Flexibility of low-CO2 gas power plants: Integration of the CO2 capture unit with CCGT operation

摘要

CCGT power is well-positioned for flexible operation due to its favorable dynamic character and is likely to play a significant role in the future intermittent power generation mix, specifically with an increasing penetration of intermittent renewable power capacity. However, concerns exist around the impact of adding Carbon Capture & Storage on the flexibility of low-CO2 fossil fuel power plants. This paper presents the results of a study on the dynamics of a carbon capture plant in order to address the impact on flexibility. This will enable the development of the learning curve to improve flexibility of future commercial scale CCGT-CCS plants. A dynamic model was set-up for a CCS retrofit on an existing typical commercial CCGT plant. Various load-following, shutdown and start-up scenarios were studied. It was concluded that flexibility of gas-fired power plants for mid-merit cycling or base-load operation does not have to be limited by the addition of post-combustion CO2 capture. It was concluded that only startup scenarios may lead to additional CO2 losses, which can be limited by appropriate design. Various options to enhance start-up response have been identified and require further study and development to explore their value. The dynamic modelling capability built for this study provides an excellent tool to do this. It is noted that, starting from early FOAK CCGT-CCS power plants, a learning curve will be required to further develop flexible operation. Reference is made to the learning curve that delivered the current flexibility of CCGT power plants, where the steam cycle follows load Variations on the gas turbine.