The Performance of a Spray Tower in Scrubbing H2S from Air

Abstract

Background and Objective: Hydrogen sulfide is a hazardous gas which is fatal at high concentrations. The application of a spray tower to remove H2S from air is the simplest and cheapest method but its performance is under question. In this study, the performance of a spray tower in removing H2S from air as well as its pressure loss across the bed were investigated.Material and Methods: In this study a spray tower was used to remove H2S from air. H2S was injected to the tower at the range of 0-30 ppm. The volumetric flow rate of water as the scrubbing liquid was 2 lit/min and spraying was carried out by a pump with 21-35 Kg/cm2 head. The volumetric flow rate of air was supplied through a fan in the range of 2400-3000 lit/min. The pressure loss across the bed was monitored by an inclined manometer. H2S concentrations in air were measured using direct reading device. The results were analyzed using SPSS version 16.Results: The minimum pressure loss, 73.81±0.2887 Pa, was obtained at 1200 lit/min air flow rate without scrubbing liquid injected to the tower. The maximum pressure loss, 292.84±2.448 Pa, was experienced at 3000 lit/min air flow rate with 2 lit/min of water flow injected to the tower. The maximum removal efficiency, 70.53±1.5415%, was experienced at 1800 lit/min of air flow rate along with 15 ppm of H2S injected to the tower. Minimum removal efficiency, 47.74±0.9295%, was gained at 3000 lit/min of air flow rate and 30 ppm of H2S injected to the tower. Statistical t-test revealed that there is a significant difference between H2S removal efficiency with air flow rate and inlet concentration, also between pressure drop with air flow rate and the presence of water (p<0.001).Conclusion: The removal efficiency of spray tower decreases by increasing the input flow rate and input concentration of H2S. The performance of water as a scrubbing liquid in spray tower is not satisfactory thus, the application of water plus chemical scrubbing liquids is strongly recommended to be studied.