# US 2014/0196474 A1 · Cold heat recovery apparatus using an lng fuel, and liquefied gas carrier including same

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- Number: US 2014/0196474 A1
- Document ID: US20140196474A1
- Status: Published application
- Kind: A1
- Application number: 14/123,474
- Filed: 2012-05-31
- Published: 2014-07-17
- Earliest claimed: 2011-05-31
- Assignees: Daewoo Shipbuilding & Marine Engineering Co., Ltd.
- Inventors: Byeong Yong Yoo; Young Sik Moon; Jae Ho Jang; Ji Eun Kim
- Web page: https://patentgrep.com/patent/US20140196474A1

## CPC

- F17C 9/04: Recovery of thermal energy
- B63H 21/38: Apparatus or methods specially adapted for use on marine vessels, for handling power plant or unit liquids, e.g. lubricants, coolants, fuels or the like ({in outboard drives B63H20/001; } lubricating or cooling machines or engines in general F01 - F04)
- B63J 2/14: of liquid-freight-carrying tanks
- F02D 19/022: {to adjust the fuel pressure, temperature or composition}
- F02M 21/0224: {Secondary gaseous fuel storages}
- F02M 21/0287: {characterised by the transition from liquid to gaseous phase (F02M21/06 takes precedence); Injection in liquid phase; Cooling and low temperature storage}
- F25J 1/0025: {Boil-off gases "BOG" from storages}
- F25J 1/0027: {Oxides of carbon, e.g. CO2}
- F25J 1/0221: {using the cold stored in an external cryogenic component in an open refrigeration loop}
- F25J 1/0222: {in combination with an intermediate heat exchange fluid between the cryogenic component and the fluid to be liquefied (F25J1/0224 takes precedence)}
- F25J 1/0244: {Operation; Control and regulation; Instrumentation (F25J1/0279 takes precedence)}
- B63J 2099/003: {of cargo oil or fuel, or of boil-off gases, e.g. for propulsive purposes}
- F02M 21/0215: {Mixtures of gaseous fuels; Natural gas; Biogas; Mine gas; Landfill gas}
- F17C 2205/0126: One vessel
- F17C 2205/0142: bundled in parallel
- F17C 2205/0326: electrically actuated
- F17C 2221/013: Carbon dioxide
- F17C 2221/033: Methane, e.g. natural gas, CNG, LNG, GNL, GNC, PLNG
- F17C 2221/035: Propane butane, e.g. LPG, GPL
- F17C 2223/0161: cryogenic, e.g. LNG, GNL, PLNG
- F17C 2223/033: Small pressure, e.g. for liquefied gas
- F17C 2225/0123: gaseous, e.g. CNG, GNC
- F17C 2225/0161: cryogenic, e.g. LNG, GNL, PLNG
- F17C 2225/035: High pressure, i.e. between 10 and 80 bars
- F17C 2227/0135: Pumps
- F17C 2227/0323: in a closed loop
- F17C 2227/0327: with recovery of heat
- F17C 2227/0372: in the gas
- F17C 2227/0388: separate
- F17C 2250/032: using computers
- F17C 2250/043: Pressure
- F17C 2250/0439: Temperature
- F17C 2250/0631: Temperature
- F17C 2250/0636: Flow or movement of content
- F17C 2260/046: Enhancing energy recovery
- F17C 2265/034: with condensing the gas phase
- F17C 2265/066: for feeding engines for propulsion
- F17C 2270/0105: Ships
- F25J 2210/62: Liquefied natural gas [LNG]; Natural gas liquids [NGL]; Liquefied petroleum gas [LPG]
- F25J 2210/90: Boil-off gas from storage
- F25J 2215/62: Ethane or ethylene
- F25J 2215/64: Propane or propylene
- Y02T 10/30: Use of alternative fuels, e.g. biofuels
- Y02T 70/00: Maritime or waterways transport
- Y02T 70/50: Measures to reduce greenhouse gas emissions related to the propulsion system
- F17C: VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES (storing fluids in natural or artificial cavities or chambers in the earth B65G5/00; construction or assembling of bulk storage containers employing civil-engineering techniques E04H7/00; variable-capacity gas-holders F17B; liquefaction or refrigeration machines, plants, or systems F25)
- B63H: MARINE PROPULSION OR STEERING (propulsion of air-cushion vehicles B60V1/14; specially adapted for submarines, other than nuclear propulsion, B63G; specially adapted for torpedoes F42B19/00)
- B63J: AUXILIARIES ON VESSELS
- F02D: CONTROLLING COMBUSTION ENGINES (vehicle fittings, acting on a single sub-unit only, for automatically controlling vehicle speed B60K31/00; conjoint control of vehicle sub-units of different type or different function, road vehicle drive control systems for purposes other than the control of a single sub-unit B60W)
- F02M: SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F25J: LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS {OR LIQUEFIED GASEOUS} MIXTURES BY PRESSURE AND COLD TREATMENT {OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE (cryogenic pumps F04B37/08; gas storage vessels, gas holders F17; filing vessels with, or discharging from vessels, compressed, liquefied or solidified gases F17C; refrigeration machines, plants, or systems F25B)}
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

Provided are a cold heat recovery apparatus using an LNG fuel and a liquefied gas carrier, in which costs involved in the installation and operation of a reliquefying facility can be reduced by recovering and utilizing cold heat of the LNG fuel when boil-off gas of liquefied gas as a cargo is reliquefied, and energy saving and reduction of environmental pollutants can be achieved because additional energy is not consumed in a reliquefaction process. A cold heat recovery apparatus for processing boil-off gas generated in a liquefied gas tank by using cold heat of an LNG fuel includes cold heat usage means using cold heat of an LNG supplied from an LNG fuel tank storing an LNG as a fuel to an engine, so as to processing the boil-off gas generated in the liquefied gas tank.

## Claims

### Claim 1

A cold heat recovery apparatus for processing boil-off gas generated in a liquefied gas tank by using cold heat of an LNG fuel, comprising:
cold heat usage means using cold heat of an LNG supplied from an LNG fuel tank storing an LNG as a fuel to an engine, so as to processing the boil-off gas generated in the liquefied gas tank.

### Claim 2 (depends on 1)

The cold heat recovery apparatus according to claim 1, wherein the cold heat usage means is a pressure control unit configured to control a pressure of the liquefied gas tank by using the cold heat of the LNG discharged from the LNG fuel tank, and
the pressure control unit comprises an LNG line installed to pass through the liquefied gas tank from the LNG fuel tank and configured to cause heat exchange between the LNG and a fluid stored in the liquefied gas tank.

### Claim 3 (depends on 2)

The cold heat recovery apparatus according to claim 2, wherein the pressure control unit further comprises a heater installed in front of the liquefied gas tank in the LNG line.

### Claim 4 (depends on 2)

The cold heat recovery apparatus according to claim 2, wherein the pressure control unit further comprises:
a first bypass line connected to the LNG line to bypass the liquefied gas tank;
a control valve configured to control a flow of the LNG passing through the first bypass line;
a pressure detection unit installed in the liquefied gas tank and configured to measure a pressure inside the liquefied gas tank and output a detection signal; and
a control unit configured to receive the detection signal output from the pressure detection unit and control the control valve.

### Claim 5 (depends on 2)

The cold heat recovery apparatus according to claim 2, further comprising:
an evaporator installed in rear of the liquefied gas tank in the LNG line;
a temperature detection unit installed in rear of the evaporator in the LNG line and configured to measure a temperature of the fluid passing through the evaporator and output a detection signal; and
a control unit configured to receive the detection signal output from the temperature detection unit and control a heat quantity of the evaporator.

### Claim 6 (depends on 1)

The cold heat recovery apparatus according to claim 1, wherein the cold heat usage means is a pressure control unit configured to control a pressure of the liquefied gas tank by using the cold heat of the LNG discharged from the LNG fuel tank, and the pressure control unit comprises:
an LNG line configured to transfer the LNG from the LNG fuel tank;
a heat exchanger installed in the LNG line; and
a coolant circulation line configured to circulate and supply a coolant to the heat exchanger and installed to pass through the liquefied gas tank.

### Claim 7 (depends on 6)

The cold heat recovery apparatus according to claim 6, wherein the pressure control unit further comprises:
a make-up tank configured to supply the coolant to the LNG line;
a pressure detection unit installed in the liquefied gas tank and configured to measure a pressure inside the liquefied gas tank and output a detection signal; and
a control unit configured to receive the detection signal output from the pressure detection unit and control the supply of the coolant from the make-up tank to the LNG line.

### Claim 8 (depends on 6)

The cold heat recovery apparatus according to claim 6, wherein the pressure control unit further comprises:
a coolant pump configured to provide a pumping force for circulating the coolant through the coolant circulation line;
a pressure detection unit installed in the liquefied gas tank and configured to measure a pressure inside the liquefied gas tank and output a detection signal; and
a control unit configured to receive the detection signal output from the pressure detection unit and control the pumping force of the coolant pump provided with a variable pump.

### Claim 9 (depends on 6)

The cold heat recovery apparatus according to claim 6, wherein the pressure control unit further comprises:
a second bypass line connected to the LNG line to bypass the heat exchanger;
a control valve configured to control a flow of the LNG passing through the second bypass line;
a pressure detection unit installed in the liquefied gas tank and configured to measure a pressure inside the liquefied gas tank and output a detection signal; and
a control unit configured to receive the detection signal output from the pressure detection unit and control the control valve.

### Claim 10 (depends on 1)

The cold heat recovery apparatus according to claim 1, wherein the cold heat usage means is a reliquefaction tank configured to reliquefy boil-off gas, which is supplied from the liquefied gas tank storing the liquefied gas through a gas pipeline, by using the cold heat of the LNG discharged from the LNG fuel tank, and return the reliquefied boil-off gas to the liquefied gas tank through a liquid pipeline.

### Claim 11 (depends on 10)

The cold heat recovery apparatus according to claim 10, wherein an LNG line configured to discharge the LNG from the LNG fuel tank is installed to pass through the reliquefaction tank, such that the boil-off gas is reliquefied by heat exchange with the LNG.

### Claim 12 (depends on 10)

The cold heat recovery apparatus according to claim 10, further comprising:
a gas manifold configured to supply the reliquefaction tank with boil-off gas supplied from each of a plurality of liquefied gas tanks; and
a liquid manifold configured to distribute the reliquefied gas discharged from the reliquefaction tank to each of the liquefied gas tanks and return the reliquefied gas thereto.

### Claim 13 (depends on 10)

The cold heat recovery apparatus according to claim 10, wherein the cold heat usage means further comprises a coolant circulation unit configured to transfer the cold heat of the LNG discharged from the LNG fuel tank through the circulating coolant to the reliquefaction tank.

### Claim 14 (depends on 13)

The cold heat recovery apparatus claim 13, wherein the coolant circulation unit comprises:
a heat exchanger installed in the LNG line through which the LNG is discharged from the LNG fuel tank; and
a coolant circulation line configured to circulate and supply the coolant to the heat exchanger and installed to pass through the reliquefaction tank.

### Claim 15 (depends on 11)

The cold heat recovery apparatus according to claim 11, further comprising:
a bypass line connected to the LNG line to bypass the reliquefaction tank; and
a control valve configured to control a flow of the LNG through the bypass line.

### Claim 16 (depends on 15)

The cold heat recovery apparatus according to claim 15, further comprising:
a detection unit configured to measure a temperature or pressure inside the reliquefaction tank and output a detection signal; and
a control unit configured to receive the detection signal output from the detection unit and control the control valve.

### Claim 17 (depends on 1)

The cold heat recovery apparatus according to claim 1, wherein the cold heat usage means is a heat exchanger configured to perform heat exchange between boil-off gas, which is supplied from a liquefied gas tank storing the liquefied gas through a gas pipeline, and the LNG, which is discharged from the LNG fuel tank, and return the boil-off gas to the liquefied gas tank through a liquid pipeline.

### Claim 18 (depends on 17)

The cold heat recovery apparatus according to claim 17, further comprising:
a heater installed to provide heat to an inside of the heat exchanger;
a temperature detection unit installed in the liquid pipeline and configured to measure a temperature of the reliquefied gas and output a detection signal; and
a control unit configured to receive the detection signal of the temperature detection unit and control the heater.

### Claim 19 (depends on 1)

A liquefied gas carrier for transporting liquefied gas, comprising:
a storage tank capable of storing the liquefied gas as a cargo;
an LNG fuel tank configured to store an LNG as a fuel; and
a cold heat recovery apparatus using an LNG fuel according to claims 1.

### Claim 20 (depends on 19)

The liquefied gas carrier according to claim 19, wherein the liquefied gas stored as the cargo is LPG or CO2.