We’re delighted to share with our community the publication of Dr Solomon Brown’s new paper, Transient CO2 capture for open-cycle gas turbines in future energy systems, co-authored with Mathew Dennis Wilkes and Sanjay Mukherjee from the University of Sheffield (also our host institution). Solomon is a member of our core research team.
With the expected increase in small-scale decentralised power, this paper evaluates the operation of a CO2 capture plant attached to a small scale open-cycle gas turbine (OCGT) power station. The quick-response nature of OCGTs can aid in balancing the grid, providing system security and much needed flexibility as a result of intermittent renewables. Data from the Balancing Mechanism Reporting Service (BMRS) is used to analyse the behaviour of these transient generators. Operational data on OCGT generation showed highly sporadic operation, used for peak demand typically in the evenings with an average operating time of 5-hours. The data also shows ramping to different power outputs in the same operating cycle, with multiple operating cycles in a 24-hour period. The BMRS data is used alongside information from industrial vendors to create exhaust gas flowrate profiles, which are used as an input into the capture model. The study presents the development and validation of a dynamic rate-based model of the benchmark CO2 absorption process using 30 wt% monoethanolamine (MEA). The model is scaled up from pilot-scale to match the flue gas output from a modern 10 MWe OCGT power station. Simulations of various flexible operating scenarios shows the rapid transitioning between full and partial load is beneficial in delivering higher time-averaged CO2 capture rates, compared to the Baseload scenario where the PCC system is operated at full load for 5-hours. The simulations include the start-up and shutdown procedures, resulting in the capture rate decreasing at full-load as the system stabilises. Maintaining a constant liquid/gas (L/G) ratio results in 90% time-averaged CO2 capture; however, the energy demand increases due to constant reboiler steam flowrate. To compensate, the steam flowrate is also ramped in accordance with flue gas changes, resulting in a small decrease in reboiler duty compared to the Baseload scenario. Importantly, no negative energy or capture rate related issues to highly-transient PCC operation are found.