KR102323465B1 - Gas Treatment System and Ship having the same - Google Patents

Abstract

To a gas processing system according to the present invention and a ship including the same, the gas processing system of the present invention includes: a first fuel supply line for supplying boil-off gas generated in a cargo tank to a customer; a boil-off gas compression unit provided in the first fuel supply line and compressing boil-off gas; a boil-off gas recovery line for branching the boil-off gas that has passed through the boil-off gas compression unit; a buffer tank condensing the boil-off gas branched through the boil-off gas recovery line; and a boil-off gas cooler for cooling the boil-off gas generated in the buffer tank.

Description

Gas Treatment System and Ship including the same

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

A ship is a means of transport that carries a large amount of minerals, crude oil, natural gas, or thousands of containers or more and sails the ocean. move to

Such a ship generates thrust by driving an engine or a gas turbine, etc. In this case, the engine uses oil fuel such as gasoline or diesel to move the piston so that the crankshaft is rotated by the reciprocating motion of the piston, and the shaft connected to the crankshaft is rotated to drive the propeller, while the gas turbine burns fuel with compressed air, and uses the temperature/pressure of the combustion air to rotate turbine blades to generate power and transmit power to the propeller.

However, recently, an LNG fuel supply method in which LNG is used as a fuel to drive a consumer such as an engine or a turbine is used in an LNG carrier that transports liquefied natural gas, a type of liquefied gas, and LNG is a clean fuel. And since the reserves are more abundant than petroleum, the method of using LNG as a fuel for consumers is being applied to ships other than LNG carriers.

However, in contrast to the conventional case of using oil fuel such as diesel, LNG is continuously vaporized in the LNG cargo tank while the LNG is transported by an LNG carrier in the case of using LNG, which is gas fuel, and evaporated in the LNG cargo tank. Boil-off gas (BOG) is generated, and the generated boil-off gas increases the pressure in the cargo tank and accelerates the flow of liquefied gas according to the fluctuations of the ship, thereby causing structural problems. There are a number of problems that need to be solved, such as the need to suppress

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 store boil-off gas naturally occurring in a cargo tank in a ship using liquefied gas stored in the cargo tank as a fuel in a buffer tank. It is intended to provide a gas processing system capable of efficiently processing boil-off gas by processing using the , and a ship including the same.

In addition, an object of the present invention is to reduce the pressure and temperature inside the buffer tank by cooling the boil-off gas in the buffer tank and/or the boil-off gas recovered to the buffer tank through the boil-off gas recovery line with a boil-off gas cooler, An object of the present invention is to provide a gas treatment system capable of solving an operational problem caused by an increase in buffer tank pressure, and a ship including the same.

A gas processing system according to an aspect of the present invention includes: a first fuel supply line for supplying boil-off gas generated in a cargo tank to a consumer; a boil-off gas compression unit provided in the first fuel supply line and compressing boil-off gas; a boil-off gas recovery line for branching the boil-off gas that has passed through the boil-off gas compression unit; a buffer tank condensing the boil-off gas branched through the boil-off gas recovery line; and a boil-off gas cooler for cooling the boil-off gas generated in the buffer tank.

Specifically, it may include a cooling circulation line configured to cool the boil-off gas inside the buffer tank using the boil-off gas cooler.

Specifically, the cooling circulation line may include: a first cooling line for supplying boil-off gas in the buffer tank to the boil-off gas cooler; and a second cooling line for supplying the boil-off gas cooled in the boil-off gas cooler to the buffer tank.

Specifically, it may include a boil-off gas bypass line configured to cool the boil-off gas recovered to the buffer tank through the boil-off gas recovery line using the boil-off gas cooler.

Specifically, the boil-off gas bypass line may have one end connected to the boil-off gas recovery line and the other end connected to the first cooling line.

Specifically, the boil-off gas cooler may be a cryocooler.

Specifically, the buffer tank may be a Type-C pressure tank.

A ship according to another aspect of the present invention is characterized in that it comprises the gas treatment system described above.

A gas treatment system according to the present invention and a ship including the same, in a ship using liquefied gas stored in a cargo tank as a fuel, naturally vaporized BOG and/or forced vaporized BOG supplied from a cargo tank as a fuel of a consumer By using a buffer tank to process the boil-off gas can be efficiently treated.

In addition, the gas treatment system according to the present invention and a ship including the same, by configuring to store in the buffer tank when the boil-off gas naturally generated in the cargo tank is greater than the amount of fuel required by the demand or is temporarily generated in the buffer tank, It is possible to reduce the amount of gas burned by the gas combustion unit or discharged to the outside, thereby preventing unnecessary waste of boil-off gas, and ensuring the pressure stability of the cargo tank.

In addition, the gas treatment system according to the present invention and a ship including the same, configure a buffer tank independently of the flow of supplying liquefied gas as fuel from the cargo tank to the demand, but selectively use the boil-off gas stored in the buffer tank as needed. Unlike a fuel tank as an example for explaining the effect of the present invention that a fuel pump, a fuel vaporizer, etc. must be provided for supplying liquefied gas to the consumer by configuring it to be supplied as the fuel of the consumer, unlike a fuel tank, a peripheral device for supplying liquefied gas fuel can be simplified.

In addition, the gas treatment system and the ship including the same according to the present invention are configured to supply the boil-off gas naturally vaporized in the cargo tank as the main fuel of the consumer, but supply the boil-off gas stored in the buffer tank as an auxiliary fuel of the consumer, Since the buffer tank does not require a fuel pump for supplying liquefied gas fuel, the effective suction head required for driving the fuel pump is different from the fuel tank as an example for explaining the effect of the present invention even if the flow rate and internal pressure of the buffer tank are low. And it is not necessary to consider the problem of fuel supply interruption and cool-down caused by insufficient inlet pressure.

In addition, the gas treatment system according to the present invention and a ship including the same are configured to supply only boil-off gas as the fuel of the consumer without supplying the liquefied gas from the buffer tank as the fuel of the consumer, so that the buffer tank explains the effect of the present invention Unlike the fuel tank as an example for this, it is not necessary to maintain a flow rate and internal pressure within a certain range in order to use the liquefied gas as the fuel of the demand, and thus can be free from maintaining the flow rate and internal pressure of the liquefied gas.

In addition, the gas treatment system according to the present invention and a ship including the same, fill the buffer tank with liquefied gas regardless of the fuel of the consumer so that the boil-off gas inside can be condensed into the liquefied gas and stored, but the filled liquefied gas is By configuring so that it can be returned to the cargo tank when it is necessary to discharge from the buffer tank, such as expansion, the buffer tank from the expansion of liquefied gas compared to the absence of a configuration of discharging liquefied gas from the fuel tank as an example for explaining the effect of the present invention stability can be ensured.

In addition, the gas treatment system according to the present invention and a ship including the same, by cooling the BOG recovered to the buffer tank through the BOG and/or BOG recovery line in the buffer tank with a BOG cooler, It is possible to lower the pressure and temperature, so that the operational problems caused by the increase in the buffer tank pressure can be solved.

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 view for explaining that the BOG cooler is provided in the buffer tank in the gas processing system according to the first to fifth embodiments 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, gas can be used to encompass all substances that are generally stored in a liquid state, such as LPG, ethylene, ammonia, etc., which are forcibly liquefied for storage due to a lower boiling point than room temperature as well as LNG, and have a calorific value.

In addition, the gas may include liquefied gas, naturally vaporized boil-off gas, forced vaporized boil-off gas, and surplus boil-off gas.

However, BOG may mean including liquefied BOG as well as gaseous BOG, and liquefied gas may mean including vaporized liquefied gas as well as liquid BOG.

The present invention includes a ship (S) provided with any one of the gas treatment systems (1, 2, 3, 4, 5) according to various embodiments described below, wherein the ship (S) is a gas carrier, gas Please note that the concept includes all commercial vessels, FSRUs, FLNGs, bunkering vessels, and offshore plants that carry cargo or people, not

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

As shown in Figure 1, the gas processing system 1 according to the first embodiment of the present invention, in a ship (S) using the liquefied gas stored in the cargo tank 10 as a fuel without a separate fuel tank, It may be provided to process the boil-off gas naturally occurring inside the cargo tank 10 in the buffer tank 80 .

Cargo tank 10, one or more installed in the hull of the ship (S) can store liquefied gas as cargo and fuel, any type of known tank such as a membrane type tank or an independent tank can be used.

In general, in the cargo tank, the stored liquefied gas is continuously naturally vaporized to generate boil-off gas (BOG) inside, and the generated boil-off gas increases the pressure in the cargo tank and is liquefied according to the fluctuations of the ship. It is necessary to suppress the generation of boil-off gas because it can accelerate the flow of gas and cause structural problems of the tank.

Accordingly, conventionally, as a method for suppressing and treating boil-off gas in the cargo tank of a ship, the method of discharging the boil-off gas to the outside of the cargo tank to incinerate it, and a re-liquefaction device by discharging the boil-off gas to the outside of the cargo tank The method of returning to the cargo tank after re-liquefaction by the used as or in combination.

In the case of a ship equipped with a boil-off gas re-liquefaction device, the boil-off gas inside the cargo tank is discharged to the outside of the cargo tank to be reliquefied through the re-liquefaction device in order to maintain an appropriate pressure of the cargo tank. At this time, the discharged BOG is reliquefied through heat exchange with a refrigerant cooled to a very low temperature in a reliquefaction apparatus including a refrigeration cycle, for example, nitrogen, mixed refrigerant, and the like, and then returned to the cargo tank.

In the case of a ship equipped with a low-pressure engine propulsion system, the BOG is treated only with a BOG compression unit and heating without installing a reliquefaction facility, and then supplied as fuel to the low-pressure engine to consume BOG. When the amount of BOG is less than the amount of BOG, BOG has no choice but to be burned out in a Gas Combustion Unit (GCU) or thrown into the atmosphere (venting).

In addition, although a vessel equipped with a reliquefaction facility and a low-pressure engine can process boil-off gas by the reliquefaction facility, the control of the entire system is complicated due to the complexity of the operation of the reliquefaction apparatus using nitrogen gas and a considerable amount of power this is consumed

As described above, in order to suppress and process boil-off gas in the cargo tank of a ship, it is necessary to use a gas combustion unit or use a reliquefaction device. In the case of using a liquefaction apparatus, the system becomes large, and the reality is that considerable installation and maintenance costs are incurred.

Therefore, there is a need to continuously research and develop a system and method for efficiently processing liquefied gas, including boil-off gas, which is naturally generated from the cargo tank. In this embodiment, naturally from the cargo tank 10 A system including a buffer tank 80 is provided as a method of efficiently processing liquefied gas including generated boil-off gas, which will be described in detail below.

The gas treatment system 1 of this embodiment is a cargo tank 10, a demand 20a, a pump 30, a forced vaporizer 40a, a gas-liquid separator 50, a boil-off gas compression unit 60a, a boil-off gas cooler 70 , a buffer tank 80 , a pressure reducing means 90 , and a gas combustion unit 100 .

The cargo tank 10 may store liquefied gas. The liquefied gas stored in the cargo tank 10 and the boil-off gas naturally generated therein may be used as fuel for the consumer 20a.

BOG naturally vaporized in the cargo tank 10 may be supplied to the consumer 20a through the first fuel supply line L1 in which the gas-liquid separator 50 and the BOG compression unit 60a are provided. In addition, the liquefied gas stored in the cargo tank 10 and used as fuel may be supplied to the consumer 20a through the second fuel supply line L2 in which the pump 30 and the forced carburetor 40a are provided. . In addition, in addition to the above-described first fuel supply line (L1) and second fuel supply line (L2), the boil-off gas replenishment line (L3), the boil-off gas recovery line (L4), the first liquefied gas recovery line (L5), liquefied gas filling line (L6), second liquefied gas recovery line (L7), boil-off gas discharge line (L8), etc. All gas lines, such as a valve for controlling the flow rate of liquefied gas or boil-off gas (not shown) ) may be provided, and a plurality of check valves (not shown) for preventing the reverse flow of liquefied gas or boil-off gas may be provided, of course.

The liquefied gas supplied from the cargo tank 10 to the fuel of the consumer 20a does not pass through the buffer tank 80 as will be described later. Of course, this liquefied gas is forcibly vaporized by the forced vaporizer 40a before being supplied to the demander 20a.

In this embodiment, when the BOG naturally generated inside the cargo tank 10 is greater than the amount of fuel required by the demander 20a or is temporarily increased, BOG is stored in the buffer tank for the safety of the cargo tank 10 ( 80) can be recovered and stored. Through this, the gas treatment system 1, the amount of BOG supplied from the cargo tank 10 to the fuel of the demander 20a is greater than the fuel consumption of the consumer 20a, and the remaining BOG is converted into the gas combustion unit 100. ) by reducing the amount burned or discharged to the outside, it is possible to prevent unnecessary waste of boil-off gas, as well as to ensure the pressure stability of the cargo tank (10).

The liquefied gas stored in the cargo tank 10 can be stored by condensing the boil-off gas inside the buffer tank 80 through the liquefied gas filling line L6 branched from the second fuel supply line L2 to the buffer tank ( 80) can be charged. When the liquefied gas charged in the buffer tank 80 expands and acts as a risk factor, etc., when discharge is required, it can be returned from the buffer tank 80 to the cargo tank 10 through the second liquefied gas recovery line (L7). have. Here, the second liquefied gas recovery line (L7), as shown, one end is connected to the lower portion of the buffer tank (80) and the other end is connected to the cargo tank (10), up to the inside of the cargo tank (10) can be extended In addition, the second liquefied gas recovery line (L7), although not shown, the other end is connected to the first liquefied gas recovery line (L5) can be returned to the liquefied gas to the cargo tank (10) of course.

The liquefied gas returned from the buffer tank 80 to the cargo tank 10 through the second liquefied gas recovery line L7, without installing a liquefied gas transfer means such as a pump in the second liquefied gas recovery line L7 It can be restored by free flow by gravity, which is possible by installing the buffer tank 80 on a deck, etc., which is at a higher level than the cargo tank 10 installed in the hull. When the buffer tank 80 is installed at a level similar to that of the cargo tank 10, that is, in the hull, a liquefied gas transfer means such as a pump may be installed in the second liquefied gas recovery line L7 for the return of the liquefied gas. is of course

The customer 20a may mean a device such as an engine installed for propulsion or power generation of the ship S, for example, a MEGI engine, an XDF engine, a DF engine included in DFDE, a DF boiler engine, or a turbine engine. , a power generation engine, and the like.

The consumer 20a is fueled by forcibly vaporized BOG generated by forcibly vaporizing the liquefied gas stored in the cargo tank 10 or naturally vaporized BOG generated by natural vaporizing of the liquefied gas in the cargo tank 10 . can generate power.

In addition, the consumer 20a, when the BOG and/or naturally vaporized BOG from the cargo tank 10 does not reach the BOG consumption of the consumer 20a, the BOG stored in the buffer tank 80 . At least a part of it may be transmitted through the boil-off gas replenishment line (L3) to generate power.

In this embodiment, the customer 20a may be an XDF engine, which is a type of low-pressure engine driven at a low pressure in the range of 10 bar to 20 bar while the methane number needs to be adjusted. Due to the application of the XDF engine, in this embodiment, a low-pressure compressor (LD Compressor) is applied as the boil-off gas compression unit 60a, and a gas-liquid separator 50 having a methane number control function is applied. In this embodiment, although the case of applying the XDF engine as the customer 20a is described, it is not limited thereto, and other low-pressure engines driven at low pressure while needing to adjust the methane number can be applied, of course. In addition, in the present embodiment, the consumer 20a may include a power generation engine that generates electricity in addition to the XDF engine, which is the main engine for propulsion of the ship S, of course.

The pump 30 may be installed inside the cargo tank 10 to pressurize the liquefied gas discharged to the outside, and may be installed in the second fuel supply line L2 extending to the bottom of the cargo tank 10 . have.

The pump 30 may be a fuel pump for compressing and transporting liquefied gas.

The liquefied gas compressed by the pump 30 passes through the forced vaporizer 40a, the gas-liquid separator 50, and the boil-off gas compression unit 60a without going through the buffer tank 80 to be supplied as fuel to the consumer 20a. can In addition, the liquefied gas compressed by the pump 30 is a liquefied gas filling line L6 branched from the second fuel supply line L2 as needed, such as for the purpose of condensing and storing the boil-off gas inside the buffer tank 80 . ) through the buffer tank 80 may be supplied.

The forced vaporizer 40a may be provided in the second fuel supply line L2 and may forcibly vaporize the liquefied gas transferred from the pump 30 .

The forcibly vaporized BOG obtained by forcibly vaporizing the liquefied gas in the forced vaporizer 40a may be merged upstream of the BOG compression unit 60a through the gas-liquid separator 50 without passing through the buffer tank 80 .

The forcibly vaporized BOG contains other components (propane, butane, etc.) in addition to the methane component and contains droplets, so a type of engine that needs to control the methane number is applied as the consumer 20a, and the BOG compression unit As (60a), when a centrifugal compressor of a type in which boil-off gas containing droplets is not allowed to enter is applied, it is necessary to remove droplets while controlling the methane number in order to improve the performance of the consumer 20a and the boil-off gas compression unit 60a. There is, by providing a gas-liquid separator 50 between the forced vaporizer 40a and the boil-off gas compression unit 60a, it can be solved.

In this embodiment, the forced carburetor 40a is an XDF engine, which is a type of low-pressure engine driven at a low pressure in the range of 10bar to 20bar, where the demander 20a is a low-pressure engine, and the BOG compression unit 60a is a low-pressure compressor (LD Compressor), It may be a low pressure vaporizer (LP Vaporizer).

The gas-liquid separator 50 is provided upstream of the BOG compression unit 60a and phase-separates the BOG supplied to the BOG compression unit 60a into a liquid phase and a gaseous phase, and only the gaseous BOG is converted to the BOG compression unit 60a. can be supplied. In addition, the gas-liquid separator 50 may adjust the methane number of the boil-off gas to be supplied to the consumer 20a.

In the gas-liquid separator 50 , the forcibly vaporized boil-off gas obtained by forcibly vaporizing the liquefied gas in the forced vaporizer 40a may be introduced through the second fuel supply line L2 . The forcibly vaporized BOG contains components such as propane and butane in addition to methane, and contains a large amount of droplets, and the methane number can be adjusted and the droplets removed in the gas-liquid separator 50 .

In addition, in the gas-liquid separator 50 , the naturally vaporized boil-off gas in the cargo tank 10 may be introduced through the first fuel supply line L1 . Naturally vaporized BOG is mostly composed of a methane component, but contains some droplets, so that the droplets can be removed in the gas-liquid separator 50 .

In addition, in the gas-liquid separator 50 , the surplus BOG stored in the buffer tank 80 may be introduced through the BOG replenishment line L3 . In this case, the surplus BOG may be introduced into the gas-liquid separator 50 after being decompressed by the pressure reducer 90 provided in the BOG supplementation line L3. The surplus BOG is mostly composed of methane, but contains some droplets, so that the droplets can be removed in the gas-liquid separator 50 .

As described above, the BOG having the methane number adjusted in the gas-liquid separator 50 and the liquid phase removed may be supplied to the BOG compression unit 60a through the first fuel supply line L1.

BOG flowing into the gas-liquid separator 50 includes both naturally vaporized BOG (including surplus BOG) and forced BOG. As described above, the forced BOG contains other components in addition to the methane component. is contained, and all BOG contains droplets, so as in this embodiment, a type of engine that needs to control the methane number as the demander 20a is applied, and the BOG compression unit 60a contains droplets. When a centrifugal compressor of a type that does not allow gas to enter is applied, it is necessary to remove droplets while controlling the methane number using the gas-liquid separator 50 in order to improve the performance of the consumer 20a and the boil-off gas compression unit 60a. have. In particular, since the present embodiment has a structure in which forcibly vaporized BOG obtained by forcibly vaporizing the liquefied gas in the forced vaporizer 40a is merged with the upstream of the BOG compression unit 60a, the gas-liquid separator 50 must be provided. do.

The gas-liquid separator 50 is filled with liquid phase-separated boil-off gas, that is, liquefied gas, which is phase-separated from the boil-off gas, and the filled liquefied gas is recovered to the cargo tank 10 through the first liquefied gas recovery line L5. . The first liquefied gas recovery line L5 has one end connected to the lower portion of the gas-liquid separator 50 , and the other end may extend to the inside of the cargo tank 10 .

The boil-off gas compression unit 60a may mean a pressurization device installed to supply boil-off gas as fuel to the consumer 20a, and may be, for example, a centrifugal compressor, a screw-type compressor, a reciprocating compressor, and the like. The boil-off gas compression unit 60a may be configured in multiple stages as shown, for example, four stages are composed of one set, and two sets are arranged in parallel so that at least one set is selectively operated. can

A cooler (not shown) may be provided between the multi-stage BOG compression units 60a. The cooler lowers the temperature of the boil-off gas raised by the upstream boil-off gas compressor 60a to facilitate the operation of the downstream boil-off gas compressor 60a.

The boil-off gas compression unit 60a may compress the boil-off gas supplied from the gas-liquid separator 50 provided in the first fuel supply line L1 to correspond to the required pressure of the consumer 20a.

In this embodiment, the boil-off gas compression unit 60a is an XDF engine, which is a low-pressure engine of a type that is driven at a low pressure in the range of 10 bar to 20 bar while the demand 20a needs to adjust the methane number, and the boil-off gas in the gas-liquid separator 50 It may be a centrifugal low-pressure compressor (LD Compressor) that compresses at a low pressure without allowing the boil-off gas containing the droplets to enter because it can remove the droplets contained in it.

Downstream of the boil-off gas compression unit (60a), branched from the first fuel supply line (L1) and extended to the buffer tank (80), discharged from the cargo tank (10), at least one stage of the boil-off gas compression unit (60a) A boil-off gas recovery line (L4) for branching some of the boil-off gas compressed by the evaporator may be provided.

The boil-off gas recovery line (L4) is, when the naturally vaporized boil-off gas in the cargo tank 10 is greater than the amount of fuel required by the demander 20a or is temporarily increased, a predetermined flow rate supplied as the fuel of the demander 20a. It serves as a passage through which the surplus BOG except for BOG is recovered and stored in the buffer tank 80 . Although not shown, the BOG recovery line L4 recovers some of the BOG discharged from the cargo tank 10 and compressed by at least one stage of the BOG compression unit 60a to the buffer tank 80. Of course, it can be configured to store.

In addition, a BOG discharge line L8 branched from the first fuel supply line L1 and extending to the gas combustion unit 100 may be provided downstream of the BOG compression unit 60a. BOG discharge line (L8), when the amount of BOG supplied as fuel from the cargo tank 10 is greater than the fuel consumption amount of the consumer 20a, and the surplus BOG can no longer be stored in the buffer tank 80 , serves as a passage through which a portion of the boil-off gas can be burned in the gas combustion unit 100 .

The boil-off gas cooler 70 is provided in the first fuel supply line L1 downstream of the boil-off gas compression unit 60a, and the temperature of the boil-off gas, which is increased while being pressurized by the boil-off gas compression unit 60a, is transferred from the consumer 20a. It can be adjusted to the desired temperature.

In addition, the BOG cooler 70 is a buffer tank ( 80), to the first fuel supply line (L1) upstream rather than the BOG recovery line (L4) branching from the first fuel supply line (L1) and extending to the buffer tank (80) will be prepared

The buffer tank 80 may be manufactured as a type-C pressure tank, and may be installed on the deck of the ship (S). The buffer tank 80 may be installed inside the hull.

The buffer tank 80 branches the naturally vaporized boil-off gas in the cargo tank 10 and/or the forced vaporized boil-off gas obtained by forcibly vaporizing the liquefied gas in the forced vaporizer 40a from the first fuel supply line L1. It can be recovered and stored through the boil-off gas recovery line (L4).

The buffer tank 80 of this embodiment, when the BOG discharged from the cargo tank 10 exceeds the BOG consumption of the consumer 20a, the surplus BOG is delivered through the BOG recovery line L4 and stored And, when the BOG discharged from the cargo tank 10 does not reach the BOG consumption of the consumer 20a, at least a portion of the BOG stored in the BOG supplement line (L3), the BOG compression unit (60a), the second It is possible to supplement the gas delivered to the demander 20a through the first fuel supply line L1.

In addition, in the buffer tank 80, when the BOG discharged from the cargo tank 10 does not reach the BOG consumption of the consumer 20a, although not shown, at least a portion of the BOG stored in the BOG supplement line L3 Of course, it is possible to supplement or indirectly supply the gas delivered to the low demand source 20a, such as a power generation engine, through the required pressure, or directly or indirectly supply the gas to the low required pressure demand 20a through the power generation engine. The boil-off gas replenishment line L3 may serve as a passage through which the boil-off gas stored in the buffer tank 80 can be supplemented with the fuel gas supplied to the consumer 20a.

BOG stored in the buffer tank 80 is BOG at a certain flow rate supplied as fuel of the consumer 20a when the BOG discharged from the cargo tank 10 exceeds the BOG consumption of the consumer 20a. It may be excess boil-off gas except for.

The excess BOG is compressed in the BOG compression unit 60a to correspond to the required pressure of the demander 20a. For example, when the demander 20a is an XDF engine, it evaporates in a pressurized state at a pressure in the range of 10bar to 20bar. It is supplied to the buffer tank 80 through the gas recovery line (L4), and even if the pressure is slightly lowered while passing through the boil-off gas recovery line (L4), it is still stored in the buffer tank 80 with a pressure of about 10 bar. can Since the buffer tank 80 is a Type-C pressure tank and the pressure of the stored surplus BOG is high, the reliquefaction rate of the stored surplus BOG may be higher than that of the non-pressure tank, so it can also function as a reliquefaction. there will be

In this way, by storing the surplus BOG in the buffer tank 80, the amount of burning the surplus BOG by the gas combustion unit 100 or releasing it to the outside can be reduced, thereby preventing unnecessary waste of the BOG. As well as there, it is possible to ensure the pressure stability of the cargo tank (10).

As described above, the buffer tank 80 is, in addition to supplying the boil-off gas naturally vaporized in the cargo tank 10 and/or the liquefied gas stored in the cargo tank 10 as the fuel of the consumer 20a, inside The stored surplus BOG may be supplied as a fuel of the consumer 20a. That is, in the buffer tank 80, when the BOG discharged from the cargo tank 10 does not reach the BOG consumption of the consumer 20a, at least a portion of the stored BOG is supplemented with the gas delivered to the consumer 20a. can do. Of course, when the fuel gas is sufficiently supplied from the buffer tank 80 to the demand 20a, the fuel gas may not be supplied from the cargo tank 10 to the demand 20a.

Since the surplus BOG stored in the buffer tank 80 is stored at a pressure of about 10 bar as described above, it is transferred from the buffer tank 80 to the gas-liquid separator 50 through the BOG supplementation line L3. When supplied, the high pressure of the surplus BOG supplied to the BOG compression unit 60a through the gas-liquid separator 50 is transferred to the BOG compression unit 60a as it is, which may cause a problem, so the pressure reducing means 90 ) should be supplied under reduced pressure.

In addition, the excess BOG stored in the buffer tank 80 may be condensed and stored. The surplus BOG inside the buffer tank 80 may be condensed by being filled with the liquefied gas of the cargo tank 10 through the liquefied gas filling line L6 branched from the second fuel supply line L2. Since the liquefied gas charged in the buffer tank 80 serves to condense the surplus BOG rather than being used as fuel for the consumer 20a, it may be filled in a small amount. You do not have to do.

In addition, when the liquefied gas filled in the buffer tank 80 needs to be discharged from the buffer tank 80, such as when the liquid level of the liquefied gas becomes higher than the set level value or the liquefied gas expands, the second liquefied gas recovery line L7 ) may be returned to the cargo tank 10 from the buffer tank 80 through. Here, the second liquefied gas recovery line (L7), as shown, one end is connected to the lower portion of the buffer tank (80) and the other end is connected to the cargo tank (10), up to the inside of the cargo tank (10) can be extended In addition, the second liquefied gas recovery line (L7), although not shown, the other end is connected to the first liquefied gas recovery line (L5) can be returned to the liquefied gas to the cargo tank (10) of course.

As described above, the buffer tank 80 stores surplus BOG and supplies the surplus BOG as needed, unlike a fuel tank that fills liquefied gas from the cargo tank 10 and supplies it as fuel to the consumer 20a. Since it is configured to be used as the fuel of (20a), it is configured independently of the flow of supplying the liquefied gas as fuel from the cargo tank 10 to the customer 20a.

That is, in this embodiment, the flow of the liquefied gas supplied from the cargo tank 10 to the consumer 20a is a second fuel supply line ( Since it is forcibly vaporized in the forced vaporizer 40a provided in L2) and supplied to the consumer 20a through the gas-liquid separator 50 and the boil-off gas compression unit 60a, it is irrelevant to the buffer tank 80 .

The buffer tank 80 according to the present invention can not only condense and store the surplus boil-off gas remaining after being oversupplied to the consumer 20a by using the liquefied gas, but also convert the liquefied gas inside the cargo tank 10 into the cargo tank 10 . By configuring so as to be returned, the boil-off gas inside the cargo tank 10 is discharged to the outside of the cargo tank 10 to maintain an appropriate pressure of the cargo tank 10 to be reliquefied, or from the cargo tank 10 to the customer 20a ), when the amount of BOG supplied as fuel is greater than the amount of fuel consumed by the consumer 20a, it can serve as a re-liquefaction device for re-liquefying it. For this reason, since the gas treatment system 1 according to the present embodiment includes the buffer tank 80, it is possible to efficiently process excess BOG without installing a reliquefaction apparatus. The gas processing systems 2, 3, 4, and 5 according to other embodiments to be described below also include the buffer tank 8, so that it is not necessary to install a reliquefaction apparatus.

In addition, the buffer tank 80 according to the present invention, the BOG supplied from the cargo tank 10 to the fuel of the demander 20a exceeds the amount of fuel required by the demander 20a. Of course, as necessary, the surplus BOG can be selectively used as a fuel for the consumer 20a, so the gas treatment system 1 including the buffer tank 80 of the present invention is an example for explaining the effect of the present invention It is inevitably different from a gas treatment system including a fuel tank as a fuel tank, and it will be clearer by comparing the fuel tank as an example for explaining the effects of the present invention below.

In general, in a ship having a cargo tank for storing liquefied gas and a fuel tank for storing liquefied gas as fuel, the fuel tank receives the liquefied gas directly from the cargo tank and is charged or charged by bunkering.

The flow configuration for supplying liquefied gas as fuel from the fuel tank to the consumer is forced vaporization by filling the liquefied gas from the cargo tank, pressurizing the filled liquefied gas using a pump, and vaporizing the pressurized liquefied gas with a fuel vaporizer. The generated boil-off gas is produced, and the forcibly vaporized boil-off gas is compressed to correspond to the required pressure of the consumer through the boil-off gas compression unit and supplied to the consumer.

However, as described above, the buffer tank 80 of the present invention is not configured to receive the liquefied gas from the cargo tank 10 and supply it as the fuel of the consumer 20a.

That is, the fuel tank must be equipped with a pump, a fuel carburetor, etc. as a peripheral device for supplying liquefied gas as fuel, but the buffer tank 80 of the present invention is used as a fuel from the cargo tank 10 to the consumer 20a. It is configured independently of the flow for supplying the liquefied gas, and there is no need for a peripheral device for supplying the liquefied gas as fuel, so the operation is relatively simple.

In particular, as is well known, a pump, which is a peripheral device of a fuel tank, has complicated operations, such as having to satisfy an inflow flow rate and an inflow pressure in order to operate without problems.

For example, when the flow rate of the fuel tank is low, it must be replenished from the cargo tank, and at this time, there is a problem that the fuel supply in the fuel tank has to be temporarily stopped. there is trouble

In addition, when the internal pressure of the fuel tank is lowered, more BOG must be supplied from the cargo tank to increase the internal pressure, but the lower internal pressure means that there is not enough BOG in the cargo tank already, and this There is no choice but to wait for natural evaporation or use a pressure generating unit, which causes a problem in that the fuel supply in the fuel tank is temporarily stopped, and there are inconveniences such as having to cool down in order to operate again.

In addition, when the fuel supply is temporarily stopped, a diesel fuel engine can be used, but it causes an exhaust gas environmental problem, so an exhaust gas treatment system must be prepared. is wasted, and if the operation is stopped, the liquefied gas fuel engine has to be operated after cool-down, which is cumbersome.

Since the buffer tank 80 of the present invention does not require a fuel gas pressurization pump, even if the flow rate and internal pressure are low, unlike the above-described fuel tank, the effective suction head and inlet pressure required for driving the pump are not satisfied. It is not necessary to consider fuel supply interruption and cool-down problems, and it can be free from maintaining flow rate and internal pressure.

In addition, the fuel tank has a line for charging liquefied gas from the cargo tank, but there is no line for returning the liquefied gas from the fuel tank to the cargo tank. Although discharge from the tank is impossible, the buffer tank 80 of the present invention can return the liquefied gas filled in the buffer tank to the cargo tank 10 through the second liquefied gas recovery line L7, so that in the fuel tank It is possible to secure the stability of the buffer tank 80 from the expansion of the liquefied gas compared to the case where there is no liquefied gas discharge configuration.

The pressure reducing means 90 reduces the pressure of the surplus BOG stored in the buffer tank 80 and supplies it to the BOG compression unit 60a.

The pressure reducing means 90 may be provided in the boil-off gas replenishment line L3 between the buffer tank 80 and the gas-liquid separator 50 . The pressure reducing means 90 may be an expansion valve such as a Joule-Thompson valve, an expander, or the like.

The reason that the surplus BOG must be supplied by reducing the pressure by the decompression means 90 is that the surplus BOG is supplied to the buffer tank 80 in a compressed state in the BOG compression unit 60a and has a pressure of about 10 bar. surplus BOG supplied to the BOG compression unit 60a through the gas-liquid separator 50 This is because the high pressure of the BOG is transferred to the BOG compression unit 60a as it is, causing problems such as lowering the driving efficiency of the BOG compression unit 60a.

The gas combustion unit 100 may be installed in the BOG discharge line L8 branched from the first fuel supply line L1 downstream of the BOG compression unit 60a, and is higher than the fuel consumption of the consumer 20a. When the amount of BOG supplied as fuel from the cargo tank 10 is large and the surplus BOG can no longer be stored in the buffer tank 80, a part of BOG may be burned. In the present embodiment, since most of the surplus BOG can be stored in the buffer tank 80, the amount of BOG burnt by the gas combustion unit 100 or discharged to the outside can be significantly reduced.

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

Hereinafter, the second embodiment will be described with reference to FIG. 2 , but configurations using the same reference numerals as those of the first embodiment in this embodiment do not necessarily mean the same configuration.

As shown in FIG. 2 , the gas treatment system 2 according to the second embodiment of the present invention is a ship (S) using liquefied gas stored in the cargo tank 10 as fuel without a separate fuel tank being provided. ), it may be provided to process the boil-off gas naturally occurring inside the cargo tank 10 in the buffer tank 80 .

The gas treatment system 2 according to the second embodiment of the present invention includes a cargo tank 10, a customer 20a, a pump 30, a forced vaporizer 40a, a gas-liquid separator 50, a boil-off gas compression unit ( 60a), the boil-off gas cooler 70, the buffer tank 80, the pressure reducing means 90, the gas combustion unit 100, the heat exchanger 110, the condensing structure 120, the pressure generating unit 130 to include can

Here, the cargo tank 10, the consumer 20a, the pump 30, the forced vaporizer 40a, the gas-liquid separator 50, the boil-off gas compression unit 60a, the boil-off gas cooler 70, the buffer tank 80 , the pressure reducing means 90 and the gas combustion unit 100 are the same as or similar to those described in the first embodiment, so detailed descriptions will be omitted, and the heat exchanger 110 which is a component different from the first embodiment of the present invention , the condensing structure 120, the pressure generating unit 130, and only the parts that are changed thereby will be described.

The heat exchanger 110 is connected to a first fuel supply line L1 connecting the cargo tank 10 and the gas-liquid separator 50 and a first fuel supply line L1 downstream of the BOG compression unit 60a. It may be provided in the boil-off gas recovery line (L4) extending to the buffer tank (80).

The heat exchanger 110 is a relatively low-temperature (eg, about -100 ℃ at 1 bar) naturally vaporized BOG, which is supplied to the gas-liquid separator 50 through the first fuel supply line L1, and the customer ( Before being supplied to 20a), heat exchange is made with the surplus BOG supplied to the buffer tank 80 through the BOG recovery line L4 (eg, about 40° C. at 10 bar to 20 bar). At this time, in the heat exchanger 110 , the surplus BOG obtains cooling heat from the naturally vaporized BOG and is cooled and partially reliquefied to be stored in the buffer tank 80 .

The condensing structure 120 is a structure for condensing the surplus BOG flowing into the buffer tank 80 through the BOG recovery line L4 into the liquefied gas filled in the buffer tank 80, so as to be submerged in the liquefied gas. It may be provided near the bottom of the buffer tank 80 .

The condensing structure 120 may be installed at the end of the boil-off gas recovery line L4, and may be formed in a structure capable of delaying the flow of the excess boil-off gas. At this time, the boil-off gas recovery line L4 may further extend from the ceiling to the floor of the buffer tank 80 so that the condensing structure 120 can be installed near the bottom of the buffer tank 80 .

The pressure generating unit 130 may be installed in the buffer tank 80 .

The pressure generating unit 130 is operated when the surplus BOG is supplied from the buffer tank 80 as fuel to the consumer 20a to increase the amount of the surplus BOG while increasing the internal pressure of the buffer tank 80. .

In this embodiment, unlike the first embodiment, the surplus BOG is stored in the buffer tank 80 in a cooled and reliquefied state by the heat exchanger 110 rather than in a gaseous state before being supplied to the consumer 20a. , the amount of stored surplus BOG is inevitably small, and the internal pressure is also lowered, thereby increasing the amount of surplus BOG when it is necessary to supply it as an auxiliary fuel of the consumer 20a. Unit 130 is required.

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

Hereinafter, the third embodiment will be described with reference to FIG. 3 . However, in this embodiment, the same reference numerals as in the first embodiment do not necessarily mean the same configuration.

As shown in FIG. 3 , the gas processing system 3 according to the third embodiment of the present invention is a ship (S) using liquefied gas stored in the cargo tank 10 as fuel without a separate fuel tank being provided. ), it may be provided to process the boil-off gas naturally occurring inside the cargo tank 10 in the buffer tank 80 .

The gas treatment system 3 according to the third embodiment of the present invention includes a cargo tank 10, a demand destination 20a, a pump 30, a forced vaporizer 40a, a first gas-liquid separator 50a, and a second gas-liquid It may include a separator 50b, a boil-off gas compression unit 60a, a boil-off gas cooler 70, a buffer tank 80, a pressure reducing means 90, and a gas combustion unit 100.

Here, the cargo tank 10, the customer 20a, the pump 30, the forced vaporizer 40a, the boil-off gas compression unit 60a, the boil-off gas cooler 70, the buffer tank 80, the pressure reducing means 90. , since the gas combustion unit 100 is the same as or similar to that described in the first embodiment, a detailed description will be omitted, and the first gas-liquid separator 50a and the second gas-liquid separator 50a, which are different components from the first embodiment of the present invention, are omitted. Only the separator 50b and the parts that are changed thereby will be described.

The first gas-liquid separator 50a is provided upstream of the BOG compression unit 60a to phase-separate BOG supplied to the BOG compression unit 60a into a liquid phase and a gaseous phase, and only the BOG compression unit 60a ) can be supplied.

In the first gas-liquid separator 50a, naturally vaporized BOG in the cargo tank 10 may be introduced through the first fuel supply line L1. Naturally vaporized BOG is mostly composed of a methane component, but contains some droplets, so that the droplets can be removed in the first gas-liquid separator 50a.

In addition, the first gas-liquid separator 50a may be connected to the boil-off gas replenishment line L3 so that the surplus BOG stored in the buffer tank 80 can be introduced after being decompressed by the decompression means 90 . The surplus BOG is mostly composed of methane.

In addition, in the first gas-liquid separator 50a, the surplus BOG stored in the buffer tank 80 may be introduced through the BOG replenishment line L3. At this time, the surplus BOG may be introduced into the first gas-liquid separator 50a after being decompressed by the pressure reducer 90 provided in the BOG supplementation line L3. The surplus BOG is mostly composed of methane, but contains some droplets, so that the droplets may be removed in the first gas-liquid separator 50a.

As described above, the BOG from which the liquid phase has been removed in the first gas-liquid separator 50a may be supplied to the BOG compression unit 60a through the first fuel supply line L1.

Naturally vaporized BOG and/or surplus BOG flowing into the first gas-liquid separator 50a contains droplets, and thus BOG including droplets enters as BOG compression unit 60a as in this embodiment. When a centrifugal compressor of a type that does not operate is applied, it is necessary to remove droplets in order to improve the performance of the boil-off gas compression unit (60a). Accordingly, in this embodiment, the first gas-liquid separator 50a must be provided upstream of the BOG compression unit 60a to prevent the introduction of droplets into the BOG compression unit 60a, which is a centrifugal compressor.

In addition, the first gas-liquid separator 50a is filled with liquid phase-separated boil-off gas, that is, liquefied gas, which is phase-separated from the boil-off gas, and the filled liquefied gas is transferred to the cargo tank 10 through the first liquefied gas recovery line L5. is recovered One end of the first liquefied gas recovery line L5 may be connected to the lower portion of the first gas-liquid separator 50a, and the other end may extend to the inside of the cargo tank 10 .

The second gas-liquid separator 50b is provided in the second fuel supply line L2 connected to the first fuel supply line L1 between the boil-off gas compression unit 60a and the demander 20a, the forced carburetor 40a It is possible to phase-separate the forcibly vaporized boil-off gas obtained by forcibly vaporizing the liquefied gas in the liquid phase and the gas phase. In addition, the second gas-liquid separator 50b removes components such as propane and butane contained in the forcibly vaporized boil-off gas, and joins the boil-off gas whose methane number has been adjusted to the downstream of the boil-off gas compression unit 60a to the consumer 20a. can be supplied to The second gas-liquid separator 50b may be provided in the second fuel supply line L2 downstream of the forced carburetor 40a.

Unlike the first embodiment connected to the upstream side of the BOG compression unit 60a, the second fuel supply line L2 of this embodiment supplies the first fuel downstream from the cargo tank 10 to the BOG compression unit 60a. It may extend to the line L1.

The peripheral line of the second gas-liquid separator 50b may be similar to that of the first gas-liquid separator 50a, and a detailed description of the peripheral line will be omitted herein.

The forcibly vaporized BOG to be used as the fuel of the consumer 20a obtained by the forced carburetor 40a and the second gas-liquid separator 50b is disposed downstream of the BOG compression unit 60a through the second fuel supply line L2. Since it joins the first fuel supply line (L1), the branching point of the boil-off gas recovery line (L4) branching from the first fuel supply line (L1) is a second fuel supply line (L1) connected to the first fuel supply line (L1). It is preferable to be located downstream of the connection point of L2).

In the above, the forcibly vaporized boil-off gas flowing into the second gas-liquid separator 50b contains other components (propane, butane, etc.) in addition to the methane component. If necessary XDF engines are applied, it is necessary to adjust the methane number to improve the performance of these engines. Therefore, in the present embodiment, the second gas-liquid separator 50b must be provided in order to supply fuel with increased methane number to the downstream of the BOG compression unit 60a to supply the XDF engine, the demand 20a.

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

Hereinafter, a fourth embodiment will be described with reference to FIG. 4 , but configurations using the same reference numerals as those of the third embodiment in this embodiment do not necessarily mean the same configuration.

As shown in FIG. 4 , the gas treatment system 4 according to the fourth embodiment of the present invention is a ship (S) using liquefied gas stored in the cargo tank 10 as fuel without a separate fuel tank being provided. ), it may be provided to process the boil-off gas naturally occurring inside the cargo tank 10 in the buffer tank 80 .

The gas processing system 4 according to the fourth embodiment of the present invention includes a cargo tank 10, a demand 20a, a pump 30, a forced vaporizer 40a, a second gas-liquid separator 50b, and boil-off gas compression. It may include a unit 60b, a boil-off gas cooler 70 , a buffer tank 80 , a pressure reducing means 90 , and a gas combustion unit 100 .

Here, the cargo tank 10, the customer 20a, the pump 30, the forced vaporizer 40a, the boil-off gas cooler 70, the buffer tank 80, the pressure reducing means 90, the gas combustion unit 100 is Since it is the same or similar to that described in the third embodiment, a detailed description will be omitted, and the boil-off gas compression unit 60b, which is a different component from the third embodiment of the present invention, and the first gas-liquid separator 50a, which is an omitted component, will be omitted. ), only the parts that change due to

The boil-off gas compression unit 60b is a screw-type low-pressure compressor (LD Compressor) or a reciprocating low-pressure compressor that compresses the boil-off gas containing droplets, which is a different type from the boil-off gas compression unit 60a of the third embodiment, to a low pressure. It may be a compressor (LD Compressor). This boil-off gas compression unit 60b may be configured in multiple stages as shown, for example, four stages are composed of one set, and two sets are arranged in parallel so that at least one set is selectively operated. can A cooler (not shown) may be provided between the multi-stage BOG compression unit 60b, and the cooler lowers the BOG temperature raised by the upstream BOG compressor 60b to lower the BOG compressor 60b. ) to facilitate the operation of

Downstream of the boil-off gas compression unit 60b of this embodiment, it is branched from the first fuel supply line L1 in the same or similar manner to the boil-off gas compression unit 60a of the third embodiment and extends to the buffer tank 80, A boil-off gas recovery line (L4) for branching a portion of the boil-off gas discharged from the cargo tank 10 and compressed by at least one stage of the boil-off gas compression unit 60b may be provided.

As described above, the boil-off gas compression unit 60b of this embodiment is different from the boil-off gas compression unit 60a of the third embodiment, and the surrounding elements are the same as or similar to those of the third embodiment. , a detailed description will be omitted to avoid overlapping description.

In this embodiment, the first gas-liquid separator 50a, which is a component of the third embodiment, is omitted. As described above, the first gas-liquid separator 50a of the third embodiment includes the boil-off gas compression unit 60a of the third embodiment. ) is essentially provided because a centrifugal low-pressure compressor of a type that does not allow BOG containing droplets to enter is applied, but in this embodiment, BOG compression unit 60b is a type that BOG containing droplets may enter. Since the screw-type low-compressor or the reciprocating-type low-pressure compressor of

That is, in the present embodiment, as in the third embodiment, the boil-off gas (BOG) flowing into the boil-off gas compression unit 60a, which is a centrifugal low-compressor, through the first fuel supply line L1 and the boil-off gas replenishment line L3 (natural vaporization) There is no need to provide the first gas-liquid separator 50a for preventing the inflow of droplets to remove the droplets contained in the boil-off gas and/or excess boil-off gas.

In this embodiment, since the first gas-liquid separator 50a of the third embodiment is omitted, the first fuel supply line L1 is connected to the boil-off gas replenishment line L3 between the pressure reducing means 90 and the boil-off gas compression unit 60b. ) connected directly to the BOG compression unit 60b through the BOG and BOG supplement line L3 of the cargo tank 10 supplied to the BOG compression unit 60b through the first fuel supply line L1. ) may be joined in the first fuel supply line L1 upstream of the BOG compression unit 60b with the BOG supplied to the buffer tank 80 .

As described above, in this embodiment, by applying a screw-type low-pressure compressor or a reciprocating low-pressure compressor that may enter the boil-off gas containing droplets into the boil-off gas compression unit 60b, the cargo tank 10 and the boil-off gas compression unit ( No gas-liquid separator is provided between 60b) and between the buffer tank 80 and the BOG compression unit 60b, and the surplus BOG in the buffer tank 80 and the BOG naturally vaporized in the cargo tank 10 are gas-liquid separated It may be configured to be joined without being introduced into the boil-off gas compression unit 60b.

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

Hereinafter, a fifth embodiment will be described with reference to FIG. 5 , but configurations using the same reference numerals as those of the third embodiment in this embodiment do not necessarily mean the same configuration.

As shown in FIG. 5 , the gas processing system 5 according to the fifth embodiment of the present invention is a ship (S) using liquefied gas stored in the cargo tank 10 as a fuel without a separate fuel tank. ), it may be provided to process the boil-off gas naturally occurring inside the cargo tank 10 in the buffer tank 80 .

The gas treatment system 5 according to the fifth embodiment of the present invention is a cargo tank 10, a demand 20b, a first pump 30a, a second pump 30b, a forced vaporizer 40b, and boil-off gas. It may include a compression unit 60c, a boil-off gas cooler 70 , a buffer tank 80 , a pressure reducing means 90 , and a gas combustion unit 100 .

Here, the cargo tank 10, the boil-off gas cooler 70, the buffer tank 80, the pressure reducing means 90, and the gas combustion unit 100 are the same or similar to those described in the third embodiment, so detailed descriptions will be omitted. and the components other than those of the third embodiment of the present invention, such as the consumer 20b, the first pump 30a, the second pump 30b, the forced carburetor 40b, the boil-off gas compression unit 60c, and are omitted. Only parts that are different due to the components of the first gas-liquid separator 50a and the second gas-liquid separator 50b will be described.

The consumer 20b is fueled by forcibly vaporized BOG generated by forcibly vaporizing the liquefied gas stored in the cargo tank 10 or naturally vaporized BOG generated by natural evaporation of the liquefied gas in the cargo tank 10 . can generate power.

In addition, when the BOG and/or naturally vaporized BOG from the cargo tank 10 do not reach the BOG consumption of the consumer 20a, the BOG stored in the buffer tank 80 is At least a part of it may be transmitted through the boil-off gas replenishment line (L3) to generate power.

In this embodiment, the consumer 20b may be a MEGI engine, which is a type of high-pressure engine driven at a high pressure of 250 bar or more, for example, 250 bar to 400 bar without the need to adjust the methane number. Due to the application of the MEGI engine, a high-pressure compressor (HD Compressor) is applied to the boil-off gas compression unit 60c in this embodiment, and a high-pressure pump is applied to the second pump 30b. In this embodiment, although the case of applying the MEGI engine as the consumer 20b is described, it is not limited thereto, and other high-pressure engines that can be driven at a high pressure of 250 bar or more without the need to adjust the methane number can be applied, of course. In addition, in the present embodiment, the consumer 20b may include a power generation engine that generates electricity in addition to the MEGI engine, which is the main engine for propulsion of the ship S, of course.

The first pump 30a is installed in the cargo tank 10 to pressurize the liquefied gas discharged to the outside, and is installed in the second fuel supply line L2 extending to the bottom of the cargo tank 10 . can be

The first pump 30a extracts liquefied gas from the cargo tank 10 and pressurizes the liquefied gas to prevent cavitation of the second pump 30b, which is a high-pressure pump, to thereby pressurize the second pump 30b. ) to supply a sufficient amount of liquefied gas.

In addition, the first pump 30a is supplied to the buffer tank 80 through the liquefied gas filling line L6 as needed, such as for the purpose of condensing and storing the boil-off gas of the buffer tank 80 . Here, the liquefied gas filling line L6 may be connected to the second fuel supply line L2 between the first pump 30a and the second pump 30b.

The second pump 30b may be a high-pressure pump provided in the second fuel supply line L2, and pressurizes the liquefied gas supplied from the first pump 30a to the high pressure required by the high-pressure engine, the consumer 20b. Thus, it is possible to supply the liquefied gas to the consumer 20b.

The second fuel supply line L2 of this embodiment is to extend from the inside of the cargo tank 10 to the first fuel supply line L1 downstream of the boil-off gas compression unit 60a in the same or similar manner as in the third embodiment. can

After the liquefied gas is discharged from the cargo tank 10, it is primarily pressurized by the first pump 30a, and the second pump 30b is the first pressurized liquid gas Secondary pressurization may be forcibly vaporized through the forced vaporizer 40b, and the forcibly vaporized boil-off gas may be joined downstream of the boil-off gas compression unit 60c and supplied to the consumer 20b.

At this time, the second pump 30b supplies the liquefied gas to the demander 20b by pressurizing the liquefied gas to the pressure required by the demander 20b, for example, 250 bar or more, so that the demander 20b, which is a high-pressure engine, powers the liquefied gas. can produce

The second pump 30b pressurizes the liquefied gas in the liquid state discharged from the first pump 30a to a high pressure, so that the liquefied gas is in a supercritical state having a temperature and a pressure higher than the supercritical point (Critical Point). can be phase-changed. In this case, the temperature of the liquefied gas in the supercritical state may be relatively higher than the critical temperature.

In addition, the second pump 30b may pressurize the liquefied gas in a liquid state to a high pressure to change it into a supercooled liquid state. Here, the liquefied gas in the supercooled liquid state is a state in which the pressure of the liquefied gas is higher than the critical pressure and the temperature is lower than the critical temperature.

Specifically, the second pump 30b pressurizes the liquefied gas in the liquid state discharged from the first pump 30a to a high pressure of 250 bar or more, and the temperature of the liquefied gas is lower than the critical temperature, so that the liquefied gas is subcooled. It can be phase-changed to a liquid state. Here, the temperature of the liquefied gas in the supercooled liquid state may be -140°C to -60°C, which is relatively lower than the critical temperature.

In this embodiment, the liquefied gas compressed by the second pump 30b is joined downstream of the boil-off gas compression unit 60c through the forced vaporizer 40b without going through the buffer tank 80, supplied as fuel.

The forced vaporizer 40b may be provided in the second fuel supply line L2 downstream of the second pump 30b, which is a high-pressure pump, and may forcibly vaporize the liquefied gas transferred from the second pump 30b. .

The forcibly vaporized BOG obtained by forcibly vaporizing the liquefied gas in the forced vaporizer 40b may be merged downstream of the BOG compression unit 60c without passing through the buffer tank 80 .

The forcibly vaporized BOG contains other components (propane, butane, etc.) in addition to the methane component, but in this embodiment, a type of engine that does not need to control the methane number is applied as the demander 20b. There is no need to install a gas-liquid separator for methane number control downstream.

In this embodiment, the forced carburetor 40b applies a MEGI engine, which is a type of high-pressure engine in which the second pump 30b is pressurized to a high pressure of 250 bar or higher and the demander 20b is driven at a high pressure of 250 bar or higher, so the corresponding high pressure It may be a vaporizer (HP Vaporizer).

The boil-off gas compression unit 60c may be provided in the first fuel supply line L1 to compress the boil-off gas to correspond to the required pressure of the demander 20b.

In the present embodiment, the boil-off gas compression unit 60c may be a reciprocating compressor into which boil-off gas containing droplets, which is a different type from that of the boil-off gas compression unit 60a of the third embodiment, may enter. However, in this embodiment, since the consumer 20b does not need to adjust the methane number and is a MEGI engine, which is a type of high-pressure engine driven at a high pressure of 250 bar or more, the BOG compression unit 60c is a multi-stage reciprocating reciprocating high-pressure compressor (HD). Compressor). A cooler (not shown) may be provided between the multi-stage BOG compression unit 60c, and the cooler lowers the BOG temperature raised by the upstream BOG compressor 60c to lower the BOG compressor ( 60c) to facilitate the operation.

In the multi-stage BOG compression unit 60c, when the intermediate stage, for example, a 5-stage compressor is configured, the second compressor downstream, specifically, downstream of the cooler provided between the second compressor and the third compressor, the first fuel A boil-off gas recovery line (L4) branched from the supply line (L1) and extending to the buffer tank (80) may be provided. The boil-off gas recovery line (L4) is, when the naturally vaporized boil-off gas in the cargo tank 10 is greater than the amount of fuel required by the demander 20b or is temporarily increased, a predetermined flow rate supplied as the fuel of the demander 20b. It serves as a passage through which the surplus BOG other than BOG can be stored in the buffer tank 80 .

In this embodiment, the first gas-liquid separator 50a, which is a component of the third embodiment, is omitted. As described above, the first gas-liquid separator 50a of the third embodiment includes the boil-off gas compression unit 60a of the third embodiment. ) is essentially provided because a centrifugal low-pressure compressor of a type that does not allow BOG containing droplets to enter is applied, but in this embodiment, BOG compression unit 60c is a type in which BOG containing droplets may enter. Since a multi-stage reciprocating high-pressure compressor is applied to generate a high pressure, there is no need to provide the first gas-liquid separator 50a, which is a component of the third embodiment.

In addition, in this embodiment, the second gas-liquid separator 50b, which is a component of the third embodiment, is omitted. As described above, the second gas-liquid separator 50b of the third embodiment is the customer 20a of the third embodiment. It is essential because the XDF engine that needs to control the methane number is applied, but in this embodiment, the demand 20b does not need to control the methane number and uses the MEGI engine, which is a high-pressure engine, so that the third There is no need to provide a second gas-liquid separator 50b.

That is, in the present embodiment, as in the third embodiment, the boil-off gas (BOG) flowing into the boil-off gas compression unit 60a, which is a centrifugal low-compressor, through the first fuel supply line L1 and the boil-off gas replenishment line L3 (natural vaporization) It is not necessary to provide the first gas-liquid separator 50a for preventing the inflow of droplets to remove the droplets contained in the boil-off gas and/or excess boil-off gas), and it is also necessary to provide a second gas-liquid separator 50b for controlling the methane number. none.

6 is a view for explaining that the BOG cooler is provided in the buffer tank in the gas processing system according to the first to fifth embodiments of the present invention.

The buffer tank 8 of each of the gas processing systems 1, 2, 3, 4, and 5 according to the first to fifth embodiments, as described above, removes boil-off gas naturally generated from the cargo tank 10 . Including liquefied gas can be efficiently treated. However, the internal pressure of the buffer tank 8 may increase due to the BOG recovered and stored from the BOG recovery line L4 and the BOG generated inside, and a problem may occur if the pressure rises above the set internal pressure. have. That is, a problem may occur in the operation of the buffer tank 80 due to an increase in internal pressure due to the boil-off gas. Although it is possible to prevent the internal pressure increase by providing the condensing structure 120 in the buffer tank 80 in the second embodiment, there is a limit to preventing the pressure increase by the condensing structure 120 alone. Accordingly, in this embodiment, the boil-off gas cooler 110 is provided in the buffer tank 80 as a way to efficiently deal with operational problems caused by the pressure increase in the buffer tank 80 , which will be described in detail below.

As shown in FIG. 6 , the BOG cooler 140 may be provided in the buffer tank 80 .

The BOG cooler 140 may cool BOG recovered to the buffer tank 80 through the BOG and/or BOG recovery line L4 in the buffer tank 80 .

The boil-off gas cooler 140 may be a cryocooler. A cryocooler is a cooler that is compactly composed of a motor, a piston, a regenerator, and a displacer.

The boil-off gas cooler 140 may be installed on the deck of the ship S adjacent to the buffer tank 80 .

A cooling circulation line L10 may be provided to cool the boil-off gas in the buffer tank 80 using the boil-off gas cooler 140 .

The cooling circulation line L10 may be provided between the buffer tank 80 and the boil-off gas cooler 140 , and allows the boil-off gas inside the buffer tank 80 to be cooled by the boil-off gas cooler 140 . A path can be provided.

The cooling circulation line L10 connects between the buffer tank 80 and the BOG cooler 140 and supplies BOG inside the buffer tank 80 to the BOG cooler 140. A first cooling line L10 -1) and a second cooling line (L10-2) connecting the BOG cooler 140 and the buffer tank 80 and supplying BOG cooled in the BOG cooler 140 to the buffer tank 80. can be made with

A plurality of valves (not shown) for controlling the flow of boil-off gas may be provided in each of the first and second cooling lines L10-1 and L10-2.

In addition, the boil-off gas bypass line L9 may be provided to cool the boil-off gas recovered to the buffer tank 80 through the boil-off gas recovery line L4 using the boil-off gas cooler 140 .

The boil-off gas bypass line L9 may have one end connected to the boil-off gas recovery line L4 and the other end connected to the first cooling line L10-1 of the cooling circulation line L10.

Of course, the boil-off gas bypass line L9 may be directly connected to the boil-off gas cooler 140 without being connected to the first cooling line L10-1.

The configuration of the boil-off gas cooler 140 and the surrounding piping may be applied to the buffer tank 80 of the first to fifth embodiments described above.

In addition to the first to fifth embodiments described above, 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 with known techniques.

As such, in this embodiment, in the ship (S) using the liquefied gas stored in the cargo tank 10 as a fuel, the naturally vaporized boil-off gas supplied from the cargo tank 10 to the fuel of the consumers 20a, 20b and / or by processing the forcibly vaporized BOG using the buffer tank 80, BOG can be efficiently processed.

In addition, this embodiment is configured to be stored in the buffer tank 80 when the boil-off gas naturally generated in the cargo tank 10 is greater than the amount of fuel required by the consumers 20a, 20b or is temporarily increased. , it is possible to reduce the amount of BOG burnt or discharged to the outside by the gas combustion unit 100, thereby preventing unnecessary waste of BOG, as well as ensuring the pressure stability of the cargo tank 10 .

In addition, in this embodiment, the buffer tank 80 is configured independently of the flow of supplying liquefied gas as fuel from the cargo tank 10 to the consumers 20a and 20b, but the boil-off gas stored in the buffer tank 80 is By configuring so that it can be selectively supplied as fuel to the consumers 20a, 20b as needed, a fuel pump, a fuel vaporizer, etc. for supplying liquefied gas to the consumers 20a, 20b must be provided to explain the effect of the present invention Unlike a fuel tank as an example for

In addition, in this embodiment, the naturally vaporized BOG in the cargo tank 10 is supplied as the main fuel of the consumers 20a and 20b, but the BOG stored in the buffer tank 80 is subsidized by the consumers 20a and 20b. By configuring to supply fuel, the buffer tank 80 does not require a fuel pump for supplying liquefied gas fuel, so even if the flow rate and internal pressure of the buffer tank 80 are lowered, it is an example for explaining the effect of the present invention. Unlike the fuel tank, it is not necessary to consider the problem of stopping the fuel supply and cooling down due to the insufficiency of the effective suction head and inlet pressure required to drive the fuel pump.

In addition, in the present embodiment, by configuring the buffer tank 80 to supply only boil-off gas as fuel to the consumers 20a and 20b without supplying the liquefied gas as the fuel of the consumers 20a and 20b, the buffer tank 80 Unlike a fuel tank as an example for explaining the effect of the present invention, it is not necessary to maintain a flow rate and internal pressure in a certain range in order to use liquefied gas as the fuel of the consumers 20a and 20b, so from maintaining the flow rate and internal pressure of the liquefied gas can be free

In addition, in this embodiment, the buffer tank 80 is filled with liquefied gas regardless of the fuel of the consumers 20a and 20b so that the boil-off gas inside can be condensed into the liquefied gas and stored, but the filled liquefied gas expands. By configuring so that it can be returned to the cargo tank 10 when discharge from the buffer tank 80 is required, such as, liquefied gas compared to the absence of a configuration of discharging liquefied gas from the fuel tank as an example for explaining the effect of the present invention It is possible to secure the stability of the buffer tank 80 from the expansion of the.

In addition, in the present embodiment, by cooling the boil-off gas in the buffer tank 80 and/or the boil-off gas recovered to the buffer tank 80 through the boil-off gas recovery line L4 with the boil-off gas cooler 140 , the buffer It is possible to lower the pressure and temperature inside the tank 80 , thereby solving operational problems caused by the increase in pressure in the buffer tank 80 .

In the above, the present invention has been described focusing on the embodiments of the present invention, but this is only an example and does not limit the present invention. It will be appreciated that various combinations or modifications and applications not illustrated in the embodiments are possible within the scope. Accordingly, descriptions related to variations and applications that can be easily derived from the embodiments of the present invention should be interpreted as being included in the present invention.

1, 2, 3, 4, 5: gas processing system
10: cargo tank 20a, 20b: customer
30, 30a, 30b: pump 40a, 40b: forced carburetor
50, 50a, 50b: gas-liquid separator 60a, 60b, 60c: BOG compression unit
70: boil-off gas cooler 80: buffer tank
90: pressure reducing means 100: gas combustion unit
110: heat exchanger 120: condensing structure
130: pressure generating unit 140: boil-off gas cooler
L1: First fuel supply line L2: Second fuel supply line
L3: BOG replenishment line L4: BOG recovery line
L5: First liquefied gas recovery line L6: Liquefied gas filling line
L7: Second liquefied gas recovery line L8: BOG discharge line
L9: BOG bypass line L10: Cooling circulation line
L10-1: 1st cooling line L10-2: 2nd cooling line
S: ship

Claims (8)

A first fuel supply line for supplying boil-off gas generated in the cargo tank to a demand destination;
a boil-off gas compression unit provided in the first fuel supply line and compressing boil-off gas;
a boil-off gas recovery line for branching the boil-off gas that has passed through the boil-off gas compression unit;
a buffer tank condensing the boil-off gas branched through the boil-off gas recovery line;
a boil-off gas cooler for cooling the boil-off gas generated in the buffer tank;
a cooling circulation line configured to cool the boil-off gas in the buffer tank using the boil-off gas cooler; and
and a boil-off gas bypass line configured to cool the boil-off gas recovered to the buffer tank through the boil-off gas recovery line using the boil-off gas cooler. delete According to claim 1, wherein the cooling circulation line,
a first cooling line for supplying the boil-off gas in the buffer tank to the boil-off gas cooler; and
and a second cooling line for supplying the boil-off gas cooled by the boil-off gas cooler to the buffer tank. delete According to claim 3, wherein the boil-off gas bypass line,
A gas treatment system, characterized in that one end is connected to the boil-off gas recovery line, and the other end is connected to the first cooling line. According to claim 1, wherein the boil-off gas cooler,
A gas processing system, characterized in that it is a cryocooler. According to claim 1, wherein the buffer tank,
A gas treatment system, characterized in that it is a Type-C pressure tank. A ship, characterized in that it is provided with the gas treatment system according to any one of claims 1, 3 and 5 to 7.

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