Introduction to the principle of distillation using double-layer glass reactors

Distillation is an evaporation and condensation process in which the vapor from the boiling of a liquid is introduced into a condenser tube to cool and condense into a liquid. So do you know what the principle of distillation is? Today, let's talk about the principle of distillation

The separation of a two-component mixture was analyzed as an example. After heating, the raw material liquid is partially vaporized, the volatile components are concentrated in the steam, and the highly non-volatile components are produced in the remaining liquid, which realizes the separation of the two to a certain extent.

The greater the difference between the volatile amounts of the two substances, the greater the concentration of the two substances. The industrial distillation device is used to directly contact the partially evaporated liquid phase with the partially condensed gas phase, so as to realize the partial evaporation of the liquid phase and the partial condensation of the gas phase, that is, the partial evaporation of the gas phase and the partial condensation of the gas phase. Partial condensation of the gas phase

The molecules of the liquid tend to spill over the surface due to molecular motion. This trend increases with increasing temperature. When a liquid is placed in a closed vacuum system, the molecules of the liquid will continuously escape and form vapors on the surface of the liquid. Then the molecules escape from the vapor, then the molecules escape from the vapor back into the liquid, and the vapor will maintain a certain pressure. At this point, the liquid surface is saturated, which is called saturated steam.

The pressure it exerts on the surface of the liquid is called the saturated vapor pressure. The results show that the saturated vapor pressure of the liquid is only related to the temperature, that is, the liquid has a certain vapor pressure at a certain temperature. It refers to the pressure at which a liquid is in equilibrium with its vapor, independent of the amount of liquid and vapor in the system

Heating a liquid until it boils, turning it into steam, then cooling the steam and condensing it into a liquid. The combined operation of these two processes is called distillation. Obviously, distillation can separate volatile and non-volatile substances, as well as mixed liquids of different boiling points. However, in order to obtain a good separation, the boiling points of the components in the mixture must be very different (at least above 30°C).

In atmospheric distillation, since the atmospheric pressure is usually not exactly 0.1MPa, strictly speaking, the boiling point plus the correction value should be observed. However, since the deviation is usually very small, even if the difference between atmospheric pressure and atmospheric pressure is 2.7kPa, the correction value is only about ±1°C, so it can be ignored.