| 摘要 |
The present invention comprises a method and apparatus for maintaining a liquified gas such as CO2 or N2 in a liquid state prior to its introduction into the suction of a positive displacement pump such as is commonly employed in high pressure well stimulation work in the petroleum industry. A heat exchanger, preferably referred to as a passive booster, is placed in the liquified gas feed line between the gas source and the positive displacement pump. Gas is introduced into the shell side of the passive booster from a chamber in the tube side through a variable orifice throttling valve which, through the Joule-Thomson Effect, drops the temperature of the gas in the shell to provide refrigeration for the main liquified gas flow through the tube side of the passive booster. Flow through the variable orifice valve may be controlled manually or automatically. A back pressure valve on the shell side of the passive booster may be employed to prevent solid formation if one is employing liquified CO2, which forms a solid phase at low temperature at normal atmospheric pressure. |
