Abstract: The present invention is a separation unit process in which a high pressure section of a separation unit operates at a relatively high pressure to initially process and separate a high pressure feed stream and a low pressure section of the separation unit to initially process and separate a low pressure feed stream, where the high pressure section and the low pressure section are integral with and exchange streams to accomplish a desired separation of a wellhead fluid feed which typically includes a heavier portion of pentanes and heavier components

Abstract: The present invention relates to methods for separating and recovering ethane, propane and heavier components from a feed gas, e.g. raw natural gas or a refinery or petroleum plant gas stream or a petrochemical plant gas stream. These methods employ a common new concept which is the use of the turbo-expander shaft compressor to generate the reflux requirement for the cryogenic absorber or distillation columns. The power of the turbo-expander which is absorbed by the shaft compressor is always high enough so that reflux generation by a specific gas compression through the expander shaft compressor and subsequent cooling, condensation and sub-cooling can always be easily maintained. The present invention allows for higher cryogenic absorber pressure and a lower demethanizer/de-ethanizer column pressure thus eliminating the common cryogenic pump at absorber bottom. The present invention ultimately results in a lower residue compression and utilities consumption.