A control method for a dual jet assisted SCR injection system

Abstract

The application provides a control method of a double-jet assisted SCR injection system, and relates to the technical field of tail gas treatment.The control method comprises the following steps: initializing the double-jet assisted SCR injection system, determining whether a pressure building condition is met, starting pressure building, counting urea injection quantity by a urea metering module in a jet unit, determining whether the urea injection quantity under the pressure is met, starting a pipeline blockage detection module, opening an atomization electromagnetic valve, waiting for a urea solution injection state, starting a urea injection module, injecting a quantitative urea solution into tail gas discharged from two exhaust channels, starting a lance blockage detection module, and starting a purge module to blow away residual urea liquid in a pipeline and a high-pressure lance by using high-pressure gas after the engine is stopped.The control method of the double-jet assisted SCR injection system can solve the problem that the prior art cannot schedule various function modules of the double-jet assisted SCR injection system, and effectively controls the double-jet assisted SCR injection system.

Description

Technical Field

[0001] This invention relates to the field of exhaust gas treatment technology, and in particular to a control method for a dual-jet assisted SCR injection 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, there is no specific control method for this dual-jet-assisted SCR injection system in the existing technology, and the control method for this dual-jet-assisted SCR injection system faces the problem of scheduling the various functional modules of the system. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a control method for a dual-jet-assisted SCR injection system, which solves the problem that existing technologies cannot schedule the various functional modules of a dual-jet-assisted SCR injection system, thereby achieving effective control of the dual-jet-assisted SCR injection system.

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

[0007] The present invention provides a control method for a dual-jet-assisted SCR injection system, comprising the following steps:

[0008] S101: Initialize the dual-jet-assisted SCR injection system and determine whether the pressure build-up conditions of the urea pump are met; if the pressure build-up conditions are met, start the train engine; if the pressure build-up conditions are not met, repeat S101.

[0009] S102: After starting the train engine, start the urea pump to build up pressure. The urea pump draws urea solution from the urea tank and maintains pressure to deliver it to the injection unit. The urea metering module in the injection unit counts the urea injection volume and determines whether it meets the urea injection volume under this pressure. If it does not meet the urea injection volume, the pressure building fails and S101 is executed again. When the urea metering module determines that the pressure building has failed three times in a row, it enters the fault mode.

[0010] S103: After the urea pump completes pressure build-up, the pipeline blockage detection module is activated to detect whether residual urea crystals in the pipeline are causing blockage; if the pipeline blockage detection is abnormal, the system enters fault mode.

[0011] S104: After the pipeline blockage detection is completed, open the atomizing solenoid valve to fully mix the urea solution and air in the high-pressure spray gun, and wait for the urea solution to be sprayed.

[0012] S105: After the urea solution enters the injection state, start the urea injection module and spray a fixed amount of urea solution into the exhaust gas discharged from the two exhaust channels by the high-pressure spray gun.

[0013] S106: After the urea solution is sprayed, the spray gun blockage detection module is activated to detect whether the crystallization of residual urea in the high-pressure spray gun causes blockage. If the high-pressure spray gun is not blocked, S105 is executed repeatedly until the engine stops. If the high-pressure spray gun is blocked, the fault mode is entered.

[0014] S107: After the engine stops, start the purging module to purge the residual urea liquid in the pipes and high-pressure spray gun with high-pressure gas; shut down the dual-jet assisted SCR injection system.

[0015] The control method for the dual-jet-assisted SCR injection system provided by the present invention preferably includes a pressure build-up condition in step S101 where the temperature in the exhaust channel reaches 180°C.

[0016] The control method for the dual-jet-assisted SCR injection system provided by the present invention preferably includes, after the step of "entering fault mode", stopping the system operation and waiting for personnel to perform maintenance.

[0017] The control method of the dual-jet-assisted SCR injection system provided by the present invention preferably includes a injection state in step S104 where the urea solution volume reaches the metering standard and the urea solution reaches the atomization state.

[0018] The above technical solution has the following advantages or beneficial effects:

[0019] The control method of the dual-jet-assisted SCR injection system provided by this invention uses the urea injection quantity counted by the urea metering module in the injection unit as the standard to determine whether the urea injection quantity meets the requirements under a constant pressure, thereby determining whether the system has completed pressure building. This method can detect whether the injection system can work normally while building pressure. When the urea metering module determines that pressure building has failed three times consecutively, the system will automatically enter the fault mode. The system provides three opportunities to build pressure, which increases the fault tolerance for pressure building and reduces pressure building failures caused by accidents. In other words, it is an automatic protection of the injection unit by the system.

[0020] The control method for a dual-jet-assisted SCR injection system provided by this invention includes a pipeline blockage detection module and a spray gun blockage detection module. These modules detect whether residual urea crystals in the pipeline are causing blockages, and whether residual urea crystals in the high-pressure spray gun are causing blockages. Since the dual-jet-assisted SCR injection system uses one pipeline to supply urea to one high-pressure spray gun, it has two exhaust gas channels and is equipped with two high-pressure spray guns. To clearly identify why the high-pressure spray gun in the dual-jet-assisted SCR injection system cannot spray urea solution and reduce the time required for system maintenance, the pipeline blockage detection module and the spray gun blockage detection module can specifically detect the two high-pressure spray guns and their pipelines, effectively locating the blockage position and reducing the time required for manual inspection.

[0021] The control method of the dual-jet-assisted SCR injection system provided by this invention sets up a urea injection module, and controls two high-pressure spray guns to inject urea into two exhaust gas channels respectively, thereby treating the exhaust gas discharged in the exhaust gas channels and improving the treatment efficiency of fuel train exhaust gas. By judging whether the engine has stopped, the exhaust gas of fuel train is automatically treated, reducing the time for manual operation and supervision.

[0022] The control method of the dual-jet-assisted SCR injection system provided by this invention includes a purging module that uses high-pressure gas to purge residual urea liquid from the pipeline and high-pressure spray gun, preventing residual liquid crystallization that could cause pipeline and high-pressure spray gun blockage. This reduces system failures caused by pipeline and high-pressure spray gun blockage, improves the overall efficiency of the system, and reduces the time cost of manual inspection and maintenance. 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 of a control method for a dual-jet-assisted SCR injection 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 2-3 As 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, this dual-jet-assisted SCR injection system lacks a specific control method for scheduling the functional modules within the system and controlling its operation. To address this issue, such as... Figure 1 As shown, Embodiment 1 of the present invention provides a control method for a dual-jet-assisted SCR injection system, comprising the following steps:

[0034] S101: Initialize the dual-jet-assisted SCR injection system and determine whether the pressure build-up conditions of the urea pump are met; if the pressure build-up conditions are met, start the train engine; if the pressure build-up conditions are not met, repeat S101.

[0035] S102: After starting the train engine, start the urea pump to build up pressure. The urea pump draws urea solution from the urea tank and maintains pressure to deliver it to the injection unit. The urea metering module in the injection unit counts the urea injection volume and determines whether it meets the urea injection volume under this pressure. If it does not meet the urea injection volume, the pressure building fails and S101 is executed again. When the urea metering module determines that the pressure building has failed three times in a row, it enters the fault mode.

[0036] S103: After the urea pump completes pressure build-up, the pipeline blockage detection module is activated to detect whether residual urea crystals in the pipeline are causing blockage; if the pipeline blockage detection is abnormal, the system enters fault mode.

[0037] S104: After the pipeline blockage detection is completed, open the atomizing solenoid valve to fully mix the urea solution and air in the high-pressure spray gun, and wait for the urea solution to be sprayed.

[0038] S105: After the urea solution enters the injection state, start the urea injection module and spray a fixed amount of urea solution into the exhaust gas discharged from the two exhaust channels by the high-pressure spray gun.

[0039] S106: After the urea solution is sprayed, the spray gun blockage detection module is activated to detect whether the crystallization of residual urea in the high-pressure spray gun causes blockage. If the high-pressure spray gun is not blocked, S105 is executed repeatedly until the engine stops. If the high-pressure spray gun is blocked, the fault mode is entered.

[0040] S107: After the engine stops, start the purging module to purge the residual urea liquid in the pipes and high-pressure spray gun with high-pressure gas; shut down the dual-jet assisted SCR injection system.

[0041] The control method for the dual-jet-assisted SCR injection system provided in Embodiment 1 of the present invention, in step S101, judges the pressure build-up condition. If the pressure build-up condition is met, the engine is started. If the pressure build-up condition is not met and the engine is started, it may have a certain impact on the dual-jet-assisted SCR injection system. The pressure build-up condition forms a protection for the dual-jet-assisted SCR injection system.

[0042] In step S102, a pressure-building module is set up. Using the urea injection volume counted by the urea metering module in the injection unit as the standard, it is determined whether the injection volume meets the urea injection volume under a constant pressure, thus determining whether the system has completed pressure building. This method can detect whether the injection system can work normally while building pressure. When the urea metering module determines that pressure building has failed three times in a row, the system will automatically enter the fault mode. The system provides three opportunities to build pressure, which increases the fault tolerance for pressure building and reduces pressure building failures caused by accidents. In other words, it is the system's automatic protection for the injection unit.

[0043] In steps S103 and S106, a pipeline blockage detection module and a spray gun blockage detection module are set up to detect whether residual urea crystals in the pipeline cause pipeline blockage, and whether residual urea liquid crystals in the high-pressure spray gun cause high-pressure spray gun blockage. Since the dual-jet-assisted SCR injection system uses one pipeline to supply urea to one high-pressure spray gun, the dual-jet-assisted SCR injection system is designed with two exhaust gas channels, and therefore is equipped with two high-pressure spray guns. In order to clearly identify the reason why the high-pressure spray gun in the dual-jet-assisted SCR injection system cannot spray urea solution and reduce the time required for system maintenance, the pipeline blockage detection module and the spray gun blockage detection module can specifically detect the two high-pressure spray guns and their pipelines, effectively locate the blockage location, and reduce the time required for manual inspection.

[0044] In step S104, by opening the atomizing solenoid valve, the urea solution and air are fully mixed in the high-pressure spray gun, and the system waits for the urea solution to be sprayed. This allows the exhaust gas to be reacted with the urea solution as soon as it is discharged, improving the efficiency of the system in treating exhaust gas and reducing the waiting time for the urea solution to be treated.

[0045] In step S105, a urea injection module is set up. By controlling two high-pressure spray guns to inject urea into the two exhaust gas channels respectively, the exhaust gas discharged in the exhaust gas channels is treated, which improves the treatment efficiency of exhaust gas from fuel-powered trains. By judging whether the engine has stopped, the exhaust gas from fuel-powered trains is automatically treated, reducing the time for manual operation and supervision.

[0046] In step S107, a purging module is set up to purge the residual urea liquid in the pipeline and high-pressure spray gun with high-pressure gas, so as to prevent the residual liquid from crystallizing and causing pipeline blockage and high-pressure spray gun blockage, thereby reducing system failures caused by pipeline blockage and high-pressure spray gun blockage, improving the overall working efficiency of the system, and reducing the time cost of manual inspection and maintenance.

[0047] The control method of the dual-jet-assisted SCR injection system provided in Embodiment 1 of the present invention preferably includes a pressure build-up condition in step S101 where the temperature inside the exhaust channel reaches 180°C. When the temperature inside the exhaust channel reaches 180°C, it is beneficial for the exhaust gas inside the exhaust channel to react with the atomized urea solution, thereby improving the system's efficiency in treating train exhaust gas.

[0048] The control method for the dual-jet-assisted SCR injection system provided in Embodiment 1 of the present invention preferably includes, after the step of "entering fault mode", stopping the system operation and waiting for personnel to maintain it; this avoids the system continuously trying to achieve failed results, thus reducing the system's service life and effectively protecting the system's safety.

[0049] The control method of the dual-jet-assisted SCR injection system provided in Embodiment 1 of the present invention preferably involves the injection state in step S104 being that the amount of urea solution reaches the metering standard and the urea solution reaches the atomization state. By preparing the urea solution in advance and making it atomized, it can react better with the exhaust gas in the exhaust channel afterward, reducing the reaction time required between the urea solution and the exhaust gas and improving the efficiency of exhaust gas treatment.

[0050] In summary, the control method for a dual-jet-assisted SCR injection system provided by this invention can solve the problem that existing technologies cannot schedule the various functional modules of a dual-jet-assisted SCR injection system, thereby achieving effective control of the dual-jet-assisted SCR injection system.

[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 control method for a dual-jet-assisted SCR injection system, characterized in that, Includes the following steps: S101: Initialize the dual-jet-assisted SCR injection system and determine whether the pressure build-up conditions of the urea pump are met; if the pressure build-up conditions are met, start the train engine; if the pressure build-up conditions are not met, repeat S101. S102: After starting the train engine, start the urea pump, build up pressure in the urea pump, and the urea pump draws urea solution from the urea tank and maintains pressure to deliver it to the injection unit. The urea injection volume is counted by the urea metering module in the injection unit to determine whether the injection volume of urea is in line with the pressure. If the injection volume of urea does not meet the requirements, the pressure build-up will fail and S101 will be executed again. If the urea metering module determines that the pressure build-up has failed three times in a row, it will enter the fault mode. S103: After the urea pump completes pressure building, the pipeline blockage detection module is activated to detect whether residual urea crystals in the pipeline are causing pipeline blockage. If the pipeline blockage detection is abnormal, the system will enter fault mode. S104: After the pipeline blockage detection is completed, open the atomizing solenoid valve to fully mix the urea solution and air in the high-pressure spray gun, and wait for the urea solution to be sprayed. S105: After the urea solution enters the injection state, start the urea injection module and spray a fixed amount of urea solution into the exhaust gas discharged from the two exhaust channels by the high-pressure spray gun. S106: After the urea solution is sprayed, the spray gun blockage detection module is activated to detect whether the crystallization of residual urea in the high-pressure spray gun causes blockage. If the high-pressure spray gun is not blocked, S105 is executed repeatedly until the engine stops. If the high-pressure spray gun is blocked, the fault mode is entered. S107: After the engine stops, start the purging module to purge the residual urea liquid in the pipes and high-pressure spray gun with high-pressure gas; shut down the dual-jet assisted SCR injection system.

2. The control method for the dual-jet-assisted SCR injection system as described in claim 1, characterized in that, In step S101, the pressure build-up condition is that the temperature inside the exhaust channel reaches 180°C.

3. The control method for the dual-jet-assisted SCR injection system as described in claim 1, characterized in that, The step of "entering fault mode" also includes stopping the system and waiting for personnel to repair it.

4. The control method for the dual-jet-assisted SCR injection system as described in claim 1, characterized in that, The spraying state in step S104 is when the amount of urea solution reaches the metering standard and the urea solution reaches the atomization state.

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