KR20150070454A - A Treatment System Liquefied Gas - Google Patents

Abstract

The present invention relates to a liquefied gas treatment system which is characterized by comprising a vaporized gas supply line connected from a liquefied gas storage tank to a high pressure engine or a low pressure engine; and multiple vaporized gas compressors formed on the vaporized gas supply line, and compressing the vaporized gas generated in the liquefied gas storage tank in multistage, wherein at least one among the multiple vaporized gas compressors includes a cylinder, a piston, multiple intake valves, and multiple discharge valves, and at least one among the multiple intake valves maintains an opened state, when the vaporized gas is discharged at a pressure higher than the set pressure range. The liquefied treatment system according to the present invention, when supplying the vaporized gas generated in the liquefied storage tank in the pressure required in the engine by compressing by multiple vaporized gas compressors in multistage, selectively maintains some of the intake valves among the multiple vaporized gas compressors to easily control pressure of the vaporized gas, thereby stably supplying the vaporized gas at a required in the engine, improving the fuel energy efficiency of the engine, and improving stability of the system.

Description

Description of the Related Art A Treatment System Liquefied Gas

The present invention relates to a liquefied gas processing system.

Liquefied natural gas (Liquefied natural gas), Liquefied petroleum gas (Liquefied petroleum gas) and other liquefied gas are widely used in place of gasoline or diesel in recent technology development.

Liquefied natural gas is a liquefied natural gas obtained by refining natural gas collected from a gas field. It is a colorless and transparent liquid with almost no pollutants and high calorific value. It is an excellent fuel. On the other hand, liquefied petroleum gas is a liquid fuel made by compressing gas containing propane (C3H8) and butane (C4H10), which come from oil in oil field, at room temperature. Liquefied petroleum gas, like liquefied natural gas, is colorless and odorless and is widely used as fuel for household, business, industrial, and automotive use.

Such liquefied gas is stored in a liquefied gas storage tank installed on the ground or stored in a liquefied gas storage tank provided in a ship which is a means of transporting the ocean. The liquefied natural gas is liquefied to a volume of 1/600 The liquefaction of liquefied petroleum gas has the advantage of reducing the volume of propane to 1/260 and the content of butane to 1/230, resulting in high storage efficiency.

However, since the liquefied gas is kept in a liquefied state by increasing the pressure or lowering the temperature, it is important to secure the heat insulating property of the liquefied gas storage tank because the phase change due to external heat penetration is a concern. However, since the liquefied gas storage tank can not achieve perfect heat insulation, some of the liquefied gas stored in the liquefied gas storage tank is phase-changed into vapor gas, which is a gas, by heat transmitted from the outside.

When the internal pressure of the liquefied gas storage tank exceeds the pressure that can be tolerated by the liquefied gas storage tank, the liquefied gas storage tank The tank may be damaged.

Therefore, conventionally, in order to keep the internal pressure of the liquefied gas storage tank at a constant level, a method has been used in which the evaporation gas is discharged to the outside to lower the internal pressure of the liquefied gas storage tank, if necessary. Or the evaporation gas was discharged to the outside of the liquefied gas storage tank, and then liquefied by using a separate liquefaction device and then recovered again into the liquefied gas storage tank.

However, when the evaporation gas is merely discharged to the outside, a problem of contamination of the external environment may occur, and in the case of using the re-liquefaction device, there arises a problem such as a cost and manpower required for installing and operating the liquefaction device. Therefore, it is required to develop an effective treatment method of the evaporation gas generated by external heat penetration.

This prior art is disclosed in Korean Patent Registration No. 10-1289212 (filed on Mar. 17, 2013).

SUMMARY OF THE INVENTION The present invention has been made in order to solve the problems of the prior art as described above, and it is an object of the present invention to provide a gas- The temperature and the pressure of the evaporation gas can be easily controlled so that the evaporation gas can be stably supplied to the temperature and the pressure required by the engine and the fuel efficiency of the engine can be increased, The present invention is intended to provide a liquefied gas processing system capable of improving the performance of the liquefied gas.

It is another object of the present invention to provide a high-pressure surplus liquefied gas or high-pressure surplus to be discharged to the outside from the front end of a high-pressure engine when supplying a liquefied gas or an evaporated gas from a liquefied gas storage tank to a temperature and a pressure required by a high- The excess liquefied gas or surplus evaporation gas can be recycled as the fuel of the high-pressure engine or the low-pressure engine by joining the evaporation gas to the rear end of the first compressor, thereby preventing waste of fuel energy of the engine, The present invention is intended to provide a liquefied gas processing system capable of enhancing the liquefied gas.

A liquefied gas processing system according to an aspect of the present invention includes: a vapor gas supply line connected from a liquefied gas storage tank to a high-pressure engine or a low-pressure engine; And a plurality of evaporative gas compressors provided on the evaporative gas supply line and for pressurizing the evaporative gas generated in the liquefied gas storage tank in multiple stages, wherein at least one of the plurality of evaporative gas compressors is a cylinder, A piston, a plurality of suction valves, and a plurality of discharge valves, wherein at least one of the plurality of suction valves maintains an open state when the evaporation gas is discharged at a pressure higher than a set pressure range .

Specifically, at least one of the plurality of evaporative gas compressors may be reciprocating.

Specifically, the plurality of suction valves of the reciprocating evaporative gas compressor may be controlled by a pressure sensor provided on the evaporative gas supply line downstream of the reciprocating evaporative gas compressor.

Specifically, the pressure sensor checks the pressure of the evaporative gas discharged from the reciprocating evaporative gas compressor, and when at least one of the plurality of suction valves is checked for a pressure higher than the set pressure range, The valve is forcibly maintained in the open state, and when the set pressure range is checked, the forcibly opened intake valve can be normally operated.

Specifically, the plurality of evaporative gas compressors may further include a plurality of evaporative gas coolers provided on the evaporative gas supply line downstream of each of the plurality of evaporative gas compressors.

Specifically, the plurality of evaporative gas compressors may be constituted by first to fifth compressors, and the plurality of evaporative gas coolers may be constituted by first to fifth coolers.

Specifically, the high-pressure engine may be connected to the evaporation gas supply line downstream of the fifth compressor, and the low-pressure engine may be connected to the evaporation gas supply line downstream of the second compressor.

A liquefied gas supply line connected from the liquefied gas storage tank to the high-pressure engine; A pump provided on the liquefied gas supply line for pressurizing the liquefied gas discharged from the liquefied gas storage tank; And a liquefied gas heat exchanger provided on the liquefied gas supply line between the high-pressure engine and the pump.

Specifically, the liquefied gas supply line between the liquefied gas heat exchanger and the high-pressure engine may be provided with a surplus liquefied gas discharge line for discharging surplus liquefied gas to the outside.

The liquefied gas processing system according to the present invention is characterized in that when the evaporation gas generated in the liquefied gas storage tank is supplied to the engine at a temperature required by the multi-stage pressurization through a plurality of evaporation gas compressors, the temperature of the evaporation gas flowing into the evaporation gas compressor Accordingly, by allowing the evaporation gas to bypass the evaporation gas cooler provided downstream of the evaporation gas compressor, the temperature of the evaporation gas can be easily controlled, and the evaporation gas can be stably supplied to the temperature required by the engine, The fuel efficiency of the fuel can be increased and the safety of the system can be improved.

The liquefied gas processing system according to the present invention is characterized in that when the evaporation gas generated from the liquefied gas storage tank is supplied to the engine at a pressure required by the engine by multi-stage pressurization through a plurality of evaporation gas compressors, The pressure of the evaporating gas can be easily controlled by returning the evaporating gas to the upstream of the evaporating gas compressor according to the pressure so that the evaporating gas can be stably supplied to the pressure required by the engine, It is possible to enhance the safety of the system.

In addition, the liquefied gas processing system according to the present invention is characterized in that, when the evaporation gas generated in the liquefied gas storage tank is multi-stage pressurized through a plurality of evaporative gas compressors and supplied at a pressure required by the engine, By keeping a part of the valve in the open state, the pressure of the evaporating gas can be easily controlled, the evaporating gas can be stably supplied to the pressure required by the engine, the fuel energy efficiency of the engine can be increased, Safety can be improved.

The liquefied gas processing system according to the present invention is characterized in that when the evaporation gas generated in the liquefied gas storage tank is supplied to the engine at a pressure required by the engine by multi-stage compression through a plurality of evaporation gas compressors, It is possible to easily control the pressure of the evaporated gas and to stably supply the evaporated gas to the pressure required by the engine, and the fuel energy efficiency of the engine Can be increased, and the safety of the system can be improved.

Further, the liquefied gas processing system according to the present invention is characterized in that, when the liquefied gas or the evaporated gas is supplied from the liquefied gas storage tank to the temperature and pressure required by the high-pressure engine, It is possible to recycle excess liquefied gas or surplus evaporated gas as the fuel of the high pressure engine or the low pressure engine by joining the surplus evaporated gas of gas or high pressure to the rear stage of the first compressor, Fuel efficiency of the fuel can be increased.

1 is a conceptual diagram of a liquefied gas processing system according to a first embodiment of the present invention.
2 is a conceptual diagram of a liquefied gas processing system according to a second embodiment of the present invention.
3 is a cross-sectional view of a liquefied gas storage tank for illustrating an evaporative gas compressor used in a liquefied gas processing system.

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 liquefied gas processing system according to a first embodiment of the present invention.

1, the liquefied gas processing system 1 according to the first embodiment of the present invention includes a liquefied gas storage tank 10, a high-pressure engine 20a, a low-pressure engine 20b, a pump 30, A liquefied gas heat exchanger 40, an evaporative gas compressor 50, an evaporative gas cooler 60, a gas combustion unit 70, and an evaporative gas remelting unit 80.

Hereinafter, the liquefied gas may be used to encompass all gaseous fuels generally stored in a liquid state, such as LNG or LPG, ethylene, ammonia, etc. In the case where the gas is not in a liquid state by heating or pressurization, . This also applies to the evaporative gas. In addition, LNG can be used to mean both NG (natural gas) as well as NG as a supercritical state for the sake of convenience. The evaporation gas generated from the LNG can be used not only as a gaseous evaporation gas, but also as a liquefied evaporation gas Can be used to mean including.

The liquefied gas storage tank 10 can store the liquefied gas and supply the liquefied gas through the liquefied gas supply line 21 to the pump 30 to be described later to drive the high pressure engine 20a to be described later. This liquefied gas storage tank 10 must store the liquefied gas in a liquid state, in which case the liquefied gas storage tank 10 may have the form of a pressure tank.

In the present embodiment, the evaporation gas generated from the liquefied gas stored in the liquefied gas storage tank 10 is supplied to the evaporation gas compressor 50, which will be described later, through the evaporation gas supply line 22, Or as a fuel for a high-pressure engine 20a to be described later, or recovering the evaporation gas from the evaporation gas compressor 50 to be described later to the liquefied gas storage tank 10 via the evaporation gas remelting device 80 to be described later, The evaporation gas can be efficiently used.

The liquefied gas storage tank 10 may, for example, maintain an internal pressure of 1 bar to 3 bar or 1 bar to 10 bar, which, of course, may vary depending on the storage tank.

The engines 20a and 20b may be powered by liquefied gas or evaporated gas supplied from the liquefied gas storage tank 10 to generate power. At this time, the engines 20a and 20b may include a high-pressure engine 20a and a low-pressure engine 20b. For example, the high-pressure engine 20a may be a MEGI engine mounted on a ship, A dual fuel engine (DFDE).

As the pistons (not shown) inside the cylinders (not shown) reciprocate by the combustion of the liquefied gas, the crankshaft (not shown) connected to the pistons is rotated, and the crankshaft The shaft (not shown) to be connected can be rotated. Therefore, as the propeller (not shown) connected to the shaft rotates when the engine 20a or 20b is driven, the hull can move forward or backward.

Of course, in the present embodiment, the engine 20a, 20b may be an engine for driving the propeller, but it may be an engine for generating power or an engine for generating other power. That is, the present embodiment does not specifically limit the types of the engines 20a and 20b. However, the engines 20a and 20b may be internal combustion engines that generate driving force by combustion of liquefied gas.

The high-pressure engine 20a is supplied with pressurized supercritical liquefied gas through a pump 30 and a heat exchanger 40 to be described later to generate a driving force, The supercritical state of the evaporation gas may be supplied and the driving force may be generated. On the other hand, the low-pressure engine 20b is supplied with the evaporated gas pressurized by the evaporative gas compressor 50 to obtain the driving force. Here, the supercritical liquefied gas or evaporated gas to which the high-pressure engine 20a is supplied may be, for example, a temperature of 30 to 60 DEG C and a pressure of about 300 to 30 bar, and the supercritical state The evaporation gas may be, for example, at a temperature of 1 to 50 DEG C and a pressure of about 45 bar. The state of the liquefied gas or the evaporated gas supplied to the high-pressure engine 20a and the low-pressure engine 20b may vary depending on the state required by each of the engines 20a and 20b.

The low-pressure engine 20b may be a dual fuel engine in which a mixture of evaporation gas and oil is not supplied and the evaporation gas or oil is selectively supplied. This is to prevent the mixture of two substances having different combustion temperatures from being mixed, thereby preventing the efficiency of the low-pressure engine 20b from deteriorating.

Between the liquefied gas storage tank 10 and the engine 20a or 20b, a liquefied gas supply line 21 for transferring liquefied gas or an evaporation gas supply line 22, 23, 25 for transferring the evaporation gas may be installed have. The liquefied gas supply line 21 is provided with a pump 30 to be described later and a liquefied gas heat exchanger 40 to be described later so that the supercritical liquefied gas can be supplied to the high pressure engine 20a, The evaporation gas compressor 50 and an evaporation gas cooler 60 to be described later are provided on the lines 22, 23 and 25 to supply supercritical evaporation gas to the high pressure engine 20a or the low pressure engine 20b .

At this time, a liquefied gas or an evaporation gas supply valve (not shown) is installed in the liquefied gas or evaporation gas supply lines 21, 22, 23 and 25 at appropriate positions so that liquefied gas or evaporated gas is supplied to the liquefied gas storage tank 10 To the engines 20a and 20b in a stable manner.

The pump 30 is provided on the liquefied gas supply line 21 and pressurizes the liquefied gas discharged from the liquefied gas storage tank 10. The pump 30 may include a boosting pump 31 and a high pressure pump 32.

The boosting pump 31 may be provided on the liquefied gas supply line 21 between the liquefied gas storage tank 10 and the high pressure pump 32 or may be provided in the liquefied gas storage tank 10 in the liquefied gas supply line 21 and a sufficient amount of liquefied gas is supplied to a high pressure pump 32 to be described later to prevent cavitation of the high pressure pump 32. [ Further, the boosting pump 31 can extract the liquefied gas from the liquefied gas storage tank 10 to pressurize the liquefied gas. At this time, in consideration of the limit pressure that can be accommodated in the high-pressure pump 32, for example, It is preferable to pressurize the liquefied gas to the outside.

The boiling pump 31 may pressurize the liquefied gas in the liquefied gas storage tank 10 to slightly increase the pressure and the temperature, The liquefied gas pressurized by the pressurizing device 31 may still be in a liquid state.

The high-pressure pump 32 can pressurize the liquefied gas discharged from the boosting pump 31 at a high pressure, so that liquefied gas can be supplied to the high-pressure engine 20a. The liquefied gas is discharged from the liquefied gas storage tank 10 and then primarily pressurized by the boosting pump 31. The high pressure pump 32 is operated to pressurize the liquefied gas in the liquid state primarily pressurized by the boosting pump 31 into 2 And can be supplied to the high-pressure engine 20a through the liquefied gas heat exchanger 40 to be described later.

At this time, the high-pressure pump 32 pressurizes the liquefied gas to a pressure required by the high-pressure engine 20a, for example, about 300 bar, and supplies it to the high-pressure engine 20a so that the high-pressure engine 20a produces power through the liquefied gas .

The high-pressure pump 32 pressurizes the liquid-state liquefied gas discharged from the boosting pump 31 at a high pressure, and supplies the liquid-phase gas to the supercritical state so that the liquefied gas has a higher temperature and a higher pressure than the critical point. . At this time, the temperature of the liquefied gas in the supercritical state may be relatively higher than the critical temperature.

Alternatively, the high-pressure pump 32 can pressurize the liquefied gas in the liquid state to a super-cooled liquid state by pressurizing it at a high pressure. Here, the liquefied gas in the subcooled liquid state is a state in which the pressure of the liquefied gas is higher than the critical pressure and the temperature is lower than the critical temperature.

Specifically, the high-pressure pump 32 pressurizes the liquid-state liquefied gas discharged from the booster pump 31 at a high pressure of about 300 bar, while the temperature of the liquefied gas is lower than the critical temperature, Phase state. Here, the temperature of the liquefied gas in the subcooled liquid state may be -140 캜 to -60 캜, which is relatively lower than the critical temperature.

The liquefied gas heat exchanger 40 can be provided on the liquefied gas supply line 21 between the high pressure engine 20a and the pump 30 and can supply the liquefied gas supplied from the pump 30 to the high pressure engine 20a, To a desired temperature. The pump 30 for supplying the liquefied gas to the liquefied gas heat exchanger 40 may be the high pressure pump 32 and the liquefied gas heat exchanger 40 may supply the liquefied gas in the subcooled liquid state or the supercritical state to the high pressure pump 32 ), And is supplied to the high-pressure engine 20a after being converted into a liquefied gas in a supercritical state at a temperature of 30 ° C to 60 ° C, while being maintained at a pressure of about 300bar.

The liquefied gas heat exchanger (40) may use electric energy or heat the liquefied gas using a heat transfer medium. Here, the heat transfer medium may be a glycol water, and the glycol water is a fluid obtained by mixing ethylene glycol and water. The fluid is heated in a medium heater (not shown) and cooled in a liquefied gas heat exchanger 40 And can be circulated. The liquefied gas heat exchanger (40) can heat the LNG using waste heat generated from a generator or other equipment provided on the ship.

The excess liquefied gas discharge line 211 may be connected to the liquefied gas supply line 21 between the liquefied gas heat exchanger 40 and the high-pressure engine 20a.

The surplus liquefied gas discharge line 211 is used when the liquefied gas supplied from the high-pressure pump 32 to the high-pressure engine 20a exceeds the amount required by the high-pressure engine 20a, or when the liquefied gas can not be transported downstream The pressure of the liquefied gas can be easily controlled by discharging the surplus liquefied gas to the outside through the excess liquefied gas discharge line 211 so that the liquefied gas is supplied to the high pressure engine 20a It is possible to stably supply the high-pressure engine 20a with pressure and protect the high-pressure engine 20a.

The evaporation gas compressor 50 pressurizes the evaporation gas generated and discharged from the liquefied gas storage tank 10 and supplies it to the low pressure engine 20b or the high pressure engine 20a through the evaporation gas supply lines 22, Or may be supplied to a gas combustion apparatus 70 or an evaporation gas remelting apparatus 80 to be described later. Pressurizing the evaporation gas to the evaporation gas compressor (50) is to increase the liquefaction efficiency of the evaporation gas. Evaporation gas increases the 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.

A plurality of evaporation gas compressors 50 are provided on the evaporation gas supply lines 22 and 25 so that the evaporation gas can be multi-stage pressurized. When the evaporation gas is pressurized by the evaporation gas compressor 50, An evaporative gas cooler 60 may be provided between the plurality of evaporative gas compressors 50. In this case, The evaporative gas cooler 60 may be installed in the same number as the evaporative gas compressor 50 wherein each evaporative gas cooler 60 is provided downstream of each evaporative gas compressor 50 and is connected to an upstream evaporative gas compressor 50, So as to facilitate the operation of the downstream evaporative gas compressor (50).

For example, the plurality of evaporative gas compressors 50 may sequentially include five first to fifth compressors 50a, 50b, 50c, 50d, and 50e based on the flow of the evaporative gas, The cooler 60 may also be provided with five first to fifth coolers 60a, 60b, 60c, 60d, and 60e sequentially based on the flow of the evaporative gas. It is needless to say that the first to fifth coolers 60a, 60b, 60c, 60d and 60e are provided downstream of the first to fifth compressors 50a, 50b, 50c, 50d and 50e, respectively. Although the first to fifth compressors 50a, 50b, 50c, 50d, and 50e are limited to five, the number of the evaporative gas compressors 50 may be five or less The first compressor 50a may be the first evaporative gas compressor but the fifth compressor 50e does not mean the fifth evaporative gas compressor and is the last evaporative gas compressor among the plurality of evaporative gas compressors 50 And the second to fourth compressors 50b, 50c, and 50d do not refer only to the second to fourth evaporative gas compressors, but may be collectively referred to as a middle evaporative gas compressor among the plurality of evaporative gas compressors 50 . Similarly to the first to fifth compressors 50a, 50b, 50c, 50d and 50e, the first to fifth coolers 60a, 60b, 60c, 60d, It is of course also possible to express this as an intermediate evaporative gas cooler.

The evaporation gas supply lines 22, 23 and 25 are distinguished by an evaporation gas supply line 22, a low pressure evaporation gas supply line 23 and a high pressure evaporation gas supply line 25 for convenience of explanation , The role of providing the passage for supplying the evaporation gas is the same. Here, the evaporation gas supply line 22 may have one end connected to the liquefied gas storage tank 10 and the other end connected to the front end of the third compressor 50c, and the evaporation gas discharged from the liquefied gas storage tank 10 Pressure evaporation gas supply line 23 and the high-pressure evaporation gas supply line 25, respectively. The low pressure evaporation gas supply line 23 may be connected at one end to the evaporation gas supply line 22 between the second compressor 50b and the third compressor 50c and at the other end to the low pressure engine 20b, It is possible to provide a passage for supplying the low-pressure engine 20b with the evaporated gas in the low-pressure state. The high-pressure evaporation gas supply line 25 is connected to the rear end of the third compressor 50c at one end and connected to the high-pressure engine 20a at the other end, and supplies the evaporation gas at high pressure to the high- Pathway can be provided.

The evaporated gas generated in the liquefied gas storage tank 10 is supplied to the first to fifth compressors 50a, 50b, 50c, 50d and 50e and the first to fifth coolers 60a, 60b, 60c, 60d and 60e Pressure engine 20b or the high-pressure engine 20a as fuel, and it is necessary to supply at the optimum temperature and pressure required by the respective engines 20a and 20b.

Hereinafter, various means for easily controlling the temperature or pressure of the evaporated gas supplied to each of the engines 20a, 20b will be described.

When the evaporation gas generated in the liquefied gas storage tank 10 is supplied to the plurality of evaporation gas compressors 50 through the plurality of evaporation gas compressors 50 at a temperature required by the engines 20a and 20b, The evaporation gas is bypassed to the first evaporative gas cooler 60 provided downstream of the first evaporative gas compressor 50 in accordance with the temperature of the evaporative gas flowing into the evaporative gas cooler 50, The temperature of the evaporation gas can be easily controlled.

Specifically, one end of the evaporation gas bypass line 221 is connected to the evaporation gas supply line 22 between the first compressor 50a and the first cooler 60a, and the other end is connected to the first cooler 60a and the evaporator 2 compressors 50b of the evaporator 10. The evaporator 50 may be connected to the evaporator gas supply line 22 between the two compressors 50b. A temperature sensor 51 and a first temperature control valve 61 may be installed on the evaporation gas supply line 22 between the first compressor 50a and the first cooler 60a and the evaporation gas bypass line 221, A second temperature control valve 62 may be provided. Here, an apparatus including a vapor bypass line 221, a temperature sensor 51, a first temperature control valve 61, and a second temperature control valve 62 is referred to as a vapor gas bypass device (not shown) Can be named.

The evaporated gas generated in the liquefied gas storage tank 10 is transferred to the second compressor 50b via the first compressor 50a and the temperature of the evaporated gas discharged from the first compressor 50a is detected by the temperature sensor 51 ). The first temperature control valve 61 is opened by the temperature sensor 51 and the second temperature control valve 61 is opened by the temperature sensor 51 when the second compressor 50b is operated, The temperature control valve 62 is closed so that the evaporated gas cooled by the first cooler 60a is transferred to the second compressor 50b. When the temperature of the second compressor 50b is checked and the temperature of the second compressor 50b is checked to be in a temperature range (below the first temperature range) in which the evaporation gas is not required to be cooled, the first temperature control valve 61 is closed by the temperature sensor 51 The second temperature control valve 62 is opened so that the evaporated gas passed through the first compressor 50a is bypassed through the evaporative gas bypass line 221 to be directly transferred to the second compressor 50b.

The temperature sensor 51 serves to open or close (or adjust the opening degree) the first temperature control valve 61 and the second temperature control valve 62 and controls the temperature of the evaporation gas discharged from the first compressor 50a The first temperature control valve 61 and the second temperature control valve 62 are preferably located on the evaporation gas supply line 22 upstream of the first temperature control valve 61 and the second temperature control valve 62. Therefore, The second temperature control valve 62 is preferably arranged in parallel.

In the above-described embodiment, the configuration has been described in which the evaporated gas is bypassed to the first cooler 60a in accordance with the temperature of the evaporated gas discharged from the first compressor 50a. However, The same can be applied to the downstream of each of the first, second, third, fourth, fifth, sixth, seventh and eighth embodiments 50b, 50c, 50d, and 50e. However, considering that the temperature of the evaporated gas discharged from each of the first to fifth compressors 50a, 50b, 50c, 50d, and 50e may vary depending on the temperature of the flowing evaporated gas, the first compressor 50a When the evaporated gas generated in the liquefied gas storage tank 10 is first introduced and the temperature of the introduced evaporated gas, for example, the liquefied gas stored in the liquefied gas storage tank 10 is LNG liquefied gas, At this time, if the LNG evaporation gas is lower in temperature than necessary from the liquefied gas storage tank 10, the second compressor 50b is operated even if it is pressurized by the first compressor 50a, It is preferable to apply the above configuration to the first compressor 50a, thereby avoiding driving the first cooler 60a, thereby increasing the energy efficiency of the system.

When the evaporation gas generated in the liquefied gas storage tank 10 is multi-stage pressurized through the plurality of evaporative gas compressors 50 and supplied to the pressures required by the engines 20a and 20b, And the evaporation gas is returned to the upstream of the evaporative gas compressor 50 in accordance with the pressure of the evaporative gas discharged from the third or last evaporative gas compressor 50, have.

Specifically, a first evaporation gas return line 222 for returning the evaporated gas discharged from the first compressor 50a, which is the first evaporated gas compressor 50, to the upstream of the first compressor 50a, A second evaporative gas return line 223 for returning the evaporated gas discharged from the second compressor 50b serving as the second evaporated gas compressor 50 to the upstream of the second compressor 50b, A third evaporation gas return line 224 for returning the evaporated gas discharged from the third compressor 50c to the upstream side of the third compressor 50c or the third evaporation gas return line 224 for returning the evaporated gas discharged from the third evaporator 50 to the upstream side of the third compressor 50c, And a fourth evaporative gas return line 225 for returning the evaporated gas discharged from the fifth compressor 50e to the upstream of the fourth compressor 50d which is the middle evaporative gas compressor 50. [ At least one of the first to fourth evaporation gas return lines 222, 223, 224, and 225 may be provided and operated when the evaporated gas to be discharged is pressurized to a pressure higher than the set pressure range, Can be utilized.

The pressure of the evaporation gas discharged from each of the first to fifth compressors 50a, 50b, 50c, 50d, and 50e can be set differently from each other. As the pressure from the first compressor 50a to the fifth compressor 5e increases, And can be raised to a pressure required by the low-pressure engine 20b or the high-pressure engine 20a. For example, if the liquefied gas stored in the liquefied gas storage tank 10 is an LNG liquefied gas and the pressure of the evaporated gas flowing into the first compressor 50a from the liquefied gas storage tank 10 is about 1.05 bar, The first set pressure range discharged from the compressor 50a is about 5 bar, the second set pressure range discharged from the second compressor 50b is about 15 bar, and the third set pressure range discharged from the third compressor 50c is 90 bar The fourth set pressure range discharged from the fourth compressor 50d is about 150 bar, and the fifth set pressure range discharged from the fifth compressor 50e is about 300 bar. Here, the numerical values for the pressure are only for the sake of understanding the present embodiment, and it is needless to say that the numerical values are not limited to the numerical values in the present embodiment.

The first evaporation gas return line 222 is connected at one end to the evaporation gas supply line 22 downstream of the first compressor 50a and at the other end to the evaporation gas supply line 22 upstream of the first compressor 50a To be connected. A first pressure sensor 52 may be provided on the evaporation gas supply line 22 between the first cooler 60a and the second compressor 50b and a first pressure sensor 52 may be provided on the first evaporation gas return line 222. [ A valve 63 may be provided. Here, a device including the first evaporation gas return line 222, the first pressure sensor 52, and the first pressure regulating valve 63 is referred to as a first evaporation gas return device (not shown) .

One end of the first evaporation gas return line 222 is connected to the evaporation gas supply line 22 downstream of the first compressor 50a and specifically to the evaporation gas supply line 22 downstream of the first condenser 60a, It is preferable that the evaporation gas bypass line 221 is connected to the evaporation gas supply line 22 downstream of the evaporation gas bypass line 221 when the evaporation gas bypass line 221 is provided. That is, one end of the first evaporation gas return line 222 is preferably connected to the evaporator gas supply line 22 downstream of the first cooler 60a and the evaporation gas bypass line 221.

The pressure of the evaporation gas discharged from the first compressor (50a) is checked by the first pressure sensor (52). When the pressure is checked to be higher than the first set pressure range, the first pressure sensor 52 opens the first pressure control valve 63 to return a part of the evaporated gas to the upstream of the first compressor 50a The first pressure regulating valve 63 is closed by the first pressure sensor 52 so that the refrigerant is transferred from the first compressor 50a to the second compressor 50b The evaporation gas can always be maintained in the first set pressure range, so that the evaporation gas can be supplied stably to the pressure required by the high-pressure engine 20a or the low-pressure engine 20b.

The first pressure sensor 52 serves to open or close the first pressure regulating valve 63 or to check the pressure of the evaporating gas discharged from the first compressor 50a , It is preferably located downstream of the point where the first evaporation gas return line 221 is connected on the evaporation gas supply line 22.

The second evaporation gas return line 223 is connected at one end to the evaporation gas supply line 22 downstream of the second compressor 50b and at the other end to the evaporation gas supply line 22 upstream of the second compressor 50b To be connected. A second pressure sensor 53 may be provided on the evaporation gas supply line 22 between the second cooler 60b and the third compressor 50c and on the second evaporation gas return line 223, A valve 64 may be provided. Here, the apparatus including the second evaporation gas return line 223, the second pressure sensor 53, and the second pressure regulating valve 64 is referred to as a second evaporation gas return device (not shown) .

One end of the second evaporation gas return line 223 is connected to the evaporation gas supply line 22 downstream of the second compressor 50b and specifically to the evaporation gas supply line 22 downstream of the second condenser 60b, . The other end of the second evaporation gas return line 223 is connected to the evaporation gas supply line 22 upstream of the second compressor 50b and specifically to the temperature sensor 51 and the evaporation gas bypass line 221, It is preferable to be connected to the evaporation gas supply line 22 upstream of the temperature sensor 51 (between the first compressor and the first condenser).

The pressure of the evaporated gas discharged from the second compressor (50b) is checked by the second pressure sensor (53). When the pressure is checked to be higher than the second set pressure range, the second pressure sensor 53 opens the second pressure regulating valve 64 to return part of the evaporated gas to the upstream of the second compressor 50b The second pressure control valve 64 is closed by the second pressure sensor 53 so as to be transmitted from the second compressor 50b to the third compressor 50c The evaporation gas can always be maintained in the second set pressure range and can eventually supply the evaporation gas stably at the pressure required by the high pressure engine 20a or the low pressure engine 20b.

The second pressure sensor 53 serves to open or close the second pressure regulating valve 64 or to check the pressure of the evaporating gas discharged from the second compressor 50b The second evaporation gas return line 223 is located downstream of the point where the second evaporation gas return line 223 is branched on the evaporation gas supply line 22.

The third evaporation gas return line 224 has one end connected to the high pressure evaporation gas supply line 25 downstream of the third compressor 50c and the other end connected to the evaporation gas supply line 22 upstream of the third compressor 50b. As shown in FIG. A third pressure sensor 54 may be provided on the high pressure evaporative gas supply line 25 between the third cooler 60c and the fourth compressor 50d and on the third evaporative gas return line 224, A regulating valve 65 may be provided. Here, a device including the third evaporation gas return line 224, the third pressure sensor 54, and the third pressure regulating valve 65 is referred to as a third evaporation gas return device (not shown) .

One end of the third evaporation gas return line 224 is connected to the high pressure evaporation gas supply line 25 downstream of the third compressor 50c and specifically to the high pressure evaporation gas supply line 25). The other end of the third evaporation gas return line 224 is connected to the evaporation gas supply line 22 upstream of the third compressor 50c and specifically to the evaporation gas supply line 22 ).

The pressure of the evaporated gas discharged from the third compressor (50c) is checked by the third pressure sensor (54). When the pressure is checked to be higher than the third set pressure range, the third pressure sensor 54 opens the third pressure regulating valve 65 so that a part of the evaporated gas returns to the upstream of the third compressor 50c The third pressure control valve 65 is closed by the third pressure sensor 54 so that the third pressure control valve 65 is transmitted from the third compressor 50c to the fourth compressor 50d The evaporation gas can always be maintained in the third set pressure range, so that the evaporation gas can be stably supplied to the pressure required by the high-pressure engine 20a.

The third pressure sensor 54 serves to open or close the third pressure regulating valve 65 or to check the pressure of the evaporating gas discharged from the third compressor 50c It is preferable that the third evaporation gas return line 224 is located on the downstream side of the point where the third evaporation gas return line 224 is branched on the high pressure evaporation gas supply line 25.

The fourth evaporation gas return line 225 is connected at one end to the high pressure evaporation gas supply line 25 downstream of the fifth compressor 50e and at the other end to the high pressure evaporation gas supply line 25 As shown in FIG. A fourth pressure sensor 55 may be installed on the high pressure evaporation gas supply line 25 between the fifth cooler 60e and the high pressure engine 20a and on the fourth evaporation gas return line 225, A valve 66 may be provided. Here, a device including the fourth evaporation gas return line 225, the fourth pressure sensor 55, and the fourth pressure regulating valve 66 is referred to as a fourth evaporation gas return device (not shown) .

One end of the fourth evaporation gas return line 225 is connected to the high pressure evaporation gas supply line 25 downstream of the fifth compressor 50e and specifically to the high pressure evaporation gas supply line 25). The other end of the fourth evaporation gas return line 225 is connected to the high pressure evaporation gas supply line 25 upstream of the fourth compressor 50d and specifically to the high pressure evaporation gas supply line 25 downstream of the third pressure sensor 54. [ (25).

The pressure of the evaporation gas discharged from the fifth compressor (50e) through the fourth compressor (50d) is checked by the fourth pressure sensor (55). When the pressure is checked to be higher than the fifth set pressure range, the fourth pressure sensor 55 opens the fourth pressure regulating valve 66 to return a part of the evaporated gas to the upstream of the fourth compressor 50d And the fourth pressure regulating valve 66 is closed by the fourth pressure sensor 55 when the fifth set pressure range is checked and the evaporation amount of the evaporation water supplied from the fifth compressor 50e to the high pressure engine 20a The gas can always be maintained in the fifth set pressure range, and eventually the evaporation gas can be stably supplied to the pressure required by the high-pressure engine 20a.

The fourth pressure sensor 55 functions to open or close the fourth pressure regulating valve 66 or to check the pressure of the evaporating gas discharged from the fifth compressor 50e It is preferable that the fourth evaporation gas return line 225 is located downstream of the point where the fourth evaporation gas return line 225 branches on the high pressure evaporation gas supply line 25.

On the other hand, the downstream of the fifth compressor (50e) is blocked by the block (50b) due to the occurrence of an abnormality in the gas train or the like provided in the high-pressure engine (20a) a block valve 67 having an on / off function is provided so as to be in parallel with the fourth evaporative gas return line 225 in which the fourth pressure regulating valve 66 is installed, And a fifth evaporative gas return line 226 on which the second evaporative gas recovery line 226 is installed. By additionally providing the fifth evaporative gas return line 226 additionally, the stability of the high-pressure engine 20a can be further improved. Here, the fifth evaporative gas return line 226 and the block valve 67 may be included in the fourth evaporative gas return device (not shown).

In the above, the block valve 67 can be opened by controlling the fourth pressure sensor 55 to block the downstream of the fifth compressor 50e. Therefore, it is possible to improve the return performance of the evaporative gas in an emergency, and the stability of the entire system can be enhanced.

The third means is that when the evaporated gas generated in the liquefied gas storage tank 10 is multi-stage pressurized through the plurality of evaporative gas compressors 50 and supplied at the pressure required by the engines 20a and 20b, As described above, by keeping a part of the suction valve 503 selectively in the plurality of evaporative gas compressors 50, the pressure of the evaporated gas can be easily controlled.

More specifically, at least one of the first to fifth compressors 50a, 50b, 50c, 50d, and 50e may be reciprocating, and the first to fifth compressors 50a, 50b, 50c, 50d, 50e May include a cylinder 501, a piston 502, a plurality of suction valves 503, and a plurality of discharge valves 504. The plurality of suction valves 503 provided in the reciprocating first to fifth compressors 50a, 50b, 50c, 50d and 50e are controlled by the first to fourth pressure sensors 52, 53, 54, 50b, 50c, 50d, and 50e is pressurized to a pressure higher than a predetermined pressure range, at least one of the plurality of suction valves 503 Any one or more of them can be operated to forcibly maintain the open state, thereby forcibly lowering the pressurizing efficiency and can be utilized as the pressure reducing means.

In a general reciprocating compressor, a plurality of suction valves 503 are all opened and a plurality of discharge valves 504 are all closed in the evaporation gas sucking step. In the evaporating gas discharging step, all the plurality of suction valves 503 are closed The plurality of discharge valves 504 are all opened and thus can not be utilized as the pressure reducing means.

When the first compressor (50a) is reciprocating, the first pressure sensor (52) provided on the evaporation gas supply line (22) checks the pressure of the evaporation gas discharged from the first compressor (50a) At least one suction valve 503 among the plurality of suction valves 503 provided in the first compressor 50a by the first pressure sensor 52 is operated by the first pressure sensor 52 When the first set pressure range is checked, the suction valve 503 forcibly opened by the first pressure sensor 52 is normally operated, so that the refrigerant discharged from the first compressor 50a The evaporated gas delivered to the second compressor 50b can always be maintained in the first set pressure range and can eventually supply the evaporated gas stably to the pressure required by the high pressure engine 20a or the low pressure engine 20b.

When the second to fourth compressors 50b, 50c, 50d and 50e are reciprocating, the second to fourth pressure sensors 53, 54 and 55, as described in the first compressor 50a, The suction valve 503 of each of the second to fourth compressors 50b, 50c, 50d, and 50e can be controlled. Therefore, the case where the second to fourth compressors 50b, 50c, 50d, and 50e are reciprocating will not be described here in detail. The second compressor 50b is controlled by the second pressure sensor 53. The third compressor 50c is controlled by the third pressure sensor 54 and the fourth and fifth compressors 50d and 50e 54 and 55 checked by the second to third pressure sensors 53, 54 and 55 are different from those of the first compressor 50a to be controlled by the fourth pressure sensor 55. The second, Each of the set pressure ranges is different from the first set pressure range checked by the first pressure sensor 52. [

On the other hand, although not shown in the drawing, the first pressure sensor 52 can control the suction valve 503 of the second compressor 50b on the downstream side, and the second pressure sensor 53 can control the suction valve 503 of the third compressor 50b, The third pressure sensor 54 may control the suction valve 503 of the compressor 50c and the third pressure sensor 54 may control the suction valve 503 of each of the fourth and fifth compressors 50d and 50e.

The fourth means is for evaporating the excess evaporation gas when the evaporation gas generated in the liquefied gas storage tank 10 is multi-stage pressurized by the plurality of evaporative gas compressors 50 and supplied at the pressure required by the engines 20a, 20b The pressure of the evaporation gas can be easily controlled by making the combustion, re-liquefaction or discharge according to the pressure of the evaporation gas discharged from the gas compressor (50).

Specifically, a gas combustion apparatus 70 for burning the evaporated gas discharged from the first compressor 50a, or an evaporative gas remelting apparatus (not shown) for re-liquefying the evaporated gas discharged from the second compressor 50b 80 or an excess evaporative gas discharge line 227 for discharging the evaporated gas discharged from the fifth compressor 50e to the outside. At least one of the gas combustion device 70, the evaporation gas remelting device 80, and the surplus evaporation gas discharge line 227 may be provided. If the evaporated gas to be discharged exceeds a predetermined amount or is not transported downstream It can be used as a means to appropriately control the amount of evaporation gas.

When the amount of the evaporative gas discharged from the first compressor 50a exceeds the sum required by the high-pressure engine 20a and the amount required by the low-pressure engine 20b, the gas- To the evaporation gas supply line 22 downstream of the first compressor 50a so as to burn the excess evaporation gas that can not be transported downstream of the first compressor 50a.

The gas combustion apparatus 70 is preferably provided downstream of the first compressor 50a that maintains a relatively low pressure state because there is a restriction that the gas combustion apparatus 70 can not be used when the pressure of the evaporation gas is high. As described above, the evaporation gas pressure downstream of the first compressor 50a is about 5 bar (the first set pressure range), and the evaporation gas pressure downstream of the other compressors 50b, 50c, 50d, and 50e The set pressure range) is relatively low.

In order to reduce the waste of fuel, the gas combustion device 70 needs to be operated as the last means to burn out the surplus evaporation gas. Accordingly, the pressure of the evaporation gas discharged from the first compressor 50a The first evaporative gas recovery device 52, 63, and 222, which control and stabilize the first evaporative gas return device, is the first to operate the first evaporative gas return device. Therefore, the rear end of the first evaporative gas return device, It is preferable to place it in the evaporation gas supply line 22 downstream of the sensor 52.

When the amount of evaporated gas discharged from the second compressor 50b exceeds the amount required by the low pressure engine 20b, the evaporation gas remelting device 80 supplies the surplus evaporated gas that can not be transferred to the low pressure engine 20b side Pressure evaporation gas supply line 23 and the other end of which is connected to the liquefied gas storage tank 10 so that the liquefied gas can be re-liquefied.

The evaporation gas re-liquefier 80 can sufficiently cool the surplus evaporation gas to change it into a liquid phase, and can cause the evaporated gas changed into the liquid phase to be re-introduced into the liquefied gas storage tank 10 to be recycled. Pressure engine 20b and the low-pressure evaporation gas supply line 23 between the low-pressure engine 20b and the low-pressure engine 20b, whereby the amount of evaporation gas required by the low-pressure engine 20b can be appropriately adjusted, So that the liquefaction efficiency can be improved.

By providing the evaporation gas re-liquefier 80 downstream of the second compressor 50b, the evaporation gas remelting device 80 can be operated in a nitrogen heat exchanger (not shown) for using nitrogen as a refrigerant in the evaporation- It is possible to prevent the pressure difference from being exerted, and to prevent the pore of the nitrogen heat exchanger.

It is preferable that the evaporation gas remelting device 80 is provided downstream of the fourth compressor 50d or the fifth compressor 50e rather than downstream of the second compressor 50b, 50a, 50b, and 50c, lubricating oil is not contained in the evaporative gas passing through the fourth and fifth compressors 50d and 50c, If the evaporating gas remelting device 80 is provided downstream of the compressor 5Oe, the liquefied evaporated gas may contain lubricating oil. When the re-liquefied vapor gas containing the lubricating oil flows into the liquefied gas storage tank 10, the lubricating oil component may cause a problem by freezing.

The excess evaporative gas discharge line 227 may be connected to the high pressure evaporative gas supply line 25 between the fifth compressor 50e and the high pressure engine 20a.

The surplus evaporated gas discharge line 227 is used when the evaporated gas supplied from the fifth compressor 50e to the high pressure engine 20a exceeds the amount required by the high pressure engine 20a or when the evaporated gas can not be transported downstream The pressure of the evaporated gas can be easily controlled by discharging the surplus evaporated gas to the outside through the surplus evaporated gas discharge line 227. This allows the evaporated gas to be supplied to the high- And the high-pressure engine 20a can be protected.

2 is a conceptual diagram of a liquefied gas processing system according to a second embodiment of the present invention.

2, the liquefied gas processing system 2 according to the second embodiment of the present invention includes a liquefied gas storage tank 10, a high-pressure engine 20a, a low-pressure engine 20b, a pump 30, A liquefied gas heat exchanger 40, an evaporative gas compressor 50, an evaporative gas cooler 60, a gas combustion device 70, an evaporative gas remelting device 80 and an exhaust gas recovery device 90.

In the second embodiment of the present invention, the remaining components 10, 20a, 20b, 30, 40, 50, 60, 70, 80, except for the exhaust gas recovery device 90, The same reference numerals are used for the same components in the exemplary liquefied gas processing system 1 and the same reference numerals are used. Accordingly, detailed description of each of the same components will be omitted in order to avoid duplication of the description, The exhaust gas recovery device 90, which is a different component from the embodiment, will be mainly described.

When the liquefied gas or the evaporated gas is supplied from the liquefied gas storage tank 10 to the high pressure engine 20a at a temperature and a pressure required by the high pressure engine 20a, Pressure surplus liquefied gas or high-surplus surplus evaporated gas to be joined can be joined to the rear end of the first compressor 50a, whereby excess liquefied gas or surplus evaporated gas can be supplied to the high-pressure engine 20a or the low-pressure engine 20b It can be recycled as fuel. Here, since the surplus liquefied gas passes through the high-pressure pump 32 and the heat exchanger 40, it is not a liquid state but a gas.

The exhaust gas collecting device 90 includes an exhaust gas collecting line 91, a pressure reducer 92 provided on the exhaust gas collecting line 91, a buffer tank (not shown) provided on the exhaust gas collecting line 91 93).

The exhaust gas reclaiming device 90, which requires the high-pressure surplus liquefied gas or the high-pressure surplus evaporative gas to be discharged to the outside from the front end of the high-pressure engine 20a to be joined to the rear end of the first compressor 50a, 20a and the first compressor 50a side. In other words, the pressure of the surplus liquefied gas or excess evaporation gas discharged from the surplus liquefied gas discharge line 211 or the surplus evaporated gas discharge line 227 connected to the front end of the high-pressure engine 20a is about 300 bar (The fifth predetermined pressure range), and the pressure of the evaporation gas downstream of the first compressor 50a may be low (for example, about 5 bar) (the first set pressure range) Decompression is required.

The exhaust gas recovery line 91 is connected to the surplus liquefied gas discharge line 211 or the surplus evaporated gas discharge line 227 at the front end of the high pressure engine 20a and the other end is connected to the rear end of the first compressor 50a Respectively. This exhaust gas recovery line 91 extends from the front end of the high-pressure engine 20a to the rear end of the first compressor 50a, so that the excess liquefied gas or surplus evaporated gas is decompressed as the high- (For example, the first set pressure range) state at the merging point at the rear end of the first compressor 50a.

The pressure reducing device 92 can be installed on the exhaust gas collecting line 91 and can further reduce the pressure of the excess liquefied gas or the surplus evaporating gas of the high pressure in addition to the primary pressure reducing of the exhaust gas collecting line 91 have. The pressure reducer 92 may be at least one pressure reducing valve (for example, a line Thompson valve).

The buffer tank 93 can be installed on the exhaust gas collecting line 91 and can further reduce the secondary pressure of the excess liquefied gas or the surplus evaporated gas of high pressure in addition to the primary vacuum of the exhaust gas collecting line 91 have.

The decompressor 92 and the buffer tank 93 may be provided on the exhaust gas collecting line 91 at the same time to further improve the function of decompressing the excess liquefied gas or excess evaporated gas.

1, 2: liquefied gas processing system 10: liquefied gas storage tank
20a: high-pressure engine 20b: low-pressure engine
21: liquefied gas supply line 22: evaporated gas supply line
23: low pressure evaporation gas supply line 24: evaporation gas recovery line
25: high-pressure evaporation gas supply line 30: pump
31: boosting pump 32: high pressure pump
40: Liquefied gas heat exchanger 50: Evaporative gas compressor
50a, 50b, 50c, 50d, and 50e: first to fifth compressors
51: Temperature sensor
52, 53, 54, 55: first to fourth pressure sensors
60: Evaporative gas cooler
60a, 60b, 60c, 60d and 60e: first to fifth coolers
61, 62: first and second temperature control valves
63, 64, 65, 66: first to fourth pressure regulating valves
67: Block valve 70: Gas burner
80: Evaporative gas remelting device 90: Exhaust gas reclaiming device
91: Exhaust gas recovery line 92: Decompression valve
93: Buffer tank 211: Surplus liquefied gas discharge line
221: Evaporative gas bypass line
222, 223, 224, 225, 226: first to fifth evaporation gas return lines
227: Surplus evaporation gas discharge line 501: Cylinder
502: Piston 503: Suction valve
504: Discharge valve

Claims (9)

A vapor gas supply line connected from the liquefied gas storage tank to the high-pressure engine or the low-pressure engine; And
And a plurality of evaporative gas compressors provided on the evaporative gas supply line and configured to pressurize the evaporative gas generated in the liquefied gas storage tank in multiple stages,
Wherein at least one of the plurality of evaporative gas compressors comprises:
At least one of the plurality of suction valves is maintained in an open state when the evaporation gas is discharged at a pressure higher than a set pressure range, Wherein the liquefied gas processing system comprises: The compressor of claim 1, wherein the plurality of evaporative gas compressors comprise:
And at least one of them is a reciprocating type. 3. The reciprocating evaporative gas compressor according to claim 2, wherein the plurality of suction valves of the reciprocating evaporative gas compressor comprise:
And a pressure sensor provided on the evaporative gas supply line downstream of the reciprocating evaporative gas compressor. The pressure sensor according to claim 3,
The pressure of the evaporative gas discharged from the reciprocating evaporative gas compressor is checked,
Wherein at least one of the plurality of suction valves is forcibly kept in an open state when a pressure higher than a set pressure range is checked,
And the forcibly opened intake valve is normally operated when the set pressure range is checked. The method according to claim 1,
Further comprising a plurality of evaporative gas coolers provided on the evaporative gas supply line downstream of each of the plurality of evaporative gas compressors. 6. The method of claim 5,
Wherein the plurality of evaporative gas compressors comprise first to fifth compressors,
Wherein the plurality of evaporative gas coolers are constituted by first to fifth coolers. The method according to claim 6,
The high-pressure engine is connected to the evaporation gas supply line downstream of the fifth compressor,
And the low-pressure engine is connected to the evaporation gas supply line downstream of the second compressor. The method according to claim 1,
A liquefied gas supply line connected from the liquefied gas storage tank to the high-pressure engine;
A pump provided on the liquefied gas supply line for pressurizing the liquefied gas discharged from the liquefied gas storage tank; And
And a liquefied gas heat exchanger provided on the liquefied gas supply line between the high-pressure engine and the pump. 9. The fuel cell system according to claim 8, wherein the liquefied gas supply line between the liquefied gas heat exchanger and the high-
And a surplus liquefied gas discharge line for discharging surplus liquefied gas to the outside is provided.

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