The Tail Gas Treatment Unit (TGTU), as the final section of the sulfur recovery train, plays a vital role in reducing sulfur compound emissions and meeting environmental regulations. Despite numerous studies in this field, a comprehensive and systematic evaluation of the simultaneous effects of key operating parameters on TGTU performance and the identification of optimal operating points still presents a research gap. The main innovation of this study is the development of an integrated simulation–sensitivity analysis framework for the independent and interactive assessment of influential parameters on outlet gas composition and amine absorber performance in a TGTU, enabling quantitative prioritization of dominant control variables.

In this work, a complete TGTU model was developed using Aspen Plus software. The effects of key variables, including feed mass flow rate, H₂S/SO₂ stoichiometric ratio, hydrogen injection rate in the hydrogenation reactor, amine mass flow rate, and cold condensate make-up flow rate were systematically investigated. The results indicated that increasing the H₂S/SO₂ ratio led to a slight increase in the mass fractions of H₂S and CO₂ in the outlet gas, while SO₂ was reduced to negligible levels under most conditions due to effective hydrogenation reactions. Analysis of hydrogen injection revealed the existence of an optimal value at which SO₂ conversion was completed, and further hydrogen increase only resulted in energy loss and unreacted hydrogen in the outlet stream. Increasing the amine and cold condensate flow rates gradually improved absorption efficiency and reduced sulfur compound concentrations in the treated gas.