Role of Toluene and Carbon Dioxide on Sulfur Recovery Efficiency in a Claus Process

Examination of the effect of toluene and carbon dioxide, accompanying acid gases (mainly H₂S) in the sulfur recovery process is very critical to determining optimum operating conditions for enhanced sulfur recovery. Experimental and simulation results presented here with the addition of different amounts of toluene or carbon dioxide/toluene mixtures to the H₂S gas stream provided direct quantification on the conversion efficiency. The results showed similar trends between the calculated and experimental data, which revealed a decrease in conversion efficiency with increase in toluene and carbon dioxide/toluene addition to the H₂S gas stream. The role of reactor operating temperature was also examined. The toluene addition increased the optimum reactor temperature for enhanced sulfur recovery, whereas presence of CO₂ reduced the optimum operating temperature. The presence of toluene and CO₂ in the acid gas stream directly affects the sulfur recovery efficiency by altering the optimum temperature of the reactor. These results reveal the importance of temperature and its excursion for enhanced sulfur recovery in a Claus process. Detailed results and analysis are presented in the paper.