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IEA Greenhouse Gas R&D Programme

67 Prachi aPost combustion CO2 capture technology is one of the potential technologies which will most likely to be applied at large scale CO2 capture facilities in power plants. One of the main concerns for the solvent based CO2 post combustion capture (PCC) technology for power plant is the relatively large energy penalty. A reduction in energy penalty for solvent based CO2 post combustion capture process can be achieved by improving solvent properties, better integration with power plant as well as by improving process design. Regarding to the improvement in process design, different process flow sheet modifications have been reported in various literature and patents for chemical solvent based CO2 absorption processes. These process modifications reduce the energy penalty imposed by the CO2 post combustion capture plant.

The proposed process flow sheet modifications are multi-component column, inter-stage temperature control, heat integrated stripping column, split flow process, vapour recompression, matrix stripping and various heat integration options. Comparison of these reported modifications was difficult as these were evaluated based on different solvent properties and process conditions. Also there are some process modifications more suitable for particular solvent than the others. In order to identify the suitable process modification for full scale PCC application it was necessary to evaluate further in detail these modifications on the same process condition for their energy savings, additional unit required and additional cost.

Therefore, there was a requirement to evaluate these process modifications on similar solvent and process conditions with a state of the art rate-based CO2 absorption model. This IEAGHG study evaluate the feasibility of these different amine-based CO2 post combustion capture process modifications for coal and natural gas based power plants.

In this study post combustion capture process improvements that are already well established such as intercooling in the absorber and improved heat integration with power plant, combined with improved solvents typical of those that are expected to become available by 2020, is implemented for the coal and natural gas power plant base case. These improvements should substantially reduce the efficiency penalty on power plant. Further in this study various process modifications were investigated for coal and natural gas power plants.

Overall it can be noticed from this study that once all current improvements have been implemented in the solvent based post combustion capture process, different process modifications for coal and natural gas power plant, only bring sljosirt improvements in the power plant efficiency penalty.

The performance and cost of different post combustion capture process modifications depend on the type of solvent used. Therefore, for new solvents further evaluation for all process modifications will be required.