KR102539441B1 - System and Method of Controlling Pressure in Cargo Tank for Vessels - Google Patents

Abstract

A cargo tank pressure control system for ships is disclosed.
The cargo tank pressure control system for ships includes a first pump pressurizing liquid fuel discharged from a fuel tank; a heat exchanger installed above the dome of the cargo tank to cool the liquid cargo discharged from the cargo tank by using the liquid fuel pressurized by the first pump as a refrigerant; And a vaporizer for vaporizing the liquid fuel, which is used as a refrigerant in the heat exchanger after being pressurized by the first pump and whose temperature has risen, wherein the liquid fuel stored in the fuel tank and the liquid cargo stored in the cargo tank are different from each other. Characterized in that it is a kind of fluid.

Description

System and method for controlling pressure in cargo tanks for ships {System and Method of Controlling Pressure in Cargo Tank for Vessels}

The present invention relates to a system and method for controlling the internal pressure of a cargo tank applied to a ship equipped with an engine that uses a different type of fuel from the cargo stored in the cargo tank.

In the existing commercial ship market, the purpose of each cargo, such as a liquefied natural gas (LNG) carrier, a liquefied petroleum gas (LPG) carrier, and a liquefied ethylene gas (LEG) carrier, is clarified, and the corresponding Cargo-only ships were operated.

However, according to the recent diversified market conditions, there is a request for technical review of a multi-gas carrier capable of accommodating various types of cargo from ship owners, especially for propulsion using liquefied natural gas as fuel. The review of the ship to which the engine is applied is ongoing.

Liquefied natural gas has a lower temperature than cargoes such as propane, butane, liquefied petroleum gas, ethane, and ethylene, and is in a cryogenic state of about -162 ° C.

In order to supply liquid fuel such as liquefied natural gas stored in a fuel tank to an engine, the liquid fuel must be pressurized and vaporized, and a heating system is required to vaporize the liquid fuel. In addition, a significant amount of steam is consumed in the heating system to vaporize the liquid fuel.

Inside the cargo tank, the liquid cargo is naturally vaporized by the heat intruding from the outside to generate boil-off gas (BOG), so the boil-off gas management system to control the pressure and temperature inside the cargo tank (BOG management system) is required.

On the other hand, among the engines generally used in ships, engines that can use natural gas as fuel include DF engines (DFDE (Dual Fuel Diesel Electric), DFDG (Dual Fuel Diesel Generator)), ME-GI engines, X-DF engines, etc. has a gas fueled engine.

The DF engine (DFDE, DFDG) consists of 4 strokes and adopts the Otto Cycle, which injects natural gas with a relatively low pressure of 6.5 bar into the combustion air inlet and compresses it as the piston rises. are doing

The ME-GI engine consists of two strokes and adopts a diesel cycle in which high-pressure natural gas around 300 bar is directly injected into the combustion chamber near the top dead center of the piston. Recently, there is a growing interest in ME-GI engines with better fuel efficiency and propulsion efficiency.

The X-DF engine is used for propulsion and consists of two strokes. Medium-pressure natural gas of about 16 bar is used as fuel, and an Otto cycle is adopted.

The present invention is to provide a cargo tank pressure control system and method for a ship, which operate in conjunction with a system for pressurizing and vaporizing liquid fuel stored in a fuel tank and supplying it to an engine and a system for adjusting the pressure and temperature inside the cargo tank.

According to one aspect of the present invention for achieving the above object, a first pump for pressurizing the liquid fuel discharged from the fuel tank; a heat exchanger installed above the dome of the cargo tank to cool the liquid cargo discharged from the cargo tank by using the liquid fuel pressurized by the first pump as a refrigerant; And a vaporizer for vaporizing the liquid fuel, which is used as a refrigerant in the heat exchanger after being pressurized by the first pump and whose temperature has risen, wherein the liquid fuel stored in the fuel tank and the liquid cargo stored in the cargo tank are different from each other. A cargo tank pressure control system for a ship, characterized in that it is a kind of fluid, is provided.

The cargo tank pressure control system for ships may further include a second pump installed inside the fuel tank to pressurize the liquid fuel inside the fuel tank and discharge it to the outside.

The first pump pressurizes the liquid fuel to the required pressure of the propulsion engine, and the fuel gas that is pressurized by the first pump and used as a refrigerant in the heat exchanger and vaporized by the vaporizer is sent to the propulsion engine. can

A part of the fuel gas sent to the propulsion engine may be sent to one or more of the engine for power generation and auxiliary machinery.

According to another aspect of the present invention for achieving the above object, a second pump installed inside the fuel tank, pressurizing the liquid fuel inside the fuel tank and discharging it to the outside; a heat exchanger installed above the dome of the cargo tank to cool the liquid cargo discharged from the cargo tank by using the liquid fuel pressurized by the second pump as a refrigerant; And a vaporizer for vaporizing the liquid fuel, which is used as a refrigerant in the heat exchanger after being pressurized by the second pump and whose temperature has risen, wherein the liquid fuel stored in the fuel tank and the liquid cargo stored in the cargo tank are different from each other. A cargo tank pressure control system for a ship, characterized in that it is a kind of fluid, is provided.

The ship cargo tank pressure control system may further include a third pump installed inside the cargo tank to pressurize the liquid cargo inside the cargo tank and discharge it to the outside.

Liquid cargo cooled by the heat exchanger after being discharged from the cargo tank may be sent to the cargo tank by gravity.

The liquid cargo stored in the cargo tank may be a fluid having a higher boiling point than the liquid fuel stored in the fuel tank.

The liquid fuel stored in the fuel tank may be liquefied natural gas.

The liquid cargo stored in the cargo tank may be any one or two or more of propane, butane, liquefied petroleum gas, ethane, ethylene, propylene, butylene, and butadiene.

A plurality of cargo tanks may be mounted on a ship, and a plurality of heat exchangers may be included as many as the number of the plurality of cargo tanks, and the plurality of heat exchangers may be installed on top of domes of the plurality of cargo tanks, respectively, The plurality of heat exchangers may be installed in series or parallel.

The cargo tank pressure control system for ships may further include a compressor for compressing boil-off gas discharged from the fuel tank.

The boil-off gas compressed by the compressor after being discharged from the fuel tank may be supplied to one or more of a power generation engine and auxiliary machinery.

The cargo tank pressure control system for ships may further include a re-liquefaction device for re-liquefying boil-off gas discharged from the cargo tank and returning it to the cargo tank.

The internal pressure and temperature of the cargo tank are preferentially controlled by the heat exchanger, and the reliquefaction device may be used auxiliary.

The re-liquefaction device may be a self-heat exchange method.

According to another aspect of the present invention for achieving the above object, a system for pressurizing and vaporizing liquid fuel stored in a fuel tank and supplying it to an engine and a system for adjusting the pressure and temperature inside the cargo tank are linked and operated, The liquid fuel discharged from the fuel tank is used as a refrigerant to cool the liquid cargo discharged from the cargo tank, thereby cooling the liquid cargo discharged from the cargo tank and preheating the liquid fuel stored in the fuel tank before vaporization, There is provided a cargo tank pressure control method for a ship, characterized in that the liquid fuel stored in the fuel tank and the liquid cargo stored in the cargo tank are different types of fluids.

According to the present invention, there is an advantage in that the liquid fuel discharged from the cargo tank can be cooled and at the same time the liquid fuel to be sent to the vaporizer can be pre-heated.

In addition, according to the present invention, there is no need to send the boil-off gas inside the cargo tank to the gas combustion device to burn it in order to control the pressure inside the cargo tank, and a separate re-liquefaction equipment is used by using a system that supplies fuel to the propulsion engine. It is possible to control the pressure and temperature inside the cargo tank in an efficient way without additional power consumption in complicated installation or separate re-liquefaction equipment.

According to one embodiment of the present invention, since the heat exchanger is installed above the dome of the cargo tank, the liquid cargo cooled by the heat exchanger can be sent to the cargo tank by gravity without installing additional equipment.

According to one embodiment of the present invention, since a plurality of heat exchangers are connected in parallel with each other, there is an advantage that flexible operation of the system is possible by easily controlling the flow rate of liquid fuel sent to each of the plurality of heat exchangers.

1 is a schematic diagram of a cargo tank pressure control system for a ship according to a first preferred embodiment of the present invention.
2 is a schematic diagram of a cargo tank pressure control system for a ship according to a second preferred embodiment of the present invention.

Hereinafter, the configuration and operation of a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. The present invention can be applied to various applications such as ships equipped with engines using natural gas as fuel and ships including various liquid cargo tanks. In addition, the following examples may be modified in many different forms, and the scope of the present invention is not limited to the following examples.

1 is a schematic diagram of a cargo tank pressure control system for a ship according to a first preferred embodiment of the present invention.

Referring to FIG. 1 , the cargo tank pressure control system for ships according to this embodiment includes a first pump 110 , a heat exchanger 200 and a vaporizer 300 .

The first pump 110 pressurizes the liquid fuel discharged from the fuel tank FT. The first pump 110 can pressurize the liquid fuel to the required pressure of the propulsion engine E1, and the second pump 120 is installed inside the fuel tank FT, so that the liquid inside the fuel tank FT The fuel can be pressurized and discharged to the outside.

When the propulsion engine E1 is an engine using high-pressure natural gas as fuel, such as an ME-GI engine, the liquid fuel pressurized by the second pump 120 is further compressed by the first pump 110. However, when the propulsion engine E1 is an engine using relatively low pressure natural gas as fuel, such as an X-DF engine, the liquid fuel pressurized by the second pump 120 is transferred to the first pump ( 110), it may be directly supplied to the propulsion engine E1 via the heat exchanger 200 and the vaporizer 300 without the need for additional compression.

The heat exchanger 200 is installed above the dome of the cargo tank CT, and uses the liquid fuel pressurized by the first pump 110 as a refrigerant to transfer liquid cargo discharged from the cargo tank CT. Cool down.

The liquid cargo cooled by the heat exchanger 200 is sent back to the cargo tank CT, and a third pump 130 is installed inside the cargo tank CT to pressurize the liquid cargo inside the cargo tank CT. and can be discharged to the outside.

Since the heat exchanger 200 is installed above the dome of the cargo tank CT, the liquid cargo cooled by the heat exchanger 200 can be sent to the cargo tank CT by gravity without installing additional equipment.

This embodiment is characterized in that the liquid fuel stored in the fuel tank FT and the liquid cargo stored in the cargo tank CT are different types of fluids. More specifically, the liquid cargo stored in the cargo tank CT may be a fluid with a higher boiling point than the liquid fuel stored in the fuel tank FT. For example, the liquid fuel stored in the fuel tank (FT) may be liquefied natural gas, and the liquid cargo stored in the cargo tank (CT) may be propane, butane, liquefied petroleum gas, ethane, ethylene (Ethylene), propylene (Propylene), butylene (Butylene) and butadiene (Butadiene) may be any one or two or more.

Since the boiling point of the liquid cargo stored in the cargo tank (CT) is higher than the boiling point of the liquid fuel stored in the fuel tank (FT), the liquid cargo discharged from the cargo tank (CT) is the same as the liquid fuel discharged from the fuel tank (FT). Efficient cooling is possible through heat exchange.

When a ship is equipped with a plurality of cargo tanks (CT), this embodiment includes as many heat exchangers 200 as the number of cargo tanks (CT), and the plurality of heat exchangers 200 are a plurality of cargo tanks (CT). ) are installed on the upper part of the dome. In addition, the liquid fuel pressurized by the first pump 110 sequentially passes through a plurality of heat exchangers 200 installed in series and is used as a refrigerant, and the liquid cargo discharged from each cargo tank CT is Each is cooled by the heat exchanger 200 installed on the top of the dome of the CT, and the cooled liquid cargo can be sent from the heat exchanger 200 to the cargo tank CT by gravity.

The vaporizer 300 is used as a refrigerant in the heat exchanger 200 after being pressurized by the first pump 110 and vaporizes the liquid fuel (some of which may be vaporized and in a gas-liquid mixture state, the same below) . When a ship is equipped with a plurality of cargo tanks (CT), the liquid fuel that has been pressurized by the first pump 110 and then sequentially passed through a plurality of heat exchangers 200 is sent to the vaporizer 300.

The fuel gas pressurized by the first pump 110 and preheated by the heat exchanger 200 and vaporized by the vaporizer 300 may be sent to the propulsion engine E1. Some of the fuel gas sent to the propulsion engine E1 may be sent to the power generation engine E2, and the fuel pressurized to the required pressure of the propulsion engine E1 is decompressed by the decompression device 700 to the power generation engine ( After reducing the pressure to the required pressure of E2), it can be supplied to the engine for power generation (E2). In addition, a part of the fuel gas sent to the propulsion engine E1 can be sent to auxiliary machinery A such as a boiler.

This embodiment may further include a compressor 510 for compressing boil-off gas discharged from the fuel tank FT. The boil-off gas compressed by the compressor 510 after being discharged from the fuel tank FT may be supplied to the power generation engine E2 and/or auxiliary machinery A such as a boiler. The compressor 510 has a small size capable of compressing the boil-off gas to the pressure required by the auxiliary machinery (A) such as the power generation engine (E2) or the boiler (compresses the boil-off gas to the pressure required by the propulsion engine (E1)). Compared to that), it is preferable.

This embodiment may further include a re-liquefying device 400 for re-liquefying boil-off gas discharged from the cargo tank CT and returning it to the cargo tank CT.

The internal pressure and/or temperature of the cargo tank (CT) is preferentially controlled by a method of heat-exchanging the liquid fuel discharged from the cargo tank (CT) with the liquid fuel discharged from the fuel tank (FT) in the heat exchanger (200). And, the reliquefaction device 400 is used as an aid when the heat exchanger 200 cannot be used or when it is necessary to additionally lower the internal pressure and/or temperature of the cargo tank CT.

The re-liquefying device 400 may be a self heat exchange method that re-liquefies the boil-off gas discharged from the cargo tank CT by using the boil-off gas itself discharged from the cargo tank CT as a refrigerant.

According to this embodiment, since the liquid fuel discharged from the fuel tank (FT) is used as a refrigerant to cool the liquid cargo discharged from the cargo tank (CT), the liquid cargo discharged from the cargo tank (CT) is cooled, There is an advantage that the liquid fuel to be sent to the vaporizer 300 can be pre-heated. If the liquid fuel is preheated and then sent to the vaporizer 300, energy used to vaporize the liquid fuel in the vaporizer 300 can be saved.

In addition, according to this embodiment, since the generation of boil-off gas is suppressed by cooling the liquid cargo of the cargo tank (CT), the boil-off gas inside the cargo tank (CT) is converted into gas to control the internal pressure of the cargo tank (CT). There is no need to send it to the gas combustion unit (GCU) to burn it.

In addition, according to the present embodiment, by using a system for supplying fuel to the propulsion engine E1, the liquid fuel inside the cargo tank CT can be cooled with only a simple installation of the heat exchanger 200, so a separate It is possible to control the internal pressure and temperature of the cargo tank (CT) in an efficient way without complicated installation such as re-liquefaction equipment or additional power consumption in separate re-liquefaction equipment.

2 is a schematic diagram of a cargo tank pressure control system for a ship according to a second preferred embodiment of the present invention.

Compared to the cargo tank pressure control system for ships of the first embodiment shown in FIG. 1, the cargo tank pressure control system for ships of the second embodiment shown in FIG. There are differences, and the following will focus on the differences. A detailed description of the same members as the cargo tank pressure control system for ships of the first embodiment described above will be omitted.

According to this embodiment, it is installed above the dome of the cargo tank (CT) and uses the liquid fuel pressurized by the first pump 110 as a refrigerant to cool the liquid cargo discharged from the cargo tank (CT). Since the plurality of heat exchangers 200 are connected in parallel to each other, compared to the case where the plurality of heat exchangers 200 are connected in series to each other as in the first embodiment, the It has the advantage of being able to easily control the flow rate of liquid fuel.

If the flow rate of liquid fuel sent to each of the plurality of heat exchangers 200 is controlled, the amount of boil-off gas re-liquefied inside the plurality of cargo tanks (CT) can be controlled respectively, so that the system can be operated flexibly.

In this embodiment, as in the first embodiment, when the propulsion engine E1 is an engine using relatively low pressure natural gas as fuel, such as an X-DF engine, the second pump 120 pressurizes the The liquid fuel may be directly supplied to the propulsion engine E1 without additional compression by the first pump 110.

It is obvious to those skilled in the art that the present invention is not limited to the above embodiments and can be variously modified or modified without departing from the technical gist of the present invention. it did

FT: fuel tank CT: cargo tank
E1: engine for propulsion E2: engine for power generation
A: auxiliary machinery 110: first pump
120: second pump 130: third pump
200: heat exchanger 300: vaporizer
400: re-liquefaction device 510: compressor
700: decompression device

Claims (17)

A first pump for pressurizing the liquid fuel discharged from the fuel tank;
a heat exchanger installed above the dome of the cargo tank to cool the liquid cargo discharged from the cargo tank by using the liquid fuel pressurized by the first pump as a refrigerant; and
A vaporizer for vaporizing the liquid fuel, which is used as a refrigerant in the heat exchanger after being pressurized by the first pump and whose temperature has risen,
The liquid fuel stored in the fuel tank and the liquid cargo stored in the cargo tank are different types of fluids,
A plurality of cargo tanks are mounted on a ship,
Includes as many heat exchangers as the number of the plurality of cargo tanks,
The plurality of heat exchangers are installed on the upper portion of the dome of the plurality of cargo tanks, respectively,
The plurality of heat exchangers are installed in series or parallel,
The cargo tank pressure control system for ships, characterized in that the liquid fuel discharged from the fuel tank is sent to the vaporizer after passing through the plurality of heat exchangers. The method of claim 1,
A cargo tank pressure control system for ships, further comprising a second pump installed inside the fuel tank to pressurize the liquid fuel inside the fuel tank and discharge it to the outside. The method of claim 1,
The first pump pressurizes the liquid fuel to the required pressure of the propulsion engine,
The fuel gas pressurized by the first pump and used as a refrigerant in the heat exchanger and then vaporized by the vaporizer is sent to the propulsion engine. The method of claim 3,
A part of the fuel gas sent to the propulsion engine is sent to one or more of the power generation engine and auxiliary machinery, the cargo tank pressure control system for ships. A second pump installed inside the fuel tank to pressurize the liquid fuel inside the fuel tank and discharge it to the outside;
a heat exchanger installed above the dome of the cargo tank to cool the liquid cargo discharged from the cargo tank by using the liquid fuel pressurized by the second pump as a refrigerant; and
A vaporizer used as a refrigerant in the heat exchanger after being pressurized by the second pump and vaporizing the liquid fuel whose temperature has risen; includes,
The liquid fuel stored in the fuel tank and the liquid cargo stored in the cargo tank are different types of fluids,
A plurality of cargo tanks are mounted on a ship,
Includes as many heat exchangers as the number of the plurality of cargo tanks,
The plurality of heat exchangers are installed on the upper portion of the dome of the plurality of cargo tanks, respectively,
The plurality of heat exchangers are installed in series or parallel,
The cargo tank pressure control system for ships, characterized in that the liquid fuel discharged from the fuel tank is sent to the vaporizer after passing through the plurality of heat exchangers. The method of claim 1,
A cargo tank pressure control system for ships, further comprising a third pump installed inside the cargo tank to pressurize the liquid cargo inside the cargo tank and discharge it to the outside. The method of claim 1,
The liquid cargo cooled by the heat exchanger after being discharged from the cargo tank is sent to the cargo tank by gravity. According to any one of claims 1 to 7,
The liquid cargo stored in the cargo tank is a fluid with a higher boiling point than the liquid fuel stored in the fuel tank, the cargo tank pressure control system for ships. The method of claim 8,
The liquid fuel stored in the fuel tank is liquefied natural gas, the cargo tank pressure control system for ships. The method of claim 8,
The liquid cargo stored in the cargo tank is any one or two or more of propane, butane, liquefied petroleum gas, ethane, ethylene, propylene, butylene and butadiene, cargo tank pressure control system for ships. According to any one of claims 1 to 7,
A plurality of cargo tanks are mounted on a ship,
Includes as many heat exchangers as the number of the plurality of cargo tanks,
The plurality of heat exchangers are installed on the upper portion of the dome of the plurality of cargo tanks, respectively,
The plurality of heat exchangers are installed in series or parallel, cargo tank pressure control system for ships. According to any one of claims 1 to 7,
Further comprising a compressor for compressing the boil-off gas discharged from the fuel tank, the cargo tank pressure control system for ships. The method of claim 12,
The boil-off gas compressed by the compressor after being discharged from the fuel tank is supplied to one or more of a power generation engine and auxiliary machinery, a cargo tank pressure control system for a ship. According to any one of claims 1 to 7,
Further comprising a re-liquefaction device for re-liquefying the boil-off gas discharged from the cargo tank and returning it to the cargo tank, the cargo tank pressure control system for ships. The method of claim 14,
The internal pressure and temperature of the cargo tank are preferentially controlled by the heat exchanger, and the re-liquefaction device is used auxiliary, the cargo tank pressure control system for ships. The method of claim 14,
The re-liquefaction device is a self-heat exchange method, a cargo tank pressure control system for ships. The system that pressurizes and vaporizes the liquid fuel stored in the fuel tank and supplies it to the engine and the system that controls the pressure and temperature inside the cargo tank are linked and operated.
In a heat exchanger installed on the upper part of the dome of the cargo tank, the liquid fuel discharged from the fuel tank is used as a refrigerant to cool the liquid cargo discharged from the cargo tank, thereby cooling the liquid cargo discharged from the cargo tank. Preheating the liquid fuel stored in the fuel tank before vaporizing it by the vaporizer,
The liquid fuel stored in the fuel tank and the liquid cargo stored in the cargo tank are different types of fluids,
A plurality of cargo tanks are mounted on a ship,
Includes as many heat exchangers as the number of the plurality of cargo tanks,
The plurality of heat exchangers are installed on the upper portion of the dome of the plurality of cargo tanks, respectively,
The plurality of heat exchangers are installed in series or parallel,
Characterized in that the liquid fuel discharged from the fuel tank is sent to the vaporizer after passing through the plurality of heat exchangers, the cargo tank pressure control method for ships.

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