Patent ID: 6659730
Filing Date: 2003-12-09
Classification: F04B,Y10S

Abstract:
A method of operating a cryogenic system for pumping a cryogenic fluid and controlling mass flow rate, said system comprising a pump operable to pump cryogenic liquid or a mixture of cryogenic liquid and vapor, whereby when said system supplies said cryogenic vapor and/or liquid to said pump from a storage tank, said method comprising:(a) selecting a first operating mode in which said cryogenic liquid is supplied to said pump to substantially fill a compression chamber with liquid to achieve a high mass flow rate; and (b) selecting a second operating mode to achieve a mass flow rate lower than said first operating mode by selectively supplying said liquid and said vapor simultaneously to said pump wherein the vapor fraction is higher for said second operating mode compared to the vapor fraction for said first operating mode; and (c) condensing said vapor in an inducer before directing it to said compression chamber and when said compression chamber is filled with said liquid, holding excess amounts of said fluid within said inducer.