KR20190080360A - Boil-Off Gas Reliquefaction System and Method for Vessel - Google Patents

Abstract

A boil-off reliquefaction system for a ship comprises: a first compressor compressing boil-off gas; a second compressor installed in parallel with the first compressor to compress boil-off gas flowing to a way different from a way to the first compressor; a first heat exchanger exchanging heat with and cooling the boil-off gas compressed by the first compressor or the second compressor by using, as a coolant, the boil-off gas before being compressed by the first compressor or the second compressor; a second heat exchanger additionally exchanging heat with and cooling a fluid cooled by the first heat exchanger by using, as a coolant, the boil-off gas circulated through a coolant cycle; and a decompression device decompressing a fluid cooled by the second heat exchanger. The boil-off reliquefaction system for the ship can efficiently liquefy the boil-off gas and lower the probability of generating liquid droplets.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a boil-

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a system and a method for re-liquefying a boil-off gas (BOG) generated by natural gasification of liquefied gas.

In recent years, consumption of liquefied gas such as Liquefied Natural Gas (LNG) has been rapidly increasing worldwide. The liquefied gas obtained by liquefying the gas at a low temperature has an advantage of being able to increase the storage and transport efficiency because the volume becomes very small as compared with the gas. In addition, liquefied natural gas, including liquefied natural gas, can be removed as an eco-friendly fuel with less air pollutant emissions during combustion because air pollutants can be removed or reduced during the liquefaction process.

Liquefied natural gas is a colorless transparent liquid which can be obtained by cooling methane-based natural gas to about -163 ° C and liquefying it, and has a volume of about 1/600 as compared with natural gas. Therefore, when the natural gas is liquefied and transported, it can be transported very efficiently.

However, since the liquefaction temperature of natural gas is a cryogenic temperature of -163 ° C at normal pressure, liquefied natural gas is susceptible to temperature change and is easily evaporated. As a result, the storage tank storing the liquefied natural gas is subjected to heat insulation, but the external heat is continuously transferred to the storage tank. Therefore, in the transportation of liquefied natural gas, the liquefied natural gas is naturally vaporized continuously in the storage tank, -Off Gas, BOG) occurs.

Evaporation gas is a kind of loss and is an important issue in transport efficiency. Further, when the evaporation gas accumulates in the storage tank, the internal pressure of the tank may rise excessively, and there is a risk that the tank may be damaged. Accordingly, various methods for treating the evaporative gas generated in the storage tank have been studied. Recently, a method of re-liquefying the evaporated gas and returning it to the storage tank for treating the evaporated gas, a method of returning the evaporated gas to the storage tank And a method of using it as an energy source of a consumer.

As a method for re-liquefying the evaporation gas, there is a method of re-liquefying the evaporation gas by heat exchange with the refrigerant by providing a refrigeration cycle using a separate refrigerant, a method of re-liquefying the evaporation gas itself as a refrigerant without any refrigerant .

On the other hand, there are gas-fuel engines such as DFDE, X-DF engine and ME-GI engine which can be used natural gas among the engines used in ships.

The DFDE adopts the Otto Cycle, which consists of four strokes, and injects natural gas with a relatively low pressure of about 6.5 bar into the combustion air inlet, compressing the piston as it rises.

The X-DF engine is composed of two strokes, using natural gas of about 16 bar as fuel and adopting autocycle.

The ME-GI engine consists of two strokes and employs a diesel cycle in which high pressure natural gas at around 300 bar is injected directly into the combustion chamber at the top of the piston.

A method for re-liquefying an evaporation gas by using evaporation gas itself as a refrigerant without a separate refrigerant. The evaporation gas compressed by the compressor is cooled by heat exchange with the evaporation gas before being compressed by the compressor, expanded by a JT valve, There is a method of re-liquefying a part of the gas, and a system adopting such a method is called a PRS (Partial Re-liquefaction System).

When there is a large amount of liquefied gas in the storage tank, a large amount of evaporated gas is generated, or when there is a large amount of evaporative gas to be re-liquefied , The amount of liquefaction required only by PRS may not be satisfied.

The PRS was modified to further re-liquefy the evaporation gas, and the evaporation gas could be further cooled by the refrigerant cycle using the evaporation gas itself as the refrigerant. The system employing this method was called Mane Refrigeration System).

The present invention is to provide a system and a method for liquefying a vaporization gas for marine vessels, which is configured to improve the conventional MRS, complement the problems that have been caused by operating the MRS, and to re-liquefy the evaporation gas more efficiently.

According to an aspect of the present invention, there is provided a compressor comprising: a first compressor for compressing an evaporative gas; A second compressor installed in parallel with the first compressor for compressing other flows of evaporative gas not sent to the first compressor; A first heat exchanger that cools the evaporated gas compressed by the first compressor or the second compressor by using heat as the refrigerant before the refrigerant is compressed by the first compressor or the second compressor; A second heat exchanger for further cooling the fluid cooled by the first heat exchanger by using the evaporation gas circulating the refrigerant cycle as a refrigerant for further heat exchange; And a first decompression device for decompressing the fluid cooled by the second heat exchanger, wherein the evaporated gas compressed by the first compressor or the second compressor is sent to a fuel consumer (hereinafter, Is supplied to the first heat exchanger, and the remaining evaporation gas, which is not used in the fuel consumer, among the evaporation gases compressed by the 'fuel supply compressor' is sent to the first heat exchanger, The evaporation gas compressed by the compressor other than the 'fuel supply compressor' among the first compressor and the second compressor is sent to the refrigerant cycle (hereinafter, the compressor supplying the evaporated gas to the refrigerant cycle is referred to as a 'compressor for refrigerant cycle' ), The refrigerant cycle is compressed by the compressor for the refrigerant cycle, and then the second Pressure device; A fourth compressor for compressing the fluid used as the refrigerant in the second heat exchanger after being depressurized by the second decompression device; And a valve for controlling the flow rate of the refrigerant circulating in the refrigerant cycle. When the vessel is in an anchoring state, the opening degree of the valve is adjusted by taking the pressure value of the refrigerant circulating in the refrigerant cycle as a factor, There is provided an evaporative gas re-liquefaction system for a ship, wherein the opening degree of the valve is controlled by taking a temperature value of a refrigerant circulating in the refrigerant cycle as a factor.

The refrigerant cycle may form a closed loop connecting the refrigerant cycle compressor, the second pressure reducing device, the second heat exchanger, the fourth compressor, and the refrigerant cycle compressor again.

The evaporated gas supplied to the refrigerant cycle after being compressed by the compressor for the refrigerant cycle is cooled by the second heat exchanger and is further reduced in pressure by the second decompressor to be cooled and then returned to the second heat exchanger And can be used as a refrigerant.

Wherein the refrigerant cycle includes at least one of a refrigerant cycle compressor, a second heat exchanger, a second decompressor, a second heat exchanger, a fourth compressor, Loop can be formed.

The valve may be installed in a line that is cooled by the second heat exchanger and sent to the second decompression device so as to control the flow rate of the fluid sent to the second decompression device.

The ship evaporation gas re-liquefaction system may further include a pressure sensor installed on a line to be sent to the second heat exchanger, the pressure of which is reduced by the second pressure reducing device, and measure the pressure of the fluid, In case of berth, the valve can be adjusted in opening degree according to the pressure value measured by the pressure sensor.

The ship evaporative gas re-liquefaction system may further include a temperature sensor installed on a line which is used as a refrigerant in the second heat exchanger to be sent to the fourth compressor and measures the temperature of the fluid, The valve can be adjusted in opening degree according to the temperature value measured by the temperature sensor.

The ship evaporative gas re-liquefaction system is provided on a line that sends the evaporated gas compressed by the first compressor or the second compressor to the first heat exchanger, and is compressed by the first compressor or the second compressor And a third compressor for further compressing the evaporated gas.

The third compressor may compress the evaporation gas to 150 to 300 bar.

The third compressor may compress the evaporation gas to 150 to 170 bar.

The marine evaporation gas re-liquefaction system may further include a gas-liquid separator provided downstream of the first decompressor to separate the re-liquefied liquefied gas from the evaporated gas remaining in a gaseous state.

The evaporated gas separated by the gas-liquid separator may be combined with the evaporated gas before being used as a refrigerant in the first heat exchanger and used as a refrigerant in the first heat exchanger.

According to another aspect of the present invention, there is provided a method of operating a refrigeration cycle comprising the steps of: 1) using an evaporating gas as a refrigerant in a first heat exchanger; 2) splitting the evaporation gas used as the refrigerant of the first heat exchanger into two flows in the step 1); 3) sending the first flow to the first compressor and the remaining flow to the second compressor among the flows branched to the two flows in the step 2); 4) sending the evaporated gas compressed by the first compressor or the second compressor to the fuel consumer (hereinafter, the compressor supplying the evaporated gas to the fuel consumer is referred to as a 'fuel supply compressor'); 5) The remaining evaporation gas not used in the fuel demanding place among the evaporation gases compressed by the 'fuel supply compressor' is used as the refrigerant in the evaporation gas supplied to the first heat exchanger in the step 1) Exchanging heat by a heat exchanger; 6) sending the evaporated gas compressed by other compressors other than the 'fuel supply compressor' among the first compressor and the second compressor to the refrigerant cycle (hereinafter, the compressor supplying the refrigerant cycle evaporated gas is referred to as' Compressor '); 7) cooling the fluid cooled by the first heat exchanger in the step 5) by heat exchange using the evaporator gas circulating in the refrigerant cycle as the refrigerant by the second heat exchanger; And 8) depressurizing the fluid cooled by the second heat exchanger in step 7), and the evaporation gas circulating in the refrigerant cycle is compressed by the compressor for the refrigerant cycle ; 5-2) cooling by the second heat exchanger after being compressed in step 5-1); 5-3) After cooling in step 5-2), the pressure is reduced by the second pressure reducing device; 5-4) using the refrigerant in the second heat exchanger after being depressurized in step 5-3); And 5-5) a step of using the refrigerant as the refrigerant of the second heat exchanger and then being compressed by the fourth compressor in the step 5-4), and if the ship is docked, The control unit controls the flow rate of the evaporative gas circulating in the refrigerant cycle by using the pressure value of the refrigerant as a factor and circulates the refrigerant cycle using the temperature value of the refrigerant circulating in the refrigerant cycle as a factor There is provided a method for re-liquefying a vaporized gas for a ship, which regulates the flow rate of the evaporated gas.

The amount of the refrigerant circulating in the refrigerant cycle can be adjusted by adjusting the flow rate of the fluid that is cooled by the second heat exchanger and then sent to the second decompressor.

During the berthing of the ship, the flow rate of the evaporative gas circulating in the refrigerant cycle can be adjusted by the pressure value of the fluid sent to the second heat exchanger after being depressurized by the second decompressor.

Wherein when the pressure of the fluid sent to the second heat exchanger after the pressure is reduced by the second pressure reducing device is higher than the first set value, the flow rate of the evaporating gas circulating in the refrigerant cycle is increased, When the pressure of the fluid sent to the second heat exchanger is lower than the first predetermined value, the flow rate of the evaporative gas circulating in the refrigerant cycle can be reduced.

During the operation of the ship, the flow rate of the evaporative gas circulating in the refrigerant cycle can be adjusted by the temperature value of the fluid sent to the fourth compressor after being used as the refrigerant in the second heat exchanger.

The flow rate of the evaporative gas circulating in the refrigerant cycle is increased when the temperature of the fluid sent to the fourth compressor after the refrigerant is used as the refrigerant in the second heat exchanger is higher than the second set value, When the temperature of the fluid sent to the fourth compressor after use is lower than the second set value, the flow rate of the evaporative gas circulating in the refrigerant cycle can be reduced.

According to another aspect of the present invention, there is provided a compressor comprising: a first compressor for compressing an evaporative gas; A second compressor installed in parallel with the first compressor for compressing other flows of evaporative gas not sent to the first compressor; A first heat exchanger that cools the evaporated gas compressed by the first compressor or the second compressor by using heat as the refrigerant before the refrigerant is compressed by the first compressor or the second compressor; A second heat exchanger for further cooling the fluid cooled by the first heat exchanger by using the evaporation gas circulating the refrigerant cycle as a refrigerant for further heat exchange; A first decompression device for decompressing the fluid cooled by the second heat exchanger; And a valve for controlling a flow rate of a refrigerant circulating in the refrigerant cycle, wherein when the temperature of the fluid used as the refrigerant in the second heat exchanger is higher than a second set value, the opening degree of the valve is increased, The evaporation gas re-liquefaction system for a ship is provided which lowers the opening of the valve if the temperature of the fluid used as the refrigerant in the evaporator is lower than the second set value.

When the evaporation gas at the maximum flow rate is supplied to the refrigerant cycle, the opening degree of the valve can be adjusted by taking the pressure value of the refrigerant circulating through the refrigerant cycle as a factor.

According to the present invention, when the ship is berth, the flow rate of the evaporative gas supplied to the refrigerant cycle (RC) is adjusted based on the pressure value of the evaporative gas circulating in the refrigerant cycle (RC) Since the flow rate of the evaporation gas supplied to the refrigerant cycle RC is controlled based on the temperature value of the evaporation gas circulating in the refrigerant cycle RC, Can be supplied to the cycle (RC).

Further, according to the present invention, the flow rate of the evaporating gas circulating in the refrigerant cycle (RC) and the process of re-liquefaction can be performed even during the operation of the ship in which the amount of evaporated gas consumed in the fuel consuming destination (E) It is possible to efficiently regenerate the vaporized gas and to reduce the probability of droplet formation by appropriately controlling the flow rate of the vaporized gas.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of a vaporization gas re-liquefaction system for ships according to a preferred embodiment of the present invention.
2 is a graph schematically illustrating the phase change of methane with temperature and pressure.
3 is a graph showing the temperature values of methane according to the heat flow rate under different pressures, respectively.
FIGS. 4 and 5 are graphs showing the amount of resolidification according to the evaporation gas pressure in the PRS (Partial Re-liquefaction System). FIG.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The system and method for liquefying the ship's evaporative gas according to the present invention can be applied to various applications such as a ship equipped with an engine using natural gas as fuel, a ship including a liquefied gas storage tank, or an offshore structure. 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 fluid in each line of the present invention may be in any one of a liquid state, a gas-liquid mixed state, a gas state, and a supercritical fluid state, depending on operating conditions of the system.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of a vaporization gas re-liquefaction system for ships according to a preferred embodiment of the present invention.

Referring to FIG. 1, the evaporative gas re-liquefaction system for a ship according to the present embodiment includes a first heat exchanger 110, a first compressor 210, a second compressor 220, a second heat exchanger 120, Device 410, a refrigerant cycle (RC), and a bypass line (BL).

The first heat exchanger 110 is operated by the first compressor 210 or the second compressor 220 by using the evaporation gas before being compressed by the first compressor 210 or the second compressor 220 as a refrigerant. Cool the compressed evaporated gas.

The evaporating gas used as the refrigerant in the first heat exchanger 110 may be evaporated gas discharged from the storage tank T. [

The evaporated gas used as the refrigerant in the first heat exchanger 110 is diverted into two flows, one stream is sent to the first compressor 210 and the other stream is sent to the second compressor 220.

The first compressor 210 is used as a refrigerant in the first heat exchanger 110, and then compresses one of the evaporative gases branched into two flows. The first compressor 210 may be a multi-stage compressor, and a first cooler 310 may be installed downstream of the first compressor 210 to cool the evaporated gas compressed by the first compressor 210.

The second compressor 220 is installed in parallel with the first compressor 210 and is used as a refrigerant in the first heat exchanger 110 and then sent to the first compressor 210 among the evaporated gases branched into two flows Compress the remaining flow. The second compressor 220 may be a multi-stage compressor, and a second cooler 320 may be installed downstream of the second compressor 220 to cool the evaporated gas compressed by the second compressor 220.

Either one of the first compressor 210 and the second compressor 220 supplies the evaporative gas to the fuel consumer E and the other one supplies the evaporative gas to the refrigerant cycle RC. In addition, among the evaporated gas compressed by the compressor that supplies the evaporated gas to the fuel demand site E, the surplus evaporated gas not used in the fuel demand site E is sent to the first heat exchanger 110 and subjected to a liquefaction process .

The fuel demand (E) includes the ME-GI engine, which uses approximately 300 bar of natural gas as fuel, the X-DF engine, which uses approximately 16 bar of natural gas as fuel, and DF An engine (DFGE, DFDE), and a gas combustion unit (GCU).

The compressor that supplies the fuel to the fuel demand destination E among the first compressor 210 and the second compressor 220 when the fuel demanding entity E is an engine compresses the evaporation gas at the required pressure of the fuel demand site E .

The ship's regulations require that a compressor that supplies fuel to the engine be designed with redundancy in case of an emergency. Redundancy design means that when one of the compressors can not be used for reasons of failure, maintenance, etc., It means to design to be able to use.

In the present embodiment, the first compressor 210 and the second compressor 220 may serve as redundancies. Conventionally, one of the first compressor 210 and the second compressor 220 evaporates (E), and the other unused one is put in the standby state. If the compressor which supplied the evaporative gas to the fuel demand point (E) can not be used, ) State compressor to supply the evaporative gas to the fuel consumer (E).

However, according to the conventional operating method, although the probability that the compressor used as the evaporative gas can not be used at the fuel demand site E is low and the duration is not long even if it occurs, the emergency situation There is a problem in that a redundant compressor is installed and the extra compressor is kept in a stand-by state in order to prepare, so that the actual dangerous cost is wasted.

According to the present embodiment, when both the first compressor 210 and the second compressor 220 can be normally used, one is used for supplying the fuel to the fuel consumer E and the other is used for the refrigerant cycle When the compressor used for supplying the evaporative gas to the fuel demand site E can not be used, the evaporative gas is supplied to the refrigerant cycle RC to regain the re-liquefaction amount and the re-liquefaction efficiency And supplies the evaporated gas to the fuel consuming destination E by means of the compressor that supplied the evaporative gas to the refrigerant cycle RC.

Therefore, according to the present embodiment, there is an advantage that the re-liquefaction amount and the re-liquefaction efficiency can be improved by utilizing an extra compressor installed to prepare for an emergency situation while satisfying the ship regulations requiring redundancy design.

It is preferable that the first compressor 210 and the second compressor 220 are compressors having the same performance so that they can serve as redundancies.

The second heat exchanger 120 compresses the refrigerant by the first compressor 210 or the second compressor 220 using the evaporation gas circulating the refrigerant cycle RC as the refrigerant, Is further cooled by heat exchange. The fluid further cooled by the second heat exchanger (120) is sent to the first pressure reducing device (410).

According to the present embodiment, the evaporated gas is further cooled not only in the first heat exchanger 110 but also in the second heat exchanger 120 so that the evaporated gas cooled only by the first heat exchanger 110 flows into the first decompressor 410, the evaporated gas in a lowered temperature state is sent to the first pressure reducing device 410, so that the re-liquefaction efficiency and the liquefaction amount are increased. The following is a detailed description.

2 is a graph schematically illustrating the phase change of methane with temperature and pressure. Referring to FIG. 2, methane enters a supercritical fluid state at a temperature of approximately -80 占 폚 or higher and a pressure of approximately 55 bar or higher. That is, in the case of methane, the critical point is about -80 ° C, 55 bar. The supercritical fluid state is a third state different from the liquid state or gas state.

When the evaporation gas has a temperature lower than the critical point at a pressure equal to or higher than the critical point, it may be in a state similar to the supercritical fluid state having a higher density than the general liquid state. The evaporation gas having a pressure higher than the critical point and a temperature lower than the critical point State is hereinafter referred to as "high-pressure liquid state ".

The evaporation gas sent to the first heat exchanger 110 for the re-liquefaction process may be in a gaseous state or in a supercritical fluid state depending on the degree of compression. When the evaporated gas sent to the first heat exchanger 110 is in a gaseous state, the evaporated gas in the gaseous state passes through the first heat exchanger 110 and the temperature is lowered to become a mixed state of the liquid and the gas, 1 heat exchanger 110 is in the supercritical fluid state, the fluid in the supercritical fluid state passes through the first heat exchanger 110 and becomes low in temperature to be in the " high pressure liquid state ".

The temperature of the fluid cooled by the first heat exchanger 110 is lowered while passing through the second heat exchanger 120. When the fluid that has passed through the first heat exchanger 110 is in a mixed state of liquid and gas , The fluid in the liquid mixed state with the gas passes through the second heat exchanger 120 and becomes lower in temperature so that the ratio of the liquid becomes higher or becomes the liquid state and passes through the first heat exchanger 110 When the fluid is in the " high pressure liquid state ", the fluid in the "high pressure liquid state" passes through the second heat exchanger 120 and becomes the "high pressure liquid state "

In addition, even if the fluid that has passed through the second heat exchanger 120 is in the "high pressure liquid state ", the fluid of the" high pressure liquid state "through the second heat exchanger 120 passes through the first pressure reducing device 410 The pressure is lowered to become a liquid state or a mixture state of liquid and gas.

Even if the pressure of the evaporation gas is lowered to the same degree (P in FIG. 2) by the first pressure reducing device 410, the temperature is lower than that in the case where the pressure is reduced in the higher temperature state (X → X ' (Y - > Y 'in Fig. 2), the ratio of liquid becomes higher. In addition, it is theoretically possible to 100% re-liquefy the evaporation gas (Z → Z 'in FIG. 2) if the temperature can be further lowered. Therefore, when the fluid cooled by the first heat exchanger 110 is further cooled by the second heat exchanger 120 and then sent to the first pressure reducing device 410, the re-liquefaction efficiency and the liquefaction amount are increased.

The first decompression device 410 compresses the evaporated gas cooled by the first heat exchanger 110 and the second heat exchanger 120 after being compressed by the first compressor 210 or the second compressor 220, . The first decompression device 410 includes all the means capable of decompressing and cooling the evaporation gas, and may be an expansion valve such as a Joule-Thomson valve or an expander. In the present embodiment, it is preferable that the first pressure reducing device 410 is an expansion valve. The expansion valve has the advantage that the price is lower than the inflator and the risk of failure is less.

The compression process by the first compressor 210 or the second compressor 220 and the cooling process by the first heat exchanger 110 and the second heat exchanger 120 are performed by the first decompressor 410 or the second decompressor 410, Some or all of the evaporated gas that has undergone the process is re-liquefied.

The marine evaporation gas re-liquefaction system of this embodiment may further include a gas-liquid separator 500 disposed downstream of the first decompressor 410 for separating the re-liquefied liquefied gas from the remaining vaporized gas .

The liquefied gas separated by the gas-liquid separator 500 can be sent to the storage tank T and the evaporated gas separated by the gas-liquid separator 500 can be sent to the evaporator 200 before being used as a refrigerant in the first heat exchanger 110 And can be used as a refrigerant in the first heat exchanger 110. [

When the first heat exchanger 110 uses the evaporated gas discharged from the storage tank T as a refrigerant, the evaporated gas separated by the gas-liquid separator 500 is mixed with the evaporated gas discharged from the storage tank T And may be sent to the first heat exchanger 110.

The evaporated gas separated by the gas-liquid separator 500 may be separately used as a refrigerant in the first heat exchanger 110 without being merged with the evaporated gas before being used as a refrigerant in the first heat exchanger 110 In this case, the first heat exchanger 110 may be composed of three flow paths.

If the ship evaporative gas re-liquefaction system of this embodiment does not include the gas-liquid separator 500, the evaporated gas partially or fully re-liquefied may be sent directly to the storage tank T from the first decompressor 410.

The refrigerant cycle RC in which the evaporation gas used as the refrigerant in the second heat exchanger 120 is circulated includes the second decompression device 420 and the fourth compressor 240.

The second decompression device 420 reduces the temperature by reducing the pressure of the evaporation gas supplied to the refrigerant cycle RC after being compressed by the first compressor 210 or the second compressor 220. The second decompression device 420 includes all the means capable of decompressing and cooling the evaporation gas, and may be an expansion valve such as a Joule-Thomson valve or an expander. In the present embodiment, it is preferable that the second decompressor 420 is an expander.

The fluid depressurized by the second pressure reducing device 420 is supplied to the second heat exchanger 120 and is used as a refrigerant for further cooling the fluid cooled by the first heat exchanger 110.

The evaporated gas supplied to the refrigerant cycle (RC) after being compressed by the first compressor (210) or the second compressor (220) is supplied to the second heat exchanger (120) before being depressurized by the second decompressor It can pass. In this case, the evaporated gas supplied to the refrigerant cycle (RC) after being compressed by the first compressor (210) or the second compressor (220) is heat-exchanged by the second heat exchanger (120) The refrigerant is further decompressed and cooled by the second heat exchanger 420 and then sent again to the second heat exchanger 120 to be used as a refrigerant.

The fourth compressor 240 compresses the fluid used as the refrigerant in the second heat exchanger 120 and maintains a constant pressure average of the evaporated gas circulating through the refrigerant cycle RC. The fourth compressor 240 may be driven by the second pressure reducing device 420 and the compander C so that the second pressure reducing device 420 may be driven by the power generated by expanding the fluid and the fourth compressor 240 A fourth cooler 340 for cooling the evaporated gas compressed by the fourth compressor 240 may be installed downstream.

According to the evaporative gas re-liquefaction system for ships of this embodiment, the evaporated gas compressed by the fourth compressor 240 can be sent upstream of the first compressor 210 or can be sent to the upstream of the second compressor 220, 1 compressor 210 to constitute a refrigerant cycle RC and may include a second compressor 220 to constitute a refrigerant cycle.

When the evaporated gas compressed by the first compressor 210 is supplied to the fuel consumer E and the evaporated gas compressed by the second compressor 220 is supplied to the refrigerant cycle RC, The refrigerant cycle RC of the closed loop connecting the second compressor 220, the second decompressor 420, the second heat exchanger 120, the fourth compressor 240, and the second compressor 220 is formed. When the evaporated gas supplied to the refrigerant cycle RC is cooled by the second heat exchanger 120 and then sent to the second decompressor 420, the second compressor 220, the second heat exchanger 120, A refrigerant cycle RC of a closed loop connecting the second decompression device 420, the second heat exchanger 120, the fourth compressor 240 and the second compressor 220 is formed.

When the evaporated gas compressed by the first compressor 210 is supplied to the refrigerant cycle RC and the evaporated gas compressed by the second compressor 220 is supplied to the fuel consumer E, A refrigerant cycle RC of a closed loop connecting the first compressor 210, the second decompressor 420, the second heat exchanger 120, the fourth compressor 240, and the first compressor 210 is formed. When the evaporated gas supplied to the refrigerant cycle RC is cooled by the second heat exchanger 120 and then sent to the second decompressor 420, the first compressor 210, the second heat exchanger 120, The refrigerant cycle RC of the closed loop connecting the second decompression device 420, the second heat exchanger 120, the fourth compressor 240, and the first compressor 210 again is formed.

According to the present embodiment, any one of the first compressor 210 and the second compressor 220 may be selected to supply the evaporative gas to the fuel demanding entity E or the first heat exchanger 110, And the refrigerant cycle (RC) can be circulated to the first heat exchanger (110) by the evaporated gas compressed by the other compressor that does not supply the evaporative gas, so that the operation of the system is advantageous.

According to the present embodiment, there is an advantage that the re-liquefaction efficiency and the liquefaction amount of the evaporation gas can be increased by utilizing the redundancy compressor which is conventionally installed on the ship but is not normally used.

The refrigerant cycle (RC) further includes a valve (V) for regulating the flow rate of the refrigerant circulating in the refrigerant cycle (RC). The valve V is installed in a line that is cooled by the second heat exchanger 120 to be sent to the second decompressor 420 and controls the flow rate of the fluid to be sent to the second decompressor 420 .

The control of the valve (V) when the ship is anchored and the ship is operated is as follows.

[When vessel is at bay]

When the ship is at anchor and does not supply fuel to the propulsion engines such as the ME-GI engine and the X-DF engine, there is almost no evaporated gas consumed at the fuel demand site (E), and thus the amount of evaporative gas to be re- . The evaporating gas passing through the re-liquefaction process is cooled not only by the first heat exchanger 110 but also by the second heat exchanger 120, so that the first decompressor 410 And supplies the evaporating gas at the maximum flow rate to the refrigerant cycle (RC).

In this way, when the evaporation gas at the maximum flow rate is supplied to the refrigerant cycle (RC) due to a large amount of evaporative gas to be re-liquefied during the anchoring of the ship, the pressure value of the refrigerant circulating in the refrigerant cycle (RC) ) To regulate the opening of the valve (V).

Specifically, during the berthing of the ship, the opening degree of the valve V can be adjusted by the pressure value of the fluid sent to the second heat exchanger 120 after the pressure is reduced by the second pressure reducing device 420. Since the refrigerant circulating in the refrigerant cycle RC is depressurized by the second decompressor 420 and has the lowest pressure and temperature, during the berthing of the ship, the refrigerant is decompressed by the second decompressor 420, It is preferable to adjust the opening degree of the valve V by taking the pressure value of the fluid sent to the heat exchanger 120 as a factor.

A pressure sensor is provided between the second pressure reducing device 420 and the second heat exchanger 120 to measure the pressure value of the fluid sent to the second heat exchanger 120 after the pressure is reduced by the second pressure reducing device 420. [ (610). The pressure value measured by the pressure sensor 610 is transmitted to the controller 630. The controller 630 calculates the opening degree of the valve V by taking the pressure value measured by the pressure sensor 610 as a factor Can be adjusted.

If the pressure P 'measured by the pressure sensor 610 is higher than the first set value P (P'> P), the opening degree of the valve V is increased to increase the flow rate of the refrigerant circulating in the refrigerant cycle RC And the refrigerant is circulated in the refrigerant cycle RC by lowering the opening degree of the valve V when the pressure P 'measured by the pressure sensor 610 is lower than the first set value P (P' <P) .

It is determined that the pressure P 'measured by the pressure sensor 610 is higher than the first set value P (P'> P) because the second pressure reducing device 420 does not supply a sufficient amount of fluid, Since the pressure reducing device 420 means that the fluid is less decompressed, the flow rate of the fluid flowing into the second decompressing device 420 is increased by increasing the opening degree of the valve V. When the flow rate of the fluid flowing into the second pressure reducing device 420 increases and the fluid of the flow rate required by the second pressure reducing device 420 is supplied to the second pressure reducing device 420, The pressure can be reduced by the pressure.

In addition, the fact that the pressure P 'measured by the pressure sensor 610 is lower than the first set value P (P' <P) indicates that the fluid is excessively depressurized by the second pressure reducing device 420 When the fluid at a flow rate exceeding the flow rate required by the second pressure reducing device 420 is supplied to the second pressure reducing device 420, the second pressure reducing device 420 can reduce the fluid beyond the set pressure have.

Accordingly, when the pressure P 'measured by the pressure sensor 610 is lower than the first set value P (P' <P), the opening degree of the valve V is lowered, Thereby reducing the flow rate of the fluid. When the flow rate of the fluid flowing into the second pressure reducing device 420 decreases and the fluid of the flow rate required by the second pressure reducing device 420 is supplied to the second pressure reducing device 420, The pressure can be reduced by the pressure.

[Ship Operated  Occation]

The evaporation gas is used as a refrigerant for use in the fuel consumer (E), or sent to the first heat exchanger (110) for re-liquefaction or circulating in the refrigerant cycle (RC) When the amount of gas is increased, the amount of remaining evaporation gas that is subjected to the re-liquefaction process or sent to the refrigerant cycle (RC) is reduced.

However, since the evaporation gas is sent to the refrigerant cycle (RC) to be used as a refrigerant for re-liquefying the evaporated gas, even if the amount of remaining evaporative gas sent through the re-liquefaction process or the refrigerant cycle (RC) If the same amount of evaporation gas is sent to the refrigerant cycle (RC), the amount of refrigerant circulating in the refrigerant cycle (RC) becomes excessively larger than the evaporative gas to be re-liquefied, and the amount of evaporative gas to be re-liquefied is inefficient.

When the ship starts to operate and the evaporative gas is supplied to the fuel demand site (E) such as the propulsion engine, the amount of the remaining evaporative gas that is subjected to the re-liquefaction process or sent to the refrigerant cycle (RC) is reduced, The higher the amount of evaporative gas used in the propulsion engine, the more the amount of evaporative gas sent to the refrigerant cycle (RC) is reduced.

Therefore, when the ship starts to operate, it may be necessary to reduce the flow rate of the evaporative gas circulating in the refrigerant cycle (RC). According to the present embodiment, when the ship is operated, the refrigerant circulating in the refrigerant cycle The opening degree of the valve (V) is controlled with the temperature value as a factor to control the flow rate of the evaporative gas sent to the refrigerant cycle (RC).

Specifically, during the operation of the ship, the opening degree of the valve V can be adjusted by the temperature value of the fluid that is used as the refrigerant in the second heat exchanger 120 and then sent to the fourth compressor 240. Knowing the temperature of the fluid used as the refrigerant in the second heat exchanger 120 can determine whether the flow rate of the evaporative gas circulating in the refrigerant cycle (RC) is more appropriate than the flow rate of the evaporative gas re-liquefied, It is preferable to adjust the opening degree of the valve V by using the temperature value of the fluid sent to the fourth compressor 240 after being used as the refrigerant in the second heat exchanger 120 as a factor.

A temperature sensor (not shown) is installed between the second heat exchanger 120 and the fourth compressor 240 to measure the temperature value of the fluid that is used as the refrigerant in the second heat exchanger 120 and then sent to the fourth compressor 420 620 may be installed. The pressure value measured by the temperature sensor 620 is transmitted to the controller 630. The controller 630 calculates the opening degree of the valve V by using the pressure value measured by the temperature sensor 620 as a factor Can be adjusted.

If the temperature T 'measured by the temperature sensor 620 is higher than the second set value T (T'> T), the valve V is opened to increase the flow rate of the refrigerant circulating in the refrigerant cycle RC And the refrigerant is circulated in the refrigerant cycle RC when the temperature T 'measured by the temperature sensor 620 is lower than the second set value T (T' <T) .

(T '> T) that the temperature T' measured by the temperature sensor 620 is higher than the second set value T, the refrigerant circulating in the refrigerant cycle RC flows from the second heat exchanger 120 It means that the amount of the evaporating gas circulating in the refrigerant cycle (RC) is smaller than the flow rate of the evaporating gas to be re-liquefied. Accordingly, when the temperature T 'measured by the temperature sensor 620 is higher than the second set value T (T'> T), the degree of opening of the valve V is increased and the refrigerant circulating in the refrigerant cycle RC Increase the flow rate.

In addition, the fact that the temperature T 'measured by the temperature sensor 620 is lower than the second set value T (T' <T) indicates that the refrigerant circulating in the refrigerant cycle RC flows through the second heat exchanger 120, it can be judged that the amount of the evaporative gas circulating in the refrigerant cycle RC is larger than the flow rate of the evaporative gas to be re-liquefied. Therefore, when the temperature T 'measured by the temperature sensor 620 is lower than the second set value T (T' <T), the opening degree of the valve V is lowered, and the refrigerant circulating in the refrigerant cycle RC .

According to the present embodiment, even when the ship is operated in which the amount of the evaporative gas consumed in the fuel consuming destination E is increased or decreased according to the speed of the ship, the flow rate of the evaporative gas circulating in the refrigerant cycle RC, There is an advantage that the evaporation gas can be re-liquefied efficiently by appropriately controlling the flow rate of the evaporation gas.

Further, when the flow rate of the evaporation gas circulating in the refrigerant cycle RC is larger than the flow rate of the evaporation gas to be re-liquefied, the average temperature of the evaporation gas circulating in the refrigerant cycle RC is lowered, When the droplet is introduced into the second decompressing device 420, it can suffer fatal damage. According to the present embodiment, even when operating the ship in which the amount of the evaporative gas consumed in the fuel consuming destination E is increased or decreased according to the speed of the ship , The flow rate of the evaporating gas circulating in the refrigerant cycle (RC) and the flow rate of the evaporating gas passing through the re-liquefaction process are appropriately controlled to maintain the average temperature of the evaporating gas circulating in the refrigerant cycle (RC) And there is an advantage that the probability of droplet occurrence can be lowered.

The evaporative gas re-liquefaction system for a ship according to the present embodiment is installed on a line for sending the evaporated gas compressed by the first compressor 210 or the second compressor 220 to the first heat exchanger 110, 210) or a third compressor (230) for further compressing the evaporated gas compressed by the second compressor (220). A third cooler 330 for cooling the evaporated gas compressed by the third compressor 230 may be installed downstream of the third compressor 230.

The reason why the third compressor 230 further compresses the evaporated gas that is compressed by the first compressor 210 or the second compressor 220 and then sent to the first heat exchanger 110 is that the re- The pressure of the evaporation gas is increased to increase the liquefaction amount and the re-liquefaction efficiency.

FIG. 3 is a graph showing the temperature values of methane according to the heat flow rate under different pressures. Referring to FIG. 3, it can be seen that the higher the pressure of the evaporation gas subjected to the re-liquefaction process, the higher the efficiency of the self-heat exchange. Self-heat self-exchange means that cold evaporation gas itself is used as refrigerant and heat is exchanged at high temperature evaporation gas.

3 (a) shows the state of each fluid in the upstream and downstream of the second heat exchanger 120 when the ship's evaporation gas re-liquefaction system of the present embodiment does not include the third compressor 230 And FIG. 3 (b) shows the state of each fluid in the upstream and downstream of the second heat exchanger 120 when the ship's evaporative-gas re-liquefaction system of the present embodiment includes the third compressor 230.

3, the evaporated gas supplied to the refrigerant cycle (RC) after being compressed by the first compressor (210) or the second compressor (220) is cooled by the second heat exchanger (120) 420 and then supplied to the second heat exchanger 120 again.

The uppermost graph I of Figures 3 (a) and 3 (b) shows the fluid state at point P1 in Figure 1 supplied to the second heat exchanger 120 and the lowermost graph L shows the second heat exchange 1, which is fed back to the second heat exchanger 120 to be used as a refrigerant after passing through the first and second decompression devices 120 and 420, The overlapped graph J shows the fluid state at the point P3 in FIG. 1, which is supplied to the second heat exchanger 120 after passing through the first heat exchanger 110. In FIG.

Since the fluid used as the refrigerant is deprived of the cold heat during the heat exchange process and the temperature gradually increases, the graph L advances from the left to the right according to the passage of time, and the fluid cooled by heat exchange with the refrigerant is cooled from the refrigerant in the heat exchange process Since the temperature is gradually decreased due to the supply, the graph I and the graph J proceed from right to left as time passes.

A graph K in the middle part of FIGS. 3 (a) and 3 (b) is a combination of graph I and graph J. That is, the fluid used as the refrigerant in the second heat exchanger 120 is drawn in a graph L, and the fluid cooled by heat exchange with the refrigerant in the second heat exchanger 120 is drawn in a graph K.

In designing the heat exchanger, the temperature and the heat flow of the fluid supplied to the heat exchanger (that is, the fluid at the points P1, P2, and P3 in FIG. 1) are fixed and the temperature of the fluid used as the refrigerant is controlled So that the logarithmic mean temperature difference (LMTD) can be minimized while preventing the graph L from crossing over the graph K so that the graph L does not appear above the graph K.

The logarithmic mean temperature difference (LMTD) is the temperature difference between the low-temperature fluid and the low-temperature fluid in the opposite direction and the opposite direction. In the case of countercurrent flow, the low-temperature fluid passes through the heat exchanger And the temperature after the high-temperature fluid has passed through the heat exchanger is th2 and d1 = th2-tc1, d2 = th1-tc2, d1) / ln (d2 / d1). As the logarithmic mean temperature difference is smaller, the efficiency of the heat exchanger increases.

The logarithmic mean temperature difference LMTD on the graph is represented by the interval between the low temperature fluid used as the coolant (graph L in FIG. 3) and the high temperature fluid cooled by heat exchange with the coolant (graph K in FIG. 3) (B) of FIG. 3 shows that the interval between the graph L and the graph K is narrower than the interval between the graph L and the graph K.

This difference is due to the fact that the initial value of the graph J, which is the point indicated by the round circle, that is, the pressure of the fluid at the point P3 in FIG. 1 fed to the second heat exchanger 120 after passing through the first heat exchanger 110 (B) of FIG. 3 is higher than that of FIG. 3 (a).

That is, as a result of the simulation, in the case of FIG. 3A in which the third compressor 230 is not included, the fluid at the point P3 in FIG. 1 may be approximately -111 DEG C and 20 bar, The fluid at point P3 in FIG. 1 may be approximately -90 DEG C, 50 bar, and under these initial conditions, the heat exchanger may be used to minimize the logarithmic mean temperature difference (LMTD) In the case of FIG. 3 (b) in which the pressure of the evaporative gas passing through the re-liquefaction process is designed, the efficiency of the heat exchanger becomes higher, and as a result, the total liquefaction amount and re-liquefaction efficiency of the entire system become high.

3 (a), when the flow rate of the evaporation gas used as the refrigerant in the second heat exchanger 120 is approximately 6401 kg / h, the refrigerant is heat-exchanged with the refrigerant from the fluid (graph L) (Graph K) is approximately 585.4 kW and the flow rate of the re-liquefied vapor is approximately 3441 kg / h.

3 (b), when the flow rate of the evaporation gas used as the refrigerant in the second heat exchanger 120 is approximately 5368 kg / h, the refrigerant is heat-exchanged with the refrigerant from the fluid (graph L) (Graph K) is approximately 545.2 kW, and the flow rate of the re-liquefied evaporation gas is approximately 4325 kg / h.

That is, if the pressure of the evaporative gas including the third compressor 230 is re-liquefied, a larger amount of the evaporated gas can be re-liquefied even if less refrigerant is used.

When the evaporator is further cooled by the third compressor 230 to increase the amount of re-liquefaction and re-liquefaction efficiency, the entire amount of evaporation gas can be re-liquefied without further cooling the evaporator by the second heat exchanger 120 The time required to supply the evaporative gas to the refrigerant cycle RC is reduced and thus the effect of the redundancy design that the compressor for supplying the evaporative gas to the fuel demand site E is prepared is sufficiently secured can do.

In the meantime, it will be appreciated that the evaporative gas re-liquefaction system of the present embodiment may advantageously include the third compressor 230 in some cases, and the preferred pressure for the third compressor 230 to compress the evaporative gas will be as follows.

FIGS. 4 and 5 are graphs showing the amount of liquefaction according to the evaporation gas pressure in a PRS (Partial Re-liquefaction System). The evaporative gas to be re-liquefied refers to the evaporated gas which is cooled and re-liquefied, and is named to distinguish it from the evaporative gas used as the refrigerant.

4 and 5 are graphs showing the re-liquefaction amount according to the evaporation gas pressure in the PRS, so that the re-liquefaction amount is lower than that of the MRS in which the evaporation gas is additionally re-liquefied by the evaporation gas circulating in the refrigerant cycle . In the case of MRS, about 3300 kg of evaporative gas per hour can be re-liquefied.

4 and 5, it can be seen that when the pressure of the evaporation gas is in the vicinity of 150 to 170 bar, the re-liquefaction amount shows the maximum value, and when the pressure is 150 to 300 bar, there is almost no change in the liquefaction amount.

The evaporated gas compressed by the first compressor 210 and the second compressor 220 at the required pressure of the fuel consumer E is sent to the fuel consumer E and the evaporated gas is fed to the fuel consumer E A surplus evaporated gas not used in the fuel demand point E is sent to the first heat exchanger 110 among the evaporated gases compressed by the supplying compressor to be subjected to a liquefaction process so that the evaporation gas re- When the third compressor (230) is not included, a part of the evaporated gas compressed at the required pressure of the fuel consuming area (E) is sent to the first heat exchanger (110)

In the case of an engine using natural gas of 150 bar or more, such as ME-GI engine in which the demand for fuel (E) is natural gas of about 300 bar, the pressure required by the fuel demand point (E) However, when the fuel demand (E) is consumed at about 16 bar of the natural gas as the fuel, the X- In the case of a DF engine or a DF engine (DFGE, DFDE) using natural gas of about 6.5 bar as a fuel, in the case of an engine using natural gas less than 150 bar as fuel, the third compressor 230, And then subjected to a re-liquefaction process.

Further, it is preferable that the third compressor 230 compress the evaporation gas to approximately 150 to 300 bar, more preferably approximately 150 to 170 bar, so as to secure the maximum amount of resolidification . Further, since the energy consumed by the third compressor 230 can be reduced as the degree to which the third compressor 230 compresses the evaporation gas is reduced, the third compressor 230 further preferably has a capacity of about 150 bar So that the evaporation gas can be compressed.

It is generally sufficient that the third compressor 230 has approximately one half capacity of the first compressor 210 or the second compressor 220. [

On the other hand, when the amount of the liquefied gas stored in the storage tank T is small and the amount of the evaporated gas discharged from the storage tank T is small, or when there is a large amount of evaporated gas used as fuel in the fuel demand site E such as the engine The second heat exchanger 120 bypasses the first heat exchanger 120 and the second heat exchanger 120 directly bypasses the first heat exchanger 110. In this case, It may be sent to the decompression apparatus 410 and operated in the same manner as PRS.

Since it is not necessary to supply the refrigerant to the second heat exchanger 120 when the evaporative gas passing through the re-liquefaction process is cooled only by the first heat exchanger 110 and the second heat exchanger 120 is bypassed, It may not supply the evaporation gas to the cycle RC.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. It is.

T: Storage tank RC: Refrigerant cycle
C: Compander E: Fuel Consumer
110: first heat exchanger 120: second heat exchanger
210: first compressor 220: second compressor
230: third compressor 240: fourth compressor
310: first cooler 320: second cooler
330: third cooler 340: fourth cooler
410: First decompression device 420: Second decompression device
500: gas-liquid separator 610: pressure sensor
620: Temperature sensor 630: Control device

Claims (20)

A first compressor for compressing the evaporation gas;
A second compressor installed in parallel with the first compressor for compressing other flows of evaporative gas not sent to the first compressor;
A first heat exchanger that cools the evaporated gas compressed by the first compressor or the second compressor by using heat as the refrigerant before the refrigerant is compressed by the first compressor or the second compressor;
A second heat exchanger for further cooling the fluid cooled by the first heat exchanger by using the evaporation gas circulating the refrigerant cycle as a refrigerant for further heat exchange;
And a first decompression device for decompressing the fluid cooled by the second heat exchanger,
The evaporated gas compressed by the first compressor or the second compressor is sent to a fuel demanding place (hereinafter, the compressor supplying the evaporating gas to the fuel demanding place is referred to as a 'fuel supplying compressor'),
The remaining evaporation gas that is not used in the fuel demanding place among the evaporation gases compressed by the 'fuel supply compressor' is sent to the first heat exchanger,
The evaporation gas compressed by the remaining compressors other than the 'fuel supply compressor' among the first compressor and the second compressor is sent to the refrigerant cycle (hereinafter, the compressor supplying the evaporated gas to the refrigerant cycle is referred to as'',
Wherein the refrigerant cycle includes:
A second decompression device for decompressing the fluid supplied to the refrigerant cycle after being compressed by the compressor for the refrigerant cycle;
A fourth compressor for compressing the fluid used as the refrigerant in the second heat exchanger after being depressurized by the second decompression device; And
And a valve for controlling the flow rate of the refrigerant circulating in the refrigerant cycle,
And controlling the opening of the valve with the pressure value of the refrigerant circulating in the refrigerant cycle as a factor,
Wherein when the ship is in operation, the opening degree of the valve is adjusted by taking the temperature value of the refrigerant circulating in the refrigerant cycle as a factor. The method according to claim 1,
Wherein the refrigerant cycle forms a closed loop connecting the compressor for the refrigerant cycle, the second decompressor, the second heat exchanger, the fourth compressor, and the compressor for the refrigerant cycle again, Gas re-liquefaction system. The method according to claim 1,
The evaporated gas supplied to the refrigerant cycle after being compressed by the compressor for the refrigerant cycle is cooled by the second heat exchanger and is further reduced in pressure by the second decompressor to be cooled and then returned to the second heat exchanger And is used as a refrigerant. The method of claim 3,
Wherein the refrigerant cycle includes at least one of a refrigerant cycle compressor, a second heat exchanger, a second decompressor, a second heat exchanger, a fourth compressor, A vapor liquefaction system for ships, forming a loop. The method of claim 3,
Wherein the valve is disposed in a line that is cooled by the second heat exchanger to be sent to the second decompression device to regulate a flow rate of the fluid to be sent to the second decompression device. The method according to any one of claims 1 to 5,
Further comprising a pressure sensor installed on a line to be sent to the second heat exchanger, wherein the fluid depressurized by the second pressure reducing device measures the pressure of the fluid,
Wherein the valve is adjusted in opening degree according to a pressure value measured by the pressure sensor when the ship is at anchor. The method according to any one of claims 1 to 5,
Further comprising a temperature sensor installed on a line which is used as a refrigerant in the second heat exchanger to be sent to the fourth compressor to measure the temperature of the fluid,
Wherein the opening degree of the valve is adjusted according to a temperature value measured by the temperature sensor when the ship is in operation. The method according to any one of claims 1 to 5,
A third compressor for compressing the evaporated gas compressed by the first compressor or the second compressor and a third compressor for compressing the evaporated gas compressed by the first compressor or the second compressor, Further comprising a compressor. The method of claim 8,
And the third compressor compresses the evaporation gas to 150 to 300 bar. The method of claim 9,
And the third compressor compresses the evaporation gas to 150 to 170 bar. The method according to any one of claims 1 to 5,
Further comprising a gas-liquid separator provided downstream of the first decompression device for separating the re-liquefied liquefied gas and the vaporized gas remaining in a gaseous state. The method of claim 11,
Wherein the evaporated gas separated by the gas-liquid separator is combined with the evaporated gas before being used as a refrigerant in the first heat exchanger and is used as a refrigerant in the first heat exchanger. 1) using evaporative gas as a refrigerant in a first heat exchanger;
2) splitting the evaporation gas used as the refrigerant of the first heat exchanger into two flows in the step 1);
3) sending the first flow to the first compressor and the remaining flow to the second compressor among the flows branched to the two flows in the step 2);
4) sending the evaporated gas compressed by the first compressor or the second compressor to the fuel consumer (hereinafter, the compressor supplying the evaporated gas to the fuel consumer is referred to as a 'fuel supply compressor');
5) The remaining evaporation gas not used in the fuel demanding place among the evaporation gases compressed by the 'fuel supply compressor' is used as the refrigerant in the evaporation gas supplied to the first heat exchanger in the step 1) Exchanging heat by a heat exchanger;
6) sending the evaporated gas compressed by other compressors other than the 'fuel supply compressor' among the first compressor and the second compressor to the refrigerant cycle (hereinafter, the compressor supplying the refrigerant cycle evaporated gas is referred to as' Compressor ');
7) cooling the fluid cooled by the first heat exchanger in the step 5) by heat exchange using the evaporator gas circulating in the refrigerant cycle as the refrigerant by the second heat exchanger; And
8) reducing the pressure of the fluid cooled by the second heat exchanger in the step 7)
The evaporation gas circulating through the refrigerant cycle is supplied to the evaporator
5-1) compressing the refrigerant by the refrigerant cycle compressor;
5-2) cooling by the second heat exchanger after being compressed in step 5-1);
5-3) After cooling in step 5-2), the pressure is reduced by the second pressure reducing device;
5-4) using the refrigerant in the second heat exchanger after being depressurized in step 5-3); And
5-5) In step 5-4), the refrigerant is used as a refrigerant of the second heat exchanger, and then compressed by a fourth compressor.
And controlling the flow rate of the evaporative gas circulating through the refrigerant cycle using the pressure value of the refrigerant circulating in the refrigerant cycle as a factor,
Wherein when the ship is in operation, the flow rate of the evaporative gas circulating in the refrigerant cycle is adjusted using the temperature value of the refrigerant circulating in the refrigerant cycle as a factor. 14. The method of claim 13,
Wherein the amount of the refrigerant circulated in the refrigerant cycle is controlled by controlling the flow rate of the fluid that is cooled by the second heat exchanger and then sent to the second pressure reducing device. The method according to claim 13 or 14,
Wherein the flow rate of the evaporative gas circulating in the refrigerant cycle is controlled by the pressure value of the fluid sent to the second heat exchanger after being depressurized by the second decompressor during the anchoring of the ship. 16. The method of claim 15,
The flow rate of the evaporative gas circulating in the refrigerant cycle is increased when the pressure of the fluid sent to the second heat exchanger after the pressure is reduced by the second pressure reducing device is higher than the first set value,
Wherein the flow rate of the evaporative gas circulating in the refrigerant cycle is reduced when the pressure of the fluid sent to the second heat exchanger after the pressure is reduced by the second pressure reducing device is lower than the first set value. The method according to claim 13 or 14,
Wherein a flow rate of the evaporative gas circulating in the refrigerant cycle is controlled by a temperature value of a fluid sent to the fourth compressor after being used as a refrigerant in the second heat exchanger during operation of the ship, . 18. The method of claim 17,
The flow rate of the evaporating gas circulating in the refrigerant cycle is increased when the temperature of the fluid sent to the fourth compressor after the refrigerant is used as the refrigerant in the second heat exchanger is higher than the second set value,
And a flow rate of the evaporative gas circulating in the refrigerant cycle is reduced when the temperature of the fluid sent to the fourth compressor after the refrigerant is used as the refrigerant in the second heat exchanger is lower than the second set value . A first compressor for compressing the evaporation gas;
A second compressor installed in parallel with the first compressor for compressing other flows of evaporative gas not sent to the first compressor;
A first heat exchanger that cools the evaporated gas compressed by the first compressor or the second compressor by using heat as the refrigerant before the refrigerant is compressed by the first compressor or the second compressor;
A second heat exchanger for further cooling the fluid cooled by the first heat exchanger by using the evaporation gas circulating the refrigerant cycle as a refrigerant for further heat exchange;
A first decompression device for decompressing the fluid cooled by the second heat exchanger; And
And a valve for controlling the flow rate of the refrigerant circulating in the refrigerant cycle,
When the temperature of the fluid used as the refrigerant in the second heat exchanger is higher than the second set value, the opening degree of the valve is increased, and when the temperature of the fluid used as the refrigerant in the second heat exchanger is lower than the second set value, A vapor liquefaction system for ships, which lowers the opening of the valve. The method of claim 19,
Wherein when the evaporation gas at the maximum flow rate is supplied to the refrigerant cycle, the opening degree of the valve is controlled by taking the pressure value of the refrigerant circulating through the refrigerant cycle as a factor.

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