SU382907A1 - METHOD OF CONDENSATION OF A MIXTURE OF VAPORS CONTAINING CRYSTALLINE SUBSTANCES - Google Patents

Description

one

The invention relates to the technology of organic ositic sietes and concerns the condensation of vapors of crystallizing substances.

Chemical technology uses capacitors of various types; bubbling, irrigating, surface, for example shell-and-tube, etc. However, none of the known condensers can be used to condense vapors of crystallizing substances (KB) in continuous production (for example, rectification), since condensate is a solid substance. To ensure the mobility of the condensate KB, appropriate solvents are fed to the condensation stage in the form of vapor. The condensate obtained in this case is usually of low KV concentration.

The purpose of the invention is to develop a method for condensing a mixture of vapors containing KB and allowing to obtain condensate with a sufficiently high concentration of KB, eliminating the risk of crystals falling out on the heat exchange surface.

According to the proposed method, the vapor mixture containing KB, as well as a certain amount of a low boiling component (NCC) with a difference in boiling points between them of not less than 20 ° C, is produced in two stages, and in the first stage the condensation is carried out in a layer of KB solution, wherein the solvent is NCC, and in the second stage, the condensation of NCC with the complete return of the latter to the layer of the solution of the first 5 condensation stages. The ratio between the amount of NCC and KB in the vapor mixture is chosen so that the crystallization temperature of the KB solution in the NCC is not less than 4 M lower than the temperature (

0 condensation in the first stage. In turn, the condensation temperature, maintained by supplying the refrigerant to the condenser jacket, must be low enough to prevent significant quantities of KB from entering the second stage of condensation.

The ratio of the content of NCC and KB in the vapor above the layer of solution at a given condensation temperature of the first stage should be at least 20: 1. Therefore, the pairs entering into the second stage can condense in conventional shell-and-tube devices at sufficiently low temperatures, ensuring complete NCC condensation. The melting point of NKK should be below

condensation temperature of the second stage. Selection of KB is carried out in the form of a liquid from a layer of a solution formed as a result of condensation of nars in the first stage, with the release of KB from a solution by distillation, distillation, crystallization, etc.

In the absence of a sufficient amount of NCC in the vapor mixture, the latter is introduced specifically in accordance with the requirements outlined above. In the first stage, bubbling or irrigation reflux condensers can be used as KaHiAeHcaTOipOB.

The drawing schematically shows the principle of operation of the proposed method for condensing a vapor mixture containing a CV.

Example. The distillation column 1 serves the mixture in the amount of 100 kg / h, containing 35 kg of perchlorethylene (C2Cl4), 35 kg of hexachloroethane {C2Clb), 30 kg of hexachlorobutadiene (Cl4Cl). A mixture of vapors, containing a crystallizing substance — hexachloroethane and a low-kink component — perchlorethylene in a 1: 1 ratio, enters condensation in a bubble reflux condenser 3 through a helmet tube 2. -100 mm. Bubble dephlegmator 3 has heat-exchanging surfaces for removing heat, cooled by water. The melting point of the solution in a reflux condenser 3 with a 1: 1 ratio of perchloroethane and hexachloroethane is 50 ° C. The composition of the vapors leaving the bubble reflux condenser 5 is determined by the vapor pressure of the pure components at a condensation temperature of 55 ° C maintained by cooling water.

CjCU 80 - Rtst, 3.5 mm Hg. st,

t 55 ° C; , Cu ((l -),. 5-80) 0.5-3.5

 23 20;

X 0,5 - the content of perchlorethylene in solution.

The vapor from the bubbling reflux condenser 3 through LINE 4 enters the shell-and-tube reflux condenser 5, cooled with water. The condensing temperature of the second stage is not higher than 20 ° C, which ensures complete condensation of perchlorethylene. Since hexachloroethane is less than 5% in bunkers, its condensation in a shell-and-tube reflux condenser is not difficult from the point of view of overgrowing with crystals. The condensate from the deflectator 5 completely returns to the bubbling reflux condenser 3, thanks to which

the desired ratio in solution between perchlorethylene and hexachloroethane is maintained at 1: 1.

Excess fluid through the overflow pipe 6 flows from the top of the bubbling

reflux condenser 3 and is divided into reflux, returned to the distillation column, for irrigation and selection, in an amount of 70 kg / h, consisting of 35 kg of perchlorethylene, 35 kg of hexachloroethane and traces of hexachlorobutadiene.

Selection is directed to the isolation of hexachloroethane by rectification. Separating the crystallizing component from the NCC using rectification or distillation is not difficult from the point of view

crystal clogging hazards during condensation. Hexachlorobutadiene in the amount of 30 kg / h is removed from the boiler 7.

Subject invention

A method of condensing a vapor mixture containing crystallizing substances in the presence of a solvent, characterized in that, in order to prevent crystals from falling out on the heat exchange surfaces and to obtain a condensate with a high concentration of the crystallizing substance, the condensation is carried out in two stages, and in the first stage a mixture of vapor, containing a low boiling point component and crystallizing substances, condense in a layer of a solution of crystallizing substances and a low peeling component, where the latter is a solvent And a second step - is condensed only pairs of a low boiling component having a complete return of the latter in the layer of the first stage solution.