device 31 in the first embodiment and the second embodiment, an acid gas component removal function by dry processing and a dust removal function by dry processing and the acidic gas component removal function by dry processing, the dust removal function by dry processing, and the hazardous substance removal function by dry processing, like the acid gas removal devices 31A and 31B in the other embodiments 1 and 2. and an aspect having an acid gas component removal function by dry processing and a harmful substance removal function by dry processing like the acid gas removal device 31C in another embodiment 3.

The exhaust gas treatment equipment and exhaust gas treatment method of the present invention are, for example, in thermal power plants, steel plants, oil refineries, etc., carbon dioxide contained in exhaust gas generated by burning fossil fuels, hydrogen production facilities, combustion of offgas Carbon dioxide contained in exhaust gas generated by waste combustion facilities, carbon dioxide contained in exhaust gas generated by combustion of waste at general waste incineration facilities, carbon dioxide contained in exhaust gas generated by combustion of biomass fuel at biomass power generation facilities, etc. It can be used for the purpose of separating and recovering

1A, 1B biomass power generation facility 10 biomass power generation facility 30A, 30B exhaust gas treatment facility 31 acid gas removal device 33 temperature reduction device 34 reheater 35 CO ₂ separation and recovery device 60 heat exchanger 70 air addition means

Claims (10)

An exhaust gas treatment facility for treating exhaust gas generated by combustion,
an acid gas removal device for removing acid gas components contained in exhaust gas by dry treatment;
a temperature reduction device for reducing the temperature of the exhaust gas from which the acid gas has been removed by the acid gas removal device by non-wet treatment;
a CO ₂ separation and recovery device for separating and recovering carbon dioxide from the exhaust gas whose temperature has been reduced by the temperature reducing device;
Exhaust gas treatment equipment. 2. The exhaust gas treatment facility according to claim 1, wherein the acid gas removal device is configured to remove dust and/or harmful substances contained in the exhaust gas in addition to the acid gas components by dry treatment. The temperature reducing device is
a heat exchanger that indirectly transfers the heat of exhaust gas from which acid gas components have been removed by the acid gas removal device to a heat medium to recover the heat;
air adding means for adding air to the exhaust gas whose heat has been recovered by the heat exchanger;
The exhaust gas treatment facility according to claim 1 or 2, comprising: The heat exchanger reduces the temperature of the exhaust gas in a temperature range where moisture in the exhaust gas does not condense,
4. The exhaust gas treatment facility according to claim 3, wherein the air addition means is configured to add air to the exhaust gas whose temperature has been reduced by the heat exchanger to reduce the temperature while preventing condensation. 5. The exhaust gas treatment facility according to claim 3, further comprising a reheater for heating the exhaust gas to which air has been added by said air adding means. An exhaust gas treatment method for treating exhaust gas generated by combustion,
an acid gas removal step of removing acid gas components contained in exhaust gas by dry treatment;
a temperature reduction step of reducing the temperature of the exhaust gas from which the acid gas component has been removed by the acid gas removal step by non-wet treatment;
a CO ₂ separation and recovery step of separating and recovering carbon dioxide from the exhaust gas whose temperature has been reduced by the temperature reduction step;
An exhaust gas treatment method comprising: 7. The exhaust gas treatment method according to claim 6, wherein in the acidic gas removing step, dust and/or harmful substances contained in the exhaust gas are removed by dry treatment in addition to the acidic gas components. The temperature reduction step is
a heat recovery step of indirectly transferring the heat of the exhaust gas from which the acid gas component has been removed by the acid gas removal step to a heat medium to recover the heat;
an air addition step of adding air to the exhaust gas from which heat has been recovered in the heat recovery step;
The exhaust gas treatment method according to claim 6 or 7, comprising: In the heat recovery step, the temperature of the exhaust gas is reduced in a temperature range in which moisture in the exhaust gas does not condense,
9. The exhaust gas treatment method according to claim 8, wherein in said air addition step, air is added to the exhaust gas whose temperature has been reduced to prevent condensation while reducing the temperature. 10. The exhaust gas treatment facility according to claim 8 or 9, further comprising a reheating step of heating the exhaust gas to which air has been added by said air adding step.

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