Study On The Batch Distillation Process With Reflux Section

The batch distillation is one of important separation methods in chemical industry.In recent years, people have made a lot of work on the batch distillation, especiallymany new operation modes and columns, many new models and methods ofcalculation about the batch distillation, and much progress has been gained. However,generally, the most new distillation modes are developed for specific separation tasks,so they have many shortcomings, such as, the poor commonality, more complicatedequipments, high investment, difficult operation and control, and so on.The control of reflux is one of most important operations in the distillationprocess and research, the policy providing reflux has much connection with the control.At present, most reflux polices are outside reflux, whose characteristic is intuitionaland precise when controlling flow rate, but those policies have many limitations, forexample, the lag is heavy when controlling reflux rate, the reflux ratio controlledpractically is usually larger than the required reflux ratio, the temperature of refluxliquid is usually below its boiling point, so the energy consumption for heating thereflux liquid is added. The inner reflux policy is often applied in petrochemicalindustry, although it can ameliorate some limitations of outside reflux policy, it needscomplex software control system, and the overall popularization is difficult. In order toeliminate these limitations, the inner reflux provided by reflux section Was adopted, theupper distillation section was changed into the reflux section with outside cooling, therising steam was partially condensed in reflux section as reflux liquid, the requiredreflux was controlled automatically by outside cooling agent. In the batch distillationwith reflux section, the unstable control was transferred into controlling thetemperature and flow rate of outside cooling agent from thermostat which had largebuffer capacity, and the stabilization were strongly raised, so it had explicitsignificance.According to the theory of batch distillation with reflux section, the effectseparating ordinary binary mixture, operation elasticity, and the simple simulationcalculation were researched by the clue of equipment evolution from small-scale tolarge-scale, the results showed that the new reflux policy had many advantages, suchas the stable top temperature and quality of product, the inner automatic adjustment of reflux, faster responding speed controlled by reflux, more simple operation and control,lower energy consumption, higher efficiency and so on. It also had the good applyingprospective in the batch distillation and the azeotropic distillation.