KR101334002B1 - A treatment system of liquefied natural gas - Google Patents

Abstract

The present invention relates to an LNG processing system. The LNG processing system comprises an LNG supply line which is connected to users from an LNG storage tank; a pump which is in the middle of the LNG supply line and pressurizes LNG discharged from the LNG storage tank; evaporative gas compressors which pressurize evaporative gas generated from the LNG storage tank in stages; an LNG heat exchanger which is placed in the LNG supply line between the pump and users and exchanges heat of the evaporative gas from the LNG storage tank with pressurized LNG; an evaporative gas heat exchanger which exchanges heat of the evaporative gas pressurized in the evaporative gas compressors with the evaporative gas generated from the LNG storage tank; and a Joule-Thomson valve which decompresses the heat exchanged evaporative gas with the LNG discharged from the LNG heat exchanger. The LNG supplied through the LNG supply line and decompressed evaporative gases are supplied to the pump. The LNG processing system supplies low pressure LNG to the users by compressing the evaporative gas generated from the LNG storage tank due to heat penetration in stages or the system supplies liquefied evaporative gas to the users with high pressure through the pump after compression in stages using the Joule-Thomson valve. The LNG processing system supplies the LNG to the users with high pressure by compressing the LNG in stages so that the system prevents the waste of the evaporative gas.

Description

LNG Treatment System {A Treatment System of Liquefied Natural Gas}

The present invention relates to an LNG processing system.

A ship is a means of transporting large quantities of minerals, crude oil, natural gas, or more than a thousand containers. It is made of steel and buoyant to float on the water surface. ≪ / RTI >

Such a vessel generates thrust by driving the engine. In this case, the engine uses gasoline or diesel to move the piston so that the crankshaft is rotated by the reciprocating motion of the piston, so that the shaft connected to the crankshaft is rotated to drive the propeller It was common.

In recent years, however, LNG fuel supply systems for driving an engine using LNG as a fuel have been used in an LNG carrier carrying Liquefied Natural Gas (LNG) It is also applied to other ships.

Generally, it is known that LNG is a clean fuel and its reserves are more abundant than petroleum, and its usage is rapidly increasing as mining and transfer technology develops. This LNG is generally stored in a liquid state at a temperature of -162 ° C. or below under 1 atm. The volume of liquefied methane is about one sixth of the volume of methane in a gaseous state, The specific gravity is 0.42, which is about one half of that of crude oil.

However, the temperature and pressure required to drive the engine may be different from the state of the LNG stored in the tank. Therefore, in recent years, research and development have been made on the technology of controlling the temperature and pressure of the LNG stored in the liquid state and supplying the engine to the engine.

In addition, when LNG is stored in the liquid phase, as the heat penetrates into the tank, some LNG is vaporized to generate boil off gas (BOG). In the past, the boil off gas (BOG) was lowered to remove the risk of damage to the tank. It was simply discharged to the outside. Recently, however, the necessity of development has gradually increased for the utilization of re-liquefaction of the boil-off gas generated in the tank and supply to the engine.

The present invention was created to solve the problems of the prior art as described above, an object of the present invention is to reduce the fuel by utilizing the boil-off gas by supplying the compressed and liquefied boil-off gas to the LNG demand by using a Thompson valve to give It is to provide a LNG processing system that can be.

An LNG processing system according to an embodiment of the present invention includes an LNG supply line connected from an LNG storage tank to an LNG consumer site; A pump provided on the LNG supply line for pressurizing the LNG discharged from the LNG storage tank; An evaporative gas compressor for pressurizing the evaporation gas generated in the LNG storage tank and provided in a plurality of stages to pressurize the evaporation gas at multiple stages; An LNG heat exchanger provided on the LNG supply line between the LNG consumer and the pump for heat-exchanging the LNG supplied from the pump with the pressurized evaporated gas; An evaporative gas heat exchanger installed upstream of the evaporative gas compressor for exchanging heat between the evaporated gas generated in the LNG storage tank and the evaporated gas pressurized in the evaporative gas compressor; And a Joule Thompson valve for reducing the boil-off gas heat-exchanged with the LNG discharged from the LNG heat-exchanger, wherein the LNG and the reduced-pressure boil-off gas through the LNG supply line are supplied to the pump.

Here, the present invention is characterized in that it further comprises a high-pressure boil-off gas supply line connected from the boil-off gas compressor to the LNG demand destination.

In addition, the plurality of the boil-off gas compressor pressurizes the boil-off gas to 200bar to 400bar, characterized in that the pressurized boil-off gas is supplied to the LNG demand destination through the high-pressure boil-off gas supply line.

In addition, the present invention is provided in the LNG supply line downstream of the Joule Thompson valve and between the LNG storage tank and the pump, LNG is introduced from the LNG storage tank, the boil-off gas flows from the Joule Thompson valve to provide LNG Characterized in that it further comprises a temporary storage tank for discharging to the pump.

In addition, the temporary storage tank, characterized in that the boil-off gas discharged from the Joule Thompson valve is mixed with the LNG discharged from the LNG storage tank and liquefied and supplied to the pump.

The present invention further includes an evaporation gas supply line connected from the LNG storage tank to the evaporative gas heat exchanger, the evaporative gas compressor, the evaporative gas heat exchanger, the LNG heat exchanger, the Joule Thompson valve, and the temporary storage tank. Characterized in that.

In addition, the LNG demand destination connected to the LNG supply line is characterized in that the high pressure LNG demand destination.

In addition, the present invention is characterized in that it further comprises a low pressure boil-off gas supply line is connected between the plurality of boil-off gas compressor on the boil-off gas supply line and supplying the pressurized boil-off gas to low pressure LNG demand.

LNG processing system according to the present invention, by compressing the evaporation gas generated in the LNG storage tank by external heat penetration in multiple stages to supply to low pressure LNG demand, or by reducing the pressure by using a Thompson valve to give the boiled gas liquefied after the multi-stage compression The pump may be supplied to the high pressure LNG source through a pump, or may be compressed to the high pressure LNG source by multistage compression, thereby preventing the boil-off gas from being discarded.

1 is a conceptual diagram of a conventional LNG processing system.
2 is a conceptual diagram of an LNG processing system according to an embodiment of the present invention.
3 is a cross-sectional view of the LNG storage tank in the LNG processing system according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a conceptual diagram of a conventional LNG processing system.

As shown in FIG. 1, the conventional LNG processing system 1 includes an LNG storage tank 10, an LNG demand destination 20, a pump 30, and an LNG heat exchanger 40. In this case, the LNG demand source 20 may be a gas fuel engine that is a high pressure LNG source or a dual fuel engine that is a low pressure LNG source, and the pump 30 may include a boosting pump 31 and a high pressure pump 32. It can be configured to include.

Hereinafter, the LNG may be used to encompass not only a liquid state NG but also a NG state such as a supercritical state for the sake of convenience. The evaporation gas may include not only gaseous state evaporation gas but also liquefied evaporation gas Can be used as a meaning.

The conventional LNG processing system 1 extracts liquid LNG from the LNG storage tank 10 and pressurizes it through the boosting pump 31 and the high pressure pump 32, and then, in the LNG heat exchanger 40, to glycol water or the like. The method of heating and supplying to the LNG demand destination 20 was used.

In this case, however, only the liquid LNG stored in the LNG storage tank 10 is used. Therefore, the evaporation gas naturally generated in the LNG storage tank 10 by the external heat penetration is used to lower the internal pressure of the LNG storage tank 10 And discharged to the outside along the evaporation gas discharge line (16). Therefore, the conventional LNG processing system 1 does not utilize any boil-off gas, there is a problem that energy waste occurs.

2 is a conceptual diagram of a LNG processing system according to an embodiment of the present invention, Figure 3 is a cross-sectional view of the LNG storage tank in the LNG processing system according to an embodiment of the present invention.

As shown in FIG. 2, the LNG processing system 2 according to an embodiment of the present invention includes an LNG storage tank 10, a high pressure LNG demand destination 20a, a low pressure LNG demand destination 20b, and a pump 31, 32. ), The LNG heat exchanger 40, the boil-off gas compressor 50, the boil-off gas heat exchanger 60, Joule Thompson valve 70, the temporary storage tank (80). In one embodiment of the present invention, the LNG demand source 20, the pumps 31 and 32, and the LNG heat exchanger 40, etc., use the same reference numerals for convenience of each configuration and convenience in the conventional LNG processing system 1, but It does not refer to the same configuration.

The LNG storage tank 10 stores LNG to be supplied to the LNG demanders 20a and 20b. The LNG storage tank 10 must store the LNG in a liquid state, and the LNG storage tank 10 may have a pressure tank form.

As shown in FIG. 3, the LNG storage tank 10 includes an outer tank 11, an inner tank 12, and an insulator 13. The outer tank 11 is formed as an outer wall of the LNG storage tank 10, and may be formed of steel, and may have a polygonal cross section.

The tanks 12 are provided inside the tanks 11 and can be supported and supported inside the tanks 11 by means of a support 14. At this time, the support 14 may be provided at the lower end of the inner tank 12, and may be provided at the side of the inner tank 12 in order to suppress the lateral movement of the inner tank 12. [

The bath tank 12 may be made of stainless steel and designed to withstand a pressure of 5 bar to 10 bar (for example 6 bar). The reason why the inner tank 12 is designed to withstand such a constant pressure is that the inner pressure of the inner tank 12 can be raised as the LNG provided in the inner tank 12 is evaporated to generate the evaporation gas Because.

A baffle 15 may be provided in the inner tank 12. [ The baffle 15 means a plate in the form of a lattice and the baffle 15 is installed so that the pressure inside the tank 12 can be evenly distributed to prevent the tank 12 from being subjected to concentrated pressure .

The heat insulating portion 13 is provided between the inner tank 12 and the outer tank 11 and can prevent the external heat energy from being transmitted to the inner tank 12. [ At this time, the heat insulating portion 13 may be in a vacuum state. By forming the adiabatic portion 13 in a vacuum, the LNG storage tank 10 can more efficiently withstand higher pressures as compared to a conventional tank. For example, the LNG storage tank 10 may sustain a pressure of 5 to 20 bar through the vacuum insulation 13.

As such, the present embodiment uses a pressure tank type LNG storage tank 10 having a vacuum insulator 13 between the outer tank 11 and the inner tank 12 to minimize the generation of boil-off gas. In addition, even if the internal pressure rises, it is possible to prevent problems such as the LNG storage tank 10 from being broken.

In addition, the present embodiment, by supplying the boil-off gas generated in the LNG storage tank 10 to the boil-off gas compressor 50 to utilize the heating of the LNG, or pressurized, liquefied, reduced pressure pumps (31, 32) It is possible to efficiently use the boil-off gas by supplying the oil to the fuel of the high pressure LNG demand destination 20a.

The LNG demanders 20a and 20b are driven through the LNG supplied from the LNG storage tank 10 to generate power. The LNG consumers 20a and 20b include a high-pressure LNG consumer 20a and a low-pressure LNG consumer 20b. The high-pressure LNG consumer 20a may be a gas fuel engine and the low-pressure LNG consumer 20b may include a dual- Lt; / RTI >

As a piston (not shown) inside the cylinder (not shown) reciprocates by the combustion of the LNG, the LNG demanders 20a and 20b rotate the crankshaft (not shown) connected to the piston, The shaft (not shown) to be connected can be rotated. Therefore, as the propeller (not shown) connected to the shaft rotates when the LNG consumers 20a and 20b are driven, the hull can advance or backward.

Of course, in this embodiment, the LNG demanders 20a and 20b may be LNG demanders for driving the propeller, but they may be LNG demanders for power generation or LNG demanders for generating other power. That is, the present embodiment does not specifically limit the types of the LNG demanders 20a and 20b. However, the LNG demanders 20a and 20b may be internal combustion engines that generate driving force by combustion of the LNG.

The high pressure LNG demand destination 20a generates power by receiving LNG in a supercritical state (30 ° C. to 60 ° C., 200 bar to 400 bar) from the LNG heat exchanger 40, while the low pressure LNG demand destination 20 b is an evaporated gas. The driving force can be obtained by receiving the boil-off gas pressurized by the compressor 50. The state of the LNG or the evaporation gas supplied to the high-pressure LNG consumer 20a and the low-pressure LNG consumer 20b may vary depending on the state required by the LNG consumers 20a and 20b.

In the case of low-pressure LNG demand site (20b), it may be a dual-fuel LNG demand place where LNG and oil are not mixed and LNG or oil is selectively supplied. This is to prevent the two materials having different combustion temperatures from being mixed and supplied, thereby preventing the efficiency of the low pressure LNG demand destination 20b from falling.

An LNG supply line 21 for delivering LNG may be installed between the LNG storage tank 10 and the high pressure LNG demand destination 20a, and the LNG supply line 21 may include pumps 31 and 32 and an LNG heat exchanger 40. ) May be provided so that LNG can be supplied to the high pressure LNG demand destination 20a.

At this time, the fuel supply valve (not shown) is installed in the LNG supply line 21, the supply amount of LNG can be adjusted according to the opening degree of the fuel supply valve.

The pumps 31 and 32 are provided on the LNG supply line 21 and pressurize the LNG discharged from the LNG storage tank 10. The pumps 31, 32 may include a boosting pump 31 and a high pressure pump 32.

The boosting pump 31 may be provided on the LNG supply line 21 between the LNG storage tank 10 and the high pressure pump 32, so that a sufficient amount of LNG is supplied to the high pressure pump 32 to supply the high pressure pump. (32) to prevent cavitation.

Also, the boosting pump 31 can pressurize the LNG from the LNG storage tank 10 to a pressure of several to several tens of bar, and the LNG through the boosting pump 31 can be pressurized to 1 to 25 bar.

The LNG stored in the LNG storage tank 10 is in a liquid state. At this time, the boosting pump 31 may pressurize the LNG discharged from the LNG storage tank 10 to slightly increase the pressure and the temperature, and the LNG pressurized by the boosting pump 31 may still be in a liquid state.

The high pressure pump 32 pressurizes the LNG discharged from the LNG storage tank 10 to a high pressure so as to be supplied to the high pressure LNG demand destination 20a. The LNG is discharged at a pressure of about 10 bar from the LNG storage tank 10 and then pressurized primarily by the boosting pump 31, and the high pressure pump 32 receives the liquid LNG pressurized by the boosting pump 31. It is pressurized secondary and it supplies to the LNG heat exchanger 40.

At this time, the high pressure pump 32 pressurizes the LNG to the high pressure LNG demand destination 20a by supplying the pressure required by the high pressure LNG demand destination 20a, for example, 200 bar to 400 bar, so that the high pressure LNG demand destination 20a is driven through the LNG. Can be produced.

The high pressure pump 32 is capable of phase-changing the LNG discharged from the boosting pump 31 to a supercritical state having a higher temperature and a higher pressure than the LNG at a high pressure have. At this time, the temperature of the supercritical LNG may be lower than -20 ° C, which is relatively higher than the critical temperature.

Or the high-pressure pump 32 can pressurize the LNG in a liquid state to a super-cooled liquid state by pressurizing it with a high pressure. Here, the supercooled liquid state means that the pressure of the LNG is higher than the critical pressure and the temperature is lower than the critical temperature.

Specifically, the high-pressure pump 32 pressurizes the liquid LNG discharged from the boosting pump 31 to a high pressure of 200 to 400 bar so that the temperature of the LNG becomes lower than the critical temperature, Phase change. Here, the temperature of the LNG in the subcooled liquid state may be -140 캜 to -60 캜, which is relatively lower than the critical temperature.

The evaporative gas compressor (50) pressurizes the evaporative gas generated in the LNG storage tank (10). The evaporative gas compressor 50 can pressurize the evaporated gas generated in the LNG storage tank 10 and discharged at a pressure of about 10 bar to supply the LNG heat exchanger 40 to be described later.

The plurality of evaporation gas compressors (50) can pressurize the evaporation gas at multiple stages. For example, the evaporation gas compressor 50 is provided with five so that the boil-off gas is pressurized by five stages, and the boil-off gas pressurized by the second stage in the boil-off gas compressor 50 is low-pressure LNG through the low-pressure boil-off gas supply line 23. It can be supplied to the demand destination 20b.

The low pressure boil-off gas supply line 23 may be connected between the plurality of boil-off gas compressors 50 on the boil-off gas supply line 22 and supply pressurized boil-off gas to the low pressure LNG demand destination 20b. For example, when five boil-off gas compressors 50 are provided, the low pressure boil-off gas supply line 23 may be connected to the second boil-off gas compressor 50 based on the flow of the boil-off gas. Therefore, the boil-off gas pressurized by the second boil-off gas compressor 50 may be supplied branched after the low-pressure LNG demand source 20b or the third boil-off gas compressor 50, respectively.

In addition, the five-stage pressurized boil-off gas may be pressurized to 200 bar to 400 bar, and may be supplied to the high-pressure LNG demand destination 20a through the high-pressure boil-off gas supply line 24. One end of the high pressure boil-off gas supply line 24 is connected to the outlet of the boil-off gas compressor 50 and is connected to the high pressure LNG demand destination 20a. Here, the boil-off gas supplied to the high-pressure boil-off gas supply line 24 and the LNG supplied to the LNG supply line 21 may be mixed and supplied to the high-pressure LNG demand destination 20a. To this end, a mixer 20C may be provided upstream of the high pressure LNG demand destination 20a. The mixer 20C may be provided on the LNG supply line 21, and the other end of the high pressure boil-off gas supply line 24 may be connected.

On the connection point of the boil-off gas supply line 22 and the low-pressure boil-off gas supply line 23 and on the high-pressure boil-off gas supply line 24, an boil-off gas supply valve (not shown) may be provided, and the boil-off gas supply valve may have a low pressure. The flow rate of the boil-off gas supplied to the LNG demand source 20b or the flow rate of the boil-off gas supplied to the LNG heat exchanger 40 through the third boil-off gas compressor 50 and the flow rate of the boil-off gas supplied to the high pressure LNG demand source 20a. It can control and may be a three-way valve.

Between the plurality of evaporative gas compressors 50, an evaporative gas cooler (not shown) may be provided. When the evaporation gas is pressurized by the evaporation gas compressor 50, since the temperature may also rise with the pressure increase, this embodiment can lower the temperature of the evaporation gas again by using the evaporation gas cooler. The evaporative gas cooler may be installed in the same number as the evaporative gas compressor 50, and each evaporative gas cooler may be provided downstream of each evaporative gas compressor 50.

The evaporation gas compressor 50 pressurizes the evaporation gas in order to increase the liquefaction efficiency of the evaporation gas. The boil-off gas has an elevated boiling point when the pressure rises, which means that it can be liquefied even at relatively high temperatures. Therefore, this embodiment can increase the pressure of the evaporation gas to the evaporation gas compressor 50, so that the evaporation gas can be easily liquefied. At this time, the boil-off gas discharged from the boil-off gas compressor 50 located upstream of the boil-off gas heat exchanger 60 may have a pressure of 30 to 60 bar (for example, 45 bar). However, the evaporated gas discharged from the evaporative gas compressor 50 located upstream of the low-pressure evaporative gas supply line 23 can have a pressure required by the low-pressure LNG consumer 20b and can be supplied to the low-pressure LNG consumer 20b May be between 1 and 50 bar.

The boil-off gas heat exchanger 60 is configured to heat-exchange the boil-off gas so as to increase the efficiency of the boil-off gas compressor 50. The boil-off gas heat exchanger 60 is installed in the boil-off gas supply line 22 upstream of the boil-off gas compressor 50 to store LNG. The boil-off gas generated in the tank 10 is exchanged with the boil-off gas pressurized by the boil-off gas compressor 50.

That is, the evaporated gas discharged from the LNG storage tank 10 is pressurized in multiple stages in the evaporative gas compressor 50 and is recovered to the evaporative gas heat exchanger 60, and the evaporated gas newly supplied from the LNG storage tank 10 Exchanged in the evaporated gas heat exchanger 60 with the recovered evaporated gas. Accordingly, the boil-off gas to be introduced into the boil-off gas heat exchanger 60 may be heated by the boil-off gas, which is previously pressurized by the boil-off gas compressor 50 in the boil-off gas heat exchanger 60 and the temperature is raised. Therefore, whenever the evaporated gas generated in the LNG storage tank 10 is supplied to the evaporative gas compressor 50, the heat of the evaporated gas is not directly affected by the temperature of the evaporated gas generated in the LNG storage tank 10, So that the breakage due to the temperature of the evaporation gas can be reduced.

The LNG heat exchanger 40 is provided on the LNG supply line 21 between the high pressure LNG demand destination 20a and the pumps 31 and 32, and the LNG supplied from the pumps 31 and 32 is discharged from the pressurized boil-off gas. Heat exchange. Pumps 31 and 32 for supplying LNG to the LNG heat exchanger 40 may be high pressure pumps 32, and the LNG heat exchanger 40 may supply LNG in a supercooled liquid state or a supercritical state from the high pressure pump 32. Heat-exchanged with the boil-off gas while maintaining the discharge pressure of 200bar to 400bar, can be converted to LNG in a supercritical state of 30 degrees to 60 degrees and then supplied to the high pressure LNG demand destination (20a).

The LNG heat exchanger (40) can heat the LNG using the evaporated gas pressurized in the evaporative gas compressor (50). The LNG is heated by receiving heat from the evaporation gas, and thereby the high-pressure LNG consumer 20a is heated by being heated by the evaporation gas compressor 50. The LNG is cooled by supplying heat to the LNG, The temperature can be raised to the required temperature.

Of course, since the heat source included in the boil-off gas can be varied according to the amount of boil-off gas in the LNG storage tank 10, the present embodiment is separate so that LNG can be smoothly heated to the required temperature of the high pressure LNG demand destination (20a) The heater 41 can be provided. In this case, the heater 41 may be provided downstream of the LNG heat exchanger 40 on the LNG supply line 21, and may heat LNG using electrical energy or steam or glycol water.

The Joule Thompson valve 70 may depressurize the LNG and pressurized boil-off gas discharged from the LNG heat exchanger 40 from 46 bar to 10 bar, and at this time, the boil-off gas may have a cooling effect of -20 ° C. The evaporated gas is cooled by heat exchange with the LNG in the LNG heat exchanger (40), but the pressure can maintain the discharge pressure discharged from the evaporative gas compressor (50). In this embodiment, since the liquefied boil-off gas can be supplied to the high-pressure LNG demand destination 20a by the pumps 31 and 32, the boil-off gas that maintains the discharge pressure from the boil-off gas compressor 50 as it is is a high-pressure pump ( When the high pressure pump 32 is introduced into the high pressure pump 32, the high pressure pump 32 may be damaged.

Therefore, the present embodiment lowers the pressure of the boil-off gas by using the Joule Thompson valve 70, so that the pressure of the boil-off gas at the inlet of the high-pressure pump 32 is changed to a range in which a problem does not occur in driving the high-pressure pump 32. You can do that.

Since the Joule Thompson valve 70 may be provided downstream of the LNG heat exchanger 40, the boil-off gas flowing into the Joule Thompson valve 70 may be at least partially liquefied. Therefore, the boil-off gas in the liquid state depressurized by the Joule Thompson valve 70 flows into the high pressure pump 32 and the high pressure LNG demand destination 20a together with the LNG transferred from the LNG storage tank 10 through the boosting pump 31. Can be supplied.

The temporary storage tank 80 is provided downstream of the Joule Thompson valve 70 and in the LNG supply line 21 between the LNG storage tank 10 and the pumps 31 and 32, and LNG from the LNG storage tank 10 Inflow, the boil-off gas from the Joule Thompson valve 70 may be introduced to discharge the LNG to the high pressure pump (32).

The temporary storage tank 80 liquefies the evaporated gas discharged from the Joule Thompson valve 70 by heat exchange with LNG discharged from the LNG storage tank 10 to convert the evaporated gas liquefied in the LNG heat exchanger 40 into a high pressure pump 32. Can be discharged.

The boil-off gas supply line 22 of the present embodiment includes the boil-off gas heat exchanger 60, the boil-off gas compressor 50, the boil-off gas heat exchanger 60, the LNG heat-exchanger 40, and a cord from the LNG storage tank 10. Thompson valve 70, can be connected to the temporary storage tank (80). The boil-off gas is generated in the LNG storage tank 10 and discharged along the boil-off gas supply line 22, pressurized in the boil-off gas compressor 50 through the boil-off gas heat exchanger 60, and in the LNG heat-exchanger 40. Heat exchanged by LNG, may be reduced pressure in the Joule Thompson valve 70 and then flow into the pump (31, 32). In this case, the pumps 31 and 32 may refer to the high pressure pump 32.

In this embodiment, the high pressure pump 32 compresses the boil-off gas generated in the LNG storage tank 10 by external heat penetration and supplies it to the low pressure LNG demand destination 20b, or liquefies and depressurizes after the multi-stage compression. By supplying to the high pressure LNG demand destination (20a) through, or by multi-stage compression to supply to the high pressure LNG demand destination (20a), it is possible to prevent the evaporated gas is discarded.

1,2: LNG processing system
10: LNG storage tank 11: outer tank
12: inner tank 13:
14: Support 15: Baffle
20: LNG source 20a: High pressure LNG source
20b: low pressure LNG source 21: LNG supply line
22: boil-off gas supply line 23: low pressure boil-off gas supply line
24: high pressure boil-off gas supply line 30: pump
31: boosting pump 32: high pressure pump
40: LNG heat exchanger 50: Evaporative gas compressor
60: boil-off gas heat exchanger 70: Joule Thompson valve
80: temporary storage tank

Claims (8)

An LNG supply line from the LNG storage tank to the LNG consumer site;
A pump provided on the LNG supply line for pressurizing the LNG discharged from the LNG storage tank;
An evaporative gas compressor for pressurizing the evaporation gas generated in the LNG storage tank and provided in a plurality of stages to pressurize the evaporation gas at multiple stages;
An LNG heat exchanger provided on the LNG supply line between the LNG consumer and the pump for heat-exchanging the LNG supplied from the pump with the pressurized evaporated gas;
An evaporative gas heat exchanger installed upstream of the evaporative gas compressor for exchanging heat between the evaporated gas generated in the LNG storage tank and the evaporated gas pressurized in the evaporative gas compressor; And
It includes a Joule Thompson valve for reducing the cooling by reducing the evaporated gas heat exchanged with the LNG discharged from the LNG heat exchanger,
The pump includes a boosting pump provided on the LNG supply line and pressurizing the LNG, and a high pressure pump compressing the LNG discharged from the boosting pump to a high pressure.
The liquid boil-off gas, depressurized by the Joule Thompson valve, flows into the high pressure pump together with LNG delivered through the boosting pump,
The Joule Thompson valve is LNG processing system, characterized in that to prevent the breakage of the high pressure pump by flowing the evaporated gas into the high pressure pump after decompression. The method of claim 1,
The LNG processing system further comprises a high pressure boil-off gas supply line connected to the LNG demand destination from the boil-off gas compressor. 3. The method of claim 2,
The plurality of boil-off gas compressor pressurizes boil-off gas to 200bar to 400bar, the pressurized boil-off gas is supplied to the LNG demand destination through the high-pressure boil-off gas supply line. The method of claim 1,
It is provided in the LNG supply line downstream of the Joule Thompson valve and between the LNG storage tank and the pump, LNG flows from the LNG storage tank, and boil-off gas flows from the Joule Thompson valve to discharge LNG to the pump. LNG processing system further comprises a temporary storage tank. The method of claim 4, wherein the temporary storage tank,
LNG processing system, characterized in that the boil-off gas discharged from the Joule Thompson valve is mixed with the LNG discharged from the LNG storage tank and liquefied and supplied to the pump. delete The method of claim 1, wherein the LNG demanding entity, to which the LNG supply line is connected,
LNG processing system, characterized in that the high pressure LNG demand. The method of claim 1,
And a low pressure boil-off gas supply line, one end of which is connected between the plurality of boil-off gas compressors and supplies the pressurized boil-off gas to a low pressure LNG source.

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