Desorption characteristics of H2O and CO2 from alumina F200 under different feed/purge pressure ratios and regeneration temperatures

Abstract

Air pre-purification is an important process for industrial air separation with cryogenic distillation method. This process is typically realized by pressure swing adsorption or temperature swing adsorption. H2O and CO2 are the two major components to be removed among the contaminants. In this paper, we establish a mathematical model describing the mass and heat balances in the adsorption bed, and the double-component adsorption/desorption equilibriums of H2O/CO2 on alumina F200. To conduct desorption performance analysis, a one-cycle process consisting of feed, blowdown, and purge step under different operating conditions, such as feed/purge pressure ratio and regeneration temperature, is numerically studied. The effect of heat on the desorption performance of H2O and CO2 is investigated by changing the purge gas temperature within 30 °C to 200 °C under feed/purge pressure ratios of 6:1.1 and 10:1.1, respectively. Detailed results of the H2O and CO2 adsorption/desorption behaviors in the bed are demonstrated. The mass and heat transfer characteristics during desorption are also analyzed. Suggestions on the optimization of the heating temperature and duration of purge gas are also proposed.

Heat and Mass Transport Characteristics of Pressure Swing Adsorption for the Removal of High-Level Moisture along with CO2 from Air

“…The edge moves backward by 30% of the bed height during purge as the flow rate of purge is just 30% of that during adsorption. Note that the movement speed of heat is different from that of gas flow in that it also depends on the relative volumetric heat capacity of gas flow to adsorbents because heat is mainly stored in solid phase . Thus, heat moves more slowly than gas flow.…”

“…Various means of determining the equilibrium adsorbed amount within the hysteresis loop have been developed. − For simplicity, in this study each branch of the desorption isotherm is obtained by scaling the loading due to capillary evaporation and expressed as where χ i is the local humidity when desorption begins. The detailed calculation of the equilibrium adsorbed amount under arbitrary state was demonstrated in our previous work …”

CO₂ Emission and Energy Assessments of a Novel Pre-Purification Unit for Cryogenic Air Separation Using Supersonic Separator

“…Furthermore, compression power demand abatement is a trend to new ASUs, particularly for oxy-combustion applications, where PSA alternative loses competitiveness as air feed pressure decreases. In this sense, the current scenario of large scale impure GOX production is a niche particularly dominated by FULL-TSA as it requires pressurized air at ≈3 bar [1,4], unlike conventional Cold Boxes, which require at least 5.5 bar [5].…”