Abstract: A cryogenic separation process for rejecting carbon dioxide from a carbon-dioxide-containing natural gas mixture. The invention is specifically designed for treating a natural gas mixture recovered from a petroleum well employing the enhanced recovery technique of carbon dioxide flooding. The carbon-dioxide-containing natural gas mixture is treated using a particular arrangement of fractional condensation, partial vaporization and rectification unit operations to produce an enriched-methane gas stream and carbon dioxide product streams at various pressures. The invention is well suited for the bulk separation of large quantities of carbon dioxide from carbon-dioxide-containing natural gas mixtures, as a preparatory step for the subsequent purification of the enriched-methane product by conventional absorption techniques.

Abstract: A process to separate by rectification low concentration nitrogen from natural gases having a gradually increasing nitrogen concentration which employs a nitrogen heat pump cycle to generate necessary liquid reflux for a fractionation column and is compatible with both single column and double column process arrangements.

Abstract: A process which effectively removes nitrogen from natural gas over a wide range of nitrogen concentrations and wherein the natural gas may also contain high concentrations of heavy hydrocarbons. The process is especially advantageous for the purification of a natural gas stream recovered from a petroleum field where nitrogen injection is employed as an enhanced recovery technique.

Abstract: An improvement in a wash system for gas separation wherein a wash liquid is contacted countercurrently with a feed gas mixture containing a high volatility component and a low volatility component in a plate and fin type exchanger where the heat of absorption is removed by a refrigerant passed in indirect heat exchange relationship with the countercurrently flowing feed gas mixture and wash liquid and then passing the resulting product stream to a wash column to further purify the product stream.