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While the demand for reduction in CO2 emission is increasing, the cost of the CO2 capture processes remains a limiting factor for large-scale application. Reducing the cost of the capture system by improving the process and the solvent used must have a priority in order to apply this technology in the future. In this paper, a definition of the economic baseline for post-combustion CO2 capture from 600 MWe bituminous coal-fired power plant is described. The baseline capture process is based on 30% (by weight) aqueous solution of monoethanolamine (MEA). A process model has been developed previously using the Aspen Plus simulation programme where the baseline CO2-removal has been chosen to be 90%. The results from the process modelling have provided the required input data to the economic modelling. Depending on the baseline technical and economical results, an economical parameter study for a CO2 capture process based on absorption/desorption with MEA solutions was performed. Major capture cost reductions can be realized by optimizing the lean solvent loading, the amine solvent concentration, as well as the stripper operating pressure. A minimum CO2 avoided cost of € 33 tonne-1 CO2 was found for a lean solvent loading of 0.3 mol CO2/mol MEA, using a 40 wt.% MEA solution and a stripper operating pressure of 210 kPa. At these conditions 3.0 GJ/tonne CO2 of thermal energy was used for the solvent regeneration. This translates to a € 22 MWh-1 increase in the cost of electricity, compared to € 31.4 MWh-1 for the power plant without capture.

In this paper the desulphurization of gas streams using aqueous copper sulphate (CuSO4) solutions as washing liquor is studied theoretically and experimentally. The desulphurization is accomplished by a precipitation reaction that occurs when sulphide ions and metal ions are brought into contact with each other. Absorption experiments of H2S in aqueous CuSO4 solutions were carried out in a Mechanically Agitated Gas Liquid Reactor. The experiments were conducted at a temperature of 293 K and CuSO4 concentrations between 0.01 and 0.1 M. These experiments showed that the process efficiently removes H2S. Furthermore, the experiments indicate that the absorption of H2S in a CuSO4 solution may typically be considered a mass transfer limited process at, for this type of industrial process, relevant conditions. The extended model developed by Al-Tarazi et al. (2004) has been used to predict the rate of H2S absorption. This model describes the absorption and accompanying precipitation process in terms of, among others, elementary reaction steps, particle nucleation and growth. The results from this extended model and results obtained with a much simpler model, regarding the absorption of H2S in CuSO4 containing aqueous solutions as absorption of a gas accompanied by an instantaneous irreversible reaction were compared with experimental results. From this comparison it appeared that the absorption rate of H2S in a CuSO4 solution can, under certain conditions, be considered as a mass transfer rate controlled process. Under a much wider range of conditions the error that is made by assuming that the absorption process is a mass transfer controlled process, is still within engineering accuracy. Application of the simple model allows for a considerable reduction of the theoretical effort needed for the design of a gas-liquid contacting device, thereby still assuring that the desired gas specification can be met under a wide range of operating conditions. A comparison of the experimental results and the simulated results showed that the extended model gives an under prediction of the H2S absorption rate for the experimental conditions applied.