SU1673150A1 - Method of continuous isohydrous crystallization - Google Patents

Abstract

The invention relates to methods of isohydric crystallization of substances from solutions and can be used in microbiological, pharmaceutical and chemical, food, chemical and other industries, to obtain high-purity crystalline products. The invention allows to obtain large crystals of a narrow particle size fraction and to reduce energy consumption by providing hydro-mixing and creating the optimum temperature conditions of the process. This is achieved by the fact that in the method of continuous isohydric crystallization, which includes heating the initial mixture with a coolant, multi-stage crystallization with separation of the flows, cooling the mixture at each step with the same coolant with decreasing temperature from step to step, at each step separates the flow with large crystals. t tangentially in the upper part of the subsequent crystallizer of the subsequent stage and the flow with small crystals, obtained in the first stage, is heated, and from subsequent ones it returns dissolved in the lower part of the mold of the previous stage. The heat carrier discharged after the first crystallization stage and released after the initial mixture is heated is directed to the heat pump, and then returned to the process. 1 hp f-ly, 1 ill.

Description

The invention relates to methods of isohydric crystallization of substances from solutions and can be used in microbiological, pharmaceutical and chemical, food, chemical and other industries to obtain high-purity crystalline products.

The purpose of the invention is to obtain large crystals of a narrow particle size fraction and reduce energy consumption by

providing hydro-mixing and creating the optimum temperature of the process.

The drawing shows a schematic diagram of an installation that implements this method.

The installation, in which the isohydric crystallization method is carried out, contains a tank 1 for dissolving the initial mass, equipped with a jacket 2, heat carriers, a series of capacitive crystallizers 3 s.

ABOUT

sj

CJ

ate about

jackets A for cooling, a capacitive crystallizer 5 of the last crystallization stage, equipped with a cooling jacket 6, is connected to a device for selecting production crystallizers 7. Crystallizers 3 and 5 are connected between each other by the feedback and feedback by means of pipelines 8 in such a way that the pipelines 8 connect The capacitive crystallizer 5 with the lower part of the crystallizer 3 is installed. The installation also includes a cooling-heating system consisting of a coolant collector 9 connected to the jacket 6 of the crystallizer 5 using pipes wires 10c by a heat pump 11, which consists of a compressor 12 and an expansion machine 13. The compressor 12 is connected via a pipeline to the cooling jacket exit and a first stage capacitive crystallizer and to the entrance of the jacket 2 of tank 1. The expansion machine 13 is connected via a pipeline with the output of the jacket 2 of the tank 1 and through the valve 14 — with the coolant collector; The capacitive crystallizer 3 (or 5) of each stage is provided with a nozzle 15 for tangential VEUDE flows.

The method is carried out as follows.

The initial mixture is fed into the tank 1 tangentially for mixing, where the crystals completely dissolve. The tangential flow inlet ensures that the apparatus is mixed by mixing, the high temperature of the initial mixture is maintained due to the transfer of crystallized heat to the solution. From the bottom of the tank 1, the resulting mixture is fed into the capacitive mold 3 tangentially to its upper part. The crystals formed are fed to the lower part of this crystallizer 3. In the lower part of the crystallizer 3, the formed suspension of crystals is divided into two streams, one of which, containing small crystals, returns to the lower part of tank 1, another stream containing larger crystals, served tangentially to the next crystallization stage in the capacitive crystallizer 5. At each crystallization stage, the cycle repeats, but at a lower temperature. Pure large crystals of a narrow particle size fraction drip from the bottom of the mold 5 and through a device for selecting production crystals they are removed from the plant. Part of the mother liquor is returned to the process in a capacitive crystallizer 5 of the last crystallization stage.

The heat energy of the isohydric crystallization process is utilized by cooling the crystallized mixture with a coolant circulating in cooling shirts 4 and 6 of crystallizers 3 and 5. Initially, the coolant enters the crystallizer 5 of the last stage, then passes successively through all the crystallizers 3, including the crystallizer 3 of the first stage, and absorbs the discharge warmth. Changing their physical condition under the influence of the compressor 12 of the heat pump 11, the coolant transfers the energy of the mixture in the tank 1, the spent coolant, changes its physical state under the influence of the expansion machine 13 of the heat pump 11, flows through the valve 14 into the collection 10. Others are possible heating and cooling circuits.

Carrying out the process, including the flow into the mixing zone of a colder flow, improves heat transfer during crystallization from solution, and washing growing crystals that are in a suspended state with a more thermal solution with even washing of their faces creates conditions for the growth of cleaner crystals. . The mixing zone is created due to the tangential introduction of the flow into the crystallizer and ensures uniform mixing of the mixture in its upper part. The utilization of crystallization heat and its use in the process also reduces energy costs.

Claims (2)

1. A method of continuous isohydric crystallization, including heating the initial mixture with a coolant, multi-stage crystallization with separation of flows in crystallizers, cooling the mixture at each step as well as a coolant with decreasing temperature from step to crystallization step and separating production crystals by separating the mother liquor, characterized in that the purpose of obtaining large crystals of a narrow particle size fraction and reducing energy consumption by ensuring hydro-mixing and creating at each stage of crystallization during the separation of flows, a stream with large crystals is removed, output from the lower part of the crystallizer, which is introduced tangentially into the upper part of the subsequent crystallizer, and a stream with small crystals, output from the crystallizer is higher than the flow with large crystals, which at the first stage of crystallization are mixed with the initial mixture, and from subsequent stages of crystallization return to the lower part of the crystallizer of the previous stage, and When selecting productional crystal mother liquor is recycled to the bottom of the last stage of crystallization. 2. A method according to claim 1. wherein the coolant after the first crystallization stage and leaving the initial mixture after heating is directed to a heat pump, after which it is returned to the heating of the initial mixture and cooling the crystallizers, respectively. V / X /, 12 / 51 ; 15 ex. mixture u Yi 33-