EP3541534B1 - Separator, separator mill and method for separating a gas-solids mixture - Google Patents

Description

The present invention relates to a classifier, a mill with a classifier and a method for classifying a gas-solid mixture.

Sifting is generally understood to mean the separation of solids according to certain criteria such as mass density or particle size. Air sifting is a group of sifting processes in which a gas flow, the so-called sifting air, is used to achieve this separation. The operating principle is based on the fact that fine or small particles are more strongly influenced and carried away by the gas flow than coarse or large particles.

Air classifiers are used, for example, to classify coal dust or other grist from a mill. The aim here is, after the grinding process, to separate particles that have been ground sufficiently small and particles that have to be ground further. These two groups of particles are also referred to as fine and coarse material. In principle, a sifter can also be used for the separation or classification of solids of other origins.

There are different types of air separators. An essential differentiating criterion is the way in which the solids to be separated, the feed material and the sifting air are introduced into the sifter. In this way, solids and classifying air can either be introduced separately or together.

A wind sifter, in which solids and air are brought in together, is from the US 2010/0236458 A1 known. The disclosed wind sifter is used for the sifting of coal dust. The mixture of coal dust and classifying air is let into the classifier housing from below. The inlet volume flow of the gas-solid mixture flows completely from the outside into the interior of a guide vane ring. The guide vane ring has a plurality of deflection elements, between which the mixture flows. The deflection elements are tilted by 50 to 70 ° relative to the horizontal and are fixed. A sifter wheel is located inside the guide vane ring. The classifier wheel is driven in rotation and has a plurality of lamellae which run essentially vertically. Due to the flow and despite the rotation of the classifier wheel, fine particles can pass between the lamellae of the classifier wheel and are then sucked upwards. Coarse particles hit the lamellas, are thrown back in this way and finally fall down due to gravity.

In other air separators, the guide vanes of the guide vane ring are arranged vertically, for example in FIG WO 2014/124899 A1 . The guide vanes provided there can be straight or curved. Similar air separators are also from the publications EP 1 239 966 B1 , EP 2 659 988 A1 , DE 44 23 815 C2 and EP 1 153 661 A1 known. In case of EP 2 659 988 A1 the slats are adjustable. In the EP 1 153 661 A1 Both vertical and horizontal lamellae are used, which should lead to an overall equalization of the flow.

A disadvantage of conventional air separators, in which the feed material and the classifying air are introduced together, is the inadequate separation of coarse and fine material, also known as a sharpness of separation. Air classifiers with other operating principles, in which, for example, the direction of flow of the classifying air is transverse to the direction of fall of the feed material, cause turbulence of the feed material, which results in a better separation of coarse and fine material. In the case of the air classifiers described above, the mixture of feed material and classifying air flows completely through the guide vane ring and largely homogeneously through the classifier. This is why there are more and more errors in sightings, in which fine material particles in particular end up in the coarse material.

The WO 2014/124899 A1 tries to solve this problem with internals. The internals can be arranged in the area between the guide vane ring and the classifier wheel, which is also referred to as the classifying zone. The aim of the internals is to counteract a homogeneous flow and thus to swirl the feed material. However, built-in components lead to a reduction in the efficiency of the classifier due to the additional resistance, which in particular manifests itself externally in a higher power requirement or a lower throughput of the classifier.

The document EP-A2-0204412 discloses a classifier according to the preamble of claim 1, as well as a method for classifying a gas-solid mixture.

The object of the invention is to improve the selectivity of classifiers in which the feed material and classifying air are introduced together.

This object is achieved by a classifier according to claim 1, by a mill according to claim 10 and by a method for classifying according to claim 11.

Advantageous further developments are the subject of the subclaims.

The classifier according to the invention has a classifier housing in which a classifier wheel and a guide vane ring are arranged. The classifier wheel has an X axis of rotation. In the radial direction R perpendicular to the axis of rotation X, an annular space is provided between the guide vane ring and the classifier housing and a viewing zone is provided between the guide vane ring and the classifier wheel.

The sifter is characterized in that there is a circumferential annular gap in the vertical direction between the guide vane ring and a cover.

The axis of rotation X preferably runs in the vertical direction.

Generic classifiers are generally arranged in an upright position. Therefore, in the following, "vertical" means directions parallel to the direction of the gravitational force. Correspondingly, directions perpendicular to the direction of the gravitational force are referred to as "horizontal".

The annular gap connects the annular space with the viewing zone.

The annular gap has the advantage that the inlet volume flow can be divided. A first partial volume flow reaches the viewing zone from above via the annular gap, a second partial volume flow flows through the guide vane ring into the viewing zone. The two partial volume flows meet in the viewing zone, which leads to turbulence and thus to improved viewing. In this way, the selectivity of the sifting can be improved.

The annular gap advantageously has a height HR.

In an advantageous development, the guide vane ring and / or the cover can be moved in the direction of the axis of rotation X, so that the height HR of the annular gap can be adjusted. In this way, the amount of the first partial volume flow can be adjusted. The ratio between the first and second partial flow can thus also be varied.

The height HR is preferably between 50 mm and 1000 mm, particularly preferably between 200 mm and 1000 mm.

The cover can be a housing cover or a classifier cover or a built-in part in the cover area of the classifier.

The housing cover is part of the classifier housing and closes the classifier housing at an upper end. The housing cover is stationary while the classifier is in operation. The housing cover can be curved upwards, which favors the deflection of the first partial volume flow into the viewing zone.

The classifier cover is preferably connected to the classifier wheel so that it rotates with the classifier wheel. The sifter cover is advantageously only an annular disk. The classifier cover is preferably arranged flush with an upper edge of the classifier wheel. An annular gap between the guide vane ring and the separator cover has a positive effect on the homogeneity of the flow in the annular space. In this way, backwater in the annular space can be prevented or reduced.

The annular space advantageously tapers towards the top. As the gas-solid mixture flows through the guide vane ring, the volume flow is reduced upwards, so that it is advantageous to continuously reduce the cross-section of the annular space upwards in order to enable a uniform flow through the guide vane ring. This is achieved through the rejuvenation.

The annular space has a width B. The width B can be constant or vary in the vertical direction. When designing the sifter, the ratio between width B and height HR can be influenced. The ratio B: HR is preferably between 0.2 and 5, particularly preferably between 0.5 and 2. In the case of a non-constant width B, the mean value of the width B should be used to calculate the ratio.

The guide vane ring has a height HL. The ratio HL: HR is advantageously between 0.5 and 10, in particular between 2 and 5. In this way, sufficient feed material reaches the viewing zone both through the guide vane ring and through the annular gap.

The guide vane ring preferably has vertical guide vanes which are arranged distributed uniformly over the circumference of the guide vane ring. It has been shown that the quantities of the second partial volume flow can be set more simply and more precisely if the guide vane ring is equipped with additional deflection elements.

Preferably, at least one deflecting element is arranged at least between two adjacent vertical guide vanes, which deflection element has at least one downward curvature and / or bevel. The downward curvature and / or bevel enables the gas-solid mixture to be diverted in a controlled manner into the sifter's viewing zone. A fold is understood to mean an angled straight section of the deflecting element.

At least one deflecting element is preferably arranged between each two adjacent vertical guide vanes.

A further advantage of these deflecting elements is that a horizontal and / or vertically downward movement component can be imparted to the flow of the gas-solid mixture already within the guide vane ring. This leads to an improved approach of the flow to the sifter wheel within the sifting zone, which in turn increases the separation accuracy of the sifter.

If a plurality of deflection elements is provided in a sifter, the deflection elements can either be identical or different. All deflecting elements are preferably identical within a sifter, which means that production costs can be reduced. Nevertheless, it can be advantageous to use differently designed deflection elements in a sifter in order to produce different effects at different points within the sifter.

Features that are described below with regard to a deflecting element can also be used in other deflecting elements in one and the same embodiment of a classifier according to the invention and preferably in all deflecting elements of this embodiment.

At least one of the deflecting elements advantageously extends over the entire width between two adjacent guide vanes. In this way, areas within the guide vane ring in which an uncontrolled flow into the viewing zone could occur are avoided.

In advantageous developments it is provided that at least one of the deflection elements extends from the guide vane ring into the viewing zone and / or into the annular space.

In particular, an extension into the annular space is advantageous, since in this case the gas-solid mixture already meets the deflecting elements in the annular space and is deflected.

This makes it possible to branch off part of the gas-solid mixture for the second partial volume flow very effectively. The length of the deflecting elements protruding into the annular space makes it possible to adjust the amount of the second partial volume flow in an even more targeted manner. There are therefore two setting options for the ratio of the partial volume flows, namely via the setting of the annular gap width on the one hand and via the arrangement and design of the deflecting elements on the other. According to the structural situation, e.g. B. also when installing in a mill, it is possible to use one or the other or both setting options.

In order to enable uniform deflection, at least one of the deflection elements has a changing radius of curvature in the radial direction R of the guide vane ring, at least in a partial section. At least one of the deflection elements preferably has a changing radius of curvature in the radial direction R over the entire length.

At least one of the deflection elements advantageously has a radially inner end with a first end section and / or a radially outer end with a second end section. The terms radially inside and radially outside refer to the guide vane ring. The guide vane ring preferably has a cylindrical basic shape. The end sections can be configured in different ways, which will be explained in more detail below.

An end section preferably comprises less than 40%, in particular less than 20% of the total length of a deflecting element.

In advantageous developments of the sifter, at least one of the end sections is straight. A section is straight if it has no curvature. This embodiment is particularly advantageous in the case of the first end section of the radially inner end. At the radially inner end, the gas-solid mixture should flow in the direction of the classifier wheel and at the same time as homogeneously as possible. The straight design of the first end section favors a homogeneous flow.

Straight end sections are preferably bevelled, i. H. angled and thus form folds.

At least one of the end sections is preferably arranged horizontally. It is particularly preferably the first end section of the radially inner end. This also serves to generate a homogeneous flow in the direction of the classifier wheel.

In advantageous developments it is provided that at least one of the second end sections or its tangential extension extends at an angle α to a horizontal H, where: α 20 °. The second end sections are each arranged at an outer end of the deflecting elements. When used as intended, the gas-solid mixture reaches the deflection elements from below. It is therefore particularly advantageous if the second end sections are oriented downward at an angle α greater than or equal to 20 °. Particularly preferably, α 60 ° also applies.

A straight extension of an arcuate section that is tangential to the curvature at an end point of the section is referred to as a tangential extension. The arcuate section is preferably viewed in cross section to determine the tangential extension.

The degree of deflection of the gas-solid mixture has an influence on the selectivity. If the deflection is too strong, turbulence or backwater can occur. Too little redirection remains ineffective.

In advantageous developments of the invention it is therefore provided that the first end section of at least one of the deflection elements or its tangential The extension and the second end section of the same deflecting element or its tangential extension run at an angle β to one another, where: β 90 °. In particular, β 120 ° applies. In addition, β 160 ° particularly preferably applies.

Depending on which solid is to be sifted and how the particle distribution contained in the gas-solid mixture is, it can be advantageous to arrange the first end section at an angle greater than 0 ° to a horizontal H. In advantageous developments it is provided that at least one of the first end sections or its tangential extension extends at an angle γ to a horizontal H, where: γ ≥ 10 °. In order to avoid that more and more coarse material ends up in the fine material, the gas-solid mixture can be deflected downwards by the deflecting element and thus in the direction in which the coarse material is ultimately intended to arrive. However, the angle γ must not be chosen too large. Preferably, γ 45 45, in particular γ 30.

With regard to the angles α, β and γ, the following applies particularly preferably: a + β + γ = 180 °. The angles are preferably below the same horizontal H.

It has been shown that good results with regard to the flow conditions can be achieved with one deflecting element between each two adjacent vertical guide vanes.

In advantageous developments of the sifter, provision is made for at least three to five deflecting elements to be arranged between each two adjacent vertical guide vanes. In this way, the gas-solid mixture flowing through between two adjacent vertical guide vanes is divided into partial flows, as a result of which turbulence is avoided and the flows are homogenized.

In advantageous developments, the guide vane ring has at least one swirl breaker. Swirl breakers prevent a flow in the circumferential direction of the guide vane ring and in this way homogenize the flow of the gas-solid mixture.

The object is also achieved with a mill which is combined with a classifier according to the invention. The mill is preferably a pendulum mill or a roller mill. The classifier is preferably integrated into the mill.

• Einleiten eines Einlassvolumenstroms Q aus einem Gas-Feststoff-Gemisch in einen Sichter mit Sichterrad, Leitschaufelkranz und einer zwischen dem Sichterrad und dem Leitschaufelkranz angeordneten Sichtzone;
• Aufteilen des Einlassvolumenstroms Q in einen ersten Teilvolumenstrom Q1 und einen zweiten Teilvolumenstrom Q2;
• Einleiten des ersten Teilvolumenstroms Q1 in die Sichtzone unter Umgehung des Leitschaufelkranzes;
• Einleiten des zweiten Teilvolumenstroms Q2 in die Sichtzone durch den Leitschaufelkranz.

The method according to the invention for sifting a gas-solid mixture has the following steps:

• Introducing an inlet volume flow Q from a gas-solid mixture into a classifier with a classifier wheel, guide vane ring and a classifying zone arranged between the classifier wheel and the guide vane ring;
• Dividing the inlet volume flow Q into a first partial volume flow Q1 and a second partial volume flow Q2;
• Introducing the first partial volume flow Q1 into the viewing zone while bypassing the guide vane ring;
• Introducing the second partial volume flow Q2 into the viewing zone through the guide vane ring.

The inlet volume flow is advantageously divided by providing an annular gap between the guide vane ring and a cover.

The first partial volume flow Q1 is preferably introduced into the viewing zone from above. As a result, the material of the first partial volume flow Q1 can flow through the entire viewing zone from top to bottom. In this way the probability is that the material is sifted, i.e. correctly separated into coarse and fine material, larger. This improves the selectivity.

The first partial volume flow Q1 or the second partial volume flow Q2 is advantageously introduced into the viewing zone essentially in the direction of the gravitational force F.

When used as intended, the inlet volume flow initially flows from the inlet into the annular space between the classifier housing and the guide vane ring. With conventional classifiers, the gas-solid mixture then flows completely through the guide vane ring. Because of the annular gap, the first partial volume flow Q1 flows past the guide vane ring and from above into the viewing zone. The second partial volume flow Q2 of the gas-solid mixture flows through the guide vane ring into the viewing zone.

In principle, the first partial volume flow Q1 moves downwards through the viewing zone, also due to the force of gravity.

Another advantage of the division into two substreams Q1, Q2 is that the substreams Q1, Q2 mutually sift one another in the viewing zone. This self-sifting consists in a turbulence of the gas-solid mixture in the viewing zone. In this way, fine and coarse material are better separated from one another.

The ratio between the first partial volume flow Q1 and the second partial volume flow Q2 can be set. In advantageous developments it is provided that the ratio Q1: Q2 between the first partial volume flow and the second partial volume flow is between 20:80 and 80:20, in particular between 40:60 and 60:40.

For a good self-inspection it is advantageous if the two partial volume flows Q1, Q2 are directed so that they meet in the viewing zone at a flow angle ϕ, where: 45 ° <ϕ <135 °, in particular 70 ° <ϕ <110 ° . The flow angle ϕ can be adjusted more advantageously by means of the deflecting elements.

Figur 1

eine schematische Seitenansicht eines Sichters im Schnitt;

Figur 2

eine Mühle mit integriertem Sichter gemäß der Figur 1 im Schnitt;

Figur 3

eine schematische Seitenansicht des oberen Abschnitt des Sichters der Figur 1 teilweise im Schnitt;

Figur 4

eine schematische Seitenansicht eines Sichters gemäß einer weiteren Ausführungsformen im Schnitt;

Figur 5

einen Leitschaufelkranz in perspektivischer Darstellung;

Figur 6

den Leitschaufelkranz der Figur 5 in einer Draufsicht;

Figur 7

einen vergrößerten Ausschnitt aus dem in den Figuren 5 und 6 gezeigten Leitschaufelkranz;

Figuren 8 - 14

verschiedene Ausführungsformen von Umlenkelementen in Seitenansicht;

Figur 15

ein Diagramm mit Summenverteilungen über Partikelgrößen.

The invention is illustrated and explained by way of example with reference to the figures. It shows:

Figure 1

a schematic side view of a sifter in section;

Figure 2

a mill with an integrated classifier according to Figure 1 on average;

Figure 3

a schematic side view of the upper portion of the classifier of FIG Figure 1 partly in section;

Figure 4

a schematic side view of a sifter according to a further embodiment in section;

Figure 5

a guide vane ring in a perspective view;

Figure 6

the guide vane ring of the Figure 5 in a plan view;

Figure 7

an enlarged section of the in the Figures 5 and 6th guide vane ring shown;

Figures 8-14

various embodiments of deflection elements in side view;

Figure 15

a diagram with cumulative distributions over particle sizes.

In Figure 1 a sifter 10 is shown. The classifier 10 has a classifier housing 20. In a lower region, the separator housing 20 has an inlet 21 for a volume flow Q of a gas-solid mixture 100.

A sifter wheel 30 and a guide vane ring 50 are arranged in the sifter housing 20. The classifier wheel 30 and the guide vane ring 50 have a common main axis, which is the axis of rotation X of the classifier wheel 30. The axis of rotation X runs in the direction of the gravitational force F. A radial direction R extends perpendicular to the axis of rotation X. An annular space 26 is provided in the radial direction R between the guide vane ring 50 and the separator housing 20. The space between the classifier wheel 30 and the guide vane ring 50 forms the classifying zone 32.

The classifier wheel 30 is driven in rotation by a drive device 40, so that the classifier wheel 30 rotates about the axis of rotation X.

An annular gap 28 is arranged between the guide vane ring 50 and a housing cover 24. The volume flow Q entering the annular space 26 from below is divided into two partial volume flows Q1 and Q2, the partial volume flow Q1 entering the viewing zone 32 from above via the annular gap 28. The partial volume flow Q2 flows through the guide vane ring 50 and in this way reaches the viewing zone 32. Both partial volume flows Q1 and Q2 thus meet again in the viewing zone 32.

A first outlet 22 is arranged above the classifier wheel 30. The first outlet 22 is connected to a suction device (not shown) which generates a negative pressure. When used as intended, a first type of particle 101, the fine material, is sucked off through the first outlet 22.

A funnel 25 is arranged below the classifier wheel 30. The funnel 25 opens into a second outlet 23. When used as intended, a second type of particle 102, the coarse material, is discharged through the second outlet 23. The classifier wheel 30 rejects large particles 102. These large particles reach the funnel 25 and from there to the second outlet 23.

The separator housing 20 is closed at the upper end by a housing cover 24.

In the Figure 2 a mill 110 is shown, which is designed as a pendulum mill. Inside the housing 112, which is closed at the top with a mill cover 114 and at the bottom by means of a mill bottom 116, there is a grinding device 118 which has several grinding pendulums 120. The classifier 10 is integrated into the mill housing above the grinding device 18. The annular space 26 is located between the mill housing 112 and the guide vane ring 50. The annular gap 28 is located between the guide vane ring 50 and the mill cover 114.

In the Figure 3 the upper part of the classifier 10 is shown. The classifier wheel 30 is arranged within the guide vane ring 50. A viewing zone 32 is located between the separator wheel 30 and the guide vane ring 50. The cylindrical separator housing 20 can also be designed to be conical. With such a conical sifter housing 20 '(shown in dashed lines) an upwardly tapering annular space 26 is formed.

A modification of the housing cover is also shown in dashed lines. The housing cover 24 'is curved upwards, which favors the deflection of the partial volume flow Q1.

The circumferential annular gap 28 is present in the vertical direction between the guide vane ring 50 and the housing cover 24. The annular gap 28 has a height HR. The annular space 26 has a width B. In the embodiment shown, the ratio B: HR is approximately 1.

The guide vane ring 50 has a height HL. In the embodiment shown, the HL: HR ratio is approximately 3.5.

The first outlet 22 is connected to the interior of the classifier wheel 30.

The guide vane ring 50 has a plurality of vertical guide vanes 54. Five deflection elements 53 are arranged between adjacent vertical guide vanes 54, each of which has a downward curvature.

An upper edge 34 of the separator wheel 30 is located above the upper edge 56 of the guide vane ring 50. More than 50% of the annular gap 28 is located completely above the upper edge 34 of the separator wheel 30 in the vertical direction.

The volume flow Q of the gas-solid mixture 100 flows from below into the annular space 26. A first partial volume flow Q1 can flow through the annular gap 28. In this way, the first partial volume flow Q1 reaches the viewing zone 32 from above. A second partial volume flow Q2 flows through the guide vane ring 50 into the viewing zone 32 and meets the first partial volume flow Q1 there. The deflection elements 53 give the gas-solid mixture flowing through the guide vane ring 50 directed flow components towards the classifier wheel, which is indicated by the arrows shown. The partial volume flows Q1, Q2 meet at an angle ϕ (see enlarged Partial representation in Figure 3 ). In the embodiment shown, the angle ϕ is approximately 45 °.

For the sake of clarity, Q2 only indicates one possible flow path for a partial flow of the second partial volume flow Q2. The second partial volume flow Q2, however, in its entirety designates the entire volume flow which flows from the annular space 26 through the guide vane ring 50 into the viewing zone 32.

Fine particles 101 pass from the sifting zone 32 into the interior of the sifter wheel 30 and are sucked off through the first outlet 22.

The Figure 4 shows a further embodiment of a sifter 10. The sifter 10 has a sifter housing 20 with an inlet 21, a first outlet 22 and a second outlet 23.

A sifter wheel 30 and a guide vane ring 50 are arranged in the sifter housing 20. The classifier wheel is driven in rotation.

The classifier wheel 30 has a classifier cover 36. The sifter cover 36 has the shape of an annular disk. In the middle of the classifier cover 36 there is an opening 38. Material can flow through the opening 38 from the interior of the classifier wheel 30 to the first outlet 22.

The classifier cover 36 rotates with the classifier wheel 30. Between the classifier cover 36 and the guide vane ring 50, a circumferential annular gap 28 is provided in the vertical direction.

The guide vane ring 50 is equipped with a further embodiment of the deflecting elements 53, which have a bevel. In addition, the deflecting elements 53 extend into the annular space 26.

The Figure 5 shows the guide vane ring 50 from Figure 3 in perspective view. The Figure 6 shows the top view of the in Figure 5 guide vane ring 50 shown.

The guide vane ring 50 has a multiplicity of vertical guide vanes 54, with five deflecting elements 53 being arranged between each two adjacent guide vanes 54. Each deflection element 53 extends over the entire width between two vertical guide vanes 54. The deflection elements 53 are arranged equidistantly in the vertical direction.

On its outer circumferential surface, the guide vane ring 50, in contrast to the guide vane ring 50, has Figure 3 a plurality of swirl breakers 52. The twist breakers 52 protrude into the annular space 26 and oppose a flow in the circumferential direction. The twist breakers 52 have a rectangular basic shape and are made of sheet metal. The swirl breakers 52 project in the radial direction R away from the guide vane ring 50 and extend over the entire height of the guide vane ring.

In Figure 7 is an enlarged section of the in Figure 5 illustrated guide vane ring 50 is shown.

The deflection elements 53 have a downward curvature. Each deflecting element 53 has a radially inner end 55 and a radially outer end 56. In the embodiment shown, the radially inner ends 55 do not protrude into the viewing zone 32.

A first end section 57 is arranged at the radially inner end 55 of each deflecting element 53 and a second end section 58 is arranged at the radially outer end 56 of each deflecting element 53. Both end sections 57, 58 are curved.

In the Figures 8 to 14 various embodiments of a deflecting element 53 are shown. The deflecting elements 53 each have a radially inner end 55 and a radially outer end 56. The radially inner end 55 has a first end section 57 and the radially outer end 56 has a second end section 58. The deflection elements 53 have a downward curvature (see Figures 8 to 12 ) or a downward edging (see Figures 13 and 14th ) on.

The deflecting elements 53 are arranged relative to an axis of rotation X of the classifier wheel (not shown here), the distance between the deflecting element 53 and the axis of rotation X being shown reduced for reasons of illustration.

The ones in the Figures 8 to 14 The illustrated embodiments differ in particular in the design of the end sections 57, 58. The end sections 57, 58 can both be curved (see FIG Figures 8 to 10 ) or both straight (see Figures 12 and 14th ), whereby straight and / or curved end sections can also be connected to one another via a curved central section. The Figures 13 and 14th show deflection elements 53 with bevels.

The first end portion 57 of each deflecting element 53 or its tangential extension (see Figure 11 ) is arranged at an angle γ to a horizontal H. In the embodiments shown, the angle γ is between 0 ° (see Figure 8 ) and approx. 28 ° (see e.g. Figure 12 ). The horizontal H, which corresponds to the radial direction R, forms a right angle with the axis of rotation X.

The second end section 58 of each deflecting element 53 or its tangential extension (see Figures 8 , 9 , 11 , 12th ) is arranged at an angle α to the horizontal H. In the embodiments shown, the angle α is between approx. 35 ° (see e.g. Figure 9 ) and approx. 65 ° (see Figure 8 ).

The first end section 57 and the second end section 58 of a deflecting element 53 or their tangential extensions form an angle β. In the embodiments shown, the angle β is between approx. 108 ° (see Figure 12 ) and approx. 153 ° (see Figure 10 ).

In the embodiments shown, the angles α, β and γ result in a total of 180 °. With the exception of the angle γ in Figure 10 all angles α, β, γ are oriented downwards.

Figure 15 shows a diagram of cumulative distributions over particle sizes. The distributions of two sightings, a first distribution V1 and a second distribution V2, are shown. The first distribution V1 is characterized by points, the second distribution V2 by triangles. A sifter without an annular gap was used for the first distribution V1. The second distribution V2, on the other hand, shows the result of a sifting using a sifter with an annular gap.

Identical source material was used for both sightings.

If the starting material is the same, the basic rule is that a steeper curve is to be assessed more positively than a less steep curve. The desired result from a sighting is usually the fine material. In the case of using the classifier according to the invention in a mill, for example, the fine material is removed and the coarse material is returned to the mill in order to again or to be further crushed. Particles that actually belong in the fine material, but which end up in the coarse material, cost additional time and energy, as they have to go through the mill cycle again. Particles that actually belong in the coarse material, but which end up in the fine material, are considerably more disruptive, as they have a direct negative impact on the quality of the end product (the fine material). Therefore, with the same starting material, a classification with less fines is positive.

In the first distribution V1, the sum of the particles that are smaller than 2 μm is 0.344. By using an annular gap (second distribution V2), this proportion could be reduced by approx. 10% to 0.312. In particular in the range of higher particle sizes (> 3 μm) it is shown that the second distribution V2 is steeper and therefore advantageous.

List of reference symbols

10

Sifter

20th

Classifier housing

20 '

conical classifier housing

21

inlet

22nd

first outlet

23

second outlet

24

Housing cover

24 '

domed housing cover

25th

funnel

26th

Annulus

28

Annular gap

30th

Classifier wheel

32

Viewing zone

34

Top edge

36

Classifier cover

38

breakthrough

40

Drive device

50

Guide vane ring

52

Swirl breaker

53

Deflection element

54

vane

56

Top edge

100

Gas-solid mixture

101

first type of particle (fine)

102

second type of particle (coarse)

B.

Width of the annulus

F.

Gravitational force

H

horizontal

HL

Height of the guide vane ring

MR

Height of the annular gap

Q

Inlet volume flow

Q1

first partial volume flow

Q2

second partial volume flow

R.

Radial direction

V1

first distribution

V2

second distribution

X

Axis of rotation

α

angle

β

angle

γ

angle

δ

angle

Claims (15)

1. Separator (10) having a separator housing (20), a separator wheel (30) which is arranged in the separator housing (20) and which has a rotation axis (X), and a guide vane ring (50) which is arranged in the separator housing (20), wherein an annular space (26) is provided in a radial direction (R) perpendicular to the rotation axis (X) between the guide vane ring (50) and the separator housing (20),
   characterised in that a peripheral annular gap (28) is provided between the guide vane ring (50) and a cover (24, 36) in a vertical direction.
2. Separator according to claim 1, characterised in that the annular gap (28) has a height (HR), wherein the guide vane ring (50) and/or the cover (24, 36) is/are movable in the direction of the rotation axis (X) so that the height (HR) can be adjusted.
3. Separator according to either of the preceding claims, characterised in that the cover (24, 36) is a housing cover (24) or a separator cover (36).
4. Separator according to claim 3, characterised in that the separator cover (36) is connected to the separator wheel (30) so that the separator cover (36) is constructed so as to rotate with the separator wheel (30).
5. Separator according to any one of the preceding claims, characterised in that the annular gap (28) has a height HR and the annular space (26) has a width B, wherein the ratio B:HR is between 0.2 and 5.
6. Separator according to any one of the preceding claims, characterised in that the annular gap (28) has a height HR and the guide vane ring (50) has a height HL, wherein the ratio HL:HR is between 0.5 and 10.
7. Separator according to any one of the preceding claims, characterised in that the guide vane ring (50) has a plurality of vertical guide vanes (54), wherein there is arranged at least between two guide vanes (54) at least one redirecting element (53) which has at least one downwardly directed curvature or bevelling.
8. Separator according to claim 7, characterised in that the redirecting elements (53) extend over the entire width between two adjacent guide vanes (54).
9. Separator according to any one of the preceding claims, characterised in that the guide vane ring (50) has at least one torsion breaker (52).
10. Mill, in particular pendulum mill, having an integrated separator according to any one of the preceding claims.
11. Method for separating a gas/solid mixture having the following steps:

    - introducing an inlet volume flow (Q) from a gas/solid mixture (100) into a separator (10) having a separator wheel (30), guide vane ring (50) and a separation zone (32) which is arranged between the separator wheel (30) and the guide vane ring (50);

    - dividing the inlet volume flow (Q) into a first part-volume flow (Q1) and a second part-volume flow (Q2);

    - introducing the first part-volume flow (Q1) into the separation zone (32) while bypassing the guide vane ring (50);

    - introducing the second part-volume flow (Q2) into the separation zone (32) through the guide vane ring (50).
12. Method for separating a gas/solid mixture according to claim 11, characterised in that the first part-volume flow (Q1) is introduced from above into the separation zone (32).
13. Method for separating a gas/solid mixture according to either claim 11 or 12, characterised in that the first part-volume flow (Q1) or the second part-volume flow (Q2) is introduced substantially in the direction of gravitational force (F) into the separation zone (32).
14. Method for separating a gas/solid mixture according to any one of claims 11 to 13, characterised in that the ratio Q1:Q2 between the first part-volume flow (Q1) and the second part-volume flow (Q2) is between 20:80 and 80:20.
15. Method for separating a gas/solid mixture according to any one of claims 11 to 14, characterised in that the two part-volume flows (Q1, Q2) are directed so that they meet each other in the separation zone (32) at an angle (ϕ), wherein there applies: 45°<ϕ< 135°.

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