Technical and economic feasibility study of boil-off gas reliquefaction system on an LNG tanker

Abstract

This paper investigated the technical and economic feasibility of on-board boil-off gas reliquefaction system on a liquefied natural gas tanker ship which has 154,852 m3 cargo tank capacity operated in Tangguh Field Indonesia by comparing three systems available in the market for mini liquefied natural gas liquefaction, i.e. single nitrogen system, ethylene and propylene refrigerant system, and Joule Thomson cycle. All three systems were evaluated through chemical process modelling software and through sensitivity analysis by varying the boil-off gas and liquefied natural gas price comparing the net present value and internal rate of return. The sensitivity analysis result shows that the Joule Thomson cycle is more economic compared than the other two systems within the range of marine gas oil price must not higher than US$640/ton on liquefied natural gas price US$10/mmbtu or liquefied natural gas price must not less than US$7/mmbtu on marine gas oil price US$400/ton.