KR102324848B1 - 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 cargo tank for storing liquefied gas as cargo containing heavy hydrocarbons or ammonia as a main component; a fuel tank for storing liquefied gas as fuel to be supplied to the propulsion engine; a high-pressure pump for delivering the liquefied gas of the cargo tank or the fuel tank to a propulsion engine; and a condenser for liquefying the boil-off gas generated in the cargo tank, wherein the condenser transfers the liquefied boil-off gas to the fuel tank or the liquefied gas supplied from the fuel tank to the high-pressure pump.

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 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 reliquefaction 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 operated using liquefied petroleum gas and the development of various systems for supplying liquefied petroleum gas to the engine have been continuously 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 processing system according to an aspect of the present invention, a cargo tank for storing liquefied gas mainly composed of heavy hydrocarbons or ammonia as cargo; a fuel tank for storing liquefied gas as fuel to be supplied to the propulsion engine; a high-pressure pump for delivering the liquefied gas of the cargo tank or the fuel tank to a propulsion engine; and a condenser for liquefying the boil-off gas generated in the cargo tank, wherein the condenser transfers the liquefied boil-off gas to the fuel tank or the liquefied gas supplied from the fuel tank to the high-pressure pump.

Specifically, the condenser may deliver the liquefied BOG to the fuel tank according to the required amount of the propulsion engine compared to the amount of BOG generated in the cargo tank.

Specifically, it further comprises a compressor for compressing the boil-off gas discharged from the cargo tank, the compressor may deliver the compressed boil-off gas to the condenser or the fuel tank.

Specifically, the cargo tank includes a first cargo tank for storing a first type of liquefied gas, and a second cargo tank for storing a second type of liquefied gas, the condenser, evaporation of the first cargo tank The gas or boil-off gas of the second cargo tank is liquefied and delivered to the high-pressure pump or the fuel tank, but may not be delivered to the cargo tank.

Specifically, a boil-off gas discharge line for transferring the boil-off gas generated in the cargo tank to the condenser and provided with the compressor; a boil-off gas delivery line branched from the downstream of the compressor from the boil-off gas discharge line and connected to the fuel tank; a boil-off gas supply line for transferring the boil-off gas liquefied in the condenser to the high-pressure pump; and a boil-off gas return line branched from the boil-off gas supply line and connected to the fuel tank.

Specifically, a low-pressure pump for transferring the liquefied gas of the fuel tank to the high-pressure pump; a liquefied gas supply line for supplying liquefied gas from the fuel tank to the propulsion engine and provided with the heat exchanger and the high-pressure pump; a liquefied gas recovery line for transferring the surplus liquefied gas returned from the propulsion engine to the high-pressure pump; a collection tank that collects the liquefied gas of the liquefied gas recovery line and delivers the liquid to the high-pressure pump; and a knockout drum for receiving liquefied gas from the collection tank and filtering impurities.

A ship according to an aspect of the present invention may be a liquefied gas carrier having the gas processing system.

The gas treatment system according to the present invention and a ship including the same can use liquefied petroleum gas as a propulsion fuel, away 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 an 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.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. For reference, in the present specification, the liquefied gas may be LPG (propane, butane, etc.) as heavy hydrocarbons, but is not limited thereto, and any substance (propylene, ammonia, etc.) can include

In addition, it should be noted that liquefied gas/evaporated gas in the present specification is not necessarily limited to liquid or gaseous due to the name.

The present invention includes a ship equipped with a gas treatment system 1 described below. At this time, a ship is a concept that includes all gas carriers, merchant ships carrying 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 measurement value by each sensor is dependent on the operation of the components described below. It can be used in various ways without limitation.

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

Referring to FIG. 1 , the gas processing system 1 according to the first embodiment of the present invention includes a cargo tank 10 and a fuel tank 20 as components for storing liquefied gas, and these components are liquefied gas It may be collectively referred to as a storage unit.

In addition, this embodiment includes a heat exchanger 30 and a high-pressure pump 40 as a configuration for supplying liquefied gas, which may be collectively referred to as a liquefied gas supply unit, and a compressor 12 as a configuration for processing boil-off gas. , and may include a boil-off gas processing unit such as the condenser 13 . In addition, the present embodiment includes a collection tank 50 and the like, which may be collectively referred to as a liquefied gas recovery unit.

The cargo tank 10 is a plurality of cargo tanks 10 provided in the ship of a liquefied gas carrier. Of course, if the vessel is a vessel other than the gas carrier, it may be a tank or container that is separately added to the inside or the outside of the vessel.

The cargo tank 10 is a tank for storing liquefied gas as a low-temperature liquid at atmospheric pressure, and various insulating structures may be added to the wall to prevent vaporization of the liquefied gas. Also, the cargo tank 10 may be a membranous tank or an independent tank, and the shape or specification thereof is not limited.

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

However, the transfer pump may be provided only in some of the plurality of cargo tanks 10 . The cargo tank 10 is basically for the purpose of transporting cargo, and two cargo pumps (unloading pumps, stripping pumps, etc., not shown) for unloading cargo are provided for each cargo tank 10. , at least one cargo tank 10 is to use the liquefied gas stored therein as fuel for a propulsion engine (E) (ME-LGI) or a power generation engine (DFDE, not shown), in addition to the cargo pump A transfer pump may be added. For reference, in this specification, the propulsion engine (E) suffices as long as a configuration for propelling a ship is sufficient, and it 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. .

For example, when the cargo tank 10 is four, the liquefied gas stored in the cargo tank No. 4 close to the engine room in which the propulsion engine E is accommodated may be used as the fuel of the propulsion engine E, and for this purpose, 4 A transfer pump may be provided only in the burner cargo tank 10 .

Since the liquefied gas stored in the cargo tank 10 is naturally evaporated by external heat penetration, boil-off gas is generated in the cargo tank 10 . BOG may also be used as fuel of the propulsion engine E, and for this purpose, a BOG discharge line L10 for discharging BOG may be provided in the cargo tank 10. Alternatively, the boil-off gas may be liquefied and returned, which will be described in detail below.

The plurality of cargo tanks 10 may be provided with vapor main, which is a line for delivering boil-off gas, and liquid main, which is a line for delivering liquefied gas. At this time, the vapor main and the liquid main may be provided to connect at least two or more of the cargo tank 10 to each other.

For reference, vapor main and liquid main are connected to lines passing through the dome (signs not shown) provided in the cargo tank 10, and the lines passing through the dome are lines for discharging/recovering liquefied gas or boil-off gas. can

Therefore, the flow direction in the vapor main/liquid main is a direction from the inside of the cargo tank 10 to the outside, or a direction from the outside to the inside of the cargo tank 10 is possible.

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 cargo tank 10 may include a first cargo tank 10 for storing a first type of liquefied gas and a second cargo tank 10 for storing a second type of liquefied gas, and the first The 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 through the condenser 13, and when configured so that the liquefied boil-off gas is returned to the cargo tank 10, the condenser 13 is at least stored in the cargo tank 10. It should be provided as much as the type of liquefied gas (additional backup is required). That is, when the cargo tank 10 stores two types of liquefied gas, at least three condensers 13 must be provided. In addition, since the compressor 12 is provided as a set corresponding to the condenser 13 , a plurality of compressors 12 should also be provided according to the number of condensers 13 .

However, in this embodiment, by transferring the boil-off gas liquefied by the condenser 13 to the fuel tank 20, etc. without returning to the cargo tank 10, so that the cargo tank 10 stores two or more kinds of liquefied gas. Even if provided, the number of installations of the condenser 13 can be reduced to less than or equal to the number of types of liquefied gas. This will be described again below.

BOG of the cargo tank 10 may be discharged to the condenser 13 through the BOG discharge line L10, and may be liquefied by refrigerant heat exchange/pressure reduction in the condenser 13 . Thereafter, the liquefied BOG is delivered to the fuel tank 20 or a high-pressure pump 40 to be described later, but is not returned to the cargo tank 10 .

Accordingly, the cargo tank 10 may reduce the amount of storage as much as the BOG is discharged, but as the discharged BOG is used as fuel for the propulsion engine E, etc., the BOG is discharged from the cargo tank 10 due to the discharge of BOG. Since the emission of liquefied gas supplied to the propulsion engine (E) will be reduced, it does not cause an unexpected cargo loss.

Although this embodiment is not shown in the drawings, a liquefied gas delivery line may be provided from the cargo tank 10 to the fuel tank 20 so that the liquefied gas of the cargo tank 10 can also be supplied to the propulsion engine E. , the liquefied gas of the cargo tank 10 is delivered to the fuel tank 20 through the liquefied gas delivery line. The liquefied gas delivery line may be provided to extend from the liquid main interconnecting the plurality of cargo tanks 10 .

On the boil-off gas discharge line L10 through which the boil-off gas of the cargo tank 10 is discharged, the drum 11, the compressor 12, and the condenser 13 may be provided. The drum 11 is a gas-liquid separation component for filtering droplets among the boil-off gas discharged from the cargo tank 10 , and the droplets may be provided to be returned to the cargo tank 10 .

The drum 11 may protect the compressor 12 by preventing droplets from flowing into the compressor 12 , and the drum 11 may be omitted depending on the type of the compressor 12 .

The compressor 12 compresses the boil-off gas discharged from the cargo tank 10 . The compressor 12 may increase the boiling point of the liquefied gas by compression, thereby increasing the liquefaction efficiency in the condenser 13 to be described below.

The compressor 12 may be configured in multiple stages, may be configured in three stages as shown in the drawing, or may be provided in various stages other than the compressor 12 . In addition, the compressor 12 may be provided in parallel on the boil-off gas discharge line L10 so as to be able to back up each other.

The compressor 12 may deliver the compressed boil-off gas to the condenser 13 so that it can be liquefied, or it may deliver it to the fuel tank 20 in which the liquefied gas is filled in an appropriate amount. In the former case, the boil-off gas liquefied in the condenser 13 is supplied to the fuel tank 20 or the high-pressure pump 40, and in the latter case, the high-pressure boil-off gas is directly injected into the fuel tank 20 and the fuel tank 20 It can be cooled and liquefied by the liquefied gas in it.

The condenser 13 liquefies the boil-off gas generated in the cargo tank 10 . A refrigerant may be used for liquefaction of BOG, or a reduced pressure may be used without heat exchange with the refrigerant.

As described above, the cargo tank 10 may be provided in plurality to respectively store at least two types of liquefied gas, and the condenser 13 may be provided to liquefy all of the different types of boil-off gas.

When a plurality of cargo tanks 10 for storing different types of liquefied gas are provided, it may be common to provide a condenser 13 corresponding to the type of liquefied gas. However, in the present embodiment, different types of BOG are integrated and delivered to one condenser 13 , thereby reducing the number of condensers 13 installed.

However, when provided to return the liquefied boil-off gas to the cargo tank 10, the liquefied propane is returned to the cargo tank 10 for storing butane, which may cause a situation in which the quality of the liquefied gas is reduced, this embodiment can be such that the liquefied boil-off gas is not delivered to the cargo tank 10, but is delivered to the fuel tank 20 or the high-pressure pump 40 to be consumed by the propulsion engine E and the like.

That is, in this embodiment, the condenser 13 delivers the liquefied BOG to the liquefied gas supplied from the fuel tank 20 or the fuel tank 20 to the high-pressure pump 40, but not to the cargo tank 10. By being provided so as not to, it is possible to allocate one condenser 13 for a plurality of cargo tanks 10 for storing different types of liquefied gas.

To this end, a boil-off gas supply line L12 may be provided in the liquefied gas supply line L20 upstream of the high-pressure pump 40 from the condenser 13 , and the boil-off gas supply line L12 is connected to the fuel tank 20 . The connected BOG return line L13 may be branched.

At this time, the condenser 13 may deliver the liquefied BOG to the fuel tank 20 according to the required amount of the propulsion engine E compared to the amount of BOG generated in the cargo tank 10 . Specifically, when the amount of BOG generated is greater than the required amount of the propulsion engine E, the condenser 13 may allow at least a surplus of the liquefied BOG to be delivered to the fuel tank 20 through the BOG return line L13. .

Such flow control may be implemented through valves that may be provided in various ways in each line.

The fuel tank 20 stores the liquefied gas as fuel to be supplied to the propulsion engine (E). The fuel tank 20 may be of the same or different type as the stand-alone (SPB type, MOSS type) or membrane-type cargo tank 10 for storing a large amount of liquefied gas at atmospheric pressure, and a stand-alone type (Type) for storing liquefied gas at high pressure C, pressure vessel type).

At this time, the fuel tank 20 may store the liquefied gas above the critical pressure (eg, around 18 bar), or store it below the critical pressure (eg, around 8 bar), inside or outside the wall to prevent vaporization of the liquefied gas. A heat insulating structure may be provided on at least one side of the.

The fuel tank 20 may be mounted on the upper deck in a ship, and is provided to be supported on the upper deck through a saddle. The fuel tank 20 does not interfere with the components (manifold, etc.) for loading/unloading the liquefied gas of the cargo tank 10 on the upper deck. can For example, the fuel tank 20 may be provided on the port side or starboard side of the bow on the upper deck. In this case, the fuel tank 20 may be referred to as a deck tank.

The fuel tank 20 may be configured to temporarily store liquefied gas between the cargo tank 10 and the propulsion engine E, and the fuel tank 20 uses the liquefied gas stored therein, the cargo tank ( It may be a configuration of a liquefaction function to condense the boil-off gas generated in 10).

That is, the fuel tank 20 may receive and condense the boil-off gas generated in the cargo tank 10 using the liquefied gas stored therein. For this purpose, the boil-off gas discharge line L10 extending from the cargo tank 10 may be provided with a boil-off gas delivery line L11 branched from the upstream of the condenser 13 toward the fuel tank 20 .

However, in this embodiment, the configuration for returning the condensed liquefied gas from the fuel tank 20 to the cargo tank 10 may not be provided, which is propane of the first cargo tank 10 or the second cargo tank 10 . This is because as the butane of the butane is delivered to the fuel tank 20 , the first type of boil-off gas and the second type of boil-off gas are mixed in the fuel tank 20 , so the return to the cargo tank 10 is undesirable. .

The above-described liquefied gas delivery line is provided from the cargo tank 10 to the fuel tank 20 , and the liquefied gas may be delivered to the fuel tank 20 by a transfer pump immersed in the cargo tank 10 . The liquefied gas stored in the fuel tank 20 may be managed at an appropriate level/pressure in consideration of the operating state of the vessel.

The liquefied gas stored in the fuel tank 20 may be transferred from the fuel tank 20 to the propulsion engine E through the low pressure pump 21 . At this time, the low pressure pump 21 may be provided inside or outside the fuel tank 20 , and may pressurize the liquefied gas to a pressure lower than the required pressure of the propulsion engine E.

A liquefied gas supply line L20 may be provided from the fuel tank 20 to the propulsion engine E, and the low pressure pump 21 may be provided in the liquefied gas supply line L20. That is, from the cargo tank 10 to the fuel tank 20, a liquefied gas delivery line, a boil-off gas discharge line (L10) & a boil-off gas delivery line (L11) are provided, and from the fuel tank 20 to the propulsion engine (E) is liquefied. A gas supply line L20 is provided.

A liquefied gas return line L21 may be provided downstream of the low pressure pump 21 in the liquefied gas supply line L20. When the flow rate delivered to the propulsion engine E through the low pressure pump 21 exceeds the required flow rate of the propulsion engine E, the liquefied gas return line L21 recovers the surplus liquefied gas to the fuel tank 20. can play a role

Alternatively, the liquefied gas return line L21 allows the liquefied gas pressurized by the low-pressure pump 21 after being discharged from the fuel tank 20 to re-introduce into the fuel tank 20, thereby increasing the internal pressure of the fuel tank 20. It can be implemented to enhance the function. Accordingly, the fuel tank 20 maintains a high internal pressure to minimize the generation of boil-off gas in the fuel tank 20 .

However, in the present invention, the fuel tank 20 may be omitted, and in this case, the cargo tank 10 and the propulsion engine E may be directly connected by the liquefied gas supply line L20. In addition, at least two kinds of BOG supplied to the condenser 13 through the BOG discharge line L10 may be condensed and then transferred to the high-pressure pump 40 and not returned to the cargo tank 10 .

The heat exchanger 30 is provided downstream of the low pressure pump 21 to change the temperature of the liquefied gas. Since the heat exchanger 30 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 30 can lower the temperature of the liquefied gas, and when entering into stable operation, the heat exchanger (30) can increase the temperature of the liquefied gas.

The heat exchanger 30 may be provided downstream of the high-pressure pump 40 as shown in the drawing, or unlike the drawing, the heat exchanger 30 may be provided upstream of the high-pressure pump 40 . In the latter case, the heat exchanger 30 may control the temperature of the liquefied gas below the boiling point of the liquefied gas so that the gaseous liquefied gas does not flow into the high-pressure pump 40 .

In addition, the heat exchanger 30, considering that the lubricating oil used in the propulsion engine (E) is mixed in the liquefied gas returned through the liquefied gas recovery line (L30) from the propulsion engine (E), the high-pressure pump (40) It is possible to adjust the temperature of the liquefied gas above the temperature at which the lubricant does not freeze in the liquefied gas flowing in.

That is, the heat exchanger 30 provided upstream of the high-pressure pump 40 is liquefied gas delivered from the fuel tank 20 to the high-pressure pump 40 and the liquefied gas recovered from the propulsion engine E and delivered to the high-pressure pump 40 . When the gas is mixed, the temperature of the liquefied gas can be controlled so that it is below the boiling point of the liquefied gas and above the freezing point of the lubricating oil.

The heat exchanger 30 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, etc., but is not limited thereto.

The high-pressure pump 40 delivers the liquefied gas of the cargo tank 10 or the fuel tank 20 to the propulsion engine (E). The high-pressure pump 40 is provided on the liquefied gas supply line L20 extending from the fuel tank 20 to the propulsion engine E.

The high-pressure pump 40 pressurizes the liquefied gas whose temperature is controlled by the heat exchanger 30 to the pressure required by the propulsion engine (E). The pressure required by the propulsion engine (E) may be 20 to 50 bar, but may vary depending on the specifications of the propulsion engine (E).

The type of the high-pressure pump 40 is not particularly limited, and a plurality of the high-pressure pumps 40 may be provided in parallel to be able to back up each other as shown in the drawing.

In the high-pressure pump 40, liquefied gas may be introduced into the liquid phase in order to suppress the occurrence of cavitation during the pressurization process. Unlike the drawing, when the heat exchanger 30 is provided upstream of the high-pressure pump 40, the temperature of the liquefied gas can be controlled in consideration of the above as described above.

The pressure of the liquefied gas sucked into the high-pressure pump 40 may correspond to the pressure of the liquefied gas discharged by the low-pressure pump 21 . It may also correspond to the pressure of the liquefied gas recovered from the propulsion engine (E).

A filter (not shown) for filtering impurities may be provided downstream of the high pressure pump 40 , and the filter may be additionally provided upstream of the low pressure pump 21 as shown in the figure.

In addition, a fuel supply valve (not shown) may be provided downstream of the high-pressure pump 40 in the liquefied gas supply line L20, and at this time, a fuel supply valve and a pressure reducing valve provided in the liquefied gas recovery line L30 ( (not shown) may be referred to as a fuel valve train (FVT) as it is composed of one train.

The collection tank 50 collects some of the liquefied gas returned from the propulsion engine (E). Unlike commercial engines (ME-GI, XDF, etc.) that receive and consume LNG in the gas phase, the propulsion engine (E) (ME-LGI, etc.) in the present invention receives and consumes LPG, etc. in liquid phase and consumes surplus liquid fuel. It has a structure that emits

This is because, unlike the gas phase, fine control of the fuel supply amount is not easy in the liquid phase, and the propulsion engine E receives a sufficient amount of the liquid fuel, thereby generating an excess of fuel.

However, the liquefied gas recovered from the propulsion engine (E) is not the liquefied gas before flowing into the propulsion engine (E), but is a liquefied gas that has passed through the inside of the propulsion engine (E), and is While having temperature/pressure (for example, around 45 bar, 50 degrees or more), lubricating oil used in the propulsion engine (E) may be mixed inside the liquefied gas.

Therefore, since the lubricating oil is mixed in the surplus liquefied gas recovered from the propulsion engine E, it is preferable not to deliver the recovered liquefied gas to the cargo tank 10 in order to prevent cargo contamination.

Therefore, the liquefied gas recovery line (L30) connected to the propulsion engine (E) so that the surplus liquefied gas is recovered is the surplus liquefied gas returned from the propulsion engine (E), not the cargo tank (10), but a high-pressure pump (40) It can be transmitted to the propulsion engine (E) to be re-introduced.

A pressure reducing valve (not shown) may be 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-Thompson valve, and as described above, it may be provided to constitute a fuel supply train (FVT) together with the fuel supply valve. This 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 (40).

The collection tank 50 may be branched from the liquefied gas recovery line L30 connected from the propulsion engine E to the liquefied gas supply line L20 upstream of the high-pressure pump 40, and the liquefied gas recovery line L30 ) to the collection tank 50, the liquefied gas collection line (L31) may be extended.

At this time, the liquefied gas collection line L31 extends from between the pressure reducing valve and a cooler (not shown) to be described later in the liquefied gas recovery line L30 and is connected to the collection tank 50, and also from the collection tank 50 to the cooler. It may be merged into an upstream liquefied gas recovery line (L30). That is, the liquefied gas collection line L31 is provided partially in parallel with the liquefied gas recovery line L30 and may be provided with a collection tank 50 .

The collection tank 50 separates the recovered liquefied gas into gas-liquid. Since a cavitation problem may occur when gaseous liquefied gas flows into the high-pressure pump 40, in the present invention, the liquefied gas flowing along the liquefied gas recovery line L30 passes through the collection tank 50 as needed, while gas-liquid separation. Thus, it is possible to block the inflow of the high-pressure pump 40 of the gaseous liquefied gas.

That is, the collection tank 50 collects the liquefied gas of the liquefied gas recovery line L30 and delivers only the liquid liquefied gas to the high-pressure pump 40 , thereby ensuring stable operation of the high-pressure pump 40 .

The gaseous liquefied gas branched from the collection tank 50 may be delivered to the knockout drum 51 . The knockout drum 51 may receive the liquefied gas recovered from the propulsion engine E from the collection tank 50 and filter impurities (lubricating oil, etc.) contained in the liquefied gas.

A liquefied gas processing line L32 may be connected from the collection tank 50 to the knockout drum 51, and the liquefied gas processing line L32 is a collection tank ( The liquefied gas in the liquid phase delivered from the 50 ) to the liquefied gas recovery line L30 may be transferred to the knockout drum 51 .

The knockout drum 51 separates the lubricating oil from the liquefied gas introduced therein. Specifically, the knockout drum 51 discharges the liquefied gas in the gas phase and the lubricating oil in the liquid phase. That is, the knockout drum 51 implements a gas-liquid separation function similarly to the collection tank 50 .

However, the knockout drum 51 may use a heating unit such as tracing in order to promote vaporization of the liquefied gas, and the tracing is configured to use a medium such as steam or seawater as a heat source or to heat using electricity can be

The knockout drum 51 may heat liquefied gas mixed with lubricating oil by a heating unit, discharge the liquefied gas through a vent mast (not shown) or the like, and drain and process (recycle) the lubricating oil from the bottom.

A cooler (not shown) may be provided in the liquefied gas recovery line L30. The cooler may be provided downstream of the point where the liquefied gas collection line L31 joins in the liquefied gas recovery line L30, and cools the liquefied gas pressure-reduced in the pressure reducing valve so that it flows into the high-pressure pump 40 in a liquid phase. . The cooler can utilize various refrigerants that are not limited, and can cool the liquefied gas below the boiling point of the depressurized liquefied gas.

Since the cooling by the cooler can be made in consideration of the mixing with the liquefied gas transferred from the fuel tank 20 to the high-pressure pump 40, the cooler cools the liquefied gas to a temperature slightly higher than the boiling point of the depressurized liquefied gas. Control is also possible.

The liquid (or a state close to the liquid) cooled by the cooler is mixed upstream of the high-pressure pump 40 in the liquefied gas supply line (L20) through the liquefied gas recovery line (L30), and the liquefied gas recovery line ( A mixer (not shown) may be provided at a point where L30 is connected to the liquefied gas supply line L20.

The liquefied gas pressurized by the high-pressure pump 40 may be joined to the liquefied gas recovery line L30. To this end, a liquefied gas branch line L22 is provided downstream of the high-pressure pump 40 from the liquefied gas supply line L20 toward the liquefied gas recovery line L30.

The liquefied gas branch line L22 may perform a function of returning the liquefied gas discharged from the high-pressure pump 40 to the high-pressure pump 40 together with the liquefied gas recovery line L30 . This is similar to that described in the liquefied gas return line (L21).

In addition, the liquefied gas branch line (L22) injects liquefied gas at a higher pressure than the liquefied gas recovered along the liquefied gas recovery line (L30) into the liquefied gas recovery line (L30), and vaporizes in the liquefied gas recovery line (L30) can suppress.

A vent mast (not shown) discharges a material to be vented from the cargo tank 10 to the outside between the propulsion engine E to the atmosphere. The vent mast is provided on the deck of the ship and has a certain height to protect the crew on the deck.

The vent mast may be connected from the collection tank 50 or the knockout drum 51 , and may also be connected to the boil-off gas discharge line L10 , the liquefied gas supply line L20 , the fuel tank 20 , and the like. Through this, the vent mast protects the system by implementing external emission in emergency situations such as normal operation or shutdown of the propulsion engine (E).

In addition, the vent mast may discharge the purging gas to the outside during purging of the boil-off gas discharge line (L10) and the liquefied gas supply line (L20). In this case, the purging gas may be nitrogen gas or an inert gas.

As such, in this embodiment, the boil-off gas generated in the cargo tank 10 is delivered to the fuel tank 20 without returning to the cargo tank 10 or directly supplied to the propulsion engine E via the high-pressure pump 40 . By providing so that, even if a plurality of cargo tanks 10 for storing different types of liquefied gas are provided, one condenser 13 can be allocated for at least two kinds of cargo tanks 10, so the condenser 13 can reduce the number of installations.

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

All simple modifications and variations 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: Drum 12: Compressor
13: condenser 20: fuel tank
21: low pressure pump 30: heat exchanger
40: high pressure pump 50: collection tank
51: knockout drum L10: boil-off gas discharge line
L11: BOG delivery line L12: BOG supply line
L13: BOG return line L20: Liquefied gas supply line
L21: Liquefied gas return line L22: Liquefied gas branch line
L30: Liquefied gas recovery line L31: Liquefied gas collection line
L32: Liquefied gas processing line E: Propulsion engine

Claims (7)

Cargo tanks for storing liquefied gas as heavy hydrocarbons or ammonia as cargo;
a fuel tank for storing liquefied gas as fuel to be supplied to the propulsion engine;
a high-pressure pump for delivering the liquefied gas of the cargo tank or the fuel tank to a propulsion engine;
a heat exchanger for changing the temperature of the liquefied gas; and
It includes a condenser for liquefying the boil-off gas generated in the cargo tank,
The condenser is
The liquefied boil-off gas is delivered to the fuel tank or the liquefied gas supplied from the fuel tank to the high-pressure pump,
a liquefied gas supply line for supplying liquefied gas from the fuel tank to the propulsion engine and provided with the heat exchanger and the high-pressure pump;
a liquefied gas recovery line for transferring the surplus liquefied gas returned from the propulsion engine to the high-pressure pump;
a collection tank that collects the liquefied gas of the liquefied gas recovery line and delivers the liquid to the high-pressure pump; and
The gas treatment system according to claim 1, further comprising: a knockout drum for receiving liquefied gas from the collection tank and filtering impurities. According to claim 1, wherein the condenser,
Gas treatment system, characterized in that for delivering the liquefied BOG to the fuel tank according to the required amount of the propulsion engine compared to the amount of BOG generated in the cargo tank. The method of claim 1,
Further comprising a compressor for compressing the boil-off gas discharged from the cargo tank,
The compressor, Gas treatment system, characterized in that for delivering the compressed boil-off gas to the condenser or the fuel tank. The method of claim 1,
The cargo tank includes a first cargo tank for storing a first type of liquefied gas, and a second cargo tank for storing a second type of liquefied gas,
The condenser liquefies the boil-off gas of the first cargo tank or the boil-off gas of the second cargo tank and delivers it to the high-pressure pump or the fuel tank, gas processing system, characterized in that it is not delivered to the cargo tank. 4. The method of claim 3,
a boil-off gas discharge line for transferring the boil-off gas generated in the cargo tank to the condenser and provided with the compressor;
a boil-off gas delivery line branched from the downstream of the compressor from the boil-off gas discharge line and connected to the fuel tank;
a boil-off gas supply line for transferring the boil-off gas liquefied in the condenser to the high-pressure pump; and
The gas treatment system further comprising a boil-off gas return line branched from the boil-off gas supply line and connected to the fuel tank. delete A ship characterized in that it is a liquefied gas carrier having the gas treatment system according to any one of claims 1 to 5.

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