Process Research Of Recovery Of Tetrahydrofuran,N-butanol From The Industrial Wastewater

Vaper-phase 1,4-butanediol(BDO)dehydrogenation process is the most populous process of industrial production of ?-butyrolactone(GBL)in the world.But there will produce some by-products by the side reaction in the process.After the separation and purification of GBL in the process of production,the by-products will be pour out with the waste liquid.As many enterprises buring the waste liquid as a kind of fuel or sell the liquid at a very low price,the utilization rate is very low,and it may cause the pollution to the environment.The waste liquid which was produced by the method of vaper-phase 1,4-butanediol(BDO)dehydrogenation process in an enterprise in Henan is studied and analyzed.And it is contained of tetrahydrofuran(THF)?n-butyl alcohol(NBA)?water and small amounts of GBL,in which the THF and NBA both can form the azeotrope with water.So the components in waste liquid can not be separated by conventional distillation.The separation process is put forward in the study of the waste liquid.Then the method of separation is verified and optimized through simulation and experiment.The above-mentioned quaternary system was studied.The separation order and methods were determined according to the properties and sequence of the boiling points of the 4 components.Then 3 stages were determined in the whole separating process,which are extraction distillation,conventional distillation and azeotropic distillation.Finally,according to the relevant literatures and the properties of the components selects calculation method.The purification process for the separation of industrial wastewater have been simulated and optimized by Aspen Plus.The simulation results have proved the feasibility and the optimal operating parameters of purification process are calculated in theory.Under the conditions mentioned above,the recovery rate and purity of THF can reach 99.9% and 99.99%,respectively.The purity of NBA is 99.99% as well.Both of them reach the requirement of enterprise's standard.In the other hand,the water content of wastewater of the method is 99.79%,which reaches discharging standards completely.The correctness of the simulation and the feasibility of the process were verified by using confirmation experiments.Under the experiment conditions,the purity of THF is 98.97% after the experiments of extraction distillation,which has some deviations compared with the simulation.Based on the experiments of extraction distillation,the operating parameters were further optimized through orthogonal test.As a result,the optimal parameters are obtained under the condition of the experiments.According to problem of high energy consumption of the azeotropic distillation,the conception of dividing wall column(DWC)was introduced in the paper.And the separation of NBA and water were carried out in a home-made dividing wall column instrument,which proved its advantages to azeotropic distillation.