RU2554578C2 - Mixer - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to machine building, particularly to mixers with vertical shaft for processing of aggressive, inflammable and toxic matters in a wide temperature range. This mixer comprises motor, shaft running in bearings inside the column. This shaft is secured at casing cover and engaged by one end with magnetic clutch. It differs from known design in that cup accommodating mixers is arranged at shaft opposite end. Note here that said shaft consists of one or more parts each being provided with bearing joints. Cup length complies with shaft length while mixers represent separable design.

EFFECT: higher reliability.

5 cl, 4 dwg

Description

The invention relates to mechanical engineering, to mixing devices with a vertical shaft for mixing various substances in a wide temperature range in the chemical, oil, pulp, food and other industries.

A mixing device for the fermenter is known, having a housing, an engine connected via a V-belt drive to an end magnetic coupling having a water-cooled screen, the driven coupling half of which is connected to the hollow shaft. There is a rod inside the shaft, which serves as a support with slide bearings mounted on the rod. The shaft sliding bearings are made of siliconized graphite, and their lubrication and cooling is carried out by condensate formed on the surface of the screen due to the temperature difference between the vapors of the mixed liquid and the water-cooled surface of the central part of the screen (A. Krasilnikov, “Features of the use of magnetic couplings in sealed machine designs” , Publishing and Publishing Department of GOU VPO "Ural State Technical University" - UPI, 2007, p. 122).

The disadvantages of this design are:

- low reliability: it is necessary to observe a certain temperature regime at which condensate will form on the lubrication of the bearings, i.e. the scope of the scheme in question is very limited;

- the complexity of the design due to the presence of a water-cooled screen and the need to fine-tune the gap in the magnetic coupling, which must be performed for the end magnetic couplings;

- when increasing the length of the shaft and the support rod, respectively, it is necessary to ensure the rigidity of the structure to significantly increase the diameter of the rod and the shaft rotating around it, which leads to an increase in mass and overall parameters;

- rolling bearings, in which the driving coupling half rotates, require maintenance (periodic lubrication), which increases operating costs.

V-belt transmission requires belt tension and periodic maintenance to replace them when wear is more than acceptable, which also increases the cost of operation and reduces the reliability of the device.

Known drive mixer, consisting of a housing with a platform for installing a drive motor, a coupling for transmitting torque from the motor shaft to the shaft of the mixing device. The rolling bearings on the shaft are mounted in a housing located at the top of the mixing device. The bearings of the shaft are radial ball bearings made of silicon nitride, behind which an mechanical seal is installed, which seals the shaft. Both bearing units are mounted above the housing cover, i.e. do not contact directly with the mixed medium, but work in pairs of the mixed medium. The mixing body of the device is mounted on the shaft cantilever. (Page from the catalog of the company OJSC Sumy NPO named after MV Frunze (Ukraine)).

The disadvantages of this design are: the large dimensions of the outer part of the mixing device, due to the spacing of the supports of the cantilever shaft, and, as a consequence, the large mass of the device, and since with the cantilever mounting scheme the lower bearing is far enough from the lower end of the shaft, large bending load, which limits the possible shaft length or requires a substantial increase in its diameter to ensure rigidity and the absence of increased shaft precession (affecting normal mechanical seal and bearings), high cost of special rolling bearings made of silicon nitride.

A known mixer with active pneumodynamic protection of the support node, comprising a housing, a drive shaft, a glass with blades mounted on it. The lower edge of the cup wall forms a gap with the flange bottom of the housing, the mixer is equipped with an additional compressed air supply system to the upper part of the casing cavity, and the tail part of the drive shaft protruding beyond the specified casing is protected by a sealed cover (RF patent No. 2264849, IPC B01F 7/20).

This design cannot be used in the oil and chemical industries for mixing media to great depths. In addition, the lower end of the glass has no support, therefore, has limited loads on the stirrer blades.

A propeller-type mixing device of a reactor is known, consisting of an electric motor, a housing, a rod cover, on which the housing is mounted, a leading and driven cylindrical magnetic coupling half with a cooled separation screen, for which water is supplied through channels in the manhole cover of the stuffing box reactor, bearing housing (Krasilnikov A .Ya., “Features of the use of magnetic couplings in the construction of pressurized machines”, Publishing Department of GOU VPO “Ural State Technical University” - UPI, 200 7, p. 120. - prototype).

The disadvantages of this design are:

- the need for organizing the supply and removal of coolant to the screen of the magnetic coupling;

- to replace the rolling bearings, when they are worn out, it is necessary to completely disassemble the product with depressurization of the reactor vessel;

- the presence of the stuffing box shaft seal, which prevents the mixing medium from entering the lower bearing and requiring control of the absence of mixed medium or its vapor from the bearings, which narrows the use of such devices.

The technical result to which this invention is directed is to ensure the reliability of the device while maintaining small external dimensions that change slightly even with an increase in the length of the shaft for mixing media to a greater depth, absence or reduction of the load on the cantilever shaft.

This technical result is provided by a mixing device that includes an engine, a shaft mounted inside the column through bearing bearings, mounted on the housing cover and connected at one end to a magnetic coupling, a mixer. A cup with stirrers mounted on it is fixed at the other end of the shaft, while the shaft consists of one or more parts, each of which has bearing connections, the cup is proportional to the length of the shaft, and the mixers are removable.

With an integral shaft, the supports are made in the form of sliding bearings (Fig. 1).

The upper shaft support is made in the form of rolling bearings (Fig. 2).

The shaft consists of one or more parts connected by couplings, has bearings in the form of rolling bearings, and the shaft seal is made in the form of a double mechanical seal located in the upper part between the glass and the column, lubricated by a barrier fluid in the cavity between the end pairs.

In the lower part of the glass, behind the lower bearing support, there is a console for installing one or more mixers, and the distance from the lower mixer on the console to the bearing support is equal to the distance to the nearest mixer mounted on the glass.

In FIG. 1 shows a cross-sectional mixing device having a shaft rotating with a cup in sliding bearings; in FIG. 2 - a mixing device having an upper shaft support in the form of a rolling bearing; in FIG. 3 - a mixing device having mixers mounted both on a glass and on a console; in FIG. 4 shows a shaft consisting of several parts. The shaft consists of one or more parts connected by couplings, has bearings in the form of rolling bearings, and the shaft seal is made in the form of a double mechanical seal located in the upper part between the glass and the column, lubricated by a barrier fluid in the cavity between the end pairs.

The mixing device (Fig. 1) consists of a drive 1 (motor or gearmotor), housing 2, adapter flange 3, a magnetic coupling consisting of a leading 4 and a driven 5 coupling halves separated by a ceramic or metal shield 6, with the shield design does not require cooling. The driven coupling half 5 is fixedly connected to the shaft 7, on the other end of which a cup 8 is fixed. One or more removable mixers 9 are fixed on the cup 8. The type of mixer can be different (propeller, turbine, anchor, etc.). The glass 8 and the removable mixer 9 form a mixing element. The shaft 7 is installed inside the column 10, mounted on the cover 11 of the tank. The cover 11 has a fitting (not shown) for introducing mixed components (liquid, gases or powders). The cup 8 is fixedly connected to the shaft 7, the upper end of the cup 8 is centered by a sliding bearing 12 of a chemically resistant polymer mounted on a fixed column 10. Removable mixers 9 are mounted on the cup 8 with different heights in relation to each other. Plain bearings 12, 13, 14, in which the shaft 7 rotates, and with it the cup 8, are made of chemically resistant material. Lubrication of the lower bearing 14 is carried out by oil or a neutral liquid poured inside the column 10. Lubrication of the upper bearing 13 is consistent or is carried out by pairs of liquid poured into the column 10. The materials of the sliding pairs 12, 13, 14 “bearing-shaft” allow operation in the semi-dry mode dry friction. The shaft has as an upper support (Fig. 2) a rolling bearing 15 of a closed type with grease. This design has advantages at high speeds of the removable mixer 9 (more than 300 rpm), greater reliability and service life, because the lower bearing 14 is always effectively lubricated and cooled by oil poured into the column, and the upper one is isolated from the vapors of the mixed medium by this oil.

A mixing device (Fig. 3), in which one or more removable mixers 9 are cantilevered relative to the lower bearing support 14 due to the presence of a shank 17 in the glass 8, while another mixer 9 (or several mixers) is fixed above the support 14 on the glass 8. The distance (L) from the lower detachable mixer 9 mounted on the shank 17 to the lower bearing is equal to the distance (L) from the lower bearing to the lower mixer installed on the bowl 8. The type and size of the mixers can be different. Due to this arrangement of the removable mixers 9 relative to the lower bearing 14, it is possible to minimize the bending moment at the location of the bearing 14 from radial forces on the removable mixers 9 by balancing them.

The mixing device (Fig. 4) has a shaft consisting of several parts 7, 7a ... 7n, if necessary, to increase the immersion depth of the removable mixers 9. As bearings of the shaft 7 and the cup 8, closed-type rolling bearings 18, 19, 20 are used, which are sealed off from the mixed product with a double mechanical seal 21 and a barrier fluid.

The mechanical seal 21 consists of a pair of mechanical seals sequentially installed one after the other, the closure (barrier liquid) is filled into the cavity between which the supply pipes 22 and the outlet 23 of this liquid are fed to the thermosiphon tank 24. Section of the shafts 7, cups 8 and columns 10 are interconnected by couplings 25, respectively, the number of rolling bearings increases, in each part of the column and glass - two. With an increase in the length of the shaft 7, the dimensions of the mixing device above the cover 11 remain unchanged.

The mixing device operates as follows.

The components for mixing through the holes in the lid 11 are fed into a container for mixing (not shown). The drive 1 transmits torque through the leading 4 and the driven 5 of the coupling half to the shaft 7 and the cup 8, driving the removable mixers 9, which provide effective mixing of the components of the mixture.

The proposed design of the mixing device ensures complete tightness of the internal volume of the container relative to the environment, reliable and safe, has small dimensions above the container cover, does not require additional lubrication for bearings and the cooling of the separation screen of the magnetic coupling, provides the ability to conveniently replace the upper thrust foot and upper bearing without removing the lid from the mixing tank.

It is possible to install any number of mixers without changing the diameter of the shaft.

The design is made in such a way that when mixing the product does not come in contact with the end pair, bearings and magnetic coupling, it is ensured that there is no wear and damage from exposure to this product, therefore, the proposed device can be used to mix any media, including with solid particles, viscous inclusions, fibers, etc. This ensures reliable sealing of the product from the environment.

Claims (5)

1. A mixing device comprising a motor, a shaft mounted inside the column through bearings, fixed to the housing cover and connected at one end to a magnetic coupling, an agitator, characterized in that a glass with agitators mounted on it is fixed to the other end of the shaft; consists of one or more parts, each of which has bearing connections, the cup is proportional to the length of the shaft, and the mixers are removable. 2. The mixing device according to claim 1, characterized in that, with an integral shaft, the supports are made in the form of sliding bearings. 3. The mixing device according to claim 1, characterized in that the upper shaft support is made in the form of rolling bearings. 4. The mixing device according to claim 1, characterized in that the shaft, consisting of one or more parts connected by couplings, has bearings in the form of rolling bearings, and the shaft seal is made in the form of a double mechanical seal located in the upper part between the glass and the column lubricated by a barrier fluid in the cavity between the end pairs. 5. The mixing device according to claim 1, characterized in that in the lower part of the glass, behind the lower bearing support there is a console for installing one or more mixers, and the distance from the lower mixer on the console to the bearing support is equal to the distance to the nearest mixer mounted on the glass .

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