Advance thermodynamic analysis of a CO2 compression system using heat-pump for CCS

Abstract

CO2 pressurization represents a significant portion of energy penalty resulting from CO2 capture in carbon capture and storage process (CCS). Effective measures to improve the pressurization scheme directly translates into an improvement of plant economics. In this paper we aim to reduce the energy expenditure of CO2 pressurization step in the CCS process by assisting the CO2 multi-stage compressors with a heat-pump system. The CO2 compressors raised CO2 pressure to an intermediate liquefaction pressure. Afterwards, the CO2 is liquefied in the heat-pump and subsequently pumped to the high pressure instead of being compressed. In addition to the conventional energetic analysis, the advance exergy analysis of the heat-pump assisted pressurization scheme is also presented. The advance exergy analysis of the proposed strategy reveals the optimum operating parameters and design of the heat pump system. Through the implementation of results obtained by the advance exergetic analysis, it was found out the proposed system can achieve 6.21% saving in electric power.