Diesel engine methanol injection system with airtightness detection function and airtightness detection method

Abstract

The invention discloses a diesel engine methanol injection system with an airtight detection function, which is formed by communicating a methanol liquid inlet double-wall pipe, a methanol liquid return double-wall pipe, a methanol pressurizing unit and a high-pressure pipeline, the methanol liquid inlet double-wall pipe is communicated with a fresh water supply system through a liquid inlet stop valve, and the methanol liquid return double-wall pipe is provided with a liquid return stop valve; a liquid return chain pipe valve is communicated between the methanol liquid return double-wall pipe and the methanol pressurizing unit, and a communication valve is arranged between the methanol liquid inlet double-wall pipe and the methanol liquid return double-wall pipe; a communicating port of the high-pressure pipeline and the methanol pressurizing unit is plugged through a plugging tool which is detachably arranged on the methanol pressurizing unit, and a plurality of methanol pressure detection sensors are arranged on the methanol liquid inlet double-wall pipe and the methanol liquid return double-wall pipe respectively. According to the airtightness detection method for the marine methanol low-speed diesel engine, fresh water which has intersolubility with methanol is used as a tightness detection medium, complete tightness detection of a methanol spraying system of the marine methanol dual-fuel low-speed diesel engine is achieved, the detection efficiency is high, and the leakage point detection speed is high.

Description

Technical Field

[0001] The present invention relates to a diesel engine methanol injection system with an airtight detection function and an airtight detection method, belonging to the technical field of marine diesel engines. Background Art

[0002] In the field of ship transportation, the regulatory limits for emissions from internal combustion engines are becoming increasingly stringent, and the degree of attention to alternative fuels for internal combustion engines at home and abroad is increasing day by day. Methanol fuel has been confirmed as a type of clean fuel, which does not contain sulfur and only contains very few particles. Its emissions of NOx, SOx and particles are all lower than those of traditional diesel engines, meeting the emission requirements of the International Maritime Organization. Marine methanol diesel engines draw on mature diesel engine technologies and only require minor improvements to the original diesel engines. The technology is relatively mature, the cost is relatively low, and it has received attention from the shipping industry worldwide in recent years.

[0003] Methanol is miscible with water. When methanol is exposed to air, it will absorb water in the air, and methanol containing water is more corrosive. Compared with conventional diesel fuel, methanol fuel has a higher risk coefficient. Once leaked, the possibility of causing a fire in the engine room and casualties to crew members is higher, which will have extremely serious consequences for the ship and the personal safety of the crew. Therefore, it is essential to check the sealing performance of the methanol injection system. Conventional dual-fuel main engines all use nitrogen for routine airtightness inspection. Through experiments, it is found that the airtightness inspection efficiency of nitrogen on methanol engines is not ideal, and it is difficult to quickly find the leakage point. Therefore, there is an urgent need in this field for an airtight structure and an airtight detection method that can quickly realize the airtightness inspection of methanol diesel engines. Summary of the Invention

[0004] The technical problem to be solved by the present invention is the problem that the existing sealing inspection method used for marine methanol diesel engines has low inspection efficiency and cannot quickly find the leakage point.

[0005] To solve the above technical problems, the present invention provides a diesel engine methanol injection system with an airtight detection function and an airtight detection method, using fresh water with a miscibility characteristic with methanol as the airtight inspection medium to achieve a complete airtight inspection of the methanol injection system of a marine methanol dual-fuel low-speed diesel engine.

[0006] To achieve the above technical objectives and reach the above technical effects, the present invention is realized through the following technical solutions:

[0007] In a first aspect, the present invention provides a diesel engine methanol injection system with an airtight detection function, including a methanol injection system. The methanol injection system includes a methanol inlet double-wall pipe, a methanol return double-wall pipe, a methanol boosting unit, and a high-pressure pipeline. An inlet shut-off valve is provided on the methanol inlet double-wall pipe, and a return shut-off valve is provided on the methanol return double-wall pipe. Both the methanol inlet double-wall pipe and the methanol return double-wall pipe are connected to the methanol boosting unit, and a return liquid chain pipe valve is connected between the methanol return double-wall pipe and the methanol boosting unit. A connection valve is provided between the methanol inlet double-wall pipe and the methanol return double-wall pipe. One end of the high-pressure pipeline is detachably connected to the methanol boosting unit, and the other end correspondingly communicates with a plurality of methanol injectors.

[0008] It further includes a fresh water supply system, a plugging tooling, and a methanol pressure detection sensor. The fresh water supply system is connected to the methanol inlet double-wall pipe through the inlet shut-off valve. The plugging tooling is detachably arranged on the methanol boosting unit to plug the connection port between the high-pressure pipeline and the methanol boosting unit. A plurality of methanol pressure detection sensors are provided and are respectively arranged on the methanol inlet double-wall pipe and the methanol return double-wall pipe. The plurality of methanol pressure detection sensors are all connected to an external host control detection system.

[0009] Preferably, the high-pressure pipeline includes at least three methanol high-pressure pipes connected to the methanol boosting unit. The methanol high-pressure pipes are double-wall pipes, and a plurality of double-wall pipe connection ports corresponding to the methanol high-pressure pipes are provided on the methanol boosting unit.

[0010] Furthermore, the plugging tooling includes a sealing column, a sealing cover, and fastening bolts. The sealing column is inserted into the double-wall pipe connection port to achieve plugging. A plurality of fastening bolts are provided and all pass through the sealing cover and are screwed to the outer wall of the methanol boosting unit.

[0011] Even further, the outer wall of one end of the sealing column inserted into the double-wall pipe connection port is provided with a conical surface.

[0012] Preferably, the inlet shut-off valve is arranged at the inlet port of the methanol inlet double-wall pipe, and the return shut-off valve is arranged at the return port of the methanol return double-wall pipe.

[0013] Furthermore, three methanol pressure detection sensors are provided and are respectively arranged in front of the inlet of the methanol boosting unit, behind the inlet shut-off valve, and in front of the return shut-off valve.

[0014] Preferably, the fresh water supply system includes a fresh water supply pump.

[0015] In a second aspect of the present invention, an airtight detection method for a marine methanol low-speed diesel engine is provided. The method is characterized in that the diesel engine methanol injection system with an airtight detection function described above is used for airtight detection, including the following steps:

[0016] Seal the methanol connection in the methanol injection system with 16 bar of seal oil;

[0017] Remove the high-pressure pipeline and plug it with a plugging tooling, and conduct a tightness test on the low-pressure circuit formed by the methanol inlet double-wall pipe, methanol return double-wall pipe and methanol booster unit;

[0018] Connect the high-pressure pipeline to the methanol booster unit and conduct a complete tightness test on the high-pressure pipeline.

[0019] Preferably, when conducting the tightness test on the low-pressure circuit, open the inlet stop valve, return chain pipe valve and the connecting valve to connect the methanol inlet double-wall pipe with the methanol return double-wall pipe, and inject fresh water in an amount sufficient to meet the test water pressure through the fresh water supply system from the inlet stop valve; after the water filling is completed, close the inlet stop valve and the fresh water supply system, and conduct a timed pressure holding test; after pressure holding, conduct airtightness detection by reading the data of multiple methanol pressure detection sensors.

[0020] Further, after the tightness test on the low-pressure circuit, conduct the complete tightness test on the high-pressure pipeline. Open the return stop valve to drain the water in the pipe, and connect the high-pressure pipeline to the methanol booster unit; after the water is drained, close the return stop valve and open the inlet stop valve, inject fresh water in an amount sufficient to meet the test water pressure into the pipe, repeat the airtightness test operation, check for leaks in the high-pressure pipeline and the methanol injector, and conduct airtightness detection of the high-pressure pipeline by reading the data of multiple methanol pressure detection sensors.

[0021] A diesel engine methanol injection system with an airtightness detection function and an airtightness detection method provided by the present invention has the following advantages:

[0022] In the diesel engine methanol injection system with an airtightness detection function and the airtightness detection method of the present invention, fresh water with a mutual solubility characteristic with methanol is used as the tightness inspection medium, and the independent fresh water supply system, stop valve group and pressure sensor are controlled and monitored through the airtightness inspection system. Inject sufficient fresh water into the high- and low-pressure double-wall pipes of the main engine methanol at a certain pressure to achieve a complete tightness inspection of the methanol injection system of the marine methanol dual-fuel low-speed diesel engine. Description of the Drawings

[0023] Figure 1 It is a schematic structural diagram of a diesel engine methanol injection system with an airtightness detection function provided by an embodiment of the present invention;

[0024] Figure 2 It is a schematic structural diagram mainly showing the positional relationship of the methanol pressure detection sensors at the methanol booster unit of the present invention;

[0025] Figure 3This is a schematic structural diagram mainly showing the positional relationship of the methanol pressure detection sensors at the methanol inlet double-wall pipe and the methanol return double-wall pipe of the present invention;

[0026] Figure 4 This is a schematic structural diagram of the plugging tool provided by the embodiment of the present invention.

[0027] In the figure:

[0028] 1 - Methanol inlet double-wall pipe; 2 - Methanol return double-wall pipe; 3 - Methanol boosting unit; 31 - Double-wall pipe connection port; 4 - High-pressure pipeline; 41 - Methanol high-pressure pipe; 5 - Inlet shut-off valve; 6 - Return shut-off valve; 7 - Return chain pipe valve; 8 - Connecting valve; 9 - Methanol injector; 10 - Plugging tool; 101 - Sealing column; 102 - Sealing cover; 103 - Fastening bolt; 11 - Methanol pressure detection sensor. Specific embodiments

[0029] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

[0030] Referring to Figures 1-4 , this application provides a diesel engine methanol injection system with an airtight detection function, including a methanol injection system. The methanol injection system includes a methanol inlet double-wall pipe 1, a methanol return double-wall pipe 2, a methanol boosting unit 3, and a high-pressure pipeline 4. An inlet shut-off valve 5 is installed on the methanol inlet double-wall pipe 1, and a return shut-off valve 6 is installed on the methanol return double-wall pipe 2. Both the methanol inlet double-wall pipe 1 and the methanol return double-wall pipe 2 are connected to the methanol boosting unit 3 to realize the inlet and return of methanol during the operation of the methanol system. A return chain pipe valve 7 is installed and connected between the methanol return double-wall pipe 2 and the methanol boosting unit 3. A connecting valve 8 is installed between the methanol inlet double-wall pipe 1 and the methanol return double-wall pipe 2. One end of the high-pressure pipeline 4 is detachably connected to the methanol boosting unit 3, and the other end correspondingly communicates with a plurality of methanol injectors 9. In this embodiment, the use and installation of each valve body, methanol injector 9, and double-wall pipe are all prior arts and will not be described in detail.

[0031] A diesel engine methanol injection system with an airtight detection function further includes a fresh water supply system (not shown in the figure), a plugging tooling 10, and a methanol pressure detection sensor 11. The fresh water supply system is connected to the methanol inlet double-wall pipe 1 through a liquid inlet stop valve 5. The plugging tooling 10 is detachably installed on the methanol boosting unit 3 to block the connection port between the high-pressure pipeline 4 and the methanol boosting unit 3. A plurality of methanol pressure detection sensors 11 are installed and distributed on the methanol inlet double-wall pipe 1 and the methanol return double-wall pipe 2 respectively to monitor the pressure of each pipeline part of the methanol injection system. A plurality of methanol pressure detection sensors 11 are all connected to an external host control detection system. In this embodiment, the fresh water supply system uses a fresh water supply pump, and the host control detection system includes but is not limited to a conventional PC and a PLC controller, and can achieve connection and display with the methanol pressure detection sensor 11, which are all existing technologies and will not be elaborated too much.

[0032] Further, the liquid inlet stop valve 5 is installed at the liquid inlet port of the methanol inlet double-wall pipe 1, the return liquid stop valve 6 is installed at the return liquid port of the methanol return double-wall pipe 2, and preferably three methanol pressure detection sensors 11 are installed and are respectively arranged in front of the inlet of the methanol boosting unit 3, behind the liquid inlet stop valve 5, and in front of the return liquid stop valve 6.

[0033] Refer to Figure 1 and Figure 4 , the high-pressure pipeline 4 includes at least three methanol high-pressure pipes 41 connected to the methanol boosting unit 3. The methanol high-pressure pipes 41 are double-wall pipes. A plurality of double-wall pipe connection ports 31 corresponding to the methanol high-pressure pipes 41 are integrally formed on the methanol boosting unit 3. In this embodiment, the socket connection between the double-wall pipes is an existing technology and will not be elaborated too much.

[0034] The plugging tooling 10 includes a sealing column 101, a sealing cover 102, and fastening bolts 103. The sealing column 101 and the sealing cover 102 are integrally formed. The sealing column 101 is inserted into the double-wall pipe connection port 31 to achieve plugging. A plurality of fastening bolts 103 are provided and all pass through the sealing cover 102 and are screwed to the outer wall of the methanol boosting unit 3. The sealing column 101 and the sealing cover 102 can be of any shape. In this embodiment, the sealing column 101 is preferably a cylinder, and the outer wall of one end of the sealing column 101 inserted into the double-wall pipe connection port 31 is provided with a conical surface. The sealing cover 102 is preferably a circular cover body coaxially arranged with the sealing column 101, and a plurality of fastening bolts 103 are arranged at equal intervals around the circumference of the sealing cover 102.

[0035] The present invention also provides an airtight detection method for a marine methanol low-speed diesel engine, which uses the above-mentioned diesel engine methanol injection system with an airtight detection function for airtight detection, and includes the following steps:

[0036] Step 1: During the airtight test process, the methanol relationship in the methanol injection system is sealed with 16 bar of sealing oil throughout the process;

[0037] Step 2: Remove the high-pressure pipeline 4, that is, disconnect the connection between the double-wall pipe connection port 31 on the methanol supercharging unit 3 and the methanol high-pressure pipe 41, and then use the plugging tooling 10 to plug the double-wall pipe connection port 31 on the methanol supercharging unit 3, so as to conduct a tightness test on the low-pressure loop formed by the methanol inlet double-wall pipe 1, the methanol return double-wall pipe 2 and the methanol supercharging unit 3. Specifically:

[0038] When conducting the low-pressure loop tightness test, open the inlet stop valve 5, the return chain pipe valve 7 and the connection valve 8 to connect the methanol inlet double-wall pipe 1 and the methanol return double-wall pipe 2, and inject fresh water in an amount sufficient to meet the test water pressure through the fresh water supply system from the inlet stop valve 5 to simulate the methanol inlet environment; after the water filling is completed, close the inlet stop valve 5 and the fresh water supply system, and conduct a timed pressure holding test. In this embodiment, preferably, 13 bar of fresh water is injected into the methanol injection system, and the pressure holding test duration is preferably 10 minutes;

[0039] After holding the pressure for 10 minutes, read the data of multiple methanol pressure detection sensors 11 through the host control detection system. If it is confirmed that the pressure drop of the inlet and return pipe pressure sensors is less than 0.1 bar, it is confirmed that the sealing of the methanol inlet double-wall pipe 1, the methanol return double-wall pipe 2, the inlet stop valve 5, the return chain pipe valve 7 and the connection valve 8 is intact; if the pressure drop is too large, it can be judged that there is a leak in the pipelines inside the methanol inlet double-wall pipe 1 and the methanol return double-wall pipe 2, and the water leakage can be checked through the external pipeline at the bottom of the valve group or the leak detection points on the external pipelines of the methanol inlet double-wall pipe 1 and the methanol return double-wall pipe 2 and repaired; after repair, repeat the above operations until the result of a 0.1 bar pressure drop in 10 minutes meets the pump pressure drop requirement, then the airtightness of the low-pressure pipeline part is completed through the realization of airtightness detection.

[0040] Step 3: Connect the high-pressure pipeline 4 to the methanol supercharging unit 3 and conduct a complete machine tightness test on the high-pressure pipeline 4. Specifically:

[0041] After the low-pressure loop tightness test is completed, conduct a complete machine tightness test on the high-pressure pipeline 4. Open the return stop valve 6 to drain the water in the pipe, and plug and connect all the methanol high-pressure pipes 41 of the high-pressure pipeline 4 to the methanol supercharging unit 3; after the water is drained, close the return stop valve 6 and open the inlet stop valve 5, and inject fresh water into the pipe in an amount sufficient to meet the test water pressure. The amount of fresh water injected is also 13 bar. Repeat the pressure holding and airtightness test operations to further check for leaks in the high-pressure pipeline 4 and the alcohol injector 9. Realize the airtightness detection of the high-pressure pipeline 4 by reading the data of multiple methanol pressure detection sensors 11 until the pump pressure requirement of a 0.1 bar pressure drop in 10 minutes is met, then the airtightness of the high-pressure pipeline 4 is completed.

[0042] The above are only the preferred embodiments of the present invention, and do not impose any formal or substantial limitations on the present invention. It should be noted that for those of ordinary skill in the art of this technology, without departing from the premise of the present invention, several improvements and supplements can still be made, and these improvements and supplements should also be regarded as within the protection scope of the present invention. For those skilled in the art, without departing from the spirit and scope of the present invention, any equivalent changes such as slight modifications, decorations and evolutions made by using the technical content disclosed above are all equivalent embodiments of the present invention; at the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the substantial technology of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A diesel engine methanol injection system with an airtight detection function, characterized in that, It includes a methanol injection system, which comprises a methanol inlet double-wall pipe, a methanol return double-wall pipe, a methanol boosting unit and a high-pressure pipeline. An inlet cut-off valve is provided on the methanol inlet double-wall pipe, and a return cut-off valve is provided on the methanol return double-wall pipe. Both the methanol inlet double-wall pipe and the methanol return double-wall pipe are communicated with the methanol boosting unit, and a return liquid chain pipe valve is communicated between the methanol return double-wall pipe and the methanol boosting unit. A communication valve is arranged between the methanol inlet double-wall pipe and the methanol return double-wall pipe. One end of the high-pressure pipeline is detachably communicated with the methanol boosting unit, and the other end correspondingly communicates with a plurality of methanol injectors; It further includes a fresh water supply system, a plugging tooling and a methanol pressure detection sensor. The fresh water supply system is communicated with the methanol inlet double-wall pipe through the inlet cut-off valve. The plugging tooling is detachably arranged on the methanol boosting unit to plug the communication port between the high-pressure pipeline and the methanol boosting unit. A plurality of methanol pressure detection sensors are provided and are respectively arranged on the methanol inlet double-wall pipe and the methanol return double-wall pipe. A plurality of methanol pressure detection sensors are all connected to an external host control detection system.

2. The diesel engine methanol injection system with an airtight detection function according to claim 1, characterized in that, The high-pressure pipeline includes at least three methanol high-pressure pipes communicated with the methanol boosting unit. The methanol high-pressure pipes are double-wall pipes, and a plurality of double-wall pipe connection ports corresponding to the methanol high-pressure pipes are provided on the methanol boosting unit.

3. The diesel engine methanol injection system with an airtight detection function according to claim 2, characterized in that The plugging tooling includes a sealing column, a sealing cover and fastening bolts. The sealing column is inserted into the double-wall pipe connection port to achieve plugging. A plurality of fastening bolts are provided and all penetrate through the sealing cover and are screwed to the outer wall of the methanol boosting unit.

4. The diesel engine methanol injection system with an airtight detection function according to claim 3, characterized in that, One end of the outer wall of the sealing column inserted into the double-wall pipe connection port is provided with a conical surface.

5. The diesel engine methanol injection system with an airtight detection function according to claim 1, characterized in that The inlet cut-off valve is arranged at the inlet port of the methanol inlet double-wall pipe, and the return cut-off valve is arranged at the return port of the methanol return double-wall pipe.

6. The diesel engine methanol injection system with an airtight detection function as described in claim 5, characterized in that, Three methanol pressure detection sensors are provided and are respectively arranged in front of the inlet of the methanol boosting unit, behind the inlet cut-off valve and in front of the return cut-off valve.

7. The diesel engine methanol injection system with an airtight detection function as described in claim 1, characterized in that, The fresh water supply system includes a fresh water supply pump.

8. A method for airtight detection of a marine low-speed methanol diesel engine, characterized in that, Applying the diesel engine methanol injection system with an airtight detection function according to any one of claims 1-7 for airtight detection includes the following steps: Sealing the methanol in the methanol injection system with 16 bar of sealing oil; Removing the high-pressure pipeline and plugging it with the plugging tooling, and performing a tightness test on the low-pressure circuit formed by the methanol inlet double-wall pipe, the methanol return double-wall pipe and the methanol boosting unit; Connecting the high-pressure pipeline with the methanol boosting unit and performing a whole machine tightness test on the high-pressure pipeline.

9. The airtight detection method of the marine methanol low-speed diesel engine according to claim 8, characterized in that, When performing the tightness test on the low-pressure circuit, opening the inlet cut-off valve, the return liquid chain pipe valve and the communication valve to communicate the methanol inlet double-wall pipe with the methanol return double-wall pipe, and injecting fresh water in an amount sufficient to meet the test water pressure through the fresh water supply system from the inlet cut-off valve; After the water filling is completed, closing the inlet cut-off valve and the fresh water supply system, and performing a timed pressure holding test; after pressure holding, realizing airtightness detection by reading the data of a plurality of the methanol pressure detection sensors.

10. The airtight detection method of the marine methanol low-speed diesel engine according to claim 9, characterized in that, After the low-pressure circuit tightness test is completed, the high-pressure pipeline integrity tightness test is carried out. Open the return liquid stop valve to drain the water in the pipeline, and connect the high-pressure pipeline to the methanol supercharging unit. After the water is drained, close the return liquid stop valve and open the inlet liquid stop valve, inject fresh water into the pipeline in an amount sufficient to meet the test water pressure requirements, repeat the airtight test operation, check for leaks in the high-pressure pipeline and the methanol injector, and realize the airtightness detection of the high-pressure pipeline by reading the data of multiple methanol pressure detection sensors.

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