Regenerative exhaust gas treatment device and exhaust gas treatment method

Abstract

The present invention provides a regenerative exhaust gas treatment device and exhaust gas treatment method that can reduce carbon dioxide emissions. [Solution] The regenerative exhaust gas treatment device 100 according to this disclosure has a combustion chamber 1, a plurality of heat storage chambers 2, a gas to be treated supply passage P1, and an exhaust passage P2. A burner 3 is installed in the combustion chamber 1. A heat storage body 21 is housed in each of the plurality of heat storage chambers 2. Each of the plurality of heat storage chambers 2 communicates with the combustion chamber 1. The gas to be treated supply passage P1 guides the gas to be treated to the combustion chamber 1 via at least a portion of the plurality of heat storage chambers 2. The exhaust passage P2 exhausts the gas to be treated, which has been combusted using the burner 3, to the outside of the combustion chamber 1 via at least a portion of the plurality of heat storage chambers 2. The burner 3 uses ammonia as fuel.

Description

Technical Field

[0001] The present disclosure relates to a regenerative exhaust gas treatment device and an exhaust gas treatment method.

Background Art

[0002] In production factories that perform painting, printing, adhesion, cleaning, etc., volatile organic solvents are used in paints, inks, adhesives, cleaning liquids, etc. Toxic gases such as toluene and xylene are discharged as exhaust gas from the equipment (dryer) for drying this volatile organic solvent. As equipment for detoxifying (rendering harmless) toxic gases, there is a regenerative exhaust gas treatment device (RTO: Regenerative Thermal Oxidizer). Note that RTO is also referred to as a regenerative deodorization device.

[0003] Japanese Patent Laid-Open No. 9-269115 (Patent Document 1) describes an RTO having a heating chamber and a combustion burner. According to this RTO, the exhaust gas introduced into the heating chamber is thermally decomposed and detoxified by being heated using the combustion burner.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Normally, hydrocarbon-based fuel is used as the fuel for the burner of the RTO. In this case, carbon dioxide (CO2) generated by the combustion of the hydrocarbon-based fuel is discharged from the RTO.

[0006] The present disclosure has been made in view of the above problems, and an object thereof is to provide a regenerative exhaust gas treatment device and an exhaust gas treatment method capable of reducing the amount of carbon dioxide emissions.

Means for Solving the Problems

[0007] The regenerative exhaust gas treatment device according to this disclosure comprises a combustion chamber, a plurality of heat storage chambers, a gas to be treated supply passage, and an exhaust passage. A burner is installed in the combustion chamber. A heat storage body is housed in each of the plurality of heat storage chambers. Each of the plurality of heat storage chambers communicates with the combustion chamber. The gas to be treated supply passage guides the gas to be treated into the combustion chamber via at least a portion of the plurality of heat storage chambers. The exhaust passage exhausts the gas to be treated, which has been combusted using the burner, to the outside of the combustion chamber via at least a portion of the plurality of heat storage chambers. The burner uses ammonia as fuel. [Effects of the Invention]

[0008] According to this disclosure, it is possible to provide a regenerative exhaust gas treatment device and exhaust gas treatment method that can reduce carbon dioxide emissions. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram showing the configuration of a thermal energy storage exhaust gas treatment device according to this embodiment. [Figure 2] This is an enlarged schematic diagram showing the configuration of the thermal energy storage exhaust gas treatment device according to this embodiment. [Figure 3] This is a schematic cross-sectional view showing the configuration of the burner and burner tile. [Figure 4] This is a schematic cross-sectional view along line IV-IV in Figure 3. [Figure 5] This is a block diagram showing the configuration of a thermal energy regenerative exhaust gas treatment device according to this embodiment. [Figure 6] This is a schematic flowchart illustrating the exhaust gas treatment method according to this embodiment. [Figure 7] This is the first schematic diagram illustrating the exhaust gas treatment method. [Figure 8] This is the second schematic diagram illustrating the exhaust gas treatment method. [Figure 9] This is an enlarged schematic diagram illustrating combustion in a combustion chamber. [Figure 10]This is the third schematic diagram illustrating the control method based on sensor measurements. [Modes for carrying out the invention]

[0010] Hereinafter, embodiments of the present disclosure (hereinafter also referred to as "these embodiments") will be described based on the drawings. In the following drawings, identical or corresponding parts will be given the same reference numerals, and their descriptions will not be repeated.

[0011] (Regenerative exhaust gas treatment system) First, the configuration of the regenerative exhaust gas treatment device 100 according to this embodiment will be described. Hereinafter, the regenerative exhaust gas treatment device 100 will also be referred to as RTO100. As shown in Figure 1, the RTO100 mainly consists of a combustion chamber 1, a plurality of heat storage chambers 2, a burner 3, a gas to be treated supply passage P1, an exhaust passage P2, a fuel supply passage P3, an air supply passage P4, and an exhaust tower 4.

[0012] The combustion chamber 1 is the part where the gas to be treated is combusted. Each of the multiple heat storage chambers 2 is in communication with the combustion chamber 1. The number of heat storage chambers 2 is not particularly limited, but in this embodiment, there are two heat storage chambers 2. The multiple heat storage chambers 2 include a first heat storage chamber 2a and a second heat storage chamber 2b. Each of the multiple heat storage chambers 2 houses a heat storage body 21.

[0013] The heat storage body 21 is constructed by stacking multiple heat storage materials, for example, made of ceramic and having a honeycomb structure. The heat storage body 21 may also be constructed by stacking spherical heat storage materials made of ceramic or metal, or by bundling multiple pipes made of ceramic or metal.

[0014] The burner 3 is attached to the combustion chamber 1. Specifically, the burner 3 is attached to the combustion chamber 1 so as to be able to generate a flame. The fuel supply flow path P3 is connected to the burner 3. The fuel supply flow path P3 supplies ammonia (NH3) to the burner 3. In other words, the burner 3 uses ammonia as fuel. Specifically, the burner 3 uses, for example, gaseous ammonia as fuel. The air supply flow path P4 is connected to the burner 3. The air supply flow path P4 supplies combustion air (Air) to the burner 3.

[0015] The process gas supply flow path P1 is connected to each of the plurality of regenerators 2. The process gas supply flow path P1 branches downstream of the first branch point B1. The process gas supply flow path P1 has a portion connecting the first branch point B1 and the first regenerator 2a and a portion connecting the first branch point B1 and the second regenerator 2b.

[0016] For example, a blower V is provided upstream of the first branch point B1. The blower V supplies the process gas to the process gas supply flow path P_{1}. The process gas supply flow path P1 guides the process gas to the combustion chamber 1 through at least a part of the plurality of regenerators 2.

[0017] The exhaust flow path P2 is connected to each of the plurality of regenerators 2. The exhaust flow path P2 branches upstream of the second branch point B2. The exhaust flow path P2 has a portion connecting the second branch point B2 and the first regenerator 2a and a portion connecting the second branch point B2 and the second regenerator 2b.

[0018] The exhaust flow path P2 exhausts the processed process gas (hereinafter also referred to as the purified gas) to the outside of the combustion chamber 1 through at least a part of the plurality of regenerators 2. The exhaust flow path P2 is connected to the exhaust tower 4. The exhaust tower 4 is provided downstream of the second branch point B2. The exhaust tower 4 dissipates the purified gas flowing in from the exhaust flow path P2 into the atmosphere.

[0019] The RTO100 includes a fuel valve 91, an air valve 92, a first gas valve 71, a second gas valve 72, a first exhaust valve 81, and a second exhaust valve 82. The fuel valve 91 is located in the fuel supply passage P3. The fuel valve 91 controls the opening and closing and degree of opening of the fuel supply passage P3. The air valve 92 is located in the air supply passage P4. The air valve 92 controls the opening and closing and degree of opening of the air supply passage P4.

[0020] The first gas valve 71 and the second gas valve 72 are each provided in the gas supply flow path P1 to be treated. The first gas valve 71 is provided between the first branching point B1 and the first heat storage chamber 2a. The first gas valve 71 opens and closes the flow path between the first branching point B1 and the first heat storage chamber 2a. The second gas valve 72 is provided between the first branching point B1 and the second heat storage chamber 2b. The second gas valve 72 opens and closes the flow path between the first branching point B1 and the second heat storage chamber 2b.

[0021] The first exhaust valve 81 and the second exhaust valve 82 are each provided in the exhaust flow path P2. The first exhaust valve 81 is provided between the second branching point B2 and the first heat storage chamber 2a. The first exhaust valve 81 opens and closes the flow path between the second branching point B2 and the first heat storage chamber 2a. The second exhaust valve 82 is provided between the second branching point B2 and the second heat storage chamber 2b. The second exhaust valve 82 opens and closes the flow path between the second branching point B2 and the second heat storage chamber 2b.

[0022] As shown in Figure 2, the RTO 100 has a wall 5. The wall 5 forms a combustion chamber 1 and a plurality of heat storage chambers 2. A burner 3 is mounted on the wall 5. The burner 3 has an opening 31. The opening 31 opens toward the combustion chamber 1.

[0023] The combustion chamber 1 has a main combustion space 11 and a secondary combustion space 12. The main combustion space 11 is in communication with each of the multiple heat storage chambers 2. The secondary combustion space 12 connects the main combustion space 11 to the opening 31. From another perspective, the secondary combustion space 12 is located between the main combustion space 11 and the burner 3. The main combustion space 11 is located between each of the multiple heat storage chambers 2 and the secondary combustion space 12.

[0024] The sub-combustion space 12 has a stepped shape in which its width increases as it moves away from the burner 3 along the opening direction 101 of the opening 31. Specifically, the sub-combustion space 12 is composed of a first portion 13 and a second portion 14. The first portion 13 is in communication with the opening 31. When viewed in the opening direction 101, the outer edge of the first portion 13 is, for example, circular. The central axis C of the burner 3 passes through the first portion 13. The central axis of the first portion 13 may coincide with the central axis C of the burner 3.

[0025] The second part 14 is located in the opening direction 101 relative to the first part 13. The first part 13 is located between the second part 14 and the opening 31. The second part 14 connects the first part 13 and the main combustion space 11. From another perspective, the second part 14 is provided between the first part 13 and the main combustion space 11. When viewed in the opening direction 101, the outer edge of the second part 14 is, for example, circular. The central axis C of the burner 3 passes through the second part 14. The central axis of the second part 14 may coincide with the central axis C of the burner 3.

[0026] The sub-combustion space 12 is formed by the inner circumferential surface 16 of the wall. The inner circumferential surface 16 of the wall has a first inner circumferential surface portion 16a and a second inner circumferential surface portion 16b. The first inner circumferential surface portion 16a is the inner circumferential surface of the first portion 13. The second inner circumferential surface portion 16b is the inner circumferential surface of the second portion 14. Each of the first inner circumferential surface portion 16a and the second inner circumferential surface portion 16b surrounds the central axis C. The area of ​​the second inner circumferential surface portion 16b is larger than the area of ​​the first inner circumferential surface portion 16a. A step 15 is provided in the sub-combustion space 12. The surface of the step 15 connects the first inner circumferential surface portion 16a and the second inner circumferential surface portion 16b.

[0027] The width of the first portion 13 in the direction perpendicular to the opening direction 101 of the opening 31 is defined as the first width H1. The first width H1 is, for example, the diameter of the first portion 13 when viewed in the opening direction 101. If the outer edge of the first portion 13 is not circular when viewed in the opening direction 101, the first width H1 is defined as the diameter of the inscribed circle of the outer edge of the first portion 13.

[0028] The width of the second portion 14 in the direction perpendicular to the opening direction 101 of the opening 31 is defined as the second width H2. The second width H2 is, for example, the diameter of the second portion 14 when viewed in the opening direction 101. If the outer edge of the second portion 14 is not circular when viewed in the opening direction 101, the second width H2 is defined as the diameter of the inscribed circle of the outer edge of the second portion 14.

[0029] The value obtained by dividing the second width H2 by the first width H1 should be between 1.2 and 2.0, based on experimental results, in order to maintain a good combustion state. The value obtained by dividing the second width H2 by the first width H1 may preferably be between 1.25 and 1.9, and more preferably between 1.3 and 1.8. In addition, in order to maintain a good combustion state, the value obtained by dividing the first width H1 by the inner diameter of the opening 31 should be, for example, between 1.0 and 3.0.

[0030] The value obtained by dividing the depth of the first portion 13 in the opening direction 101 (first depth D1) by the first width H1 should be between 0.3 and 0.8 in order to maintain a good combustion state. Similarly, the depth of the second portion 14 in the opening direction 101 (second depth D2) should be deeper than the first depth D1, and the value obtained by dividing the second depth D2 by the second width H2 should be between 0.8 and 1.2.

[0031] As shown in Figure 3, the RTO 100 has a burner tile 6. The burner tile 6 constitutes the sub-combustion space 12. The burner tile 6 is attached to the wall 5 (see Figure 2). For the sake of explanation, the burner tile 6 and the wall 5 are shown as a single unit in Figure 2.

[0032] The burner 3 is mounted on the burner tile 6. The burner 3 has, for example, a fuel supply pipe 30, a first air supply pipe 40, a second air supply pipe 50, and a third air supply pipe 60. The fuel supply pipe 30 extends along the central axis C. The fuel supply pipe 30 surrounds the central axis C. The fuel supply pipe 30 guides ammonia. For example, a first nozzle 39 is provided at the front end of the fuel supply pipe 30. The first nozzle 39 ejects ammonia. The first nozzle 39 opens, for example, toward the opening direction 101.

[0033] The first air supply pipe 40 guides combustion air (Air) towards the opening direction 101 while swirling around the fuel supply pipe 30. The first air supply pipe 40 has a first main section 41 and a first introduction section 42.

[0034] The first main section 41 surrounds the fuel supply pipe 30. A second nozzle 49 is provided at the front end of the first main section 41. The second nozzle 49 is located 101 degrees in the opening direction relative to the first nozzle 39. From another perspective, the first main section 41 surrounds the first nozzle 39.

[0035] The first introduction section 42 is connected to the first main section 41. The first introduction section 42 guides the combustion air supplied to the first introduction section 42 to the first main section 41. The first introduction section 42 extends along an in-plane direction perpendicular to the central axis C.

[0036] The second air supply pipe 50 guides the combustion air toward the opening direction 101 while rotating around the first air supply pipe 40. The second air supply pipe 50 has a second main section 51 and a second introduction section 52.

[0037] The second main section 51 surrounds the first air supply pipe 40. A third nozzle 59 is provided at the front end of the second main section 51. The third nozzle 59 is located in the opposite direction to the opening direction 101 relative to the second nozzle 49. From another perspective, the second nozzle 49 is located in the opening direction 101 relative to the second air supply pipe 50.

[0038] The second introduction section 52 is connected to the second main section 51. The second introduction section 52 guides the combustion air supplied to the second introduction section 52 to the second main section 51. The second introduction section 52 extends along an in-plane direction perpendicular to the central axis C.

[0039] The third air supply pipe 60 guides the combustion air toward the opening direction 101 while swirling around the second air supply pipe 50. The third air supply pipe 60 has a third main section 61 and a third introduction section 62.

[0040] The third main section 61 surrounds the second air supply pipe 50. The front end of the third main section 61 constitutes the opening 31 of the burner 3. The third inlet section 62 is connected to the third main section 61. The third inlet section 62 guides the combustion air supplied to the third inlet section 62 to the third main section 61. The third inlet section 62 extends along an in-plane direction perpendicular to the central axis C.

[0041] The cross-section shown in Figure 4 is perpendicular to the central axis C and passes through the first inlet 42. As shown in Figure 4, the first air supply pipe 40 is configured such that the combustion air flowing from the first inlet 42 to the first main section 41 swirls around the fuel supply pipe 30. Specifically, viewed in the opening direction 101, the first inlet 42 extends along the tangent to the inner circumferential surface of the first main section 41. For the sake of explanation, in Figure 3, the cross-section of the first inlet 42 is shown in a cross-section that includes the central axis C and is parallel to the direction in which the first inlet 42 extends.

[0042] In Figure 4, the direction of the combustion air flow is indicated by a dashed line. The direction in which the combustion air swirls is referred to as the swirl direction R. Although not particularly limited, when viewed in the opening direction 101, the swirl direction R is, for example, counterclockwise.

[0043] The configuration of the second main section 51 and the second inlet section 52 is the same as the configuration of the first main section 41 and the first inlet section 42 shown in Figure 4. Specifically, the second air supply pipe 50 is configured such that the combustion air flowing from the second inlet section 52 to the second main section 51 swirls around the first air supply pipe 40 in a swirling direction R.

[0044] The configuration of the third main section 61 and the third inlet section 62 is the same as the configuration of the first main section 41 and the first inlet section 42 shown in Figure 4. Specifically, the third air supply pipe 60 is configured such that the combustion air flowing from the third inlet section 62 into the third main section 61 swirls around the first air supply pipe 40 and the second air supply pipe 50 in a swirling direction R.

[0045] As shown in Figure 5, the RTO 100 has a control unit 9. The control unit 9 controls the opening and closing and degree of opening of the fuel valve 91 and the air valve 92, the opening and closing of the first gas valve 71, the second gas valve 72, the first exhaust valve 81, and the second exhaust valve 82, and controls the ON / OFF of the blower V.

[0046] The control unit 9 can adjust the flow rate of ammonia supplied to the burner 3 by controlling the fuel valve 91. The control unit 9 can also adjust the flow rate of combustion air supplied to the burner 3 by controlling the air valve 92. During the combustion process of the gas to be treated, the control unit 9 controls the air-to-burn ratio in the combustion of the burner 3 to be between 0.7 and 0.95 (the reason will be explained later).

[0047] The control unit 9 controls the start and stop of the supply of the gas to be treated to the first heat storage chamber 2a and the second heat storage chamber 2b by controlling the first gas valve 71 and the second gas valve 72, respectively. The control unit 9 controls the start and stop of the exhaust of the purified gas from the first heat storage chamber 2a and the second heat storage chamber 2b, respectively, by controlling the first exhaust valve 81 and the second exhaust valve 82, respectively.

[0048] (Exhaust gas treatment method) Next, the exhaust gas treatment method according to this embodiment will be described. The exhaust gas treatment method is carried out using the RTO100 described above. As shown in Figure 6, the exhaust gas treatment method according to this embodiment includes a step of raising the temperature of the combustion chamber (S10) and a step of burning the gas to be treated (S20).

[0049] First, a process (S10) is carried out to raise the temperature of the combustion chamber. As shown in Figure 7, the burner 3 is ignited. Specifically, the control unit 9 first starts supplying combustion air to the burner 3 by controlling the air valve 92. Then, the control unit 9 starts supplying ammonia to the burner 3 by controlling the fuel valve 91. The combustion air supplied to the burner 3 flows in the opening direction 101 while swirling in the swirling direction R inside the burner 3 (see Figure 3), so that the combustion air and ammonia are mixed inside the burner 3.

[0050] The control unit 9 generates a spark by energizing a spark plug (not shown) provided in the burner 3. This spark ignites the mixture of combustion air and ammonia. The combustion of ammonia generates a flame F in the burner 3.

[0051] The combustion chamber 1 is heated by the flame F. Under normal operation, the inside of the combustion chamber 1 is heated to a temperature between 800°C and 1000°C. During the process of raising the temperature of the combustion chamber (S10), the gas to be treated is not supplied to the combustion chamber 1. Alternatively, the third supply valve 73 is closed.

[0052] In the process of raising the temperature of the combustion chamber (S10), the air ratio (first air ratio) in the combustion of burner 3 is 1.0. The air ratio in the combustion of burner 3 is the value obtained by dividing the amount of combustion air supplied to burner 3 by the theoretical amount of ammonia air supplied to burner 3.

[0053] Next, a process (S20) is carried out to burn the gas to be treated. As shown in Figure 7, the control unit 9 supplies the gas to be treated to the combustion chamber 1 via the first heat storage chamber 2a and exhausts the treated gas (purified gas) that has been burned through the second heat storage chamber 2b from the combustion chamber 1.

[0054] Specifically, the control unit 9 opens the flow path from the first branching point B1 to the first heat storage chamber 2a by controlling the first gas valve 71. The control unit 9 closes the flow path from the first branching point B1 to the second heat storage chamber 2b by controlling the second gas valve 72. The control unit 9 closes the flow path from the first heat storage chamber 2a to the second branching point B2 by controlling the first exhaust valve 81. The control unit 9 opens the flow path from the second heat storage chamber 2b to the second branching point B2 by controlling the second exhaust valve 82.

[0055] The control unit 9 starts supplying the gas to be treated to the gas supply channel P1 by controlling the third supply valve 73 and the blower V, respectively. The gas to be treated passes through the heat storage body 21 housed in the first heat storage chamber 2a and flows into the combustion chamber 1. The gas to be treated is air containing volatile organic compounds (VOCs) such as toluene and xylene, for example, discharged from a paint factory.

[0056] VOCs contained in the gas to be treated are thermally decomposed by heating to a high temperature using the flame F of burner 3. In this way, the gas to be treated is combusted. The purified gas that has been combusted flows into the exhaust flow path P2 through the second heat storage chamber 2b. As the high-temperature purified gas passes through the second heat storage chamber 2b, the heat storage body 21 contained in the second heat storage chamber 2b is heated. The purified gas that has flowed into the exhaust flow path P2 is released into the atmosphere through the exhaust tower 4.

[0057] In the step of combustion treatment of the gas to be treated (S20), the air ratio in the combustion of burner 3 is determined based on the amount of oxygen in the gas to be treated and the atmospheric gas in combustion chamber 1. In combustion chamber 1, the oxygen concentration of the gas to be treated and the atmospheric gas is, for example, about 10% to 20%. In this case, in the step of combustion treatment of the gas to be treated (S20), the air ratio in combustion of burner 3 (second air ratio) is lower than the first air ratio described above, and is set to 0.7 to 0.95 (the reason will be explained later).

[0058] The second air ratio may be, for example, 0.73 or higher, or 0.75 or higher. The second air ratio may be, for example, 0.93 or lower, or 0.90 or lower. The control unit 9 controls the flow rate of combustion air by controlling the air valve 92 so that the air ratio in the combustion of the burner 3 becomes the value of the above-mentioned second air ratio.

[0059] In the above, the process of supplying the gas to be treated to the combustion chamber 1 via the first heat storage chamber 2a and exhausting the purified gas from the combustion chamber 1 via the second heat storage chamber 2b was described. In the process of combustion treatment of the gas to be treated (S20), the control unit 9 periodically repeats the first step of supplying the gas to be treated to the combustion chamber 1 via the first heat storage chamber 2a and exhausting the purified gas from the combustion chamber 1 via the second heat storage chamber 2b, and the second step of supplying the gas to be treated to the combustion chamber 1 via the second heat storage chamber 2b and exhausting the purified gas from the combustion chamber 1 via the first heat storage chamber 2a. Figure 7 shows the flow of the gas to be treated in the first step.

[0060] Figure 8 shows the flow of the gas to be treated in the second step. As shown in Figure 8, the control unit 9 starts supplying the gas to be treated to the second heat storage chamber 2b and shuts off the flow path to the first heat storage chamber 2a.

[0061] Specifically, the control unit 9 closes the flow path from the first branching point B1 to the first heat storage chamber 2a by controlling the first gas valve 71. The control unit 9 opens the flow path from the first branching point B1 to the second heat storage chamber 2b by controlling the second gas valve 72.

[0062] The control unit 9 opens the flow path from the first heat storage chamber 2a to the second branching point B2 by controlling the first exhaust valve 81. The control unit 9 closes the flow path from the second heat storage chamber 2b to the second branching point B2 by controlling the second exhaust valve 82.

[0063] As described above, in the second step, the gas to be treated is supplied to the combustion chamber 1 through the heat storage body 21, which has been heated to a high temperature in the first step described above. Therefore, the gas to be treated is heated by the heat storage body 21. This allows the waste heat from the first step described above to be utilized. As a result, the amount of fuel used by the burner that heats the gas to be treated in the combustion chamber 1 can be reduced.

[0064] In the second step, the high-temperature purified gas passes through the first heat storage chamber 2a, heating the heat storage body 21 contained in the first heat storage chamber 2a. Therefore, when the first step is performed after the second step, the waste heat from the second step can be utilized.

[0065] Next, the effects and benefits of the RTO100 and exhaust gas treatment method according to this embodiment will be described.

[0066] Typically, RTO burners use easily combustible hydrocarbon fuels. In this case, CO2 produced by the combustion of hydrocarbon fuels is emitted from the RTO. Therefore, the emitted CO2 may have a negative impact on the environment.

[0067] According to the RTO100 of this embodiment, the burner 3 uses ammonia as fuel. No CO2 is generated during the combustion of ammonia. Therefore, according to the RTO100 of this embodiment, CO2 emissions can be reduced.

[0068] While ammonia combustion does not produce CO2 in its exhaust, it is environmentally harmful because the nitrogen in ammonia reacts with oxygen in the combustion air during combustion, generating NOx, which is released into the atmosphere and contributes to acid rain. NOx is particularly generated when there is an excessive amount of oxygen around the flame during ammonia combustion. However, if ammonia fuel is completely combusted in a closed space (combustion with an air-to-fuel ratio of around 1.0), the amount of NOx generated can be reduced. However, during RTO operation, even if the air-to-fuel ratio during flame injection from the burner is adjusted to around 1.0, a large amount of air (air containing harmful components) enters the furnace as the gas to be treated. As a result, the actual air-to-fuel ratio inside the furnace exceeds 1.0, leading to the generation of a large amount of NOx.

[0069] The RTO100 according to this embodiment has a control unit 9. During the combustion treatment of the gas to be treated, the control unit 9 controls the air ratio in the combustion of the burner 3 to 0.95 or less. Therefore, ammonia is not completely combusted with only the combustion air supplied to the burner 3. Consequently, oxygen in the gas to be treated supplied to the combustion chamber 1 is used for the combustion of ammonia. This reduces the amount of oxygen present in the combustion chamber 1. Therefore, the amount of NOx generated during the combustion treatment of the gas to be treated can be reduced.

[0070] Furthermore, when the amount of gas to be treated supplied to RTO100 is very small, the amount of oxygen in the gas to be treated supplied to combustion chamber 1 will also be very small. Therefore, it is considered possible to make the amount of oxygen in the gas to be treated supplied to combustion chamber 1 equal to the amount of oxygen consumed by the combustion of ammonia.

[0071] If the combustion air supplied to burner 3 is excessively reduced, ammonia will not burn completely, resulting in unburned ammonia being generated in combustion chamber 1 and released into the atmosphere from exhaust tower 4. Ammonia has a pungent odor and is harmful to the environment.

[0072] According to the RTO100 of this embodiment, the control unit 9 controls the air-to-air ratio in the combustion of the burner 3 to 0.7 or higher. This suppresses an excessive increase in unburned ammonia emitted during the combustion of the burner 3. Therefore, the emission of unburned ammonia from the RTO100 can be suppressed. For these reasons, it is preferable to set the air-to-air ratio in the combustion of the burner 3 to 0.7 or higher and 0.95 or lower.

[0073] As an alternative control method, as shown in Figure 10, a sensor 7 (such as an oxygen concentration sensor or NOx concentration sensor) may be installed in the exhaust flow path P2, and the air-fuel ratio may be adjusted by controlling the opening of the fuel valve 91 and the air valve 92 while monitoring the exhaust condition via the control unit 9.

[0074] For example, an oxygen concentration sensor may be used to monitor the oxygen concentration in the exhaust gas and adjust the air-fuel ratio so that no oxygen remains that can contribute to the combustion of ammonia, or a NOx concentration sensor may be used to monitor the NOx concentration in the exhaust gas and adjust the air-fuel ratio so that excessive NOx is not emitted. In these cases, the sensor 7 transmits information about the exhaust gas conditions (such as the oxygen concentration and NOx concentration of the exhaust gas) to the control unit 9. In Figure 10, the dashed arrows indicate the flow of electrical signals.

[0075] According to the RTO100 of this embodiment, the combustion chamber 1 has a main combustion space 11 and a secondary combustion space 12. The main combustion space 11 is in communication with each of the multiple heat storage chambers 2. The secondary combustion space 12 connects the opening 31 of the burner 3 to the main combustion space 11. Therefore, as shown in Figure 9, the flame F of the burner 3 enters the main combustion space 11 after passing through the secondary combustion space 12.

[0076] According to the RTO100 of this embodiment, the sub-combustion space 12 is provided with a step 15 and has a first portion 13 on the burner 3 side and a second portion 14 on the main combustion space 11 side. The inner diameter of the second portion 14 is larger than that of the first portion 13, and the surface area of ​​the inner circumferential surface 16 of the wall is larger in the second portion 14. The inner circumferential surface 16 is heated by the flame F, and radiant heat is generated from the heated inner circumferential surface 16. By widening the area of ​​the inner circumferential surface 16 of the wall in the second portion 14 in this way, a large amount of radiant heat can be supplied to the flame F. As a result, the flame F is less likely to go out, and stable combustion becomes possible.

[0077] Because the combustion chamber 1 has a sub-combustion space 12, the ammonia and combustion air ejected from the burner 3 are burned in the sub-combustion space 12 (primary combustion). Subsequently, the ammonia that remains unburned in the primary combustion is secondarily burned in the main combustion space 11 using oxygen in the gas to be treated supplied to the combustion chamber 1 (secondary combustion). By burning the ammonia in these two stages, it is possible to suppress the flame temperature F from becoming excessively high. This reduces the amount of NOx produced by the combustion of ammonia.

[0078] Furthermore, the first part 13 is in communication with the opening 31 of the burner 3. The second part 14 connects the first part 13 to the main combustion space 11. The value obtained by dividing the width H2 of the second part 14 by the width H1 of the first part 13 is between 1.2 and 2.0.

[0079] As shown in Figure 9, by providing a step 15 in the middle of the fluid flow ejected from the opening 31 of the burner 3 to widen the space, a delay occurs in the flow near the inner circumferential surface 16 of the second part 14, and a vortex S is generated in the fluid ejected from the burner 3 in the second part 14. In Figure 9, the flow of the vortex S is indicated by arrows. The vortex S better mixes the ammonia and the combustion air. As a result, the ammonia and combustion air can be effectively mixed, making the ammonia more flammable and improving the stability of the flame F.

[0080] As shown in Figure 9, the generation of a vortex S in the second section 14 causes a portion of the gas to be treated flowing through the main combustion space 11 to be drawn into the vortex S, as indicated by arrow A. This allows the gas to take in more oxygen from the air it contains.

[0081] According to the exhaust gas treatment method of this embodiment, the gas to be treated is burned using a burner 3. The burner 3 uses ammonia as fuel. No CO2 is generated during the combustion of ammonia. Therefore, according to the exhaust gas treatment method of this embodiment, CO2 emissions can be reduced.

[0082] According to the exhaust gas treatment method of this embodiment, in the step of burning the gas to be treated (S20), the air ratio in the combustion of the burner 3 is 0.95 or less. Therefore, ammonia is not completely combusted with only the combustion air supplied to the burner 3. Consequently, the oxygen in the gas to be treated supplied to the combustion chamber 1 is used for the combustion of ammonia. This reduces the amount of oxygen present in the combustion chamber 1. Therefore, the amount of NOx generated during the combustion of the gas to be treated can be reduced.

[0083] According to the exhaust gas treatment method of this embodiment, in the step of burning the gas to be treated (S20), the air ratio in the combustion of the burner 3 is 0.7 or higher. This makes it possible to suppress an excessive increase in unburned ammonia emitted during the combustion of the burner 3. Therefore, it is possible to suppress the emission of unburned ammonia from the RTO 100.

[0084] In the above description, the RTO 100 was configured to have two heat storage chambers 2, but the RTO 100 may have three or more heat storage chambers 2. Also, in the above description, the burner 3 was attached to the burner tile 6, but the burner 3 may be attached to the wall 5 of the RTO 100. Furthermore, in the above description, a configuration in which the flow of the gas to be treated is switched using a gas supply valve and an exhaust valve was described, but the configuration of the RTO 100 according to this embodiment is not limited to the above configuration. For example, the RTO 100 may be a rotary heat storage exhaust gas treatment device. Specifically, the RTO 100 may sequentially switch the supply of the gas to be treated to a plurality of heat storage chambers 2 and the discharge of the purified gas using a rotary switching valve (distribution valve).

[0085] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the embodiments described above, and all modifications within the meaning and scope of the claims are intended to be included. [Explanation of Symbols]

[0086] 1. Combustion chamber 2 Heat storage chamber 2a 1st heat storage chamber 2b 2nd heat storage chamber 3 burners 4. Exhaust tower 5 walls 6 Burner Tiles 7. Sensors (oxygen concentration sensor, NOx concentration sensor, etc.) 9. Control Unit 11 Main combustion space 12. Secondary combustion space 13 Part 1 14 Part 2 15 steps 16. Inner surface of the wall 16a First inner peripheral surface part 16b Second inner peripheral surface part 21 Heat storage element 30 Fuel supply pipe 31 Opening 39 1st spout 40 First air supply pipe 41 First main part 42 First introduction part 49 Second jet outlet 50 Second air supply pipe 51 Second main part 52 Second introduction part 59 Third jet outlet 60 Third air supply pipe 61 Third main part 62 Third introduction part 71 First gas valve 72 Second gas valve 73 Third supply valve 81 First exhaust valve 82 Second exhaust valve 91 Fuel valve 92 Air valve 100 Regenerative thermal oxidizer (RTO) 101 Opening direction B1 First branch point B2 Second branch point C Central axis D1 First depth D2 Second depth F Flame H1 First width H2 Second width P1 Process gas supply flow path P2 Exhaust flow path P3 Fuel supply flow path P4 Air supply flow path R Swirling direction S Vortex V Blower

Claims

1. The combustion chamber in which the burner is installed, Multiple heat storage chambers, each containing a heat storage element and communicating with the combustion chamber, A gas to be treated supply channel that guides the gas to be treated to the combustion chamber through at least a portion of the plurality of heat storage chambers, The system includes an exhaust passage for exhausting the gas to be treated, which has been combusted using the burner, to the outside of the combustion chamber through at least a portion of the plurality of heat storage chambers. The aforementioned burner is a regenerative exhaust gas treatment device that uses ammonia as fuel.

2. The system includes a control unit that controls the flow rates of the ammonia supplied to the burner and the combustion air supplied to the burner, respectively. In the combustion treatment of the gas to be treated, the control unit controls the air ratio in the combustion of the burner to 0.7 or more and 0.95 or less, according to claim 1, a regenerative exhaust gas treatment apparatus.

3. The burner has an opening that opens toward the combustion chamber, The aforementioned combustion chamber is A main combustion space communicating with each of the aforementioned multiple heat storage chambers, It has a secondary combustion space connecting the main combustion space and the opening, The aforementioned sub-combustion space is A first portion communicating with the aforementioned opening, It has a second part that connects the first part and the main combustion space, The regenerative exhaust gas treatment apparatus according to claim 1 or claim 2, wherein the value obtained by dividing the width of the second portion by the width of the first portion is 1.2 or more and 2.0 or less.

4. The process of raising the temperature of the combustion chamber, The process includes burning the gas to be treated supplied to the combustion chamber using a burner, The burner is an exhaust gas treatment method that uses ammonia as fuel.

5. The exhaust gas treatment method according to claim 4, wherein in the step of burning the gas to be treated using the burner, the air ratio in the combustion of the burner is determined based on the amount of oxygen in the gas to be treated supplied to the combustion chamber and the atmospheric gas in the combustion chamber.

6. The exhaust gas treatment method according to claim 4 or claim 5, wherein in the step of burning the gas to be treated using the burner, the air ratio in the combustion of the burner is 0.7 or more and 0.95 or less.

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