Method for detecting clogging of injection lines in a gas-assisted twin injection system in an scr system

Abstract

The application provides a detection method for injection pipeline blockage in a gas-assisted double-injection system of an SCR system, and relates to the technical field of tail gas treatment.The method comprises the following steps: starting a train engine, starting a urea pump to build pressure;waiting for urea solution injection state; starting pipeline blockage detection; opening two metering valves, and allowing urea solution to flow through two pipelines, respectively acquiring urea pressure in the two pipelines, and judging whether the urea pressure is normal; judging whether urea solution injection conditions are met; starting lance blockage detection; calculating conversion efficiency of NOX in two tail gas channels, and judging whether the conversion efficiency of NOX is normal; when it is determined that the engine is closed, it is determined that the lance blockage detection has been completed, and the system operation is ended.The detection method for injection pipeline blockage in the gas-assisted double-injection system of the SCR system can solve the problem that the prior art cannot detect two high-pressure lances and their pipelines in a targeted manner when blockage occurs in an injection unit, and effectively locates the blockage position.

Description

Technical Field

[0001] This invention relates to the field of exhaust gas treatment technology, and in particular to a method for detecting blockage in the injection pipeline of an air-assisted dual-injection system in an SCR system. Background Technology

[0002] Oil-fired trains typically require exhaust gas treatment systems to remove harmful substances from their exhaust fumes, with NOx being a significant component. Chinese patent application number 202111455587.1 discloses an exhaust gas purification system for oil-fired trains, comprising an intake unit, a catalytic oxidation filter unit, a urea mixing chamber, a catalytic reduction unit, and an exhaust unit. The intake unit is directly connected to the engine's exhaust port. Exhaust gas exiting the engine passes sequentially through the intake unit, catalytic oxidation filter unit, urea mixing chamber, and catalytic reduction unit before exiting the exhaust port. The catalytic oxidation filter unit includes a DOC carrier (diesel catalytic oxidizer) and a DPF carrier (diesel particulate filter), while the catalytic reduction unit includes an SCR carrier (selective catalytic reduction unit). By incorporating an SCR carrier within the catalytic reduction unit, the system effectively removes nitrogen oxide pollutants such as NOx emitted from oil-fired trains.

[0003] However, this patent uses a single-channel spray gun to spray a large amount of urea solution into the exhaust gas. When the exhaust gas mixed with the urea solution enters the catalytic reduction unit, the poor atomization effect of the urea solution makes it impossible to achieve a good conversion effect of NOx in the exhaust gas. To solve this problem, the existing technology uses two exhaust gas channels and two spray guns to treat the exhaust gas simultaneously, and adds a gas-assisted method. High-pressure gas is added before the urea solution is sprayed. The high-pressure gas can make the urea solution achieve a better atomization effect, thereby improving the conversion efficiency of NOx in the exhaust gas.

[0004] However, when using this dual-jet-assisted SCR injection system, if the injection unit becomes clogged, the design of the two high-pressure spray guns will prolong the time required for clog detection, making it impossible to specifically inspect the two high-pressure spray guns and their pipelines. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a method for detecting blockages in the injection pipeline of an air-assisted dual-jet system in an SCR system. This method solves the problem in existing technologies where, when a blockage occurs in the injection unit, it is impossible to specifically detect the two high-pressure spray guns and their pipelines, thus effectively locating the blockage.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] This invention provides a method for detecting blockage in the injection pipeline of an air-assisted dual-injection system in an SCR system, comprising the following steps:

[0008] S101: Start the train engine and turn on the urea pump to build up pressure;

[0009] S102: After the urea pump has built up pressure, wait for the urea solution to be sprayed.

[0010] S103: When the urea solution injection state is met, the pipeline blockage detection module is activated; the two metering valves in the urea metering module in the injection unit are set to be normally open for 1 second. At this time, the urea pump delivers urea solution to the injection unit. The urea solution flows through two pipelines. The differential pressure sensor in the pipeline obtains the urea pressure in the two pipelines respectively and determines whether the urea pressure is normal. When the urea pressure is greater than the target pressure, the pipeline is identified as blocked and the first fault mode is entered.

[0011] S104: After the pipeline blockage detection is completed, determine whether the urea solution injection conditions are met; if the urea solution injection conditions are not met, shut down the engine and end the system operation.

[0012] S105: When the urea solution injection conditions are met, activate the spray gun blockage detection module; install a front NOx sensor in front of the SCR carrier in both exhaust gas channels, and a rear NOx sensor in rear of the SCR carrier in both exhaust gas channels; open the metering valves of the two high-pressure spray guns in the injection unit, so that the front NOx sensor in the two exhaust gas channels counts the NOx content before exhaust gas treatment, and the rear NOx sensor counts the NOx content after exhaust gas treatment; calculate the NOx conversion efficiency of the two exhaust gas channels based on the data from the front and rear NOx sensors, and determine whether the NOx conversion efficiency is normal; if the conversion efficiency is less than the target value, the high-pressure spray gun in that channel is considered blocked, and enter the second fault mode; if the conversion efficiency is greater than the target value, re-execute S104.

[0013] S106: When the engine is determined to be off, the spray gun blockage detection is considered complete, and the system operation ends.

[0014] The present invention provides a method for detecting blockage in the injection pipeline of an air-assisted dual-injection system in an SCR system. Preferably, the injection state in step S102 is that the urea pump pressure reaches the pressure build-up threshold and maintains the state after pressure build-up.

[0015] The present invention provides a method for detecting blockage in the injection pipeline of an air-assisted dual-injection system in an SCR system. Preferably, the injection condition in step S104 is that the exhaust gas temperature in the exhaust gas passage reaches 200°C.

[0016] The method for detecting blockage in the injection pipeline of the air-assisted dual-injection system in the SCR system provided by the present invention preferably includes, after "entering the first fault mode" in step S103, feedback of the blockage information of the pipeline.

[0017] The method for detecting blockage in the injection pipeline of the air-assisted dual-injection system in the SCR system provided by the present invention preferably includes, after "entering the second fault mode" in step S105, feedback of blockage information of the high-pressure spray gun in that line.

[0018] The present invention provides a method for detecting blockage in the injection pipeline of an air-assisted dual-injection system in an SCR system. Preferably, the urea pressure in step S103 is the pressure generated by the urea solution being squeezed in the pipeline.

[0019] The above technical solution has the following advantages or beneficial effects:

[0020] The present invention provides a method for detecting blockage in the injection pipeline of an air-assisted dual-injection system in an SCR system. In steps S103 and S105, a pipeline blockage detection method and a spray gun blockage detection method are disclosed. Since an air-assisted dual-injection system is used, it employs two exhaust gas channels to treat exhaust gas simultaneously. For this purpose, two high-pressure spray guns are used. The two high-pressure spray guns are supplied with the urea solution required for injection by two pipelines. When the high-pressure spray guns cannot spray urea solution normally, it is difficult to accurately and quickly find the cause of the abnormality of the high-pressure spray guns. By first detecting pipeline blockage and then detecting spray gun blockage, the specific location of the blockage of the two high-pressure spray guns and their pipelines can be detected, effectively locating the blockage location and reducing the time of manual inspection.

[0021] The present invention provides a method for detecting blockage in the injection pipeline of an air-assisted dual-injection system in an SCR system. In step S103, the pipeline blockage detection adopts a differential pressure sensor placed in the pipeline. The urea pressure is used to determine whether there is crystal blockage in the pipeline. When there is crystal blockage in the pipeline, the pressure of the urea solution in the pipeline will increase, and the urea pressure will rise. The differential pressure sensor can clearly monitor the urea pressure, thereby determining whether there is crystal blockage in the pipeline, and the data collected by the differential pressure sensor is used to provide feedback on the crystal blockage situation in the pipeline.

[0022] When the pipeline blockage detection fails to prove that there is crystallization blockage in the pipeline, step S105 will use the method of calculating the NOx conversion efficiency to determine whether there is near blockage in the high-pressure spray gun. When there is crystallization blockage in the high-pressure spray gun, the front NOx sensor will detect the NOx content of the untreated exhaust gas, and the rear NOx sensor will detect the NOx content of the treated exhaust gas. The NOx conversion efficiency in the exhaust gas channel can be calculated by using the data from the front and rear NOx sensors. If the NOx conversion efficiency in the exhaust gas channel is low, the high-pressure spray gun fails to spray a normal amount of urea solution per unit time, which indicates that there is crystallization blockage in the high-pressure spray gun. This method uses NOx sensors to detect the exhaust gas treatment efficiency in real time, and can determine whether the urea solution enters the exhaust gas channel normally, monitor the blockage of the high-pressure spray gun and provide feedback. Attached Figure Description

[0023] The invention, its features, shape, and advantages will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings. Like reference numerals denote like parts throughout the drawings. The drawings are not intentionally drawn to scale; the focus is on illustrating the spirit of the invention.

[0024] Figure 1 This is a flowchart illustrating the method for detecting blockage in the injection pipeline of the air-assisted dual-injection system in the SCR system provided in Embodiment 1 of the present invention.

[0025] Figure 2 This is a schematic diagram of a dual-jet-assisted SCR injection system provided in Embodiment 1 of the present invention.

[0026] Figure 3 This is an electrical connection diagram of a dual-jet-assisted SCR injection system provided in Embodiment 1 of the present invention. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but these are not intended to limit the scope of the invention.

[0028] Example 1:

[0029] For ease of explanation, Embodiment 1 of the present invention provides a dual-jet-assisted SCR injection system, such as... Figures 2-3As shown, the system includes a first high-pressure spray gun 1 for spraying atomized urea solution, a first exhaust gas passage 2 for treating engine exhaust, a high-pressure gas supply module 3 for supplying external high-pressure gas, a second high-pressure spray gun 4, a second exhaust gas passage 5, a urea tank 11, a urea supply module 12, a urea metering module 13 for controlling urea solution spraying, a urea purging and cleaning module 31, a sensor module 6 for data acquisition, a controller 7, a locomotive ECU 8, and a power module 9. The first high-pressure spray gun 1 is located inside the first exhaust gas passage 2; the high-pressure gas supply module 3 is connected to the first high-pressure spray gun 1 via a pipeline; the second high-pressure spray gun 4 is located inside the second exhaust gas passage 5; the high-pressure gas supply module 3 is connected to the second high-pressure spray gun 4 via a pipeline; the urea tank 11 and... The urea supply module 12 is connected via pipelines; the urea supply module 12 is connected to the urea metering module 13 via pipelines; the urea metering module 13 is connected to the first high-pressure spray gun 1 via pipelines; the urea metering module 13 is connected to the second high-pressure spray gun 4 via pipelines; the urea blowing and cleaning module 31 is connected to the high-pressure air supply module 3 via pipelines; the controller 7 is electrically connected to the urea supply module 12, the urea metering module 13, the high-pressure air supply module 3, the urea blowing and cleaning module 31, and the sensor module 6; the locomotive ECU 8 is electrically connected to the controller 7; the power module 9 is electrically connected to the controller 7, the urea supply module 12, the urea metering module 13, the high-pressure air supply module 3, the urea blowing and cleaning module 31, the locomotive ECU 8, and the sensor module 6.

[0030] Both the first exhaust gas passage 2 and the second exhaust gas passage 5 include an exhaust pipe 21, a DPF carrier 22, and an SCR carrier 23; the exhaust gas emission direction in the exhaust pipe 21 is taken as the front-to-back direction of the exhaust pipe 21; the DPF carrier 22 and the SCR carrier 23 are placed inside the exhaust pipe 21; the DPF carrier 22 is located in front of the SCR carrier 23; the first high-pressure spray gun 1 is located between the DPF carrier 22 and the SCR carrier 23 in the first exhaust gas passage 2; the second high-pressure spray gun 4 is located between the DPF carrier 22 and the SCR carrier 23 in the second exhaust gas passage 5.

[0031] The sensor module 6 includes several temperature sensors 61, differential pressure sensors 62, and NOx sensors 63; all temperature sensors 61 are distributed inside the exhaust pipe 21; all temperature sensors 61 are located in front of the DPF carrier 22; all differential pressure sensors 62 are distributed in the pipeline between the urea supply module 12 and the urea metering module 13; all NOx sensors 63 are distributed inside the exhaust pipe 21; and all NOx sensors 63 are located on the front and rear sides of the SCR carrier 23 respectively.

[0032] When using the dual-jet assisted SCR injection system, the locomotive ECU8 determines whether the locomotive engine is running, and the temperature sensor 61 monitors the temperature inside the exhaust pipe 21. If the engine is running, the controller 7 controls the urea supply module 12 to draw urea solution from the urea tank 11. The urea metering module 13 opens the metering valve to send the urea solution to the first high-pressure spray gun 1 and the second high-pressure spray gun 4. The differential pressure sensor 62 in the pipeline records the pressure difference of the urea solution in the pipeline. At the same time, the high-pressure gas supply module 3 supplies high-pressure gas to the first high-pressure spray gun 1 and the second high-pressure spray gun 4 to assist the first high-pressure spray gun 1 and the second high-pressure spray gun 4. The urea solution in gun 4 is atomized and sprayed by the first high-pressure spray gun 1 in the first exhaust gas channel 2 and the second high-pressure spray gun 4 in the second exhaust gas channel 5. The exhaust gas is first filtered by the DPF carrier 22. The filtered exhaust gas and the atomized urea solution are mixed and pass through the SCR carrier 23 in the exhaust pipe 21 for catalytic reaction. The NOx content before and after exhaust gas treatment is recorded by the front and rear NOx sensors 63. After the exhaust gas treatment is completed, the high-pressure gas supply module 3 supplies high-pressure gas to the urea purging and cleaning module 31, which removes the residual urea solution in the pipeline and spray gun.

[0033] However, when using this dual-jet-assisted SCR injection system, if the injection unit becomes clogged, the design of the two high-pressure spray guns will prolong the time required for clog detection, making it impossible to specifically inspect the two high-pressure spray guns and their pipelines. To solve this problem, such as Figure 3 As shown in Embodiment 1 of the present invention, a method for detecting blockage in the injection pipeline of an air-assisted dual-injection system in an SCR system includes the following steps:

[0034] S101: Start the train engine and turn on the urea pump to build up pressure;

[0035] S102: After the urea pump has built up pressure, wait for the urea solution to be sprayed.

[0036] S103: When the urea solution injection state is met, the pipeline blockage detection module is activated; the two metering valves in the urea metering module in the injection unit are set to be normally open for 1 second. At this time, the urea pump delivers urea solution to the injection unit. The urea solution flows through two pipelines. The differential pressure sensor in the pipeline obtains the urea pressure in the two pipelines respectively and determines whether the urea pressure is normal. When the urea pressure is greater than the target pressure, the pipeline is identified as blocked and the first fault mode is entered.

[0037] S104: After the pipeline blockage detection is completed, determine whether the urea solution injection conditions are met; if the urea solution injection conditions are not met, shut down the engine and end the system operation.

[0038] S105: When the urea solution injection conditions are met, activate the spray gun blockage detection module; install a front NOx sensor in front of the SCR carrier in both exhaust gas channels, and a rear NOx sensor in rear of the SCR carrier in both exhaust gas channels; open the metering valves of the two high-pressure spray guns in the injection unit, so that the front NOx sensor in the two exhaust gas channels counts the NOx content before exhaust gas treatment, and the rear NOx sensor counts the NOx content after exhaust gas treatment; calculate the NOx conversion efficiency of the two exhaust gas channels based on the data from the front and rear NOx sensors, and determine whether the NOx conversion efficiency is normal; if the conversion efficiency is less than the target value, the high-pressure spray gun in that channel is considered blocked, and enter the second fault mode; if the conversion efficiency is greater than the target value, re-execute S104.

[0039] S106: When the engine is determined to be off, the spray gun blockage detection is considered complete, and the system operation ends.

[0040] The method for detecting blockage in the injection pipeline of the air-assisted dual-injection system in the SCR system provided in Embodiment 1 of the present invention discloses a pipeline blockage detection method and a spray gun blockage detection method in steps S103 and S105. Since the air-assisted dual-injection system is adopted, it uses two exhaust gas channels to treat exhaust gas simultaneously. For this purpose, two high-pressure spray guns are equipped. The two high-pressure spray guns are supplied with the urea solution required for injection by two pipelines. When the high-pressure spray guns cannot spray urea solution normally, it is impossible to accurately and quickly find the cause of the abnormality of the high-pressure spray guns. By first detecting pipeline blockage and then detecting spray gun blockage, the specific location of the blockage of the two high-pressure spray guns and their pipelines can be detected, effectively locating the blockage location and reducing the time of manual inspection.

[0041] The method for detecting blockage in the injection pipeline of the air-assisted dual-jet system in the SCR system provided in Embodiment 1 of the present invention includes steps S101 to S102, which prepare for pipeline blockage detection and high-pressure spray gun detection, so that the urea pump can supply urea solution to the pipeline normally.

[0042] In step S103, the pipeline blockage detection is performed by placing a differential pressure sensor in the pipeline. The urea pressure is used to determine whether there is crystal blockage in the pipeline. When there is crystal blockage in the pipeline, the pressure of the urea solution in the pipeline will increase, and the urea pressure will rise. The differential pressure sensor can clearly monitor the urea pressure, thereby determining whether there is crystal blockage in the pipeline.

[0043] In step S104, in order to fully meet the conditions for the reaction between NOx and urea solution, the judgment of the urea solution injection conditions is added to control the reaction conditions between NOx and urea solution in the two exhaust pipes, so that the actual NOx conversion efficiency is more referential and more conducive to demonstrating the existence of crystallization blockage in the high-pressure spray gun.

[0044] If the pipeline blockage detection fails to prove that there is crystallization blockage in the pipeline, in step S105, the method of calculating the NOx conversion efficiency will be used to determine whether there is near blockage in the high-pressure spray gun. When there is crystallization blockage in the high-pressure spray gun, the front NOx sensor will detect the NOx content of the exhaust gas before treatment, and the rear NOx sensor will detect the NOx content of the exhaust gas after treatment. The NOx conversion efficiency in the exhaust gas channel can be calculated by using the data from the front and rear NOx sensors. If the NOx conversion efficiency in the exhaust gas channel is low, the high-pressure spray gun fails to spray a normal amount of urea solution per unit time, which indicates that there is crystallization blockage in the high-pressure spray gun.

[0045] The method for detecting injection pipeline blockage in the air-assisted dual-injection system of the SCR system provided in Embodiment 1 of the present invention preferably involves the injection state in step S102 being that the urea pump pressure reaches the pressure build-up threshold and is maintained in the state after pressure build-up. After the urea pump is turned on to build up pressure in step S101, it is necessary to maintain the urea pump pressure so that it can continuously and uniformly supply urea solution to the pipeline. When detecting pipeline blockage, continuously and uniformly supplying urea solution to the pipeline can accurately obtain the pressure of urea solution in the pipeline per unit time, and can more effectively compare it with the target pressure to obtain a more accurate judgment. When detecting spray gun blockage, continuously and uniformly supplying urea solution can control the amount of urea solution injected into the exhaust gas channel per unit time, and can obtain a more accurate NOx conversion efficiency. Compared with the target conversion efficiency, it can better determine whether there is crystal blockage in the high-pressure spray gun.

[0046] The method for detecting blockage in the injection pipeline of the air-assisted dual-injection system in the SCR system provided in Embodiment 1 of the present invention preferably includes an injection condition in step S104 where the exhaust temperature in the exhaust gas channel reaches 200°C. When judging the blockage of the high-pressure spray gun, in order to fully meet the conditions for the reaction between NOx and urea solution, it is necessary to add the judgment of the urea solution injection conditions, control the reaction temperature of NOx and urea solution in the two exhaust gas pipelines, so that the actual NOx conversion efficiency is more referential and more conducive to demonstrating the existence of crystallization blockage in the high-pressure spray gun.

[0047] The method for detecting blockage in the injection pipeline of the air-assisted dual-jet system in the SCR system provided in Embodiment 1 of the present invention preferably includes, after "entering the first fault mode" in step S103, feedback of the pipeline blockage information; when there is crystal blockage in the pipeline, the system is fed back the situation of crystal blockage in the pipeline by entering the first fault mode, which is distinguished from the situation of high-pressure spray gun blockage, and the actual situation of crystal blockage in the pipeline is fed back by the data collected by the differential pressure sensor.

[0048] The method for detecting blockage in the injection pipeline of the air-assisted dual-injection system in the SCR system provided in Embodiment 1 of the present invention preferably includes, after "entering the second fault mode" in step S105, feedback of blockage information of the high-pressure spray gun in that line; when there is crystal blockage in the high-pressure spray gun, by entering the second fault mode, feedback of the crystal blockage in the high-pressure spray gun to the system is provided to distinguish it from the pipeline blockage, and at the same time, relevant data on NOx conversion efficiency can be transmitted to the system to determine whether the actual blockage of the high-pressure spray gun is serious.

[0049] The method for detecting blockage in the injection pipeline of the air-assisted dual-injection system in the SCR system provided in Embodiment 1 of the present invention preferably uses the urea pressure in step S103 as the pressure generated by the urea solution being squeezed in the pipeline. When using the urea pressure to determine whether there is crystal blockage in the pipeline, the pressure of the urea solution in the pipeline will increase when there is crystal blockage, thus the urea pressure will rise. The urea pressure can be clearly monitored by the differential pressure sensor, thereby determining whether there is crystal blockage in the pipeline, and the data collected by the differential pressure sensor will provide feedback on the crystal blockage situation in the pipeline.

[0050] In summary, the detection method for injection pipeline blockage in the air-assisted dual-jet system of the SCR system provided by this invention can solve the problem that existing technologies cannot specifically detect the two high-pressure spray guns and their pipelines when the injection unit is blocked, thus achieving effective location of the blockage.

[0051] Those skilled in the art should understand that variations can be implemented by combining existing technology and the above embodiments, and will not be elaborated here. Such variations do not affect the essence of the present invention, and will not be elaborated here.

[0052] The preferred embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and the devices and structures not described in detail should be understood as being implemented in a manner common to the art; any possible variations and modifications made by those skilled in the art without departing from the technical solution of the present invention, or equivalent embodiments with equivalent changes, do not affect the essential content of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for detecting blockage in the injection pipeline of an air-assisted dual-injection system in an SCR system, characterized in that, Includes the following steps: S101: Start the train engine and turn on the urea pump to build up pressure; S102: After the urea pump has built up pressure, wait for the urea solution to be sprayed. S103: When the urea solution injection state is met, the pipeline blockage detection module is activated; the two metering valves in the urea metering module in the injection unit are set to be normally open for 1 second. At this time, the urea pump delivers urea solution to the injection unit. The urea solution flows through two pipelines. The differential pressure sensor in the pipeline obtains the urea pressure in the two pipelines respectively and determines whether the urea pressure is normal. When the urea pressure is greater than the target pressure, the pipeline is identified as blocked and the first fault mode is entered. S104: After the pipeline blockage detection is completed, determine whether the conditions for urea solution injection are met; If the conditions for urea solution injection are not met, shut down the engine and terminate the system operation; S105: When the urea solution injection conditions are met, activate the spray gun blockage detection module; install a front NOx sensor in front of the SCR carrier in both exhaust gas channels, and a rear NOx sensor in rear of the SCR carrier in both exhaust gas channels; open the metering valves of the two high-pressure spray guns in the injection unit, so that the front NOx sensor in the two exhaust gas channels counts the NOx content before exhaust gas treatment, and the rear NOx sensor counts the NOx content after exhaust gas treatment; calculate the NOx conversion efficiency of the two exhaust gas channels based on the data from the front and rear NOx sensors, and determine whether the NOx conversion efficiency is normal; if the conversion efficiency is less than the target value, the high-pressure spray gun in that channel is considered blocked, and enter the second fault mode; if the conversion efficiency is greater than the target value, re-execute S104. S106: When the engine is determined to be off, the spray gun blockage detection is considered complete, and the system operation ends.

2. The method for detecting blockage in the injection pipeline of the air-assisted dual-injection system in the SCR system as described in claim 1, characterized in that, The injection state in step S102 is when the urea pump pressure reaches the pressure build-up threshold and maintains the state after pressure build-up.

3. The method for detecting blockage in the injection pipeline of the air-assisted dual-injection system in the SCR system as described in claim 1, characterized in that, The injection condition in step S104 is that the exhaust temperature in the exhaust gas passage reaches 200°C.

4. The method for detecting blockage in the injection pipeline of the air-assisted dual-injection system in the SCR system as described in claim 1, characterized in that, After "entering the first fault mode" in step S103, the method also includes feeding back information about the blockage of the pipeline.

5. The method for detecting blockage in the injection pipeline of the air-assisted dual-injection system in the SCR system as described in claim 1, characterized in that, After "entering the second fault mode" in step S105, the system also includes providing feedback on the blockage of the high-pressure spray gun.

6. The method for detecting blockage in the injection pipeline of the air-assisted dual-injection system in the SCR system as described in claim 1, characterized in that, The urea pressure in step S103 is the pressure generated when the urea solution is squeezed in the pipeline.

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