Method and apparatus for separating gases

Apparatus for separating a purified gas from a mixture thereof with at least one gaseous contaminant, said apparatus comprising a pressure swing adsorption unit comprising a plurality of adsorption zones for adsorbing said contaminant from said mixture and means for purging adsorbent of adsorbed contaminant, said adsorption unit including

• at least four compartments for adsorbent, each having a gas inlet and a gas outlet for gas to be passed through adsorbent in the compartment, each compartment forming a separately isolatable adsorption zone,
• an inlet for the gas mixtures to be separated in said unit.
• an outlet for purified gas,
• an inlet manifold connected to the inlet for the gas mixture,
• a purified gas outlet manifold connected to the outlet for the purified product,
• said means for purging adsorbent comprising a purge gas manifold,
• a waste gas manifold,
• first conduit means for connecting the inlet of each compartment to the inlet manifold, with an inlet valve in the conduit between each compartment inlet and the inlet manifold,
• second conduit means for connecting the outlet from each compartment to the purified gas manifold, with an outlet valve in the conduit between each compartment outlet and the outlet manifold,
• third conduit means for connecting the purge gas manifold to the outlet from each compartment, with a purge gas inlet valve in the conduit between each compartment outlet and the purge gas manifold,
• fourth conduit means for connecting the inlet to each compartment to the waste gas manifold, there being a waste gas outlet valve between each compartment inlet and the waste gas manifold, and
• fifth conduit means adapted to connect the compartments together for flow of gas therethrough with the outlet of each compartment connected to the inlet of the next compartment, there being a valve in the conduit between the outlet of each compartment and the inlet of the next compartment, said valves being arranged such that at least a first and a second of said compartments are connected in series to provide a separation section between the inlet manifold and the outlet manifold for flow of gas therethrough and in that order with respect to the gas flow, at least a third compartment is connected to the outlet manifold for repressurisation and at least a fourth compartment is connected for gas flow therethrough from the purge gas manifold to the waste gas manifold for purging, and automatic valve control means adapted periodically to switch the valves to connect said third compartment in series with said second compartment in said separation section to form the last compartment in said section, expressed in terms of flow of gas therethrough, disconnect said fourth compartment from said purge gas manifold and said waste gas manifold and connect it to said outlet manifold for repressurisation, and disconnect said first compartment from said separation section and connect it between the purge gas manifold and the waste gas manifold for purging.

Apparatus for separating a purified gas from a mixture thereof with at least one gaseous contaminant, said apparatus comprising a pressure swing adsorption unit comprising a plurality of adsorption zones for adsorbing said contaminant from said mixture and means for purging adsorbent of adsorbed contaminant, said adsorption unit including

• at least three compartments for adsorbent, each having a gas inlet and a gas outlet for gas to be passed through adsorbent in the compartment, each compartment forming a separately isolatable adsorption zone,
• an inlet for the gas mixture to be separated in said unit,
• an outlet for purified gas,
• an inlet manifold connected to the inlet for the gas mixture,
• a purified gas outlet manifold connected to the outlet for the purified product,
• a purge gas manifold,
• a waste gas manifold,
• first conduit means for connecting the inlet of each compartment to the inlet manifold, with an inlet valve in the conduit between each compartment inlet and the inlet manifold,
• second conduit means for connecting the outlet from each compartment to the purified gas manifold, with an outlet valve in the conduit between each compartment outlet and the outlet manifold,
• third conduit means for connecting the purge gas manifold to the outlet from each compartment, with a purge gas inlet valve in the conduit between each compartment outlet and the purge gas manifold,
• fourth conduit means for connecting the inlet to each compartment to the waste gas manifold, there being a waste gas outlet valve between each compartment inlet and the waste gas manifold, and
• fifth conduit means adapted to connect the compartments together for flow of gas therethrough with the outlet of each compartment connected to the inlet compartment, there being a valve in the conduit between the outlet of each compartment and the inlet of the next compartment, said valves being arranged such that at least a first and a second of said compartments are connected in series to provide a separation section between the inlet manifold and the outlet manifold for flow of gas therethrough and in that order with respect to the gas flow, and at least a third compartment is connected for gas flow therethrough from the purge gas manifold to the waste gas manifold for purging, and automatic valve control means adatped periodically to switch the valves to disconnect said third compartment from said purge gas manifold and said waste gas manifold and connect it in series with said second compartment in said separation section to form the last compartment in said section, expressed in termes of flow of gas therethrough and disconnect said first compartment from said separation section and connect it between the purge gas manifold and the waste gas manifold for purging.

A method of separating a purified gas from a mixture thereof with at least one gaseous contaminant, said method comprising the steps of

• a. providing an adsorption unit comprising x zones of adsorbent material which selectively adsorbs said gaseous contaminant, x being a whole number of at least three;
• b. passing the gas mixture at a first pressure through y of the zones of said adsorption unit arranged in series with respect to the flow of the gas mixture therethrough, y being a whole number of from 2 to x - 1 and said y zones constituting a separation section of said adsorption unit;
• c. recovering from the last zone of said separation section a purified gas in which the concentration of the contaminant does not exceed a predetermined value which is below the concentration of contaminant in the gas mixture;
• d. before the concentration of the contaminant in said purified gas rises above said predetermined value, but after the concentration of said contaminant in the gas stream leaving the zone forming the penultimate zone of said separation section has exceeded said predetermined value, adding another zone of said adsorption unit to the end of said separation section, expressed in terms of the direction of flow of said gas mixture through the separation section whereby said added zone now forms the last zone of said separation section;
• e. removing from said separation section the zone forming the first zone of the section whereby the zone next to it in the separation section now becomes the first zone;
• f. regenerating the adsorbent in said removed zone by evacuation of said zone;
• g. periodically repeating steps (d), (e) and (f) whereby each zone of said unit is in successive periods incorporated into the separation section as the last zone thereof, subsequently periodically progressed along said section until it becomes the first zone thereof, and then treated to regenerate the adsorbent therein ready for re-incorporation into the separation section in a subsequent period.

A method of separating a purified gas from a mixture thereof with at least one gaseous contaminant by pressure swing adsorption, said method comprising the steps of

• a. providing an adsorption unit comprising x zones of adsorbent material which selectively adsorbs said gaseous contaminant, x being a whole number of at least three;
• b. passing the gas mixture at a first pressure through y of the zones of said adsorption unit arranged in series with respect to the flow of the gas mixture therethrough, y being a whole number of from 2 to x - 1 and said y zones constituting a separation section of said adsorption unit;
• c. recovering from the last zone of said separation section a purified gas in which the concentration of the contaminant does not exceed a predetermined value which is below the concentration of contaminant in the gas mixture;
• d. before the concentration of the contaminant in said purified gas rises above said predetermined value, but after the concentration of said contaminant in the gas stream leaving the zone forming the penultimate zone of said separation section has exceeded said predetermined value, adding another zone of said adsorption unit to the end of said separation section, expressed in terms of the direction of flow of said gas mixture through the separation section whereby said added zone now forms the last zone of said separation section;
• e. removing from said separation section the zone forming the first zone of the section whereby the zone next to it in the separation section now becomes the first zone;
• f. reducing the pressure in said removed zone and purging the adsorbent in said removed zone of adsorbed material by passing a purge gas through it at a second pressure which is lower than the first pressure whereby to prepare said zone for re-use in the adsorption section commencing as the last zone of said section;
• g. periodically repeating steps (d), (e) and (f) whereby each zone of said unit is in successive periods incorporated into the separation section as the last zone thereof, subsequently periodically progressed along said section until it becomes the first zone thereof, and then purged ready for re-incorporation into the separation section in a subsequent period;
• and
• h. recycling the gas initially exiting from said removed zone during the step of reducing the pressure in said zone to the inlet of the separation section to be passed therethrough at substantially said first pressure, said recycle being continued until not later than the occurrence of a rapid increase in concentration of said contaminant in said exit gas.

Apparatus for separating a purified gas from a mixture thereof with at least one gaseous contaminant, said apparatus comprising an adsorption unit comprising a plurality of adsorption zones for adsorbing said contaminant from said mixture and means for regenerating adsorbent, said adsorption unit including

• at least three compartments for adsorbent, each having a gas inlet and a gas outlet for gas to be passed through adsorbent in the compartment, each compartment forming a separately isolatable adsorption zone,
• an inlet for the gas mixture to be separated in said unit,
• an outlet for purified gas,
• an inlet manifold connected to the inlet for the gas mixture,
• a purified gas outlet manifold connected to the outlet for the purified product,
• said regenerating means comprising means for evacuating the adsorption zones,
• first conduit means for connecting the inlet of each compartment to the inlet manifold, with an inlet valve in the conduit between each compartment inlet and the inlet manifold,
• second conduit means for connecting the outlet from each compartment to the purified gas manifold, with an outlet valve in the conduit between each compartment outlet and the outlet manifold,
• third conduit means for connecting the interior of each compartment to said evacuating means, there being a valve between each compartment interior and the evacuating means, and
• fourth conduit means adapted to connect the compartments together for flow of gas therethrough with the outlet of each compartment connected to the inlet of the next compartment, there being a valve in the conduit between the outlet of each compartment and the inlet of the next compartment, said valves being arranged such that at least a first and a second of said compartments are connected in series to provide a separation section between the inlet manifold and the outlet manifold for flow of gas therethrough and in that order with respect to the gas flow, and at least a third compartment is connected to said evacuating means for regeneration of the adsorbent therein, and automatic valve control means adapted periodically to switch the valves to disconnect said third compartment from said evacuating means and connect it in series with said second compartment in said separation section to form the last compartment in said section, expressed in terms of flow of gas therethrough and disconnect said first compartment from said separation section and connect it to said evacuating means for regeneration of the adsorbent therein.