SU8364A1 - Urea Production Method - Google Patents

Description

Usually, methods of urea synthesis have been used up to now in practice to reduce the interaction of ammonia and carbonic acid in autoclaves under high pressure, or to inject under high pressure these gases that have been pre-converted into liquid. These types of urea production require complex, costly equipment that takes up a lot of space.

In the proposed method, in order to simplify the technical preparation of urea, it is based on the well-known phenomenon of creating high pressure during the distillation in a closed space of volatile substances. A new method is as follows: a saturated solution of ammonium carbonate or carbamate acid is injected into the column withstanding high pressure, under high pressure and at high temperature (excess water hinders the formation of urea); The salts decomposing under the influence of the above factors form gases, ammonia and carbonic acid, which are a source of increased pressure. The mixture of gases is directed to a refrigerator that withstands a considerable pressure, the temperature of which is kept within 0 ° - 150 degrees, which allow condensation, but not solidification, of the resulting alloy of salts. From the refrigerator, the fused mass is sent to an autoclave, where, at a temperature from, it is converted to urea.

The desired water content in the fused mass is easily achieved and maintained by appropriate adjustment of the temperature in the column and in the refrigerator. The outlet from the column is controlled by a valve so that only the used solution is released, but not the gas. With proper installation of the flow in the column, and.

at a proper temperature, a solution containing traces of gas may, upon re-saturation with ammonia and carbonic acid, serve as a material for injecting said gases into the column. The filling and emptying of the autoclave can be carried out periodically or continuously; It is also possible, instead of a continuously operating column, to use a high-pressure boiler, with the help of which it can be distilled. The urea containing alloyed mass is processed in the usual way; The ammonia and carbon dioxide, which are not embedded in the reaction, are released in the course to saturate the solution discharged from the column. Thus, a circular process is established, whereby the compression of gases is replaced by distillation under pressure.

It is also possible to substitute the solution of the carbonic ammonium salt with the ammonia and carbon dioxide required for the reaction, the solutions of which are then distilled under pressure in two separate columns; chasing away, or joining together before

transfer to the refrigerator, or separately cool, and then join together before passing to the autoclave, or in the autoclave itself. For example, it is possible to get ammonia by distillation under pressure from raw ammonia water, and carbon dioxide from solutions of acid carbonate salts of sodium or ammonium, or to obtain carbon dioxide by other known methods, or, for example, one of the reactive bodies ammonia can be introduced into the autoclave by distillation of water. its solution under pressure, and the other, carbon dioxide, in a compressed state.

The subject of the patent.

The method of producing urea from ammonia and carbon dioxide by heating under pressure, characterized in that the pressure required to mix the ingredients of the mixture is obtained by distillation under pressure of aqueous solutions of one or both components separately or together.