Benzoic Acid Purification System Simulation And Transformation

Many processes were used to refine benzoic acid. Each process has its advantages and disadvantages and can be used in different production conditions. Melt crystallization and extraction under supercritical condition are the suitable ways in small-scale or batch production .For industrial scale production, distillation is a more economical way. In this paper, benzoic acid refining distillation system with SNIA benzene liquid phase process was researched via simulation. The effect of theoretical tray numbers,operation pressure,reflux ratio,feeding position etc. on the purity of the product were investigated. Based on the simulation results, the process and equipment were modified. An extra distillation column was added; the operation pressure was reduced and the sieved tray in column 103 is replaced by tray with high separation efficiency and capacity; the sieved tray in column 104 was replaced by packing. Industrial experiments were carried out and the practical operation results were conformed to the simulation. The purity of benzoic is up to 99.5% under 140% production capacity, and it has made a good foundation for the separation of benzaldehyde and benzyl alcohol.The experiment result also showed that the top and bottom temperatures of benzoic acid distillation towers under normal pressure were decreased about 10℃ than that under high pressure. It effectively prevents the components from decomposing under high temperature. The energy consumption was greatly reduced and the corrosion of equipment under high temperature was decreased.The quality and capacity enlargement problems existed in Shijiazhuang Chemical Fiber Co., Ltd. Benzoic acid production were successfully solved by the development of this process and considerable economic and social benefit were gained.