Liquefied gas treatment system

• US 10,767,921 B2
• Filed: 06/23/2016
• Issued: 09/08/2020
• Est. Priority Date: 05/30/2013
• Status: Active Grant

• Current Assignee: Hyundai Heavy Industries Company Limited (Korea Shipbuilding & Offshore Engineering Co., Ltd.)
• Original Assignee: Hyundai Heavy Industries Company Limited (Korea Shipbuilding & Offshore Engineering Co., Ltd.)
• Inventors: Baek, Eun Sung
• Primary Examiner(s): Raymond, Keith M
• Assistant Examiner(s): Megesha, Webeshet
• Application Number:
  US15/191,486
• Publication Number:
  US 20160305709A1
• Time in Patent Office: 1,538 Days
• CPC Class Codes: F02M 21/0221 Fuel storage reservoirs, e.g. cryogenic tanks
• CPC Class Codes: F17C 2201/0157 Polygonal
• CPC Class Codes: F17C 2201/052 large (>1000 m3)
• CPC Class Codes: F17C 2203/0391 by vacuum
• CPC Class Codes: F17C 2203/0629 Two walls
• CPC Class Codes: F17C 2203/0639 Steels
• CPC Class Codes: F17C 2221/033 Methane, e.g. natural gas, CNG, LNG, GNL, GNC, PLNG
• CPC Class Codes: F17C 2223/0161 cryogenic, e.g. LNG, GNL, PLNG
• CPC Class Codes: F17C 2223/033 Small pressure, e.g. for liquefied gas
• CPC Class Codes: F17C 2223/035 High pressure (>10 bar)
• CPC Class Codes: F17C 2223/043 in the gas
• CPC Class Codes: F17C 2225/0123 gaseous, e.g. CNG, GNC
• CPC Class Codes: F17C 2225/033 Small pressure, e.g. for liquefied gas
• CPC Class Codes: F17C 2225/035 High pressure, i.e. between 10 and 80 bars
• CPC Class Codes: F17C 2227/0164 with specified compressor type, e.g. piston or impulsive type
• CPC Class Codes: F17C 2227/0306 using the same fluid
• CPC Class Codes: F17C 2227/0309 using another fluid
• CPC Class Codes: F17C 2227/036 "Joule-Thompson" effect
• CPC Class Codes: F17C 2250/0443 Flow or movement of content
• CPC Class Codes: F17C 2265/036 with heating
• CPC Class Codes: F17C 2265/037 : with pressurising
• CPC Class Codes: F17C 2265/066 : for feeding engines for propulsion
• CPC Class Codes: F17C 2270/0105 : Ships
• CPC Class Codes: F17C 7/04 : with change of state, e.g. vaporisation
• CPC Class Codes: F17C 9/02 : with change of state, e.g. vaporisation
• CPC Class Codes: F25J 1/0025 : Boil-off gases "BOG" from storages
• CPC Class Codes: F25J 1/0035 : by gas expansion with extraction of work
• CPC Class Codes: F25J 1/004 : by flash gas recovery F25J1/0267 takes precedence
• CPC Class Codes: F25J 1/0045 : by vaporising a liquid return stream
• CPC Class Codes: F25J 1/0202 : in a quasi-closed internal refrigeration loop F25J1/0208, F25J1/0219, F25J1/0224 take precedence
• CPC Class Codes: F25J 1/023 : for the combustion as fuels, i.e. integration with the fuel gas system
• CPC Class Codes: F25J 1/0254 : controlling particular process parameter, e.g. pressure, temperature
• CPC Class Codes: F25J 1/0298 : Safety aspects and control of the refrigerant compression system, e.g. anti-surge control
• CPC Class Codes: F25J 2240/02 : Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream
• CPC Class Codes: F25J 2240/40 : Expansion without extracting work, i.e. isenthalpic throttling, e.g. JT valve, regulating valve or venturi, or isentropic nozzle, e.g. Laval
• CPC Class Codes: F25J 2290/62 : Details of storing a fluid in a tank
• CPC Class Codes: Y02T 10/30 : Use of alternative fuels, e.g. biofuels

Abstract

A liquefied gas treatment system according to an embodiment of the present invention includes a boil-off gas heat exchanger exchanging heat between boil-off gas, pressurized by a boil-off gas compressor and recovered along a boil-off gas supply line branching off upstream of a liquefied gas-consuming unit, and the boil-off gas supplied from a liquefied gas storage tank, wherein the boil-off gas heat exchanger cools the boil-off gas, recovered along the boil-off gas supply line, with the boil-off gas, supplied from the liquefied gas storage tank, or flash gas, supplied through a vapor recovery line.

Claims

1. A liquefied gas treatment system, comprising:

a boil-off gas supply line connected from a liquefied gas storage tank to a liquefied gas-consuming unit;

a boil-off gas compressor provided on the boil-off gas supply line and pressurizing boil-off gas generated from the liquefied gas storage tank;

a boil-off gas heat exchanger provided upstream of the boil-off gas compressor on the boil-off gas supply line and exchanging heat between the boil-off gas, pressurized by the boil-off gas compressor and recovered along the boil-off gas supply line branching off upstream of the liquefied gas-consuming unit, and the boil-off gas supplied from the liquefied gas storage tank;

a boil-off gas decompressor provided downstream of the boil-off gas heat exchanger on a flow of the boil-off gas, recovered along the boil-off gas supply line, and decompressing the boil-off gas pressurized by the boil-off gas compressor;

a vapor-liquid separator separating flash gas from the boil-off gas decompressed by the boil-off gas decompressor;

a vapor recovery line connected from the vapor-liquid separator to the boil-off gas heat exchanger and supplying the flash gas to the boil-off gas heat exchanger;

a flash gas recovery line extending the vapor recovery line from the boil-off gas heat exchanger to a mixer;

the mixer provided upstream of the boil-off gas heat exchanger on the boil-off gas supply line, configured to mix the boil-off gas, supplied from the liquefied gas storage tank, with the flash gas, heat-exchanged by the boil-off gas heat exchanger, and supplying mixed gases to the boil-off gas heat exchanger;

a first valve positioned between the boil-off gas heat exchanger and the mixer and configured to control flow of the flash gas supplied to the boil-off gas compressor by exhausting the flash gas to an outside of the liquefied gas treatment system;

a flash gas bypass line branching off from the vapor recovery line and connected to a position between the first valve and the boil-off gas heat exchanger; and

a second valve configured to control flow of the flash gas supplied to the position between the first valve and the boil-off gas heat exchanger through the flash gas bypass line.

2. The liquefied gas treatment system of claim 1, wherein the first valve is a three-way valve configured to discharge the flash gas to an outside of the liquefied gas treatment system.

3. The liquefied gas treatment system of claim 1, wherein the second valve is a three-way valve provided between the vapor-liquid separator and the heat exchanger on the vapor recovery line.

4. The liquefied gas treatment system of claim 1, wherein the boil-off gas, heat-exchanged by the boil-off gas heat exchanger, is supplied to the boil-off gas decompressor or the boil-off gas compressor.

5. The liquefied gas treatment system of claim 1, wherein the flash gas, heat-exchanged by the boil-off gas heat exchanger, is supplied to and combusted in a gas combustion unit combusting fuel.

6. The liquefied gas treatment system of claim 1, further comprising a liquid recovery line connected from the vapor-liquid separator to the liquefied gas storage tank and recovering the boil-off gas in liquid state, separated by the vapor-liquid separator, to the liquefied gas storage tank.

7. The liquefied gas treatment system of claim 1, wherein the boil-off gas decompressor is a Joule-Thomson valve.

8. The liquefied gas treatment system of claim 1, wherein the boil-off gas compressor comprises a plurality of boil-off gas compressors.

9. The liquefied gas treatment system of claim 1, further comprising a boil-off gas cooler associated with the boil-off gas compressor.

10. The liquefied gas treatment system of claim 8, further comprising at least one boil-off gas cooler provided between the plurality of boil-off gas compressors.

11. The liquefied gas treatment system of claim 1, further comprising a third valve provided at a position where the boil-off gas supply line branches off to the boil-off gas heat exchanger.

12. The liquefied gas treatment system of claim 1, wherein the vapor recovery line connected from the vapor-liquid separator to the boil-off gas heat changer is connected through the boil-off gas heat exchanger to the flash gas recovery line connecting the boil-off gas heat exchanger to the mixer provided upstream of the boil-off gas heat exchanger.

13. The liquefied gas treatment system of claim 1, wherein the liquefied gas-consuming unit comprises a dual fuel engine to which boil-off gas or oil is selectively supplied without mixing the boil off gas and oil with each other.