Patent ID: 9656202
Date: 2017-05-23
CPC Classifications: B01D,Y02C

Claim:
1. Method for separating a gas mixture according to a pressure swing adsorption process (PSA process), comprising the steps of: separating the gas mixture by adsorbing at least one gas component in an adsorbent mass provided in each vessel of a plurality of vessels, wherein each vessel has at least one inlet and one outlet; and storing off-gas from said process into an off-gas vessel, wherein in each of said plurality of vessels the following steps are conducted, (i) admitting the gas mixture for a specified period into a first vessel via an inlet of said vessel, and releasing a separated product gas via an outlet of said vessel, to be followed by admitting the gas mixture into a second vessel while continuing the release of product gas from the first vessel, to be followed by (ii) releasing purge gas from the first vessel via its outlet, (iii) releasing off-gas from the first vessel via its inlet and admitting at least part of the off-gas into the off-gas vessel, (iv) admitting purge gas into the first vessel via its outlet, and releasing off-gas from said vessel via its inlet, (v) admitting a separated product gas into the first vessel until the pressure in the first vessel has reached a predetermined value, after which admitting of the gas mixture into the first vessel begins, and the steps are to be repeated beginning with the step (i), wherein during at least one of the steps (iii) and (iv) at least part of the off-gas from the first vessel is released directly to an off-gas consuming device, characterized by (a) connecting, in a first state in which pi>po+Δ and pi>pb, each of the plurality of vessels directly to both the off-gas consuming device and the off-gas storage vessel, (b) connecting, in a second state in which pb<pi<po+Δ, each of the plurality of vessels directly to only the off-gas consuming device, and (c) connecting, in a third state in which pi<pb and po>pb, the off-gas storage vessel to the off-gas consuming device, wherein pi represents the value of the pressure at the inlet of the respective one of the plurality of vessels, po represents the value of the pressure in the storage vessel, pb represents a pressure having a predetermined value, and Δ represents a predetermined pressure difference.