Structured packing improves wet scrubbing of airborne molecular contaminants in cleanroom make-up air units

Abstract

The use of wet scrubbing to remove airborne molecular contaminants in cleanroom make-up air units has economic benefits and good application prospects. Still, problems with this method include low removal efficiency and large water consumption. To improve scrubbing performance, we built a full-scale scrubbing experiment platform using SO2 as the removal object. In addition, we applied structured packing in the scrubbing process to enhance the mass transfer between gas and liquid, and we tested the wet scrubbing removal efficiency and pressure drop under a variety of operating conditions. Results showed that under the condition of double-row spraying only, the SO2 removal efficiency increased with increasing liquid-gas ratio. The efficiency ranged from 57% to 83.9% and the pressure drop ranged from 6 to 15 Pa. After adding structured packing, the removal efficiency under different liquid-gas ratios improved significantly. Improvement was more apparent, ranging from 72.2% to 86.2%, when the liquid-gas ratio was low. The pressure drop also increased, ranging between 59 Pa and 100 Pa. In addition, we changed the packing thickness and the number of stages, and found that when the packing thickness was 0.2 m and the two-stage spacing was 0.15 m, removal efficiency improved up to 89.7%. The research results are significant for optimizing wet scrubbing performance and, at the same time, have practical engineering value for controlling the concentration of airborne molecular contaminants in the cleanrooms.