CA1160991A - Centrifugal classifier - Google Patents
Centrifugal classifierInfo
- Publication number
- CA1160991A CA1160991A CA000380435A CA380435A CA1160991A CA 1160991 A CA1160991 A CA 1160991A CA 000380435 A CA000380435 A CA 000380435A CA 380435 A CA380435 A CA 380435A CA 1160991 A CA1160991 A CA 1160991A
- Authority
- CA
- Canada
- Prior art keywords
- sifting
- rotor
- air
- ring
- outlet
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- Combined Means For Separation Of Solids (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A centrifugal classifier is disclosed which has a higher throughput than existing classifiers. The classifier has a sub-stantially cylindrical upright housing with an approximately tan-gential sifting-air inlet in which are arranged at a radial dis-tance from, and centrally of, the casing of the housing, a vane-ring and, at a radial distance inwardly therefrom, a sifting rotor with a lamination-ring forming radial passages, an inlet for the granular material to be classified opening, at the top, into the classifying area located between the vane-ring and sifting rotor, and an outlet for the sifting air, charged with fine material, be-ing located adjacent the rotor, the diameter of the outlet corres-ponding approximately to the inside diameter of the rotor, and the sifting-air inlet and the vane-ring extending over approximately the same axial length as the rotor, characterized in that the two end-faces of the sifting rotor are each located adjacent a fine-material-sifting-air outlet.
A centrifugal classifier is disclosed which has a higher throughput than existing classifiers. The classifier has a sub-stantially cylindrical upright housing with an approximately tan-gential sifting-air inlet in which are arranged at a radial dis-tance from, and centrally of, the casing of the housing, a vane-ring and, at a radial distance inwardly therefrom, a sifting rotor with a lamination-ring forming radial passages, an inlet for the granular material to be classified opening, at the top, into the classifying area located between the vane-ring and sifting rotor, and an outlet for the sifting air, charged with fine material, be-ing located adjacent the rotor, the diameter of the outlet corres-ponding approximately to the inside diameter of the rotor, and the sifting-air inlet and the vane-ring extending over approximately the same axial length as the rotor, characterized in that the two end-faces of the sifting rotor are each located adjacent a fine-material-sifting-air outlet.
Description
The invention relates to a centrifugal classifier.
A classifier of this kind, as already known from German OS 1, 607,631, is used for classifying, i.e separating a mixture or quantity of granular material, of different sizes and/
or different shapes and/or different specific weight, into coarse material or coarse grains (of a grain-size above a certain dia-meter) and fine material (of a grain-size below that limit). The material to be classified is charged from above into the classi-fying area (an annular space between the vane-ring and the sifting rotor); at the same time, sifting air flows from the outside, through the vane-ring, into the classifying area, thus following a spiral path and carrying the particles along accorgingly. In the classifying area, the particles are subjected to radially di-rected resistance and centrifugal forces acting in opposite direc-tions. For a specific radial and axial air-velocity, there exists a limiting grain size at which the two forces are equal.
The coarser particles (coarser than the limiting size) thus arrive sooner or later at the coarse-material outlet at the bottom of the classifying area The fine material, on the other hand, is carried along with the sifting air which flows inwardly through the passages in the sifting wheel and is drawn o~f through a fine-material/sifting-air outlet adjoining axially the interior of the sifting wheel The said fine material is finally separated from, or precipitated out of, the sifting air which can then be returned to the sifting-air inlet, i.e. it can be circulated.
Classifiers of this kind are used mainly for recovering fine ma-terial of the smallest possible grain-size and in a narrow grain-size distribution, the upper limit sought being between 2 and 4 ~m.
This very fine granular material is frequently used as a filler, for synthetic material, automobile tires, colours, paints or coat-ing agents for paper. The coarse material is used for other pur-- poses, or is reground to yield further fine material.
_ 1 - ~.
116~
Relatively large quantities are required for the above-mentioned purposes at the lowest possible price. With existing classifiers of this kind, however, comprising only one fine-material/sifting-air outlet, the throughput is relatively low, being dependent upon, among other things, the dimensions of the classifierJ more particularly the length and dia~eter of the sift-ing rotor, i,e, the peripheral surface thereof where classifying takes place, Diameter is limited by increasing centrifugal force, while the limiting grain size is dependent upon diameter and r,p,m,, and thus also upon centrifugal force. The length of the sifting rotor is also limited, mainly because of the difference in radial flow-velocity along the sifting rotor between pairs of laminations, This radial flow-velocity is dependent upon the suction, i,e, negative pressure applied at the outlet, the said suction being at its maximum at the outlet and decreasing towards the opposite end, It is the purpose of the invention to provide a classi-fier of this kind with far higher throughput, preferable for grain sizes from 10 down to 2 ~m, According to the invention, this pur-pose is achieved by locating a fine-material/sifting-air outlet at each end-face of the sifting rotor, These two fine-material/sifting-air outlets make it possible to use a much longer sifting wheel than heretofore, re-sulting in a correspondingly higher throughput, The great length of the sifting rotor provides a correspond~ng zone of relatively uniform stable flow undisturbed by irregularities at the ends of the sifting rotor, thus achieving correspondingly effective and uniform classifying, The diameter : length ratio of the sifting rotor is preferably between 1 : 1,5 and 1 : 4, The two fine-material/sifting-air outlets almost double the cross-section of the outlet, so that in spite of the increased throughput, the flow-velocity is lower, With the high flow-1 1 689~1 ve~ocities hitherto used, the fine material strikes the walls so violently that is adheres thereto, especially if an initial coat-ing of fine material has already been deposited thereon. This progressively impairs the flow conditions and results in a de-crease in throughput.
Above all, however, some of these stratified deposited (so-called "eggshells") burst and pass into the fine material which leads to major difficulties or even renders the fine material useless. In order to avoid these deposi$s, therefore, the flow deposit has been limited, but this also limits the throughput.
According to the invention, these deposits of fine ma-terial are prevented by surrounding the two fine-material/sifting-air outlets, in the vicinity or the rotor, with cooling chambers, since cooler particles adhere less easily to a cooled surface.
In this connection, it is desirable to arrange the bearings at each end of the sifting-rotor shaft in the cooling chambers. This also cools the bearings, thus increasing the reliability and life of the machine. With increased throughput, this becomes particu-larly important.
' 20 According to another configuration, a labyrinth-seal is provided at each end-face of the sifting rotor, each of the said seals communicating through a duct with one of the cooling cham-bers. The cooling air thus also serves to flush the labyrinth-, seals from outside to inside. This not only cools the said seals, but also eliminates the need for a separate source of flushing air.
A flushed labyrinth-seal in a classifier is already known from German AS 1,757,582.
~' According to still another configuration, support-discs, provided with axial passages, for retaining the sifting-rotor la-minations, are shrunk onto the shaft. The rotor laminations are thus secured, not only at their ends, but also by the said support-discs between the ends.
-- 3 _ ., 1 3 6~99 1 Finally, an annular duct for injecting into the classi-fying area the amount of material to be classified is provided at the end-face of the housing facing the coarse-material outlet.
This permits uniform charging of the increased throughput.
The present invention refers to a centrifugal classifier having a substantially cylindrical, upright housing with an approximately tangential sifting-air inlet, in which are arranged, at a radial distance from, and centrally of, the casing of the housing,~ a vane-ring and, at a radial distance inwardly there-from, a sifting rotor with a lamination-ring forming radial passages, an inlet for the granular material to be classified opening, at the top, into the classifying area located between the said vane-ring and sifting rotor, and an outlet for the sifting air, charged with fine material, being located adjacent the rotor, the diameter of the said outlet corresponding approximately to the inside diameter of the said rotor, and the sifting-air inlet and the vane-ring extend-ing over approximately the same axial length as the rotor.
It is the purpose of the invention to provide a classi-fier of this kind with far higher throughput, preferable forgrain sizes from 10 down to 2 ~m. According to the invention, this purpose is achieved by locating a fine-material/sifting-air outlet at each end-face of the sifting rotor.
These two fine-material/sifting-air outlets make it possible to use a much longer sifting wheel than heretofore, resulting in a correspondingly higher throughput. The great length of the sifting rotor provides a corresponding zone of relatively uniform stable flow undisturbed by irregularities at the ends of the sifting rotor, thus achieving correspondingly effective and uniform classifying.
A better explanation is provided by the following des-cription of an example of embodiment of the invention, in con-1 1 6~9g 1 Junction with the drawing attached hereto, wherein:
Figure 1 is a longitudinal section through a classifieraccording to the invention.
Figure 2 is a view of the classifier from above, to the left in cross-section and to the right in plan-view.
Figure 3 is an enlarged view of detail III in Figure 1, namely of the labyrinth-seal with a supply of flushing air from the cooling chamber.
The classifier comprises a concentric, substantially cylindrical housing 1 with a tangential sifting-air inlet 2, into which the sifting air enters, uniformly over the entire axial height, in the direction of arrows 20.
A vane-ring 9 is arranged in the said housing, spaced radially from the casing thereof. Lamination-ring 11 on the sifting rotor is also spaced radially from the vane-ring 9. The granular material to be separated is charged from above into classifying area 23 between vane-ring 9 and rotor lamination-ring 11. An annular duct 22, for injecting the granular material, is provided in the upper part of the housing wall, with a con-nector 7 opening into the said duct. Located at the opposite,i~e. the lower, end-face of the housing is a funnel-shaped coarse-material outlet 8.
Located at each end-face of the sifting rotor is a fine-material/sifting-air outlet 3, 4 in the form of a curved piece of pipe, the diameter of which corresponds approximately to the inside diameter of the rotor.
Sifting-air/fine-material outlets 3, 4 are each sur-rounded by a cooling-air chamber 17, 18 to each of which cooling air is supplied through a connection 19 which prevents fine material from being deposited in the said outlets. Also mounted in cooling-air chambers 17, 18, at both ends, in bearing brackets 5, 6, is the rotor-shaft lOa which passes through curved outlets 1 16~gl , 4. The bearin~s are thus also cooled. Due to the positive pressure obtaining in the said cooling-air chambers, no fine material can enter them (see arrows in shaft lead-throughs).
Dr:ive is by a V/belt pulley 12.
Sifting rotor 10 is open at both end-faces in such a manner that it is sealed to outlets 3, 4. Located between the sifting rotor and the housing is a seal 15, 16 in the form of a flat disc or a labyrinth. Flushing air is introduced froin cooling-air chambers 17, 18, through a duct 27, to provide a ; 10 seal between sifting area 23 and outlets 3, 4 (arrow 19 in Figure 3).
Support-discs 24, equipped with radial passages, are shrunk onto shaft lOa of the sifting rotor. The outer periphery of each end of the rotor is surrounded by a deflector ring 25, 26.
, .
,.
-5a-,, .
.
' ~
A classifier of this kind, as already known from German OS 1, 607,631, is used for classifying, i.e separating a mixture or quantity of granular material, of different sizes and/
or different shapes and/or different specific weight, into coarse material or coarse grains (of a grain-size above a certain dia-meter) and fine material (of a grain-size below that limit). The material to be classified is charged from above into the classi-fying area (an annular space between the vane-ring and the sifting rotor); at the same time, sifting air flows from the outside, through the vane-ring, into the classifying area, thus following a spiral path and carrying the particles along accorgingly. In the classifying area, the particles are subjected to radially di-rected resistance and centrifugal forces acting in opposite direc-tions. For a specific radial and axial air-velocity, there exists a limiting grain size at which the two forces are equal.
The coarser particles (coarser than the limiting size) thus arrive sooner or later at the coarse-material outlet at the bottom of the classifying area The fine material, on the other hand, is carried along with the sifting air which flows inwardly through the passages in the sifting wheel and is drawn o~f through a fine-material/sifting-air outlet adjoining axially the interior of the sifting wheel The said fine material is finally separated from, or precipitated out of, the sifting air which can then be returned to the sifting-air inlet, i.e. it can be circulated.
Classifiers of this kind are used mainly for recovering fine ma-terial of the smallest possible grain-size and in a narrow grain-size distribution, the upper limit sought being between 2 and 4 ~m.
This very fine granular material is frequently used as a filler, for synthetic material, automobile tires, colours, paints or coat-ing agents for paper. The coarse material is used for other pur-- poses, or is reground to yield further fine material.
_ 1 - ~.
116~
Relatively large quantities are required for the above-mentioned purposes at the lowest possible price. With existing classifiers of this kind, however, comprising only one fine-material/sifting-air outlet, the throughput is relatively low, being dependent upon, among other things, the dimensions of the classifierJ more particularly the length and dia~eter of the sift-ing rotor, i,e, the peripheral surface thereof where classifying takes place, Diameter is limited by increasing centrifugal force, while the limiting grain size is dependent upon diameter and r,p,m,, and thus also upon centrifugal force. The length of the sifting rotor is also limited, mainly because of the difference in radial flow-velocity along the sifting rotor between pairs of laminations, This radial flow-velocity is dependent upon the suction, i,e, negative pressure applied at the outlet, the said suction being at its maximum at the outlet and decreasing towards the opposite end, It is the purpose of the invention to provide a classi-fier of this kind with far higher throughput, preferable for grain sizes from 10 down to 2 ~m, According to the invention, this pur-pose is achieved by locating a fine-material/sifting-air outlet at each end-face of the sifting rotor, These two fine-material/sifting-air outlets make it possible to use a much longer sifting wheel than heretofore, re-sulting in a correspondingly higher throughput, The great length of the sifting rotor provides a correspond~ng zone of relatively uniform stable flow undisturbed by irregularities at the ends of the sifting rotor, thus achieving correspondingly effective and uniform classifying, The diameter : length ratio of the sifting rotor is preferably between 1 : 1,5 and 1 : 4, The two fine-material/sifting-air outlets almost double the cross-section of the outlet, so that in spite of the increased throughput, the flow-velocity is lower, With the high flow-1 1 689~1 ve~ocities hitherto used, the fine material strikes the walls so violently that is adheres thereto, especially if an initial coat-ing of fine material has already been deposited thereon. This progressively impairs the flow conditions and results in a de-crease in throughput.
Above all, however, some of these stratified deposited (so-called "eggshells") burst and pass into the fine material which leads to major difficulties or even renders the fine material useless. In order to avoid these deposi$s, therefore, the flow deposit has been limited, but this also limits the throughput.
According to the invention, these deposits of fine ma-terial are prevented by surrounding the two fine-material/sifting-air outlets, in the vicinity or the rotor, with cooling chambers, since cooler particles adhere less easily to a cooled surface.
In this connection, it is desirable to arrange the bearings at each end of the sifting-rotor shaft in the cooling chambers. This also cools the bearings, thus increasing the reliability and life of the machine. With increased throughput, this becomes particu-larly important.
' 20 According to another configuration, a labyrinth-seal is provided at each end-face of the sifting rotor, each of the said seals communicating through a duct with one of the cooling cham-bers. The cooling air thus also serves to flush the labyrinth-, seals from outside to inside. This not only cools the said seals, but also eliminates the need for a separate source of flushing air.
A flushed labyrinth-seal in a classifier is already known from German AS 1,757,582.
~' According to still another configuration, support-discs, provided with axial passages, for retaining the sifting-rotor la-minations, are shrunk onto the shaft. The rotor laminations are thus secured, not only at their ends, but also by the said support-discs between the ends.
-- 3 _ ., 1 3 6~99 1 Finally, an annular duct for injecting into the classi-fying area the amount of material to be classified is provided at the end-face of the housing facing the coarse-material outlet.
This permits uniform charging of the increased throughput.
The present invention refers to a centrifugal classifier having a substantially cylindrical, upright housing with an approximately tangential sifting-air inlet, in which are arranged, at a radial distance from, and centrally of, the casing of the housing,~ a vane-ring and, at a radial distance inwardly there-from, a sifting rotor with a lamination-ring forming radial passages, an inlet for the granular material to be classified opening, at the top, into the classifying area located between the said vane-ring and sifting rotor, and an outlet for the sifting air, charged with fine material, being located adjacent the rotor, the diameter of the said outlet corresponding approximately to the inside diameter of the said rotor, and the sifting-air inlet and the vane-ring extend-ing over approximately the same axial length as the rotor.
It is the purpose of the invention to provide a classi-fier of this kind with far higher throughput, preferable forgrain sizes from 10 down to 2 ~m. According to the invention, this purpose is achieved by locating a fine-material/sifting-air outlet at each end-face of the sifting rotor.
These two fine-material/sifting-air outlets make it possible to use a much longer sifting wheel than heretofore, resulting in a correspondingly higher throughput. The great length of the sifting rotor provides a corresponding zone of relatively uniform stable flow undisturbed by irregularities at the ends of the sifting rotor, thus achieving correspondingly effective and uniform classifying.
A better explanation is provided by the following des-cription of an example of embodiment of the invention, in con-1 1 6~9g 1 Junction with the drawing attached hereto, wherein:
Figure 1 is a longitudinal section through a classifieraccording to the invention.
Figure 2 is a view of the classifier from above, to the left in cross-section and to the right in plan-view.
Figure 3 is an enlarged view of detail III in Figure 1, namely of the labyrinth-seal with a supply of flushing air from the cooling chamber.
The classifier comprises a concentric, substantially cylindrical housing 1 with a tangential sifting-air inlet 2, into which the sifting air enters, uniformly over the entire axial height, in the direction of arrows 20.
A vane-ring 9 is arranged in the said housing, spaced radially from the casing thereof. Lamination-ring 11 on the sifting rotor is also spaced radially from the vane-ring 9. The granular material to be separated is charged from above into classifying area 23 between vane-ring 9 and rotor lamination-ring 11. An annular duct 22, for injecting the granular material, is provided in the upper part of the housing wall, with a con-nector 7 opening into the said duct. Located at the opposite,i~e. the lower, end-face of the housing is a funnel-shaped coarse-material outlet 8.
Located at each end-face of the sifting rotor is a fine-material/sifting-air outlet 3, 4 in the form of a curved piece of pipe, the diameter of which corresponds approximately to the inside diameter of the rotor.
Sifting-air/fine-material outlets 3, 4 are each sur-rounded by a cooling-air chamber 17, 18 to each of which cooling air is supplied through a connection 19 which prevents fine material from being deposited in the said outlets. Also mounted in cooling-air chambers 17, 18, at both ends, in bearing brackets 5, 6, is the rotor-shaft lOa which passes through curved outlets 1 16~gl , 4. The bearin~s are thus also cooled. Due to the positive pressure obtaining in the said cooling-air chambers, no fine material can enter them (see arrows in shaft lead-throughs).
Dr:ive is by a V/belt pulley 12.
Sifting rotor 10 is open at both end-faces in such a manner that it is sealed to outlets 3, 4. Located between the sifting rotor and the housing is a seal 15, 16 in the form of a flat disc or a labyrinth. Flushing air is introduced froin cooling-air chambers 17, 18, through a duct 27, to provide a ; 10 seal between sifting area 23 and outlets 3, 4 (arrow 19 in Figure 3).
Support-discs 24, equipped with radial passages, are shrunk onto shaft lOa of the sifting rotor. The outer periphery of each end of the rotor is surrounded by a deflector ring 25, 26.
, .
,.
-5a-,, .
.
' ~
Claims (7)
1. A centrifugal classifier having a substantially cylindrical, upright housing with an approximately tangential sifting-air inlet, in which are arranged, at a radial distan-ce from, and centrally of, the casing of the housing, a vane-ring and, at a radial distance inwardly therefrom, a sifting rotor with a lamination-ring forming radial passages, an inlet for the granular material to be classified opening, at the top, into the classifying area located between the said vane-ring and sifting rotor, and an outlet for the sifting air, charged with fine material, being located adjacent the rotor, the diameter of the said outlet corresponding approximately to the inside diameter of the said rotor, and the sifting-air inlet and the vane-ring extending over approximately the same axial length as the rotor, characterized in that the two end-faces of the sifting rotor are each located adjacent a fine-material/sifting-air outlet.
2. The classifier according to claim 1, characte-rized in that the diameter: length ratio of the sifting rotor is between 1 : 1,5 and 1 : 4.
3. The classifier according to claim 1, characteri-zed in that each of the two fine-material/sifting-air outlets is surrounded, in the vicinity of the rotor, by a cooling-air chamber.
4. The classifier according to claim 3, characteri-zed in that each of the bearings of the sifting-rotor shaft, which is mounted at both ends, is arranged in a cooling-air chamber.
5. The classifier according to claim 4, characteri-zed in that a labyrinth-seal is provided at each end-face of the sifting rotor, each seal communicating, through a duct, with one of the cooling-air chambers.
6. The classifier according to claim 5, characteri-zed in that support-discs, equipped with axial passages, for retaining the laminations of the sifting rotor, are shrunk onto the shaft.
7. The classifier according to one of the claims 1, 4 or 6, characterized in that an annular duct for injecting the material to be sifted into the classifying area is provided at the end-face of the housing facing the coarse-material outlet.
-? -
-? -
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000380435A CA1160991A (en) | 1981-06-23 | 1981-06-23 | Centrifugal classifier |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000380435A CA1160991A (en) | 1981-06-23 | 1981-06-23 | Centrifugal classifier |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1160991A true CA1160991A (en) | 1984-01-24 |
Family
ID=4120307
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000380435A Expired CA1160991A (en) | 1981-06-23 | 1981-06-23 | Centrifugal classifier |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1160991A (en) |
-
1981
- 1981-06-23 CA CA000380435A patent/CA1160991A/en not_active Expired
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4786406A (en) | Particle classifier with wear-resistant classifier wheel | |
| EP0487833A2 (en) | Continuous air-swept type planetary ball mill | |
| EP1750861B1 (en) | Particle classifier | |
| US4528091A (en) | Particle classifier | |
| US4390419A (en) | Centrifugal classifier | |
| GR3030663T3 (en) | Agitator mill with separator for retaining milling beads | |
| US5032222A (en) | Spray drier for the preparation of powders, agglomerates and the like | |
| US4691448A (en) | Apparatus and process for drying finely grained solid particles | |
| US4409097A (en) | Improved pivotable centrifugal classifier and method of classifying | |
| US3089595A (en) | Flow apparatus for separating granular particles | |
| US4626343A (en) | Separator for sorting particulate material | |
| CA1160991A (en) | Centrifugal classifier | |
| US4511462A (en) | Method and apparatus for sorting particulate material | |
| US6109448A (en) | Vertical-axis air classifier | |
| US5791490A (en) | Separator for particulate materials | |
| EP0819030B1 (en) | Apparatus for classification of particulate material | |
| CA1160990A (en) | Pivoting centrifugal classifier | |
| US2943735A (en) | Particle classifiers | |
| US6260708B1 (en) | Method for air classification of toner | |
| JP2969555B2 (en) | Centrifugal classifier | |
| CA2171890C (en) | Centrifugal force separator | |
| CA2303742A1 (en) | Centrifugal separator | |
| JP4026051B2 (en) | Classifier | |
| JPS6017592B2 (en) | centrifuge separator | |
| SU1346275A2 (en) | Air centrifugal classifier for powder-like materials |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |