Retrofitting CO 2 capture ready fossil plants with post-combustion capture. Part 2: Requirements for natural gas combined cycle plants using solvent-based flue gas scrubbing

Abstract

A number of natural gas combined cycle (NGCC) power stations recently permitted in the UK have been required to be CO₂ capture ready so that carbon capture and storage can be retrofitted once it is commercially viable (or legally required). Several options for future CO₂ capture from NGCC units can be envisaged including post-combustion capture technology using flue gas scrubbing with aqueous solvents. When an NGCC plant is designed to be ready for a retrofit with post-combustion capture, one of the most important technical considerations is the steam extraction pressure and flow to provide the energy necessary for solvent regeneration. This is determined by the choice of solvent used, but new solvents are being developed and the exact future requirements, in perhaps 10–20 years time, cannot be predicted. Ways in which designs for the steam cycle of NGCC plants can cope with this challenge are presented. Several alternatives to mitigate the loss of power output of NGCC plants retrofitted with post-combustion capture and to achieve improved plant flexibility are also assessed and compared.