GB2116883A

GB2116883A - Centrifugal separator

Info

Publication number: GB2116883A
Application number: GB08208313A
Authority: GB
Inventors: Nikolai Emelyanovich Avdeev; Evgeny Alexeevich Alabin; Alexandr Gerasimovich Balyasov; Mikhail Andreevich Boriskin; Evgeny Leonidovich Orlov; Anatoly Fedorovich Prokopenko; Evgeny Vladimirovich Tamarov; Jury Alexandrovich Salikov
Original assignee: VNI EX K I PRODOVOLST; VNII KOMBIKORMOVOI PROMY; VORONEZH TEKH INST
Current assignee: VNI EX K I PRODOVOLST; VNII KOMBIKORMOVOI PROMY; VORONEZH TEKH INST
Priority date: 1982-03-22
Filing date: 1982-03-22
Publication date: 1983-10-05
Also published as: DE3209309C2; CH659008A5; DE3209309A1; FR2523873A1; FR2523873B1; GB2116883B

Abstract

A centrifugal separator comprises a housing accommodating a rotor capable of rotating around a vertical axis, the rotor having blades (6) positioned at an angle to a vertical plane passing through the axis of rotation of the rotor (4). The material to be separated is admitted axially of the rotor (4) from a loading means (15) through an axial passageway (9) of the rotor (4) to be delivered to the rotor blades (6). Separation of the material into fractions is effected by passing the material through outwardly diverging sizing slots (17) provided in the blades (6) and disposed one above the other. The separated line fraction passing through the slots impinges upon baffles (18) which are equal in number to the number of the blades (6) and which direct the fraction towards discharge means 22. The coarse fraction is discharged towards discharge means 21. <IMAGE>

Description

SPECIFICATION Centrifugal separator This invention relates to apparatus for separating into fractions or sizing heterogeneous mixtures, of predominantly solid loose materials, undertheac- tion of inertial, particularly centrifugal, forces and more specifically concerns centrifugal separators.

The invention is applicable to the fractionation of solid loose materials with particle sizes ranging from tenths of 1 mm to 15 mm and larger.

The invention can be employed by the food, flour-and- cereal industries, in animal feed manufacture and in agriculture for fractionating, sizing and classifying grain and for separating impurities from grain.

The proposed centrifugal separator can also be used in the chemical, construction, or benefication and coal mining industries for sizing granulated and loose materials such as sand or gravel.

It can be further used as successfully for separating solids from liquids, such as during removing water from coal fines or extracting juice from fruit.

The invention provides a centrifugal separator comprising a housing accommodating a rotor capable of rotating around a vertical axis with blades positioned at an angle to a plane passing through the rotor axis and imparting under the action of centrifugal forces a direction to a material being separated for the latter to travel from the axis of rotation of the rotor towards its periphery, the material being admitted into the separator axially of the rotor through a loading means to pass further downwards along an axial passageway to the rotor blades, separation of the material into fractions being effected through main sizing slots arranged on the blades and adapted to diverge from the axis of rotation of the rotor toward it's periphery, the separated fractions being discharged by way of baffles equal in number to the number of blades and each secured in close proximity to the corresponding blade on the side of the blade opposite the direction of rotation of the rotor, each of the blades having at least one additional sizing slot similar to the main one, the main and additional sizing slots being arranged in a sandwich fashion longitudinally of the axis of rotation of the rotor.

In order to prevent the separated particulate material from being jammed in the sizing slots, peripheral ends of the blades are preferably bent in a direction which is counter to the direction of rotation of the rotor, the line of bend crossing the main and additional sizing slots.

It is preferable, when employing a plurality of sizing slots in each blade of the centrifugal separator according to the invention, that the loading means be comprised of flat rings for distributing the material being separated across the height of the blade, the flat rings being positioned concentrically of the axial passageway of the rotor in parallel arrangement with each other, the inner diameters of the rings being adapted to reduce from the upper toward the lower ring.

Preferably, each of the flat rings has an iris-type diaphragm.

According to another aspect of the invention, it is also preferable that the loading means should have spacing sleeves interposed between the flat rings so as thereby to adjust the distance therebetween.

According to one more aspect of the invention, it is further preferable that each of the rotor blades should be fashioned as a plate with the main and additional sizing slots arranged equidistantlythere- on, the width of the blade portions between the slots approximating to the width of the slots.

In order to increase the efficiency of separating fine fractions it is convenient that the blades should be curved on an arcuate cylindrical surface, the generatrix of which is parallel with the axis of rotation of the rotor, their concave sides conforming to the direction of rotation of the rotor.

In order to increase the efficiency for separating fine fractions, the blade portions between the sizing slots are preferably bulged in cross-section, the bulges conforming to the direction of rotation of the rotor.

In order that the blades of the rotor shall be more resistant to wear, according to yet another aspect of the present invention, each of the blades may consist of a plurality of rods secured cantilever fashion at their ends to form sizing slots therebetween; alternatively, the plurality of rods may be secured at both their ends.

For preventing large particles of the material being separated from being jammed in the sizing slots, it is advisable that the rods be fixed together in a cantilever fashion and that spacers be interposed between the rods to form sizing slots diverging toward the unsupported or free ends of the rods.

This structural modification of the centrifugal separator affords, with equal lengths of sizing slots and with an equal number of blades as compared with the known apparatus, an increase in efficiency which is proportional to the number of sizing slots arranged in each of the blades. In fact, the efficiency of the separator modified in such a manner may be increased from 2 to 3.5 times without affecting the rate of separation of the fine fraction as compared with the known separator.

In addition, the above proposed modification of blades simplifies the construction of the separator, since the sizing slots are arranged on the blades.

A major advantage of the proposed separator is that it has an at least twice smaller volumetric capacity compared with the known separators.

The invention will now be described in greater detail with reference to various preferred embodiments which are illustrated in the accompanying drawings, in which: Figure 1 is a sectional elevation of a centrifugal separator according to the invention; Figure 2 is a view of one modification of a rotor blade in the form of a slotted plate; Figure 3 shows another modification of the rotor blade in the form of a slotted plate having a bent peripheral end; Figure 4 is a view of a modification of the rotor blade in the form of a slotted plate curved on an arcuate cylindircal surface; Figures 5a, 5b and 5c are cross-sectional views of alternative modifications of the rotor blade; Figure 6 is a modification of the rotor blade comprised of a plurality of rods fixedly secured at both their ends;; Figure 7 is a sectional elevation of another modification of the rotor blade comprised of a plurality of rods secured together at one side of the blade; Figure 8 is a section along line VII - VII of Figure 6; Figure 9 is a plan view of the rotor showing three of its blades; Figures iota, lob, lox and 10darecross-sectional views of alternative configurations of the rods comprising the rotor blade; Figure 11 is a sectional elevation of a centrifugal separator according to the invention wherein a loading means has rings; Figure 12 is an enlarged sectional elevation of the loading means; Figure 13 is a view along the arrow A of Figure 11; and Figure 14 is an isometric view of a section of the centrifugal separator illustrating the process of fractionation of a material being separated.

With reference to Figure 1, there is shown a centrifugal separator comprising a cylindrical housing 1 having a top lid 2 and mounted on a base 3. A rotor 4 is arranged along the axis of the upper portion of the housing 1. The rotor 4 includes a discS to which there is attached, such as by a threaded connection, blades 6 (one blade 6 being shown in Figure 1 for the sake of convenience). The blades 6 are arranged vertically and equidistantly at an angle to a plane passing through the axis of rotation of the rotor 4 and spaced a certain distance from this axis of rotation, that is the plane of each blade 6 fails to pass through the axis of rotation of the rotor 4; the blades are fixed in position in the upper portion of the rotor 4 by a ring 7.Each blade 6 has its end which faces the axis of rotation of the rotor 4 mated with a guide 8 which is rigidly connected to the blade 6, the guides 8 being in the form of plates arranged radially at a certain distance from the axis of rotation of the rotor 4 such that an axial passageway 9 is formed for feeding a product to tbe separated. The disc 5 of the rotor 4 is secured on a shaft 10 journaled in bearings 11. The shaft 10 is connected with an electric motor 13 by means of a V-belt transmission 12. The bearings 11 and electric motor 13 are mounted on a support plate 14.

The separator has a loading means which includes a hopper 15 arranged in the lid 2 axially of the rotor 4 and a distributing cone 16 secured on the disc 5.

In order to separate coarse and fine fractions of a material charged into the separator, the blades 6 are provided with slotted sizing apertures 17, the slots diverging in the direction from the axis of rotation of the rotor 4 toward the periphery. In the embodiment illustrated in Figure 1 each blade 6 has three sizing slots 17. Rotation of the rotor 4 causes its blades 6 to impart movement to the material being separated, directed under the action of centrifugal forces, for the axis of rotation of the rotor 4 towards the periphery. The number of the blades 6 is determined by the size of the disc 5, as well as by the length and number of the sizing slots 17 in each of the blades 6, the number of the sizing slots 17 being in tum dictated by the required capacity ar, efficiency the separator.

For the discharge of the material being separated, the separator has baffles 18 equal in number to the number of the blades 6, and cylinders 19 and 20 arranged in the interior of the housing 1 to form chambers 21 and 22 intended to collect the discharged fractions. Discharge ducts 23 rigidly connected with the baffles 18 are further provided to direct the fractions being separated into the corresponding chamber 21 or 22.

In the embodiment of the separator shown in Figure 1 the fine fraction is discharged into the chamber 21, while the chamber 22 is adapted to receive the coarse fraction.

The number of cylinders inside the housing 1 is determined by the preselected number of fractions to be separated. If required, additional cylinders (not shown) may be mounted on slopes 24.

The blades 6 may have various configurations, depending on what the separator is intended for.

Figure 2 shows an alternative modification of the baffle 6 in the form of a plate 25 with equidistant sizing slots 26.

The sizing slots 26 diverge towards one end of the plate 25. The dimensions of the slots 26 (length, minimum and maximum width) are chosen according to the intended purpose of the separator. The width of the plate portions 27 between the slots 26 is commensurate with the width of these slots.

The modification of the blade 6 shown in Figure 2 is employed predominantly in separators intended for separating loose food products, such as grain and crushed grain products, as well as for extracting juice from fruit.

Referring to Figure 3, there is shown another modification of the blade 6 in the form of a plate 28 with a bent end.

In orderto prevent a particulate product being separated from being jammed in the sizing apertures or slots during the separation of particles of which the size exceeds the maximum width of such apertures, the peripheral end of the plate 28 is bent in a direction which is counter to the direction of rotation of the rotor 4, the line of bend crossing the slots.

Figure 4 shows an alternative modification of the blade 6 in the form of a plate 29 bent on an arcuate cylindrical surface. Because the efficiency of separation of the fine fractions depends on the speed of movement and the structural/mechanical properties thereof, such a shape of the blade 6 allows the speed of travel of the product particles to be reduced in the course of their movement along the blade 6, which is especially important for its peripheral portion. The use of blades 6 of this construction is most preferable to separate a product containing large amounts of particles with sizes approaching the maximum width of the slots.

The radius R of the arcuate cylindrical surface is chosen to take into consideration the structurall mechanical properties of the product being separated to obtain the optimum speed of travel of the product longitudinally of the blade 6.

This arrangement of the blade, as compared with the rectilinear blade, affords an equal efficiency of fine fractin separation to reduce the dimensions and weight of the separator and to bring down the energy costs for its operation.

In Figure 5, there are shown various alternative modifications of the cross-sectional configuration of the blade 6 made from the plates 25, 28 and 29. Plate portions 27 (Figure 5a) between the slotted apertures 26 are rectangular in cross-section. Plate portions 30 (Figure 5b) and 31 (Figure 5c) of the blade 6 are buled or of curved cross-section, the bulges conforming to the direction of rotation of the rotor 4. The plate portions 30 are angular in cross-section, while the plate portions 31 are arcuate.

The shaped cross-sectional configuration of the plate portions 30 and 31 between the sizing slots makes it possible, as compared with the employment of the flat portions 27, to increase the efficiency of separation of the fine fraction, other conditions being equal (same size of the slotted apertures and same material subjected to separation).

In orderthatthe blade space be more resistant to wearwhen the separator is used for sizing loose building material, such as sand or gravel, the blade 6 is preferably made up of a plurality of rods 32 (Figure 6) arranged one above the other and secured at the ends so as to form slotted sizing apertures 33 therebetween, the rods 32 being preferably welded to support plates 34 and 35 so that the slots 33 diverge towards the plate 34.

In order to ensure that jamming of the material being separated with a particle size in excess of the maximum width of the slotted apertures and fibrous particles is prevented, the blade 6 is preferably composed of rods 36 (Figures 7 and 8) arranged one above the other with their ends facing the axis of rotation of the rotor 4 secured in a holder 37 between wedged spacers 38, the thickness of the spacers 38 being such as to form between the rods 36 sizing slots 39 of required width.

The holder 36 is fashioned as a cylinder having a groove 40 (Figure 8) extending axially therealong and accommodating alternatively stacked rods 36 and wedged spacers 38 pressed together by means such as a screw 41. The screws 41 (Figure 9) also function to secure the blades 6 to the ring 7, three such blades being shown in this figure, two of the three having baffles 18.

Figure 10 illustrates various modifications of the cross-sectional configuration of the blade 6 composed of rods. Thus: Rods 32 (Figures 6 and 10a) have a rectangular shape; rods 36 (Figures 7,8 and 10a) are of circular cross-section; rods 42 (Figure 10c) have the shape of a hexahedron,while rods 43 (Figure 10d) have the shape of a hexahedron, while rods 43 (Figure 1 Od) are square. The blades 6 fabricated from the rods 36, 42 and 43 afford a higher efficiency of separation of fine fractions compared with the blades 6 made up of rods 32.

The heretofore described modifications of the blades 6 illustrated in Figures 2,6 and 7 are of sufficient height, since the blades have from five to sixteen sizing slots.

Referring now to Figure 11,there is shown an embodiment of the separator according to the invention wherein the loading means additionally comprises flat rings 44,45 and 46 intended to distribute the material being separated vertically of the blades 6. The rings are positioned horizontally at equal distances from each other. The outer diameters of the rings 44,45 and 46 are equal, although these diameters are of essentially lesser diameter than the inner circumference of the rotor 4 on which the inner ends of the blades 6 are secured. The inner diameters of the rings 44,45 and 46 are reduced in value in the direction from the upper ring 44 toward the lower ring 46. In this embodiment of the separator the blade 6 is composed of the rods 36 (Figure 7).The coarse fraction of the material being separated is discharged into the chamber 21, whilst the fine fraction is discharged into the chamber 22.

For directing the fractions of the material being separated into the appropriate chambers, each blade 6 has an outlet duct 47, while baffles 48 have outlet ducts 49. Other elements of the centrifugal separator are similar to those of the modification described with reference to Figures 1.

As shown in Figure 11, the rings 44,45 and 46 are secured on the disc 5 by means of three pins 50, the rings spaced by sleeves 51 arranged on the pins 50 between the rings 44, 45 and 46. The number of rings may range from one to ten depending on the height of the blades 6 which is determined by the number of sizing slots required. The spacings between the rings may also vary. They are selected experimentally and generally depend on the mechanical properties of the material being separated. Variations in the spacings between the rings are effected by the employment of sleeves 51 of various lengths.

In addition, adjustment of the separator for operation with materials exhibiting various physical and mechanical properties is effected by a special provision which permits alteration of the inner diameters of the rings 44,45 and 46. For this purpose, each of the rings 44,45 and 46 has an iris diaphragm comprising a set of leaves 52 with slots 53. These leaves 52 are attached to the corresponding rings 44, 45 and 46 by means of screws 54 received by the slots 53.

In Figure 14 the arrows illustrate a process of separating a material into two fractions along paths of travel of the material particles.

The centrifugal separator according to the invention operates in the following manner.

The rotor 4 (Figure 1) is rotated by the motor 13.

The material to be separated is admitted to the separator through the hopper 15 of the loading means to fall onto the distributing cone 16, from where it is directed towards the guides 8 arranged radialiy vertically on the disc 5. By virtue of the fact that the guides 8 are disposed radially, particles of the material being separated are acted upon by centrifural and Coriolis inertia forces of considerable magnitude. These forces act to impart to the material a speed of 2 to 4 m/s and distribute the material along the height of the guides 8. The uniform distribution is further facilitated by the forces of gravity and the flow of air running against the material.Therefore, the material is delivered onto the blades 6 in a uniform layer and at a high speed which provides a very efficient passage of the material through the sizing slots 17 arranged in the blades 6, thereby increasing the efficiency of the centrifugal separator.

The speed of the material being separated is accelerated further in the course of its travel along the blades 6 from the centre towards the periphery.

When there is an increase in the speed of the material the Coriolis inertia forces acting on the material in a direction which is perpendicular to the plane of the sizing slots 17 tend to grow in magnitude. Therefore the particles travelling along the blades 6 are separated through the slots 17 under the action of a combination of the Coriolis and centrifugal component forces acting perpendicularly to the plane of the sizing slots 17 in the area thereof corresponding to the size of the particles.

This results in a very active separation of the particles having a size essentially corresponding to the maximum width of the sizing slots and permits a highly efficient separation of the fine fraction. The fine fraction enters the chamber 21, while the coarse fraction enters the chamber 22.

The centrifugal separator shown in Figures 11,12, 13 and 14 is similar to what has been described herebefore, the difference being in the operation of the charging device. The material to be separated is admitted through the hopper 15 onto the rings 44,45 and 46. By virtue of the fact that the inner diameters of the flat rings 44,45 and 46 are reduced in a downward direction, the material is divided into four streams, the lower stream directly entering the disc 5 of the rotor 4, while the upper streams are distributed among the rings 44,45 and 46.

The rings 44,45 and 46 being rotated together with the rotor 4, the material under the action of centrifugal forces is caused to flow horizontally on the surface of the rings towards their periphery reaching a speed of between 0.5 and 1 m/s. The provision of these rings 44,45 and 46 enables the material to be distributed uniformly along the height of the blade 6 in cases where the number of the sizing slots 39 is sufficiently large.

The fine fraction of the material subsequent to its separation through the sizing slots 39, is directed by baffles 48 toward the outlet ducts 49 to be thereafter delivered to the chamber 22 for further use. The coarse fraction with particles of size in excess of the maximum width of the sizing slots 39 is guided to the chamber 21 from where it is discharged for further use.

This arrangement of the centrifugal separator is sufficiently versatile to allow separation of materials having widely ranging structural and mechanical properties. When employed with hard-to-loose materials, the inner diameters of the rings are increased by moving the leaves 52 (Figures 12, 13) of the iris diaphragm. This is also accompanied by an increasing of the distance between the rings 44,45 and 46 by changing the sleeves 51.

When employing other modifications of the blade 6 as illustrated in Figures 2,3,4 and 6, separation of a material into fractions is carried out similarly to what has already been described.

Claims

1. Acentrifugal separator comprising a housing accommodating a rotor capable of rotating around a vertical axis with blades positioned at an angle to a plane passing through the rotor axis and imparting under the action of centrifugal forces a direction to a material being separated for the latter to travel from the axis of rotation of the rotor toward the periphery thereof, the material being admitted into the separ atoraxiallyofthe rotorthrough a loading means to pass further downwards along an axial passageway to the rotor blades, separation of the material into fractions being effected through main sizing slots arranged on the blades and adapted to diverge from the axis of rotation of the rotor toward the periphery thereof, the separated fractions being discharged by way of baffles equal in number to the number of blades and each secured in close proximity to the corresponding blade on the side thereof opposite the direction of rotation of the rotor, each of the blades having at least one additional sizing slot similar to the main ones, the main and additional sizing slots being arranged successively longitudinally of the axis of rotation of the rotor.

2. A centrifugal separator according to claim 1 wherein peripheral ends of the blades are bent to a side counter to the direction of rotation of the rotor, the line of bend passing across the main and additional sizing slots.

3. A centrifugal separator according to claim 1 or claim 2 wherein, along with a plurality of sizing slots in each of the blades, the loading means comprises flat rings for distributing the material being separated across the height of the blades, the flat rings being positioned concentrically of the axial passageway of the rotor in a parallel relationship between each other, the inner diameters of the rings being adapted to reduce in a direction from the upper toward the lower ring.

4. A centrifugal separator according to claim 3 wherein each of the flat rings has an iris-type diaphragm.

5. A centrifugal separator according to any of the claims 3 or 4 wherein the loading means has spacing sleeves interposed between the flat rings to adjust the distance therebetween.

6. A centrifugal separator according to any of the claims 1 to 5 wherein each of the rotor blades has the form of a plate with the main and additional sizing slots arranged at equal distances from each other, the width of the blade portions separating the sizing slots approximating to the width of the slots.

7. A centrifugal separator according to claim 6, wherein the rotor blades are bent along a circular cylindrical surface whose generatrix is parallel to the rotational axis of the rotor, the concave side of the blades conforming to the direction of rotation of the rotor.

8. A centrifugal separator according to any of claims 6 or 7, wherein the plate portions between the sizing slots are of bulged cross-section, the bulges conforming to the direction of rotation of the rotor.

9. A centrifugal separator according to any of claims 1 to 5, wherein each of the rotor blades is composed of a plurality of rods secured so that sizing slots are formed therebetween.

10. A centrifugal separator according to claim 8 wherein the rods are fixedly secured at both ends.

11. A centrifugal separator according to claim 8 wherein the rods are secured together by their ends which face the rotor axis, a plurality of spacer elements being interposed between the rods to form between the thus secured rods sizing slots diverging from the secured ends toward the non-secured ones.

12. A centrifugal separator substantially as heretofore described with reference to any of the accompanying drawings.