Various illustrative embodiments of a system and process for recovering high-quality biomethane and carbon dioxide product streams from biogas sources and utilizing or sequestering the product streams are provided. The system and process synergistically yield a biomethane product which meets gas pipeline quality specifications and a carbon dioxide product of a quality and form that allows for its transport and sequestration or utilization and reduction in greenhouse gas emissions. The system and process result in improved access to gas pipelines for products, an improvement in the carbon intensity rating of the methane fuel, and improvements in generation of credits related to reductions in emissions of greenhouse gases.

A process and an apparatus are disclosed for separation of a hydrocarbon gas stream containing methane and heavier hydrocarbons and significant quantities of nitrogen and carbon dioxide. The gas stream is cooled and expanded, then fractionated in a first distillation column into a first overhead vapor and a hydrocarbon liquid stream containing the majority of the carbon dioxide. The hydrocarbon liquid stream is fractionated into a hydrocarbon vapor stream and a less volatile fraction comprised of heavier hydrocarbons.

The first overhead vapor is cooled, expanded, and separated into vapor and liquid streams. Both streams are cooled and expanded before feeding a second distillation column that produces a second overhead vapor that is predominantly nitrogen and a bottom liquid that is predominantly methane. The bottom liquid is vaporized and combined with the hydrocarbon vapor stream to form a volatile residue gas fraction containing the majority of the methane.

A combined plant for cryogenic separation and liquefaction of methane and carbon dioxide in a biogas stream, including a mixing means, a compressor, a first exchanger, a distillation column, a second exchanger, a separating means, an expanding means, and a separator vessel. Wherein, the mixing means is configured such that the recycle gas is the overhead vapour stream, and the first exchanger and the expanding means are combined.

The present invention relates to a method for modifying the crystalline inorganic framework of an adsorbent with coatings to provide rate selectivity for one gas over others is described. The method described herein narrows the effective pore size of crystalline porous solids with pores less than about 5 Å for rate selective separations. This method of the invention comprises treating the hydrated or partially hydrated zeolite with a silicone derived binding agent followed by subsequent heat treatment. The additive content and treatment are adjusted to match effective pore size to specific separations. The superior adsorbent has the added convenience of bead forming simultaneously with pore modification as well as having the treatment result in the yielding of high crush strength products.

Process for producing biomethane from a biogas stream including methane, carbon dioxide and at least one impurity chosen from ammonia, volatile organic compounds, water, sulfur-based impurities (H.sub.2S) and siloxanes. A biogas stream is dried, the at least one impurity is at least partially removed by solidification and removal of the impurity. The methane and the carbon dioxide contained in the biogas obtained from the second step are separated so as to produce a biomethane stream and a CO.sub.2 stream.

A feed containing methane and nitrogen gas is processed in a three-stage membrane system, each stage of which is selective for methane over nitrogen. The methane enriched permeate from the first stage is removed as product gas. The methane-depleted residue from the second stage is purified in second and third cascaded stages to provide second and third permeates and second and third residues. The third stage permeate is recycled to the feed.

The present invention generally relates to a pressure swing adsorption process for separating an adsorbate impurity from a feed stream comprising product gas, said process comprising feeding the feed stream to an adsorbent bed at a pressure of from about 60 psig to 2000 psig, wherein said adsorbent bed comprises adsorbent having: An isosteric heat of adsorption of from about 5 kJ/mol to about 30 kJ/mol, as determined by the LRC method, for the adsorbate, and an equivalent 65 kJ/mol or less isosteric heat of adsorption for the product,
wherein the adsorbent has a rate of adsorption for the adsorbate impurity that is at least 10 times greater than the rate of adsorption for the product gas as determined by the TGA method and recovering said product gas with a reduced a level of said adsorbate impurity. The invention also related to an adsorbent useful in PSA separations, particularly separating N.sub.2 from methane, CO.sub.2 from methane O.sub.2 from N.sub.2 and the like.

Disclosed herein are carbon molecular sieves and methods of making the same through the pyrolysis of a polymer precursor in the presence of a reactive gas stream including a hydrogen source.

Methods and systems for producing and using multi-layer composite co-polyimide membranes, one method for producing including preparing a microporous or mesoporous membrane support material for coating; applying a sealing layer to the membrane support material to prevent intrusion into the membrane support material of co-polyimide polymer; applying a first permselective co-polyimide layer atop and in contact with the sealing layer; and applying a second permselective co-polyimide layer atop and in contact with the first permselective co-polyimide layer.

A method, system, and apparatus for managing variable, multi-phase fluid conversion to output fuel and energy for providing customizable management for processing a volume of natural gas including a volume of methane and a volume of other alkanes that may be cleaned of the other alkanes using a conversion system to create synthesis gas and other fuel products to be used in onsite or combined heat and power or cogeneration applications. In particular, the method, system, and apparatus provide for automated feedback and control directing various gas constituents to different application units with allocations according to settings system parameters to quickly and efficiently meet the demand for various products while making adjustments in real-time.