Simulation and Cost Comparison of CO2 Liquefaction

Liquefaction of CO2 is an intermediate step for storage or ship transport. Two processes are suggested. The traditional method is based on external refrigeration and the other is an integrated refrigeration process. In the external refrigeration process, traditional refrigeration based on ammonia was selected. In the internal refrigeration process, liquefaction is achieved by compression, cooling and expansion of the CO2. Simulation models in Aspen HYSYS have been developed for different alternatives. A process based on ammonia refrigeration was calculated to be most cost optimum. There are however still possibilities for improvements especially for the internal refrigeration process.