Improvement and optimization of sulfur recovery process and catalyst in a refinery

The 5 000 t/a sulfur recovery unit in the refinery of PetroChina Ningxia Petrochemical Company used two-stage Claus and low temperature hydrogenation-reduction absorption process before improvement. The hydrogenated tail gas was absorbed by MDEA. The mass concentration of SO₂ in flue gas was 500-800 mg/m³. The method of centralized regeneration was adopted in solvent regeneration system. Based on the design process provided by Research Institute of Natural Gas Technology(RINGT), PetroChina Southwest Oil & Gasfield Company, the refinery carried out a new technology improvement. The hydrolysis was enhanced by Ti-based catalyst which was developed by RINGT and two-stage absorption process was applied. The SO₂ mass concentration in flue gas from sulfur recovery unit was about 50 mg/m³ after improvement, which had met the discharge standard. The technology improvement could provide technical ideas and solutions for the tail gas up-to-standard discharge of the small-scale sulfur recovery units, especially for the factories which are difficult to treat lye and alkali residue.