Exhaust gas treatment device and exhaust gas treatment method

Abstract

The present disclosure relates to an exhaust gas treatment device (100) comprising a combustion chamber (101) and a plurality of heat storage layers (107) connected to the combustion chamber (101). An untreated exhaust gas passes through at least one heat storage layer (107) among the plurality of heat storage layers (107) and is supplied to the combustion chamber (101), and after the exhaust gas has been treated, the treated exhaust gas passes through at least one heat storage layer (107) different from the previous at least one heat storage layer (107) and is discharged. The supply direction of the untreated exhaust gas and the exhaust direction of the treated exhaust gas are alternately switched at prescribed time intervals to carry out the exhaust gas treatment. The combustion chamber (101) is provided with a heating mechanism (105), and the temperature of the combustion chamber (101) is maintained at 750°C or higher. The plurality of heat storage layers (107) are provided with a heat source in an area of 60% or more from the bottom in the height direction, and the temperature of an area of 80% or more from the bottom in the height direction is maintained at a temperature that is higher than the temperature of the combustion chamber (101) by 50°C or more.

Description

Exhaust gas treatment device and exhaust gas treatment method

[0001] The present invention relates to an exhaust gas treatment apparatus and an exhaust gas treatment method.

[0002] In painting processes, printing processes, plastic and plywood manufacturing facilities, food processing, industrial waste incineration facilities, etc., harmful and odorous flammable malodorous components such as alcohols, esters, phenols, and aldehydes may be generated from paints, inks, solvents, adhesives, synthetic resins, or chemicals.

[0003] Because exhaust gases containing such flammable, toxic, and malodorous components cannot be directly released into the atmosphere from a pollution prevention standpoint, they are released into the atmosphere only after being treated to render them harmless and odorless. To treat such exhaust gases, regenerative exhaust gas treatment devices are used that convert the flammable, toxic, and malodorous components in the exhaust gas into harmless and odorless substances through catalytic or direct combustion, while simultaneously recovering the heat generated and reusing it to heat the untreated exhaust gas.

[0004] Japanese Patent Publication No. 2000-274642 (Patent Document 1) proposes a thermal energy storage combustion deodorizer in which heating locations are dispersed and made uniform by installing a honeycomb heater in the heat storage layer in order to reduce fuel consumption. Japanese Patent Publication No. 9-262434 (Patent Document 2) and Japanese Patent Publication No. 10-99647 (Patent Document 3) propose a catalytic thermal energy storage deodorizer in which the combustion chamber temperature is lowered to 300°C to 500°C by installing a catalyst in the heat storage layer in order to suppress fuel consumption.

[0005] JP 2000-274642 JP 9-262434 JP 10-99647

[0006] However, when the concentration of the exhaust gas being treated fluctuates greatly, the temperature fluctuations in the combustion chamber also become large. This increases the load on the heating mechanism used to control the combustion chamber temperature, and tends to increase the fuel consumption of the burner and the power consumption of the electric heater.

[0007] While the thermal energy storage combustion deodorizer described in Patent Document 1 can improve the heating efficiency with exhaust gas, it cannot address the reduction in power consumption required for temperature control in response to fluctuations in exhaust gas concentration.

[0008] In the catalytic thermal deodorizing treatment apparatuses described in Patent Documents 2 and 3, it is difficult to combust and decompose exhaust gas using heat alone. Therefore, the exhaust gas must always come into contact with the catalyst. However, the treatment efficiency of the exhaust gas may decrease due to the effects of gaps between catalyst blocks that occur due to aging, or the partial deterioration of catalyst performance.

[0009] The purpose of this disclosure is to provide an exhaust gas treatment device and an exhaust gas treatment method that suppress increases in fuel consumption or power consumption due to fluctuations in exhaust gas concentration in a regenerative exhaust gas treatment device.

[0010] An exhaust gas treatment apparatus according to an embodiment of the present disclosure comprises a combustion chamber and a plurality of heat storage layers connected to the combustion chamber. In the exhaust gas treatment apparatus of the present disclosure, untreated exhaust gas is supplied to the combustion chamber by passing through at least one of the plurality of heat storage layers, treated, and then the treated exhaust gas is discharged by passing through at least one heat storage layer other than the one heat storage layer, and the supply direction of the untreated exhaust gas and the exhaust direction of the treated exhaust gas are alternately switched at predetermined intervals to perform exhaust gas treatment. The combustion chamber is equipped with a heating mechanism, and the temperature of the combustion chamber is maintained at 750°C or higher. The plurality of heat storage layers are equipped with a heat source in a region of 60% or more from the bottom in the height direction, and the temperature of the region of the plurality of heat storage layers in a region of 80% or more from the bottom in the height direction is maintained at a temperature 50°C or higher than the temperature of the combustion chamber.

[0011] An exhaust gas treatment method according to another embodiment of the present disclosure includes a first step of supplying untreated exhaust gas to a combustion chamber by passing it through a first heat storage layer, treating it, and then discharging the treated exhaust gas by passing it through a second heat storage layer; a switching step of switching the supply direction of untreated exhaust gas and the discharge direction of treated exhaust gas; and a second step of supplying untreated exhaust gas to a combustion chamber by passing it through a second heat storage layer, treating it, and then discharging the treated exhaust gas by passing it through the first heat storage layer. In the first and second steps, the temperature of the combustion chamber is maintained at 750°C or higher. A heat source is installed in the area of ​​the first and second heat storage layers at least 60% from the bottom in the height direction, and the temperature of the first heat storage layer in the first step and the area of ​​the second heat storage layer at least 80% from the bottom in the height direction is maintained at a temperature at least 50°C higher than the temperature of the combustion chamber.

[0012] According to this disclosure, it is possible to provide an exhaust gas treatment device and an exhaust gas treatment method that suppress the increase in fuel consumption or power consumption due to fluctuations in exhaust gas concentration in a regenerative exhaust gas treatment device.

[0013] Figure 1 is a schematic cross-sectional view of a regenerative exhaust gas treatment device. Figure 2 is a schematic cross-sectional view of a heat storage layer on which a heat source is installed. Figure 3 is a schematic cross-sectional view of a heat storage layer on which another heat source is installed. Figure 4 is a schematic cross-sectional view of a heat storage layer on which yet another heat source is installed. Figure 5 is a flow chart showing the exhaust gas treatment method. Figure 6 is a schematic cross-sectional view illustrating the position where thermocouples are attached to the heat storage layer in Comparative Example 1. Figure 7 is a schematic cross-sectional view illustrating the position where thermocouples are attached to the heat storage layer in Example 1. Figure 8 is a graph showing the temperature distribution inside the exhaust gas treatment device in Comparative Example 1. Figure 9 is a graph showing the temperature distribution inside the exhaust gas treatment device in Example 1. Figure 10 is a schematic cross-sectional view illustrating the position where thermocouples are attached to the heat storage layer in Comparative Example 2. Figure 11 is a schematic cross-sectional view illustrating the position where thermocouples are attached to the heat storage layer in Example 2. Figure 12 is a graph showing the temperature change inside the combustion chamber in Comparative Example 2. Figure 13 is a graph showing the temperature change inside the combustion chamber in Example 2.

[0014] <Exhaust Gas Treatment Device> The exhaust gas treatment device of this disclosure comprises a combustion chamber and a plurality of heat storage layers connected to the combustion chamber. In the exhaust gas treatment device of this disclosure, untreated exhaust gas is supplied to the combustion chamber by passing through at least one of the plurality of heat storage layers, treated, and then the treated exhaust gas is discharged by passing through at least one heat storage layer other than the one heat storage layer, and the supply direction of the untreated exhaust gas and the exhaust direction of the treated exhaust gas are alternately switched at predetermined intervals to perform exhaust gas treatment. The combustion chamber is equipped with a heating mechanism and the temperature of the combustion chamber is maintained at 750°C or higher. The plurality of heat storage layers are equipped with a heat source in a region of 60% or more from the bottom in the height direction, and the temperature of the region of the plurality of heat storage layers in a region of 80% or more from the bottom in the height direction is maintained at a temperature 50°C or higher than the temperature of the combustion chamber.

[0015] The exhaust gas treatment device of this disclosure may be a regenerative exhaust gas treatment device that burns and decomposes harmful components and malodorous components (hereinafter, when both harmful components and malodorous components are referred to, they may also be called harmful and malodorous components) contained in the exhaust gas to convert them into harmless and odorless substances, and recovers the combustion heat generated in the process for reuse in exhaust gas treatment.

[0016] The exhaust gas treated by the exhaust gas treatment device may be, for example, a gas containing volatile organic compounds (VOCs) and an ammonia-containing gas. The VOC-containing gas may be, for example, a hydrocarbon gas. Examples of hydrocarbon gases include gases containing at least one selected from the group consisting of aromatic hydrocarbon compounds, alcohol compounds, ketone compounds, aldehyde compounds, and carboxylic acid compounds. The concentration of harmful odor components in the exhaust gas (e.g., VOC concentration) is, for example, 400 to 2200 mg / Nm³. ３ It can vary within this range. According to this disclosure, even when exhaust gas concentrations fluctuate, it is possible to suppress increases in fuel consumption or electricity consumption required for exhaust gas treatment.

[0017] The structure of the exhaust gas treatment device can be that of a general regenerative exhaust gas treatment device. Figure 1 shows the structure of the exhaust gas treatment device. The exhaust gas treatment device 100 shown in Figure 1 is a regenerative exhaust gas treatment device. The exhaust gas treatment device 100 has a combustion chamber 101 equipped with a heating mechanism 105 that heats untreated exhaust gas to a predetermined temperature, and multiple heat storage chambers 106 are arranged in parallel to it. The heat storage chambers 106 are equipped with a heat storage layer 107 that stores heat when high-temperature treated exhaust gas is discharged and releases the stored heat when low-temperature untreated exhaust gas is supplied to preheat the untreated exhaust gas.

[0018] The exhaust gas treatment device 100 comprises buildings A and B. The exhaust gas treatment device 100 may have additional buildings in addition to buildings A and B. Buildings A and B are connected to each other via a combustion chamber 101. The exhaust gas treatment device 100 comprises a plurality of heat storage chambers 106. The exhaust gas treatment device 100 comprises two heat storage chambers 106. Buildings A and B comprise heat storage chamber 106A and heat storage chamber 106B. Heat storage chamber 106A and heat storage chamber 106B each comprise heat storage layers 107A and 107B. Untreated exhaust gas is supplied from the exhaust gas inlet 102 through the heat storage layer 107A to the combustion chamber 101, treated, and then the treated gas is discharged from the exhaust gas outlet 103 through the heat storage layer 107B. After the supply direction of untreated exhaust gas and the exhaust direction of treated exhaust gas are switched, the untreated exhaust gas is supplied from the exhaust gas inlet 102 through the heat storage layer 107B to the combustion chamber 101, where it is treated, and then the treated gas is discharged from the exhaust gas outlet 103 through the heat storage layer 107A.

[0019] The exhaust gas treatment device 100 may include three or more buildings, a heat storage chamber, and a heat storage layer. If the exhaust gas treatment device 100 includes three or more buildings, a heat storage chamber, and a heat storage layer, the switching of the supply direction of untreated exhaust gas and the exhaust direction of treated exhaust gas may be performed, for example, in a rotary manner.

[0020] Switching between the supply direction of untreated exhaust gas and the exhaust direction of treated exhaust gas is performed using dampers 108 installed at the exhaust gas inlet 102 and exhaust gas outlet 103. The dampers 108 are opened or closed at predetermined timings to alternately switch between the exhaust gas supply side and the exhaust gas discharge side. As a result, the heat from the treated exhaust gas is stored in another heat storage layer that the untreated exhaust gas supplied from the heat storage layer passes through after being treated in the combustion chamber. After the exhaust gas supply side and discharge side are switched, the untreated exhaust gas passes through the other heat storage layer with stored heat, and the untreated exhaust gas heated using the stored heat is supplied to the combustion chamber, thus performing exhaust gas purification treatment continuously and efficiently. The timing for switching between the supply direction of untreated exhaust gas and the exhaust direction of treated exhaust gas may be, for example, every 10 to 120 seconds, every 20 to 90 seconds, or every 30 to 60 seconds.

[0021] The heating mechanism 105 can be a heating mechanism capable of maintaining the temperature inside the combustion chamber 101 at 750°C or higher. Specific examples include burners and electric heaters. Since heat is generated during exhaust gas combustion in the device, the amount of heat generated constantly changes according to fluctuations in the concentration of the processed gas. Therefore, in exhaust gas treatment, the temperature of the combustion chamber 101 is measured by a thermocouple 104, and temperature control is performed by the heating mechanism 105 to maintain the temperature inside the combustion chamber 101 at a set value. Although not shown, the exhaust gas treatment device 100 may have a control unit configured to control the temperature inside the combustion chamber 101 to a set value. The temperature inside the combustion chamber 101 can be monitored by the thermocouple 104.

[0022] The time it takes for the untreated exhaust gas to pass through the heat storage chamber 106 and the combustion chamber 101 (the processing time for the untreated exhaust gas) may be, for example, 1 second or more, and may be 2 to 10 seconds.

[0023] The temperature of the untreated exhaust gas supplied from the exhaust gas inlet 102 to the heat storage layer 107 may be, for example, 10°C or higher, or 100°C or lower.

[0024] The heat storage layer 107 is equipped with a heat source in the region at least 60% from the bottom in the height direction. This makes it easier to maintain a temperature at least 50°C higher than the temperature of the combustion chamber 101 in the region at least 80% from the bottom in the height direction. As a result, the temperature of the untreated exhaust gas passing through the heat storage layer rises more easily, reducing temperature fluctuations in the combustion chamber even when there are large fluctuations in the concentration of the exhaust gas to be treated. This reduces the load on the heating mechanism used for temperature control in the combustion chamber, and makes it easier to suppress increases in fuel consumption or power consumption of the heating mechanism. In addition, heat is more easily stored in the heat storage layer when the treated exhaust gas passes through it and is discharged.

[0025] As shown in Figure 2, the heat storage layer 107 can be composed of a heat source 109 and a heat storage material 110. The heat source 109 is installed in a region of 60% or more from the bottom in the height direction (arrow y direction in the figure) from the bottom (0%) to the top (100%) of the heat storage layer 107. By providing a heat source in a region of 60% or more from the bottom in the height direction of the heat storage layer 107, it becomes easier to maintain a temperature of 50°C or more higher than the temperature inside the combustion chamber 101 in a region of 80% or more from the bottom in the height direction of the heat storage layer. From the viewpoint of the temperature rise of the untreated exhaust gas and the cost of the heat source, the heat source 109 is preferably installed in a region of 70% or more from the bottom in the height direction of the heat storage layer 107, more preferably in a region of 80% or more from the bottom, and even more preferably in a region of 83% or more. The heat source 109 may be installed in the entire region within the above range, or in only a part of the region within the above range.

[0026] The ratio of the dimensions of the heat source 109 in the height direction may be 40% or less when the height of the heat storage layer 107 is taken as 100%, preferably 30% or less, and more preferably 20% or less from the bottom, from the viewpoint of the temperature rise of the untreated exhaust gas and the cost of the heat source.

[0027] The heat source 109 may be installed in a region of the heat storage layer 107 that is, for example, 60% to 100% from the bottom, or 70% to 100%, or 80% to 100%, or 70% to 90%. By installing the heat source 109 within the above ranges, the cost of the heat source 109 can be reduced, and the temperature of the region of the heat storage layer that is 80% or more from the bottom in the height direction can be more easily maintained at a temperature 50°C or more higher than the temperature inside the combustion chamber 101.

[0028] The heat storage layer 107 is preferably maintained at a temperature at least 70°C higher than the temperature inside the combustion chamber 101 in the region at least 80% from the bottom in the height direction, and more preferably at a temperature at least 85°C higher than the temperature inside the combustion chamber 101. More specifically, the heat storage layer 107 can be maintained at a temperature at least 88°C higher than the temperature inside the combustion chamber 101 in the region at least 83% from the bottom in the height direction.

[0029] The heat storage layer 107 through which untreated exhaust gas passes can maintain a temperature of, for example, 800°C or higher in the region at least 60% from the bottom in the height direction. The temperature of the heat storage layer 107 can be maintained at, for example, 850°C or higher in the region at least 80% from the bottom in the height direction. The temperature of the heat storage layer 107 can be maintained at, for example, 880°C or higher in the region at least 83% from the bottom in the height direction. The temperature of the heat storage layer 107 can be measured, for example, by attaching thermocouples to the heat source 109 and heat storage material 110 that constitute the heat storage layer 107.

[0030] The heat storage layer 107 through which the untreated exhaust gas passes may have a temperature of, for example, 100°C or higher, or 120°C or lower, at the bottom (0%) of the heat storage layer 107.

[0031] The heat storage layer 107 through which the untreated exhaust gas passes may have a temperature of, for example, 100°C or higher, or 200°C or lower, in the region from the bottom 17% in the height direction.

[0032] The heat storage layer 107 through which the untreated exhaust gas passes may have a temperature of, for example, 500°C or higher, or 600°C or lower, in the lower 20% of the height region.

[0033] The heat storage layer 107 through which the untreated exhaust gas passes may have a temperature of, for example, 650°C or higher and 800°C or lower in the 40% region from the bottom in the height direction.

[0034] The heat storage layer 107 through which the untreated exhaust gas passes may have a temperature of, for example, 800°C or higher and 950°C or lower in the 60% region from the bottom in the height direction.

[0035] The heat storage layer 107 through which the untreated exhaust gas passes may have a temperature of, for example, 850°C or higher and 950°C or lower in the 80% region from the bottom in the height direction.

[0036] The heat storage layer 107 through which the untreated exhaust gas passes may have a temperature of, for example, 880°C or higher and 900°C or lower in the 83% region from the bottom in the height direction.

[0037] The heat source 109 does not need to be installed so as to contact all of the untreated exhaust gas passing through the heat storage layer 107. It may be installed at intervals so that the surrounding heat storage material is maintained at a temperature 50°C or higher than the temperature in the combustion chamber 101 by heat conduction. The heat source 109 may be installed in the whole or a part of the region of 80% or more and 100% or less from the bottom in the height direction of the heat storage layer 107. The heat source 109 is preferably installed dispersedly in the heat storage layer 107. For example, as shown in FIG. 3, the heat source 109 may be installed in stripes at regular intervals in the direction perpendicular to the height direction of the heat storage layer 107. For example, as shown in FIG. 4, the heat source 109 may be installed in a grid at regular intervals in the height direction and the direction perpendicular to the height direction of the heat storage layer 107.

[0038] As the heat source, for example, an electric heater, a burner, or the like can be used, but it is preferable to use the combustion heat of the exhaust gas as the heat source. When using the combustion heat of the exhaust gas as the heat source, for example, a heat storage layer provided with a catalyst material for promoting the combustion reaction, or a heat storage layer provided with a material having an increased gas contact area such as the number of cells or the surface shape of the heat storage material to promote the reaction can be used. Among them, it is preferable to use a heat storage layer provided with a catalyst material.

[0039] Examples of the catalyst material include a catalyst material containing a metal element that promotes the combustion of hydrocarbon-based gases. Examples of the metal element that promotes the combustion of hydrocarbon-based gases include transition metal elements and the like. Examples of the transition metal elements include manganese (Mn), cobalt (Co), iron (Fe), nickel (Ni), platinum (Pt), palladium (Pd), ruthenium (Ru), and the like. Among them, Mn, Co, Fe, and Ni are preferable. The heat source can include a catalyst material containing at least one element selected from the group consisting of Mn, Co, Fe, Ni, Pt, Pd, and Ru.

[0040] The catalyst material may, for example, contain a metal oxide. The catalyst material may be a metal oxide. Examples of the metal oxide include ZrO ２ , Al ２ O ３ , CeO ２ , Y ２ O ３ , MgO, and the like. Among them, ZrO ２ and Al ２ O ３ are preferable. The catalyst material can include at least one selected from the group consisting of ZrO ２ and Al ２ O ３ .

[0041] The catalyst material may include, for example, a metal composite oxide. Considering long-term use in environments above 750°C, the catalyst material is preferably a metal composite oxide. The metal composite oxide may be, for example, a metal composite oxide composed of two or more elements, such as the above-mentioned metal oxide and a transition metal element. From the viewpoint of long-term use in environments above 750°C, the metal composite oxide is preferably a perovskite-type metal composite oxide containing at least one element selected from the group consisting of barium (Ba), strontium (Sr), and calcium (Ca). Examples of perovskite-type metal composite oxides include a perovskite-type metal composite oxide composed of at least one element selected from the group consisting of Ba, Sr, and Ca, zirconium (Zr), and at least one element selected from the group consisting of Mn, Co, Fe, Ni, Pt, Pd, and Ru. A specific example is a perovskite-type metal composite oxide consisting of Ba-Zr-Mn.

[0042] The catalyst material can be installed in such an amount that the temperature of the heat storage layer 107 is maintained at a temperature at least 50°C higher than the combustion chamber temperature in the region from the bottom 80% or more in the height direction. The catalyst material can be installed by coating it with the heat storage material, incorporating it into the heat storage material, or replacing a part of the heat storage material. The catalyst material can be used, for example, as a honeycomb structure containing the catalyst material.

[0043] As the heat storage material 110, ceramics or the like are used from the viewpoint of heat exchange characteristics. Examples of ceramics include cordierite. The heat storage material 110 may be, for example, a honeycomb structure, or a cordierite honeycomb structure.

[0044] The treated exhaust gas processed in the combustion chamber 101 is discharged after passing through a different heat storage layer 107 than the one it passed through when it was supplied to the combustion chamber 101. Heat is stored in the heat storage material 110 as the treated exhaust gas passes through the heat storage layer 107. The temperature of the treated exhaust gas discharged from the exhaust gas outlet 103 may be, for example, 150°C or lower, or 100°C or lower.

[0045] <Exhaust Gas Treatment Method> The exhaust gas treatment method of this disclosure includes a first step of supplying untreated exhaust gas to a combustion chamber by passing it through a first heat storage layer, treating it, and then discharging the treated exhaust gas by passing it through a second heat storage layer; a switching step of switching the supply direction of untreated exhaust gas and the discharge direction of treated exhaust gas; and a second step of supplying untreated exhaust gas to a combustion chamber by passing it through a second heat storage layer, treating it, and then discharging the treated exhaust gas by passing it through the first heat storage layer. In the first and second steps, the temperature of the combustion chamber is maintained at 750°C or higher. A heat source is installed in the area of ​​the first heat storage layer and the second heat storage layer in the height direction, at least 60% from the bottom, to maintain the temperature of the area of ​​the first heat storage layer in the first step and the area of ​​the second heat storage layer in the second step in the height direction, at least 80% from the bottom, at a temperature at least 50°C higher than the temperature of the combustion chamber.

[0046] The exhaust gas treatment method will be explained with reference to Figure 5. The exhaust gas treatment method includes a first step S1 in which untreated exhaust gas is passed through a first heat storage layer and supplied to the combustion chamber for treatment, and then the treated exhaust gas is passed through a second heat storage layer and discharged; a switching step S2 in which the supply direction of untreated exhaust gas and the discharge direction of treated exhaust gas are switched; and a second step S3 in which untreated exhaust gas is passed through a second heat storage layer and supplied to the combustion chamber for treatment, and then the treated exhaust gas is passed through the first heat storage layer and discharged. The exhaust gas treatment method can be performed by repeatedly alternating between the first step S1 and the second step S3 by performing the switching step S2.

[0047] In the exhaust gas treatment method, in the first step S1, the untreated exhaust gas supplied from the first heat storage layer is decomposed in the combustion chamber and then passes through the second heat storage layer, where the heat of the untreated exhaust gas is stored. In the switching step S2, the supply side and discharge side of the exhaust gas are switched, so in the second step, the untreated exhaust gas passes through the second heat storage layer where the heat has been stored. As a result, the untreated exhaust gas heated using the stored heat is supplied to the combustion chamber, thus performing exhaust gas purification treatment continuously and efficiently.

[0048] The exhaust gas treatment method of this disclosure can be carried out using a general regenerative exhaust gas treatment device. The regenerative exhaust gas treatment device can be the exhaust gas treatment device of this disclosure. The description, examples, and preferred ranges of the exhaust gas treated by the exhaust gas treatment method, and the combustion chamber and heat source used in the exhaust gas treatment method, are the same as the description, examples, and preferred ranges of the exhaust gas treatment device described above. Furthermore, the description, examples, and preferred ranges of the heat storage layer in the exhaust gas treatment device described above apply to the first and second heat storage layers.

[0049] In the first step S1 and the second step S3, the temperature of the combustion chamber is maintained at 750°C or higher. The temperature of the combustion chamber can be maintained at 750°C or higher using the heating mechanism described above. The temperature of the combustion chamber can be maintained at a set value by controlling the heating mechanism while monitoring it, for example, using a thermocouple placed in the combustion chamber.

[0050] The time for passing the untreated exhaust gas through the heat storage chamber 106 and the combustion chamber 101 (the processing time for the untreated exhaust gas) may be, for example, 1 second or more, and may be 2 to 10 seconds.

[0051] The first and second heat storage layers may each be a single heat storage layer or multiple heat storage layers. The first and second heat storage layers may each be two or more heat storage layers or three or more heat storage layers. The first and second heat storage layers are each housed in separate heat storage chambers. When the first and second heat storage layers are multiple heat storage layers, in the switching process S2, the supply and discharge sides of all exhaust gases from the multiple heat storage layers may be switched, or the supply and discharge sides of some of the exhaust gases from the multiple heat storage layers may be switched.

[0052] The temperature of the untreated exhaust gas supplied to the first or second heat storage layer may be, for example, 10°C or higher, or 100°C or lower. The temperature of the treated exhaust gas discharged from the first or second heat storage layer may be, for example, 150°C or lower, or 100°C or lower.

[0053] By installing a heat source in the area of ​​the first and second heat storage layers at least 60% from the bottom in the height direction, the temperature of the area of ​​the first heat storage layer in the first process and the area of ​​the second heat storage layer in the second process at least 80% from the bottom in the height direction can be maintained at a temperature at least 50°C higher than the temperature of the combustion chamber. In other words, the temperature of the area of ​​the first and second heat storage layers at least 80% from the bottom in the height direction when untreated exhaust gas is passed through can be maintained at a temperature at least 50°C higher than the temperature of the combustion chamber. As a result, the temperature of the untreated exhaust gas passing through the first and second heat storage layers rises more easily, and even when there are large fluctuations in the concentration of the exhaust gas being treated, the temperature fluctuation in the combustion chamber becomes smaller, the load on the heating mechanism used for temperature control in the combustion chamber is reduced, and the increase in fuel consumption or power consumption of the heating mechanism is more easily suppressed. In addition, when the treated exhaust gas passes through the heat storage layers and is discharged, heat is more easily stored in the heat storage layers.

[0054] The heat source is preferably installed in the region 70% or higher from the bottom, more preferably in the region 80% or higher from the bottom, and even more preferably in the region 83% or higher from the bottom, in the height direction of the first and second heat storage layers, from the viewpoint of the temperature rise of the untreated exhaust gas and the cost of the heat source.

[0055] The ratio of the dimensions of the heat source in the height direction may be 40% or less when the height of the first heat storage layer and the second heat storage layer are set to 100%, preferably 30% or less, and more preferably 20% or less from the bottom, from the viewpoint of the temperature rise of the untreated exhaust gas and the cost of the heat source.

[0056] The heat source may be installed in the region between 60% and 100% from the bottom in the height direction of the first and second heat storage layers, or in the region between 70% and 100%, or in the region between 80% and 100%, or in the region between 70% and 90%. By installing the heat source within the above range, the cost of the heat source can be reduced, and the temperature in the region above 80% from the bottom in the height direction of the heat storage layers can be more easily maintained at a temperature at least 50°C higher than the temperature of the combustion chamber.

[0057] In the first step, the temperature of the first heat storage layer and in the second step, the temperature of the region from the bottom 80% or more in the height direction is preferably maintained at a temperature 70°C or more higher than the temperature of the combustion chamber, and more preferably at a temperature 85°C or more higher than the temperature of the combustion chamber. More specifically, the temperature of the region from the bottom 83% or more in the height direction of the first heat storage layer and in the second step, the temperature of the combustion chamber can be maintained at a temperature 88°C or more higher than the temperature of the combustion chamber.

[0058] The temperature of the region from the bottom 60% or more in the height direction of the first heat storage layer in the first process and the second heat storage layer in the second process can be maintained at, for example, 800°C or higher. The temperature of the region from the bottom 80% or more in the height direction of the first heat storage layer in the first process and the second heat storage layer in the second process can be maintained at, for example, 850°C or higher. The temperature of the region from the bottom 83% or more in the height direction of the first heat storage layer in the first process and the second heat storage layer in the second process can be maintained at, for example, 880°C or higher.

[0059] The temperature of the lower part (0%) of the first heat storage layer in the first process and the second heat storage layer in the second process may be, for example, 100°C or higher, or 120°C or lower.

[0060] The temperature of the region in the lower 17% of the height direction of the first heat storage layer in the first process and the second heat storage layer in the second process may be, for example, 100°C or higher and 200°C or lower.

[0061] The temperature of the region in the lower 20% of the height direction of the first heat storage layer in the first process and the second heat storage layer in the second process may be, for example, 500°C or higher and 600°C or lower.

[0062] The temperature of the first heat storage layer in the first process and the second heat storage layer in the second process, in the region from the bottom 40% in the height direction, may be, for example, 650°C or higher and 800°C or lower.

[0063] The temperature of the first heat storage layer in the first process and the second heat storage layer in the second process, in the region from the bottom 60% in the height direction, may be, for example, 800°C or higher and 950°C or lower.

[0064] The temperature of the first heat storage layer in the first process and the second heat storage layer in the second process, in the area from the bottom 80% in the height direction, may be, for example, 850°C or higher and 950°C or lower.

[0065] In the first step, the temperature of the first heat storage layer and in the second step, the temperature of the region from the bottom 83% in the height direction of the second heat storage layer may be, for example, 880°C or higher and 900°C or lower.

[0066] In switching step S2, the timing for switching the supply direction of untreated exhaust gas and the exhaust direction of treated exhaust gas may be, for example, every 10 to 120 seconds, every 20 to 90 seconds, or every 30 to 60 seconds. The switching of the supply direction of untreated exhaust gas and the exhaust direction of treated exhaust gas can be performed using dampers installed at the exhaust gas inlet and exhaust gas outlet connected to the heat storage layer.

[0067] The present invention will be described in more detail below with reference to examples.

[0068] <Comparative Example 1> A regenerative exhaust gas treatment device having the structure of the exhaust gas treatment device 100 shown in Figure 1 was used as the device for treating exhaust gas. The regenerative exhaust gas treatment device comprises building A and building B. Building A and building B each comprise a first heat storage layer and a second heat storage layer. The first and second heat storage layers used were heat storage layers without a heat source. The heat storage material constituting the first and second heat storage layers was made of cordierite honeycomb. 0.41 m ３ A heat storage material measuring 0.45 m wide x 1.20 m deep x 0.75 m high was installed. As shown in Figure 6, thermocouples for temperature measurement were installed in the first and second heat storage layers 201 at points 80%, 60%, 40%, and 20% from the bottom (referred to as heat storage layer A, heat storage layer B, heat storage layer C, and heat storage layer D, respectively) in the height direction from the bottom (0%) to the top (100%) of the first and second heat storage layers 201, and the temperature inside the heat storage layers was measured. Thermocouples were also installed at the bottom of the first and second heat storage layers to measure the temperature.

[0069] First, toluene-added air was supplied to the first heat storage layer from the exhaust gas inlet on the A building side. The gas flow rate was 40 Nm³. ３The gas was supplied as / min from the exhaust gas inlet of the device, and the temperature inside the combustion chamber was controlled to 800°C by a burner installed in the combustion chamber. The switching cycle of the gas flow path damper was set to 30 seconds, and during the test, the toluene concentration at the exhaust gas inlet and exhaust gas outlet was measured to confirm that more than 94% of the toluene was being decomposed at all times. Tests were conducted at two levels of toluene concentration: low concentration (toluene concentration: 114 ppm) and high concentration (toluene concentration: 286 ppm), and the temperature from the combustion chamber to the first heat storage layer was measured for 30 minutes in each case.

[0070] <Example 1> In Comparative Example 1, as shown in Figure 7, the upper 0.1 m above the first and second heat storage layers 201 ３ The test operation was performed under the same conditions as in Comparative Example 1, except that the first and second heat storage layers 202 were used, in which the heat storage material (above the 87% mark from the bottom in the height direction) was removed and replaced with a honeycomb catalyst of the same volume. As the catalyst, a composite oxide catalyst with a perovskite structure consisting of Ba-Zr-Mn was applied to a cordierite honeycomb. Furthermore, since the catalyst has heat resistance up to 1000°C, the reaction acceleration performance does not deteriorate due to heat during the test.

[0071] Figures 8 and 9 show the measurement results of the temperature distribution inside the device. Table 1 shows the temperature difference between the heat storage layer A and the combustion chamber (heat storage layer A temperature - combustion chamber temperature), and the temperature change of the combustion chamber under low concentration conditions and high concentration conditions (absolute value of the difference between the combustion chamber temperature under low concentration conditions and the combustion chamber temperature under high concentration conditions).

[0072] As shown in Figure 8, the temperature of heat storage layer A in Comparative Example 1 is the same as or lower than that of the combustion chamber, and the temperature of the heat storage layer tends to decrease as it moves away from the combustion chamber. The temperature of heat storage layer B is maintained at 750°C or higher under low concentration conditions, but drops to below 750°C under high concentration conditions, which may shorten the time that the exhaust gas remains in the combustion zone above 750°C.

[0073] On the other hand, as shown in Figure 9, the temperature of the heat storage layer A in Example 1 is more than 50°C higher than that of the combustion chamber, and even considering the temperature change cycle of about 30°C associated with the switching of the gas flow path damper, it always maintains a higher temperature than that of the combustion chamber. Furthermore, even the lower heat storage layer B maintains a temperature of 800°C or higher, which increases the time that the exhaust gas remains in the combustion zone above 750°C.

[0074]

[0075] As shown in Table 1, in Example 1, where the temperature of the heat storage layer A is 50°C or higher than that of the combustion chamber, fluctuations in the combustion chamber temperature when the gas concentration changes can be reduced. Compared to Comparative Example 1, in Example 1, where the temperature of the heat storage layer A (at 80% from the bottom in the height direction) is kept higher than that of the combustion chamber temperature, it is possible to suppress changes in the combustion chamber temperature when the exhaust gas concentration is high and when it is low. Therefore, even when the exhaust gas concentration fluctuates during actual operation, it is possible to reduce the energy consumption of the heating mechanism used to maintain the temperature inside the combustion chamber.

[0076] Furthermore, as is clear from the temperature graphs shown in Figures 8 and 9, in Example 1, compared to Comparative Example 1, heat is also stored in the heat storage material below the installed catalyst, increasing the amount of heat stored in the heat storage layer. As a result, fluctuations in the amount of heat generated inside the device due to concentration fluctuations are absorbed by the heat storage layer, reducing temperature fluctuations in the combustion chamber. Moreover, in Example 1, the heat storage layer B adjacent to the catalyst maintains a temperature of 800°C or higher, so the time that the exhaust gas remains in the combustion zone above 750°C is longer compared to the operating method of Comparative Example 1, making it possible to treat the exhaust gas more reliably.

[0077] Furthermore, as shown in Example 1, the rise in temperature of the heat storage layer extends to the area surrounding the catalyst, which is the heating means. Therefore, even if the catalysts are installed with gaps between them, as shown in Figures 3 and 4, the adjacent heat storage material also becomes hot. This similarly reduces temperature fluctuations in the combustion chamber, suppresses combustion consumption, and allows the exhaust gas to remain in the combustion zone above 750°C for a longer period, thus ensuring that the exhaust gas is reliably thermally decomposed.

[0078] <Comparative Example 2> Exhaust gas treatment was performed using a regenerative exhaust gas treatment device with the structure shown in Figure 1, in which exhaust gases from multiple facilities in a factory emitting hydrocarbon exhaust gases consisting of alcohols and esters are centrally connected. The first heat storage layer in Building A and the second heat storage layer in Building B each had a length of 8.9 m ３ The structure is filled with a cordierite honeycomb heat storage material. As shown in Figure 10, thermocouples for temperature measurement were installed at 17% and 83% points from the bottom (referred to as heat storage layer X and heat storage layer Y, respectively) in the height direction from the bottom (0%) to the top (100%) of the first and second heat storage layers 301, and the temperature inside the heat storage layers was measured.

[0079] The exhaust gas concentration constantly fluctuates depending on the operating status of the factory equipment, with a gas airflow of approximately 800 Nm³. ３ The device is supplied with LNG at a rate of / min from the exhaust gas inlet. The combustion chamber temperature was set to 800°C, and the combustion chamber temperature was maintained at the set temperature using an LNG burner installed in the combustion chamber. The gas flow path damper was operated with a switching cycle of 42 seconds. During the test, the VOC concentration at the outlet was measured periodically to confirm that an exhaust gas decomposition rate of 98% or higher was always maintained.

[0080] <Example 2> In Comparative Example 2, as shown in Figure 11, the upper 1.49 m above the first and second heat storage layers 301 ３ Exhaust gas treatment was performed under the same conditions as in Comparative Example 2, except that the first and second heat storage layers 302 were modified by removing the heat storage material (above the 83% point in the height direction) and replacing it with a honeycomb catalyst of the same volume. As with Example 1, a composite oxide catalyst with a perovskite structure consisting of Ba-Zr-Mn was used as the catalyst, coated onto a cordierite honeycomb. Furthermore, since this catalyst has heat resistance up to 1000°C, its reaction acceleration performance does not deteriorate due to heat during the test.

[0081] Figures 12 and 13 show the temperature changes during exhaust gas treatment, and Table 2 shows the average temperature over 100 minutes. Table 2 also shows the difference between the heat storage layer X and the combustion chamber temperature, as well as the temperature fluctuation (difference between maximum and minimum values) of the combustion chamber temperature over 100 minutes.

[0082]

[0083] As shown in Figure 12, in Comparative Example 2, the temperatures of the heat storage layer and combustion chamber constantly fluctuate due to the reversal of airflow direction associated with the switching of the gas flow path damper and fluctuations in exhaust gas concentration. Focusing on the temperature of the heat storage layer X, although it temporarily exceeds the temperature of the combustion chamber due to temperature fluctuations, the average temperature over 100 minutes is -13°C relative to the combustion chamber, as shown in Table 2. This trend is the same on the B side, where the temperature of the heat storage layer X was -31°C relative to the combustion chamber. In addition, the temperature fluctuation (difference between the maximum and minimum values) of the combustion chamber over 100 minutes was 133°C for both the A and B buildings.

[0084] On the other hand, as shown in Figure 13, although temperature fluctuations existed in Example 2 as well, the temperature of the heat storage layer X consistently remained higher than the combustion chamber temperature, and as shown in Table 2, the average temperature over 100 minutes was 88°C relative to the combustion chamber. This trend was the same in Building B, where the temperature of the heat storage layer X was 96°C relative to the combustion chamber. Furthermore, the temperature fluctuation (difference between maximum and minimum values) of the combustion chamber over 100 minutes was 33°C in Building A and 37°C in Building B.

[0085] Compared to Comparative Example 2, Example 2, in which the temperature of the heat storage layer X (located at 83% from the bottom in the height direction) has a higher temperature distribution relative to the combustion chamber temperature, makes it possible to suppress changes in combustion chamber temperature due to fluctuations in exhaust gas concentration during operation. Therefore, it is possible to reduce the frequency and amount of heat input from the burner, which is used to control the temperature inside the combustion chamber when the temperature drops, thereby reducing energy consumption during exhaust gas treatment.

[0086] Table 3 shows the fuel consumption of the LNG burner, the average value of the exhaust gas inlet temperature, and the average value of the exhaust gas outlet temperature of the device, obtained from the 24-hour operating data of Comparative Example 2 and Example 2.

[0087]

[0088] The amount of LNG burner fuel consumed during 24 hours of operation was 287 Nm³ in Comparative Example 2. ３ In contrast, in Example 2, the torque was 141 Nm ３ This represents a reduction in fuel consumption, and according to this disclosure, it is possible to reduce burner fuel consumption by approximately 50%.

[0089] Furthermore, the outlet gas temperature was reduced to 71°C in Example 2 compared to 103°C in Comparative Example 2. This confirms that, according to this disclosure, the heat discharged outside the device is reduced and the thermal efficiency is improved.

[0090] Comparing the temperatures of the heat storage layer Y shown in Table 2, the temperature in Example 2 is more than 100°C lower than that in Comparative Example 2. Therefore, it is thought that when the temperature of the upper part of the heat storage layer is maintained at a high temperature as in Example 2, the combustion heat is trapped in the upper part, which can lower the temperature of the lower part. This is expected to lower the temperature of the outlet gas and improve the thermal efficiency of the device.

[0091] Furthermore, in Example 2, the time the exhaust gas spends passing through the temperature range of 750°C or higher is longer compared to Comparative Example 2, making it possible to more reliably promote the thermal decomposition of the exhaust gas.

[0092] In the description of the embodiments described above, the combinable configurations may be combined with each other.

[0093] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope of equivalents of the claims are intended.

[0094] 100 Exhaust gas treatment device, 101 Combustion chamber, 102 Exhaust gas inlet, 103 Exhaust gas outlet, 104 Thermocouple, 105 Heating mechanism, 106, 106A, 106B Heat storage chamber, 107, 107A, 107B Heat storage layer, 108 Damper, 109 Heat source, 110 Heat storage material, 201, 202, 301, 302 First and second heat storage layers.

Claims

1. An exhaust gas treatment apparatus comprising a combustion chamber and a plurality of heat storage layers connected to the combustion chamber, wherein untreated exhaust gas is supplied to the combustion chamber by passing through at least one of the plurality of heat storage layers, treated, and then discharged by passing through at least one heat storage layer other than the at least one heat storage layer, and the supply direction of the untreated exhaust gas and the exhaust direction of the treated exhaust gas are alternately switched at predetermined intervals to perform exhaust gas treatment, wherein the combustion chamber is equipped with a heating mechanism and the temperature of the combustion chamber is maintained at 750°C or higher, and the plurality of heat storage layers are equipped with heat sources in a region of 60% or more from the bottom in the height direction, and the temperature of a region of 80% or more from the bottom in the height direction is maintained at a temperature 50°C or higher than the temperature of the combustion chamber.

2. The exhaust gas treatment apparatus according to claim 1, wherein the heat source is installed in a region of 83% or more from the bottom in the height direction of the heat storage layer.

3. The exhaust gas treatment apparatus according to claim 1 or 2, wherein the temperature of the region from the bottom 83% or more in the height direction of the plurality of heat storage layers is maintained at a temperature 85°C or higher than the temperature of the combustion chamber.

4. The exhaust gas treatment apparatus according to any one of claims 1 to 3, wherein the heat source includes a catalyst material containing at least one element selected from the group consisting of manganese, cobalt, iron, nickel, platinum, palladium, and ruthenium.

5. The catalyst material is ZrO ２ and Al ２ O ３ The exhaust gas treatment apparatus according to claim 4, comprising at least one metal oxide selected from the group consisting of the following.

6. The exhaust gas treatment apparatus according to claim 4 or 5, wherein the catalyst material comprises a metal composite oxide having a perovskite structure containing at least one element selected from the group consisting of barium, strontium, and calcium.

7. The exhaust gas treatment apparatus according to any one of claims 4 to 6, wherein the catalyst material is dispersed in the plurality of heat storage layers.

8. A method for treating exhaust gas, comprising: a first step of supplying untreated exhaust gas to a combustion chamber by passing it through a first heat storage layer, treating it, and then discharging the treated exhaust gas by passing it through a second heat storage layer; a switching step of switching the supply direction of the untreated exhaust gas and the discharge direction of the treated exhaust gas; and a second step of supplying untreated exhaust gas to a combustion chamber by passing it through the second heat storage layer, treating it, and then discharging the treated exhaust gas by passing it through the first heat storage layer, wherein in the first and second steps, the temperature of the combustion chamber is maintained at 750°C or higher, and a heat source is installed in the area of ​​the first and second heat storage layers at least 60% from the bottom in the height direction, thereby maintaining the temperature of the first heat storage layer in the first step and the area of ​​the second heat storage layer at least 80% from the bottom in the height direction at 50°C or higher than the temperature of the combustion chamber.

9. The exhaust gas treatment method according to claim 8, wherein the temperature of the region from the bottom 83% or more in the height direction of the first heat storage layer in the first step and the second heat storage layer in the second step is maintained at a temperature 85°C or higher than the temperature of the combustion chamber.

10. The exhaust gas treatment method according to claim 8 or 9, wherein the temperature of the region from the bottom 60% or more in the height direction of the first heat storage layer in the first step and the second heat storage layer in the second step is maintained at 800°C or higher.

11. The exhaust gas treatment method according to any one of claims 8 to 10, wherein the heat source is installed in an area of ​​83% or more from the bottom in the height direction of the first heat storage layer and the second heat storage layer.

12. The exhaust gas treatment method according to any one of claims 8 to 11, wherein the heat source includes a catalyst material containing at least one element selected from the group consisting of manganese, cobalt, iron, nickel, platinum, palladium, and ruthenium.

13. The catalyst material is ZrO ２ and Al ２ O ３ The exhaust gas treatment method according to claim 12, comprising at least one metal oxide selected from the group consisting of the following.

14. The exhaust gas treatment method according to claim 12 or 13, wherein the catalyst material comprises a metal composite oxide having a perovskite structure containing at least one element selected from the group consisting of barium, strontium, and calcium.

15. The exhaust gas treatment method according to any one of claims 12 to 14, wherein the catalyst material is dispersed in the first heat storage layer and the second heat storage layer.

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