A flushing system and method for a low flashpoint fuel

Abstract

This invention discloses a flushing system and method for low flash point fuel. The system includes a low-carbon fuel supply module connected to a low-carbon fuel tank. The low-carbon fuel supply module and a fuel mixing tank are respectively connected to the two inlet ends of a fuel inlet switching valve. The outlet end of the fuel inlet switching valve is sequentially connected to the inlet of a low-carbon fuel engine via a first fuel supply shut-off valve and a second fuel supply shut-off valve. The outlet end of the first fuel supply shut-off valve is also connected to the low-carbon fuel tank via a vent valve. The outlet of the low-carbon fuel engine is connected to the inlet end of a fuel return switching valve. The two outlet ends of the fuel return switching valve are respectively connected to the low-carbon fuel tank and the fuel mixing tank. The inlet of the low-carbon fuel engine is also connected to a flushing pipeline, which is equipped with a flushing valve. This invention uses diesel, which is also a liquid fuel, and operates on a liquid-to-liquid principle, allowing for a more flexible system layout and avoiding excessive consumption of compressed gas.

Description

Technical Field

[0001] This invention relates to a technical solution for the safe use of low flash point fuels, specifically to a principle and operating method for flushing pipelines with low flash point fuels, belonging to the field of power machinery technology, and particularly in the application field of marine high-power medium-low speed new dual-fuel engines. Background Technology

[0002] With the IMO (International Maritime Organization) placing increasing emphasis on ship carbon emissions, a series of mandatory regulations have been introduced in recent years to restrict and constrain ship carbon emissions. Therefore, seeking low-carbon or zero-carbon alternatives to traditional fossil fuels has become a crucial and effective method for addressing ship carbon emissions. Currently, various new fuels such as methanol, ethanol, LPG, LNG, ammonia, hydrogen, and DME have been technically proven to be usable in reciprocating internal combustion engines, replacing traditional diesel fuels. Depending on the fuel type, they can reduce ship carbon emissions to varying degrees. However, unlike traditional diesel fuels, these new fuels share common characteristics such as low viscosity, low flash point, and low calorific value, as well as unique characteristics such as strong corrosiveness and toxicity. The low flash point, in particular, poses a significant challenge to the safe use of these fuels. According to the requirements of existing international laws and regulations, when a ship uses low flash point fuel, the relevant pipelines for low flash point fuel must be purged and cleaned when the engine is stopped or other engines are not using low flash point fuel. This ensures that no low flash point fuel remains in the engine pipelines, thereby eliminating the flammability and explosiveness of low flash point fuel and making the engine using low flash point fuel extremely safe. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a system and method for purging and cleaning pipelines related to low flash point fuels.

[0004] To address the aforementioned problems, this invention provides a flushing system for low flash point fuel, comprising a low-carbon fuel supply module connected to a low-carbon fuel tank, a fuel mixing tank and a fuel inlet switch valve connected to the two inlet ends of the fuel inlet switch valve, the outlet end of the fuel inlet switch valve connected to the inlet of a low-carbon fuel engine via a first fuel supply stop valve and a second fuel supply stop valve, the outlet end of the first fuel supply stop valve also connected to the low-carbon fuel tank via a vent valve; the outlet of the low-carbon fuel engine connected to the inlet end of a fuel return switch valve, the two outlet ends of the fuel return switch valve connected to the low-carbon fuel tank and the fuel mixing tank respectively; the inlet of the low-carbon fuel engine also connected to a flushing pipeline, on which a flushing valve is provided.

[0005] Preferably, the fuel mixing tank is connected to the fuel inlet switching valve via a mixed fuel supply pump.

[0006] Preferably, a flow meter is installed on the pipeline between the fuel mixing tank and the fuel inlet switching valve.

[0007] Preferably, the flushing medium in the flushing pipeline is the first fuel oil, i.e., diesel oil. In this invention, the low-carbon fuel is the engine's second fuel, and the first fuel is conventional diesel fuel.

[0008] This invention also provides a flushing method for low flash point fuels. Using the aforementioned low flash point fuel flushing system, when switching from low-carbon fuel to diesel fuel, the residual low flash point fuel in the low-carbon fuel pipeline must be flushed clean. Therefore, at the moment of the switching command, the diesel fuel injection system will immediately start working (the first fuel injection system and the second fuel injection system are two independent systems). Subsequently, the fuel inlet switching valve, fuel supply cut-off valve one, and fuel supply cut-off valve two are closed, the vent valve is opened, and at the same time, the fuel return switching valve is switched to connect with the low-carbon fuel tank. The low-carbon fuel in the low-carbon fuel engine is discharged back to the low-carbon fuel tank through the fuel return switching valve. When the low-carbon fuel pipeline of the low-carbon fuel engine detects a pressure drop to a set value, the fuel return switching valve is switched to connect with the fuel mixing tank, and at the same time, the flushing valve is opened. Diesel fuel enters the low-carbon fuel engine through the flushing valve, flushing the low-carbon fuel pipeline of the low-carbon fuel engine, and then flows back to the fuel mixing tank through the switching valve.

[0009] Preferably, the set value is 1 bar.

[0010] Preferably, the fuel in the fuel mixing tank can be supplied to the working state of each valve on the pipeline and enter the low-carbon fuel engine to participate in combustion.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0012] 1) Compared with the current method of purging pipelines with inert gases such as nitrogen, the operation principle of using diesel, which is also a liquid fuel, to purge the pipelines allows for a more flexible system layout and avoids the consumption of large amounts of compressed gas.

[0013] 2) Using traditional diesel fuel already present in the engine as a medium to purge liquid fuels such as methanol and DME makes the system structure very simple and the cost low;

[0014] 3) The diesel-methanol mixture formed after diesel flushing can be recycled as fuel again, so this method has extremely high economic efficiency. Attached Figure Description

[0015] Figure 1 A schematic diagram of the flushing system for low flash point fuel provided by the present invention;

[0016] Figure 2 A schematic diagram of the low-carbon fuel operating mode;

[0017] Figure 3 This is a schematic diagram of the mixed fuel operating mode;

[0018] Figure 4 This is a schematic diagram of the first stage - venting - in the flushing mode;

[0019] Figure 5 This is a schematic diagram of the second stage of rinsing under rinsing mode;

[0020] In the diagram, dashed lines represent mixed fuels, and solid lines represent diesel or low-carbon fuels. Detailed Implementation

[0021] To make the present invention more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings.

[0022] Example

[0023] like Figure 1 As shown, this invention provides a flushing system for low flash point fuel, comprising a low-carbon fuel supply module 2 connected to a low-carbon fuel tank 1. The low-carbon fuel supply module 2 and a fuel mixing tank 3 are respectively connected to the two inlet ends of a fuel inlet switching valve 5 (the fuel mixing tank 3 is sequentially connected to a mixed fuel supply pump 13, a flow meter 11, and the fuel inlet switching valve 5). The outlet end of the fuel inlet switching valve 5 is sequentially connected to the inlet of a low-carbon fuel engine 4 via a fuel supply shut-off valve 1 8 and a fuel supply shut-off valve 2 6. The outlet end of the fuel supply shut-off valve 1 8 is also connected to the low-carbon fuel tank 1 via a vent valve 7. The outlet of the low-carbon fuel engine 4 is connected to the inlet end of a fuel return switching valve 9. The two outlet ends of the fuel return switching valve 9 are respectively connected to the low-carbon fuel tank 1 and the fuel mixing tank 3. The inlet of the low-carbon fuel engine 4 is also connected to a flushing pipeline, which is equipped with a flushing valve 10. The flushing medium in the flushing pipeline is diesel fuel.

[0024] The working principle of the above flushing system is as follows:

[0025] Low-carbon fuel operating modes (such as) Figure 2 (As shown): The inlet end of the fuel inlet switching valve 5 is switched to connect with the fuel supply module 1, the fuel supply shut-off valve 1 8 and the fuel supply shut-off valve 2 6 are opened, and the vent valve 7, the fuel return switching valve 9 and the flushing valve 10 are closed.

[0026] Hybrid fuel operating modes (such as) Figure 3 (As shown): The inlet end of the fuel inlet switching valve 5 is switched to connect with the fuel mixing box 3, the fuel supply stop valve 1 8 and the fuel supply stop valve 2 6 are opened, and the vent valve 7, the fuel return switching valve 9 and the flushing valve 10 are closed.

[0027] The first stage of the flushing mode - venting (e.g.) Figure 4 (As shown): When switching from low-carbon fuel to diesel fuel, the residual low-flash-point fuel in the low-carbon fuel pipeline must be flushed clean. Therefore, at the moment of the switching command, the diesel fuel injection system will start working immediately. Subsequently, the fuel inlet switching valve 5, fuel supply cut-off valve 1 8, and fuel supply cut-off valve 2 6 will close, and the vent valve 7 will open. At the same time, the fuel return switching valve 9 will switch to connect with the low-carbon fuel tank 1. The low-carbon fuel in the low-carbon fuel engine 4 will be discharged back to the low-carbon fuel tank 1 through the fuel return switching valve 9. The flushing valve 10 will always be closed.

[0028] The second stage of the flushing mode - flushing (such as...) Figure 5 (As shown): When the low-carbon fuel line of the low-carbon fuel engine 4 detects a pressure drop of 1 bar, the fuel return switching valve 9 is connected to the fuel mixing tank 3, and the flushing valve 10 is opened. Diesel fuel enters the low-carbon fuel engine 4 through the flushing valve 10, flushes the low-carbon fuel line of the low-carbon fuel engine 4, and flows back to the fuel mixing tank 3 through the switching valve 9. At this time, the fuel inlet switching valve 5, the fuel supply cut-off valve 1 8, and the fuel supply cut-off valve 2 6 remain closed, and the vent valve 7 remains open.

[0029] The fuel in the fuel mixing tank 3 supplies fuel to the various valves on the pipeline and enters the low-carbon fuel engine 4 for combustion. The fuel inlet switching valve 5 and the fuel return switching valve 9 are two key three-way valves in the system. The fuel inlet switching valve 5 switches the fuel supply source, while the fuel return switching valve 9 controls the return flow of fuel from the engine. It directly returns clean low-carbon fuel to the fuel tank and also circulates the fuel mixture back to the mixing fuel tank 3 when diesel fuel enters the pipeline to flush the low-carbon fuel. The mixed fuel supply pump 13 circulates the fuel in the mixing fuel tank 3, which then enters the main unit of the low-carbon fuel engine 4 for reuse via the fuel inlet switching valve 5.

Claims

1. A flushing system for low flash point fuel, characterized in that, The system includes a low-carbon fuel supply module (2) connected to a low-carbon fuel tank (1). The low-carbon fuel supply module (2) and the fuel mixing tank (3) are respectively connected to the two inlet ends of the fuel inlet switching valve (5). The outlet end of the fuel inlet switching valve (5) is connected to the inlet of the low-carbon fuel engine (4) in sequence through the first fuel supply stop valve (8) and the second fuel supply stop valve (6). The outlet end of the first fuel supply stop valve (8) is also connected to the low-carbon fuel tank (1) through the vent valve (7). The outlet of the low-carbon fuel engine (4) is connected to the inlet end of the fuel return switching valve (9). The two outlet ends of the fuel return switching valve (9) are respectively connected to the low-carbon fuel tank (1) and the fuel mixing tank (3). The inlet of the low-carbon fuel engine (4) is also connected to the flushing pipeline, and the flushing pipeline is equipped with a flushing valve (10). The low flash point fuel is liquid methanol or liquid DME.

2. The flushing system for low flash point fuel as described in claim 1, characterized in that, The fuel mixing tank (3) is connected to the fuel inlet switching valve (5) via a fuel mixing supply pump (13).

3. The flushing system for low flash point fuel as described in claim 1, characterized in that, A flow meter (11) is installed on the pipeline between the fuel mixing tank (3) and the fuel inlet switching valve (5).

4. The flushing system for low flash point fuel as described in claim 1, characterized in that, The flushing medium in the flushing pipeline is diesel fuel.

5. A method for flushing low flash point fuel, characterized in that, Using the flushing system for low flash point fuel as described in any one of claims 1-4, when switching from low carbon fuel to diesel fuel, the residual low flash point fuel in the low carbon fuel pipeline must be flushed clean. Therefore, at the moment of the switching command, the diesel fuel injection system will start working immediately. Subsequently, the fuel inlet switching valve (5), fuel supply stop valve one (8), and fuel supply stop valve two (6) are closed, the vent valve (7) is opened, and at the same time, the fuel return switching valve (9) is switched to connect with the low carbon fuel tank (1). The low carbon fuel in the low carbon fuel engine (4) is discharged back to the low carbon fuel tank (1) through the fuel return switching valve (9). When the low carbon fuel pipeline of the low carbon fuel engine (4) detects that the pressure has dropped to the set value, the fuel return switching valve (9) is switched to connect with the fuel mixing tank (3). At the same time, the flushing valve (10) is opened, and diesel fuel enters the low carbon fuel engine (4) through the flushing valve (10), flushing the low carbon fuel pipeline of the low carbon fuel engine (4), and then flows back to the fuel mixing tank (3) through the switching valve (9).

6. The flushing method for low flash point fuel as described in claim 5, characterized in that, The setting value is 1 bar.

7. The flushing method for low flash point fuel as described in claim 5, characterized in that, The fuel in the fuel mixing tank (3) can supply the working state of each valve on the pipeline and enter the low-carbon fuel engine (4) to participate in combustion.

Images