In August 2015, Nanjing Lushan Chemical Company built a 12-ton/hour waste sulfuric acid vacuum concentrating unit for the treatment of m-phenylenediamine in Zhejiang Longsheng Aluminium Chemicals Co., Ltd. Production of waste acid, the process does not need to add other chemicals, after 72 hours of continuous operation assessment, each ton of raw acid concentration treatment consumes 473kg of medium pressure steam, 27kg of low pressure steam, 3.5 degrees of electricity, the concentration of concentrated sulfuric acid is 88%, waste acid The recycling rate reached 99%, and the finished sulfuric acid after concentration treatment was all returned to the original process unit for recycling. The inspection and acceptance index of the whole set of equipment was better than the contract requirement. Currently, the device has been running continuously for more than 4 years.