Patent ID: 7819948

Claim:
A rotary valve for performing cyclic process operations, comprising: a feed stator comprising a feed stator mating surface, a feed stator rear surface, and a plurality of ports connecting between the feed stator mating surface and the feed stator rear surface; a feed rotor adjacent to the feed stator comprising a feed rotor mating surface, a feed rotor rear surface, and a plurality of ports disposed upon the feed rotor mating surface to direct fluid flow between the plurality of stator ports of the feed stator, the feed rotor rotatable about an axis perpendicular to the feed rotor surface; a product rotor engaged with the feed rotor and comprising a product rotor mating surface, a product rotor rear surface, a product outlet, and a plurality of ports disposed upon the mating surface to direct fluid flow between the plurality of ports of the product stator, the product rotor rotatable about an axis perpendicular to the product rotor face; a product stator adjacent to the product rotor comprising a product stator mating face, a product stator rear face, and a plurality of ports connecting between the product stator mating face and the product stator rear face; and at least one compression spring disposed between the feed rotor and the product rotor configured to apply a spring force with a center of force on the feed rotor rear face and the product rotor rear face, wherein the spring force center of force is located at a predetermined distance greater than zero from the axis of rotation such that the spring force is configured to reduce torque required to turn the feed rotor and the product rotor when the valve is operational.