US 12,006,017 B2
Boil-off gas reliquefication apparatus and method for vessel
Hyun Jun Shin, Seoul (KR); Su Kyung An, Gwangmyeong-si (KR); and Seung Chul Lee, Seoul (KR)
Assigned to HANWHA OCEAN CO., LTD., Geoje-si (KR)
Filed by DAEWOO SHIPBUILDING & MARINE ENGINEERING CO., LTD., Geoje-si (KR)
Filed on Jan. 13, 2021, as Appl. No. 17/148,182.
Application 17/148,182 is a continuation of application No. 16/090,115, abandoned, previously published as PCT/KR2016/011007, filed on Sep. 30, 2016.
Claims priority of application No. 10-2016-0039516 (KR), filed on Mar. 31, 2016.
Prior Publication US 2021/0129970 A1, May 6, 2021
Int. Cl. F17C 9/04 (2006.01); B63B 25/16 (2006.01); B63J 2/14 (2006.01); F02M 21/02 (2006.01); F17C 6/00 (2006.01); F17C 9/02 (2006.01); F25J 1/00 (2006.01)
CPC B63J 2/14 (2013.01) [B63B 25/16 (2013.01); F02M 21/0215 (2013.01); F17C 6/00 (2013.01); F17C 9/02 (2013.01); F17C 9/04 (2013.01); F17C 2221/033 (2013.01); F17C 2227/0164 (2013.01); F17C 2227/0185 (2013.01); F17C 2227/0339 (2013.01); F17C 2227/0348 (2013.01); F17C 2227/0358 (2013.01); F17C 2265/033 (2013.01); F17C 2265/034 (2013.01); F17C 2265/037 (2013.01); F17C 2265/038 (2013.01); F17C 2265/066 (2013.01); F17C 2270/0105 (2013.01); F25J 1/0025 (2013.01)] 6 Claims
OG exemplary drawing
 
1. A method of operating a ship comprising a cargo storage tank storing liquefied cargo gas, an engine, a fuel tank storing liquefied fuel for the engine, and a fuel vaporizer for vaporizing liquefied fuel from the fuel tank for supplying to the engine,
wherein the method comprises:
compressing, at a multistage compressor, boil-off gas (BOG) discharged from the cargo storage tank to provide compressed BOG (CBOG);
cooling, at a first heat exchanger, a flow of the CBOG from the multistage compressor by heat exchanging with a flow of the BOG flowing from the cargo storage tank to the multistage compressor to provide a flow of cooled CBOG;
branching off, from the flow of cooled CBOG, a first flow of cooled CBOG and a second flow of cooled CBOG;
expanding, at a first expansion unit, the first flow of cooled CBOG to further cool the first flow;
cooling, in a second heat exchanger, the second flow of cooled CBOG by heat exchange with the first flow from the first expansion unit;
cooling, at the fuel vaporizer, a cooled second flow from the second heat exchanger by heat exchange with liquefied fuel from the fuel tank to further cool the cooled second flow; and
expanding, at a second expansion unit, the further cooled second flow from the fuel vaporizer to re-liquefy at least portion of the further cooled second flow for returning to the cargo storage tank,
wherein at the fuel vaporizer, the cooled second flow from the second heat exchanger is further cooled by heat exchange with the liquefied fuel before the further cooled second flow is sent to the second expansion unit whereas the liquefied fuel is heated and gasified by heat exchange with the cooled second flow from the second heat exchanger such that the gasified fuel is supplied to the engine,
wherein the multistage compressor comprises a first compressor, a second compressor, and a first cooler interposed between the first compressor and the second compressor, wherein that a flow of the BOG compressed at the first compressor is cooled at the first cooler prior to further compression at the second compressor;
wherein the method further comprises returning the first flow that cooled the second flow at the second heat exchanger, to a point of the multistage compressor between the first compressor and the first cooler.