Honeycomb wet scrubber for acidic gas control: modeling and long-term test results

A laboratory scale, 1.0 CMM (m³ min^{− 1}) wet scrubber packed with water-absorbing honeycomb material (HWS) with a very large geometric surface area of 480 m² m^{− 3} and a low pressure drop developed in our previous study was shown to achieve a very high removal efficiency for acidic gases but there were no long-term test data. In this study, the HWS scaled up to operate at a 100 CMM flow rate was tested for removing mixed acidic gases at a semiconductor fab for a very long period of 3.5 yr. Results showed that the removal efficiency for the mixed gases emitted from the fab always maintained as high as > 95% for HF, CH₃COOH, HCl, HNO₃, HNO₂, and H₂SO₄ with the inlet concentrations ranging from supper-ppmv to sub-ppmv, during a 3.5-yr period. With water jet cleaning of the honeycomb modules once per year, the pressure drop of the HWS remained to be low at 0.5–0.8 cm H₂O, indicating minimal scaling in the HWS. Additionally, the predicted height and removal efficiencies of the HWS were very close to the experimental data. The excellent long-term performance of the HWS warrants its potential applications in many areas in which liquid absorption is the preferred treatment method and the theoretical equations can facilitate the design of the HWS.