| 摘要 |
A conventional air separator unit separates nitrogen, oxygen or argon merchant gas to be liquefied. Input pressurized natural gas is processed through a pressure letdown liquefaction system including gas separators for removing moisture and for drying the gas. The dried gas is then separated into large and small gas stream portions wherein CO2 in the smaller portion is removed. The two portions are passed through a first heat exchanger from which the larger portion is expanded which cools it and then passed through two heat exchangers including the first exchanger, used to regenerate the CO2 separator and drier and then returned to the input stream. The smaller portion is passed through the two heat exchangers to a throttle valve where the gas is liquefied and processed to a second set of heat exchangers which receive compressed separated merchant gas to be cooled by the liquefied natural gas and liquefied via an additional heat exchanger which receives cooled vapor separated from the liquefied merchant gas, the vapor being formed by a flash valve. The vapor is repetitively recycled through a compressor and passed through the second set of heat exchangers. Different embodiments are disclosed including a compander for expanding the merchant gas which is passed through the first and second set of heat exchangers and including an embodiment for supplying cold merchant gas rather than liquid merchant gas to an air separation unit for producing liquefied merchant gases. |
