Review on Boil-Off Gas (BOG) Re-Liquefaction System of Liquefied CO2 Transport Ship for Carbon Capture and Sequestration (CCS)

Abstract

This paper presents the review on the boil-off gas re-liquefaction system of liquefied CO2 transport ship for carbon capture and sequestration (CCS). It is assumed that liquefied CO2 is transported between South Korea and Middle East for enhanced oil recovery (EOR) and enhanced gas recovery (EGR), which is similar to the oil and LNG transportation route. The concept of open re-liquefaction cycle which means that the boil-off CO2 is compressed, cooled, and expanded before being piped back into the tank is suggested. The effects of impurities on the re-liquefaction cycle is investigated under the condition of fixed cooling capacity in terms of cycle performance and reliability. Specifications of LCO2 transport ship about storage tank and re-liquefaction system is reviewed. In addition, economic feasibility is investigated. As for the case of the present study, negative effects of impurities on the cycle performance and reliability should be considered due to its considerable effects. Conservatively calculated internal rate of return (IRR) of the re-liquefaction system shows 4.1%, therefore, it can be guessed that the BOG re-liquefaction system will have economic validity in the future CCS chain.