Modular pressure-swing adsorption system

A pressure-swing adsorption (PSA) system, comprising:

• a) a plurality of substantially similar pairs of towers, each tower containing an adsorbent material to which a component of a feed gas becomes adsorbed under pressure,
• b) each tower having a top header and a bottom header, the top and bottom headers having extensions which define conduit segments,
• c) wherein the conduit segments are aligned so as to define a conduit which spans all of the pairs of towers, wherein feed gas can be directed through the conduit so as to be fed into a plurality of towers in parallel, and wherein product gas can be directed out of a plurality of towers,
• d) wherein each tower includes a tension rod, the tension rod being positioned inside the tower and being connected between the top and bottom headers, such that the tension rod pulls the headers towards each other so as to provide a tight seal for the tower,
• e) wherein a gasket seals a connection of each tower to the top and bottom headers, wherein each tower is sealed independently from other towers, and
• f) means for directing gases into, and out of, said pairs of towers, according to which tower in a pair is being pressurized and which tower is being depressurized, the directing means including at least one control block, located outside the towers, the control block defining passages for gas flow.