RU2207901C2 - Centrifugal mixer - Google Patents

Abstract

FIELD: continuous preparation of mixtures; food-processing, chemical and other industries. SUBSTANCE: proposed centrifugal mixer includes vertical cylindrical housing provided with cover, loading and unloading branch pipes, receiving unit, guide and dispersing blades. Mixer is also provided with drive hollow shaft with ports; secured on said shaft one above other are rotors made in form of disks with hollow truncated cones mounted on them concentrically; height and angle of inclination of generatrix to base of said cones increase from central part to periphery. Construction of mixer includes availability of leading flows in the course of mixing, as well as mixing of finished mixture with new portion of initial component. Leading flows, as well as smooth and stable distribution of material are ensured by availability of ports in lower portion of inner and center cones of upper and lower rotors which at bounded at the bottom by surface of disk. Diluting is effected in proposed apparatus due to delivery of starting component to disk of lower rotor through drive shaft; thus mixture coming off upper rotor lays on new component. Solid rings and rings with holes provided above upper edges of cones are used as reflectors for forming additional crossing flows. EFFECT: intensification of mixing process; improved quality of mixture. 3 dwg

Description

 The invention relates to devices for continuous mixing of components with a large difference in their content in the mixture and can be used in food, chemical and other industries.

 A known mixer [1], comprising a cylindrical body with conical partitions having discharge windows, a vertical hollow shaft with conical rotors mounted on it in the form of conical plates located one above the other with central holes, a drive with a agitator, an accelerating device, loading and unloading nozzles. However, insufficient sparse flows and lack of recirculation does not allow to obtain high-quality mixtures, and the presence of a storage hopper with a agitator requires additional energy costs.

 A known mixer [2], comprising a vertical cylindrical body with loading and unloading nozzles, a receiving funnel, a drive shaft with unloading blades fixed to it and a rotor made in the form of a base with concentrically arranged hollow truncated cones with height and angle of inclination generatrix to the base increase from the central part to the periphery. Moreover, there are windows on the surfaces of the inner and middle cones through which part of the material moving along the inner conical surface enters the surface of the next cone in an advancing flow. In addition, a reflector is installed above the cones in the form of a volumetric spiral of Archimedes, which provides a partial return of material coming off the cone.

 When researching the operation of this mixer, its design flaws were revealed. Thus, the bypass windows of the inner and middle cones are arranged in such a way that they are bounded on all sides by a conical surface, as a result of which the material flow moving from bottom to top at the moment of descent from the bottom edge of the window has a speed that is tangential to the surface of the cone. This leads to the fact that part of the flow of material descended from the edge of the window, again falls on the surface of the subsequent cone above the window, not having time to slip into it. In addition, the lower parts of the surfaces of the middle and outer cones are not involved in the mixing process. In addition, the descent of the material from the surface of the reflector does not occur in a circle, but in a spiral line, which leads to an uneven distribution of the material over the surface of each cone.

 The purpose of the invention is the intensification of the mixing process of bulk components with a ratio of 1: 500 and above, increasing the smoothing ability of the mixer and, as a result, improving the quality of the resulting mixture. Achieving this goal is ensured by the fact that the preparation of the mixture in this apparatus is carried out according to the method of sequential dilution, which occurs due to the superposition of the flow of bulk material descended from the upper rotor onto the stream introduced through the hollow shaft to the base of the lower rotor. The goal is also achieved due to the presence of reflectors over the cones, which allow creating intersecting flows of material and directing the bulk mixture coming down from the cone to the base of the next one.

 Figure 1 shows a General view of a centrifugal mixer continuous operation with an indication of the direction of movement of the mixture in the apparatus; figure 2 shows a distribution diagram of the input stream spreading over the surface of the disk of the lower rotor; in FIG. 3 is a flow diagram of a flow coming off a cone.

 The mixer comprises a cylindrical housing 1, a cover 2 with loading nozzles 3, 4, a bottom 5 with an unloading nozzle 6. Inside the housing 1, in the bearing units 7 and 8, a vertical hollow shaft 9 with windows 10 is installed, which is also a loading nozzle for input the main component of the mixture. Over the upper and lower rotors are receiving and guiding devices 11 and 12, on the outer surface of which reflective rings are mounted (solid 21 and with windows 22). In this case, the cross-shaped vanes 13 are mounted on the hollow shaft between the fingers 14, fixed in the receiving and guiding device 11. Two conical rotors 15 and unloading vanes 16 are fixed on the hollow shaft 9. The rotor is a disk with three hollow truncated cones 17 mounted concentrically on it. 18 and 19, which are facing smaller bases down. The height and angle of inclination of the forming cones to their bases increase from the central part to the periphery. On the surfaces of the inner 17 and middle 18 cones there are windows 19 bounded from below by the surface of the rotor disk. The hollow shaft 9 is driven by a V-belt drive 23 from an electric motor 24.

 The mixer operates as follows.

 The initial components of the mixture are dispensed through the loading nozzles 3, 4 onto the cross-shaped vanes 13. Under the action of centrifugal inertia forces, the bulk material is thrown onto the inner surface of the receiving-guiding device 11, falling into the gap between the fingers 14. Then, the loosened and crushed components are uniformly poured onto the upper disk rotor through an annular gap between the outlet of the device 11 and the hollow shaft 9. Under the action of inertia forces, the particles of material move along the surface of the disk, while the relative to the latter and the cones are twisted in the direction opposite to the direction of rotation (figure 2). The bypass windows 20, bounded below by the surface of the disk, ensure that only part of the flow passes to the surface of the cone (inner 17), and the other through the windows 20 moves to the carpet cone (middle 18). The material stream that has reached it is again divided into two parts. One of them passes through the windows 20 and moves on, and the other goes to the surface of the second cone 18. The stream passing through the windows 20 enters the surface of the third (external 19) cone (see Fig. 2). Due to the fact that the windows 20 are limited from below by the surface of the disk, under certain conditions the throughput will be constant.

 The part of the input stream that has passed to the surface of the inner cone 17 moves along it from the bottom up, with the components being mixed. The stream reaching the first continuous reflective ring 21, under the action of inertia forces moves along its inner surface and is evenly poured onto the lower part of the subsequent cone. Here it is embedded in the stream that has switched to this cone from the disk. Further, the total flow moves along the surface of the second cone 18, reaches the second reflective ring, after passing through it, the material is evenly poured onto the third cone 19, being introduced into the flow that has passed to this cone from the lower rotor disk.

 After that, the flow under the action of centrifugal force is discharged to the receiving and guiding device 12, from where it is evenly, with a thin layer, poured onto the disk of the lower rotor, on which the mixture obtained, descended from the upper rotor, is superimposed on the flow of the initial component passing through the openings 10 of the hollow shaft 9 , i.e. the process of sequential dilution of the mixture. Further, under the action of inertia forces, the total mixture is evenly distributed over three cones, on which a similar process of mixing materials occurs, as on the cones of the upper rotor. The difference is that over each cone there are two reflective rings - a solid 21 and a ring with windows 22. The part of the input stream that has crossed to the surface of the inner cone 17 of the lower rotor moves along it from the bottom up, and the components are mixed. Material reaching the first reflective ring 22, in which there are windows, begins to slide along its inner surface. After some time, the mixture through the windows in the reflection ring 22 is directed to the second (solid) ring 21 (see figure 3) and intersects with the flow moving along its inner surface. Crossing streams creates additional mixing of components. The material that has reached the continuous reflective ring 21 slides along its inner surface and is evenly poured onto the lower part of the middle cone 18 of the lower rotor. A similar intersection of the flows of bulk materials occurs over the middle 18 and external 19 cones of the lower rotor. Since the material flows are rarefied, this contributes to the efficient mixing of the components and to the improvement of the smoothing ability of the mixer. After this, the mixture is discharged to the bottom of the mixer 5, from which the material is discharged using the discharge blades 16 through the discharge pipe 6. In this case, additional dispersion and mixing of the material occurs, which improves the quality of the finished composition.

 The intensification of the mixing process of bulk components with their subsequent dilution is achieved by dividing the input stream into several parts, then intersecting them and adding the original component to the mixture obtained on the upper cone, as well as by creating intersecting flows over the cones using reflective rings with windows.

Due to the organization of the advanced material flow and the process in thin rarefied layers, it is possible to:
- to achieve uniform specific loading of the cones of the rotor, which contributes to an equal thickness of the layer of material on them;
- to achieve that the mixing process occurs at the level of microvolumes and individual particles.

 The organization of mixing bulk materials with their subsequent dilution in a continuous mixer allows you to get high-quality mixtures with a ratio of components of 1: 500 and above in one mixing device.

Sources of information
1. A. p. SU 1278236 A1, B 28 C 5/16, 1982.

 2. Patent RU 2132725 C1, B 01 F 7/26, 1999.

Claims (1)

 A centrifugal mixer containing a vertical cylindrical body equipped with a cover, loading and unloading nozzles, a receiving and guiding device, a drive shaft with a rotor mounted on it in the form of a disk with hollow truncated cones concentrically mounted on it, in which the height and angle of inclination of the generators to the base increase from the central part to the periphery, characterized in that the drive shaft is made in the form of a long loading pipe with windows below, on which two rotors are located one above the other.

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