Abstract: A process is shown for separating a relatively hot feed gas containing methane, ethane and heavier hydrocarbon constituents into a volatile residue gas and a primarily liquid bottoms. The feed gas is cooled to partially condense the feed gas to form a liquid portion which is expanded and fed to a fractionating column. The expanded liquid portion flows down the column in countercurrent fashion to vapors flowing up the column to separate the relatively less volatile fraction as column bottoms. A side reboiler heats and vaporizes a portion of the liquids flowing down the fractionating column to provide stripping vapors which flow up the column. A portion of the relatively hot, methane rich feed gas entering the process is routed to the column at a selected location in order to raise the relative volatility of liquids near the bottom of the column, resulting in ethane rejection.

Abstract: A process for separating the components of a feed gas containing methane and heavier hydrocarbons is shown in which a recycle stream is used to satisfy the heat requirements of the process while at the same time providing a reflux to a demethanizer column to improve product recovery. The inlet gas stream is fed to a separator without first splitting the stream. A first vapor portion and a first liquid portion are produced by the separator with the first vapor portion being supplied, after expansion, to the demethanizer column at an intermediate feed position. The first liquid portion from the separator is expanded and supplied to the demethanizer column at a relatively lower feed position. Overhead vapor is removed from the column and compressed to a higher pressure. The resulting compressed recycle stream is cooled sufficiently to substantially condense it and is supplied as reflux to the demethanizer column at a top feed position.

Abstract: A process is shown for producing liquefied natural gas from a pressurized natural feed stream. The feed stream is introduced into heat exchange contact with a mechanical refrigeration cycle to cool the feed stream to a first cooling temperature. At least a portion of the feed stream is passed through a turboexpander cycle to provide auxiliary refrigeration for the mechanical refrigeration cycle to thereby cool the feed stream to a second, relatively lower cooling temperature.

Abstract: A cryogenic process for recovering propane and heavier hydrocarbons from natural gas streams or similar refinery or process streams containing lighter hydrocarbons such as methane and ethane. In the process disclosed, the gas to be separated is cooled which may include some condensation, in which case the condensate is separated from the vapor and fed to a lower region of all the fractionating column. The cooled vapor from the separator is split into two streams. One portion of the split vapor stream is work expanded to a midpoint of the fractionating column, while another portion of the split vapor stream is further cooled causing partial condensation, the condensate being separated and fed to the fractionation column above the feed from the first work expander, and the vapor being work expanded through a second expander and fed to the top of the fractionator as reflux.

Abstract: Carbon dioxide is separated from light hydrocarbons such as methane and ethane by absorbing CO.sub.2 gas with water at a pressure of at least 500 psia thus avoiding the CO.sub.2 --C.sub.2 H.sub.6 azeotrope problem. The CO.sub.2 is recovered from the absorbing water by pressure reduction and flashing and/or by heating and flashing. The process is particularly applicable to the recovery of high pressure pure carbon dioxide from the wellhead products of carbon dioxide flooding used in enhanced oil recovery. The high pressure pure carbon dioxide is liquified and reinjected to the well at the desired pressure.

Abstract: Carbon dioxide is cryogenically separated from methane and then is separated from the ethane by liquid extraction with water at high pressures of 500 to 2250 psia thus avoiding the CO.sub.2 --C.sub.2 H.sub.6 azeotrope problem. The process is particularly applicable to the recovery of high pressure pure carbon dioxide from the wellhead products of carbon dioxide flooding used in enhanced oil recovery. The high pressure pure carbon dioxide liquid is pumped for reinjection to the well.

Abstract: A cryogenic process for separating methane from ethane and heavier hydrocarbons in which a high pressure gas feed is divided into two gas streams. The gas is cooled either before or after it is divided and this step may include some condensation in which case the condensate is separated from the gas. One of the divided gas streams is expanded through a work expansion machine down to the pressure of the fractionation column. Any separated condensate is also expanded to the column pressure. The second divided gas stream is further cooled by heat exchange and then expanded down to an intermediate pressure whereby a portion is condensed. This condensate is separated from the remaining gas and then expanded to the column pressure. The remaining gas is further cooled and expanded and fed to the column as the top feed.

Abstract: A process for low temperature fractionation of natural gas to recover as product propane and the heavier hydrocarbons with an efficiency of 90% or greater and an ethane content rejection of 90% or more. The process includes passage of the natural gas through several refrigeration zones followed by a first separation stage to separate liquid condensate from C.sub.1, C.sub.2 and C.sub.3 hydrocarbon gas. The gas stream is cooled further by expansion followed by a second separation stage to separate liquid containing C.sub.1, C.sub.2 and C.sub.3 hydrocarbons from the gas which contains only C.sub.1 and C.sub.2 hydrocarbons. Both streams are fed to a de-ethanizer fractionating column, with the liquid entering at a point intermediate the ends and the gas being utilized in a reflux condenser internal to the column above the point of entry of the liquid stream. Employment of the low temperature C.sub.1, C.sub.