CONTROL STRATEGIES FOR FLEXIBLE OPERATION OF POWER PLANT INTEGRATED WITH CO2 CAPTURE PLANT

Amine-based CO2 capture schemes have been developed to reduce CO2 emission from coal-fired power plant. Large electricity penalties will be incurred due to heat required for CO2 desorption. It was suggested this loss can be partially compensated by flexible operation. However, daily large variations of liquid and gas flows may cause operation problems to packed columns. In this work, control schemes were proposed to improve the flexibility of power output without causing substantial hydraulic disturbances in the capture plant. They were verified by steady state and dynamic simulations using ASPEN Plus. In varying lean solvent flow strategy, the flow-rate of recycling solvent was manipulated to control the CO2 capture rate. The gas flow in the absorber and the gas/liquid ratio in the stripper will remain constant relatively. The liquid flow of the absorber and gas flow of the stripper will vary. In an alternative strategy, the lean solvent loading will be varied. Also, variation of gas throughput in the stripper is avoided by recycling part of CO2 vapor to stripper. This strategy provided the stable hydraulics condition in both columns. Power output is similar compared to the previous scheme.