Separation And Energy-saving Analysis Of Dimethylacetamide Wastewater

Energy saving and environmental protection have always been significant research subjects for industrial process.The main target of industrial process is to obtain pure product.And pay little attention to other factors like wastewater recycle,energy consumption calculation and equipment utilization.As we all know,it is esstial to recycle the wastewater.And it is of great importance to minimize the energy consumption and cost.There is 5~15 wt%dimethylacetamide(DMAc)wastewater with little polymer in membrane production process.In my research,multi-distillation technology is used to recover the wastewater.Firstly,a small scale vacuum distillation process was set and the experiment was carried out with the raw material.Secondly,the countercurrent multi-distillation processes were established and the model of distillation cost was designed.Then the multi-effect distillation system was optimized by the response surface methodology.It was found that multi-effect distillation showed many advantages compare to other industrial methods.The vacuum distillation and rotary evaporation experiments were used to deal with the raw material,and high purity products were obtained.The multi effect distillation process was established based on separation process constraints and target.Through the calculated material and energy balance the reasonable overhead product formula was deduced.The model of distillation cost system was designed in detail,and the total operating cost(TAC)calculation model was gained.The response surface method is used to optimize the multi-effect process.For the 5 wt%DMAc wastewater recovery,the minimize TAC is four-effect distillation,1.069?10~6$,which is 55.1%less than that of conventional distillation.For the 15%DMAc wastewater recovery,the minimize TAC is three-effect distillation,1.058?10~6$,which is 50.9%less than that of conventional distillation.Additionally,the extraction process of 5 wt%DMAc wastewater was simulated and optimized,and the calculated TAC is 1.01?10~6$,which was nearly the same with four-effect distillation.However,the extraction process introduced a third component into the separation system,which increased the complexity of the operation.Therefore,the multi-effect distillation is optional for the DMAc wastewater recovery,and it can achieve the goal of saving energy and reducing equipment investment.