Flue-gas cooling in post-combustion capture plants

In the present paper, the results of an activity performed in the ongoing EU project, CESAR (CO2 Enhanced Separation and Recovery) are presented. In the CESAR project five different baseline power-plants are considered. These consist of two lignite- and two bituminous-coal fired plants while the fifth is fuelled by natural gas. Part of the design work relates to identifying the benefits attainable through appropriate integration of flue-gas cooling to these baseline power-plants. It is shown that the approximate reductions in capture-cost for the studied (optimal) cases are of the order of 20% for the lignite-coal cases, 10% for the bituminous coal cases and 13% for the natural gas case using MEA as solvent. The reductions are basically due to the inclusion of pre-cooling. However, a positive effect of inter-cooling was also found for all the coal cases, while a negative cost effect was found for the natural gas case. For piperazine as solvent the positive effect of cooling was much more pronounced than for MEA and especially the effect of inter-cooling.

► Effect of flue-gas pre-cooling and/or inter-cooling for 5 various power plants with post-combustion capture.
► The energy effect and capture cost is dependent on the specific solvent.
► All cases exhibit a positive energy effect of pre-cooling.
► Combination of pre-cooling and inter-cooling has a positive effect for all coal-based power plants.
► There is no energy effect of inter-cooling and a negative effect on capture cost for the natural gas based power plant case.