Abstract: The present invention is directed to methods for improving the efficiency of processes for the recovery of natural gas liquids from a gas feed, e.g., raw natural gas or a refinery or petrochemical plant gas stream. These methods may be employed with most, if not all, conventional separation methods using distillation towers, e.g., a demethanizer and/or deethanizer column. The methods of the present invention involve installing an internal refrigeration system consisting of an open cycle refrigerant withdrawn from a distillation column and a closed cycle refrigerant derived from the open cycle refrigeration system. A separator is installed downstream of the recycle compressor discharge cooler in the open cycle refrigeration scheme. At least a portion of liquid withdrawn from this separator is used as a closed cycle refrigerant by indirect heat exchange with the inlet gas or other process streams. Thus a closed refrigeration cycle enhances the performance of the open refrigeration cycle.

Abstract: A process for enhancing the recovery of less volatile components, from a multi component gas mixture, in a cryogenic distillation column, which involves withdrawing a stream from the cryogenic distillation column and processing it to yield a stream leaner in the component to be recovered, which will be cooled and fed to the cryogenic distillation column as a reflux. The processing step may include heating or cooling the side draw and then further contacting the side draw with another stream which is substantially condensed.

Abstract: A process for enhancing the recovery of less volatile components, from a multi component gas mixture, in a cryogenic distillation column, which involves withdrawing a stream from the cryogenic distillation column and processing it to yield a stream leaner in the component to be recovered, which will be cooled and fed to the cryogenic distillation column as a reflux. The processing step may include heating or cooling the side draw and then further contacting the side draw with another stream which is substantially condensed.