A
pressure vessel provided with a first port acting as a
high pressure inlet of a first
stream and a second port acting as a
high pressure outlet. A rotatable valve element is located in the centre of the
machine and includes a centre plate, which is utilized to separate
high pressure streams. At each end of the valve element are valves. The valves ensure that as the valve element rotates the exchange ducts are either both isolated or that one is exposed to high pressure while the other is exposed to low pressure. In operation, a fluid
stream is introduced to the
machine at high pressure through port and flows around the outside of the exchange duct towards the centre of the
machine. The
stream then flows downwardly to the valve element, where it then passes through the open ports of the valve element and into flow
distributor. The stream then passes into and upwardly in the exchange duct, causing
upward displacement of the duct
piston, resulting in the pressurization and flow of the second fluid above the duct
piston. The second fluid then flows into the upper flow
distributor, into the valve element, and then downwardly and finally between the exchange duct and out through the high pressure port. At the same time a fluid stream is introduced to the machine at low pressure through port. This flows into the valve element and then into the flow
distributor. From the flow distributor it flows and downwardly into the pressure exchange duct, causing
downward displacement of duct
piston and resulting in flow of the first fluid below the duct piston, which then flows into the lower flow distributor, into the valve element, and then out of the lower sealing plate at port. A planar radial sealing surface promotes sealing connection between the rotatable valve element and various pressure exchange ducts within the
pressure vessel.