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CN-122014387-A - Improved ship engine SCR device ventilation realization method

CN122014387ACN 122014387 ACN122014387 ACN 122014387ACN-122014387-A

Abstract

The invention discloses an improved ship engine SCR device ventilation realization method, which relates to the technical field of ship engines and comprises the steps of signal acquisition, acquisition of differential pressure signals of a differential pressure sensor PDT501 before and after an SCR stop valve, boost time processing, adjustment of the number of auxiliary air supply channels according to differential pressure rise time when a ventilation function is executed for the first time, determination of an air supply strategy corresponding to target boost time, ventilation execution, control of urea spray gun atomizing air, blowing air and injection of compressed air into SCR pipelines by a plurality of soot blowing pipelines according to the air supply strategy, circulation control based on upper and lower limits of differential pressure, differential pressure monitoring and alarm, and real-time monitoring of differential pressure. According to the invention, ventilation and air supply are realized by utilizing the original SCR urea spray gun and the soot blowing pipeline, the self-adaptive setting of the boosting time and the closed-loop control of the pressure difference are combined, the positive pressure can be stably maintained without an independent ventilation pipeline and an electromagnetic valve, devices with different specifications are adapted, the cost is reduced, and the reliability is improved.

Inventors

  • HONG WEIHUA
  • LI ZHIFENG
  • RAO WEI
  • LV SONGTAO
  • ZHONG JUNHE
  • An Yijie

Assignees

  • 宜昌船舶柴油机有限公司

Dates

Publication Date
20260512
Application Date
20260310

Claims (10)

  1. 1. An improved ship engine SCR device ventilation implementation method is characterized by comprising the following steps: Step 1, collecting signals, namely collecting pressure difference signals of a pressure difference sensor PDT501 before and after an SCR stop valve, and receiving host ventilation command signals; Step 2, a step of processing boosting time, namely setting the number of auxiliary air supply channels according to the rising time of the pressure difference when the ventilation function is executed for the first time, and determining an air supply strategy corresponding to the target boosting time; step 3, ventilation executing step, namely controlling atomization air and purge air of a urea spray gun and injection of compressed air into an SCR pipeline by a plurality of soot blowing pipelines according to the air supply strategy, and performing circulation control based on the upper limit and the lower limit of pressure difference; and step 4, a differential pressure monitoring and alarming step, namely monitoring the differential pressure in real time, starting a low pressure alarming logic when the ventilation instruction is effective, and closing an alarm when the ventilation instruction is ineffective.
  2. 2. The improved ventilation implementation method of the SCR device of the marine engine according to claim 1, wherein the differential pressure signal acquisition and processing in step 1 comprises: Circularly sampling analog quantity signals of a differential pressure sensor PDT501 before and after the SCR stop valve according to the frequency of 1 time/0.5 second; Performing maximum value and minimum value elimination processing on a plurality of sampling values which are continuously acquired; constructing a sliding window average filtering model for the residual sampling values to obtain a stable voltage difference value; transmitting the stable differential pressure value to an SCR controller in real time and displaying the stable differential pressure value on an operation interface; Wherein the PDT501 is measured in the range of-1 bar to 1bar.
  3. 3. The improved ventilation implementation method of the SCR device of the marine engine according to claim 1, wherein the logic control of the ventilation command in step 1 comprises: When the host ventilation command is switched from invalid to valid, starting a ventilation mode and enabling the low-pressure alarm logic to be in an activated state; When the host ventilation command is switched from effective to ineffective, the air supply electromagnetic valve is closed and an alarm shielding signal is sent to the controller; while maintaining the continuous acquisition and display function of the differential pressure value uninterrupted.
  4. 4. The improved ventilation implementation method of an SCR device for a marine engine according to claim 1, wherein the step 2 boost time treatment comprises: When the ventilation instruction is executed for the first time, an atomization air electromagnetic valve, a purging air electromagnetic valve and a soot blowing branch pipe electromagnetic valve of the urea spray gun are simultaneously opened; Monitoring a first boost time required for the differential pressure to reach a set upper limit; after the pressure difference falls back to the set lower limit, reducing the input quantity of one path of soot blowing branch pipe electromagnetic valve and measuring the boosting time again; And repeatedly adjusting until the boosting time approaches to the target boosting time, so as to determine the number of soot blowing pipelines put into ventilation operation.
  5. 5. The improved marine engine SCR device ventilation implementation of claim 4, wherein the target boost time satisfies: the target boost time is less than the low ventilation pressure alarm triggering time; and the target boost time is 50% -60% of the alarm trigger delay time.
  6. 6. The improved ventilation implementation method of an SCR device of a marine engine as defined in claim 1, wherein said step 3 comprises: After receiving the ventilation instruction, opening a corresponding electromagnetic valve according to the air supply strategy determined in the step 2; Closing the air supply solenoid valve when the PDT501 differential pressure value is above an upper limit; and opening the air supply electromagnetic valve when the PDT501 pressure difference value is lower than the lower limit value so as to maintain the positive pressure in the SCR pipeline.
  7. 7. The improved marine engine SCR device ventilation implementation of claim 6, wherein the upper pressure differential limit is 0.12bar. The lower limit value of the pressure difference is 0.02bar.
  8. 8. The improved ship engine SCR device ventilation implementation method according to claim 1, wherein in the step 3, a polling opening mode is adopted for soot blowing branch pipe electromagnetic valves participating in ventilation, when the total number of soot blowing branch pipes is N, the number of the input ventilation operation is m, each round of ventilation sequentially selects codes with different numbers and the number of the soot blowing branch pipe electromagnetic valves participate in air supply until all branch pipes participate in polling.
  9. 9. The improved ventilation implementation method of an SCR device of a marine engine as defined in claim 1, wherein said step 4 comprises: when the pressure difference is lower than a set value and the duration exceeds the alarm triggering time in the valid state of the ventilation instruction, a ventilation pressure low alarm signal is output; In the ventilation command disabled state, only the differential pressure value is displayed without triggering an alarm.
  10. 10. The improved ship engine SCR device ventilation implementation method according to claim 1, wherein the ventilation air supply channel adopts an atomization air channel, a purging air channel and a soot blowing air pipeline of an original urea spray gun of the SCR system.

Description

Improved ship engine SCR device ventilation realization method Technical Field The invention relates to the technical field of marine engines, in particular to an improved method for realizing ventilation of an SCR device of a marine engine. Background A Selective Catalytic Reduction (SCR) system is widely used in the fields of marine diesel engines and dual-fuel engines as an important exhaust aftertreatment device for satisfying IMO emission regulations for marine engines. When the marine host is in TierII operating conditions, service conditions, or there is a potential leakage risk for the dual fuel system, ventilation treatment of the SCR system is typically required to prevent exhaust or flammable gases from stagnating inside the SCR reactor and pipeline. The ventilation function of the ship SCR system is usually realized by adopting an independent ventilation air supply pipeline and a special ventilation electromagnetic valve. The independent ventilation system is characterized in that an SCR controller controls a ventilation electromagnetic valve to be opened and closed, the flow is limited through a fixed throttle plate, and the ventilation pressure state is judged according to signals of a pressure difference sensor before and after an SCR stop valve. When the shortage of the positive pressure in the SCR is detected, the ventilation electromagnetic valve is controlled to be opened to inject compressed air into the pipeline so as to maintain a certain positive pressure. However, in the prior art, the system integration level is low in practical application, independent ventilation pipelines and valves are usually required to be independently constructed in the installation stage of a ship factory, installation errors, neglected loading or debugging difficulties are easily caused by site layout differences or insufficient construction coordination, the existing ventilation flow is determined in advance by a throttle orifice plate, when the volumes of SCR pipelines are different due to ship type, arrangement or modification, fixed flow is difficult to match with different volume requirements, the boosting time deviation is overlarge or the ventilation effect is unstable, the traditional ventilation control mostly adopts a single-threshold start-stop mode, the optimization of the boosting time and the alarm delay logic design are lacked, and frequent start-stop or false alarm phenomena are easily caused. Disclosure of Invention The invention aims to provide an improved ship engine SCR device ventilation implementation method so as to solve the problems in the background technology. In order to achieve the purpose, the invention provides the following technical scheme that the improved ship engine SCR device ventilation achieving method comprises the following steps: Step 1, collecting signals, namely collecting pressure difference signals of a pressure difference sensor PDT501 before and after an SCR stop valve, and receiving host ventilation command signals; Step 2, a step of processing boosting time, namely setting the number of auxiliary air supply channels according to the rising time of the pressure difference when the ventilation function is executed for the first time, and determining an air supply strategy corresponding to the target boosting time; step 3, ventilation executing step, namely controlling atomization air and purge air of a urea spray gun and injection of compressed air into an SCR pipeline by a plurality of soot blowing pipelines according to the air supply strategy, and performing circulation control based on the upper limit and the lower limit of pressure difference; and step 4, a differential pressure monitoring and alarming step, namely monitoring the differential pressure in real time, starting a low pressure alarming logic when the ventilation instruction is effective, and closing an alarm when the ventilation instruction is ineffective. Preferably, the differential pressure signal collecting and processing in step 1 includes: Circularly sampling analog quantity signals of a differential pressure sensor PDT501 before and after the SCR stop valve according to the frequency of 1 time/0.5 second; Performing maximum value and minimum value elimination processing on a plurality of sampling values which are continuously acquired; constructing a sliding window average filtering model for the residual sampling values to obtain a stable voltage difference value; transmitting the stable differential pressure value to an SCR controller in real time and displaying the stable differential pressure value on an operation interface; Wherein the PDT501 is measured in the range of-1 bar to 1bar. Preferably, the ventilation command logic control in step 1 includes: When the host ventilation command is switched from invalid to valid, starting a ventilation mode and enabling the low-pressure alarm logic to be in an activated state; When the host ventilation command is switched from effective to