KR102436050B1 - Gas treatment system and ship having the same - Google Patents

Abstract

The present invention relates to a gas treatment system and a ship including the same, comprising: a plurality of storage tanks provided to store n types of liquefied gas, respectively; a fuel supply unit for supplying the liquefied gas of the storage tank to the propulsion engine; a plurality of re-liquefaction units for liquefying the boil-off gas generated in the storage tank; and a fuel recovery unit for recovering the liquid surplus liquefied gas discharged from the propulsion engine, wherein n of the plurality of re-liquefaction units are provided, and when a problem occurs in the operation of any one of the re-liquefaction units, the boil-off gas Some are processed by the reliquefaction unit operating normally, and the rest are processed by supplying them to auxiliary consumers.

Description

Gas treatment system and ship including the same {Gas treatment system and ship having the same}

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

In general, liquefied petroleum gas, that is, LPG (Liquefied petroleum gas) is liquefied by pressurizing the gas at room temperature with hydrocarbons having a low boiling point such as propane and butane among petroleum components. This liquefied petroleum gas is filled in a small and light pressure vessel (cylinder) and is widely used as fuel for household, business, industrial, and automobile use.

Liquefied petroleum gas is extracted in gaseous form at the production site, stored after being liquefied through a liquefied petroleum gas processing facility, and transported to the land while maintaining the liquid phase by a liquefied petroleum gas carrier, and then supplied to consumers in various forms such as gas. do.

Since the boiling point of such liquefied petroleum gas is around -50°C, a liquefied petroleum gas carrier for transporting liquefied petroleum gas must maintain a lower temperature than this. Therefore, the storage tank for storing liquefied petroleum gas uses low-temperature steel (Low Temperature Carbon Steel and Nickel Steel) that is strong at low temperatures, and a re-liquefaction facility is also provided for the liquefied petroleum gas carrier.

These liquefied petroleum gas carriers generate propulsion by operating an engine using diesel oil in the conventional case. However, in the process of combustion of diesel oil in a marine propulsion engine, nitrogen oxides (NOx), sulfur oxides (SOx), and carbon dioxide (CO2), which are harmful components, are generated. have.

Therefore, in recent years, in order to significantly lower the pollution level of the exhaust when compared to the case of using diesel oil, the development of engines operating using liquefied petroleum gas and the development of various systems for supplying liquefied petroleum gas to the engine are continuously being made. have.

The present invention was created to solve the problems of the prior art as described above, and an object of the present invention is to provide a gas processing system capable of generating propulsion by using liquefied petroleum gas and a ship including the same.

A gas treatment system according to an aspect of the present invention includes: a plurality of storage tanks provided to store n types of liquefied gas, respectively; a fuel supply unit for supplying the liquefied gas of the storage tank to the propulsion engine; a plurality of re-liquefaction units for liquefying the boil-off gas generated in the storage tank; and a fuel recovery unit for recovering the liquid surplus liquefied gas discharged from the propulsion engine, wherein n of the plurality of re-liquefaction units are provided, and when a problem occurs in the operation of any one of the re-liquefaction units, the boil-off gas Some are processed by the reliquefaction unit operating normally, and the rest are processed by supplying them to auxiliary consumers.

Specifically, the auxiliary demand may be at least one of a boiler, a gas combustion device, or a generator that burns boil-off gas.

Specifically, the re-liquefaction unit includes a compressor for compressing BOG in multiple stages, a condenser for liquefying the compressed BOG, and heat exchange by dividing the BOG liquefied in the condenser, and heat-exchanging a gaseous phase of the heat-exchanged BOG of the compressor. It may include an intercooler delivered to some of the intermediate stages, and an aftercooler provided at the rest of the intermediate stages of the compressor for cooling the boil-off gas using a refrigerant provided separately from the boil-off gas.

Specifically, the plurality of re-liquefaction units, when a problem occurs in the operation of the condenser of any one of the re-liquefaction units, some of the boil-off gas is treated as the re-liquefaction unit operating normally, and the rest of the re-liquefaction unit has a problem in operation It can be processed by supplying it from the upstream or middle to the auxiliary demanding place.

A ship according to an aspect of the present invention has the gas treatment system.

The gas treatment system and the ship including the same according to the present invention can use liquefied petroleum gas as a propulsion fuel, deviating from the conventional system using only diesel oil, thereby reducing environmental pollution and increasing energy efficiency.

1 is a conceptual diagram of a gas processing system according to a first embodiment of the present invention.
2 is a conceptual diagram of a gas processing system according to a second embodiment of the present invention.
3 is a conceptual diagram of a gas processing system according to a third embodiment of the present invention.
4 is a conceptual diagram of a gas processing system according to a fourth embodiment of the present invention.
5 is a conceptual diagram of a gas processing system according to a fifth embodiment of the present invention.
6 is a conceptual diagram of a gas processing system according to a sixth embodiment of the present invention.

The objects, specific advantages and novel features of the present invention will become more apparent from the following detailed description and preferred embodiments taken in conjunction with the accompanying drawings. In the present specification, in adding reference numbers to the components of each drawing, it should be noted that only the same components are given the same number as possible even though they are indicated on different drawings. In addition, in describing the present invention, if it is determined that a detailed description of a related known technology may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

In the present specification, the liquefied gas may be LPG (propane, butane, etc.) as a heavy hydrocarbon, but is not limited thereto, and any substance (propylene, ammonia, hydrogen, etc.) can include

In addition, it should be noted that liquefied gas/evaporated gas in the present specification is classified based on the state inside the tank, and is not necessarily limited to liquid or gas due to the name.

The present invention includes a vessel equipped with a gas treatment system as described below. At this time, a ship is a concept that includes all gas carriers, merchant ships that transport cargo or people other than gas, FSRUs, FPSOs, bunkering vessels, and offshore plants, but note that it may be a liquefied petroleum gas carrier as an example.

Although not shown in the drawings of the present invention, of course, the pressure sensor (PT), the temperature sensor (TT), etc. may be provided at an appropriate position without limitation, and the measured value by each sensor is dependent on the operation of the components described below. It can be used in various ways without limitation.

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

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

Referring to FIG. 1 , the gas treatment system 1 according to the first embodiment of the present invention includes a storage tank, a fuel supply unit 20 , a reliquefaction unit 30 , and a fuel recovery unit 40 .

The storage tank stores liquefied gas. The storage tank may include a cargo tank 10 and a fuel tank 11 .

The cargo tank 10 may be a plurality of cargo tanks 10 provided in the ship, which is a liquefied gas carrier. The cargo tank 10 may be a tank for storing liquefied gas as a low-temperature liquid at atmospheric pressure, and various insulating structures may be added to the wall. In addition, the cargo tank 10 may be a membranous tank or an independent tank, and the shape or specifications thereof are not limited.

A cargo pump (not shown) may be provided to discharge the liquefied gas of the cargo tank 10 to the outside. The cargo pump may be provided inside the cargo tank 10, and may be provided as a submerged type submerged in liquefied gas.

The cargo pump may be an unloading pump, a stripping pump, a spray pump, etc. for processing the liquefied gas as cargo, or a fuel pump for delivering the liquefied gas as a fuel to the fuel tank 11 or the fuel supply unit 20 .

Since the liquefied gas stored in the cargo tank 10 is naturally evaporated by external heat penetration, evaporation gas is generated in the cargo tank 10 . BOG may be used as fuel of the propulsion engine E or may be re-liquefied, and a BOG discharge line L10 for discharging BOG may be provided in the cargo tank 10 .

The cargo tank 10 may be provided in plurality in order to respectively store at least two kinds of liquefied gases among liquefied gases (propane, butane, propylene, etc.) containing heavy hydrocarbons as a main component. For example, the first cargo tank 10 may store propane, and the second cargo tank 10 may store butane.

The boil-off gas of the cargo tank 10 is liquefied by the re-liquefaction unit 30 to be described later. In order to prevent this, in addition to the number of types of liquefied gas stored in the cargo tank 10 may be provided in consideration of additional backup. That is, when the cargo tank 10 stores n types of liquefied gas, it is common that at least n+1 pieces of the reliquefaction unit 30 are provided.

However, in this embodiment, by transferring the boil-off gas liquefied by the re-liquefaction unit 30 to the fuel tank 11 or the fuel supply unit 20 without returning to the cargo tank 10, the cargo tank 10 is n Even if it is provided to store a kind of liquefied gas, the number of re-liquefaction units 30 can be reduced from n+1 to n. This will be described in detail below. Of course, if the composition mixing of the liquefied gas is not a concern, it will be possible for the boil-off gas to be returned from the reliquefaction unit 30 to the cargo tank 10 .

The fuel tank 11 stores the liquefied gas for use as fuel and receives the liquefied gas from the cargo tank 10 . The fuel tank 11 is different from the cargo tank 10 for the purpose of storing the liquefied gas. The fuel tank 11 may have a relatively small storage capacity compared to the cargo tank 10 .

The fuel tank 11 stores the liquefied gas as a low-temperature liquid similar to the cargo tank 10, and the type is not limited. However, the fuel tank 11 may have a relatively high design pressure and liquefied gas storage pressure compared to the cargo tank 10 .

The fuel tank 11 may be a Type C tank in the form of a pressure vessel, and may be disposed on the deck unlike the cargo tank 10 mounted inside the hull. Of course, the arrangement position or type of the fuel tank 11 is not limited.

The fuel tank 11 receives the liquefied gas from the cargo tank 10 and temporarily stores it to supply it as fuel. In addition, if the composition mixing of the cargo is not a concern, the return of the liquefied gas from the fuel tank 11 to the cargo tank 10 may be possible.

The liquid BOG liquefied in the reliquefaction unit 30 may be delivered to the fuel tank 11 . In addition, it is also possible that the high-pressure boil-off gas before condensing after compression in the reliquefaction unit 30 is injected into the fuel tank 11 , which will be described later.

The fuel supply unit 20 supplies the liquefied gas of the storage tank to the propulsion engine (E). In particular, the fuel supply unit 20 may supply the liquefied gas of the fuel tank 11 , the boil-off gas of the cargo tank 10 , and the like to the propulsion engine E .

In the present specification, the propulsion engine (E) is a configuration for propulsion of a ship, and can be interpreted as any configuration capable of directly or indirectly generating propulsion force by consuming liquefied gas such as a turbine, a fuel cell, etc. rather than an engine.

The liquefied gas of the fuel tank 11 is delivered to the propulsion engine E by a liquefied gas supply line L20 extending from the fuel tank 11, and the fuel supply unit 20 is on the liquefied gas supply line L20. A high-pressure pump 21 and a heat exchanger 22 are provided.

The high-pressure pump 21 pressurizes the liquefied gas according to the required pressure of the propulsion engine E. The high-pressure pump 21 may be provided in plurality to enable mutual backup, and may be a centrifugal type, a reciprocating type, a screw type, or the like.

However, in this embodiment, the high-pressure pump 21 may be provided in a reciprocating type, and may be a membrane type rather than a side channel type. At this time, the suction pressure of the high-pressure pump 21 may be about 8 bar. The suction pressure of the high-pressure pump 21 is lower than the critical pressure of the liquefied gas, and may be a pressure at which vaporization may occur based on the temperature of the liquefied gas recovered by the fuel recovery unit 40 to be described later. However, since a cooler 41 is provided in the fuel recovery unit 40 , vaporization in the high-pressure pump 21 can be sufficiently prevented.

When the suction pressure of the high-pressure pump 21 is higher than the critical pressure of the liquefied gas or the pressure that does not vaporize even at the highest temperature that the liquefied gas reaches in the system (about 50 degrees Celsius) or more (for example, about 20 bar), the high pressure The advantage is that cavitation in the pump 21 is blocked.

However, in this case, a boosting pump for pressurizing and delivering liquefied gas from the fuel pump to the high-pressure pump 21 must be provided, and since the liquefied gas flows in a high-pressure state at the front end of the high-pressure pump 21, line and control, etc. The configuration should be provided for high pressure. Accordingly, there is a problem in that manufacturing cost and maintenance cost are increased.

On the other hand, in this embodiment, the high-pressure pump 21 is provided with a suction pressure of about 8 bar, but by controlling the internal pressure of the fuel tank 11 to be high in response to the internal pressure of the high-pressure pump 21, the fuel tank 11 It is not necessary to provide a separate pressurizing means between the and the high-pressure pump (21).

Specifically, the fuel tank 11 maintains the liquefied gas above the first pressure. The first pressure is lower than the design pressure of the fuel tank 11 (eg, around 18 bar) and may be a value corresponding to the suction pressure of the high-pressure pump 21 , and the temperature of the liquefied gas recovered from the fuel recovery unit 40 . It may be a lower pressure than the reference pressure at which vaporization does not occur (for example, around 15 bar). For example, the first pressure may be 5 bar to 10 bar.

The fuel tank 11 may use the boil-off gas compressed in the reliquefaction unit 30 to maintain the internal pressure. That is, since the high-pressure boil-off gas compressed in the reliquefaction unit 30 is injected into the fuel tank 11 , the internal pressure of the fuel tank 11 can be maintained above the first pressure, which is the suction pressure of the high-pressure pump 21 . Through this, in the present embodiment, the liquefied gas of the fuel tank 11 can be delivered to the high-pressure pump 21 without a separate pressurization.

The heat exchanger 22 adjusts the temperature of the liquefied gas according to the required temperature of the propulsion engine (E). The heat exchanger 22 may be provided downstream of the high-pressure pump 21 as shown in the drawing, but may also be provided upstream of the high-pressure pump 21 .

Since the heat exchanger 22 may increase or decrease the temperature of the liquefied gas, it may be referred to as a fuel conditioner. For example, during the initial operation of this embodiment, since the flow rate of the high-temperature liquefied gas recovered from the propulsion engine E is large, the heat exchanger 22 can lower the temperature of the liquefied gas, and when entering into stable operation, the heat exchanger (22) can increase the temperature of the liquefied gas.

The heat exchanger 22 may implement heat exchange with liquefied gas using various heat exchange media. For example, the heat exchange medium may be seawater, fresh water, glycol water, exhaust gas, or the like, but is not limited thereto.

The re-liquefaction unit 30 compresses and liquefies the boil-off gas generated in the storage tank. In particular, the re-liquefaction unit 30 may receive and condensate the boil-off gas discharged from the cargo tank 10 . ) can be provided.

The reliquefaction unit 30 includes a compressor 31 , a condenser 32 , and an intercooler 33 . The compressor 31 compresses the boil-off gas in multiple stages. The compressor 31 may be, for example, a multi-stage compressor 31 composed of three stages, but the number of stages is not limited to three stages. For the sake of the following description, for convenience, between each compression stage is referred to as an intermediate stage.

The condenser 32 liquefies the compressed boil-off gas. Since the boiling point of the BOG whose pressure is increased by the compressor 31 is increased, the condenser 32 can liquefy the BOG even if it is cooled to a temperature lower than the BOG boiling point at atmospheric pressure.

The condenser 32 liquefies the compressed BOG into a refrigerant such as seawater. The condenser 32 may have a structure of at least two streams including a boil-off gas stream into which the boil-off gas compressed in the compressor 31 flows, and a refrigerant stream through which a refrigerant for heat exchange with the boil-off gas flows. The type of the condenser 32 is not limited, such as Shell & Tube, PCHE, and a bath type is also possible.

The intercooler 33 divides the boil-off gas liquefied in the condenser 32 to exchange heat with each other. The intercooler 33 may receive liquid BOG delivered from a separator (not shown) provided downstream of the condenser 32, and divide the flow of the liquid BOG so that some flows into the intercooler 33, , the remainder may be heat exchanged without mixing while passing through the intercooler 33 .

At this time, the BOG flowing into the intercooler 33 may be decompressed before flowing into the intercooler 33 , and the BOG passing through the intercooler 33 may be cooled by the BOG stored in the intercooler 33 . have. BOG cooled while passing through the intercooler 33 may be delivered to the cargo tank 10 or the fuel tank 11 .

The BOG introduced into the intercooler 33 may be gas-liquid separated, and the vapor BOG is joined to an intermediate stage of the compressor 31 . Therefore, the inflow flow rate of the compression stage downstream of the intermediate stage where the boil-off gas is joined from the intercooler 33 is greater than that of the first stage of the compressor 31 .

When the compressor 31 is provided in three stages and two intermediate stages are formed, the intercooler 33 may be provided in two to deliver the gas phase to each intermediate stage. That is, the intercooler 33 may be disposed at each intermediate stage of the compressor 31 .

However, in this case, as described above, as the vapor phase boil-off gas is merged into the intermediate stage by the intercooler 33, the inflow flow rate of each compression stage is gradually increased. Therefore, the compressor 31 may limit the inflow flow rate of the compressor 31 based on the inflow flow rate of the final compression stage, which means that the BOG processing amount of the reliquefaction unit 30 itself may be limited.

In order to solve this problem, in the present embodiment, the intercooler 33 is allocated to only a part of the intermediate stage, and the aftercooler 34 may be provided in the rest of the intermediate stage instead of the intercooler 33 .

That is, the intercooler 33 transmits the gas phase to only a part of the intermediate stages of the compressor 31 , and an aftercooler 34 is disposed on the rest of the intermediate stages of the compressor 31 , so that boil-off gas is used using a refrigerant provided separately from the boil-off gas. can be cooled directly.

Therefore, in the compressor 31 of this embodiment, the intermediate stage where the gas phase is joined by the intercooler 33 becomes a part of all intermediate stages, so that the inflow flow rate of the compressor 31 can be sufficiently secured, and the reliquefaction unit ( 30) can be expanded.

Furthermore, in the present embodiment, when providing a plurality of reliquefaction units 30 , the number of reliquefaction units 30 may be minimized. For example, if the three-stage compressor 31 and the reliquefaction unit 30 for installing the intercooler 33 for each intermediate stage can handle 400 capacity, this embodiment uses any one intercooler 33 as the aftercooler ( 34), it is possible to increase the BOG processing capacity of one reliquefaction unit 30 to 600. Therefore, the number of re-liquefaction units 30 can be reduced to two in comparison with the case of installing three re-liquefaction units 30 in the past.

As such, in this embodiment, the capacity of each reliquefaction unit 30 can be increased, and liquefied gas composition contamination is prevented by transferring the boil-off gas liquefied by the reliquefaction unit 30 to the fuel tank 11 , n When storing the liquefied gas of the species, it is possible to install only n re-liquefaction units 30 .

As an example, in a system for storing two types of liquefied gas, as opposed to installing three reliquefaction units 30 having a BOG processing capacity of 400, in this embodiment, the reliquefaction unit 30 having a BOG processing capacity of 600 is installed. Only two can be installed.

For reference, one fuel tank 11 may be allocated to one or more reliquefaction units 30 . That is, the fuel tank 11 may be provided in a smaller number than the reliquefaction unit 30 , and for example, two reliquefaction units 30 may be connected to one fuel tank 11 .

BOG liquefied in the reliquefaction unit 30 may be delivered to the fuel supply unit 20 along the BOG supply line L11 , and high pressure together with the liquefied gas delivered from the fuel tank 11 to the high pressure pump 21 . It may be supplied to the pump 21 .

That is, the boil-off gas supply line L11 may be provided to join between the fuel tank 11 and the high-pressure pump 21 in the liquefied gas supply line L20 . In addition, the boil-off gas supply line L11 may be connected to the liquefied gas supply line L20 upstream from the point where the liquefied gas recovery line L30, which will be described later, joins the liquefied gas supply line L20.

A boil-off gas delivery line L12 may be branched from the boil-off gas supply line L11. The boil-off gas delivery line L12 delivers the liquid boil-off gas liquefied in the re-liquefaction unit 30 to the fuel tank 11 . That is, the boil-off gas liquefied by the re-liquefaction unit 30 is delivered to the high-pressure pump 21 or the fuel tank 11 of the fuel supply unit 20, not the cargo tank 10, so that liquefied gases of different compositions are simultaneously recycled. Even if it is liquefied, it is possible to prevent the liquefied gas composition from being contaminated in the cargo tank 10 .

A boil-off gas recovery line L13 is provided in the reliquefaction unit 30 . The boil-off gas recovery line L13 may be connected to the fuel tank 11 upstream of the condenser 32 in order to deliver the high-pressure boil-off gas compressed in the reliquefaction unit 30 to the fuel tank 11 .

The boil-off gas recovery line (L13) may extend from a downstream end of the final stage in the compressor 31 configured in multiple stages, or may extend from an intermediate stage. However, the boil-off gas recovery line L13 is for maintaining the internal pressure of the fuel tank 11 above the first pressure, and when it is branched from the middle end of the compressor 31, it is upstream of the aftercooler 34 or the intercooler 33 ) may extend to the fuel tank 11 from the upstream of the point at which the boil-off gas is delivered.

In this embodiment, by injecting the high-pressure BOG compressed in at least one stage of the compressors 31 of the reliquefaction unit 30 into the fuel tank 11 by using the BOG recovery line L13, the fuel tank 11 maintains the internal pressure of the high pressure pump 21 or higher than the first pressure, which is the suction pressure of the high-pressure pump 21 . Therefore, in this embodiment, the liquefied gas of the fuel tank 11 can be delivered to the high-pressure pump 21 without a separate boosting.

The fuel recovery unit 40 recovers the liquid surplus liquefied gas discharged from the propulsion engine (E). The propulsion engine (E) of this embodiment may be an engine (ME-LGI, etc.) supplied with liquefied gas in a liquid phase, and the flow rate of the engine (ME-GI, X-DF, etc.) Difficult to fine-tune. Therefore, the propulsion engine (E) may be configured to receive the liquefied gas at a required flow rate or more and discharge the surplus liquefied gas.

At this time, the liquefied gas discharged from the propulsion engine (E) is a liquefied gas that has passed through the inside of the propulsion engine (E), and has a temperature / pressure corresponding to the required pressure of the propulsion engine (E) (for example, around 45 bar, 50°C or higher), the lubricating oil used in the propulsion engine (E) may have been mixed. In this case, in order to prevent contamination of the cargo, it is preferable not to deliver the recovered liquefied gas to the cargo tank 10 .

Therefore, the liquefied gas recovery line (L30) connected to the propulsion engine (E) so that the surplus liquefied gas is recovered is the fuel supply unit (20), not the cargo tank (10), for the surplus liquefied gas returned from the propulsion engine (E). It can be delivered to the high-pressure pump 21 of the propulsion engine (E) to be re-introduced.

The fuel recovery unit 40 includes a cooler 41 , a collection tank 42 , and a knockout drum 43 provided in the liquefied gas recovery line L30 . In addition, the fuel recovery unit 40 may include a pressure reducing valve (not shown) provided in the liquefied gas recovery line (L30).

The pressure reducing valve depressurizes the liquid liquefied gas. The pressure reducing valve may be a Joule-Thomson valve, and may constitute a fuel supply train (FVT) together with a fuel supply valve provided in the liquefied gas supply line (L20). Such a pressure reducing valve may reduce the pressure of the liquefied gas of high pressure (about 30 to 50 bar) recovered from the propulsion engine (E) to match the suction pressure of the high pressure pump (21).

The cooler 41 cools the liquefied gas pressure-reduced by the pressure reducing valve and delivers it to the high-pressure pump 21 . The cooler 41 may utilize a variety of refrigerants that are not limited, and may cool the liquefied gas below the boiling point of the depressurized liquefied gas.

The liquefied gas cooled by the cooler 41 is mixed upstream of the high-pressure pump 21 in the liquefied gas supply line L20 through the liquefied gas recovery line L30, and the liquefied gas recovery line L30 is liquefied gas A mixer (not shown) may be provided at a point connected to the supply line L20.

A liquefied gas circulation line (not shown) connected to the liquefied gas recovery line L30 may be provided downstream of the high pressure pump 21 . The liquefied gas discharged from the high-pressure pump 21 may be transferred to the liquefied gas recovery line L30 along the liquefied gas circulation line and circulated back to the high-pressure pump 21 . Through this, even when the propulsion engine (E) has a low load, it is possible to satisfy the minimum required flow rate of the high-pressure pump (21).

The collection tank 42 separates gas-liquid gas recovered from the propulsion engine (E). Since a cavitation problem may occur when gaseous liquefied gas flows into the high-pressure pump 21, in the present invention, the liquefied gas flowing along the liquefied gas recovery line L30 passes through the collection tank 42 as needed, while gas-liquid separation. As possible, it is possible to block the inflow of the gaseous liquefied gas to the high-pressure pump 21 .

That is, the collection tank 42 collects at least a portion of the liquefied gas of the liquefied gas recovery line L30 and delivers only the liquid liquefied gas to the high-pressure pump 21 , thereby ensuring stable operation of the high-pressure pump 21 .

The gaseous liquefied gas branched from the collection tank 42 may be delivered to the knockout drum 43 . The knockout drum 43 may receive the liquefied gas recovered from the propulsion engine E from the collection tank 42 and filter out impurities (lubricating oil, etc.) contained in the liquefied gas.

The knockout drum 43 separates lubricating oil from the liquefied gas introduced therein. Specifically, the knockout drum 43 discharges the liquefied gas in the gas phase and the lubricating oil in the liquid phase. That is, the knockout drum 43 implements a gas-liquid separation function similarly to the collection tank 42 .

The knockout drum 43 may use a heating unit such as tracing to promote vaporization of the liquefied gas, and the tracing may be configured to use a medium such as steam or seawater as a heat source or to heat using electricity. have.

The knockout drum 43 may heat liquefied gas mixed with lubricating oil by a heating unit, discharge the liquefied gas through a vent mast (not shown), etc., and drain the lubricating oil from the lower portion for treatment (recycle).

As described above, in this embodiment, the suction pressure of the high-pressure pump 21 is lower than the critical pressure of the liquefied gas, and the internal pressure of the fuel tank 11 is maintained according to the suction pressure of the high-pressure pump 21 by utilizing the high-pressure boil-off gas. By doing so, it is possible to omit a separate pumping means between the fuel tank 11 and the high-pressure pump 21 .

2 is a conceptual diagram of a gas processing system according to a second embodiment of the present invention.

Hereinafter, the present embodiment will be mainly described on the points that are different from the previous embodiment, and the parts omitted from the description will be replaced with the previous content. Note that this also applies to other embodiments below.

Referring to FIG. 2 , the gas treatment system 1 according to the second embodiment of the present invention maintains the internal pressure of the fuel tank 11 above the first pressure as in the previous embodiment, but the means for this is provided in advance. Unlike the example

In the present embodiment, the internal pressure increase of the fuel tank 11 may be realized by itself. That is, the fuel tank 11 is provided with a configuration for heating the liquefied gas stored therein. Specifically, the fuel tank 11 may be provided with an in-tank heater 13 for heating the liquefied gas inside the fuel tank 11 .

Alternatively, the pressure increasing unit 14 for circulating the liquefied gas stored in the fuel tank 11 to the fuel tank 11 after heating from the outside of the fuel tank 11 may be provided. The pressure increase unit 14 may be a PBU (Pressure Build-up Unit), etc., and may include a pump and a heater for circulation of liquefied gas.

As described above, in this embodiment, in order to supply liquefied gas from the fuel tank 11 to the high-pressure pump 21 without additional pressurization, as in the previous embodiment, the liquefied gas stored in the fuel tank 11 is transferred to the fuel tank 11 . ) can be maintained at a sufficient level by heating from the inside/outside of the fuel tank 11 .

3 is a conceptual diagram of a gas processing system according to a third embodiment of the present invention.

Referring to FIG. 3 , the gas processing system 1 according to the third embodiment of the present invention may be prepared for a case in which a problem occurs in the operation of at least one of the plurality of reliquefaction units 30 . .

For reference, in the case of FIG. 3 , the transfer pump 12 is provided to transfer the liquefied gas from the fuel tank 11 to the high-pressure pump 21 , but the transfer pump 12 is omitted as in the previous embodiment. It is also possible to

This embodiment includes an auxiliary demanding destination (D). Auxiliary demand (D) may be at least one of a boiler that burns boil-off gas, a gas combustion device, or a generator (such as a power generation engine or a turbine for power generation). In addition, a plurality of auxiliary consumers (D) may be provided in parallel.

The BOG branch line L40 is connected to the auxiliary consumer (D) to supply BOG, and the BOG branch line L40 is branched from the BOG discharge line L10 or the re-liquefaction unit 30 to the auxiliary consumer. (D) is extended.

Auxiliary demand (D) consumes boil-off gas that is not treated by the re-liquefaction unit 30 after being discharged from the cargo tank 10 when any one of the re-liquefaction units 30 among the plurality of re-liquefaction units 30 fails. do.

Specifically, when the cargo tank 10 is provided to store n types of liquefied gas, respectively, and n re-liquefaction units 30 are provided, when a problem occurs in the operation of any one re-liquefaction unit 30, evaporation Some of the gas is processed by the reliquefaction unit 30 that is normally operated, and the rest is supplied to and processed by the auxiliary demander (D).

To this end, the boil-off gas branch line L40 may be connected from the upstream or intermediate stage of the compressor 31 in the reliquefaction unit 30 or the downstream of the compressor 31 to the auxiliary consumer D, and in this case, the auxiliary consumer D ) may consume the boil-off gas compressed by any one of the compressors 31 of the reliquefaction unit 30 .

That is, when a problem occurs in the operation of the condenser 32 of any one of the reliquefaction units 30 (the compressor 31 operates normally), the plurality of reliquefaction units 30 convert some of the boil-off gas to the reliquefaction unit ( 30), and the rest can be supplied to the auxiliary demand D from upstream or middle (intermediate stage, between the compressor 31 and the condenser 32, etc.) of the reliquefaction unit 30 having a problem in operation.

As described above, in this embodiment, as described in the first embodiment, while reducing the number of installations of the reliquefaction unit 30 , it is possible to secure the processing stability of the boil-off gas.

4 is a conceptual diagram of a gas processing system according to a fourth embodiment of the present invention.

Referring to FIG. 4 , in the gas processing system 1 according to the fourth embodiment of the present invention, the fuel tank 11 and related components can be made compact.

Specifically, in this embodiment, the boil-off gas of the fuel tank 11 is provided to be supplied to the auxiliary consumer D independently of the fuel supply unit 20 . In this case, a boil-off gas branch line L40 for delivering boil-off gas from the fuel tank 11 to the auxiliary consumer D may be provided.

Since the fuel tank 11 is configured to receive the boil-off gas liquefied in the re-liquefaction unit 30 while storing the liquefied gas to be supplied as fuel, the fuel tank 11 corresponds to the BOG processing capacity of the re-liquefaction unit 30 . ) can be determined.

That is, when the BOG processing capacity of the reliquefaction unit 30 is increased, the capacity of the fuel tank 11 also increases. /Operating costs are a problem.

Therefore, the present embodiment utilizes the auxiliary consumer D so as to cover the increase in the processing capacity of the reliquefaction unit 30 even if the capacity of the fuel tank 11 is not expanded. Specifically, the reliquefaction unit 30 delivers the boil-off gas upstream or downstream of the condenser 32 to the fuel tank 11 , the boil-off gas or the condenser 32 delivered from the downstream of the condenser 32 to the fuel tank 11 . BOG flowing toward the fuel tank 11 from the upstream of ) may be supplied to the auxiliary consumer D through the BOG branch line L40.

In this embodiment, the amount of BOG that can be digested by the downstream part of the reliquefaction unit 30 in the system can be increased, so that the fuel tank 11 is prevented from expanding despite the increase in the throughput of the reliquefaction unit 30. can

In this embodiment, the auxiliary consumer D may receive the boil-off gas in the fuel tank 11 and the boil-off gas delivered to the fuel tank 11 before being condensed in the re-liquefaction unit 30, or alternatively, the auxiliary consumer ( D) may consume liquid BOG delivered to the fuel tank 11 after being condensed in the reliquefaction unit 30 or liquid BOG supplied from the fuel tank 11 to the fuel supply unit 20 .

That is, the boil-off gas branch line L40 can be variously modified if it is possible to reduce the storage load of the fuel tank 11 downstream of the reliquefaction unit 30 .

5 is a conceptual diagram of a gas processing system according to a fifth embodiment of the present invention.

Referring to FIG. 5 , the gas processing system 1 according to the fifth embodiment of the present invention is for reducing the storage capacity of the fuel tank 11 similarly to the fourth embodiment, except that the boil-off gas branch line ( The connection point of L40) may be different from FIG. 4 .

Specifically, in this embodiment, the reliquefaction unit 30 delivers the liquefied BOG to the fuel tank 11 , but some of the BOG flowing toward the fuel tank 11 is assisted independently of the fuel supply unit 20 . It can be supplied to the demand (D).

At this time, in order to satisfy the required pressure and the required temperature of the auxiliary consumer D, the boil-off gas branch line L40 may include a pressure control valve (not shown) and a vaporizer (not shown). For example, the boil-off gas (20 bar, liquid at around 35 degrees Celsius) liquefied in the reliquefaction unit 30 is reduced to about 5 bar by the pressure control valve (temperature drop occurs when the pressure is reduced), and then around 30 degrees Celsius in the vaporizer It can be heated and supplied to the auxiliary demand (D).

Of course, the above configuration can be changed according to the requirements of the auxiliary consumer (D), and furthermore, when the auxiliary consumer (D) consumes liquid liquefied gas, the vaporizer and the like may be omitted.

The reliquefaction unit 30 may distribute the boil-off gas downstream of the condenser 32 to the fuel tank 11 and the fuel supply unit 20, and the boil-off gas downstream of the condenser 32 is converted into the fuel tank 11 and the fuel supply unit ( 20), it may be branchedly supplied to the auxiliary demander (D) on the boil-off gas supply line (L11), which is a point before being distributed to (20).

Alternatively, it is also possible that the boil-off gas branch line L40 extends from the boil-off gas supply line L11 toward the fuel tank 11 to the auxiliary demander D on the boil-off gas delivery line L12.

As described in the first embodiment, the present embodiment and the fourth embodiment are provided with an auxiliary consumer D that consumes at least a portion of the boil-off gas transferred from the reliquefaction unit 30 to the fuel tank 11 as described in the first embodiment. Likewise, even if the processing capacity of the reliquefaction unit 30 is increased and the number of installations of the reliquefaction unit 30 is reduced, stable BOG treatment can be guaranteed.

6 is a conceptual diagram of a gas processing system according to a sixth embodiment of the present invention.

Referring to FIG. 6 , in the gas processing system 1 according to the sixth embodiment of the present invention, the liquefied gas may be branched from the fuel recovery unit 40 to the auxiliary demander D.

Specifically, the fuel recovery unit 40 transfers the high-temperature liquefied gas discharged from the propulsion engine E to the high-pressure pump 21 , and transfers some of the liquefied gas flowing toward the high-pressure pump 21 to the fuel supply unit 20 . It is provided to supply to the auxiliary demanding source (D) independently of the To this end, the liquefied gas branch line L50 is branched from the liquefied gas recovery line L30 and may be extended to the auxiliary consumer D.

The auxiliary consumer (D) of this embodiment is the same as described in the previous embodiment, but the auxiliary consumer (D) of this embodiment may be provided to process the liquefied gas mixed with lubricating oil, unlike the previous embodiment.

The fuel recovery unit 40 includes a cooler 41 that cools the high-temperature liquefied gas discharged from the propulsion engine E and delivers it to the high-pressure pump 21 , the liquefied gas branch line L50 is the It can branch upstream.

That is, the liquefied gas branch line L50 allows the liquefied gas flowing from the upstream of the cooler 41 to the high-pressure pump 21 to be branched and supplied to the auxiliary consumer D. This is to omit or minimize the load required to heat the liquefied gas in order to meet the required temperature of the auxiliary demand (D).

In addition, a pressure control valve (not shown) may be provided in the liquefied gas branch line L50. The pressure control valve may reduce the pressure of the liquefied gas discharged from the propulsion engine (E) and decompressed by the pressure reducing valve according to the required pressure of the auxiliary consumer (D). Of course, when the pressure reduction degree of the pressure reducing valve provided in the fuel recovery unit 40 corresponds to the required pressure of the auxiliary consumer D, the pressure control valve may be omitted.

The fuel recovery unit 40 may supply at least a portion of the high-temperature liquefied gas discharged from the propulsion engine E to the auxiliary consumer D, and deliver the remainder to the high-pressure pump 21 without separate cooling. That is, the fuel recovery unit 40 of the present embodiment may omit the cooler 41 . This is because, as most of the recovered liquefied gas is consumed by the auxiliary consumer D, the remaining amount is mixed with the liquefied gas of the fuel supply unit 20 even if it is not cooled, so that the vaporization concern can be resolved.

Furthermore, the fuel recovery unit 40 may deliver all of the recovered liquefied gas to the auxiliary demand destination D, and it is also possible not to deliver the liquefied gas to the high-pressure pump 21 . In this case, the liquefied gas recovery line L30 may not be connected to the fuel supply unit 20 .

As such, in this embodiment, by allowing at least a portion of the surplus liquefied gas recovered from the propulsion engine (E) to be consumed by the auxiliary consumer (D), provision for the management of the recovered liquefied gas can be minimized or omitted, and the system The overall efficiency can be increased.

The present invention encompasses all embodiments generated by a combination of at least two or more of the above embodiments, or a combination of at least one or more of the above embodiments and known techniques, in addition to the embodiments described above.

Although the present invention has been described in detail through specific examples, it is intended to describe the present invention in detail, and the present invention is not limited thereto. It will be clear that the transformation or improvement is possible.

All simple modifications or changes of the present invention fall within 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 handling system 10: cargo tank
11: fuel tank 12: transfer pump
13: in-tank heater 14: pressure rise unit
20: fuel supply 21: high pressure pump
22: heat exchanger 30: reliquefaction unit
31: compressor 32: condenser
33: intercooler 34: aftercooler
40: fuel recovery unit 41: cooler
42: collection tank 43: knockout drum
L10: BOG discharge line L11: BOG supply line
L12: BOG delivery line L13: BOG recovery line
L20: Liquefied gas supply line L30: Liquefied gas recovery line
L40: BOG branch line L50: Liquefied gas branch line
E: Propulsion engine D: Auxiliary demand

Claims (5)

a plurality of storage tanks provided to store n types of liquefied gas, respectively;
a fuel supply unit for supplying the liquefied gas of the storage tank to the propulsion engine;
a plurality of re-liquefaction units for liquefying the boil-off gas generated in the storage tank; and
and a fuel recovery unit for recovering the liquid surplus liquefied gas discharged from the propulsion engine,
The plurality of re-liquefaction units,
n are provided, and when a problem occurs in the operation of any one of the re-liquefaction units, some of the boil-off gas is processed by the normally operating re-liquefaction unit, and the rest is supplied and processed by auxiliary demanders,
The fuel supply unit,
a high-pressure pump for pressurizing liquefied gas according to the required pressure of the propulsion engine; and
A heat exchanger for adjusting the temperature of the liquefied gas according to the required temperature of the propulsion engine,
The fuel recovery unit,
a cooler for cooling the high-temperature liquefied gas discharged from the propulsion engine and transferring it to the high-pressure pump;
a collection tank that separates the liquefied gas recovered from the propulsion engine and transfers the liquid to the high-pressure pump; and
and a knockout drum configured to receive the liquefied gas of the gaseous phase branched from the collection tank and separate impurities. According to claim 1, wherein the auxiliary demand,
At least one of a boiler for burning boil-off gas, a gas combustion device, or a generator, a gas treatment system. According to claim 1, wherein the re-liquefaction unit,
A compressor for compressing BOG in multiple stages, a condenser for liquefying the compressed BOG, and an intercooler that divides BOG liquefied in the condenser to exchange heat with each other and transfers a gaseous phase of the heat-exchanged BOG to some of the intermediate stages of the compressor and an aftercooler provided at the rest of the intermediate stages of the compressor and cooling the boil-off gas using a refrigerant provided separately from the boil-off gas. The method of claim 1, wherein the plurality of re-liquefaction units,
When a problem occurs in the operation of the condenser of any one of the reliquefaction units, some of the boil-off gas is treated with the reliquefaction unit operating normally, and the rest is supplied to the auxiliary demander in the upstream or middle of the reliquefaction unit having a problem in operation. processing, gas processing system. A ship having the gas treatment system of any one of claims 1 to 4.

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