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, especially many new operation modes and columns, many new models and methods of calculation 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 complicated equipments, high investment, difficult operation and control, and so on.The control of reflux is one of most important operations in the distillation process and research, the policy providing reflux has much connection with the control. At present, most reflux polices are outside reflux, whose characteristic is intuitional and precise when controlling flow rate, but those policies have many limitations, for example, the lag is heavy when controlling reflux rate, the reflux ratio controlled practically is usually larger than the required reflux ratio, the temperature of reflux liquid is usually below its boiling point, so the energy consumption for heating the reflux liquid is added. The inner reflux policy is often applied in petrochemical industry, although it can ameliorate some limitations of outside reflux policy, it needs complex software control system, and the overall popularization is difficult. In order to eliminate these limitations, the inner reflux provided by refluxsection was adopted, the upper distillation section was changed into the reflux section with outside cooling, the rising steam was partially condensed in reflux section as reflux liquid, the required reflux was controlled automatically by outside cooling agent. In the batch distillation with reflux section, the unstable control was transferred into controlling the temperature and flow rate of outside cooling agent from thermostat which had large buffer capacity, and the stabilization were strongly raised, so it had explicit significance.According to the theory of batch distillation with reflux section, the effect separating ordinary binary mixture, operation elasticity, and the simple simulation calculation were researched by the clue of equipment evolution from small-scale to large-scale, the results showed that the new reflux policy had many advantages, such as 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 applying prospective in the batch distillation and the azeotropic distillation.