KR102649335B1 - Gas treatment system and ship having the same - Google Patents

Abstract

The present invention relates to a gas processing system and a ship including the same, comprising: a liquefied gas tank storing liquefied gas, which is heavy hydrocarbon or ammonia; A high-pressure pump that delivers the liquefied gas from the liquefied gas tank to the propulsion engine; A heat exchanger that changes the temperature of the liquefied gas; A condenser that liquefies the boil-off gas generated in the liquefied gas tank and transfers it to the liquefied gas supplied to the high-pressure pump; A liquefied gas supply line that supplies liquefied gas from the liquefied gas tank to the propulsion engine and is provided with the heat exchanger and the high pressure pump; And a liquefied gas recovery line that delivers excess liquefied gas returned from the propulsion engine 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 processing system and a vessel incorporating the same.

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

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

Since the boiling point of liquefied petroleum gas is around -50°C, liquefied petroleum gas carriers to transport liquefied petroleum gas must maintain a temperature lower than this. Therefore, storage tanks that store liquefied petroleum gas use low-temperature steel (Low Temperature Carbon Steel and Nickel Steel) that is resistant to low temperatures, and liquefied petroleum gas carriers are also equipped with re-liquefaction facilities.

In the past, these liquefied petroleum gas carriers generated propulsion by operating engines using diesel oil. However, diesel oil generates harmful components such as nitrogen oxides (NOx), sulfur oxides (SOx), and carbon dioxide (CO2) during the combustion process in marine propulsion engines, and these harmful components are released into the atmosphere, causing the problem of polluting the environment. there is.

Therefore, in recent years, the development of engines that run using liquefied petroleum gas and the development of various systems for supplying liquefied petroleum gas to the engine have been continuously conducted to significantly reduce the pollution level of the exhaust compared to the case of using diesel oil. there is.

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

A gas processing system according to an embodiment of the present invention includes a liquefied gas tank storing liquefied gas, which is heavy hydrocarbon or ammonia; A high-pressure pump that delivers the liquefied gas from the liquefied gas tank to the propulsion engine; A heat exchanger that changes the temperature of the liquefied gas; A condenser that liquefies the boil-off gas generated in the liquefied gas tank and transfers it to the liquefied gas supplied to the high-pressure pump; A liquefied gas supply line that supplies liquefied gas from the liquefied gas tank to the propulsion engine and is provided with the heat exchanger and the high pressure pump; And a liquefied gas recovery line that delivers excess liquefied gas returned from the propulsion engine to the high pressure pump.
Specifically, the liquefied gas recovery line extends from the propulsion engine, is provided with a pressure reducing valve to reduce the pressure of the liquid liquefied gas discharged from the propulsion engine, and passes through the inside of the propulsion engine to remove the lubricant used in the propulsion engine. The excess mixed liquid liquefied gas can be delivered to the liquefied gas supply line upstream of the high pressure pump to be re-introduced to the propulsion engine.
Specifically, a collection tank that collects the liquefied gas in the liquefied gas recovery line and delivers the liquid phase to the high pressure pump; And it may further include a knockout drum that receives the liquefied gas from the collection tank and filters out impurities.
Specifically, the liquefied gas recovery line is provided with a cooler that cools the excess liquefied gas returned from the propulsion engine, and the collection tank can collect the liquefied gas between the pressure reducing valve and the cooler.
Specifically, the liquefied gas supply line may further include a liquefied gas branch line connected to the liquefied gas recovery line from downstream of the high pressure pump.
A ship according to an embodiment of the present invention has the above gas processing system.

The gas processing system according to the present invention and the ship including the same can reduce environmental pollution and increase energy efficiency by using liquefied petroleum gas as a propulsion fuel, beyond the conventional system that used only diesel oil.

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

The objectives, 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 this specification, when adding reference numbers to components in each drawing, it should be noted that identical components are given the same number as much as possible even if they are shown in different drawings. Additionally, in describing the present invention, if it is determined that a detailed description of related known technologies may unnecessarily obscure the gist of the present invention, the detailed description will be omitted.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. For reference, in this specification, the liquefied gas is a heavy hydrocarbon, which may be LPG (propane, butane, etc.), but is not limited to this, and is forcibly liquefied for storage because its boiling point is lower than room temperature, and all substances with calorific value (propylene, ammonia, etc.) can encompass.

Also, please note that in this specification, liquefied gas/evaporated gas is not necessarily limited to liquid or gas phase due to its name.

The present invention includes a vessel equipped with a gas processing system 1 described below. At this time, a ship is a concept that includes gas carriers, merchant ships that transport non-gas cargo or people, FSRUs, FPSOs, bunkering vessels, offshore plants, etc. However, please note that it may be a liquefied petroleum gas carrier as an example.

Although not shown in the drawings of the present invention, a pressure sensor (PT), a temperature sensor (TT), etc. can of course be provided at an appropriate location without limitation, and the measured values by each sensor are used in the operation of the configurations described below. It can be used in a variety of 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 configured to store 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 component for supplying liquefied gas, which may be collectively referred to as a liquefied gas supply unit, and a compressor 12 as a component for processing boil-off gas. , may include an evaporation gas treatment unit such as a condenser 13. Additionally, this embodiment includes a collection tank 50, which can be collectively referred to as a liquefied gas recovery unit.

The cargo tank 10 is a plurality of cargo tanks 10 provided on board a ship that is a liquefied gas carrier. Of course, if the ship is a type other than a gas carrier, tanks or containers may be added separately onboard or outboard.

The cargo tank 10 is a tank that stores liquefied gas in a low-temperature liquid form at atmospheric pressure, and various insulation structures may be added to the walls to prevent evaporation of the liquefied gas. Additionally, the cargo tank 10 may be a membrane-type tank or an independent tank, and its shape or specifications are not limited.

A transfer pump (not shown) may be provided to discharge the liquefied gas in the cargo tank 10 to the outside. The transfer pump may be provided inside the cargo tank 10 and may be of 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 intended for cargo transportation, and two cargo pumps (unloading pump, stripping pump, etc., not shown) for unloading cargo are provided for each cargo tank 10. In addition to the cargo pump, at least one cargo tank 10 uses the liquefied gas stored therein as fuel for a propulsion engine (E) (ME-LGI) or a power generation engine (DFDE, not shown). A transfer pump may be added. For reference, in this specification, the propulsion engine (E) is sufficient as a configuration to propel a ship, and can be interpreted as any configuration that can generate propulsion directly or indirectly by consuming liquefied gas, such as a turbine, fuel cell, etc., rather than an engine. .

For example, when there are four cargo tanks (10), the liquefied gas stored in cargo tank number 4 (10), which is close to the engine room where the propulsion engine (E) is accommodated, can be used as fuel for the propulsion engine (E), and for this purpose, 4 A transfer pump can be provided only in the cargo tank 10.

Since the liquefied gas stored in the cargo tank 10 naturally evaporates due to external heat penetration, evaporation gas is generated in the cargo tank 10. Boil-off gas can also be used as fuel for the propulsion engine (E), and for this purpose, an evaporation gas discharge line (L10) that discharges evaporation gas 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 a vapor main line for delivering evaporated gas and a liquid main line for delivering liquefied gas. At this time, the vapor main and liquid main may be provided to connect at least two of the cargo tanks 10 to each other.

For reference, the vapor main and liquid main are connected to lines penetrating the dome (not shown) provided in the cargo tank 10, and the lines penetrating the dome are lines that discharge/recover liquefied gas or boil-off gas. You can.

Therefore, the flow direction in the vapor main/liquid main can be either a direction from the inside of the cargo tank 10 toward the outside or a direction from the outside of the cargo tank 10 toward the inside.

The cargo tank 10 may be provided in plural numbers to each store at least two types of liquefied gases (propane, butane, propylene, etc.) that mainly contain heavy hydrocarbons. For example, the cargo tank 10 may include a first cargo tank 10 storing a first type of liquefied gas, and a second cargo tank 10 storing a second type of liquefied gas. The cargo tank 10 can store propane, the second cargo tank 10 can store butane, etc.

The boil-off gas in the cargo tank 10 is liquefied through the condenser 13. When the liquefied boil-off gas is configured to return to the cargo tank 10, the condenser 13 is at least stored in the cargo tank 10. It must be equipped with the same type of liquefied gas (additional backup is required). That is, if 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 must be provided to match the number of condensers 13.

However, in this embodiment, the boil-off gas liquefied by the condenser 13 is not returned to the cargo tank 10 but is transferred to the fuel tank 20, etc., so that the cargo tank 10 stores two or more types of liquefied gas. Even if provided, the number of installed condensers 13 can be reduced to less than the number of types of liquefied gas. This will be explained again below.

The evaporation gas in the cargo tank 10 is discharged to the condenser 13 through the evaporation gas discharge line L10 and can be liquefied in the condenser 13 by heat exchange/decompression of the refrigerant. Thereafter, the liquefied boil-off gas is delivered to the fuel tank 20 or the high pressure pump 40 described later, but is not returned to the cargo tank 10.

Therefore, the storage amount of the cargo tank 10 may decrease as the evaporative gas is discharged, but as the discharged evaporative gas is used as fuel for the propulsion engine (E), Since the emission of liquefied gas supplied to the propulsion engine (E) will be reduced, it will not cause unexpected cargo loss.

Although not shown in the drawing in this embodiment, a liquefied gas transmission 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 in the cargo tank 10 is delivered to the fuel tank 20 through the liquefied gas transmission line. The liquefied gas delivery line may be provided to extend from the liquid main connecting the plurality of cargo tanks 10 to each other.

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

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

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

The compressor 12 may be composed of multiple stages, may be composed of three stages as shown in the drawing, or may be provided with various stages. In addition, the compressors 12 may be installed in parallel on the boil-off gas discharge line L10 so that they can back up each other.

The compressor 12 can deliver the compressed boil-off gas to the condenser 13 so that it can be liquefied, or it can be delivered to the fuel tank 20 filled with an appropriate amount of liquefied gas. 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 inside.

The condenser 13 liquefies the boil-off gas generated in the cargo tank 10. The evaporation gas can be liquefied using a refrigerant, or it is also possible to use decompression without refrigerant heat exchange.

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

When a plurality of cargo tanks 10 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, this embodiment allows different types of boil-off gases to be integrated and delivered to one condenser 13, thereby reducing the number of installed condensers 13.

However, when equipped to return the liquefied boil-off gas to the cargo tank 10, a situation may occur in which the liquefied propane is returned to the cargo tank 10 storing butane, thereby deteriorating the quality of the liquefied gas, in this embodiment. The liquefied boil-off gas may not be delivered to the cargo tank 10, but may be delivered to the fuel tank 20 or the high pressure pump 40 to be later consumed by the propulsion engine (E).

That is, in this embodiment, the condenser 13 delivers the liquefied boil-off gas to the fuel tank 20 or the liquefied gas supplied from the fuel tank 20 to the high pressure pump 40, but does not deliver it to the cargo tank 10. By being provided so as not to do so, one condenser 13 can be allocated to a plurality of cargo tanks 10 storing different types of liquefied gas.

For this purpose, 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) may be connected to the fuel tank (20). The connected evaporation gas return line (L13) may be branched.

At this time, the condenser 13 can deliver the liquefied boil-off gas to the fuel tank 20 according to the demand of the propulsion engine (E) compared to the amount of boil-off gas generated in the cargo tank 10. Specifically, when the amount of boil-off gas generated is greater than the required amount of the propulsion engine (E), the condenser 13 allows at least the excess of the liquefied boil-off gas to be delivered to the fuel tank 20 through the boil-off gas return line (L13). .

This flow control may be implemented through various valves that can be provided in each line.

The fuel tank 20 stores 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 cargo tank 10, which is an independent type (SPB type, MOSS type) or membrane type that stores a large amount of liquefied gas at atmospheric pressure, and an independent type (Type) that stores liquefied gas at high pressure. C, pressure vessel type).

At this time, the fuel tank 20 can store the liquefied gas above the critical pressure (for example, about 18 bar) or below the critical pressure (for example, about 8 bar), and is stored inside or outside the wall to prevent evaporation of the liquefied gas. An insulation structure may be provided on at least one side.

The fuel tank 20 can be mounted on the upper deck of a ship and is provided to be supported on the upper deck through a saddle. The fuel tank 20 may be placed in a position that does not interfere with the components (manifold, etc.) for loading/unloading liquefied gas of the cargo tank 10 on the upper deck and does not block the visibility when sailing the ship. You can. For example, the fuel tank 20 may be provided on the port or starboard side of the bow side of 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 inside to store the cargo tank ( It may be a configuration of a liquefaction function that condenses the boil-off gas generated in 10).

That is, the fuel tank 20 can receive and condense the evaporation gas generated in the cargo tank 10 using the liquefied gas stored therein. To this end, the evaporative gas discharge line L10 extending from the cargo tank 10 may be provided with an evaporative gas transmission line L11 branching from the upstream of the condenser 13 toward the fuel tank 20.

However, in this embodiment, a configuration for returning the condensed liquefied gas from the fuel tank 20 to the cargo tank 10 may not be provided, which means that the propane of the first cargo tank 10 or the second cargo tank 10 As 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, and return to the cargo tank 10 is not desirable. .

The liquefied gas transmission line described above is provided from the cargo tank 10 to the fuel tank 20, and the liquefied gas can be transmitted to the fuel tank 20 by a transfer pump immersed in the cargo tank 10. The liquefied gas stored in the fuel tank 20 can be managed at an appropriate level/pressure in consideration of the operating status of the ship.

The liquefied gas stored in the fuel tank 20 can 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 can pressurize the liquefied gas at 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, a liquefied gas transmission line, an evaporative gas discharge line (L10), and an evaporative gas transmission line (L11) are provided from the cargo tank (10) to the fuel tank (20), and the liquefied gas is provided from the fuel tank (20) to the propulsion engine (E). 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). The liquefied gas return line (L21) recovers the excess liquefied gas to the fuel tank (20) 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). can play a role.

Alternatively, the liquefied gas return line (L21) allows the liquefied gas pressurized by the low pressure pump 21 to reflow into the fuel tank 20 after being discharged from the fuel tank 20, thereby increasing the internal pressure of the fuel tank 20. You can implement functions that enhance it. Therefore, the fuel tank 20 can maintain a high internal pressure to minimize the generation of boil-off gas within the fuel tank 20.

However, in the present invention, the fuel tank 20 can be omitted, and in this case, the cargo tank 10 and the propulsion engine (E) can be directly connected by the liquefied gas supply line (L20). In addition, at least two types of boil-off gases supplied to the condenser 13 through the boil-off gas 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 can increase or decrease the temperature of the liquefied gas, it may also be referred to as a fuel conditioner.

For example, during the initial operation of this embodiment, since the flow rate of 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 stable operation, the heat exchanger 30 (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 can control the temperature of the liquefied gas below the boiling point of the liquefied gas to prevent the gaseous liquefied gas from flowing into the high pressure pump 40.

In addition, the heat exchanger 30 is connected to the high pressure pump 40, taking into account that the lubricating oil used in the propulsion engine (E) is mixed with the liquefied gas returned from the propulsion engine (E) through the liquefied gas recovery line (L30). The temperature of the incoming liquefied gas can be adjusted to a temperature higher than the temperature at which the lubricating oil does not freeze.

That is, the heat exchanger 30 provided upstream of the high pressure pump 40 collects the 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 gases are 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 lubricant.

The heat exchanger 30 can implement heat exchange with liquefied gas using various heat exchange media. For example, the heat exchange media may be sea water, fresh water, glycol water, exhaust gas, etc., but is not limited thereto.

The high pressure pump 40 delivers liquefied gas from the cargo tank 10 or 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, the temperature of which has been 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 high pressure pumps 40 may be provided in parallel to back up each other as shown in the drawing.

The high pressure pump 40 may introduce liquefied gas into the liquid phase in order to suppress the occurrence of cavitation during the pressurization process. As explained above, if the heat exchanger 30 is provided upstream of the high pressure pump 40, unlike the drawing, the temperature of the liquefied gas can be controlled by taking the above matters into account.

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 can also respond to the pressure of liquefied gas recovered from the propulsion engine (E).

A filter (not shown) may be provided downstream of the high-pressure pump 40 to filter out impurities, and the filter may be additionally provided upstream of the low-pressure pump 21 as shown in the drawing.

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, the fuel supply valve and the pressure reducing valve provided in the liquefied gas recovery line (L30) ( (not shown) may be composed of one train and may be referred to as a fuel valve train (FVT).

The collection tank 50 collects some of the liquefied gas returned from the propulsion engine (E). Unlike commercial engines (ME-GI, It has a structure that discharges.

This is because, unlike in the case of gas phase, fine control of the fuel supply amount is not easy in the case of liquid phase, and excess fuel is generated as the propulsion engine (E) receives a sufficient amount of liquid 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 a liquefied gas that corresponds to the required pressure of the propulsion engine (E). While it has a temperature/pressure (for example, around 45 bar, over 50 degrees Celsius), lubricating oil used in the propulsion engine (E) may be mixed inside the liquefied gas.

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

Therefore, the liquefied gas recovery line (L30), which is connected to the propulsion engine (E) and allows the surplus liquefied gas to be recovered, transfers the surplus liquefied gas returned from the propulsion engine (E) to the high pressure pump (40) rather than the cargo tank (10). It can be delivered to and re-introduced into the propulsion engine (E).

The liquefied gas recovery line (L30) may be equipped with a pressure reducing valve (not shown). The pressure reducing valve reduces the pressure of liquid liquefied gas. The pressure reducing valve may be a Joule-Thompson valve, and may be provided to form a fuel supply train (FVT) together with the fuel supply valve as described above. This pressure reducing valve can reduce the pressure of the high pressure (about 30 to 50 bar) liquefied gas recovered from the propulsion engine (E) to match the suction pressure of the high pressure pump (40).

The collection tank 50 may be provided by branching 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) ) The liquefied gas collection line (L31) may be extended from the collection tank 50.

At this time, the liquefied gas collection line (L31) extends from the liquefied gas recovery line (L30) between the pressure reducing valve and a cooler (not shown) to be described later and is connected to the collection tank (50), and also connects the cooler to the collection tank (50). It can be joined to the upstream liquefied gas recovery line (L30). That is, the liquefied gas collection line (L31) may be 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 and liquid. Since cavitation problems may occur when gaseous liquefied gas flows into the high pressure pump (40), the present invention provides gas-liquid separation while the liquefied gas flowing along the liquefied gas recovery line (L30) passes through the collection tank (50) as needed. Thus, it is possible to block the inflow of gaseous liquefied gas into the high pressure pump 40.

That is, the collection tank 50 collects the liquefied gas in 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, etc. diverged from the collection tank 50 may be transferred to the knockout drum 51. The knockout drum 51 can receive the liquefied gas recovered from the propulsion engine (E) from the collection tank 50 and filter out impurities (lubricating oil, etc.) contained in the liquefied gas.

A liquefied gas processing line (L32) may be connected to the knockout drum 51 in the collection tank 50, and the liquefied gas processing line (L32) may be used to control the collection tank (L32) in addition to the gaseous liquefied gas separated from the collection tank 50. The liquid liquefied gas delivered from 50) to the liquefied gas recovery line (L30) can be delivered to the knockout drum (51).

The knockout drum 51 separates 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 similar to the collection tank 50.

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

The knockout drum 51 heats the liquefied gas mixed with lubricating oil with a heating unit, discharges the liquefied gas through a vent mast (not shown), etc., and the lubricating oil can be drained from the bottom and treated (recycled).

A cooler (not shown) may be provided in the liquefied gas recovery line (L30). The cooler may be installed downstream of the point where the liquefied gas collection line (L31) joins the liquefied gas recovery line (L30), and cools the liquefied gas decompressed in the pressure reducing valve so that it flows into the high pressure pump (40) in liquid form. . The cooler can utilize an unlimited variety of refrigerants and can cool the liquefied gas below the boiling point of the depressurized liquefied gas.

Since cooling by the cooler can be done considering mixing with the liquefied gas delivered from the fuel tank 20 to the high pressure pump 40, the cooler cools the liquefied gas to a temperature somewhat higher than the boiling point of the depressurized liquefied gas. Control is also possible.

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

The liquefied gas pressurized by the high pressure pump 40 may join the liquefied gas recovery line (L30). For this purpose, 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), together with the liquefied gas recovery line (L30), can perform the function of returning the liquefied gas discharged from the high pressure pump (40) to the high pressure pump (40). This is similar to what was 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), thereby preventing vaporization in the liquefied gas recovery line (L30). can be suppressed.

The vent mast (not shown) releases substances that must be vented to the outside between the cargo tank 10 and the propulsion engine E into the atmosphere. The vent mast is provided on the deck of a ship and has a certain height to protect the crew on the deck.

The vent mast can be connected not only to the collection tank 50 or the knockout drum 51, but also to the evaporative gas discharge line (L10), the liquefied gas supply line (L20), and the fuel tank (20). Through this, the vent mast protects the system by implementing external emissions during normal operation or emergency situations such as shutdown of the propulsion engine (E).

In addition, the vent mast can discharge purging gas to the outside when purging the evaporation gas discharge line (L10) and the liquefied gas supply line (L20). At this time, the purging gas may be nitrogen gas or inert gas.

In this way, in this embodiment, the evaporation gas generated in the cargo tank 10 is not returned to the cargo tank 10, but is delivered to the fuel tank 20 or directly supplied to the propulsion engine (E) through the high pressure pump 40. By providing so, even if a plurality of cargo tanks 10 storing different types of liquefied gas are provided, one condenser 13 can be allocated to at least two types of cargo tanks 10, so that the condenser 13 The number of installed units can be reduced.

Although the present invention has been described in detail through specific examples, this is for the purpose of specifically explaining the present invention, and the present invention is not limited thereto, and can be understood by those skilled in the art within the technical spirit of the present invention. It would be clear that modifications and improvements are 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 processing 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: Evaporative gas discharge line
L11: boil-off gas delivery line L12: boil-off gas supply line
L13: Evaporative gas 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)

A liquefied gas tank storing liquefied gas, which is heavy hydrocarbon or ammonia;
A high-pressure pump that delivers the liquefied gas from the liquefied gas tank to the propulsion engine;
A condenser that liquefies the boil-off gas generated in the liquefied gas tank and transfers it to the liquefied gas supplied to the high-pressure pump;
A liquefied gas supply line that supplies liquefied gas from the liquefied gas tank to the propulsion engine and is provided with the high pressure pump; and
It includes a liquefied gas recovery line that delivers surplus liquefied gas returned from the propulsion engine to the high pressure pump,
The liquefied gas recovery line passes through the interior of the propulsion engine and transfers excess liquid liquefied gas mixed with the lubricant used in the propulsion engine to the liquefied gas supply line upstream of the high pressure pump to re-introduce it to the propulsion engine. Gas processing system that makes it possible. The method of claim 1, wherein the liquefied gas recovery line,
A gas processing system that extends from the propulsion engine and is provided with a pressure reducing valve that reduces the pressure of liquid liquefied gas discharged from the propulsion engine. According to claim 2,
A collection tank that collects the liquefied gas in the liquefied gas recovery line and delivers the liquid to the high pressure pump; and
A gas processing system further comprising a knockout drum that receives the liquefied gas from the collection tank and filters out impurities. The method of claim 3, wherein the liquefied gas recovery line,
A cooler is provided to cool the excess liquefied gas returned from the propulsion engine,
The collection tank is,
A gas processing system that collects liquefied gas between the pressure reducing valve and the cooler. According to claim 1,
A gas processing system further comprising a liquefied gas branch line connected from the liquefied gas supply line to the liquefied gas recovery line downstream of the high pressure pump. According to claim 1,
A gas processing system further comprising a heat exchanger provided in the liquefied gas supply line to change the temperature of the liquefied gas. A vessel having the gas processing system according to any one of claims 1 to 6.