Design and Optimisation of a Modular Industrial Air Scrubber Utilising Surfactant Absorption Technology

Abstract

A novel air scrubbing technology using a misting application and water additives has successfully demonstrated the capability of scrubbing H2S at a water treatment plant. The air scrubber design utilises a solution of potable water and a water additive that exploits chemical surfactant technology as the scrubbing agent. The air scrubber equipment is modular in design, so that its performance can be tailored to the application in the testing environment. The modularity aspect allows for customisation to benefit the technology in high and low pollutant concentrations and with a range of air volume flow rates. The design allows for retrofit in existing systems for air scrubbing, and can be used in series or parallel for increased flow rate and removal efficiency. The technology of surfactant induced absorption with water is able to be studied by the ability to vary the water flow rate to a rotary atomiser, and alter the exposure time of water droplets to polluted air streams over a range of air flow rates, of 5 seconds exposure and above. The testing site proved to be a challenging area to utilise for the research, with the fluctuating properties of the pollutant gas streams, the multiple gas species and by-products present, and changing environmental factors. The first test results of air scrubbing was observed at an air flow rate of 1000 m3 per hour, with 200 litres per hour of water and scrubbing additive at a concentration of 1.25%. The obtained absorption efficiency was 21.9%, where the polluted gas at the inlet had a concentration of H2S in excess of 2000 PPM. Further tests of the air scrubber resulted in removal efficiency performances of 55% where the inlet H2S concentration was at 500 PPM. The scrubbing additive was reduced to a 0.5% concentration into 200 litres per hour of water, and an air flow rate of 1000 m3 per hour. Despite the low H2S removal efficiency calculated in the testing of the design, considerable efficiency gains can be made by optimising several features. These would include improvements in sealing joints between parts in the modular design, improving the atomisation method and reaction chamber to further prolong the water droplet lifespan increasing absorption capacity, and research and testing to the effects on surfactant additives and concentrations for increased absorption efficiency. This project has shown promising results, highlighted areas for further analysis, and testing should be performed to further validate the efficacy of the technology and the design.