Simulation and optimization for power plant flue gas CO2 absorption-stripping systems

Performance characteristics and design optimization for industrial-scale coal-tired and natural-gas-fired power plant flue gas CO2 absorption-stripping systems, using MEA (monoethanolamine) and mixed-DGA/MDEA (diglycolamine/methyldiethanolamine) aqueous solutions, are investigated by computer simulation. A rigorous model adopted from the literature, built on RATEFRAC of Aspen Plus, is used to simulate the complex reactive absorption behaviors. Column profiles and mass transfer characteristics as well as the effects of design variables for conventional, conventional with absorber intercooler and split-flow schemes are analyzed. Major design variables for each scheme are identified. Both intercooler and split-flow schemes are beneficial. The split-flow scheme is examined from three aspects for its applicability. Design optimizations by the logical search plan method are performed for both coal-fired and natural-gas-fired CO2 recovery systems using MEA aqueous solution. Compared to practical initial designs, the optimized designs provide cost reductions of 10% and 26% for intercooler and split-flow schemes, respectively.