An exhaust gas treatment device and an exhaust gas treatment method for an ammonia diesel engine

Abstract

The present invention discloses an exhaust gas treatment device and an exhaust gas treatment method for an ammonia diesel engine, and relates to the technical field of exhaust gas treatment for an ammonia diesel engine. A selective catalytic reducer, an ammonia oxidation catalyst, and a particle collector are connected in sequence from front to back. An ammonia nozzle is provided at the front end of the selective catalytic reducer, and the ammonia nozzle is connected to the ammonia source of the ammonia diesel engine. A first temperature sensor and a first nitrogen oxide sensor are provided at the front end of the selective catalytic reducer. A first ammonia sensor is also provided at the front end of the selective catalytic reducer. The first temperature sensor, the first nitrogen oxide sensor, and the first ammonia sensor are electrically connected to the post-processing unit of the ammonia diesel engine, respectively. The present invention adopts DPF passive regeneration to solve the problem of particles in the exhaust gas; the ammonia source of the selective catalytic reducer borrows the ammonia used for combustion of the ammonia diesel engine, eliminates the urea injection system, and solves the problem of urea crystallization.

Description

Technical Field

[0001] The invention relates to the technical field of tail gas treatment of an ammonia diesel engine, and in particular to a tail gas treatment device and a tail gas treatment method of an ammonia diesel engine. Background Art

[0002] In the field of traditional internal combustion engines, the exhaust post-treatment of diesel engines is an oxidation catalyst (DOC) + particulate filter (DPF) + selective catalytic reducer (SCR) + ammonia oxidation catalyst (ASC) system. The role of DOC is to purify carbon monoxide and hydrocarbons in the exhaust gas, and at the same time oxidize part of NO into NO2, increase the reaction speed of SCR, increase the exhaust temperature, ignite the diesel sprayed after the internal combustion engine, and increase the exhaust temperature to reach the temperature required for DPF regeneration. DPF is a device used to filter solid particles (mainly carbon soot) in the exhaust of internal combustion engines, which serves the purpose of reducing particulate (PM) emissions. Its focus is to capture large particles (5um) in the exhaust gas by collision and interception, and to capture small particles less than 100nm by diffusion, which makes the particle capture efficiency of DPF as high as more than 95%. SCR injects urea into the exhaust pipe through the urea injection system, and converts nitrogen oxides (NOx) in the exhaust gas into N2 and H2O through a selective catalytic reduction reaction, thereby achieving the purpose of removing nitrogen oxides. The existing technology requires a urea injection system, whose main sub-components include a urea tank, a urea pump, a urea injection pipeline, and a urea nozzle. ASC uses a catalyst coating such as precious metals on the inner wall of the carrier to catalytically oxidize the exhaust gas, which can be used to eliminate excess ammonia (NH3) or unreacted ammonia (NH3) in the SCR.

[0003] At present, the diesel exhaust treatment devices used in National VI and non-road ammonia diesel engines generally use urea aqueous solution to decompose ammonia, which is used as the ammonia source for SCR to remove nitrogen oxides (NO X )'s reduction reaction will cause a series of problems such as urea crystallization, low nitrogen oxide conversion efficiency of the selective catalytic reducer due to inferior urea, nozzle clogging, catalyst clogging, etc.

[0004] Terminology explanation:

[0005] Ammonia-diesel engine: An internal combustion engine that uses both diesel and ammonia as fuels.

[0006] Diesel oxidation catalyst (DOC): The abbreviation of "Diesel oxidation catalyst", a device that converts carbon monoxide (CO) and hydrocarbons (HC) in the exhaust of ammonia diesel engines into harmless water (H2O) and carbon dioxide (CO2) through oxidation reaction.

[0007] Diesel Particulate Filter (DPF): The abbreviation of "Diesel Particulate Filter". The function of DPF is to capture large particles (5um) in the exhaust gas by collision and interception, and to capture small particles smaller than 100nm by diffusion. DPF is a particulate filter with a wall-flow honeycomb ceramic block as the filter element. It is mainly used to capture particles in the exhaust gas to meet the requirements of the National VI emission regulations. When the carbon soot (particles) in the DPF reaches a certain amount, the DPF needs to be regenerated. DPF regeneration is divided into two forms: passive regeneration and active regeneration.

[0008] Selective Catalytic Reduction (SCR): The technical principle is to use a reducing agent under the action of a catalyst to selectively reduce nitrogen oxides into nitrogen and water in an oxygen-rich environment.

[0009] Ammonia Oxidation Catalyst (ASC): The abbreviation of "Ammonia Slip Catalyst". The main function of ASC is to eliminate excess or escaped ammonia (NH3).

[0010] Urea injection system: includes urea tank, urea injection pipeline and nozzle.

[0011] Ammonia (NH3): Ammonia is an inorganic compound with the chemical formula NH3. It is a colorless gas with a strong irritating odor. Summary of the invention

[0012] The purpose of the present invention is to provide an exhaust gas treatment device and an exhaust gas treatment method for an ammonia diesel engine, which solves the problem of urea crystallization.

[0013] To achieve the above object, the present invention provides the following solutions:

[0014] The present invention provides an exhaust gas treatment device for an ammonia diesel engine, comprising: a catalyst assembly and a particulate trap, wherein the catalyst assembly comprises a selective catalytic reducer and an ammonia oxidation catalyst, wherein the selective catalytic reducer, the ammonia oxidation catalyst and the particulate trap are sequentially connected from front to back, wherein the front end of the selective catalytic reducer is used to be connected to the ammonia diesel engine, wherein the front end of the selective catalytic reducer is provided with an ammonia nozzle, wherein the ammonia nozzle is connected to an ammonia source of the ammonia diesel engine, wherein the rear end of the particulate trap is used to be connected to the atmosphere, wherein the front end of the selective catalytic reducer is provided with a first temperature sensor and a first nitrogen oxide sensor The first temperature sensor is used to detect the temperature of the exhaust gas discharged from the ammonia diesel engine at the inlet of the selective catalytic reducer, and the first nitrogen oxide sensor is used to detect the sum of the nitrogen oxide content and the ammonia content of the exhaust gas discharged from the ammonia diesel engine at the inlet of the selective catalytic reducer. A first ammonia sensor is also provided at the front end of the selective catalytic reducer, and the first ammonia sensor is used to detect the ammonia content of the exhaust gas discharged from the ammonia diesel engine at the inlet of the selective catalytic reducer. The first temperature sensor, the first nitrogen oxide sensor and the first ammonia sensor are electrically connected to the post-processing unit of the ammonia diesel engine respectively.

[0015] Preferably, a second temperature sensor is provided at the rear end of the ammonia oxidation catalyst, the second temperature sensor is used to detect the temperature of the exhaust gas passing through the catalyst assembly, and the second temperature sensor is electrically connected to the post-processing unit of the ammonia diesel engine.

[0016] Preferably, a second nitrogen oxide sensor is provided at the rear end of the particulate trap, the second nitrogen oxide sensor is used to detect the content of nitrogen oxides in the exhaust gas passing through the particulate trap, and the second nitrogen oxide sensor is electrically connected to the post-processing unit of the ammonia diesel engine.

[0017] Preferably, a second ammonia sensor is provided between the catalyst assembly and the particulate trap, and the second ammonia sensor is used to detect the ammonia content in the exhaust gas passing through the catalyst assembly.

[0018] Preferably, it also includes an ammonia gas storage tank, which is connected to the ammonia source of the ammonia diesel engine and the ammonia nozzle respectively.

[0019] Preferably, the ammonia gas storage tank is provided with a third temperature sensor and a pressure sensor, the third temperature sensor is used to detect the temperature inside the ammonia gas storage tank, the pressure sensor is used to detect the pressure inside the ammonia gas storage tank, and the third temperature sensor and the pressure sensor are electrically connected to the post-processing unit of the ammonia diesel engine respectively.

[0020] Preferably, an intake valve is provided between the ammonia gas storage tank and the ammonia source, and the intake valve is electrically connected to the post-processing unit of the ammonia-diesel engine.

[0021] The present invention also provides an exhaust gas treatment method using the exhaust gas treatment device of the ammonia diesel engine, comprising:

[0022] When the temperature of the exhaust gas discharged by the ammonia-diesel engine detected by the first temperature sensor is not greater than the preset temperature value, the ammonia-diesel engine enters the pure diesel mode;

[0023] When the temperature of the exhaust gas discharged by the ammonia-diesel engine detected by the first temperature sensor is greater than a preset temperature value, the ammonia-diesel engine enters the ammonia-diesel mode. In the ammonia-diesel mode:

[0024] When the ratio of the ammonia content of the exhaust gas discharged by the ammonia diesel engine at the inlet of the selective catalytic reduction device to the nitrogen oxide content of the exhaust gas discharged by the ammonia diesel engine at the inlet of the selective catalytic reduction device is greater than a preset value, the ammonia nozzle stops spraying ammonia;

[0025] When the ratio of the ammonia content of the exhaust gas discharged from the ammonia-diesel engine at the inlet of the selective catalytic reducer to the nitrogen oxide content of the exhaust gas discharged from the ammonia-diesel engine at the inlet of the selective catalytic reducer is not greater than a preset value, the ammonia nozzle injects ammonia.

[0026] Preferably, in pure diesel mode, the demand for ammonia is based on the content of nitrogen oxides in the exhaust gas discharged from the ammonia-diesel engine at the inlet of the selective catalytic reducer, the target value of the ammonia storage capacity of the ammonia oxidation catalyst, the nitrogen oxide conversion efficiency of the selective catalytic reducer, the content of nitrogen oxides in the exhaust gas passing through the particulate filter detected by the second nitrogen oxide sensor, and the content of ammonia in the exhaust gas passing through the catalyst assembly detected by the second ammonia sensor.

[0027] Preferably, when the ratio of the ammonia content in the exhaust gas exhausted by the ammonia-diesel engine at the inlet of the selective catalytic reducer to the nitrogen oxide content in the exhaust gas exhausted by the ammonia-diesel engine at the inlet of the selective catalytic reducer is not greater than a preset value, the demand for ammonia is based on the nitrogen oxide content in the exhaust gas exhausted by the ammonia-diesel engine at the inlet of the selective catalytic reducer, the ammonia content in the exhaust gas exhausted by the ammonia-diesel engine at the inlet of the selective catalytic reducer detected by the first ammonia sensor, the ammonia storage target value of the ammonia oxidation catalyst, the nitrogen oxide conversion efficiency of the selective catalytic reducer, the nitrogen oxide content in the exhaust gas passing through the particulate filter detected by the second nitrogen oxide sensor, and the ammonia content in the exhaust gas passing through the catalyst assembly detected by the second ammonia sensor.

[0028] Compared with the prior art, the present invention has achieved the following technical effects:

[0029] The present invention designs a catalyst assembly (SCR-ASC) and arranges it before the particulate filter (DPF), cancels the oxidation catalyst (DOC) and some sensors, and adopts DPF passive regeneration to solve the particles in the exhaust gas; the ammonia source of the selective catalytic reducer (SCR) borrows the ammonia used for combustion of the ammonia diesel engine, eliminates the urea injection system, and completely solves the problem of urea crystallization. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 The figure is a schematic diagram of the exhaust gas treatment device of the ammonia diesel engine of the present invention;

[0032] Figure 2 is a flow chart of the tail gas treatment method of the present invention;

[0033] In the figure: 1-selective catalytic reduction device, 2-ammonia oxidation catalyst, 3-particulate filter, 4-ammonia diesel engine, 5-ammonia nozzle, 6-first temperature sensor, 7-first nitrogen oxide sensor, 8-second temperature sensor, 9-second nitrogen oxide sensor, 10-second ammonia sensor, 11-ammonia gas storage tank, 12-liquid ammonia tank, 13-ammonia tank, 14-intake valve, 15-third temperature sensor, 16-pressure sensor, 17-first ammonia sensor. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] The purpose of the present invention is to provide an exhaust gas treatment device and an exhaust gas treatment method for an ammonia diesel engine, which solves the problem of urea crystallization.

[0036] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] Embodiment 1

[0038] like Figure 1As shown, this embodiment provides an exhaust gas treatment device for an ammonia diesel engine, which is used for a generator set and includes: a catalyst assembly (SCR-ASC) and a particulate filter 3 (DPF), the catalyst assembly includes a selective catalytic reducer 1 (SCR) and an ammonia oxidation catalyst 2 (ASC), the selective catalytic reducer 1, the ammonia oxidation catalyst 2 and the particulate filter 3 are connected in sequence from front to back, the front end of the selective catalytic reducer 1 is used to connect with the ammonia diesel engine 4, the front end of the selective catalytic reducer 1 is provided with an ammonia nozzle 5, the ammonia nozzle 5 is connected to the ammonia source of the ammonia diesel engine 4, the rear end of the particulate filter 3 is used to communicate with the atmosphere, the front end of the selective catalytic reducer 1 is provided with a first temperature sensor 6 and a first nitrogen oxide sensor 7, the first temperature sensor 6 is used to detect ammonia The temperature of the exhaust gas discharged by the ammonia diesel engine 4 at the inlet of the selective catalytic reducer 1, the first nitrogen oxide sensor 7 is used to detect the sum of the nitrogen oxide content and the ammonia content of the exhaust gas discharged by the ammonia diesel engine 4 at the inlet of the selective catalytic reducer 1, and a first ammonia sensor 17 is also provided at the front end of the selective catalytic reducer 1. The first ammonia sensor 17 is used to detect the ammonia content of the exhaust gas discharged by the ammonia diesel engine 4 at the front end of the selective catalytic reducer 1. The values ​​detected by the first nitrogen oxide sensor 7 and the first ammonia sensor 17 can be used to obtain the nitrogen oxide content of the exhaust gas discharged by the ammonia diesel engine 4 at the inlet of the selective catalytic reducer 1. The first temperature sensor 6, the first nitrogen oxide sensor 7, and the first ammonia sensor 17 are electrically connected to the after-treatment unit (DCU) of the ammonia diesel engine 4 respectively. This embodiment designs a catalyst assembly (SCR-ASC) and arranges it before the particulate filter 3 (DPF), cancels the oxidation catalyst (DOC) and some sensors, and adopts DPF passive regeneration to solve the particles in the exhaust gas; the ammonia source of the selective catalytic reducer 1 (SCR) borrows the ammonia used for combustion of the ammonia diesel engine 4, eliminates the urea injection system, and completely solves the problem of urea crystallization.

[0039] In this embodiment, a second temperature sensor 8 is provided at the rear end of the ammonia oxidation catalyst 2. The second temperature sensor 8 is used to detect the temperature of the exhaust gas passing through the catalyst assembly. The second temperature sensor 8 is electrically connected to the post-processing unit of the ammonia diesel engine 4. The function of the second temperature sensor 8 is to monitor the temperature at the inlet of the particulate trap 3 (DPF), because the particulate trap 3 (DPF) in the post-processing needs to be within a certain temperature range to passively regenerate the particles in the exhaust gas that have been captured. Because the present invention is mainly used for generator sets, the working condition is a fixed condition (rated condition) most of the time, and the exhaust temperature is relatively high and can reach the passive regeneration temperature. The function of the second temperature sensor 8 is to monitor the inlet temperature of the particulate trap 3 (DPF) to ensure the passive regeneration of the particulate trap 3 (DPF).

[0040] In this embodiment, a second nitrogen oxide sensor 9 is provided at the rear end of the particulate filter 3, and the second nitrogen oxide sensor 9 is electrically connected to the after-treatment unit (DCU) of the ammonia diesel engine 4. The second nitrogen oxide sensor 9 is used to detect the content of nitrogen oxides in the exhaust gas passing through the particulate filter 3, and the second nitrogen oxide sensor 9 is electrically connected to the after-treatment unit of the ammonia diesel engine 4.

[0041] In this embodiment, a second ammonia sensor 10 is arranged between the catalyst assembly and the particulate filter. The second ammonia sensor 10 is electrically connected to the after-treatment unit (DCU) of the ammonia diesel engine 4. The second ammonia sensor 10 is used to detect the ammonia content in the exhaust gas passing through the catalyst assembly.

[0042] The present embodiment also includes an ammonia gas storage tank 11, which is used to store ammonia and provide a place for pressure control and temperature control of ammonia. The liquid ammonia in the liquid ammonia tank 12 is processed to obtain ammonia, which is stored in the ammonia gas storage tank 11. The ammonia gas storage tank 11 is connected to the ammonia tank 13 and the ammonia nozzle 5 respectively. An intake valve 14 is provided between the ammonia gas storage tank 11 and the ammonia source. The intake valve 14 is electrically connected to the control unit of the ammonia diesel engine 4. The opening of the intake valve 14 is controlled by the control unit to control the amount of ammonia entering the ammonia gas storage tank 11. The ammonia gas storage tank 11 is provided with a third temperature sensor 15 and a pressure sensor 16. The third temperature sensor 15 is used to detect the temperature in the ammonia gas storage tank 11, and the pressure sensor 16 is used to detect the pressure in the ammonia gas storage tank 11, which is used to accurately control the injection amount of the ammonia nozzle 5 each time. The third temperature sensor 15 and the pressure sensor 16 are electrically connected to the post-processing unit of the ammonia diesel engine 4 respectively.

[0043] In this embodiment, the post-processing unit of the ammonia-diesel engine 4 is electrically connected to the control unit of the ammonia-diesel engine 4.

[0044] The exhaust gas treatment device of the ammonia diesel engine of this embodiment is compatible with the pure diesel mode and the ammonia diesel mode. The ammonia diesel engine 4 used in this embodiment is an ammonia diesel engine 4 for a generator set, and the operating condition of the ammonia diesel engine 4 is a constant speed operating condition. During the startup condition stage of the ammonia diesel engine 4, the ammonia diesel engine 4 operates in the pure diesel mode, and the nitrogen oxides in the exhaust gas are converted, and ammonia needs to be injected into the catalyst assembly (SCR-ASC) through the ammonia nozzle 5. The ammonia injected by the ammonia nozzle 5 comes from the ammonia used for combustion of the ammonia diesel engine 4, eliminating the urea injection system and solving the urea crystallization problem.

[0045] At the rated operating speed of the ammonia-diesel engine 4 (the constant operation stage of the ammonia-diesel engine 4), which is the ammonia-diesel mode, the temperature inside the particulate filter 3 (DPF) can reach above 300°C, and the passive regeneration ability of the particulate filter 3 (DPF) is relatively strong, so that the carbon particles captured by the particulate filter 3 (DPF) can be regenerated at a relatively high temperature, thereby eliminating the oxidation catalyst (DOC) and reducing the cost of the after-treatment system.

[0046] Embodiment 2

[0047] like Figure 2 As shown, this embodiment provides an exhaust gas treatment method using the exhaust gas treatment device of the ammonia diesel engine of embodiment 1, comprising:

[0048] When the temperature of the exhaust gas discharged from the ammonia-diesel engine 4 detected by the first temperature sensor 6 (pre-SCR temperature) is not greater than the preset temperature value, the ammonia-diesel engine 4 enters the pure diesel mode (constant operation stage of the ammonia-diesel engine 4). In the pure diesel mode, the supply of ammonia to the ammonia-diesel engine 4 is suspended, and the exhaust gas is discharged after passing through the selective catalytic reducer 1, the ammonia oxidation catalyst 2 and the particulate trap 3 in sequence. The ammonia required for the conversion of nitrogen oxides in the catalyst assembly (SCR-ASC) is injected from the ammonia storage tank through the ammonia nozzle 5. The demand for ammonia is based on the nitrogen oxide content of the exhaust gas discharged from the ammonia-diesel engine 4 at the inlet of the selective catalytic reducer 1 (pre-SCR nitrogen oxide target value), the ammonia storage target value of the ammonia oxidation catalyst (ammonia storage target value), the nitrogen oxide conversion efficiency of the selective catalytic reducer (SCR conversion efficiency), the nitrogen oxide content in the exhaust gas passing through the particulate trap 3 detected by the second nitrogen oxide sensor 9 (post nitrogen oxide target value) and the ammonia content in the exhaust gas passing through the catalyst assembly detected by the second ammonia sensor 10 (post ammonia target value);

[0049] When the temperature of the exhaust gas discharged by the ammonia-diesel engine 4 detected by the first temperature sensor 6 (pre-SCR temperature) is greater than the preset temperature value, the ammonia-diesel engine 4 enters the ammonia-diesel mode. In the ammonia-diesel mode:

[0050] When the ratio of the ammonia content of the exhaust gas discharged from the ammonia diesel engine 4 at the inlet of the selective catalytic reducer 1 detected by the first ammonia sensor 17 before the SCR to the nitrogen oxide content of the exhaust gas discharged from the ammonia diesel engine 4 at the inlet of the selective catalytic reducer 1 (target value of the ammonia nitrogen ratio before SCR) is greater than a preset value, the ammonia nozzle 5 stops spraying ammonia, and the exhaust gas passes through the selective catalytic reducer 1, the ammonia oxidation catalyst 2 and the particulate filter 3 in sequence and is then discharged;

[0051] When the ratio of the ammonia content of the exhaust gas discharged by the ammonia diesel engine 4 at the inlet of the selective catalytic reduction device 1 detected by the first ammonia sensor 17 before SCR to the nitrogen oxide content of the exhaust gas discharged by the ammonia diesel engine 4 at the inlet of the selective catalytic reduction device 1 (target value of ammonia nitrogen ratio before SCR) is not greater than a preset value, the demand for ammonia is based on the nitrogen oxide content of the exhaust gas discharged by the ammonia diesel engine 4 at the inlet of the selective catalytic reduction device 1 (target value of nitrogen oxide before SCR), the ammonia content of the exhaust gas discharged by the ammonia diesel engine 4 at the inlet of the selective catalytic reduction device 1 detected by the first ammonia sensor 17 (target value of ammonia before SCR), and the ammonia storage capacity of the ammonia oxidation catalyst. The reserve target value (ammonia storage target value), the selective catalytic reduction nitrogen oxide conversion efficiency (SCR conversion efficiency), the nitrogen oxide content in the exhaust gas passing through the particulate trap 3 detected by the second nitrogen oxide sensor 9 (post nitrogen oxide target value) and the ammonia content in the exhaust gas passing through the catalyst assembly detected by the second ammonia sensor 10 (post ammonia target value) are derived, the exhaust gas is discharged after passing through the selective catalytic reduction device 1, the ammonia oxidation catalyst 2 and the particulate trap 3 in sequence, and the temperature inside the particulate trap 3 can reach above 350°C, the passive regeneration ability of the particulate trap 3 is strong, so that the carbon particles captured by the particulate trap 3 can be regenerated at a higher temperature.

[0052] In this embodiment, the nitrogen oxide content of the exhaust gas discharged by the ammonia diesel engine 4 at the inlet of the selective catalytic reduction device 1 is obtained by the difference between the first nitrogen oxide sensor 7 and the first ammonia sensor 17.

[0053] In the ammonia-diesel mode, unburned NH3 in the exhaust gas can be completely consumed in the selective catalytic reducer 1 (SCR) and the ammonia oxidation catalyst 2 (ASC), and the particulate matter in the exhaust gas is captured by the particulate filter 3 (DPF), and the particulate matter in the exhaust gas is resolved by passive regeneration of the particulate filter 3 (DPF).

[0054] The exhaust gas treatment method of this embodiment can divide the pure diesel mode and the ammonia diesel mode according to the temperature before the exhaust gas post-treatment as the dividing line, and at the same time determine the ammonia injection amount of the ammonia nozzle 5 according to the ratio and amount of nitrogen oxides and ammonia in the exhaust gas.

[0055] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A tail gas treatment method, characterized in that: An exhaust gas treatment device for an ammonia diesel engine is used, and the exhaust gas treatment device for the ammonia diesel engine includes: a catalyst assembly and a particulate trap, the catalyst assembly includes a selective catalytic reducer and an ammonia oxidation catalyst, the selective catalytic reducer, the ammonia oxidation catalyst and the particulate trap are connected in sequence from front to back, the front end of the selective catalytic reducer is used to be connected to the ammonia diesel engine, the front end of the selective catalytic reducer is provided with an ammonia nozzle, the ammonia nozzle is connected to the ammonia source of the ammonia diesel engine, the rear end of the particulate trap is used to communicate with the atmosphere, the front end of the selective catalytic reducer is provided with a first temperature sensor and a first nitrogen an oxygen sensor, the first temperature sensor is used to detect the temperature of the exhaust gas discharged from the ammonia diesel engine at the inlet of the selective catalytic reducer, the first nitrogen oxide sensor is used to detect the sum of the nitrogen oxide content and the ammonia content of the exhaust gas discharged from the ammonia diesel engine at the inlet of the selective catalytic reducer, the front end of the selective catalytic reducer is also provided with a first ammonia sensor, the first ammonia sensor is used to detect the ammonia content of the exhaust gas discharged from the ammonia diesel engine at the inlet of the selective catalytic reducer, the first temperature sensor, the first nitrogen oxide sensor and the first ammonia sensor are electrically connected to the post-processing unit of the ammonia diesel engine respectively; A second nitrogen oxide sensor is provided at the rear end of the particulate trap; A second ammonia sensor is disposed between the catalyst assembly and the particulate trap; Exhaust gas treatment methods include: When the temperature of the exhaust gas discharged by the ammonia-diesel engine detected by the first temperature sensor is not greater than the preset temperature value, the ammonia-diesel engine enters the pure diesel mode; When the temperature of the exhaust gas discharged by the ammonia-diesel engine detected by the first temperature sensor is greater than a preset temperature value, the ammonia-diesel engine enters the ammonia-diesel mode. In the ammonia-diesel mode: When the ratio of the ammonia content of the exhaust gas discharged by the ammonia diesel engine at the inlet of the selective catalytic reduction device to the nitrogen oxide content of the exhaust gas discharged by the ammonia diesel engine at the inlet of the selective catalytic reduction device is greater than a preset value, the ammonia nozzle stops spraying ammonia; When the ratio of the ammonia content in the exhaust gas exhausted by the ammonia-diesel engine at the inlet of the selective catalytic reducer to the nitrogen oxide content in the exhaust gas exhausted by the ammonia-diesel engine at the inlet of the selective catalytic reducer is not greater than a preset value, the ammonia nozzle injects ammonia, and the demand for ammonia is based on the nitrogen oxide content in the exhaust gas exhausted by the ammonia-diesel engine at the inlet of the selective catalytic reducer, the ammonia content in the exhaust gas exhausted by the ammonia-diesel engine at the inlet of the selective catalytic reducer detected by the first ammonia sensor, the ammonia storage target value of the ammonia oxidation catalyst, the nitrogen oxide conversion efficiency of the selective catalytic reducer, the nitrogen oxide content in the exhaust gas passing through the particulate filter detected by the second nitrogen oxide sensor, and the ammonia content in the exhaust gas passing through the catalyst assembly detected by the second ammonia sensor.

2. The tail gas treatment method according to claim 1, characterized in that: A second temperature sensor is provided at the rear end of the ammonia oxidation catalyst, and the second temperature sensor is used to detect the temperature of the exhaust gas passing through the catalyst assembly, and the second temperature sensor is electrically connected to the post-processing unit of the ammonia diesel engine.

3. The tail gas treatment method according to claim 1, characterized in that: The second nitrogen oxide sensor is used to detect the content of nitrogen oxides in the exhaust gas passing through the particulate trap, and the second nitrogen oxide sensor is electrically connected to the post-processing unit of the ammonia diesel engine.

4. The tail gas treatment method according to claim 1, characterized in that: The second ammonia sensor is used to detect the ammonia content in the exhaust gas passing through the catalyst assembly.

5. The tail gas treatment method according to claim 1, characterized in that: It also includes an ammonia gas storage tank, which is connected to the ammonia source of the ammonia diesel engine and the ammonia nozzle respectively.

6. The tail gas treatment method according to claim 5, characterized in that: The ammonia gas storage tank is provided with a third temperature sensor and a pressure sensor. The third temperature sensor is used to detect the temperature inside the ammonia gas storage tank, and the pressure sensor is used to detect the pressure inside the ammonia gas storage tank. The third temperature sensor and the pressure sensor are electrically connected to the post-processing unit of the ammonia diesel engine respectively.

7. The tail gas treatment method according to claim 5, characterized in that: An intake valve is arranged between the ammonia gas storage tank and the ammonia gas source, and the intake valve is electrically connected to the post-processing unit of the ammonia diesel engine.

8. The tail gas treatment method according to claim 1, characterized in that: In pure diesel mode, the demand for ammonia is based on the nitrogen oxide content in the exhaust gas discharged from the ammonia-diesel engine at the inlet of the selective catalytic reduction device, the ammonia storage target value of the ammonia oxidation catalyst, the nitrogen oxide conversion efficiency of the selective catalytic reduction device, the nitrogen oxide content in the exhaust gas passing through the particulate filter detected by the second nitrogen oxide sensor, and the ammonia content in the exhaust gas passing through the catalyst assembly detected by the second ammonia sensor.

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