Patent ID: 7201557

Claim:
A pressure exchange apparatus for transferring pressure energy from a high pressure first fluid to a lower pressure second fluid to provide a pressurized second fluid, which apparatus comprises: a rotatably mounted cylindrical rotor having a pair of opposite planar end faces with at least two channels extending axially therethrough and between openings located in said planar end faces; a pair of end covers having inward and outward end faces, with said inward end faces interfacing with and slidingly and sealingly engaging said end faces of said rotor, each said end cover having one inlet passageway and one discharge passageway, said passageways being located so that an inlet passageway in one said end cover is aligned with one said channel in said rotor when a discharge passageway in the other said end cover is aligned with the same channel, said inlet passageway and said discharge passageway in each said end cover plate being constantly sealed from each other during the operation by a sealing region at the interface between said rotor end face and said end cover, whereby said channel openings during rotation of said rotor are, in alternating sequence, brought into partial or full alignment with an inlet passageway in one said end cover and a discharge passageway in the other said end cover and then into partial or full alignment with a discharge passageway in said one end cover and an inlet passageway in said other end cover; at least one pressure-balancing chamber which is in fluid communication with an inward-facing surface of at least one said end cover; and means connecting said chamber to either the high pressure first fluid or to the pressurized second fluid so that last-named end cover is subjected to relatively equal forces upon said inward and outward end faces thereof.