Patent ID: 7438746
Filing Date: 2008-10-21
Classification: B01D,Y02C

Abstract:
1. An off-gas feeding method for supplying off-gas discharged from a plurality of adsorption towers to an off-gas consumption unit, while performing a pressure swing adsorption process of repeating a cycle including a plurality of steps, to enrich and separate target gas out of a gas mixture in the adsorption towers loaded with an adsorbent, comprising: causing at least one of the adsorption towers to discharge the off-gas, in all the steps included in the cycle, so as to continue to supply the off-gas to the off-gas consumption unit without interruption; wherein each of the adsorption towers repeats the cycle which includes: an adsorption step of adsorbing an unnecessary gas component in the gas mixture with the adsorbent so as to discharge a product gas containing a higher concentration of the target gas, a first depressurizing step of reducing the pressure in the adsorption tower to a first intermediate pressure, a second depressurizing step of reducing the pressure in the adsorption tower to a second intermediate pressure, a desorption step of desorbing and discharging the unnecessary gas component from the adsorbent, a scavenging step of introducing scavenging gas into the adsorption tower so as to discharge residual gas in the tower, and a pressurizing step of increasing the pressure in the adsorption tower; and wherein the residual gas discharged through a product gas outlet of the adsorption tower performing the second depressurizing step is introduced to another adsorption tower performing the pressurizing step, and the off-gas is supplied to the off-gas consumption unit through a gas mixture inlet of the adsorption tower performing the second depressurizing step.