Adsorptive process for the removal of carbon dioxide from a gas

Claim 1

In a process for removing carbon dioxide from a gas stream in an adsorbent bed by temperature swing adsorption comprising flowing a water-depleted gas feed stream containing carbon dioxide through said bed to selectively adsorb carbon dioxide, the improvement comprising the steps of: (a) passing the carbon dioxide-depleted gas product of the adsorbent bed through a recuperator to retain heat from said adsorbent bed; (b) bypassing the flow of carbon dioxide-depleted gas product around said recuperator after the gas reaches a predetermined lower temperature level, but while continuing the adsorption; (c) discontinuing the flow of water-depleted feed gas through said bed when the gas product of said bed reaches a predetermined level of carbon dioxide; (d) reducing the pressure of the bed and initiating the purging of the bed countercurrently with a heated water and carbon dioxide-depleted purge gas, which is heated to an elevated temperature by externally supplied heat and heat recovered from said recuperator until a thermal zone exists in said bed; (e) continuing the purge of the adsorbent bed without externally supplied heat until the thermal zone in said bed is approximately at the feed end of the bed; (f) discontinuing the flow of purge gas, and (g) repressurizing the bed countercurrently with water and carbon dioxide-depleted gas until the bed reaches a preset pressure level such that the adsorption cycle can be initiated again.