Simulation and Optimization of a Rotary Temperature Swing Adsorption (RTSA) Process for CO₂ Capture

A rotary temperature swing adsorption process (RTSA) coupled with a cryogenic purification unit (CPU) was evaluated for capturing and concentrating CO₂ from the natural gas combustion cycle (NGCC) flue gas. With a Lewatit sorbent, a 4-step RTSA process coupled with CPU was optimized to study the levelized cost of electricity (LCOE) and specific primary energy consumption for CO₂ avoided (SPECCA). The RTSA process was able to concentrate the CO₂ to 95% on a dry basis, and with the addition of the CPU, the CO₂ was concentrated to 100%. From the optimization of the process, the LCOE was found to be 86.2 €/MWh. The SPECCA value was 2.29 MJ/kg. The cost of CO₂ avoided was 76.4€/tonne. The LCOE of the RTSA process was 6% lower compared to a fixed bed containing monoliths, while the SPECCA was higher due to the high steam velocities chosen by the optimizer for the RTSA process. For the 4-step TSA process with a steam purge step, nearly 99% of the specific energy consumption was due to the steam generation process.