IMPROVED PROPANE RECOVERY METHODS

摘要

The present invention is directed to methods for separating and recovering propane, propylene and heavier hydrocarbons, i.e., the C3+ hydrocarbons, from a gas feed (10), e.g., raw natural gas or a refinery or petroleum plant gas stream. These methods employ sequentially configured first (20) and second (73) distillation columns, e.g., a de-methanizer tower (20) followed by a de-ethanizer tower (73). A cooled gas feed condensate is separated in the first column into methane and a liquid phase comprising ethane and heavier hydrocarbons. The liquid phase is separated in the second column (73) into a gas phase (77) primarily comprising ethane and a second liquid phase primarily comprising the desired C3+ hydrocarbons. At least a portion of the second gas phase (45) is introduced into the first distillation column as an overhead reflux to improve the separation of C3+ hydrocarbons. The methods of the present invention permit separation and recovery of more than about 99 % of the C3+ hydrocarbons in the gas feed at higher operating pressures.