Study On The Total-reflux Concentrating And No-reflux Withdrawing Process Of Batch Distillation

The total-reflux concentrating and no-reflux withdrawing process of batch distillation is a kind of new distillation mode. The differentiation of this process and traditional distillation process is that during the no-reflux process there is no reflux liquid which is necessary in the traditional distillation process. This operation method made a breakthrough in the reflux ratio theory of distillation. It can make good use of the advantage of total-reflux and no-reflux in concentrating and separating, respectively. Therefore the no-reflux operation is a very promising operation and can be applied widely.In this paper, the experimental study investigated a total-reflux concentrating and no-reflux withdrawing process of batch distillation. Three mixtures which have different relative volatilities, iso-propanol-n-propanol, alcohol-iso-propanol and methol-water, have been conducted at different feed composition. During the withdrawing stage, the temperature profiles and the concentration profile of the liquid phase along the column were measured. It can be seen from the data obtained that when the no-reflux withdrawing process started, the temperature of the column increased while the concentration of the light component decreased. The change at the top and body of the column is more dramatic than the one at the still during the first few minutes.This paper provided a simplified mode to simulate a total-reflux concentrating and no-reflux withdrawing process of batch distillation. Material balances of reboiler, trays, condenser were studied and the simulation was computed by using two-point implicit method andθcorrector method. The trends of concentration of top product with time and operating time with plate amount, relative volatility, hold-up, and vapour-liquid flow rate during total-reflux concentrating process were investigated. Comparison of model predictions of three mixtures with different relative volatilities with experimental results explicated the mixtures whose latent heat of vaporization were close had an agreeable results. The model was useful for the new distillation mode applying to industry.