Scrubbers slash sulphur and chlorine emissions
15 Jan 2000
When a speciality chemicals producer needed to slash the emissions from chlorination and sulphonation units, it called in Yorkshire-based environmental technology specialist Chem Resist.
The unit installed at the site had to handle an inlet gas which was heavily contaminated with HCl, SO2 and SOCl2, all of which are reactive and corrosive. The solution was to route the gas stream through a high-rate primary spray tower unit in series with a secondary fluidised bed scrubbing unit.
Initially, the contaminated stream flows into two spray tower/packed column units, mounted in series above a 10 000l sodium hydroxide liquor reservoir. These hydrolyse the high concentrations of thionyl chloride, converting it into HCl and SO2. This less corrosive mixture then passes into the secondary scrubber, which uses a fluidised bed with a turbulent contact absorption column. The stream passes through a `polishing scrubber' before being vented to atmosphere.
Because the contaminants are so aggressive, the system is constructed entirely out of thermoplastics. The initial spray towers, where the effluent is at its most corrosive, are made of glass-reinforced fluoroplastics, while the secondary stage uses solid spiral wound polypropylene.
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