Exergetic comparison of different oxyfuel technologies


CIRCE (Research Centre for Energy Resources and Consumption), Universidad de Zaragoza, Mariano Esquillor, 15, 50018 Zaragoza, Spain


Carbon Capture and Storage (CCS) systems have relevant energy consumption associated with the CO2 capture process. It causes an energy efficiency reduction that diminishes the economic interests and increases the technical uncertainty of these systems. With the objective of improving the system perform-ance and reducing thermodynamic inefficiencies, the exergy analysis has been traditionally applied as a guide for design process. This work presents and compares energy and exergy analysis of two CCS sys-tems based on pressurized oxyfuel combustion, a pressurized fluidized bed combustion working under oxyfiring conditions and a chemical looping combustion using coal as fuel. The aim is to calculate CCS energy and exergy penalties, detecting irreversibilities and proposing items for optimization. It is demon-strated that opposed to energy penalty, the exergy losses do extend neither in the same quantity nor in the same equipment, leading to outstanding conclusions for system improvements. As it will be demon-strated, the exergy penalty of additional equipment for CO2 capture does not cause relevant losses and these irreversibilities are concentrated in several systems that should be redesigned or analysed in detail to reduce the losses.