A CR CleanAir two-stage Jet-Venturi scrubber/packed tower system solved a number of hydrochloric acid (HCI) pollution problems for an Albany, Oregon, electronics company.
The Zirconium Extraction Div. of Teledyne Wah Chang produces high-quality reactor-grade zirconium and hafnium ozide using a chemical separation process, which produces silicon tetrachloride (SiCI4) as a byproduct.
This crude inorganic chemical is stored in a tank farm, processed into pure SiCI4 , and sold as a raw material to other chemical processors. As it comes into contact with moisture, the silicon tetrachloride generates hydrochloric acid (HCI) fumes.
EPA required the elimination of fugitive emissions. And the plant also needed a scrubber system to protect tank farm workers from potentially hazardous fumes that might escape.
A two-stage system-Model 18 x 18-66V Jet-Venturi Fume Scrubber/Separator unit and 48T-12H Packed Tower-from the Clean Air Group were selected for three reasons.
- It could handle the sticky gel formed when silicon tetrachloride decomposed in water
- It has a high liquid-to-gas ration that provides efficient gas scrubbing of HCI
- Any HCI that may escape is easily scrubbed by the packed tower.
For the second stage of the process, a scrubber material in the packed tower handles residual low concentrations of SiCI4 and HCI. It channels the gas flow upward, through a packed bed; the scrubbing liquid flows down by gravity over the packing.
The packing material had to be selected carefully to prevent solids plugging. Molded polypropylene loops, called Spiral Pac®, were used to obtain a maximum mass transfer area. Liquids and gases come in contact with inside and outside surfaces, preventing gel buildup and providing the high HCI scrubbing capacity.
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