Optimisation of carbon dioxide recovery from flue gas in a TPSA system

Power stations and industrial processes burning fossil fuels account for the largest percentage of carbon dioxide emissions. Carbon capture and sequestration has received enormous global attention to reduce the carbon footprint and combat global warming. Adsorption has become an alternative technique to the conventional absorption process for capturing carbon dioxide due to its low operating and capital costs. In this study, Pressure Swing Adsorption (PSA) process has been compared with Thermal Pressure Swing Adsorption (TPSA) process for CO, recovery from a flue gas composition of 10% CO2 (by vol) in N-2 using Ceca 13X adsorbent. A factorial design set of experiments was performed to optimise the carbon dioxide recovery and study the effects and interaction of four control parameters namely, purge/feed flow ratio, purge time, purge gas temperature and adsorption column pressure. Results indicated that better regeneration conditions used in a TPSA cycle was essential over a PSA cycle for regaining maximum adsorption capacity of the used Ceca 13X adsorbent. It was found that Purge time had a significant effect on the CO2) recovery followed by Column pressure, purge/feed flow ratio and purge temperature. A Minitab (R) statistical software was used to analyse the data. It was found that the test of significance for lack of fit showed the fitted model to be an adequate representation of the experimental data. The results showed that to maximise the CO2 recovery, highest values of the control parameters have to be used.