Modeling gas transfer in a spray tower oxygen absorber

A computer model characterizing the performance of a spray tower oxygen absorption system was developed based on finite difference mass transfer calculations. Performance was assessed in terms of oxygen utilization, transfer efficiency, and economy. Pilot scale tests verified model assumptions and performance predictions. Simulation runs indicated spray tower head and oxygen feed requirements for desired changes in dissolved oxygen (DO) exceeded those required for packed column equipment. Spray tower performance was improved by increasing hydraulic loading from 35 to 85 kg m⁻² s⁻¹ and by increasing tower height from 1·25 to 2·50 m. The effluent DO concentration that minimized variable costs of oxygen transfer was lower in the spray tower than in the packed tower, indicating clean water use of the spray tower will be limited to moderate effluent DO requirement applications (DO <20 mg l⁻¹).