Study On Separation Of Phenolic Compounds From Coal Tar Of Middle And Low Temperature

Coal resources are abundant in China,and the output of medium and low temperature coal tar is large.The medium and low temperature coal tar is rich in phenolic compounds.The phenolic compounds in the coal tar can be extracted by alkaline washing and extraction methods,but the extracted phenolic compounds are complex in composition and have not been rationally utilized.This article mainly studies the separation of phenolic compounds from Coal Tar of Middle and Low Temperature.The vapor-liquid equilibrium data of the three binary systems of phenol+p-cresol,phenol+2,5-xylenol,phenol+2,6-xylenol at 53.5 k Pa were measured using a Rose vapor-liquid equilibrium kettle.The measured data have passed the thermodynamic consistency test of the Herington area test and the Van Ness point test.The NRTL thermodynamic model is used to regress the phase equilibrium data,and the binary interaction parameters of the three sets of systems are obtained to provide theoretical data for process simulation of crude phenol refining process,which can be applied to the simulation calculation of continuous distillation and batch distillation of crude phenol refining.Using NRTL model of Aspen Plus software to simulate the continuous distillation of crude phenol extracted from the two phenol oils in Yulin and Northern Shanxi,respectively,simulating the conventional process used in the industry and the independently designed new process.The Aspen Plus software was used to analyze and optimize the sensitivity of the feed position,the recovery rate at the top of the tower,the reflux ratio and the number of theoretical plates.Under the conditions of the same product purity and recovery rate,the new process requires fewer theoretical plates and lower reflux ratio than the conventional process,and the total reboiler heat load is more than 10% lower.A batch distillation device is used to carry out a vacuum batch distillation experiment on the model crude phenol and real crude phenol.Using NRTL model of Aspen Plus software to simulate the batch distillation of the model crude phenol and real crude phenol,the results obtained are consistent with the experimental results,which proves the accuracy of the binary interaction parameters between the phenolic compounds,which can prove the simulation results of the crude phenol continuous distillation reliability.