Abstract: An air treatment system includes a recirculation line (24) through which air from the enclosed space can be recirculated, and a contaminant adsorption assembly (36) is provided in an auxiliary supply conduit (31). In the event that contaminants are detected in atmospheric air, air from the enclosed space can be recirculated for conditioning and then readmitted to the enclosed space. Oxygen that is breathed by occupants of the enclosed space can be replenished by admitting air from atmosphere, which is treated using the adsorption assembly and then mixed with air that is in the enclosed space or being recirculated for admission to the enclosed space.

Abstract: A system for treating air for supply to an enclosed space in which the air is to be breathed, includes an inlet through which air can enter the system from atmosphere for supply to the enclosed space, and a regenerative adsorption assembly having at least two chambers which contain an adsorbent material, arranged so that air flowing in the inlet for supply to the enclosed space can pass through one of the chambers for adsorption of contaminants before supply to the enclosed space while adsorbent material in another of the chambers is purged of adsorbed contaminants. A recirculation path is provided for supplying air from the enclosed space to the inlet to be mixed with air from atmosphere before it is supplied to the enclosed space. The system includes structure for adjusting the resistance to flow of air through the recirculation path.

Abstract: A gas dryer includes a housing, and a drying drum in the housing which is permeable to allow a flow of gas through the drum between its opposite first and second ends. A first flow guide is located at the first end of the drum and a second flow guide is located at the second end of the drum. The first and second flow guides define between them a primary region of the drum for a primary gas flow to flow through the drum, and a secondary region of the drum for a secondary gas flow to flow through the drum, and are mounted for rotation about the drum axis so that boundaries between the primary and secondary regions rotate around the drum. The permeable structure of the drying drum and the flow guides allow the primary and secondary gas flows to flow through their respective regions of the drum without significant mixing.

Abstract: A drum dryer comprises a drying drum which is arranged for a gas to flow through it to be dried from a first end of the drum to its opposite second end, and a housing in which the drum is located with a space around the drum between the internal wall of the housing and the external surface of the drum. Gas can be directed into the space through a housing inlet, to flow in the space to the first end of the drum where it can be admitted into the drum for drying.

Abstract: A system for treating air for supply to an enclosed space in which the air is to be breathed, includes an inlet through which air can enter the system from atmosphere for supply to the enclosed space, and a regenerative adsorption assembly having at least two chambers which contain an adsorbent material, arranged so that air flowing in the inlet for supply to the enclosed space can pass through one of the chambers for adsorption of contaminants before supply to the enclosed space while adsorbent material in another of the chambers is purged of adsorbed contaminants. A recirculation path is provided for supplying air from the enclosed space to the inlet to be mixed with air from atmosphere before it is supplied to the enclosed space. The system includes structure for adjusting the resistance to flow of air through the recirculation path according to the resistance that is provided to the flow of air from atmosphere into the enclosed space.

Abstract: An air conditioning system comprises first (8) and second (13) heat exchangers having first and second counterflow passages, a twin bed gas purification unit comprising (i) first (22) and second (23) parallel filter beds, (ii) valve means for directing air from an inlet to flow through the first filter bed and for directing purified air from the first bed so that a greater proportion flows to an outlet while a smaller proportion flows in counter direction as purge gas through the second bed and then to a purge outlet, (iii) a plurality of heater units (30) at spaced apart locations along each of the filter beds for heating a gas as it flows through the heater bed, and (iv) means for controlling the heater.