An internal mixing ammonia-hydrogen dual fuel low pressure coaxial injector and control method

Abstract

The application discloses an inner mixing type ammonia-hydrogen dual-fuel low-pressure coaxial injector and a control method, which comprises a coaxial injection system and an ammonia online cracking hydrogen production system; the ammonia cracking hydrogen production system comprises a liquid ammonia branch and a hydrogen branch; when fuel is started, two gate valves are opened at the same time, two outlets of a liquid ammonia storage tank 1 release liquid ammonia at the same time, the liquid ammonia of the liquid ammonia branch reaches 0.8Mpa-10Mpa after being pressurized by a pump, and then enters a fuel cavity of the dual-fuel coaxial injection system. The liquid ammonia of the liquid ammonia branch is released through opening of the first gate valve 2, the liquid ammonia passes through a vaporizer, a heat exchanger, a decomposition furnace and a separator to obtain high-purity hydrogen, and then enters a mixing cavity after being compressed to a pressure close to that of the liquid ammonia in the liquid ammonia branch by a compressor, at this time, the ECU controls the pressure regulating screw to move upward to drive the needle valve to move upward, so that the liquid ammonia fuel enters the mixing cavity, and the liquid ammonia and the hydrogen are mixed and injected in the mixing cavity. The application can be carried out under low pressure (0.8Mpa-10Mpa), and the problem of poor atomization effect is solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of power and energy engineering, and particularly relates to an ammonia-hydrogen dual-fuel low-pressure coaxial injector and a control method. BACKGROUND

[0002] The fuel injector is a key component in the fuel supply system of an internal combustion engine, which is responsible for injecting fuel into the combustion chamber of the internal combustion engine at a specific pressure, atomization state and time.

[0003] In the field of marine engines, engines mostly use dual fuel for injection, while traditional fuel injectors are mostly single fuel injectors, which cannot inject different types of fuel in the cylinder to form active stratification to reduce the combustion rate and thus increase the load of the engine. Therefore, when using the traditional fuel injector with the dual fuel strategy, multiple fuel injectors must be used, which will inevitably complicate the fuel injection device inside the engine. The dual fuel injection device can overcome the above defects. The current dual fuel injector structure is generally coaxial injection and multi-axis injection, and the multi-axis injection device structure is relatively less researched. The research on dual fuel coaxial injection device is more, which is generally divided into internal mixing type and external mixing type. The internal mixing type generally realizes the mixing of fuel inside the fuel injector and then injects into the cylinder, while the external mixing type first injects two kinds of fuel into the cylinder by the fuel injector, and then mixes in the cylinder. The traditional fuel injection method of the fuel injector is cross flow injection, which is a method of spraying liquid fuel into the gas cross flow in the form of a column. The main purpose of designing an internal mixing dual fluid fuel injector is to convert the liquid column into a liquid film by atomizing air. When encountering cross flow, the liquid film should promote the injection / mist atomization. The dual fuel coaxial injector has a simple structure and is easy to realize, and the matching of ammonia, a clean fuel, is beneficial to reduce carbon emissions in the shipping industry. However, ammonia has a low calorific value, and about 3 times the amount of traditional fuel is needed to achieve the same cruising range as traditional diesel fuel. Secondly, ammonia has a high ignition temperature, is difficult to ignite, and has a slow combustion speed, so other active fuels are needed to ignite. Hydrogen has the characteristics of high energy density and fast combustion speed. Mixing hydrogen and ammonia can complement ammonia-hydrogen fuel and achieve clean and efficient combustion. Hydrogen has high storage and transportation costs and technical barriers, while ammonia, as an ideal hydrogen storage fuel, is relatively easy to store and transport. Therefore, an online ammonia reforming hydrogen process can be used to realize ammonia-hydrogen dual fuel coaxial injection. SUMMARY

[0004] The purpose of the present application is to provide an ammonia-hydrogen dual fuel low-pressure coaxial injector and a control method.

[0005] The purpose of the present application is achieved by the following technical solutions:

[0006] The application discloses an ammonia-hydrogen dual fuel low-pressure coaxial injector, which comprises a coaxial injection system and an ammonia cracking hydrogen production system; the coaxial injection system is arranged on an oil injector of a cylinder head; the ammonia cracking hydrogen production system comprises a liquid ammonia branch and a hydrogen branch; the liquid ammonia branch comprises a No. 2 port of an ammonia storage tank, a No. 2 gate valve, a pressure pump and a liquid ammonia inlet of the dual fuel coaxial injection system which are connected by pipelines; the hydrogen branch comprises a No. 1 port of the ammonia storage tank, a No. 1 gate valve, a vaporizer, a heat exchanger, a decomposition furnace, a separator, a compressor, a flow controller and a hydrogen inlet of the dual fuel coaxial injection system which are connected by pipelines in sequence; liquid ammonia released from the No. 2 outlet of the ammonia storage tank through the opening of the No. 2 gate valve is pressurized by the pressure pump and then enters the dual fuel coaxial injection system through the liquid ammonia branch; liquid ammonia released from the No. 1 outlet of the ammonia storage tank through the opening of the No. 1 gate valve is subjected to the vaporizer, the heat exchanger, the decomposition furnace and the separator to obtain high-purity hydrogen; the separated hydrogen is pressurized by the compressor to be consistent with the pressure of the liquid ammonia in the liquid ammonia branch and then enters the coaxial injection system through the flow controller.

[0007] Further, the dual fuel coaxial injection system comprises a shell, and the inside of the shell comprises, from top to bottom, a pressure regulating screw, a spring seat, a pressure regulating spring, a needle valve and a nozzle hole in sequence; the pressure regulating screw is connected with an ECU control system; the lower part of the spring seat is fixedly connected with the pressure regulating spring, and the other end of the pressure regulating spring is connected with the top end of the needle valve; a gasket is arranged between the shell and the top end of the needle valve.

[0008] Further, the left side of the shell is provided with a liquid ammonia inlet channel and a hydrogen inlet channel; a check valve is arranged on the liquid ammonia inlet channel to prevent ammonia fuel backflow; a one-way valve is arranged on the hydrogen inlet channel to prevent gas backflow.

[0009] Further, the outer wall of the needle valve is provided with a valve sleeve, and a gap is left between the valve sleeve and the shell; a fuel cavity is arranged between the valve sleeve and the shell and used for storing liquid ammonia fuel; a mixing cavity is arranged at the lower part of the fuel cavity and used for mixing ammonia fuel and hydrogen; a single or a plurality of nozzle holes are arranged at the lower part of the mixing cavity.

[0010] Further, the liquid ammonia is pressurized by the pressure pump and then enters the fuel cavity of the dual fuel coaxial injection system through the liquid ammonia branch; the hydrogen enters the mixing cavity of the dual fuel coaxial injection system through the hydrogen branch.

[0011] Further, the outer wall surface of the lower end of the needle valve is tightly combined with the inner wall surface of the shell, when the needle valve is lifted, the fuel in the fuel cavity flows into the mixing cavity through the gap between the wall surfaces, the liquid ammonia is mixed with the hydrogen in the mixing cavity, and then the injection is completed through the nozzle holes arranged on the mixing cavity.

[0012] Further, the pressure applied by the pressure pump to the liquid ammonia is 0.8-10 MPa.

[0013] The application discloses a control method of an internal mixing ammonia-hydrogen dual fuel low-pressure coaxial injector.

[0014] The ammonia-hydrogen dual fuel mixed injection mode is as follows: when starting fuel, the first gate valve and the second gate valve are opened simultaneously, liquid ammonia is released from the second outlet of a liquid ammonia storage tank, the liquid ammonia reaches the pressure of 0.8-10 MPa after being pressurized by a pressurizing pump, and then the liquid ammonia enters the fuel cavity of the dual fuel coaxial injection system through the liquid ammonia branch; the first outlet of the ammonia storage tank releases liquid ammonia by opening the first gate valve, high-purity hydrogen is obtained after the liquid ammonia passes through a vaporizer, a heat exchanger, a decomposition furnace and a separator, the obtained high-purity hydrogen reaches the same pressure as the liquid ammonia in the liquid ammonia branch after being compressed by a compressor; at this time, the ECU control system controls the pressure regulating screw and the spring seat to move upwards, drives the needle valve to move upwards, makes the liquid ammonia fuel in the fuel cavity enter the mixing cavity, and then the hydrogen in the hydrogen branch enters the mixing cavity to realize the mixing of the liquid ammonia and the hydrogen, and then the mixture is injected into the cylinder through the injection hole arranged on the mixing cavity;

[0015] The single ammonia fuel injection mode is as follows: the second gate valve is opened and the first gate valve is closed, liquid ammonia is released from the second outlet of the liquid ammonia storage tank, the released liquid ammonia reaches the required pressure after being pressurized by the pressurizing pump, and then the liquid ammonia enters the fuel cavity of the dual fuel coaxial injection system through the liquid ammonia branch; the ECU control system controls the pressure regulating screw and the spring seat to move upwards, drives the needle valve to move upwards, makes the liquid ammonia fuel in the fuel cavity enter the mixing cavity, and then the liquid ammonia is injected into the cylinder through the injection hole arranged on the mixing cavity.

[0016] The single hydrogen fuel injection mode is as follows: the first gate valve is opened and the second gate valve is closed, liquid ammonia passes through the vaporizer, the heat exchanger, the decomposition furnace and the separator to obtain high-purity hydrogen, the obtained high-purity hydrogen is pressurized to the required pressure by the compressor, and then the high-purity hydrogen enters the mixing cavity through the flow controller, and then the high-purity hydrogen is injected into the cylinder through the injection hole arranged on the mixing cavity.

[0017] The application has the following beneficial effects:

[0018] The dual fuel coaxial injector provided by the application obtains liquid ammonia and hydrogen from single ammonia fuel to realize ammonia-hydrogen mixed injection and single ammonia fuel injection and hydrogen fuel injection. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1Structure diagram of the dual-fuel coaxial injection system.

[0020] Figure 2 Structure diagram of the mixing chamber.

[0021] Figure 3 Structure diagram of the injection hole. DETAILED DESCRIPTION

[0022] The application will be further described below with reference to the accompanying drawings.

[0023] As Figure 1 shown in the figure, a dual-fuel coaxial injector includes an ammonia cracking hydrogen production system and a dual-fuel coaxial injection system. The ammonia cracking hydrogen production system includes a hydrogen branch 7 and a liquid ammonia branch 23; the hydrogen branch 7 is connected by pipes in sequence to an ammonia storage tank 1, a first gate valve 2, a vaporizer 3, a heat exchanger 4, a decomposition furnace 5, a separator 6, a compressor 8, a flow controller 9, and a check valve 10; the liquid ammonia branch is connected by pipes in sequence to a liquid ammonia storage tank 1, a second gate valve 24, a pressure pump 22, and a check valve 21; and the coaxial injection system is arranged in an oil injector on a cylinder head.

[0024] The dual-fuel coaxial injection system is used for injecting liquid ammonia fuel and hydrogen fuel, and can realize both mixed injection and separate injection of liquid ammonia and hydrogen.

[0025] The ammonia storage tank 1 has two outlets, a first outlet connected to the first gate valve 2 for controlling the on-off of the hydrogen branch 7, and a second outlet connected to the second gate valve 24 for controlling the on-off of the liquid ammonia branch 23. The liquid ammonia released from the second outlet of the ammonia storage tank 1 reaches a corresponding pressure (0.8-10 MPa) after passing through the pressure pump 22, and then enters the fuel chamber 13 of the dual-fuel coaxial injection system through the liquid ammonia branch 23. The liquid ammonia released from the first outlet of the ammonia storage tank 1 is released by opening the first gate valve 2, and high-purity hydrogen is obtained after passing through the vaporizer 3, the heat exchanger 4, the decomposition furnace 5, and the separator 6. The separated hydrogen is pressurized to be close to the pressure of the liquid ammonia in the liquid ammonia branch by the compressor 8, and then enters the mixing chamber 12 of the coaxial injection system through the flow controller 9; the liquid ammonia branch 23 is provided with the check valve 21 to prevent backflow of the liquid ammonia; and the hydrogen branch 7 is provided with the check valve 10 to prevent backflow of the gas.

[0026] The dual-fuel coaxial injection system includes a housing 17, which includes from top to bottom in sequence a pressure regulating screw 18, a spring seat 19, a pressure regulating spring 16, a needle valve 15, a fuel chamber 13, a mixing chamber 12, and an injection hole 11; the outer wall of the needle valve 15 is sleeved with a valve sleeve 14; and a gasket 20 is arranged between the housing 17 and the top end of the needle valve 15 to reduce the impact and wear between the needle valve and the housing during back-and-forth movement of the needle valve.

[0027] The pressure regulating screw 18 is connected to the ECU control system. When the fuel is started, the ECU controls the spring seat 19 connected to the pressure regulating screw 18 to move upward together with the pressure regulating spring 16 at the lower end of the spring seat 19, thereby driving the needle valve 15 connected to the pressure regulating spring 16 to move upward. When the needle valve 15 is lifted, the liquid ammonia fuel enters the gap between the needle valve 15 and the valve sleeve 14, and when the needle valve 15 is lifted, the outer wall surface of the needle valve is separated from the inner wall surface of the housing, and the liquid ammonia enters the mixing chamber 12 through the gap between the outer wall surface of the needle valve 15 and the inner wall surface of the housing after the separation, and is injected into the cylinder through the injection hole 11 arranged on the mixing chamber 12. The present application takes four injection holes as an example, as shown in Figure 3 .

[0028] Ammonia-hydrogen dual fuel mixed injection mode: when the fuel is started, the first gate valve 2 and the second gate valve 24 are opened at the same time, and the corresponding liquid ammonia is released from the second outlet of the liquid ammonia storage tank 1. After the released liquid ammonia reaches the corresponding pressure (0.8-10 MPa) through the pressure pump 22, it enters the fuel chamber 13 of the dual fuel coaxial injection system through the liquid ammonia branch 23. The first outlet of the ammonia storage tank 1 releases liquid ammonia by opening the first gate valve 2, and high-purity hydrogen is obtained after the liquid ammonia passes through the vaporizer 3, the heat exchanger 4, the decomposition furnace 5, and the separator 6. The obtained high-purity hydrogen is compressed to a pressure close to that of the liquid ammonia in the liquid ammonia branch 7 through the compressor 8, and then enters the mixing chamber 12 of the dual fuel coaxial injection system. At this time, the ECU controls the pressure regulating screw 18 to move upward, driving the needle valve 15 to move upward, so that the liquid ammonia fuel enters the mixing chamber 12, and the compressed hydrogen enters the mixing chamber 12 to realize the mixing of liquid ammonia and hydrogen, and then is injected into the cylinder through the injection hole 11 arranged on the mixing chamber 12.

[0029] Single ammonia fuel injection mode: open the second gate valve 24 and close the first gate valve 2, and the corresponding liquid ammonia is released from the second outlet of the liquid ammonia storage tank 1. After the released liquid ammonia reaches the corresponding pressure requirement through the pressure pump 22, it enters the fuel chamber 13 of the dual fuel coaxial injection system through the liquid ammonia branch 23. The ECU controls the pressure regulating screw 18 to drive the needle valve 15 to move upward, and the liquid ammonia in the fuel chamber 13 enters the mixing chamber 12, and is injected into the cylinder through the injection hole 11 arranged on the mixing chamber 12.

[0030] Single hydrogen fuel injection mode: open the first gate valve 2 and close the second gate valve 24, and the liquid ammonia passes through the vaporizer 3, the heat exchanger 4, the decomposition furnace 5, and the separator 6 to obtain high-purity hydrogen. After the separated hydrogen is pressurized to the required pressure through the compressor 8, it enters the mixing chamber 12 of the dual fuel coaxial injection system through the flow controller 9, and then is injected into the cylinder through the injection hole 11 arranged on the mixing chamber 12.

[0031] The above merely provides the preferred embodiments of the present application, and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the principles and technical scope of the present application shall fall into the scope of the present application.

Claims

1. A control method of an internal mixing ammonia-hydrogen dual fuel low pressure coaxial injection system, characterized in that: The application is applied to an internal mixing ammonia-hydrogen dual fuel low pressure coaxial injection system, which comprises a coaxial injection system and an ammonia cracking hydrogen production system; the coaxial injection system is arranged on an oil injector of a cylinder head; the ammonia cracking hydrogen production system comprises a liquid ammonia branch (23) and a hydrogen branch (7); the liquid ammonia branch (23) comprises a No. 2 port of an ammonia storage tank (1), a No. 2 gate valve (24), a pressure pump (22) and a liquid ammonia inlet of the dual fuel coaxial injection system which are connected by pipelines; the hydrogen branch (7) comprises a No. 1 port of the ammonia storage tank (1), a No. 1 gate valve (2), a vaporizer (3), a heat exchanger (4), a decomposition furnace (5), a separator (6), a compressor (8), a flow controller (9) and a hydrogen inlet of the dual fuel coaxial injection system which are connected by pipelines in sequence; liquid ammonia released from the No. 2 outlet of the ammonia storage tank (1) through the opening of the No. 2 gate valve (24) is pressurized by the pressure pump (22) and then enters the dual fuel coaxial injection system through the liquid ammonia branch (23); liquid ammonia released from the No. 1 outlet of the ammonia storage tank (1) through the opening of the No. 1 gate valve (2) is vaporized by the vaporizer (3), the heat exchanger (4), the decomposition furnace (5) and the separator (6) to obtain high-purity hydrogen, and the separated hydrogen is pressurized by the compressor (8) to the same pressure as that of the liquid ammonia in the liquid ammonia branch (23) and then enters the coaxial injection system through the flow controller (9); The coaxial injection system comprises a shell (17), and the inside of the shell (17) comprises, from top to bottom, a pressure regulating screw (18), a spring seat (19), a pressure regulating spring (16), a needle valve (15) and a spray hole (11) in sequence; the pressure regulating screw (18) is connected with an ECU control system; the lower part of the spring seat (19) is fixedly connected with the pressure regulating spring (16), and the other end of the pressure regulating spring (16) is connected with the top end of the needle valve (15); a gasket (20) is arranged between the shell (17) and the top end of the needle valve (15); the outer wall of the needle valve (15) is provided with a valve sleeve (14), and a gap is left between them; a fuel cavity (13) is arranged between the valve sleeve (14) and the shell (17) and used for storing liquid ammonia fuel; a mixing cavity (12) is arranged at the lower part of the fuel cavity (13) and used for mixing the ammonia fuel and hydrogen; a single or a plurality of spray holes (11) are arranged at the lower part of the mixing cavity (12); the liquid ammonia enters the fuel cavity (13) of the dual fuel coaxial injection system through the liquid ammonia branch (23) after being pressurized by the pressure pump (22); and the hydrogen enters the mixing cavity (12) of the dual fuel coaxial injection system through the hydrogen branch (7); The control method comprises an ammonia-hydrogen dual fuel mixed injection mode, a single ammonia fuel injection mode and a single hydrogen fuel injection mode, and the three injection modes The ammonia-hydrogen dual fuel injection mode is as follows: when the engine is started, the first gate valve (2) and the second gate valve (24) are opened at the same time, liquid ammonia is released from the second outlet of the ammonia storage tank (1), the liquid ammonia reaches the pressure of 0.8-10 MPa after being pressurized by the pressurizing pump (22), and then enters the fuel cavity (13) of the dual fuel coaxial injection system through the liquid ammonia branch (23); the liquid ammonia is released from the first outlet of the ammonia storage tank (1) by opening the first gate valve (2), high-purity hydrogen is obtained after the liquid ammonia passes through the vaporizer (3), the heat exchanger (4), the decomposition furnace (5) and the separator (6), the obtained high-purity hydrogen is compressed to the same pressure as the liquid ammonia in the liquid ammonia branch (23) by the compressor (8); at this time, the ECU control system controls the pressure regulating screw (18) and the spring seat (19) to move upward, drives the needle valve (15) to move upward, makes the liquid ammonia fuel in the fuel cavity (13) enter the mixing cavity (12), and the hydrogen in the hydrogen branch (7) enters the mixing cavity (12) to realize the mixing of the liquid ammonia and the hydrogen, and then is injected into the cylinder through the injection hole (11) arranged on the mixing cavity (12); The single ammonia fuel injection mode is as follows: the second gate valve (24) is opened and the first gate valve (2) is closed, liquid ammonia is released from the second outlet of the ammonia storage tank (1), the released liquid ammonia reaches the required pressure after being pressurized by the pressurizing pump (22), and then enters the fuel cavity (13) of the dual fuel coaxial injection system through the liquid ammonia branch (23); the ECU control system controls the pressure regulating screw (18) and the spring seat (19) to move upward, drives the needle valve (15) to move upward, makes the liquid ammonia fuel in the fuel cavity (13) enter the mixing cavity (12), and is injected into the cylinder through the injection hole (11) arranged on the mixing cavity (12). The single hydrogen fuel injection mode is as follows: the first gate valve (2) is opened and the second gate valve (24) is closed, high-purity hydrogen is obtained after the liquid ammonia passes through the vaporizer (3), the heat exchanger (4), the decomposition furnace (5) and the separator (6), the obtained high-purity hydrogen is pressurized to the required pressure by the compressor (8), and then enters the mixing cavity (12) through the flow controller (9), and is injected into the cylinder through the injection hole (11) arranged on the mixing cavity (12).

2. The control method of the inner-mixing ammonia-hydrogen dual-fuel low-pressure coaxial injection system according to claim 1, characterized in that: The left side of the shell (17) is provided with a liquid ammonia inlet channel and a hydrogen inlet channel; the liquid ammonia inlet channel is provided with a check valve (21) to prevent ammonia fuel backflow; the hydrogen inlet channel is provided with a one-way valve (10) to prevent gas backflow.

3. The control method of an inner-mixing ammonia-hydrogen dual fuel low-pressure coaxial injection system according to claim 1, characterized in that: The outer wall surface of the lower end of the needle valve (15) is closely combined with the inner wall surface of the shell (17), when the needle valve (15) is lifted, the fuel in the fuel cavity (13) flows into the mixing cavity (12) through the gap between the wall surfaces, the mixing of the liquid ammonia and the hydrogen is realized in the mixing cavity (12), and then the injection is completed through the injection hole (11) arranged on the mixing cavity (12).

4. The control method of an inner-mixing ammonia-hydrogen dual fuel low-pressure coaxial injection system according to claim 1, characterized in that: The pressure applied to the liquid ammonia by the pressurizing pump (22) is 0.8-10 MPa.

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