Methods and systems are provided herein utilizing a membrane cascade to separate a hydrocarbon feed into boiling point fractions. Also provided herein are methods for selecting membranes for said cascades to achieve the desired boiling point fraction separation.

A process and system for recovering natural gas liquids (NGL) using a combination of J-T cooling and membrane separation. The process involves compressing, separating, and cooling a flare gas stream comprising at least methane and C.sub.3+ hydrocarbons prior to being introduced to a J-T valve. The cooled stream exiting the J-T valve is further separated, producing a NGL product stream and an uncondensed gas stream. The uncondensed gas stream is directed to a membrane separation step, which results in a C.sub.3+ hydrocarbon enriched stream and a C.sub.3+ hydrocarbon depleted stream. The C.sub.3+ hydrocarbon enriched stream may be recycled back to the process to recover more NGL.

An acid gas purification system is described herein that includes a primary membrane system with a CO.sub.2- and H.sub.2S-enriched permeate stream effluent and a hydrocarbon stream effluent; a first compression stage arranged to receive the CO.sub.2- and H.sub.2S-enriched permeate stream and produce a compressed stream; and a cryogenic separation system to receive the compressed stream, the cryogenic separation system including a cooler followed by a fractionator, wherein the fractionator produces a CO.sub.2- and H.sub.2S liquid stream and a hydrocarbon gas stream.

Methods and systems are provided herein utilizing a membrane cascade to separate a hydrocarbon feed into boiling point fractions. Also provided herein are methods for selecting membranes for said cascades to achieve the desired boiling point fraction separation.

An acid gas purification system is described herein that includes a primary membrane system with a CO.sub.2- and H.sub.2S-enriched permeate stream effluent and a hydrocarbon stream effluent; a first compression stage arranged to receive the CO.sub.2- and H.sub.2S-enriched permeate stream and produce a compressed stream; and a cryogenic separation system to receive the compressed stream, the cryogenic separation system including a cooler followed by a fractionator, wherein the fractionator produces a CO.sub.2- and H.sub.2S liquid stream and a hydrocarbon gas stream.

The present disclosure relates to processes for the removal of paraffins. The processes generally include providing a C.sub.4 containing stream including isobutylene, 1-butene, 2-butene, n-butane and isobutane, introducing the C.sub.4 containing stream into a paraffin removal process to form an olefin rich stream, wherein the paraffin removal process is selected from extractive distillation utilizing a solvent including an organonitrile, passing the C.sub.4 containing stream over a semi-permeable membrane and combinations thereof; and recovering the olefin rich stream from the paraffin removal process, wherein the olefin rich stream includes less than 5 wt. % paraffins.

A process and system for recovering natural gas liquids (NGL) using a combination of J-T cooling and membrane separation. The process involves compressing, separating, and cooling a flare gas stream comprising at least methane and C.sub.3+ hydrocarbons prior to being introduced to a J-T valve. The cooled stream exiting the J-T valve is further separated, producing a NGL product stream and an uncondensed gas stream. The uncondensed gas stream is directed to a membrane separation step, which results in a C.sub.3+ hydrocarbon enriched stream and a C.sub.3+ hydrocarbon depleted stream. The C.sub.3+ hydrocarbon enriched stream may be recycled back to the process to recover more NGL.

A process and system for recovering natural gas liquids (NGL) using a combination of J-T cooling and membrane separation. The process involves compressing, separating, and cooling a flare gas stream comprising at least methane and C.sub.3+ hydrocarbons prior to being introduced to a J-T valve. The cooled stream exiting the J-T valve is further separated, producing a NGL product stream and an uncondensed gas stream. The uncondensed gas stream is directed to a membrane separation step, which results in a C.sub.3+ hydrocarbon enriched stream and a C.sub.3+ hydrocarbon depleted stream. The C.sub.3+ hydrocarbon enriched stream may be recycled back to the process to recover more NGL.

The invention relates to membrane gas separation, in particular to a method of fractionating mixtures of low molecular weight hydrocarbons based on the capillary condensation of the mixture components in the pores of microporous membranes having uniform porosity and a pore diameter of 5 to 250 nm, wherein, for capillary condensation, the temperature of the membrane and the pressure on the permeate side are kept below the temperature and the pressure of the feed mixture. The method provides significantly increasing membrane permeability with respect to condensable components, and also component separation factors, while also allowing to avoid deep cooling of the gas stream fed to a membrane module, and to carry out gas separation under insignificant cooling of the membrane on the permeate side (down to -50? C.). The invention provides for energy-efficient fractionation of hydrocarbon mixtures, including separation and drying of natural and associated petroleum gases.

The invention relates to the field of membrane gas separation and can be used for the energy-efficient fractionation of hydrocarbon mixtures, including separation and drying of natural and associated petroleum gases. Proposed is a method of fractionating mixtures of low molecular weight hydrocarbons which is based on the capillary condensation of the components of a mixture in the pores of microporous membranes with uniform porosity and a pore diameter in a range of 5 to 250 nm, wherein, for capillary condensation, the temperature of the membrane and the pressure on the permeate side are kept below the temperature and the pressure of the feed mixture such that the equilibrium pressure of the saturated vapors of the separated components on the permeate side is lower than the partial pressure of the components in the feed stream. This method makes it possible to significantly increase membrane permeability with respect to condensable components (over 500 m.sup.3/(m.sup.2.Math.atm.Math.h) for n-butane), and also component separation factors (the n-C.sub.4H.sub.10/CH.sub.4 separation factor is greater than 60 for a mixture having an associated petroleum gas composition), while also making it possible to dispense with deep cooling of the gas stream fed to a membrane module, and to carry out gas separation under insignificant cooling of the membrane on the permeate side (down to ?50? C.) For more effective gas separation, permeate is collected in a liquid state. A technical effect of the invention resides in providing a method that makes it possible to efficiently remove high-boiling hydrocarbons (C.sub.3-C.sub.6) from natural gas and associated petroleum gases, as well as to obtain gas mixtures with a constant composition.