KR20190013393A - Boil-Off Gas Reliquefaction System and Method of Discharging Lubrication Oil in the Same, and Method of Supplying Fuel for Engine - Google Patents

Abstract

Disclosed is a method of discharging lubrication oil in a system which compresses a boil-off gas by a first compressor, cools the compressed boil-off gas by exchanging heat with the boil-off gas before being compressed in a heat exchanger, decompresses a fluid cooled by heat exchange by a first decompressing device, reliquefies the boil-off gas. The method of discharging lubrication oil includes: a step of activating an alarm; and a step of generating the alarm. The first compressor includes at least one oil feeding cylinder and determines through the alarm whether or not condensed or solidified lubrication oil is removed.

Description

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

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.

According to an aspect of the present invention, there is provided a method of operating a compressor, comprising: compressing an evaporated gas by a first compressor, cooling the compressed evaporated gas by heat exchange in a heat exchanger with the evaporated gas before being compressed, 1. A method for discharging a lubricating oil in a system for re-liquefaction of an evaporating gas by reducing pressure by a first pressure reducing device, comprising the steps of: 1) activating an alarm; And 2) generating the alarm, wherein the first compressor includes at least one oil-feeding cylinder and detects by the alarm whether or not to remove condensed or solidified lubricating oil. A lubricating oil discharge method is provided.

In the step 1), the alarm may be activated when the system re-liquefies the evaporation gas.

In the step (1), when the opening ratio of the first decompressor is equal to or larger than the first predetermined value, it can be determined that the system is re-liquefying the evaporated gas.

The second decompression device may be installed in parallel with the first decompression device, and in the case where the opening rate of the first decompressor or the second decompressor is equal to or larger than the first set value in the step 1) It can be judged that the gas is re-liquefied.

A plurality of the first decompression devices may be installed in series, a plurality of second decompression devices may be installed in series, and a plurality of the first decompression devices installed in series may be installed in series. In the case where the opening ratio of any one of the plurality of first decompression devices or the plurality of second decompression devices is equal to or larger than the first set value in the step 1) It is judged that the liquid is re-liquefied.

Some or all of the evaporated gas compressed by the first compressor may be used as the fuel of the engine and the excess evaporated gas not used as the fuel of the engine may be re-liquefied.

A seventh valve may be provided on a line for supplying surplus evaporated gas not used as fuel of the engine among the evaporated gases compressed by the first compressor to the heat exchanger, and in the first step, the seventh valve is opened State, it can be determined that the system is re-liquefying the evaporated gas.

A second compressor may be installed in parallel with the first compressor and part or all of the evaporated gas compressed by the second compressor is used as the fuel of the engine and a surplus evaporated gas not used as the fuel of the engine And a tenth valve may be installed on the line for supplying surplus evaporated gas not used as the fuel of the engine among the evaporated gases compressed by the second compressor to the heat exchanger, And may determine that the system is re-liquefying the evaporated gas when the seventh valve or the tenth valve is open.

A gas-liquid separator is provided at the downstream of the first decompression device to separate the liquefied gas re-liquefied by the gas-liquid separator from the remaining vaporized gas. In the step 1), the liquefied gas The system can judge that the evaporation gas is re-liquefied when the water level of the evaporation gas is equal to or higher than the second set value.

A second valve may be provided on a line through which the evaporation gas used as a refrigerant is discharged from the heat exchanger, and in the first step, if the second valve further satisfies the condition of the open state, It can be judged that the gas is re-liquefied.

In the step 2), the 'temperature difference of the low temperature flow' of the heat exchanger is larger than that of the normal case, and the condition is maintained for a predetermined time or longer. The temperature difference of the high-temperature flow of the heat exchanger is larger than that of the normal case and the condition is maintained for a predetermined time or longer; And a condition that the pressure difference of the high-temperature flow path of the heat exchanger is greater than that of the normal case and the state thereof is maintained for a predetermined time or longer; The above alarm may be generated.

In the step (2), the smaller of the 'temperature difference of the low temperature stream' of the heat exchanger and the 'temperature difference of the high temperature stream' of the heat exchanger may be longer than the third set value, The alarm may be generated if the pressure difference of the high-temperature flow path is equal to or greater than the fourth set value and is continued for the first set time or longer.

According to another aspect of the present invention, there is provided a refrigerator including: a first compressor for compressing an evaporative gas; A heat exchanger that cools the evaporated gas compressed by the first compressor by heat exchange using the evaporated gas before being compressed by the first compressor as a refrigerant; A first decompressor installed downstream of the heat exchanger for decompressing the fluid cooled by the heat exchanger; And a second decompression device installed downstream of the heat exchanger for decompressing the fluid cooled by the heat exchanger, wherein the first decompressor and the second decompressor are installed in parallel, and the first compressor There is provided an evaporation gas remelting system comprising at least one oil-feeding cylinder.

A plurality of the first pressure reducing devices may be installed in series, and a plurality of the second pressure reducing devices may be installed in series.

An isolation valve may be provided at the front end and the rear end of the first decompression device, and an isolation valve may be provided at the front end and the rear end of the second decompression device, respectively.

The evaporation gas re-liquefaction system may further include a second compressor installed in parallel with the first compressor.

According to another aspect of the present invention, there is provided a fuel supply method for an engine in which an evaporation gas is used as fuel in an engine and a surplus evaporation gas is re-liquefied, characterized in that the condensed or solidified lubricating oil is melted or lowered Fuel is supplied to the engine while discharging, and whether or not to remove condensed or solidified lubricating oil is detected by an alarm.

The method for supplying fuel to the engine includes: 1) activating the alarm; And 2) generating the alarm.

In the step 1), the alarm may be activated when the evaporation gas is re-liquefied.

In the step 2), the 'temperature difference of the low temperature flow' of the heat exchanger is larger than that of the normal case and the condition is maintained for a predetermined time or longer; The temperature difference of the high-temperature flow of the heat exchanger is larger than that of the normal case and the condition is maintained for a predetermined time or longer; And a condition that the pressure difference of the high-temperature flow path of the heat exchanger is greater than that of the normal case and the state thereof is maintained for a predetermined time or longer; The above alarm may be generated.

According to another aspect of the present invention, there is provided a compressor for compressing an evaporative gas; A heat exchanger that cools the evaporated gas compressed by the compressor by heat exchange using the evaporated gas before being compressed by the compressor as a refrigerant; And a decompression device installed downstream of the heat exchanger for reducing the pressure of the fluid cooled by the heat exchanger, wherein the first temperature sensor is disposed at a front end of the low temperature channel of the heat exchanger, A fourth temperature sensor; A second temperature sensor provided at a downstream end of the low-temperature flow path of the heat exchanger, and a third temperature sensor provided at a front end of the high-temperature flow path of the heat exchanger; A first pressure sensor provided at a front end of the high-temperature flow path of the heat exchanger, and a second pressure sensor provided at a downstream end of the high-temperature flow path of the heat exchanger; Wherein the compressor comprises at least one oil-feeding cylinder. ≪ Desc / Clms Page number 5 >

According to another aspect of the present invention, there is provided a compressor for compressing an evaporative gas; A heat exchanger that cools the evaporated gas compressed by the compressor by heat exchange using the evaporated gas before being compressed by the compressor as a refrigerant; And a decompression device installed downstream of the heat exchanger for reducing the pressure of the fluid cooled by the heat exchanger, wherein the first temperature sensor is disposed at a front end of the low temperature channel of the heat exchanger, A fourth temperature sensor; A second temperature sensor provided at a downstream end of the low-temperature flow path of the heat exchanger, and a third temperature sensor provided at a front end of the high-temperature flow path of the heat exchanger; And a pressure difference sensor for measuring a pressure difference between a front end and a rear end of the high temperature flow path of the heat exchanger; Wherein the compressor comprises at least one oil-feeding cylinder. ≪ Desc / Clms Page number 5 >

According to another aspect of the present invention, there is provided a method for reducing the pressure of an evaporation gas, comprising: compressing an evaporation gas by a compressor, cooling the evaporation gas by heat exchange in a heat exchanger with the evaporation gas before the compression, An evaporation gas re-liquefaction system comprising: at least one oil-feeding cylinder; and an alarm sounding when an abnormality in the performance of the heat exchanger is sensed.

According to another aspect of the present invention, there is provided a method for discharging a lubricating oil in a system for re-liquefying an evaporating gas by using the evaporating gas itself as a refrigerant, A temperature difference measured by a temperature sensor measured at a first temperature sensor provided upstream of the low temperature channel of the heat exchanger and a temperature measured by a fourth temperature sensor disposed at a downstream end of the high temperature channel of the heat exchanger, And a temperature difference measured by a second temperature sensor provided at a downstream end of the low-temperature flow path of the heat exchanger and a temperature difference measured by a third temperature sensor provided upstream of the high-temperature flow path of the heat exchanger; Or the difference between the pressure measured by the first pressure sensor provided on the upstream side of the high-temperature flow path of the heat exchanger and the pressure difference measured by the second pressure sensor provided after the high-temperature flow path of the heat exchanger as the index, To determine whether or not it is necessary to discharge the lubricating oil.

According to another aspect of the present invention, there is provided a method for discharging a lubricating oil in a system for re-liquefying an evaporating gas by using the evaporating gas itself as a refrigerant, A temperature difference measured by a temperature sensor measured at a first temperature sensor provided upstream of the low temperature channel of the heat exchanger and a temperature measured by a fourth temperature sensor disposed at a downstream end of the high temperature channel of the heat exchanger, And a temperature difference measured by a second temperature sensor provided at a downstream end of the low-temperature flow path of the heat exchanger and a temperature difference measured by a third temperature sensor provided upstream of the high-temperature flow path of the heat exchanger; Or a pressure difference measured by a pressure difference sensor measuring the pressure difference between the upstream and the downstream of the high-temperature flow path of the heat exchanger as an index, determines whether it is necessary to discharge the condensed or solidified lubricating oil do.

According to another aspect of the present invention, there is provided a method for reducing the pressure of an evaporation gas, comprising: compressing an evaporation gas by a compressor, cooling the evaporation gas by heat exchange in a heat exchanger with the evaporation gas before the compression, A method for discharging a lubricating oil in a system for re-liquefying a vaporized gas by reducing the pressure by means of an apparatus, wherein evaporation gas used as a refrigerant in the heat exchanger is supplied to the heat exchanger along a first supply line, The evaporated gas used is supplied to the compressor along a second supply line and the evaporated gas before being used as refrigerant in the heat exchanger can be supplied to the compressor bypassing the heat exchanger along the bypass line, A bypass valve is provided for controlling the flow rate of the fluid and the opening and closing of the fluid, And a second valve for controlling the flow rate and opening and closing of the fluid is provided at a rear end of the heat exchanger on the second supply line, 2) opening the detour valve, closing the first valve and the second valve; 3) the evaporation gas before being used as a refrigerant in the heat exchanger is compressed by the compressor through the bypass line; And 4) sending some or all of the evaporated gas compressed by the compressor to the heat exchanger, wherein the condensed or solidified lubricant is compressed or lowered in viscosity by the evaporated gas compressed by the compressor A lubricating oil discharge method is provided.

According to another aspect of the present invention, there is provided a compressor for compressing an evaporative gas; A heat exchanger for cooling the evaporated gas compressed by the compressor by heat-exchanging the evaporated gas discharged from the storage tank with refrigerant; A first valve installed on a first supply line for supplying an evaporative gas to be used as a refrigerant in the heat exchanger to the heat exchanger, the first valve controlling the flow rate and opening / closing of the fluid; A second valve installed on a second supply line for supplying an evaporative gas used as a refrigerant in the heat exchanger to the compressor, the second valve controlling the flow rate and opening / closing of the fluid; A bypass line bypassing the heat exchanger and supplying it to the compressor; And a decompression device disposed downstream of the heat exchanger for reducing the pressure of the fluid cooled by the heat exchanger, wherein the compressor includes at least one oil-feeding cylinder, Wherein the branching from the first supply line and joining to the second supply line at the end of the second valve is provided.

According to another aspect of the present invention, there is provided a method for reducing the pressure of an evaporation gas, comprising: compressing an evaporation gas by a compressor, cooling the evaporation gas by heat exchange in a heat exchanger with the evaporation gas before the compression, CLAIMS 1. A method of discharging lubricating oil in a system for re-liquefaction of an evaporating gas by reducing pressure by an apparatus, the compressor comprising at least one oil-feeding cylinder, bypassing the heat exchanger through a bypass line, And supplying the evaporated gas compressed by the compressor to the engine and supplying the residual evaporation gas remaining to the engine to the heat exchanger so as to be condensed or solidified by the evaporated gas compressed by the compressor and heated to a high temperature Characterized in that the lubricating oil is lubricated A method for draining oil is provided.

According to another aspect of the present invention, there is provided a method of discharging a lubricating oil in a system for re-liquefying an evaporating gas by using the evaporating gas itself as a refrigerant, The compressor is provided with at least one oil-feeding cylinder, and is installed to bypass the heat exchanger, so that the maintenance of the heat exchanger There is provided a lubricating oil discharging method for dissolving condensed or solidified lubricating oil or discharging the condensed lubricating oil at a lowered viscosity.

According to another aspect of the present invention for achieving the above object, there is provided a fuel supply method characterized in that the engine is supplied with fuel even while melting or discharging the 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 for exchanging heat between the evaporated gas compressed by the compressor and the evaporated gas before being compressed by the compressor, A decompression device installed downstream of the heat exchanger to decompress the fluid cooled by the heat exchanger; And a gas-liquid separator provided at a downstream end of the pressure-reducing device for separating the re-liquefied liquefied gas and the gas remaining in the gaseous state, wherein the compressor includes at least one oil-feeding cylinder, There is provided an evaporation gas remelting system to which a lubricating oil discharge line for discharging lubricating oil collected inside the gas-liquid separator is connected.

According to another aspect of the present invention, there is provided a method of discharging a lubricating oil in a system for re-liquefying an evaporating gas by using the evaporating gas itself as a refrigerant, comprising the steps of: And the lubricant discharge line is provided separately from a fifth supply line for discharging the liquefied liquefied gas from the gas-liquid separator during evaporation gas re-liquefaction, wherein the lubricating oil discharge line is provided separately from the gas- .

According to another aspect of the present invention, there is provided a method for reducing the pressure of an evaporation gas, comprising: compressing an evaporation gas by a compressor, cooling the evaporation gas by heat exchange in a heat exchanger with the evaporation gas before the compression, A method of discharging a lubricating oil in a system for re-liquefaction of an evaporating gas by decompressing by an apparatus, characterized in that the compressor comprises at least one oil-feeding cylinder, wherein the evaporator gas is used as a refrigerant in the heat exchanger (Hereinafter referred to as " temperature difference of the low temperature flow ") of the evaporation gas cooled by the heat exchanger after being compressed by the compressor is equal to or higher than the first set value for a predetermined time or more; 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 is determined that " the time when condensed or solidified lubricant should be discharged " is provided.

According to another aspect of the present invention, there is provided a method for reducing the pressure of an evaporation gas, comprising: compressing an evaporation gas by a compressor, cooling the evaporation gas by heat exchange in a heat exchanger with the evaporation gas before the compression, A method of discharging a lubricating oil in a system for re-liquefaction of an evaporating gas by decompressing by an apparatus, characterized in that the compressor comprises at least one oil-feeding cylinder, wherein the evaporator gas is used as a refrigerant in the heat exchanger (Hereinafter referred to as " temperature difference of the low temperature flow ") of the evaporator gas cooled by the heat exchanger after being compressed by the compressor; 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 it is determined that 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 passage ") is equal to or higher than the second predetermined value exceeds a predetermined time, , A lubricating oil discharge method is provided.

According to another aspect of the present invention, there is provided a method of discharging a lubricating oil in a system for re-liquefying an evaporating gas by using a volatile gas itself as a refrigerant, the method comprising: A point of time at which condensed or solidified lubricating oil should be discharged "as an index, and notifying the time when the condensed or solidified lubricating oil should be discharged by an alarm.

According to another aspect of the present invention, there is provided a refrigerating apparatus comprising: a compressor for compressing an evaporation gas; a heat exchanger for exchanging heat by using an evaporation gas before the evaporation gas compressed by the compressor is compressed by the compressor, And a decompression device for decompressing the fluid cooled by the heat exchanger, wherein the evaporation gas re-liquefaction system comprises at least one of a front end and a rear end of the heat exchanger and detects whether the heat exchanger is clogged with lubricant Sensing means; And an alarm indicating the phenomenon that the heat exchanger sensed by the sensing means is clogged by the lubricating oil.

According to another aspect of the present invention, there is provided a compressor for compressing an evaporative gas; A heat exchanger that cools the evaporated gas compressed by the compressor by heat exchange using the evaporated gas before being compressed by the compressor as a refrigerant; A decompression device installed downstream of the heat exchanger for decompressing the fluid cooled by the heat exchanger; And a second oil filter disposed at a downstream end of the pressure reducing device, wherein the compressor includes at least one oil feed cylinder and the second oil filter is at a cryogenic temperature.

According to another aspect of the present invention, there is provided a compressor for compressing an evaporative gas; A heat exchanger that cools the evaporated gas compressed by the compressor by heat exchange using the evaporated gas before being compressed by the compressor as a refrigerant; A decompression device installed downstream of the heat exchanger for decompressing the fluid cooled by the heat exchanger; A gas-liquid separator disposed at a downstream end of the decompression device to separate the re-liquefied liquefied gas from the evaporated gas remaining in a gaseous state; And a second oil filter installed on a fifth supply line through which the liquefied gas separated by the gas-liquid separator is discharged, wherein the compressor includes at least one oil-feeding cylinder and the second oil filter is at a cryogenic temperature An evaporation gas re-liquefaction system is provided.

According to another aspect of the present invention, there is provided a compressor for compressing an evaporative gas; A heat exchanger that cools the evaporated gas compressed by the compressor by heat exchange using the evaporated gas before being compressed by the compressor as a refrigerant; A decompression device installed downstream of the heat exchanger for decompressing the fluid cooled by the heat exchanger; A gas-liquid separator disposed at a downstream end of the decompression device to separate the re-liquefied liquefied gas from the evaporated gas remaining in a gaseous state; And a second oil filter installed on a sixth supply line through which the gaseous vaporized gas separated by the gas-liquid separator is discharged, wherein the compressor includes at least one oil-feeding cylinder, and the second oil The filter is a cryogenic, evaporative gas remelting system.

According to another aspect of the present invention, there is provided a compressor for compressing an evaporative gas; A heat exchanger that cools the evaporated gas compressed by the compressor by heat exchange using the evaporated gas before being compressed by the compressor as a refrigerant; A decompression device installed downstream of the heat exchanger for decompressing the fluid cooled by the heat exchanger; A bypass line bypassing the heat exchanger at a front end of the heat exchanger to supply the evaporated gas to be used as a refrigerant in the heat exchanger to the compressor; And a bypass valve installed on the bypass line for controlling the flow rate and opening and closing of the fluid, and when the pressure of the evaporative gas supplied to the compressor is lower than the suction pressure condition required by the compressor, A part of or all of which is opened.

According to another aspect of the present invention, there is provided a method for reducing the pressure of an evaporation gas, comprising: compressing an evaporation gas by a compressor, cooling the evaporation gas by heat exchange in a heat exchanger with the evaporation gas before the compression, A method for supplying fuel to an engine of a system for reducing the pressure of an evaporation gas by reducing pressure by an apparatus, the method comprising the steps of: when the pressure of the evaporation gas supplied to the compressor is lower than the suction pressure condition required by the compressor And a part or all of the evaporated gas is bypassed to the compressor and supplied to the compressor.

According to another aspect of the present invention, there is provided a compressor for compressing an evaporative gas; A heat exchanger for exchanging heat between the evaporated gas compressed by the compressor and the evaporated gas before being compressed by the compressor, A bypass line bypassing the heat exchanger and supplying it to the compressor; A second valve installed on a second supply line for sending the evaporation gas used as a refrigerant in the heat exchanger to the compressor to control the flow rate and opening and closing of the fluid; And a decompression device disposed downstream of the heat exchanger for decompressing the fluid cooled by the heat exchanger, wherein the compressor includes at least one oil-feeding cylinder, and the bypass line is connected to the downstream end of the second valve And the second supply line is joined to the second supply line.

According to another aspect of the present invention, there is provided a method for reducing the pressure of an evaporation gas, comprising: compressing an evaporation gas by a compressor, cooling the evaporation gas by heat exchange in a heat exchanger with the evaporation gas before the compression, A method of discharging a lubricating oil in a system for re-liquefying an evaporating gas by reducing the pressure by means of an apparatus, the compressor comprising at least one oil-feeding cylinder, the evaporating gas being used as a refrigerant in the heat exchanger A second valve for controlling the flow rate and opening and closing of the fluid is provided on the second supply line, the evaporation gas bypasses the heat exchanger through the bypass line and is compressed by the compressor, and the excess evaporation gas remaining after being supplied to the engine Is supplied to the heat exchanger, and the refrigerant is compressed by the compressor Sikimyeo discharge melt tarred lubricant, wherein the bypass line, wherein the, lubricant outlet method for joining the second and the second supply line of the rear end of the valve is provided.

According to another aspect of the present invention, there is provided a compressor for compressing an evaporative gas; A heat exchanger for exchanging heat between the evaporated gas compressed by the compressor and the evaporated gas before being compressed by the compressor, A bypass line bypassing the heat exchanger and supplying it to the compressor; A first valve installed on a first supply line for supplying an evaporative gas to be used as a refrigerant in the heat exchanger to the heat exchanger to control a flow rate and opening and closing of the fluid; And a decompression device disposed downstream of the heat exchanger for reducing the pressure of the fluid cooled by the heat exchanger, wherein the compressor includes at least one oil-feeding cylinder, Wherein the first supply line is branched from the first supply line.

According to another aspect of the present invention, there is provided a compressor for compressing an evaporative gas; A heat exchanger for exchanging heat between the evaporated gas compressed by the compressor and the evaporated gas before being compressed by the compressor, A bypass line branched from the first supply line for supplying the refrigerant in the heat exchanger to the first heat exchanger and bypassing the heat exchanger to supply the evaporated gas to the compressor; A decompression device installed downstream of the heat exchanger for decompressing the fluid cooled by the heat exchanger; And a gas-liquid separator provided at a downstream end of the decompression device for separating the re-liquefied liquefied gas from the evaporated gas remaining in a gaseous state, wherein the compressor includes at least one oil-feeding cylinder, Liquid separator and the sixth feed line is merged into a first feed line at a point preceding the point where the bypass line is branched, the evaporated gas remelting system / RTI >

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 .

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.
3 is a schematic diagram of a vaporization gas remelting system according to a third preferred embodiment of the present invention.
4 is an enlarged view of a gas-liquid separator according to an embodiment of the present invention.
5 is an enlarged view of a second oil filter according to an embodiment of the present invention.
6 is an enlarged view of a second oil filter according to another embodiment of the present invention.
7 is a schematic view of a vaporized gas remelting system according to a fourth preferred embodiment of the present invention.
8 is an enlarged view of a decompression apparatus according to an embodiment of the present invention.
9 is an enlarged view of a decompression apparatus according to another embodiment of the present invention.
10 is an enlarged view of a heat exchanger and a gas-liquid separator according to an embodiment of the present invention.
11 and 12 are graphs showing the amount of resolidification with the evaporation gas pressure in the Partial Re-liquefaction System (PRS).
13 is a top view of the filter element shown in Figs. 5 and 6. 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.

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 compressor 200, a heat exchanger 100, a pressure reducing device 600, a bypass line BL, and a bypass valve 590.

The compressor 200 compresses the evaporated gas discharged from the storage tank T and includes a plurality of cylinders 210, 220, 230, 240 and 250 and a plurality of coolers 211, 221, 231, 241 and 251 . The pressure of the evaporated gas compressed by the compressor 200 may be approximately 150 to 350 bar.

Some of the evaporated gas compressed by the compressor 200 can be sent to the main engine for propelling the ship along the fuel supply line SL and the remaining evaporation gas not required in the main engine is supplied to the third supply line L3, And then sent to the heat exchanger 100 to be subjected to a re-liquefaction process. The main engine may be an ME-GI engine using high pressure natural gas as the fuel with a pressure of approximately 300 bar.

Some of the evaporated gas passing through only a part of the cylinders 210 and 220 included in the compressor 200 may be branched and sent to the generator. The generator of this embodiment may be a DF engine using low pressure natural gas as the fuel with a pressure of approximately 6.5 bar.

The heat exchanger 100 is connected to the compressor 200 supplied along the third supply line L3 using the evaporation gas discharged from the storage tank T supplied along the first supply line L1 as the refrigerant Thereby cooling the evaporated gas compressed by the heat exchange. The evaporated gas used as the refrigerant in the heat exchanger 100 is supplied to the compressor 200 along the second supply line L2 and the fluid cooled in the heat exchanger 100 is supplied to the compressor 200 through the fourth supply line L4, (600).

The decompression apparatus 600 compresses 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 may be an expander.

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 discharged from the storage tank T And may be combined with the evaporated gas and sent to the heat exchanger 100.

A ninth valve 582 for controlling the flow rate and opening / closing of the fluid may be installed on the sixth supply line L6 through which the vaporized gas is discharged from the gas-liquid separator 700.

When the heat exchanger 100 can not be used, such as when the heat exchanger 100 of the present embodiment is under maintenance or the heat exchanger 100 fails, the evaporated gas discharged from the storage tank T flows through the bypass line BL The heat exchanger 100 can be bypassed. On the bypass line (BL), a bypass valve (590) for opening and closing the bypass line (BL) is provided.

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

Referring to FIG. 2, 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.

11 and 12 are graphs showing the amount of resolidification with the evaporation gas pressure in the Partial Re-liquefaction System (PRS). 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.

11 and 12, 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. Accordingly, when the ME-GI engine using the evaporation gas at a pressure of approximately 150 to 350 bar (mainly 300 bar) as the fuel is a high-pressure engine, the refueling system can be easily It has the advantage of being able to control it.

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 of the cylinders 210, 220, 230, 240, and 250 may have 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.

2 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.

2 shows a 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.

2 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.

2, 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. However, 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).

2 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 to this, 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.

4, the gas-liquid separator 700 is provided with one or more water level sensors 940 for measuring the level of the internal liquefied gas, as shown in FIG. 4, .

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- .

2 and 4, the second oil filter 420 may be installed on the fourth supply line L4 between the pressure reducing device 600 and the gas-liquid separator 700 Liquid separator 700 is discharged from the gas-liquid separator 700, and the gas-phase evaporation gas is discharged from the gas-liquid separator 700 (C position in Fig. 4). FIG. 2 shows a case where a second oil filter 420 is installed at a position A in FIG.

The gas-phase evaporated gas separated by the gas-liquid separator 700 may be combined with the evaporated gas discharged from the storage tank T and supplied to the low-temperature channel of the heat exchanger 100. In the gas-liquid separator 700, It is impossible to exclude the possibility that a small amount of lubricating oil is mixed into the gaseous vaporized gas separated by the gas-liquid separator 700.

The inventors of the present invention have found that when lubricating oil is mixed with the gaseous vaporized gas separated by the gas-liquid separator 700 and sent to the low-temperature channel of the heat exchanger 100, the lubricating oil compressed by the compressor 200, It has been found that a more difficult situation may arise than when the high-temperature flow path of the heat exchanger 100 is supplied.

Since the fluid used as the refrigerant in the heat exchanger 100 is supplied to the low-temperature flow path of the heat exchanger 100, the ultra-low temperature evaporation gas is supplied throughout the operation of the system and the high- No fluid with temperature is supplied. Therefore, it is very difficult to remove the condensed or solidified oil accumulated in the low-temperature flow path of the heat exchanger 100.

The second oil filter 420 may be disposed at the position A or the position C in FIG. 4 so as to minimize the possibility that the lubricating oil is mixed with the gaseous evaporated gas separated by the gas-liquid separator 700 and sent to the low-temperature channel of the heat exchanger 100, .

When the second oil filter 420 is installed at the position C in Fig. 4, most of the lubricating oil which has melted or reduced in viscosity is collected in the liquid state in the gas-liquid separator 700, There is an advantage that the filtering efficiency is high and the second oil filter 420 is not replaced relatively frequently.

When the second oil filter 420 is installed at the position B in FIG. 4, it is possible to block the lubricating oil flowing into the storage tank T, thereby preventing contamination of the liquefied gas stored in the storage tank T .

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 Since the temperature of the second oil filter 420 is about -160 to -150 ° C, the second oil filter 420 should be designed for a cryogenic temperature regardless of the positions of A, B, and C in FIG.

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.

FIG. 5 is an enlarged view of a second oil filter according to an embodiment of the present invention, and FIG. 6 is an enlarged view of a second oil filter according to another embodiment of the present invention.

5 and 6, the second oil filter 420 may have a structure shown in FIG. 5 (hereinafter, referred to as a "lower exhaust type"), or may have a structure shown in FIG. 6 Upper discharge type "). 5 and 6, the dotted line indicates the fluid flow direction.

5 and 6, the second oil filter 420 includes a fixing plate 425 and a filter element 421. The second oil filter 420 includes an inlet pipe 422, a discharge pipe 423, And an oil discharge pipe 424 are connected.

The filter element 421 is provided on the fixing plate 425 to separate the lubricating oil mixed with the fluid flowing through the inflow pipe 422.

FIG. 13 is a plan view of the filter element 421 shown in FIGS. 5 and 6. Referring to FIG. 13, the filter element 421 may have a cylindrical shape with a hollow (Z space in FIG. 13) ) May be a stacked multi-layered layer of different sizes. The fluid flowing through the inlet pipe 422 passes through the multi-stage layer contained in the filter element 421 and the lubricant is filtered. The filter element 421 can separate the lubricating oil by a physical adsorption method.

The fluid filtered by the filter element 421 is discharged along the discharge line 423 and the lubricant filtered by the filter element 421 is discharged through the oil discharge pipe 424 .

The material of the components used in the second oil filter 420 is made of a material which can withstand extremely low temperature to separate the lubricating oil mixed with the cryogenic fluid. The filter element 421 may be made of a metal material capable of withstanding extremely low temperatures, and specifically, the filter element 421 may be made of SUS material.

Referring to FIG. 5, the 'lower discharge type' oil filter has a structure in which the fluid supplied through the inflow pipe 422 connected to the upper portion of the oil filter passes through the filter element 421, (X in Fig. 5), and is discharged through the discharge pipe 423 connected to the lower portion of the oil filter.

A filter element 421 is installed on the upper surface of the fixing plate 425 and the filter element 421 is mounted on the fixing plate 425 with reference to the fixing plate 425. [ And the discharge pipe 423 is connected to the opposite side.

In addition, the 'lower drain type' oil filter is configured to allow the fluid introduced through the supply line 422 to be also filtered by the upper portion of the filter element 421 (i.e., to use the entire filter element as much as possible) It is preferable that the pipe 422 is connected above the upper end of the filter element 421.

It is preferred that the supply piping 422 and the discharge piping 423 are provided on opposite sides (left and right with respect to the filter element 421 in Fig. 5) in the flow of the fluid and lubricant It is preferable that the oil discharge pipe 424 is connected to the lower side of the filter element 421 because the filter element 421 is gathered under the filter element 421.

In the case of the " lower discharge type " oil filter, the oil discharge pipe 424 may be connected directly above the fixing plate 425.

As shown in FIG. 5 (a), when a fluid having a large number of liquid components (for example, a volume ratio of 90% of liquid and 10% of gas) is supplied to the oil filter of the 'lower discharge type' So that an appropriate flow from the top to the bottom occurs and the filtering effect is excellent.

However, as shown in FIG. 5 (b), when a fluid having a large number of gas components (for example, a volume ratio of 10% liquid and 90% gas) is supplied to the oil filter of the 'lower discharge type' Since the small gas component remains on the oil filter, the flow of the fluid is deteriorated and the filtering effect is also reduced.

Referring to FIG. 6, in the 'upper discharge type' oil filter, the fluid supplied through the inflow pipe 422 connected to the lower portion of the oil filter passes through the filter element 421, (Y in Fig. 6), and is discharged through the discharge pipe 423 connected to the upper portion of the oil filter.

The oil filter of the 'upper discharge type' is provided with a fixing plate 425 on the oil filter, a filter element 421 on the lower surface of the fixing plate 425, and a filter element 421 on the fixing plate 425, And the discharge pipe 423 is connected to the opposite side.

In addition, the " top discharge type " oil filter is configured to allow the fluid introduced through the supply line 422 to be filtered by the lower portion of the filter element 421 (i.e., to use the entire filter element as much as possible) It is preferable that the pipe 422 is connected further downward than the lower end of the filter element 421.

It is preferable that the supply pipe 422 and the discharge pipe 423 are provided on the opposite sides (left and right with respect to the filter element 421 in FIG. 6) in the flow of the fluid and the lubricant It is preferable that the oil discharge pipe 424 is connected to the lower side of the filter element 421 because the filter element 421 is gathered under the filter element 421.

Referring to FIG. 6, the 'upper discharge type' oil filter includes a pipe 423 connected to the upper portion of the oil filter after the fluid supplied along the pipe 422 connected to the lower portion of the oil filter passes through the filter element 421 Respectively. The lubricating oil filtered by the filter element 421 is discharged to the outside along a separate pipe 424.

As shown in FIG. 6 (a), when a fluid having a large number of gas components (for example, a volume ratio of 10% liquid and 90% gas) is supplied to the oil filter of the 'upper discharge type' Is small, an appropriate flow occurs upwards and the filtering effect is excellent.

However, as shown in FIG. 6 (b), when a fluid having a plurality of liquid components (for example, a volume ratio of 90% liquid and 10% gas) is supplied to the oil filter of the 'upper discharge type' Since large liquid components stay in the bottom of the oil filter, the flow of the fluid is deteriorated and the filtering effect is also reduced.

Therefore, when the second oil filter 420 is installed at position B in FIG. 4, it is preferable to apply the second oil filter 420, which is the 'lower exhaust type' shown in FIG. 5, When the second oil filter 420 is installed at the position, it is preferable to apply the second oil filter 420 which is the 'upper discharge type' shown in FIG.

When the second oil filter 420 is installed at the position A in FIG. 4, the fluid decompressed by the pressure reducing device 600 is in a vapor-liquid mixed state (theoretically, 100% It is preferable to apply the second oil filter 420 of the 'upper discharge type' shown in FIG. 6.

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.

The bypass line BL is used when the heat exchanger 100 can not be used, such as when the heat exchanger 100 fails or when maintenance is required. For example, when the evaporation-gas re-liquefaction system of this embodiment sends some or all of the evaporated gas compressed by the compressor 200 to the high-pressure engine, if the heat exchanger 100 can not be used, The evaporator 200 bypasses the heat exchanger 100 along the bypass line BL and supplies the evaporated gas discharged from the storage tank T directly to the compressor 200, To the high-pressure engine, and the surplus evaporated gas can be sent to the GCU for incineration.

As an example of using the bypass line BL for maintenance of the heat exchanger 100, when the flow path of the heat exchanger 100 is clogged by the condensed or solidified lubricating oil, the bypass line BL is used for condensing or solidifying And removing the lubricating oil.

When it is not necessary to re-liquefy the evaporated gas because there is no surplus evaporated gas such as the ballast condition of the ship, all of the evaporated gas discharged from the storage tank T is sent to the bypass line BL, So that it can be bypassed to the compressor (200). The evaporated gas compressed in the compressor 200 is used as the fuel of the high-pressure engine. The bypass valve 590 can be controlled to automatically open if it is determined that there is no excess evaporative gas and there is no need to re-liquefy the evaporative gas.

The inventors of the present invention have found that when the evaporation gas is supplied to the engine through a narrow heat exchanger according to the present invention, a large pressure drop of the evaporation gas is caused by the heat exchanger. When there is no need for re-liquefaction, fuel can be smoothly supplied to the engine by bypassing the heat exchanger and compressing the evaporation gas as described above.

Also, the bypass line (BL) can be used even when the evaporation gas is not re-liquefied and the amount of the evaporation gas is increased to re-vaporize the evaporation gas.

When the evaporation gas is not re-liquefied and the amount of the evaporation gas is increased to re-liquefy the evaporation gas (that is, when the evaporation gas resupply liquefaction is started or restarted), the evaporation gas discharged from the storage tank T is bypassed to the bypass line BL The entire evaporation gas bypasses the heat exchanger 100 and is directly supplied to the compressor 200. The evaporated gas compressed by the compressor 200 can be sent to the high temperature channel of the heat exchanger 100 . A part of the evaporated gas compressed by the compressor 200 may be sent to the high-pressure engine.

If the temperature of the high-temperature flow path of the heat exchanger 100 is increased at the same time as the evaporation gas re-liquefaction is started or re-circulated through the above-described process, the temperature of the hot gas flow path, which may remain in the heat exchanger 100, It is possible to start liquefaction of the evaporation gas after removing condensed or solidified lubricating oil or other impurities.

The low temperature evaporated gas immediately discharged from the storage tank T is supplied to the heat exchanger 100 without the process of raising the temperature of the high temperature flow path of the heat exchanger 100 by using the bypass line BL, The low temperature evaporated gas discharged from the storage tank T is supplied to the low temperature channel of the heat exchanger 100 while the high temperature vapor is not yet supplied to the high temperature channel of the heat exchanger 100, The lubricant that has not yet been condensed or solidified remaining in the heat exchanger 100 may be condensed or solidified as the temperature of the heat exchanger 100 is lowered.

The bypass line BL is used to continue the process of raising the temperature of the high-temperature flow path of the heat exchanger 100, and when the time has elapsed (if it is determined that the condensed or solidified lubricant or other impurities are almost removed) The valve 510 and the second valve 520 are opened gradually and the bypass valve 590 is closed gradually to start evaporation gas remelting. The first valve 510 and the second valve 520 are fully opened and the bypass valve 590 is completely closed so that all of the evaporated gas discharged from the storage tank T is discharged from the heat exchanger 100 to the evaporation gas Is used as a refrigerant for re-liquefaction.

In addition, the bypass line BL may be utilized to satisfy the suction pressure condition of the compressor 200 when the pressure inside the storage tank T is low.

In addition, when the internal pressure of the storage tank T needs to be controlled to a low range, the bypass line BL can be used to satisfy the suction pressure condition of the compressor 200 even if the pressure of the storage tank T is lowered. .

The bypass line BL is utilized to satisfy the suction pressure condition of the compressor 200 when the lubricating oil condensed or solidified by using the bypass line BL is removed and when the pressure inside the storage tank T is low The following is a detailed description of the case.

1. If bypass line (BL) is used to remove condensed or solidified lubricant

A predetermined lubricating oil is mixed in the evaporation gas that has passed through the cylinder of the oil supply and lubricating system of the compressor 200. 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 with time, so that it is necessary to remove the condensed or solidified lubricating oil in the heat exchanger 100 after a predetermined period of time The inventors of the present invention have found that the present invention is not limited thereto.

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

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

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 is determined that the lubricating oil condensed or solidified in the heat exchanger 100 should be removed if the performance falls to approximately 50 to 90%, preferably approximately 60 to 80%, more preferably approximately 70% can do.

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.

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.

Whether or not condensed or solidified lubricating oil should be removed can be determined by an alarm, which will be described later.

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 is compressed by the compressor 200 through the bypass line BL

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.

When the condensed or solidified lubricating oil is removed by utilizing the bypass line BL, the lubricating oil discharged from the storage tank T is discharged from the bypass line BL, the compressor 200, the high-temperature flow path of the heat exchanger 100, The evaporation gas that has passed through the apparatus 600 may be sent to a tank or other collection device that is installed separately from the storage tank T in a mixed state of the lubricating oil and the evaporated gas having lowered or lowered viscosity. The evaporated gas in the tank or other recovery device installed separately from the storage tank (T) can be sent back to the bypass line (BL) to continue the condensed or solidified lubricant removal process.

Even if the gas-liquid separator 700 is installed at the downstream of the pressure reducing device 600 in the case where the fluid mixed with the lubricating oil and the vaporized gas whose melting or viscosity is lowered is sent to a tank or another collecting device separately provided from the storage tank T, Since the lubricating oil 700 has the same function as the existing evaporative gas re-liquefaction system and does not collect the lubricating oil having a lowered melting or viscosity inside the gas-liquid separator 700 (the lubricating oil having a lowered or lowered viscosity is stored in the storage tank T It is not necessary to include the improved gas-liquid separator 700 for discharging the lubricating oil, so that the cost can be saved.

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

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

The lubricating oil discharged from the heat exchanger 100 and having a lowered or reduced viscosity collects in the gas-liquid separator 700. In order to process the lubricating oil collected in the gas-liquid separator 700, in the present embodiment, It is possible to use a gas-liquid separator 700 in which the separator 700 is improved.

10 is an enlarged view of a heat exchanger and a gas-liquid separator according to an embodiment of the present invention. Some of the devices have been omitted for convenience of explanation.

10, the gas-liquid separator 700 is provided with a fifth supply line L5 for sending the liquefied gas separated by the gas-liquid separator 700 to the storage tank T, A lubricating oil discharge line OL is further provided. The lubricant discharge line OL is connected to the lower end of the gas-liquid separator 700 and the end of the fifth supply line L5 is connected to the lubricant discharge line OL so that oil collected under the gas-liquid separator 700 can be effectively discharged. Liquid separator 700 is higher than the lower end of the gas-liquid separator 700. It is preferable to position the end of the fifth supply line L5 higher than the level of the lubricating oil when the amount of the lubricating oil collected in the gas-liquid separator 700 becomes maximum so that the fifth supply line L5 is not blocked by the lubricating oil .

A third valve 530 may be provided on the lubricant discharge line OL to control the flow rate and opening / closing of the fluid, and a plurality of third valves 530 may be provided.

The lubricating oil collected in the gas-liquid separator 700 can not be discharged naturally or may take a long time to be discharged. Therefore, the lubricating oil in the gas-liquid separator 700 can be discharged through nitrogen purging. 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.

A nitrogen supply line NL may be provided so as to be merged into the third supply line L3 of the upstream side of the heat exchanger 100 to discharge the lubricating oil in the gas-liquid separator 700 by nitrogen purge. A plurality of nitrogen supply lines may be provided at different positions as required.

A nitrogen valve 583 for regulating the flow rate and opening and closing of the fluid is provided on the nitrogen supply line NL and the nitrogen valve 583 is normally kept closed when the nitrogen supply line NL is not used, Liquid separator 700. When it is necessary to use the nitrogen line NL, the nitrogen valve 583 is opened. A plurality of nitrogen valves 583 may be provided.

The nitrogen purging may be performed by injecting nitrogen directly into the gas-liquid separator 700. However, if nitrogen supply lines for other purposes are already installed, .

All of the evaporated gas discharged from the storage tank T is sent to the bypass line BL to be compressed by the compressor 200 and the evaporated gas compressed by the compressor 200 is sent to the high temperature channel of the heat exchanger 100, After passing through the high-temperature flow path of the heat exchanger 100, the evaporated gas decompressed in the decompressor 600 is sent to the gas-liquid separator 700 and the evaporated gas discharged from the gas-liquid separator 700 is again sent to the bypass line BL Liquid separator 700 (that is, it is determined that the heat exchanger 100 has been normalized), the compressor 200 is operated in the same manner as described above, And the nitrogen valve 583 is opened to perform nitrogen purging.

7) confirming that the heat exchanger 100 has been normalized

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.

7 is a schematic view of a vaporized gas remelting system according to a fourth preferred embodiment of the present invention.

As shown in FIG. 7, two compressors 200 and 210 of the present invention can be installed in parallel. The two compressors 200 and 210 may have the same specifications, and when one of the compressors 200 and 210 fails, the other one may serve as a redundancy. In Fig. 7, for convenience of explanation, the illustration of other devices shown in Fig. 2 is omitted.

7, even when two compressors 200 and 210 are installed in parallel as in the present embodiment, the evaporated gas discharged from the storage tank T flows into the first supply line L1 (Or the bypass line BL) and the second supply line L2 to the first compressor 200 and the evaporated gas compressed by the first compressor 200 is partially supplied to the fuel supply line SL ), And the surplus evaporated gas is sent to the heat exchanger 100 through the third supply line L3 to be subjected to a re-liquefaction process. Also, on the third supply line L3 of the present embodiment, as in the second embodiment, a seventh valve 570 for regulating the flow rate and opening / closing of the fluid may be provided.

When two compressors 200 and 210 are installed in parallel as in the present embodiment, the evaporated gas discharged from the storage tank T flows through the first supply line L1 (or the bypass line BL) Is sent to the second compressor 210 via the supply line L22 and the evaporated gas compressed by the second compressor 210 is partly sent to the high pressure engine along the fuel supply line SL, May be sent to the heat exchanger (100) through the eighth supply line (L33) and may be subjected to a re-liquefaction process. On the eighth supply line L33, a tenth valve 571 for regulating the flow rate and opening / closing of the fluid may be provided.

FIG. 8 is an enlarged view of a decompression apparatus according to an embodiment of the present invention, and FIG. 9 is an enlarged view of a decompression apparatus according to another embodiment of the present invention.

According to the present invention, as shown in FIG. 8, two decompressors 600 and 610 can be installed in parallel. In the case where one of the two decompression devices 600 and 610 installed in parallel can not be used due to failure, maintenance, or the like, the other one may serve as redundancy, and the two decompression devices 600 and 610 installed in parallel, An isolation valve 620 may be provided at the front and rear ends of the devices 600 and 610, respectively.

9, a plurality of first pressure reducing devices 600 are installed in series, a plurality of second pressure reducing devices 610 are installed in series, and a plurality of first pressure reducing devices 600 are installed in series, A plurality of second pressure reducing devices 610 installed in series with the first pressure reducing device 600 may be installed in parallel. In FIG. 9, two first pressure reducing devices 600 and two second pressure reducing devices 610 are shown in series.

A number of decompression devices are connected in series for stability of decompression depending on the manufacturer. When a plurality of decompression devices are connected in series, the evaporation gas is decompressed through a multistage system. Therefore, There is an advantage that the burden of each decompressor can be reduced and the life of the decompressor can be prevented from being shortened.

As shown in FIG. 9, a plurality of first pressure reducing devices 600 and a plurality of second pressure reducing devices 610 are connected in series, and a plurality of first pressure reducing devices 600 installed in series and a plurality of second Even when at least one of the plurality of first pressure reducing devices 600 installed in series is broken, even when the pressure reducing devices 610 are connected in parallel, a plurality of second pressure reducing devices 610 installed in series may have a redundancy And when one or more of the plurality of second decompression devices 610 installed in series is broken, a plurality of first decompressor devices 600 installed in series may play a role of redundancy.

In addition, an isolation valve 620 may be installed at each of a front end and a rear end of the plurality of first decompression devices 600 installed in series, and an isolation valve 620 may be provided at the front end and the rear end of the plurality of second decompression devices 610, An isolation valve 620 may be provided.

The isolation valve 620 shown in Figs. 8 and 9 is used to isolate the decompression devices 600 and 610 from each other when the decompressor 600 or 610 is broken or when the maintenance of the decompressor 600 or 610 is required. (Isolation).

On the other hand, whether or not to remove the condensed or solidified lubricating oil as described above can be detected by an alarm. The process of detecting by the alarm whether to remove the condensed or solidified lubricating oil is as follows: Generating step.

① Alarm activation step

If the evaporative gas remelting system of the present invention re-liquefies the evaporative gas, the alarm is activated and the alarm may be deactivated if the evaporative gas is not re-liquefied. When the evaporative gas discharged from the storage tank (T) is all used in the engine and there is no surplus evaporating gas, or when equipment necessary for re-liquefaction can not be used due to failure, maintenance, etc., the evaporating gas is not re-liquefied.

That is, whether or not the alarm is activated can be determined depending on whether the evaporation gas re-liquefaction system of the present invention re-liquefies the evaporation gas. Whether or not the evaporation gas is re-liquefied can be determined according to the system configuration as follows can do.

(2) When the evaporation gas remelting system of the present invention includes one compressor (200) and one decompressing apparatus (600) as shown in FIG. 2

Whether or not the opening ratio of the pressure reducing device 600 is equal to or greater than the first set value, whether the seventh valve 570 is opened, whether the second valve 520 is open, And whether or not the water level is equal to or greater than the second set value is satisfied, it can be determined that the evaporation gas is re-liquefied.

However, since the second valve 520 is opened not only to re-liquefy the evaporated gas but also to supply the evaporated gas as fuel to the engine even if the evaporated gas is not re-liquefied, the "second valve 520 " Or "whether " whether " whether " whether or not the evaporation gas is re-liquefied alone " The same applies to the case where the configuration of the system is different.

The liquefied gas re-liquefied through the compression process by the compressor 200, the cooling process by the heat exchanger 100, and the decompression process by the decompressor 600 collects in the gas-liquid separator 700 , And the level of the liquefied gas in the gas-liquid separator 700 can be used as an indicator for determining whether or not the evaporated gas is re-liquefied. The second set value may vary depending on the amount of liquefied gas stored in the storage tank T, the speed of the ship, and so on.

It is preferable to determine that the evaporation gas is re-liquefied when both conditions are satisfied. For example, when the opening ratio of the pressure reducing device 600 is equal to or greater than the first set value, Liquid separator 700 is in the open state and the second valve 520 is open and the water level of the liquefied gas in the gas-liquid separator 700 is equal to or higher than the second set value, The alarm can be activated.

The first set value, which is the opening ratio of the pressure-reducing device 600, may be approximately 1% to 4%, preferably approximately 2% to 3%, and more preferably approximately 2%.

■ include a boil-off gas re-liquefaction system, the single sheet of the two pressure-connected in parallel as shown in Figure 8, it comprises a compressor 200, as values (600, 610) shown in Figure 2 of the present invention When

Whether the opening rate of the first pressure reducing device 600 or the second pressure reducing device 610 is equal to or greater than the first set value, whether the seventh valve 570 is opened, whether the second valve 520 is open And whether or not the level of the liquefied gas in the gas-liquid separator 700 is equal to or higher than the second set value, it is determined that the evaporation gas is re-liquefied.

It is preferable to determine that the evaporation gas is re-liquefied when two or more conditions are satisfied in order to increase the reliability of judgment. For example, it is preferable that the opening rate of the first decompressor 600 or the second decompressor 610 Liquid separator 700 is equal to or higher than the first set value, the seventh valve 570 is opened, the second valve 520 is opened, and the liquid level in the gas-liquid separator 700 is equal to or higher than the second set value, It can be determined that the gas is re-liquefied, and the alarm can be activated.

The first set value, which is the opening rate of the first decompressor 600 or the second decompressor 610, can be approximately 1% to 4%, preferably approximately 2% to 3%, more preferably approximately 1% 2%.

The evaporating gas remelting system of the present invention includes one compressor 200 as shown in FIG. 2, and a plurality of first pressure reducing devices 600 installed in series as shown in FIG. 9, When a plurality of second decompression devices 610 are installed in parallel

The seventh valve 570 determines whether the opening ratio of any one of the plurality of first pressure reducing devices 600 installed in series or the plurality of second pressure reducing devices 610 installed in series is equal to or larger than the first set value, Whether or not the second valve 520 is opened, and whether or not the level of the liquefied gas in the gas-liquid separator 700 is equal to or higher than the second set value is satisfied, it is determined that the evaporation gas is re-liquefied can do.

It is preferable to determine that the evaporation gas is re-liquefied when two or more conditions are all satisfied in order to increase the reliability of the judgment. For example, it is preferable to determine that the first decompressor 600, The opening degree of any one of the plurality of second decompression devices 610 installed is equal to or larger than the first set value and the seventh valve 570 is opened and the second valve 520 is opened and the gas- ) When the level of the internal liquefied gas is equal to or higher than the second set value, it can be determined that the evaporative gas is re-liquefied and the alarm can be activated.

The first set value, which is the opening rate of the first decompressor 600 or the second decompressor 610, can be approximately 1% to 4%, preferably approximately 2% to 3%, more preferably approximately 1% 2%.

(2) The evaporative gas remelting system of the present invention includes two compressors 200 and 210 installed in parallel as shown in FIG. 7, and includes one decompressor 600 as shown in FIG. 2 Occation

Whether the seventh valve 570 or the tenth valve 571 is opened, whether or not the opening degree of the decompression device 600 is equal to or greater than the first set value, whether the second valve 520 is open, It is determined that the evaporation gas is re-liquefied if at least one of the conditions is satisfied, that is, whether or not the level of the internal liquefied gas is not less than the second set value.

When the first compressor 200 is used, it is determined whether the seventh valve 570 is in the open state. If the second compressor 210 is used, the tenth valve 571 is in the open state Is used as a condition.

It is preferable to determine that the evaporation gas is re-liquefied when two or more conditions are satisfied in order to increase the reliability of judgment. For example, when the opening ratio of the pressure-reducing device 600 is equal to or greater than the first set value, When the valve 570 or the tenth valve 571 is opened and the second valve 520 is opened and the water level of the liquefied gas in the gas-liquid separator 700 is equal to or higher than the second set value, It can be determined that the liquid is liquefied, and the alarm can be activated.

The first set value, which is the opening ratio of the pressure-reducing device 600, may be approximately 1% to 4%, preferably approximately 2% to 3%, and more preferably approximately 2%.

The evaporation gas remelting system of the present invention includes two compressors 200 and 210 installed in parallel as shown in FIG. 7, and two decompressors 600, 600 connected in parallel as shown in FIG. 8, 610)

Whether the opening ratio of the first pressure reducing device 600 or the second pressure reducing device 610 is equal to or greater than the first set value, whether the seventh valve 570 or the tenth valve 571 is open, 520 is open, and whether or not the level of the liquefied gas in the gas-liquid separator 700 is equal to or higher than the second set value, the evaporation gas is judged to be re-liquefied.

When the first compressor 200 is used, it is determined whether the seventh valve 570 is in the open state. If the second compressor 210 is used, the tenth valve 571 is in the open state Is used as a condition.

It is preferable to determine that the evaporation gas is re-liquefied when two or more conditions are satisfied in order to increase the reliability of judgment. For example, it is preferable that the opening rate of the first decompressor 600 or the second decompressor 610 Liquid separator 700 is higher than the first set value and the seventh valve 570 or the tenth valve 571 is opened and the second valve 520 is opened and the liquid level of the liquefied gas in the gas- If it is equal to or higher than the set value, it can be determined that the evaporation gas is re-liquefied and the alarm can be activated.

The first set value, which is the opening rate of the first decompressor 600 or the second decompressor 610, can be approximately 1% to 4%, preferably approximately 2% to 3%, more preferably approximately 1% 2%.

The evaporation gas re-liquefaction system of the present invention comprises two compressors 200 and 210 installed in parallel as shown in FIG. 7, and a plurality of first decompressors (not shown) installed in series as shown in FIG. 9 600) and a plurality of second decompression devices 610 installed in series are connected in parallel

Whether the opening ratio of any one of the plurality of first pressure reducing devices 600 installed in series or the plurality of second pressure reducing devices 610 installed in series is equal to or greater than the first set value, Whether or not the tenth valve 571 is open, whether the second valve 520 is open, whether the level of the liquefied gas in the gas-liquid separator 700 is equal to or higher than the second set value, It can be judged that the gas is re-liquefied.

When the first compressor 200 is used, it is determined whether the seventh valve 570 is in the open state. If the second compressor 210 is used, the tenth valve 571 is in the open state Is used as a condition.

It is preferable to determine that the evaporation gas is re-liquefied when two or more conditions are all satisfied in order to increase the reliability of the judgment. For example, it is preferable to determine that the first decompressor 600, The seventh valve 570 or the tenth valve 571 is opened and the second valve 520 is opened when the opening ratio of any one of the plurality of the second pressure reducing devices 610 installed is equal to or greater than the first set value, Liquid separator 700 is equal to or higher than the second predetermined value, it can be determined that the evaporation gas is re-liquefied and the alarm can be activated.

The first set value, which is the opening rate of the first decompressor 600 or the second decompressor 610, can be approximately 1% to 4%, preferably approximately 2% to 3%, more preferably approximately 1% 2%.

② Alarm generation phase

When the alarm is activated, an alarm is triggered when the condition that can be regarded as the point at which the lubricant should be removed is satisfied.

In the case where it is considered to be the time to remove the lubricating oil, as described above, the condition that the temperature difference of the low temperature flow is larger than that in the normal case and the state is maintained for a predetermined time or longer, And the condition that the condition lasts more than a certain period of time and the condition that the pressure difference of the high-temperature channel is higher than the normal case and the condition lasts for a predetermined time or longer is satisfied. It is preferable to judge whether or not to remove the condensed or solidified lubricating oil using at least two of "temperature difference of low-temperature flow", "temperature difference of high-temperature flow", and "pressure difference of high- .

For example, if the smaller of the temperature difference of the low temperature flow and the temperature difference of the high temperature flow is longer than the third set value for a first set time or the pressure difference of the high temperature flow path is greater than the fourth set value Or more for a predetermined time period or longer, an alarm may be generated to notify when the condensed or solidified lubricant should be removed.

The third set value may be 30 캜 to 40 캜, preferably 33 캜 to 37 캜, and more preferably 35 캜. Further, the fourth set value may be twice or more as large as the normal case, and may be 150 kPa to 250 kPa, preferably 180 kPa to 220 kPa, more preferably 200 kPa. The first set time may be one hour.

In the present invention, the performance abnormality of the heat exchanger, occurrence of an alarm, and the like can be judged by appropriate control means. As the control means for judging the performance of the heat exchanger and the occurrence of an alarm or the like, control means used in the evaporative gas remelting system of the present invention, preferably a ship to which the evaporation gas re-liquefaction system of the present invention is applied, A control means previously used in an offshore structure may be used and a separately installed control means may be used to judge the performance of the heat exchanger and alarm occurrence.

Further, utilization of the bypass line, discharge of lubricating oil, fuel supply of the engine, start-up or restart of the evaporation gas re-liquefaction system, opening and closing of various valves for these can be automatically or manually controlled by the control means.

2. Bypass line (BL)  When the pressure in the storage tank T is low and the pressure is used to satisfy the suction pressure condition of the compressor 200

When the amount of the liquefied gas in the storage tank T is small and the amount of generated gas is small or when the speed of the ship is high and the amount of evaporative gas supplied to the engine for the propulsion of the ship is large, The suction pressure condition at the front end of the compressor 200 required by the compressor 200 may not be satisfied.

Particularly, when PCHE (DCHE) is applied to the heat exchanger 100, the pressure drop of the PCHE is large when the evaporation gas discharged from the storage tank T passes through the PCHE.

The recirculation valves 541, 542, 543, and 544 are opened and the recirculation lines RC1, RC2, RC3, and RC4 open or close part or all of the evaporated gas To protect the compressor (200).

However, if the suction pressure condition of the compressor 200 is satisfied by recirculating the evaporation gas, the amount of the evaporation gas compressed by the compressor 200 is eventually decreased, so that the liquefaction performance is reduced, The required fuel consumption may not be satisfied. Particularly, if the fuel consumption amount required by the engine can not be satisfied, even if the internal pressure of the storage tank T is low, it is possible to satisfy the suction pressure condition required by the compressor 200, A method that can satisfy the fuel consumption amount required by the engine is urgently required.

According to the present invention, even when the internal pressure of the storage tank T is low, the bypass line BL, which has been installed for maintenance and repair of the heat exchanger 100, It is possible to satisfy the suction pressure condition required by the compressor 200 without reducing the amount of the evaporation gas compressed by the compressor 100. [

According to the present invention, when the internal pressure of the storage tank T becomes a certain value or less, the bypass valve 590 is opened to discharge a part or all of the evaporated gas discharged from the storage tank T through the bypass line BL (100) and directly sends it to the compressor (200).

The amount of the evaporated gas sent to the bypass line BL can be adjusted depending on how much the pressure of the storage tank T is short compared to the suction pressure condition required by the compressor 200. [ That is, the bypass valve 590 may be opened and the first valve 510 and the second valve 520 may be closed to send the entire evaporative gas discharged from the storage tank T to the bypass line BL, 590), the first valve 510 and the second valve 520 are opened partially so that only a part of the evaporated gas discharged from the storage tank T is sent to the bypass line BL and the rest is sent to the heat exchanger 100 It is possible. As the amount of the evaporating gas bypassing the heat exchanger 100 through the bypass line BL increases, the pressure drop of the evaporating gas decreases.

Although the evaporation gas discharged from the storage tank T is bypassed through the heat exchanger 100 and directly sent to the compressor 200, the pressure drop can be minimized. However, the cold heat of the evaporation gas can be used for liquefaction of the evaporation gas (BL) should be used to reduce the pressure drop in consideration of the internal pressure of the storage tank (T), the amount of fuel consumed by the engine, the amount of evaporative gas to be refluxed, T of the evaporation gas to be sent to the bypass line BL.

For example, it can be considered advantageous to reduce the pressure drop using the bypass line BL when the internal pressure of the storage tank T is less than a predetermined value and the ship is operated at a constant speed or higher. Specifically, it can be judged that it is advantageous to reduce the pressure drop using the bypass line (BL) when the pressure inside the storage tank (T) is 1.09 bar or less and the speed of the ship is 17 knots or more.

It is also possible that all the evaporated gas discharged from the storage tank T is sent to the compressor 200 through the bypass line BL but can not satisfy the suction pressure conditions required by the compressor 200. In this case, The lines (RC1, RC2, RC3, RC4) are used to satisfy suction pressure conditions.

That is, when the pressure of the storage tank T is lowered and the suction pressure condition required by the compressor 200 can not be satisfied, the compressor 200 is directly operated using the recirculation lines RC1, RC2, RC3, On the other hand, according to the present invention, the bypass line (BL) is used to primarily satisfy the suction pressure condition of the compressor (200), and all of the evaporated gas discharged from the storage tank (T) The recirculation lines RC1, RC2, RC3, and RC4 are used in the second cycle when the compressor 200 can not satisfy the suction pressure conditions required by the compressor 200.

Recirculation valves 541, 542, 543, and 544 are provided in order to match the suction pressure conditions of the compressor 200 through the second recirculation lines RC1, RC2, RC3, and RC4 after first utilizing the bypass line BL The pressure value which is a condition in which the bypass valve 590 is opened is set to be higher than the pressure value which is the open condition.

The conditions under which the recirculation valves 541, 542, 543 and 544 are opened and the condition in which the bypass valve 590 is opened are preferably used as factors in the front end pressure of the compressor 200. However, It can also be used.

The pressure at the front end of the compressor 200 may be measured by a third pressure sensor (not shown) installed at the front end of the compressor 200 and the pressure inside the storage tank T may be measured by a fourth pressure sensor .

On the other hand, the sixth supply line L6 for discharging the gaseous vaporized gas separated by the gas-liquid separator 700 is connected to the first supply line L 1 at the rear end of the branch line from the first supply line L 1 A portion of the evaporated gas discharged from the storage tank T while preventing the pressure drop to a certain degree may be used as a refrigerant in the heat exchanger 100 by using the bypass valve 590, When the system is operated with both the first valve 510 and the second valve 520 open, the gaseous vaporized gas separated by the gas-liquid separator 700 can be directly sent to the bypass line BL.

The temperature of the gaseous vaporized gas separated by the gas-liquid separator 700 is lower than the temperature of the vaporized gas discharged from the storage tank T and supplied to the heat exchanger 100, If the gaseous vaporized gas is sent directly to the bypass line BL, the cooling efficiency of the heat exchanger 100 may be reduced and at least a portion of the gaseous vaporized gas separated by the gas-liquid separator 700 may be sent to the heat exchanger 100).

However, if the amount of evaporative gas generated in the storage tank T is less than the amount of evaporative gas required as fuel in the engine, it may not be necessary to re-liquefy the evaporated gas, It is not necessary to supply the refrigerant to the heat exchanger 100. Therefore, all of the gaseous vaporized gas separated by the gas-liquid separator 700 can be sent to the bypass line BL.

Accordingly, in the present invention, the sixth supply line L6 is merged into the first supply line L1 at the point preceding the branch point of the bypass line BL from the first supply line L1. When the sixth supply line L6 is joined to the first supply line L1 at the front end of the branching point of the bypass line BL, the evaporated gas discharged from the storage tank T and the gas phase separated by the gas- Is sent to the bypass line BL and the heat exchanger 100 respectively according to the opening ratio of the bypass valve 590 and the first valve 510 after the evaporation gas of the first valve 510 is first merged at the front end of the bypass line BL It is possible to control the system easily and to prevent the evaporated gas in the gaseous state separated by the gas-liquid separator 700 from being directly sent to the bypass line BL because the flow rate of the evaporation gas is determined.

It is preferable that the bypass valve 590 is a valve having a higher reaction rate than that in the ordinary case so that opening control according to the pressure change of the storage tank T can be performed quickly.

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

The evaporation gas remelting system of the third embodiment shown in Fig. 3 differs from the evaporation gas remelting system of the first embodiment shown in Fig. 1 in that 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.

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 OL: Lubricant discharge line
NL: nitrogen supply line 100: heat exchanger
200, 210: compressor 300: oil separator
410, 420: Oil filter 550: Reverse flow prevention valve
590: Bypass valve 583: Nitrogen valve
600, 610: Pressure reducing device 620: Isolation valve
700: gas-liquid separator 910, 920: pressure sensor
930: differential pressure sensor 940: water level sensor
810, 820, 830, 840: Temperature sensor
L1, L2, L3, L4, L5, L6, L7, L8:
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, 530, 560, 570, 571, 581, 582:

Claims (20)

The evaporated gas is compressed by the first compressor, the compressed evaporated gas is cooled by heat exchange in the heat exchanger with the evaporated gas before being compressed, the fluid cooled by heat exchange is decompressed by the first decompressor, A method of discharging a lubricating oil in a system,
1) an alarm activation step; And
2) generating the alarm;
Wherein the first compressor includes at least one oil-feeding cylinder,
And whether or not to remove condensed or solidified lubricating oil is determined by the alarm. The method according to claim 1,
In the step 1), the alarm is activated when the system re-liquefies the evaporation gas. The method of claim 2,
Wherein the system determines that the evaporating gas is re-liquefied when the opening ratio of the first decompressor is equal to or larger than the first set value in the step (1). The method of claim 2,
A second pressure reducing device is provided in parallel with the first pressure reducing device,
Wherein the system determines that the evaporating gas is re-liquefied when the opening rate of the first decompressor or the second decompressor is equal to or larger than the first set value in the step (1). The method of claim 2,
Wherein a plurality of the first decompression devices are installed in series,
A plurality of second pressure reducing devices are installed in series,
A plurality of second decompression devices installed in series with a plurality of the first decompression devices installed in series are connected in parallel,
In the step 1), when the opening ratio of any one of the plurality of first decompression devices or the plurality of second decompression devices is equal to or larger than the first set value, the system determines that the evaporation gas is re-liquefied , Lubricating oil discharge method. The method of claim 2,
Wherein a part or all of the evaporated gas compressed by the first compressor is used as fuel for the engine and the excess evaporated gas not used as the fuel of the engine is re-liquefied. The method of claim 6,
A seventh valve is installed on a line for supplying surplus evaporated gas not used as fuel of the engine among the evaporated gases compressed by the first compressor to the heat exchanger,
Wherein in the step (l), the system determines that the evaporating gas is re-liquefied when the seventh valve is in the open state. The method of claim 7,
A second compressor is installed in parallel with the first compressor,
Part or all of the evaporated gas compressed by the second compressor is used as the fuel of the engine, the excess evaporative gas not used as the fuel of the engine is re-liquefied,
A tenth valve is provided on a line for sending excess evaporative gas not used as fuel of the engine among the evaporated gases compressed by the second compressor to the heat exchanger,
Wherein in the step (1), when the seventh valve or the tenth valve is in the open state, the system determines that the evaporating gas is res liquefying. The method of claim 2,
A gas-liquid separator is provided at the downstream end of the first decompression device to separate the liquefied gas re-liquefied by the gas-liquid separator and the evaporated gas remaining in a gaseous state,
Wherein in the step (1), when the level of the liquefied gas in the gas-liquid separator is equal to or higher than a second set value, the system determines that the evaporating gas is re-liquefied. The method according to any one of claims 3 to 5, and claims 7 to 9,
A second valve is installed on a line through which the evaporation gas used as a refrigerant is discharged in the heat exchanger,
Wherein in the step (l), the system determines that the evaporating gas is re-liquefied if the second valve further satisfies the condition of the open state. The method according to any one of claims 1 to 9,
In the step 2)
The temperature difference of the low-temperature flow of the heat exchanger is greater than that of the normal case, and the condition is maintained for a predetermined time or longer;
The temperature difference of the high-temperature flow of the heat exchanger is larger than that of the normal case and the condition is maintained for a predetermined time or longer; And
The pressure difference of the high-temperature flow path of the heat exchanger is larger than that of the normal case and the condition is maintained for a predetermined time or more;
Wherein the alarm is generated when at least one of the following conditions is satisfied. The method of claim 11,
In the step 2)
The temperature difference between the 'low temperature flow' of the heat exchanger and the 'temperature difference of the high temperature flow' of the heat exchanger is greater than or equal to the third set value and continues for a first set time or longer, 'Is greater than or equal to a fourth set value and is maintained for a first predetermined time or more, the alarm is generated. A first compressor for compressing the evaporation gas;
A heat exchanger that cools the evaporated gas compressed by the first compressor by heat exchange using the evaporated gas before being compressed by the first compressor as a refrigerant;
A first decompressor installed downstream of the heat exchanger for decompressing the fluid cooled by the heat exchanger; And
And a second decompression device disposed downstream of the heat exchanger for decompressing the fluid cooled by the heat exchanger,
Wherein the first decompressor and the second decompressor are provided in parallel,
Wherein the first compressor comprises at least one oil-feeding cylinder. 14. The method of claim 13,
Wherein a plurality of the first decompression devices are installed in series,
Wherein a plurality of the second decompression devices are installed in series. The method according to claim 13 or 14,
An isolation valve is provided at the front end and the rear end of the first decompression device,
And an isolation valve is provided at the front end and the rear end of the second decompression device, respectively. The method according to claim 13 or 14,
Further comprising a second compressor installed in parallel with the first compressor. A fuel supply method for an engine in which an evaporation gas is used as fuel in an engine and a surplus evaporation gas is re-
Supplying the engine with fuel even while melting or condensing or losing the coagulated lubricating oil,
And whether or not to remove condensed or solidified lubricating oil is detected by an alarm. 18. The method of claim 17,
1) activating the alarm; And
2) generating the alarm. 19. The method of claim 18,
In the step 1), the alarm is activated when the evaporation gas is re-liquefied. The method according to claim 18 or 19,
In the step 2)
The condition that the temperature difference of the low-temperature flow of the heat exchanger is larger than that of the normal case and the state is maintained for a predetermined time or longer;
The temperature difference of the high-temperature flow of the heat exchanger is larger than that of the normal case and the condition is maintained for a predetermined time or longer; And
The pressure difference of the high-temperature flow path of the heat exchanger is larger than that of the normal case and the condition is maintained for a predetermined time or more;
Wherein the alarm is generated when at least one of the at least two alarms is satisfied.

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