Systems and methods for debottlenecking propane feed, including a propylene separation system and C3 distillation column are provided herein. In some embodiments, the method includes providing a dry feed stream including propane and propylene to a propylene separation system including a membrane configured to separate the C3 feed stream into a retentate stream and a permeate stream, and providing at least a portion of the permeate stream and at least a portion of the propylene discharge stream to a propylene refrigeration system.

The present invention relates to a method of cooling and separating a hydrocarbon stream: (a) passing an hydrocarbon feed stream (7) through a first cooling and separation stage to provide a methane enriched vapour overhead stream (110) and a methane depleted liquid stream (10); (b) passing the methane depleted liquid stream (10) to a fractionation column (200) to obtain a bottom condensate stream (210), a top stream enriched in C1-C2 (220) and a midstream enriched in C3-C4 (230), (c) cooling the upper part of the fractionation column (201) by a condenser (206), (d) obtaining a split stream (112) from the methane enriched vapour overhead stream (110) and obtaining a cooled split stream (112) by expansion-cooling the split stream (112), (e) providing cooling duty to the top of the fractionation column (201) using the cooled split stream (112).

Processes and systems for recovery of a dilute ethylene stream are illustrated and described. More specifically, embodiments disclosed herein relate to processes and systems for separation of a dilute ethylene stream from an offgas or other vapor streams, where the ultra-low temperature refrigeration for the desired separations is provided by the offgas itself, and only moderately-low temperature externally supplied propylene refrigerants (for example, at 40 C. to 15 C.) are necessary.

Flowing a first buffer fluid and a second buffer fluid through a heat exchanger network thermally coupled to heat sources of a Natural Gas Liquid (NGL) fractionation plant, and transferring heat from the heat sources to the first buffer fluid and the second buffer fluid. Generating power via a first sub-system thermally coupled to the heat exchanger network and generating potable water from brackish water via a second sub-system thermally coupled to the heat exchanger network.

A system and method for removing nitrogen and producing a high pressure methane product stream and an NGL product stream from natural gas feed streams where at least 90%, and preferably at least 95%, of the ethane in the feed stream is recovered in the NGL product stream. The system and method of the invention are particularly suitable for use with feed streams in excess of 5 MMSCFD and up to 300 MMSCFD and containing around 5% to 80% nitrogen. The system and method preferably combine use of strategic heat exchange between various process streams with a high pressure rectifier tower and the ability to divert all or a portion of a nitrogen rejection unit feed stream to optionally bypass a nitrogen fractionation column to reduce capital costs and operating expenses.

A system and method for processing an NGL product stream from a natural gas feed stream in either an ethane retention or ethane rejection mode utilizing heat exchange of particular process streams. In ethane rejection mode, there are preferably two stages of heat exchange between the feed stream and a first separator bottoms stream and a side stream withdrawn from a fractionation tower is cooled through heat exchange with both the fractionation tower and second separator overhead streams, and optionally with an external refrigerant, resulting in 5-15% ethane and at least 97% propane recovery. In ethane retention mode, a portion of the feed stream and portions of a first separator overhead and bottoms streams are preferably separately cooled through heat exchange with other process streams, including the entireties of a recycled residue gas and fractionation column overhead streams, resulting in around 99% ethane and around 100% propane recovery.

A system and method for producing an NGL product stream in either an ethane retention or rejection mode. Rejection modes include (a) two heat exchange stages between a feed stream and first separator bottoms stream and cooling a side stream withdrawn from a fractionation tower through heat exchange with both the fractionation tower and second separator overhead streams; or (b) warming the first separator bottoms stream and fractionation overhead stream through heat exchange with the side stream prior to heat exchange with the feed stream, to achieve 4-15% ethane recovery and 97%+ propane recovery. In ethane retention mode, a portion of the feed stream and portions of a first separator overhead and bottoms streams are separately cooled through heat exchange with other process streams, including the entireties of a recycled residue gas and fractionation column overhead streams, resulting in around 99% ethane and around 100% propane recovery.

A method of recovering heat from a Natural Gas Liquid (NGL) fractionation plant for production of potable water. The method includes heating a buffer fluid via a heat exchanger in the NGL fractionation plant to transfer heat from the NGL fractionation plant to the buffer fluid. The method includes heating feed water with the buffer fluid discharged from the heat exchanger for production of potable water via a multi-effect-distillation (MED) system. The method may include producing potable water with heat from the buffer fluid in the MED system.

Disclosed herein are processes for producing and separating ethane and ethylene. In some embodiments, an oxidative coupling of methane (OCM) product gas comprising ethane and ethylene is introduced to a separation unit comprising two separators. Within the separation unit, the OCM product gas is separated to provide a C.sub.2-rich effluent, a methane-rich effluent, and a nitrogen-rich effluent. Advantageously, in some embodiments the separation is achieved with little or no external refrigeration requirement.

A method of recovering heat from a Natural Gas Liquid (NGL) fractionation plant for production of potable water. The method includes heating a buffer fluid via a heat exchanger in to transfer heat from the NGL fractionation plant to the buffer fluid. The method includes heating water with the buffer fluid discharged from the heat exchanger to produce potable water via train distillation effects.