Process Simulation of Power Generation Systems with CO2 Capture

The increase in the anthropogenic greenhouse gases has severely damaged the environment in terms of pollution and global climate change. It is capturing the carbon dioxide from the present and future power plants that could save the climate. The post-combustion CO2 capture system using amine wet scrubbing is investigated in detail for natural-gas fired power plant from pilot-scale to commercial-scale level. The research work is focused on the investigation of the different innovative modifications to the micro gas turbine (MGT) including exhaust gas recirculation (EGR), steam injection and humid air turbine. The process models are developed for both MGT and pilot-scale amine-based CO2 capture plant. The MGT model is tuned and validated with extensive experimental data at different part load conditions for base case, CO2, steam and simultaneous CO2 and steam injection to the default MGT. The thermodynamic behaviour, emissions, system efficiency and the sensitivity of the base case MGT for ambient conditions are explored. The robust model is extended for EGR, steam injection and humid air turbine system models; and process system performance comparison for the different modifications is assessed for possible recommendation. In addition, the impact of the operating conditions and locations of the EGR on the performance of the MGT is also analysed. Further, the effect of the enhanced CO2 on the extensively validated pilot-scale amine-based CO2 capture plant integrated with MGT is examined. In addition, the sensitivity analysis of the pilot-scale amine-based CO2 capture model is studied to quantify the effect of the operating parameters on the system performance and to estimate the optimum operating envelope. The EGR at 55 % resulted in a 20.5 % decrease in specific reboiler duty from the pilot-scale amine-based CO2 capture plant at the CO2 capture rate of 90 % for monoethanolamine at 30 wt. % aqueous solution. Furthermore, a techno-economic process design and/or scale-up of the commercial-scale amine-based CO2 capture system to service about 650 MWe of the natural gas-fired power plant system with and without EGR is investigated for varying EGR percentage. Finally, thorough comparative potential for the natural gas, coal, biomass fired and co-firing of coal and biomass power plants integrated with CO2 capture and CO2 compressions system are explored for different cases of each power plant. The biomass firing resulted in about 40 % increase in fuel flow rate for the constant heat input case while it resulted in 30 % derating of the power output for the constant fuel flow rate case. The comparative potential of gas-CCS, coal-CCS and BECCS has shown that the NGCC with EGR resulted in the least efficiency penalty on integration with CO2 capture and compression system due to the higher net efficiency. However, coal and biomass fired power plant resulted in the least specific losses per unit of the CO2 capture on integration with CO2 capture and compression system due to the higher specific CO2 capture.