Cargo Conditions of CO2 in Shuttle Transport by Ship

AbstractFor shuttle transport of liquid CO2 in ship-based CCS, the cargo conditions were investigated in view of the pressure tank manufacturability, the cost of the tanks and the carrier vessel, the total energy efficiency of the CO2 flow, etc.In a CCS chain, since the critical path might be the injectivity of the well, the unit cargo of a carrier vessel is set to 3000 tonnes, which is equivalent to the Sleipner case, annual injection rate of ca. 1 million tonnes.The physical properties of CO2, specifically the vapor liquid equilibrium properties of CO2, are such that the design of a storage tank for the containment of liquid carbon dioxide is very similar to existing designs for intermediate pressure liquefied petroleum gas (LPG) containment systems. The design methodology for LPG cargo tanks is well understood and is regulated by international standards (specifically the “International Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk”; IGC code) and Classification Societion Societies (such as DNV, BV and LRS) The disign methodology employed in this study, which is for the marine transport of LCO2 is exactly the same as described by the IGC code and subject to Classification Society rules. These design rules are well proven with literally hundreds of LPG carriers operating worldwide in an industry that has an excellent safety record since the advent of LPG bulk marine transport in the early 1960s. The proposed ship design which installs two cargo tanks was as follows:-the volume of the tanks is about 1500m3 and design pressure and temperature are 3.10MPa and munus 10degC, respectively.-The shape of the tanks is a cylindrical bilobe with single cylinder radius of 3.50 m and 26.96m in lengthThe necessary facilities for LCO2 loading from land-based storage tanks are also examined, including CO2 buffer storage tanks, the loading pumps, the loading arms, and so on. The offshore delivery and injection system are investigated and the resultant design proposal was as follows: the temperature of the cargo LCO2 is raised to 5degC by on-board heat exchange system using the ambient seawater.The cost estimate of the proposed system will be also given in the presentation.The study is a part of the Preliminary Feasibility Study on CO2 Carrier for Ship-based CCS and its follow-up study sponsored by Global CCS Institute and conducted by Chiyoda Corporation. The other technical parts of the study are Ship-based offshore CCS featuring CO2 shuttle ships equipped with injection facilities by M Ozaki et al, “Offshore operational availability of onboard direct injection of CO2 into sub-seabed geological formations” by T Miyazaki et al, and “Onboard CO2 injection into subseabed geological formation via picked-up flexible pipe by N. Nakazawa et al