KR20190013463A - Boil-Off Gas Reliquefaction System and Method of Discharging Lubrication Oil in the Same - Google Patents

Abstract

Disclosed is a method to discharge lubricant from a system which compresses boil-off gas (BOG) by a compressor, cools the BOG compressed by the compressor through heat exchange with low temperature BOG before compression by the compressor in a heat exchanger, and decompresses a fluid cooled through the heat exchange by a decompressor to reliquefy the BOG. In a lubricant discharge method, the compressor includes at least one lubricating type cylinder, the low temperature BOG to be used as refrigerant in the heat exchanger is supplied to the compressor through a bypass line installed to bypass the heat exchanger, and the BOG compressed by the compressor and having an increased temperature is supplied to a high temperature flow path of the heat exchanger, such that condensed or solidified lubricant is discharged after being melted or lowering the viscosity of the lubricant. A pipe installed between the heat exchanger and the decompressor comprises: a first horizontal part receiving the BOG discharged from the high temperature flow path of the heat exchanger and horizontally extended by a predetermined length; a first vertical part downwardly extended from one side of the first horizontal part by a predetermined length; a second horizontal part horizontally extended from the lower part of the first vertical part by a predetermined length; and a second vertical part upwardly extended from one side of the second horizontal part by a predetermined length and also downwardly extended by a predetermined length. The lubricant is collected at the lower part of the second vertical part and the BOG is supplied to the decompressor through the upper part of the second vertical part.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a boil-off gas re-liquefaction system and a boil-

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system and a method for re-liquefying boil-off gas (BOG) generated by spontaneous vaporization of a liquefied gas, The present invention relates to a system for re-liquefying a surplus evaporation gas remaining in an engine while using evaporation gas itself as a refrigerant.

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 consuming place.

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 . Particularly, the system adopting the latter method is called a Partial Re-liquefaction System (PRS).

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.

In this way, particularly when the evaporation gas (BOG) generated in the liquefied natural gas (LNG) storage tank is pressurized and the evaporation gas itself is used as the refrigerant without any additional refrigerant to mutually heat-exchange and re-liquefy the evaporation gas, It is necessary to compress the evaporation gas at a high pressure for compressing the evaporation gas to a high pressure.

Lubrication oil is mixed in the evaporated gas compressed by the cylinder compressor of the oil supply type. The inventors of the present invention have found that there is a problem that the lubricating oil mixed with the compressed evaporated gas condenses or coagulates before the evaporated gas while the compressed evaporated gas is cooled in the heat exchanger, thereby blocking the flow path of the heat exchanger. Particularly, in the case of PCHE (Printed Circuit Heat Exchanger, also referred to as DCHE) having a narrow flow path (for example, a microchannel type flow path), the phenomenon that the flow path of the heat exchanger is blocked by the condensed or solidified lubricant oil occurs more frequently do.

Accordingly, the inventors of the present invention are developing various techniques for separating the oil mixed in the compressed vaporized gas so as to prevent or mitigate the phenomenon that the condensed or solidified lubricant blocks the flow path of the heat exchanger.

The present invention relates to a system capable of mitigating or improving the phenomenon of condensed or solidified lubricating oil blocking the flow path of a heat exchanger and capable of removing condensed or solidified lubricant blocking the flow path of the heat exchanger in a simple and economical manner And methods.

Further, the present invention proposes a system and a method that can solve the problem that the lubricating oil is blocked or introduced into the storage tank while the lubricating oil is discharged by the bypass line.

According to an aspect of the present invention, there is provided an evaporator for compressing an evaporation gas by a compressor, cooling the evaporation gas compressed by the compressor by heat exchange in a heat exchanger with a low temperature evaporation gas before being compressed by the compressor A method of discharging a lubricating oil in a system for re-liquefying a vapor by reducing the pressure of a fluid cooled by heat exchange with a pressure reducing device, the compressor comprising at least one oil-feeding cylinder, Is supplied to the compressor through a bypass line provided to bypass the heat exchanger, and the evaporated gas, which is compressed by the compressor and has a high temperature, is supplied to the high-temperature channel of the heat exchanger to cool the condensed or solidified lubricant Dissolves or lowers the viscosity thereof, The piping installed between the decompression devices includes a first horizontal portion into which the evaporated gas discharged from the high-temperature flow path of the heat exchanger flows, and horizontally extending by a predetermined length; A first vertical part extending downward from the one side of the first horizontal part by a predetermined length; A second horizontal portion extending horizontally by a predetermined length from a lower portion of the first vertical portion; And a second vertical portion extending a predetermined length from one side of the second horizontal portion and extending a predetermined length downwardly so that the lubricating oil collects below the second vertical portion, 2 is supplied to the decompression device via the upper portion of the vertical portion.

During the liquefaction of the evaporated gas, the liquefied liquefied gas and the evaporated gas remaining in the gaseous state are separated by the gas-liquid separator, and the gaseous vaporized gas separated by the gas-liquid separator is discharged from the gas-liquid separator The lubricating oil may be collected by the gas-liquid separator. The lubricating oil may be collected by the compressor, melted by the evaporation gas whose temperature is increased, or lowered in viscosity.

The high-temperature flow path of the heat exchanger and the evaporation gas passing through the decompression device may be repeatedly sent to the bypass line, and then repeated by the compressor.

The temperature difference between the temperature of the evaporator gas used as the refrigerant in the heat exchanger at the front end of the heat exchanger and the evaporator gas cooled by the heat exchanger after being compressed by the compressor is hereinafter referred to as' ) Is equal to or greater than the first set value for a predetermined time or longer; The temperature difference between the temperature of the evaporation gas used as the refrigerant in the heat exchanger and the evaporation gas sent to the heat exchanger after being compressed by the compressor is hereinafter referred to as a " A condition in which the state lasts for a certain period of time; And a pressure difference between a pressure at a front end of the heat exchanger of the evaporation gas compressed by the compressor and then sent to the heat exchanger and a pressure difference at a rear end of the heat exchanger of the evaporation gas cooled by the heat exchanger Difference ") is equal to or greater than the second set value for a predetermined period of time or longer; , It can be judged that it is time to discharge condensed or solidified lubricating oil.

The temperature difference between the temperature of the evaporator gas used as the refrigerant in the heat exchanger at the front end of the heat exchanger and the evaporator gas cooled by the heat exchanger after being compressed by the compressor (hereinafter, ); And a temperature difference between the temperature of the evaporation gas used as the refrigerant in the heat exchanger and the evaporation gas sent to the heat exchanger after being compressed by the compressor (hereinafter, referred to as 'temperature difference of the high temperature flow'); The pressure of the evaporator gas at the front end of the heat exchanger that is sent to the heat exchanger after being compressed by the compressor and the pressure of the evaporator gas cooled by the heat exchanger If the state in which the pressure difference at the rear end of the heat exchanger (hereinafter, referred to as "pressure difference of the high-temperature flow path") is equal to or more than the second set value continues for a predetermined time or more, it is determined that the time point is "to discharge condensed or solidified lubricating oil" .

According to another aspect of the present invention, there is provided a compressor for compressing an evaporative gas, A heat exchanger that uses a low-temperature evaporation gas before being compressed by the compressor as a refrigerant to cool the evaporation gas compressed by the compressor by heat exchange; And a decompression device for decompressing the fluid cooled by the heat exchanger, wherein a piping installed between the heat exchanger and the decompression device receives the evaporation gas discharged from the high-temperature flow path of the heat exchanger, A first horizontal portion extending from the first horizontal portion; A first vertical part extending downward from the one side of the first horizontal part by a predetermined length; A second horizontal portion extending horizontally by a predetermined length from a lower portion of the first vertical portion; And a second vertical portion extending a predetermined length from one side of the second horizontal portion and extending a predetermined length downwardly so that the lubricating oil collects below the second vertical portion, 2 < / RTI > vertical portion of the evaporator.

The evaporation gas re-liquefaction system may further include a lubricant discharge valve connected to the lower end of the second vertical portion.

The lubricating oil discharge valve may be a DDB valve.

A third horizontal part connected to the upper part of the second vertical part at one side and horizontally extending a predetermined length from the upper part of the second collecting part, the pipeline installed between the heat exchanger and the decompression device; And a third vertical part extending upward from the other side of the third horizontal part, and the evaporation gas sent to the third horizontal part through the upper part of the second vertical part may be separated from the third horizontal part and the third horizontal part, 3 vertical portion and can be supplied to the decompressor.

The evaporation gas re-liquefaction system includes a second pressure sensor installed downstream of the high-temperature flow path of the heat exchanger and measuring the pressure of the evaporation gas cooled by the heat exchanger after being compressed by the compressor; Or a differential pressure sensor for measuring the pressure difference between upstream and downstream of the high-temperature flow path of the heat exchanger, and the second pressure sensor or the differential pressure sensor may be installed on the third horizontal portion.

The evaporation gas re-liquefaction system may further comprise a lubricant collecting means provided below the lubricant discharge valve for collecting lubricant discharged by the lubricant discharge valve.

The second horizontal portion may extend in a direction opposite to the first horizontal portion.

The third horizontal portion may extend in the same direction as the second horizontal portion or may extend in a direction opposite to the first horizontal portion.

The first horizontal portion and the second horizontal portion may be inclined so that lubricant can flow along the bottom surface.

The second horizontal portion may be shorter than the first horizontal portion.

According to the present invention, it is possible to simply and economically remove the condensed or solidified lubricating oil in the heat exchanger by using only the existing equipment, without installing additional equipment or supplying a separate fluid for removing the lubricating oil.

According to the present invention, the engine can be driven while the internal condensed or solidified lubricating oil is removed, and the heat exchanger can be maintained while continuing the operation of the engine. In addition, it is possible to remove the condensed or solidified lubricating oil by utilizing the surplus evaporative gas remaining in the engine. In addition, there is an advantage that the lubricating oil mixed with the evaporation gas can be burned by the engine.

According to the present invention, there is an advantage that the improved gas-liquid separator can efficiently discharge the lubricating oil collected in the gas-liquid separator and having reduced melting or viscosity.

According to the present invention, the cryogenic oil filter is installed in at least one of the downstream end of the pressure reducing device, the fifth supply line through which the liquefied gas is discharged from the gas-liquid separator, and the sixth supply line through which the evaporation gas is discharged from the gas- It has the advantage of being able to effectively remove mixed lubricating oil.

According to the present invention, it is possible to maintain the liquefaction performance while satisfying the intake pressure conditions required by the compressor simply and economically, without using any additional equipment, and to satisfy the fuel consumption required by the engine .

According to the present invention, while discharging the condensed or solidified lubricating oil by the bypass line, the lubricating oil can be effectively collected in the second vertical portion and then discharged by the lubricating oil discharge valve.

Further, according to the present invention, the lubricant can be efficiently collected at the lower portion of the second vertical portion only by improving the shape of the piping, so that the lubricant can be prevented from clogging the decompression device while discharging the lubricant by the bypass line The problem of flowing into the storage tank can be solved.

1 is a schematic view of a vaporization gas remelting system according to a first preferred embodiment of the present invention.
2 is a schematic diagram of a vaporization gas remelting system according to a second preferred embodiment of the present invention.
Fig. 3 schematically shows the shape of a piping installed between the heat exchanger and the decompression apparatus in the evaporation gas remelting system shown in Figs. 1 and 2. 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 evaporation gas re-liquefaction system of 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.

Figs. 1 and 2 are for showing the connection of each device and the flow of fluid, and do not directly reflect the actual installation position of each device or the shape of the pipe.

In the present specification, the term 'vertical' is interpreted as being limited to 90 ° with respect to the ground, or 'horizontally' should not be construed as limited to dm only when the horizontal is 0 ° with the ground, , The general meaning of the left and right front and back direction should be interpreted as 'horizontal'.

1 is a schematic view of a vaporization gas remelting system according to a first preferred embodiment of the present invention.

1, the evaporation gas remelting system of the present embodiment includes a heat exchanger 100, a first valve 510, a second valve 520, a first temperature sensor 810, a second temperature sensor 820 The compressor 200, the third temperature sensor 830, the fourth temperature sensor 840, the first pressure sensor 910, the second pressure sensor 920, the pressure reducing device 600, the bypass line BL, And a bypass valve 590.

The heat exchanger 100 cools the evaporation gas compressed by the compressor 200 by using the evaporation gas discharged from the storage tank T as a refrigerant. The evaporated gas used as the refrigerant in the heat exchanger 100 after being discharged from the storage tank T is sent to the compressor 200 and the evaporated gas compressed by the compressor 200 is discharged from the storage tank T And is cooled by the heat exchanger 100 using the evaporation gas as a refrigerant.

The evaporated gas discharged from the storage tank T is sent to the heat exchanger 100 along with the first supply line L1 to be used as a refrigerant and the evaporated gas used as the refrigerant in the heat exchanger 100 is supplied to the second supply line L2 To the compressor (200). Some or all of the evaporated gas compressed by the compressor 200 is sent to the heat exchanger 100 along the third supply line L3 to be cooled and the fluid cooled in the heat exchanger 100 flows through the fourth supply line L4 To the decompressor 600.

The first valve 510 is installed on the first supply line L1 to regulate the flow rate and opening and closing of the fluid and the second valve 520 is installed on the second supply line L2 to control the flow rate of the fluid, .

The first temperature sensor 810 is installed on the upstream side of the heat exchanger 100 on the first supply line L 1 and measures the temperature of the evaporated gas discharged from the storage tank T and supplied to the heat exchanger 100. The first temperature sensor 810 is preferably installed immediately before the heat exchanger 100 so that the temperature of the evaporated gas immediately before being supplied to the heat exchanger 100 can be measured.

In the present invention, the front end includes the meaning of the upstream, and the rear end includes the meaning of the downstream.

The second temperature sensor 820 is installed at the rear end of the heat exchanger 100 on the second supply line L2 and detects the temperature of the evaporation gas used as the refrigerant in the heat exchanger 100 after being discharged from the storage tank T . The second temperature sensor 820 is preferably installed immediately after the heat exchanger 100 so that the temperature of the evaporated gas immediately after being used as the refrigerant in the heat exchanger 100 can be measured.

The compressor 200 compresses the evaporated gas used as the refrigerant in the heat exchanger 100 after being discharged from the storage tank T. The evaporated gas compressed by the compressor 200 can be supplied to the fuel of the high-pressure engine, and the surplus evaporated gas remaining after being supplied to the fuel of the high-pressure engine can be sent to the heat exchanger 100 to undergo a liquefaction process.

A sixth valve 560 may be provided on the fuel supply line SL for sending the evaporated gas compressed by the compressor 200 to the high-pressure engine, for controlling the flow rate and opening / closing of the fluid.

The sixth valve 560 serves as a safety device for completely shutting off supply of the evaporative gas sent to the high-pressure engine when the gas mode operation of the high-pressure engine is stopped. The gas mode means a mode in which the engine is operated using natural gas as the fuel. When the evaporation gas to be used as the fuel is insufficient, the engine is switched to the fuel oil mode, and the fuel oil is used as the fuel for the engine.

A seventh valve 570 for controlling the flow rate of the fluid and the opening and closing of the fluid is disposed on the line for sending the surplus evaporated gas remaining after being supplied to the fuel of the high pressure engine among the evaporated gases compressed by the compressor 200 to the heat exchanger 100. [ Can be installed.

When the evaporated gas compressed by the compressor 200 is sent to the high-pressure engine, the compressor 200 can compress the evaporated gas to a pressure required by the high-pressure engine. The high-pressure engine may be an ME-GI engine using high-pressure evaporation gas as fuel.

The ME-GI engine is known to use about 150 to 400 bar, preferably about 150 to 350 bar, more preferably about 300 bar of natural gas as fuel. The compressor 200 of the present invention can compress the evaporation gas to approximately 150 to 350 bar so as to supply the compressed evaporated gas to the ME-GI engine.

In the present invention, instead of the ME-GI engine as the main engine, an X-DF engine or a DF engine using a vapor of about 6 to 20 bar pressure as the fuel may be used. In this case, Since the evaporation gas is at a low pressure, it is possible to re-liquefy by further pressurizing the compressed evaporation gas to be supplied to the main engine. The pressure of the further pressurized evaporation gas for re-liquefaction can be approximately 80 to 250 bar.

The compressor 200 includes a plurality of cylinders 210, 220, 230, 240 and 250 and a plurality of coolers 211, 221, 231, and 231 installed at the downstream ends of the plurality of cylinders 210, 220, 230, 241, 251). The coolers 211, 221, 231, 241 and 251 are compressed by the cylinders 210, 220, 230, 240 and 250 and cools the evaporated gas not only in pressure but also in temperature.

In the case where the compressor 200 includes a plurality of cylinders 210, 220, 230, 240 and 250, the evaporated gas supplied to the compressor 200 is compressed by the plurality of cylinders 210, 220, 230, 240 and 250 It is compressed in multiple stages. Each cylinder 210, 220, 230, 240, 250 has the meaning of each compression stage of the compressor 200.

The compressor 200 further includes a first recirculation line RC1 for sending part or all of the evaporated gas that has passed through the first cylinder 210 and the first cooler 211 to the upstream side of the first cylinder 210; A second recirculation line RC2 for sending part or all of the evaporated gas that has passed through the second cylinder 220 and the second cooler 221 to the front end of the second cylinder 220; A third recirculation line RC3 for sending part or all of the evaporated gas that has passed through the third cylinder 230 and the third cooler 231 to the front end of the third cylinder 230; And a fourth recirculation valve 242 for sending some or all of the evaporated gas that has passed through the fourth cylinder 240, the fourth cooler 241, the fifth cylinder 250 and the fifth cooler 251 to the front end of the fourth cylinder 240 Line RC4.

A first recirculation valve 541 for regulating the flow rate and opening and closing of the fluid is provided on the first recirculation line RC1 and a second recirculation valve 541 for regulating the flow rate and opening and closing of the fluid is provided on the second recirculation line RC2. A third recirculation valve 543 for regulating the flow rate and opening and closing of the fluid is provided on the third recirculation line RC3 and a third recirculation valve 543 for regulating the flow rate and opening and closing of the fluid is disposed on the fourth recirculation line RC4. 4 recirculation valve 544 may be provided.

The recirculation lines RC1, RC2, RC3 and RC4 recirculate some or all of the evaporated gas to the compressor 200 when the pressure inside the storage tank T is low and the suction pressure conditions required by the compressor 200 are not satisfied. ). When the recirculation lines RC1, RC2, RC3 and RC4 are not used, the recirculation valves 541, 542, 543 and 544 are closed and the recirculation lines RC1 and RC2 , RC3, RC4), the recirculation valves 541, 542, 543, 544 are opened.

1 shows a case where the evaporation gas is completely sent to the heat exchanger 100 through the plurality of cylinders 210, 220, 230, 240 and 250 included in the compressor 200, The evaporated gas passing through some of the cylinders 210, 220, 230, 240, 250 may be branched at the middle of the compressor 200 and sent to the heat exchanger 100.

Further, the evaporated gas passing through a part of the plurality of cylinders 210, 220, 230, 240 and 250 may be branched from the middle of the compressor 200 to be sent to the low-pressure engine for use as fuel, GCU (Gas Combustion Unit).

The low pressure engine may be a DF engine (e.g., DFDE) using a vapor of about 6 to 10 bar pressure as the fuel.

The plurality of cylinders 210, 220, 230, 240, and 250 included in the compressor 200 may operate in an oil-free lubricated manner and others may operate in an oil lubricated manner. have. Particularly, when the evaporation gas compressed by the compressor 200 is used as the fuel of the high-pressure engine, or when the evaporation gas is compressed to 80 bar or more, preferably 100 bar or more, for the liquefaction efficiency, A cylinder of a refueling type is included to compress the evaporation gas to a high pressure.

With existing technology, lubricating oil for lubrication and cooling must be supplied to the reciprocating compressor 200, for example, at the piston sealing area in order to compress the evaporation gas to 100 bar or more.

Lubricating oil is supplied to cylinders of refueled lubrication type. At the current technology level, some of lubricating oil is mixed in the evaporated gas that passes through the cylinder of refueling type. The inventors of the present invention have found that the lubricating oil compressed by the evaporation gas and mixed with the evaporation gas is condensed or solidified before the evaporation gas in the heat exchanger 100 to block the flow path of the heat exchanger 100.

The evaporation gas re-liquefaction system of the present embodiment may further include an oil separator 300 and a first oil filter 410 installed between the compressor 200 and the heat exchanger 100 to separate the oil mixed with the evaporation gas have.

The oil separator 300 separates mainly the lubricating oil in the liquid state, and the first oil filter 410 separates the lubricating oil in the vapor or mist state. Since the oil separator 300 separates the lubricant oil having a larger particle size than the first oil filter 410, the oil separator 300 is installed at the front end of the first oil filter 410, It is preferable that the gas is sequentially passed through the oil separator 300 and the first oil filter 410 and then sent to the heat exchanger 100.

1 shows the case where the oil separator 300 and the first oil filter 410 are both included in the oil separator 300 and the first oil filter 410. However, It may include only one. However, it is preferable to use both the oil separator 300 and the first oil filter 410.

1 shows a case where the first oil filter 410 is installed on the second supply line L2 at the rear stage of the compressor 200. The first oil filter 410 is disposed in front of the heat exchanger 100 The third supply line L3, and a plurality of the supply lines L3 may be provided in parallel.

The evaporation gas re-liquefaction system of this embodiment includes at least one of the oil separator 300 and the first oil filter 410, and the compressor 200 of this embodiment includes the cylinder of the non-lube oiling system and the cylinder of the oil- The evaporated gas that has passed through the cylinder of the refueling lubrication system is configured to be sent to the oil separator 300 and / or the first oil filter 410, and the evaporation gas that has passed through only the cylinder of the non-lube lubrication system is supplied to the oil separator 300 Or may be configured to be sent directly to the heat exchanger 100 without passing through the oil filter 410.

For example, the compressor 200 of the present embodiment includes five cylinders 210, 220, 230, 240 and 250, the front three cylinders 210, 220 and 230 are non-lubrication lubricating systems and the two cylinders 240 , 250 may be an oil supply lubricating system. When the evaporation gas is branched in the third or lower stage, the evaporation gas is directly sent to the heat exchanger 100 without passing through the oil separator 300 or the first oil filter 410 When the boil-off gas is branched at four or more stages, the boil-off gas may be sent to the first heat exchanger 100 after passing through the oil separator 300 and / or the first oil filter 410.

The first oil filter 410 may be a coalescer type oil filter.

A check valve 550 may be provided on the fuel supply line SL between the compressor 200 and the high-pressure engine. The check valve 550 serves to prevent the evaporation gas from flowing backward and damaging the compressor when the high-pressure engine stops.

When the evaporation gas re-liquefaction system of this embodiment includes the oil separator 300 and / or the first oil filter 410, the backflowed evaporation gas is supplied to the oil separator 300 and / or the first oil filter 410 The backflow prevention valve 550 may be installed downstream of the oil separator 300 and / or the first oil filter 410 so as not to flow.

The backflow prevention valve 550 prevents the third supply line L3 from flowing into the fuel supply line SL (SL) when the expansion valve 600 is suddenly closed, ) At the branch point.

The third temperature sensor 830 is provided on the third supply line L3 before the heat exchanger 100 to measure the temperature of the evaporated gas that is compressed by the compressor 200 and then sent to the heat exchanger 100 do. The third temperature sensor 830 is preferably installed immediately before the heat exchanger 100 so that the temperature of the evaporated gas immediately before being supplied to the heat exchanger 100 can be measured.

The fourth temperature sensor 840 is disposed downstream of the heat exchanger 100 on the fourth supply line L4 and detects the temperature of the evaporated gas cooled by the heat exchanger 100 after being compressed by the compressor 200 . The fourth temperature sensor 840 is preferably disposed immediately after the heat exchanger 100 so that the temperature of the evaporated gas immediately after being cooled by the heat exchanger 100 can be measured.

The first pressure sensor 910 is installed on the third supply line L3 in front of the heat exchanger 100 and measures the pressure of the evaporated gas that is compressed by the compressor 200 and then sent to the heat exchanger 100 do. The first pressure sensor 910 is preferably installed immediately upstream of the heat exchanger 100 so that the pressure of the evaporated gas immediately before being supplied to the heat exchanger 100 can be measured.

The second pressure sensor 920 is disposed downstream of the heat exchanger 100 on the fourth supply line L4 so that the pressure of the evaporated gas cooled by the heat exchanger 100 after being compressed by the compressor 200 . The second pressure sensor 920 is preferably installed immediately after the heat exchanger 100 so that the pressure of the evaporated gas immediately after being cooled by the heat exchanger 100 can be measured.

It is preferable that all of the first to fourth temperature sensors 810 to 840, the first pressure sensor 910 and the second pressure sensor 920 are installed as shown in FIG. 1, Only a first temperature sensor 810 and a fourth temperature sensor 840 (hereinafter referred to as a "first pair") are provided, or the second temperature sensor 820 and the third temperature sensor 840 Only a first pressure sensor 910 and a second pressure sensor 920 (hereinafter referred to as a "third pair") may be provided, or only a first pressure sensor 830 (hereinafter referred to as a "second pair" Only two of the first through third pairs may be installed.

The decompressor 600 is disposed downstream of the heat exchanger 100 to compress the evaporated gas cooled by the heat exchanger 100 after being compressed by the compressor 200. The evaporation gas that has undergone the compression process by the compressor 200, the cooling process by the heat exchanger 100, and the decompression process by the decompressor 600 may partially or totally re-liquefy. The pressure reducing device 600 may be an expansion valve such as a line-Thomson valve or an expansion valve, depending on the configuration of the system.

The evaporation gas re-liquefaction system of this embodiment comprises a liquefied natural gas which is disposed at the downstream end of the decompressor 600 and passes through the compressor 200, the heat exchanger 100, and the decompressor 600, And a gas-liquid separator 700 for separating the remaining evaporation gas.

The liquefied gas separated by the gas-liquid separator 700 is sent to the storage tank T along the fifth supply line L5 and the evaporated gas separated by the gas-liquid separator 700 is supplied to the sixth supply line L6 May be combined with the evaporated gas discharged from the storage tank (T) and then sent to the heat exchanger (100).

1 shows that the evaporated gas separated by the gas-liquid separator 700 is combined with the evaporated gas discharged from the storage tank T and then sent to the heat exchanger 100. However, the present invention is not limited thereto, Liquid separator 700 may be used as a refrigerant in the heat exchanger 100 along a separate flow path.

It is also possible to send the fluid, which does not include the gas-liquid separator 700, but is partially or totally re-liquefied by the pressure-reducing device 600, directly to the storage tank T.

An eighth valve 581 for opening and closing the flow rate of the fluid may be provided on the fifth supply line L5. The level of the liquefied gas in the gas-liquid separator 700 is adjusted by the eighth valve 581.

A ninth valve 582 may be provided on the sixth supply line L6 to control the flow rate and opening / closing of the fluid. The pressure inside the gas-liquid separator 700 is adjusted by the ninth valve 582.

The evaporation gas re-liquefaction system of the present embodiment is provided with a second oil filter 420 installed between the carburane 600 and the gas-liquid separator 700 to filter the oil mixed with the fluid reduced in pressure by the pressure- .

The first oil filter 410 is installed at the rear end of the compressor 200 and the evaporated gas compressed by the compressor 200 is approximately 40 to 45 ° C so that it is not necessary to use the oil filter for cryogenic temperature. However, the temperature of the fluid depressurized by the decompressor 600 becomes about -160 to -150 DEG C so that at least a part of the evaporated gas can be re-liquefied, and the liquefied gas separated by the gas-liquid separator 700 and the evaporated gas The temperature of the second oil filter 420 is about -160 to -150 DEG C, so that the second oil filter 420 should be designed for a cryogenic temperature.

Further, since the lubricating oil mixed in the evaporation gas at approximately 40 to 45 DEG C compressed by the compressor 200 is mostly in the liquid state or the mist state, the oil separator 300 is suitable for separating the lubricating oil in the liquid state And the first oil filter 410 is designed to be suitable for separating the lubricating oil in the mist state (part of the lubricating oil in the vapor state may be partly included).

On the other hand, the fluid, which is the cryogenic fluid, reduced in pressure by the pressure reducing device 600, the evaporated gas separated by the gas-liquid separator 700, and the lubricant mixed in the liquefied gas separated by the gas- (Or solidified) state of the second oil filter 420, the second oil filter 420 is designed to be suitable for separating the solid (or solidified) lubricating oil.

The bypass line BL of the present invention is branched from the first supply line L1 at the upstream end of the heat exchanger 100 and bypasses the heat exchanger 100 and then bypasses the second To the supply line L2.

Typically, the bypass line bypassing the heat exchanger is installed inside the heat exchanger and integrated with the heat exchanger. When the bypass line is installed inside the heat exchanger, when the valve installed at the front end and / or the rear end of the heat exchanger is closed, the fluid is not supplied to the heat exchanger and the fluid is not supplied to the bypass line.

However, in the present invention, the bypass line BL is installed outside the heat exchanger 100 separately from the heat exchanger 100, and the first valve 510 and / or the heat exchanger 100 The bypass line BL is branched from the first supply line L1 at the front end of the first valve 510 so that the evaporation gas can be supplied to the bypass line BL even when the second valve 520 installed at the rear end of the first valve 510 is closed. And to the second supply line (L2) at the rear end of the second valve (520).

A bypass valve 590 is provided on the bypass line BL and is opened when the bypass valve 590 is normally closed and the bypass line BL needs to be used.

According to the present invention, the bypass line (BL) is used when the heat exchanger (100) can not be used, such as when the heat exchanger (100) fails or maintenance is required. However, according to the present invention, the bypass line BL is used for removing lubricant accumulated in the system, which is condensed or solidified, unlike the prior art.

A predetermined lubricating oil is mixed in the evaporation gas passing through the cylinder of the oil supply and lubricating system of the compressor 200 and the lubricating oil mixed with the evaporation gas is condensed or solidified before the evaporation gas in the heat exchanger 100, The amount of condensed or solidified lubricating oil accumulated in the flow path of the heat exchanger 100 increases as time elapses so that the condensed or solidified lubricating oil inside the heat exchanger 100 The inventors of the present invention have found that there is a need to remove them.

Particularly, it is preferable that the heat exchanger 100 of the present embodiment is a PCHE (Printed Circuit Heat Exchanger, also referred to as DCHE) in consideration of the pressure and / or flow rate of the evaporation gas to be re-liquefied, (A microchannel-like flow path) is bent, and the flow path can be easily clogged by the condensed or solidified lubricating oil. In particular, the lubricating oil condensed or solidified in the bent portion of the flow path is well piled. PCHE (DCHE) is produced by companies such as Kobelko and Alfalaval.

The condensed or solidified lubricating oil can be removed by the following steps.

1) determining whether to remove the condensed or solidified lubricating oil

2) opening the bypass valve 590 and closing the first valve 510 and the second valve 520

3) the evaporated gas discharged from the storage tank T is compressed by the compressor 200 through the bypass line BL

4) sending some or all of the high temperature evaporated gas compressed by the compressor 200 to the heat exchanger 100

5) sending the evaporated gas that has passed through the heat exchanger 100 to the gas-liquid separator 700

6) discharging the lubricating oil collected in the gas-liquid separator 700

7) confirming that the heat exchanger 100 has been normalized

In the present invention, each step of removing the condensed or solidified lubricating oil by utilizing the bypass line (BL) will be described in detail as follows.

1) Condensate or solidified lubricant Whether to remove  Step to judge

If the flow path of the heat exchanger 100 is clogged by the condensed or solidified lubricating oil, the cooling efficiency of the heat exchanger 100 is lowered. Therefore, if the performance of the heat exchanger 100 is lower than a predetermined value, it can be estimated that the condensed or solidified lubricating oil is accumulated to some extent in the heat exchanger 100. For example, It can be determined that the lubricating oil condensed or solidified in the heat exchanger 100 should be removed if the performance falls below 70% of that in the normal case.

When the performance of the heat exchanger 100 is lowered, the temperature difference between the low-temperature evaporation gas L1 supplied to the heat exchanger 100 and the low-temperature evaporation gas L4 discharged from the heat exchanger 100 increases, The temperature difference between the high-temperature evaporating gas L2 discharged from the heat exchanger 100 and the high-temperature evaporating gas L3 supplied to the heat exchanger 100 becomes large. When the flow path of the heat exchanger 100 is clogged by the condensed or solidified lubricating oil, the flow path of the heat exchanger 100 is narrowed, so that the pressure difference between the front end L3 and the rear end L4 of the heat exchanger 100 increases .

The temperature differences 810 and 840 of the low temperature fluids supplied to the heat exchanger 100 or discharged from the heat exchanger 100 and the temperature differences 820 and 840 of the high temperature fluid supplied to the heat exchanger 100 or discharged from the heat exchanger 100 , 830), pressure differences (910, 920) applied to the high-temperature flow path of the heat exchanger (100), and the like.

The low-temperature channel of the heat exchanger 100 means a channel through which low-temperature evaporation gas used as a coolant flows in the heat exchanger 100. The high-temperature channel is a channel through which a high-temperature evaporation gas cooled by the heat exchanger 100 flows it means.

More specifically, the temperature of the evaporated gas discharged from the storage tank T measured by the first temperature sensor 810 and sent to the heat exchanger 100 is compared with the temperature of the refrigerant discharged from the compressor 200 measured by the fourth temperature sensor 840 (Hereinafter referred to as "temperature difference of the low temperature flow") of the evaporation gas cooled by the heat exchanger 100 after being compressed by the heat exchanger 100 is larger than that in the normal case, The heat exchanger 100 can judge that the heat exchange is not properly performed.

For example, if the state in which the temperature difference of the low-temperature flow is 20 to 50 ° C or more, preferably 30 to 40 ° C or more, more preferably approximately 35 ° C or more is maintained for 1 hour or more, It can be judged that it is time to discharge.

When the heat exchanger 100 is operating normally, the evaporated gas compressed by the compressor 200 to approximately 300 bar is approximately 40 to 45 ° C, and the evaporator gas discharged from the storage tank T is approximately -160 to -140 ° C The temperature of the evaporation gas may increase somewhat during the transfer to the heat exchanger 100, and may be about -150 to -110 캜, preferably about -120 캜.

The evaporation gas remelting system of this embodiment includes the gas-liquid separator 700 so that the gaseous vaporized gas separated by the gas-liquid separator 700 is combined with the vaporized gas discharged from the storage tank T, The temperature of the evaporative gas supplied to the heat exchanger 100 is lower than that of only the evaporated gas discharged from the storage tank T to the heat exchanger 100, The greater the amount of the separated gaseous vaporized gas, the lower the temperature of the vaporized gas supplied to the heat exchanger 100.

The evaporation gas at approximately 40 to 45 캜 supplied to the heat exchanger 100 along the third supply line L 3 is cooled by the heat exchanger 100 to approximately -130 to -110 캜, Temperature difference of the low-temperature flow " is preferably about 2 to 3 占 폚.

The temperature of the evaporation gas used as the refrigerant in the heat exchanger 100 after discharged from the storage tank T measured by the second temperature sensor 820 and the temperature of the refrigerant discharged from the compressor 200 measured by the third temperature sensor 830 (Hereinafter referred to as "temperature difference of high temperature flow") of the evaporation gas compressed by the heat exchanger 100 and then sent to the heat exchanger 100 is larger than that in the normal case, The heat exchanger 100 can judge that the heat exchange is not properly performed.

If the state in which the 'temperature difference of the high temperature flow' is 20 to 50 ° C or more, preferably 30 to 40 ° C or more, more preferably approximately 35 ° C or more is maintained for 1 hour or more, the condensed or solidified lubricant should be discharged It can be judged as a time point.

When the heat exchanger 100 is operating normally, it is cooled to a temperature of about -150 to -110 DEG C (preferably about -120 DEG C), which is somewhat increased during discharge to the heat exchanger 100 after being discharged from the storage tank T. The evaporation gas may be approximately -80 to 40 占 폚, depending on the speed of the vessel after being used as a refrigerant in the heat exchanger 100, and may be a vapor of approximately -80 to 40 占 폚 used as a refrigerant in the heat exchanger 100 Lt; RTI ID = 0.0 > 45 C < / RTI >

The pressure of the evaporation gas sent to the heat exchanger 100 after being compressed by the compressor 200 measured by the first pressure sensor 910 and the pressure of the evaporation gas sent to the heat exchanger 100 (Hereinafter, referred to as a "pressure difference of the high-temperature flow path") which is cooled by the heat exchanger 100 .

Since the evaporation gas discharged from the storage tank T is not mixed with oil or is present at a very low level and the lubricating oil is mixed at the time when the evaporation gas is compressed by the compressor 200, The condensed or solidified lubricating oil is hardly accumulated in the low-temperature flow path of the heat exchanger 100 which uses the evaporated gas discharged from the compressor 200 as a refrigerant and then sends the refrigerant to the compressor 200. After cooling the evaporated gas compressed by the compressor 200 The condensed or solidified lubricating oil is accumulated in the high-temperature flow path of the heat exchanger 100 to be sent to the decompression apparatus 600.

Therefore, the phenomenon that the flow path is clogged by the condensed or coagulated lubricant oil and the pressure difference between the front and rear ends of the heat exchanger 100 becomes large rapidly progresses in the high temperature flow path. Therefore, the pressure applied to the high temperature flow path of the heat exchanger 100 is measured, Whether or not the lubricant should be removed.

Whether or not condensed or solidified lubricating oil should be removed is determined by the pressure difference between the front and rear ends of the heat exchanger 100, in particular, the PCHE in which the flow path is formed narrow and curved to the heat exchanger 100 of this embodiment can be applied , It can be usefully used.

For example, it can be judged that it is time to discharge the condensed or solidified lubricating oil when the pressure difference of the high-temperature flow path is twice or more than the normal case and the state is maintained for 1 hour or more.

When the heat exchanger 100 operates normally, the evaporated gas compressed by the compressor 200 passes through the heat exchanger 100 and is cooled to a pressure of about 0.5 to 2.5 bar, A pressure drop of about 1.5 bar, more preferably about 1 bar, occurs. If the state in which the pressure difference of the high-temperature flow path is at least a predetermined pressure, for example, 1 to 5 bar or more, preferably 1.5 to 3 bar or more, more preferably approximately 2 bar (200 kPa) Or that it is time to discharge the solidified lubricating oil.

As described above, it is possible to judge whether or not to remove the condensed or solidified lubricating oil by using any one of the "temperature difference of the low temperature flow", "the temperature difference of the high temperature flow", and " However, in order to increase the reliability, it is judged whether or not to remove the condensed or solidified lubricant by using at least two of "temperature difference of low temperature flow", "temperature difference of high temperature flow", and "pressure difference of high temperature flow path" .

For example, the difference between the temperature difference of the low-temperature flow and the temperature difference of the high-temperature flow may be at least two times longer than the normal case, kPa or more for 1 hour or more, it can be judged that it is time to remove condensed or solidified lubricating oil.

The first temperature sensor 810, the second temperature sensor 820, the third temperature sensor 830, the fourth temperature sensor 840, the first pressure sensor 910, and the second pressure sensor 920, It can be regarded as a kind of sensing means for sensing whether or not the heat exchanger 100 is clogged with lubricating oil.

The evaporation gas re-liquefaction system of the present invention includes a first temperature sensor 810, a second temperature sensor 820, a third temperature sensor 830, a fourth temperature sensor 840, a first pressure sensor 910 (Not shown) for determining whether the heat exchanger 100 is clogged with lubricating oil by a value sensed by at least one of the first pressure sensor 920 and the second pressure sensor 920. The control device can be regarded as a kind of judging means for judging whether or not the heat exchanger 100 is clogged by the lubricating oil.

2) opening the bypass valve 590 and closing the first valve 510 and the second valve 520

A bypass valve 590 provided on the bypass line BL is operated to determine whether or not to remove the condensed or solidified lubricating oil in the first step and to remove the condensed or solidified lubricating oil in the heat exchanger 100, And the first valve 510 provided on the first supply line L1 and the second valve 520 provided on the second supply line L2 are closed.

When the bypass valve 590 opens and closes the first valve 510 and the second valve 520, the evaporated gas discharged from the storage tank T is sent to the compressor 200 through the bypass line BL, It is not sent to the machine 100. Therefore, the refrigerant is not supplied to the heat exchanger 100.

3) The evaporated gas discharged from the storage tank (T) Bypass line (BL)  And then compressed by the compressor (200)

The evaporated gas discharged from the storage tank T bypasses the heat exchanger 100 through the bypass line BL and is then sent to the compressor 200. The evaporated gas sent to the compressor 200 is compressed by the compressor 200 and the temperature is increased as well as the pressure. The temperature of the evaporated gas compressed by the compressor 200 to about 300 bar is about 40 to 45 ° C.

4) sending some or all of the high temperature evaporated gas compressed by the compressor 200 to the heat exchanger 100

When the evaporated gas having a high temperature compressed by the compressor 200 is continuously sent to the heat exchanger 100, the low-temperature evaporated gas discharged from the storage tank T used as the refrigerant in the heat exchanger 100 passes through the heat exchanger 100 And the temperature of the high-temperature flow path of the heat exchanger 100 through which the evaporated gas compressed by the compressor 200 passes gradually increases because only the high-temperature evaporated gas is supplied to the heat exchanger 100 continuously.

When the temperature of the high-temperature flow path of the heat exchanger 100 becomes equal to or higher than the temperature at which the lubricating oil is condensed or solidified, the condensed or solidified lubricating oil accumulated in the heat exchanger 100 gradually melts or becomes low in viscosity, The lubricating oil mixes with the evaporating gas and exits the heat exchanger 100.

When the condensed or solidified lubricating oil is removed using the bypass line BL, the evaporation gas is supplied to the bypass line BL, the compressor 200, and the high-temperature flow path of the heat exchanger 100 until the heat exchanger 100 is normalized. The decompression apparatus 600, and the gas-liquid separator 700, as shown in FIG.

5) The evaporation gas passing through the heat exchanger 100 Liquid separator 700  Sending step

As the temperature of the high-temperature flow path of the heat exchanger 100 increases, the condensed or solidified lubricating oil accumulated in the heat exchanger 100 melts or becomes viscous and mixed with the evaporated gas and sent to the gas-liquid separator 700. In the process of removing the condensed or solidified lubricating oil in the heat exchanger 100 by utilizing the bypass line BL, the re-liquefaction of the evaporated gas is not performed. Therefore, the liquefied liquefied gas is not collected in the gas-liquid separator 700, The evaporated gas in the state and the lubricating oil which melts or lowers in viscosity are gathered.

The vaporized gaseous state collected in the gas-liquid separator 700 is discharged from the gas-liquid separator 700 along the sixth supply line L6 and then sent to the compressor 200 along the bypass line BL. Since the first valve 510 is closed in the second stage, the gaseous vaporized gas separated by the gas-liquid separator 700 is merged with the vaporized gas discharged from the storage tank T and flows along the bypass line BL, Is not supplied to the low-temperature flow path of the heat exchanger (100).

The supply of the gaseous vaporized gas separated by the gas-liquid separator 700 to the bypass line BL in a state where the first valve 510 is closed can be performed by supplying the lubricating oil partially contained in the vaporized gas to the heat exchanger 100 To prevent the low-temperature flow path of the heat exchanger 100 from being clogged.

Liquid separator 700 is discharged from the gas-liquid separator 700 along the sixth supply line L6 and then sent to the compressor 200 along the bypass line BL, the circulation process of the gas- The temperature of the high-temperature flow path of the apparatus 100 is compressed by the compressor 200 and then it is judged that the temperature of the high-temperature flow path of the apparatus 100 is increased by the temperature of the evaporation gas sent to the high-temperature flow path of the heat exchanger 100. However, the circulation process may continue until sufficient time has been judged to have passed.

During the removal of the condensed or solidified lubricating oil in the heat exchanger 100 by utilizing the bypass line BL, the eighth valve 581 is closed and the lubricant collected in the gas-liquid separator 700 is supplied to the fifth supply line L5 So that it is not sent to the storage tank (T). When the lubricating oil is introduced into the storage tank T, the purity of the liquefied gas stored in the storage tank T may be lowered, thereby decreasing the value of the liquefied gas.

6) In the gas-liquid separator 700  The step of discharging the collected lubricating oil

The lubricating oil discharged from the heat exchanger 100 and having a lowered or reduced viscosity is collected in the gas-liquid separator 700. The lubricating oil collected in the gas-liquid separator 700 is discharged to the outside.

In order to process the lubricating oil collected in the gas-liquid separator 700, a gas-liquid separator 700 having improved gas-liquid separator 700 conventionally used in the present embodiment can be used.

The gas-liquid separator 700 of this embodiment includes a fifth supply line L5 for discharging the liquefied gas separated by the gas-liquid separator 700 and a sixth supply line L5 for discharging the vaporized gas separated by the gas- (Not shown) for discharging the lubricating oil collected in the gas-liquid separator 700 may be additionally provided.

Further, since the lubricating oil collected in the gas-liquid separator 700 can not be discharged naturally or takes a long time to be discharged, the lubricating oil in the gas-liquid separator 700 can be discharged through the nitrogen purge. When nitrogen of approximately 5 to 7 bar is supplied to the gas-liquid separator 700, the pressure in the gas-liquid separator 700 becomes high, so that the oil can be discharged quickly.

7) The heat exchanger 100 Normalized  Steps to check

It is determined that the condensed or solidified lubricating oil in the heat exchanger 100 is discharged and the heat exchanger 100 is normalized again and the lubricating oil in the gas-liquid separator 700 is discharged, The second valve 520 is opened, the bypass valve 590 is closed, and then the evaporation gas remelting system is normally operated. When the evaporation gas re-liquefaction system is operated normally, the evaporated gas discharged from the storage tank T is used as refrigerant in the heat exchanger 100, and the evaporated gas used as the refrigerant in the heat exchanger 100 is discharged from the compressor 200 A compression process, a cooling process by the heat exchanger 100, and a decompression process by the pressure reduction device 600, all or part of the liquid is re-liquefied.

The determination that the heat exchanger 100 has been normalized again can be carried out in such a manner as to determine whether or not to remove the condensed or solidified lubricating oil by determining the difference between the temperature difference of the low temperature flow, the temperature difference of the high temperature flow, 'Can be used as an indicator.

Condensation or solidified lubricating oil accumulated in piping, valves, meters, and various equipment as well as condensed or solidified lubricating oil in the heat exchanger 100 can be removed through the above-described process.

Conventionally, during the above-described steps of removing the condensed or solidified lubricant in the heat exchanger 100 from the heat exchanger 100 by utilizing the bypass line BL, the high-pressure engine and / or the low- Engine "). When the parts of equipment included in the fuel supply system or the re-liquefaction system are to be serviced, it is not normally possible to supply the engine with fuel or to re-liquefy the excess evaporative gas, so that the engine is not driven.

However, as in the present invention, when the engine is driven while removing the condensed or solidified lubricating oil in the heat exchanger 100, the heat exchanger 100 can be maintained while continuing the operation of the engine, ), It is possible to propel the ship and generate power, and it is possible to remove condensed or solidified lubricating oil by utilizing the surplus evaporation gas that is used in the engine.

In addition, when the engine is driven while removing the condensed or solidified lubricating oil in the heat exchanger 100, there is an advantage that the lubricating oil, which is compressed by the compressor 200 and mixed with the evaporated gas, can be burned by the engine. That is, the engine is used not only for the purpose of propulsion or power generation of the ship, but also for removing the oil mixed with the evaporative gas.

2 is a schematic diagram of a vaporization gas remelting system according to a second preferred embodiment of the present invention.

The evaporation gas re-liquefaction system of the second embodiment shown in Fig. 2 is different from the evaporation gas re-liquefaction system of the first embodiment shown in Fig. 1 in that instead of the first pressure sensor 910 and the second pressure sensor 920, There is a difference in that a sensor 930 is installed. In the following, differences will be mainly described. A detailed description of the same components as those of the evaporation gas re-liquefaction system of the first embodiment described above will be omitted.

The evaporation gas re-liquefaction system of the present embodiment differs from the first embodiment in that the third supply line L3 in front of the heat exchanger 100 is replaced by the third pressure supply line L3 instead of the first pressure sensor 910 and the second pressure sensor 920, And a differential pressure sensor 930 for measuring the pressure difference between the fourth supply line L4 at the rear end of the heat exchanger 100 and the fourth supply line L4.

The pressure difference of the high-temperature flow path "can be determined by the pressure difference sensor 930. As in the first embodiment, the pressure difference of the high-temperature flow path, the temperature difference of the low temperature flow, One or more can be used as an indicator to determine whether to remove condensed or solidified lubricant.

3 schematically shows the shape of a piping installed between the heat exchanger 100 and the decompression device 600 in the evaporation gas remelting system shown in Figs. 1 and 2. As shown in Fig.

The inventors of the present invention have found that lubricating oil can be introduced into the storage tank T while blocking the decompression device 600 while discharging the condensed or solidified lubricating oil by the bypass line BL.

Particularly, despite the action of closing the eighth valve 581 to prevent the lubricating oil collected in the gas-liquid separator 700 from being sent to the storage tank T along the fifth supply line L5, a part of the lubricating oil is stored in the storage tank T). ≪ / RTI >

3, the piping installed between the heat exchanger 100 and the decompression device 600 includes a first horizontal portion hu1, a first vertical portion pu1, a second horizontal portion pu2, A portion hu2, and a second vertical portion pu2.

A lubricant discharge valve 590 may be connected to the lower end of the second vertical portion pu2 and a lubricant collecting means 750 may be provided below the lubricant discharge valve 590. [

The first horizontal portion hu1 extends horizontally by a predetermined length and is connected to the upper portion of the first vertical portion pu1 and the first vertical portion pu1 extends downward from the first horizontal portion hu1 by a predetermined length And is connected to the second horizontal portion hu2.

The second horizontal portion hu2 extends horizontally in a predetermined direction from the lower portion of the first vertical portion pu1 and is connected to the middle portion of the second vertical portion pu2. It is preferable that the second horizontal portion hu2 extends in a direction opposite to the first horizontal portion hu1 so as to facilitate the utilization of the space around the pipe. The second horizontal portion hu2 is preferably shorter than the first horizontal portion hu1 so that the second vertical portion pu2 is located below the first horizontal portion hu1, And may be about half the length of the horizontal portion hu1.

In FIG. 3, the second vertical part pu2 is positioned directly below the first horizontal part hu1. However, the second vertical part pu2 is not limited to the first horizontal part hu1, The second vertical part pu2 may be located and another piping may be located below the first horizontal part hu1 and the second vertical part pu2 may be located under the other piping.

The second vertical portion pu2 extends upwardly from one side of the second horizontal portion hu2 by a predetermined length and extends downward by a predetermined length. The upper portion of the second vertical portion pu2 is connected to the decompression device 600 and the lower end of the second vertical portion pu2 is connected to the lubricant discharge valve 590. [

The piping installed between the heat exchanger 100 and the decompressor 600 of the present embodiment may further include a third horizontal portion hu3 and a third vertical portion pu3.

The third horizontal part hu3 has one side connected to the upper part of the second vertical part pu2 and extended horizontally by a predetermined length from the upper part of the second vertical part pu2, Lt; / RTI > The third horizontal portion hu3 may extend in the same direction as the second horizontal portion hu2 or may extend in a direction opposite to the first horizontal portion hu1 so as to facilitate utilization of the space around the pipe.

The third vertical part pu3 extends upward from the other side of the second horizontal part hu2 and the upper part of the third vertical part pu3 is connected to the decompression device 600. [

It is preferable that the first horizontal portion hu1 and the second horizontal portion hu2 have a slight inclination so that the lubricant can flow well along the bottom surface. The first horizontal portion hu1 may be inclined to the first vertical portion pu1 and the second horizontal portion hu2 may be inclined to the second vertical portion pu2, (Right side with reference to Fig. 3).

The flow of the fluid inside the piping installed between the heat exchanger 100 and the decompressor 600 of the present embodiment is as follows.

The evaporated gas discharged from the hot channel of the heat exchanger 100 is sent to the second vertical portion pu2 through the first horizontal portion hu1, the first vertical portion pu1 and the second horizontal portion hu2. In the second vertical portion pu2, the evaporated gas moves upward and is sent to the pressure reducing device 600, and the relatively denser lubricating oil is collected at the lower portion of the second vertical portion pu2.

The lubricating oil collected under the second vertical portion pu2 opens the lubricating oil discharge valve 590 and discharges it to the outside.

When the piping installed between the heat exchanger 100 and the decompressor 600 of the present embodiment includes the third horizontal portion hu3 and the third vertical portion pu3, The moved evaporated gas is sent to the third horizontal portion hu3 and the evaporated gas sent to the third horizontal portion hu3 is sent to the decompressor 600 through the third vertical portion pu3.

The lubricating oil discharge valve 590 may be a Double Block and Bleed Valve (DDB). A DDB valve is a valve that blocks two points of a pipe and bleed the fluid between two points that are shut off. It usually has two valves that block the fluid, Bleed).

It is desirable to apply a DDB valve that blocks two points of the piping by two valves to the lubricating oil discharge valve 590 because there is a risk of leakage if the high pressure piping is blocked by a single valve (Single Block Valve).

In addition, a differential pressure sensor 930 (FIG. 2) or a second pressure sensor 920 (FIG. 1) may be installed downstream of the second vertical portion pu2. During maintenance, the residual fluid must be drained to reduce the pressure so that safety problems do not occur. The DDB valve is installed upstream of the pressure measuring device, such as a differential pressure sensor or a pressure sensor, and can discharge the residual fluid to lower the pressure.

Therefore, the application of the DDB valve to the lubricating oil discharge valve 590 of the present invention is advantageous in that a differential pressure sensor (930 of FIG. 2) or a second pressure sensor (920 of FIG. 1) is installed downstream of the second vertical portion pu2 This can be especially meaningful in some cases.

When the piping provided between the heat exchanger 100 and the decompressor 600 of the present embodiment includes the third horizontal portion hu3 and the third vertical portion pu3, A sensor (930 of FIG. 2) or a second pressure sensor (920 of FIG. 1) is preferably provided.

On the other hand, the lubricating oil collected at the lower portion of the second vertical portion pu2 and discharged to the outside by the lubricating oil discharge valve 590 can be collected in the lubricating oil collecting means 750. Drip trays and the like may be applied to the lubricating oil collecting means 750, and the lubricating oil collected in the lubricating oil collecting means 750 may be collected periodically.

According to the present invention, while the condensed or solidified lubricating oil is discharged by the bypass line BL, the lubricating oil can be effectively collected in the second vertical portion pu2 and then discharged by the lubricant discharge valve 590. [ The lubricating oil collected in the second vertical portion pu2 may be discharged by the lubricating oil discharge valve 590 after completion of the process of discharging the condensed or solidified lubricating oil by the bypass line BL in accordance with the system operation .

Further, according to the present invention, even when the shape of the pipe is improved, the lubricating oil can be efficiently collected at the lower portion of the second vertical portion pu2, and the lubricating oil can be efficiently discharged It is possible to solve the problem that the lubricating oil blocks the decompression device 600 or flows into the storage tank T. [

According to the present invention, it is possible to lower the probability that the lubricant is introduced into the decompression apparatus (600) or the storage tank (T), not only during discharge of the lubricant by the bypass line (BL)

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 BL: Bypass line
SL: fuel supply line 100: heat exchanger
200: compressor 300: oil separator
410, 420: Oil filter 550: Reverse flow prevention valve
590: Bypass valve 600: Pressure reducing device
700: gas-liquid separator 750: lubricating oil collecting means
910, 920: Pressure sensor 930: Differential pressure sensor
810, 820, 830, 840: Temperature sensor
L1, L2, L3, L4, L5, L6: supply line
RC1, RC2, RC3, RC4: recirculation line
541, 542, 543, 544: recirculation valve
210, 220, 230, 240, 250: cylinder
211, 221, 231, 241, 251:
510, 520, 560, 570, 581, 582: valves
590: Lubricating oil discharge valve

Claims (15)

The evaporated gas is compressed by a compressor, the evaporated gas compressed by the compressor is cooled by heat exchange with the low temperature evaporated gas before being compressed by the compressor in a heat exchanger, and the cooled fluid is decompressed by the decompressor, A method for discharging a lubricating oil in a system for re-
Wherein the compressor includes at least one oil-feeding cylinder,
Supplying the low temperature evaporative gas, which is intended to be used as a refrigerant in the heat exchanger, to the compressor through a bypass line provided to bypass the heat exchanger,
A condenser for condensing or solidifying the lubricating oil, a condenser for condensing the condensed or solidified lubricating oil,
And a pipe provided between the heat exchanger and the decompression device,
A first horizontal portion into which the evaporated gas discharged from the high-temperature flow path of the heat exchanger flows and which extends horizontally by a predetermined length;
A first vertical part extending downward from the one side of the first horizontal part by a predetermined length;
A second horizontal portion extending horizontally by a predetermined length from a lower portion of the first vertical portion; And
And a second vertical part extending a predetermined length upward from one side of the second horizontal part and extending a predetermined length downwardly,
Wherein the lubricating oil is collected at the lower portion of the second vertical portion and the evaporated gas is supplied to the decompression device via the upper portion of the second vertical portion. The method according to claim 1,
During the liquefaction of the evaporated gas, the liquefied liquefied gas and the evaporated gas remaining in the gaseous state are separated by the gas-liquid separator, and the gaseous vaporized gas separated by the gas-liquid separator is discharged from the gas-liquid separator And,
Wherein the lubricating oil is melted by the evaporation gas whose temperature is increased by the compressor and lowered in viscosity, and the discharged lubricating oil collects in the gas-liquid separator. The method according to claim 1,
Wherein the high-temperature flow path of the heat exchanger and the evaporation gas that has passed through the decompression device are again sent to the bypass line and then repeated by the compressor. The method according to any one of claims 1 to 3,
The temperature difference between the temperature of the evaporator gas used as the refrigerant in the heat exchanger at the front end of the heat exchanger and the evaporator gas cooled by the heat exchanger after being compressed by the compressor is hereinafter referred to as' ) Is equal to or greater than the first set value for a predetermined time or longer;
The temperature difference between the temperature of the evaporation gas used as the refrigerant in the heat exchanger and the evaporation gas sent to the heat exchanger after being compressed by the compressor is hereinafter referred to as a " A condition in which the state lasts for a certain period of time; And
The pressure difference between the pressure at the front end of the heat exchanger and the evaporator gas cooled by the heat exchanger at the rear end of the heat exchanger after being compressed by the compressor, ) Is equal to or greater than the second set value for a predetermined period of time or longer;
Is satisfied, it is determined that " the point at which condensed or solidified lubricating oil should be discharged ". The method according to any one of claims 1 to 3,
The temperature difference between the temperature of the evaporator gas used as the refrigerant in the heat exchanger at the front end of the heat exchanger and the evaporator gas cooled by the heat exchanger after being compressed by the compressor (hereinafter, ); And a temperature difference between the temperature of the evaporation gas used as the refrigerant in the heat exchanger and the evaporation gas sent to the heat exchanger after being compressed by the compressor (hereinafter, referred to as 'temperature difference of the high temperature flow'); The state in which the smaller value is greater than or equal to the first set value continues for a predetermined time or more,
The pressure difference between the pressure at the front end of the heat exchanger and the evaporator gas cooled by the heat exchanger at the rear end of the heat exchanger after being compressed by the compressor, ) Is equal to or greater than the second set value continues for a predetermined time or longer,
A time point at which the " condensed or solidified lubricating oil should be discharged ". A compressor for compressing the evaporating gas;
A heat exchanger that uses a low-temperature evaporation gas before being compressed by the compressor as a refrigerant to cool the evaporation gas compressed by the compressor by heat exchange; And
And a decompression device for decompressing the fluid cooled by the heat exchanger,
And a pipe provided between the heat exchanger and the decompression device,
A first horizontal portion into which the evaporated gas discharged from the high-temperature flow path of the heat exchanger flows and which extends horizontally by a predetermined length;
A first vertical part extending downward from the one side of the first horizontal part by a predetermined length;
A second horizontal portion extending horizontally by a predetermined length from a lower portion of the first vertical portion; And
And a second vertical part extending from a side of the second horizontal part upward by a predetermined length and extending downward by a predetermined length,
Wherein the lubricating oil is collected in the lower portion of the second vertical portion and the evaporation gas is supplied to the decompression device via the upper portion of the second vertical portion. The method of claim 6,
And a lubricating oil discharge valve connected to the lower end of the second vertical portion. The method of claim 7,
Wherein the lubricating oil discharge valve is a DDB valve. The method of claim 6,
And a pipe provided between the heat exchanger and the decompression device,
A third horizontal part connected at one side to the upper part of the second vertical part and extending horizontally by a predetermined length from the upper part of the second collecting part; And
And a third vertical part extending upward from the other side of the third horizontal part,
And the evaporation gas sent to the third horizontal portion through the upper portion of the second vertical portion passes through the third horizontal portion and the third vertical portion and is supplied to the decompression device. The method of claim 9,
A second pressure sensor installed downstream of the hot flow path of the heat exchanger and measuring the pressure of the evaporated gas cooled by the heat exchanger after being compressed by the compressor; or
And a differential pressure sensor for measuring a pressure difference between upstream and downstream of the high-temperature flow path of the heat exchanger,
Wherein the second pressure sensor or the differential pressure sensor is installed on the third horizontal portion. The method according to claim 7 or 8,
And a lubricant collecting means provided below the lubricant discharge valve for collecting lubricant discharged by the lubricant discharge valve. 11. The method according to any one of claims 6 to 10,
And the second horizontal portion extends in a direction opposite to the first horizontal portion. The method according to claim 9 or 10,
Wherein the third horizontal portion extends in the same direction as the second horizontal portion or extends in a direction opposite to the first horizontal portion. 11. The method according to any one of claims 6 to 10,
Wherein the first horizontal portion and the second horizontal portion have a slope so that the lubricant can flow along the bottom surface. 11. The method according to any one of claims 6 to 10,
Wherein the second horizontal portion is shorter in length than the first horizontal portion.

Images