An NGL recovery facility utilizing a single, closed-loop mixed refrigerant cycle for recovering a substantial portion of the C.sub.2 and heavier or C.sub.3 and heavier NGL components from the incoming gas stream. Less severe operating conditions, including a warmer refrigerant temperature and a lower feed gas pressure, contribute to a more economical and efficient NGL recovery 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 system and method for treating associated gas in which a stream of raw gas is passed through safety valving, an inlet pressure control mechanism, and an inlet scrubber. Pressure/temperature data is transmitted to a control system via pressure and temperature transducers. The raw gas is sent to a gas compressor to generate pressurized gas, which is sent to an aerial cooler and a chiller heat exchanger, in which a chilling media contacts the pressurized gas. The chilled pressurized gas is sent to a vapor liquid separator to generate processed gas, which is routed through either a system backpressure valve or a pressure reducing recycle valve that directs the processed gas to the inlet scrubber. The processed gas that has passed through the system backpressure valve is delivered as fuel or routed through a backpressure regulating recycle valve that directs the processed gas to a system inlet pressure reducing valve.

Systems and methods for the enhanced recovery of ethane and heavier hydrocarbons using an absorbing agent. Typical absorbing agents include one or more C3+ alkanes. The systems and methods separate components of a feed gas containing methane and heavier hydrocarbons, which maximizes ethane recovery, without requiring appreciable increases in capital and operating costs, and improves the safety margin with respect to the risk of CO.sub.2 freeze-out.

The disclosure provides a process for recovery of C.sub.2 and C.sub.3 components in an on-purpose propylene production system utilizing a packed rectifier with a countercurrent stream to strip C.sub.2 and C.sub.3 components from a combined de-ethanizer overhead lights vapor and cracked gas vapor stream.

In a process for the separation of a gas rich in carbon dioxide and containing at least one component lighter than carbon dioxide, the feed gas rich in carbon dioxide is cooled in a first heat exchanger, partially condensed and separated to form a gaseous portion and a liquid, sending the liquid portion to the top of a distillation column, removing a liquid stream richer in carbon dioxide than the feed gas from the bottom of the distillation column, removing a gaseous stream less rich in carbon dioxide than the feed gas from the top of the distillation column and warming the gaseous stream in the first heat exchanger, sending the gaseous portion to a shell and tube heat exchanger having tubes in a bath of triple point carbon dioxide, in which it condenses at least partially to form a liquid fraction, sending the liquid fraction to the top of the distillation column, vaporizing a liquid stream from the bottom of the distillation column outside or within the distillation column to form a gas which is subsequently separated in the distillation column, expanding a liquid stream from the bottom of the distillation column, vaporizing at least part of the expanded liquid stream in the shell and tube heat exchanger to form a vapor and warming the vapor formed in the first heat exchanger.

A method is described for removing carbon dioxide during Liquid Natural Gas production from natural gas at gas pressure letdown stations. The above method removes carbon dioxide from a Liquid Natural Gas production stream by using hydrocarbon fractions taken from a gas for consumption stream as a carbon dioxide stripping adsorption agent for a stripping column used to remove carbon dioxide.

The present disclosure provides method for clean methane startup of a distillation tower. The method includes maintaining a rectifier section and a lower section in the distillation tower, feeding stream to the lower section, directly feeding methane to at least one of the rectifier section and a rectifier section outlet line of the rectifier section when a contaminant concentration of the contaminant exiting as a vapor in an upper portion of the lower section is outside of a predetermined concentration and introducing the vapor from the lower section to the rectifier section when the contaminant concentration exiting the upper portion of the lower section is within the predetermined concentration.

A method and system for separating fluids in a distillation tower. The method may include feeding a stream to the distillation tower, wherein the stream includes carbon dioxide, reducing a carbon dioxide concentration of the stream received by the rectifier section by feeding a first cryogenic fluid to the controlled freeze zone section and accumulating rectifier section stream in at least one of a holding vessel and a sump of the rectifier section, and terminating reducing the carbon dioxide concentration when the carbon dioxide concentration of the stream travelling from the controlled freeze zone section to the rectifier section is less than or equal to a maximum carbon dioxide concentration. The first cryogenic fluid may comprise a substantially carbon-dioxide-free fluid.

Helium can be recovered from nitrogen-rich natural gas at high pressure with low helium loss by cryogenic distillation of the natural gas after pre-treatment of the gas to remove incompatible impurities and then recovery of natural gas liquid (NGL) from the pre-treated gas by distillation. Overall power consumption may be reduced, particularly if the feed to the helium recovery column system is at least substantially condensed by indirect heat exchange against a first portion of nitrogen-enriched bottoms liquid at first pressure, and a second portion of nitrogen-enriched bottoms liquid at a second pressure that is different from the first pressure.