Patent ID: 6220052
Filing Date: 2001-04-24
Classification: F25J

Abstract:
Apparatus for liquefying natural gas supplied from a source of natural gas comprising a compressor for compressing the natural gas, chiller means for reducing the temperature of the compressed gas, a heat exchanger for further cooling the cooled compressed gas, a dewar having compressed natural gas therein at a pressure, a Joule-Thompson valve carried by the dewar and having an inlet and an orifice in communication with the inlet and an adjustable needle movable into and out of the orifice for changing the size of the orifice, inlet piping connecting the heat exchanger to the inlet of the Joule-Thompson valve for supplying cooled compressed gas at a pressure to the inlet of the Joule-Thompson valve, said dewar having a pressure substantially less than the pressure in the inlet whereby when the cooled compressed gas from the inlet piping passes through the Joule-Thompson valve there is an expansion of the gas to cause liquefaction of a substantial portion of the gas as it passes into the dewar and means coupled to the needle for precisely adjusting the position of the needle with respect to the orifice to thereby precisely adjust the size of the orifice to maintain a substantially constant pressure of the cooled compressed gas in the inlet to thereby provide a continuous controlled expansion of the cooled compressed natural gas from a high pressure to the lower pressure in the dewar through the Joule-Thompson valve and independent of the temperature of the gas in the inlet.