A methanol injection system for a marine dual-fuel low-speed diesel engine

Abstract

A methanol injection system for a marine dual-fuel low-speed diesel engine includes a methanol injection valve, a methanol inlet valve, an injection control valve, a purge valve, a pressure sensor, a pressure reducing valve, a sealing oil control valve, a purge relief valve, a servo oil common rail, and a methanol common rail. The methanol injection valve has the functions of pressurizing and injecting methanol and is connected to the methanol common rail via the methanol inlet valve, the servo oil common rail via the injection control valve, and the servo oil common rail via the pressure reducing valve and the sealing oil control valve. The pressure sensor is located on the methanol injection valve and is connected to the main engine control system. Two purge valves are respectively connected to the methanol injection valve and between the methanol common rail and the methanol inlet valve. The purge relief valve is connected between the methanol injection valve and the methanol inlet valve. The methanol injection system achieves stable methanol injection from the main engine and purges and releases residual methanol under different operating conditions. The present invention has the advantages of simple structure, precise control, high safety, good economy, high reliability, good versatility, and energy conservation and environmental protection.

Description

Technical Field

[0001] The invention relates to a fuel system of a marine dual-fuel low-speed diesel engine, in particular to a methanol injection system of the marine dual-fuel low-speed diesel engine, belonging to the technical field of diesel engines. Background Art

[0002] With the increasing adoption of clean fuels in low-speed marine diesel engines and the global search for low-carbon fuels in the shipping industry, methanol has emerged as a green fuel, increasingly being adopted by ships. Methanol, also known as hydroxymethane (CH3OH), has a chemical formula of CH3OH. It is high in oxygen, sulfur-free, and burns at a low temperature. Compared to conventional diesel, methanol combustion produces no sulfur compounds, while reducing solid particulate matter, nitrogen oxides, and carbon dioxide emissions by 90%, 70%, and 15%, respectively, making it a green and clean energy source. However, methanol is also a flammable and toxic liquid. As a marine engine fuel, it carries a higher risk than conventional diesel fuel. A leak could cause an engine room fire and potentially cause crew casualties, with potentially serious consequences for the safety of the ship and its crew. Therefore, ensuring its safe and stable entry into the cylinders for combustion is crucial for the proper operation of the main engine and the safety of the vessel.

[0003] During normal operation of a dual-fuel diesel engine using methanol, methanol is transported to the dual-fuel low-speed diesel engine through the supply pipeline. The methanol injection system continuously and stably injects methanol into the cylinder to achieve continuous and stable operation of the dual-fuel diesel engine. At the same time, the methanol injection amount is precisely controlled according to the signal sent by the diesel engine control system to realize the load change of the diesel engine. Summary of the Invention

[0004] The purpose of the present invention is to provide a methanol injection system for a marine dual-fuel low-speed diesel engine. While ensuring stable injection of methanol into the cylinder, the system monitors the injection pressure of the methanol in real time. Once an abnormal situation occurs, the methanol supply is cut off and the remaining methanol in the pipeline is purged and discharged. This purge and discharge function is implemented in an emergency, providing effective safety protection for the safe operation of the dual-fuel diesel engine.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A methanol injection system for a marine dual-fuel low-speed diesel engine, wherein the main engine of the marine dual-fuel low-speed diesel engine includes a cylinder, a main engine control system, a belt pump, a methanol daily cabinet, and a discharge cabinet; the methanol injection system includes:

[0007] A methanol injection valve is provided on the cylinder and integrates the pressurization and injection functions of methanol;

[0008] A methanol common rail pipe is connected to the methanol daily cabinet and is used to transport methanol fuel;

[0009] A methanol inlet valve, the upstream end of which is connected to the methanol common rail pipe and the downstream end of which is connected to the methanol injection valve. The methanol inlet valve is connected to the host control system and is controlled by the host control system to control the inflow of methanol;

[0010] A servo oil common rail pipe is connected to the engine belt pump and is used to transport servo oil;

[0011] An injection control valve, the upstream end of which is connected to the servo oil common rail pipe, and the downstream end of which is connected to the methanol injection valve. The injection control valve is connected to the host control system and controlled by the host control system, and is used to control the start of the methanol injection valve;

[0012] A pressure reducing valve, the upstream end of which is connected to the servo oil common rail pipe, and is used to reduce the pressure of the servo oil to the sealing oil of the set pressure;

[0013] a sealing oil control valve, the upstream end of which is connected to the downstream end of the pressure reducing valve, and the downstream end of which is connected to the methanol injection valve; the sealing oil control valve is connected to and controlled by the host control system, and is used to control the sealing oil to enter the methanol injection valve to prevent methanol backflow;

[0014] a pressure sensor, disposed on the methanol injection valve and connected to the host control system, for monitoring the methanol injection pressure of the methanol injection valve and feeding back the pressure to the host control system;

[0015] Two purge valves, one purge valve connected to the methanol injection valve, and the other purge valve connected to the pipeline between the methanol common rail pipe and the methanol inlet valve, the purge valves being connected to and controlled by the host control system to control the entry of purge medium;

[0016] a purge relief valve connected to the pipeline between the methanol injection valve and the methanol inlet valve, and connected to the relief cabinet, for discharging the methanol purged from the methanol injection valve;

[0017] The methanol injection system completes the methanol injection and purging and discharge of the host under different working conditions.

[0018] As a further improvement, the methanol injection system further includes:

[0019] A methanol accumulator is connected to the pipeline between the methanol injection valve and the methanol inlet valve, and is used to absorb the pulse pressure fluctuations generated by the methanol in the pipeline and maintain pressure stability;

[0020] The servo oil accumulator is connected to the pipeline between the methanol injection valve and the injection control valve, and is used to absorb the pulse pressure fluctuations generated by the servo oil in the pipeline to maintain pressure stability.

[0021] As a further improvement, when the host control system cuts off the injection of methanol, the purge valve opens, and the purge medium purges and discharges the remaining methanol in the methanol injection system.

[0022] As a further improvement, after receiving the opening instruction from the host control system, the injection control valve controls the servo oil to enter the methanol injection valve, pressurizes the methanol to a pressure of 600 bar and injects it into the cylinder.

[0023] As a further improvement, when the pressure sensor detects that the injection pressure of the methanol injection valve deviates from the normal working range, the host control system issues an instruction to close the methanol inlet valve, cut off the supply and injection of methanol, and the host switches to diesel operation mode.

[0024] As a further improvement, the methanol injection system completes the methanol injection and purge discharge of the host under different working conditions, including:

[0025] Methanol injection process: In the methanol operating mode of the main engine, the methanol inlet valve opens, the methanol in the methanol common rail pipe is transported to the methanol injection valve, the injection control valve opens after receiving the command from the main engine control system, and the high-pressure servo oil in the servo oil common rail pipe enters the methanol injection valve, pressurizing the methanol to the injection pressure and injecting it into the cylinder. After the injection is completed, the injection control valve closes, completing one injection;

[0026] Purge and discharge process - when the main engine is switched from methanol operation mode to diesel operation mode, or an abnormal situation occurs in the methanol operation mode, the main engine control system instructs the injection control valve and the methanol inlet valve to close, and at the same time the two purge valves and the purge and discharge valve are opened. The purge medium purges the oil-containing methanol in the methanol injection valve through one purge valve and is discharged to the discharge cabinet through the purge and discharge valve. The purge medium purges the methanol in the methanol common rail pipe back to the methanol daily cabinet through the other methanol injection valve.

[0027] As a further improvement, the pressure of methanol in the methanol common rail pipe is 13 bar, and the pressure of high-pressure servo oil in the servo oil common rail pipe is 300 bar.

[0028] The present invention realizes the safe and stable injection of methanol fuel for a marine dual-fuel low-speed diesel engine, as well as the cutting off of methanol supply and the purging and discharge of residual methanol in the pipeline under abnormal circumstances, thereby ensuring the safe and stable operation of the ship and the safety of the life and health of the crew.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. Simple structure and easy maintenance - There are no complex components in the methanol injection system, with a simple structure and easy maintenance.

[0031] 2. Precise control - Each valve in the system operates according to the instructions of the host control system and is controlled by common rail hydraulic oil, with high real-time performance and precise valve movement control.

[0032] 3. Multifunctional integration - the methanol injection system integrates the functions of methanol injection control, injection pressure monitoring, and purge and discharge, and has high integration.

[0033] 4. High safety - Real-time monitoring and control of methanol injection pressure are realized, and a double insurance design of methanol inlet and injection two-way control is adopted for methanol entering the cylinder, ensuring the safe operation of the system.

[0034] 5. Good economy - the system is equipped with two purge valves to purge the methanol in the methanol injection valve and the methanol common rail pipe respectively. The oily methanol purged back into the discharge cabinet can also be used together with diesel, without wasting methanol.

[0035] 6. High reliability - The present invention utilizes basic hydraulic principles and adopts hydraulic power to control valve components, which has simple structure, high reliability, durability and long service life.

[0036] 7. Good versatility - only appropriate changes and adjustments need to be made to the selection of components such as pressure sensors and pressure reducing valves to make it applicable to various dual-fuel low-speed diesel engines such as methanol, LPG, and ammonia.

[0037] 8. Energy saving and environmental protection - The methanol injection valve is driven by the existing servo oil system of the diesel engine, which has low energy consumption, safety and environmental protection.

[0038] In summary, the present invention has the advantages of simple structure, precise control, high integration, high safety, good economy, high reliability, good versatility, easy maintenance, energy saving and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a system principle diagram of the present invention.

[0040] In the figure,

[0041] 1—Methanol injection valve, 2—Methanol inlet valve, 3—Injection control valve, 4—Purge valve, 5—Pressure sensor, 6—Pressure reducing valve, 7—Methanol accumulator, 8—Servo oil accumulator, 9—Sealing oil control valve, 10—Purge relief valve, 11—Servo oil common rail, 12—Methanol common rail. DETAILED DESCRIPTION

[0042] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings in order to more clearly understand the structure and use of the present invention, but this does not limit the scope of protection of the present invention.

[0043] The present invention is used for the injection, purge, and discharge of methanol fuel in a marine dual-fuel, low-speed diesel engine. The following description uses a single methanol injection valve as an example. The main engine of a marine dual-fuel, low-speed diesel engine typically has multiple methanol injection valves installed on multiple cylinders, along with an engine control system, a drive pump, a methanol daily cabinet, and a discharge cabinet.

[0044] See also Figure 1 The methanol injection system includes a methanol injection valve 1, a methanol inlet valve 2, an injection control valve 3, a purge valve 4, a pressure sensor 5, a pressure reducing valve 6, a methanol accumulator 7, a servo oil accumulator 8, a sealing oil control valve 9, a purge relief valve 10, a servo oil common rail pipe 11, a methanol common rail pipe 12 and connecting pipelines, etc.

[0045] The methanol injection valve 1 is arranged on the cylinder and integrates the pressurization and injection functions of methanol.

[0046] The methanol common rail pipe 12 is connected to the methanol daily tank of the marine dual-fuel low-speed diesel engine and is used to transport methanol fuel at a pressure of 13 bar.

[0047] The methanol inlet valve 2 is connected to the methanol common rail pipe 12 at its upstream end and the methanol injection valve 1 at its downstream end through a pipeline. The methanol inlet valve 2 is connected to and controlled by the host control system to control the entry of methanol. In the open state, methanol enters the methanol injection valve 1 of each cylinder. In the closed state, methanol cannot enter the methanol injection valve 1 and the cylinder.

[0048] The servo oil common rail pipe 11 is connected to the engine pump of the marine dual-fuel low-speed diesel engine and is used to deliver servo oil with a pressure of 300 bar to each cylinder.

[0049] The injection control valve 3 is connected to the servo oil common rail pipe 11 at its upstream end and the methanol injection valve 1 at its downstream end through a pipeline. The injection control valve 3 is connected to and controlled by the host control system to control the start-up of the methanol injection valve 1. After receiving the "open" command from the host control system, the injection control valve 3 controls the servo oil to enter the methanol injection valve 1, pushing the plunger of the methanol injection valve 1 to pressurize the methanol to an injection pressure of 600 bar and spray it into the cylinder.

[0050] The upstream end of the pressure reducing valve 6 is connected to the servo oil common rail pipe 11 for reducing the pressure of the servo oil to a set pressure of 20 bar, which serves as the sealing oil of the methanol injection valve 1 .

[0051] The upstream end of the sealing oil control valve 9 is connected to the downstream end of the pressure reducing valve 6, and the downstream end is connected to the methanol injection valve 1. The sealing oil control valve 9 is connected and controlled by the host control system, and is used to control the sealing oil to enter the methanol injection valve 1 to prevent methanol from flowing back to the servo oil system during the operation of the methanol injection valve 1.

[0052] The pressure sensor 5 is arranged on the methanol injection valve 1 and connected to the host control system, and is used to monitor the methanol injection pressure of the methanol injection valve 1 and feed it back to the host control system; if the injection pressure deviates from the normal working range, the host control system will issue an instruction to close the methanol inlet valve 2, cut off the supply and injection of methanol, and the host will switch to diesel mode operation.

[0053] The methanol accumulator 7 is connected to the pipeline between the methanol injection valve 1 and the methanol inlet valve 2, and is used to absorb the pulse pressure fluctuations generated by the methanol in the pipeline, maintain pressure stability, and reduce the impact of pressure fluctuations on the methanol injection system.

[0054] The servo oil accumulator 8 is connected to the pipeline between the methanol injection valve 1 and the injection control valve 3, and is used to absorb the pulse pressure fluctuations generated by the hydraulic oil in the pipeline, maintain pressure stability, and reduce the impact of pressure fluctuations on the methanol injection system.

[0055] The purge valve 4 is connected to and controlled by the host control system, and is used to control the entry of the purge medium (nitrogen); there are two purge valves 4, one is connected to the methanol injection valve 1, and the other purge valve 4 is connected to the pipeline between the methanol common rail pipe 12 and the methanol inlet valve 2; when the host control system cuts off the injection of methanol, the purge valve 4 opens, and the purge medium purges and discharges the remaining methanol in the methanol injection system.

[0056] The purge relief valve 10 is connected to the pipeline between the methanol injection valve 1 and the methanol inlet valve 2, and is connected to the relief cabinet of the marine dual-fuel low-speed diesel engine, and is used to discharge the oil-containing methanol purged from the methanol injection valve 1.

[0057] The methanol injection system performs methanol injection and purge / drainage for the marine dual-fuel low-speed diesel engine under different operating conditions. The system allows methanol to enter the methanol injection valve by opening and closing the methanol inlet valve. The servo oil control valve controls the operation of the methanol injection valve, pressurizing the methanol to the injection pressure and injecting it into the cylinder, achieving methanol combustion and work. A pressure sensor monitors the methanol injection pressure and feeds back a signal to the main engine control system, which then controls the opening and closing of various valves. If an abnormality occurs during methanol mode operation, the methanol injection system automatically cuts off the methanol supply, opens the purge valve, and allows purge medium to enter the methanol injection system, purging and draining any remaining methanol in the pipelines and valves, ensuring the safety of the ship's operation and personnel.

[0058] The specific working process of the present invention is as follows, please refer to Figure 1 :

[0059] Methanol injection process - In the methanol operation mode of the main engine, the methanol inlet valve 2 receives a command from the main engine control system and opens. The methanol fuel with a pressure of 13 bar in the methanol common rail pipe 12 is delivered to the methanol injection valve 1 through the methanol inlet valve 2. The injection control valve 3 opens after receiving an "open" command from the main engine control system. The high-pressure servo oil with a pressure of 300 bar in the servo oil common rail pipe 11 enters the methanol injection valve 1 through the injection control valve 3, pushing the plunger of the methanol injection valve 1 downward, pressurizing the methanol to the injection pressure and injecting it into the cylinder. After the injection is completed, the injection control valve 3 closes, and the plunger of the methanol injection valve 1 returns to its original position under the action of the spring force, completing one injection cycle.

[0060] Purge and discharge process - when the main engine is switched from methanol operation mode to diesel operation mode, or an abnormal situation occurs in the methanol operation mode, the main engine control system instructs the injection control valve 3 and the methanol inlet valve 2 to close, and at the same time the two purge valves 4 and the purge and discharge valve 10 are opened. The purge medium purges the oil-containing methanol in the methanol injection valve 1 through one purge valve 4 and is discharged to the discharge cabinet of the main engine through the purge and discharge valve 10. The purge medium purges the methanol in the methanol common rail pipe 12 back to the methanol daily cabinet through the other methanol injection valve 1.

[0061] The protection scope of the present invention is not limited to the above-mentioned embodiments, but should also include other obvious changes and alternatives to the present invention.

Claims

1. A methanol injection system for a marine dual-fuel low-speed diesel engine, wherein the main engine of the marine dual-fuel low-speed diesel engine comprises a cylinder, a main engine control system, a belt pump, a methanol daily tank, and a discharge tank; characterized by: The methanol injection system includes: A methanol injection valve is provided on the cylinder and integrates the pressurization and injection functions of methanol; A methanol common rail pipe is connected to the methanol daily cabinet and is used to transport methanol fuel; A methanol inlet valve, the upstream end of which is connected to the methanol common rail pipe and the downstream end of which is connected to the methanol injection valve. The methanol inlet valve is connected to the host control system and is controlled by the host control system to control the inflow of methanol; A servo oil common rail pipe is connected to the engine belt pump and is used to transport servo oil; An injection control valve, the upstream end of which is connected to the servo oil common rail pipe, and the downstream end of which is connected to the methanol injection valve. The injection control valve is connected to the host control system and controlled by the host control system, and is used to control the start of the methanol injection valve; A pressure reducing valve, the upstream end of which is connected to the servo oil common rail pipe, and is used to reduce the pressure of the servo oil to the sealing oil of the set pressure; a sealing oil control valve, the upstream end of which is connected to the downstream end of the pressure reducing valve, and the downstream end of which is connected to the methanol injection valve; the sealing oil control valve is connected to and controlled by the host control system, and is used to control the sealing oil to enter the methanol injection valve to prevent methanol backflow; a pressure sensor, disposed on the methanol injection valve and connected to the host control system, for monitoring the methanol injection pressure of the methanol injection valve and feeding back the pressure to the host control system; Two purge valves, one purge valve connected to the methanol injection valve, and the other purge valve connected to the pipeline between the methanol common rail pipe and the methanol inlet valve, the purge valves being connected to and controlled by the host control system to control the entry of purge medium; a purge relief valve connected to the pipeline between the methanol injection valve and the methanol inlet valve, and connected to the relief cabinet, for discharging the methanol purged from the methanol injection valve; The methanol injection system completes the methanol injection and purging and discharge of the host under different working conditions.

2. The methanol injection system for a marine dual-fuel low-speed diesel engine according to claim 1, characterized in that: The methanol injection system also includes: A methanol accumulator is connected to the pipeline between the methanol injection valve and the methanol inlet valve, and is used to absorb the pulse pressure fluctuations generated by the methanol in the pipeline and maintain pressure stability; The servo oil accumulator is connected to the pipeline between the methanol injection valve and the injection control valve, and is used to absorb the pulse pressure fluctuations generated by the servo oil in the pipeline to maintain pressure stability.

3. The methanol injection system for a marine dual-fuel low-speed diesel engine according to claim 1, characterized in that: When the host control system cuts off the injection of methanol, the purge valve opens, and the purge medium purges and discharges the remaining methanol in the methanol injection system.

4. The methanol injection system for a marine dual-fuel low-speed diesel engine according to claim 1, characterized in that: After receiving the opening instruction from the host control system, the injection control valve controls the servo oil to enter the methanol injection valve, pressurizes the methanol to a pressure of 600 bar and injects it into the cylinder.

5. The methanol injection system for a marine dual-fuel low-speed diesel engine according to claim 1, characterized in that: When the pressure sensor detects that the injection pressure of the methanol injection valve deviates from the normal operating range, the host control system issues an instruction to close the methanol inlet valve, cut off the supply and injection of methanol, and the host switches to the diesel operation mode.

6. The methanol injection system for a marine dual-fuel low-speed diesel engine according to claim 1, characterized in that: The methanol injection system completes the methanol injection and purge discharge of the host under different working conditions, including: Methanol injection process: In the methanol operating mode of the main engine, the methanol inlet valve opens, the methanol in the methanol common rail pipe is transported to the methanol injection valve, the injection control valve opens after receiving the command from the main engine control system, and the high-pressure servo oil in the servo oil common rail pipe enters the methanol injection valve, pressurizing the methanol to the injection pressure and injecting it into the cylinder. After the injection is completed, the injection control valve closes, completing one injection; Purge and discharge process - when the main engine is switched from methanol operation mode to diesel operation mode, or an abnormal situation occurs in the methanol operation mode, the main engine control system instructs the injection control valve and the methanol inlet valve to close, and at the same time the two purge valves and the purge and discharge valve are opened. The purge medium purges the oil-containing methanol in the methanol injection valve through one purge valve and is discharged to the discharge cabinet through the purge and discharge valve. The purge medium purges the methanol in the methanol common rail pipe back to the methanol daily cabinet through another purge valve.

7. The methanol injection system for a marine dual-fuel low-speed diesel engine according to claim 6, characterized in that: The pressure of methanol in the methanol common rail pipe is 13 bar, and the pressure of high-pressure servo oil in the servo oil common rail pipe is 300 bar.

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