阅读说明：本技术 双燃料船舶发动机低压lng供气系统及双燃料船舶 (Low-pressure LNG (liquefied Natural gas) supply system of dual-fuel ship engine and dual-fuel ship ) 是由 曾维武 王廷勇 赵超 董如意 于 2020-05-27 设计创作，主要内容包括：本发明提供一种双燃料船舶发动机低压LNG供气系统,包括LNG储罐、第一三通调节阀、混合气分离器、气化器、混合罐、高压喷射泵、高压缓冲罐、第一调节阀、低压缓冲罐、集液罐、工质泵、第二三通调节阀、废气换热器、气液分离器、第二调节阀、低压喷射泵、第三调节阀、抽风机、加热器和第四调节阀。本发明还提供一种双燃料船舶。(The invention provides a low-pressure LNG gas supply system of a dual-fuel ship engine, which comprises an LNG storage tank, a first three-way regulating valve, a mixed gas separator, a gasifier, a mixing tank, a high-pressure injection pump, a high-pressure buffer tank, a first regulating valve, a low-pressure buffer tank, a liquid collecting tank, a working medium pump, a second three-way regulating valve, a waste gas heat exchanger, a gas-liquid separator, a second regulating valve, a low-pressure injection pump, a third regulating valve, an exhaust fan, a heater and a fourth regulating valve. The invention also provides a dual-fuel ship.)

1. The low-pressure LNG gas supply system of the dual-fuel ship engine is characterized by comprising an LNG storage tank (1), a first three-way regulating valve (2), a mixed gas separator (3), a gasifier (4), a mixing tank (5), a high-pressure injection pump (6), a high-pressure buffer tank (8), a first regulating valve (9), a low-pressure buffer tank (10), a liquid collecting tank (12), a working medium pump (13), a second three-way regulating valve (14), an exhaust gas heat exchanger (15), a gas-liquid separator (16), a second regulating valve (19), a low-pressure injection pump (20), a third regulating valve (21), an exhaust fan (22), a heater (23) and a fourth regulating valve (24);

the bottom outlet of the LNG storage tank (1) is communicated with the inlet of the first three-way regulating valve (2), one outlet of the first three-way regulating valve (2) is communicated with the inner pipeline inlet of the mixed gas separator (3), the other outlet of the first three-way regulating valve (2) is communicated with the inlet of the gasifier (4) after being converged with the inner pipeline outlet of the mixed gas separator (3), the outlet of the gasifier (4) is communicated with the inlet of the mixing tank (5), the outlet of the mixing tank (5) is communicated with the injection suction port of the high-pressure injection pump (6), the outlet of the high-pressure injection pump (6) is communicated with the inner cavity inlet of the mixed gas separator (3), the bottom outlet of the mixed gas separator (3) is communicated with the inlet of the liquid collecting tank (12), and the bottom outlet of the liquid collecting tank (12) is communicated with the inlet of the working medium pump (13), an outlet of the working medium pump (13) is communicated with an inlet of a second three-way regulating valve (14), one outlet of the second three-way regulating valve (14) is communicated with the top of the liquid collecting tank (12), the other outlet of the second three-way regulating valve (14) is communicated with an inlet of the waste gas heat exchanger (15), an outlet of the waste gas heat exchanger (15) is communicated with an inlet of the gas-liquid separator (16), an outlet of the gas-liquid separator (16) is communicated with a working fluid inlet of the high-pressure jet pump (6), and a top outlet of the mixed gas separator (3) is communicated with an inlet of the high-pressure buffer tank (8);

the high-pressure buffer tank (8) is output in three ways, one way is communicated with a ship host, the other way is communicated with the low-pressure buffer tank (10) through the first regulating valve (9), and the other way is communicated with a working fluid inlet of the low-pressure injection pump (20) through the second regulating valve (19);

the low-pressure buffer tank (10) is output in three ways, one way is communicated with a ship auxiliary engine, the other way is communicated with a ship boiler, and the other way is communicated with the mixing tank (5) through the third regulating valve (21);

the top of the LNG storage tank (1) is provided with two outlets, one of the outlets is communicated with the inlet of the heater (23), the other one of the outlets is communicated with the inlet of the exhaust fan (22), and the outlet of the exhaust fan (22) is communicated with the inlet of the heater (23);

the outlet of the heater (23) is divided into four paths, one path is communicated with the injection suction port of the low-pressure injection pump (20), the other path is communicated with the ship boiler through the fourth regulating valve (24), the other path is communicated with the top of the LNG storage tank (1), and the other path is communicated with the bottom of the LNG storage tank (1).

2. The dual fuel marine engine low pressure LNG gas supply system as claimed in claim 1, characterized in that a first pressure sensor (18) is provided at the top of the LNG storage tank (1), the first pressure sensor (18) being used to control the second regulating valve (19) and the fourth regulating valve (24).

3. The low-pressure LNG gas supply system of a dual-fuel marine engine as claimed in claim 1, characterized in that a second pressure sensor (17) is provided at the top of the high-pressure buffer tank (8), the second pressure sensor (17) being used to control the working medium pump (13) and the second three-way regulating valve (14).

4. The dual fuel marine engine low pressure LNG gas supply system as claimed in claim 1, characterized in that a third pressure sensor (11) is provided at the top of the low pressure buffer tank (10), the third pressure sensor (11) being used to control the first regulating valve (9) and the third regulating valve (21).

5. The low-pressure LNG supply system for the dual-fuel marine engine as claimed in claim 1, characterized in that a temperature sensor (7) is arranged on a pipeline between the top outlet of the mixture separator (3) and the inlet of the high-pressure buffer tank (8), and the temperature sensor (7) is used for controlling the first three-way regulating valve (2).

6. The low-pressure LNG supply system of the dual-fuel ship engine as claimed in claim 1, characterized in that the working medium pump (13) is a variable-frequency controlled explosion-proof centrifugal pump.

7. The low-pressure LNG gas supply system of the dual-fuel marine engine as claimed in claim 1, wherein the exhaust fan (22) is a cryogenic explosion-proof exhaust fan.

8. The low pressure LNG gas supply system for a dual fuel marine engine as claimed in claim 1, characterized in that a safety relief valve (54) is further provided at the top of the LNG storage tank (1).

9. The low-pressure LNG gas supply system of a dual-fuel marine engine as claimed in claim 1, wherein the sump tank (12) is used to store an organic liquid, which is an environmentally friendly refrigerant having a condensing temperature at a gas supply pressure lower than a gas supply required temperature and not reacting with LNG.

10. A dual fuel marine vessel comprising the dual fuel marine engine low pressure LNG gas supply system of any one of claims 1 to 9.

Technical Field

The invention relates to the technical field of ships, in particular to a low-pressure LNG gas supply system of a dual-fuel ship engine and a dual-fuel ship with the system.

Background

With the global atmospheric environmental problem becoming worse, the international maritime organization has proposed many emission regulations for ships, and in order to cope with the strict regulations, Liquefied Natural Gas (LNG) as a clean energy source has become an alternative fuel for ships, and accordingly, the development of dual-fuel ship engines has been rapidly progressed in recent years.

At present, the dual-fuel ship engines are divided into two types, one type is a high-pressure dual-fuel engine with the air supply pressure higher than 300bar, and the other type is a low-pressure dual-fuel engine. The low-pressure dual-fuel engine is roughly divided into two types according to the air supply pressure, wherein one type is a 16bar low-pressure dual-fuel engine, the other type is a 6bar dual-fuel engine, in addition, the requirement of the ship dual-fuel boiler on the air supply pressure is relatively low, and the air supply pressure is usually higher than 3 bar. Correspondingly, the gas supply system of the dual-fuel ship is also divided into a high-pressure gas supply system and a low-pressure gas supply system.

The low-pressure gas supply system of the dual-fuel engine is divided into a self-pressurization gas supply system and a conventional low-pressure LNG gas supply system.

The self-pressurization gas supply system returns natural gas generated by LNG gasification to the storage tank, so that the pressure in the storage tank is increased, the LNG is conveyed to the heater to be gasified by using the pressure difference between the inside and the outside of the LNG storage tank, and then the LNG is supplied to gas utilization equipment. The self-pressurization gas supply system needs an LNG storage tank to have high pressure resistance on one hand, is suitable for a small engine with gas supply pressure of 6bar on the other hand, and has the defects of high system manufacturing cost, narrow application range and the like.

The conventional low-pressure LNG gas supply system utilizes a low-temperature immersed pump to pressurize LNG and then conveys the LNG from a storage tank to a heater for gasification, then supplies the LNG to gas utilization equipment, LNG evaporation gas generated in the storage tank is pumped out through a compressor and is pressurized and then is conveyed to the gas utilization equipment, in addition, the compressor sucks the evaporation gas in the LNG storage tank, the evaporation gas is heated by the heater and then returns to the storage tank, and storage tank pressurization and storage tank warming are realized. The immersed pump belongs to low-temperature equipment, has high acquisition cost, is usually arranged in a pump pool inside or outside a storage tank, is in direct contact with low-temperature LNG, and is difficult to overhaul and has large workload because the LNG in the storage tank or the pump pool and in corresponding pipe systems needs to be removed when any fault occurs in the immersed pump and needs to be overhauled; the compressor belongs to intermittent type nature operation equipment, and area is big, and investment cost is higher, and daily maintenance work is more, and work load is big during the fault repair, simultaneously, when using the compressor to carry out LNG storage tank pressure boost and warm cabin operation, because the discharge capacity of compressor is less, so operating time is longer. The immersed pump and the compressor both belong to energy consumption equipment and need to consume a large amount of ship energy, so that the conventional LNG low-pressure gas supply system of the dual-fuel engine has the defects of high investment cost, more maintenance work, difficulty in maintenance, lower working efficiency of part of working conditions, high energy consumption and the like.

Disclosure of Invention

The invention aims to provide a low-pressure LNG (liquefied natural gas) supply system of a dual-fuel ship engine and a dual-fuel ship, aims to overcome the defects in the background art, is suitable for all low-pressure dual-fuel engines, can effectively reduce the investment cost, the maintenance work, the maintenance difficulty and the energy consumption of the LNG supply system, and can improve the efficiency of the gas supply system in different operation modes.

The invention provides a low-pressure LNG gas supply system of a dual-fuel ship engine, which comprises an LNG storage tank, a first three-way regulating valve, a mixed gas separator, a gasifier, a mixing tank, a high-pressure injection pump, a high-pressure buffer tank, a first regulating valve, a low-pressure buffer tank, a liquid collecting tank, a working medium pump, a second three-way regulating valve, a waste gas heat exchanger, a gas-liquid separator, a second regulating valve, a low-pressure injection pump, a third regulating valve, an exhaust fan, a heater and a fourth regulating valve;

the bottom outlet of the LNG storage tank is communicated with the inlet of the first three-way regulating valve, one outlet of the first three-way regulating valve is communicated with the inner pipeline inlet of the mixed gas separator, the other outlet of the first three-way regulating valve is converged with the inner pipeline outlet of the mixed gas separator and then communicated with the inlet of the gasifier, the outlet of the gasifier is communicated with the inlet of the mixing tank, the outlet of the mixing tank is communicated with the injection suction port of the high-pressure injection pump, the outlet of the high-pressure injection pump is communicated with the inner cavity inlet of the mixed gas separator, the bottom outlet of the mixed gas separator is communicated with the inlet of the liquid collecting tank, the bottom outlet of the liquid collecting tank is communicated with the inlet of the working medium pump, the outlet of the working medium pump is communicated with the inlet of the second three-way regulating valve, and one outlet of the second three-way regulating valve is communicated with the top of the, the other outlet of the second three-way regulating valve is communicated with the inlet of the waste gas heat exchanger, the outlet of the waste gas heat exchanger is communicated with the inlet of the gas-liquid separator, the outlet of the gas-liquid separator is communicated with the working fluid inlet of the high-pressure jet pump, and the outlet of the top of the mixed gas separator is communicated with the inlet of the high-pressure buffer tank;

the high-pressure buffer tank is output in three paths, one path is communicated with a ship host, the other path is communicated with the low-pressure buffer tank through the first regulating valve, and the other path is communicated with a working fluid inlet of the low-pressure jet pump through the second regulating valve;

the low-pressure buffer tank is output in three paths, one path is communicated with the auxiliary engine of the ship, the other path is communicated with the boiler of the ship, and the other path is communicated with the mixing tank through the third regulating valve;

the top of the LNG storage tank is provided with two paths of outlets, one path of the outlets is communicated with the inlet of the heater, the other path of the outlets is communicated with the inlet of the exhaust fan, and the outlet of the exhaust fan is communicated with the inlet of the heater;

the outlet of the heater is divided into four paths, one path is communicated with the injection suction port of the low-pressure injection pump, the other path is communicated with the ship boiler through the fourth regulating valve, the other path is communicated with the top of the LNG storage tank, and the other path is communicated with the bottom of the LNG storage tank.

Further, a first pressure sensor is arranged at the top of the LNG storage tank and used for controlling the second regulating valve and the fourth regulating valve.

And furthermore, a second pressure sensor is arranged at the top of the high-pressure buffer tank and used for controlling the working medium pump and the second three-way regulating valve.

And further, a third pressure sensor is arranged at the top of the low-pressure buffer tank and used for controlling the first regulating valve and the third regulating valve.

Furthermore, a temperature sensor is arranged on a pipeline between the top outlet of the mixed gas separator and the inlet of the high-pressure buffer tank, and the temperature sensor is used for controlling the first three-way regulating valve.

Furthermore, the working medium pump is an explosion-proof centrifugal pump controlled by variable frequency.

Further, the exhaust fan is a low-temperature explosion-proof exhaust fan.

Further, a safety relief valve is arranged at the top of the LNG storage tank.

Further, the liquid collecting tank is used for storing organic liquid, and the organic liquid is an environment-friendly refrigerant which has a condensing temperature lower than the gas supply required temperature under the gas supply pressure and does not react with LNG.

The invention also provides a dual-fuel ship, which comprises the low-pressure LNG gas supply system of the engine of the dual-fuel ship.

The low-pressure LNG gas supply system of the dual-fuel ship engine is suitable for all low-pressure engines, and can realize all functions of the low-pressure LNG gas supply system of the conventional dual-fuel ship engine under the condition that the manufacturing requirement of a storage tank is not increased.

The waste heat of the ship waste gas is utilized to heat the low-boiling-point organic matter to generate high-pressure steam, the high-pressure steam flows through the high-pressure injection pump to generate low pressure in the high-pressure injection pump, so that LNG is sucked out of the storage tank, and the pressurization and the conveying of the LNG are realized; meanwhile, the LNG boil-off gas is conveyed by utilizing the pumping effect generated by the high-pressure natural gas flowing through the low-pressure jet pump, and the LNG boil-off gas is supplied to the gas consumption equipment.

Meanwhile, the working medium pump for conveying the organic matters is a normal-temperature pump, and the working medium pump is installed in the atmospheric environment, so that the operation state is easier to monitor, and the maintenance is simpler and more convenient.

Meanwhile, the invention utilizes the exhaust fan to realize the functions of pressurizing the storage tank and warming the storage tank, compared with a compressor used in the conventional scheme, the exhaust fan has larger discharge capacity, and meanwhile, the investment cost, the operation power consumption, the maintenance workload and the fault maintenance difficulty of the exhaust fan are lower.

Drawings

Fig. 1 is a schematic structural diagram of a low-pressure LNG supply system of a dual-fuel ship engine according to a first embodiment of the present invention.

Fig. 2 is a schematic structural diagram of a low-pressure LNG supply system of a dual-fuel ship engine according to a second embodiment of the present invention.

Detailed Description

The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.