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Gas Cleaning: Active Carbon Absorption (ACA)

By The Environmental Group Limited

ACA systems clean industrial exhaust air of a wide range of pollutants, in particular volatile organic compounds (VOC’s) and hydrogen sulphide (H2S).

The VOC or H2S laden air is directed through one or more beds of carbon. The air can be pre-filtered, dehumidified or cooled if necessary to assist the adsorption.

The carbon takes the form of small granules or extruded (8mm long) pieces. Very high rates of adsorption can occur, such that the exhaust air is essentially free of VOC’s or H2S. The carbon is replaced when its working capacity has been reached.

If there are high loadings of VOC it becomes uneconomic to replace the carbon after one use. In such cases regenerable systems are used. These systems have a duty and a standby bed. At any given time the duty bed is adsorbing VOC’s while the standby bed is being regenerated by steam stripping.

ACA systems have very wide application, ranging from bulk liquid hydrocarbon storage and handling facilities (tank farms) to sewage transport systems odour control.