CN213065523U

CN213065523U - Marine liquefied natural gas low pressure fuel supply system

Info

Publication number: CN213065523U
Application number: CN202021710496.9U
Authority: CN
Inventors: 周伟; 李文伟; 李华诚
Original assignee: Zhejiang Power Co Ltd
Current assignee: Zhejiang Power Co Ltd
Priority date: 2020-08-17
Filing date: 2020-08-17
Publication date: 2021-04-27
Anticipated expiration: 2030-08-17

Abstract

The utility model relates to a natural gas power ship fuel supply system technical field specifically is a marine liquefied natural gas low pressure fuel supply system, including LNG storage tank, filling system, fuel evaporation heating unit and pressure control, ventilation system, nitrogen gas purging system, ventilation system, gas and fire detection system, control system. The fuel evaporation heating unit is provided with an LNG evaporator and a fuel gas heater, a fuel pipeline behind the LNG evaporator is provided with a regulating valve for regulating fuel flow, and a supercharged natural gas pipeline is provided with a regulating valve for regulating natural gas flow for supercharging. LNG flow that gets into in the LNG evaporimeter can be adjusted according to user's gas consumption, carries out accurate control to the pressure in the storage tank, and storage tank internal pressure maintains in reasonable interval, provides the gas that satisfies low pressure engine and other user's air feed pressure and temperature requirement.

Description

Marine liquefied natural gas low pressure fuel supply system

Technical Field

The utility model relates to a natural gas power ship fuel supply system technical field specifically is a marine liquefied natural gas low pressure fuel supply system.

Background

The International Maritime Organization (IMO) stipulates that the sulfur content of ship fuel must be less than 0.5% since 2020. The main measures for reducing the sulfur emission of ships at present are to use low-sulfur fuel oil, install a desulfurizing device additionally and use clean energy such as liquefied natural gas and the like. The liquefied natural gas is used as clean energy, has no sulfide emission, can greatly reduce the emission of pollutants such as oil stain, nitrogen oxide, carbon oxide, particulate matters and the like, and is considered as an important fuel for fundamentally reducing the ship pollution.

When the dual fuel engine using natural gas is a four-stroke medium speed internal combustion engine, the supply pressure of the gas does not exceed 10bar, and the fuel supply system is generally of the self-supercharging type. For a conventional self-pressurization fuel supply system, Liquefied Natural Gas (LNG) in an LNG storage tank automatically flows into an LNG vaporizer due to the pressure in the tank, is vaporized into low-pressure natural gas, is heated by a gas heater to reach the gas temperature, and then can be delivered to users. When the pressure in the storage tank is lower than a set value, the LNG enters the self-pressurization evaporator, and the gasified low-temperature natural gas flows back to the storage tank to pressurize the storage tank. The conventional self-pressurization fuel supply system is provided with an LNG evaporator and a fuel gas heater, and the self-pressurization evaporator is also needed, so that the LNG flow can not be adjusted according to the consumption of a user, the fuel gas with stable pressure is provided, and the pressure in the storage tank can not be controlled in real time.

SUMMERY OF THE UTILITY MODEL

Technical problem

An object of the utility model is to provide a supply system for natural gas power ship provides low pressure fuel can save LNG fuel, filling and gasification heating, provides the gas that satisfies low pressure engine and other users' air feed pressure and temperature requirement to control the pressure in the LNG storage tank.

Technical solution

To above problem, the utility model provides a marine liquefied natural gas fuel low pressure supply system, include: the filling system mainly comprises a filling pipeline and a gas return pipeline and is mainly used for filling LNG to the storage tank. The filling pipeline is sequentially connected with the double-wall pipe from the filling station to the joint of the storage tank and then connected into the filling spray pipe in the tank. The gas return pipeline is connected with the gas phase space on the top of the tank and is sent to the filling station after reaching the joint of the storage tank.

The LNG storage tank, the storage tank be the double-deck jar of vacuum insulation. The storage tank comprises a monitoring instrument and a pipeline interface, and the monitoring instrument comprises liquid level monitoring, liquid level alarming, pressure monitoring, pressure alarming and temperature monitoring. The end of the storage tank is provided with a storage tank joint, and the joint comprises all equipment, pipelines and meters connected with the tank.

A fuel evaporation heating unit configured to: the LNG fuel pipeline connects gradually LNG storage tank bottom, sixth stop valve, LNG evaporimeter, second governing valve, gas heater, each user's branch pipeline, and every user's branch pipeline sets up manual valve and control valve valves. The boil-off gas fuel pipeline is connected with the fuel pipeline behind LNG storage tank top, fifth stop valve, ninth stop valve and the evaporimeter in proper order. The booster natural gas pipeline is led out from a gas supply pipeline behind the LNG evaporator and is sequentially connected with a first regulating valve and a fifth stop valve to the top of the LNG storage tank.

The stop valves are automatic control valves, wherein the first stop valve, the second stop valve, the third stop valve, the fourth stop valve, the fifth stop valve and the sixth stop valve are emergency stop valves.

The gas system is also provided with a ventilation system, a nitrogen purging system, a ventilation system, a gas and fire detection system and a control system, so that the integrity of the system is ensured.

The utility model provides a pair of marine liquefied natural gas low pressure fuel supply system, beneficial effect lies in: the LNG evaporator, the fuel gas heater and the self-pressurization evaporator configured in the conventional self-pressurization fuel gas system are optimized into the LNG evaporator and the fuel gas heater, so that the construction cost is saved. LNG flow that gets into in the LNG evaporimeter can be adjusted according to user's gas consumption, carries out accurate control to the pressure in the storage tank, and storage tank internal pressure maintains in reasonable interval, provides the gas that satisfies low pressure engine and other user's air feed pressure and temperature requirement.

Drawings

Fig. 1 is a flow chart of a low-pressure supply system for liquefied natural gas fuel for ships according to the present invention.

In the figure: 1. a filling station; 2. an LNG storage tank; 3. an LNG vaporizer; 4. a gas heater; 5. a tank joint location; 6. a venting system; 7. a nitrogen purge system; 8. a ventilation system; 9. gas and fire detection systems; 10. a control system; 101. a first shut-off valve; 102. a second stop valve; 103. a third stop valve; 104. a fourth stop valve; 105. a fifth stop valve; 106. a sixth stop valve of the storage tank; 107. a seventh stop valve; 108. an eighth stop valve; 109. a ninth cut-off valve; 110. a main engine gas manual valve and control valve group; 111. the auxiliary gas manual valve and control valve group; 112. a boiler fuel gas manual valve and control valve set; 201. a first regulating valve; 202. a second regulator valve.

Detailed Description

The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

As shown in fig. 1, a low-pressure supply system for liquefied natural gas fuel for a ship mainly includes:

the filling system adopts a filling station 1, and pipelines, valves and instruments in the filling station 1 are arranged by adopting a prying block. The filling line filling station is connected to the storage tank joint 5 and is divided into a top filling line and a bottom filling line. The top filling line connects the third stop valve 103, the fifth stop valve 105 and the top of the tank 2. The bottom filling line connects the fourth and sixth shut-off valves 104, 106 with the bottom of the reservoir 2. The air return line is connected with the top of the storage tank 2 and the seventh stop valve 107 in sequence, and is connected with the second stop valve 102 in the filling station 1 after being discharged from the storage tank joint 5.

The fuel sources are divided into LNG fuel lines and boil-off gas fuel lines. The LNG fuel pipeline is connected to the bottom of the storage tank 2, the sixth stop valve 106, the LNG vaporizer 3, the second regulating valve 202, and the gas heater 4 in sequence, and then is divided into 3 branches, i.e., a main engine gas supply pipeline, an auxiliary engine gas supply pipeline, and a boiler gas supply pipeline. The main machine fuel gas supply pipeline is provided with a manual valve and control valve set 110, the auxiliary machine fuel gas supply pipeline is provided with a manual valve and control valve set 111, and the boiler fuel gas supply pipeline is provided with a manual valve and control valve set 112. The evaporation gas fuel pipeline is connected with the top of the storage tank 2, the fifth stop valve 105, the ninth stop valve 109 and the fuel pipeline behind the evaporator in sequence. The pressurized natural gas pipeline is led out from a gas supply pipeline behind the LNG evaporator 3 and is sequentially connected with the first regulating valve 201 and the fifth stop valve 105 to the top of the LNG storage tank 2.

The ventilation system 6 comprises a safety valve and a ventilation mast which are arranged on each pipeline. The following positions are provided with a safety valve or a stop valve for discharging: a filling line before and after the first stop valve 101, a discharge line provided at the top of the storage tank 2, an LNG fuel line between the LNG vaporizer 3 and the gas heater 4, a vaporized gas line between the fifth stop valve 105 and the ninth stop valve 109, and a fuel supply line after the gas heater 4. Each vent line is connected to a vent mast. The top of the ventilating mast is provided with a ventilating head, and the bottom of the ventilating mast is provided with a liquid level switch for monitoring liquid level accumulation.

In addition to the above, the low pressure supply system comprises a nitrogen purge system 7, a ventilation system 8, a gas and fire detection system 9, and a control system 10.

The technology and the principle of the utility model are as follows:

the fuel gas supply system mainly comprises an LNG storage tank, a filling system, a fuel evaporation heating unit, a pressure control system, a ventilation system, a nitrogen purging system, a ventilation system, a gas and fire detection system and a control system. The LNG storage tank is a vacuum heat insulation double-layer tank, and is provided with liquid level monitoring and liquid level alarming, pressure monitoring and pressure alarming and temperature monitoring.

The filling system comprises a filling pipeline and a gas return pipeline. After the filling pipeline enters the joint of the storage tank, the top filling pipeline and the bottom filling pipeline are separated. LNG can enter a nozzle at the top of the storage tank through a top filling pipeline, is sprayed into the tank, and can be filled through a bottom filling pipeline. The top-fill pre-cools the reservoir prior to filling and is used to control the pressure in the reservoir during filling. After the pre-cooling is completed, bottom-up priming may be used. And a stop valve and a safety valve at the interface of the filling pipeline and the air return pipeline are arranged in the filling station. The safety valve is used for protecting the filling pipeline from overpressure. The filling pipeline is arranged outside the ground pressure gauge, and a pressure transmitter is needed to monitor the pressure in the filling pipeline. When the filling and air returning pipelines are in a closed area, a vacuum heat insulation double-wall pipe form is adopted. And a gas detector is arranged in the annular space to detect gas leakage, and a pressure transmitter and a vacuum pump are arranged.

The fuel evaporation heating unit comprises an LNG evaporator and a fuel gas heater. The LNG evaporator gasifies LNG, and the gasified low-temperature natural gas mainly goes to a gas heater as fuel and can also pressurize the storage tank. When the low-temperature natural gas is used as fuel, the temperature of the low-temperature natural gas is further increased by the heater to meet the requirements of users.

After the LNG storage tank is filled, the pressure in the tank needs to be increased to a set value. And opening the sixth stop valve 106 and the fifth stop valve 105, opening the first regulating valve 201 to a proper opening degree, allowing the LNG to enter the LNG evaporator from the bottom of the storage tank, and returning the low-temperature natural gas to the storage tank to increase the pressure in the tank. After the pressure rises to the set value, the fifth stop valve 105 is closed and LNG is ready to be delivered to the gas heater. The second regulating valve 202 is opened, the first regulating valve 201 is closed, and the main valve of each user can be opened after the gas pressure and the temperature after the heater meet the requirements.

As LNG is supplied to each customer, the pressure in the LNG tank also decreases, and the tank also needs to be pressurized. The first regulating valve 201 is interlocked with the tank internal pressure, and the first regulating valve 201 is opened when the tank internal pressure is lower than a set value.

When the user's gas consumption changes, the pressure monitored by the pressure sensor on the gas line behind the gas heater, which is interlocked with the second regulating valve 202, changes accordingly. When the air consumption is increased, the pressure sensor detects that the pressure value is reduced, and the opening degree of the second regulating valve 202 is automatically increased; when the air consumption is reduced, the pressure sensor detects that the pressure value is increased, and the opening degree of the second regulating valve 202 is automatically reduced.

When the user does not use gas or the gas consumption is very small, the heat leakage of the LNG storage tank may cause a natural increase in the pressure in the tank. If the pressure in the storage tank rises to a high set point, the sixth shutoff valve 106 is closed and the supply of LNG to the LNG vaporizer is stopped. By opening the fifth and ninth cut-off valves 105 and 109, the vapor in the tank will be led directly to each user through the heater, and the pressure in the tank will be rapidly reduced. The gas fired heater receives boil-off gas from the LNG vaporizer outlet or the top of the storage tank depending on the pressure level in the tank.

And (5) purging the system with nitrogen. In order to avoid explosive mixture of fuel gas and air in the fuel gas system, nitrogen is filled before starting and after stopping the system. The nitrogen is connected to a fuel gas supply system at the joint of the filling system and the storage tank, and each nitrogen purging port is provided with a control valve for controlling. The nitrogen manifold is provided with a pressure sensor to monitor the nitrogen pressure.

A ventilation system. The storage tank joint is provided with a suction type mechanical ventilation system which comprises an air inlet pipeline and an air outlet pipeline with a fan. 2 sets of fans were placed in the outlet duct to deliver any leaking gas to the safety area, with ventilation ensuring 30 air changes per hour.

Gas and fire detection systems. A gas detector is installed at the joint of the filling station and the storage tank. If gas leakage or fire alarm is activated, the gas system will automatically be switched off urgently.

The operation of the gas system is controlled by a 2LC based control system. The 2LC cabinet comprises three independent 2LC units, the process control function is realized by a redundant process 2LC, and the emergency cut-off function is realized by a safety 2 LC. In addition, an operation station is arranged to monitor the operation of the gas system, give control commands and adjust set points. Two operation stations are arranged on the ship and are positioned in a driving cab and a cabin control room.

Claims

1. A marine lng low pressure fuel supply system comprising: filling station (1), muffler line, pressure boost natural gas pipeline, filling pipeline, valve, instrument adopt the sled piece to arrange, LNG fuel line and evaporation gas fuel line, its characterized in that: the filling pipeline is connected with a joint (5) of the storage tank, the filling pipeline is divided into a top filling pipeline and a bottom filling pipeline, the top filling pipeline is respectively connected with a third stop valve (103), a fifth stop valve (105) and the top of the storage tank (2), the bottom filling pipeline is respectively connected with a fourth stop valve (104), a sixth stop valve (106) and the bottom of the storage tank (2), the gas return pipeline is sequentially connected with the top of the storage tank (2) and a seventh stop valve (107), the rear end of the joint (5) of the storage tank is connected with a second stop valve (102) in the filling station (1), the LNG fuel pipeline is sequentially connected with the bottom of the storage tank (2), the sixth stop valve (106), the LNG evaporator (3), the second regulating valve (202) and the gas heater (4), and then is divided into 3 branches, namely a main machine gas supply pipeline, an auxiliary machine gas supply pipeline and a boiler gas supply pipeline, the evaporation gas fuel pipeline is connected with the top of the storage tank (2), the fifth stop valve (105), the ninth stop valve (109) and a fuel pipeline behind the evaporator in sequence, an air supply pipeline of the pressurization natural gas pipeline behind the LNG evaporator (3) is led out, and the first regulating valve (201) and the fifth stop valve (105) are connected with the top of the LNG storage tank (2) in sequence.

2. The marine liquefied natural gas low-pressure fuel supply system according to claim 1, wherein: after the filling pipeline is connected to a joint of the storage tank, the filling pipeline is divided into a top filling pipeline and a bottom filling pipeline, the top filling pipeline comprises a part of pipe section of a fifth stop valve (105), and can be used as a pipeline for circulation of evaporation gas after filling, and the part of pipe section of a sixth stop valve (106) comprises a part of pipe section of the bottom filling pipeline can be used as a pipeline for circulation of LNG fuel after filling.

3. The marine liquefied natural gas low-pressure fuel supply system according to claim 1, wherein: the air supply pipeline behind the LNG evaporator leads out a supercharged natural gas pipeline, the supercharged natural gas pipeline is provided with a first regulating valve (201), and the first regulating valve (201) is interlocked with a pressure signal in the tank.

4. The marine liquefied natural gas low-pressure fuel supply system according to claim 1, wherein: an air supply line behind the LNG vaporizer leads into a boil-off gas fuel line, which is provided with a ninth shut-off valve (109).

5. The marine liquefied natural gas low-pressure fuel supply system according to claim 1, wherein: and a second regulating valve (202) is arranged on the fuel pipeline behind the LNG evaporator, and the second regulating valve (202) is interlocked with the pressure signal of the fuel pipeline behind the gas heater.