A multiple injection system integrating methanol and its cracking gas

Abstract

The present application belongs to the technical field of alcohol hydrogen engine, and discloses a multiple injection system integrating methanol and its cracking gas, which comprises a methanol engine assembly, a methanol fuel tank, a methanol cracker, a methanol high-pressure pipeline, a methanol low-pressure pipeline and a methanol cracking gas pipeline; the methanol engine assembly comprises an alcohol hydrogen injector; one end of the methanol high-pressure pipeline is connected with a first outlet of the methanol fuel tank, and the other end is connected with an inlet one of the alcohol hydrogen injector; one end of the methanol low-pressure pipeline is connected with a second outlet of the methanol fuel tank, and the other end is connected with an inlet of the methanol cracker; one end of the methanol cracking gas pipeline is connected with an outlet of the methanol cracker, and the other end is connected with an inlet two of the alcohol hydrogen injector. The present application realizes accurate control of the cracking gas amount entering the cylinder, adjusts the injection amount according to the change of the in-cylinder mixture parameters, realizes simultaneous or independent injection of methanol and its cracking gas through the alcohol hydrogen injector, and can adopt different fuel control modes for different working conditions.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field related to alcohol hydrogen engine, and relates to a multiple injection system integrating methanol and its cracking gas, more particularly, to a multiple fuel injection system for realizing simultaneous or independent injection of methanol and its cracking gas by using a gas-liquid two-phase dual-fluid injector, and providing fuel organization modes under different loads. BACKGROUND

[0002] Under the global trend of carbon reduction, methanol as a potential engine alternative fuel has attracted widespread attention. Since methanol contains 50% oxygen, it helps to fully burn the fuel and improve the thermal efficiency of the engine. Methanol is also a hydrogen energy carrier, which can be used to produce hydrogen gas by using engine waste heat, thereby solving the problem of hydrogen storage. In addition, the price of methanol is lower than that of fuel oil, so it has good fuel economy.

[0003] Alcohol hydrogen engine refers to the cracking of methanol into hydrogen-rich methanol cracking gas under the action of a catalyst using engine exhaust waste heat, and then burning in the combustion chamber. This technology recovers part of the exhaust waste heat, and hydrogen can accelerate combustion and improve the constant volume degree of combustion, thereby improving the thermal efficiency of the engine. Therefore, alcohol hydrogen engine provides an effective technical path and solution for reducing carbon emissions and addressing climate change.

[0004] In the prior art, there are mainly two fuel supply modes for alcohol hydrogen engine: one is methanol direct injection in the cylinder, and the cracking gas is injected through the intake port; the other is that methanol and methanol cracking gas are injected into the cylinder through two independent nozzles in the intake port. The above-mentioned modes both need two nozzles, and the double-nozzle injection system increases the complexity of the engine structure, increases the manufacturing cost and the difficulty of maintenance and repair, and in addition, there are problems of wear resistance and corrosion resistance of the nozzle, and the cracking gas amount entering the cylinder cannot be accurately controlled. Therefore, it is urgent to propose a multiple injection system integrating methanol and its cracking gas, which simultaneously or independently injects methanol and cracking gas into the cylinder by the in-cylinder direct injection method, simplifies the installation structure, and realizes accurate control of the cracking gas amount entering the cylinder. SUMMARY

[0005] In view of the above defects or improvement needs of the prior art, the present application provides a multiple injection system integrating methanol and its cracking gas, which aims to simplify the structure of the fuel supply system, optimize the arrangement space, realize accurate control of the cracking gas amount entering the cylinder, and adjust the injection amount according to the change of the in-cylinder mixture parameters, thereby solving the technical problems of complex double-nozzle injection system structure and the need for accurate control of the cracking gas amount.

[0006] To achieve the above object, according to one aspect of the present application, a multiple injection system integrating methanol and its cracking gas is provided, comprising: a methanol engine assembly, a methanol fuel tank 4, a methanol cracker 12, a methanol high-pressure pipeline, a methanol low-pressure pipeline, a methanol cracking gas pipeline; the methanol engine assembly comprises an alcohol hydrogen injector 2; one end of the methanol high-pressure pipeline is connected to a first outlet of the methanol fuel tank 4, and the other end is connected to an inlet one of the alcohol hydrogen injector 2; one end of the methanol low-pressure pipeline is connected to a second outlet of the methanol fuel tank 4, and the other end is connected to an inlet of the methanol cracker 12; one end of the methanol cracking gas pipeline is connected to an outlet of the methanol cracker 12, and the other end is connected to an inlet two of the alcohol hydrogen injector 2.

[0007] Preferably, a methanol high-pressure pump 5, a methanol flowmeter one 6, a methanol supply amount control valve 7 and a methanol high-pressure common rail 8 are sequentially arranged on the methanol high-pressure pipeline along the gas flow direction; the methanol high-pressure pipeline is used to provide methanol to the alcohol hydrogen injector 2.

[0008] Preferably, a methanol low-pressure pump 9, a methanol cracking amount control valve 10 and a methanol flowmeter two 11 are sequentially arranged on the methanol low-pressure pipeline along the gas flow direction; the methanol low-pressure pipeline is used to supply the methanol required for cracking to the methanol cracker 12.

[0009] Preferably, a booster pump 13, a pressure stabilizer 14, a cracking gas flowmeter 15, a cracking gas flow control valve 16 and a cracking gas high-pressure common rail 17 are sequentially arranged on the methanol cracking gas pipeline along the gas flow direction; the methanol cracking gas pipeline is used to provide methanol cracking gas to the alcohol hydrogen injector 2.

[0010] Preferably, the methanol engine assembly further comprises an intake port 1, a combustion chamber, a cylinder head, a spark plug 3, an exhaust port 19, the alcohol hydrogen injector 2 and the spark plug 3 are installed on the cylinder head, the alcohol hydrogen injector 2 is used to simultaneously or separately inject methanol and methanol cracking gas multiple times, and the spark plug 3 is used to ignite the cracking gas or the methanol or the mixture of methanol and its cracking gas.

[0011] Preferably, the alcohol hydrogen injector 2 is provided with a methanol channel 22, a cracking gas channel 21, a cracking gas injection hole 23 and a methanol injection hole 24; the cracking gas channel 21 is located outside the methanol channel 22 and is independent of each other; the methanol injection hole 24 is located below the cracking gas injection hole 23.

[0012] Preferably, the high-temperature exhaust gas of the methanol engine assembly enters the methanol cracker 12 through the exhaust port 19, and after fully exchanging heat with the methanol, the high-temperature exhaust gas enters the exhaust port 19 again; the methanol cracker 12 is provided with a cracker safety valve 18.

[0013] Preferably, the methanol high-pressure pump 5 pumps methanol into the methanol high-pressure common rail 8, the methanol flowmeter one 6 is used to detect the real-time flow of methanol, and the methanol supply amount control valve 7 adjusts the flow of methanol into the methanol high-pressure common rail 8 according to the current load of the engine, so as to change the rail pressure of the methanol high-pressure common rail 8.

[0014] Preferably, the methanol low-pressure pump 9 pumps methanol into the methanol cracker 12, the methanol cracking amount control valve 10 is used to control the amount of methanol entering the methanol cracker 12, and the methanol flowmeter two 11 is used to detect the amount of methanol entering the methanol cracker 12.

[0015] Preferably, the booster pump 13 is used to increase the pressure of the methanol cracking gas at the outlet of the methanol cracker 12, so as to increase the pressure in the pressure stabilizer 14; the pressure stabilizer 14 is used to stabilize the pressure of the methanol cracking gas and has the function of storing a part of the methanol cracking gas; the cracking gas flowmeter 15 is used to detect the flow of the methanol cracking gas, and the cracking gas flow control valve 16 adjusts the flow of the methanol cracking gas into the cracking gas high-pressure common rail 17 according to the current load of the engine, and controls the injection amount of the methanol cracking gas through the alcohol-hydrogen injector 2.

[0016] Overall, compared with the prior art, the above technical scheme conceived by the present application provides a multiple injection system integrating methanol and its cracking gas, which mainly has the following beneficial effects:

[0017] 1. Compared with intake port injection of methanol cracking gas, the present application realizes precise control of the amount of cracking gas entering the cylinder and adjusts the injection amount according to the change of the in-cylinder mixture parameters. By utilizing the characteristics of the alcohol-hydrogen injector, simultaneous injection of methanol cracking gas and methanol helps to atomize the methanol, forming a uniform methanol-cracking gas-air mixture, and different fuel organization methods can be adopted for different working conditions. Since the alcohol-hydrogen injector is installed on the cylinder head and directly injected into the combustion chamber, the amount of cracking gas entering the combustion chamber can be accurately controlled, the demand amount of cracking gas under different working conditions can be more accurately matched, the engine running stability is improved, and the influence of gaseous fuel on the charge coefficient is avoided.

[0018] 2. The present application simplifies the structure of the fuel supply system and optimizes the layout space; simultaneous or independent injection of methanol and its cracking gas is realized through a single alcohol-hydrogen injector, which saves the installation area on the cylinder head, simplifies the installation structure and difficulty, and improves the reliability.

[0019] 3. The pressure stabilizer of the present application has the function of storing cracking gas. Since the cracking gas contains a part of hydrogen, it is easier to ignite than methanol. During cold start of the engine, only methanol cracking gas is injected to realize cold start of the engine, without the need for additional heating devices.

[0020] 4. The application provides a multiple injection system integrating methanol and its cracking gas, which is suitable for fuel organization and combustion control under medium and low load and high load conditions. Under medium and low load, as much cracking gas as possible is mixed and burned, and premixed-diffusion combustion of methanol is realized through multiple injection, so that the combustion efficiency can be improved; under high load, the amount of cracking gas mixed and burned is reduced, and multiple injection is combined to effectively reduce the risk of knocking and ensure stable operation of the engine. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a structural schematic diagram of a multiple injection system integrating methanol and its cracking gas according to the application;

[0022] Figure 2 is a structural schematic diagram of an alcohol hydrogen injector.

[0023] In all the drawings, the same reference signs are used to represent the same elements or structures, in which: the engine intake passage 1, the alcohol hydrogen injector 2, the cracking gas passage 21, the methanol passage 22, the cracking gas injection hole 23, the methanol injection hole 24, the spark plug 3, the methanol fuel tank 4, the methanol high-pressure pump 5, the methanol flowmeter 6, the methanol flow control valve 7, the methanol high-pressure common rail 8, the methanol low-pressure pump 9, the methanol cracking amount control valve 10, the methanol flowmeter 11, the methanol cracker 12, the booster pump 13, the pressure stabilizer 14, the cracking gas flowmeter 15, the cracking gas flow control valve 16, the cracking gas high-pressure common rail 17, the cracker safety valve 18, and the exhaust passage 19. DETAILED DESCRIPTION

[0024] In order to make the objectives, technical solutions and advantages of the application clearer, the application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the application and do not limit the application. In addition, the technical features involved in each embodiment of the application described below can be combined with each other as long as they do not conflict with each other.

[0025] Please refer to Figure 1 The application provides a multiple injection system integrating methanol and its cracking gas, which comprises: a methanol engine assembly, a methanol fuel tank 4, a methanol cracker 12, a methanol high-pressure pipeline, a methanol low-pressure pipeline, and a methanol cracking gas pipeline; the methanol engine assembly comprises an alcohol hydrogen injector 2; one end of the methanol high-pressure pipeline is connected to a first outlet of the methanol fuel tank 4, and the other end is connected to an inlet one of the alcohol hydrogen injector 2; one end of the methanol low-pressure pipeline is connected to a second outlet of the methanol fuel tank 4, and the other end is connected to an inlet of the methanol cracker 12; one end of the methanol cracking gas pipeline is connected to an outlet of the methanol cracker 12, and the other end is connected to an inlet two of the alcohol hydrogen injector 2.

[0026] The methanol engine assembly further comprises an intake port 1, a combustion chamber, a cylinder head, a spark plug 3, an exhaust port 19, an alcohol hydrogen injector 2 and a spark plug 3, the alcohol hydrogen injector 2 and the spark plug 3 are installed on the cylinder head, the alcohol hydrogen injector 2 is used for simultaneously or respectively multiple times injecting methanol and methanol cracking gas, and the spark plug 3 is used for igniting the cracking gas or the methanol or a mixture of the methanol and the cracking gas.

[0027] A methanol high-pressure pump 5, a methanol flowmeter 6, a methanol supply amount control valve 7 and a methanol high-pressure common rail 8 are sequentially arranged on the methanol high-pressure pipeline in the direction of the gas flow; the methanol high-pressure pipeline is used for providing the alcohol hydrogen injector 2 with methanol. The methanol high-pressure pump 5 pumps the methanol into the methanol high-pressure common rail 8, the methanol flowmeter 6 is used for detecting the real-time flow of the methanol, and the methanol supply amount control valve 7 adjusts the methanol flow into the methanol high-pressure common rail 8 according to the current load of the engine, so as to change the rail pressure of the methanol high-pressure common rail 8, and further dynamically adjust the injection pressure of the methanol.

[0028] A methanol low-pressure pump 9, a methanol cracking amount control valve 10 and a methanol flowmeter 11 are sequentially arranged on the methanol low-pressure pipeline in the direction of the gas flow; the methanol low-pressure pipeline is used for supplying the methanol cracking device 12 with the methanol required for cracking. The methanol low-pressure pump 9 pumps the methanol into the methanol cracking device 12, the methanol cracking amount control valve 10 is used for controlling the amount of the methanol entering the methanol cracking device 12, and the methanol flowmeter 11 is used for detecting the amount of the methanol entering the methanol cracking device 12. A control unit is arranged in the engine assembly, and the methanol cracking amount control valve 10 is controlled according to the cracking amount required by different working conditions and the current cracking amount.

[0029] A booster pump 13, a pressure stabilizer 14, a cracking gas flow meter 15, a cracking gas flow control valve 16 and a cracking gas high-pressure common rail 17 are sequentially arranged along the gas flow direction on the methanol cracking gas pipeline. The methanol cracking gas pipeline is used to provide methanol cracking gas for the alcohol-hydrogen injector 2. The booster pump 13 is used to increase the pressure of the methanol cracking gas at the outlet of the methanol cracker 12, thereby increasing the pressure in the pressure stabilizer 14. The pressure stabilizer 14 is used to stabilize the pressure of the methanol cracking gas and has the function of storing a part of the methanol cracking gas. The cracking gas flow meter 15 is used to detect the cracking gas flow, and the cracking gas flow control valve 16 adjusts the methanol cracking gas flow into the cracking gas high-pressure common rail 17 according to the current load of the engine, and controls the injection amount of the methanol cracking gas through the alcohol-hydrogen injector 2. Specifically, the methanol cracking gas generated by the methanol cracker 12 is pressurized by the booster pump 13 to the rail pressure of the cracking gas high-pressure common rail 17, and then enters the pressure stabilizer 14 to stabilize the pressure of the cracking gas. The rail pressure of the cracking gas high-pressure common rail 17 can be set to about 5 MPa. The pressurized methanol cracking gas adjusts the appropriate injection amount through the alcohol-hydrogen injector 2 according to the working condition of the engine. The pressure stabilizer 14 also has the function of storing methanol cracking gas: when the engine is stopped, a part of the methanol cracking gas will still be generated due to the high exhaust temperature. At this time, the booster pump 13 still maintains the working state and stores a part of the methanol cracking gas in the pressure stabilizer 14 for the cold start of the engine.

[0030] The alcohol-hydrogen injector 2 is provided with a methanol channel 22, a cracking gas channel 21, a cracking gas injection hole 23 and a methanol injection hole 24. The cracking gas channel 21 is located outside the methanol channel 22 and is independent of each other. The methanol injection hole 24 is located below the cracking gas injection hole 23, which uses high-speed gas injection to guide the methanol spray to move towards the piston, preventing the methanol spray from moving towards the cylinder head and adhering to the cylinder head, causing incomplete combustion. The high-temperature exhaust gas of the methanol engine assembly enters the methanol cracker 12 through the exhaust passage 19, fully exchanges heat with the methanol, and then enters the exhaust passage 19 again. The methanol cracker 12 is provided with a cracker safety valve 18. When the pressure of the methanol cracker 12 is higher than the safety value, the cracker safety valve 18 is opened to maintain the pressure within a safe range.

[0031] In this embodiment, the multiple injection system provided by the present application integrates methanol and its cracking gas, and the working process of the system facing different engine working conditions is as follows:

[0032] During the cold start of the engine, the methanol is not easy to be ignited after being injected into the cylinder due to the large methanol vaporization latent heat. Therefore, during the cold start of the engine, the alcohol-hydrogen injector 2 injects methanol cracking gas into the cylinder after the intake passage 1 is completely closed, to ensure the sufficient mixing of the methanol cracking gas and air. The spark plug 3 ignites near the top dead center to ignite the cracking gas-air premixed gas and realize premixed combustion. The ignition advance angle can be set to 20-30°CA, which is determined according to the model of the engine.

[0033] When the engine is under medium or low load, the engine determines the blending ratio of the pyrolysis gas according to the specific load. Specifically, in order to improve the economy of the engine, as much pyrolysis gas as possible can be blended under the premise of ensuring stability. The methanol and the methanol pyrolysis gas are injected simultaneously, and since the pyrolysis gas injection hole 23 is located above the methanol injection hole 24, when the two are injected simultaneously, the methanol pyrolysis gas helps to further atomize the methanol, forming a uniform methanol-pyrolysis gas-air premixed gas, achieving rapid combustion. The spark plug 3 ignites when the piston moves close to the top dead center. Specifically, compared to cold start, the ignition advance angle should be reduced. In order to prevent the pressure rise rate of the mixture after ignition from being too large, a small amount of methanol is injected again after ignition, achieving diffusion combustion of the methanol. The second injected methanol also has a large latent heat of vaporization, which can reduce the combustion temperature and reduce NOx emissions. Since premixed combustion has a faster flame propagation speed and the engine has a lower tendency to knock under medium or low load, the proportion of methanol premixed combustion can be increased. Specifically, the ratio of the amount of methanol injected during premixing to the amount of methanol injected the second time can be more at the beginning and less at the end.

[0034] When the engine is under high load, the combustion is more intense, and the methanol pyrolysis gas contains more hydrogen, which can increase the tendency of the engine to knock, so the blending ratio should be reduced accordingly, and the premixed combustion ratio should also be reduced. Specifically, in order to ensure sufficient premixing time, the pyrolysis gas injection advance angle is increased and the ignition advance angle is reduced to avoid excessive pressure gradient in the combustion chamber. Although the preferred embodiment of the present application is described by way of example with double injection, those skilled in the art will understand that by appropriately adjusting the number of injections (such as three or more times), similar technical effects can be achieved. For example, further injecting an appropriate amount of methanol during the late combustion period can effectively improve the combustion characteristics during the afterburning period.

[0035] Those skilled in the art will readily understand that the above description is only a preferred embodiment of the present application and is not intended to limit the present application, and any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A multi-injection system integrating methanol and its cracked gas, characterized in that: The application relates to a methanol engine assembly. The methanol engine assembly comprises an alcohol hydrogen injector (2), a first outlet of a methanol fuel tank (4) is connected to one end of a methanol high-pressure pipeline, the other end of the methanol high-pressure pipeline is connected to an inlet one of the alcohol hydrogen injector (2), a second outlet of the methanol fuel tank (4) is connected to one end of a methanol low-pressure pipeline, the other end of the methanol low-pressure pipeline is connected to an inlet of a methanol cracker (12), one end of a methanol cracking gas pipeline is connected to an outlet of the methanol cracker (12), and the other end of the methanol cracking gas pipeline is connected to an inlet two of the alcohol hydrogen injector (2). The alcohol hydrogen injector (2) is internally provided with a methanol channel (22), a cracking gas channel (21), a cracking gas injection hole (23) and a methanol injection hole (24); the cracking gas channel (21) is located outside the methanol channel (22) and is independent of each other; the methanol injection hole (24) is located below the cracking gas injection hole (23). A methanol high-pressure pump (5), a methanol flowmeter one (6), a methanol supply amount control valve (7) and a methanol high-pressure common rail (8) are sequentially arranged on the methanol high-pressure pipeline along the gas flow direction; the methanol high-pressure pipeline is used for providing methanol to the alcohol hydrogen injector (2).

2. The integrated methanol and its cracking gas multiple injection system of claim 1, wherein: A methanol low-pressure pump (9), a methanol cracking amount control valve (10) and a methanol flowmeter two (11) are sequentially arranged on the methanol low-pressure pipeline along the gas flow direction; the methanol low-pressure pipeline is used for supplying the methanol required for cracking to the methanol cracker (12).

3. The integrated methanol and its cracked gas multiple injection system according to claim 1, wherein: A booster pump (13), a pressure stabilizer (14), a cracking gas flowmeter (15), a cracking gas flow control valve (16) and a cracking gas high-pressure common rail (17) are sequentially arranged on the methanol cracking gas pipeline along the gas flow direction; the methanol cracking gas pipeline is used for providing methanol cracking gas to the alcohol hydrogen injector (2).

4. The integrated methanol and its cracked gas multiple injection system of claim 1, wherein: The methanol engine assembly further comprises an air inlet (1), a combustion chamber, a cylinder head, a spark plug (3) and an air outlet (19); the alcohol hydrogen injector (2) and the spark plug (3) are installed on the cylinder head; the alcohol hydrogen injector (2) is used for simultaneously or respectively spraying the methanol and the methanol cracking gas for multiple times; the spark plug (3) is used for igniting the cracking gas or the methanol or a mixture of the methanol and the cracking gas thereof.

5. The integrated methanol and its cracked gas multiple injection system according to claim 1, wherein: High-temperature exhaust gas of the methanol engine assembly enters the methanol cracker (12) through the air outlet (19), exchanges heat with the methanol and then enters the air outlet (19) again; a cracker safety valve (18) is installed on the methanol cracker (12).

6. The integrated methanol and its cracked gas multiple injection system according to claim 5, wherein: The methanol high-pressure pump (5) pumps the methanol into the methanol high-pressure common rail (8); the methanol flowmeter one (6) is used for detecting the real-time flow of the methanol; the methanol supply amount control valve (7) adjusts the methanol flow entering the methanol high-pressure common rail (8) according to the current load of the engine, so as to change the rail pressure of the methanol high-pressure common rail (8).

7. The integrated methanol and its cracked gas multiple injection system according to claim 2, wherein: The methanol low-pressure pump (9) pumps the methanol into the methanol cracker (12); the methanol cracking amount control valve (10) is used for controlling the amount of the methanol entering the methanol cracker (12); the methanol flowmeter two (11) is used for detecting the amount of the methanol entering the methanol cracker (12).

8. The integrated methanol and its cracked gas multiple injection system according to claim 3, wherein: ​ 9. The integrated methanol and its cracked gas multiple injection system of claim 4, wherein: The booster pump (13) is used to increase the pressure of the methanol cracking gas at the outlet of the methanol cracker (12), so as to increase the pressure in the pressure stabilizer (14); the pressure stabilizer (14) is used to stabilize the methanol cracking gas pressure and has the function of storing a part of the methanol cracking gas; the cracking gas flow meter (15) is used to detect the methanol cracking gas flow, and the cracking gas flow control valve (16) adjusts the methanol cracking gas flow entering the cracking gas high-pressure common rail (17) according to the current load of the engine, and controls the injection amount of the methanol cracking gas through the alcohol-hydrogen injector (2).

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