Capital costs and energy considerations of different alternative stripper configurations for post combustion CO2 capture

Capturing and storing the greenhouse gas carbon dioxide produced by power plants and chemical production plants before it is emitted to the atmosphere will play a major role in mitigation climate change. Among the different technologies, aqueous amine absorption/stripping is a promising one. In this study, five different configurations for aqueous absorption/stripping have been compared with regards to capital investment and energy consumption. The process simulations are made with the use of Unisim Design and ProTreat, while for the cost calculations, data from Thrton et al. (2009) and Sinnott and Towler (2009) are used. We cannot identify one single configuration to be the optimum always for all situations, as it depends on many parameters like energy and material costs, interest rate, plant complexity, etc. With the assumption and estimated parameters in this study we find that vapor recompression configuration is the best configuration because it has the lowest total capture cost and CO2 avoided cost. In addition, the plant complexity does not increase very much compared to the benchmark. The split-stream configuration with cooling of semi-lean amine is the second best. However, this configuration increases the investment cost and plant complexity significantly. The effect of heat integration between the compression section and the stripper is also considered. We can reduce heat requirement by heat integration, but since the inlet temperature to the compressors become higher, the compression efficiency will decrease and compression work will increase. In addition, the capital cost and the complexity of the plant will increase. Because of the higher inlet temperature the water content of produced CO2 is higher and consequently the corrosion problems is more serious in pipes and equipment for compression and injection section. (C) 2011 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.