Improvement in steam stripping of sour water through an industrial-scale simulation

Abstract

Sour water containing hydrogen sulfide, carbon dioxide, hydrogen cyanide, and ammonia is mainly purified by steam stripping. Increased concern in recent times over effluent water quality and energy saving has caused sour water stripping to attract considerable attention. However, the development of the operation methodology and structure of this process has not been systemic, leading to inefficiencies in the systems commonly used. In this paper, the characteristics of a sour water stripping column are investigated by using an industrial-scale simulation. From these results, we propose several guidelines (high feed temperature, low composition of CO2 in the feed, need of rectifying section, low mass flow rate of the second recycle stream, high reflux ratio, and modified structure using a pump-around side cooler) for improving stripper performance through changes in the operating condition and process structure. The proposed structure and guidelines can be applied not only to reduce steam consumption and lower the ammonia concentration in the effluent water but also to operate the system stably.