KR20190078921A - Boil Off Gas Treating Method and Liquefied Gas Regasification System - Google Patents

Abstract

The present invention relates to a liquefied gas re-gasification system and an evaporation gas treatment method, which can effectively process evaporation gas generated at a liquefied gas re-gasification facility regardless of a capacity for liquefied gas re-gasification. To this end, the evaporation gas treatment method comprises: a step of supplying liquefied gas and evaporation gas to be re-gasified to a re-condenser so as to condense the evaporation gas by a cold energy of the liquefied gas; and a step of supplying the liquefied gas in a liquid state from the re-condenser to a high pressure pump to compress the same, before gasifying the compressed liquefied gas to supply the same to a gas demand. Here, the re-condenser is provided with the flow amount of the liquefied gas required for re-condensing the evaporation gas, and, when the flow amount of the liquefied gas supplied from the re-condenser to the high pressure pump exceeds a gas demand amount required by the gas demand, the amount of the liquefied gas exceeding the gas demand amount is recovered to a liquefied gas storage tank.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a liquefied gas regeneration system,

The present invention relates to a liquefied gas regasification system and a method of treating a vaporized gas, which enables the vaporized gas produced in a liquefied gas regasification system to be effectively treated regardless of the liquefied gas regeneration capacity.

Generally, natural gas is made in the form of Liquefied Natural Gas (LNG) liquefied at the cryogenic temperature at the place of production, and then transported over a long distance to the destination by an LNG carrier. LNG is obtained by cooling natural gas to a cryogenic temperature of about -163 ° C at normal pressure, and its volume is reduced to about 1/600 of that of natural gas, making it well suited for long distance transportation through the sea.

LNG transported by an LNG carrier can be vaporized either onshore or offshore and can be supplied to the offshore gas demand. Regeneration vessels that receive LNG from LNG carriers and re-emit them at sea and supply them to gas demand include LNG Regasification Vessel (LNG Regasification Vessel) or LNG FSRU (Floating Storage and Regasification (Hereinafter referred to as "LNG regasification vessel").

Generally, the regeneration equipment installed in the LNG regasification vessel is a high pressure pump that compresses the low pressure LNG stored in the LNG storage tank to a pressure required by the gas demanding place, a heat transfer medium such as a seawater, and a high pressure vaporizer that heats and vaporizes to a required temperature in a regas network using a heating medium. The regasification gas, which is vaporized through the high-pressure pump and the vaporizer, is delivered to the gas consumer through the gas pipeline.

LNG regeneration LNG storage tanks installed in vessels are stored at a cryogenic temperature of about -163 ° C. The LNG storage tank is thermally insulated so that the LNG can be maintained in a liquid state. However, even if the LNG storage tank is adiabatically treated, the LNG is spontaneously vaporized by external heat invasion or the like. When the LNG is spontaneously vaporized and boil-off gas (BOG) is continuously generated, the pressure of the LNG storage tank is increased.

If the pressure of the LNG storage tank rises excessively, there is a risk of explosion. If the pressure of the LNG storage tank exceeds the set value, the safety valve is opened to discharge the evaporation gas from the LNG storage tank to the outside.

In the LNG regasification vessel, the evaporated gas discharged from the LNG storage tank is re-condensed by using the cold heat of the LNG, supplied to the high-pressure pump and the vaporizer together with the LNG to be regasified, regenerated and supplied to the gas consumer.

At this time, since the evaporation gas is recycled using the cold heat of the LNG to be regasified, the capacity of the evaporation gas to be recycled is proportional to the amount of LNG to be regasified. That is, the evaporation gas can be recycled and processed only when the flow rate of the LNG to be regasified is sufficient to recondense the evaporated gas discharged from the LNG storage tank.

If the LNG regasification vessel is not capable of condensing the condensate due to the lack of sufficient cold heat from the LNG due to the reduced regeneration capacity, or the evaporation gas generated when the re-condensation is not carried out, it can be recovered to the LNG storage tank. In addition, the amount of evaporative gas that can not be recovered to the LNG storage tank beyond the pressure level acceptable to the LNG storage tank can be supplied as fuel to the engine.

However, the amount of evaporative gas exceeding the amount that can be accommodated in the LNG storage tank and exceeding the amount of fuel required by the engine can be supplied to the GCU (Gas Combustion Unit), burned or treated, or vented to the atmosphere There is nothing.

Since the evaporation gas is mainly composed of methane having the highest boiling point among components constituting the LNG, it is an enormous economic loss when the evaporation gas is burnt to be treated or vented.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention Accordingly, the present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to solve the above problems and to provide a process for recycling the liquefied gas, which does not waste the volatile gas, A liquefied gas regeneration system, and a vaporized gas treatment method.

According to an aspect of the present invention, there is provided a method of regenerating an evaporator, comprising: supplying a re-condensed liquefied gas and an evaporated gas to a re-condenser to condense the evaporated gas by cooling the liquefied gas; And supplying the liquefied gas in a liquid state from the re-condenser to a high-pressure pump, compressing the compressed liquefied gas, and vaporizing the compressed liquefied gas to supply it to the gas consumer, wherein the recondenser includes a flow rate When the flow rate of the liquefied gas supplied from the re-condenser to the high-pressure pump exceeds the gas demand amount required by the gas consumer, the liquefied gas in an amount exceeding the gas demand amount is recovered to the liquefied gas storage tank A method of treating an evaporative gas in a liquefied gas regasification system is provided.

Preferably, the flow rate control of the liquefied gas supplied to the recondenser further comprises: measuring the pressure of the recondenser; and if the pressure of the recondenser exceeds a set value, increasing the flow rate of the liquefied gas supplied to the recondenser .

Preferably, if the pressure of the recondenser exceeds a set value, the flow rate of the liquefied gas recovered from the recondenser to the liquefied gas storage tank can be increased.

Preferably, if the pressure of the recondenser is lower than the set value, the regrounding gas supplied to the gas consumer can be recovered to the recondenser.

Preferably, if the pressure of the recondenser exceeds a set value, it is possible to recover the vaporized gas from the recondenser to the liquefied gas storage tank.

According to another aspect of the present invention, there is provided a recuperator comprising: a recondenser for condensing evaporated gas into cold heat of a re-circulating liquefied gas; A high-pressure pump for discharging the liquid-state liquefied gas from the recondenser and compressing it at a high pressure; A vaporizer for vaporizing a liquefied gas compressed at a high pressure and supplying the liquefied gas to a gas consumer; A re-liquefaction line branching between the recondenser and the high-pressure pump, for allowing the liquefied gas supplied from the recondensor to the high-pressure pump to be recovered to the liquefied gas storage tank; A second pressure transmitter for measuring the pressure of the recondenser; And a fifth valve installed in the refueling line, the fifth valve being controlled by the measured value of the second pressure transmitter.

Preferably, a second valve installed between the liquefied gas storage tank and the recondenser, the second valve being controlled by the measured value of the second pressure transmitter.

Preferably, the second valve and the fifth valve are controlled such that when the measured value of the second pressure transmitter exceeds a set value, the second valve and the fifth valve are further opened, The amount of gas to be supplied from the recondenser to the high-pressure pump is regulated so that the amount of gas required for condensing is supplied to the recondenser, And a controller for controlling the opening amount of the second valve so that the amount of the liquefied gas is recovered to the liquefied gas storage tank.

Preferably, the apparatus further comprises a level transmitter for measuring the level of the re-condenser, wherein the controller is configured to calculate the opening amount of the second valve and the fifth valve using the measured values of the second pressure transmitter and the level transmitter, Can be adjusted.

According to the liquefied gas regasification system and the evaporation gas treatment method of the present invention, even when the flow rate of the liquefied gas to be regasified is not sufficient to recondense the evaporation gas, the evaporation gas can be recycled without waste It is possible to efficiently recover the evaporated gas without wasting it.

Further, by effectively treating the evaporation gas, the internal pressure of the liquefied gas storage tank can be kept constant within the safety range, and the amount of LNG discharged can be reduced.

In addition, the amount of reconditioning of the evaporated gas can be efficiently controlled regardless of the re-condensation capacity, and the pressure of the re-condenser can be kept constant within the safe range.

1 is a schematic view showing a liquefied gas regeneration system according to an embodiment of the present invention.

In order to fully understand the operational advantages of the present invention and the objects attained by the practice of the present invention, reference should be made to the accompanying drawings, which illustrate preferred embodiments of the present invention, and to the contents of the accompanying drawings.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, like reference numerals refer to like elements throughout. The same elements are denoted by the same reference numerals even though they are shown in different drawings. In addition, the following examples can be modified in various forms, and the scope of the present invention is not limited to the following examples.

The liquefied gas may be a liquefied natural gas (LNG), a liquefied ethane gas (LEG), or a liquefied petroleum gas (LPG) Gas, liquefied ethylene gas, liquefied propylene gas, and the like. Alternatively, it may be a liquid gas such as liquefied carbon dioxide, liquefied hydrogen, or liquefied ammonia. However, in the following embodiments, LNG, which is a typical liquefied gas, is applied will be described as an example.

LNG is mainly composed of methane, and includes ethane, propane, butane, etc., and its composition may vary depending on the place of production.

Also, in one embodiment of the present invention, the LNG regasification vessel may be any type of ship equipped with an LNG regeneration facility capable of regenerating LNG and supplying it to a gas demanding place, that is, an LNG RV (Regasification Vessel) And floating structures that do not have propelling capabilities, such as floating storage regasification units (LNG FSRUs), but float at sea. However, in the following embodiments, the LNG FSRU will be described as an example.

Also, the LNG regasification vessel according to an embodiment of the present invention is characterized in that the LNG is regasified at sea and the regasification gas is supplied to a demand place of gas on the land via a pipe network.

In addition, the LNG regeneration system and method according to an embodiment of the present invention will be described as an example applied to a ship, but may also be applied on the land.

1 is a schematic view illustrating an LNG regeneration system according to an embodiment of the present invention. Hereinafter, an evaporative gas treatment method of an LNG regeneration system and a regeneration system according to an embodiment of the present invention will be described with reference to FIG.

1, the LNG regeneration system according to an embodiment of the present invention includes an LNG storage tank 100 for storing LNG; A high pressure pump 200 for compressing the LNG to be regenerated and supplying it to the vaporizer 300; And a vaporizer (300) for vaporizing the compressed LNG and supplying it to a gas consumer.

The LNG storage tank 100, the high-pressure pump 200, the vaporizer 300, and the gas consumer of the present embodiment are connected by a regasification line (VL), and the LNG is regenerated along the regasification line (VL) , And is transferred from the LNG storage tank 100 to the gas consumer.

In the present embodiment, the LNG to be regasified is stored in the LNG storage tank 100. However, the present invention is not limited thereto. For example, the LNG regasification system may not include an LNG storage tank.

It is preferable that the LNG storage tank 100 of the present embodiment is heat-treated so that the LNG can be stored while being maintained in a liquid state. In this embodiment, the LNG may be stored in the LNG storage tank 100 at about 0.05 bar, about -161.3 ° C. Or from about 1.1 bar to about -163 < 0 > C.

Although FIG. 1 illustrates only one LNG storage tank 100, at least one LNG storage tank 100 of the present embodiment may be provided.

The LNG storage tank 100 of the present embodiment may be provided with an LNG supply pump (not shown) for transferring the LNG from the LNG storage tank 100 to the high-pressure pump 200. The LNG supply pump may be a semi-submerged pump installed inside the LNG storage tank, or may be installed outside the LNG storage tank.

Also, even if the LNG storage tank 100 is adiabatically treated, the LNG can be spontaneously vaporized by external heat penetration in the LNG storage tank 100 to generate boil-off gas (BOG). Therefore, the LNG storage tank 100 may be designed to withstand a pressure rise caused by the evaporation gas generated in the LNG storage tank 100 to a set pressure. When the internal pressure of the storage tank exceeds the set pressure, And may be designed to discharge the vaporized gas in the LNG storage tank 100 to the outside of the LNG storage tank 100. [

In the present embodiment, the LNG storage tank 100 is connected to the evaporation gas line BL through which the evaporated gas discharged from the LNG storage tank 100 flows. According to the present embodiment, the evaporated gas discharged from the LNG storage tank 100 along the evaporation gas line BL is supplied to the recondenser 150, which will be described later, and is condensed by the cold heat of the LNG to be re- (VL).

The evaporated gas discharged from the LNG storage tank 100 along the evaporated gas line BL can be supplied to the engine as fuel or burned in a gas combus- tion unit (GCU).

However, in the present embodiment, it is preferable that the evaporation gas is preferentially supplied to the recondenser 150 or the engine, and supplied to the recondenser 150 and the engine, and the remaining evaporation gas is supplied to the GCU.

The evaporation gas line (BL) is connected from the LNG storage tank (100) to the recondenser (150). Further, the evaporation gas line BL includes a first evaporation gas branch line BL1 branched from the evaporation gas line BL and connected to the engine DFDE; And a second evaporative gas branch line BL2 connected to the GCU.

The engine of this embodiment can be a power generation engine that is installed in an LNG regeneration vessel and can use LNG as fuel, and can be installed in the ship more than one.

In this embodiment, the power generation engine may be a dual fuel diesel electric (DFDE) engine. The DFDE engine uses four-stroke (4-stroke) cycles and is mainly used for power generation. The DFDE engine also employs an otto cycle in which a low pressure natural gas of about 2 bar to 8 bar, or about 6.5 bar is injected into the combustion air inlet to compress the piston as it rises.

According to the present embodiment, the apparatus further includes a low-pressure compressor (400) for compressing the evaporated gas discharged along the evaporation gas line (BL) to a low pressure.

The evaporated gas is discharged from the LNG storage tank 100 along the evaporation gas line BL and is compressed in the low pressure compressor 400 and all or most of the compressed evaporation gas is supplied to the recondenser 150, The remaining compressed vaporized gas supplied to the first evaporated gas branch line BL1 may be branched to the first evaporated gas branch line BL1 and supplied to the fuel of the engine. Alternatively, all or most of the compressed evaporative gas is branched into the first evaporative gas branch line BL1 and supplied to the fuel of the engine, and a quantity of compressed evaporative gas exceeding the amount of fuel required by the engine is supplied to the evaporative gas line BL And then supplied to the recondenser 150.

The low pressure compressor 400 may compress the evaporation gas to a pressure required by the engine, that is, a pressure of about 2 bar to 8 bar, or about 6.5 bar, which is the pressure required by the DFDE engine in this embodiment.

According to the present embodiment, the apparatus further includes a recondenser (150) for condensing the compressed evaporated gas compressed at the low pressure in the low pressure compressor (400) using the cold heat of the LNG to be regenerated.

The recondenser 150 is connected to the evaporation gas line BL and the regasification line VL, as shown in Fig.

In the recondenser 150, the compressed evaporation gas conveyed along the evaporation gas line BL and the LNG to be regasified conveyed from the LNG storage tank 100 along the regasification line VL are mixed, and the cooling heat of the LNG The evaporation gas is condensed.

The condensed vaporized gas recycled by the cooling of the LNG and LNG delivered from the recondenser 150, that is, the LNG transferred from the LNG storage tank 100 along the regasification line VL to the recondenser 150, Pressure pump 200. The high- Hereinafter, the term 'LNG to be regasified' can be interpreted as a concept including condensed evaporative gas condensed in the recondenser (150).

The high-pressure pump 200 of this embodiment compresses the LNG to be regenerated, which is transferred from the recondenser 150, to a high pressure. Here, the high pressure is a pressure higher than the critical pressure of the LNG, and may be a pressure required by the gas consumer. For example, the pressure required by a gas consumer may be 30-40 barg, or 50-70 barg, or 100 barg.

In this embodiment, by compressing the LNG to be vaporized to a pressure higher than the critical pressure of the LNG, heat exchange efficiency in the vaporizer 300 can be increased. That is, the LNG compressed by the high-pressure pump 200 and transferred to the vaporizer 300 may be in a supercritical state.

The vaporizer 300 of the present embodiment vaporizes the LNG compressed at high pressure by the high-pressure pump 200 by heat exchange with the heating medium.

As described above, the high-pressure LNG transferred from the high-pressure pump 200 to the vaporizer 300 may be in a supercritical state. Thus, in the present specification, 'vaporizing' means not only a phase change from a liquid phase to a gaseous phase but also a movement of heat energy from a heating medium to an LNG, that is, an LNG receives heat energy from a heating medium, .

In this embodiment, the heating medium may be seawater, fresh water or glycol water. In the present embodiment, it is assumed that the heating medium supplied to the vaporizer 300 is seawater.

The regasification gas vaporized in the vaporizer 300 is supplied to the gas consumer along the regasification line VL.

The LNG regasification system according to the present embodiment is configured such that part or all of the LNG to be regenerated which is branched from the regeneration line VL and is conveyed from the recondenser 150 to the high pressure pump 200 is supplied to the LNG storage tank 100, And a redistribution line RL connected to the LNG storage tank 100 so as to be recovered to the LNG storage tank 100.

The LNG regeneration system according to the present embodiment further includes an LNG storage tank 100 for controlling the pressure of the recondenser 150, A third evaporation gas branch line BL3 connected to the third evaporation gas branch line BL3; And a gas recovery line (RL1) connected to the recondenser (150) and connected to the recondenser (150).

The recondenser 150 of this embodiment is connected to the re-condensation line VL, the evaporation gas line BL, the third evaporation gas branch line BL3 and the gas recovery line RL1, By controlling the transfer of the fluid through each line, the pressure, water level, etc. of the recondenser 150 are controlled.

According to the present embodiment, a first valve (V1) installed in the evaporation gas line (BL) for controlling the fluid transportation of each line and controlled to be opened and closed and controlled by the control of a control unit described later; A second valve (V2) installed in the regeneration line (VL) and controlled by opening and closing by a control unit; A third valve (V3) installed in the third evaporative gas branch line (BL3) and controlled by opening and closing by a control unit; A fourth valve (V4) installed in the gas recovery line (RL1) and controlled by opening and closing by a control unit; And a fifth valve (V5) installed in the liquid refilling line (RL), the opening and closing of which is controlled by a control unit and the opening amount thereof is controlled.

Also, a first pressure transmitter (PT1) for measuring the pressure of the LNG storage tank (100) to control each valve; A level transmitter LT1 for measuring the level of the re-condenser 150; And a second pressure transmitter (PT2) for measuring the pressure of the recondenser (150).

In addition, a control unit for controlling the first to fifth valves V1, V2, V3, V4, V5 using the measured values of the first pressure transmitter PT1, the level transmitter LT1 and the second pressure transmitter PT2, ; ≪ / RTI >

The control unit controls the first valve V1 and controls the flow rate of the compressed evaporative gas to be supplied from the LNG storage tank 100 to the recondenser 150 by controlling the first valve V1 by a tank pressure controller PIC1, cargo tank pressure controller); A recondenser pressure controller (PIC2) for controlling the second valve V2 and controlling the flow rate of the LNG to be supplied from the LNG storage tank 100 to the recondenser 150 by controlling the second valve V2, ; A recondenser overpressure controller (PIC3), which controls the third valve (V3) and discharges non-recondensed gaseous vapor from the re-condenser (150) by controlling the third valve (V3); A recondenser underpressure controller (PIC4) for controlling the fourth valve (V4) and re-supplying the regeneration gas supplied to the gas consumer by controlling the fourth valve (V4) to the recondenser (150); Some or all of the LNG to be regenerated to be transferred from the recondenser 150 to the high-pressure pump 200 by controlling the fifth valve V5 is supplied to the LNG storage tank 100 And a recondenser overpressure protection controller (PIC 5) to be recycled.

The control unit controls the flow rate of the LNG to be regasified, that is, the regeneration of the regeneration gas, by controlling the first valve V1, the second valve V2, the third valve V3, the fourth valve V4 and the fifth valve V5 The amount of evaporation gas to be recycled, the flow rate of the LNG necessary for recirculating the evaporated gas, the pressure in the recondenser 150, and the level of the liquid level.

Hereinafter, an evaporative gas treatment method of the LNG regasification system according to an embodiment of the present invention will be described with reference to FIG. 1, and the LNG regeneration system according to an embodiment of the present invention.

First, LNG to be regasified is supplied from the LNG storage tank 100 to the recondenser 150 by using the LNG supply pump in order to regenerate the LNG and supply it to the gas consumer.

At this time, the tank pressure controller PIC1 controls the first valve V1 in accordance with the pressure measurement value of the LNG storage tank 100 transmitted from the first pressure transmitter PT1, and controls the first valve V1 from the LNG storage tank 100 And supplies the evaporated gas to the recondenser 150.

According to the present embodiment, the tank pressure controller PIC1 controls all of the remaining evaporation gas supplied to the fuel of the engine among the evaporated gas discharged by an amount exceeding the set pressure of the LNG storage tank 100, The amount of opening of the first valve V1 is controlled.

In the recondenser 150, the evaporated gas transferred to the recondenser 150 through the evaporation gas line BL is condensed by the cooling heat of the LNG to be regasified.

The liquid, that is, the LNG to be regenerated from the recondenser 150 is transferred to the high-pressure pump 200, the high-pressure pump 200 compresses the LNG to be regenerated and supplies it to the vaporizer 300, , LNG to be regasified is regenerated and supplied to the gas consumer.

At this time, the control unit maintains the water level and the pressure of the re-condenser 150 within the set range.

The control unit receives the measured values of the level transmitter LT1 and the second pressure transmitter PT2 and controls the second valve V2. That is, when the water level of the recondenser 150 is lower than the set value, the second valve V2 is opened to allow a larger amount of LNG to flow into the recondenser 150. [ When the water level of the recondenser 150 is equal to or higher than the set value, the opening amount of the second valve V2 is reduced to maintain the water level of the recondenser 150 in the set range.

The control unit receives the measured values of the level transmitter LT1 and the second pressure transmitter PT2 so that the level of the re-condenser 150 is within the set range and controls the third valve V3 and the fourth valve V4 ) And the fifth valve (V5).

For example, if the water level of the recondenser 150 is higher than the set value, the amount of opening of the fourth valve V4 is adjusted to recover the regeneration gas to the recondenser 150, So that the LNG to be regenerated in the liquid state from the recondenser 150 can be transferred to the high-pressure pump 200.

Alternatively, if the water level of the recondenser 150 becomes higher than the predetermined value, the amount of opening of the fifth valve V5 may be adjusted to recover the LNG to be regasified to the LNG storage tank 100. The adjustment of the amount of opening of the fifth valve V5 is controlled by the flow rate of the regeneration gas required by the gas consumer and the measured value of the water level and the pressure of the recondenser 150.

For example, when the level of the recondenser 150 is higher than the set value, the LNG to be regenerated from the recondenser 150 should be discharged. If the flow rate to be discharged is higher than the demanded gas amount at the reclaimed gas consumer, The fifth valve (V5) is opened as much as possible so that the LNG is recovered to the LNG storage tank (100).

By doing so, it is possible to recover the remaining LNG to the LNG storage tank 100 while supplying the regeneration gas to the gas consumer.

Also, the control unit maintains the pressure of the recondenser 150 within the set range. When the pressure in the recondenser 150 becomes higher than the set value, the third valve (V3) is opened to allow the evaporated gas to be recovered to the LNG storage tank (100). At this time, the evaporation gas in an amount exceeding the amount of evaporable gas that can be accommodated in the LNG storage tank 100 is regenerated by regulating the amount of opening of the second valve (V2) to recondense the evaporated gas to the recondenser So that the LNG is supplied to the recondenser 150 by an amount necessary for the LNG.

Alternatively, the pressure of the recondenser 150 is higher than the set value, so that a larger amount of LNG is to be supplied to the recondenser 150, and the flow rate of the LNG to be supplied to the recondenser 150 to lower the pressure in the recondenser 150 The amount of opening of the second valve V2 is adjusted so that the amount of LNG required to lower the pressure of the recondenser 150 is supplied to the recondenser 150, The LNG to be regenerated by the amount of gas demanded by the gas consumer is supplied to the high-pressure pump 200. The LNG of the amount exceeding the gas demand is regulated by the amount of opening of the fifth valve V5, ). ≪ / RTI >

That is, if the pressure of the recondenser 150 is higher than the set value, that is, if the amount of evaporated gas in the recondenser 150 is too large to receive sufficient cold heat from the LNG to be regenerated, the LNG need not be regenerated, When the amount of gas demanded by the gas consumer is smaller than the amount required for recirculating the evaporated gas in the recondenser 150, the LNG sufficient to recondense the evaporated gas in the recondenser 150 is recycled to the recycler 150 ).

By doing so, even when the flow rate of LNG required for recondensing and processing the evaporated gas is larger than the gas demand demanded by the gas consumer, LNG as much as the flow rate necessary for recondensing the evaporated gas, regardless of the gas demand amount, LNG supplied from the recycler 150 to the high-pressure pump 200 and supplied to the high-pressure pump 200, that is, a quantity exceeding the gas demand amount Of the LNG can be recovered to the LNG storage tank 100.

Therefore, even if the evaporation gas is generated in an amount larger than the gas demand amount, the evaporation gas can be discharged to the atmosphere, or can be condensed and recovered to the LNG storage tank 100 without burning in the GCU, The evaporative gas can be economically and efficiently treated.

The control of the second valve V2, the third valve V3, the fourth valve V4 and the fifth valve V5 for maintaining the water level and the pressure of the re-condenser 150 is controlled by the level transmitter LT1, And the measured value of the second pressure transmitter (PT2).

In this embodiment, the pressure of the recondenser 150 can be controlled from about 3 barg to 6 barg.

For example, if the pressure of the recondenser 150 is less than about 3 barg, the recondenser pressure controller PIC4 controls the fourth valve V4 to cause the regasification gas to be recovered to the recondenser 150 , Thereby increasing the pressure in the recondenser (150).

If the pressure of the recondenser 150 exceeds about 4 barg, the re-condenser pressure controller PIC2 controls the second valve V2 to supply the LNG supply flow rate from the LNG storage tank 100 to the recondenser 150 .

If the pressure of the recondenser 150 exceeds about 5 barg, the controller determines that the amount of LNG required to condense the evaporated gas is less than the amount of gas demand, and controls the second valve V2 to store the LNG The LNG supply flow from the tank 100 to the recondenser 150 is increased and the recondenser overpressure protection controller PIC5 controls the fifth valve V5 so that an amount of LNG exceeding the gas demand amount is supplied to the recondenser 150 to the LNG storage tank 100.

In addition, if the pressure of the recondenser 150 exceeds about 6 barg, the recondenser overpressure controller PIC3 controls the third valve V3 to deliver the unconcentrated gaseous evaporated gas from the recondenser 150 And recovered to the LNG storage tank 100.

Conventionally, the water level and pressure in the recondenser 150, that is, the recondensing capacity of the recondenser 150, was controlled according to the amount of LNG to be regasified, that is, the gas demand amount of the gas demanded place. Accordingly, if only LNG as much as the required amount of gas is supplied to the recondenser 150 regardless of the amount of the evaporated gas generated from the LNG storage tank 100 and LNG is insufficient as much as the gas required amount for recondensing the evaporated gas, The amount of evaporative gas that can not be re-condensed was vented into the atmosphere or treated by burning in the GCU.

However, according to the present invention, by controlling the water level and the pressure in the recondenser 150, that is, the recondensing capacity of the recondenser 150, based on the amount of the evaporating gas to be recondensed regardless of the recycling capacity, All of the evaporated gas can be condensed and recovered to the LNG storage tank 100 without venting the evaporated gas into the atmosphere or burning in the GCU and processing.

It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or scope of the invention as defined in the appended claims. . Therefore, the above-described embodiments are to be considered as illustrative rather than restrictive, and thus the present invention is not limited to the above description, but may be modified within the scope of the appended claims and equivalents thereof.

100: LNG storage tank
150: Re-condenser
200: High pressure pump
300: vaporizer
400: Low pressure compressor
V1, V2, V3, V4, V4: first, second, third, fourth and fifth valves
PT1: 1st pressure transmitter
PT2: 2nd pressure transmitter
LT1: Level transmitter
PIC1: Tank pressure controller
PIC2: Re-condenser pressure controller
PIC3: Re-condenser overpressure controller
PIC4: Re-condenser pressure controller
PIC5: Re-condenser overpressure protection controller
VL: Regeneration line
BL: Evaporation gas line
RL: Re-liquefaction line

Claims (9)

Supplying the evaporation gas and the liquefied gas to be regasified to the recondenser to condense the evaporation gas by cooling and heating the liquefied gas; And
Supplying the liquefied gas discharged from the re-condenser to a high-pressure pump for compressing the compressed liquefied gas, and vaporizing the compressed liquefied gas to supply it to the gas consumer,
The recondenser is supplied with a liquefied gas at a flow rate necessary for recondensing the evaporated gas,
When the flow rate of the liquefied gas supplied from the re-condenser to the high-pressure pump exceeds the gas demand amount required by the gas demanding place, the liquefied gas is regenerated into the liquefied gas storage tank in an amount exceeding the gas demand amount, A method for treating an evaporative gas in a system. The method according to claim 1,
The flow rate of the liquefied gas to be supplied to the recondenser is controlled,
Measuring the pressure of the recondenser,
And increases the flow rate of the liquefied gas supplied to the recondenser when the pressure of the recondenser exceeds a set value. The method of claim 2,
And increases the flow rate of the liquefied gas recovered from the recondenser to the liquefied gas storage tank if the pressure of the recondenser exceeds a set value. 4. The method according to any one of claims 1 to 3,
And reclaiming the regeneration gas to be supplied to the gas consumer when the pressure of the recirculator is lower than the set value. The method of claim 4,
And recovers the evaporated gas from the recondenser to the liquefied gas storage tank if the pressure of the recondenser exceeds a set value. A recondenser for condensing the evaporated gas to the cold of the liquefied gas to be regenerated;
A high-pressure pump for discharging the liquid-state liquefied gas from the recondenser and compressing it at a high pressure;
A vaporizer for vaporizing a liquefied gas compressed at a high pressure and supplying the liquefied gas to a gas consumer;
A re-liquefaction line branching between the recondenser and the high-pressure pump, for allowing the liquefied gas supplied from the recondensor to the high-pressure pump to be recovered to the liquefied gas storage tank;
A second pressure transmitter for measuring the pressure of the recondenser; And
And a fifth valve installed in the refueling line, the fifth valve being controlled by the measured value of the second pressure transmitter. The method of claim 6,
And a second valve installed between the liquefied gas storage tank and the recondenser, the second valve being controlled by the measured value of the second pressure transmitter. The method of claim 7,
The second valve and the fifth valve are controlled such that when the measured value of the second pressure transmitter exceeds a set value, the second valve and the fifth valve are further opened,
Adjusting the amount of opening of the second valve so that as much liquefied gas as necessary for recondensing the evaporated gas is supplied to the recondenser,
A controller for controlling an amount of opening of the second valve so that liquefied gas in an amount exceeding the amount of gas demanded by the gas demanding customer is recovered to the liquefied gas storage tank from a flow rate of the liquefied gas supplied from the recondenser to the high pressure pump; Further comprising: a liquefied gas regeneration system. The method of claim 8,
And a level transmitter for measuring the level of the re-condenser,
Wherein the control unit adjusts the amount of opening of the second valve and the fifth valve by using the measured values of the second pressure transmitter and the level transmitter.

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