Gas Processing Systems

Abstract

To provide a gas treatment technique effective for reducing thermal energy loss when treating an exhaust gas discharged from a coat-drying furnace.SOLUTION: A gas treatment system 101 includes: a coat-drying furnace 10 for drying a workpiece W after coating; a combustion device 20 having a combustion chamber 21 into which a portion Gb of an exhaust gas Ga discharged from the coat-drying furnace 10 is returned, wherein a drying gas Gd generated through combustion treatment in the combustion chamber 21 is supplied to the coat-drying furnace 10; a deodorizing treatment part 30 for removing an odor component contained in a residual gas Gc, which is not returned to the combustion chamber 21, out of the exhaust gas Ga; a denitration treatment part 40 for removing a nitrogen oxide contained in the residual gas Gc; and a gas-returning path 60 for sending a recovered gas Gf generated by treatment by the deodorizing treatment part 30 and the denitration treatment part 40 to the combustion chamber.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a gas treatment system for treating exhaust gas discharged from a paint drying oven. [Background technology]

[0002] Patent Document 1 below describes a gas treatment system in which workpieces such as automobile bodies are dried in a paint drying oven after being painted. This gas treatment system is configured so that high-temperature gas generated by a combustion burner in a heating device is supplied to the paint drying oven for drying, while most of the exhaust gas generated in the paint drying oven is returned to the heating device. In addition, the exhaust gas discharged from the paint drying oven is separated from resin in a cyclone device, then combusted in a combustion device, and all of the gas is then exhausted outdoors.

[0003] In paint drying ovens, volatile organic compounds (VOCs) and tar are generated from the paint as the workpieces are dried. Volatile organic compounds are odorous components that have the property of giving off an odor as they dry. The high-temperature gas supplied to the paint drying oven from the heating device contains nitrogen oxides generated during combustion. Nitrogen oxides are also generated when odorous components in the gas are decomposed during the combustion process in the combustion device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-66638 Summary of the Invention [Problem to be solved by the invention]

[0005] In this type of gas treatment technology for treating exhaust gases generated in paint dryers, the challenge is to increase thermal energy efficiency by minimizing the amount of outdoor exhaust. In the case of the gas treatment system described in Cited Document 1, returning the high-temperature gas discharged from the combustion device to the paint dryer would be effective in reducing thermal energy loss. However, as mentioned above, the high-temperature gas discharged from the combustion device contains nitrogen oxides. If this high-temperature gas is returned directly to the paint dryer, the concentration of nitrogen oxides in the paint dryer will increase, which could adversely affect paint quality. Therefore, removing not only odorous components but also nitrogen oxides from the exhaust gas discharged from the paint dryer would make it possible to reduce thermal energy loss.

[0006] The present invention has been made in view of the above problems, and aims to provide a gas treatment technology that is effective in reducing thermal energy loss when treating exhaust gas discharged from a paint drying oven. [Means for solving the problem]

[0007] One aspect of the present invention is A paint drying oven for drying the workpiece after painting, a combustion device having a combustion chamber to which a portion of the exhaust gas discharged from the paint drying oven is returned, and which supplies drying gas generated by combustion treatment in the combustion chamber to the paint drying oven; a deodorizing treatment unit that removes odorous components contained in the remaining gas that is not returned to the combustion chamber from the exhaust gas; a denitration treatment unit for removing nitrogen oxides contained in the residual gas; a gas return path for sending the deodorized and denitrified gas generated by the processes in the deodorizing treatment section and the denitrification treatment section to at least one of the combustion chamber and the paint drying furnace; Equipped with picture, the deodorizing treatment unit is a deodorizing device having a treatment unit that combusts the residual gas at a temperature higher than that of the paint drying oven, The denitration treatment unit is a denitration device having a treatment unit that receives the deodorized gas generated by the deodorization device and burns it, a reduction catalyst filled in the treatment unit, and an injection device that injects a reducing agent into the treatment unit. Gas treatment systems, is located. Another aspect of the present invention is A paint drying oven for drying the workpiece after painting, a combustion device having a combustion chamber to which a portion of the exhaust gas discharged from the paint drying oven is returned, and which supplies drying gas generated by combustion treatment in the combustion chamber to the paint drying oven; a deodorizing treatment unit that removes odorous components contained in the remaining gas that is not returned to the combustion chamber from the exhaust gas; a denitration treatment unit for removing nitrogen oxides contained in the residual gas; above a gas return path for sending the deodorized and denitrified gas generated by the processes in the deodorizing treatment section and the denitrification treatment section to at least one of the combustion chamber and the paint drying furnace; a deodorization / denitrification device that serves both as the deodorization processing unit and the denitrification processing unit, The deodorizing and denitrifying device has a treatment unit that combusts the residual gas at a temperature higher than that of the paint drying furnace, a reducing catalyst filled in the treatment unit, and an injection device that injects a reducing agent into the treatment unit, and is configured to perform a deodorizing treatment that removes odorous components contained in the residual gas and a denitrifying treatment that removes nitrogen oxides contained in the residual gas in parallel within the treatment unit, The gas return path is provided with an auxiliary denitration device, above a gas treatment system, wherein the auxiliary denitration device comprises a treatment unit that combusts the deodorized and denitrified gas generated by the deodorization and denitration device, a reduction catalyst filled in the treatment unit, and an injection device that injects a reducing agent into the treatment unit; is located. [Effects of the Invention]

[0008] In the gas treatment system of the above aspect, a portion of the exhaust gas discharged from the paint drying oven, which dries painted workpieces, is returned to the combustion chamber, and the remaining gas that is not returned to the combustion chamber is treated in a deodorizing treatment unit and a denitrifying treatment unit. Odor components contained in the remaining gas are removed in the deodorizing treatment unit, and nitrogen oxides contained in the remaining gas are removed in the denitrifying treatment unit. The deodorized and denitrified gas produced by the treatment in the deodorizing treatment unit and the denitrifying treatment unit is sent to at least one of the combustion chamber and the paint drying oven via a gas return path.

[0009] The deodorized and denitrified gas itself contains almost no nitrogen oxides. Therefore, even if the deodorized and denitrified gas is sent to the combustion chamber or paint drying oven, the nitrogen oxide concentration in the paint drying oven can be prevented from rising to a level that would degrade paint quality. Therefore, by recovering the deodorized and denitrified gas, the amount of outdoor exhaust can be reduced, and thermal energy loss can be reduced accordingly.

[0010] As described above, according to the above-mentioned embodiment, it is possible to provide a gas treatment technology that is effective in reducing the loss of thermal energy when treating the exhaust gas discharged from a paint drying oven. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic configuration diagram of a gas processing system according to a first embodiment. [Figure 2]FIG. 10 is a schematic configuration diagram of a gas processing system according to a second embodiment. [Figure 3] FIG. 10 is a schematic configuration diagram of a gas processing system according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Preferred embodiments of the above aspects are described below.

[0013] The gas treatment system of the above aspect is preferably equipped with a deodorization / denitration device that serves both as the deodorization treatment section and the denitration treatment section, and the deodorization / denitration device has a treatment unit that combusts the residual gas at a temperature higher than that of the paint drying oven, a reduction catalyst filled in the treatment unit, and an injection device that injects a reducing agent into the treatment unit, and is configured so that the deodorization treatment that removes odorous components contained in the residual gas and the denitration treatment that removes nitrogen oxides contained in the residual gas are carried out in parallel within the treatment unit.

[0014] This gas treatment system uses a deodorization / denitrification device that serves both the deodorization and denitrification treatment functions. In the treatment space of this deodorization / denitrification device's treatment unit, the remaining gas is burned at a higher temperature than in a paint drying oven. During the deodorization process, odorous components are decomposed and removed by high-temperature combustion. In the denitrification process, nitrogen oxides are decomposed and removed by injecting a reducing agent in the presence of a reduction catalyst. With this type of gas treatment system, the use of a deodorization / denitrification device makes it possible to keep equipment costs lower than when deodorization and denitrification are performed in separate devices.

[0015] In the gas treatment system of the above aspect, it is preferable that a heat storage body is provided in the treatment unit of the deodorization and denitration device.

[0016] This gas treatment system uses a heat storage material to maintain a high temperature inside the treatment unit, reducing the amount of fuel required for combustion treatment. The use of a heat storage material also reduces the temperature of the deodorized and denitrified gases discharged from the deodorizing and denitrifying equipment.

[0017] In the gas treatment system of the above aspect, an auxiliary denitration device is provided in the gas return path, and the auxiliary denitration device preferably has a treatment unit that combusts the deodorized and denitrified gas produced in the deodorization and denitration device, a reduction catalyst filled in the treatment unit, and an injection device that injects a reducing agent into the treatment unit.

[0018] According to this gas treatment system, the deodorized and denitrified gas produced by the deodorizer and denitrator is further subjected to a denitration process in which nitrogen oxides are removed in an auxiliary denitrator. In this denitration process, nitrogen oxides are decomposed and removed by injecting a reducing agent in the presence of a reduction catalyst, just as in the case of the deodorizer and denitrator. Therefore, the denitration process is carried out in two stages: the deodorizer and denitrator and the auxiliary denitrator. This makes it possible to further reduce the concentration of nitrogen oxides contained in the recovered deodorizer and denitrified gas.

[0019] In the gas treatment system of the above aspect, the deodorization treatment section is preferably a deodorization device having a treatment unit that combusts the residual gas at a temperature higher than that of the paint drying oven, and the denitrification treatment section is preferably a denitrification device having a treatment unit that receives the deodorized gas produced in the deodorization device and combusts it, a reduction catalyst filled in the treatment unit, and an injection device that injects a reducing agent into the treatment unit.

[0020] According to this gas treatment system, the deodorized gas produced by the deodorization process in the deodorizer is subjected to denitration treatment in the denitration device to remove nitrogen oxides. In the deodorization process in the deodorizer, odorous components are decomposed and removed by high-temperature combustion. In addition, in the denitration process in the denitration device, nitrogen oxides are decomposed and removed by injecting a reducing agent in the presence of a reducing catalyst. As a result, if the deodorization device is an existing facility, it is possible to utilize the existing facility and simply add a denitration device, thereby keeping the cost of facility modification low.

[0021] The gas treatment system of the above aspect preferably includes a heat exchanger that heats the outside air introduced into the combustion chamber by heat exchange with the deodorized and denitrified gas or the deodorized gas.

[0022] According to this gas treatment system, by providing a heat exchanger, the thermal energy of the deodorized and denitrified gas or deodorized gas can be recovered into the outside air, thereby reducing the amount of fuel used in the combustion chamber.

[0023] Hereinafter, specific embodiments of the gas processing system according to the above aspects will be described with reference to the drawings.

[0024] (Embodiment 1) 1, the gas treatment system 101 of the first embodiment is mainly composed of a paint drying oven 10, a combustion device 20, a deodorization and denitrification device 50, and a heat exchanger 70. This gas treatment system 101 is for treating the exhaust gas Ga discharged from the paint drying oven 10.

[0025] 1. Structure of the paint drying oven 10 The paint drying oven 10 is a drying oven that dries the workpiece W, which is an automobile body after painting. This paint drying oven 10 is operated at a high temperature, for example, at an internal temperature of about 160 to 200°C. Therefore, the paint drying oven 10 generates high-temperature exhaust gas Ga caused by the paint. This exhaust gas Ga is a smoke-like product of the paint being gasified inside the oven, and contains volatile organic compounds, other odorous gases, and tar. Volatile organic compounds are typically composed mainly of formaldehyde and acetaldehyde. These volatile organic compounds are also generally referred to as "VOC gases." Furthermore, this exhaust gas Ga contains nitrogen oxides (hereinafter referred to as "NO X In this specification, for the sake of convenience, the gas that combines VOC gases and other odorous gases will be simply referred to as "odor components."

[0026] 2. Structure of the combustion device 20 The combustion device 20 has a combustion chamber 21, a combustion burner 22, and a suction fan 23. Partial gas Gb, which is a part of the exhaust gas Ga discharged from the paint drying oven 10, is returned to the combustion chamber 21. In order to minimize thermal energy loss, it is preferable to increase the ratio of partial gas Gb to exhaust gas Ga. The combustion chamber 21 is provided with a combustion burner 22 that combusts the partial gas Gb together with outside air using liquefied natural gas (hereinafter referred to as "LNG") as fuel. In this combustion chamber 21, drying gas Gd at a temperature of, for example, about 160 to 200°C is generated by the combustion process.

[0027] The drying gas Gd generated in the combustion chamber 21 is sucked in by the suction fan 23 and supplied to the paint drying furnace 10, where the drying gas Gd is used to dry the workpieces W. At this time, the drying gas Gd contains NOx, which is generated by combining air and nitrogen during the combustion process in the combustion chamber 21. X Therefore, the exhaust gas Ga discharged from the paint drying oven 10 contains NO due to this drying gas Gd. X This NO X is the so-called "thermal NO X "It is called "

[0028] 3. Structure of deodorizing and denitrifying device 50 The deodorizing and denitrifying device 50 is a device that receives and treats the residual gas Gc that is not returned to the combustion chamber 21 from the exhaust gas Ga discharged from the paint drying furnace 10. The residual gas Gc has the same gas composition as the exhaust gas Ga, and contains odor components and NO. X The deodorizing and denitrifying device 50 is provided with a treatment unit 50a having a treatment space therein for combusting the residual gas Gc. The treatment space of this treatment unit 50a is provided with a combustion burner 51 for the combustion treatment, and further, a reduction catalyst ("NO X The deodorizing and denitrifying device 50 is filled with a reducing catalyst (also called a "reducing catalyst") 52 and a heat storage material 53. The deodorizing and denitrifying device 50 is also equipped with an injection device 54 that injects a reducing agent A into the treatment unit 50a. The reducing agent A injected from the injection device 54 is added to the residual gas Gc flowing through the treatment space of the treatment unit 50a.

[0029] The combustion burner 51 uses LNG as fuel to combustibly treat the residual gas Gc. The deodorization and denitration device 50 is operated at a high temperature such that the temperature of the treatment space of the treatment unit 50a is, for example, about 800 to 900°C. As a result, in the treatment space of the treatment unit 50a, the residual gas Gc is combusted by the combustion burner 51, thereby performing a deodorization treatment to remove odorous components contained in the residual gas Gc. Here, "deodorization treatment to remove odorous components" means a treatment to reduce odorous components to a level below the control standard value. Therefore, the gas after the deodorization treatment may contain odorous components at a concentration below the control standard value, or may not contain any odorous components at all. On the other hand, this combustion treatment can remove odorous components by combustion decomposition, while also removing NO X This will cause new NO to be generated. X As in the case of the combustion chamber 21, the thermal NO X In addition, since the combustion temperature of the deodorizing and denitrifying device 50 is higher than that of the combustion chamber 21, the NO X It is known that the content ratio of the fuel in the combustion chamber 21 is significantly higher than that in the combustion chamber 22.

[0030] In the deodorization and denitration device 50 of this embodiment, in parallel with this deodorization treatment, the residual gas Gc is brought into contact with the reduction catalyst 52 in a state where the reducing agent A is injected, and is then combusted by the combustion burner 51. X At this time, denitration treatment is performed to remove NO in the gas Gc. X is decomposed at high temperatures and reduced to nitrogen and water. X "Denitrification treatment" refers to the process of removing NO to a level below the control standard value. X Therefore, the gas after denitrification contains NO X may remain at concentrations below the control standard value, or NO X In this way, the deodorizing and denitrifying device 50 performs a deodorizing process to remove odorous components contained in the residual gas Gc, and a denitrifying process to remove NO contained in the residual gas Gc. XThe deodorization treatment for removing the oxidized gas and the denitration treatment for removing the oxidized gas are carried out in parallel in one treatment unit 50a, and the treatment unit 50a is configured to serve both as the deodorization treatment unit 30 for performing the deodorization treatment and the denitration treatment unit 40 for performing the denitration treatment.

[0031] Here, the deodorized and denitrified gas Gf generated by the deodorizing and denitrifying device 50 is obtained by extracting odor components and NO from the residual gas Gc. X Therefore, even if this deodorized and denitrified gas Gf is returned from the combustion chamber 21 to the paint drying oven 10, the high concentration of NO X Therefore, the gas treatment system 101 of this embodiment is provided with a connection path 60 that branches off from the gas path 50b downstream of the deodorization and denitrification device 50 and connects this gas path 50b to the combustion chamber 21.

[0032] 4. Combination of reducing agent A and reduction catalyst 52 Typically, ammonia, hydrocarbons, hydrogen, etc. can be used as the reducing agent A. When ammonia is used as the reducing agent A, for example, a catalyst selected from a vanadium-titania carrier, a noble metal catalyst, a zeolite catalyst, an iron ore catalyst, and an activated coke catalyst can be used as the reduction catalyst 52. When hydrocarbons are used as the reducing agent A, for example, a zeolite catalyst or an alumina catalyst can be used as the reduction catalyst 52. When hydrogen is used as the reducing agent A, for example, a noble metal-hydrophobic carrier can be used as the reduction catalyst 52.

[0033] The reduction catalyst 52 and the heat storage body 53 may be separate bodies or may be integrally formed. When the reduction catalyst 52 and the heat storage body 53 are integrally formed, a part or all of the carrier supporting the reduction catalyst 52 may be used as the heat storage body 53.

[0034] The connection path 60 is a gas return path that sends the deodorized and denitrified gas Gf generated by the processes performed by the deodorization processing unit 30 and the denitrification processing unit 40 of the deodorization and denitrification device 50 to the combustion chamber 21. This connection path 60 is typically configured by piping that connects the gas path 50b and the combustion chamber 21 so that gas can flow through. This connection path 60 allows a portion of the deodorized and denitrified gas Gf flowing through the gas path 50b to be sent to the combustion chamber 21. As a result, the deodorized and denitrified gas Gf is supplied to the paint drying furnace 10 via the combustion chamber 21.

[0035] In addition, NO X is generated, but NO in the generated gas X The content ratio of NO in the product gas generated by the combustion process of residual gas Gc depends on the difference in combustion temperature as mentioned above. X Therefore, the NO generated in the deodorizing and denitrifying device 50 X Even if the deodorized and denitrified gas Gf containing almost no NO is sent to the combustion chamber 21, the NO X It is unlikely to be a factor that increases the concentration of

[0036] The remainder of the deodorized and denitrified gas Gf flowing through gas path 50b is sent to heat exchanger 70. Heat exchanger 70 has the function of heating the outside air introduced into combustion chamber 21 by heat exchange with the deodorized and denitrified gas Gf. In addition, a suction fan 71 is provided in the path downstream of this heat exchanger 70 to exhaust the deodorized and denitrified gas Gf to the outdoors after heat exchange. By providing heat exchanger 70, the thermal energy of the deodorized and denitrified gas Gf can be recovered into the outside air, thereby reducing the amount of LNG used as fuel in combustion burner 22.

[0037] According to the above-described first embodiment, the following effects can be obtained.

[0038] In the gas treatment system 101 of the first embodiment, a part of the exhaust gas Ga discharged from the paint drying furnace 10 that dries the painted workpiece W is returned to the combustion chamber 21 as Gb, and the remaining gas Gc that is not returned to the combustion chamber 21 is treated in the deodorization and denitrification device 50 (the deodorization treatment unit 30 and the denitrification treatment unit 40). The odor components contained in the remaining gas Gc are removed in the deodorization treatment unit 30, and the NOx contained in the remaining gas is removed. X is removed in the denitration treatment unit 40. The deodorized and denitrified gas Gf generated in the deodorization and denitration device 50 is sent to the combustion chamber 21 through a connecting path 60.

[0039] Here, the deodorized and denitrified gas Gf itself contains NO X Therefore, even if the deodorized and denitrified gas Gf is sent to the combustion chamber 21, the NO X This prevents the concentration of CO₂ from rising to a level that would degrade the coating quality. Therefore, by recovering the deodorized and denitrified gas Gf, the amount of outdoor exhaust can be reduced, and the thermal energy loss can be reduced accordingly.

[0040] As described above, according to the first embodiment, it is possible to reduce the thermal energy loss when treating the exhaust gas Ga discharged from the paint drying oven 10.

[0041] The gas treatment system 101 of the first embodiment uses a deodorization / denitration device 50 that serves both as the deodorization treatment section 30 and the denitration treatment section 40. In the treatment space of the treatment unit 50a of this deodorization / denitration device 50, the residual gas Gc is combusted at a temperature higher than that of the combustion chamber 21 (and therefore higher than that of the paint drying oven 10). During this deodorization, odorous components are decomposed and removed by high-temperature combustion. In addition, in the denitration treatment, a reducing agent A is injected in the presence of a reduction catalyst 52 to remove NOx. X In such gas treatment system 101, by using deodorization / denitrification device 50, the cost of the device can be kept lower than when deodorization treatment and denitrification treatment are performed in separate devices.

[0042] According to the gas processing system 101 of the first embodiment, a high temperature state can be maintained inside the processing unit 50a by the heat storage body 53, and the amount of fuel used for the combustion process (amount of LNG used) can be reduced. Furthermore, by using the heat storage body 53, the temperature of the deodorized and denitrified gas Gf discharged from the deodorization and denitrification device 50 can be kept low.

[0043] In a modification particularly related to the above-described first embodiment, a structure can be adopted in which the heat storage body 53 filled in the treatment unit 50a of the deodorization and denitration device 50 is omitted, if necessary.

[0044] Next, other embodiments related to the above-described embodiment 1 will be described with reference to the drawings. In the other embodiments, the same elements as those in embodiment 1 are denoted by the same reference numerals, and the description of the same elements will be omitted.

[0045] (Embodiment 2) 2, gas treatment system 102 of embodiment 2 differs from gas treatment system 101 of embodiment 1 in that an auxiliary denitration device 55 is added. This auxiliary denitration device 55 is provided in connection path 60 that connects gas path 50b and combustion chamber 21.

[0046] The auxiliary denitration device 55 includes a treatment unit 55a having an internal treatment space for combusting the deodorized and denitrified gas Gf generated in the deodorization and denitration device 50, a reduction catalyst 57 filled inside the treatment unit 55a, and an injection device 58 for injecting a reducing agent A into the treatment space of the treatment unit 55a. The reduction catalyst 57 is of the same type as the reduction catalyst 52 used in the deodorization and denitration device 50. The deodorized and denitrified gas Gf is treated in the auxiliary denitration device 55 while flowing through the connection path 60. Therefore, the deodorized and denitrified gas Gf is subjected to denitration treatment in the treatment space of the treatment unit 55a of the auxiliary denitration device 55. In this denitration treatment, NO in the deodorized and denitrified gas Gf is removed. X is decomposed at high temperature and reduced to nitrogen and water. The deodorized and denitrified gas Gf' generated in the auxiliary denitration device 55 is sent to the combustion chamber 21 as a recovered gas.

[0047] The other configurations are the same as those in the first embodiment.

[0048] According to the gas treatment system 102 of the second embodiment, the deodorized and denitrified gas Gf generated in the deodorization and denitration device 50 is further denitrified by the auxiliary denitration device 55. X In this denitration treatment, as in the case of the deodorization / denitration device 50, a reducing agent A is injected from an injection device 80 in the presence of a reduction catalyst 57 to remove NO. X Therefore, the denitration treatment is carried out in two stages, in the deodorization / denitration device 50 and the auxiliary denitration device 55. As a result, the NO contained in the recovered deodorization / denitration gas Gf' is decomposed and removed. X Furthermore, the amount of LNG used as fuel in the combustion chamber 21 can be reduced by the amount of heat generated by the combustion process in the auxiliary denitration device 55.

[0049] In addition, the same effects as those of the first embodiment are achieved.

[0050] (Embodiment 3) 3, gas treatment system 103 of embodiment 3 differs from gas treatment system 101 of embodiment 1 in that it has a deodorization device 30 and a denitration device 40, which are separate devices. This gas treatment system 103 is a system similar to deodorization / denitration device 50 of embodiment 1, in which deodorization treatment section 30 and denitration treatment section 40 are separated, and is configured so that deodorization function of deodorization treatment section 30 is performed by deodorization device 30, and denitration function of denitration treatment section 40 is performed by denitration device 40.

[0051] The deodorizing device 30 is equipped with a treatment unit 30a having an internal treatment space for combusting the residual gas Gc at a temperature higher than that of the paint drying oven 10. The treatment space of this treatment unit 30a is provided with a combustion burner 31 for the combustion treatment, and is further filled with a heat storage medium 32.

[0052] The gas treatment system 103 includes a connection path 60 that branches off from the gas path 30b downstream of the deodorization device 30 and connects this gas path 30b to the combustion chamber 21, and a denitration device 40 is provided on this connection path 60.

[0053] The denitration device 40 includes a treatment unit 40a having an internal treatment space for receiving the deodorized gas Ge generated in the deodorization device 30 and performing combustion treatment thereon, a reduction catalyst 42 filled in the treatment unit 40a, and an injection device 43 for injecting a reducing agent A into the treatment unit 40a. The reduction catalyst 42 is of the same type as the reduction catalyst 52 of the first embodiment.

[0054] The remainder of the deodorized gas Ge flowing through the gas path 30b is sent to the heat exchanger 70. In the heat exchanger 70, the outside air introduced into the combustion chamber 21 is heated by heat exchange with the deodorized gas Ge.

[0055] The other configurations are the same as those in the first embodiment.

[0056] According to the gas treatment system 103 of the third embodiment, the deodorized gas Ge generated by the deodorization treatment in the deodorization device 30 is denitrified by the denitration device 40. X In the deodorization treatment in the deodorization device 30, odorous components are decomposed and removed by high-temperature combustion. In the denitration treatment in the denitration device 40, a reducing agent A is injected in the presence of a reduction catalyst 42, thereby removing NO. X Therefore, if the deodorizing device 30 is an existing facility, it is possible to utilize the existing facility and simply add the denitrification device 40, thereby keeping the cost required for facility modification low.

[0057] In addition, the same effects as those of the first embodiment are achieved.

[0058] In a modification particularly related to the above-described third embodiment, a structure in which the heat storage body 32 filled in the treatment unit 30a of the deodorizing device 30 is omitted can be adopted as necessary.

[0059] The present invention is not limited to the above-described embodiments, and various applications and modifications are possible without departing from the scope of the present invention. For example, the following embodiments can be implemented by applying the above-described embodiments.

[0060] In the above embodiment, the case where the deodorized and denitrified gases Gf, Gf' are sent only to the combustion chamber 21 through the connection path 60 has been exemplified, but the destination of the deodorized and denitrified gases Gf, Gf' is not limited to the combustion chamber 21. For example, it is also possible to employ a structure in which the deodorized and denitrified gases Gf, Gf' are sent only to the paint drying oven 10 through the connection path 60, or a structure in which the deodorized and denitrified gases Gf, Gf' are sent in parallel to both the paint drying oven 10 and the combustion chamber 21 through the connection path 60.

[0061] In the above embodiment, the case where the reducing agent A and the reduction catalysts 42, 52, and 57 are used in combination has been exemplified, but instead, it is also possible to use only the reducing agent A. For example, when ammonia, urea, cyanuric acid, or the like is used as the reducing agent A, as in the non-catalytic selective reduction method, the denitrification treatment can be performed without requiring the reduction catalysts 42, 52, and 57.

[0062] In the above embodiment, a gas treatment technology for treating exhaust gas emitted from a paint drying oven for automobile bodies has been exemplified. However, the use of this paint drying oven is not particularly limited, and it may be used, for example, to dry vehicle parts other than automobile bodies or workpieces in fields other than automobiles. [Explanation of symbols]

[0063] 10 Paint drying oven 20 Combustion equipment 21 Combustion chamber 30 Deodorizing device (deodorizing treatment section) 30a, 40a, 50a, 55a Processing Unit 32,53 Heat storage body 40 Denitration equipment (Denitrification processing section) 42,52,57 Reduction catalyst 43,54,58 Injection device 50 Deodorization and denitrification equipment 55 Auxiliary denitrification equipment 60 Connection path (gas return path) 70 Heat exchanger 101,102,103 Gas Treatment Systems A reducing agent Ga exhaust gas Gb Partial gas (part of exhaust gas) Gc remaining gas Ge deodorizing gas Gd drying gas Gf,Gf' Deodorized and denitrified gas double work

Claims

1. A paint drying oven for drying the workpiece after painting, a combustion device having a combustion chamber to which a portion of the exhaust gas discharged from the paint drying oven is returned, and which supplies drying gas generated by combustion treatment in the combustion chamber to the paint drying oven; a deodorizing treatment unit that removes odorous components contained in the remaining gas that is not returned to the combustion chamber from the exhaust gas; a denitration treatment unit for removing nitrogen oxides contained in the residual gas; a gas return path for sending the deodorized and denitrified gas generated by the processes performed by the deodorizing treatment unit and the denitrification treatment unit to at least one of the combustion chamber and the paint drying furnace; Equipped with the deodorizing treatment unit is a deodorizing device having a treatment unit that combusts the residual gas at a temperature higher than that of the paint drying oven, The denitrification treatment unit is a denitrification device having a treatment unit that receives the deodorized gas produced by the deodorization device and burns it, a reduction catalyst filled in the treatment unit, and an injection device that injects a reducing agent into the treatment unit.

2. A paint drying furnace for drying the workpiece after painting; a combustion device having a combustion chamber to which a portion of the exhaust gas discharged from the paint drying oven is returned, and which supplies drying gas generated by combustion treatment in the combustion chamber to the paint drying oven; a deodorizing treatment unit that removes odorous components contained in the remaining gas that is not returned to the combustion chamber from the exhaust gas; a denitration treatment unit for removing nitrogen oxides contained in the residual gas; a gas return path for sending the deodorized and denitrified gas generated by the processes performed by the deodorizing treatment unit and the denitrification treatment unit to at least one of the combustion chamber and the paint drying furnace; a deodorization / denitration device that serves both as the deodorization processing unit and the denitration processing unit, The deodorizing and denitrifying device includes a treatment unit that combusts the residual gas at a temperature higher than that of the paint drying oven, a reducing catalyst filled in the treatment unit, and an injection device that injects a reducing agent into the treatment unit, and is configured to perform a deodorizing treatment that removes odorous components contained in the residual gas and a denitrifying treatment that removes nitrogen oxides contained in the residual gas in parallel within the treatment unit; The gas return path is provided with an auxiliary denitration device, The auxiliary denitration device is a gas treatment system having a treatment unit that combusts the deodorized and denitrified gas produced by the deodorization and denitration device, a reduction catalyst filled in the treatment unit, and an injection device that injects a reducing agent into the treatment unit.

3. 3. The gas treatment system according to claim 2, wherein a heat storage body is provided in the treatment unit of the deodorization and denitration device.

4. 4. The gas treatment system according to claim 1, further comprising a heat exchanger that heats the outside air introduced into the combustion chamber by heat exchange with the deodorized and denitrified gas or the deodorized gas.

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