LIQUEFACTION OF CAPTURED CO_2 FOR SHIP-BASED TRANSPORT

摘要

This paper presents a new cost and energy efficient liquefaction process for CO_2. Presently CO_2 is transported in ships or trucks in semi-pressurized vessels at a pressure of 14-20 bar. For economic large-scale transport of CO_2 by ship the CO_2 should be transported semi-pressurized at pressure near the triple point e.g. at 6.5 bar and -52 ℃. At this pressure, the technology and experience from building and operation of conventional LPG tankers can be utilised, and large pressurized cargo tanks can be produced in an economical way. Care must be taken to avoid dry ice formation in the process plant, storage and when loading and unloading. Large-scale liquefaction of CO_2 is best achieved in an open cycle, using the CO_2 feed as the refrigerant where the refrigeration is partly or fully provided by the feed gas itself. The plant delivers CO_2 at 6.5 bar and -52℃ to the storage tanks. The capacity of the liquefaction plant is 1.0 mill ton CO_2 per year. The technology can be used in plants between 0.5 and 2.5 mill tonne CO_2/year. The power consumption is 110 kWh/tonne liquid CO_2.