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Product Introduction

Distillation tower (packed tower) is a tower type gas-liquid contact device used for distillation. By utilizing the property that each component in the mixture has different volatility, that is, the vapor pressure of each component is different at the same temperature, the light components (low boiling substances) in the liquid phase are transferred to the gas phase, while the heavy components (high boiling substances) in the gas phase are transferred to the liquid phase, thus achieving the purpose of separation. Distillation tower is also a widely used mass and heat transfer device in laboratories and petrochemical production.

working principle

The distillation tower is supplied with two-phase contact between steam and liquid. The condenser located at the top of the tower partially condenses the steam, and some of the condensed liquid returns to the top of the tower as reflux liquid. The remaining distillate is the product at the top of the tower. The reboiler located at the bottom of the tower vaporizes a portion of the liquid, causing the vapor to rise along the tower and the remaining liquid to be used as the bottom product. The feed is added to the middle of the tower, and the liquid in the feed and the liquid from the upper tower section descend along the tower, while the vapor in the feed and the vapor from the lower tower section ascend along the tower. In the entire distillation tower, the vapor-liquid two phases are in countercurrent contact for interfacial mass transfer. The volatile components in the vapor phase enter the vapor phase, while the non-volatile components in the vapor phase transfer to the liquid phase. For those that do not form, as long as they are designed and operated properly, the distillate will be a high-purity volatile component and a high-purity non-volatile component. The tower section above the feed inlet is called the distillation section, which further concentrates the volatile components in the rising vapor; The tower section below the feed inlet is called the distillation section, which extracts volatile components from the descending liquid. The combination of two operations enables the complete separation of the two components in the liquid mixture, producing the required two products.

The key to achieving complete separation of liquid mixtures through distillation lies in the application of reflux. Reflux includes both the high concentration volatile component liquid at the top of the tower and the high concentration non-volatile component vapor at the bottom of the tower returning to the tower. The vapor-liquid reflux forms a counter current contact between the two phases, resulting in relatively pure single component products at both ends of the tower. The ratio of the amount of liquid refluxed into the tower at the top to the amount of product at the top is called, which is an important control parameter in distillation operations. Its variation affects the separation efficiency of distillation operations。