Croda Chemicals

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The packed tower scrubbing system is designed to treat exhaust air and ensures that emissions discharged to atmosphere from a chemical production sites and wastewater treatment facility, are odour free.

The air is ducted to the exhaust fans from which it enters the base of the scrubbing tower, passing upwards through a bed of packing media. This provides the maximum level of surface area for direct contact between the contaminated air and a scrubbing liquor which absorbs odorous contaminants. The scrubbing liquor, a dilute alkaline solution of sodium hypochlorite, is recirculated by a recycle pump from an integral tank at the base of the scrubber to the top of the tower where, evenly distributed by water sprays, it flows downwards through the packing media.

The dosing rate of sodium hypochlorite is controlled by the Redox potential of the scrubbing liquor, and to ensure that the acid gases and H2S are fully absorbed, it is necessary that the solution is alkaline – a condition maintained by a pH controller which regulates the dosing of sodium hydroxide solution. Due to the chemical reaction, a periodic blowdown is required to maintain dissolved salt levels in the liquor at acceptable levels.

Before being vented to atmosphere via a stack, clean air passes through a demister at the top of the scrubber to reduce carry over of liquor droplets.

Project Details

Client: Croda Chemicals

Industry: Chemicals

Application: Odour control system to treat 12 000 m3/h of exhaust air from an effluent treatment plant.


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Packed Towers