Demonstrating load-change transient performance of a commercial-scale natural gas combined cycle power plant with post-combustion CO2 capture

Dynamic simulations of three gas turbine load-change ramp rates (2%/min, 5%/min and 10%/min) showed that the total stabilization times of the power plant's main process variables are shorter (10-30 min) than for the PCC unit (1-4 h). A dynamic interaction between the NGCC and the PCC unit is found in the steam extraction to feed the reboiler duty of the PCC unit. The transient performance of five decentralized PCC plant control structures under load change was analyzed. When controlling the CO2 capture rate, the power plant performs in a more efficient manner at steady-state part load; however, the PCC unit experiences longer stabilization times of the main process variables during load changes, compared with control structures without CO2 capture rate being controlled. Control of L/G ratio of the absorber columns leads to similar part load steady-state performance and significantly faster stabilization times of the power plant and PCC unit's main process variables. It is concluded that adding the PCC unit to the NGCC does not significantly affect the practical load-following capability of the integrated plant in a day-ahead power market, but selection of a suitable control structure is required for efficient operation of the process under steady-state and transient conditions.