KR102190950B1 - treatment system for gas and vessel having the same - Google Patents

Abstract

The present invention relates to a gas processing system and a ship including the same, wherein the gas processing system includes a low-pressure compression unit provided in parallel with three or more stages of cryogenic compressors for compressing boil-off gas of a liquefied gas storage tank; A high-pressure compression unit provided with a four-stage or more room temperature compressor for supplying the boil-off gas pressurized by the cryogenic compressor to a high-pressure consumer; And the boil-off gas discharged from the low-pressure compression unit joins the boil-off gas supplied to the low-pressure compression unit when the boil-off gas pressure at the rear end of the low-pressure compression unit is higher than a certain pressure, provided between the low-pressure compression unit and the high-pressure compression unit. It characterized in that it comprises an overpressure valve to let.

Description

Gas treatment system and vessel including the same {treatment system for gas and vessel having the same}

The present invention relates to a gas treatment system and a ship including the same.

According to recent technological developments, liquefied gases such as Liquefied Natural Gas and Liquefied Petroleum Gas have been widely used in place of gasoline or diesel.

Liquefied natural gas is liquefied by cooling methane obtained by refining natural gas collected from a gas field. It is a colorless and transparent liquid that contains almost no pollutants and has a high calorific value. Liquefied petroleum gas, on the other hand, is a fuel made into a liquid by compressing gas containing propane (C3H8) and butane (C4H10) as main components from oil fields together with oil at room temperature. Liquefied petroleum gas, like liquefied natural gas, is colorless and odorless, and is widely used as fuel for home, business, industrial and automobiles.

Such liquefied gas is stored in a liquefied gas storage tank installed on the ground or in a liquefied gas storage tank provided on a ship, which is a transportation means for sailing the ocean, and liquefied natural gas is stored in a volume of 1/600 by liquefaction. The volume of liquefied petroleum gas is reduced to 1/260 of propane and 1/230 of butane by liquefaction, which has the advantage of high storage efficiency.

Such liquefied gas is supplied and used to various consumers. Recently, an LNG fuel supply method in which an engine is driven by using LNG as fuel in an LNG carrier carrying liquefied natural gas has been developed. The method used is also applied to other ships other than LNG carriers.

However, the temperature and pressure of the liquefied gas required by a consumer such as an engine may be different from the state of the liquefied gas stored in the liquefied gas storage tank. Therefore, in recent years, continuous research and development has been made on a technology that controls the temperature and pressure of the liquefied gas stored in a liquid state and supplies it to a customer.

The present invention has been created to solve the problems of the prior art as described above, and an object of the present invention is to provide a gas treatment system capable of efficiently supplying gas to a customer in accordance with the pressure required by the customer, and a ship including the same. For.

A gas treatment system according to an embodiment of the present invention includes a low pressure compression unit provided in parallel with three or more stages of cryogenic compressors for compressing boil-off gas of a liquefied gas storage tank; A high-pressure compression unit provided with a four-stage or more room temperature compressor for supplying the boil-off gas pressurized by the cryogenic compressor to a high-pressure consumer; And the boil-off gas discharged from the low-pressure compression unit joins the boil-off gas supplied to the low-pressure compression unit when the boil-off gas pressure at the rear end of the low-pressure compression unit is higher than a certain pressure, provided between the low-pressure compression unit and the high-pressure compression unit. It characterized in that it comprises an overpressure valve to let.

Specifically, the gas treatment system may further include a reliquefaction unit for liquefying at least some of the boil-off gas discharged from the low-pressure compression unit and delivered to the high-pressure compression unit using a refrigerant, and delivering it to the liquefied gas storage tank. have.

Specifically, at least some of the boil-off gas discharged from the low-pressure compression unit and delivered to the high-pressure compression unit is supplied to a low-pressure consumer, and the low-pressure consumer includes at least one of a power generation engine and a gas combustion device (GCU), and the The pressure of the boil-off gas between the low pressure compression unit and the high pressure compression unit may be adjusted to 6 to 7 bar.

Specifically, the gas treatment system includes: a forced vaporizer for vaporizing liquefied gas in the liquefied gas storage tank; A gas-liquid separator that receives the liquefied gas vaporized from the forced vaporizer and separates it into a gas phase and a liquid phase; And a heater that heats the gaseous liquefied gas separated by the gas-liquid separator and supplies it to a low pressure consumer.

Specifically, the low pressure compression unit, a cooler for cooling the boil-off gas discharged from the cryogenic compressor; And an anti-surge valve provided between the cryogenic compressor and the cooler and configured to join the boil-off gas discharged from the cryogenic compressor to the boil-off gas supplied to the low-pressure compression unit when a surge phenomenon occurs in the cryogenic compressor. Can include.

Specifically, the high pressure compression unit, a recovery valve for recovering the boil-off gas discharged from the high pressure compression unit to the high pressure compression unit; And a downstream pressure control module provided at a rear end of the high pressure compression unit and controlling opening/closing of the recovery valve so that the pressure of the boil-off gas discharged from the high pressure compression unit is maintained at a pressure required by the high pressure consumer.

Specifically, the high-pressure compression unit is provided at a front end of the high-pressure compression unit, and when the pressure of the boil-off gas at the front end of the high-pressure compression unit is less than a certain pressure, the recovery valve is opened to compress the boil-off gas discharged from the high-pressure compression unit. It may further include an upstream pressure control module to recover as a negative.

Specifically, the cryogenic compressor may be a centrifugal compressor, and the room temperature compressor may be a reciprocating compressor.

Specifically, the gas treatment system includes: a liquefied gas pump for compressing and delivering liquefied gas in the liquefied gas storage tank; And a liquefied gas vaporizer that vaporizes the liquefied gas discharged from the liquefied gas pump to supply the vaporized liquefied gas to the high pressure consumer.

A ship according to an embodiment of the present invention is characterized in that it includes the gas treatment system.

The gas treatment system according to the present invention can effectively supply the boil-off gas to the high-pressure consumer and the low-pressure consumer by controlling the pressure of the boil-off gas at a pressure required by each of the high-pressure consumer and the low-pressure consumer.

In the gas treatment system according to the present invention, by providing a cryogenic compressor in parallel to the low pressure compression unit, the backup and load of the cryogenic compressor can be shared.

In the gas treatment system according to the present invention, since the low pressure compression unit and the high pressure compression unit can be separately controlled, the boil-off gas can be smoothly supplied to various demanders having different pressures.

1 is a conceptual diagram of a gas treatment system according to a first embodiment of the present invention.
2 is a conceptual diagram of a gas treatment system according to a fourth embodiment of the present invention.
3 is a conceptual diagram of a gas treatment system according to a fifth embodiment of the present invention.
4 is a conceptual diagram of a gas treatment system according to a sixth embodiment of the present invention.
5 is a conceptual diagram of a gas treatment system according to a seventh embodiment of the present invention.
6 is a conceptual diagram of a gas treatment system according to an eighth embodiment of the present invention.

Objects, specific advantages and novel features of the present invention will become more apparent from the following detailed description and preferred embodiments associated with the accompanying drawings. In adding reference numerals to elements of each drawing in the present specification, it should be noted that, even though they are indicated on different drawings, only the same elements are to have the same number as possible. In addition, in describing the present invention, when it is determined that a detailed description of related known technologies may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

Hereinafter, it should be noted that high pressure (HP) and low pressure (LP) are relative and do not represent absolute values.

In the following, liquefied gas may be used in the sense of encompassing all gaseous fuels generally stored in a liquid state, such as LNG or LPG, ethylene, ammonia, etc., and when not in a liquid state by heating or pressurization, it is also expressed as liquefied gas for convenience. I can. This can also be applied to boil-off gas. In addition, for convenience, LNG can be used to mean not only NG (Natural Gas) in liquid state, but also NG in supercritical state, etc., and evaporation gas can be used to mean not only gaseous evaporation gas but also liquefied evaporation gas. have.

Hereinafter, a gas treatment system of the present invention will be described, and the present invention includes a gas treatment system and a ship having the same. In this case, it should be noted that the ship may be a general merchant ship that loads cargo other than liquefied gas in addition to a liquefied gas carrier, and furthermore, it is an expression that encompasses all offshore structures such as FSRU and FLNG, which are not commercial ships.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Hereinafter, the gas treatment system of the present invention will be described in detail with reference to FIGS. 1 to 6.

1 is a conceptual diagram of a gas treatment system 1 according to a first embodiment of the present invention.

Referring to FIG. 1, a gas treatment system 1 according to a first embodiment of the present invention includes a liquefied gas storage tank 10, a low pressure compression unit 20, a high pressure compression unit 30, and a precooler 52. , And a boil-off gas gas-liquid separator 51.

The liquefied gas storage tank 10 stores liquefied gas to be supplied to the low pressure consumer 200 and the high pressure consumer 100. At this time, the liquefied gas storage tank 10 may store liquefied gas in a liquid state and may have a pressure tank shape.

A pump 11 may be provided in the liquefied gas storage tank 10, and the liquefied gas stored in the liquefied gas storage tank 10 may be extracted through the pump 11. The pump 11 may be provided to be immersed in the liquefied gas stored in the liquefied gas storage tank 10 or may be provided outside the liquefied gas storage tank 10.

The low-pressure compression unit 20 may pressurize the boil-off gas generated in the liquefied gas storage tank 10 to a first pressure that is a pressure required by the low-pressure consumer 200 and supply it to the low-pressure consumer 200. By utilizing the boil-off gas generated in the liquefied gas storage tank 10 as fuel for the low-pressure consumer 200, the boil-off gas can be efficiently used.

The low pressure compression unit 20 includes a cryogenic compressor 21 for pressurizing the boil-off gas of the liquefied gas storage tank 10 to a first pressure. The cryogenic compressor 21 can effectively compress the boil-off gas discharged from the liquefied gas storage tank 10 in a low-temperature state of about -100 degrees Celsius.

The cryogenic compressor 21 may be provided in multiple stages, and specifically, may be provided in two stages. By providing the two-stage cryogenic compressor 21, it may be easy to pressurize the cryogenic boil-off gas discharged from the liquefied gas storage tank 10 to the required pressure of the low-pressure consumer 200.

Two-stage cryogenic compressors 21 may be provided in parallel in the low pressure compression unit 20. Since the cryogenic compressors 21 are provided in parallel, the other cryogenic compressor 21 can perform backup when a failure occurs in one cryogenic compressor 21. In addition, the cryogenic compressors 21 are provided in parallel to share the load of the cryogenic compressor 21, so that the stability and durability of the gas treatment system 1 can be further improved.

Here, the cryogenic compressor 21 may be a centrifugal type compressor. Centrifugal compressors do not have a labyrinth ring, so they are inexpensive and have an effect of preventing vibration during low-load motion.

The low pressure compression unit 20 may include a pressure control module 42 that controls the operation of the cryogenic compressor 21. For example, the pressure control module 42 is interlocked with the variable diffuser vane 211 of the cryogenic compressor 21, so that the pressure of the boil-off gas discharged from the low-pressure compression unit 20 is reduced to the low-pressure consumer 200 It is possible to control the driving of the variable diffuser vane 211 to be maintained at the required pressure of ). Through this, the pressure of the boil-off gas between the low pressure compression unit 20 and the high pressure compression unit 30 can be easily adjusted to the required pressure of the low pressure customer 200.

At this time, the pressure control module 42 may be interlocked with the pressure measurement sensor 61 to control the driving of the low pressure compression unit 20 according to the measured value of the pressure measurement sensor 61.

The pressure of the boil-off gas between the low pressure compression unit 20 and the high pressure compression unit 30 may be adjusted to the required pressure of the low pressure customer 200. Specifically, the pressure of the boil-off gas between the low pressure compression unit 20 and the high pressure compression unit 30 may be adjusted to 6 to 7 bar, which is the required pressure of the low pressure customer 200. More specifically, the pressure of the boil-off gas between the low pressure compression unit 20 and the high pressure compression unit 30 may be adjusted to 6.5 bar.

The low pressure consumer 200 may include at least one of a power generation engine 210, a gas combustion device (GCU, 220), and a reliquefaction unit 230. That is, some of the boil-off gas discharged from the low-pressure compression unit 20 and delivered to the high-pressure compression unit 30 is in a state in which the pressure is adjusted to 6 to 7 bar, and the power generation engine 210, the gas combustion device (GCU, 220) ), and may be delivered to the reliquefaction unit 230.

By adjusting the pressure of the boil-off gas between the low pressure compression unit 20 and the high pressure compression unit 30 to 6 to 7 bar, the power generation engine 210, the gas combustion device (GCU, 220), and the reliquefaction unit 230 Driving efficiency can be improved.

The re-liquefied unit 230 may receive at least a portion of the boil-off gas discharged from the low-pressure compression unit 20 and delivered to the high-pressure compression unit 30, liquefy through a refrigerant, and then transfer it to the liquefied gas storage tank 10. . The re-liquefier 230 may include a re-liquefier 231 and a refrigerant circulation line (not shown), and the re-liquefier 231 has a flow path through which the boil-off gas delivered from the low-pressure compression unit 20 flows and a refrigerant circulation line. A flow path through which the circulating refrigerant flows may be provided. The refrigerant circulation line controls various types of refrigerants in the order of compression, condensation, expansion, and evaporation, and when the refrigerant is evaporated in the reliquefier 231, the boil-off gas may be liquefied.

The room temperature compressor 35 used in the high pressure compression unit 30 uses lubricating oil, and there may be a problem that the lubricating oil is mixed into the boil-off gas compressed by the room temperature compressor 35. However, in this embodiment, by supplying some of the boil-off gas delivered from the low-pressure compression unit 20 to the high-pressure compression unit 30 to the low-pressure consumer 200, the lubricant is mixed in the boil-off gas supplied to the low-pressure consumer 200 You can avoid the problem.

The low pressure compression unit 20 may include a cooler 22 that cools the boil-off gas discharged from the cryogenic compressor 21. In FIG. 1, a cooler 22 is provided downstream of the two-stage cryogenic compressor 21, but an additional cooler (not shown) may be provided between the cryogenic compressors 21.

Even when a two-stage cryogenic compressor 21 is provided in the low-pressure compression unit 20, a precooler 52 to be described later is provided upstream of the low-pressure compression unit 20 and discharged from the cryogenic compressor 21 of the second stage. It is possible to easily adjust the pressure of the boil-off gas to be the required pressure of the low pressure customer 200.

That is, the gas treatment system 1 according to the present embodiment can pressurize the boil-off gas at the required pressure of the low-pressure consumer 200 by providing a two-stage cryogenic compressor 21 in the low-pressure compression unit 20, CAPEX and OPEX can be optimized, and stable operation of the system can be secured.

The low pressure compression unit 20 may include an anti-surge valve 23 for recovering from a surge phenomenon by recirculating the boil-off gas pressure when a surge occurs in the cryogenic compressor 21 to maintain a normal pressure. The anti-surge valve 23 may be provided between the cryogenic compressor 21 and the cooler 22, and when a surge occurs in the cryogenic compressor 21, the boil-off gas discharged from the cryogenic compressor 21 is reduced to a low pressure. It can be joined to the boil-off gas supplied to the compression unit 20.

In this case, the boil-off gas recovered through the anti-surge valve 23 may be joined upstream of the boil-off gas-liquid separator 51 to be described later. Specifically, the boil-off gas discharged from the cryogenic compressor 21 may be joined with the boil-off gas upstream of the pre-cooler 52 through the anti-surge valve 23.

The high-pressure compression unit 30 pressurizes the boil-off gas pressurized by the low-pressure compression unit 20 to a second pressure higher than the first pressure, and supplies it to the high-pressure consumer 100. The high-pressure consumer 100 may be a ME-GI engine or a 2sDf engine, and the second pressure, which is the pressure of the boil-off gas required by the high-pressure consumer 100, may be 200 to 400 bar.

The high pressure compression unit 30 includes a room temperature compressor 35 for pressurizing the boil-off gas to a second pressure. The temperature of the boil-off gas pressurized by the low-pressure compression unit 20 increases, so that a room temperature compressor 35 may be used for the high-pressure compression unit 30. The room temperature compressor 35 may be provided in multiple stages, and specifically, it may be provided in 4 stages or more or 5 stages or more.

Here, the room temperature compressor 35 may be a reciprocating type compressor. The reciprocating compressor can pressurize to a second pressure, that is, 200 to 400 bar, and can pressurize according to the pressure required by the high pressure consumer 100. In addition, a cooler (not shown) may be provided between each end of the room temperature compressor 35.

The high pressure compression unit 30 may include a recovery valve 31 for recovering the boil-off gas discharged from the high pressure compression unit 30 upstream of the high pressure compression unit 30. The downstream pressure control module 32 is interlocked with the recovery valve 31 to open and close the recovery valve 31 so that the pressure of the boil-off gas discharged from the high-pressure compression unit 30 is maintained at the required pressure of the high-pressure consumer 100. Can be adjusted.

That is, the downstream pressure control module 32 may control the recovery valve 31 so that the boil-off gas supplied to the high-pressure consumer 100 is constantly maintained at the second pressure. The downstream pressure control module 32 is interlocked with the pressure measurement sensor 63 and can control the opening and closing of the recovery valve 31 according to the measured value of the pressure measurement sensor 63.

In addition, the high pressure compression unit 30 may include an upstream pressure control module 33. When the pressure of the boil-off gas at the front end of the high-pressure compression unit 30 is less than a certain pressure, the upstream pressure control module 33 opens the recovery valve 31 to reduce the boil-off gas discharged from the high-pressure compression unit 30 to the high-pressure compression unit 30 ) Can be recovered.

The pressure of the boil-off gas upstream of the high-pressure compression unit 30 may decrease by changing the load of the high-pressure compression unit 30. At this time, the upstream pressure control module 33 opens the recovery valve 31 when the pressure of the boil-off gas measured through the pressure measurement sensor 64 falls below a certain pressure, and the boil-off gas discharged from the high-pressure compression unit 30 Can be recovered upstream of the high pressure compression unit 30. By adjusting the pressure of the boil-off gas upstream of the high-pressure compression unit 30, the pressure of the boil-off gas discharged from the high-pressure compression unit 30 can be effectively controlled as the second pressure.

The control selection module 34 is interlocked with the downstream pressure control module 32 and the upstream pressure control module 33, and compares the pressure of the boil-off gas in the upstream of the high-pressure compression unit 30 and the pressure of the boil-off gas in the downstream. First of all, you can select the part to control the pressure. Through this, it is possible to efficiently control the pressure of the boil-off gas supplied to the high-pressure consumer 100.

The gas treatment system 1 includes a boil-off gas gas-liquid separator 51 provided upstream of the low-pressure compression unit 20. At this time, the boil-off gas gas-liquid separator 51 may be referred to as a mist separator.

The boil-off gas gas-liquid separator 51 temporarily stores boil-off gas from the liquefied gas storage tank 10 to separate it into a liquid and a gas. The boil-off gas-liquid separator 51 allows only pure gas from the supplied boil-off gas to be supplied to the cryogenic compressor 21 of the low pressure compression unit 20 and the room temperature compressor 35 of the high pressure compression unit 30, It is possible to increase the elasticity of the fuel supply to the consumer 200 and the high pressure consumer 100.

The low pressure compression unit 20 may include a two-stage cryogenic compressor 21, and at this time, a precooler 52 may be provided upstream of the boil-off gas gas-liquid separator 51. The precooler 52 may receive liquefied gas from the liquefied gas storage tank 10 and precool the boil-off gas supplied to the precooler 52.

The temperature of the boil-off gas discharged from the liquefied gas storage tank 10 may increase during the process of being transferred to the boil-off gas gas-liquid separator 51. At this time, the precooler 52 pre-cools the boil-off gas delivered to the boil-off gas gas-liquid separator 51 by using the liquefied gas of the liquefied gas storage tank 10, so that the temperature of the boil-off gas delivered to the cryogenic compressor 21 And pressure can be kept constant. Through this, the pressure of the boil-off gas discharged from the cryogenic compressor 21 can be more stably adjusted to the required pressure of the low-pressure consumer 200.

The gas treatment system 1 may include a liquefied gas pump 71 and a liquefied gas vaporizer 72.

The liquefied gas pump 71 is for supplying the liquefied gas in the liquefied gas storage tank 10 to the high-pressure consumer 100 by pressurizing it, and may be a reciprocating or centrifugal pump, and may be a boosting pump.

The liquefied gas vaporizer 72 may vaporize the liquefied gas discharged and pressurized by the liquefied gas pump 71 to be supplied to the high-pressure consumer 100 in the state of a boil-off gas.

The liquefied gas vaporizer 72 heats the liquefied gas by exchanging the liquefied gas with the heat medium and cools the heat medium, and the heated liquefied gas may be changed into a boil-off gas as it has a high temperature.

The gas processing system 1 includes a main boil-off gas supply line L100 and an auxiliary boil-off gas supply line L200.

The main boil-off gas supply line L100 may include a low pressure compression section and a high pressure compression section, a low pressure compression section 20 is provided in the low pressure compression section, and a high pressure compression section 30 may be provided in the high pressure compression section.

The low pressure compression section includes a pressurization section and a cooling section, and a two-stage cryogenic compressor 21 may be provided in the pressurization section, and the cooling section may be provided downstream of the pressurization section and a cooler 22 may be provided. .

A pressure control section is provided between the low pressure compression section and the high pressure compression section on the main boil-off gas supply line (L100), and the pressure of the boil-off gas in the pressure control section is adjusted to the required pressure of the low pressure consumer 200, that is, 6 to 7 bar. Can be.

The auxiliary boil-off gas supply line (L200) is branched from the pressure control section on the main boil-off gas supply line (L100) and is connected to the low-pressure consumer 200, and the boil-off gas adjusted to the required pressure of the low-pressure consumer 200 in the pressure control section. It can be supplied to the low pressure consumer 200.

The gas treatment system 1 may include a boil-off gas reliquefaction line L210. The boil-off gas re-liquefaction line (L210) is branched from the pressure control section on the main boil-off gas supply line (L100) and is connected to the liquefied gas storage tank (10), and the boil-off gas re-liquefaction line (L210) includes a re-liquefaction unit (230). Can be provided. The boil-off gas whose pressure is adjusted to 6 to 7 bar in the pressure control section is liquefied through the boil-off gas re-liquefaction line (L210), and the liquefied boil-off gas is transferred to the liquefied gas storage tank (10). Can be recovered.

The gas treatment system 1 may include an anti-surge line L110 branched between the pressurization section and the cooling section and connected upstream of the gas-liquid separation section to be described later. An anti-surge valve 23 is provided in the anti-surge line L110, and when a surge occurs in the pressurization section, the boil-off gas downstream of the pressurization section may be recovered as the boil-off gas upstream of the gas-liquid separation section.

The gas treatment system 1 may include a boil-off gas recovery line L130 for returning the boil-off gas discharged from the high-pressure compression section upstream of the high-pressure compression section. In the high-pressure compression section, a four-stage or more room temperature compressor 35 may be provided, and a recovery valve 31 may be provided in the boil-off gas recovery line L130. In order to maintain the pressure of the boil-off gas discharged from the high-pressure compression section at the required pressure of the high-pressure consumer 100, the boil-off gas can be recovered from the downstream of the high-pressure compression section to the upstream of the high-pressure compression section.

The main boil-off gas supply line L100 may include a gas-liquid separation section, and a boil-off gas gas-liquid separator 51 may be provided in the gas-liquid separation section. In the gas-liquid separation section, the gas phase is separated from the boil-off gas of the liquefied gas storage tank 10, and can be transferred to the low pressure compression section.

The gas treatment system 1 may include a liquefied gas transfer line L310 connected from the liquefied gas storage tank 10 upstream of the gas-liquid separation section. Specifically, the liquefied gas transfer line L310 may be connected from the liquefied gas storage tank 10 to the precooler 52 provided on the main boil-off gas supply line L100.

The precooler 52 may be provided upstream of the gas-liquid separation section, and the boil-off gas precooled by the liquefied gas transferred to the liquefied gas transfer line L310 may be supplied to the gas-liquid separation section.

The gas treatment system 1 includes a main liquefied gas supply line L300, and a liquefied gas pump 71 and a liquefied gas vaporizer 72 may be provided in the main liquefied gas supply line L300. The main liquefied gas supply line (L300) is connected from the liquefied gas storage tank 10 to the high-pressure consumer 100, and the liquefied gas in the liquefied gas storage tank 10 is compressed and vaporized to be supplied to the high-pressure consumer 100. have.

As described above, in this embodiment, by providing the two-stage cryogenic compressors 21 in parallel in the low pressure compression unit 20, the backup and load of the cryogenic compressor 21 can be shared, and the gas processing system 1 ) CAPEX and OPEX can be optimized, and lubricating oil is mixed in the low pressure compression unit 20 by delivering the boil-off gas pressurized in the low pressure compression unit 20 to the low pressure compression unit 20 such as the reliquefaction unit 230. It is possible to prevent the boil-off gas from flowing into the low-pressure compression unit 20.

The gas treatment system 1 according to the second embodiment of the present invention includes a liquefied gas storage tank 10, a low pressure compression unit 20, a high pressure compression unit 30, and a forced vaporizer 81a.

Hereinafter, the description will be made mainly on points that the present embodiment is different from the previous embodiment, and portions omitted from the description will be replaced with the previous contents. It should be noted that this is the same for the embodiments described below.

The forcing vaporizer 81a may receive the liquefied gas from the liquefied gas storage tank 10 and vaporize it into a boil-off gas. The forced vaporizer 81a receives the liquefied gas from the liquefied gas storage tank 10, vaporizes it, and supplies it to the low pressure compression unit 20, so that the flow rate of the boil-off gas supplied to the low pressure consumer 200 and the high pressure consumer 100 Can increase.

By controlling the flow rate of the boil-off gas delivered to the low-pressure compression unit 20 and the high-pressure compression unit 30 using a forced vaporizer 81a, the gas treatment system 1 is a ship in a Laden condition or ballast. Even when operated in a ballast condition, it can be driven flexibly.

The gas treatment system may further include a precooler and a gas-liquid separator provided downstream of the forced vaporizer. The liquefied gas vaporized in the forced vaporizer and the boil-off gas of the liquefied gas storage tank are delivered to the precooler, and can be cooled through the liquefied gas received from the liquefied gas storage tank in the precooler. The boil-off gas pre-cooled in the pre-cooler is transferred to a gas-liquid separator, and the gas-liquid separator separates the gas phase and the liquid phase and transfers the vaporized gas to the low-pressure compression unit.

The gas treatment system 1 may include a liquefied gas forced vaporization line L320 connecting the liquefied gas storage tank 10 and the main boil-off gas supply line L100. A forced vaporizer 81a may be provided in the liquefied gas forced vaporization line L320, and the liquefied gas in the liquefied gas storage tank 10 may be vaporized and supplied to the precooler 52.

As described above, this embodiment controls the flow rate of the boil-off gas delivered to the low-pressure compression unit and the high-pressure compression unit by forcibly vaporizing the liquefied gas in the liquefied gas storage tank by using a forced vaporizer. It can be driven flexibly.

The gas treatment system 1 according to the third embodiment of the present invention includes a liquefied gas storage tank 10, a low pressure compression unit 20, a high pressure compression unit 30, a precooler 52, a boil-off gas gas-liquid separator ( 51), and an overpressure valve 41. The gas treatment system 1 according to the third embodiment of the present invention may further include an overpressure valve 41 compared to the first embodiment.

The gas treatment system 1 is provided between the low pressure compression unit 20 and the high pressure compression unit 30, and supplies boil-off gas discharged from the low-pressure compression unit 20 to the boil-off gas supplied to the low-pressure compression unit 20. It includes an overpressure valve 41 to merge.

When the pressure of the boil-off gas at the rear end of the low-pressure compression unit 20 is higher than a certain pressure, the overpressure valve 41 is opened so that the boil-off gas discharged from the low-pressure compression unit 20 can be joined upstream of the boil-off gas-liquid separator 51. have. Specifically, the boil-off gas discharged from the low-pressure compression unit 20 may be joined with the boil-off gas upstream of the precooler 52 through the overpressure valve 41.

When the pressure of the boil-off gas downstream of the low-pressure compression portion 20 rapidly rises due to a change in conditions at the high-pressure compression unit 30 and the low-pressure consumer 200, the boil-off gas downstream of the low-pressure compression unit 20 is overpressure valve ( By recovering upstream of the low pressure compression unit 20 through 41), the pressure of the boil-off gas discharged from the low pressure compression unit 20 can be controlled, and the cryogenic compressor 21 of the low pressure compression unit 20 can be effectively protected. have.

Opening and closing of the overpressure valve 41 may be controlled through the pressure control module 43. The pressure control module 43 is interlocked with the pressure measurement sensor 62 to control the opening and closing of the overpressure valve 41 according to the measured value of the pressure measurement sensor 62.

In addition, when the low pressure compression unit 20 is initially driven (start-up), the anti-surge valve 23 is closed and the opening degree of the overpressure valve 41 is adjusted, so that the low pressure compression unit 20 can be initially driven. have.

The gas treatment system 1 may include an overpressure prevention line L120 branched from a downstream of the low pressure compression section and connected to an upstream of the low pressure compression section. An overpressure valve 41 is provided in the overpressure prevention line L120, and if the pressure of the boil-off gas downstream of the low-pressure compression section is higher than a predetermined pressure, the boil-off gas may be recovered from the downstream of the low-pressure compression section to the upstream of the low-pressure compression section.

As described above, in this embodiment, by providing an overpressure valve 41 between the low pressure compression unit 20 and the high pressure compression unit 30, the pressure of the boil-off gas discharged from the low pressure compression unit 20 is kept constant. Stable driving of the processing system 1 can be ensured.

2 is a conceptual diagram of a gas treatment system 1 according to a fourth embodiment of the present invention. Specifically, FIG. 2 is a conceptual diagram for re-liquefying the boil-off gas of the gas treatment system 1 according to the fourth embodiment of the present invention.

Referring to FIG. 2, a gas treatment system 1 according to a fourth embodiment of the present invention includes a liquefied gas storage tank 10, a low pressure compression unit 20, a high pressure compression unit 30, and a boil-off gas heat exchanger ( 90), a pressure reducing valve 91, and a liquefied gas gas-liquid separator 92. For reference, the valve indicated in black in FIG. 2 indicates that it is closed.

The boil-off gas compressed by the high-pressure compression unit 30 is delivered to the high-pressure consumer 100. At this time, there may be an excess amount of evaporated gas that cannot be consumed by the high-pressure consumer 100, and the excess amount of evaporative gas may be liquefied and returned to the liquefied gas storage tank 10. To this end, the boil-off gas re-liquefaction line L210' may be branched from the downstream of the high-pressure compression unit 30 of the main boil-off gas supply line L100 to be connected to the liquefied gas storage tank 10.

The boil-off gas flow from the main boil-off gas supply line (L100) to the boil-off gas re-liquefaction line (L210') can be controlled by the high-pressure boil-off gas recovery valve (97) provided in the boil-off gas re-liquefaction line (L210'). have.

The boil-off gas heat exchanger 90 is provided in the boil-off gas re-liquefaction line (L210'), and the boil-off gas heat exchanger 90 is boiled gas pressurized by the room temperature compressor 35 of 4 or more stages of the high-pressure compression unit 30. And the boil-off gas flowing into the low-pressure compression unit 20 is heat-exchanged.

The boil-off gas re-liquefaction line (L210') is branched from the downstream of the high-pressure compression unit 30 in the main boil-off gas supply line (L100) and is connected to the liquefied gas storage tank 10 via the boil-off gas heat exchanger (90). I can. In addition, the main boil-off gas supply line (L100) is also connected from the liquefied gas storage tank 10 to the high-pressure consumer 100 via the boil-off gas heat exchanger 90, the low-pressure compression unit 20, and the high-pressure compression unit 30 in sequence. I can.

Therefore, the boil-off gas heat exchanger 90 is parallel to the main boil-off gas supply line L100, a flow path through which the low-pressure/low-temperature boil-off gas flows (not shown), and the boil-off gas re-liquefaction line (L210'). A flow path through which high-pressure/high-temperature evaporative gas flows (not shown) may be provided, and further, a low-pressure/low-temperature evaporative evaporative gas (flash gas, flash gas) parallel to the vapor phase evaporative gas delivery line (L230) to be described later A flow path (not shown) may be provided.

The boil-off gas heat exchanger (90) is compressed by the room temperature compressor (35) for four or more stages of the high-pressure compression unit (30), and then flows through the boil-off gas re-liquefaction line (L210'). It can be cooled with low-temperature evaporative gas discharged from the storage tank 10.

Since the boil-off gas flowing along the boil-off gas re-liquefaction line L210' needs to be returned to the liquefied gas storage tank 10 after liquefaction, the boil-off gas heat exchanger 90 may perform precooling before liquefaction to increase liquefaction efficiency.

However, there may be a mixture of lubricating oil in the boil-off gas compressed by the room temperature compressor (35) for four or more stages of the high-pressure compression unit (30), and the boil-off gas mixed with the lubricating oil is boiled off along the boil-off gas reliquefaction line (L210') It may be introduced into the heat exchanger (90).

At this time, the lubricating oil is a material having a significantly higher boiling point compared to the evaporation gas, and may be in a liquid state at room temperature, may be sufficiently solidified even with slight cooling, and may have a high viscosity.

It is not a problem if the flow in the flow path of the boil-off gas heat exchanger 90 is continuous, but if the flow in the boil-off gas heat exchanger 90 is reduced due to the absence of excess boil-off gas, the boil-off gas heat exchanger ( Lubricating oil may be trapped in the flow path of 90), which may interfere with the flow.

Therefore, the present invention is discharged from the low-pressure compression unit in order to solve the problem of obstructing the flow of the boil-off gas due to the lubricating oil in the configurations provided downstream of the boil-off gas heat exchanger 90 and the boil-off gas heat exchanger 90. The lubricant can be melted and pushed out using hot evaporative gas. This will be described later.

The pressure reducing valve 91 decompresses the boil-off gas that has been compressed in the high-pressure compression unit 30 and then heat-exchanged in the boil-off gas heat exchanger 90. In the present invention, the pressure reducing valve 91 may be a Joule-Thomson valve, but it should be noted that it can be replaced with various means capable of lowering the pressure such as an expander.

The boil-off gas is compressed to 6 to 7 bar by the two-stage cryogenic compressor (21) of the low pressure compression unit (20), and to 200 bar or more by the room temperature compressor (35) of four or more stages of the high pressure compression unit (30). After that, it may be cooled in the boil-off gas heat exchanger (90). Although the boil-off point is increased due to the high pressure of the boil-off gas, the boil-off gas may not be sufficiently liquefied only by cooling in the boil-off gas heat exchanger (90).

Accordingly, the present invention can utilize the effect of lowering the temperature during decompression by using the pressure reducing valve 91. The pressure reducing valve 91 can reduce the high-pressure boil-off gas of 200 bar or more to about 1 bar similar to the internal pressure of the liquefied gas storage tank 10, and the temperature of the boil-off gas may drop below the boiling point during the depressurization.

The pressure reducing valve 91 is provided on the boil-off gas re-liquefaction line L210', and unlike the drawing, a plurality of pressure-reducing valves 91 may be provided in series with the boil-off gas re-liquefaction line L210'. Alternatively, variations in which the Joule-Thomson valve and the expander are provided in series are possible.

The liquefied gas gas-liquid separator 92 separates the evaporated gas reduced by the pressure reducing valve 91 into gas-liquid. The boil-off gas is cooled in the boil-off gas heat exchanger (90) and can be liquefied while being depressurized by the pressure-reducing valve (91), but it may not be completely re-liquefied depending on the situation. Some substances may remain unliquefied.

At this time, the gaseous evaporation gas remaining in the gaseous state may be separated from the liquefied gas gas-liquid separator 92 and not flow into the liquefied gas storage tank 10, and the liquid evaporated gas in the liquid state is passed through the liquefied gas gas-liquid separator 92. It may be returned to the liquefied gas storage tank 10 along the boil-off gas re-liquefaction line L210' connected to the liquefied gas storage tank 10.

The liquefied gas gas-liquid separator 92 may return the liquid boil-off gas to the liquefied gas storage tank 10 and transfer the gaseous boil-off gas to the boil-off gas heat exchanger 90. Since the gaseous evaporative gas delivered from the liquefied gas gas-liquid separator 92 to the boil-off gas heat exchanger 90 is cooled by decompression by the pressure reducing valve 91, it is compressed in the high-pressure compression unit 30 and is compressed in the boil-off gas heat exchanger ( It can be used to cool the high-pressure boil-off gas flowing into 90).

In addition, the gaseous boil-off gas separated by the liquefied gas gas-liquid separator 92 may be transferred to the low pressure compression unit 20 through the boil-off gas heat exchanger 90. To this end, the liquefied gas gas-liquid separator 92 is provided with a gaseous boil-off gas delivery line (L230), the vapor-phase boil-off gas delivery line (L230) is the main via the boil-off gas heat exchanger (90) from the liquefied gas-liquid separator (92) It may be connected to the boil-off gas supply line (L100).

Specifically, the gaseous boil-off gas delivery line L230 may be connected to the upstream of the precooler 52 of the main boil-off gas supply line L100. The gaseous boil-off gas separated by the liquefied gas gas-liquid separator 92 is heated in the boil-off gas heat exchanger 90, and the temperature may be lowered through the liquefied gas in the liquefied gas storage tank 10 by the pre-cooler 52. Thereafter, the gaseous evaporative gas merges with the liquefied gas in the precooler 52 and is transferred to the evaporative gas-liquid separator 51, and the evaporative gas-liquid separator 51 separates the evaporated gas in the gaseous phase and transfers it to the low pressure compression unit 20 Can supply.

At this time, a shutoff valve 96a may be provided upstream of the point where the vapor phase evaporative gas delivery line L230 joins the main evaporative gas supply line L100, and the main evaporative gas is supplied from the vapor phase evaporative gas delivery line L230. It is possible to control the flow of gaseous boil-off gas delivered to the line L100.

In addition, a gaseous boil-off gas recovery line L240 branched downstream of the boil-off gas heat exchanger 90 of the vapor-phase boil-off gas delivery line L230 and connected to the low-pressure consumer 200 may be provided. A shut-off valve 96b may be provided in the vapor phase evaporative gas recovery line L240, and a flow of the vapor phase evaporative gas transmitted from the vapor phase evaporative gas delivery line L230 to the low pressure consumer 200 may be controlled.

A forced vaporizer 81a may be provided upstream of the precooler 52, and the low pressure compression unit 20 additionally adds the boil-off gas in which the liquefied gas of the liquefied gas storage tank 10 is forcibly vaporized in the forced vaporizer 81a. Since it can be supplied, the efficiency can be improved as the operation of more than a certain level is guaranteed.

The gas treatment system 1 may include a boil-off gas diesel line L140. The boil-off gas line L140 allows boil-off gas discharged from the liquefied gas storage tank 10 to be transferred to the low-pressure compression unit 20 via the boil-off gas heat exchanger 90. The boil-off gas diesel line L140 may be provided with a boil-off gas diesel valve 94 that controls the flow of the boil-off gas diesel line L140.

The boil-off gas via line L140 may be branched from the main boil-off gas supply line L100, pass through the boil-off gas heat exchanger 90, and then reconnected to the main boil-off gas supply line L100. The low-temperature boil-off gas discharged from the liquefied gas storage tank 10 is delivered to the boil-off gas heat exchanger 90 through the boil-off gas line (L140), and the boil-off gas heat exchanger 90 uses low-temperature boil-off gas. The boil-off gas pressurized by the high-pressure compression unit 30 can be effectively liquefied.

The boil-off gas discharged from the liquefied gas storage tank 10 is heat-exchanged in the boil-off gas heat exchanger (90) and then joins the main boil-off gas supply line (L100) again, and the pre-cooler (52) and the boil-off gas gas-liquid separator (51) Can be delivered to. At this time, the boil-off gas discharged from the liquefied gas storage tank 10 may be heated in the boil-off gas heat exchanger 90, but is cooled by the liquefied gas in the pre-cooler 52 and transferred to the boil-off gas-liquid separator 51. Can be.

As described above, in this embodiment, some of the boil-off gas that is pressurized by the high-pressure compression unit 30 and supplied to the high-pressure consumer 100 is liquefied without a separate refrigerant and transferred to the liquefied gas storage tank 10, thereby reducing excess boil-off gas. It can be effectively liquefied and recovered to the liquefied gas storage tank 10.

3 is a conceptual diagram of a gas treatment system 1 according to a fifth embodiment of the present invention. Specifically, FIG. 3 is a conceptual diagram for removing lubricating oil flowing into the boil-off gas heat exchanger 90 of the gas treatment system 1 according to the fourth embodiment of the present invention. For reference, the valve indicated in black in FIG. 3 indicates that it is closed.

As described above, the lubricating oil may be mixed with the boil-off gas compressed by the room temperature compressor 35 of the high-pressure compression unit 30 or higher in 4 stages, and the boil-off gas mixed with the lubricating oil is the boil-off gas reliquefaction line (L210') The boil-off gas may be introduced into the heat exchanger 90 along the line.

It is not a problem if the flow in the flow path of the boil-off gas heat exchanger 90 is continuous, but if the flow in the boil-off gas heat exchanger 90 is reduced due to the absence of excess boil-off gas, the boil-off gas heat exchanger ( Lubricating oil may be trapped in the flow path of 90), which may interfere with the flow.

Thus, the present invention uses the high-temperature boil-off gas compressed by the low-pressure compression unit 20, and in the configurations provided downstream of the boil-off gas heat exchanger 90 and the boil-off gas heat exchanger 90, the boil-off gas It can solve problems that hinder the flow of energy. Hereinafter, the removal of the lubricating oil stuck in the flow path of the boil-off gas heat exchanger 90 will be described in detail.

The gas treatment system 1 may include a high-temperature boil-off gas recovery line L220 branched between the low-pressure compression unit 20 and the high-pressure compression unit 30 and connected to the boil-off gas reliquefaction line L210'. A high-temperature boil-off gas recovery valve 95 may be provided in the high-temperature boil-off gas recovery line L220. In addition, in the boil-off gas re-liquefaction line L210', a high-pressure boil-off gas recovery valve 97 may be provided upstream of a point where the high-temperature boil-off gas recovery line L220 of the boil-off gas re-liquefaction line L210' joins. .

In this embodiment, in order to remove the lubricating oil from the boil-off gas heat exchanger 90, the high-pressure boil-off gas recovery valve 97 is closed, and the high-temperature boil-off gas recovery valve 95 is opened to remove the high temperature discharged from the low-pressure compression unit 20. The boil-off gas of can be delivered to the boil-off gas heat exchanger (90). The high-temperature boil-off gas discharged from the low-pressure compression unit 20 may be removed from the boil-off gas heat exchanger 90 by forcibly pushing the lubricating oil while lowering the viscosity of the lubricating oil by heating the lubricating oil.

In a state in which the boil-off gas compressed by the high-pressure compression unit 30 is not delivered to the boil-off gas heat exchanger 90, the boil-off gas pressurized by the low-pressure compression unit 20 is supplied to the boil-off gas heat exchanger 90 to supply lubricating oil. Can be removed. When the boil-off gas compressed by the high-pressure compression unit 30 is transferred to the boil-off gas heat exchanger 90 when the lubricant is removed, the liquefaction efficiency of the boil-off gas may be lowered and the lubricant removal effect may be deteriorated.

The boil-off gas into which the lubricating oil discharged from the boil-off gas heat exchanger 90 is mixed is transferred to the liquefied gas gas-liquid separator 92 via the pressure reducing valve 91 along the boil-off gas re-liquefaction line L210'.

At this time, although not separately shown in FIG. 3, the high-temperature boil-off gas mixed with the lubricating oil from the upstream and/or downstream of the pressure reducing valve 91 in the boil-off gas re-liquefaction line (L210') from the boil-off gas re-liquefaction line (L210'). Can be discharged.

After filtering the lubricating oil from the boil-off gas + lubricating oil discharged from the boil-off gas reliquefaction line (L210'), the filtered lubricating oil can be recycled back to the room temperature compressor 35, and the boil-off gas from which the lubricating oil has been removed is heated again. The boil-off gas may be re-introduced into the heat exchanger 90.

In addition, a lubricating oil filter (not shown) is provided between the pressure reducing valve 91 of the boil-off gas re-liquefaction line L210' and the liquefied gas gas-liquid separator 92, and lubricating oil mixed in the boil-off gas may be filtered out.

Through this, it is possible to prevent the lubricating oil removed from the boil-off gas heat exchanger 90 from flowing back into the gas-liquid separator, the liquefied gas storage tank 10, and the boil-off gas heat exchanger 90.

The gas treatment system 1 includes a gaseous boil-off gas delivery line (L230) connected to the main boil-off gas supply line (L100) via an boil-off gas heat exchanger (90) from the liquefied gas-liquid separator (92), and vapor-phase boil-off gas delivery. It may include a gaseous boil-off gas recovery line L240 branched downstream of the boil-off gas heat exchanger 90 of the line L230 and connected to the low-pressure consumer 200.

When the lubricating oil of the boil-off gas heat exchanger 90 is removed, the shut-off valve 96a provided in the vapor phase boil-off gas delivery line L230 is closed, and the shut-off valve 96b provided in the vapor phase boil-off gas recovery line L240 is opened, The gaseous boil-off gas separated by the liquefied gas gas-liquid separator 92 may be supplied to the low pressure consumer 200 via the boil-off gas heat exchanger 90. For example, the gaseous boil-off gas separated by the liquefied gas gas-liquid separator 92 may be delivered to the gas combustion device 220 via the boil-off gas heat exchanger 90.

The gas treatment system 1 includes a boil-off gas gas line (L140) through which boil-off gas discharged from the liquefied gas storage tank 10 is transferred to the low pressure compression unit 20 via the boil-off gas heat exchanger 90. The boil-off gas via line L140 may be provided with an boil-off gas via valve 94 for controlling the boil off gas flow.

When removing the lubricating oil from the boil-off gas heat exchanger (90), the boil-off gas gas oil valve (94) is closed to prevent the low-temperature boil-off gas discharged from the liquefied gas storage tank (10) from passing through the boil-off gas heat exchanger (90). have. At this time, by opening the boil-off gas supply valve 93 provided in the main boil-off gas supply line (L100), the boil-off gas discharged from the liquefied gas storage tank 10 is not passed through the boil-off gas heat exchanger (90) It can be delivered to (20).

That is, the low-temperature evaporation gas discharged from the liquefied gas storage tank 10 does not pass through the boil-off gas heat exchanger 90, so that the high-temperature evaporation is discharged from the low-pressure compression unit 20 and transferred to the boil-off gas heat exchanger 90. You can prevent the gas from cooling.

As described above, in this embodiment, the lubricating oil remaining in the boil-off gas heat exchanger 90 can be effectively removed by using the high-temperature boil-off gas pressurized by the low-pressure compression unit 20.

4 is a conceptual diagram of a gas treatment system 1 according to a sixth embodiment of the present invention.

Referring to FIG. 4, in the gas treatment system 1 according to the sixth embodiment of the present invention, three or more stages of cryogenic compressors 21 are provided in parallel in the low pressure compression unit 20 compared to the first embodiment. The precooler 52 and the evaporative gas-liquid separator 51 may be omitted.

The low pressure compression unit 20 may be provided with a cryogenic compressor 21 having three stages or more and five stages or less in parallel. For example, a four-stage cryogenic compressor 21 may be provided in parallel in the low pressure compression unit 20.

Since the cryogenic compressor 21 for three or more stages is provided in the low pressure compression unit 20, even when the pressure and temperature of the boil-off gas flowing into the low pressure compression unit 20 is not constant, it is discharged from the low pressure compression unit 20 Since the pressure of the boil-off gas to be constant can be adjusted, the pre-cooler 52, the forced vaporizer 81a, and the boil-off gas gas-liquid separator 51 may not be provided upstream of the low-pressure compression unit 20.

The gas treatment system 1 includes an auxiliary liquefied gas supply line L400 connected from the liquefied gas storage tank 10 to the low pressure consumer 200, and the auxiliary liquefied gas supply line L400 includes a forced vaporizer 81b. , A gas-liquid separator 82, and a heater 83 may be provided.

The forced vaporizer 81b vaporizes the liquefied gas in the liquefied gas storage tank 10 into a boil-off gas, and may supply it to the gas-liquid separator 51.

The gas-liquid separator 82 may temporarily store the liquefied gas forcibly vaporized in the forced vaporizer 81b to separate it into a liquid and a gas. At this time, the gas-liquid separator 82 supplies only pure gas to the forced vaporized liquefied gas supplied to the low pressure consumer 200 and at the same time separates the heavy carbon remaining in the liquid phase from the vaporized liquefied gas to increase the methane number. I can. The gas separated by the gas-liquid separator 82 is heated by the heater 83 and supplied to the low pressure consumer 200, and the liquid may be recovered to the liquefied gas storage tank 10.

When a large amount of heavy carbon is introduced into the low pressure consumer 200, the driving efficiency may decrease. Accordingly, in the present invention, when the liquefied gas is forcibly vaporized, the heavy carbon retaining the liquid phase is separated to improve the quality of the boil-off gas supplied to the low-pressure consumer 200, thereby increasing the driving efficiency of the low-pressure consumer 200.

4, the auxiliary liquefied gas supply line (L400) connects the liquefied gas storage tank (10) and the power generation engine (210), and is branched from the downstream of the low pressure compression unit (20) of the main boil-off gas supply line (L100). The auxiliary boil-off gas supply line L200 may be connected to the downstream of the heater 83 of the auxiliary liquefied gas supply line L400.

The gas treatment system 1 receives at least a portion of the boil-off gas discharged from the low-pressure compression unit 20 and delivered to the high-pressure compression unit 30, liquefies the liquefied boil-off gas using a refrigerant, and then stores the liquefied boil-off gas into a liquefied gas storage tank. It may include a re-liquefaction unit 230 that is delivered to (10).

As described above, in this embodiment, by providing three or more stages of cryogenic compressors 21 in parallel in the low pressure compression unit 20, the backup and load of the cryogenic compressor 21 can be shared, and the low pressure compression unit 20 ), the boil-off gas pressurized in the reliquefaction unit 230 can be transferred to the low-pressure compression unit 20, such as the reliquefaction unit 230, to prevent the boil-off gas mixed with the lubricating oil from the low-pressure compression unit 20 from flowing into the low-pressure compression unit 20. have.

5 is a conceptual diagram of a gas treatment system 1 according to a seventh embodiment of the present invention. Specifically, FIG. 5 is a conceptual diagram for re-liquefying the boil-off gas of the gas treatment system 1 according to the seventh embodiment of the present invention. For reference, the valve indicated in black in FIG. 5 indicates that it is closed.

5, in the gas treatment system 1 according to the seventh embodiment of the present invention, three or more stages of cryogenic compressors 21 are provided in parallel in the low pressure compression unit 20 compared to the fourth embodiment. I can.

The gas treatment system 1 is a liquefied gas storage tank 10, a low pressure compression unit 20, a high pressure compression unit 30, a boil-off gas heat exchanger 90, and a pressure reducing valve 91 as in the fourth embodiment. , And a liquefied gas gas-liquid separator 92.

The gas treatment system 1 may include an evaporation gas gas-liquid separator 51, a precooler 52, and a forced vaporizer 81a upstream of the low pressure compression unit 20.

The high-pressure boil-off gas pressurized by the high-pressure compression unit 30 is vaporized from the boil-off gas heat exchanger (90), the low-temperature boil-off gas flowing along the boil-off gas line (L140), the liquefied gas gas-liquid separator (92) It can be cooled by heat exchange with gas.

After the boil-off gas discharged from the boil-off gas heat exchanger (90) is depressurized by the pressure reducing valve (91), it is transferred to the liquefied gas gas-liquid separator (92), and the liquid boil-off gas separated by the liquefied gas gas-liquid separator (92) is a liquefied gas. It is delivered to the storage tank 10. In addition, the gaseous boil-off gas separated by the liquefied gas gas-liquid separator 92 may be transferred to the low-pressure compression unit 20 via the boil-off gas heat exchanger 90.

At this time, the gaseous boil-off gas separated by the liquefied gas gas-liquid separator 92 and passed through the boil-off gas heat exchanger 90 is joined to the main boil-off gas supply line L100 with an elevated temperature, but is transferred to the precooler 52. The temperature may be lowered through the supplied liquefied gas.

The forced vaporizer 81a vaporizes the liquefied gas in the liquefied gas storage tank 10 into evaporated gas, and the vaporized liquefied gas may be delivered to the evaporated gas gas-liquid separator 51 via the precooler 52. That is, by controlling the flow rate of the boil-off gas delivered to the low-pressure compression unit 20 and the high-pressure compression unit 30 using the forced carburetor 81a, the gas treatment system 1 operates in a raiden condition or a ballast condition. Even if it becomes, it can be driven elastically.

As described above, in this embodiment, by providing three or more stages of cryogenic compressors 21 in parallel to the low pressure compression unit 20, the backup and load of the cryogenic compressor 21 can be shared, and the high pressure compression unit 30 ), it is possible to recover the liquefied gas storage tank 10 by effectively liquefying the excess boil-off gas pressurized without a separate refrigerant.

6 is a conceptual diagram of a gas treatment system 1 according to an eighth embodiment of the present invention. Specifically, FIG. 6 is a conceptual diagram for removing lubricating oil introduced into the boil-off gas heat exchanger 90 of the gas treatment system 1 according to the seventh embodiment of the present invention. For reference, the valve indicated in black in FIG. 6 indicates that it is closed.

6, in the gas treatment system 1 according to the eighth embodiment of the present invention, three or more stages of cryogenic compressors 21 are provided in parallel in the low pressure compression unit 20 compared to the fifth embodiment. I can.

This embodiment can effectively remove the lubricating oil remaining in the boil-off gas heat exchanger 90 by using the high-temperature boil-off gas pressurized by the low-pressure compression unit 20 in the same manner as in the fifth embodiment.

It goes without saying that the present invention is not limited to the above-described embodiments, and may include a combination of the above embodiments or a combination of at least one of the above embodiments and a known technology as another embodiment.

Although the present invention has been described in detail through specific examples, this is for explaining the present invention in detail, and the present invention is not limited thereto, and within the technical scope of the present invention, those of ordinary skill in the art It would be clear that the transformation or improvement is possible.

All simple modifications to changes of the present invention belong to the scope of the present invention, and the specific scope of protection of the present invention will be made clear by the appended claims.

1: gas treatment system
10: liquefied gas storage tank 11: pump
20: low pressure compression unit 21: cryogenic compressor
211: diffuser vane 22: cooler
23: anti-surge valve 30: high pressure compression unit
31: return valve 32: downstream pressure control module
33: upstream pressure control module 34: control selection module
35: room temperature compressor 41: overpressure valve
42, 43: pressure control module 51: boil-off gas gas-liquid separator
52: precooler 61, 62, 63, 64: pressure measuring sensor
71: liquefied gas pump 72: liquefied gas vaporizer
81a, 81b: forced vaporizer 82: gas-liquid separator
83: heater 90: boil-off gas heat exchanger
91: pressure reducing valve 92: liquefied gas gas-liquid separator
93: boil-off gas supply valve 94: boil-off gas light oil valve
95: high temperature boil-off gas recovery valve 96a, 96b: shut-off valve
97: high-pressure boil-off gas recovery valve 100: high-pressure consumer
200: low pressure consumer 210: power generation engine
220: gas combustion device 230: reliquefaction unit
231: reliquefier L100: main boil-off gas supply line
L110: anti-surge line L120: overpressure prevention line
L130: boil-off gas recovery line L140: boil-off gas line
L200: auxiliary boil-off gas supply line L210, L210': boil-off gas reliquefaction line
L220: high temperature boil-off gas recovery line L230: vapor-phase boil-off gas delivery line
L240: gaseous boil-off gas recovery line L300: main liquefied gas supply line
L310: liquefied gas transfer line L320: liquefied gas forced vaporization line
L400: auxiliary liquefied gas supply line

Claims (10)

A low pressure compression unit provided in parallel with three or more stages of cryogenic compressors for compressing the boil-off gas of the liquefied gas storage tank;
A high-pressure compression unit provided with a four-stage or more room-temperature compressor for supplying the boil-off gas pressurized by the cryogenic compressor to a high-pressure consumer;
It is provided between the low pressure compression unit and the high pressure compression unit, and when the pressure of the boil-off gas at the rear end of the low-pressure compression unit is more than a certain pressure, the boil-off gas discharged from the low-pressure compression unit is joined to the boil-off gas supplied to the low-pressure compression unit. Overpressure valve;
A re-liquefaction unit for liquefying at least some of the boil-off gas discharged from the low-pressure compression unit and delivered to the high-pressure compression unit by using a refrigerant, and delivering the liquefied gas storage tank;
A forced vaporizer for vaporizing the liquefied gas in the liquefied gas storage tank;
A gas-liquid separator that receives the liquefied gas vaporized from the forced vaporizer and separates it into a gas phase and a liquid phase; And
And a heater for heating the gaseous liquefied gas separated by the gas-liquid separator and supplying it to a low-pressure consumer. delete The method of claim 1,
At least some of the boil-off gas discharged from the low pressure compression unit and delivered to the high pressure compression unit is supplied to a low pressure consumer,
The low pressure consumer includes at least one of a power generation engine and a gas combustion device (GCU), and the pressure of the boil-off gas between the low pressure compression unit and the high pressure compression unit is adjusted to 6 to 7 bar. system. delete The method of claim 1, wherein the low pressure compression unit,
A cooler for cooling the boil-off gas discharged from the cryogenic compressor; And
An anti-surge valve provided between the cryogenic compressor and the cooler and configured to join the boil-off gas discharged from the cryogenic compressor to the boil-off gas supplied to the low-pressure compression unit when a surge phenomenon occurs in the cryogenic compressor. Gas treatment system, characterized in that. The method of claim 1, wherein the high pressure compression unit,
A recovery valve for recovering the boil-off gas discharged from the high-pressure compression unit to the high-pressure compression unit; And
Gas, characterized in that it comprises a downstream pressure control module that is provided at the rear end of the high pressure compression unit and controls the opening and closing of the recovery valve so that the pressure of the boil-off gas discharged from the high pressure compression unit is maintained at a pressure required by the high pressure customer. Processing system. The method of claim 6, wherein the high pressure compression unit,
An upstream pressure control module provided at a front end of the high-pressure compression unit and for recovering the boil-off gas discharged from the high-pressure compression unit to the high-pressure compression unit by opening the recovery valve when the boil-off gas pressure at the front end of the high-pressure compression unit is less than a certain pressure. Gas treatment system, characterized in that it further comprises. The method of claim 1,
The cryogenic compressor is a centrifugal compressor, and the room temperature compressor is a reciprocating compressor. The method of claim 1,
A liquefied gas pump for compressing and delivering the liquefied gas in the liquefied gas storage tank; And
And a liquefied gas vaporizer that vaporizes the liquefied gas discharged from the liquefied gas pump and supplies the vaporized liquefied gas to the high pressure consumer. A vessel comprising the gas treatment system of any of claims 1, 3 and 5 to 9.

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