Waste gas treatment device

Abstract

Provided is an exhaust gas treatment device that efficiently separates a water-soluble gas contained in an exhaust gas. This exhaust gas treatment device is provided with: a vapor generation unit 1 that heats an absorption liquid 9 to generate vapor of the absorption liquid; a mixing unit (2) that mixes the vapor generated by the vapor generating unit (1) in the exhaust gas; a cooling unit (3) for cooling the vapor of the absorption liquid so as to absorb and liquefy the water-soluble gas in the exhaust gas; and a separation unit (4) that separates the liquefied absorption liquid (9) from the exhaust gas.

Description

Technical Field

[0001] The present invention relates to a waste gas treatment device, and in particular to a treatment device which is most suitable for separating carbon dioxide, NOx, SOx and other gases from waste gases of power plants, cement plants, blast furnaces and other equipment, or for separating ammonia, ethanol, esters, toluene and other reusable gases from waste gases of various equipment. Background Art

[0002] Devices for removing carbon dioxide from exhaust gas have been developed. (See Patent Documents 1 and 2)

[0003] These patent documents disclose a technique in which an absorbing liquid containing a carbon dioxide gas absorbent is brought into contact with exhaust gas to absorb carbon dioxide gas.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2005-211878

[0007] Patent Document 1: Japanese Patent Application Publication No. 2018-79409 Summary of the invention

[0008] Conventional devices bring waste gas into contact with an absorbent so that carbon dioxide gas and the like contained in the waste gas are absorbed into the absorbent and separated from the waste gas. This method makes it difficult to efficiently absorb carbon dioxide gas contained in the waste gas into the absorbent. In order to improve the absorption efficiency of carbon dioxide gas, it is necessary to increase the contact area between the absorbent and the carbon dioxide gas. In order to achieve this area increase, the following structures are used, namely: spraying the absorbent to form a mist, mixing the mist with the waste gas, thereby increasing the contact area; or a structure in which fine fibers are assembled into a state with gaps to form a mat, the absorbent is spread in the mat, and the waste gas is passed through the gaps in the fibers, thereby increasing the contact area between the waste gas and the absorbent. However, even with the above structure, it is impossible to efficiently absorb carbon dioxide gas and the like contained in the waste gas. Because carbon dioxide gas and the like cannot be separated efficiently, there is a problem that the separation device becomes large, resulting in an increase in separation costs.

[0009] The present invention is developed for the purpose of eliminating the above disadvantages. One of the purposes of the present invention is to provide a waste gas treatment device that can more efficiently separate water-soluble gases contained in waste gas.

[0010] A waste gas treatment device according to a certain embodiment of the present invention comprises: a steam generating section that heats an absorbent to generate vapor of the absorbent; a mixing section that mixes the vapor generated by the steam generating section with the waste gas; a cooling section that cools the vapor of the absorbent and absorbs water-soluble gas in the waste gas to liquefy it; and a separation section that separates the liquefied absorbent from the waste gas.

[0011] The above-mentioned waste gas treatment device has the advantage of being able to efficiently separate and treat water-soluble gases such as carbon dioxide contained in the waste gas. This is because the above-mentioned treatment device uses a steam generating unit to vaporize the absorbent to form a vapor state, uses a mixing unit to supply the vapor of the absorbent to the waste gas, uses a cooling unit to cool and liquefy the vapor of the absorbent in the waste gas, and uses a separation unit to recover the liquid absorbent. When the absorbent is vaporized, 1 mol (18 g in the case of water) of the absorbent is dispersed into 6×10 23 (Avogadro constant) and dispersed in the exhaust gas. The vapor of the absorbent dispersed in the exhaust gas becomes particles that cannot be compared with the mist of the unvaporized absorbent and disperses in the exhaust gas, mixing with the water-soluble gas in the exhaust gas. When the vapor of the absorbent is cooled and liquefied in this state, it absorbs water-soluble gases such as carbon dioxide contained in the exhaust gas during the liquefaction process and liquefies.

[0012] In order to expand the contact area between the liquid absorbent and the exhaust gas, the previous device sprayed the absorbent into the exhaust gas for mixing. However, the average particle size of the sprayed absorbent is significantly larger than the vapor of the vaporized absorbent, and it is difficult for the absorbent to absorb efficiently. Although the particle size of the absorbent can be reduced to increase the contact area with the exhaust gas, the absorbent as a fine mist has the following disadvantages, namely: the device becomes complicated, the equipment cost becomes high, and the energy consumption becomes large, and the operating cost becomes high. The above-mentioned treatment device forms the vapor of the absorbent by vaporizing the absorbent, and the particle size of the vaporized absorbent becomes extremely fine particles at the angstrom level. By further cooling the vapor of the absorbent, countless vapors of the absorbent absorb water-soluble gases and liquefy. Therefore, it is possible to achieve the advantage of recovering the liquefied absorbent and separating water-soluble gases such as carbon dioxide in the exhaust gas extremely efficiently.

[0013] In addition, the above-mentioned treatment device also has the following advantages, namely, it can not only separate carbon dioxide gas, but also separate all water-soluble gases dissolved in the absorption liquid contained in the exhaust gas, and can also select the absorption liquid to efficiently separate specific water-soluble gases from the exhaust gas. For example, the treatment can be performed in the following manner, namely, adjusting the pH of the absorption liquid so that the absorption liquid becomes alkaline water to efficiently separate carbon dioxide gas, etc., or becomes acidic water to efficiently separate water-soluble gases such as NOx, SOx, ammonia, ethanol, ester, toluene, etc. from the exhaust gas.

[0014] In the exhaust gas treatment device according to another aspect of the present invention, the steam generating unit may be capable of generating steam mist including both steam and mist of the absorbing liquid, and the mixing unit may be capable of mixing the steam mist with the exhaust gas.

[0015] In the exhaust gas treatment device according to another aspect of the present invention, the steam generating unit may be capable of generating steam for heating the absorbent.

[0016] In the exhaust gas treatment device according to another aspect of the present invention, the steam generating unit may be capable of generating steam of an absorbing liquid in which a solute chemically bonded with a water-soluble gas is dissolved.

[0017] The exhaust gas treatment device has the advantages of efficiently absorbing and separating water-soluble gas using an absorbing liquid, and can reduce the amount of absorbing liquid used for the absorbed water-soluble gas and efficiently separate the water-soluble gas from the exhaust gas.

[0018] In another aspect of the exhaust gas treatment device of the present invention, the steam generating unit may be capable of generating steam of any one of the absorbents selected from the group consisting of water, seawater, alkaline water, acidic water, calcium hydroxide aqueous solution, and sodium hydroxide aqueous solution.

[0019] The exhaust gas treatment device has the following advantages: as the absorbing liquid, water, seawater, alkaline water, acidic water, water containing calcium hydroxide, etc., in which the gas separated from the exhaust gas easily dissolves, is selected, thereby selecting specific gases and being able to separate them efficiently.

[0020] In the exhaust gas treatment device according to another aspect of the present invention, the steam generation unit may generate the steam of the absorbent by vaporizing the absorbent using exhaust heat from a device that discharges the exhaust gas.

[0021] The exhaust gas treatment device described above vaporizes the absorbent using the exhaust heat of the equipment discharging the exhaust gas to form the vapor of the absorbent. Therefore, the exhaust gas can be treated with reduced running costs by effectively utilizing the exhaust heat of the equipment discharging the exhaust gas to vaporize the absorbent.

[0022] In the exhaust gas treatment device according to another aspect of the present invention, the exhaust gas may be exhaust gas discharged from a power plant, and the steam generating unit may heat the absorbent using exhaust heat from power generation equipment in the power plant.

[0023] The above-mentioned exhaust gas treatment device can effectively use the exhaust heat of the power plant's power generation equipment to vaporize the absorbent. Therefore, it has the following advantages: it can reduce the energy consumed to vaporize the absorbent, thereby reducing operating costs while also being able to efficiently treat the exhaust gas of the power plant.

[0024] In the exhaust gas treatment device according to another aspect of the present invention, the steam generation unit may be capable of heating the absorbent using exhaust heat of a steam turbine for driving a generator in a power plant.

[0025] The steam generating unit of the above-mentioned device heats and vaporizes the absorbent using the exhaust heat of the steam turbine driving the generator, thereby reducing the heat energy used to cool the condenser using seawater. As a result, the device has the following advantages: while suppressing the temperature rise of the seawater caused by the power plant, it is also possible to effectively use the exhaust heat of the steam turbine to efficiently separate carbon dioxide gas and the like from the exhaust gas.

[0026] In the exhaust gas treatment device according to another aspect of the present invention, the exhaust gas may be exhaust gas discharged from a blast furnace, and the steam generating unit may heat and vaporize the absorbent using exhaust heat from the blast furnace.

[0027] The exhaust gas treatment device described above can effectively use the exhaust heat of the blast furnace to generate the vapor of the absorbent, and therefore has the following advantages: it can improve energy efficiency, reduce running costs, and effectively separate the water-soluble gas exhausted from the blast furnace.

[0028] In the exhaust gas treatment device according to another aspect of the present invention, the exhaust gas may be exhaust gas discharged from a cement factory, and the steam generating unit may heat and vaporize the absorbing liquid using exhaust heat from the cement kiln.

[0029] The above-mentioned waste gas treatment device effectively uses the exhaust heat of the kiln in the cement plant to generate the vapor of the absorbent, and therefore has the following advantages: it can improve energy efficiency, reduce running costs and effectively separate water-soluble gases discharged from the cement plant.

[0030] In the exhaust gas treatment device according to another aspect of the present invention, the exhaust gas may be exhaust gas discharged from a chemical plant, and the steam generating unit may heat the absorbent using exhaust heat from the chemical plant to vaporize the absorbent.

[0031] The above-mentioned exhaust gas treatment device can effectively use the exhaust heat of the chemical plant to generate the vapor of the absorbent, thereby improving energy efficiency, reducing running costs and effectively separating the water-soluble gas exhausted from the chemical plant.

[0032] In the exhaust gas treatment device according to another aspect of the present invention, the steam generation unit may heat the absorbent using solar heat or geothermal heat to vaporize the absorbent.

[0033] In the exhaust gas treatment device according to another aspect of the present invention, the cooling unit may cool the steam-containing exhaust gas mixed with the vapor of the absorbent, and cool the vaporized absorbent.

[0034] In the exhaust gas treatment device according to another aspect of the present invention, the temperature of the steam-containing exhaust gas before cooling by the cooling unit can be set to 50° C. or higher.

[0035] The above-mentioned exhaust gas treatment device has the following advantages, namely: it can increase the temperature of the steam-containing exhaust gas that supplies the steam of the absorbent to above 50°C, increase the amount of steam of the absorbent supplied to the exhaust gas, and vaporize a large amount of steam, thereby efficiently separating the water-soluble gas.

[0036] In an exhaust gas treatment device according to another aspect of the present invention, the cooling temperature difference of the cooling unit can be set to 30° C. or more.

[0037] In the exhaust gas treatment device according to another aspect of the present invention, the cooling unit may mix the vapor of the absorbent with the exhaust gas, and the exhaust gas may cool the vapor of the absorbent.

[0038] The above-mentioned exhaust gas treatment device utilizes the exhaust gas to cool the vapor of the absorbent, and therefore has the advantage that the vapor of the absorbent can be cooled with a simple structure.

[0039] The exhaust gas treatment device according to another aspect of the present invention may further include a pre-treatment section for separating condensed water obtained by cooling and liquefying the exhaust gas, and a mixing section for mixing vapor of the absorbent with the exhaust gas from which the condensed water has been separated by the pre-treatment section.

[0040] In the exhaust gas treatment device according to another aspect of the present invention, the pre-treatment section may separate condensed water generated by cooling the exhaust gas, and separate NOx and SOx contained in the exhaust gas.

[0041] In the exhaust gas treatment device according to another embodiment of the present invention, the water-soluble gas may contain any one of carbon dioxide, NOx, SOx, ammonia, ethanol, ester, and toluene. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1This is a block diagram of an exhaust gas treatment device according to one embodiment of the present invention.

[0043] Figure 2 This is a schematic configuration diagram showing an example of a steam generating section, a mixing section, and a cooling section.

[0044] Figure 3 This is a schematic configuration diagram showing an example of a steam generating section and a mixing section.

[0045] Figure 4 This is a schematic configuration diagram showing another example of the steam generating section and the mixing section.

[0046] Figure 5 This is a schematic configuration diagram showing still another example of the steam generating section, the mixing section, and the cooling section.

[0047] Figure 6 This is a schematic configuration diagram showing still another example of the steam generating section, the mixing section, and the cooling section.

[0048] Figure 7 It is a schematic configuration diagram showing another example of the separation unit and the cooling unit.

[0049] Figure 8 This is a schematic configuration diagram showing still another example of the separation unit and the cooling unit. DETAILED DESCRIPTION

[0050] The present invention is described in detail below based on the accompanying drawings. In addition, in the following description, although terms indicating specific directions or positions (such as "upper", "lower", and other terms including these terms) are used as needed, these terms are used to facilitate understanding of the invention with reference to the accompanying drawings, and the technical scope of the present invention is not limited by the meaning of these terms. In addition, the parts with the same symbols shown in multiple drawings represent the same or equivalent parts or components.

[0051] In addition, the embodiments shown below are specific examples of the technical concept of the present invention, and the present invention is not limited to the following embodiments. In addition, the size, material, shape, and relative configuration of the components described below are intended to be illustrative only unless otherwise specified, and the scope of the present invention is not limited to this. In addition, the content described in one embodiment or example can also be applied to other embodiments or examples. In addition, the size and positional relationship of the components shown in the drawings are sometimes exaggerated in order to make the description clear.

[0052] (Implementation Method)

[0053] Figure 1The block diagram of FIG. 1 is a waste gas treatment device 100 for separating water-soluble gas from waste gas. The treatment device 100 in the figure comprises: a steam generating unit 1, which heats the absorbent 9 to generate the vapor of the absorbent; a mixing unit 2, which mixes the vapor generated by the steam generating unit 1 with the waste gas; a cooling unit 3, which cools the vapor of the absorbent to absorb the water-soluble gas in the waste gas and liquefy it; and a separation unit 4, which separates the liquefied absorbent 9 from the waste gas.

[0054] In addition, the processing device can select: vaporize and supply the vapor of the absorbent to the exhaust gas to efficiently separate a specific water-soluble gas. For example, the processing device for separating carbon dioxide gas can mix the vapor of the alkaline absorbent with the exhaust gas and efficiently separate it, and mix the vapor of the acidic absorbent with the exhaust gas to efficiently separate NOx or SOx. Therefore, the mixing section mixes: the vapor of the absorbent with a high solubility of the separated water-soluble gas.

[0055] [Pre-processing unit 5]

[0056] Figure 1 The treatment device 100 includes: a pre-treatment unit 5 for separating condensed water 10 formed by cooling and liquefying the exhaust gas. The treatment device 100 mixes the vapor of the absorbent into the exhaust gas after the condensed water 10 is separated by the pre-treatment unit 5. The pre-treatment unit 5 separates the condensed water 10 from the exhaust gas and separates the water-soluble gas dissolved in the condensed water 10. The condensed water 10 of the exhaust gas becomes acidic water due to the components contained in the combustion gas, so NOx or SOx with high solubility is dissolved in the acidic water. Therefore, the pre-treatment unit 5 can separate the condensed water 10 and separate NOx and SOx from the exhaust gas.

[0057] The pre-treatment unit 5 separates NOx and SOx from the exhaust gas with a simple structure. Regarding the exhaust gas, the fuel contains combustion water in a vapor state, which is at a high temperature and has a relative humidity close to 100%. The combustion water of the exhaust gas is acidic water, and NOx and SOx are dissolved therein. The pre-treatment unit 5 separates the combustion water in which NOx and SOx are dissolved from the exhaust gas. The pre-treatment unit 5 includes: an exhaust gas heat exchanger 11, which cools the exhaust gas and liquefies the combustion water; and a gas-liquid separator 12 such as a cyclone separator, which separates the condensed water 10 cooled and liquefied by the exhaust gas heat exchanger 11 from the exhaust gas. Since the above-mentioned pre-treatment unit 5 can liquefy the combustion water and separate it from the exhaust gas, thereby separating NOx and SOx, it has the advantage of being able to separate NOx and SOx with a simple device without adding the vapor of the absorbent to the exhaust gas. As Figure 1As shown, the exhaust gas heat exchanger 11 may be provided with heat sinks 13 on the outer peripheral surface to utilize the external atmosphere for cooling. Furthermore, cooling air or cooling medium such as the external atmosphere may be circulated in the exhaust gas heat exchanger 11 to cool the exhaust gas.

[0058] The absolute humidity of the exhaust gas after the condensed water 10 is separated by the pre-treatment unit 5 is reduced. The exhaust gas after the absolute humidity is reduced contains less water, and a large amount of absorbent can be mixed in the state of vapor in the subsequent mixing unit 2.

[0059] Figure 1 After the treatment device 100 uses the pre-treatment unit 5 to separate NOx and SOx from the exhaust gas, the carbon dioxide gas is separated by the following steps. However, the exhaust gas treatment device of the present invention does not specifically separate the water-soluble gas from the exhaust gas, and the pre-treatment unit is not necessarily required for separation. This is because: carbon dioxide gas, NOx, SOx, ammonia, ethanol, ester, toluene and other water-soluble gases can also be separated from the exhaust gas by omitting the pre-treatment unit.

[0060] [Steam generating unit 1]

[0061] The steam generating unit 1 can utilize all mechanisms for heating the liquid absorbent 9 to turn it into a vapor state. The steam of the steam generating unit 1 is mixed with the exhaust gas, and the exhaust gas is made into a steam-containing exhaust gas. The absorbent vaporized by the steam generating unit 1 can dissolve specific solutes and increase the solubility of water-soluble gases. The absorbent can select solutes to specify the water-soluble gases separated from the exhaust gas. This is because the absorbent 9 dissolves and separates the separated water-soluble gases. For example, when water is used as the absorbent 9, 15°C water at 1m 3 Medium absorption 1m 3 Therefore, in order to separate 1m 3 Carbon dioxide gas must be added to the exhaust gas 1m 3 of water vapor. Since carbon dioxide gas is easily dissolved in alkaline water, when the solute of the absorption liquid 9 is made alkaline water, and alkaline water is used to make the solubility of carbon dioxide gas 10 times that of water, the amount of absorption liquid 9 added to the exhaust gas is made 1 / 10, and the same amount of carbon dioxide gas can be separated from the exhaust gas. The pH of the absorption liquid 9 of alkaline water and acidic water is set to an optimal value to dissolve a specific water-soluble gas. For example, the pH of alkaline water is set to 8 or more, preferably 8.5 or more, and the pH of acidic water is set to, for example, 6 or less, preferably 5.5 or less.

[0062] Although water or seawater can be used as the absorption liquid 9, in order to improve the solubility of the water-soluble gas, a specific solute is dissolved in the water, and an absorption liquid such as alkaline water, acidic water, calcium hydroxide aqueous solution, sodium hydroxide aqueous solution, etc. is used. For example, by dissolving solutes such as calcium hydroxide or sodium hydroxide in the absorption liquid 9 and making the absorption liquid alkaline water, carbon dioxide gas can be efficiently absorbed. The above-mentioned exhaust gas treatment device 100 has the following advantages, namely: a specific solute is dissolved in the absorption liquid 9, and the gas separated from the exhaust gas is easily dissolved in water, seawater, alkaline water, acidic water, water containing calcium hydroxide, etc., so that a specific gas can be selected and separated efficiently.

[0063] The steam generating section 1 converts the entire absorbent 9 into a vapor state, or into a vapor mist state containing both vapor and mist of the absorbent, or heats the vapor of the absorbent to 100° C. or higher and supplies the heated vapor to the mixing section 2. The steam generating section 1 that generates the vapor mist contains both vapor and mist, and therefore a large amount of the absorbent 9 can be supplied to the exhaust gas.

[0064] Since the steam mist contains not only vaporized steam but also unvaporized mist, the relative humidity exceeds 100%. Since the steam mist absorbs and liquefies the water-soluble gas, and the mist of the absorbent 9 also absorbs and condenses the water-soluble gas, the steam mist can absorb the water-soluble gas by both the steam and the mist. Although the steam of the absorbent can absorb and liquefy the water-soluble gas more efficiently than the mist, the mist can also absorb and condense the water-soluble gas, so the steam mist mixed in the exhaust gas can absorb the water-soluble gas by both the steam and the water.

[0065] The steam-containing waste gas with a relative humidity of 100% or less can be cooled to a temperature lower than the dew point temperature, and the vapor of the supersaturated absorbent can be condensed and liquefied. The relative humidity of the steam-containing waste gas changes depending on the amount (g) of vapor of the absorbent contained and the temperature (°C). The temperature of the steam-containing waste gas is preferably set to 50°C (saturated water vapor amount 83g / m 3 ) or more, and more preferably 60°C (saturated water vapor volume 130 g / m 3 ) or more, and most preferably 70°C (saturated water vapor volume 197g / m 3) or more. The temperature of the steam-containing waste gas can be increased, and the content of the vapor of the absorbent (the saturated water vapor content) can be increased. The steam-containing waste gas containing a large amount of the vapor of the absorbent is cooled in the separation step and becomes supersaturated, thereby increasing the amount of the absorbent that absorbs and liquefies the water-soluble gas. Since the amount of the liquefied absorbent can be increased in the separation step because the water-soluble gas is separated by the liquefaction of the vapor of the absorbent, the water-soluble gas can be effectively separated from the waste gas.

[0066] Since the steam generating unit 1 heats and vaporizes the liquid absorbent 9, it is necessary to heat the absorbent 9 with heat energy greater than the heat of vaporization. Since the heat of vaporization of water used as the absorbent 9 is as high as about 540 cal / g, a large amount of heat energy is required to vaporize the absorbent 9. Figure 1 The steam generating unit 1 utilizes the exhaust heat of the equipment that discharges the exhaust gas as the thermal energy for vaporizing the absorbent 9, thereby reducing the energy cost. Since the amount of absorbent added to the exhaust gas increases in proportion to the exhaust gas discharge amount of the equipment, the thermal energy for vaporizing the absorbent 9 also increases in proportion to the exhaust gas discharge amount, but since the exhaust heat of the equipment also increases in proportion to the exhaust gas discharge amount, even if the exhaust gas increases and the thermal energy required for vaporizing the absorbent 9 increases, it can be heated and liquefied by utilizing the exhaust heat of the equipment.

[0067] Various devices that discharge exhaust gas do not effectively utilize a considerable amount of thermal energy as unused heat, and thus wastefully dissipate heat. The unused heat in various devices is the same, and the temperature distribution of unused heat also varies according to power (power plant), steel (blast furnace), ceramic industry (cement factory, glass factory), etc. When the exhaust heat temperature of power (power plant) is 100-150°C, and the exhaust heat temperature of steel (blast furnace) and ceramic industry (cement factory, glass factory) is 100-200°C, it is in a temperature range suitable for vaporization of the absorbent. Therefore, a device that utilizes the unused heat, i.e., the exhaust heat of these devices to heat and vaporize the absorbent can effectively utilize the equipment to liquefy the absorbent.

[0068] The steam generating unit 1 is as follows Figure 2As shown, the liquid absorbent 9 can be directly supplied to the flow path 18 of the exhaust gas, and the absorbent 9 can be vaporized by using the thermal energy of the exhaust gas. The steam generating unit 1 of this structure can make the absorbent 9 directly contact with the exhaust gas and efficiently vaporize the absorbent 9. Since the steam generating unit 1 can vaporize the absorbent 9 by a simple structure such as spraying or spraying the absorbent 9 from the nozzle 14 into the exhaust gas, the structure can be simplified. In addition, since the thermal energy of the exhaust gas can be effectively used, the consumed energy supplied from the outside can be reduced. That is, supplying the liquid absorbent 9 to the above-mentioned exhaust gas steam generating unit 1 can achieve the following advantages, namely: reducing the energy consumption for vaporizing the absorbent 9 and reducing the running cost, and simplifying the mechanism for vaporizing the absorbent 9 and miniaturizing it, thereby reducing the equipment cost.

[0069] In addition, the steam generating unit 1 for vaporizing the absorbent 9 by utilizing the thermal energy of the exhaust gas may be as follows. Figure 3 As shown, a downward flow path 18 exposed to the exhaust gas is provided, and the absorbent 9 is supplied to the flow path 18, and the absorbent flowing in the flow path is heated and vaporized by the thermal energy of the exhaust gas. Figure 4 As shown, a heater 19 heated by the thermal energy of the exhaust gas is arranged in the exhaust gas flow path 18, and the absorbent 9 is supplied to the heater 19, and the heater 19 is heated by the thermal energy of the exhaust gas to become vapor of the absorbent. Figure 4 The heater 19 is a downslope drain that allows the absorbent 9 supplied to the upper end to flow naturally, and the absorbent 9 flowing in the downslope drain is vaporized into steam by utilizing the thermal energy of the exhaust gas.

[0070] Figure 1Although the steam generating unit 1 uses the exhaust heat of the equipment to heat and vaporize the absorbent 9, the steam generating unit 1 can also use the exhaust heat of the steam turbine 22 of the power plant 20 to vaporize the absorbent 9. The steam generating unit 1 uses the thermal energy of the condenser 23 that cools and liquefies the water vapor described below to heat and vaporize the absorbent 9, and the above-mentioned water vapor is discharged from the steam turbine 22 used to drive the generator 21 of the power plant 20. Since the steam generating unit 1 uses the exhaust heat of the condenser 23 for vaporizing the absorbent 9, the energy cost of vaporizing the absorbent 9 can be reduced. The water vapor discharged from the steam turbine 22 needs to absorb a large amount of thermal energy to be liquefied. The condenser 23 liquefies the water vapor discharged from the steam turbine 22 and circulates it to the boiler 24. The water liquefied by the condenser 23 is heated by the boiler 24 and circulated to the steam turbine 22. Since the temperature of the steam supplied from the steam turbine 22 to the condenser 23 is as high as 100°C or more, the absorbent 9 can be efficiently heated and liquefied by the steam generating unit 1. In addition, since the condensation heat generated by the liquefaction of the steam is large, the absorbent 9 can be efficiently vaporized.

[0071] Since the power plant 20 uses seawater for cooling the condenser 23, the heat dissipated by the condenser 23 causes the seawater temperature to rise. The device that uses the heat energy absorbed by the condenser 23 for vaporizing the absorbent 9 can reduce the amount of heat dissipated by the condenser 23 to the seawater, reduce the rise in seawater temperature, and thus suppress the deterioration of the natural environment.

[0072] Figure 1 The condenser 23 includes a heat exchanger 25 for seawater and a heat exchanger 26 for absorbent. The heat exchanger 25 for seawater circulates seawater to cool and liquefy the steam exhausted from the steam turbine 22, and the heat exchanger 26 for absorbent passes the absorbent 9 to vaporize the absorbent. The condenser 23 uses both the heat exchanger 25 for seawater and the heat exchanger 26 for absorbent to cool and liquefy the steam supplied from the steam turbine 22. Therefore, while adjusting the heat energy used to heat and vaporize the absorbent 9 by the heat exchanger 26 for absorbent and the heat energy absorbed by the heat exchanger 25 for seawater to liquefy the absorbent 9, the steam supplied from the steam turbine 22 is liquefied and circulated to the boiler 24.

[0073] Not limited to power plants, equipment that uses coal, oil, natural gas, etc. as fuel and burns them, such as cement plants and blast furnaces, does not effectively utilize the exhaust heat below 200°C but dissipates it as unused heat. In particular, the exhaust heat in the temperature range of 100 to 200°C is not effectively utilized but is discharged into the atmosphere. Equipment that discharges exhaust gas can effectively utilize the unused heat to heat the absorbent and vaporize it. Figure 5 The steam generating section 1 is provided with a heat exchanger 28, which heats and vaporizes the absorbent 9 using exhaust heat from the device 30. The heat exchanger 28 heats and vaporizes the absorbent 9 pumped by the pump 29, and supplies the vaporized absorbent vapor to the mixing section 2. The steam generating section 1 has the following advantages: the heat energy for liquefying the absorbent 9 to generate vapor can be greatly reduced, thereby reducing the running cost.

[0074] The steam generating unit 1 is as follows Figure 1 As shown in FIG. 1 , in a power plant 20, the exhaust heat of the steam turbine 22 can be used to efficiently vaporize the absorbent 9. However, even in a blast furnace, cement plant, chemical plant, etc., it is also possible to Figure 5 As shown, the exhaust heat of the device 30 is used to heat and vaporize the absorbent 9. The steam generating unit of the cement plant can use the exhaust heat of the cement kiln to heat the absorbent. Figure 6 As shown, the absorption liquid 9 can be heated and vaporized by utilizing the heat energy of solar heat or geothermal heat.

[0075] [Mixing section 2]

[0076] The mixing section 2 may be any mechanism that mixes the vapor of the absorbent supplied from the vapor generating section 1 to form a steam-containing exhaust gas. The mixing section 2 may be a mechanism that is only intended to mix the exhaust gas and the vapor of the absorbent, or may be a part of the steam generating section. Although the present invention does not specify the structure of the mixing section 2, the mixing section 2 may be, for example, a static mixer or a mixer that stirs the exhaust gas using the vapor of the absorbent sprayed.

[0077] The mixing section 2 may also be Figure 2 as well as Figure 5 As shown, it is composed of a part of the steam generating unit 1. Figure 2 The steam generating unit 1 injects the liquid absorbent 9 from the nozzle 14 into the exhaust gas at a temperature of 100°C or higher, vaporizes the injected liquid absorbent 9 by utilizing the thermal energy of the exhaust gas, and supplies the absorbent vapor to the exhaust gas. Since the steam generating unit 1 injects the liquid absorbent 9 into the exhaust gas and disperses the absorbent vapor in the exhaust gas, the mixing unit 2 is provided as an integral structure. Figure 5The steam generating section 1 pressurizes the liquid absorbent 9 and sprays it from the nozzle 14 into the exhaust gas in a liquid state of more than 100°C. Although the liquid boils and vaporizes at 1 atmosphere and 100°C, since the boiling point of the pressurized liquid is more than 100°C, for example, when the absorbent 9 is pressurized to about 4.7 atmospheres, it becomes a liquid at 150°C, and further pressurized to about 10 atmospheres, it becomes a liquid at 180°C. For example, when the liquid absorbent 9 pressurized and heated to 150-180°C is sprayed from the nozzle 14 into the exhaust gas, the pressure decreases and evaporates, and is dispersed in the exhaust gas. Since the steam generating section 1 also disperses the vapor of the absorbent in the exhaust gas, the mixing section 2 is provided as an integral structure. Figure 2 and Figure 5 The steam generating section 1 of the embodiment of the present invention comprises the mixing section 2 as an integral structure, but as Figure 1 As shown, a dedicated mixing section 2 may also be provided to mix the exhaust gas and the vapor of the absorption liquid more evenly. Figure 3 and Figure 4 Since the steam generating section 1 supplies the absorbent 9 to the exhaust gas and vaporizes it, the steam generating section 1 and the mixing section 2 can be integrally structured.

[0078] [Cooling section 3]

[0079] The cooling unit 3 may use any structure that cools and liquefies the vapor of the absorbent in the exhaust gas. The cooling unit 3 cools the steam-containing exhaust gas in which the vapor of the absorbent is mixed, and condenses the vapor of the absorbent. The cooling unit 3 may use any mechanism that cools the steam-containing exhaust gas and liquefies the vapor of the absorbent. The cooling unit 3 may be an integrated structure with the mixing unit 2. Figure 6 The cooling section 3 and the mixing section 2 are integrally structured, and utilize the exhaust gas below 100° C. to cool the steam-containing exhaust gas to liquefy the vapor of the absorbent. Figure 6 Although the mixing section heats and vaporizes the waste gas of the liquid heated to above 100°C, the vapor of the absorbent is cooled and liquefied by utilizing the waste gas below 100°C. Therefore, no dedicated cooling section is provided, and the discharge side of the mixing section 2 is used as the cooling section 3 to liquefy the vapor of the absorbent. The absorbent added to the waste gas can cool the waste gas by utilizing the heat of vaporization of its own vaporization. Therefore, the treatment device that supplies steam mist to the waste gas can cool the waste gas by utilizing the heat of vaporization of the mist contained in the steam mist, and can cool and liquefy the vapor of the absorbent by utilizing the cooled waste gas. Therefore, Figure 2 Although the processing device is provided with a dedicated cooling section 3, the processing device may not be provided with a dedicated cooling section 3, so that the cooling section and the mixing section are integrated into one structure, and the vapor of the supplied absorption liquid is liquefied.

[0080] Although the vapor of the absorbent is cooled and condensed by the cooling unit 3, it absorbs the water-soluble gas efficiently in this step. This is because the extremely fine vapor of the absorbent condenses and liquefies. Since 1 mol (18 g) of water in the absorbent 9 is vaporized, 6×10 23 The vapor of the absorption liquid of the microparticles will condense and liquefy, so that the water-soluble gas can be efficiently absorbed in the process of condensing and liquefying a large amount of vapor. The absorption liquid 9 that is condensed and becomes liquid is dispersed in the exhaust gas in the form of mist, or condenses and adheres to the cooling surface. The cooling unit 3 cools the steam-containing exhaust gas to below the dew point temperature to liquefy the vapor of the supersaturated absorption liquid. The saturated water vapor amount of the steam-containing exhaust gas will change according to the temperature. When the temperature of the steam-containing exhaust gas decreases, the saturated water vapor amount will decrease. Therefore, the lower the temperature to which the cooling unit 3 cools the steam-containing exhaust gas, the greater the vaporization amount of the absorption liquid vapor.

[0081] The amount of water that can be contained in the steam-containing exhaust gas in the gas state, that is, the saturated water vapor content, changes with the temperature as a parameter. When the temperature of the steam-containing exhaust gas decreases, its saturated water vapor content decreases. Since the saturated water vapor content decreases when the steam-containing exhaust gas is cooled, the supersaturated water vapor will liquefy. The saturated water vapor content of the steam-containing exhaust gas decreases to 292g / m at 80°C. 3 , reduced to 30g / m at 30℃ 3 , reduced to 17g / m at 20℃ 3 , reduced to 13g / m at 15℃ 3 Therefore, the exhaust gas containing steam at 80°C (relative humidity 100%) is cooled by the cooling unit 3 for 1m 3 When cooled to 20℃, 175g (292-17g / m 3 ) is liquefied. Since the vapor of the absorbing liquid is liquefied and the water-soluble gas is separated from the exhaust gas, the liquefied amount of the absorbing liquid 9 can be increased, thereby enabling the water-soluble gas to be separated efficiently.

[0082] Since the temperature difference before and after the steam-containing exhaust gas is increased, the amount of liquefied absorbent 9 can be increased. Therefore, the temperature difference before and after the steam-containing exhaust gas cooled by the cooling unit 3 is, for example, 30°C or more, preferably 35°C or more, and more preferably 40°C or more. Since the cooling temperature of the steam-containing exhaust gas can be set relatively low in the cooling unit 3 to increase the temperature difference of the cooling, the temperature of the steam-containing exhaust gas after cooling is, for example, 30°C (saturated water vapor amount 30 g / m 3 ) or less, preferably 20°C (saturated water vapor volume 17g / m 3 ) or less, more preferably 15°C (saturated water vapor volume 13g / m 3 )the following.

[0083] Steam-containing exhaust gas with a relative humidity of less than 100% can be cooled to a temperature lower than the dew point temperature to liquefy the vapor of the supersaturated absorbent. 3 It contains 234g of water vapor, so when it is cooled to 30℃ and the saturated water vapor amount is reduced to 30g, the vapor of 234-30g of the absorption liquid will liquefy. Therefore, the cooling unit 3 can cool the steam-containing exhaust gas whose relative humidity is not 100% to a temperature lower than the dew point temperature, and liquefy the vapor of the absorption liquid. Even if the cooling unit 3 cools the steam-containing exhaust gas with a relative humidity of 80% and 80℃ to 75℃, the vapor of the absorption liquid will not liquefy. This is because: the saturated water vapor amount of the steam-containing exhaust gas at 75℃ is 240g, which is greater than the saturated water vapor amount of the steam-containing exhaust gas at 80℃ and 80%, and the vapor of the absorption liquid cannot be supersaturated. Therefore, the cooling unit 3 cools the steam-containing exhaust gas with a relative humidity less than 100% to a temperature lower than the dew point temperature, and liquefies the vapor of the absorption liquid.

[0084] [Separation section 4]

[0085] The separation unit 4 can utilize: all mechanisms for recovering the absorbent 9 liquefied by the cooling unit 3 from the exhaust gas. The separation unit 4 recovers the liquefied absorbent 9 from the exhaust gas. The separation unit 4 separates the liquefied absorbent 9 from the exhaust gas and separates the water-soluble gas from the exhaust gas. Since the absorbent 9 is obtained by dissolving and liquefying the water-soluble gas, the liquefied absorbent 9 is recovered to separate the carbonic acid gas, NOx, SOx, ammonia, and other water-soluble gases contained in the exhaust gas.

[0086] The liquefied absorbent 9 is dispersed in the exhaust gas as fine water droplets, that is, in the form of mist, or condensed on a cooling surface for cooling the steam-containing exhaust gas. The mist of the absorbent 9 dispersed in the exhaust gas can be separated from the exhaust gas and recovered by a gas-liquid separation device 15 such as a cyclone separator. The cyclone separator of the gas-liquid separation device 15 can recover the mist of the absorbent 9 from the exhaust gas with a simple structure.

[0087] The separation section 4 may cause the vapor of the absorbent to condense on the cooling surface and recover the absorbent 9 . Figure 7 and Figure 8 The separation unit 4 and the cooling unit 3 are integrally structured, and a collector 16 is provided in the exhaust gas duct 15 for discharging the absorbent 9 liquefied by the cooling unit 3 to the outside. Figure 7 The exhaust gas pipe 15A is arranged to be downwardly inclined in the opposite direction to the conveying direction of the exhaust gas. Figure 8The pipe 15B is arranged in a vertical posture, so that the condensed absorbent 9 flows down and is discharged from the collector 16. The separation unit 4 can collect the absorbent 9 cooled in the pipe 15 and condensed on the inner surface by flowing down and discharging it from the collector 16. Figure 7 and Figure 8 The pipes 15A and 15B are provided with heat sinks 17 on the outer side surface, and cooling is performed by using the heat sinks 17. The pipes 15 cooled by using the heat sinks 17 can be cooled by using the outside atmosphere at normal temperature with a simple structure. Although the pipes are not shown in the figure, a cooling plate protruding from the inner surface toward the inside of the pipe can also be provided, and the surface of the cooling plate is used as a cooling surface. The pipe can enlarge the surface area in contact with the exhaust gas by providing a cooling plate on the inner surface, so that the vapor of the absorbent can be condensed more efficiently. In addition, the pipe can also set the heat exchanger tube that circulates the cooling fluid in a thermally coupled state, and forced cooling is performed by using the cooling fluid circulating in the heat exchanger tube. Since the above-mentioned separation section 4 and the cooling section 3 are an integrated structure, the steam-containing exhaust gas can be cooled by using a simple structure, and the cooled and liquefied absorbent 9 can be recovered.

[0088] Although Figure 1 The block diagram of exemplifies an apparatus for recovering carbonic acid gas which is a water-soluble gas from the exhaust gas of the power plant 20, but the present invention does not specify the exhaust gas treatment apparatus as an apparatus used in a power plant.

[0089] The waste gas discharged from various equipment is mainly the waste gas generated by burning fuels such as coal, oil, natural gas, and wood. Although the waste gas contains carbon dioxide, NOx, SOx, etc. Figure 1 The separation device 100 of the block diagram can separate carbon dioxide, NOx, SOx, etc. The separation device of the present invention can separate water-soluble gas not only from the combustion gas generated by combustion, but also from all waste gases containing water-soluble gas in the carrier gas. For example, waste gas of air containing ammonia can be separated from ammonia and recycled to reuse ammonia.

[0090] [Industrial Applicability]

[0091] The exhaust gas treatment device of the present invention can be used as a device for efficiently separating water-soluble gases such as carbon dioxide gas from exhaust gas.

[0092] [Description of Reference Numerals]

[0093] 1: Steam generating unit

[0094] 2: Mixing section

[0095] 3: Cooling section

[0096] 4: Separation

[0097] 5: Pre-processing unit

[0098] 6: Gas-liquid separation device

[0099] 9: Absorption liquid

[0100] 10: Condensation

[0101] 11: Exhaust gas heat exchanger

[0102] 12: Gas-liquid separator

[0103] 13,17: Heat sink

[0104] 14: Nozzle

[0105] 15,15A,15B: Pipeline

[0106] 16: Trap

[0107] 18: Flow path

[0108] 19: Heater

[0109] 20: Power Plant

[0110] 21: Generator

[0111] 22: Steam Turbine

[0112] 23: Condenser

[0113] 24: Boiler

[0114] 25,26,28: Heat exchanger

[0115] 29: Pump

[0116] 30: Equipment

[0117] 100: Processing device / separation device

Claims

1. An exhaust gas treatment device, characterized in that: The exhaust gas treatment device comprises: a steam generating unit for heating the absorbent to generate steam of the absorbent; a mixing unit that mixes the steam generated by the steam generating unit with the exhaust gas; a cooling unit for cooling the vapor of the absorption liquid so as to absorb and liquefy the water-soluble gas in the exhaust gas; and A separation section separates the liquefied absorption liquid from the exhaust gas.

2. The exhaust gas treatment device according to claim 1, characterized in that: The steam generating unit generates: a steam mist including both steam and mist of the absorbing liquid; The mixing unit mixes the steam mist with the exhaust gas.

3. The exhaust gas treatment device according to claim 1, characterized in that: The steam generating unit generates steam for heating the absorbent.

4. The exhaust gas treatment device according to claim 1, characterized in that: The vapor generating unit generates vapor of an absorbing liquid in which a solute chemically bonded with a water-soluble gas is dissolved.

5. The exhaust gas treatment device according to claim 1, characterized in that: The steam generating unit generates steam of any one of the absorbents, including water, seawater, alkaline water, acidic water, calcium hydroxide aqueous solution, and sodium hydroxide aqueous solution.

6. The exhaust gas treatment device according to claim 1, characterized in that: The steam generating unit vaporizes the absorbent using exhaust heat from a device that discharges the exhaust gas to generate vapor of the absorbent.

7. The exhaust gas treatment device according to claim 6, characterized in that: The exhaust gas is exhaust gas discharged from a power plant, The steam generation unit heats the absorbent using exhaust heat from power generation equipment in a power plant.

8. The exhaust gas treatment device according to claim 7, characterized in that: The steam generating unit heats the absorbent using exhaust heat of a steam turbine that drives a generator in the power plant.

9. The exhaust gas treatment device according to claim 6, characterized in that: The waste gas is waste gas discharged from a blast furnace, The steam generating unit heats and vaporizes the absorbent using exhaust heat from the blast furnace.

10. The exhaust gas treatment device according to claim 6, characterized in that: The waste gas is waste gas discharged from a cement factory, The steam generating unit utilizes exhaust heat from the cement kiln to heat and vaporize the absorbent.

11. The exhaust gas treatment device according to claim 6, characterized in that: The waste gas is waste gas discharged from a chemical plant, The steam generation unit heats and vaporizes the absorbent using exhaust heat from the chemical plant.

12. The exhaust gas treatment device according to claim 1, characterized in that: The steam generating unit heats and vaporizes the absorbent using solar heat or geothermal heat.

13. The exhaust gas treatment device according to claim 1, characterized in that: The cooling unit cools the steam-containing exhaust gas mixed with the steam of the absorbent and cools the vaporized absorbent.

14. The exhaust gas treatment device according to claim 13, characterized in that: The temperature of the steam-containing exhaust gas before cooling by the cooling unit is 50° C. or higher.

15. The exhaust gas treatment device according to claim 14, characterized in that: The cooling temperature difference of the cooling part is 30° C. or more.

16. The exhaust gas treatment device according to claim 1, characterized in that: The cooling unit mixes the vapor of the absorbent with the exhaust gas, and the exhaust gas cools the vapor of the absorbent.

17. The exhaust gas treatment device according to claim 1, characterized in that: A pre-treatment unit is provided, the pre-treatment unit separates condensed water obtained by cooling and liquefying the exhaust gas, The mixing section mixes the vapor of the absorbing liquid with the exhaust gas after the condensed water is separated by the pre-treatment section.

18. The exhaust gas treatment device according to claim 17, characterized in that: The pre-treatment section separates condensed water generated by cooling the exhaust gas, and separates NOx and SOx contained in the exhaust gas.

19. The exhaust gas treatment device according to claim 1, characterized in that: The water-soluble gas includes any one of carbon dioxide, NOx, SOx, ammonia, ethanol, ester and toluene.

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