SCR system based on ammonia combustion and control method

Abstract

The invention provides an ammonia combustion-based SCR (selective catalytic reduction) system and a control method, which are used for tail gas emission control of an ammonia fuel engine, and the method comprises the following steps of: feeding tail gas generated after an ammonia fuel is combusted by an engine (1) to a flue gas analyzer (2) to judge the concentration of a tail gas product; the flue gas analyzer outputs a control signal for a switching conversion valve (6) at a tail gas path according to a judgment result, so that the tail gas path is subjected to working condition switching according to different tail gas product concentrations, the tail gas is introduced into different treatment devices for treatment, and each treatment device comprises a heat exchange sleeve (4), a selective catalytic reduction device (3) and an ammonia water buffer tank (5). A reducing agent ammonia gas source of the selective catalytic reduction device comprises an ammonia gas storage tank in an engine ammonia fuel tank; according to the invention, low nitrogen oxide emission of the ammonia power system can be realized, and the pollution problem caused by emission of incompletely combusted ammonia gas is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of engine tail gas emission systems, and in particular to an SCR system based on ammonia combustion and a control method thereof. Background Art

[0002] With the rapid development of industry in the past century, human productivity has been greatly improved, but the resulting energy problems have attracted much attention, including concerns about the depletion of fossil fuels and the negative impact of global greenhouse effects caused by carbon emissions. my country has formulated a strategic goal for carbon emission reduction, and automobile engine exhaust emissions, as an important source of greenhouse gases, have an impact on the global climate that cannot be ignored. In order to achieve this strategic goal as soon as possible, it is imperative to shift from traditional carbon fuels to clean energy. Ammonia, as a zero-carbon fuel, is regarded as one of the new alternative fuels due to its relatively mature industrial synthesis and storage and transportation facilities, as well as its advantages of being relatively safe during production, transportation and use. However, due to the shortcomings of ammonia, such as weak reactivity, high ignition temperature (903K), low combustion velocity (5–13cm / s), and narrow flammable range (15.5–27.0% volume ratio in air), the application of ammonia fuel in automobile engines still has many technical difficulties to be overcome. In order to solve this outstanding problem, the performance complementation can be achieved through hydrogen blending and co-firing. The in-situ blending of ammonia and hydrogen fuel can also be achieved by using ammonia catalytic decomposition hydrogen production technology. More importantly, after the ammonia fuel is burned in the engine, a large amount of nitrogen oxides (NO x ) has certain harm to the environment. In order to solve this problem, it is necessary to use a selective catalytic reduction system to post-treat the exhaust gas.

[0003] The Selective Catalytic Reduction (SCR) system is a common post-treatment device in the prior art. It uses urea to reduce NO in the exhaust gas. x Selectively reduced to N2 and H2O. However, urea solution will not only decompose to produce ammonia during use, but also undergo polymerization to produce a large amount of scale that blocks the SCR system, thereby affecting the denitration efficiency. The polymer will generate a stable polymer-melamine during long-term heating, which is very difficult to clean and has a low solubility in water solvents. Taking the automotive denitrification system as an example, the basic method after the SCR system is blocked is to clean it manually, which is difficult to operate. Secondly, the exhaust temperature generated by the combustion of ammonia fuel is relatively low. Compared with the original SCR catalytic reduction, which requires the improvement of low-temperature characteristics, the exhaust gas emissions generated by the combustion of amino fusion fuels have a relatively high proportion of NO and N2O, and there is incompletely burned NH3, so there are great differences in the working characteristics, temperature range, and selection of reducing agents from traditional SCRs. It is particularly necessary to develop a special post-treatment system that integrates NO, N2O and NH3.

[0004] In the system of the present invention, ammonia is used to replace the original urea to reduce the generated NO x and can effectively solve the problem of high ammonia and high nitrogen oxide emissions after the combustion of an ammonia fuel engine. Summary of the Invention

[0005] The present invention provides an SCR system and a control method based on ammonia combustion, which can achieve low nitrogen oxide emissions in an ammonia power system and solve the pollution problem of unburned ammonia emissions.

[0006] The present invention adopts the following technical solutions.

[0007] An SCR system control method based on ammonia combustion is used for controlling the exhaust gas emissions of an ammonia fuel engine. The method sends the exhaust gas generated after the combustion of ammonia fuel by the engine (1) to a flue gas analyzer (2) for determining the concentration of exhaust gas products. The flue gas analyzer outputs a control signal for a switching steering valve (6) at the exhaust gas path according to the determination result, so that the exhaust gas path is switched under different exhaust gas product concentrations, and the exhaust gas is introduced into different treatment devices for treatment. The treatment devices include a heat exchange sleeve (4), a selective catalytic reduction device (3), and an ammonia water buffer tank (5). The reducing agent ammonia source of the selective catalytic reduction device includes an ammonia storage tank (7) in the engine ammonia fuel tank.

[0008] The main components of the exhaust gas are NO and NH3. The flue gas analyzer uses the difference between the NO generation concentration and the NH3 concentration as the determination threshold, and outputs a control signal for the switching steering valve according to the determination threshold.

[0009] The determination threshold is 200 ppm.

[0010] If the difference between the measured values of NO and NH3 in the exhaust gas by the flue gas analyzer is 0–200 ppm, the switching steering valve controls the exhaust gas path to introduce the exhaust gas into the heat exchange sleeve and discharge it after heat exchange.

[0011] If the difference between the measured values of NO and NH3 is greater than 200 ppm, the switching steering valve controls the exhaust gas path to introduce the exhaust gas into the selective catalytic reduction device. At the same time, the ammonia storage tank (7) injects ammonia into the selective catalytic reduction device, so that the exhaust gas fully performs a reduction reaction and then is discharged after heat exchange.

[0012] If the difference between the measured values of NO and NH3 in the flue gas analyzer 2 is less than 0, the switching steering valve controls the exhaust gas path to introduce the exhaust gas into the ammonia water buffer tank, and the unburned NH3 in the exhaust gas is absorbed by it and then discharged.

[0013] The equivalence ratio of the engine during operation is 0.6 - 1.2. The equivalence ratio is the ratio of the amount of air theoretically required for complete combustion of ammonia fuel in the engine to the amount of air actually supplied. The engine operating conditions include rich combustion and lean combustion. Rich combustion means that the actual amount of air contained in the combustible mixture is less than the necessary theoretical amount of air. Lean combustion means that the actual amount of air contained in the combustible mixture exceeds the necessary theoretical amount of air; The initial temperature of the engine is set to 300–500 K, the initial pressure of the engine is set to 0.12 –0.42 MPa, and the engine ignition timing is set to -15 ℃ AATDC, -10 ℃ A ATDC. By adjusting the above engine parameters, the combustion stability is improved, NOx emissions are reduced, and ammonia slip is prevented.

[0014] An SCR system based on ammonia combustion. In the SCR system, the exhaust gas outlet of the engine is connected to a flue gas analyzer. The control signal of the flue gas analyzer is transmitted to a switching steering valve through a signal output port. The switching steering valve is a controllable steering valve, and its exhaust gas output end is connected to three gas paths. When it works, according to the signal transmitted by the upstream flue gas analyzer, it selects to transmit the exhaust gas to a designated one of the paths; The first gas path connected to the exhaust gas output end of the switching steering valve is connected to a heat exchange sleeve; The second gas path connected to the exhaust gas output end of the switching steering valve is connected to an ammonia water buffer tank; The third gas path connected to the exhaust gas output end of the switching steering valve is connected to a selective catalytic reduction device.

[0015] The selective catalytic reduction device is used for the reduction of nitrogen oxides; downstream of the selective catalytic reduction device is connected to a switching steering valve; the catalyst of the selective catalytic reduction device is a supported noble metal catalyst, a metal oxide catalyst or a molecular sieve catalyst; the internal catalytic bed structure of the selective catalytic reduction device is arranged in a spiral shape, When the selective catalytic reduction device works, the reducing agent used includes the unburned ammonia slip in the exhaust gas emissions, and the ammonia slip partially or completely replaces the reducing agent urea required by the selective catalytic reduction device; When the ammonia storage tank supplies the reducing agent ammonia to the selective catalytic reduction device, the ammonia is injected into the SCR system through a special ammonia injection nozzle.

[0016] The ammonia water buffer tank buffers when the ammonia supply is excessive or insufficient, and is used to maintain a stable ammonia supply and improve the system efficiency; The heat exchange sleeve reduces the exhaust gas temperature by exchanging heat with the exhaust gas.

[0017] The present invention can achieve low nitrogen oxide emissions in the ammonia power system and solve the pollution problem of unburned ammonia emissions. The beneficial effects of the present invention also lie in: (1) The present invention relates to an SCR system based on ammonia fuel and a control method, namely a tail gas emission control method of in-cylinder (engine) - out-of-cylinder (flue gas analyzer, selective catalytic reduction device, ammonia water buffer tank) collaborative control. A flue gas analyzer is arranged outside the cylinder to detect nitrogen oxides and ammonia in the exhaust gas, and emissions are reduced through the SCR system, enabling it to have a lower NOx emission range.

[0018] (2) In view of the unique reduction property of ammonia fuel, the present invention uses an ammonia fuel tank to provide the reducing agent - ammonia for the SCR system, that is, the ammonia storage tank is the direct source of the SCR system. The unburned ammonia (escaped ammonia) in the tail gas emission is used to replace the original urea in the selective catalytic reduction device as the reducing agent, and ammonia is injected into the SCR system through a special ammonia injection nozzle. Description of the Drawings

[0019] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments: Att Figure 1 is a schematic flow diagram of an SCR system based on ammonia combustion according to the present invention; In the figure: 1 - engine; 2 - flue gas analyzer; 3 - selective catalytic reduction device; 4 - heat exchange sleeve; 5 - ammonia water buffer tank; 6 - switching steering valve; 7 - ammonia storage tank. Specific Embodiments

[0020] As shown in the figure, an SCR system control method based on ammonia combustion is used for the tail gas emission control of an ammonia fuel engine. The method sends the tail gas generated after the ammonia fuel is burned by the engine 1 to the flue gas analyzer 2 for determining the concentration of the tail gas products. The flue gas analyzer outputs a control signal for the switching steering valve 6 at the tail gas gas path according to the determination result, so that the tail gas gas path is switched according to different tail gas product concentrations, and the tail gas is introduced into different treatment devices for treatment. The treatment devices include a heat exchange sleeve 4, a selective catalytic reduction device 3, and an ammonia water buffer tank 5. The source of the reducing agent ammonia for the selective catalytic reduction device includes the ammonia storage tank 7 in the engine ammonia fuel tank.

[0021] The main components of the tail gas are NO and NH3. The flue gas analyzer uses the difference between the NO generation concentration and the NH3 concentration as the determination threshold, and outputs a control signal for the switching steering valve according to the determination threshold.

[0022] The determination threshold is 200 ppm.

[0023] If the difference between the measured values of NO and NH3 in the tail gas by the flue gas analyzer is 0 - 200 ppm, the tail gas gas path is controlled by the switching steering valve, and the tail gas is introduced into the heat exchange sleeve and discharged after heat exchange.

[0024] If the difference between the measured values of NO and NH3 by the flue gas analyzer is greater than 200 ppm, the tail gas gas path is controlled by the switching steering valve, and the tail gas is introduced into the selective catalytic reduction device. At the same time, the ammonia storage tank 7 injects ammonia into the selective catalytic reduction device, so that after the tail gas fully undergoes the reduction reaction, it is heat-exchanged and discharged.

[0025] If the difference between the measured values of NO and NH3 in the flue gas analyzer 2 is less than 0, the tail gas gas path is controlled by the switching steering valve, and the tail gas is introduced into the ammonia water buffer tank, and the unburned NH3 in the tail gas is absorbed by it and then discharged.

[0026] The equivalence ratio of the engine during operation is 0.6 - 1.2. The equivalence ratio is the ratio of the amount of air theoretically required for the complete combustion of ammonia fuel in the engine to the actual supplied air amount. The engine operating conditions include rich combustion and lean combustion; rich combustion means that the actual amount of air contained in the combustible mixture is less than the required theoretical air amount. Lean combustion means that the actual amount of air contained in the combustible mixture exceeds the required theoretical air amount; The initial temperature of the engine is set to 300–500 K, the initial pressure of the engine is set to 0.12 –0.42 MPa, and the engine ignition timing is set to -15 ℃ AATDC, -10 ℃ A ATDC; by adjusting the above engine parameters, the combustion stability is improved, the NOx emissions are reduced, and ammonia slip is prevented.

[0027] An SCR system based on ammonia combustion. In the SCR system, the tail gas outlet of the engine is connected to a flue gas analyzer, and the control signal of the flue gas analyzer is transmitted to the switching steering valve through the signal output port. The switching steering valve is a controllable steering valve, and its tail gas output end is connected with three gas paths. When it works, according to the signal transmitted by the upstream flue gas analyzer, it selects to transmit the tail gas flue gas to a designated one; The first gas path connected to the tail gas output end of the switching steering valve is connected to the heat exchange sleeve; The second gas path connected to the tail gas output end of the switching steering valve is connected to the ammonia water buffer tank; The third gas path connected to the tail gas output end of the switching steering valve is connected to the selective catalytic reduction device.

[0028] The selective catalytic reduction device is used for the reduction of nitrogen oxides; downstream of the selective catalytic reduction device is connected to the switching steering valve; the catalyst of the selective catalytic reduction device is a supported noble metal catalyst, a metal oxide catalyst or a molecular sieve catalyst; the internal catalytic bed structure of the selective catalytic reduction device is arranged in a spiral shape, When the selective catalytic reduction device works, the reducing agent used includes the unburned ammonia slip in the tail gas emissions, and the ammonia slip partially or completely replaces the reducing agent urea required by the selective catalytic reduction device; When the ammonia storage tank supplies the reducing agent ammonia to the selective catalytic reduction device, the ammonia is injected into the SCR system through a dedicated ammonia injection nozzle.

[0029] The ammonia water buffer tank buffers when the ammonia supply is excessive or insufficient, and is used to maintain a stable ammonia supply and improve system efficiency. The heat exchange jacket reduces the temperature of the exhaust gas by exchanging heat with the exhaust gas.

[0030] Example 1: In this example, after the ammonia fuel is burned by the engine 1, the exhaust gas is judged for the concentration of exhaust gas products by the flue gas analyzer 2. The main exhaust gas products include NO and NH3. The control signal is transmitted from the flue gas analyzer 2 to the switching steering valve 6. The judgment threshold is set at 200 ppm. If the difference between the measured values of NO and NH3 in the flue gas analyzer 2 is 0 - 200 ppm, it is controlled by the switching steering valve 6 to pass through the heat exchange jacket 4 for heat exchange and then discharged; if the difference between the measured values of NO and NH3 in the flue gas analyzer 2 is greater than 200 ppm, it is controlled by the switching steering valve 6 to pass into the selective catalytic reduction device 3, and at the same time, the ammonia storage tank 7 sprays ammonia for reduction and then heat exchange and discharge; if the difference between the measured values of NO and NH3 in the flue gas analyzer 2 is less than 0, it is controlled by the switching steering valve 6 to pass into the ammonia water buffer tank 5, and the unburned NH3 in the exhaust gas is absorbed and then discharged. In this example, the equivalence ratio is set at 0.6 - 1.2. The equivalence ratio is the ratio of the amount of air required for complete combustion of the fuel to the amount of air actually supplied. Rich combustion means that the actual amount of air contained in the combustible mixture is less than the required theoretical amount of air. Lean combustion means that the actual amount of air contained in the combustible mixture exceeds the required theoretical amount of air.

[0031] In this example, the initial temperature of the engine is set at 300 - 500 K.

[0032] In this example, the initial pressure of the engine is set at 0.12 - 0.42 MPa.

[0033] In this example, the engine ignition timing is set at -15 °CA ATDC and -10 °CA ATDC.

[0034] By adjusting the above parameters, the combustion stability is improved, the NOx emissions are reduced, and ammonia slip is prevented.

[0035] In this example, an ammonia combustion-based SCR system and control method include: an ammonia fuel engine, a selective catalytic reduction device and a flue gas analyzer connected in parallel behind the engine, a switching steering valve, an ammonia water buffer tank, a heat exchange jacket, and an ammonia storage tank. The exhaust gas generated by the combustion of the ammonia fuel in the ammonia fuel engine needs to be introduced into the flue gas analyzer for flue gas analysis; the catalyst of the selective catalytic reduction device is a supported noble metal catalyst, a metal oxide catalyst, or a molecular sieve catalyst; a switching steering valve is connected downstream of the selective catalytic reduction device; the internal catalytic bed structure of the selective catalytic reduction device is arranged in a spiral manner; the selective catalytic reduction device is used for the reduction of nitrogen oxides; a switching steering valve is connected downstream of the flue gas analyzer; the flue gas analyzer can accurately measure the concentrations of NO and NH3 in the flue gas and transmit signals to the switching steering valve downstream; the determination criterion of the flue gas analyzer is the difference between the NO generation concentration and the NH3 concentration; the switching steering valve is a controllable steering valve, with a total of three connections, and can select to transmit the flue gas to a specified one through the signal transmitted by the upstream flue gas analyzer; the first connection of the switching steering valve is connected to the heat exchange jacket; the second connection of the switching steering valve is connected to the ammonia water buffer tank; the third connection of the switching steering valve is connected to the selective catalytic reduction device; the ammonia water buffer tank buffers when the ammonia supply is excessive or insufficient, maintains a stable supply, and improves the system efficiency; the ammonia storage tank provides reducing gas for the selective catalytic reduction device; the heat exchange jacket provides heat exchange for the exhaust gas to reduce the exhaust gas temperature.

[0036] Example 2: This example provides an ammonia combustion-based SCR system and control method, which includes an ammonia fuel engine 1. The outlet of the ammonia fuel engine 1 is connected to a flue gas analyzer 2. The outlet of the flue gas analyzer 2 transmits a control signal to a switching steering valve 6. The outlet of the switching steering valve 6 is respectively connected to a selective catalytic reduction device 3, a heat exchange jacket 4, and an ammonia water buffer tank 5. The following further illustrates the present invention with reference to the examples. In the following examples, the flow rate of the ammonia fuel entering the ammonia engine is set to 28.2 SLM.

[0037] Using the ammonia combustion-based SCR system and control method provided by the present invention in this example, the following steps are included: The exhaust gas generated after the combustion of the ammonia fuel contains a mixture of ammonia and NO.

[0038] The mixture is introduced into the flue gas analyzer for concentration determination.

[0039] Among them, the equivalence ratio is 0.8, the initial temperature is 323 K, the initial pressure is 0.12 MPa, the ignition timing is -15 °C AATDC, the generated NO concentration in the tail gas is 163 ppm, the concentration of NH3 is 56 ppm, and the measured value determined by the flue gas analyzer is 107 ppm. Within the range of 0–200 ppm, the flue gas analyzer transmits a signal to the switching steering valve, which controls the exhaust after heat exchange through the heat exchange jacket.

[0040] Example 3 A SCR system and control method based on ammonia combustion based on Example 2 include the following steps: The tail gas generated after the combustion of ammonia fuel contains a mixture of ammonia and NO.

[0041] The mixture is introduced into a flue gas analyzer for concentration determination.

[0042] Among them, the equivalence ratio is 0.9, the initial temperature is 373 K, the initial pressure is 0.22 MPa, the ignition timing is -15 °C AATDC, the generated NO concentration in the tail gas is 723 ppm, the concentration of NH3 is 44 ppm, and the measured value determined by the flue gas analyzer is 679 ppm, which is greater than the set threshold of 200 ppm. The flue gas analyzer transmits a signal to the switching steering valve, which controls the introduction into the selective catalytic reduction device, and at the same time, ammonia is injected from the ammonia storage tank for reduction and then discharged after heat exchange.

[0043] Example 4 A SCR system and control method based on ammonia combustion based on Example 2 include the following steps: The tail gas generated after the combustion of ammonia fuel contains a mixture of ammonia and NO.

[0044] The mixture is introduced into a flue gas analyzer for concentration determination.

[0045] Among them, the equivalence ratio is 1, the initial temperature is 323 K, the initial pressure is 0.42 MPa, the ignition timing is -10 °C AATDC, the generated NO concentration in the tail gas is 232 ppm, the concentration of NH3 is 346 ppm, and the measured value determined by the flue gas analyzer is -114 ppm. The measured value range is less than 0. The flue gas analyzer transmits a signal to the switching steering valve, which controls the introduction into the ammonia water buffer tank to absorb the unburned NH3 in the tail gas and then discharge it.

Claims

1. A SCR system control method based on ammonia combustion, used for exhaust emission control of ammonia fuel engine, characterized by: The method sends the exhaust gas generated after the combustion of ammonia fuel in an engine (1) to a flue gas analyzer (2) for determining the concentration of the exhaust gas product. The flue gas analyzer outputs a control signal for switching a steering valve (6) at the exhaust gas path according to the determination result, so that the exhaust gas path switches the working conditions according to different exhaust gas product concentrations, and the exhaust gas is passed into different treatment devices for treatment. The treatment device includes a heat exchange jacket (4), a selective catalytic reduction device (3), and an ammonia buffer tank (5). The source of the reducing agent ammonia in the selective catalytic reduction device includes an ammonia storage tank in the engine ammonia fuel tank.

2. The SCR system control method based on ammonia combustion according to claim 1, characterized in that: The main components of the exhaust gas are NO and NH3. The flue gas analyzer uses the difference between the NO generation concentration and the NH3 concentration as a determination threshold, and outputs a control signal for switching the steering valve according to the determination threshold.

3. The SCR system control method based on ammonia combustion according to claim 2, characterized in that: The determination threshold is 200 ppm.

4. The SCR system control method based on ammonia combustion according to claim 3, characterized in that: If the flue gas analyzer measures that the difference between the values ​​of NO and NH3 in the exhaust gas is 0-200 ppm, the exhaust gas path is controlled by switching the steering valve, and the exhaust gas is passed into the heat exchange jacket and discharged after heat exchange.

5. The SCR system control method based on ammonia combustion according to claim 3, characterized in that: If the difference between the values ​​of NO and NH3 measured by the flue gas analyzer is greater than 200 ppm, the exhaust gas path is controlled by switching the steering valve to pass the exhaust gas into the selective catalytic reduction device. At the same time, the ammonia storage tank (7) sprays ammonia into the selective catalytic reduction device so that the exhaust gas can fully perform the reduction reaction before being discharged through heat exchange.

6. The SCR system control method based on ammonia combustion according to claim 3, characterized in that: If the difference between the values ​​of NO and NH3 measured in the flue gas analyzer 2 is less than 0, the exhaust gas path is controlled by switching the steering valve to pass the exhaust gas into the ammonia buffer tank, which absorbs the unburned NH3 in the exhaust gas and then discharges it.

7. The SCR system control method based on ammonia combustion according to claim 3, characterized in that: The equivalence ratio of the engine during operation is 0.6-1.2, which is the ratio of the theoretical amount of air required for complete combustion of the ammonia fuel of the engine to the actual amount of air supplied. The engine operating conditions include rich combustion and lean combustion; rich combustion means that the actual amount of air contained in the combustible mixture is less than the theoretical amount of air required; Lean-burn combustion means that the actual amount of air contained in the combustible mixture exceeds the theoretical amount of air required; The initial engine temperature was set to 300–500 K, the initial engine pressure was set to 0.12–0.42 MPa, and the engine ignition timing was set to -15 °C A ATDC, -10 °C A ATDC; By adjusting the above engine parameters, combustion stability can be improved, NOx emissions can be reduced, and ammonia slip can be prevented.

8. An SCR system based on ammonia combustion, characterized in that: In the SCR system, the exhaust gas outlet of the engine is connected to the flue gas analyzer, and the control signal of the flue gas analyzer is transmitted to the switching steering valve through the signal output port. The switching steering valve is a controllable steering valve, and its exhaust gas output end is connected to three gas paths. When it is working, according to the signal transmitted by the upstream flue gas analyzer, the exhaust gas flue gas is selected to be transmitted to the designated one path; The first gas path connected to the tail gas output end of the switching steering valve is connected to a heat exchange jacket; The second gas path connected to the tail gas output end of the switching steering valve is connected to the ammonia buffer tank; The third gas path connected to the tail gas output end of the switching steering valve is connected to a selective catalytic reduction device.

9. The SCR system based on ammonia combustion according to claim 8, characterized in that: The selective catalytic reduction device is used for reducing nitrogen oxides; a switching valve is connected to the downstream of the selective catalytic reduction device; the catalyst of the selective catalytic reduction device is a supported precious metal catalyst, a metal oxide catalyst or a molecular sieve catalyst; the catalytic bed structure inside the selective catalytic reduction device is a spiral arrangement, When the selective catalytic reduction device is working, the reducing agent used includes the escaped ammonia which is not completely burned in the exhaust gas emission, and the escaped ammonia partially or completely replaces the reducing agent urea required by the selective catalytic reduction device; When the ammonia storage tank provides the reducing agent ammonia to the selective catalytic reduction device, the ammonia is injected into the SCR system through a special ammonia injection nozzle.

10. The SCR system based on ammonia combustion according to claim 8, characterized in that: The ammonia buffer tank is used for buffering when the ammonia supply is excessive or insufficient, so as to maintain a stable ammonia supply and improve system efficiency; The heat exchange jacket reduces the temperature of the exhaust gas by exchanging heat with the exhaust gas.

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