Used 20,000 TPY Maleic Anhydride plant built in 2012 for sale. The plant uses benzene as raw material. The process air from the blower is heated to about 165-170 ° C and enters the vaporizer. The liquid benzene also enters the vaporizer. The liquid benzene is vaporized in the vaporizer and mixed with the air evenly. After mixing, the gas mixture at about 153 ~ 158 ? passes through the catalyst bed from the upper part of the reactor. The temperature is controlled at 420 ~ 450 °C. Reactant gas containing maleic anhydride flows out at the lower part of the reactor at around 370 ° and is cooled by a gas cooler to 140 ° C. After the cooler, it enters the aftercooler and is cooled further to 60 ~ 65 ? by 54 ? by temper water. The maleic anhydride gas entering at the bottom of the absorption tower is absorbed by the circulating acid water and becomes an aqueous maleic acid solution. The maleic acid aqueous solution is metered and sent to the refining tower for dehydration. It is fed into the refining tower with o-xylene gas for azeotrope boiling. When maintaining top the pressure of the tower to be at 20 KPa (A), the main distillate, liquid maleic anhydride, is produced. The plant has DCS control system.