KR20160053379A - Reliquefaction system, and fuel gas supply system - Google Patents

Abstract

A re-liquefaction system and a fuel gas supply system are disclosed. The re-liquefaction system according to an embodiment of the present invention comprises: a first storage tank which stores first liquefied gas therein; a second storage tank which stores second liquefied gas having a liquefaction point lower than the first liquefied gas; a fuel supply tank which stores the second liquefied gas supplied from the second storage tank; a re-liquefaction part which has a heat exchange part for exchanging the heat of the evaporation gas of the first liquefied gas supplied from the first storage tank with the second liquefied gas from the fuel supply tank; and a separator which receives the evaporation gas of the first liquefied gas passing through the re-liquefaction part and separates the received evaporation gas into liquid and gas components. Thus, the present invention effectively uses ethane evaporation gas generated in a process of transferring liquefied ethane.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a re-liquefaction system and a fuel gas supply system,

The present invention relates to a refueling system and a fuel gas supply system.

Ethane extracted from shale gas and Liquefied natural gas (LNG) is used as a raw material for petrochemical products, and recently its economical efficiency has been highlighted. At 1 atmosphere, ethane is approximately -88.6 ° C, and methane, the main constituent of LNG, has a breaking point of approximately -161.5 ° C. These ethane and LNG can be transported by the vessel in a liquefied state. Ships include liquefied fuel carriers, liquefied fuel RVs, containerships, general merchant ships, LNG FPSOs, LNG FSRUs and so on.

The ship may be provided with a fuel gas supply system for converting the pressure, temperature, state, etc. of LNG vapor (BOG, Boil-Off Gas) or LNG supplied from the storage tank to the engine. Here, the vessel includes a low pressure gas injection engine such as a Dual Fuel Disel Electric (DFDE) engine using two or more different kinds of fuel as a fuel, and a high pressure gas injection engine such as an ME-GI engine (Man B & W's Gas Injection Engine) . For example, Korean Patent Laid-Open No. 10-2008-0103500 (published on November 27, 2008) has proposed a fuel gas supply system capable of supplying fuel to a high-pressure gas injection engine such as an ME-GI engine. The system extracts LNG from the LNG fuel tank, compresses it to high pressure, vaporizes it, and supplies it to the high-pressure gas injection engine. In addition, a variety of fuel gas supply systems have been known, such as compressing the LNG vapor from the storage tank to meet the supply conditions in a multi-stage compressor, supplying it to the engine, or re-liquefying it.

However, as described above, conventionally, system development has been vigorously carried out to supply LNG evaporation gas to the engine or to store liquefied liquefied gas, and the like. On the other hand, in a ship storing and transporting liquefied ethane, There is not enough system available.

Korean Patent Laid-Open No. 10-2008-0103500 (published on November 27, 2008)

An embodiment of the present invention is to provide a re-liquefaction system and a fuel gas supply system which can effectively utilize the ethane-evaporated gas generated in the process of transporting liquefied ethane and re-store it in a liquefied ethane storage tank.

The present invention also provides a re-liquefaction system and a fuel gas supply system that can process LNG that has undergone heat exchange with liquefied ethane in accordance with fuel gas supply conditions of the engine and supply it to the engine.

According to an aspect of the present invention, there is provided a liquid storage tank comprising: a first storage tank for storing a first liquefied gas; A second storage tank for storing a second liquefied gas having a lower liquefaction point than the first liquefied gas; A fuel supply tank for storing a second liquefied gas supplied from the second storage tank and a second liquefied gas supplied from the second storage tank to perform heat exchange between the first liquefied gas evaporated gas supplied from the first storage tank and the second liquefied gas in the fuel supply tank A re-cure unit including a heat exchange unit; And a separator for separating the first liquefied gas evaporated gas that has passed through the re-cure unit into a liquid component and a gaseous component, may be provided.

A first heat exchange unit installed inside the fuel supply tank for performing heat exchange between the first liquefied gas evaporated gas supplied from the first storage tank and the second liquefied gas stored in the fuel supply tank, And a second heat exchanger for performing heat exchange between the first liquefied gas evaporated gas passed through the first heat exchanger and the second liquefied gas discharged from the fuel supply tank.

Further comprising a first liquefied gas supply line through which the first liquefied gas evaporated gas supplied from the first storage tank passes through the re-cure unit and the separator, wherein the first liquefied gas supply line is provided in the first liquefied gas supply line, And a compressor for compressing and supplying the first liquefied gas evaporated gas supplied from the storage tank to the first heat exchanger.

The first liquefied gas may be liquefied ethane, and the second liquefied gas may be liquefied natural gas.

According to another aspect of the present invention, there is provided a liquid storage tank comprising: a first storage tank for storing a first liquefied gas; A second storage tank for storing a second liquefied gas having a lower liquefaction point than the first liquefied gas; A fuel supply tank for storing a second liquefied gas supplied from the second storage tank; A first heat exchange unit installed inside the fuel supply tank for performing heat exchange between the first liquefied gas evaporated gas supplied from the first storage tank and the second liquefied gas stored in the fuel supply tank; And a second heat exchanger for performing heat exchange between the first liquefied gas evaporated gas passed through the first heat exchanger and the second liquefied gas discharged from the fuel supply tank.

And a pressure regulator installed in the fuel supply tank for exchanging the second liquefied gas stored in the fuel supply tank with air or heat transfer medium to raise the pressure of the fuel supply tank to a predetermined pressure.

Wherein the fuel supply tank includes a first fuel supply tank and a second fuel supply tank, the volume of which is smaller than that of the second storage tank and the pressure of which is larger than that of the second storage tank, and wherein either one of the first fuel supply tank and the second fuel supply tank And the second liquefied gas is discharged from the second storage tank, the other liquefied gas may be alternately operated to receive the second liquefied gas from the second storage tank.

And the second liquefied gas evaporation gas of the first fuel supply tank is supplied to the first fuel supply tank and the second fuel supply tank through the heat exchange pipes respectively provided in the first fuel supply tank and the second fuel supply tank when the pressure in the first fuel supply tank exceeds the set value. And the second liquefied gas stored in the first fuel supply tank and the second fuel supply tank may be sequentially heat-exchanged and re-liquefied.

The second liquefied gas passed through the second heat exchanger is supplied to the engine. The engine includes a medium pressure gas injection engine, and the pressure in the fuel supply tank is 16 to 45 bar, which is the fuel gas supply pressure condition of the medium pressure gas injection engine. have.

The re-liquefaction system and the fuel gas supply system according to the embodiment of the present invention can effectively utilize the ethane evaporation gas generated in the process of transporting liquefied ethane, re-liquefy it, and store it again in the liquefied ethane storage tank.

Further, the LNG subjected to the heat exchange with the liquefied ethane can be treated to meet the fuel gas supply condition of the engine and supplied to the engine.

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 shows a re-liquefaction system according to an embodiment of the present invention.
Fig. 2 shows a configuration for re-liquefying the LNG vaporized gas in the fuel supply tank shown in Fig.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments described below are provided by way of example so that those skilled in the art will be able to fully understand the spirit of the present invention. The present invention is not limited to the embodiments described below, but may be embodied in other forms. In order to clearly explain the present invention, parts not related to the description are omitted from the drawings, and the width, length, thickness, etc. of the components may be exaggerated for convenience. Like reference numerals designate like elements throughout the specification.

Referring to FIG. 1, the re-liquefaction system 100 according to the embodiment of the present invention can effectively utilize the ethane-evaporated gas generated in the process of transporting liquefied ethane and re-liquefy it. The re-liquefaction system 100 may be installed in a vessel that transports liquefied ethane. In addition, the re-liquefaction system 100 includes various liquefied fuel carriers, regasification vessels, container ships, general merchant ships, LNG FPSO (Floating, Production, Storage and Off-loading), LNG FSRU ) And the like.

The re-liquefaction system 100 includes a first storage tank 10 for storing liquefied ethane, a second storage tank 20 for storing the LNG, a fuel supply tank (not shown) for storing the LNG supplied from the second storage tank 20 And a heat exchanging part (35, 36) for performing heat exchange between the ethane evaporating gas supplied from the first storage tank (10) and the LNG of the fuel supply tank (31, 32) A separator 40 for separating the ethane evaporated gas supplied from the re-condenser 30 into a liquid component and a gaseous component and an ethane evaporated gas supplied from the first storage tank 10 is supplied to the re- And an ethane recovery line L2 for allowing the liquid component stored in the separator 40 to be stored in the first storage tank 10.

A plurality of first storage tanks 10 are provided to store liquefied ethane and supply ethane vapor to the fuel supply tanks 31 and 32 through the ethane gas supply line L1. At this time, the compressor 50 is provided in the ethane gas supply line L1 to compress the ethane evaporation gas supplied from the first storage tank 10, and to send it to the first heat exchanger 35. The first storage tank 10 may include a membrane type tank, an SPB type tank, and the like.

The second storage tank 20 stores the LNG, and may be, for example, an LNG fuel tank or an LNG cargo tank. The second storage tank 20 is disposed upstream of the fuel supply tanks 31 and 32 so that the LNG can be supplied to the fuel supply tanks 31 and 32 by the difference in pressure (head water pressure). This second storage tank 20 may comprise a pressure type C type tank of the International Maritime Organization (IMO). However, it is not necessarily limited to this, and may include various kinds of pressure-type tanks.

When the second storage tank 20 is made of a pressure C type tank, the LNG vapor can be held for a considerable time without performing the LNG evaporative gas treatment. In addition, the LNG evaporation gas holding time of the second storage tank 20 can be maintained to be larger than the bunkering period of the ship, and the LNG evaporation gas holding time of the second storage tank 20 can be maintained longer than the LNG evaporation gas of the second storage tank 20, Equipment and operation costs for the user can be reduced.

Also, although not shown, when the pressure in the second storage tank 20 exceeds a set value and it is necessary to eliminate the LNG vapor, the LNG evaporated gas is discharged from the second storage tank 20, One or more of pressure, temperature, and state may be converted into the fuel gas supply condition of the engine 70 and sent to the engine 70 for consumption. The engine 70 may include a low pressure, medium pressure or high pressure gas injection engine.

The low pressure gas injection engine uses a fuel gas of about 5 to 7 bar and includes a power generation engine such as a DFDE engine. The low-pressure gas injection engine may be a dual fuel engine that can use not only natural gas but also heavy oil (HFO) as fuel. The medium pressure gas injection engine uses approximately 16 to 45 bar of fuel gas. The high-pressure gas injection engine includes the ME-GI engine using approximately 150 to 300 bar of fuel gas. Hereinafter, the case where the engine 70 is a low-pressure gas injection engine will be described as an example.

The remanent unit 30 includes the fuel supply tanks 31 and 32 and the heat exchange units 35 and 36 as described above. The internal pressure of the fuel supply tanks 31 and 32 can be raised to a pressure level required by the engine 70. To this end, a pressure regulating portion 37 for heating the LNG stored in the fuel supply tanks 31, 32 by heat or for exchanging heat with the atmosphere or heat transfer medium to raise the pressure in the fuel supply tanks 31, .

The fuel supply tanks 31 and 32 discharge the LNG toward the engine 70 by using the pressure raised by the pressure regulating portion 37. [ Since the LNG can be effectively discharged from the fuel supply tanks 31 and 32 by the pressure of the fuel supply tanks 31 and 32, a conventional apparatus such as a pump, a compressor and the like can be omitted. The fuel supply tanks 31 and 32 may be provided with a pressure C type tank as in the second storage tank 20. [

The fuel supply tanks 31 and 32 may include a first fuel supply tank 31 and a second fuel supply tank 32 having a smaller volume and a larger pressure than the second storage tank 20. [ In the present embodiment, a pair of fuel supply tanks are arranged in parallel, but the number may be more than that. By disposing separate fuel supply tanks 31 and 32 connected to the second storage tank 20, the pressure of the second storage tank 20 can be kept low during the LNG bunkering.

Specifically, when the pressure of the second storage tank 20 is kept low, the second storage tank 20 does not require a separate LNG evaporative gas processing device when the internal pressure increases to a pre-designed pressure by the LNG evaporation gas Thereby reducing costs and increasing the efficiency of operation.

Further, since the internal pressure of the second storage tank 20 is kept low during bunkering and the difference from the actually designed pressure of the second storage tank 20 becomes large, it is not necessary to process the LNG evaporated gas immediately, The longer the time to do so. Even if the internal pressure of the second storage tank 20 increases, there is a possibility that the pressure of the second storage tank 20 continuously decreases through the supply of LNG to the fuel supply tanks 31 and 32. Therefore, It is possible to perform stable operation without processing the LNG evaporating gas of the second storage tank 20 during the period. For example, the internal pressure of the second storage tank 20 may be approximately 0 to 5 bar, and may be close to 0 bar immediately after bunkering.

Further, when the engine 70 includes the medium pressure gas injection engine, the internal pressure of the fuel supply tanks 31 and 32 can be maintained at about 16 to 45 bar, which is the fuel supply condition of the medium pressure gas injection engine.

When either of the first fuel supply tank 31 and the second fuel supply tank 32 reaches the set pressure and the LNG is discharged, the other one is operated alternately to receive the LNG from the second storage tank 20 . The pressure set in the first fuel supply tank 31 and the second fuel supply tank 32 may be determined according to the fuel gas supply condition of the engine 70. [ Specifically, when the pressure set by the pressure regulating portion 37 is reached and the first fuel supply tank 31 discharges the LNG, the second fuel supply tank 32 receives the LNG from the second storage tank 20 . When the second fuel supply tank 32 reaches the set pressure and discharges the LNG, the first fuel supply tank 31 can receive the LNG from the second storage tank 20. The set pressure described above may be 16 to 45 bar, which is the fuel gas supply pressure condition of the medium pressure gas injection engine.

At this time, the valves (V1 to V4) provided in the first fuel supply tank 31 and the second fuel supply tank 32 are opened and closed for LNG discharge and supply. The operation of the valves V1 to V4 can be controlled by a control unit (not shown). Here, a sensor (not shown) for measuring the pressure and flow rate of the first fuel supply tank 31 and the second fuel supply tank 32 may be provided, and a control unit (not shown) (V1 to V4) can be controlled.

2, for example, when the pressure in the first fuel supply tank 31 exceeds the set value and it is necessary to solve the problem, the LNG evaporating gas in the first fuel supply tank 31 is supplied to the first Can be heat exchanged with the LNG stored in the fuel supply tanks 31 and 32 sequentially through the heat exchange pipes P1 and P2 provided in the fuel supply tank 31 and the second fuel supply tank 32, That is, heat exchange is performed between the LNG stored in the first fuel supply tank 31 and the LNG evaporation gas BOG in the first fuel supply tank 31 through the heat exchange pipe P1 of the first fuel supply tank 31 . The heat-exchanged LNG vapor is heat-exchanged with the LNG stored in the second fuel supply tank 32 through the heat exchange pipe P2 of the second fuel supply tank 32 to be re-liquefied and stored in the second fuel supply tank 32 do.

1, the heat exchanging units 35 and 36 are provided inside the fuel supply tanks 31 and 32 and are connected to the first and second storage tanks 10 and 10 and the fuel supply tanks 31 and 32, respectively. A first heat exchange unit 35 for performing primary heat exchange between the LNG and the LNG and a second heat exchange between the LNG discharged from the ethane evaporation gas and the fuel supply tanks 31 and 32 through the first heat exchange unit 35 And a second heat exchanging unit 36 for heat exchanging the heat. The re-circulation of the ethane-evaporated gas supplied from the first storage tank 10 is carried out through the heat exchanging portions 35 and 36.

The separator 40 receives the ethane-evaporated gas passing through the second heat exchanger 36 and separates it into a liquid component and a gas component. Thereafter, the liquid component stored in the separator 40 is restored to the first storage tank 10 through the ethane recovery line L2.

Hereinafter, the ethane evaporative gas re-liquefaction process will be described based on the above-mentioned contents.

First, primary heat exchange is carried out by the first heat exchanger 35 between the LNG stored in the fuel supply tanks 31, 32 and the ethane evaporation gas supplied from the first storage tank 10.

Next, the secondary heat exchange is performed by the second heat exchanger 36 between the LNG discharged from the fuel supply tanks 31, 32 and the ethane evaporation gas through the first heat exchanger 35.

Next, the ethane-evaporated gas passed through the second heat exchanging section (36) is separated into a liquid component and a gas component by the separator (40).

Thereafter, the liquid component stored in the separator 40 is restored to the first storage tank 10 by the ethane recovery line L2.

The second storage tank 20 sends the LNG to the fuel supply tanks 31 and 32 through the third line L3 and the LNG discharged from the fuel supply tanks 31 and 32 flows through the fourth line L4 to the engine 70 through the second heat exchanger 36 and the processing unit 60. [

The treatment section 60 may include devices for adjusting at least one of the pressure, temperature, and state of the fluid through the second heat exchange section 36 to meet the fuel gas supply conditions of the engine 70.

For example, when the engine 70 is a low-pressure gas injection engine such as a DFDE engine, the processing unit 60 includes a vaporizer 62 for vaporizing the fluid passing through the second heat exchanging unit 36, A pressure reducing valve 64 for reducing pressure to the fuel gas supply pressure of the gas injection engine, a heater 66 for correcting the temperature of the fluid passing through the pressure reducing valve 64 to meet the required temperature of the low pressure gas injection engine have.

When the engine 70 is a high-pressure gas injection engine such as the ME-GI engine, the processing unit 60 includes a high-pressure pump (not shown) for pressurizing and delivering the LNG in accordance with the fuel gas supply pressure of the high-pressure gas injection engine, A high pressure vaporizer (not shown) for vaporizing the vaporizer, and the like.

Thus, the ethane-evaporated gas generated in the process of transporting liquefied ethane can be utilized as a heat exchange medium with the LNG, and the heat-exchanged LNG can be utilized as the fuel gas of the engine.

In the above-described embodiments, LNG and liquefied ethane are exemplified. However, the present invention is not limited to the LNG and the liquefied ethane, and the above-described embodiments may be applied to various liquefied gases having different liquefaction points. For example, liquefied propane, liquefied butane, etc. may be used instead of liquefied ethane. In addition, a variety of materials that have a higher breaking point (or liquefying point) than methane and require a liquefaction process for transport can be used.

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: first storage tank 20: second storage tank
30: Re-liquidating unit 40: Separator
31, 32: Fuel supply tank 35: First heat exchanger
36: second heat exchanger 37: pressure regulator
50: compressor 60:
70: engine L1: ethane gas supply line
L2: ethane recovery line

Claims (9)

A first storage tank for storing the first liquefied gas;
A second storage tank for storing a second liquefied gas having a lower liquefaction point than the first liquefied gas;
A fuel supply tank for storing a second liquefied gas supplied from the second storage tank and a second liquefied gas supplied from the second storage tank to perform heat exchange between the first liquefied gas evaporated gas supplied from the first storage tank and the second liquefied gas in the fuel supply tank A re-cure unit including a heat exchange unit; And
And a separator for receiving the first liquefied gas evaporated gas passed through the re-cure unit and separating the liquid gas component into a liquid component and a gaseous component. The method according to claim 1,
A first heat exchange unit installed inside the fuel supply tank for performing heat exchange between the first liquefied gas evaporated gas supplied from the first storage tank and the second liquefied gas stored in the fuel supply tank,
And a second heat exchanger for performing heat exchange between the first liquefied gas evaporated gas passed through the first heat exchanger and the second liquefied gas discharged from the fuel supply tank. 3. The method of claim 2,
A first liquefied gas supply line through which the first liquefied gas evaporated gas supplied from the first storage tank passes through the re-cure unit and the separator,
And a compressor installed in the first liquefied gas supply line for compressing the first liquefied gas evaporated gas supplied from the first storage tank and supplying the compressed liquefied gas to the first heat exchanger. The method according to claim 1,
Wherein the first liquefied gas is liquefied ethane and the second liquefied gas is liquefied natural gas. A first storage tank for storing the first liquefied gas;
A second storage tank for storing a second liquefied gas having a lower liquefaction point than the first liquefied gas;
A fuel supply tank for storing a second liquefied gas supplied from the second storage tank;
A first heat exchange unit installed inside the fuel supply tank for performing heat exchange between the first liquefied gas evaporated gas supplied from the first storage tank and the second liquefied gas stored in the fuel supply tank; And
And a second heat exchanger for performing heat exchange between the first liquefied gas evaporated gas passed through the first heat exchanger and the second liquefied gas discharged from the fuel supply tank. 6. The method of claim 5,
And a pressure regulating unit installed in the fuel supply tank for heat-exchanging the second liquefied gas stored in the fuel supply tank with air or heat transfer medium to raise the pressure of the fuel supply tank to a predetermined pressure. 6. The method of claim 5,
Wherein the fuel supply tank includes a first fuel supply tank and a second fuel supply tank, the volume of which is smaller and the pressure of which is larger than that of the second storage tank,
Wherein one of the first fuel supply tank and the second fuel supply tank reaches the set pressure to discharge the second liquefied gas and the other one of the first and second fuel supply tanks is operated alternately to receive the second liquefied gas from the second storage tank Fuel gas supply system. 8. The method of claim 7,
The second liquefied gas evaporation gas of the first fuel supply tank
Wherein when the pressure in the first fuel supply tank exceeds a set value, the first fuel supply tank and the second fuel supply tank are connected to each other through a heat exchange pipe provided in the first fuel supply tank and the second fuel supply tank, respectively, And the liquid fuel is recycled by sequentially exchanging heat with the stored second liquefied gas. 6. The method of claim 5,
The second liquefied gas passed through the second heat exchanger is supplied to the engine,
Wherein the engine comprises a medium pressure gas injection engine,
Wherein the pressure in the fuel supply tank is 16 to 45 bar, which is a fuel gas supply pressure condition of the medium pressure gas injection engine.

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