Improving H2S removal in the coke oven gas purification process

Abstract

Coke oven gas is an important byproduct of the steel industry as it is used as an energy substitute for natural gas. However, coke gas contains impurities and must be treated before use. One of the steps of the treatment is the absorption process, wherein ammonia and hydrogen sulfide are removed. Considering the increasing use of coke oven gas and, in parallel, the strengthening of compliance with emission restrictions, it is extremely important to make the absorption process more efficient. This work consists of the development of a coke oven gas purification process model to evaluate solutions that would allow greater removal of hydrogen sulfide. The developed model was validated with data from an industrial plant, with errors of less than 6% for the most relevant variables. Among the three configurations tested, the best configuration represented a 5% increase in removal efficiency. This result is in line with scientific efforts in the search for environmentally responsible solutions. In addition, the improvement in the performance of this process allows for the use of coal with a higher sulfur content (responsible for generating hydrogen sulfide) at processes upstream of coke oven gas purification. Since coal with a higher sulfur content is cheaper and abundant, unlike low sulfur coal, an economic analysis was developed that allowed the financial impact of this modification to be quantified. The proposed modification resulted in a reduction of 15% of raw materials costs.