Abstract: The invention relates to a process for recovering methane from digester biogas or landfill gas. More specifically, the invention pertains to a method for producing biomethane that removes impurities from a compressed digester biogas with staged membrane modules of at least two different types, to produce a biomethane having at least 94% CH4, below 3% of CO2, and below 4 ppm of H2S.

Abstract: This invention integrates a membrane with a steam reformer such that a membrane is placed between a raw biogas feed, and a steam reformer to supply a retentate of purified methane feed to the steam reformer and the permeate as fuel to the steam reformer,

Abstract: Nitrogen is removed from biogas using a three-stage separation system based on gas separation membranes. The first stage separates a biomethane feed stream into a first permeate gas stream and a first retentate gas stream. The second stage separates the first permeate stream into a biomethane product gas and a first low quality biomethane gas stream. The third stage separates the first retentate into a second low quality biomethane gas stream and a waste gas. A biogas feed stream is pretreated to remove amounts of water, VOCs, and CO2 to yield a methane-enriched biogas stream. The methane-enriched biogas stream is compressed together with the first and second low quality biomethane gas streams to form the biomethane feed stream.

Abstract: The invention relates to a process for recovering methane from digester biogas or landfill gas. More specifically, the invention pertains to biomethane production that substantially removes carbon dioxide from a digester biogas or landfill gas using first, second, and third purification stages each comprising one or more membranes selective for carbon dioxide over methane. A retentate from the first stage is separated by the one more membranes of the second stage into a second state retentate, forming a biomethane product gas. A permeate from the first stage is separated by the one or more membranes of the third stage into a third stage retentate and a third stage permeate. Recovery of methane from the the biogas is boosted by feeding the third stage retentate to the first purification stage. The recovery may be optionally further boosted by compressing the second stage permeate with the biogas at a main compressor.

Abstract: The invention relates to a process for recovering methane from digester biogas or landfill gas. More specifically, the invention pertains to a method for producing biomethane that removes impurities from a compressed digester biogas with staged membrane modules of at least two different types, to produce a biomethane having at least 94% CH4, below 3% of CO2, and below 4 ppm of H2S.

Abstract: The invention relates to a process for recovering methane from digester biogas or landfill gas. More specifically, the invention pertains to a method for producing biomethane that removes impurities from a compressed digester biogas with staged membrane modules of at least two different types, to produce a biomethane having at least 94% CH4, below 3% of CO2, and below 4 ppm of H2S.

Abstract: The invention relates to a process for recovering methane from digester biogas or landfill gas. More specifically, the invention pertains to biomethane production that substantially removes carbon dioxide from a digester biogas or landfill gas using first, second, and third purification stages each comprising one or more membranes selective for carbon dioxide over methane. A retentate from the first stage is separated by the one more membranes of the second stage into a second state retentate, forming a biomethane product gas. A permeate from the first stage is separated by the one or more membranes of the third stage into a third stage retentate and a third stage permeate. Recovery of methane from the biogas is boosted by feeding the third stage retentate to the first purification stage. The recovery may be optionally further boosted by compressing the second stage permeate with the biogas at a main compressor.

Abstract: Nitrogen is removed from biogas using a three-stage separation system based on gas separation membranes. The first stage separates a biomethane feed stream into a first permeate gas stream and a first retentate gas stream. The second stage separates the first permeate stream into a biomethane product gas and a first low quality biomethane gas stream. The third stage separates the first retentate into a second low quality biomethane gas stream and a waste gas. A biogas feed stream is pretreated to remove amounts of water, VOCs, and CO2 to yield a methane-enriched biogas stream. The methane-enriched biogas stream is compressed together with the first and second low quality biomethane gas streams to form the biomethane feed stream.

Abstract: Biogas containing H2S and CO2 is upgraded by removing H2S using PTSA and CO2 using two stages of gas separation membranes. The first stage permeate may optionally be used a regeneration gas stream. The second stage permeate may optionally be used a cool down gas stream. The PTSA unit includes two or more adsorbent beds each selective for water, VOCs, and H2S over CO2 and for H2S over methane.

Abstract: The invention relates to a process for recovering methane from digester biogas or landfill gas. More specifically, the invention pertains to biomethane production that substantially removes carbon dioxide from a digester biogas or landfill gas using first, second, and third purification stages each comprising one or more membranes selective for carbon dioxide over methane. A retentate from the first stage is separated by the one more membranes of the second stage into a second state retentate, forming a biomethane product gas. A permeate from the first stage is separated by the one or more membranes of the third stage into a third stage retentate and a third stage permeate. Recovery of methane from the biogas is boosted by feeding the third stage retentate to the first purification stage. The recovery may be optionally further boosted by compressing the second stage permeate with the biogas at a main compressor.

Abstract: Biogas containing H2S and CO2 is upgraded by removing H2S using PTSA and CO2 using two stages of gas separation membranes. The first stage permeate may optionally be used a regeneration gas stream. The second stage permeate may optionally be used a cool down gas stream. The PTSA unit includes two or more adsorbent beds each selective for water, VOCs, and H2S over CO2 and for H2S over methane.

Abstract: The invention relates to a process for recovering methane from digester biogas or landfill gas. More specifically, the invention pertains to a method for producing biomethane that removes impurities from a compressed digester biogas with staged membrane modules of at least two different types, to produce a biomethane having at least 94% CH4, below 3% of CO2, and below 4 ppm of H2S.

Abstract: Biogas containing H2S and CO2 is upgraded by removing H2S using PTSA and CO2 using two stages of gas separation membranes. The first stage permeate may optionally be used a regeneration gas stream. The second stage permeate may optionally be used a cool down gas stream. The PTSA unit includes two or more adsorbent beds each selective for water, VOCs, and H2S over CO2 and for H2S over methane.

Abstract: Biogas containing H2S and CO2 is upgraded by removing H2S using PTSA and CO2 using two stages of gas separation membranes. The first stage permeate may optionally be used a regeneration gas stream. The second stage permeate may optionally be used a cool down gas stream. The PTSA unit includes two or more adsorbent beds each selective for water, VOCs, and H2S over CO2 and for H2S over methane.

Abstract: A natural gas feedstream containing contaminants such as carbon dioxide is purified by passing the contaminated natural gas stream through a membrane to remove the bulk of the contaminant, passing the purified natural gas stream to a TSA unit to remove additional contaminant from the natural gas stream to a desired specification, and regenerating the TSA adsorbent by heating the adsorbent with a heated contaminant-containing permeate stream from the membrane.

Abstract: A natural gas-containing stream such as biogas from landfills and sewage treatment plants is freed of siloxane contaminants by passing the biogas through a bed containing an adsorbent having a neutral surface, which adsorbs the siloxanes. When the bed of neutral adsorbent is filled to capacity, the adsorbent bed is heated to remove the siloxanes and regenerate the bed. The neutral adsorbent reduces disadvantageous reactions between the adsorbent and siloxane and other impurities in the natural gas-containing stream.

Abstract: A natural gas-containing stream such as biogas from landfills and sewage treatment plants is freed of siloxane contaminants by passing the biogas through a bed containing an adsorbent having a neutral surface, which adsorbs the siloxanes. When the bed of neutral adsorbent is filled to capacity, the adsorbent bed is heated to remove the siloxanes and regenerate the bed. The neutral adsorbent reduces disadvantageous reactions between the adsorbent and siloxane and other impurities in the natural gas-containing stream.

Abstract: A natural gas feedstream containing contaminants such as carbon dioxide is purified by passing the contaminated natural gas stream through a membrane to remove the bulk of the contaminant, passing the purified natural gas stream to a TSA unit to remove additional contaminant from the natural gas stream to a desired specification, and regenerating the TSA adsorbent by heating the adsorbent with a heated contaminant-containing permeate stream from the membrane.

Abstract: The present invention is directed toward a method for purifying a natural gas stream comprising: 1) removing the bulk of CO2 by at least one non-membrane gas separation means; and 2) removing oxygen and other impurities by at least one additional gas separation means, wherein the final natural gas product has low level of CO2 and oxygen.

Abstract: A process for removing hydrogen sulfide from a raw natural gas stream such as biogas from landfills or controlled anaerobic digestion comprises passing the natural gas stream though a separation unit such as a PSA unit to form a product stream comprising a high concentration of methane and a low pressure tail gas containing hydrogen sulfide, passing the tail gas through a biofilter which includes bacteria that degrades the hydrogen sulfide to sulfur and sulfate compounds which are washed from the biofilter. The tail gas stream subsequent to treatment in the biofilter can be flared to the atmosphere without significant SOx emissions.