Exhaust gas treatment device and method for designing exhaust gas treatment device

Abstract

Provided is an exhaust gas treatment device (100) for treating exhaust gas discharged from a combustion device (200) for combusting fuel containing ammonia, the exhaust gas treatment device (100) being provided with: an ammonia decomposition unit (10) having an ammonia decomposition catalyst for decomposing ammonia contained in the exhaust gas; and a nitrogen oxide decomposition unit (20) having a second catalyst for decomposing nitrous oxide and NOx contained in the exhaust gas from which ammonia has been decomposed in the ammonia decomposition unit (10).

Description

Technical Field

[0001] The present disclosure relates to an exhaust gas treatment device and a design method of the exhaust gas treatment device. Background Art

[0002] In recent years, in order to curb global warming and achieve carbon neutrality, the use of ammonia fuel has been studied as a fuel that does not emit carbon dioxide when burned. When using ammonia fuel, the exhaust gas contains not only NOx but also ammonia (NH3), nitrous oxide (N2O), etc., so it is necessary to remove them from the exhaust gas to reduce the impact on the environment.

[0003] Conventionally, there is known an ammonia treatment apparatus that decomposes ammonia into nitrogen and water by oxidizing ammonia using an ammonia decomposition catalyst (for example, refer to Patent Document 1).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2006-26529 Summary of the invention

[0007] Problems to be solved by the invention

[0008] However, in Patent Document 1, although ammonia can be decomposed, for example, when nitrous oxide is contained in the gas to be processed, nitrous oxide cannot be decomposed.

[0009] In addition, in order to decompose NOx contained in the exhaust gas discharged from the combustion device, a selective catalytic reduction method (SCR) is known in the past, which sprays ammonia or urea water as a reducing agent into the exhaust gas to reduce NOx. However, in the selective catalytic reduction method, although NOx can be decomposed, nitrous oxide cannot be decomposed.

[0010] The present disclosure has been made in view of such circumstances, and an object of the present disclosure is to provide an exhaust gas treatment device and a method for designing an exhaust gas treatment device that can appropriately decompose ammonia, nitrous oxide, and NOx contained in exhaust gas discharged from a combustion device that burns a fuel containing ammonia.

[0011] Means for solving problems

[0012] In order to solve the above-mentioned problems, the present disclosure adopts the following means.

[0013] The exhaust gas treatment device disclosed in the present invention is an exhaust gas treatment device for treating exhaust gas discharged from a combustion device that burns a fuel containing ammonia, wherein the exhaust gas treatment device comprises: a first treatment section having a first catalyst for decomposing ammonia contained in the exhaust gas; and a second treatment section having a second catalyst for decomposing nitrous oxide and NOx contained in the exhaust gas in which ammonia has been decomposed in the first treatment section.

[0014] The design method of the exhaust gas treatment device disclosed in the present invention is a design method of the exhaust gas treatment device for treating exhaust gas discharged from a combustion device that burns a fuel containing ammonia, wherein, when the concentration of ammonia contained in the exhaust gas is higher than the total concentration of a first concentration obtained by multiplying the concentration of nitrous oxide contained in the exhaust gas by a first coefficient and a second concentration obtained by multiplying the concentration of NOx contained in the exhaust gas by a second coefficient, the exhaust gas treatment device is designed in a manner that a first treatment section having a first catalyst for decomposing ammonia contained in the exhaust gas is arranged on the downstream side of the combustion device, and a second treatment section having a second catalyst for decomposing nitrous oxide and NOx contained in the exhaust gas in which ammonia has been decomposed in the first treatment section is arranged on the downstream side of the first treatment section, and when the concentration of ammonia contained in the exhaust gas is lower than the total concentration, the exhaust gas treatment device is designed in a manner that the first treatment section is not arranged on the downstream side of the combustion device and the second treatment section is arranged.

[0015] Effects of the Invention

[0016] According to the present disclosure, it is possible to provide an exhaust gas treatment device and a method for designing an exhaust gas treatment device that can appropriately decompose ammonia, nitrous oxide, and NOx contained in exhaust gas exhausted from a combustion device that burns a fuel containing ammonia. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic configuration diagram showing an exhaust gas treatment device according to a first embodiment of the present disclosure.

[0018] Figure 2 This is a graph showing the decomposition characteristics of the ammonia decomposition catalyst.

[0019] Figure 3 This is a graph showing the relationship between the ammonia concentration in the ammonia decomposition catalyst and the temperature increase.

[0020] Figure 4 This is a graph showing the decomposition characteristics of nitrous oxide with respect to the temperature of the exhaust gas.

[0021] Figure 5 This is a graph showing the decomposition characteristics of NO with respect to the temperature of the exhaust gas.

[0022] Figure 61 is a flowchart showing a supply process of a reducing agent in the exhaust gas treatment device according to the first embodiment of the present disclosure.

[0023] Figure 7 1 is a flowchart showing a switching process of the bypass valve in the exhaust gas treatment device according to the first embodiment of the present disclosure.

[0024] Figure 8 It is a schematic configuration diagram showing an exhaust gas treatment device according to a second embodiment of the present disclosure.

[0025] Fig. 9 1 is a flowchart showing a switching process of a bypass valve in an exhaust gas treatment device according to a second embodiment of the present disclosure.

[0026] Fig.10 It is a schematic configuration diagram showing an exhaust gas treatment device according to a third embodiment of the present disclosure.

[0027] Fig.11 1 is a flowchart showing a method for designing an exhaust gas treatment device according to a fourth embodiment of the present disclosure.

[0028] Fig.12 It is a schematic configuration diagram showing an exhaust gas treatment device according to a fifth embodiment of the present disclosure.

[0029] Fig.13 This is a graph showing the decomposition rate of nitrous oxide in the nitrogen oxide decomposition unit with respect to the temperature of the exhaust gas, and comparing the case where the NO concentration is 0 ppm and the case where the NO concentration is 450 ppm.

[0030] Fig.14 1 is a flowchart showing a supply process of fuel and reducing agent in an exhaust gas treatment device according to a fifth embodiment of the present disclosure.

[0031] Fig.15 1 is a flowchart showing a supply process of fuel and reducing agent in an exhaust gas treatment device according to a fifth embodiment of the present disclosure.

[0032] Fig.16 1 is a flowchart showing a supply process of fuel and reducing agent in an exhaust gas treatment device according to a fifth embodiment of the present disclosure.

[0033] Fig.17 It is a schematic configuration diagram showing an exhaust gas treatment device according to a modified example of the fifth embodiment of the present disclosure. DETAILED DESCRIPTION

[0034] [First embodiment]

[0035] Hereinafter, an exhaust gas treatment device 100 according to a first embodiment of the present disclosure will be described with reference to the drawings. The exhaust gas treatment device 100 according to this embodiment treats exhaust gas discharged from a combustion device 200 that burns a fuel containing ammonia, and reduces ammonia, nitrous oxide, and NOx discharged to the outside.

[0036] The combustion device 200 is a device that burns a fuel containing ammonia, and is, for example, a marine diesel engine that generates propulsion for a ship. The combustion device 200 of this embodiment, for example, mixes ammonia with other fuels (heavy oil, LNG (liquefied natural gas), LPG (liquefied petroleum gas)). In addition, the combustion device 200 may also be a device that uses only ammonia as fuel.

[0037] In the combustion device 200, ammonia is used as a fuel, so the exhaust gas discharged from the combustion device 200 contains unburned ammonia. In addition, the exhaust gas discharged from the combustion device 200 contains NOx (NO, NO2) and nitrous oxide (N2O) generated by the combustion of ammonia and other fuels. The exhaust gas treatment device 100 of this embodiment reduces ammonia, NOx and nitrous oxide contained in the exhaust gas discharged from the combustion device 200.

[0038] Figure 1 1 is a schematic structural diagram showing an exhaust gas treatment device according to a first embodiment of the present disclosure. Figure 1 As shown, the exhaust gas treatment device 100 of the present embodiment includes an ammonia decomposition unit (first treatment unit) 10, a nitrogen oxide decomposition unit (second treatment unit) 20, an ammonia decomposition unit (third treatment unit) 30, a detection unit 40, a first supply unit 50 for supplying ammonia or urea water as a reducing agent, a temperature sensor 60, a bypass valve 70, and a control unit 80.

[0039] The exhaust gas discharged from the combustion device 200 is supplied to the ammonia decomposition unit 10 via the pipe L1. The exhaust gas that has passed through the ammonia decomposition unit 10 is supplied to the nitrogen oxide decomposition unit 20 via the pipe L2. The exhaust gas that has passed through the nitrogen oxide decomposition unit 20 is supplied to the ammonia decomposition unit 30 via the pipe L3. The exhaust gas that has passed through the ammonia decomposition unit 30 is discharged to the outside via the pipe L4. When the bypass valve 70 is in an open state, a part of the exhaust gas that has passed through the nitrogen oxide decomposition unit 20 does not pass through the ammonia decomposition unit 30 but is introduced from the pipe L3 to the pipe L4 via the pipe L5.

[0040] The exhaust gas treatment device 100 of the present embodiment includes the pipe L5 and the bypass valve 70 , but a modified example that does not include these is also possible. In this modified example, the total amount of the exhaust gas that has passed through the nitrogen oxide decomposition unit 20 is introduced into the ammonia decomposition unit 30 .

[0041] The ammonia decomposition unit 10 has an ammonia decomposition catalyst (first catalyst) for decomposing ammonia contained in the exhaust gas discharged from the combustion device 200. The ammonia decomposition catalyst is a multifunctional catalyst that not only decomposes ammonia but also decomposes NOx and suppresses the generation of nitrous oxide. The ammonia decomposition catalyst of the present embodiment is a catalyst composed of a first component and a second component, wherein the first component is silica and / or zeolite loaded with one or more precious metals selected from platinum (Pt), palladium (Pd), iridium (Ir) and rhodium (Rh), and the second component is a composition composed of oxides of one or more elements selected from titanium (Ti), tungsten (W) and vanadium (V). Examples of the ammonia decomposition catalyst will be described later.

[0042] The ammonia decomposition catalyst of the ammonia decomposition unit 10 decomposes NH 3 using the first component according to the following formulas (1) and (2).

[0043] 4NH3+3O2→2N2+6H2O (1)

[0044] 4NH3+5O2→4NO+6H2O (2)

[0045] The ammonia decomposition catalyst of the ammonia decomposition unit 10 decomposes NH 3 using the second component according to the following formula (3), and removes at least a portion of NO produced as a by-product in the formula (2).

[0046] 4NH3+4NO+O2→4N2+6H2O (3)

[0047] In addition, in the ammonia decomposition catalyst of the ammonia decomposition unit 10, it is estimated that NO2 generated by oxidation of NH3 according to equation (4) generates nitrous oxide (N2O) according to equation (5). In the ammonia decomposition catalyst, a small amount of precious metal catalyst is uniformly present on the denitration catalyst, so there is a high probability that NO2 generated on the precious metal catalyst reacts directly with NO generated by equation (2) on the denitration catalyst as shown in equation (6) to become N2, thereby reducing the by-production of N2O.

[0048] 4NH3+7O2→4NO2+6H2O (4)

[0049] 4NH3+4NO2+O2→4N2O+6H2O (5)

[0050] NO+NO2+2NH3→2N2+3H2O (6)

[0051] The nitrogen oxide decomposition unit 20 has a nitrogen oxide decomposition catalyst (second catalyst) that decomposes nitrous oxide and NOx contained in the exhaust gas whose ammonia has been decomposed in the ammonia decomposition unit 10. The nitrogen oxide decomposition catalyst contains: a carrier containing SiO2 and Al2O3 and an iron element supported thereon. In the carrier, SiO2 and Al2O3 can be contained in the form of a mixture or in the form of a composite. As a substance formed by a composite of SiO2 and Al2O3, for example, aluminum silicate (xM2O·yAl2O3·zSiO2·nH2O) and the like can be cited. Examples of the nitrogen oxide decomposition catalyst will be described later.

[0052] The nitrogen oxide decomposition catalyst of the nitrogen oxide decomposition unit 20 decomposes dinitrogen monoxide by reducing reaction with NH 3 according to the following formula (7).

[0053] 3N2O+2NH3→4N2+3H2O (7)

[0054] The nitrogen oxide decomposition catalyst of the nitrogen oxide decomposition unit 20 decomposes NOx by causing a reduction reaction using NH 3 according to the following equations (8), (9), and (10).

[0055] 4NO+4NH3+O2→4N2+6H2O (8)

[0056] NO+NO2+2NH3→2N2+3H2O (9)

[0057] 6NO2+8NH3→7N2+12H2O (10)

[0058] The ammonia decomposition unit 30 has an ammonia decomposition catalyst (third catalyst) that decomposes ammonia contained in the exhaust gas that has passed through the nitrogen oxide decomposition unit 20. The ammonia decomposition catalyst is a multifunctional catalyst that not only decomposes ammonia but also has the function of decomposing NOx and suppressing the generation of nitrous oxide. The ammonia decomposition catalyst is a catalyst composed of a first component and a second component, wherein the first component is silica and / or zeolite supported with one or more precious metals selected from platinum (Pt), palladium (Pd), iridium (Ir) and rhodium (Rh), and the second component is a composition composed of oxides of one or more elements selected from titanium (Ti), tungsten (W) and vanadium (V). The structure of the ammonia decomposition unit 30 is the same as that of the ammonia decomposition unit 10, so the following description is omitted.

[0059] The detection unit 40 is a device for detecting the concentration of nitrous oxide and NOx contained in the exhaust gas passing through the ammonia decomposition unit 10. The detection unit 40 detects the concentration of nitrous oxide and NOx contained in the exhaust gas passing through the pipe L3. The concentration of nitrous oxide and NOx detected by the detection unit 40 is transmitted to the control unit 80.

[0060] The first supply unit 50 is a device for supplying ammonia or urea water as a reducing agent to the exhaust gas supplied from the ammonia decomposition unit 10 to the nitrogen oxide decomposition unit 20. The first supply unit 50 supplies the reducing agent to the pipe L2 via the pipe L6 to mix it with the exhaust gas flowing in the pipe L2. The pipe L6, for example, sprays the reducing agent into the pipe L2 to mix the reducing agent with the exhaust gas. The first supply unit 50 adjusts the supply amount of the reducing agent supplied to the pipe L2 according to the control signal transmitted from the control unit 80.

[0061] When urea water is supplied as a reducing agent, the urea water mixed with the exhaust gas in the pipe L2 is hydrolyzed in the exhaust gas to generate ammonia. Then, the nitrogen oxide decomposition catalyst of the nitrogen oxide decomposition unit 20 decomposes NOx by reducing reaction using ammonia (NH3) according to the above-mentioned equations (7), (8), and (9).

[0062] The temperature sensor 60 is a device that detects the temperature of the exhaust gas flowing through the pipe L2 . The temperature sensor 60 transmits the detected temperature of the exhaust gas to the control unit 80 .

[0063] The bypass valve 70 is an on-off valve disposed in the pipe L5. The on-off state of the bypass valve 70 is controlled by the control unit 80. When the bypass valve 70 is in the open state, the exhaust gas is introduced from the pipe L3 to the pipe L4 via the pipe L5. When the bypass valve 70 is in the closed state, the exhaust gas is not introduced into the pipe L5, and the total amount of the exhaust gas flowing in the pipe L3 is introduced into the pipe L4 via the ammonia decomposition unit 30.

[0064] The control unit 80 is a device that controls each unit of the exhaust gas treatment device 100. The control unit 80 reads and executes a control program stored in a storage unit (not shown), thereby controlling each unit of the exhaust gas treatment device 100.

[0065] The control unit 80 controls the amount of the reducing agent supplied from the first supply unit 50 to the pipe L2 based on the concentrations of nitrous oxide and NOx detected by the detection unit 40 and the temperature of the exhaust gas detected by the temperature sensor 60. In addition, the control unit 80 controls the opening and closing state of the bypass valve 70 based on the concentrations of nitrous oxide and NOx detected by the detection unit 40 and the temperature of the exhaust gas detected by the temperature sensor 60.

[0066] Next, refer to Figure 2 The decomposition characteristics of the ammonia decomposition catalyst of the ammonia decomposition unit 10 of the present embodiment will be described. Figure 2 is a graph showing the decomposition characteristics of an ammonia decomposition catalyst. Figure 2 As shown, as the temperature of the exhaust gas containing ammonia increases from 350° C. to 450° C., the ammonia decomposition rate [%] by the ammonia decomposition catalyst of the ammonia decomposition unit 10 increases.

[0067] Next, refer to Figure 3 The relationship between the ammonia concentration in the ammonia decomposition catalyst of the ammonia decomposition unit 10 of the present embodiment and the temperature increase will be described. Figure 3 This is a graph showing the relationship between the ammonia concentration in the ammonia decomposition catalyst and the temperature increase.

[0068] like Figure 3 As shown, the ammonia decomposition catalyst of the ammonia decomposition unit 10 generates heat when decomposing ammonia, and as the concentration of unburned ammonia contained in the exhaust gas discharged from the combustion device 200 increases, the temperature of the exhaust gas increases. By burning the unburned ammonia using the ammonia decomposition catalyst of the ammonia decomposition unit 10, the temperature of the ammonia decomposition unit 10 can be increased, and the ammonia decomposition rate can be improved. In addition, the temperature of the exhaust gas discharged from the ammonia decomposition unit 10 can be increased.

[0069] Next, refer to Figure 4 The decomposition characteristics of nitrous oxide with respect to the temperature of the exhaust gas will be described. Figure 4 This is a graph showing the decomposition characteristics of nitrous oxide with respect to the temperature of the exhaust gas. Figure 4 The catalysts A to F shown correspond to the catalysts A to F described in the examples of the nitrogen oxide decomposition catalyst described later. Figure 4 As shown, in any of the catalysts A to F, the decomposition rate of dinitrogen monoxide increases as the exhaust gas temperature rises. Therefore, when the exhaust gas temperature rises due to the decomposition of ammonia by the ammonia decomposition catalyst of the ammonia decomposition unit 10, the decomposition rate of dinitrogen monoxide increases as the exhaust gas temperature rises.

[0070] Next, refer to Figure 5 The decomposition characteristics of NO with respect to the temperature of the exhaust gas will be described. Figure 5 This is a graph showing the decomposition characteristics of NO with respect to the temperature of the exhaust gas. Figure 5 The catalysts A to F shown correspond to the catalysts A to F described in the examples of the nitrogen oxide decomposition catalyst described later. Figure 5 As shown, in any of the catalysts AF, the NO decomposition rate increases as the exhaust gas temperature increases. Therefore, when the exhaust gas temperature increases as the ammonia decomposition catalyst of the ammonia decomposition unit 10 decomposes ammonia, the NO decomposition rate increases as the exhaust gas temperature increases.

[0071] In the present embodiment, the ammonia decomposition section 10 is provided on the upstream side of the nitrogen oxide decomposition section 20 because it is assumed that the supply amount of unburned ammonia contained in the exhaust gas discharged from the combustion device 200 exceeds the amount of ammonia required for decomposing nitrous oxide and NOx in the nitrogen oxide decomposition section 20. The exhaust gas treatment device 100 of the present embodiment decomposes the excess ammonia in the ammonia decomposition section 10, and increases the temperature of the exhaust gas by the heat generated when decomposing ammonia, thereby increasing the decomposition rate of nitrous oxide and NOx in the nitrogen oxide decomposition section 20.

[0072] In the exhaust gas treatment device 100 of the present embodiment, it is assumed that the concentrations of ammonia, nitrous oxide, and NOx contained in the exhaust gas exhausted from the combustion device 200 satisfy the following formula (11), respectively.

[0073] Ammonia concentration > α × nitrous oxide concentration + β × NOx concentration (11)

[0074] Here, α and β are coefficients, for example, α = 1.0, β = 1.5. Let α = 1.0 be the value obtained by multiplying the molar ratio of ammonia to nitrous oxide in the reaction of formula (7) (ammonia / nitrous oxide = 2 / 3) by 1.5. Let β = 1.5 be the value obtained by multiplying the molar ratio of ammonia to NO in the reaction of formula (8) (ammonia / NO = 1 / 1) by 1.5. It should be noted that the numerical value multiplied by α and β is not limited to 1.5, for example, it can also be set to any numerical value greater than 1.2 and less than 2.0 according to the properties of the exhaust gas of the combustion device 200.

[0075] On the other hand, for example, when the amount of exhaust gas discharged from the exhaust gas treatment device 100 and the ammonia contained in the exhaust gas are less than expected, the total amount of unburned ammonia is decomposed in the ammonia decomposition unit 10, and the ammonia required as a reducing agent is insufficient in the nitrogen oxide decomposition unit 20. Therefore, in the present embodiment, when the ammonia required as a reducing agent in the nitrogen oxide decomposition unit 20 is insufficient, the shortage of ammonia in the nitrogen oxide decomposition unit 20 is supplemented by supplying the reducing agent from the first supply unit 50.

[0076] Next, refer to Figure 6 The supply process of the reducing agent in the exhaust gas treatment device 100 of the present embodiment will be described. Figure 6 1 is a flowchart showing a reducing agent supply process in the exhaust gas treatment device 100 according to the present embodiment. Figure 6 The processing of each step is executed by the control unit 80 controlling each unit of the exhaust gas treatment device 100. When the combustion operation by the combustion device 200 starts, the processing of this flowchart starts.

[0077] In step S101, the control unit 80 determines whether the temperature Ta of the exhaust gas flowing through the pipe L2 transmitted from the temperature sensor 60 is above the supplyable temperature (for example, 350° C.) at which the reducing agent can be supplied to the nitrogen oxide decomposition unit 20. If so, the process proceeds to step S102, and if not, the process proceeds to step S108.

[0078] In step S108 , since the temperature Ta of the exhaust gas flowing through the pipe L2 is lower than the supplyable temperature at which the reducing agent can be supplied to the nitrogen oxide decomposition unit 20 , the control unit 80 performs control to stop the supply of the reducing agent by the first supply unit 50 .

[0079] In step S102 , the control unit 80 determines whether the NOx concentration detected by the detection unit 40 is less than or equal to a first predetermined concentration (eg, 200 ppm), and if so, proceeds to step S103 , and if not, proceeds to step S105 .

[0080] In step S103 , control unit 80 determines whether the nitrous oxide concentration detected by detection unit 40 is less than or equal to a second predetermined concentration (eg, 50 ppm), and if so, advances the process to step S104 , and if not, advances the process to step S105 .

[0081] In step S104, since the NOx concentration is below the first predetermined concentration and the nitrous oxide concentration is below the second predetermined concentration, the control unit 80 determines that the reduction treatment of NOx and nitrous oxide using ammonia is appropriately performed, and controls the first supply unit 50 to reduce the reducing agent supply amount.

[0082] In step S105, since the NOx concentration is higher than the first specified concentration, or the nitrous oxide concentration is higher than the second specified concentration, the control unit 80 determines that the reduction treatment of NOx and nitrous oxide using ammonia has not been fully performed, and controls the first supply unit 50 to increase the reducing agent supply amount, causing the process to enter step S101.

[0083] In step S106, the control unit 80 determines whether the combustion device 200 is stopped, and if so, advances the process to step S107, and if not, executes step S101 again. The combustion device 200 transmits the operating state including the state of stopping the combustion operation to the control unit 80.

[0084] In step S107, since the combustion device 200 is stopped, the control unit 80 determines that the reduction treatment of NOx and nitrous oxide by ammonia is not necessary, stops the supply of the reducing agent by the first supply unit 50, and ends the processing of this flowchart. When the combustion device 200 starts the combustion operation, the control unit 80 starts the processing of this flowchart again.

[0085] Next, refer to Figure 7 The switching process of the bypass valve 70 in the exhaust gas treatment device 100 of the present embodiment will be described. Figure 7 1 is a flowchart showing the switching process of the bypass valve 70 in the exhaust gas treatment device 100 according to the present embodiment. Figure 7 The processing of each step is executed by the control unit 80 controlling each unit of the exhaust gas treatment device 100. When the combustion operation by the combustion device 200 starts, the processing of this flowchart starts.

[0086] The exhaust gas treatment device 100 of the present embodiment is provided with an ammonia decomposition unit 30 on the downstream side of the nitrogen oxide decomposition unit 20. The ammonia decomposition unit 30 is provided, for example, to reliably decompose the remaining ammonia without discharging it to the outside when the ammonia concentration contained in the exhaust gas discharged from the combustion device 200 is higher than the pre-assumed concentration and is not completely decomposed in the ammonia decomposition unit 10 and the nitrogen oxide decomposition unit 20.

[0087] On the other hand, in the ammonia decomposition section 30, when the concentration of ammonia contained in the exhaust gas discharged from the nitrogen oxide decomposition section 20 is below the predetermined allowable concentration, it is not necessary to treat the exhaust gas by the ammonia decomposition section 30, and pressure loss occurs when the exhaust gas passes through the ammonia decomposition section 30. Therefore, in the present embodiment, when the concentration of ammonia contained in the exhaust gas discharged from the nitrogen oxide decomposition section 20 is below the predetermined allowable concentration, a part of the exhaust gas discharged from the nitrogen oxide decomposition section 20 is introduced into the pipe L5 to prevent the generation of pressure loss when the exhaust gas passes through the ammonia decomposition section 30.

[0088] In step S201, the control unit 80 determines whether the temperature Ta of the exhaust gas flowing through the pipe L2 transmitted from the temperature sensor 60 is above the supplyable temperature (for example, 350° C.) at which the reducing agent can be supplied to the nitrogen oxide decomposition unit 20. If so, the process proceeds to step S203; if not, the process proceeds to step S202.

[0089] In step S202, since the temperature Ta of the exhaust gas flowing through the piping L2 is lower than the possible supply temperature of the reducing agent to the nitrogen oxide decomposition section 20, and the temperature of the exhaust gas discharged from the combustion device 200 has not risen to an appropriate temperature, the control unit 80 controls the bypass valve 70 to be in a closed state.

[0090] In step S203 , the control unit 80 determines whether the load of the combustion device 200 is below a predetermined load (for example, 50% load), and if so, the process proceeds to step S204 , and if not, the process executes step S201 again. The combustion device 200 transmits the load of the combustion operation to the control unit 80 .

[0091] In step S204, since the load of the combustion device 200 is below the prescribed load, the control unit 80 controls the bypass valve 70 to be in an open state. When the load of the combustion device 200 is below the prescribed load, the concentration of ammonia contained in the exhaust gas discharged from the nitrogen oxide decomposition unit 20 is below the prescribed allowable concentration (for example, 5 ppm), and the exhaust gas does not need to be treated in the ammonia decomposition unit 30. Therefore, in order to reduce the pressure loss generated when the exhaust gas passes through the ammonia decomposition unit 30, a part of the exhaust gas flowing through the pipe L3 is introduced from the pipe L5 to the pipe L4.

[0092] In step S205, the control unit 80 determines whether the combustion device 200 is stopped, and if so, advances the process to step S206, and if not, executes step S201 again. The combustion device 200 transmits the operating state including the state of stopping the combustion operation to the control unit 80.

[0093] In step S206, since the combustion device 200 is stopped, the control unit 80 closes the bypass valve 70 and ends the process of this flowchart. When the combustion device 200 starts the combustion operation, the control unit 80 restarts the process of this flowchart.

[0094] In the above description, the detection unit 40 detects the concentration of nitrous oxide and NOx contained in the exhaust gas that has passed through the ammonia decomposition unit 10, but other schemes are also possible. The detection unit 40 may detect the concentration of either nitrous oxide or NOx contained in the exhaust gas that has passed through the ammonia decomposition unit 10. In the case where the detection unit 40 detects the concentration of nitrous oxide, the detection unit 40 may be omitted. Figure 6 In addition, when the detection unit 40 detects the concentration of NOx, Figure 6 The processing of step S103 is omitted.

[0095] [Examples of Ammonia Decomposition Catalyst]

[0096] The ammonia decomposition catalyst of the ammonia decomposition unit 10 of the present embodiment can be obtained by, for example, any of the following examples.

[0097] Example 1

[0098] In 1 liter, 1.33 × 10 －2 100 g of micro-particle silica powder (manufactured by Tomita Pharmaceutical Co., Ltd., silicic anhydride) was added to a wt% aqueous solution of chloroplatinic acid (H2〔PtCl6〕·6H2O), evaporated and dried on a sand bath, and calcined at 500°C in air for 2 hours to prepare 0.05wt% Pt·SiO2 and obtain a catalyst composition powder of the first component.

[0099] On the other hand, ammonium paratungstate (NH4) was added to 46.7 kg of titanium oxide powder (manufactured by Ishihara Sangyo Co., Ltd., trade name, MCH, SO4 content: 3 wt%). 10 ·W 12 O 41 ·5H2O) 7.43 kg, ammonium metavanadate 3.0 kg, kneaded using a kneader, granulated and dried the resulting paste, and calcined at 550°C for 2 hours. The resulting particles were crushed to obtain a catalyst composition powder as the second component. The composition was Ti / W / V = 91 / 5 / 4 (atomic ratio).

[0100] The slurry obtained by suspending 20g of the first component and 2.02kg of the second component in 3.06kg of water is impregnated in a paper honeycomb carrier (manufactured by NICHIAS Corporation, trade name, HONEYCLE 3722, 150mm×150mm square, length 50mm). After the slurry is impregnated in the carrier, it is deliquated by air blowing to obtain the catalyst of this embodiment. After air-drying it in the atmosphere for 12 hours, it is calcined at 500°C for 2 hours. The first component / second component ratio of the first component to the second component in this catalyst is 1 / 99 (weight ratio, the same below), the Pt content in the catalyst component is equivalent to 5ppm, and the catalyst loading is 150g / m per carrier surface area when the first component and the second component are added together. 2 . Five sections×8 cells (11×14 mm) and 50 mm in length were cut out from the obtained honeycomb catalyst to obtain test pieces.

[0101] Example 2

[0102] The catalyst of this example was obtained in the same manner as in Example 1 except that the first component of Example 1 was changed to 10 g, the second component was changed to 2.02 kg, and the water was changed to 3.04 kg. The first component / second component ratio of the first component to the second component in this catalyst was 0.5 / 99.5, the Pt content in the catalyst component was equivalent to 2.5 ppm, and the catalyst loading was 150 g / m per carrier surface area when the first component and the second component were added together. 2 .

[0103] Example 3-5

[0104] The first component and the second component obtained in Example 1 were used, and the amount of water added during slurry preparation was changed to 476 kg and 816 kg. The obtained slurry was loaded on a paper honeycomb carrier (manufactured by NICHIAS Corporation, trade name, HONEYCLE 3319, 150 mm × 150 mm square, 50 mm in length) in the same manner as in Example 1 to obtain the catalyst of this example. The first component / second component ratio of the first component to the second component in this catalyst is 1 / 99, and the Pt content in the catalyst component is equivalent to 5 ppm. The loading amount of the catalyst of Examples 3-5 is 100 g / m per carrier surface area when the first component and the second component are added together. 2 , 80g / m 2 , 50g / m 2 .

[0105] Example 6

[0106] The catalyst of this embodiment was obtained in the same manner as in Example 1 except that the paper honeycomb carrier of Example 1 was replaced with a metal mesh (SUS304, plate thickness 0.2 mmt, 150 mm×150 mm square). The first component / second component ratio of the first component to the second component in this catalyst was 1 / 99, and the Pt content in the catalyst component was equivalent to 5 ppm. The catalyst loading was 200 g / m per carrier surface area when the first component and the second component were added together. 2 .

[0107] Example 7

[0108] The catalyst of this example was prepared in the same manner except that the water used for preparing the slurry in Example 1 was changed to colloidal silica (manufactured by Nissan Chemical Co., Ltd., trade name, OS sol, SiO2 content 20%) / water = 3 / 7.

[0109] Example 8

[0110] 20 g of the first component prepared in Example 1 was suspended in 1000 g of a liquid of colloidal silica / water = 3 / 7, and a paper honeycomb carrier was immersed therein to immerse the carrier in the slurry, and then the liquid was removed by blowing, air-dried in the atmosphere for 12 hours, and then calcined at 500° C. for 2 hours. The obtained catalyst was impregnated in a slurry obtained by suspending 2.02 kg of the second component of Example 1 in 3.06 kg of water, and then the liquid was removed, air-dried, and calcined at 500° C. for 2 hours to prepare the catalyst of this example.

[0111] [Examples of Nitrogen Oxide Decomposition Catalyst]

[0112] The nitrogen oxide decomposition catalyst of the nitrogen oxide decomposition unit 20 of the present embodiment is, for example, any one of the following catalysts AE.

[0113] Catalyst A

[0114] (Supporting process (ion exchange))

[0115] 60 g of BEA type zeolite (SiO2 / Al2O3 ratio = 25) was put into 2000 ml of aqueous solution containing 13.2 g of iron (III) nitrate nonahydrate (Fe2(NO2)2·9H2O) heated to 80°C, and then stirred for 3 hours while maintaining the temperature at 80°C to obtain a slurry. The slurry was dehydrated using a suction funnel equipped with filter paper (No.5C). A specified amount of pure water was injected into the filter cake on the filter paper for washing. The washed filter cake was dried at 110°C for 12 hours and calcined at 500°C for 5 hours. The calcined product was crushed with a planetary ball mill to obtain a powdered Fe-loaded zeolite catalyst A.

[0116] (Honeycomb coating process)

[0117] The Fe-loaded zeolite catalyst A was added into pure water and then stirred to obtain a catalyst slurry. 2 The catalyst slurry was applied with a coating amount of . It was dried at 120° C. for 2 hours and then calcined at 500° C. for 2 hours to obtain a honeycomb catalyst A.

[0118] Catalyst B

[0119] Powdered Fe-supported zeolite catalyst B and honeycomb catalyst B were obtained by the same manufacturing method as catalyst A except that BEA type zeolite (SiO2 / Al2O3 ratio = 25) was replaced with BEA type zeolite (SiO2 / Al2O3 ratio = 28).

[0120] Catalyst C

[0121] Powdered Fe-supporting zeolite catalyst C and honeycomb catalyst C were obtained by the same manufacturing method as catalyst A except that BEA type zeolite (SiO2 / Al2O3 ratio = 25) was replaced with BEA type zeolite (SiO2 / Al2O3 ratio = 7.5).

[0122] Catalyst D

[0123] 60 g of CHA zeolite (SiO2 / Al2O3 ratio = 24) was placed in a 2000 ml aqueous solution containing 13.2 g of iron (III) nitrate nonahydrate (Fe2(NO3)3·9H2O) heated to 80°C, and then stirred for 3 hours while maintaining the temperature at 80°C to obtain a slurry. The slurry was filtered using a suction funnel equipped with filter paper (No.5C). A specified amount of pure water was injected into the filter cake on the filter paper to wash it. The washed filter cake was dried at 110°C for 12 hours and calcined at 500°C for 5 hours. The calcined product was crushed with a planetary ball mill to obtain a powder.

[0124] The powder was put into 2000 ml of an aqueous solution containing 13.2 g of iron (III) nitrate nonahydrate (Fe2(NO3)3·9H2O), and the above operation was further performed twice (a total of three ion exchange steps) to obtain a powdered Fe-loaded zeolite catalyst D. Honeycomb catalyst D was obtained by the same manufacturing method as catalyst A, except that Fe-loaded zeolite catalyst A was replaced with Fe-loaded zeolite catalyst D.

[0125] Catalyst E

[0126] Powdered Fe-supported zeolite catalyst E and honeycomb catalyst E were obtained by the same manufacturing method as catalyst A except that BEA type zeolite (SiO2 / Al2O3 ratio = 25) was replaced with MFI type zeolite (SiO2 / Al2O3 ratio = 30).

[0127] Catalyst F

[0128] Powdered Fe-supporting zeolite catalyst F and honeycomb catalyst F were obtained by the same manufacturing method as catalyst A except that BEA type zeolite (SiO2 / Al2O3 ratio = 25) was replaced with BEA type zeolite (SiO2 / Al2O3 ratio = 24).

[0129] The functions and effects of the exhaust gas treatment device 100 according to the present embodiment described above will be described.

[0130] According to the exhaust gas treatment device 100 of the present disclosure, ammonia contained in the exhaust gas discharged from the combustion device 200 is appropriately decomposed by the ammonia decomposition catalyst when passing through the ammonia decomposition unit 10. In addition, nitrous oxide and NOx generated when ammonia is burned in the combustion device 200 are appropriately decomposed by the nitrogen oxide decomposition catalyst when passing through the nitrogen oxide decomposition unit 20. In this way, according to the exhaust gas treatment device 100 of the present disclosure, ammonia and nitrous oxide contained in the exhaust gas discharged from the combustion device 200 that burns the fuel containing ammonia can be appropriately decomposed.

[0131] According to the exhaust gas treatment device 100 of the present embodiment, even when ammonia remains in the exhaust gas that has passed through the nitrogen oxide decomposition unit 20 , the ammonia is decomposed in the ammonia decomposition unit 30 , thereby preventing the ammonia from being discharged to the outside.

[0132] According to the exhaust gas treatment device 100 of the present embodiment, when the detection unit 40 detects that the concentration of dinitrogen monoxide contained in the exhaust gas passing through the nitrogen oxide decomposition unit 20 is higher than the first predetermined concentration, or the concentration of NOx contained in the exhaust gas passing through the nitrogen oxide decomposition unit 20 is higher than the second predetermined concentration, in order to supplement the shortage of ammonia for reducing dinitrogen monoxide and NOx, the reducing agent is supplied from the first supply unit 50 to the exhaust gas supplied to the nitrogen oxide decomposition unit 20. Therefore, the shortage of ammonia supplied from the ammonia decomposition unit 10 to the nitrogen oxide decomposition unit 20 can be supplemented, and the concentration of dinitrogen monoxide and the concentration of NOx contained in the exhaust gas passing through the nitrogen oxide decomposition unit 20 can be reduced.

[0133] [Second embodiment]

[0134] The exhaust gas treatment device 100A of the second embodiment of the present disclosure is described below with reference to the drawings. The exhaust gas treatment device 100A of this embodiment is a modified example of the exhaust gas treatment device 100 of the first embodiment, and is the same as the first embodiment except for the cases particularly described below, and the following description is omitted.

[0135] The exhaust gas treatment device 100B of the present embodiment is different from the exhaust gas treatment device 100 of the first embodiment in that it includes a pipe (bypass pipe) L7 for introducing a part of the exhaust gas flowing through the pipe L1 into the pipe L2 and a bypass valve 90 disposed in the pipe L7 .

[0136] Figure 8 1 is a schematic structural diagram showing an exhaust gas treatment device 100A according to a second embodiment of the present disclosure. Figure 8 As shown, the exhaust gas treatment device 100A of the present embodiment includes a pipe L7 for introducing a part of the exhaust gas flowing through the pipe L1 into the pipe L2 and a bypass valve 90 disposed in the pipe L7.

[0137] The bypass valve 90 is an on-off valve disposed in the pipe L7. The on-off state of the bypass valve 90 is controlled by the control unit 80. When the bypass valve 90 is in an open state, the exhaust gas is introduced from the pipe L1 to the pipe L2 via the pipe L7. When the bypass valve 90 is in a closed state, the exhaust gas is not introduced into the pipe L7, and the total amount of the exhaust gas flowing in the pipe L1 is introduced into the pipe L2 via the ammonia decomposition unit 10.

[0138] In the exhaust gas treatment device 100A of the present embodiment, when the supply amount of unburned ammonia contained in the exhaust gas discharged from the combustion device 200 exceeds the amount of ammonia required for decomposing nitrous oxide and NOx in the nitrogen oxide decomposition section 20, the bypass valve 90 is closed, the total amount of exhaust gas flowing in the piping L1 is introduced into the ammonia decomposition section 10, and the remaining ammonia is decomposed in the ammonia decomposition section 10.

[0139] On the other hand, in the exhaust gas treatment device 100A of the present embodiment, when the supply amount of unburned ammonia contained in the exhaust gas discharged from the combustion device 200 is the same as or lower than the amount of ammonia required for decomposing nitrous oxide and NOx in the nitrogen oxide decomposition section 20, the bypass valve 90 is opened to introduce a part of the exhaust gas flowing in the piping L1 without passing through the ammonia decomposition section 10 into the piping L2.

[0140] Next, refer to Fig. 9 The switching process of the bypass valve 90 of the exhaust gas treatment device 100A according to the present embodiment will be described. Fig. 9 1 is a flowchart showing the switching process of the bypass valve 90 of the exhaust gas treatment device 100A according to the present embodiment. Fig. 9 The processing of each step is executed by the control unit 80 controlling each unit of the exhaust gas treatment device 100A. When the combustion operation by the combustion device 200 starts, the processing of this flowchart starts.

[0141] In step S301, the control unit 80 determines whether the temperature Ta of the exhaust gas flowing through the pipe L2 transmitted from the temperature sensor 60 is above the supplyable temperature (for example, 350° C.) at which the reducing agent can be supplied to the nitrogen oxide decomposition unit 20. If so, the process proceeds to step S302; if not, the process proceeds to step S305.

[0142] In step S302, the control unit 80 calculates the concentration of each component of ammonia, nitrous oxide, and NOx in the exhaust gas discharged from the combustion device 200 based on the load of the combustion device 200. The combustion device 200 transmits the load of the combustion operation to the control unit 80. The control unit 80 stores the map of the concentration of each component of ammonia, nitrous oxide, and NOx corresponding to the multiple loads of the combustion device 200 in the storage unit (not shown). The control unit 80 refers to the map stored in the storage unit to calculate the concentration corresponding to the load transmitted from the combustion device 200.

[0143] In step S303, the control unit 80 determines whether the ammonia concentration calculated in step S302 is equal to or less than a predetermined concentration, and if so, advances the process to step S304, and if not, advances the process to step S305. Here, the predetermined concentration is the concentration represented by the following formula (12).

[0144] α·nitrous oxide concentration+β·NOx concentration(12)

[0145] Here, α and β are coefficients, and for example, α=1.0, which is the same as described in the formula (11) of the first embodiment.

[0146] In step S304 , since the ammonia concentration is equal to or less than the predetermined concentration, it is not necessary to supply the total amount of exhaust gas to the ammonia decomposition unit 10 in order to decompose the excess ammonia in the ammonia decomposition unit 10 , and thus the controller 80 opens the bypass valve 90 .

[0147] In step S305, the temperature Ta of the exhaust gas is lower than the supplyable temperature of the reducing agent to the nitrogen oxide decomposition unit 20, or the ammonia concentration is higher than the prescribed concentration, so the control unit 80 closes the bypass valve 90. This is because the temperature of the exhaust gas discharged from the combustion device 200 is not sufficiently increased, or the ammonia concentration contained in the exhaust gas is higher than the prescribed concentration, so the total amount of the exhaust gas needs to be supplied to the ammonia decomposition unit 10.

[0148] In step S306, the control unit 80 determines whether the combustion device 200 is stopped, and if so, advances the process to step S307, and if not, executes step S301 again. The combustion device 200 transmits the operating state including the state of stopping the combustion operation to the control unit 80.

[0149] In step S307, since the combustion device 200 is stopped, the control unit 80 closes the bypass valve 90 and ends the process of this flowchart. When the combustion device 200 starts the combustion operation, the control unit 80 restarts the process of this flowchart.

[0150] The functions and effects of the exhaust gas treatment device 100B according to the present embodiment described above will be described.

[0151] According to the exhaust gas treatment device 100A of the present embodiment, when the concentration of ammonia contained in the exhaust gas discharged from the combustion device 200 is higher than the concentration required as a reducing agent when decomposing nitrous oxide and NOx in the nitrogen oxide decomposition section 20, the bypass valve 90 is closed, and the remaining ammonia can be decomposed in the ammonia decomposition section 10. In addition, when the concentration of ammonia contained in the exhaust gas discharged from the combustion device 200 is the same as or lower than the concentration required as a reducing agent when decomposing nitrous oxide and NOx in the nitrogen oxide decomposition section 20, the bypass valve 90 is opened, and ammonia can be introduced into the nitrogen oxide decomposition section 20 without being decomposed in the ammonia decomposition section 10.

[0152] [Third embodiment]

[0153] The exhaust gas treatment device 100B of the second embodiment of the present disclosure is described below with reference to the drawings. The exhaust gas treatment device 100B of this embodiment is a modified example of the exhaust gas treatment device 100 of the first embodiment, and is the same as the first embodiment except for the cases particularly described below, and the following description is omitted.

[0154] The exhaust gas treatment device 100 of the first embodiment arranges the ammonia decomposition unit 10 on the upstream side of the nitrogen oxide decomposition unit 20 . In contrast, the exhaust gas treatment device 100B of the present embodiment does not arrange the ammonia decomposition unit 10 on the upstream side of the nitrogen oxide decomposition unit 20 .

[0155] Fig.10 1 is a schematic structural diagram showing an exhaust gas treatment device 100B according to a third embodiment of the present disclosure. Fig.10 As shown, in the exhaust gas treatment device 100B of the present embodiment, the ammonia decomposition unit 10 is not disposed on the upstream side of the nitrogen oxide decomposition unit 20, and the exhaust gas discharged from the combustion device 200 is supplied to the nitrogen oxide decomposition unit 20 via the pipe L1.

[0156] In the present embodiment, the ammonia decomposition unit 10 is not provided on the upstream side of the nitrogen oxide decomposition unit 20 because it is assumed that the supply amount of unburned ammonia contained in the exhaust gas discharged from the combustion device 200 is the same as or lower than the amount of ammonia required for decomposing nitrous oxide and NOx in the nitrogen oxide decomposition unit 20. The exhaust gas treatment device 100B of the present embodiment supplies the insufficient amount of ammonia required as a reducing agent for decomposing nitrous oxide and NOx contained in the exhaust gas from the first supply unit 50 to make up for it.

[0157] In the exhaust gas treatment device 100B of the present embodiment, it is assumed that the concentrations of ammonia, nitrous oxide, and NOx contained in the exhaust gas exhausted from the combustion device 200 satisfy the following formula (13), respectively.

[0158] Ammonia concentration ≤ α·nitrous oxide concentration + β·NOx concentration (13)

[0159] Here, α and β are coefficients, which are the same as those described in the formula (11) of the first embodiment.

[0160] The supply process of the reducing agent in the exhaust gas treatment device 100B of this embodiment is different from that of the first embodiment. Figure 6 The switching process of the bypass valve 70 in the exhaust gas treatment device 100A of this embodiment is the same as that of the first embodiment. Figure 7 The processing shown is the same.

[0161] The functions and effects of the exhaust gas treatment device 100B according to the present embodiment described above will be described.

[0162] According to the exhaust gas treatment device 100B of the present embodiment, ammonia contained in the exhaust gas discharged from the combustion device 200 is decomposed by the nitrogen oxide decomposition catalyst as a reducing agent reacting with nitrous oxide and NOx when passing through the nitrogen oxide decomposition unit 20. In addition, nitrous oxide and NOx generated when ammonia is burned in the combustion device 200 are appropriately decomposed by the nitrogen oxide decomposition catalyst when passing through the nitrogen oxide decomposition unit 20. In this way, according to the exhaust gas treatment device 100B of the present embodiment, ammonia, nitrous oxide and NOx contained in the exhaust gas discharged from the combustion device 200 that burns the fuel containing ammonia can be appropriately decomposed.

[0163] [Fourth embodiment]

[0164] The following describes a design method for an exhaust gas treatment device according to a fourth embodiment of the present disclosure. The design method of this embodiment is a method for determining whether to perform a design in which the ammonia decomposition unit 10 is arranged on the upstream side of the nitrogen oxide decomposition unit 20 as in the exhaust gas treatment device 100 and 100A described in the first and second embodiments, or a design in which the ammonia decomposition unit 10 is not arranged on the upstream side of the nitrogen oxide decomposition unit 20 as in the exhaust gas treatment device 100B described in the third embodiment.

[0165] Fig.11 This is a flowchart showing a method for designing the exhaust gas treatment device according to the present embodiment.

[0166] In step S401, the concentration of each component of ammonia, nitrous oxide, and NOx in the exhaust gas discharged from the combustion device 200 is calculated. The concentration of each component is assumed to be the concentration when the combustion device 200 operates at a predetermined constant load, and the concentration of each component of ammonia, nitrous oxide, and NOx in the exhaust gas under the load is determined.

[0167] In step S402, it is determined whether the ammonia concentration calculated in step S401 is less than or equal to a predetermined concentration. If so, the process proceeds to step S403, and if not, the process proceeds to step S404. Here, the predetermined concentration is the concentration represented by equation (12) of the second embodiment, which is α·nitrous oxide concentration + β·NOx concentration.

[0168] In step S403, since the ammonia concentration in the exhaust gas discharged from the combustion device 200 is below the predetermined concentration, the design of the exhaust gas treatment device 100B of the third embodiment is adopted in which the ammonia decomposition unit 10 is not arranged on the upstream side of the nitrogen oxide decomposition unit 20. This design is adopted because it is not necessary to arrange the ammonia decomposition unit 10 on the upstream side of the nitrogen oxide decomposition unit 20 to decompose the excess ammonia.

[0169] In step S404, since the ammonia concentration in the exhaust gas discharged from the combustion device 200 is higher than the predetermined concentration, the design of the exhaust gas treatment device 100 of the first embodiment or the exhaust gas treatment device 100A of the second embodiment is adopted in which the ammonia decomposition unit 10 is arranged on the upstream side of the nitrogen oxide decomposition unit 20. Such a design is adopted because, since the ammonia concentration contained in the exhaust gas is higher than the predetermined concentration, the total amount of the exhaust gas needs to be supplied to the ammonia decomposition unit 10 to decompose the excess ammonia.

[0170] According to the design method of the exhaust gas treatment device of the present embodiment, when the concentration of ammonia contained in the exhaust gas is higher than the total concentration of a first concentration obtained by multiplying the concentration of nitrous oxide contained in the exhaust gas by α (first coefficient) and a second concentration obtained by multiplying the concentration of NOx contained in the exhaust gas by β (second coefficient), in order to prevent the concentration of ammonia supplied from the ammonia decomposition section 10 to the nitrogen oxide decomposition section 20 from being excessive, the exhaust gas treatment device is designed in such a manner that the ammonia decomposition section 10 is arranged on the downstream side of the combustion device 200, and the nitrogen oxide decomposition section 20 is arranged on the downstream side of the ammonia decomposition section 10.

[0171] On the other hand, when the concentration of ammonia contained in the exhaust gas is less than the total concentration of the first concentration obtained by multiplying the concentration of nitrous oxide contained in the exhaust gas by α (first coefficient) and the second concentration obtained by multiplying the concentration of NOx contained in the exhaust gas by β (second coefficient), the concentration of ammonia supplied from the ammonia decomposition unit 10 to the nitrogen oxide decomposition unit 20 does not become excessive, so the exhaust gas treatment device is designed in such a way that the nitrogen oxide decomposition unit 20 is arranged instead of the ammonia decomposition unit 10 on the downstream side of the combustion device 200. As a result, it is possible to design an exhaust gas treatment device with an appropriate structure corresponding to the concentration of ammonia contained in the exhaust gas discharged from the combustion device 200.

[0172] [Fifth embodiment]

[0173] Next, an exhaust gas treatment device 100C according to a fifth embodiment of the present disclosure will be described with reference to the drawings. The exhaust gas treatment device 100C of this embodiment is a modified example of the exhaust gas treatment device 100 of the first embodiment, and is the same as the first embodiment except for the cases particularly described below, and the following description is omitted.

[0174] The exhaust gas treatment device 100C of this embodiment is different from the exhaust gas treatment device 100 of the first embodiment in that it is provided with a second supply unit 55 that supplies ammonia or urea water as a fuel for heating the ammonia decomposition catalyst (first treatment unit) of the ammonia decomposition unit 10 to the exhaust gas supplied from the combustion device 200 to the ammonia decomposition unit 10. In addition, the exhaust gas treatment device 100C of this embodiment is different from the exhaust gas treatment device 100 of the first embodiment in that it does not include the ammonia decomposition unit 30.

[0175] Fig.12 1 is a schematic diagram showing the structure of an exhaust gas treatment device 100C according to this embodiment. Fig.12 As shown, the exhaust gas treatment device 100C of the present embodiment includes an ammonia decomposition unit (first treatment unit) 10, a nitrogen oxide decomposition unit (second treatment unit) 20, a detection unit 40, a first supply unit 50, a second supply unit 55, a temperature sensor 60, and a control unit 80. The other structures except the second supply unit 55 are the same as those of the first embodiment, so the following description is omitted.

[0176] The second supply unit 55 is a device that supplies ammonia or urea water as a fuel for heating the ammonia decomposition catalyst to the exhaust gas supplied from the combustion device 200 to the ammonia decomposition unit 10 when the temperature detected by the temperature sensor 60 is below a predetermined temperature. The second supply unit 55 supplies urea water to the pipe L1 via the pipe L8, and generates ammonia by a hydrolysis reaction of the urea water.

[0177] The ammonia introduced into the ammonia decomposition unit 10 is decomposed by the ammonia decomposition catalyst through the reaction of the formula (1) and (2) of the first embodiment. The exhaust gas passing through the ammonia decomposition unit 10 is heated by the exothermic reaction during the decomposition of ammonia. In addition, instead of supplying urea water from the second supply unit 55, ammonia may be supplied from the second supply unit 55 to the pipe L2.

[0178] The inventors and others have experimentally confirmed the relationship between the properties of the exhaust gas discharged from the combustion device 200 and the decomposition rate of dinitrogen monoxide, and as a result, have obtained the following insights: there is a temperature zone in which the decomposition rate of dinitrogen monoxide changes according to the concentration of NO contained in the exhaust gas. If the decomposition rate of dinitrogen monoxide changes according to the concentration of NO contained in the exhaust gas, it is possible that the desired decomposition rate of dinitrogen monoxide cannot be obtained in the exhaust gas treatment device 100 of the first embodiment. Therefore, the exhaust gas treatment device 100C of this embodiment operates the nitrogen oxide decomposition unit 20 within a temperature range in which the decomposition rate of dinitrogen monoxide does not change according to the concentration of NO contained in the exhaust gas.

[0179] Fig.13 This is a graph showing the decomposition rate of nitrous oxide in the nitrogen oxide decomposition unit 20 with respect to the temperature of the exhaust gas, and comparing the case where the NO concentration is 0 ppm and the case where the NO concentration is 450 ppm. Fig.13 This is an example in which the catalyst A is used as the nitrogen oxide decomposition catalyst of the nitrogen oxide decomposition unit 20 . Fig.13 The example shown by the solid line is different from the example shown by the dotted line in that the NO concentration in the exhaust gas is 450 ppm and 0 ppm. Fig.13 The example shown by the solid line and the example shown by the dotted line have in common that the concentration of nitrous oxide in the exhaust gas is 180 ppm, the concentration of ammonia in the exhaust gas is 570 ppm, the concentration of oxygen in the exhaust gas is 13%, the concentration of sulfur dioxide in the exhaust gas is 15 ppm, the concentration of water in the exhaust gas is 15%, and the rest is nitrogen.

[0180] like Fig.13As shown in FIG. 1 , if the temperature of the exhaust gas is around 450°C, there is almost no difference in the decomposition rate of dinitrogen monoxide even if the NO concentration in the exhaust gas is 450 ppm and 0 ppm. On the other hand, as the temperature of the exhaust gas is lower than 450°C, the difference in the decomposition rate of dinitrogen monoxide becomes larger. Specifically, at the same exhaust gas temperature, the decomposition rate of dinitrogen monoxide when the NO concentration in the exhaust gas is 0 ppm is lower than the decomposition rate of dinitrogen monoxide when the NO concentration in the exhaust gas is 450 ppm.

[0181] Speculation Fig.13 The reason for showing the above tendency is that the oxygen bonded to the nitrogen oxide decomposition catalyst in the following formula (11) is removed by the oxygen bonded by the formula (12) in the temperature range below 450° C. and / or the nitrous oxide is reduced by the reaction of the formula (13). That is, it is presumed that the decomposition rate of the nitrous oxide increases because NO in the exhaust gas exists together with the nitrous oxide.

[0182] 2N2O→2N2+3O2 (11)

[0183] 4NO+4NH3+O2→4N2+6H2O (12)

[0184] N2O+NO→N2+NO2 (13)

[0185] The inventors considered the above Fig.13 The experimental results shown in the figure set the temperature range so that the temperature of the exhaust gas discharged from the ammonia decomposition unit 10 is 450°C or higher so that the decomposition rate of nitrous oxide does not change depending on the concentration of NO contained in the exhaust gas. In addition, in order to reduce the thermal stress on the catalyst reactor and suppress the thermal aging of the catalyst, the inventors set the temperature range so that the temperature of the exhaust gas discharged from the ammonia decomposition unit 10 is 530°C or lower.

[0186] Next, refer to Figures 14 to 16 The supply process of the fuel and the reducing agent in the exhaust gas treatment device 100C of the present embodiment will be described. Figures 14 to 16 100C is a flowchart showing the supply process of the fuel and the reducing agent in the exhaust gas treatment device 100C of the present embodiment. Figures 14 to 16 The processing of each step is executed by the control unit 80 controlling each unit of the exhaust gas treatment device 100C. When the combustion operation by the combustion device 200 starts, the processing of this flowchart starts.

[0187] In step S401, the control unit 80 determines whether the temperature Ta of the exhaust gas flowing through the piping L2 transmitted from the temperature sensor 60 is above the fuel supply possible temperature (for example, 300° C.) at which the fuel for heating the ammonia decomposition catalyst (first treatment unit) can be supplied from the second supply unit 55 to the ammonia decomposition unit 10. If so, the process proceeds to step S402; if not, the process proceeds to step S403.

[0188] In step S402, the control unit 80 controls the second supply unit 55 to increase the amount of fuel supplied to the pipe L1. When step S402 is first executed after step S401, the amount of fuel supplied by the second supply unit 55 is increased from 0 to a predetermined amount.

[0189] In step S403 , since the temperature Ta of the exhaust gas flowing through the pipe L1 is lower than the fuel supplyable temperature at which fuel can be supplied to the ammonia decomposition unit 10 , the control unit 80 performs control to stop the supply of fuel by the second supply unit 55 .

[0190] In step S404, the control unit 80 determines whether the temperature Ta of the exhaust gas is above the possible reducing agent supply temperature (for example, 450° C.) at which the reducing agent can be supplied to the nitrogen oxide decomposition unit 20. If so, the processing proceeds to step S405. If not, the processing proceeds to step S402 to increase the supply amount of fuel from the second supply unit 55.

[0191] In step S405, the control unit 80 controls the first supply unit 50 to increase the amount of reducing agent supplied from the first supply unit 50 to the pipe L2. When step S405 is first executed after step S404, the amount of reducing agent supplied by the first supply unit 50 is increased from 0 to a predetermined amount.

[0192] In step S406 , the control unit 80 determines whether the NOx concentration detected by the detection unit 40 is less than or equal to a first predetermined concentration (eg, 200 ppm), and if so, proceeds to step S407 , and if not, proceeds to step S414 .

[0193] In step S407 , the control unit 80 determines whether the nitrous oxide concentration detected by the detection unit 40 is less than or equal to a second predetermined concentration (eg, 10 ppm), and if so, proceeds to step S408 ; if not, proceeds to step S414 .

[0194] In step S408, the control unit 80 controls the combustion device 200 in a manner to release the load restriction of the combustion device 200. The control unit 80 controls the combustion device 200 so that the load becomes less than the prescribed load until the load restriction is released in this step. This is because when the combustion device 200 is operated without setting a restriction on the load, if the supply amount of the reducing agent supplied from the first supply unit 50 to the nitrogen oxide decomposition unit 20 in order to reduce the NOx concentration and the nitrous oxide concentration is excessive, unreacted ammonia may be discharged from the nitrogen oxide decomposition unit 20 to the outside through the pipe L3.

[0195] By controlling the combustion device 200 to be below the specified load before releasing the load restriction in this step, unreacted ammonia can be prevented from being discharged to the outside from the nitrogen oxide decomposition unit 20 through the piping L3, and the NOx concentration and the nitrous oxide concentration can be kept below the threshold, thereby reducing the environmental load.

[0196] In step S409 , the control unit 80 determines whether the temperature Ta is lower than or equal to a first upper limit temperature (eg, 480° C.), and if so, proceeds to step S410 , and if not, proceeds to step S411 .

[0197] In step S410, the control unit 80 reduces the amount of fuel supplied from the second supply unit 55 to the pipe L1 so that the temperature Ta is lower than the first upper limit temperature. After executing step S410, the control unit 80 advances the process to step S404.

[0198] In step S411, since the temperature Ta is lower than the first upper limit temperature, the control unit 80 reduces the amount of the reducing agent supplied from the first supply unit 50 to the pipe L2 and advances the process to step S412.

[0199] In step S412, the control unit 80 determines whether the combustion device 200 is stopped, and if so, advances the process to step S413, and if not, executes step S404 again. The combustion device 200 transmits the operating state including the state of stopping the combustion operation to the control unit 80.

[0200] In step S413, since the combustion device 200 is stopped, the control unit 80 stops the supply of the reducing agent by the first supply unit 50 and the supply of the fuel by the second supply unit 55, and ends the process of this flowchart. When the combustion device 200 starts the combustion operation, the control unit 80 restarts the process of this flowchart.

[0201] In step S414, the control unit 80 performs Fig. 9The NOx concentration and the nitrous oxide concentration calculated in step S302 are used to calculate the amount of reducing agent required for the reduction treatment of NOx and nitrous oxide, and it is determined whether the amount of reducing agent supplied is more than the amount obtained by multiplying the required amount of reducing agent by a predetermined coefficient γ. If so, the process proceeds to step S415, and if not, the process proceeds to step S405. Here, the prescribed reducing agent supply amount is the supply amount obtained by multiplying the prescribed coefficient γ by the amount of reducing agent required for the reduction treatment of NOx and nitrous oxide included in the total concentration of nitrogen oxides. The coefficient γ is set to a value of, for example, 0.8 or more and 1.2 or less.

[0202] In step S415 , the control unit 80 determines whether the temperature Ta is lower than or equal to the second upper limit temperature (eg, 530° C.), and if so, proceeds to step S416 , and if not, proceeds to step S417 .

[0203] In step S416, the control unit 80 increases the amount of fuel supplied to the pipe L1 from the second supply unit 55. After executing step S416, the control unit 80 advances the process to step S419.

[0204] In step S417, the control unit 80 reduces the amount of fuel supplied from the second supply unit 55 to the pipe L1 so that the temperature Ta becomes lower than the second upper limit temperature.

[0205] In step S418 , the control unit 80 reduces the output of the combustion device 200 (for example, reduces the load by 10%), and proceeds to step S404 .

[0206] In step S419, the control unit 80 determines whether the combustion device 200 is stopped, and if so, advances the process to step S420, and if not, executes step S405 again. The combustion device 200 transmits the operating state including the state of stopping the combustion operation to the control unit 80.

[0207] In step S420, since the combustion device 200 is stopped, the control unit 80 stops the supply of the reducing agent by the first supply unit 50 and the supply of the fuel by the second supply unit 55, and ends the process of this flowchart. When the combustion device 200 starts the combustion operation, the control unit 80 restarts the process of this flowchart.

[0208] In the above description, fuel is supplied from the second supply unit 55 to generate ammonia by exothermic reaction using the ammonia decomposition catalyst of the ammonia decomposition unit 10 , but other schemes are also possible. For example, ammonia or urea water may be supplied from the first supply unit 50 to the pipe L1 .

[0209] According to the exhaust gas treatment device 100C of the present embodiment, by supplying ammonia or urea water to the exhaust gas supplied from the combustion device 200 to the ammonia decomposition unit 10, it is possible to promote the exothermic reaction based on the oxidation of ammonia in the ammonia decomposition unit 10. As a result, the temperature of the exhaust gas introduced from the ammonia decomposition unit 10 to the nitrogen oxide decomposition unit 20 can be appropriately increased, and the nitrogen oxide decomposition unit 20 can be operated within a temperature range in which the decomposition rate of nitrous oxide does not change depending on the concentration of NO contained in the exhaust gas.

[0210] Furthermore, according to the exhaust gas treatment device 100C of this embodiment, by setting the predetermined temperature to 450° C. to 530° C., the nitrogen oxide decomposition unit 20 can be operated within an appropriate temperature range in which the decomposition rate of nitrous oxide does not change depending on the concentration of NO contained in the exhaust gas.

[0211] It should be noted that the exhaust gas treatment device 100C of this embodiment discharges the exhaust gas that has passed through the nitrogen oxide decomposition unit 20 to the outside through the pipe L3, but other schemes are also possible. Fig.17 As in the exhaust gas treatment device 100D of the illustrated modification, the exhaust gas having passed through the nitrogen oxide decomposition section 20 is introduced into the ammonia decomposition section 30, and the exhaust gas having passed through the ammonia decomposition section 30 is discharged to the outside through the pipe L4.

[0212] Fig.17 It is a schematic configuration diagram showing an exhaust gas treatment device 100D according to a modified example of the fifth embodiment of the present disclosure. Fig.17 The ammonia decomposition unit 30 shown has the same structure as the ammonia decomposition unit 30 of the first embodiment. Fig.17 The exhaust gas treatment device 100D shown can appropriately decompose the ammonia in the ammonia decomposition section 30 without discharging the ammonia to the outside, even if the exhaust gas having passed through the nitrogen oxide decomposition section 20 contains ammonia.

[0213] In addition, Fig.17 In the exhaust gas treatment device 100D shown in the figure, ammonia is appropriately decomposed in the ammonia decomposition unit 30, so there is no need to Fig.15 In order to eliminate the need for load restriction or reduce the frequency of load restriction, in step S414, relative to the load restriction of the combustion device 200 before step S408, Fig. 9 The NOx concentration and the nitrous oxide concentration calculated in step S302 are used to calculate the reducing amount required for the reduction treatment of NOx and nitrous oxide, and the coefficient γ multiplied by the required reducing amount is set to a larger value (for example, 1.5) than that in the fifth embodiment.

[0214] The exhaust gas treatment device and the design method of the exhaust gas treatment device described in each embodiment described above can be understood as follows, for example.

[0215] The exhaust gas treatment device (100) disclosed herein is an exhaust gas treatment device (100, 100A) for treating exhaust gas discharged from a combustion device (200) that burns a fuel containing ammonia, wherein the exhaust gas treatment device comprises: a first treatment section (10) having a first catalyst for decomposing ammonia contained in the exhaust gas; and a second treatment section (20) having a second catalyst for decomposing nitrous oxide and NOx contained in the exhaust gas in which ammonia has been decomposed in the first treatment section.

[0216] According to the exhaust gas treatment device disclosed in the present invention, ammonia contained in the exhaust gas discharged from the combustion device is appropriately decomposed by the first catalyst when passing through the first treatment unit. In addition, nitrous oxide and NOx generated when ammonia is burned in the combustion device are appropriately decomposed by the second catalyst when passing through the second treatment unit. In this way, according to the exhaust gas treatment device disclosed in the present invention, ammonia, nitrous oxide and NOx contained in the exhaust gas discharged from the combustion device that burns the fuel containing ammonia can be appropriately decomposed.

[0217] In the exhaust gas treatment device of the present disclosure, the first treatment unit may be configured to remove NOx generated when decomposing ammonia contained in the exhaust gas using the first catalyst.

[0218] According to the exhaust gas treatment device of this configuration, NOx generated when ammonia is decomposed in the first treatment section is removed by the first catalyst, so that NOx contained in the exhaust gas exhausted from the combustion device can be appropriately prevented from increasing when passing through the first treatment section.

[0219] The exhaust gas treatment device of the present disclosure may be configured to include: a bypass pipe (L7) for introducing the exhaust gas discharged from the combustion device into the second treatment section without passing through the first treatment section; and a bypass valve (90) disposed on the bypass pipe.

[0220] According to the exhaust gas treatment device of this structure, when the concentration of ammonia contained in the exhaust gas discharged from the combustion device is higher than the concentration required as a reducing agent when decomposing nitrous oxide and NOx in the second treatment section, the bypass valve is closed, and the remaining ammonia can be decomposed in the first treatment section. In addition, when the concentration of ammonia contained in the exhaust gas discharged from the combustion device is the same as or lower than the concentration required as a reducing agent when decomposing nitrous oxide and NOx in the second treatment section, the bypass valve is opened, and ammonia can be introduced into the second treatment section without being decomposed in the first treatment section.

[0221] The exhaust gas treatment device of the present disclosure may be configured to include a third treatment section (30) for decomposing ammonia contained in the exhaust gas having passed through the second treatment section.

[0222] According to the exhaust gas treatment device of this configuration, even when ammonia remains in the exhaust gas that has passed through the second treatment section, the ammonia can be prevented from being discharged to the outside by decomposing the ammonia in the third treatment section.

[0223] In the exhaust gas treatment device disclosed in the present invention, it can be constructed to include: a detection unit (40) which detects the concentration of nitrous oxide and / or NOx contained in the exhaust gas that has passed through the second treatment unit; and a first supply unit (50) which supplies ammonia or urea water to the exhaust gas supplied from the first treatment unit to the second treatment unit when the concentration of nitrous oxide contained in the exhaust gas is higher than a first specified concentration or the concentration of NOx contained in the exhaust gas is higher than a second specified concentration, and the second catalyst is a catalyst that uses ammonia to reduce and decompose the nitrous oxide and NOx contained in the exhaust gas.

[0224] According to the exhaust gas treatment device of this structure, when the detection unit detects that the concentration of dinitrogen monoxide contained in the exhaust gas passing through the second treatment unit is higher than the first specified concentration, or the concentration of NOx contained in the exhaust gas passing through the second treatment unit is higher than the second specified concentration, in order to supplement the shortage of ammonia for reducing dinitrogen monoxide and NOx, ammonia or urea water is supplied as a reducing agent from the first supply unit to the exhaust gas supplied to the second treatment unit. Therefore, the shortage of ammonia supplied from the first treatment unit to the second treatment unit can be supplemented, and the concentration of dinitrogen monoxide and NOx contained in the exhaust gas passing through the second treatment unit can be reduced.

[0225] In the exhaust gas treatment device disclosed in the present invention, it can be constructed to include: a temperature detection unit, which detects the temperature of the exhaust gas discharged from the first treatment unit; and a second supply unit (55), which supplies ammonia or urea water to the exhaust gas supplied from the combustion device to the first treatment unit when the temperature detected by the temperature detection unit is below a specified temperature.

[0226] According to the exhaust gas treatment device of this structure, by supplying ammonia or urea water to the exhaust gas supplied from the combustion device to the first treatment unit, the exothermic reaction caused by the decomposition of ammonia in the first treatment unit can be promoted. As a result, the temperature of the exhaust gas introduced from the first treatment unit to the second treatment unit can be appropriately increased, and the nitrogen oxide decomposition unit can be operated within a temperature range in which the decomposition rate of nitrous oxide does not change according to the concentration of NO contained in the exhaust gas.

[0227] The exhaust gas treatment device of the present disclosure may be configured to include a third treatment section (30) for decomposing ammonia contained in the exhaust gas having passed through the second treatment section.

[0228] According to the exhaust gas treatment device of this configuration, even if ammonia is contained in the exhaust gas having passed through the second treatment section, the ammonia can be appropriately decomposed in the third treatment section without being discharged to the outside.

[0229] In the exhaust gas treatment device of the present disclosure, the predetermined temperature may be a temperature of 450° C. or higher and 530° C. or lower.

[0230] According to the exhaust gas treatment device of this configuration, by setting the predetermined temperature to 450° C. or higher and 530° C. or lower, the nitrogen oxide decomposition unit can be operated within an appropriate temperature range in which the decomposition rate of nitrous oxide does not change depending on the concentration of NO contained in the exhaust gas.

[0231] The exhaust gas treatment device disclosed herein is an exhaust gas treatment device (100B) for treating exhaust gas discharged from a combustion device that burns a fuel containing ammonia, wherein the exhaust gas treatment device comprises: a first supply unit (50) that supplies ammonia as a reducing agent to the exhaust gas discharged from the combustion device; a nitrogen oxide decomposition unit (20) having a decomposition catalyst, the decomposition catalyst using the ammonia supplied from the ammonia supply unit to reduce nitrous oxide and NOx contained in the exhaust gas; and an ammonia decomposition unit (30) that decomposes the ammonia contained in the exhaust gas that has passed through the nitrogen oxide decomposition unit.

[0232] According to the exhaust gas treatment device disclosed in the present invention, ammonia contained in the exhaust gas discharged from the combustion device is decomposed by the decomposition catalyst as a reducing agent reacting with nitrous oxide and NOx when passing through the nitrogen oxide decomposition unit. In addition, nitrous oxide and NOx generated when ammonia is burned in the combustion device are appropriately decomposed by the decomposition catalyst when passing through the nitrogen oxide decomposition unit. In this way, according to the exhaust gas treatment device disclosed in the present invention, ammonia, nitrous oxide and NOx contained in the exhaust gas discharged from the combustion device burning a fuel containing ammonia can be appropriately decomposed.

[0233] The design method of the exhaust gas treatment device disclosed in the present invention is a design method of the exhaust gas treatment device for treating exhaust gas discharged from a combustion device that burns a fuel containing ammonia, wherein, when the concentration of ammonia contained in the exhaust gas is higher than the total concentration of a first concentration obtained by multiplying the concentration of nitrous oxide contained in the exhaust gas by a first coefficient and a second concentration obtained by multiplying the concentration of NOx contained in the exhaust gas by a second coefficient, the exhaust gas treatment device is designed in a manner that a first treatment section having a first catalyst for decomposing ammonia contained in the exhaust gas is arranged on the downstream side of the combustion device, and a second treatment section having a second catalyst for decomposing nitrous oxide and NOx contained in the exhaust gas in which ammonia has been decomposed in the first treatment section is arranged on the downstream side of the first treatment section, and when the concentration of ammonia contained in the exhaust gas is lower than the total concentration, the exhaust gas treatment device is designed in a manner that the first treatment section is not arranged on the downstream side of the combustion device and the second treatment section is arranged.

[0234] According to the design method of the exhaust gas treatment device disclosed in the present invention, when the concentration of ammonia contained in the exhaust gas is higher than the total concentration of a first concentration obtained by multiplying the concentration of nitrous oxide contained in the exhaust gas by a first coefficient and a second concentration obtained by multiplying the concentration of NOx contained in the exhaust gas by a second coefficient, in order to prevent an excessive concentration of ammonia supplied from the first treatment section to the second treatment section, the exhaust gas treatment device is designed in such a manner that the first treatment section is arranged on the downstream side of the combustion device, and the second treatment section is arranged on the downstream side of the first treatment section.

[0235] On the other hand, when the concentration of ammonia contained in the exhaust gas is less than the total concentration of the first concentration obtained by multiplying the concentration of nitrous oxide contained in the exhaust gas by the first coefficient and the second concentration obtained by multiplying the concentration of NOx contained in the exhaust gas by the second coefficient, the concentration of ammonia supplied from the first treatment unit to the second treatment unit will not be excessive, so the exhaust gas treatment device is designed in such a way that the first treatment unit is not arranged on the downstream side of the combustion device but the second treatment unit is arranged. As a result, it is possible to design an exhaust gas treatment device with an appropriate structure corresponding to the concentration of ammonia contained in the exhaust gas discharged from the combustion device.

[0236] Description of reference numerals:

[0237] 10 Ammonia decomposition section (first treatment section)

[0238] 20 Nitrogen oxide decomposition section (second treatment section)

[0239] 30 Ammonia decomposition section (third treatment section)

[0240] 40 Detection Department

[0241] 50 First supply unit (reducing agent supply unit)

[0242] 55. Second supply unit (fuel supply unit)

[0243] 60 Temperature Sensor

[0244] 70 Bypass valve

[0245] 80 Control Department

[0246] 90 Bypass valve

[0247] 100, 100A, 100B, 100C, 100D exhaust gas treatment device

[0248] 200 Combustion Device

[0249] L1, L2, L3, L4, L5, L6, L7, L8 piping.

Claims

1. An exhaust gas treatment device for treating exhaust gas discharged from a combustion device that burns a fuel containing ammonia, wherein: The exhaust gas treatment device comprises: a first treatment unit having a first catalyst for decomposing ammonia contained in the exhaust gas; and The second treatment section includes a second catalyst for decomposing nitrous oxide and NOx contained in the exhaust gas in which ammonia has been decomposed in the first treatment section.

2. The exhaust gas treatment device according to claim 1, wherein: The first treatment unit removes NOx generated when decomposing ammonia included in the exhaust gas using the first catalyst.

3. The exhaust gas treatment device according to claim 1 or 2, wherein: The exhaust gas treatment device comprises: a bypass pipe for introducing the exhaust gas discharged from the combustion device into the second processing section without passing through the first processing section; and A bypass valve is arranged on the bypass pipe.

4. The exhaust gas treatment device according to claim 1 or 2, wherein: The exhaust gas treatment device includes a third treatment section that decomposes ammonia included in the exhaust gas that has passed through the second treatment section.

5. The exhaust gas treatment device according to claim 1 or 2, wherein: The exhaust gas treatment device comprises: a detection unit that detects the concentration of nitrous oxide and / or NOx contained in the exhaust gas that has passed through the second treatment unit; and a first supply unit for supplying ammonia or urea water to the exhaust gas supplied from the first treatment unit to the second treatment unit when the concentration of nitrous oxide contained in the exhaust gas is higher than a first predetermined concentration or the concentration of NOx contained in the exhaust gas is higher than a second predetermined concentration; The second catalyst is a catalyst that reduces and decomposes NOx contained in the exhaust gas using ammonia.

6. The exhaust gas treatment device according to claim 5, wherein: The exhaust gas treatment device comprises: a temperature detection unit that detects a temperature of the exhaust gas discharged from the first processing unit; and The second supply unit supplies ammonia or urea water to the exhaust gas supplied from the combustion device to the first processing unit when the temperature detected by the temperature detection unit is equal to or lower than a predetermined temperature.

7. The exhaust gas treatment device according to claim 6, wherein: The exhaust gas treatment device includes a third treatment section that decomposes ammonia included in the exhaust gas that has passed through the second treatment section.

8. The exhaust gas treatment device according to claim 6, wherein: The predetermined temperature is a temperature of 450°C or higher and 530°C or lower.

9. An exhaust gas treatment device for treating exhaust gas discharged from a combustion device that burns a fuel containing ammonia, wherein: The exhaust gas treatment device comprises: an ammonia supply unit that supplies ammonia as a reducing agent to the exhaust gas exhausted from the combustion device; a nitrogen oxide decomposition unit having a nitrogen oxide decomposition catalyst for reducing nitrous oxide and NOx contained in the exhaust gas using ammonia supplied from the ammonia supply unit; and An ammonia decomposition unit decomposes ammonia contained in the exhaust gas that has passed through the nitrogen oxide decomposition unit.

10. A method for designing an exhaust gas treatment device, which is a method for designing an exhaust gas treatment device for treating exhaust gas discharged from a combustion device that burns a fuel containing ammonia, wherein: In a case where the concentration of ammonia contained in the exhaust gas is higher than the total concentration of a first concentration obtained by multiplying the concentration of nitrous oxide contained in the exhaust gas by a first coefficient and a second concentration obtained by multiplying the concentration of NOx contained in the exhaust gas by a second coefficient, the exhaust gas treatment device is designed in such a manner that a first treatment section having a first catalyst for decomposing ammonia contained in the exhaust gas is arranged on the downstream side of the combustion device, and a second treatment section having a second catalyst for decomposing nitrous oxide and NOx contained in the exhaust gas in which ammonia has been decomposed in the first treatment section is arranged on the downstream side of the first treatment section, When the concentration of ammonia contained in the exhaust gas is equal to or lower than the total concentration, the exhaust gas treatment device is designed so that the second treatment part is arranged instead of the first treatment part on the downstream side of the combustion device.

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