One or more specific embodiments disclosed herein includes a method for separating hydrogen from an olefin hydrocarbon rich compressed effluent vapor stream, employing an integrated heat exchanger, multiple gas-liquid separators, external refrigeration systems, and a rectifier attached to a liquid product drum.

A C3 hydrocarbon fractionation system includes: a) a unit for providing a feed containing mainly propane and propylene, b) a C3 fractionation column for separating the feed to provide a top product richer in propylene than the feed and a bottom product leaner in propylene than the feed, wherein the bottom product comprises at least 50 wt % of propylene and c) a cumene production unit comprising an alkylation reactor for producing cumene from a propylene feed and a benzene feed, wherein the propylene feed comprises the bottom product of the C3 fractionation column.

One or more specific embodiments disclosed herein includes a method for separating hydrogen from an olefin hydrocarbon rich compressed effluent vapor stream, employing an integrated heat exchanger, multiple gas-liquid separators, external refrigeration systems, and a rectifier attached to a liquid product drum.

Techniques and systems for separating components of a mixture of compressed gases each having different boiling points are described. One example system includes multiple recovery stages that each recover one of the gases by condensing it into liquid form. The recovery stages are chained together, such that each stage recovers a gas having a boiling point that is higher than those of the gases to be recovered in downstream stages. Each stage typically includes a warming element that is fluidly coupled to a condenser element that provides a surface cooled to a temperature low enough to condense one of the gases, but high enough such that the remaining gases remain in gaseous form. The system may include an initial evaporator stage that heats a liquid solution of phytochemical extracts and multiple solvents, thereby recovering the extracts and producing the mixture of gaseous solvents.

One or more specific embodiments disclosed herein includes a method for separating hydrogen from an olefin hydrocarbon rich compressed effluent vapor stream, employing a integrated heat exchanger, multiple gas-liquid separators, external refrigeration systems, and a rectifier attached to a liquid product drum.

One or more specific embodiments disclosed herein includes a method for separating hydrogen from an olefin hydrocarbon rich compressed effluent vapor stream, employing an integrated heat exchanger, multiple gas-liquid separators, external refrigeration systems, and a rectifier attached to a liquid product drum.

An energy efficient process for NGL recovery and production of compressed natural gas (CNG) in which natural gas is fed to a first gas separation membrane-based separation stage where it is separated into a permeate and a retentate. The high C.sub.3+ concentration first stage permeate is chilled and separated to provide liquid phase NGL and a gaseous phase. The first stage retentate is separated at a second gas membrane-based separation stage to produce a retentate meeting pipeline specifications for CNG (including hydrocarbon dewpoint) and a permeate that is recycled to the first stage. The gaseous phase, constituting a low BTU fuel, may be used in on-site power generation equipment and/or in internal combustion engines. The second stage permeate (and optionally the third stage retentate) is (are) recycled back to the first stage to enhance the production of NGL and CNG. The gaseous phase may instead be fed to a third stage to produce a third permeate and a third residue, in which case the third permeate is recycled to the first stage and the third retentate is a low BTU fuel which may be used in on-site power generation equipment and/or in internal combustion engines.

One or more specific embodiments disclosed herein includes a method for separating hydrogen from an olefin hydrocarbon rich compressed effluent vapor stream, employing a single heat exchanger, multiple gas-liquid separators, multiple expander/compressor sets, and a rectifier attached to a liquid product drum.

A process for recovering hydrogen from dehydrogenation reactor effluent is disclosed. A feed stream comprising hydrocarbons and hydrogen to a dehydrogenation reactor maintained at dehydrogenation conditions to provide a dehydrogenation reactor effluent. The dehydrogenation reactor effluent is passed to a cold box separation unit to provide a liquid hydrocarbon product stream and a recycle hydrogen stream. A return portion of the recycle hydrogen stream is passed to the reactor effluent compressor. The subject matter disclosed improved process and apparatus which enables the paraffin dehydrogenation reactor to run at reduced H.sub.2/HC ratio without requiring an investment in a resized compressor or resized turboexpanders or separators in the cold box.

A system for recovering valuables from vent gas in polyolefin production is disclosed. The system includes a compression device, a drying device, a condensation and separation device, and a membrane separation device that are connected to each other in sequence. The drying device includes a first adsorption bed and a second adsorption bed which are in parallel connection with each other and in which a desiccant is provided, and a third adsorption bed which is in communication with the first adsorption bed and the second adsorption bed respectively and in which a desiccant is provided. The first adsorption bed and the second adsorption bed are in an adsorption process and a regeneration process alternately, and the third adsorption bed is in an auxiliary regeneration process. A process for recovering valuables from vent gas in polyolefin production is further disclosed. When the system and the process are used, one part of the normal temperature compressed gas stream output by the compression device directly serves as a regeneration gas for regeneration of saturated desiccant in adsorption bed, and it is unnecessary for external supply of regeneration gas, whereby the actual recovery of nitrogen can be effectively improved. Membrane separation technology is combined, and hydrocarbon recovery can be effectively improved as well.