A thermo-economic comparison on new and conventional alternatives of pressurization of CO2 in CCS systems

Abstract

The final stage of carbon capture and storage processes involves the pressurization of CO₂ by a suitable method which is conventionally carried out through a series of compressors with intercoolers in between them. In the present study, the idea of liquefying the captured CO₂ is considered. Four different systems for the liquefaction process are evaluated and compared Thermo-economically with the benchmark system of direct carbon dioxide compression. The results indicate that the EPLS system outperforms the others, with a product cost 5.89% lower than the benchmark system. Evaluations show that most of the costs are imposed by the initial compression stage in each system. A detailed investigation of the sensitivity analysis shows that the benchmark and claude systems have the largest dependency on pressure ratio and intercooling temperature, respectively. Additionally, evaluation of the economic parameters indicates that the changes in unit cost of power have the most effect on the benchmark system while the interest rate affects the results of claude and DEBARS more than other options. Detailed evaluations reveal that the EPLS layout has the advantage of less dependency on the changes of operating parameters and on the other hand, the cost of input heat, the maintenance factor, and the generator and evaporator temperatures make a high difference in the final product cost of the DEBARS. Finally, the effect of pressure drops in heat exchangers is investigated and results reveal that the consideration of pressure drops leads to power penalties ranging from 0.97 to 8.52 $/hr in different systems.