Pressure swing adsorption process for reducing fluctuations in the flow rate of tail gas from the adsorption unit. The flow rate of the stream of blowdown gas is regulated responsive signals from a sensor measuring the pressure and/or flow rate of the tail gas comprising the blowdown gas and purge gas effluent before the tail gas is introduced into a surge vessel.

A process and apparatus for producing a hydrogen-enriched product and recovering CO.sub.2 from an effluent stream from a hydrogen production process unit are described. The process utilizes a CO.sub.2 recovery system integrated with a PSA system that produces at least two product streams to recover additional hydrogen and CO.sub.2 from the tail gas stream of a hydrogen PSA unit in the hydrogen production process.

A process and apparatus for producing a hydrogen-enriched product and recovering CO.sub.2 from an effluent stream from a hydrogen production unit are described. The effluent from the hydrogen production unit, which comprises a mixture of gases comprising hydrogen, carbon dioxide, water, and at least one of methane, carbon monoxide, nitrogen, and argon, is sent to a PSA system that produces at least two product streams for separation. The PSA system that produces at least two product streams separates the gas mixture into a high-pressure hydrogen stream enriched in hydrogen, optionally a second gas stream containing the majority of the impurities, and a low-pressure tail gas stream enriched in CO.sub.2 and some impurities. The CO.sub.2-rich tail gas stream is compressed and sent to a CO.sub.2 recovery unit, where a CO.sub.2-enriched stream is recovered. The CO.sub.2-depleted overhead gas stream is recycled to the PSA system that produces at least two product streams.

Provided are apparatus and systems for performing a swing adsorption process. This swing adsorption process may involve performing modeling to generate a swing adsorption system to manage a feed stream to produce a product stream within specification. The process may be utilized for swing adsorption processes, such as TSA and/or PSA, which are utilized to remove one or more contaminants from a gaseous feed stream.

The embodiments of the present disclosure provide a portable oxygen concentrator. The portable oxygen concentrator may comprise an input configured to receive air flow, a column comprising a housing, an outer porous tube, an inner porous tube, and an inner cavity, and an output configured to release oxygen to a user. The inner porous tube comprises an adsorbent bed comprising a plurality of zeolites, and the column is configured to channel air radially through and across the outer porous tube, through and across the adsorbent bed in the inner porous tube, into the inner cavity of the column, and through the output. When the air flow contacts the adsorbent bed, oxygen is released.

The invention includes methods for removing higher acetylenes from a gaseous stream that includes a hydrogen fraction and a non-hydrogen fraction, wherein the gaseous stream includes less than about 4% in total of diacetylene and vinylacetylene, where the method includes the following steps: (i) an adsorption that passes the gaseous stream at a preselected superficial linear gas velocity across an adsorption bed supported within an enclosure, the adsorption bed containing a crystalline porous ceramic adsorbent to adsorb the higher acetylenes onto the adsorbent, thereby producing a saturated adsorption bed and a purified gaseous stream including less than about 25 ppm of diacetylene that regenerates the saturated adsorbent bed by passing a regeneration gas across the saturated adsorption bed to desorb the higher acetylenes retained thereupon, thereby producing a regenerated adsorbent bed and a contaminated gas stream bearing the higher acetylenes; and (iii) a purging step that removes the contaminated gas stream from the enclosure. The invention also includes systems for removing diacetylene and vinylacetylene from a hydrogen-dominant acetylene-hydrogen gaseous stream.

Drying compressed air while utilizing a method for preemptive overload avoidance of moisture to a desiccant bed, including a recovery control process. The method may include a purge means, an initialization period for pre-learning to develop usage-profile log performance summary to compare against real-time data and a protocol for a normal state, a recovery state and a supplemental purge state and means to reestablish normal operations. A procedure for standby and overload alarm alerting states are also described. The purge means may be fixed rate or modulating. The system may have cycle times decrementing or incrementing stepwise in a predetermined or varying time frame to respond to on-going trending data in order to correct imbalance loading conditions by adjusting drying and regenerating cycle times, thus affording a stable delivery of quality dewpoint compressed air to the dryer output.

Provided are apparatus and systems for performing a swing adsorption process. This swing adsorption process may involve performing a startup mode process prior to beginning a normal operation mode process to remove contaminants from a gaseous feed stream. The startup mode process may be utilized for swing adsorption processes, such as TSA and/or PSA, which are utilized to remove one or more contaminants from a gaseous feed stream.

An aircraft environmental control system includes means for mixing and conditioning bleed air from a bleed air input and recirculation air from an aircraft interior to provide mixed, conditioned air to the aircraft interior. The system also includes a first contaminant removal device and a second contaminant removal device arranged in a path of at least part of the recirculation air, prior to the means for mixing and conditioning, and a valve (SV1) arranged to alternate flow of recirculation air through the first and second contaminant removal devices.

Provided are apparatus and systems for performing a swing adsorption process. This swing adsorption process may involve performing a startup mode process prior to beginning a normal operation mode process to remove contaminants from a gaseous feed stream. The startup mode process may be utilized for swing adsorption processes, such as TSA and/or PSA, which are utilized to remove one or more contaminants from a gaseous feed stream.