US 6,440,196 B1Granted

Method for purifying and concentrating a gas mixture into a minor constituent, method for detecting this constituent, and installation

AssigneeCommissariat a l'Energie Atomique

InventorsRemo Chiappini, Jean-Pierre Fontaine, Michel Hamonet, Michel Thouard

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Abstract

A method for purifying a minority constituent and concentrating it in a majority constituent of a gas mixture that also contains one or more other minority constituent(s) employs (i) a selective permeation step, (ii) next, a purification step, and (iii) finally a concentration step. In the selective permeation step, an initial gas mixture is passed through a membrane to yield a gas mixture that is enriched in the first minority constituent. In the purifying step, the first minority constituent is absorbed by a solid adsorbent which has a strong affinity for the first minority constituent, then following an elution step, a gas mixture that contains essentially only the majority constituent and the first minority constituent is formed. Finally, in the concentrating step, one or more successive adsorption and elution operations on a solid adsorbent, which has a strong specific affinity for the first minority constituent, are employed until an end gas mixture having the desired concentration of the majority constituent and the first minority constituent is obtained. This end gas mixture is highly enriched in the first minority constituent relative to the initial gas mixture. The procedure is particularly suited for detecting rare gases, e.g., xenon, and especially for detecting the natural and radioactive species in the atmosphere. The procedure can be employed in association with nuclear spectrometry to detect and monitor the presence of trace gases in the environment around nuclear installations.

Claims21

Dependent claims

Method for purifying a first minority constituent and concentrating the latter in the majority constituent of a gas mixture containing, in addition to said first minority constituent and said majority constituent, one or more other minority constituent(s), said method comprising the succession of following steps:

Selective permeation of an initial gas mixture to be treated through a membrane specific to the initial gas mixture, after which a gas mixture is obtained enriched in said first minority constituent and much depleted or only slightly enriched in said other minority constituent(s);
Purifying said gas mixture enriched in said first minority constituent derived from the first step, by adsorption at ambient temperature on a solid adsorbent which is a specific adsorbent having a strong affinity for the first minority constituent, then elution, after which a gas mixture is obtained essentially made up of said majority constituent and said first minority constituent, and from which the other minority constituent(s) have been removed,
Concentrating said first minority constituent in the majority constituent derived from the second step, by one or more successive adsorption and elution operations on a solid adsorbent which is a specific adsorbent having a strong affinity for the first minority constituent, until an end gas mixture is obtained essentially made up of said majority constituent and said first minority constituent, highly enriched in said first minority constituent relative to said initial gas mixture, and having the desired concentration of said first minority constituent.

Dependencies are inferred from the claim text.