SU1762963A1 - Equipment for foam breaking - Google Patents

Abstract

The invention: the device includes a housing, a vertical shaft in which the blades are mounted. An apparatus is installed on the casing, into the upper part of which superheated steam is supplied, and the aerosol formed is directed into the liner, under which the grid with apertures of 1.5-3.0 mm is located. The upper end of the mesh is attached to the Laval nozzle, and the lower one is installed at a distance of 0.3-0.5 nozzle lengths, the jet opening angle in the Laval nozzle being more than 15 °. 3 il.

Description

The invention relates to devices for the destruction of technological and other types of foam before it is supplied to dewatering devices, such as vacuum filters or thickeners, and can be used in mineral processing.

The purpose of the invention is to increase the efficiency of the defoaming process. The goal is achieved by installing an aerosol supply of reagents in the defoaming device on the body, the upper part of which is supplied with superheated steam, which at the entrance to the apparatus is dissected into separate jets and sucks the reagent, and when the resulting aerosol is released it goes to the liner under which there is a grid with openings of 1.5-3.0 mm, the upper end of which is attached directly to the Laval nozzle, and the lower one is installed at a distance of 0.3-0.5 the length of the nozzle, and the jet opening angle in the nozzle is more than 15 °

FIG. 1 shows a device for defoaming, FIG. 2, node A of FIG. 1, on

figure 3 is a section along BB figure 2.

The device includes a housing 1, an inlet nozzle 2, a nozzle 3 for pulp removal, a conical mesh insert 4, a vertical shaft 5, discs 6, perforated vanes 7, a drive pulley 8, an electric motor 9 supporting a partition 10, a differential valve 11, seals 12, vanes 13 , gland 14, thrust bearing 15, a lumen 16 between the blades 7 and 13, a pipeline for supplying superheated steam 17, thresholds 18, made with a cut 19 to the axis of the chamber 20 and with longitudinal slots 21, a pipeline for supplying reagents 22 with branches 23 , 24, liner 25 with swirl chamber 26 and through hole 27, Laval nozzle 28, grid 29, with attachments at points C and D, lower part (diffuser) of Laval nozzle 30, angle a - opening angle of the jet 31, (diffuser Lawal 30 nozzle)

with

Vi o

yoo you

Lena 32 of the apparatus for the aerosol supply of reagents to the housing 1.

The device works as follows.

The frothy product from the flotation machine or the collections along the inlet nozzle 2 is tangentially introduced into the inside of the insert 4 of conical shape with mesh walls and is evenly distributed throughout the whole volume. Since the insert has mesh walls, part of the air bubbles under the action of friction forces on the surface and centrifugal forces destroys and the liquid goes under the grid, and the components of the solid phase that were kept on the surface of the air bubbles, slide along the surface of the grid (from top to bottom) and through the holes also fall down the housing 1.

Inertia and centrifugal forces act on the foam product, which are transmitted to air bubbles from perforated blades 7, 13 mounted on disk 6.

Strengthened on the disk b and driven by the vertical shaft 5 through the drive pulley 8 from the electric motor 9, the blades are rigidly mounted on the disk, do not change their position and discharge the solid that is formed after the destruction of the frothy product.

Under the action of centrifugal and inertial forces in the defoaming device, the foam was partially quenched, but as a result of the constant action of water currents in the direction of the thickened areas, the same water is sucked into them. Thus, the rupture of the bubbles and the degree of their destruction begins to be affected by the Gibbs pressure, the capillary pressure, the value of which is determined from the equation:

2sgzh-g

R

(one)

where P is the capillary pressure;

Og – g is the magnitude of the surface tension at the liquid – gas interface;

g is the radius of curvature of the bubble surface.

It is possible to increase the defoaming efficiency if water is not absorbed in the direction of the water intake section, which increases the stability of the flotation foam. To reduce the capillary pressure inside the so-called. Gibbs triangle, it is necessary to introduce some kind of reagent or aerosol into the liquid phase. For this purpose, in the apparatus for aerosol supply of reagent, superheated steam is supplied through nozzle 17, which passage through thresholds 18 made with cut 19 to the axis of chamber 20, with longitudinal slots 21 in the reagent inlet section from pipe 23 creates a section with reduced speed of movement of superheated steam, which creates the necessary conditions for mixing the reagent with superheated steam. Superheated steam, mixed with the introduced reagent and being in the state of separate jets, is directed to the vortex chamber 26 located in the liner 25, and the aerosol formed from the vortex chamber 26 enters the passage opening 27 and further to the grid 29 located at the top5 The parts of the Lawal 28 nozzle and attached to it with the help of special plugs B and G. The aerosol, along with superheated steam, passed through the grid 29, is directed to the lower part of the Lawal 30 nozzle, where it is even stronger

0 is enriched with reagent supplied to the nozzle using pipelines 24, 22. The prepared aerosol (process aerosol) leaves the Laval nozzle with a jet opening angle of more than 15 ° into the device

5 defoaming the top cover that secures the aerosol reagent supply unit with a bolt 32. Adjusting the degree of mixing of superheated steam with a reagent that is sucked from pipe 23 is made by screwing in and unscrewing the insert 25 through a thread.

With excessive pressure (or vacuum) the differential valve 11 opens in the device and the air escapes into the atmosphere. On a laboratory stand, tests of the operability of the defoamer were carried out, with the determination of the effectiveness of the defoaming, with the contact of flotation pulp with an aerosol of reagents prepared from superheated steam and kerosene. The analysis shows that the installation is operational, the load on the flotation pulp corresponds to a load of 5 aerosols on the apparatus, the consumption of the aerosol is 0.2-0.3 m3 / m3 of the flotation pulp. In the apparatus it is possible to obtain an aerosol with a particle size of up to 2 µm to 60-70%. Contacting the aerosol with air bubbles leads to their instantaneous destruction. The table shows the effectiveness of quenching the foam mass, processed in the device for defoaming. On the effectiveness of defoaming

5 is influenced by the distance of the mesh fixation in the Laval nozzle, the diameter of the mesh holes, and the opening angle of the jet at the exit of the Laval nozzle.

The effectiveness of defoaming when processing foam in the device for defoaming

75.9-84.5% versus 63.1-72.2% for the prototype. The following can be an explanation of the observed effect of defoaming. At the moment when the defrosting action on the surface of the film is max, and this occurs when the currents of water in the direction of the thickened areas have reached the limiting value and water should be sucked into them, at this time heated aerosol is supplied to housing 1, which tends to precipitate Upon encountering a film on its way, it is instantly adsorbed by it. If r (formula 1) is too small, then pressure P increases to such an extent that the gases of the bubble (in accordance with Henry's law) are again dissolved. The condition for the disturbance of the steady state of the bubble nucleus is that the gas pressure inside the bubbles must be greater than the external gas pressure at which the liquid is saturated. Since in our case the process of aerosol formation occurs under the influence of superheated steam and the lower phase of the reagent is superheated steam, then at the moment of contact with the foam film, the condition of breaking of foam stability occurs. So, for example, foam stability is at the level of 181-191 sec, (gr.11) in case of foam quenching in the prototype and absolutely different stability when quenching it during operation of the proposed apparatus. In this case, the foam stability is 104-169 sec.

reaching the optimum value (104-117 sec. gr. 9) at the optimum value of the apparatus parameters: the jet opening angle, the diameter of the holes on the grid, the distance of the grid attachment. At the same time, the efficiency of defoaming reaches the optimum value - 75.9-84.5% (gr. 10).

Thus, in the device for defoaming, at optimal values of the parameters: the grid attachment distance is 0.3-0.5 the length of the nozzle, the diameter of the holes on the grid is 1.5-3.0 mm and the opening angle of the jet in the nozzle is more than 15 ° achieve effective defoaming.

Claims (1)

The invention The device for defoaming, including a housing with an inlet pipe, a differential valve, a vertical shaft, external perforated and internal blades, characterized in that, in order to increase the efficiency of damping the foam, the device is equipped with a vertical apparatus for supplying superheated steam mounted on the housing and provided in the upper part with thresholds with a cut and longitudinal slits under which the pipeline is installed for supplying the reagent, liner, inclined mesh with openings of 1.5-3.0 mm and sop of Laval, the upper end grid fixed to Laval nozzle, the lower end installed at a distance of 0.3-0.5 Nozzle length and opening angle of the diffuser Laval nozzle over 15 °. The results of the observation of the installation of defoaming v (( , - / BT / DA rotated ft-ft ot : lgashhashgash 19 I G1 FIG. 2  21 Fig.Z