Gravity Distillation equipment manufacturers Introduces short distillation and its application

 

Short path distillation (short path distillation) is a continuous distillation process carried out in a separate operation under high vacuum. Under high vacuum conditions, due to the heating surface short distance distiller and condensed surface is less than or equal to the material to be separated molecular mean free path, when the film surface molecules in short distiller heating surface formed by evaporation, the intermolecular mutual collision does not occur, no hindrance to the movement of the condensing surface and is condensed in the condensation surface, and therefore short-path distillation is also called molecular distillation. Since the short path distillation under high vacuum to a temperature well below the boiling point, the distillation time is very short, so the process has become the most gentle separation of the desired product distillation process, especially suitable for concentrating, purifying or isolating high molecular weight, high boiling point, substances and poor thermal stability of high viscosity organic mixtures. Currently, short-path distillation has been successfully used in food, pharmaceuticals, fine chemicals and cosmetics and other industries.

Short path distillation process

1 shows a schematic diagram of the short path distillation, the distillation process is divided into the following five steps:

(1) heating the material in the liquid film formed on the surface: mechanically heated in retort to produce a fast-moving surface, a film of uniform thickness.

(2) molecule on the surface of the liquid film evaporation freedom: molecules under high vacuum well below the boiling point evaporated.

(3) molecular condensation from the heating surface facing the movement: just short distiller ensure a sufficiently high degree of vacuum evaporation so that the mean free path of molecules is greater than or equal to the distance between the heating surface and the condensation surface, the molecular motion to the condensation surface and evaporation process can be carried out rapidly.

(4) condensing surface molecules flutter eligible: as long as reached between the heating surface and the condensing surface temperature sufficient difference, reasonable shape and smooth surface condensation, light components will be condensed in the condensation surface, the process can be snap.

(5) to collect the distillate and residues of: by gravity, the distillate was collected in the bottom of the condenser. No evaporation of recombinant points and return to the little light component residue heated surface by gravity or centrifugal force, slipped to the bottom of the heater or dial rim.

The basic principle of the short path distillation

Molecular mean free path of molecular mean free path length is short distiller design a very important reference data is the average molecule in the collision between the two walked away. Only one molecule, the molecular mean free path is:

It exists only when two molecules, the molecular mean free path is:

(2) where, λ is the molecular mean free path, ηT is the viscosity of the liquid, p is the vapor pressure, T is the evaporation temperature, M is the molecular weight, d is the molecular diameter.

Langmuir evaporation rate and molecular studies of the phenomenon Knudsen evaporation under high vacuum pure substance, derived from the theoretical vacuum in absolute freedom under surface evaporation rate per unit of time equal to the number of molecules per unit wall area of ​​occurrence of collision,

Chong Hing Chemical Equipment Co., Ltd. focus on gravity distillation equipment, gravity distillation machine production, the company's main products: efficient rotary distillation machine, sampler distillation, desulfurization equipment, sewage treatment equipment (saline waste water treatment) all kinds of stainless steel reactor, heat exchangers, condensers, solvent efficient separation device, retorts, continuous centrifuge.

 

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