EP0836893A2 - Pneumatic classifier with vertical axis - Google Patents

Abstract

The wind classifier, with vertical axis, issuing the material centrally, has a tangential classifying air input (4) at the height of the rotor (8), a guide scoop crown fixed with radial clearance at the circumference of the rotor, the scoop rotor itself with a bearing on one side, a rotor drive shaft (2) and a casing (1) with outputs for fine and coarse material (23,24). The drive shaft, fine and coarse material output cavities (13,14) and the rotor bearing are all on the same side of, i.e. below, the rotor. A support device connects the drive shaft to the rotor.

Description

The invention relates to a vertical-axis air classifier with a central good job with tangential air supply arranged at the level of the classifying rotor, with a fixed on the circumference of the classifying rotor arranged at a radial distance Guide vane ring, with a ring-shaped one through one Paddle wheel classifier rotor and a coaxial radial distance to the The outer circumference of the classifying rotor arranged guide vane ring limited Visual space, with a drive shaft for the classifier rotor mounted on one side and a housing with fine and coarse material outlet.

Such an air classifier, in which the material to be viewed is arranged around an axis rotating wheel is set in rotating motion and with one from the outside inward running air flow into which the rotating visible material is added evenly over the circumference of the classifying wheel to the classifying zone known from German Offenlegungsschrift DE 35 21 638 A1.

The material to be sifted is fed in centrally and spread over a spreading plate distributed and bell-shaped over the outer circumference of the classifying rotor evenly distributed good veil passed past the classifier wheel blades. The The classifying wheel is flowed through by the classifying air from the outside in and that Fine material directed into the interior of the classifier rotor. The rejected coarse material follows gravity continues and is surrounded by an annular coarse material discharge area added.

The visible air flows radially from the outside to the inside. By the rotating paddle wheel rejects the coarse material radially outwards and the fine material together with the classifying air into the interior of the classifying rotor transported. The fine material sighted is then led axially downward Redirected direction and then discharged from the classifier rotor.

The drive and the bearing of the classifier rotor are above the classifier rotor arranged and on the same side of the central task.

The problem of uniform and continuous good feed is here by central task solved well enough. Since drive and storage above the Scatter plates of the classifier rotor are arranged, but this area for the the central good task must be kept free at the stand technology only an unsatisfactory arrangement of central good task, Drive and bearing using a hollow drive shaft. This construction, storage is very complex, only for small ones Suitable speeds and very cumbersome to assemble.

Another disadvantage of this classifier is the discharge of the coarse material with the help a conveyor trough running at an angle to the horizontal. Task of this It is the conveyor trough that extends over the entire circumference of the coarse material discharge area resulting coarse material to one, only part of the scope of the To lead coarse material discharge space taking discharge nozzle.

For the classifier according to this prior art, the problem of Coarse material discharge solved well enough. The disadvantage here, however, is that the Conveyor channel builds very large in the axial direction.

Another state of the art with central good task from above shows the German patent DE-PS 894 803. The main characteristics of this Air classifier is the one-sided mounting of the classifier rotor with one on the drive side arranged fine material discharge. The task of the good to be sifted is done centrally above the closed cover plate of the classifier rotor. At The cover disk acts in a vertical arrangement of classifier rotor and drive shaft as a spreading disc around the feed material evenly over the classifier rotor circumference to distribute. This results in a over the outer circumference of the classifying rotor evenly distributed good veil.

The visible air flowing radially from the outside in through the classifying rotor carries the fine material into the interior of the classifier rotor, whereas the coarse material goes to the rotating blades is rejected. The fines sighted in this way then in a radial direction from the inside to the outside of the classifying rotor carried out.

In the wind classifier according to this prior art, the cover plate together with the classifier wheel blades from an extended one, the classifier rotor penetrating part of the drive shaft. The disadvantage is that the Inside the classifier rotor does not remain free of internals and therefore the flow in the Inside the classifier rotor is disturbed.

Another disadvantage is the insufficient sealing of the fine material discharge area vis-à-vis the viewing area, so that spray grain through the gap between Sifter wheel blades and housing penetrate into the fine material that has already been sighted can.

The construction is overall not very stable and an assembly or disassembly of the Classifier rotor out of the housing very difficult. Such is an air classifier especially not suitable for very high speeds.

The invention is therefore based on the object with a vertical air classifier to create a centralized task and spreading disc, in which the entire constructive design of classifier rotor, storage, drive and housing in such a way is solved that the classifier rotor is stable even at high speeds, a simple assembly / disassembly of the classifier rotor in the classifier housing enables and at the same time the flow is favored and on the other hand an easy one Cleaning is guaranteed, as well as improved sealing of the work rooms is made possible.

According to the invention, this object is achieved by the characterizing features solved according to the claims, in particular in that the Drive shaft, an annular fine material outlet space, an annular Coarse material discharge area, and the classifier wheel bearing on the same side are arranged below the classifier rotor.

Although air classifiers according to the prior art are known, which in addition to a classifier rotor driven on one side an axially downward leading Have fines exit, such as from the German patent DE-PS 36 38 915 C 2.

However, there is still the coarse material outlet at the level of the classifier wheel blades arranged and leads to the outside in the radial direction. This construction is little Easy to assemble and the cleaning of such a classifier is very complex.

With newer air classifiers, especially for high-tech products, will special emphasis on easy dismantling of the entire classifier and on the good Cleanability laid. This is particularly important for products from the Pharmaceutical sector, as well as for pigments and ultrafine powders and toners.

In these cases, mainly small quantities of good are processed and often changing products spotted. The good cleanability and easy disassembly increasingly comes to the fore.

This leads to a compact, space-saving design for the classifier the supply rooms such as visual air supply, fine material discharge and coarse material discharge are narrow lie together.

In order to be able to clean all areas within the classifier, the classifier must do so be completely disassembled into its individual parts. This is about the distribution of the functional connections such as drive, storage, good feed, fine material outlet and Coarse material escaping through several sides of the classifier housing is particularly difficult.

The basic idea of the classifier according to the invention is that all functional connections are made from one side. The only exception is represents the product task, which is ideally carried out centrally from above.

Since the functional connections are all in the vertical direction below the Classifier wheel are arranged, the classifier wheel is from above via a cover in the Sifter housing easy to reach. To the air classifier according to the invention dismantling, only the upper housing cover has to be removed.

The classifier rotor can be released, in particular by means of a support device Drive shaft connected. The attachment takes place in a preferred Design by a central screw. By solving this one The classifier rotor can be screwed off the drive shaft and axially adjusted removed from the top of the classifier housing.

The primary task of the support device is to transmit the torque from the drive shaft to the classifier rotor. At the same time, the support device carries the Classifier rotor completely. This construction allows the space inside the Classifier rotor are kept completely free.

The aerodynamically designed openings of the support device are used for Removal of the sifted fine material from the inside of the sifting wheel. The load-bearing webs of the support device can in their cross section be aerodynamically shaped so as not to slow down the flow or otherwise to hinder and on the other hand the fine material with the visual air accelerate from the inside through a fan effect.

Suitable shapes of the webs are profiled cross sections, which are also spatial May have curvatures and thus act as an outlet guide. So can ventilation efficiency can be optimized.

By a suitable choice of the inner diameter of the support device in the Transitional area between classifier wheel and blade ring and the openings of the The support device also acts as an aperture.

The outer circumference of the transition area is machined as a sealing surface enables an exact seal of the visual space against the Fine goods exit room.

In a preferred embodiment, the seal is a fluid that can be flushed Poetry.

The inner walls of the classifier housing are designed so that a light Accessibility is achieved. With the classifier rotor removed, this can be done Classifier housings can be easily cleaned from above. The too Removing product approaches can from the inner walls of the classifier housing can be easily removed. Visible material that falls on the bottom of the classifier housing can be easily removed from the case base by suction.

This classifier construction is essential compared to the prior art simplified. In the case of sifter housings according to the prior art, the Cleaning openings mostly on the side of the classifier housing and provide window-like ones Breakthroughs. A horizontal discharge of the product approaches from these Lateral breakthroughs are, however, difficult because of the inner Sifter housing wall loosened product approaches due to gravity vertically fall down and then difficult through the horizontal Cleaning openings can be carried out.

Since the classifier rotor according to the invention has no undercuts, must apart from the upper housing cover, the classifier housing is not disassembled will.

In a classifier of this type with a relatively short axial extension of the Visible wheels and a good run in which the good is only once Classifying wheel is offered, it is disadvantageous that the residence time of the goods in the Visibility is short. The quality of the coarse goods is not optimal, because possibly not all fine goods are sighted and thus the share of fine goods in the discharged coarse material is still relatively high.

With such classifiers, the visible material is affected by the action of gravity guided down along the classifier rotor. Except for the radial The material to be sifted essentially moves in turbulence Direction of gravity downwards. The visible material is only the sifter offered once and for a short time. Due to the short dwell time of the material to be viewed on the classifier, the fine material cannot be completely diverted from the flow of classifying material and be sighted. The rejected coarse material fraction therefore still contains significant proportions of fine grain. The quality of the coarse goods is therefore not optimal.

Furthermore, the vertical alignment of the classifier and the result in Visible material falling downward is an inconsistent Good concentration in the viewing zone, which means that the entire classifier rotor length is not can be used optimally.

To control the dwell time and the concentration of the goods in the visual space can and thus a larger proportion of the fine material through the classifier rotor prospects and thereby optimizing the quality of the coarse goods the classifier with a helical screw that runs coaxially to the classifying wheel Helix equipped, which is within the ring-shaped viewing area extends.

The idea is that a visible material introduced into the sifter is in its Residence time is affected. Because with conventional classifiers in the outer Visible zone a mixture of fresh feed material and already viewed material occurs, there is a broad distribution of residence times of individual good particles with negative ones Consequences for the visual quality. The dwell time of the material to be sighted on the classifier is one important parameters for the visual quality. It determines the number of Particle contact with the classifying wheel or the guide vanes and thus the Probability for the release of coarse particles from adhering fine ones Particles.

Another problem with the known air classifiers is the inclination of the fluid particle suspension, to segregate in a force field. This allows local excessive concentrations of particles occur. With increasing Concentration of the particles, therefore, the fines are getting worse and worse from the Separate visible material. The visual quality is thus deteriorated.

The new helix in the viewing area also enables targeted Control of the visible material concentration in the area of the classifying wheel. Undesirable Particle concentrations can thereby be avoided.

By using such a screw helix according to the invention can control both the dwell time and the particle concentration will.

This is achieved by inserting one or more screw spirals between classifier wheel and guide vane ring. The helixes do one Transport of the in the viewing area between the guide vanes and the classifying wheel rotating visible material. The transport effect can be selected by choosing the slope the helix can be adjusted. By increasing the slope to Coarse material leakage increases the transport effect and thus the dwell time shortened. If, on the other hand, the pitch of the screw spiral is reduced, it is Dwell time longer. If the slope is reduced to such an extent that it becomes negative, i.e. the transport effect is directed towards the entry of the visible goods, so the visible goods promoted upwards against gravity and it becomes an additional one After-effect of the coarse material achieved.

Depending on the task, the screw spiral can over in individual areas the sight wheel height can be given a different slope. So that will the dwell time of the material to be classified varies over the height of the classifier wheel set.

For example, the visible material in the upper area of the classifying wheel by a Helical section with a high pitch can be quickly drawn in middle section due to a slight slope of the screw spiral a long Dwell time or a negative effect can be achieved and in the lower area of the classifying wheel with a helical section again high incline a quick discharge of the sighted coarse material will be realized.

The control of the particle concentration is determined by the number of Snail spirals reached. Due to the fact that the sifters according to the invention the visual goods task in general on the the entire circumference of the sight wheel is even, each one takes Helix a peripheral part of the amount of particles to be sifted. By the number of screw spirals thus becomes the maximum particle concentration limited. To determine the particle concentration in individual areas above the Changing the sight wheel height can vary the number of worm helixes will.

The helical coils do not necessarily have to cover the whole Extend sight wheel height, you can only in partial areas of sight wheel heights be arranged.

In the further embodiment, a flat washer is below arranged of the classifier rotor and extends over the entire bottom of the annular coarse material discharge space. This has compared to other solutions essential advantages.

If the washer according to the invention is provided with clearers which are fixed on the Are attached to the surface of the ring disc, the transport effect reinforced, but there is a risk that the sighted coarse material through the The scraper is crushed and thus the quality of the coarse goods deteriorates.

If there are no high demands on the quality of the coarse goods, can such clearers enable a high throughput of coarse material.

Another possibility is given by an additional air flow, the one has the desired transport effect on the coarse material. This air flow should be however, be so strong that due to the crowded construction, the sighting through the additional flow would be affected.

The additional idea of the invention is the coarse material that has been sighted through a fluidize additional air flow and through a rotating ring disc to transport to the coarse goods outlet. An additional, fixed ring prevents the finished coarse material from being returned to the viewing area.

The invention is described in more detail below on the basis of the preferred exemplary embodiments explained.

Fig. 1 shows the cross section of an air classifier according to the invention with a closed drive shaft.

Fig. 2 shows the cross section of an air classifier according to the invention with a perforated drive shaft.

In the wind sifter according to Fig. 1 at the lower end of the housing 1 is mounted the drive shaft 2. The drive shaft 2 penetrates the housing 1 and receives the classifying rotor 8 at the shaft end. The guide vane ring 3 is fixedly arranged inside the housing 1 at the level of the classifier wheel vane ring 9 .

The complete classifier rotor 8 is detachably fastened to the drive shaft 2 with the fastening screw 12 . The cover disk of the rotor 8, which is designed as a diffusion disk 16 , is closed by a releasable cover screw 11 in order to allow access to the fastening screw 12 so that the complete rotor 8 can be detached from the drive shaft 2 .

The classifying air is supplied through the classifying air inlet 4 behind the guide vane ring 3 . Within the housing 1 , the annular coarse material discharge space 13 and the annular fine material discharge space 14 are arranged below the classifying wheel vane ring 9 coaxially with the drive shaft.

The lower cover plate 15 of the classifying rotor 8 is provided with openings and thereby opens the fine material outlet from the inside of the classifying rotor 8 into the fine material discharge space 14 .

In FIG. 2, the Feingutaustragsraum the penetrating portion of the drive shaft 2 as a perforated shaft member, the support means 10 is formed and thereby allows the passage of the fine material from the interior of the separator 8 in the Feingutaustragsraum fourteenth

This support device 10 comprises the base plate 18 , the washer 17 , and the aerodynamic spacer webs 10a and form a connecting link between the drive shaft 2 and classifier wheel 8 and the passages for the discharge of the fine material from the inside of classifier wheel 8 .

The classifier wheel 8 consists of the classifier wheel vane ring 9 , the lens 16 and the cover plate 15 and is rotatably connected to the support device 10 . This connection in the area of the discs 15 and 17 can be designed releasably and z. B. by screws 19 arranged uniformly over the circumference of the classifying rotor.

In the area of the disks 15, 17 and the housing 1 , a seal 20 that can be flushed with a fluid is shown in an axial arrangement and reliably separates the visible space 21 from the fine material outlet space 14 .

In the axial transition area between classifier wheel 8 and support device 10 , the lower cover disk 15 projects beyond the inner diameter of the annular disk 17 , and thus over the support device 10 into the interior, and thus forms an orifice with a throttling effect in the transition area.

The good feed takes place on the cover plate 16 of the classifying rotor 8 , which forms a diffusing plate. The annular channel between the outer diameter of the classifying wheel 8 and the inner diameter of the guide vane ring 13 forms the classifying space 21 over the height of the classifying wheel 8 .

Visible material flows through the viewing space 21 in the vertical direction. In order to control both the concentration of visible material in the visible space 21 and the dwell time, a screw spiral 29 extends almost over the entire radial width of the visible space 21 and extends over the entire height of the classifying wheel 8 . In the embodiment shown, a single helical screw with a constant pitch is used.

The sifting air flow runs perpendicular to the sifting material flow. The classifying air from the classifying air inlet 22 passes horizontally through the fixed guide vane ring 3 into the classifying chamber 21 and flows through it perpendicularly to the classifying material flow.

The fine material sighted is discharged axially with the classifying air via the fine material outlet 23 . The coarse material sighted is discharged through the coarse material discharge space 13 below the viewing space 21 via the coarse material outlet 24 .

The coarse material discharge ring 25 is fixedly connected to the classifying wheel 8 and rotates within the coarse material discharge space 13 . The fixed retaining ring 26 is arranged above the coarse material discharge space 13 and is firmly connected to the housing 1 .

The gap 27 for the introduction of the scavenging air 28 is located between the bottom of the coarse material discharge space 13 and the coarse material discharge ring 25 .

Claims (36)

Vertical-axis air classifier with a central crop feed with tangential air supply arranged at the level of the classifier rotor, with a fixed guide vane ring arranged at a radial distance on the circumference of the classifier rotor, with an annular classifier rotor classifier rotor arranged through one side and a coaxially arranged at a radial distance from the outer circumference of the classifier rotor Guide vane ring limited visual space, with a drive shaft for the classifier rotor mounted on one side and a housing with fine and coarse material outlet, characterized in that the drive shaft, an annular fines discharge area, an annular coarse material discharge area, and the classifier wheel bearing
are arranged on the same side and below the classifier rotor. Vertical-axis air classifier according to claim 1, characterized in that the annular fine material discharge space is arranged coaxially to the drive shaft is. Vertical-axis air classifier according to claim 1, characterized in that the annular coarse material discharge space arranged coaxially to the drive shaft is. Vertical-axis air classifier according to claim 1 to 3, that the coarse material discharge area is located directly below the viewing zone. Vertical-axis air classifier according to claim 1 to 4, that the fines exit from the classifier wheel interior in the axial direction runs below. Vertical-axis air classifier according to claim 1 to 5, characterized in that the fines exit through a perforated drive shaft he follows. Vertical-axis air classifier according to claim 6, characterized in that the drive shaft through a perforated for the fine material outlet, the Torque-transmitting, aerodynamic for guiding the fine material flow designed support device is connected to the classifier rotor. Vertical-axis air classifier according to claim 6 or 7, characterized in that that the flow-optimized openings in the cross section Support device designed as essentially axially extending slots are. Vertical-axis air classifier according to claims 6 to 8, characterized in that that the axially extending slots are evenly distributed over the circumference. Vertical-axis air classifier according to claims 6 to 9, characterized in that that with at least 20% of the peripheral surface of the support device Breakthroughs is provided. Vertical-axis air classifier according to claim 6 to 10, characterized in that the percentage area of breakthroughs on the lateral surface of the Support device is at least as large as the percentage of the area Breakthroughs on the surface of the classifier rotor. Vertical-axis air classifier according to claims 6 to 11, characterized in that that the aerodynamic openings of the support device on a circumference deviating from the radial circumference of the classifying wheel blades are arranged. Vertical-axis air classifier according to claim 6 to 12, characterized in that the classifier rotor is detachably connected to the support device. Vertical-axis air classifier according to claims 6 to 13, characterized in that that in the inner flow area of the classifier rotor at the transition between a throttle diaphragm is arranged in the classifying rotor and support device. Vertical-axis air classifier according to claim 6 to 14, characterized in that a seal between the fine material discharge space and the visible space in the Transition area of the support device to the classifying rotor is arranged. Vertical-axis air classifier according to claim 15, characterized in that the seal is a seal that can be flushed with a fluid. Vertical-axis air classifier according to claim 16, characterized in that the flushing gap of the seal, which can be flushed with a fluid, is arranged axially. Vertical-axis air classifier according to claim 16, characterized in that the flushing gap of the seal, which can be flushed with a fluid, is arranged radially. Vertical-axis air classifier according to claim 1, characterized in that at least one coaxial with the classifier wheel within the classroom extending, helical screw spiral extends. Vertical-axis air classifier according to claim 19, characterized in that the helix on the inner circumference of the fixed guide vane ring is attached. Vertical-axis air classifier according to claim 19 or 20, characterized characterized in that the screw spiral has a positive slope. Vertical-axis wind classifier according to claim 19 to 21, characterized characterized in that the screw helix has a negative slope. Vertical-axis air classifier according to claims 19 to 22, characterized characterized in that the slope of the screw spiral over their History changes. Vertical-axis air classifier according to claims 19 to 23, characterized characterized in that the helix at different altitudes of the Visible space has different slopes. Vertical-axis air classifier according to claims 19 to 24, characterized characterized in that the screw spiral only in a partial area of the radial extension of the viewing space is arranged. Vertical-axis air classifier according to claims 19 to 25, characterized characterized in that the screw spiral only in a partial area of the axial viewing height is arranged. Vertical-axis air classifier according to claims 19 to 26, characterized characterized in that several helixes are arranged in the viewing area are. Vertical-axis air classifier according to claim 3, characterized in that an annular disc below the classifier wheel rotating within the Coarse material discharge space is arranged. Vertical-axis air classifier according to claim 28, characterized in that the rotating ring disc is firmly connected to the classifier wheel. Vertical-axis air classifier according to claim 28 or 29, characterized characterized in that the washer over the radially inner side wall of the annular coarse material discharge space and the floor of the coarse material discharge space extends. Vertical-axis air classifier according to claim 28 to 30, characterized characterized in that between the floor of the coarse material discharge space and the washer a gap channel for a fluid flow to fluidize the Coarse good is provided. Vertical-axis air classifier according to claim 28 to 31, characterized characterized in that the washer with uniform over the circumference distributed clearers projecting into the coarse material discharge area is provided. Vertical-axis win classifier according to claims 28 to 32, characterized in that that coaxial to the rotating washer a fixed retaining ring for the coarse material is provided. Vertical-axis air classifier according to claim 33, characterized in that the fixed retaining ring is firmly connected to the housing. Vertical-axis air classifier according to claim 1 to 34, that the coarse material outlet from the coarse material discharge space axially downwards runs. Vertical-axis air classifier according to claim 1 to 35, that the fine material outlet from the fine material discharge area runs axially downward.

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