Modeling of an integrated H2S/NH3 scrubber and regeneration columns for coke oven gas purification

Abstract

A model of an industrial coke oven gas absorption/stripping process for hydrogen sulfide and ammonia removal is developed. Three scrubbing liquids, weak and strong ammoniacal water produced by the strippers and sodium hydroxide solution, are used in the scrubber. Rate-based modeling is used for both the scrubber and the strippers. The model can accurately predict hydrogen sulfide and ammonia concentration in vapor sampled from multiple locations in the scrubber. The effects of the scrubbing liquid flow rates on the scrubbing efficiency is studied with a sensitivity analysis. It is found that increasing the flow rate of strong ammoniacal water can improve the hydrogen sulfide scrubbing efficiency. Increasing the flow rate of weak ammoniacal water can enhance both hydrogen sulfide and ammonia scrubbing efficiency. However, the pH of the wastewater produced by the process also increases, which may adversely affect the wastewater treatment process. Using more sodium hydroxide solution can effectively enhance hydrogen sulfide scrubbing efficiency, but its effect on the pH of the wastewater is profound. These results can provide guidance for improved operation of this process and similar processes.