Exhaust gas purification method

Abstract

To provide an exhaust gas purification method that facilitates the extension of the lifespan of a CO2 absorption solution and enables the economical removal of harmful substances contained in exhaust gases (such as nitrogen dioxide, nitric oxide, sulfur oxides, carbon dioxide, mercury, dioxins, volatile organic compounds).SOLUTION: An exhaust gas purification method comprises: allowing an exhaust gas containing at least one substance selected from the group consisting of ash dust, hydrogen chloride, a nitrogen oxide, a sulfur oxide, mercury, a volatile organic compound and a carbon oxide to pass through a catalyst bag filter having at least one function selected from the group consisting of a denitration function, an NO oxidation function, an Hg0 oxidation function, a desulfurization function and an adsorption function; bringing the exhaust gas that has passed through the catalyst bag filter into direct contact with a cooling solution to decrease the temperature of the exhaust gas; and subsequently bringing the exhaust gas that has been directly contacted with the cooling solution into direct contact with a CO2 absorption solution to reduce carbon dioxide in the exhaust gas.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention is a method for treating harmful substances contained in exhaust gases, such as nitrogen oxides (NO x ), sulfur oxides (SO x ), carbon oxides (COx), hydrogen chloride (HCl), mercury (Hg 0 The present invention relates to an exhaust gas purification method and an exhaust gas purification device capable of removing contaminants such as heavy metals (e.g., volatile organic compounds (VOCs), dioxins (DXNs), and soot and dust. [Background technology]

[0002] Gases discharged from thermal power plants, waste incinerators, cement kilns, aluminum melting furnaces, boilers, etc. contain harmful substances such as nitrogen oxides, sulfur oxides, carbon dioxide, hydrogen chloride, heavy metals, dioxins, and volatile organic compounds. It is said that if the concentrations of such harmful substances in the atmosphere increase, it will have a negative impact on the global environment. Therefore, various devices have been proposed to remove harmful substances from exhaust gases, such as denitration devices, dust collection devices, desulfurization devices, demineralization devices, and CO2 removal devices.

[0003] Known denitrification devices include devices that use the ammonia catalytic reduction method. Known desulfurization devices include devices that use the wet limestone gypsum method, devices that use the alkaline solution absorption method or lime slurry absorption method, devices that use the spray dry method, and devices that use the activated carbon adsorption method. Known CO2 removal devices include devices that use the absorption of carbon dioxide by a liquid containing an amine compound such as alkanolamine (hereinafter sometimes referred to as a CO2 absorbing liquid) (CO2 absorption device).

[0004] Even after passing through a denitration device or a desulfurization device, exhaust gas contains several ppm to tens of ppm of nitrogen dioxide and several ppm to hundreds of ppm of sulfur dioxide, and also contains trace amounts of nitrogen monoxide, sulfur trioxide, mercury, dust, and volatile organic compounds. If such exhaust gas is sent directly to a CO2 absorption device for CO2 removal treatment, the amine compounds contained in the CO2 absorbing solution will be altered by nitrogen dioxide, sulfur trioxide, mercury, soot, etc., and the CO2 absorption performance of the CO2 absorbing solution will decrease. In order to solve such problems, NO x It has been proposed to install CO2 absorption pretreatment devices such as scrubbers, desalination and desulfurization agent spray devices, and wet electrostatic precipitators to remove substances that alter amine compounds from the exhaust gas immediately before it is supplied to the CO2 absorption device (Patent Document 1, Patent Document 2, Patent Document 3, Patent Document 4, and Patent Document 5). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] WO2013 / 78211A1 [Patent Document 2] JP 2005-40683 A [Patent Document 3] WO2012 / 14831A1 [Patent Document 4] JP 2015-85310 A [Patent Document 5] WO2011 / 152550A1 [Patent Document 6] Japanese Patent Application Publication No. 8-332349 [Patent Document 7] Japanese Patent Application Publication No. 8-196830 [Patent Document 8] JP 2002-18241 A [Patent Document 9] JP 2006-7055 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, the above-mentioned conventional CO2 absorption pretreatment equipment has high equipment and operating costs, and is prone to damage by substances that alter the amine compounds (especially Hg 0 In many cases, removal of pollutants (e.g., VOCs) is insufficient. The object of the present invention is to provide an exhaust gas purification method and exhaust gas purification device that can extend the life of a CO2 absorption solution and efficiently remove harmful substances contained in exhaust gas (nitrogen dioxide, nitric oxide, sulfur oxides, carbon dioxide, mercury, dioxins, volatile organic compounds, etc.) at low cost. [Means for solving the problem]

[0007] As a result of investigations conducted in order to achieve the above object, the present invention, which includes the following aspects, has been completed. [1] A device for treating exhaust gas containing at least one selected from the group consisting of soot, hydrogen chloride, nitrogen oxides, sulfur oxides, mercury, volatile organic compounds, and carbon oxides, the device having a denitrification function, a NO oxidation function, a Hg oxidation function, 0 Passing the mixture through a catalytic bag filter having at least one function selected from the group consisting of an oxidation function, a desulfurization function, and an adsorption function; The exhaust gas that passes through the catalytic bag filter is cooled to lower the temperature of the exhaust gas, The method for purifying exhaust gas includes directly contacting the cooled exhaust gas with a CO2 absorbing liquid to reduce carbon dioxide in the exhaust gas.

[0008] [2] The method for purifying exhaust gas according to [1], wherein the exhaust gas is cooled by direct contact with a cooling liquid, and the cooling liquid is plain water, seawater or an alkaline aqueous solution.

[0009] [3] The method for purifying exhaust gas according to [1] or [2], further comprising subjecting the exhaust gas to at least one treatment selected from the group consisting of denitrification treatment, dust collection treatment, desulfurization treatment, and desalination treatment before passing the exhaust gas through the catalytic bag filter.

[0010] [4] The method for purifying exhaust gas according to any one of [1] to [3], wherein the CO2 absorbing liquid is an aqueous solution containing an amine compound.

[0011] [5] The method for purifying an exhaust gas according to any one of [1] to [4], wherein the temperature of the exhaust gas immediately before passing through the catalytic bag filter is 80 to 250°C.

[0012] [6] The method for purifying an exhaust gas according to any one of [1] to [5], wherein the temperature of the exhaust gas immediately before being brought into direct contact with the CO2 absorbing liquid is 20 to 80°C.

[0013] [7] Denitration function, NO oxidation function, Hg 0 a catalytic bag filter having at least one function selected from the group consisting of an oxidation function, a desulfurization function, and an adsorption function; a gas cooling device configured to cool the gas to reduce the temperature of the gas; and A CO2 absorbing device configured to reduce carbon dioxide in the gas by direct contact between the gas and a CO2 absorbing solution, An exhaust gas purification device configured to allow exhaust gas containing at least one selected from the group consisting of soot, hydrogen chloride, nitrogen oxides, sulfur oxides, mercury, volatile organic compounds, and carbon oxides to pass through a catalytic bag filter, a gas cooling device, and a CO2 absorption device in that order.

[0014] [8] The exhaust gas purification device according to [7], further comprising a demineralizer configured to reduce hydrogen chloride in the gas, and configured so that exhaust gas containing at least one selected from the group consisting of soot, hydrogen chloride, nitrogen oxides, sulfur oxides, mercury, volatile organic compounds, and carbon oxides can pass through the demineralizer, catalytic bag filter, gas cooler, and CO2 absorber in that order.

[0015] [9] A denitration device configured to reduce nitrogen oxides in a gas; A dust collector configured to reduce soot in the gas; and The present invention further includes a desulfurization device configured to reduce sulfur oxides in the gas, The exhaust gas purification device according to [7], which is configured so that exhaust gas containing at least one selected from the group consisting of soot, hydrogen chloride, nitrogen oxides, sulfur oxides, mercury, volatile organic compounds, and carbon oxides can pass through a denitration device, a dust collector, a desulfurization device, a catalytic bag filter, a gas cooling device, and a CO2 absorption device in that order.

[0016]

[10] The method further includes a desalination device configured to reduce hydrogen chloride in the gas; The exhaust gas purification device according to [9], which is configured so that exhaust gas containing at least one selected from the group consisting of soot, hydrogen chloride, nitrogen oxides, sulfur oxides, mercury, volatile organic compounds, and carbon oxides can pass through a denitrification device, a dust collector, a desulfurization device, a demineralization device, a catalytic bag filter, a gas cooling device, and a CO2 absorption device in that order. Effect of the Invention

[0017] The method for purifying exhaust gas according to the present invention can efficiently remove harmful substances such as nitrogen dioxide, nitrogen monoxide, sulfur oxides, carbon dioxide, mercury, dioxins, and volatile organic compounds from exhaust gas. According to the method for purifying exhaust gas according to the present invention, substances that alter the CO2 absorbing liquid are efficiently removed before direct contact with the CO2 absorbing liquid, so that deterioration of the performance of the CO2 absorbing liquid is suppressed and the life of the CO2 absorbing liquid can be extended. The exhaust gas purification device according to the present invention is optimal for carrying out the method for purifying exhaust gas according to the present invention. The equipment costs and operating costs of the device related to the catalytic bag filter are approximately 100%. x It is less expensive than conventional CO2 absorption pre-treatment devices such as scrubbers, desalination and desulfurization agent sprayers, and wet electrostatic precipitators. [Brief description of the drawings]

[0018] [Figure 1] 1 is a diagram showing an example of an apparatus configuration suitable for carrying out the exhaust gas purification method of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an example of an embodiment of the method and apparatus of the present invention will be described, however, the present invention is not limited to these embodiments.

[0020] The method for purifying exhaust gas of the present invention includes passing the exhaust gas through a catalytic bag filter, cooling the exhaust gas that has passed through the catalytic bag filter, and then directly contacting the exhaust gas with a CO2 absorbing liquid to reduce carbon dioxide in the exhaust gas. The method for purifying exhaust gas of the present invention can further include, as necessary, subjecting the exhaust gas to at least one treatment from the group consisting of a denitrification treatment, a dust collection treatment, a desulfurization treatment, and a desalination treatment before passing the exhaust gas through the catalytic bag filter.

[0021] The exhaust gas purification apparatus of the present invention includes a catalytic bag filter 1, a gas cooling device 2, and a CO2 absorption device 3. The exhaust gas purification apparatus of the present invention may further include a denitrification device 6, a dust collection device 7, a desulfurization device 8, or a demineralization device 9, as necessary. The exhaust gas purification apparatus of the present invention may further include a CO2 recovery device 4, as necessary.

[0022] The exhaust gas to which the method or apparatus of the present invention can be applied contains at least one selected from the group consisting of dust, hydrogen chloride, nitrogen oxides, sulfur oxides, mercury, volatile organic compounds, and carbon oxides. In addition, the exhaust gas may contain harmful substances such as dioxins, phosphorus oxides, and arsenic. Alternatively, the exhaust gas may contain urea, ammonia, and the like that can be added in the denitrification treatment by the ammonia catalytic reduction method.

[0023] Exhaust gas applicable to the present invention may be gas discharged from an exhaust gas generating source 5 such as a thermal power plant, a garbage incinerator, a cement kiln, an aluminum melting furnace, or a boiler.

[0024] The temperature of the exhaust gas immediately before passing through the catalytic bag filter is preferably 80 to 250° C., more preferably 100 to 200° C. The temperature of the exhaust gas immediately before directly contacting with the CO2 absorbing liquid is preferably 20 to 80° C., more preferably 30 to 65° C., and more preferably 40 to 50° C.

[0025] The catalytic bag filter used in the present invention has the following functions: denitration, NO oxidation, and Hg 0 It has at least one function selected from the group consisting of an oxidation function, a desulfurization function, and an adsorption function. The catalytic bag filter is a bag filter configured to be capable of collecting particulate matter (soot, dust, etc.) (dust removal treatment), and is supported with catalysts and functional substances that can add various functions. Examples of the catalytic bag filter used in the present invention include those described in Patent Document 6, Patent Document 7, Patent Document 9, etc.

[0026] Although not limited to this example, the bag filter may be made of a filter cloth including one or more base fabrics made of woven or nonwoven fabric and one or more felt layers laminated on one or both sides of the base fabric. The base fabric or felt layer may be made of a fiber material made of a heat-resistant organic resin such as polyphenylene sulfide resin or polytetrafluoroethylene resin, or a heat-resistant inorganic fiber material such as glass fiber, carbon fiber, or titania fiber (JP Patent Publication 2002-113311).

[0027] It may be preferable to provide a felt layer on the side where the exhaust gas flows in. The felt layer may be useful, for example, for collecting submicron-sized particulate matter. The base fabric and / or felt layer may also act as a carrier for carrying catalysts, functional materials, etc.

[0028] The bag filter is not particularly limited in its external shape. For example, it may be cylindrical, cylindrical with a bottom, or bag-shaped. The cylindrical, cylindrical with a bottom, or bag-shaped bag filter may have a cylindrical, cylindrical with a bottom, or bag-shaped filter cloth and a gauge (retainer) incorporated in the filter cloth. The bag filter itself has a function of collecting soot, particulate matter (PM), and the like.

[0029] The catalytic bag filter used in the present invention has various other functions in addition to the collection function. These functions include denitration, NO oxidation, Hg 0 The function may be at least one selected from the group consisting of an oxidation function, a desulfurization function, and an adsorption function. Note that the denitrification function includes a NOx reduction function such as a NO2 reduction function and a NO reduction function.

[0030] The catalytic bag filter used in the present invention may have a precoat layer containing slaked lime. The precoat layer is preferably provided on the side where the exhaust gas flows in. The slaked lime contained in the precoat layer neutralizes acid gases such as hydrogen chloride and SOx contained in the exhaust gas. The precoat layer also serves to capture unreacted acid gases or soot. The precoat layer may be formed on the base fabric and / or felt layer by adding slaked lime to the side where the exhaust gas flows in of the base fabric and / or felt layer.

[0031] The catalytic bag filter used in the present invention may have an adsorption layer containing powder having a pore structure such as activated alumina (Al2O3), diatomaceous earth, activated clay, silica (SiO2), and activated carbon. The adsorption layer is preferably provided in a position close to the side where the exhaust gas flows in. The powder having a pore structure is useful for adsorbing and removing chlorides, sulfur oxides, acidic ammonium sulfate, VOCs, dioxins, and the like that may be contained in the exhaust gas. Adding an element such as zinc or sulfur, or a metal halide such as zinc iodide or copper chloride to the powder having a pore structure may improve the adsorption ability. The adsorption layer may be formed by supporting the powder having a pore structure on a gauge (retainer), a base cloth, and / or a felt layer, or by sandwiching the powder between the base cloth and / or a felt layer. In addition, the adsorption layer may be formed by storing granular material having a pore structure such as activated alumina (Al2O3), diatomaceous earth, activated clay, silica (SiO2), and activated carbon in the cylinder of a bottomed cylindrical bag filter. Furthermore, a base fabric or felt layer may be formed using fibers having a fine pore structure, and the layer itself may serve as the adsorption layer.

[0032] The catalytic bag filter used in the present invention may have a catalytic layer. It is preferable to provide the catalytic layer at a position farther from the exhaust gas inflow side than the adsorption layer or precoat layer, from the viewpoint of suppressing catalyst degradation. The denitration catalyst that can be used in the catalytic layer is useful for reducing and reducing nitrogen oxides (NOx) that may be contained in exhaust gas. The denitration catalyst may be used in combination with an NO oxidation catalyst. The NO oxidation catalyst may be useful for oxidizing NO to convert it to NO2 and oxidizing particulate matter (PM) with NO2. The denitration catalyst may be used in combination with Hg depending on the composition. 0 It may have oxidizing properties, but Hg 0 The oxidation catalyst removes Hg, which is difficult to remove from exhaust gas. 0 It helps to oxidize and convert mercury to easily removed mercury compounds (HgO, HgCl2, etc.). 0 The oxidation catalyst and / or the NOx oxidation catalyst may be used in any combination as at least one catalyst layer. 0The oxidation catalyst layer and / or the NO oxidation catalyst layer may be provided as separate catalyst layers in any combination. 0 (melting point -38.83°C), and hydrogen chloride (boiling point -85.09°C) can change to mercury(II) chloride (melting point 304°C), which can be easily removed using filters. As a result, most of the NOx, NO, and mercury contained in the exhaust gas before it passes through the catalytic bag filter is removed simply by passing through it.

[0033] The catalytic bag filter used in the present invention may have a dioxin decomposition catalyst layer. The dioxin decomposition catalyst is useful for decomposing and reducing dioxins that may be contained in exhaust gas. The dioxin decomposition catalyst layer may be provided separately from the catalyst layer, or the catalyst and the dioxin decomposition catalyst may be used in any combination to provide at least one catalyst layer.

[0034] Denitrification, NO oxidation, Hg 0 The composition and preparation of catalysts suitable for oxidation or dioxin decomposition are well known and will not be described in detail here. 0 Examples of catalyst compositions suitable for oxidation or dioxin decomposition include those containing at least one precious metal element selected from the group consisting of W, Mo, and V, those containing precious metals such as Pt, Ru, Pd, and Rh, those containing titanium oxide, silicon oxide, gypsum, alumina, etc., those containing aluminosilicates, zeolites, etc., and any combination of these. The catalyst layer can be formed by supporting such catalysts on a base fabric and / or felt layer, or by sandwiching them between base fabric and / or felt layers.

[0035] The catalytic bag filter is housed in a bag filter house having a gas inlet and a gas outlet, and exhaust gas is supplied from the gas inlet of the bag filter house, making it easy to pass the exhaust gas through the catalytic bag filter. The exhaust gas that has passed through the catalytic bag filter leaves the bag filter house from the gas outlet. By optimizing the functions given to the catalytic bag filter in a well-balanced manner, multiple harmful substances contained in the exhaust gas immediately before passing through the catalytic bag filter can be simultaneously and significantly reduced by the exhaust gas passing through the catalytic bag filter. When soot, dust, particulate matter, etc. accumulate on the catalytic bag filter and the pressure loss becomes higher than a predetermined value, the accumulated substances can be removed by vibration or backwashing using a pulse jet (see Patent Document 8, etc.).

[0036] Next, the exhaust gas that has passed through the catalytic bag filter is cooled to lower the temperature of the exhaust gas. The exhaust gas may be cooled by indirect contact with a refrigerant via a heat exchanger, or by direct contact with a cooling liquid. As the cooling liquid, ordinary water, seawater, an alkaline aqueous solution (aqueous solution of a base such as NaOH, KOH, or Ca(OH)2), or a basic aqueous solution of a reducing substance (dithionite, thiosulfate, sulfite, bisulfite, iodide, etc.) can be preferably used. The direct contact between the exhaust gas and the cooling liquid can be performed by a gas-liquid contact operation known in the art. Examples of the apparatus for the gas-liquid contact operation include a plate (plate, tray, or tray) tower, a packed tower, a wetted wall tower, a spray tower, and a scrubber. Of these, a spray tower is preferred. By this cooling, the exhaust gas is adjusted to a temperature suitable for the next step, CO2 absorption. The cooling liquid after the gas-liquid contact operation can be cooled by a chiller or the like as necessary, and consumed bases and reducing substances can be replenished as necessary, and can be used again for direct contact with the exhaust gas.

[0037] When an alkaline aqueous solution is used as a coolant, a base such as sodium hydroxide reacts with the sulfur dioxide in the exhaust gas to produce sulfite (for example, SO2 + 2NaOH → Na2SO3 + H2O). Sulfite reacts with the sulfur dioxide in the exhaust gas to produce hydrogen sulfite (for example, SO2 + Na2SO3 + H2O → 2NaHSO3). These reactions remove sulfur dioxide from the exhaust gas. At this time, the sulfurous acid concentration of the alkaline aqueous solution increases due to the reaction with the sulfur dioxide in the exhaust gas. However, the pH of the alkaline aqueous solution decreases due to the reaction with the nitrogen dioxide and sulfur dioxide in the exhaust gas. A decrease in the pH of the alkaline aqueous solution, i.e., a decrease in the base, reduces the reaction with sulfur dioxide and reduces the production of sulfite or hydrogen sulfite. Therefore, direct contact between the alkaline aqueous solution and the exhaust gas reduces the sulfurous acid concentration overall. When an aqueous solution of sulfite or hydrogen sulfite is used, sulfite ions react with nitrogen dioxide in the exhaust gas and are reduced to nitrogen or nitrogen oxide, thereby removing nitrogen dioxide from the exhaust gas.

[0038] Next, the cooled exhaust gas is directly contacted with a CO2 absorbing solution to reduce carbon dioxide in the exhaust gas. As the CO2 absorbing solution, an aqueous solution containing an amine compound is preferably used. Examples of the amine compound include alcoholic hydroxyl group-containing primary amines such as monoethanolamine and 2-amino-2-methyl-1-propanol, alcoholic hydroxyl group-containing secondary amines such as diethanolamine and 2-methylaminoethanol, alcoholic hydroxyl group-containing tertiary amines such as triethanolamine and N-methyldiethanolamine, polyethylene polyamines such as ethylenediamine, triethylenediamine, and diethylenetriamine, cyclic amines such as piperazines, piperidines, and pyrrolidines, polyamines such as xylylenediamine, amino acids such as methylaminocarboxylic acid, and mixtures thereof. In addition, the CO2 absorbing solution may contain a carbon dioxide absorption promoter or a corrosion inhibitor, and further, methanol, polyethylene glycol, sulfolane, and the like as other media.

[0039] The direct contact of the flue gas with the CO2 absorbing liquid can be carried out by a gas-liquid contact operation known in the art. Examples of devices related to the gas-liquid contact operation include a plate (plate, plate plate, tray) tower, a packed tower, a wetted-wall tower, a spray tower, and a scrubber. Of these, a plate tower and a packed tower are preferred. For example, the flue gas flows into the bottom of the absorption tower, rises in the absorption section, passes through the water washing section, and is discharged from the top of the absorption tower as purified gas 12. The CO2 absorbing liquid is poured onto the top of the absorption section, comes into countercurrent contact with the flue gas in the absorption section, absorbs carbon dioxide in the flue gas, and accumulates at the bottom of the absorption tower.

[0040] The CO2 absorbing liquid accumulated at the bottom of the absorption tower has a high carbon dioxide concentration. This CO2 absorbing liquid is sent to a desorption tower, for example, where carbon dioxide is desorbed from the CO2 absorbing liquid by heating with steam or the like, and carbon dioxide 13 is discharged from the top of the desorption tower. The CO2 absorbing liquid from which carbon dioxide has been desorbed accumulates at the bottom of the desorption tower and is returned to the absorption tower and recycled for carbon dioxide absorption. Meanwhile, the carbon dioxide 13 discharged from the top of the desorption tower is variously treated in the next process. For example, carbon dioxide can be stored underground or in the ocean, or can be used for enhanced crude oil recovery technology, welding, dry ice, synthesis of chemicals (oxygen-containing compounds (polycarbonate, urethane, etc.), general-purpose materials, etc.), synthesis of fuels (methanol, ethanol, methane, etc.), synthesis of carbonates, absorption into concrete products, absorption into seaweed, seaweed, and microalgae (biofuel synthesis), etc.

[0041] In the present invention, harmful substances such as nitrogen dioxide, sulfur dioxide, and mercury are efficiently removed by the catalytic bag filter and the gas cooling device that directly contacts the coolant. The exhaust gas that is directly contacted with the CO2 absorbing liquid contains almost no nitrogen dioxide or sulfur dioxide, which cause a decrease in the carbon dioxide absorption capacity of the CO2 absorbing liquid. As a result, the decrease in the carbon dioxide absorption capacity of the CO2 absorbing liquid is suppressed, and the life of the CO2 absorbing liquid is significantly extended. In addition, it is economical because the frequency of stopping the operation of the CO2 absorbing device and performing the operation of removing nitrates and the like from the CO2 absorbing liquid (reclaimer) is reduced.

[0042] In the present invention, the exhaust gas may be subjected to at least one of the following treatments, if necessary, before passing the exhaust gas through the catalytic bag filter: denitration treatment, dust collection treatment, desulfurization treatment, and desalination treatment.

[0043] A denitration device (denitrification treatment) reduces nitrogen oxides in exhaust gas. Denitrification treatment can be performed by passing exhaust gas through the denitration device. The denitration device is not particularly limited, but an ammonia catalytic reduction denitration device using a catalyst composition containing titanium oxide is preferred. The catalyst may contain at least one element selected from the group consisting of W, Mo and V, gypsum, silica, etc., in addition to titanium oxide. Examples of catalysts to be installed in the denitration device include catalyst compositions formed into honeycomb, columnar, cylindrical, etc., and catalyst compositions formed into a corrugated plate shape by adhering the catalyst composition to a metal substrate such as a metal lath or a ceramic or glass mesh woven fabric. In the present invention, a catalyst formed into a corrugated plate shape is preferably used.

[0044] Dust collection devices (dust collection treatment) reduce soot (combustion ash, particulate matter (PM), etc.) in exhaust gas. Dust collection treatment can be performed by passing exhaust gas through a dust removal device. There are no particular limitations on the dust removal device used in the present invention. For example, an electric dust collector, a bag filter device, etc. can be used.

[0045] A desulfurization device (desulfurization treatment) reduces sulfur oxides in exhaust gas. Desulfurization treatment can be performed by passing exhaust gas through the desulfurization device. Although there is no particular limitation on the desulfurization device used in the present invention, a device using a wet limestone gypsum method or a magnesium hydroxide method is preferable.

[0046] A desalination device (desalting process) reduces acidic substances such as hydrogen chloride and sulfur oxides in exhaust gas. The desalination process can be performed by passing the exhaust gas through the desalination device. The desalination device used in the present invention is not particularly limited, but is a device that can directly contact the exhaust gas with a desalination and desulfurization agent. As the desalination and desulfurization agent, for example, an alkaline aqueous solution such as an aqueous solution of sodium bicarbonate (sodium bicarbonate) or an aqueous solution of slaked lime can be used. The temperature of the exhaust gas immediately before passing through the desalination device can be adjusted by a gas temperature adjustment device. As the gas temperature adjustment device, for example, a heat exchanger, a heater, etc. can be used. As the medium of the heat exchanger 11 (which supplies heat to the exhaust gas) for adjusting the temperature of the exhaust gas immediately before passing through the desalination device, a medium discharged from the heat exchanger 10 (which recovers heat from the exhaust gas) for adjusting the temperature of the exhaust gas immediately before passing through the desulfurization device can be used. The medium that transferred heat to the exhaust gas in the heat exchanger 11 can be returned to the heat exchanger 10 and used to recover heat from the exhaust gas.

[0047] The temperature of the exhaust gas immediately before passing through the catalytic bag filter can be adjusted by a desulfurization device or demineralization device, which may be installed upstream of the catalytic bag filter, or a gas temperature adjustment device. For example, a heat exchanger, a heater, etc. can be used as the gas temperature adjustment device. The medium discharged from the heat exchanger 10 (which recovers heat from the exhaust gas) for adjusting the temperature of the exhaust gas immediately before passing through the desulfurization device can be used as the medium for the heat exchanger 15 (which supplies heat to the exhaust gas) for adjusting the temperature of the exhaust gas immediately before passing through the catalytic bag filter. The medium that has transferred heat to the exhaust gas in the heat exchanger 15 can be returned to the heat exchanger 10 and used to recover heat from the exhaust gas. [Explanation of symbols]

[0048] 1: Catalytic bag filter 2: Gas cooling device 3: CO2 absorber 4:CO2 capture device 5: Exhaust gas sources 6: Denitration equipment 7: Dust collector 8: Desulfurization equipment 9: Desalination equipment 10: Gas temperature regulator (heat exchanger for heat recovery) 11: Gas temperature control device (heat exchanger for heat supply) 12: Purified exhaust gas (to the chimney) 13: Carbon dioxide 14: Denitrification agents (ammonia, urea, etc.) 15: Gas temperature control device (heat exchanger for heat supply)

Claims

1. The exhaust gas containing at least one selected from the group consisting of soot, hydrogen chloride, nitrogen oxides, sulfur oxides, mercury, volatile organic compounds, and carbon oxides is treated with a denitrification function, a NO oxidation function, a Hg oxidation function, and a ０ Passing the mixture through a catalytic bag filter carrying a catalyst having at least one function selected from the group consisting of an oxidation function and a desulfurization function; Cooling the exhaust gas that has passed through the catalytic bag filter reduces the temperature of the exhaust gas, The cooled exhaust gas is then ２ A method for purifying flue gas, comprising reducing carbon dioxide in the flue gas by direct contact with an absorption liquid.

2. 2. The method for purifying exhaust gas according to claim 1, further comprising subjecting the exhaust gas to at least one treatment selected from the group consisting of denitration, dust collection, desulfurization, and demineralization before passing the exhaust gas through the catalytic bag filter.

3. 2. The method for purifying exhaust gas according to claim 1, wherein the temperature of the exhaust gas immediately before passing through the catalytic bag filter is 80 to 250°C.

4. CO ２ 2. The method for purifying an exhaust gas according to claim 1, wherein the temperature of the exhaust gas immediately before being brought into direct contact with the absorption liquid is 20 to 80°C.

5. Denitration function, NO oxidation function, Hg ０ a catalytic bag filter carrying a catalyst having at least one function selected from the group consisting of an oxidation function and a desulfurization function; a gas cooler configured to cool the gas to reduce the temperature of the gas; and Gas and CO ２ A CO2 absorber configured to reduce carbon dioxide in gas by direct contact with an absorbing liquid. ２ an absorber; The exhaust gas containing at least one selected from the group consisting of soot, hydrogen chloride, nitrogen oxides, sulfur oxides, mercury, volatile organic compounds, and carbon oxides is filtered through a catalytic bag filter, a gas cooler, and a CO ２ An exhaust gas purification device configured so that it can pass through an absorber in sequence.

6. The present invention further includes a demineralizer configured to reduce hydrogen chloride in the gas, and the exhaust gas containing at least one selected from the group consisting of soot, hydrogen chloride, nitrogen oxides, sulfur oxides, mercury, volatile organic compounds, and carbon oxides is passed through the demineralizer, catalytic bag filter, gas cooler, and CO ２ The exhaust gas purification device according to claim 5 , which is configured so that the exhaust gas can pass through the absorption device in this order.

7. a denitration device configured to reduce nitrogen oxides in the gas; A dust collector configured to reduce soot and dust in the gas; and Further comprising a desulfurization device configured to reduce sulfur oxides in the gas; The exhaust gas containing at least one selected from the group consisting of soot, hydrogen chloride, nitrogen oxides, sulfur oxides, mercury, volatile organic compounds, and carbon oxides is used in a denitration device, a dust collector, a desulfurization device, a catalytic bag filter, a gas cooler, and a CO ２ The exhaust gas purification device according to claim 5 , which is configured so that the exhaust gas can pass through the absorption device in this order.

8. further comprising a demineralizer configured to reduce hydrogen chloride in the gas; The exhaust gas containing at least one selected from the group consisting of soot, hydrogen chloride, nitrogen oxides, sulfur oxides, mercury, volatile organic compounds, and carbon oxides is used in a denitration device, a dust collector, a desulfurization device, a demineralization device, a catalytic bag filter, a gas cooler, and a CO ２ The exhaust gas purification device according to claim 7, which is configured so that the exhaust gas can pass through the absorption device in this order.

9. The exhaust gas purification method described in claim 1, wherein the catalytic bag filter has the denitrification function and at least one function selected from the group consisting of the NO oxidation function, the Hg 0 oxidation function, the desulfurization function and the adsorption function.

10. The catalytic bag filter has a catalyst layer on which the catalyst is supported and an adsorption layer having an adsorption function, 2. The exhaust gas purification method according to claim 1, wherein the catalyst layer is provided at a position farther from the exhaust gas inflow side than the adsorption layer.

11. The catalytic bag filter further has a precoat layer containing slaked lime, The exhaust gas purification method according to claim 10 , wherein the catalyst layer is provided at a position farther from the exhaust gas inflow side than the adsorption layer and the precoat layer.

12. A method for purifying exhaust gas as described in claim 1, wherein the temperature of the exhaust gas is lowered by directly contacting the exhaust gas that has passed through the catalytic bag filter with a coolant.

13. A method for purifying exhaust gas as described in claim 2, wherein the exhaust gas after passing through a dust collector configured to reduce soot and dust in the gas is passed through the catalytic bag filter.

14. The exhaust gas purification device described in claim 5, wherein the catalytic bag filter has the denitrification function and at least one function selected from the group consisting of the NO oxidation function, the Hg 0 oxidation function, the desulfurization function and the adsorption function.

15. The catalytic bag filter has a catalyst layer on which the catalyst is supported and an adsorption layer having an adsorption function, The exhaust gas purification device according to claim 5 , wherein the catalyst layer is provided at a position farther from the exhaust gas inflow side than the adsorption layer.

16. The catalytic bag filter further has a precoat layer containing slaked lime, The exhaust gas purification device according to claim 15, wherein the catalyst layer is provided at a position farther from the exhaust gas inflow side than the adsorption layer and the precoat layer.

17. An exhaust gas purification device as described in Claim 5, wherein the gas cooling device is configured to lower the temperature of the exhaust gas by directly contacting a cooling liquid with the exhaust gas that has passed through the catalytic bag filter.

18. The method further includes a dust collector configured to reduce soot and dust in the gas, The exhaust gas purification device according to claim 5 , wherein the exhaust gas after passing through the dust collector passes through the catalytic bag filter.

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