EP4059625A1 - Dispositif et procédé de criblage de marchandises pulvérulentes - Google Patents

Dispositif et procédé de criblage de marchandises pulvérulentes Download PDF

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Publication number
EP4059625A1
EP4059625A1 EP22000049.1A EP22000049A EP4059625A1 EP 4059625 A1 EP4059625 A1 EP 4059625A1 EP 22000049 A EP22000049 A EP 22000049A EP 4059625 A1 EP4059625 A1 EP 4059625A1
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EP
European Patent Office
Prior art keywords
wheel
classifying
classifying wheel
classifier
blades
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.)
Pending
Application number
EP22000049.1A
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German (de)
English (en)
Inventor
Stefano L. Zampini
Benjamin BIBER
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hosokawa Alpine AG
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Hosokawa Alpine AG
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Hosokawa Alpine AG filed Critical Hosokawa Alpine AG
Publication of EP4059625A1 publication Critical patent/EP4059625A1/fr
Pending legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
    • B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
    • B07B7/00—Selective separation of solid materials carried by, or dispersed in, gas currents
    • B07B7/08—Selective separation of solid materials carried by, or dispersed in, gas currents using centrifugal force
    • B07B7/083—Selective separation of solid materials carried by, or dispersed in, gas currents using centrifugal force generated by rotating vanes, discs, drums, or brushes

Definitions

  • the invention relates to a classifying wheel for a centrifugal air classifier according to the preamble of claim 1 and a method for separating classified material dispersed in a classifying fluid into a fine and a coarse fraction according to the preamble of claim 11.
  • Air classifiers are used to separate a material dispersed in a fluid into a fine and a coarse fraction.
  • the separating effect of a classifying wheel is based on the fact that the drag force of the fluid and the centrifugal force in the flow channels between the classifying wheel blades of a classifying wheel, the so-called deflector wheel, act in opposite directions on the individual particles of the solid.
  • the drag force predominates, so that they are carried along by the fluid and discharged as fines.
  • the centrifugal force predominates, so that they are thrown out of the deflector wheel against the fluid flow.
  • the particle size for which centrifugal force and drag force are in equilibrium i.e. which is equally likely to end up in the fine or coarse material, is referred to as the cut-off size or cut-off point.
  • Centrifugal air classifiers with a deflector wheel are one of the preferred classifiers for producing very fine classifying materials with relatively little energy consumption. For a sharp separation of the sifted material into fine material and coarse material it is necessary that in all flow channels of the deflector wheel there is a uniform flow with the same mean radial velocity of the fluid.
  • deflector wheels according to the prior art cannot be used to enable a uniform flow in the flow channels.
  • the annular arrangement of vanes causes the angular velocity of the flowing fluid within the flow channel defined by the vanes to be constant at any radial distance from the axis of rotation of the classifier wheel.
  • the solid-body vortex that occurs in this way has the property that the separation limit is smallest on the outer circumference of the classifying wheel. The further the fluid, together with the particles dispersed in it, penetrates into the inside of the wheel, i.e. the smaller the radius, the greater the separation limit.
  • flow breakers are to be attached to the boundary walls of the blades in the radially central area of the flow channel in such a way that the fluid flow penetrating the flow channels is already broken in the first radial third of the flow channel and vortex formation can only occur in this third of the flow channel. Since the vortices are the reason for the suction of coarse particles, coarse particles are no longer sucked so far into the flow channels if the vortices form as far as possible in the area of the outer circumference of the classifying wheel. If the coarse particles can penetrate less far into the classifying wheel, then it is also less heavily loaded with coarse particles and the probability that coarse particles can penetrate the interior and thus get into the fines is greatly minimized.
  • the flow breaks up in classifier wheels whose peripheral speed (v s ) is greater than the speed of the fluid flowing along the outer circumference of the deflector wheel (v ⁇ ,) on those boundary surfaces of the classifier wheel blades that are at the front in the direction of rotation.
  • the flow in classifier wheels whose peripheral speed (v s ) is less than the speed of the fluid flowing along the outer circumference of the deflector wheel (v ⁇ ,), breaks up on those boundary surfaces of the classifier wheel blades that are at the rear in the direction of rotation.
  • the known sight wheels are limited in their fineness. You can't keep up with the desire for higher subtleties. It has been shown that the previous geometries do not allow any improvement in the subtleties.
  • the sifting process takes place through a force balance of repelling centrifugal force and transporting drag force. For finer sifting, higher speeds are required, i.e. higher centrifugal forces. The forces acting on the components limit the speed upwards. The reduction of the towing power remains for finer sightings. It was found that when the flow falls below a limit, the flow becomes unstable and there is no further increase in fineness.
  • the object of the invention is therefore to provide a sifting wheel and a sifting method which expands the fineness range of existing air classifiers in order to achieve an even greater fineness than before.
  • the classifying wheel according to the invention for a centrifugal force air classifier is rotationally driven in this and is flowed through from outside to inside against its centrifugal direction. It has classifying wheel vanes arranged in a ring between two retaining disks.
  • the classifier wheel vanes and the retaining disks delimit flow channels.
  • the flow influencing internals are arranged, which are provided on the front side of the classifier blade in the direction of rotation in the radially outer third of the classifier radius, so that the flow channels between the classifier blades has at least one of two constrictions delimited widening.
  • the bottlenecks limit the sifting vortex that forms from the inflowing sifting fluid.
  • the sifting wheel according to the invention has specially shaped flow ducts, which further influence the formation of vortices in the flow ducts positively for the sifting.
  • the classifying wheel channels according to the invention which are delimited by the classifying wheel blades and retaining disks, have a constriction from radially outside inwards, then a widening and finally a constriction again, i.e. at least one widening limited by two narrow points. This shape is achieved by fittings in the flow channels.
  • These internals are arranged in the radially outer third of the classifying wheel radius. They are on the front side of the classifier wheel blades in the direction of rotation.
  • the sifting vortex that forms from the inflowing sifting fluid is limited on both sides and stabilized in terms of location and time.
  • the size of the turbulence and the location of the turbulence in the flow channel are defined by the bottlenecks. It is also more stable and shows less fluctuations over time. These measures have a defined influence on the fineness.
  • the classifying wheel blades do not run exactly in the radial direction, but are inclined or rotated at an angle to the radial direction against the direction of rotation, so that they are predominantly aligned repelling.
  • the classifier blades thereby form a flow channel with a kinked Course from so that the flow channel is oriented repellent in its central position.
  • the kink in the classifying wheel blades or the flow channel is in the outer radial third of the classifying wheel in relation to the classifying wheel radius.
  • the classifying wheel blades extend into the inner two-thirds of the classifying wheel, based on the classifying wheel radius, the classifying wheel blades remain radially aligned in the inner area.
  • the classifying wheel blades are arranged at an angle or rotated in the outer area to the radial direction. In the radially outer third, based on the radius of the classifying wheel, they are preferably oriented in a repelling manner.
  • One embodiment of the invention is characterized by a continuous contour profile of the specially shaped outer area of the classifying wheel blades that is oriented to repel, the distance between two adjacent classifying wheel blades viewed from the outside inward initially narrowing, followed by a widening before the distance widens narrowed again.
  • the classifying wheel blades delimiting the flow channel are also oriented repellingly, i.e. inclined in the radially outer area of the blades against the direction of rotation of the classifying wheel.
  • the blades in the radially outer third of the flow channel are oriented in a repelling manner in relation to the classifying wheel radius.
  • the radially outermost area of the classifier blade is bent forwards in the direction of rotation of the classifier wheel.
  • the buckling forward of the outermost area of the classifier wheel blades can be pronounced to different extents.
  • This outermost element which also represents an internal, can be designed, for example, in such a way that it is formed radially to the classifying wheel axis. Furthermore, the classifier blade has another built-in component in the radially outer third of the classifier wheel radius.
  • the outermost element and the internals represent the constrictions between the widening of the flow channel. They limit the view vortex that forms. They define the location and size of the vortex.
  • the outermost element is bent forward more than would correspond to a radial orientation with respect to the axis of the separating wheel.
  • the bent outer end of the classifying wheel blade can be bent so slightly that it is still designed to be repellent.
  • the external built-in components viewed from the outside inwards, i.e. the external constriction, close off the outer circumference of the classifying wheel, regardless of the diameter of the retaining disks, e.g.
  • the contour in the radially outer third, based on the classifying wheel radius, of the flow channels consisting of a constriction, an expansion and a constriction in cross section is formed by a continuously curved curve.
  • the specially shaped contour has kinks, corners and edges that occur as a result of the assembly of two or more straight, curved or kinked parts using a suitable manufacturing process.
  • a continuous course means here that the contour of the sifting wheel blades in the area of the sifting vortex is formed without corners and edges.
  • a discontinuous course means that the contour of the classifier wheel blades has at least one edge or a kink in the area of the classifying vortex. With kinks and edges, production-related edges such as e.g. weld seams can also be understood here.
  • the internals preferably have a square, rectangular, triangular or round cross-section, but any other cross-sectional shape can also be used, depending on the application.
  • the internals and thus the specially shaped areas of the classifying wheel blades extend axially over their entire height. This is equivalent to that the contour of the flow channels extends over the entire axial height of the classifying wheel.
  • the internals or the specially shaped areas of the classifying wheel blades are preferably located on a common radial circular path that lies in an area within the outer third of the classifying wheel radius.
  • the internals are arranged on the front side of the classifying wheel vane in the direction of rotation of the classifying wheel.
  • the rear side of the classifying wheel vane in the direction of rotation has no internals.
  • the retaining disks between which the classifying wheel blades are arranged can be designed as cover disks and/or hub disks.
  • the cover disk is provided with a fines outlet. It is preferably designed in the form of a ring.
  • the hub disk can also have openings through which the fines can flow.
  • the classifying wheel according to the invention can be designed either as a single-flow or as a double-flow.
  • a double-flow classifying wheel can be composed of two single-flow classifying wheels.
  • the classifying wheels are assembled on their cover disks so that they have a common axis of rotation.
  • the double-flow sifter wheel now has two hub disks and is mounted on both sides in the housing of the centrifugal air sifter.
  • the two hub disks have openings that represent the outlets for the fines.
  • the cover disks in the middle of the double-flow classifying wheel are omitted, so that it has a continuous inner area.
  • the flow channels of the classifying wheel have at least one expansion limited by two constrictions.
  • the ratios of the distances between the classifier wheel blades at these points can be described using the arc lengths at the constrictions and the widening.
  • the arc length a describes the distance between two adjacent classifier wheel blades at the radius r(a) of the classifier wheel at the level of the radially outer constriction.
  • the arc length b describes the largest distance between the two adjacent classifier wheel blades at the radius r(b) of the classifier wheel. It describes the spacing of the classifier wheel blades at the widening between the constrictions.
  • the arc length c describes the distance between the two adjacent classifier wheel blades at the radius r(c) of the classifier wheel at the level of the radially inner constriction.
  • the factor x has a value >0.5, preferably 0.5 ⁇ x ⁇ 3.
  • the invention relates to a method for separating a sifting material dispersed in a sifting fluid into a fine fraction and a coarse fraction.
  • a classifying vortex is formed from the classifying fluid flowing in due to the contour of the flow channels, caused by the internals.
  • the visibility vortex is limited on both sides by internals.
  • This classifying vortex has a flow velocity that is higher than when the classifying vortex is only limited on one side by internals. It is therefore more stable and shows fewer fluctuations over time.
  • the described shape of the flow channels ensures that the degrees of freedom of the particle-laden classifying fluid when it flows onto the classifying wheel are restricted in such an advantageous manner that the momentum of the classifying fluid flowing against it can be converted as completely as possible into a high speed in the classifying vortex.
  • a classifying zone is formed between the classifying wheel blades, which zone is located between two stagnation points, with the first stagnation point being located on the front side of the classifying wheel blades in the direction of rotation of the classifying wheel.
  • the second stagnation point consequently lies on the rear side of the classifying wheel blades of the classifying wheel in the direction of rotation of the classifying wheel.
  • the stagnation points limit the vortex size. As a result, higher finenesses and a higher fines extraction can be achieved.
  • this variant is particularly well suited aerodynamically and converts the impulse of the oncoming fluid most effectively into an increase in the speed of the fluid in the sifting vortex.
  • a flow rate in the sifting vortex can be achieved that corresponds to twice the peripheral speed of the sifting wheel.
  • the variants which have discontinuous profiles of the specially shaped classifying wheel blades due to kinks and edges, are not as efficient as variants with continuous contours due to losses in momentum exchange. Since the variants with kinked ends of the separator vane do not convert the momentum of the inflowing fluid as efficiently, the speed increases are lower there in comparison to continuous contours. However, these classifying wheels are more economical to manufacture.
  • the figure 1 shows a preferred embodiment of the classifying wheel (10) according to the invention for a centrifugal force air classifier. It comprises a hub disc (2) carrying the classifying wheel hub (1) and a cover disc (4) with a fines outlet.
  • the cover disk is ring-shaped here.
  • the classifying wheel blades (3) arranged in a ring are arranged between these disks. They are distributed evenly over the circumference of the classifying wheel (10).
  • the classifying wheel blades (3) are aligned essentially radially and delimit the flow channels (6).
  • the classifying wheel (10) is flowed through from the outside inward by the particle-laden classifying fluid, for example classifying air.
  • the classifying wheel (10) according to the invention has flow channels (6) which are specially designed in the outer third, based on the classifying wheel radius, by internals (5a, 5b).
  • the figure 2 shows a classifying wheel (10) with the contour of the flow channels (6) according to the invention.
  • the flow channels (6) have a continuous contour.
  • the classifying wheel blades (3) do not run exactly in the radial direction in the radially outer third of the classifying wheel radius, but are arranged inclined at an angle to the radial direction counter to the direction of rotation of the classifying wheel (10). It is characterized by a continuous contour of the specially shaped outer areas of the classifying wheel blades (3), with the distance between two adjacent classifying wheel blades (3), viewed from the outside inward, initially narrows, followed by a widening before the distance narrows again.
  • This narrowing, widening and narrowing of the flow channels (6) is realized by fittings (5a, 5b) on the classifying wheel blades (3) which protrude into the flow channels (6).
  • the internals (5a, 5b) are arranged in the direction of rotation on the front boundary surfaces of each classifying wheel blade (3). There are no internals on the boundary surface at the rear in the direction of rotation.
  • the built-in components (5a, 5b) have a triangular cross-section here, viewed from the outside inward of the flow channel (6), both for the outer and for the inner built-in components.
  • the classifier blades (3) do not run exactly in the radial direction in the radially outer third of the classifier wheel radius, but are arranged inclined at an angle to the radial direction counter to the direction of rotation.
  • the flow channels (6) have a constriction, an expansion and a constriction.
  • the contour of the flow channels is discontinuous, it has edges, corners and projections.
  • the classifying wheel (10) has elements (5a) of the radially outermost area of the classifying wheel blade which are bent forward in the direction of rotation of the classifying wheel (10) and represent the outer constriction.
  • the buckling forward of the outermost area of the classifier wheel vanes (3) can be pronounced to different extents. For example, as in the figure 3 shown, be designed such that it is formed radially to the classifier wheel axis.
  • the built-in components (5a, 5b) viewed from the outside inward of the flow channel (6), have a triangular cross-section for the outer built-in components (5a) and a square cross-section for the inner built-in components (5b). They form the constrictions, between them is the widening of the flow channel (6).
  • the internals (5a, 5b) extend axially over the entire blade height. They can be connected to the boundary surfaces of the classifying wheel blades (3) by welding, soldering or gluing, for example.
  • the built-in components (5a, 5b) are preferably each on a common radial circular path around the axis of rotation of the classifying wheel (10), which lies approximately in an area within the outer third of the classifying wheel radius.
  • the outer internals (5a) are located on the outer circumference of the classifying wheel (10).
  • figure 4 shows a section of a classifying wheel according to the invention in cross section.
  • Three separator wheel blades are shown with the flow channels in between with the built-in components (5a) and (5b); they delimit the widening in between as a radially outer and radially inner constriction.
  • the constrictions are designed as internals and can be made of the same or different material than the classifier wheel blades.
  • the arc length a describes the distance between two adjacent classifier wheel blades with the associated radius r(a) at the outer constriction at the height of the internals 5a.
  • the radius r(a) corresponds to the sighting wheel radius r(s).
  • the arc length b describes the distance between two adjacent classifier wheel blades with the associated radius r(b) at the largest point of the widening.
  • the arc length c describes the distance between two adjacent classifier wheel blades with the associated radius r(c) at the inner constriction at the height of the internals 5b.

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  • Combined Means For Separation Of Solids (AREA)
EP22000049.1A 2021-03-09 2022-03-03 Dispositif et procédé de criblage de marchandises pulvérulentes Pending EP4059625A1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE102021001237.2A DE102021001237B4 (de) 2021-03-09 2021-03-09 Vorrichtung und Verfahren zur Sichtung von staubförmigen Gütern

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EP4059625A1 true EP4059625A1 (fr) 2022-09-21

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EP22000049.1A Pending EP4059625A1 (fr) 2021-03-09 2022-03-03 Dispositif et procédé de criblage de marchandises pulvérulentes

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EP (1) EP4059625A1 (fr)
DE (1) DE102021001237B4 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115805130A (zh) * 2022-12-30 2023-03-17 合肥中亚建材装备有限责任公司 一种基于流线形叶片的选粉系统

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0226682A (ja) * 1988-07-18 1990-01-29 Babcock Hitachi Kk 粉砕分級装置
US5055182A (en) * 1989-01-12 1991-10-08 Krupp Polysius Ag Separator
EP0983802A2 (fr) 1998-09-04 2000-03-08 HOSOKAWA ALPINE Aktiengesellschaft & Co. OHG Roue de triage pour séparateur pneumatique centrifuge

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0226682A (ja) * 1988-07-18 1990-01-29 Babcock Hitachi Kk 粉砕分級装置
US5055182A (en) * 1989-01-12 1991-10-08 Krupp Polysius Ag Separator
EP0983802A2 (fr) 1998-09-04 2000-03-08 HOSOKAWA ALPINE Aktiengesellschaft & Co. OHG Roue de triage pour séparateur pneumatique centrifuge

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
K. LESCHONSKIK. LEGENHAUSEN, IN EINEM AUFSATZ IN CHEMICAL ENGINEERING AND PROCESSING, vol. 31, 1992, pages 131 - 136

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115805130A (zh) * 2022-12-30 2023-03-17 合肥中亚建材装备有限责任公司 一种基于流线形叶片的选粉系统

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DE102021001237B4 (de) 2023-02-09
DE102021001237A1 (de) 2022-09-15

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