Pressure swing adsorption system with indexed rotatable multi-port valves

A pressure swing adsorption system comprising

• (a) first, second, third, and fourth vessels, each vessel having a feed end, a product end, and adsorbent material adapted to adsorb a selected component from a feed gas mixture;
• (b) piping adapted to introduce the feed gas mixture into the feed ends of the vessels, piping adapted to withdraw a product gas from the product ends of the vessels, piping adapted to place the product ends of any pair of vessels in flow communication, and piping adapted to withdraw a waste gas from the feed ends of the vessels;
• (c) a feed pipe adapted to supply the feed gas mixture to the system, a product pipe adapted to withdraw the product gas from the system, and a waste gas pipe adapted to withdraw the waste gas from the system;
• and
• (d) an indexed rotatable multi-port product valve having eight indexed positions wherein
• (1) in a first indexed position the valve is adapted to place the product ends of the second and fourth vessels in flow communication;
• (2) in a second indexed position the valve is adapted to place the product ends of the third and fourth vessels in flow communication and to place the product ends of the first and second vessels in flow communication;
• (3) in a third indexed position the valve is adapted to place the product ends of the first and third vessels in flow communication;
• (4) in a fourth indexed position the valve is adapted to place the product ends of the first and fourth vessels in flow communication and to place the product ends of the second and third vessels in flow communication;
• (5) in a fifth indexed position the valve is adapted to place the product ends of the second and fourth vessels in flow communication;
• (6) in a sixth indexed position the valve is adapted to place the product ends of the first and second vessels in flow communication and to place the product ends of the third and fourth vessels in flow communication;
• (7) in a seventh indexed position the valve is adapted to place the product ends of the first and third vessels in flow communication;
• and
• (8) in an eighth indexed position the valve is adapted to place the product ends of the first and fourth vessels in flow communication and to place the product ends of the second and third vessels in flow communication.