SU1124996A2 - Vacuum crystallizer - Google Patents

Abstract

VACUUM CRYSTALLIZER on avt., Sv. No. 990252, characterized in that, in order to intensify the mass transfer process, increase the unit productivity and the size of the crystals, improve the uniformity and particle size distribution of the crystals by imposing pulsations on the interactive phases, further dispersing, mixing the solution and preventing incrustation of the walls, the evaporator is provided with free an additional disk with holes placed on the shaft — coaxial with the holes in the perforated disk and the lower ends fixed on it E elastic plates, the upper free ends of which are evenly spaced circumferentially in the gap ezhdu nozzles segner wheel and the walls of the evaporator. (L

Description

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The invention relates to the chemical and food industries I can be used to obtain crystalline substances from foaming, encrusting evaporator surfaces, as well as toxic solutions.

According to the main auth. No. 990252 is well-known for a vacuum crystallizer containing an evaporator with a segner wheel, a shaft and a perforated disk with padding plates, a crystal grower and an iasos, interconnected on the suction side, supply, drain and suction pipes, which are loosely mounted on the supply pipe.

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A disadvantage of the known vacuum crystallizer is the inefficient use of the energy imparted to the fluid by the pump. The hydraulic energy of the fluid introduced into the distributor head of the Segner wheel is used to rotate the perforated disk with plates in the solution (45%), the Segner wheel in the vapor phase (X20%), to overcome the hydraulic resistance of the hydraulic drive channels and nozzles. The remaining part of the input energy represents the kinetic energy of the liquid jets flowing from the nozzles. This part of the energy (xO3%) $ is mainly spent on hitting the inner surface of the body, which prevents the encrustation of the apparatus walls around the circumference at the point of impact of the jet, as well as on the spray of the solution and the jet destruction of the foam. Such use of the kinetic energy of the jets is not sufficiently effective for the crystallization process and to prevent incrustation of the apparatus walls. ,one.

The purpose of the invention is to intensify the mass transfer process, increase the specific productivity of the apparatus and the size of the crystals, improve the uniformity and particle size distribution of the crystals by imposing pulsations on the interacting phases, further dispersing, mixing the solution and preventing incrustation of the walls.

The goal is achieved by the fact that in the device the evaporator is provided with an additional disk freely placed on the shaft with holes coaxial with the holes in the perforated disk and lower ends fixed on it with elastic plates, the upper free ends of which are evenly circumferentially distributed in the gap between the nozzles of the wedge wheel and evaporator walls.

1 shows a schematic of the proposed device, a section; FIG. 2 shows a section A-A in FIG. 1.

The mold consists of a vacuum evaporator 1 containing a supply pipe 2, on which the Segner wheel 3 is freely mounted with nozzles 4 and the shaft 5, at its lower end a perforated disk is fixed. 6 with padding plates 7 and freely relative to the shaft, an additional disc 8 with elastic plates 9, a drain pipe 10, a crystal grower 11 having a soothing grille 12 and two drain connections 13 and 14 is placed. The padding plates 7 are arranged with a small clearance relative to the walls of the apparatus, their upper ends are attached to the disk 6, and the lower are interconnected. The elastic plates 9 have lower ends fixed on the additional disk 8, and the upper ends of the plates are free, uniformly arranged in the annular space between the nozzles 4 and the walls of the evaporator 1. The perforated 6 and additional 8 disks have symmetrically arranged holes or slots, are made with a minimum clearance relative to the walls the evaporator and placed with the landing slip relative to each other. The apparatus is provided with a circulation circuit including suction 15 and discharge 16 pipelines, a pump 17 and a port 18 for supplying the feed solution.

Vacuum crystallizer. Works as follows.

A closed circuit formed by the evaporator 1, the drain pipe 10, the crystal grower 11, the suction 15 and the discharge pipes 16, the pump 17 and the supply pipe 2 creates a circulation of the solution. The hot feed solution through pipe 18 is fed into the suction pipe 15 of pump 17, in which it mixes with the circulating mother liquor solution and together with it is thrown into the evaporator in the form of jets of nozzles. 4 segner wheels 3. The jet of solution flowing from the nozzles 4 produces periodic impacts on the free ends of the elastic plates 9. At the same time, the impact energy of the jets is spent partially on the dispersion of the solution, partially converted to the elastic energy of the plates 9, which is then spent on the vibrational mixing of the plant the thief. From the surface of the jets and droplets of a dispersed solution and,; em is intensive. evaporation, whereby the solution is cooled and in it creates supersaturation causing crystallization. Under the action of the reactive forces of the solution flowing out of the nozzles, the Segner wheel 3 rotates together with the perforated disk 6 and the padding plates 7. The solution streams leaving the nozzles together with the Segner wheel rotating in the direction opposite to the outlet of the jets produce jet and mechanical destruction of the foam. A rotating perforated disk 6 with padding plates 7 increases the residence time of crystals in the evaporator and prevents the formation of deposits on the walls of the conical part of the apparatus.

Under the action of blows of the jets of the solution on the flexible plates 9, the additional disk 8 begins to rotate with them at a low speed in the direction of the jets moving. The rotating elastic plates 9 perform additional mechanical mixing of the solution, intensifying the process and simultaneously preventing the formation of incrustations on the cylindrical surface evaporator. During the rotation of the disks 6 and 8 there is a periodic alignment of the holes or slots in them, through which the solution periodically enters the lower part of the evaporator. Since the upper additional disk B rotates at a low speed, the pulsation of the solution through contiguous holes in the disks takes place at different points around the circumference. The frequency of the pulsations and their amplitude is regulated by changing the area of the living cross section and the shape of the holes or slots in the additional disk 8 (one hole is shown in Figure 2: in the disks). The pulsation imparted to the solution in the evaporator is transferred to the same solution flowing through pipe 10 into the crystal grower 11, preventing incrustation on the walls of the drain pipe and washing out small crystals from

bottom of crystal grower. Production crystals are discharged from crystal grower 11 through pipe 13, and the mother liquor through pipe 14. To reduce turbulence in the mother liquor rising up through the crystal root and prevent entrainment through large core crystal 14 and the suction pipe 15 of the large crystals of the crystal grower 11 are provided with a soothing grate 1

The advantages of the proposed design in comparison with the known are as follows.

The installation in the evaporator of an additional free b disk mounted on the shaft with holes coaxial with the holes in the perforated disk and the lower ends of the elastic plates fixed on it allows pulsation of the solution through the holes aligned in the two disks. Due to the slow rotation of the additional disk, the alignment of the holes in the disks occurs at various points around the circumference, which will make it possible to evenly distribute the pulsations around the circumference. The pulsations imparted to the solution in the evaporator and the solution growing through the pipe in the crystal grower, together with the circulation, increase the relative speed of the crystals and the solution, which leads to washing off the faces of the crystals of the solution that has ceased to be peresisthennym, and replacing it with fresh supersaturated solution, which , in turn, leads to an intensification of mass transfer processes, and, consequently, to an increase in the unit's specific productivity, as well as crystal sizes, an improvement in homogeneity and grain size distribution. of their composition. Due to the periodic blows of the jets of the solution on the free ends of the elastic plates, the solution is further dispersed, leading to an increase in the evaporation surface, and, consequently, to additional cooling and supersaturation of the solution. The uniform oscillatory and mechanical mixing of the solution rotates with the additional disk elastic plates also intensifies the process of mass exchange, improves the homogeneity and granulometric composition of the crystals and prevents the formation of molds of the cylindrical surface

Claims (1)

VACUUM CRYSTALIZER by ed. St. No. 990252, characterized in that, in order to intensify the process of mass transfer, increase the specific productivity of the apparatus and the size of the crystals, improve the uniformity and particle size distribution of the crystals by applying pulsations to the interacting phases, additional dispersing, mixing the solution and preventing wall encrustation, the evaporator is equipped with a freely placed the shaft with an additional disk with holes, · 'coaxial with holes in perforated tsiska, and the lower ends fixed on it' elastic plates, the upper free ends of which are located evenly around the circumference in the gap between the nozzles of the Segner wheel and the walls of the evaporator. é ζ © С © © э 1 _