KR20190041211A - Reliquefaction system - Google Patents

Abstract

Disclosed is a reliquefaction system capable of performing a reliquefaction process by equipment of a line installed in one integrated system in accordance with the kind of liquefied gas stored in a storage tank of a vessel. According to one embodiment of the present invention, the reliquefaction system comprises: one or more storage tanks to store liquefied gas and boil-off gas (BOG) of the liquefied gas; a compression unit having a compressor and a first cooler alternatively disposed on a supply line connected to the storage tank, and receiving and compressing a gaseous fluid including the BOG at a first pressure; a heat exchanger connected to the front end of the compression unit by the supply line and connected to the rear end of the compression unit by a reliquefaction line to perform heat exchange between the gaseous fluid and the fluid compressed by the compression unit; and a first branch line having a second cooler disposed therein, branched from a set position of the compression unit of the supply line to be connected to the reliquefaction line, and sending the fluid, which is compressed at a second pressure, which is less than the first pressure, through a compressor of the compression unit, to a heat exchange unit of the reliquefaction line through the second cooler. When the liquefied gas stored in the storage tank is ethane, the gaseous fluid including the BOG of the ethane can be selectively supplied to the heat exchange unit of the reliquefaction line through the supply line or the first branch line while being compressed at the first pressure.

Description

RELIQUACTION SYSTEM

The present invention relates to a re-liquefaction system.

As the regulations of the International Maritime Organization (IMO) on the emission of greenhouse gases and various air pollutants have been strengthened, the shipbuilding and marine industries have replaced natural fuels such as heavy oil and diesel oil, And it is often used as a fuel gas of a ship.

Natural gas, which is widely used in fuel gas, is mainly composed of methane, and is usually stored and transported into a liquefied gas state in which the volume thereof is reduced to 1/600.

The liquefied gas is stored and transported in a storage tank installed in an adiabatic treatment on the hull, and the engine of the ship is driven by supplying liquefied gas or boiled off gas as the fuel gas. Here, high pressure (about 5 to 8 bar) injection engine such as DFDE (Dual Fuel Disel Electric) engine and ME-GI engine (Man B & W's Gas Injection engine) 150 ~ 400 bar) injection engines are widely used. In addition, a medium pressure gas injection engine capable of combusting with medium pressure (about 16 to 18 bar) fuel gas has been developed and used.

On the other hand, various types of liquefied gas such as Ethane, Propane, Propylene, Butane, LPG (Liquefied Petroleum Gas) mainly composed of propane and butane are stored in the storage tank Can be transported. Here, ethane (boiling point -89 ° C), propane (boiling point -42.07 ° C), propylene (boiling point -47.6 ° C), and butane (boiling point-1 ° C) are different from each other.

In addition, the ship is provided with a re-liquefaction facility for re-liquefying the evaporated gas of the liquefied gas and restoring it in the storage tank. For example, Korean Patent Laid-Open No. 10-2012-0103421 (published on Mar. 19, 2012) discloses a system for compressing the evaporated gas generated in a storage tank in a compressor and liquefying it in a re-liquefier.

In this case, when the liquefied gas having a breaking point different from that of the existing liquefied gas stored in the storage tank is stored in the storage tank, there is a problem that the liquefaction system corresponding to the liquefied gas must be installed again.

Korean Patent Laid-Open No. 10-2012-0103421 (published on September 19, 2012)

The embodiment of the present invention is intended to provide a re-liquefaction system in which a re-liquefaction process is performed by equipment on corresponding lines provided in a single integrated system according to the type of liquefied gas stored in a storage tank of a ship.

According to an aspect of the present invention, there is provided a method of producing a liquefied gas, comprising: one or more storage tanks for storing a liquefied gas and an evaporated gas of the liquefied gas; A compressor for alternately arranging a compressor and a first cooler on a supply line connected to the storage tank and supplying a gaseous fluid containing the evaporated gas to the first pressure; A heat exchange unit connected to a front end of the compression unit by the supply line and connected to a rear end of the compression unit by a re-liquefaction line to perform heat exchange between the gaseous fluid and the fluid compressed by the compression unit; And a second cooler is disposed in the supply line and branched from a predetermined point of the compression section of the supply line and connected to the refill line. The fluid compressed to a second pressure lower than the first pressure through the compressor of the compression section, And a second branch line connected to the second branch line to be supplied to the heat exchange unit of the re-liquefaction line via the second cooler, wherein when the type of the liquefied gas stored in the storage tank is ethane, Line and the first branch line may be selectively supplied to the heat exchanger of the redistribution line in a compressed state at the first pressure via the supply line.

A connection line for bypassing the first cooler and connecting only a predetermined number of compressors of the compressors to each other; a branch line branched from a set point of the compression section of the supply line and connected to the first branch line; Further comprising a second branch line through which the fluid compressed to a third pressure lower than the second pressure is delivered to the second cooler, wherein when the type of liquefied gas stored in the storage tank is at least one of propane, propylene, and LPG, Wherein the gaseous fluid containing the evaporation gas of the liquefied gas is selectively supplied to the first branch line in a state compressed by the second pressure, and when the type of the liquefied gas stored in the storage tank is butane, The gaseous fluid containing the evaporation gas is optionally compressed to the third pressure through the connection line and then to the second branch line Can be supplied.

A first gas-liquid separator for separating the fluid containing the evaporated gas supplied from the storage tank into a gas phase and a liquid phase; a first pressure reducing valve for reducing the fluid passing through the heat exchanging section of the re-liquefaction line; Liquid separator and a flash gas line for supplying the separated gas phase component to the first gas-liquid separator, wherein the gaseous fluid separated by the first gas-liquid separator passes through the heat exchanging unit, And can be supplied to the compression section.

And a merging line for supplying a part of the gaseous components branched from the flash gas line and separated by the second gas-liquid separator to a front end or a rear end of the first gas-liquid separator of the supply line.

A first refrigerant supply line for reducing a part of the fluid compressed by the first pressure to be supplied to the first gas-liquid separator by the second pressure reducing valve, and a second refrigerant supply line branched from the second refrigerant- Further comprising a second refrigerant supply line for reducing a part of the fluid compressed by the second pressure or the third pressure by the third pressure reducing valve and supplying the reduced pressure to the first gas-liquid separator, wherein the type of liquefied gas stored in the storage tank The first refrigerant supply line and the second refrigerant supply line may be selectively connected to the first refrigerant supply line and the second refrigerant supply line in accordance with a temperature value of a sensor provided at a front end of the heat exchange unit of the supply line, Liquid separator through the second pressure reducing valve through the supply line.

The re-liquefaction system according to the embodiment of the present invention can perform the liquefaction process by the equipment on the corresponding line provided in one integrated system depending on the type of liquefied gas stored in the storage tank of the ship.

The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the description of the claims.

1 illustrates a re-liquefaction system in accordance with an embodiment of the present invention.
Fig. 2 is a view showing a state in which a merging line branched from the flash gas line supplying the gaseous components separated by the second gas-liquid separator to the first gas-liquid separator and connected to the front end of the heat-exchanging portion of the supply line is added to the re- It is.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided to fully convey the spirit of the present invention to a person having ordinary skill in the art to which the present invention belongs. The present invention is not limited to the embodiments shown herein but may be embodied in other forms. For the sake of clarity, the drawings are not drawn to scale, and the size of the elements may be slightly exaggerated to facilitate understanding.

Referring to FIG. 1, the re-liquefaction system 100 according to an embodiment of the present invention may be installed in a vessel for transporting liquefied gas. For example, the ship may include various liquefied fuel carriers, regasification vessels, container ships, general merchant ships, floating, production, storage and off-loading (FPSO), and floating storage and regasification unit (FSRU).

Specifically, the re-liquefaction system 100 includes a storage tank 10 for storing evaporative gas of liquefied gas and liquefied gas, a fluid (not shown) connected to the storage tank 10 and containing evaporative gas supplied from the storage tank 10 Liquid separator 20 for separating the gas-liquid separator 20 from the gas-liquid separator 20, and a first gas-liquid separator 20 for separating the gas- A compressor 30 for compressing the fluid to a first pressure and a fluid compressed at a predetermined pressure by one or more compressors of the compressor 30 are heat-exchanged with fluid in the gaseous phase supplied from the first gas-liquid separator 20, And a heat exchange unit 40 for supplying heat to the heat exchanger.

The re-liquefaction system 100 includes a supply line L1 for connecting the storage tank 10, the first gas-liquid separator 20, the heat exchanging unit 40 and the compressing unit 30, And a regeneration line L11 for sending the fluid compressed by the first pressure to the heat exchange unit 40 and a set point of the compression unit 30 of the supply line L1, Compresses the fluid to a second pressure lower than the first pressure through the compressors 31a to 31d and the first and second coolers 32a to 32d and supplies the fluid to the second cooler 33 A first branch line L2 through which the reclaiming line L11 joins the front end of the heat exchanging unit 40 and a second branching line L2 which bypasses the first cooling units 32a through 32d and which are provided in the compressors 31a through 31d, The compressed refrigerant is compressed to a third pressure lower than the second pressure by a compressor which is branched from the set point of the compression section 30 of the supply line L1 and connected by the connection line L3a, And a second branch line L3 for joining the fluid to the front end of the second cooler 33 of the first branch line L2.

Specifically, for example, when the type of liquefied gas stored in the storage tank 10 is ethane, the evaporated gas of ethane flows through the compressors 31a to 31d and the first coolers 32a to 32d of the compressing section 30 1 < / RTI >

When the liquefied gas stored in the storage tank 10 is any one of propane, propylene and LPG, the evaporation gas of the liquefied gas is supplied to the compressors 30 of the supply line L1, Is compressed to a second pressure lower than the first pressure via the first cooler, and then flows through the first branch line (L2).

If the liquefied gas stored in the storage tank 10 is butane, for example, the evaporated gas of butane flows through only a predetermined number of compressors 30 of the supply line L1 to a third pressure And then flows through at least one of the first branch line L2 and the second branch line L3. The second branch line L3 is connected to the front end of the second cooler 33 of the first branch line L2.

The re-liquefaction system 100 described above includes a first pressure reducing valve V1 for reducing the pressure of the fluid passing through the heat exchanging part 40 of the liquid refilling line L11 and a second pressure reducing valve V2 for releasing the fluid reduced in pressure by the first pressure reducing valve V1 A second gas-liquid separator 50 for separating the liquid component separated by the second gas-liquid separator 50 into a liquid phase, a first collection line L4 for storing the liquid component separated by the second gas-liquid separator 50 in the storage tank 10, 50 for supplying a gas-phase component separated by the gas-liquid separator 20 to the first gas-liquid separator 20. The re-liquefaction line L11 connects the compression unit 30, the heat exchanging unit 40, the first pressure reducing valve V1 and the second gas-liquid separator 50. The first pressure reducing valve V1 is connected to, for example, And a Joule Thomson valve.

The re-liquefaction system 100 is branched from the rear end of the compression section 30 of the supply line L1 and supplies the fluid compressed by the first pressure via the compression section 30 of the supply line L1 to the second pressure- Liquid separator 20 and the first refrigerant supply line L21 branched from the rear end of the second cooler 33 of the first branch line L2 and supplied to the first gas- A second refrigerant supply line L22 for depressurizing the fluid compressed by the pressure or the third pressure by the third pressure reducing valve V3 and supplying the reduced pressure to the first gas-liquid separator 20 may be provided.

Hereinafter, each component of the liquefaction system 100 will be described in detail.

One or more of the storage tanks 10 may be provided and may be any one of, for example, Ethane, Propane, Propylene, Butane, LPG (Liquefied Petroleum Gas) Of the liquefied gas. All of the storage tanks 10 may store the same kind of liquefied gas or some of the storage tanks 10 may store different kinds of liquefied gases. 1, one storage tank 10 is shown for convenience of explanation.

The storage tank 10 may include a membrane type tank, an SPB type tank, and the like which store the fuel in a liquefied state while maintaining an adiabatic state.

The first gas-liquid separator 20 separates the fluid containing the evaporated gas supplied from the storage tank 10 into a gas phase and a liquid phase. For example, the first gas-liquid separator 20 can separate the high-carbon components in the form of droplets contained in the evaporated gas supplied from the storage tank 10 so as not to flow toward the heat exchange unit 40.

The gaseous fluid separated by the second gas-liquid separator (50) can be introduced into the first gas-liquid separator (20) through the flash gas line (L5) and mixed.

2, the first gas-liquid separator 20 of the supply line L1 is branched from the flash gas line L5 connecting the second gas-liquid separator 50 and the first gas-liquid separator 20, A merge line L5a connected to the front end may be added. In this case, the gaseous components separated by the second gas-liquid separator 50 are supplied to the first gas-liquid separator 20 through the merging line L5a and mixed.

This confluence line L5a is branched from the flash gas line L5 described above in the other example and is connected to the downstream end of the first gas-liquid separator 20 of the supply line L1, Can be mixed with the fluid.

That is, the confluence line L5a may be branched from the above-described flash gas line L5 and connected to either the front end or the rear end of the first gas-liquid separator 20 of the supply line L1, The temperature rises.

In the above example, a part of the gaseous components branched from the flash gas line L5 and separated by the second gas-liquid separator 50 is supplied to the front end of the first gas-liquid separator 20 of the supply line L1 through the confluence line L5a Liquid separator 50 to supply the entire amount of the gaseous component separated by the second gas-liquid separator 50 to the front end or the rear end of the first gas-liquid separator 20 of the supply line L1, L5 may be connected.

The liquid fluid separated by the first gas-liquid separator 20 is joined to the first collecting line L4 through the second collecting line L6 and stored in the storage tank 10. The gaseous fluid separated by the first gas-liquid separator 20 is supplied to the compression unit 30 via the heat exchange unit 40 via the supply line L1.

The heat exchanging unit 40 heat-exchanges the fluid compressed by the first pressure, the second pressure, or the third pressure with the gaseous fluid supplied from the first gas-liquid separator 20 to liquefy it. The fluid liquefied by the heat exchanging part 40 flows into the second gas-liquid separator 50 through the first pressure reducing valve V1.

If the liquefied gas stored in the storage tank 10 is ethane, the liquefied gas is separated through the first gas-liquid separator 20, The gas phase fluid containing the evaporated gas of the ethane is compressed to the first pressure through the compressors 31a to 31d and the first coolers 32a to 32d of the compressing section 30 of the supply line L1, And is supplied to the heat exchanging unit 40 through the line L11. At this time, a part of the fluid compressed by the compression unit 30 may be supplied to the consumer E and used.

The pressure of the fluid flowing into the heat exchanging unit 40 of the re-liquefaction line L11 through the compression unit 30 of the supply line L1 may be 140 to 160 barA.

The fluid compressed at the first pressure through the compression section 30 of the supply line L1 is discharged through the first refrigerant supply line L21 to lower the fluid temperature of the gas phase in the first gas- Liquid separator 20 via the second pressure reducing valve V2.

In this case, a sensor T for measuring the temperature may be provided at a front end of the heat exchanging unit 40 of the supply line L1. The controller 60 may control the temperature of the first refrigerant The degree of opening / closing of the second pressure reducing valve V2 of the supply line L21 can be controlled. The re-liquefaction efficiency of the heat exchanging unit 40 can be increased.

The controller 60 controls the supply line L1, the first branch line L2, the second branch line L3, the first refrigerant supply line L21, and the second refrigerant supply line L3, depending on the type of liquefied gas stored in the storage tank 10. [ The second refrigerant supply line L22 or the like can be controlled to control the flow of the fluid.

As described above, according to the temperature value measured by the sensor T provided on the upstream side of the heat exchanging section 40 of the supply line L1, the control section 60 controls the second refrigerant supply line L21, It is possible to control the degree of opening and closing of the valve V2 or the degree of opening and closing of the third pressure reducing valve V3 of the second refrigerant supply line L22 to be described later. As a result, the re-liquefaction efficiency of the heat exchanging unit 40 can be increased.

The control unit 60 increases the degree of opening and closing of the second pressure reducing valve V2 of the first refrigerant supply line L21 so as to increase the degree of opening and closing of the first pressure reducing valve V2 when the temperature value measured by the sensor T is higher than the set value, The temperature of the gas phase in the first gas-liquid separator 20 can be lowered by the fluid supplied to the first gas-liquid separator 20 through the second pressure-reducing valve V2 through the refrigerant supply line L21.

As another example, when the liquefied gas stored in the storage tank 10 is propane, propylene or LPG, the gaseous fluid containing the evaporation gas of the liquefied gas passed through the first gas-liquid separator 20 is supplied to the supply line L1 The refrigerant is compressed to a second pressure lower than the first pressure through the set number of compressors 31a to 31c and the first coolers 32a and 32b of the second branch line L2 To the re-liquefaction line L11 and supplied to the heat exchanging unit 40. [

The set number of first coolers 32a and 32b of the supply line L1 does not sufficiently provide a change in the amount of heat due to the phase change and thus the second cooler 33 is separately disposed in the first branch line L2, The fluid compressed by the second pressure can be sufficiently cooled.

Here, the pressure of the fluid flowing into the second cooler 33 may be 15 to 50 barA. The fluid that has passed through the second cooler 33 may have a part of liquid phase and is merged into the re-liquefaction line L11 and then supplied to the heat exchanging unit 40. The heat of the fluid passing through the first reducing valve V1 ) To a level of approximately 3 to 5 barA, and then flows into the second gas-liquid separator (50).

In order to lower the temperature of the gas phase in the first gas-liquid separator 20, the temperature of the second cooler 33 is adjusted according to the temperature value measured by the sensor T provided at the upstream side of the heat exchanging unit 40 of the supply line L1. May be supplied to the first gas-liquid separator 20 via the third pressure reducing valve V3 through the second refrigerant supply line L22. The control unit 60 controls the degree of opening and closing of the third pressure reducing valve V3 of the second refrigerant supply line L22 according to the temperature value measured by the sensor T provided at the upstream side of the heat exchanging unit 40 of the supply line L1 Can be controlled.

The control unit 60 increases the degree of opening and closing of the third pressure reducing valve V3 of the second refrigerant supply line L22 and increases the opening degree of the second pressure reducing valve V2 of the second refrigerant supply line L22 when the temperature value measured by the sensor T is higher than the set value. The fluid temperature of the gas phase in the first gas-liquid separator 20 can be lowered by the fluid supplied to the first gas-liquid separator 20 via the third pressure-reducing valve V3 through the refrigerant supply line L22.

As another example, when the type of the liquefied gas stored in the storage tank 10 is butane, the fluid containing the evaporation gas of butane through the first gas-liquid separator 20 flows through the one-stage compressor 31a of the connection line L3a, And may be joined to the front end of the second cooler 33 of the first branch line L2 through the second branch line L3. Thereafter, the fluid is supplied to the heat exchanging unit 40 through the second cooler 33.

Here, as shown in FIG. 1, when the two-stage and three-stage compressors 31b and 31c at the rear stage of the first stage compressor 31a are connected in parallel to each other by the connection line L3a, . In this case, the fluid passing through the compressors 31a to 31c on the connection line L3a may merge at the front end of the second cooler 33 through the first branch line L2 and the second branch line L3. The pressure of this fluid entering the second cooler 33 may be 2.5 to 3.5 barA.

Specifically, in the case of butane, the liquid has a liquid phase when passing through the first stage compressor 31a and the first cooler 32a depending on its characteristics, and when the liquid having the liquid phase flows into the second stage compressor 31b Problems can arise. Therefore, in the embodiment of the present invention, the first coolers 32a to 32d are bypassed so that fluid can be introduced only by a predetermined number of compressors.

Since the butane is required to have a pressure of less than 10 barA for re-liquefaction and the two-stage compression is sufficient, the two-stage compressor 31b and the three-stage compressor 31c at the rear stage of the first stage compressor 31a are connected in parallel to each other More flow can be compressed.

The fluid flows through the first branch line L2 and the second branch line L3 at the rear end of the second stage compressor 31b and the third stage compressor 31c and flows into the second cooler 33, And then supplied to the heat exchanging unit 40. The heat exchanging unit 40 is provided with a heat exchanger 40,

Further, in the case of re-liquefaction of butane, the temperature of the second gas-liquid separator 50 is sufficiently low, so that the amount of generated flash gas may be small or absent. Therefore, in the case of pure butane liquefaction, the frequency of use of the flash gas line L5 may be reduced. However, in the case where propane, ethane or the like, which is lower than butane, is mixed in a small amount in the storage tank 10 described above, they are evaporated into flash gas and supplied to the first gas-liquid separator 20 through the flash gas line L5 have.

As described above, in order to increase the re-liquefaction efficiency in accordance with the temperature measurement value of the sensor T, the refrigerant is supplied to the first gas-liquid separator 20 via the third pressure-reducing valve V3 through the second refrigerant supply line L22 It is possible to supply the fluid through the second cooler 33.

In this way, the liquefied gas is compressed and cooled by the equipment on the corresponding line according to the type of the liquefied gas stored in the storage tank 10 of the ship through the integrated liquefying system 100, .

The foregoing has shown and described specific embodiments. However, it is to be understood that the present invention is not limited to the above-described embodiment, and various changes and modifications may be made without departing from the scope of the technical idea of the present invention described in the following claims It will be possible.

10: Storage tank 20, 50: Gas-liquid separator
30: compression section 40: heat exchange section
60:
L1: supply line L2: first branch line
L3: second branch line L4, L6: recovery line
L5: Flash gas line L11: Re-liquefaction line
L21: first refrigerant supply line L22: second refrigerant supply line

Claims (5)

At least one storage tank for storing a liquefied gas and an evaporated gas of the liquefied gas;
A compressor for alternately arranging a compressor and a first cooler on a supply line connected to the storage tank and supplying a gaseous fluid containing the evaporated gas to the first pressure;
A heat exchange unit connected to a front end of the compression unit by the supply line and connected to a rear end of the compression unit by a re-liquefaction line to perform heat exchange between the gaseous fluid and the fluid compressed by the compression unit; And
A second cooler is disposed and branched from a set point of the compressing section of the supply line and connected to the refill lining line, the fluid compressed to a second pressure lower than the first pressure via the compressor of the compressing section, And a first branch line through the cooler to the heat exchanger of the re-liquefaction line,
Wherein the gaseous fluid containing the vapor of ethane is selectively compressed among the supply line and the first branch line to the first pressure through the supply line when the type of liquefied gas stored in the storage tank is ethane, Liquefaction line is supplied to the heat exchanger of the re-liquefaction line. The method according to claim 1,
A connection line for bypassing the first cooler and connecting only a predetermined number of compressors among the compressors,
A second branch which branches from a set point of the compression section of the supply line and is connected to the first branch line and sends a fluid compressed to a third pressure lower than the second pressure through the set number of compressors to the second compressor, Further comprising a branch line,
When the liquefied gas stored in the storage tank is at least one of propane, propylene, and LPG, the gaseous fluid containing the evaporation gas of the liquefied gas is selectively compressed into the first branch line And,
The liquid in the gaseous phase containing the evaporation gas of the butane is compressed to the third pressure through the connection line and then supplied to the second branch line when the liquefied gas stored in the storage tank is butane, Liquefaction system. The method according to claim 1,
A first gas-liquid separator for separating the fluid containing the evaporated gas supplied from the storage tank into a gas phase and a liquid phase;
A first pressure reducing valve for reducing the pressure of the fluid passing through the heat exchanging section of the redistribution line,
A second gas-liquid separator for separating the decompressed fluid into a gas phase and a liquid phase,
And a flash gas line for supplying the separated gas phase component to the first gas-liquid separator,
And the gaseous fluid separated by the first gas-liquid separator is supplied to the compression section via the heat exchange section. The method of claim 3,
Further comprising a merging line for supplying a part of the gaseous components branched from the flash gas line and separated by the second gas-liquid separator to a front end or a rear end of the first gas-liquid separator of the supply line. The method according to claim 1,
A first refrigerant supply line for reducing a part of the fluid compressed by the first pressure by a second pressure reducing valve and supplying the pressure to the first gas-liquid separator,
Liquid separator that is branched from the second refrigerant downstream of the first branch line and reduces a part of the fluid compressed by the second pressure or the third pressure by the third pressure reducing valve and supplies the reduced pressure to the first gas- Further comprising a supply line,
Wherein the first refrigerant is supplied to the first refrigerant supply line and the second refrigerant is supplied to the first refrigerant supply line and the second refrigerant is supplied to the second refrigerant supply line, Liquid separator via the first pressure-reducing valve through the first refrigerant supply line.

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