Influence of feed gas condition and regeneration temperature on the separation performance of thermal swing continuous Co2 adsorber using a honeycomb adsorbent rotor

A thermal swing continuous rotary regenerative CO2 adsorber employing a honeycomb rotor was experimentally studied. Based on a previous report, a honeycomb rotor binding 13X type zeolite, which has relatively high adsorption capacities for CO2, was prepared and mounted on a CO2 separation and recovery concentrator. Its performance was evaluated by measuring CO2 recovery concentration and recovery ratio. First, the existence of an optimal rotation speed for performance was confirmed. Next, a CO2 removal and recovery test was performed by changing feed gas conditions of humidity (dew point), temperature, and CO2 concentration, or by changing the main operation variable, regeneration temperature. As expected, performance improved as the dew point or temperature of feed gas was lower, and as regeneration temperature was higher. To attain a target performance of CO2 recovery ratio of 50% and CO2 concentration of 80% of recovered gas, it was found that feed gas required a dew point of ≤−20°C DP and temperature of ≤25°C at a regeneration temperature of 180°C. At a regeneration temperature was 160°C and a dew point of feed gas of ≤−60°C DP, a feed gas temperature around 35°C was acceptable for the above mentioned target performance. As the CO2 concentration of feed gas was increased, the CO2 recovery concentration increased, but recovery ratio decreased due to a relatively small increase of adsorption capacity. It was also found that the recovery gas flow rate should be set to an appropriate value by considering the relationship between recovery gas concentration, recovery ratio and feed gas concentration. Finally, on condition that regeneration temperature was 160°C or higher and the dew point of feed gas was ≤−20°C DP, the temperature of feed gas was found to largely affect the CO2 adsorption characteristics of a rotor. Therefore, lowering the temperature of feed gas should be given priority in order to reduce the energy requirement for regeneration and pre-dehumidification. © 2017 The Society of Chemical Engineers, Japan.