The pilot dual-reflux vacuum pressure swing adsorption unit for CO2 capture from flue gas

The results of carbon dioxide separation from real flue gas using the dual-reflux vacuum pressure swing adsorption (DR-VPSA) technology have been presented. The mobile pilot CO2 separation plant consists of two containers: a processing container and a control container. The processing container includes a flue gas treatment section (which comprises dust removal, cooling, deSOx, deNOx, gas drying and compression units), as well as a CO2 adsorptive separation unit. The adsorption unit is made up of four fixed-bed columns, each divided into two sections, operating in a dual-reflux vacuum pressure swing adsorption mode. Two kinds of activated carbon in the total amount of 540 kg were used as the beds filling. The results from the 8-step reference process with no partition of the adsorbers into the upper and lower sections (as one-step separation process with partial product recirculation), and from the 9-step DR-VPSA process (as two-step separation process) with a division of the adsorbers are presented. In the measurement campaign three different feed gas flow rates and five different times of adsorption step were selected to assess their influence on separation results. The results show the optimal parameters of 100 Nm3/h for feed gas flow rate and 300 sec for adsorption step time for both mentioned processes. The 87.5% of purity, 44.6% of recovery, 11.4 kg/(m3 h) of productivity and 978 kWh/MgCO2 of energy demand for gas compression and vacuum evacuation in the case of optimal parameters of 9-step DR-VPSA technology were obtained. Additionally the results from measurement campaign were compared with those reported by other researchers.