An ammonia roll system and control method
By employing an ammonia entrainment system in a natural gas-diesel dual-fuel engine, the problem of difficult ammonia fuel ignition is solved by utilizing a small proportion of diesel fuel to ignite natural gas and taking advantage of the entrainment effect of ammonia fuel, thus achieving stable combustion and low emissions.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- YANTAI UNIV
- Filing Date
- 2022-12-01
- Publication Date
- 2026-07-21
AI Technical Summary
Existing natural gas-diesel dual-fuel engines face difficulties in ignition when using ammonia fuel. The slow flame propagation of ammonia fuel necessitates a large amount of diesel fuel for ignition, resulting in reduced engine emission reduction efficiency.
The system employs an ammonia entrainment system, which uses a dual-fuel injector for ammonia and natural gas and an ignition diesel injector in the combustion chamber. A small proportion of diesel fuel is used to ignite the natural gas, and the heat released from the natural gas is used to ignite the ammonia fuel. The jet of ammonia fuel entrains the natural gas flame, forming layers of different flow velocities to promote combustion, block the collision between methane and the wall, and reduce unburned methane emissions.
It achieves stable ignition and co-combustion of ammonia fuel, reduces unburned methane emissions, lowers carbon dioxide emissions, and improves the engine's emission reduction performance.
Smart Images
Figure CN115750081B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of in-cylinder combustion technology for dual-fuel engines, specifically to an ammonia entrainment system and control method. Background Technology
[0002] A search revealed an LNG / diesel dual-fuel engine control system in publication number CN105697161B, which includes an electronic control unit and, in sequence connected to the electronic control unit, a speed sensor, a throttle position sensor, a water temperature sensor, an exhaust temperature sensor, an oxygen sensor, a natural gas supply system, and a diesel supply system. Compared with the prior art, this invention uses a combination of open-loop and closed-loop methods to achieve operation control of the LNG / diesel dual-fuel engine, realizing real-time control and adjustment of the pilot fuel quantity, natural gas injection time, and injection quantity, thereby ensuring smooth operation of the diesel engine and improving the engine's performance in dual-fuel operation mode.
[0003] As mentioned above, many ships use natural gas as an alternative fuel in their low-speed two-stroke engines. Natural gas, as a clean, efficient, and low-carbon fossil fuel, plays a crucial role in the transition of energy consumption from fossil fuels to renewable energy, promoting emissions reduction and carbon control in ship engines. However, ship natural gas / diesel dual-fuel engines typically produce unburned hydrocarbon emissions, primarily methane. Unburned methane emissions from two-stroke dual-fuel engines mainly consist of three parts: unburned methane accumulated near the bottom of the exhaust valve, unburned methane remaining in the piston crown area, and unburned methane caused by the flame quenching effect near the combustion chamber walls. The large-scale emission of unburned methane not only wastes energy but also increases ship operating costs and may even exacerbate the greenhouse effect.
[0004] Since ammonia is a clean energy source, its use can effectively solve the carbon emission problem caused by combustion. However, ammonia fuel is difficult to ignite, has a long minimum ignition delay time, and the flame propagation is slow. Directly using diesel for ignition requires a large proportion of diesel fuel, which reduces the engine's emission reduction effect. Therefore, we propose an ammonia combustion system and control method. Summary of the Invention
[0005] The purpose of this invention is to provide an ammonia scavenging system and control method to solve the problems mentioned in the background art.
[0006] To achieve the above objectives, the present invention provides the following technical solution: an ammonia entrainment system for a natural gas-diesel dual-fuel engine, comprising a diesel supply system and an LNG supply system, and a dual-fuel engine installed at the output end of the diesel supply system and the LNG supply system; The dual-fuel engine has a combustion chamber inside, a piston below the combustion chamber, a cylinder body outside the piston, a cylinder head on top of the cylinder body, an ammonia and natural gas dual-fuel injector inside the cylinder head, and a diesel ignition injector inside the ammonia and natural gas dual-fuel injector. An exhaust valve is installed on top of the combustion chamber. The ammonia and natural gas dual-fuel injector has two sets of air supply channels, one set being channel A and the other being channel B. An exhaust valve sleeve is installed on top of the exhaust valve, and an exhaust pipe is installed on one side of the exhaust valve.
[0007] Preferably, the LNG supply system includes a set of natural gas storage tanks and a set of ammonia fuel storage tanks.
[0008] Preferably, an ME-GI-ECS control system is provided between the LNG supply system and the dual-fuel engine, and an ME-ECS control system is provided between the diesel supply system and the dual-fuel engine.
[0009] Preferably, the ME-GI-ECS control system is used for electrically controlled natural gas injection, electrically controlled ammonia fuel injection, switching between fuel oil operation and dual-fuel operation, gas combustion monitoring, gas cut-off and conversion between natural gas and ammonia, ventilation and leakage alarm of double-walled pipes, sealing oil control, inert gas purging of gas pipelines, and interaction with the gas supply system.
[0010] Preferably, the ME-ECS control system is used to control the electronic ignition diesel injection, the opening of the electronic exhaust valve, the governor and speed control, the starting and reversing process, and cylinder lubrication.
[0011] Preferably, the combustion chamber consists of the bottom of the exhaust valve, the top of the piston, the inside of the cylinder head, and the inside of the cylinder body.
[0012] Preferably, the ammonia entrainment control method for the natural gas-diesel dual-fuel engine includes the following steps: S1: When the piston is near top dead center, the ignition diesel fuel is first injected into the combustion chamber through the ignition diesel fuel injector for compression ignition, providing ignition energy; S2: Natural gas is then injected into the combustion chamber through channel A of the ammonia and natural gas dual-fuel injector at an injection pressure of 20-30MPa for combustion. After the natural gas is ignited, the ammonia fuel is injected into the combustion chamber through channel B of the ammonia and natural gas dual-fuel injector for combustion. S3: The jet of ammonia fuel sweeps the natural gas combustion flame in the combustion chamber, preventing methane from colliding with the cylinder head and cylinder body walls; S4: Ammonia and natural gas have different flame propagation speeds. Under the interaction of flames, the flow field in the combustion chamber is more likely to form different velocity layers, which promotes the movement of oxygen in each fuel vortex, and enables the combustible mixture to form a lean / rich oxygen region conversion, promotes the combustion of methane in the middle oxygen-rich region, and the combustion of ammonia fuel in the oxygen-lean region near the cylinder head and cylinder body of the combustion chamber. S5: The low-speed flame of ammonia fuel disturbs the methane near the inner wall of the cylinder head and cylinder body, increases the radial flow velocity in the combustion chamber, guides the methane away from the inner wall of the cylinder head and cylinder body, and forms a low-speed flame layer mainly composed of ammonia fuel near the combustion chamber wall. This blocks the path of methane impacting the combustion chamber wall, reduces the low wall temperature of the combustion chamber, and interrupts the thermochemical branching reaction of methane, thus preventing the natural gas flame from continuing to propagate.
[0013] As can be seen from the above description, the technical solution described in this application can certainly solve the technical problem that this application aims to address.
[0014] Meanwhile, through the above technical solutions, the present invention has at least the following beneficial effects: This invention employs ammonia entrainment combustion in a natural gas / diesel dual-fuel engine. Ammonia is a zero-carbon fuel, and its combustion products contain no carbon dioxide. A small proportion of diesel fuel is used to ignite the natural gas, and the heat released by the natural gas is then used to ignite the ammonia fuel, ensuring the stability of ignition. Ammonia entrainment prevents the natural gas from colliding with the combustion wall, reducing unburned methane emissions. This invention reduces the unburned methane produced by the cooling effect of the combustion chamber by entraining ammonia fuel, thereby reducing the emission of unburned methane. It also solves the problems of difficult ignition and unstable ignition of ammonia fuel, effectively ensuring the co-combustion of ammonia and natural gas. Ammonia fuel is a zero-carbon fuel, and there is no carbon dioxide in the combustion products, which effectively reduces the carbon dioxide emissions of the engine. Attached Figure Description
[0015] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the dual-fuel engine structure of the present invention; Figure 3 For the present invention Figure 2 A magnified structural diagram at point A in the diagram.
[0016] In the diagram: 1. Exhaust valve; 2. Ignition diesel injector; 3. Ammonia and natural gas dual-fuel injector; 4. Piston; 5. Exhaust valve sleeve; 6. Cylinder head; 7. Cylinder body; 8. Exhaust pipe; 9. Combustion chamber; 10. Passage A; 11. Passage B. Detailed Implementation
[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0018] Implementation Case 1 As attached Figure 1 and Figure 3 As shown, the present invention provides a technical solution: an ammonia injection system for a natural gas-diesel dual-fuel engine, comprising a diesel supply system and an LNG supply system, and a dual-fuel engine installed at the output ends of the diesel supply system and the LNG supply system. The LNG supply system includes a set of natural gas storage tanks and a set of ammonia fuel storage tanks. An ME-GI-ECS control system is installed between the LNG supply system and the dual-fuel engine, and an ME-ECS control system is installed between the diesel supply system and the dual-fuel engine. The ME-GI-ECS control system is used for electronically controlled natural gas injection, electronically controlled ammonia fuel injection, switching between fuel operation and dual-fuel operation, gas combustion monitoring, gas cut-off and conversion between natural gas and ammonia, dual-wall pipe ventilation and leakage alarm, sealing oil control, inert gas purging of gas pipelines, and interaction with the gas supply system. The ME-ECS control system is used to control electronically controlled ignition diesel injection, electronically controlled exhaust valve opening, governor and speed control, starting and reversing process, and cylinder lubrication. The dual-fuel engine has a combustion chamber 9 inside, which is composed of the bottom of the exhaust valve 1, the top of the piston 4, the inside of the cylinder head 6, and the inside of the cylinder body 7. The piston 4 is located below the combustion chamber 9, and the cylinder body 7 is located outside the piston 4. The cylinder head 6 is located on the top of the cylinder body 7. The ammonia and natural gas dual-fuel injector 3 is located inside the cylinder head 6, and the ignition diesel injector 2 is located inside the ammonia and natural gas dual-fuel injector 3. The exhaust valve 1 is installed on the top of the combustion chamber 9. The ammonia and natural gas dual-fuel injector 3 has two sets of air supply channels inside, one set of air supply channels is channel A 10, and the other set of air supply channels is channel B 11. The exhaust valve sleeve 5 is located on the top of the exhaust valve 1, and the exhaust pipe 8 is located on one side of the exhaust valve 1.
[0019] Example 2 The solution in Example 1 will be further described below with reference to its specific working method. like Figure 2 and Figure 3 As shown, in a preferred embodiment, based on the above method, the ammonia entrainment control method for a natural gas-diesel dual-fuel engine further includes the following steps: S1: When piston 4 reaches near top dead center, the ignition diesel fuel is first injected into combustion chamber 9 through ignition diesel fuel injector 2 for compression ignition, providing ignition energy; S2: Natural gas is injected into combustion chamber 9 through channel A 10 in ammonia and natural gas dual fuel injector 3 at an injection pressure of 20-30MPa. After the natural gas is ignited, ammonia fuel is injected into combustion chamber 9 through channel B 11 in ammonia and natural gas dual fuel injector 3. S3: The jet of ammonia fuel sweeps the natural gas combustion flame in the combustion chamber 9, preventing methane from colliding with the cylinder head 6 and the cylinder body 7. S4: Ammonia and natural gas have different flame propagation speeds. Under the interaction of flames, the flow field in combustion chamber 9 is more likely to form layers of different flow velocities, which promotes the movement of oxygen in each fuel vortex, and enables the combustible mixture to form a lean / rich oxygen region conversion, which promotes the combustion of methane in the intermediate oxygen-rich region, while ammonia fuel is burned in the lean oxygen region near the cylinder head 6 and cylinder body 7 of combustion chamber 9. S5: The low-speed flame of ammonia fuel disturbs the methane near the inner wall of the cylinder head 6 and cylinder body 7, increases the radial flow velocity in the combustion chamber 9, guides the methane away from the inner wall of the cylinder head 6 and cylinder body 7, and forms a low-speed flame layer mainly composed of ammonia fuel near the wall of the combustion chamber 9. This blocks the path of methane impacting the wall of the combustion chamber 9, reduces the low wall temperature of the combustion chamber 9, and causes the thermochemical branching reaction of methane to be interrupted, thus preventing the natural gas flame from continuing to propagate.
[0020] This invention addresses the technical problem of existing natural gas-diesel dual-fuel engines experiencing difficulties in combustion and ignition when using ammonia fuel, characterized by a long minimum ignition delay time, slow flame propagation, and the need for a large proportion of diesel fuel for direct ignition, thus reducing engine emission reduction efficiency. The invention employs the technical solutions described in the above embodiments. Furthermore, the implementation process of the above technical solutions is as follows: The diesel supply system and LNG supply system are based on the existing layout of the natural gas / diesel dual-fuel engine. There is no need to add an ammonia fuel storage tank. While ensuring the natural gas usage, one of the natural gas storage tanks will be replaced with ammonia fuel storage to form an ammonia fuel supply system. The ME-GI-ECS gas control system controls ammonia and natural gas. Specifically, ME-GI-ECS performs electronic natural gas injection, electronic ammonia fuel injection, switching between fuel oil and dual-fuel operation, gas combustion monitoring, gas cutoff and switching between natural gas and ammonia, dual-wall pipe ventilation and leak alarm, sealing oil control, inert gas purging of gas pipelines, and interaction with the gas supply system. The ME-ECS diesel control system primarily controls: electronic ignition diesel injection, electronic exhaust valve opening, governor and speed control, starting and reversing processes, and cylinder lubrication, among other conventional engine controls. In the natural gas / diesel dual-fuel engine, ammonia entrainment combustion is employed, utilizing a small proportion of diesel fuel to ignite natural gas, and then using the heat released from the natural gas to ignite the ammonia fuel, ensuring stable ignition. Combustion chamber 9 consists of the bottom of exhaust valve 1, the top of piston 4, the interior of cylinder head 6, and the interior of cylinder body 7. When piston 4 reaches near top dead center, ignition diesel fuel is first injected into combustion chamber 9 through ignition diesel injector 2 for compression ignition, providing ignition energy. Natural gas is then injected into combustion chamber 9 at an injection pressure of 20-30 MPa through channel A 10 of ammonia and natural gas dual-fuel injector 3 for combustion. After natural gas ignition, ammonia fuel is injected into combustion chamber 9 through channel B 11 of ammonia and natural gas dual-fuel injector 3 for combustion. The ammonia fuel jet entrains the natural gas combustion flame in combustion chamber 9, preventing methane from colliding with the cylinder head 6 and cylinder body 7 walls. Ammonia and natural gas flames have different propagation speeds, resulting in flame interaction. The flow field in the lower combustion chamber 9 more easily forms layers of different flow velocities, promoting the movement of oxygen in each fuel vortex, enabling the combustible mixture to form lean / rich oxygen regions, promoting the combustion of methane in the intermediate oxygen-rich region, and the combustion of ammonia fuel in the lean oxygen region near the cylinder head 6 and cylinder body 7 of the combustion chamber 9; the low-speed flame of ammonia fuel disturbs the methane near the inner wall of the cylinder head 6 and cylinder body 7, strengthens the radial flow velocity in the flow field of the combustion chamber 9, guides the methane away from the inner wall of the cylinder head 6 and cylinder body 7, and forms a low-speed flame layer mainly composed of ammonia fuel near the wall of the combustion chamber 9, blocking the path of methane impacting the wall of the combustion chamber 9, reducing the low wall temperature of the combustion chamber 9, causing the thermochemical branching reaction of methane to be interrupted, and the phenomenon that the natural gas flame cannot continue to propagate; With the above-mentioned settings, this application will certainly solve the above-mentioned technical problems, and at the same time achieve the following technical effects: This invention employs ammonia entrainment combustion in a natural gas / diesel dual-fuel engine. Ammonia is a zero-carbon fuel, and its combustion products contain no carbon dioxide. A small proportion of diesel fuel is used to ignite the natural gas, and the heat released by the natural gas is then used to ignite the ammonia fuel, ensuring the stability of ignition. Ammonia entrainment prevents the natural gas from colliding with the combustion wall, reducing unburned methane emissions. This invention reduces the unburned methane produced by the cooling effect of the combustion chamber 9 by using ammonia fuel, thus reducing the emission of unburned methane. It also solves the problems of difficult ignition and unstable ignition of ammonia fuel, effectively ensuring the co-combustion of ammonia and natural gas. Ammonia fuel is a zero-carbon fuel, and there is no carbon dioxide in the combustion products, which effectively reduces the carbon dioxide emissions of the engine.
[0021] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A method for controlling ammonia entrainment in a natural gas-diesel dual-fuel engine, characterized in that, It includes a diesel supply system and an LNG supply system, as well as a dual-fuel engine installed at the output of the diesel supply system and the LNG supply system; The dual-fuel engine has a combustion chamber (9) inside, a piston (4) below the combustion chamber (9), a cylinder body (7) outside the piston (4), a cylinder head (6) on top of the cylinder body (7), an ammonia and natural gas dual-fuel injector (3) inside the cylinder head (6), and a diesel ignition injector (2) inside the ammonia and natural gas dual-fuel injector (3). A discharge valve (1) is installed on top of the combustion chamber (9). The ammonia and natural gas dual-fuel injector (3) has two sets of air supply channels inside, one set of which is channel A (10) and the other set of which is channel B (11). An exhaust valve sleeve (5) is installed on top of the discharge valve (1), and an exhaust pipe (8) is installed on one side of the discharge valve (1). The ammonia entrainment control method for the natural gas-diesel dual-fuel engine includes the following steps: S1: When the piston (4) runs to near the top dead center, the ignition diesel fuel is first injected into the combustion chamber (9) through the ignition diesel fuel injector (2) for compression ignition, providing ignition energy; S2: Natural gas is injected into the combustion chamber (9) through the A channel (10) of the ammonia and natural gas dual fuel injector (3) at an injection pressure of 20-30MPa. After the natural gas is ignited, the ammonia fuel is injected into the combustion chamber (9) through the B channel (11) of the ammonia and natural gas dual fuel injector (3) for combustion. S3: The jet of ammonia fuel sweeps the natural gas combustion flame in the combustion chamber (9) to prevent methane from colliding with the cylinder head (6) and cylinder body (7) walls; S4: The flame propagation speed of ammonia and natural gas is different. Under the interaction of flames, the flow field in the combustion chamber (9) is more likely to form different velocity layers, which promotes the movement of oxygen in each fuel vortex, and makes the combustible mixture form a lean / rich oxygen region conversion, which promotes the combustion of methane in the middle oxygen-rich region, and the ammonia fuel is burned in the lean oxygen region near the cylinder head (6) and cylinder body (7) of the combustion chamber (9). S5: The low-speed flame of ammonia fuel disturbs the methane near the inner wall of the cylinder head (6) and cylinder body (7), strengthens the radial flow velocity in the combustion chamber (9), guides the methane away from the inner wall of the cylinder head (6) and cylinder body (7), and forms a low-speed flame layer mainly composed of ammonia fuel near the wall of the combustion chamber (9), blocking the path of methane impacting the wall of the combustion chamber (9), reducing the low wall temperature of the combustion chamber (9) and causing the thermochemical branching reaction of methane to be interrupted, and the natural gas flame cannot continue to propagate.
2. The ammonia entrainment control method for a natural gas-diesel dual-fuel engine according to claim 1, characterized in that, The LNG supply system includes a set of natural gas storage tanks and a set of ammonia fuel storage tanks.
3. The ammonia entrainment control method for a natural gas-diesel dual-fuel engine according to claim 1, characterized in that, The LNG supply system and the dual-fuel engine are connected by an ME-GI-ECS control system, and the diesel supply system and the dual-fuel engine are connected by an ME-ECS control system.
4. The ammonia entrainment control method for a natural gas-diesel dual-fuel engine according to claim 3, characterized in that, The ME-GI-ECS control system is used for electrically controlled natural gas injection, electrically controlled ammonia fuel injection, switching between fuel oil operation and dual-fuel operation, gas combustion monitoring, gas cut-off and conversion between natural gas and ammonia, ventilation and leakage alarm for double-walled pipes, sealing oil control, inert gas purging of gas pipelines, and interaction with the gas supply system.
5. The ammonia entrainment control method for a natural gas-diesel dual-fuel engine according to claim 3, characterized in that, The ME-ECS control system is used to control electronic ignition diesel injection, electronic exhaust valve opening, governor and speed control, starting and reversing process and cylinder lubrication.
6. The ammonia entrainment control method for a natural gas-diesel dual-fuel engine according to claim 1, characterized in that, The combustion chamber (9) consists of the bottom of the exhaust valve (1), the top of the piston (4), the inside of the cylinder head (6), and the inside of the cylinder body (7).