These scrubbers are installed directly at the point of use, in order to efficiently reduce the pollutant discharged of processing plants.
Specifically for CVD (chemical vapor deposition) processes, Wallstein has developed a process gas scrubber which treats highly concentrated process exhaust gas flows, refining it to reach the required emission limits. These scrubbers are a perfect solution for separation of chlorsilanes emitted in high concentrations during the epitaxy processes.
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A 4-stage epitaxy gas scrubber is optimal for process gas treatment. As the gas comes into contact with the cleaning agent at the entrance of the first stage of the device, an instant hydrolysis occurs, producing strongly adhesive reaction products (intermediates which continue to slowly react to SiO2). These are washed off by the wall film in the first stage of the scrubber.
The sediment accumulated at the gas inlet pipe at the head of the first stage is removed mechanically with a cleaning device. Flushing nozzles prevent foaming in the scrubbing solution.
Random packings in stages 2 and 4 ensure the compliance to the emission standards (chlorsilane, HCl).
The 3rd stage is a jetting stage to compensate the pressure loss in the scrubber.
The Wallstein epitaxy exhaust gas scrubber combines high degree of safety with long operating times. It conforms to the ATEX Directive 94/9/EC.
