Abstract: A proprietary gas-liquid mixer was first applied in SRU of a refinery. The tail gas ultra-low emissions were achieved through sodium alkali wet flue gas desulfurization process. The concentration of SO2 in the clean gas is 10 - 25 mg / m3 with desulfurization rate of ≥95% in 0-120% of flue gas flow range. The technology can meet ultra-low emission for tail gas under the various operating conditions of SRU. GGH was first applied to tail gas ultra-low emission in domestic SRU，it enhances the flue gas temperature, reduces white mist effectively and solves the problem of sulfur dew point corrosion in flue gas pipelines and equipments. Meanwhile，GGH saves energy 4 950 MJ / h, decreases water 0.64 t/h and flue gas emission 840m3/h.

Key words: sulfur recovery, tail gas ultra-low emission, wet flue gas desulfurization, gas-liquid mixer, GGH, white mist