KR20150049748A - A Treatment System of Liquefied Gas - Google Patents

Abstract

A liquefied gas treatment system according to an embodiment of the present invention comprises: an evaporated gas line connected to a liquefied gas storage tank; an evaporated gas compressor arranged in the evaporated gas line to pressurize evaporated gas generated in the liquefied gas storage tank; an evaporated gas heat exchanger arranged in the upstream of the evaporated gas compressor in the evaporated gas line to perform heat exchange of an evaporated gas collected to the evaporated gas line via the evaporated gas line and an evaporated gas supplied from the liquefied gas storage tank; an evaporated gas pressure reducer arranged in the downstream of the evaporated gas heat exchanger in the evaporated gas line to reduce the pressure of an evaporated gas heat exchanged in the evaporated gas pressure reducer; a gas-fluid separator arranged in the downstream of the evaporated gas pressure reducer in the evaporated gas line to separate a flash gas from an evaporated gas of which pressure is reduced in the evaporated gas pressure reducer; a gas collecting line connected from the gas-fluid separator to the upstream of the evaporated gas heat exchanger to supply a flash gas to the evaporated gas heat exchanger; and a nitrogen remover arranged in the gas collecting line to remove nitrogen in an evaporated gas supplied from the gas-fluid separator. A liquefied gas treatment system according to the present invention removes nitrogen from a flash gas supplied from the gas-fluid separator, supply the remaining gas to the evaporated gas compressor, and compresses the flash gas with reduced volume by removing nitrogen, thereby compression efficiency may be improved and operation costs of re-liquefying process can be reduced.

Description

Description of the Related Art A Treatment System of 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.

These liquefied gases are supplied to various customers and used. Recently, LNG carrier that uses LNG as fuel for LNG carriers that transport liquefied natural gas has been developed. The method used is applied to ships other than LNG carriers.

However, the temperature and pressure of the liquefied gas required by the customer such as the engine may be different from the state of the liquefied gas stored in the liquefied gas storage tank. Therefore, recently, research and development have been conducted on technologies for controlling the temperature and pressure of the liquefied gas stored in a liquid state to supply it to a customer.

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 method and apparatus for recovering liquefied gas after compression, And to provide a liquefied gas processing system.

A liquefied gas processing system according to an embodiment of the present invention includes an evaporation gas line connected to a liquefied gas storage tank; An evaporative gas compressor provided on the evaporative gas line for pressurizing the evaporative gas generated in the liquefied gas storage tank; And an evaporation gas supply unit for supplying the evaporation gas compressed by the evaporation gas compressor and recovered into the evaporation gas line and the evaporation gas supplied from the liquefied gas storage tank through the evaporation gas line, An evaporative gas heat exchanger for exchanging heat; An evaporative gas decompressor provided downstream of the evaporative gas heat exchanger on the evaporative gas line for reducing the evaporated gas heat-exchanged in the evaporative gas heat exchanger; A gas-liquid separator provided downstream of the evaporation gas decompressor on the evaporation gas line, the gas-liquid separator separating the flash gas from the decompressed gas in the evaporation gas decompressor; A gas recovery line connected from the gas-liquid separator to an upstream side of the evaporation gas heat exchanger to supply the flash gas to the evaporation gas heat exchanger; And a nitrogen eliminator provided on the gas recovery line for removing nitrogen in the vaporized gas supplied from the gas-liquid separator.

The gas-liquid separator may further include a nitrogen sensor provided in the gas-liquid separator to detect a nitrogen amount of the evaporated gas supplied from the gas-liquid separator. When the amount of nitrogen detected by the nitrogen detector is equal to or greater than a predetermined amount, And is supplied to the evaporation gas heat exchanger via the nitrogen remover.

Further, the present invention further includes a detour line branched from the gas recovery line and bypassing the nitrogen remover, and joining the gas recovery line, wherein when the amount of nitrogen detected by the nitrogen detector is less than a predetermined amount, evaporation And the gas is supplied to the evaporation gas heat exchanger via the bypass line.

Further, the evaporated gas heat-exchanged in the evaporative gas heat exchanger is supplied to the evaporative gas decompressor or the evaporative gas compressor.

Further, the present invention is characterized in that the evaporation gas line is provided on the evaporation gas line upstream of the evaporation gas heat exchanger, and the evaporation gas supplied from the liquefied gas storage tank and the flash gas recovered in the gas-liquid separator are mixed and supplied to the evaporation gas heat exchanger And a mixer.

The present invention further includes a liquid recovery line connected to the liquefied gas storage tank in the gas-liquid separator and adapted to recover the liquid-state evaporated gas separated by the gas-liquid separator to the liquefied gas storage tank.

The liquefied gas processing system according to the present invention can improve the compression efficiency by removing nitrogen from the flash gas supplied from the gas-liquid separator and supplying it to the evaporative gas compressor to compress the reduced flash gas by nitrogen, It is possible to reduce the operating cost of the liquefaction process.

Furthermore, as nitrogen is removed from the flash gas, the present invention reduces the flow rate of the liquefied flash gas as well as the composition of nitrogen in the liquefied gas storage tank, thereby reducing the flow rate of the evaporation gas and reducing the design capacity .

1 is a conceptual diagram of a conventional liquefied gas processing system.
2 is a conceptual diagram of a liquefied gas 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 liquefied gas processing system.

1, a conventional liquefied gas processing system 1 includes a liquefied gas storage tank 10, a customer 20, an evaporative gas compressor 50, an evaporative gas heat exchanger 60, (90), and a gas-liquid separator (100). Here, the evaporated gas heat exchanger 60, the evaporative gas compressor 50, and the customer 20 can be connected to the evaporative gas supply line 16 in the liquefied gas storage tank 10.

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 not only NG (Natural Gas) in liquid state but also NG in supercritical state for convenience, and evaporation gas can be used to include not only gaseous evaporation gas but also liquefied evaporation gas have.

The conventional liquefied gas processing system 1 pressurizes the evaporative gas generated and discharged from the liquefied gas storage tank 10 by the evaporative gas compressor 50 and supplies it to the evaporative gas heat exchanger 60 or the demander 20 Can be driven

At this time, the evaporation gas supplied from the evaporation gas compressor (50) to the evaporation gas heat exchanger (60) is heat-exchanged with the evaporation gas supplied from the liquefied gas storage tank (10) in the evaporation gas heat exchanger (60) Is decompressed in the decompressor (90), and the evaporation gas at the time of decompression is cooled.

The evaporated gas decompressed in the evaporation gas decompressor 90 is supplied to a gas-liquid separator 100 and is separated into a liquid and a gas in the gas-liquid separator 100 so that the liquid is supplied to the liquefied gas storage tank 10, Can be recovered as a flash gas to the evaporative gas heat exchanger (60) upstream of the evaporative gas compressor (50). The unexplained branch line 17, the liquid recovery line 103, and the like will be described later.

In such a conventional liquefied gas processing system 1, it is possible to supply a certain flow rate or more to the evaporating gas compressor 50 by mixing the flash gas with the evaporating gas, but the evaporating gas is re-liquefied after compression There is a problem that nitrogen is contained in the process of returning the gas to the evaporative gas compressor 50 and the compression efficiency is lowered.

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

2, a liquefied gas processing system 2 according to an embodiment of the present invention includes a liquefied gas storage tank 10, an evaporative gas compressor 50, an evaporative gas heat exchanger 60, a mixer (not shown) 70, a forced vaporizer 80, an evaporative gas decompressor 90, a gas-liquid separator 100, a nitrogen detector 110, and a nitrogen remover 120. In the embodiment of the present invention, the liquefied gas storage tank 10, the customer 20 and the like are denoted by the same reference numerals for convenience and convenience in the conventional liquefied gas processing system 1, no.

The liquefied gas storage tank (10) stores liquefied gas to be supplied to the customer (20). The liquefied gas storage tank 10 must store the liquefied gas in a liquid state, wherein the liquefied gas storage tank 10 may have the form of a pressure tank.

The liquefied gas storage tank 10 includes an outer tank (not shown), an inner tank (not shown), and a heat insulating portion (not shown). The outer tank may be formed of steel, and the inner tank may be made of stainless steel and designed to withstand a pressure of 5 bar to 10 bar (for example 6 bar). . The heat insulating portion is provided between the inner tank and the outer tank, and can prevent the external heat energy from being transmitted to the inner tank.

In this embodiment, the evaporative gas generated in the liquefied gas storage tank 10 is supplied to the evaporative gas compressor 50 to be used for heating the evaporative gas, or vaporized and pressurized by the evaporative gas, , The evaporation gas can be efficiently used.

Here, a forcing vaporizer 80 may be provided downstream of the liquefied gas storage tank 10, and the forced vaporizer 80 is operated when the flow rate of the evaporation gas is insufficient, The flow rate of the gas can be increased. That is, the forced vaporizer 80 is provided upstream of the mixer 70 on the evaporation gas supply line 16 to vaporize the liquefied gas in the liquefied gas storage tank 10 and supply it to the evaporative gas compressor 50 in the gaseous liquefied gas Can be supplied. Here, the evaporation gas supply line 16 and the branch line 17, which will be described later, may be referred to as evaporation gas lines.

The customer 20 is driven through evaporative gas supplied from the liquefied gas storage tank 10 and flash gas to generate power. At this time, the customer 20 is a high-pressure engine and may be a MEGI engine.

As the piston 20 (not shown) in the cylinder (not shown) reciprocates by the combustion of the liquefied gas, the consumer 20 rotates the crankshaft (not shown) connected to the piston and is connected to the crankshaft A shaft (not shown) can be rotated. Therefore, as the propeller (not shown) connected to the shaft rotates when the consumer 20 is driven, the hull can move forward or backward.

Of course, in this embodiment, the customer 20 may be an engine for driving the propeller, but it may be an engine for generating power or an engine for generating other power. In other words, the present embodiment does not particularly limit the kind of the consumer 20. However, the customer 20 may be an internal combustion engine that generates a driving force by the combustion of the evaporative gas and the flash gas.

The consumer 20 is supplied with the evaporated gas and flash gas pressurized by the evaporative gas compressor 50 to obtain the driving force. The state of the evaporative gas and the flash gas supplied to the consumer 20 may vary depending on the state required by the consumer 20.

Or the customer 20 may be a dual fuel engine in which a mixture of the evaporation gas and the oil is not supplied and the evaporation gas or oil is selectively supplied. The dual fuel engine is selectively supplied with the evaporation gas or oil in order to prevent the mixing of the two materials having different combustion temperatures to prevent the efficiency of the consumer 20 from deteriorating.

The evaporator gas supply line 16 for transferring the evaporation gas may be installed between the liquefied gas storage tank 10 and the customer 20 and the forced vaporizer 80 and the mixer 70 may be installed in the evaporation gas supply line 16. [ An evaporation gas heat exchanger 60, an evaporation gas compressor 50, and the like, so that the evaporation gas can be supplied to the customer 20. At this time, a fuel supply valve (not shown) is provided in the evaporation gas supply line 16 so that the supply amount of the evaporation gas can be adjusted according to the adjustment of the opening degree of the fuel supply valve.

The evaporative gas compressor (50) pressurizes the evaporative gas generated in the liquefied gas storage tank (10). The evaporation gas compressor 50 can pressurize the evaporation gas generated and discharged from the liquefied gas storage tank 10 and supply the evaporation gas to the evaporation gas heat exchanger 60 or the consumer 20.

The plurality of evaporation gas compressors (50) can pressurize the evaporation gas at multiple stages. For example, five evaporation gas compressors 50 may be provided so that the evaporation gas is pressurized in five stages. The five-stage pressurized gas can be pressurized to 200 to 400 bar and supplied to the customer 20.

Here, the branch line 17 that branches off from the evaporation gas supply line 16 may be provided downstream of any one of the evaporative gas compressors 50, and the branch line 17 may be connected to the evaporation gas heat exchanger 60 Liquid separator 100, as shown in FIG. At this time, a valve (not shown) may be provided on the evaporation gas supply line 16 at the branching point of the branch line 17 in the evaporation gas supply line 16, The flow rate of the gas or the flow rate of the evaporation gas supplied to the evaporation gas heat exchanger 60 through the evaporation gas compressor 50, and can 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.

As the evaporation gas compressor 50 pressurizes the evaporation gas, the evaporation gas can be in a state where the pressure rises and the boiling point rises and can be liquefied even at a relatively high temperature. 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.

The evaporation gas heat exchanger 60 is provided between the liquefied gas storage tank 10 and the evaporation gas compressor 50 on the evaporation gas supply line 16 and is provided between the evaporation gas pressurized in the evaporation gas compressor 50 and the liquefied gas storage The evaporation gas supplied from the tank 10 can be heat-exchanged. The evaporated gas heat-exchanged in the evaporative gas heat exchanger (60) may be supplied to the evaporative gas decompressor (90) or the evaporative gas compressor (50). That is, the evaporated gas recovered to the evaporation gas decompressor 90 and the evaporation gas newly supplied from the liquefied gas storage tank 10 after being multi-stage pressurized by the evaporation gas compressor 50 are heat-exchanged in the evaporation gas heat exchanger 60 do.

The mixer 70 is provided upstream of the evaporation gas heat exchanger 60 on the evaporation gas supply line 16 and is supplied with the flash gas that is supplied from the liquefied gas storage tank 10 and is recovered in the gas- Can be introduced. The mixer (70) may be in the form of a pressure tank, which is space for storing the evaporating gas and the flash gas. Here, the evaporated gas and the flash gas mixed in the mixer 70 are supplied to the evaporative gas heat exchanger 50.

The evaporation gas decompressor (90) is pressurized in the evaporation gas compressor (50) to reduce the evaporated gas heat exchanged in the evaporation gas heat exchanger (60). For example, the evaporation gas decompressor 90 can reduce the pressure of the evaporation gas to 1 to 10 bar, and the evaporation gas can be liquefied and reduced to 1 bar when it is transferred to the liquefied gas storage tank 10, The cooling effect can be achieved.

Here, the evaporated gas pressurized in the evaporative gas compressor (50) is cooled by heat exchange with the evaporated gas supplied from the liquefied gas storage tank (10) in the evaporative gas heat exchanger (60) The discharge pressure can be maintained. In the present embodiment, the evaporation gas is decompressed by using the evaporation gas decompressor 90 so that the evaporation gas is cooled, and the evaporation gas can be liquefied. At this time, the greater the pressure range to be depressurized, the greater the cooling effect of the evaporative gas. For example, the evaporative gas decompressor 90 may reduce the evaporated gas pressurized to 300 bar by the evaporative gas compressor 50 to 1 bar.

The evaporative gas decompressor 90 may be a line Thompson valve. Alternatively, the evaporative gas decompressor 90 may comprise an expander. In the case of the Row Thompson valve, depressurization can effectively cool the evaporated gas so that at least some of the evaporated gas is liquefied.

On the other hand, the inflator can be driven without using any extra power, and in particular, the efficiency of the liquefied gas processing system 2 can be improved by utilizing the generated power as electric power for driving the evaporative gas compressor 50. The power transmission may be accomplished by, for example, a gear connection or an electric conversion and the like.

The gas-liquid separator 100 separates the gas from the decompressed gas in the gas-decompressing device 90. In the gas-liquid separator 100, the evaporated gas is separated into a liquid and a gas so that the liquid is supplied to the liquefied gas storage tank 10, and the gas can be recovered as flash gas upstream of the evaporative gas compressor 50.

Here, the evaporation gas supplied to the gas-liquid separator 100 may be decompressed and cooled in the evaporation gas decompressor 90. For example, in the evaporative gas compressor (50), the evaporation gas may be multi-stage pressurized to have a pressure of 200 bar to 400 bar, and the temperature may be around 45 degrees. The evaporated gas raised to a temperature of about 45 degrees is recovered by the evaporation gas heat exchanger 60 and is heat-exchanged with the evaporation gas of about -100 degrees supplied from the liquefied gas storage tank 10, And is supplied to the evaporation gas decompressor 90. At this time, in the evaporating gas decompressor 90, the evaporation gas is cooled by the reduced pressure and can have a pressure of about 1 bar and a temperature of about -162.3 degrees.

As described above, in this embodiment, since the evaporation gas supplied to the gas-liquid separator 100 is reduced in pressure by the evaporation gas decompressor 90 to have a temperature lower than -162 degrees, about 30 to 40% of the evaporation gas can be liquefied have.

In this embodiment, the liquefied evaporated gas is recovered to the liquefied gas storage tank 10, and the flash gas generated in the gas-liquid separator 100 is recovered into the mixer 70 without discarding the evaporated gas and the flash gas, The gas can be supplied to the customer 20 after being pressurized through the gas compressor 50.

Liquid separator 100 separates the evaporated gas into a liquid and a gas, the liquefied evaporated gas and the flash gas are respectively supplied to the liquefied gas storage tank 10 and the mixer 10 through the liquid recovery line 103 and the gas recovery line 101, (70). ≪ / RTI >

The liquid recovery line 103 is connected from the gas-liquid separator 100 to the liquefied gas storage tank 10 to recover the vaporized liquid state to the liquefied gas storage tank 10 and the gas recovery line 101 is connected to the gas- 100 to the mixer 70 upstream of the evaporative gas compressor 50 to recover the flash gas upstream of the evaporative gas compressor 50 to prevent the flash gas from being wasted and wasted.

In this case, the flash gas may be cooled to -162.3 degrees by being decompressed by the evaporation gas decompressor 90 as described above. The flash gas and the -100 degree evaporation gas generated in the liquefied gas storage tank are mixed in the mixer 70 And flows into the evaporation gas heat exchanger 60 as evaporation gas of -110 to -120 degrees (about-114 degrees).

Therefore, the 45-degree evaporated gas recovered along the evaporated gas supply line 16 branched from the evaporated gas compressor 50 and the consumer 20 and connected to the evaporated gas heat exchanger 60 is discharged from the evaporated gas heat exchanger 60 And can be cooled by heat exchange with evaporation gas of -110 to -120 degrees. This allows additional cooling of the evaporated gas to be achieved when the flash gas is not recovered (45 degrees of evaporation gas versus -100 degrees of evaporation and heat exchange).

Accordingly, the evaporated gas discharged from the evaporated gas heat exchanger 60 and flowing into the evaporated gas decompressor 90 may be about -112 degrees lower than the case where no flash gas circulates (about -97 degrees), and the evaporated gas When the pressure is reduced by the pressure reducer 90, it can be cooled to about -163.7 degrees. In this case, more evaporative gas can be liquefied by the evaporative gas decompressor 90 than in the case where there is no circulation of the flash gas and can be recovered to the liquefied gas storage tank 10.

 Therefore, in this embodiment, the vaporized gas in the gaseous state in the evaporated gas cooled through the evaporated gas decompressor 90 is separated into flash gas in the gas-liquid separator 100 and supplied to the evaporated gas heat exchanger 60, The liquefaction efficiency of the evaporation gas can be increased to 60% or more by sufficiently lowering the temperature of the evaporation gas recovered from the compressor 50 to the evaporation gas heat exchanger 60 and the evaporation gas decompressor 90.

In this embodiment, not only the evaporated gas from the liquefied gas storage tank 10 but also the flash gas is mixed with the evaporated gas and flows into the evaporated gas compressor 50, so that a constant flow rate or more is supplied to the evaporated gas compressor 50 So that the driving efficiency can be improved.

The nitrogen eliminator 120 is provided on the gas recovery line 101 and removes nitrogen in the evaporated gas supplied from the gas-liquid separator 100 to supply the reduced flash gas to the mixer 70 and the evaporative gas heat exchanger 60 And then supplied to the evaporative gas compressor (50). For example, the nitrogen remover 120 can remove nitrogen using an adsorbent, and CMS (Carbon Molecular Sieve) can be used as the adsorbent.

The flash gas whose nitrogen is reduced by the nitrogen remover 120 can be supplied to the customer 20 via the evaporative gas compressor 50 or can be recovered to the gas-liquid separator 100 via the branch line 17.

The flash gas introduced into the evaporative gas compressor 50 can be improved in compression efficiency of the evaporative gas compressor 50 as nitrogen is reduced, and the volume of the flash gas is reduced corresponding to the decrease of nitrogen. When the flash gas is recovered to the gas-liquid separator 100 via the branch line 17, the flow rate of liquefied flash gas is reduced, and as the composition of nitrogen in the liquefied gas storage tank 10 is reduced, The flow rate of the gas can also be reduced and the design capacity can be reduced.

Here, the detection of nitrogen removed by the nitrogen remover 120 may be performed by the nitrogen detector 110, and the nitrogen detector 110 may be provided in the gas-liquid separator 100 so that the nitrogen amount of the evaporation gas supplied from the gas- Lt; / RTI > The nitrogen sensor 110 is a gas sensor and can measure the nitrogen amount by a change in resistance value or current.

The bypass line 102 may be provided in the gas recovery line 101 and the bypass line 102 may be branched at the gas recovery line 101 to bypass the nitrogen purifier 120 to the gas recovery line 101 And the flash gas supplied from the gas-liquid separator 100 can be supplied to the mixer 70 by bypassing the nitrogen remover 120.

At this time, a valve such as a three-way valve is provided on the bypass line 102 branched from the gas recovery line 101 so that the flow rate of the flash gas supplied to the mixer 70 through the nitrogen remover 120, The flow rate of the flash gas supplied to the mixer 70 can be adjusted.

In the present embodiment, when the amount of nitrogen detected by the nitrogen sensor 110 is equal to or greater than a predetermined amount, the evaporated gas supplied from the gas-liquid separator 100 is supplied to the evaporation gas heat exchanger 60 via the nitrogen remover 120, Liquid separator 100 may be supplied to the evaporative gas heat exchanger 60 via the bypass line 102 when the amount of nitrogen detected by the evaporator 110 is less than a predetermined amount.

In the present embodiment, the gas recovery line 101 is described as being provided up to the mixer 70 so as to be connected to the upstream of the evaporative gas compressor 50. Alternatively, the gas recovery line 101 may include a plurality of evaporative gas compressors (Not shown). For example, the gas recovery line 101 is connected to the rear end of the first stage evaporative gas compressor 50 in the evaporative gas compressor 50 in the five-stage evaporative gas compressor 50 to supply the nitrogen-depleted flash gas It is possible.

As described above, this embodiment removes nitrogen from the flash gas supplied from the gas-liquid separator 100 and supplies it to the evaporative gas compressor 50 to compress the flash gas whose volume is reduced by nitrogen, thereby improving the compression efficiency The operation cost of the liquefaction process can be reduced.

1,2: liquefied gas processing system 10: liquefied gas storage tank
16: Evaporative gas supply line 17: Branch line
20: Demand source 50: Evaporative gas compressor
60: Evaporative gas heat exchanger 70: Mixer
80: forced vaporizer 90: evaporative gas decompressor
100: gas-liquid separator 101: gas recovery line
102: bypass line 103: liquid recovery line
110: Nitrogen sensor 120: Nitrogen remover

Claims (6)

An evaporative gas line connected to the liquefied gas storage tank;
An evaporative gas compressor provided on the evaporative gas line for pressurizing the evaporative gas generated in the liquefied gas storage tank;
And an evaporation gas supply unit for supplying the evaporation gas compressed by the evaporation gas compressor and recovered into the evaporation gas line and the evaporation gas supplied from the liquefied gas storage tank through the evaporation gas line, An evaporative gas heat exchanger for exchanging heat;
An evaporative gas decompressor provided downstream of the evaporative gas heat exchanger on the evaporative gas line for reducing the evaporated gas heat-exchanged in the evaporative gas heat exchanger;
A gas-liquid separator provided downstream of the evaporation gas decompressor on the evaporation gas line, the gas-liquid separator separating the flash gas from the decompressed gas in the evaporation gas decompressor;
A gas recovery line connected from the gas-liquid separator to an upstream side of the evaporation gas heat exchanger to supply the flash gas to the evaporation gas heat exchanger; And
And a nitrogen eliminator provided on the gas recovery line for removing nitrogen in the evaporation gas supplied from the gas-liquid separator. The method according to claim 1,
Further comprising a nitrogen sensor provided in the gas-liquid separator and sensing a nitrogen amount of the evaporation gas supplied from the gas-liquid separator,
Wherein when the amount of nitrogen detected by the nitrogen detector is equal to or greater than a predetermined amount, the evaporation gas supplied from the gas-liquid separator is supplied to the evaporation gas heat exchanger via the nitrogen remover. 3. The method of claim 2,
Further comprising a bypass line that branches off from the gas recovery line and bypasses the nitrogen removal unit to join the gas recovery line,
Wherein when the amount of nitrogen detected by the nitrogen detector is less than a predetermined amount, the vaporized gas supplied from the gas-liquid separator is supplied to the vaporized gas heat exchanger via the bypass line. The method according to claim 1,
The evaporated gas heat-exchanged in the evaporating gas heat exchanger is supplied to the evaporator
And the gas is supplied to the evaporative gas decompressor or the evaporative gas compressor. The method according to claim 1,
Further comprising a mixer provided upstream of the evaporation gas heat exchanger on the evaporation gas line for mixing the evaporation gas supplied from the liquefied gas storage tank with the flash gas recovered from the gas-liquid separator and supplying the mixture to the evaporation gas heat exchanger Wherein the liquefied gas processing system comprises: The method according to claim 1,
Further comprising a liquid recovery line connected to the liquefied gas storage tank in the gas-liquid separator to recover the liquid-state evaporated gas separated in the gas-liquid separator to the liquefied gas storage tank.

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