Moving Bed Temperature Swing Adsorption (MBTSA) for post combustion CO2 capture

This work considers the utilization of a Moving Bed Temperature Swing Adsorption (MBTSA) process for post-combustion CO2 capture in the context of Natural Gas Combined Cycle (NGCC) power plants. A detailed mathematical model consisting of energy, mass and momentum balances was implemented in gPROMS Model Builder®, in order to investigate the system behavior under different operating conditions and design parameters. The set of coupled differential equations, implemented for each section of the moving bed (adsorption, desorption and cooling section), has to be solved simultaneously for continuous process simulations. For this purpose, the individual units were connected to each other in a “composite model" flowsheet. With the gPROMS® composite model approach, the different sections of the moving bed communicate with each other through specifically designed variable-ports. The purpose of these inlet-outlet ports is to transfer certain model variables (e.g. concentrations, temperature, pressure) at the boundary of the corresponding section-space domain, so that the model instances can exchange information with the adjacent model instances during simulation. Results show that under the simulated process conditions, the system is suitable for capturing CO2 at high purity and high capture rate. The effect of implementing the MBTSA process on plant performance was studied, by integrating the capture system with a process model of the reference power plant. A detailed analysis of the energy use associated with the capture process auxiliaries was performed. Finally, the power plant model was used to simulate the same NGCC system coupled with a state-of-the-art absorption process, for a direct comparison between the two capture technologies.