Patent ID: 6981850

Claim:
An apparatus for producing a pressurized vapor stream comprising: a cryopump to pump a cryogenic stream and thereby to produce a pressurized liquid stream; a hydraulic transmission to drive the cryopump; at least one hydraulic power generation system having a source of shaft power and first and second hydraulic pumps driven by the source of shaft power, the first of the hydraulic pumps being a variable displacement pump; a hydraulic flow circuit for circulating the hydraulic fluid, the hydraulic flow circuit having at least first and second hydraulic fluid flow paths for the hydraulic fluid, the first of the flow paths connecting the first of the hydraulic pumps to the hydraulic transmission so that adjustment of pumping output of the first of the hydraulic pumps controls the flow rate of the cryogenic liquid stream and the second of the hydraulic fluid flow paths connected to the second of the pumps and bypassing the hydraulic transmission so that none of the shaft power imparted to the hydraulic fluid by the second of the pumps is utilized in pumping the cryogenic stream; first and second adjustable back pressure valves connected to the first and second hydraulic flow paths, respectively, downstream of the first and second of the hydraulic pumps, to allow for independent adjustment of heat generation within hydraulic fluid flowing in the first and second flow paths; and at least a heat exchanger for indirectly exchanging heat from the hydraulic fluid to the pressurized liquid stream, thereby to vaporize at least part of the liquid stream and form the pressurized vapor stream.