An LPG dual fuel supply pipeline system

Abstract

The present invention relates to an LPG dual-fuel supply pipeline system, including a conventional fuel system and an LPG fuel supply system. The original single-fuel engine of the conventional fuel system is changed into a dual-fuel engine suitable for both conventional fuel and LPG fuel, and its fuel supply system is changed into a dual-system supply of conventional fuel and LPG fuel. The original conventional fuel system remains unchanged, and the newly added LPG fuel supply system is composed of a storage tank delivery pipeline, a high-pressure boosting unit, a distribution control valve group, an emergency discharge box, a safety valve release buffer tank, a double-walled pipe and the like. The function is to deliver low-ignition-point petroleum gas, keep it in a liquefied state until the engine cylinder nozzle releases vaporization, and then burns to drive the engine piston to work. The system of the present invention allows the engine to use LPG as fuel, reduces costs, and the dual-fuel supply is flexibly switched. It is switched to use LPG fuel in the offshore, meets the emission standards of IMO and various port countries, is environmentally friendly and energy-saving, and is easy to operate.

Description

Technical Field

[0001] The invention relates to the technical field of fuel supply, in particular to an LPG dual-fuel supply pipeline system. Background Art

[0002] On large transport ships, conventional marine fuel supply systems are generally used, which consist of a single-fuel engine, oil tank, fuel inlet pipe, fuel pump, fuel return pipe, control valve and quick-closing valve. At present, this traditional fuel supply system has the following problems and disadvantages:

[0003] 1. High fuel consumption and high cost.

[0004] 2. The emissions cause serious environmental pollution, producing harmful sulfur oxides, nitrogen oxides, PM2.5 pollutants, and CO2 emissions.

[0005] 3. The uncertainty of fuel cost is high, which has a great impact on the shipping cost.

[0006] Therefore, we propose an LPG dual fuel supply pipeline system. Summary of the invention

[0007] The object of the present invention is to provide an LPG dual-fuel supply pipeline system.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] An LPG dual-fuel supply pipeline system includes a conventional fuel system and an LPG fuel supply system. The original single-fuel engine of the conventional fuel system is changed into a dual-fuel engine suitable for both conventional fuel and LPG fuel, and its fuel supply system is changed into a dual-system supply of conventional fuel and LPG fuel. The original conventional fuel system remains unchanged, and the newly added LPG fuel supply system consists of a storage tank delivery pipeline, a high-pressure boosting unit, a distribution control valve group, an emergency discharge box, a safety valve release buffer tank, a double-walled pipe and the like. The function of the system is to deliver low-ignition-point petroleum gas, keep it in a liquefied state until the engine cylinder nozzle releases vaporization, and then burns to drive the engine piston to do work.

[0010] Preferably, the storage tank delivery pipeline consists of a storage tank, a low-pressure pump, an outlet control valve, a one-way valve, a safety valve, a safety valve release pipe, a remote pressure gauge and a delivery pipeline, which delivers the LPG in the storage tank to the high-pressure boosting unit.

[0011] Preferably, the high-pressure boosting unit is composed of a high-pressure pump, a filter, a safety valve, a one-way valve, a three-way valve, a flow control valve, a remote pressure gauge, a remote temperature gauge, a heat exchanger, a nitrogen buffer tank, a delivery pipeline, an ethylene glycol pipeline, a nitrogen pipeline, a safety valve release pipe and the like. The LPG delivered from the storage tank is further pressurized and filtered to maintain the necessary cleanliness. The heat exchanger can adjust the LPG temperature within a specified range and keep it in a liquid state. The buffer tank can receive the refluxed LPG to provide a buffer storage space.

[0012] Preferably, the distribution control valve group is divided into two parts: a gas supply valve group and a return valve group, which are composed of a remote pneumatic control valve, a pressure control valve, a remote pressure gauge, a remote thermometer, a liquid level switch, a supply pipe, a return pipe, an emergency discharge pipe, an air-controlled valve control instrument pipe, an air-controlled valve box, a nitrogen blow-off pipe, etc., to monitor and control pipeline transportation, and can be discharged urgently in case of leakage, reduce the pressure on the return pipe, and provide nitrogen blow-off to clean up residual LPG in the pipeline.

[0013] Preferably, the emergency discharge box part includes a discharge box, a liquid level gauge, a relief valve, a discharge pipe, etc., which provide a buffer when the distribution control valve group discharges urgently, collect liquid that may exist when LPG vaporizes during discharge, and avoid direct discharge into the atmosphere.

[0014] Preferably, the buffer tank portion of the safety release valve includes a buffer tank, a liquid level gauge, a relief valve, a discharge pipe, etc., which provide buffering when the safety release valve is discharged urgently, collect liquid that may be present when LPG vaporizes during discharge, and avoid direct discharge into the atmosphere.

[0015] Preferably, the double-walled delivery pipe is composed of a double-walled inner pipe, a double-walled outer pipe, a double-walled ventilation pipe, a fan and a pipe clamp, etc. The double-walled inner pipe is used to deliver LPG to the dual-fuel engine, and the excess fuel is refluxed. The outer pipe provides additional protection when the inner pipe leaks, and the leakage is controlled within the outer pipe. The double-walled ventilation pipe is used for ventilation between the double-walled inner pipe and the outer pipe. When LPG leaks from the inner pipe to the outer pipe, the vaporized LPG is pumped to an outdoor safe area by the fan. The pipe clamp is installed between the inner pipe and the outer pipe to provide support and shock absorption. The main purpose is to adopt a double-walled pipe design for the pipeline between the distribution control valve group and the dual-fuel engine, especially for this part of the LPG pipe passing through the main engine room and other mechanical places, to avoid leakage that causes the entire mechanical place or even the entire ship to be in great danger of explosion.

[0016] Compared with the prior art, the present invention has the following beneficial effects: the present invention provides a dual-fuel system that can use fuel oil and LPG clean energy at the same time, which is particularly suitable for use with high-power engines with high fuel consumption on large transport ships, and can achieve the following effects:

[0017] 1. Allow the engine to use LPG as fuel, reducing costs;

[0018] 2. Using LPG as clean energy can reduce sulfur oxides in emissions by 100%, nitrogen oxides by 40%-85%, PM2.5 pollutants by 95-100%, and CO2 emissions by 20%, so that the pollutant emissions of ships meet the increasingly stringent standards of the IMO International Maritime Organization and various port countries;

[0019] 3. Flexible switching of dual fuel supply, switching to LPG fuel in offshore, in line with IMO and national emission standards of various ports, environmental protection, energy saving and easy operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a diagram of a dual fuel system of the present invention;

[0021] Figure 2 An enlarged view of the distribution control valve group in the dual fuel system of the present invention;

[0022] Figure 3 It is an enlarged view of the high-pressure boosting unit in the dual-fuel system of the present invention;

[0023] Figure 4 It is an enlarged view of a conventional fuel supply system in the dual-fuel system of the present invention;

[0024] Figure 5 It is an enlarged view of the storage tank delivery pipeline in the dual fuel system of the present invention;

[0025] Figure 6 It is a sectional view of the double-walled tube axis of the present invention;

[0026] Figure 7 It is a front view of the double-walled tube of the present invention;

[0027] Figure 8 It is a side view of the double-walled tube of the present invention.

[0028] In the figure:

[0029] B1 Low pressure pump 1 S8 PT remote pressure gauge V1 Quick closing valve B2 Low pressure pump 2 S9 LS Level Switch V2 Control valve B3 High pressure pump 1 S10 TT remote temperature gauge V3 Check valve B4 High pressure pump 2 S11 PT remote pressure gauge V4 Control valve B5 Conventional fuel pump 1 S12 TT remote temperature gauge V5 Check valve P1 Conventional fuel supply pipe S13 LS Level Switch V6 Check valve P2 Conventional fuel return line S14 LS Level Switch V7 Check valve P3 LPG supply pipe SV1 Safety relief valve V8 Check valve P4 LPG return pipe SV2 Safety relief valve V9 Three-way control valve P5 Double wall pipe SV3 Safety relief valve V10 Three-way control valve P5-1 Double wall outer tube SV4 Safety relief valve V11 Flow Control Valves P5-2 Double wall inner tube SV5 Safety relief valve V12 Flow Control Valves P5-3 Double wall pipe clamp G1 Liquefied gas tank 1 V13 Remote pneumatic control valve P6 Ethylene glycol tube G2 Liquefied gas tank 2 V14 Remote pneumatic control valve P7 Nitrogen tube G3 Conventional fuel tank 1 V15 Remote pneumatic control valve P8 Safety valve release pipe G4 Nitrogen buffer tank 1 V16 Remote pneumatic control valve P9 Emergency discharge pipe G5 Emergency discharge box V17 Remote pneumatic control valve P10 Air control valve control instrument pipe G6 Safety valve release buffer tank V18 Remote pneumatic control valve P11 Nitrogen purge G7 Air control valve box V19 Remote pneumatic control valve P12 Double wall pipe ventilation-air intake F1 Fan 1 V20 Remote pneumatic control valve P13 Double wall pipe ventilation-air outlet J1 Heat exchanger (heating) V21 Drain valve S1 Filter 1 J2 Heat exchanger (cooling) V22 Pressure Control Valve S2 Filter 2 A1 Single fuel engine V23 Drain valve S3 PT remote pressure gauge A2 Dual fuel engine S4 TT remote temperature gauge S5 TT remote temperature gauge S6 PT remote pressure gauge S7 TT remote temperature gauge DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] See also Figure 1-8The present invention provides a technical solution: an LPG dual-fuel supply pipeline system, including a conventional fuel system and an LPG fuel supply system. The original single-fuel engine of the conventional fuel system is changed into a dual-fuel engine suitable for both conventional fuel and LPG fuel, and its fuel supply system is changed into a dual-system supply of conventional fuel and LPG fuel. The original conventional fuel system remains unchanged, and the newly added LPG fuel supply system is composed of a storage tank delivery pipeline, a high-pressure boosting unit, a distribution control valve group, an emergency discharge box, a safety valve release buffer tank, a double-walled pipe and the like. The function of the system is to deliver low-ignition-point petroleum gas, keep it in a liquefied state until the engine cylinder nozzle releases vaporization, and then burns to drive the engine piston to do work.

[0032] The tank delivery pipeline consists of a storage tank (G1, G2), a low-pressure pump (B1, B2), an outlet control valve V4, a one-way valve V3, a safety valve SV1, a safety valve release pipe P8, a remote pressure gauge S3 and a delivery pipeline P3. Its function is to deliver the LPG in the tank to the high-pressure booster unit. Its working mode is:

[0033] LPG (liquefied petroleum gas) is stored in storage tank G1 (working pressure 5 bar, temperature below 8°C). Here, LPG is considered to be 100% propane. From the saturated vapor pressure of propane, it can be seen that when the pressure is 5 bar, the corresponding temperature is 8°C. That is to say, when the pressure in the tank is 5 bar, the temperature of propane is kept below 8°C in the tank by relevant insulation means. It is stored in liquid form and is liquefied petroleum gas. Otherwise, it will vaporize.

[0034] Use pump B1 to extract LPG from storage tank G1 and transport it to the high-pressure booster unit at a pressure of 29 bar. S3 remote pressure gauge is used to detect the LPG pressure in the pipeline. The safety release valve SV1 is set at 32 bar. Once the pump outlet pipeline P3 exceeds 32 bar, the pressure release valve SV1 will open and the LPG liquid inside will be urgently released through pipeline P8. Pump B1 tank G1 and pump B2 tank G2 are backup for each other.

[0035] The high-pressure booster unit consists of a high-pressure pump (B3, B4), a filter (S1, S2), a safety valve (SV2, SV3, SV4, SV5), a one-way valve (V5, V6, V7, V8), a three-way valve (V9, V10), a flow control valve (V11, V12), a remote pressure gauge (S11), a remote temperature gauge (S4, S5, S10, S12), a heat exchanger (J1, J2), a nitrogen buffer tank (G4), and a delivery pipeline (P3, P4), ethylene glycol pipeline (P6), nitrogen pipeline (P7), safety valve release pipe (P9), etc. Its function is to further pressurize the LPG delivered from the storage tank to 53 bar through the high-pressure pump (B3, B4), and filter out impurities in the pipeline through a 10um level filter (S1, S2) to avoid clogging the engine. The three-way valves V9 and V10 can switch the filters S1 and S2, making them standby for each other, and pumps B3 and B4 standby for each other;

[0036] The hot glycol solution enters the heat exchanger J1 through the pipeline P6 to heat the LPG to 35°C for supply to the engine. At this time, LPG will not vaporize at 35°C, and its saturated vapor pressure is 12 bar. However, the pressure of LPG coming out of pump B1 is 29 bar ≥ 12 bar, so LPG remains in liquid state. At the same time, the hot glycol solution is cooled by LPG and becomes cold glycol.

[0037] After the 35°C LPG from the P3 pipeline reaches the engine to supply fuel, the remaining part flows back to the pipeline P4. As it passes through the main engine, its temperature rises and it becomes hotter LPG. It reaches the heat exchanger J2 and exchanges heat with the cold ethylene glycol from the P6 pipeline again. This time it is cooled. After cooling, it returns to the inlet of the high-pressure pump (B3, B4), mixes with the LPG from the tanks G1 and G2, and enters the supply pipeline P3 again.

[0038] Buffer tank G4 can receive the LPG returned from pipeline P4 to provide a buffer storage space. Flow control valves V11 and V12 can adjust the LPG flow in pipeline P4 and buffer tank respectively. A nitrogen line P7 is connected to buffer tank G4. The nitrogen pressure is 25 bar. The volume of nitrogen is compressible. The gas-liquid ratio in tank G4 can be adjusted according to the amount of LPG entering, so as to play a buffering role. Remote pressure gauge S11 provides remote pressure indication. SV5 safety valve is set at 32 bar. It is released urgently when pipeline P4 is over-pressured and discharged to a safe area through pipeline P8.

[0039] Instruments S4, S5, S10, and S12 provide remote indication of the pressure and temperature of the inlet and outlet of the heat exchangers J1 and J2. The safety valves SV2 and SV3 are set at 65 bar, and SV4 is set at 32 bar. In case of overpressure, they are released urgently and discharged to a safe area through pipeline P8. The function of the one-way valve (V5, V6, V7, and V8) is to allow the fluid to move in one direction and is irreversible.

[0040] The distribution control valve group is divided into two parts: the air supply valve group and the return valve group. It consists of remote pneumatic control valves (V13, V14, V15, V16, V17, V18, V19, V20), pressure control valve V22, remote pressure gauge (S7, S8), remote thermometer S7, liquid level switch S9, supply pipe P3, return pipe P4, emergency discharge pipe P9, air control valve control instrument pipe P10, air control valve box G7, nitrogen blow-off pipe P11, etc. Its working mode is:

[0041] The pipeline P4 is monitored by the liquid level switch S9. Once the abnormal liquid level in the pipeline causes the liquid level switch S9 to alarm, the remote control valves V13 and V20 can be opened for emergency discharge through the pipeline P9. If the abnormality cannot be solved, the remote control valves V14, V15, V16, V17, V18, and V19 are further used for emergency discharge. The working method is to close V14 on the return pipe P4, open V15 and V16 for emergency discharge through the pipeline P9, and close V18 on the supply pipe P3, open V17 and V19 for emergency discharge through the pipeline P9;

[0042] The pressure control valve V22 reduces the pressure of the return pipe P4 from 53 bar to 29 bar, ensuring that the pressure of the return pipe remains consistent with that of the suction pipe P3 of the high-pressure pump (B3, B4) when it rejoins the return pipe. Instruments S6, S7, and S8 provide remote indication of the pressure and temperature of the pipes P3 and P4.

[0043] Pneumatic valve box G7 is used for remote control of valves (V13, V14, V15, V16, V17, V18, V19, V20);

[0044] A nitrogen purge pipe P11 is provided to clean the residual LPG in the pipeline when necessary.

[0045] The emergency discharge box part includes a discharge box G5, a liquid level gauge S13, a discharge valve V21, a discharge pipe P9, etc. Its working method is to provide a buffer when the distribution control valve group is discharged urgently, collect the liquid that may exist when the LPG vaporizes in the P9 pipeline during discharge, and avoid the liquid from being directly discharged into the atmosphere. When the liquid in G5 reaches a certain amount and triggers the liquid level switch S13, it can be discharged and collected through the valve V21.

[0046] The buffer tank part of the safety release valve includes a buffer tank G6, a liquid level gauge S14, a discharge valve V23, a discharge pipe P8, etc. Its working method is to provide buffering when the safety release valve is urgently discharged through the P8 pipeline, collect the liquid that may exist when the LPG vaporizes in the P8 pipeline during discharge, and avoid direct discharge into the atmosphere. When the liquid in G6 reaches a certain amount and triggers the liquid level switch S14, it can be discharged and collected through the valve V23.

[0047] The double-walled pipe P5 is composed of a double-walled inner pipe P5-1, a double-walled outer pipe P5-2, a double-walled ventilation pipe (P12, P13), a fan F1 and a double-walled pipe clamp P5-3, etc. Its working mode is:

[0048] The double-walled inner pipe P5-1 provides LPG for delivery to the dual-fuel engine, and the excess fuel flows back to P4. The outer pipe P5-2 provides additional protection in case of leakage in the inner pipe P5-1, and controls the leakage within the outer pipe;

[0049] Double-walled pipe ventilation pipes P12 and P13 are used for positive pressure ventilation between the inner and outer pipes of the double-walled pipe. When LPG leaks from the inner pipe P5-1 to the outer pipe P5-2, the vaporized LPG is pumped to the outdoor safe area by the fan F1. P12 is the fan air inlet pipe, and P13 is the fan air outlet pipe.

[0050] The pipe clamp P5-3 is installed between the inner pipe P5-1 and the outer pipe P5-2 to provide support and shock absorption;

[0051] Mainly, the P3 and P4 pipelines between the distribution control valve group and the dual-fuel engine A2 should adopt the double-walled pipe P5 design, especially for the LPG pipes P3 and P4 passing through the main engine room and other mechanical spaces, double-layer protection should be provided through the double-walled pipe design to prevent LPG from leaking into the main engine room and causing the entire mechanical space or even the entire ship to be in great danger of explosion.

[0052] The above is just an example of analyzing a dual-fuel system that can use both conventional fuel oil and LPG clean energy according to the actual conditions of the shipyard, but we can actually further flexibly expand it into different configurations as needed:

[0053] The storage tank is currently designed to use 100% propane, but it can also use liquefied petroleum gas (LPG) with other media such as butane, isobutane, propylene, etc. Of course, the saturated vapor pressure of LPG will change after adding other components. The heating and cooling of the heat exchanger in the corresponding system design, the design temperature and pressure of the pipeline, and the setting of the safety valve will all change to a certain extent. This can be calculated to make corresponding system configuration adjustments;

[0054] In addition, the storage tank size, pump parameters, valves, buffer tank size, control valve group form, etc. in the supply pipeline can be adjusted within a certain range according to needs;

[0055] This patent only illustrates an example of a dual-fuel main engine. In fact, multiple main engines can be configured according to the needs of the ship. Multiple branches and control valve groups are added on the basis of the supply pipeline design of this patent to transport LPG to multiple main engines. This depends entirely on the actual needs of the ship. In short, this patent can be flexibly configured and changed according to the ship size, the number and power of main engines, and the fuel composition and cost budget.

[0056] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An LPG dual fuel supply pipeline system, comprising a fuel system and an LPG fuel supply system, characterized in that: The single-fuel engine of the fuel system is changed to a dual-fuel engine suitable for both fuel oil and LPG fuel, and its fuel supply system is changed to a dual-system supply of fuel oil and LPG fuel; The LPG fuel supply system consists of a storage tank delivery pipeline, a high-pressure boost unit, a distribution control valve group, an emergency discharge box, a safety valve release buffer tank, and a double-walled pipe. Its function is to deliver low-ignition-point petroleum gas and keep it in a liquefied state until the engine cylinder nozzle releases vaporization, and then burns to drive the engine piston to do work; The storage tank delivery pipeline is composed of a storage tank, a low-pressure pump, an outlet control valve, a one-way valve, a safety valve, a safety valve release pipe, a remote pressure gauge and a delivery pipeline, and delivers the LPG in the storage tank to the high-pressure boosting unit; The high-pressure boosting unit is composed of a high-pressure pump, a filter, a safety valve, a one-way valve, a three-way valve, a flow control valve, a remote pressure gauge, a remote temperature gauge, a heat exchanger, a nitrogen buffer tank, a delivery pipeline, an ethylene glycol pipeline, a nitrogen pipeline, and a safety valve release pipe. The LPG delivered from the storage tank is further pressurized and filtered to maintain cleanliness. The heat exchanger adjusts the LPG temperature within a specified range and keeps it in a liquid state. The buffer tank can receive the refluxed LPG to provide a buffer storage space. The distribution control valve group is divided into two parts: the gas supply valve group and the return valve group, which are composed of a remote pneumatic control valve, a pressure control valve, a remote pressure gauge, a remote thermometer, a liquid level switch, a supply pipe, a return pipe, an emergency discharge pipe, a gas control valve control instrument pipe, a gas control valve box, and a nitrogen purge pipe. It monitors and controls pipeline transportation, performs emergency discharge in case of leakage, reduces pressure on the return pipe, provides nitrogen purge, and cleans residual LPG in the pipeline; The emergency discharge box includes a discharge box, a liquid level gauge, a discharge valve, and a discharge pipe, which provide a buffer when the distribution control valve group is discharged urgently, collect the liquid present when the LPG is vaporized during discharge, and avoid direct discharge into the atmosphere; The safety valve release buffer tank includes a buffer tank, a liquid level gauge, a relief valve, and a discharge pipe. When the safety valve is discharged in an emergency, it provides a buffer and collects liquid that may exist when LPG vaporizes during discharge to avoid direct discharge into the atmosphere.

2. The LPG dual fuel supply pipeline system according to claim 1, characterized in that: The double-walled pipe is composed of a double-walled pipe inner pipe, a double-walled pipe outer pipe, a double-walled pipe ventilation pipe, a fan and a pipe clamp. The double-walled pipe inner pipe provides LPG for delivery to the dual-fuel engine, and excess fuel refluxes. The outer pipe provides additional protection when the inner pipe leaks, and controls the leakage within the outer pipe. The double-walled pipe ventilation pipe is used for ventilation between the double-walled pipe inner pipe and the outer pipe. When LPG leaks from the inner pipe to the outer pipe, the vaporized LPG is pumped to an outdoor safe area by the fan. The pipe clamp is installed between the inner pipe and the outer pipe to provide support and shock absorption. The pipeline between the distribution control valve group and the dual-fuel engine adopts a double-walled pipe design.

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