Boc, Inc.

The Boc Group, Inc.

John W Armond

Kenneth C Smith

Devasihamani J Sebastian

David A Webber

David J Graham

Martyn S Ray

In a pressure swing adsorption plant for the production of oxygen enriched gas a pressure vessel contains a first bed of molecular sieve adsorbent located adjacent an outlet 4 of the vessel which has an optimum operating efficiency at approximately ambient temperature and a second bed 10 of molecular sieve adsorbent which has an optimum efficiency below that of ambient operating temperature located adjacent the inlet 2.

Pressure swing adsorption plants

A compressed gas mixture, for example air, is passed through one of beds 12 and 14 of adsorbent that selectively adsorbs oxygen from the air. Unadsorbed nitrogen-enriched gas flows into a buffer vessel 28, from which product gas is withdrawn through pipeline 30. While one of the beds 12 and 14 is adsorbing oxygen for air the other is being regenerated, and during this period the communication between the beds is denied. At the end of a chosen period of time the beds are placed in communication with one another by opening valves 54 and 56. Then the bed that was previously being regenerated is placed in communication with the source of compressed air and the other bed regenerated. The period of intercommunication between the beds lasts for as long as it takes the volume of product gas as measured by an integrating flow meter 31 from the start of the preceding adsorption step to reach a chosen value. The apparatus is able to supply nitrogen of a chosen purity at a variable flow rate.

Process and apparatus for separation of a gaseous mixture

In a gas separation process a pressurized gaseous mixture is passed through a first bed of adsorbent while a second bed is being regenerated by desorbing gas therefrom and venting or discharging such gas from the second bed. The adsorbent is of such a character that one component of the gaseous mixture is preferentially adsorbed. The non-adsorbed component or components are collected as product. After a chosen time flow of gas into the first bed and out of the second bed is stopped, and the two beds are placed in communication with one another through a flow restrictor means so as to reduce the pressure difference therebetween. The flow restriction means is effective to prevent fluidization of the beds. The intercommunication between the two beds is stopped before the pressure difference therebetween has been eliminated and the gas mixture is then passed through the second bed, while the first is regenerated. The pressure difference between the two beds is then reduced and the cycle of operations repeated.

Process for the separation of a gaseous mixture

A portion of a component of a gas stream is condensed with the remaining non-condensed gas stream being passed to an adsorber. The remainder of the component in the non-condensed stream is adsorbed in the adsorber and in a later stage of the adsorber cycle, the adsorbed component is desorbed and supplied to the inlet of a condenser together with the gas stream to promote condensation of the component by providing an increased concentration of the component in the gas stream.

Treatment of gas streams

An air separation process using pressure swing adsorption techniques, for providing high purity oxygen. Two sections are employed one comprising beds of molecular sieve carbon and the other comprising beds of zeolite molecular sieve. Air is fed to a first of the sections which provides an oxygen-rich gas stream as feedstock for the next section where further enrichment takes place. The zeolite sieve section serves to effect a separation as between oxygen and nitrogen while the carbon sieve section serves to effect a separation as between oxygen and argon and the processes performed at each section are integrated in such a manner as to minimize power consumption and make use of gas recycled from the second section to the first in addition to the flow of gas from the first section to the second.

Gas separation

A process and apparatus for separating gaseous mixtures by a pressure swing adsorption technique. One or more adsorbent beds are employed which operate on a cycle comprising the successive steps of adsorption, vacuum regeneration, and backfilling. The pressure in the bed(s) during backfilling is sensed, backfilling is ceased when such pressure reaches a predetermined level, and the regeneration step is controlled to occupy a constant period of time. The described process is able to maintain a substantially constant output flow and product purity despite the changes in adsorption capacity of the bed(s) which occur under fluctuating ambient temperatures.

A process for increasing the proportion of a gas in a gaseous mixture of which it is a component. The gaseous mixture is allowed to be drawn through an adsorbent bed in a substantially unpressurized condition by the action of a reduced pressure applied to an outlet of the bed. The bed is then regenerated prior to a further admission of the gaseous mixture thereto.

A process for increasing the proportion of a gas in a gaseous mixture comprising such gas and at least two other constituents. The gaseous mixture in a substantially unpressurized condition is drawn successively through two beds of absorbent which adsorbs the two other constituents respectively by the action of a reduced pressure applied to an outlet of the second adsorbent bed in the series. The beds are then regenerated prior to a further admission of gaseous mixture thereto.

Method and apparatus for separating gaseous mixtures using adsorbent material. The mixture is contacted with an adsorbent bed which adsorbs preferentially a desired product gas constituent of the mixture. The bed is then purged with such gas or a stream rich in such gas at a pressure substantially equal to the partial pressure of that gas in the gaseous mixture fed to the adsorbent bed. The bed is then regenerated to recover product gas.

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Buckhurst Hill, United Kingdom

John W Armond