The third unit consists of solvent regeneration unit, acid water stripping unit and sulfur recovery unit. The commissioning of the unit can not only effectively reduce the sulfur content in the oil and meet the requirements of higher standard gasoline, but also the quality of solid sulfur produced by the unit can fully meet the requirements of gb2449-2006 grade I product index, so as to achieve a win-win situation of environmental protection and economic benefits. A total of 44 low voltage capacitors, reactors and controllers of Hertz brand are used.