EP2411150B1 - Roller grinding mill - Google Patents

Description

The invention relates to a roller mill according to the preamble of claim 1.

Roller mills, which have a grinding plate or a grinding plate with a flat grinding track with or without storage rim on the outer circumference and two, three, four or six grinding rollers which roll on the grinding path or on a grinding bed formed thereon supplied Mahlgut are out DE 102 24 009 B4 . DE 31 00 341 A1 and DE 31 34 601 C2 known. The grinding rollers are conical and arranged such that a predeterminable, parallel grinding gap between the roll shell of the grinding rollers and the grinding path is formed.

The ground material to be comminuted is usually supplied laterally via a chute, wherein this is arranged such that the ground material reaches a central region of the rotating grinding bowl. Under the influence of the centrifugal forces, the millbase then spirals on the flat grinding path to the grinding rollers and is crushed.

In overflow mills, the fine and coarse material passes over the edge of the grinding bowl and falls down into a grinding material discharge.

In air flow roller mills, the fines and the coarse material fractions are fed to a sifter arranged above the grinding chamber. The fine material is discharged and the coarse material particles are returned via a semolina cone to the central area of the grinding bowl and below the grinding rolls.

Loesche type air flow roller mills have a storage rim on the grinding table or grinding table circumference, the height of which depends on the size of the mill

Number of grinding rollers, the grinding material to be ground and the fineness of the ground product to be achieved is determined. For the grinding of cement raw material, storage head heights in the range of about 50 to about 130 mm and for the grinding of cement clinker, blastfurnace slag and the like are Staurandhöhen common, which can be from about 150 to about 400 mm.

Roller mills with crowned grinding rollers and with a complementarily designed grinding path have an increased discharge edge ( DE 19 851 103 A1 ) or are also provided with a storage area ( DD-PS 106 953 . DE 197 23 100 A1 ).

It is known to arrange a device for Mahlgutverteilung in the task area of the grinding chamber, or in the central region of the grinding bowl to achieve a uniform feed of the material to be ground to the grinding rollers and thus a nearly uniform comminution work of the individual grinding rollers, a smooth running of the roller mill and overall to achieve the highest possible grinding performance and the desired fineness of the ground product.

Out DE 31 00 341 A1 and DE 31 34 601 C2 are known grinding plates with an elevated central part. The central part is designed as a very flat, relatively wide truncated cone and integrated into the grinding table. The central part has the same height as the storage edge of the flat grinding plate.

In the DD-PS 136 799 and DD-PS 136 800 described air flow roller mills have a flat, flat grinding plate and a central two-part task cone, which consists of a relatively wide, lower truncated cone and a flat, upper cone. The two-part task cone is two to three times higher than a storage rim on Mahltellerumfang. A task chute is arranged decentrally above the task cone, and the feed material passes unevenly under the milling rollers arranged at a different distance from the mill axis and thus to the task cone.

Out AT-PS 189 039 is a roller mill with a grinding bowl is known, the central frusto-conical portion is provided with wings which are to convey the feed material into the spaces between the grinding rollers. At the same time, the air supply to the grinding bowl is divided, whereby the air should also get into these spaces in particular. With these additional facilities should Fluctuations in the throughput of the mill can be avoided and a lower energy requirement can be achieved. The radially upwardly projecting wings are formed on the downwardly sloping lateral surface of the truncated cone and adjoining the lateral surface Mahlbahn is rising upwardly and outwardly formed. At the outer edge of the grinding bowl, a storage rim has a greater height than the central frustoconical portion of the grinding bowl.

In DE 38 34 965 A1 is a vertical roller mill with a flat grinding bowl without storage margin and described with an elevated circular cylindrical central area. Above this central area of the grinding bowl is provided with sensors, additional feeder height adjustable arranged for a continuous supply of material without emptying. The grinding rollers are assigned fixed or adjustable scrapers, which are arranged above the central area and are intended to ensure a uniform distribution of the material to be ground from the central area to the outside under the grinding rollers.

Out DE 197 23 100 A1 is a roller mill is known in which the ground material reaches a central Gutverteilerplatte the grinding bowl. This Gutverteilerplatte is lid-like and can be mitdrehend or even stationary with the grinding bowl. Inner and outer Gutleitschaufeln and gas deflection devices on the mill housing should ensure a uniform Mahlgutverteilung together with the central Gutverteilerplatte.

In DE 196 51 103 A1 a roller mill is described, the rotating grinding plate is provided with a central circular plate. On or above this circular plate, an additional separation device is arranged, with the aid of a lower Mahlbettschicht primarily fine material and an overlying, second Mahlbettschicht should be formed from coarse material, whereby a sufficient venting of the grinding bed, especially when supplying relatively much fines, achieved shall be. The additional separating means is an annular, conically upwardly and outwardly expanding separating comb, which is concentrically mounted on the grinding table. In an alternative embodiment, a Gutaufteileinrichtung is provided instead of the separating. The central circular plate has a central distribution cone for the recirculated granules which are to form the lower Mahlbettschicht, and the coarse-grained feedstock is over several Feeds supplied, which open out over a transition portion of a slightly elevated, central circular plate for gebuldeten Mahlbahn.

The known frustoconical and circular cylindrical Mahlgutverteiler in the center of the grinding bowl or the grinding table are not suitable in the required manner to ensure a uniform distribution of the feed material to the grinding rolls and a nearly uniform grinding bed on the grinding path. The additional facilities, such as wings, scrapers, vanes, Separierkämme, in conjunction with additional air guide elements and / or more coaxially arranged feeds for the feed material are relatively expensive, susceptible to wear and can adversely affect the pressure conditions in the grinding chamber and thus the energy balance of the milling process and affect the throughput of the roller mill.

The invention has for its object to provide a structurally simple, inexpensive Mahlgutverteiler for roller mills with which the described disadvantages of the known solutions can be avoided and particularly good throughput performance of the roller mills can be achieved.

According to the invention the object is achieved by the features of claim 1. Advantageous and advantageous embodiments are included in the description of the figures and in the subclaims.

A basic idea of the invention can be seen in the use as a grinding stock distributor a scattering plate, which is formed and dimensioned in relation to the grinding rollers and the storage edge or to a discharge edge of the grinding bowl, and has a shape which the Mahlgutverteilung and feed to the grinding path and below improves the grinding rolls, contributes to an increase in the throughput of the roller mill and to a significant reduction in grinding energy.

It has been found that a spreading plate, which is arranged as an elevation in the center of the grinding bowl, is to be dimensioned such that the distance of the lateral surface of the spreading plate to the end faces of the grinding rolls greatly improves the grinding material distribution. The end faces of the grinding rollers are directed towards the mill axis surfaces, and the lateral surfaces as rolling surfaces The grinding rollers describe on the grinding path of the grinding bowl a running circle in the form of a circular ring with an inner diameter D _wi and an outer diameter D _wa .

Experiments have shown that the distance of the front side of the grinding rollers of the lateral surface of the spreading plate in small Wälzmühlen in the range of 80 mm and large Wälzmühlen can be up to 400 mm in order to achieve an optimal distribution of the ground material.

genügt. Dabei handelt es sich bei dem Durchmesser D_ST des Streutellers um den Durchmesser in Höhe der Mahlbahn beziehungsweise am Übergang vom Streuteller zur Mahlbahn, und dieser Durchmesser wird in Relation zum Innendurchmesser D_wi des Laufkreises der Mahlwalzen auf der Mahlbahn gesetzt.According to the invention, the spreading plate has a virtually horizontally arranged feeding surface for the ground material and is formed with a diameter D _ST which corresponds to the relationship $$\mathrm{80}\mathrm{mm}\mathrm{\le }\mathrm{½}\left[{\mathrm{D}}_{\mathrm{wi}}\mathrm{-}{\mathrm{D}}_{\mathrm{ST}}\right]\mathrm{\le }\mathrm{400}\mathrm{mm}$$

enough. The diameter D _{ST of} the spreading disc is the diameter at the level of the grinding track or at the transition from the spreading disc to the grinding track, and this diameter is set on the grinding track in relation to the inner diameter D _{wi of} the running circle of the grinding rollers.

In this context, small roller mills are understood to mean roller mills having a grinding bowl diameter of approximately 1.2 to 2.0 m and, in particular, two grinding rollers. Large roller mills are equipped with two, three, four or more, for example six, rollers and the grinding bowls may have diameters from about 2.1 to over 6 m.

It is particularly advantageous to provide roller discs of the LOESCHE type, which have a grinding bowl or a grinding plate with a horizontal grinding path and conical grinding rollers rolling thereon, with a frustum-shaped spreading plate and with a height H _ST as a function of the height H _{SR of} a Forming staurings on the grinding bowl circumference.

gilt.Basically, the height of the storage ring of the grinding bowl is selected depending on the material to be ground and the desired fineness of the ground product. In LOESCHE roller mills with conical grinding rollers and a flat grinding track, the height of the jam ring in the grinding of cement raw material about 50 to 130 mm and in the grinding of cement clinker or Granulated slag about 150 to 400 mm. It has been found in experiments that a spreading plate causes an extraordinarily advantageous distribution of the feed material whose height is greater than or at least equal to the height of the storage ring. For certain mill sizes and selected milling processes, however, it may also be advantageous to make the spreading plate lower than the storage ring. Basically, the height H _{ST of} the spreading disc may be in the range of 60 to 250% of the height H _{SR of} the jam ring, so that the relationship $$\mathrm{0}\mathrm{.}\mathrm{6}{\mathrm{H}}_{\mathrm{SR}}\mathrm{\le }{\mathrm{H}}_{\mathrm{ST}}\mathrm{\le }\mathrm{2}\mathrm{.}\mathrm{5}{\mathrm{H}}_{\mathrm{SR}}$$

applies.

Experiments have shown that the spreading plate can also be formed as a circular cylindrical elevation in order to ensure efficient distribution and feeding of the material to be ground to the grinding path and below the grinding rollers.

In principle, the horizontal feeding surface of the spreading disc according to the invention may have a diameter which is greater than the grinding path width.

In the case of a truncated cone-shaped spreading plate, it is advantageous if the truncated cone angle α, that is to say the inclination of the lateral surface of the truncated cone relative to its base, is in the range from approximately 45 ° to approximately 90 °. For example, the truncated cone angle α 45, 50, 55, 60, 65, 70, 75, 80, 85 or 89 °, it being expedient, in a frustoconical spreading plate having a height greater than the Stauringhöhe a truncated cone angle α in the range of about 45 ° to about 75 ° to choose, while frustoconical spreading discs with a lower height than the storage ring frustoconical angle in the range of 65 ° to 85 ° may have. It has been found that a spreading plate with a truncated cone angle of around 70 ° exhibits particularly advantageous effects, in particular with regard to the running smoothness of the mill and energy saving. This can be explained inter alia with a vertical force component at a larger truncated cone angle in the context of an oblique sliding or rolling surface in the direction of the grinding path.

The upper feeding surface of the spreading disc may be formed as a plane. Depending on the material to be ground for grinding, it may also be expedient for the feeding surface to be inclined upwards or downwards in the direction of the mill axis or curved in a curved manner, that is to say concavely or convexly curved, to form, wherein the inclination angle β then a maximum of 10 ° and thus 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ° can be.

It has been shown in experiments that a concave or convex design of the lateral surface of a frusto-conical or circular cylindrical spreading plate can be advantageous for the distribution of the ground material. The angle of inclination γ of the inside or outside curved lateral surface can advantageously amount to a maximum of 5 °, that is to say 1, 2, 3, 4 or 5 °.

Also advantageous are rounded transition areas, which can be formed between the application surface and the lateral surface of the spreading plate and between the lateral surface of the spreading plate and the adjacent grinding path and favor the flow of the feed material from the application surface and the lateral surface of the storage plate.

In roller mills with grinding bowls, which have a sloping or trough-shaped grinding track and complementarily formed conical or crowned grinding rollers, a discharge edge on the outer edge of the grinding bowl or grinding track can be equated to the storage bin. The height H _{AK of} the discharge edge then corresponds to the height of the storage ring. In principle, it is advantageous if the ratio of height H _{ST of} the spreading plate to the height H _{AK of} the discharge edge is 1.2 to 2.2: 1, that is, the spreading plate is 1.2 to 2.2 times higher than the discharge edge is formed , wherein the height of the discharge edge from the lowest point of the grinding path is measured.

Roller mills with an inventively designed spreading plate show due to the centrifugal and gravity effect on the material to be ground an improved flow of the ground material and under the grinding rollers. Experiments have shown that the throughput of rolling mills could be increased by up to 10% or the grinding energy could be reduced by up to 10%. Due to the inventive arrangement and design of the spreading plate, in particular its dimensions and distance to the grinding rollers in the form of the inner diameter of the running circle of the grinding rollers and the diameter of the spreading plate at the level of the grinding path was found to be a further special effect that from the end faces of the grinding rollers in Millbase discarded millbase from the spreading plate, that is held by its lateral surface, on the grinding track and efficiently transported under the grinding rollers.

Fig. 1

einen Ausschnitt einer erfindungsgemäßen Wälzmühle mit einer Mahlschüssel und einem Streuteller;

Fig. 2

einen Ausschnitt einer alternativen erfindungsgemäßen Wälzmühle mit einer Mahlschüssel und einem Streuteller;

Fig. 3

einen kegelstumpfförmigen Streuteller und

Fig. 4

einen kreiszylindrischen Streuteller.

The invention will be explained below with reference to a drawing. In this show:

Fig. 1

a detail of a roller mill according to the invention with a grinding bowl and a spreading plate;

Fig. 2

a section of an alternative inventive roller mill with a grinding bowl and a spreading plate;

Fig. 3

a frustoconical spreading plate and

Fig. 4

a circular cylindrical spreading plate.

Fig. 1 shows a section of a roller mill with a mill axis 2, a rotating grinding bowl 3 and rolling thereon grinding rollers 5, wherein in the partial view, only the left part of the grinding bowl and only one grinding roller is shown.

The grinding bowl 3 has a flat grinding track 4, which is bounded on the outer periphery by a storage rim 15 with the height H _SR .

In the central region of the grinding bowl 3 a Mahlgutverteiler 7 is arranged, which is integrated in this embodiment in the grinding bowl. In principle, the grinding stock distributor can also be a separate component and can be retrofitted and exchanged.

The Mahlgutverteiler 7 is formed as a scattering plate 10 and has the shape of a truncated cone with the height H _ST and a diameter D _ST in the bottom region, that is, at the level of the grinding track 4.

The grinding rollers 5 rolling on the grinding track 4 or a grinding bed (not shown) formed thereon describe a running circle, which has an annular shape and an inside diameter D _wi and an outside diameter D _wa . Half the difference between the outer diameter and inner diameter of the running circle of the grinding rolls substantially corresponds the width of the lateral surface 6 of the grinding rollers 5, which are conical and face with end faces 8 in the direction of mill axis 2. The grinding bowl 3 in this example has a diameter D _MS of about 5.6 m and a storage rim height H _SR of 0.35. The inner diameter D _{wi of} the running circle of the grinding rolls is about 3.95 m and the outer diameter D _{wa of} the running circle of the grinding rolls 5 is about 5.5 m. The Mahlbahnbreite is thus $$\frac{{\mathit{D}}_{\mathit{Wa}}\mathit{-}{\mathit{<figure-callout\; id="2"\; label="D\; wi"\; filenames="imgf0002.png"\; state="\{\{state\}\}">D\; </figure-callout>}}_{\mathit{wi}}}{2}\approx 0.76m\mathrm{,}$$

The centrally arranged and frusto-conical scattering plate 10 is formed with a flat feed surface 11 and below a central Mahlgutzuführung (not shown) arranged so that the ground material on the feed surface 11 and then under the action of gravity on a lateral surface 12 of the spreading plate 10 on the grinding path 4 flows and enters the catchment area of the grinding rollers 5.

The distance between the spreading plate 10 and the grinding rollers 5 is defined by the diameter D _{ST of} the spreading plate 10 in the amount of the grinding track 4 and the inner diameter D _{wi of} the running circle of the grinding rollers 5, and this distance is 350 mm in the present embodiment. Thus, this distance corresponds to the relationship 80 mm ≦ [D _wi -D _ST ] ≦ 400 mm.

The task surface 11 and the lateral surface 12 of the spreading plate 10 are in the embodiment of Fig. 1 each just trained. The truncated cone angle α is about 65 °.

Fig. 2 shows a left half of an alternative trained grinding bowl 3 with an inclined grinding track 4, which, like the associated grinding rollers 5, of which only one is shown again, is shown by solid lines, and with an alternative, domed grinding track 4 ', which like those on it The discharge edge 17 has a height H _AK of 300 mm, while the scattering plate 10 in the center of the grinding bowl 3 has a height H _ST of 335 mm. The grinding bowl diameter D _MS in this embodiment is 4500 mm, the inner diameter D _{wi of} the running circle of the grinding rolls 5 is 2700 mm, the outer diameter D _{wa of} the running circle of the grinding rolls 5 is 4200 mm and the spreading disc diameter D _ST measures 1980 mm, while the diameter of the feeding surface 11 is 1800 mm.

Using the example of the spreading plate according to Fig. 3 should be clarified that upper transition regions 13 and lower transition regions 14 between the task area 11 and the lateral surface 12 and between the lateral surface 12 and the grinding path 4 are rounded. Dashed line is also shown that the feeding surface 11 in the mill axis 2 inclined upward or downward or concave or convex may be formed with an inclination angle β of 10 °, thereby forming bearing surfaces 11 'and 11 " 10 may also be concave or convexly curved in addition to a flat surface, in which case the angle y may amount to a maximum of 5.degree .. These lateral surfaces are designated by 12 'and 12 ", respectively.

Fig. 4 shows a circular cylindrical scattering plate 10 with a flat feed surface 11 and vertically oriented lateral surface 12. The diameter of the feed surface 11 and the diameter D _ST at the level of the grinding path 4 agree here. The transition regions 13, 14 are in turn rounded and dashed is indicated that the support surface 11 in addition to a flat design also in the direction of mill axis 2 up or down beveled or may have a concave or convex formation. This applies analogously to the lateral surface 12, so that a circular cylindrical scattering plate 10 with the illustrated bearing surfaces 11, 11 ', 11 "and / or the lateral surfaces 12, 12', 12" and an inclination angle β from 1 to 10 ° or a Angle γ of 1 to 5 °, each based on a horizontal shelf surface 11 and a vertical lateral surface 12 of 0 °, may be formed.

Basically, the spreading plate can be integrated into the grinding bowl and manufactured with this. Advantageous for different feed material is a detachable and replaceable arrangement of a separately produced spreading plate, so that a retrofit is possible.

Claims (11)

1. Roller mill,
   having a grinding pan (3) rotatable about a mill axis (2), on a grinding track (4) of the grinding pan (3) stationarily disposed grinding rollers (5) roll and thereby define with their circumferential surfaces (6) on the grinding track (4) the same running circle with an inner diameter D_wi and an outer diameter D_wa, and having a grinding material distributor (7) for grinding material to be comminuted, which grinding material distributor (7) is disposed as an elevation in the centre of the grinding pan (3) coaxially to the mill axis (2),
   characterized in that
   a distributing plate (10) is formed as grinding material distributor (7) having an almost horizontally arranged feed area (11) for the grinding material and a diameter D_ST at the level of the grinding track (4) according to the equation 80 mm ≤½ [D_Wi - D_ST] ≤ 400 mm.
2. Roller mill according to claim 1,
   characterized in that
   the distributing plate (10), which is formed as a truncated cone shaped or circularly cylindrical elevation, has a height H_ST which in relation to the height H_SR of a retention ring (15) on an outer periphery of the grinding pan (3) satisfies the equation $$\mathrm{0.6}{\mathrm{H}}_{\mathrm{SR}}\mathrm{\le }{\mathrm{H}}_{\mathrm{ST}}\mathrm{\le }\mathrm{2.5}{\mathrm{H}}_{\mathrm{SR}\mathrm{.}}$$

   
3. Roller mill according to claim 1,
   characterized in that
   the distributing plate (10) has a greater height H_ST than the retention ring (15) and in that the height of the distributing plate (10) is 1.1 to 2.5 times the height H_SR of the retention ring (15).
4. Roller mill according to one of the preceding claims,
   characterized in that
   the distributing plate (10) has a feed area (11) with a planar formation.
5. Roller mill according to one of the claims 1 to 3,
   characterized in that
   the distributing plate (10) has a feed area (11) which is designed to be upwardly or downwardly inclined in the direction of the mill axis (2) or concavely or convexly curved.
6. Roller mill according to claim 5,
   characterized in that
   the feed area (11) with inclined or curved formation has an inclination angle β of maximum 10°.
7. Roller mill according to one of the claims 2 to 6,
   characterized in that
   the distributing plate (10) formed as a truncated cone has a frustum angle α in the range of from 45° to maximum 89°.
8. Roller mill according to one of the claims 2 to 7,
   characterized in that
   the distributing plate (10) has a shell surface (12) which is concavely or convexly formed and has an angle γ of maximum 5° in relation to a straight line forming the shell surface (12).
9. Roller mill according to one of the preceding claims,
   characterized in that
   the distributing plate (10) has an upper and lower transition region (13, 14) between the feed area (11) and shell surface (12) or respectively between the shell surface (12) and grinding track (4), whereby said upper and lower transition regions (13, 14) are designed so as to be rounded off.
10. Roller mill according to one of the preceding claims,
    characterized in that
    the grinding pan (3) comprises a planar grinding track (4) and the grinding rollers (5) are conically formed and in that the distributing plate (10) has a diameter D_STwhich is equal to or greater than the grinding track width of the grinding rollers (5) according to $${\mathrm{D}}_{\mathrm{ST}}\ge \frac{{\mathit{D}}_{\mathit{Wa}}\mathit{-}{\mathit{D}}_{\mathit{Wi}}}{2}\mathrm{.}$$

    
11. Roller mill according to one of the claims 1 to 9,
    characterized in that
    the grinding pan (3) comprises an inclined (4) or trough shaped grinding track (4') and complementarily formed conical (5) or spherical grinding rollers (5') roll thereon and in that the distributing plate (10) has a height H_ST which in relation to the height H_AK of a discharge edge (17) on an outer edge of the grinding pan (3) satisfies the equation $${\mathrm{H}}_{\mathrm{ST}}\mathrm{:}{\mathrm{H}}_{\mathrm{AK}}\mathrm{=}\mathrm{1.2}\mathrm{to}\mathrm{2.2}\mathrm{:}\mathrm{1.}$$

    

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