During the production of dinitrotoluene(DNT),the synthesized DNT contains a small amount of phenolic salt,and the removal of phenolic salt impurities directly determines the purity of DNT.In order to fur-ther improve the quality of DNT products and reduce the phenolic salt content,it is urgent to further improve the removal efficiency of the washing process.Through two experiments,it is proved that the DNT raw material washed by raw washing tower could reduce its phenolic salt content to different degrees by further washing,in-dicating that there was still room for transformation of the raw washing tower.Through multistage countercur-rent extraction and multistage cross-flow extraction,the phenolic salt content met the separation requirements.Multistage cross-flow extraction required fewer theoretical boards and lower cost,and the theoretical series of cross-flow extraction was determined to be four.Based on the experimental results,through flow simulation and material balance analysis,the final phenol salt content was reduced to 1.13×10-5.For the existing water washing tower,the improvement scheme was that the tower diameter and the original tower of 1 100 mm,the tower spacing of 450 mm,the reserved space for flange of 500 mm,and the final tower section of 5 000 mm was needed.
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