A fuel supply control method for development of a marine methanol engine

Abstract

The application discloses a kind of fuel supply control methods for the development of marine methanol engine, belong to methanol engine technical field, using marine methanol engine fuel supply equipment, fuel supply equipment includes: first thermometer, first stop valve, variable frequency supply pump, heat exchanger, fine filter, second thermometer, first pressure gauge, flowmeter and supply valve, the conveying pipe between heat exchanger and fine filter is connected with backflow pipe, backflow pipe is provided with electric control pressure regulating valve and is connected to methanol temporary storage tank with other end, control method includes: pre-preparation stage, pressure building standby stage, steady state operation stage and dynamic adjustment stage, by supply pump variable frequency and pressure regulating valve backflow collaborative control, can according to demand quickly adjust methanol supply pressure, realize that methanol supply pressure is adjusted quickly and stably, simultaneously only single flowmeter can measure the methanol consumption of engine, reduce the error of flow calibration, reduce unnecessary energy consumption, it is favorable to improve system energy efficiency ratio.

Description

Technical Field

[0001] This invention belongs to the field of methanol engine technology, specifically relating to a fuel supply control method for the development of marine methanol engines. Background Technology

[0002] Methanol fuel, as a carbon-neutral clean energy source, has significantly lower combustion emissions than petroleum combustion, and its application in the field of marine engines is becoming increasingly widespread.

[0003] Currently, methanol fuel supply systems are mainly used in large marine methanol engines. The system consists of a methanol fuel storage container, a methanol fuel supply unit, and a methanol fuel valve assembly connected in sequence. The methanol fuel supply unit delivers methanol fuel to the engine via a constant-speed pump, and excess methanol flows back to the methanol fuel storage container through an overflow valve and return line. This solution is well-suited for large marine engines; however, because the engine's operating conditions are essentially constant, the methanol supply pressure of the system is also constant and unadjustable, failing to meet the development needs of large marine methanol engines with varying methanol supply pressure requirements.

[0004] Meanwhile, because the methanol supply pressure in the methanol fuel supply system is uncontrollable, to ensure sufficient methanol supply, the methanol pump's methanol delivery rate is always greater than the engine's methanol demand. Only a portion of the methanol supplied to the engine is used and consumed by the engine; the unused methanol fuel flows back to the methanol storage tank through the return pipeline, which is detrimental to improving the system's energy efficiency ratio. Moreover, measuring the engine's methanol consumption requires two flow meters, which is prone to data errors and affects the flow calibration during engine development. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a fuel supply control method for the development of marine methanol engines, which can adjust the methanol supply pressure according to demand, meet the development needs of large marine methanol engines with different methanol supply pressure requirements, reduce flow calibration error, and improve system energy efficiency ratio.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0007] A fuel supply control method for the development of a marine methanol engine, employing a marine methanol engine fuel supply device, the fuel supply device comprising: a methanol storage tank and a delivery pipe connected between the methanol storage tank and the engine, wherein the delivery pipe is sequentially provided with a first thermometer, a first shut-off valve, a variable frequency supply pump, a heat exchanger, a fine filter, a second thermometer, a first pressure gauge, a flow meter, and a supply valve from one end near the methanol storage tank to one end near the engine;

[0008] The delivery pipe between the heat exchanger and the fine filter is connected to a return pipe. The return pipe is equipped with an electrically controlled pressure regulating valve and its other end is connected to the methanol temporary storage tank. The top of the methanol temporary storage tank is connected to a nitrogen supply pipe, a liquid replenishment pipe, and a breather pipe. The other end of the nitrogen supply pipe is connected to a nitrogen supply source. The liquid replenishment pipe is equipped with a liquid replenishment valve and its other end is connected to the methanol refueling station. The breather pipe is equipped with an exhaust valve.

[0009] The control method includes the following steps:

[0010] S1. Pre-preparation stage: Nitrogen gas is introduced into the methanol storage tank through the nitrogen supply pipe, the replenishment valve automatically controls the replenishment, and the exhaust valve maintains the safe pressure in the methanol storage tank.

[0011] S2, Pressure Buildup and Standby Stage: Start the supply pump, methanol enters the delivery pipe and passes through the heat exchanger and fine filter in sequence. The pressure regulating valve is kept at a small opening to build up the reference pressure. After the pressure and temperature reach the target, the supply valve is opened, the system enters the standby state, and sends a preparation completion signal to the engine ECU, and the engine starts.

[0012] S3. Steady-state operation stage: The supply pump matches the amount of alcohol used by the engine and operates at a constant speed. The pressure regulating valve is at a small opening to compensate for backflow. The flow meter collects the engine consumption in real time.

[0013] S4. Dynamic Adjustment Stage: Detects engine load. When the engine load increases suddenly, the pressure regulating valve closes quickly to reduce backflow, and the supply pump increases speed to compensate for the flow. When the engine load decreases suddenly, the pressure regulating valve opens quickly to increase backflow, and the supply pump decreases speed to reduce flow, maintaining stable pressure.

[0014] Furthermore, the fuel supply equipment also includes a PLC control system, which is electrically connected to the supply pump and the pressure regulating valve. Step S1 also includes a system status self-check.

[0015] When the system self-test is qualified, proceed to step S2. When the system self-test is unqualified, the PLC control system outputs a fault alarm or shutdown signal and sends a shutdown signal to the engine ECU.

[0016] Furthermore, in step S2, the opening of the pressure regulating valve is 4% to 8% when establishing the reference pressure.

[0017] Furthermore, in step S3, the specific method for matching the methanol supply pump to the engine for constant-speed operation is as follows: the methanol flow rate is collected by a flow meter, and the speed of the supply pump is set according to the pre-established methanol flow rate and supply pump speed MAP.

[0018] Furthermore, in step S3, the specific method for compensating for backflow at a small opening of the pressure regulating valve is as follows: the methanol flow rate is collected by a flow meter, and the corresponding target pressure is found based on the pre-established methanol flow rate and the target pressure of the required fuel MAP. The PLC control system collects the parameters of the first pressure gauge, and uses the found target pressure as a reference to adjust the opening of the pressure regulating valve using PID closed-loop control.

[0019] Furthermore, the delivery pipe between the first shut-off valve and the supply pump is connected to a vent pipe, the vent pipe is equipped with a second shut-off valve and a vent pump, and the other end is connected to a receiving container; the delivery pipe between the flow meter and the supply valve is connected to the nitrogen supply source through a nitrogen backflush pipe, the nitrogen backflush pipe is equipped with a first check valve, and the nitrogen supply pipe is equipped with a second check valve and a pressure reducing valve.

[0020] Furthermore, when the engine stops, the engine ECU sends a stop signal to the PLC control system. After receiving the stop signal, the PLC control system determines whether the engine stops normally or due to a fault.

[0021] When the engine is in a normal shutdown, the supply pump is stopped and the supply valve is closed. When the engine is in a fault shutdown, the supply pump is stopped, the supply valve is closed, the venting pump is started, and the first check valve is opened.

[0022] Furthermore, a second pressure gauge and a level gauge are installed at the top of the methanol storage tank. The PLC control system monitors the temperature, pressure, level, and flow parameters in the fuel supply equipment and performs graded protection actions when the system set values ​​are exceeded.

[0023] Furthermore, the graded protection actions include audible and visual alarm actions and shutdown actions.

[0024] Furthermore, the return pipe is divided into two paths at one end near the delivery pipe. One path is equipped with the pressure regulating valve, and the other path is equipped with a mechanical safety valve. When the PLC control system detects that the pressure in the fuel supply equipment exceeds the system set value, it determines that the electrical control has failed, and the mechanical safety valve opens to release pressure.

[0025] After adopting the above technical solution, the beneficial effects of the present invention are:

[0026] In the fuel supply control method for marine methanol engines disclosed in this invention, all methanol supplied to the engine is consumed by the engine without any backflow. Only one flow meter is needed to measure the engine's methanol consumption, reducing the error in flow calibration. The supply pump uses a variable frequency pump, which can adjust the motor speed of the supply pump according to the actual methanol consumption or system requirements, reducing unnecessary energy consumption and improving the system's energy efficiency ratio. The variable frequency of the supply pump and the backflow control of the pressure regulating valve are coordinated, which can adjust the methanol supply pressure according to demand. When the engine's flow demand changes rapidly, the rapid response of the pressure regulating valve can compensate for the relatively slow response of the supply pump, achieving rapid and stable adjustment of the methanol supply pressure.

[0027] In this invention, during the pre-preparation phase, the PLC control system performs a system status self-check. During the steady-state operation phase, the PLC control system monitors the temperature, pressure, liquid level, and flow parameters in the supply equipment, and executes safety protection actions when the system set values ​​are exceeded, thus ensuring that the system is always in a safe state.

[0028] In this invention, the safety protection actions executed by the PLC control system are specifically graded protection actions, including audible and visual alarm actions and shutdown actions. That is, when slight parameter drift or instantaneous signal fluctuation occurs, only audible and visual alarms are triggered without triggering shutdown, which can reduce unnecessary shutdowns and improve development efficiency.

[0029] In this invention, a mechanical safety valve is installed on the return pipe. When the PLC control system fails to control the pressure regulating valve and / or the supply pump, the pressure in the delivery pipe cannot be kept stable. When the pressure in the supply equipment exceeds the system set value, the PLC control system judges that the electrical control has failed. After the pressure rises to a certain value, the mechanical safety valve opens to release pressure, thereby protecting the system. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the principle structure of the fuel supply device for marine methanol engines developed according to the present invention;

[0031] Figure 2 This is a logic diagram of the fuel supply control method for marine methanol engines developed according to the present invention;

[0032] In the diagram, 1-methanol temporary storage tank, 2-transfer pipe, 3-first thermometer, 4-first shut-off valve, 5-supply pump, 6-heat exchanger, 7-fine filter, 8-second thermometer, 9-first pressure gauge, 10-flow meter, 11-supply valve, 12-engine, 13-return pipe, 14-pressure regulating valve, 15-mechanical safety valve, 16-methanol refueling station, 17-replenishment pipe, 18-replenishment valve, 19-nitrogen supply source, 20-nitrogen backflush pipe, 21-first check valve, 22-nitrogen supply pipe, 23-second check valve, 24-pressure reducing valve, 25-breathing pipe, 26-exhaust valve, 27-exhaust head, 28-second pressure gauge, 29-level gauge, 30-relief pipe, 31-second shut-off valve, 32-relief pump, 33-collection container. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and embodiments. Preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the textual part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but they should not be construed as limiting the scope of protection of the present invention.

[0034] like Figure 1 As shown, a fuel supply control method for the development of a marine methanol engine is provided. The method employs a marine methanol engine fuel supply device, which includes a methanol storage tank 1 and a delivery pipe 2 connected between the methanol storage tank 1 and the engine 12. The delivery pipe 2 is provided with a first thermometer 3, a first shut-off valve 4, a variable frequency supply pump 5, a heat exchanger 6, a fine filter 7, a second thermometer 8, a first pressure gauge 9, a flow meter 10, and a supply valve 11 in sequence from the end near the methanol storage tank 1 to the end near the engine.

[0035] A return pipe 13 is connected to the delivery pipe 2 between the heat exchanger 6 and the fine filter 7. An electrically controlled pressure regulating valve 14 is installed on the return pipe 13, and its other end is connected to the methanol storage tank 1. The top of the methanol storage tank 1 is connected to a nitrogen supply pipe 22, a liquid replenishment pipe 17, and a breather pipe 25. The other end of the nitrogen supply pipe 22 is connected to a nitrogen supply source 19. Nitrogen enters the methanol storage tank 1 to fill it, which reduces the contact between methanol and air, inertizes the gas environment inside the methanol storage tank 1, and improves system safety.

[0036] Specifically, a replenishment valve 18 is installed on the replenishment pipe 17 and the other end is connected to the methanol refueling station 16. The replenishment valve 18 is a float valve, which automatically opens when the liquid level in the methanol temporary storage tank 1 is low and automatically cuts off the feed when it exceeds the set height.

[0037] The supply pump 5 can adjust its motor speed according to the actual methanol consumption and supply pressure requirements of the engine. The pressure regulating valve 14 is a pneumatic valve with equal percentage adjustment, which can respond quickly. When the system's methanol supply pressure and flow rate are stable, the pressure regulating valve 14 maintains a small pressure regulation compensation opening. When the engine's methanol demand increases sharply and the adjustment response of the supply pump 5 is slow, the PLC control system controls the opening of the pressure regulating valve 14 to decrease to ensure a rapid response in system flow and pressure regulation. The frequency conversion control of the supply pump 5 and the backflow regulation of the pressure regulating valve 14 can respond quickly, making the methanol supply flow rate variable and the pressure regulation rapid and stable.

[0038] An exhaust valve 26 is provided on the breathing tube 25. The exhaust valve 26 can be a breathing valve, which will automatically open when the pressure in the methanol temporary storage tank 1 is too high. An exhaust head 27 is provided at the end of the breathing tube 25 away from the methanol temporary storage tank 1. A filter device can be installed in the exhaust head 27 to filter out the methanol vapor and discharge the internal nitrogen. Alternatively, it can be directly connected to a gas collection container.

[0039] like Figure 2 As shown, the control method includes the following steps:

[0040] Step S1, Pre-preparation stage: Nitrogen gas is introduced into methanol temporary storage tank 1 through nitrogen supply pipe 22, liquid replenishment valve 18 automatically controls liquid replenishment, and exhaust valve 26 maintains safe pressure inside methanol temporary storage tank 1.

[0041] Specifically, the fuel supply equipment also includes a PLC control system. The PLC control system is responsible for collecting system data, controlling each component of the fuel supply equipment, and monitoring the system to ensure it is in a safe state. The PLC control system is electrically connected to the fuel supply pump 5 and the pressure regulating valve 14. Step S1 also includes a system status self-check. When the system self-check is successful, the process proceeds to step S2. When the system self-check fails, the PLC control system outputs a fault alarm or shutdown signal and sends a shutdown signal to the engine ECU.

[0042] Step S2, Pressure Buildup and Standby Stage: Start the supply pump 5, methanol enters the delivery pipe 2 and passes through the heat exchanger 6 and the fine filter 7 in sequence. The pressure regulating valve 14 maintains a small opening to reflux and establish the reference pressure. After the pressure and temperature reach the standard, open the supply valve 11, the system enters the standby state, and sends a preparation completion signal to the engine ECU, and the engine starts.

[0043] Preferably, in step S2, the opening degree of the pressure regulating valve 14 is 4% to 8% when establishing the reference pressure.

[0044] Step S3, steady-state operation stage: The supply pump 5 is matched with the engine to operate at a constant speed for the amount of alcohol used, the pressure regulating valve 14 is opened at a small degree to compensate for backflow, and the flow meter 10 collects the engine consumption in real time.

[0045] In step S3, the specific method for matching the methanol supply pump 5 to the engine for constant-speed operation is as follows: the methanol flow rate is collected by the flow meter 10, and the speed of the supply pump 5 is set according to the pre-established methanol flow rate and the speed MAP of the supply pump 5.

[0046] In step S3, the specific method for compensating backflow at the small opening of the pressure regulating valve 14 is as follows: the methanol flow rate is collected by the flow meter 10, the corresponding target pressure is found according to the pre-established methanol flow rate and the target pressure MAP of the required fuel, the PLC control system collects the parameters of the first pressure gauge 9, and the opening of the pressure regulating valve 14 is adjusted by using PID closed-loop control based on the found target pressure.

[0047] Step S4, Dynamic Adjustment Stage: The load condition of engine 12 is detected. When the engine load increases suddenly, the pressure regulating valve 14 quickly closes to reduce backflow, and the supply pump 5 synchronously increases its speed to compensate for the flow. When the engine load decreases suddenly, the pressure regulating valve 14 quickly opens to increase backflow, and the supply pump 5 synchronously decreases its speed to reduce the flow, maintaining stable pressure. The engine load can be collected from the engine ECU. The specific calculation method has been disclosed in existing technology and will not be elaborated here.

[0048] Preferred in this application, such as Figure 1 As shown, the delivery pipe 2 between the flow meter 10 and the supply valve 11 is connected to the nitrogen supply source 19 via a nitrogen backflush pipe 20. A first check valve 21 is installed on the nitrogen backflush pipe 20, and a second check valve 23 and a pressure reducing valve 24 are installed on the nitrogen supply pipe 22. The nitrogen pressure after pressure reduction by the pressure reducing valve 24 is lower than the exhalation pressure of the exhaust valve 26. When the gas pressure in the methanol storage tank 1 reaches the exhalation pressure, the exhaust valve 26 will automatically open to discharge some of the gas in the methanol storage tank 1, preventing the gas pressure in the methanol storage tank 1 from becoming too high. The first check valve 21 prevents methanol from flowing into the nitrogen backflush pipe 20, and the second check valve 23 prevents gas or liquid in the methanol storage tank 1 from flowing into the nitrogen inerting pipe.

[0049] The first shut-off valve 4 and the supply pump 5 are connected to the delivery pipe 2, which is connected to the discharge pipe 30. The discharge pipe 30 is equipped with a second shut-off valve 31 and a discharge pump 32, and the other end is connected to the sewage or discharge collection container 33.

[0050] like Figure 2 As shown, when the engine stops, the engine ECU sends a stop signal to the PLC control system. After receiving the stop signal, the PLC control system determines whether the engine stops normally or malfunctions (i.e., maintenance stop). When the engine stops normally, the supply pump 5 is stopped and the supply valve 11 is closed. When the engine stops malfunction, the supply pump 5 is stopped, the supply valve 11 is closed, the vent pump 32 is started, and the first check valve 21 is opened to drain residual alcohol from the pipeline before component disassembly and maintenance.

[0051] In this application, such as Figure 1 and Figure 2 As shown, a second pressure gauge 28 and a level gauge 29 are installed at the top of the methanol storage tank 1. The PLC control system monitors the temperature, pressure, level, and flow parameters in the fuel supply equipment and executes graded protection actions when the system set values ​​are exceeded. The graded protection actions include PLC online protection (i.e., audible and visual alarm action) and shutdown action. Specifically, when the corresponding first set threshold is exceeded, only the audible and visual alarm action is executed; when the corresponding second set threshold is exceeded (greater than the first set threshold), the shutdown action is executed. The PLC control system collects system parameters through the first thermometer 3, the second thermometer 8, the first pressure gauge 9, the flow meter 10, the second pressure gauge 28, and the level gauge 29. These data serve as the data support for the operation of the control system, which executes system self-protection actions and safety protection actions to always ensure that the system is in a safe state.

[0052] Furthermore, the return pipe 13 is divided into two paths near the delivery pipe 2. One path is equipped with a pressure regulating valve 14, and the other path is equipped with a mechanical safety valve 15. When the PLC control system detects that the pressure in the fuel supply equipment exceeds the system set value, it determines that the electrical control has failed. The mechanical safety valve 15 opens to release pressure, which can prevent the pressure in the delivery pipe 2 from becoming too high when the system control fails.

[0053] The fuel supply control method for marine methanol engines of the present invention uses frequency conversion of the supply pump and backflow coordinated control of the pressure regulating valve to quickly adjust the methanol supply pressure according to demand, achieving rapid and stable adjustment of the methanol supply pressure. At the same time, it ensures that all the methanol delivered to the engine is used and consumed by the engine, without backflow. Only a single flow meter is needed to measure the methanol consumption of the engine, reducing the error of flow calibration and reducing unnecessary energy consumption, which is beneficial to improving the system energy efficiency ratio.

[0054] In the description of this specification, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Unless otherwise expressly defined, terms such as "set," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0055] While specific embodiments of the present invention have been described above, those skilled in the art should understand that the described embodiments are merely some, not all, of the present invention. These are merely illustrative examples, and the scope of protection of the present invention is defined by the claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention and without any inventive effort, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A fuel supply control method for the development of marine methanol engines, characterized in that, A marine methanol engine fuel supply device is adopted. The fuel supply device includes: a methanol storage tank and a delivery pipe connected between the methanol storage tank and the engine. The delivery pipe is provided with a first thermometer, a first shut-off valve, a variable frequency supply pump, a heat exchanger, a fine filter, a second thermometer, a first pressure gauge, a flow meter and a supply valve in sequence from the end near the methanol storage tank to the end near the engine. The delivery pipe between the heat exchanger and the fine filter is connected to a return pipe. The return pipe is equipped with an electrically controlled pressure regulating valve and its other end is connected to the methanol temporary storage tank. The top of the methanol temporary storage tank is connected to a nitrogen supply pipe, a liquid replenishment pipe, and a breather pipe. The other end of the nitrogen supply pipe is connected to a nitrogen supply source. The liquid replenishment pipe is equipped with a liquid replenishment valve and its other end is connected to the methanol refueling station. The breather pipe is equipped with an exhaust valve. The control method includes the following steps: S1. Pre-preparation stage: Nitrogen gas is introduced into the methanol storage tank through the nitrogen supply pipe, the replenishment valve automatically controls the replenishment, and the exhaust valve maintains the safe pressure in the methanol storage tank. S2, Pressure Buildup and Standby Stage: Start the supply pump, methanol enters the delivery pipe and passes through the heat exchanger and fine filter in sequence. The pressure regulating valve is kept at a small opening to build up the reference pressure. After the pressure and temperature reach the target, the supply valve is opened, the system enters the standby state, and sends a preparation completion signal to the engine ECU, and the engine starts. S3. Steady-state operation stage: The supply pump matches the amount of alcohol used by the engine and operates at a constant speed. The pressure regulating valve is at a small opening to compensate for backflow. The flow meter collects the engine consumption in real time. S4. Dynamic Adjustment Stage: Detects engine load. When the engine load increases suddenly, the pressure regulating valve closes quickly to reduce backflow, and the supply pump increases speed to compensate for the flow. When the engine load decreases suddenly, the pressure regulating valve opens quickly to increase backflow, and the supply pump decreases speed to reduce flow, maintaining stable pressure.

2. The fuel supply control method for marine methanol engine development according to claim 1, characterized in that, The fuel supply equipment also includes a PLC control system, which is electrically connected to the supply pump and the pressure regulating valve. Step S1 also includes a system status self-check. When the system self-test is qualified, proceed to step S2. When the system self-test is unqualified, the PLC control system outputs a fault alarm or shutdown signal and sends a shutdown signal to the engine ECU.

3. The fuel supply control method for marine methanol engine development according to claim 2, characterized in that, In step S2, the pressure regulating valve opening is 4% to 8% when establishing the reference pressure.

4. The fuel supply control method for marine methanol engine development according to claim 3, characterized in that, In step S3, the specific method for matching the methanol supply pump to the engine for constant-speed operation is as follows: the methanol flow rate is collected by a flow meter, and the speed of the supply pump is set according to the pre-established methanol flow rate and supply pump speed MAP.

5. The fuel supply control method for marine methanol engine development according to claim 3, characterized in that, In step S3, the specific method for compensating backflow at the small opening of the pressure regulating valve is as follows: the methanol flow rate is collected by the flow meter, the corresponding target pressure is found according to the pre-established methanol flow rate and the target pressure of the required fuel MAP, the PLC control system collects the parameters of the first pressure gauge, and the opening of the pressure regulating valve is adjusted by using PID closed-loop control based on the found target pressure.

6. The fuel supply control method for marine methanol engine development according to claim 2, characterized in that, A vent pipe is connected to the delivery pipe between the first shut-off valve and the supply pump. The vent pipe is equipped with a second shut-off valve and a vent pump, and its other end is connected to a receiving container. The delivery pipe between the flow meter and the supply valve is connected to the nitrogen supply source through a nitrogen backflush pipe. A first check valve is installed on the nitrogen backflush pipe, and a second check valve and a pressure reducing valve are installed on the nitrogen supply pipe.

7. The fuel supply control method for marine methanol engine development according to claim 6, characterized in that, When the engine stops, the engine ECU sends a stop signal to the PLC control system. After receiving the stop signal, the PLC control system determines whether the engine stops normally or due to a fault. When the engine is in a normal shutdown, the supply pump is stopped and the supply valve is closed. When the engine is in a fault shutdown, the supply pump is stopped, the supply valve is closed, the venting pump is started, and the first check valve is opened.

8. The fuel supply control method for the development of marine methanol engines according to any one of claims 2 to 7, characterized in that, The top of the methanol storage tank is equipped with a second pressure gauge and a level gauge. The PLC control system monitors the temperature, pressure, level, and flow parameters in the fuel supply equipment and performs graded protection actions when the system set values ​​are exceeded.

9. The fuel supply control method for marine methanol engine development according to claim 8, characterized in that, The graded protection actions include audible and visual alarm actions and shutdown actions.

10. The fuel supply control method for marine methanol engine development according to claim 9, characterized in that, The return pipe is divided into two paths at one end near the delivery pipe. One path is equipped with the pressure regulating valve, and the other path is equipped with a mechanical safety valve. When the PLC control system detects that the pressure in the fuel supply equipment exceeds the system set value, it determines that the electrical control has failed, and the mechanical safety valve opens to release pressure.

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