EP0165429B1 - Process for operating a crushing mill, and crushing mill working by this process - Google Patents

Process for operating a crushing mill, and crushing mill working by this process Download PDF

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Publication number
EP0165429B1
EP0165429B1 EP85105567A EP85105567A EP0165429B1 EP 0165429 B1 EP0165429 B1 EP 0165429B1 EP 85105567 A EP85105567 A EP 85105567A EP 85105567 A EP85105567 A EP 85105567A EP 0165429 B1 EP0165429 B1 EP 0165429B1
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EP
European Patent Office
Prior art keywords
nozzle ring
mill
segments
sifter
control circuit
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
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EP85105567A
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German (de)
French (fr)
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EP0165429A1 (en
Inventor
Heinrich Dipl.-Ing. Henne
Ludger Dipl.-Ing. Lohnherr
Walter Dipl.-Ing. Holz
Peter Dipl.-Ing. Rittscher
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ThyssenKrupp Industrial Solutions AG
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Krupp Polysius AG
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C15/00—Disintegrating by milling members in the form of rollers or balls co-operating with rings or discs
    • B02C15/001—Air flow directing means positioned on the periphery of the horizontally rotating milling surface

Definitions

  • the invention relates to a prior art method according to the preamble of claim 1, furthermore to a grinding system operating according to this method and also belonging to the prior art according to the preamble of claim 5.
  • the amount of hot gas flow passing through the mill and the classifier is kept constant by a control circuit, a constant gas speed also being established in the nozzle ring of the mill. Due to dynamic processes within the grinding system, however, the amount of material falling through the nozzle ring and transported back up by the bucket elevator and its particle size distribution fluctuate even at constant gas velocity in the nozzle ring. This change in the quantity and grain distribution of the circulating material is disadvantageous, since when producing special products or, for example, also during cement grinding, it is often desirable to keep the quantity and grain distribution of the circulating material constant, for example in order to pull a certain grain belt from the circulating material.
  • the prior art includes a process (CH-A-435940) which uses a hammer mill heated with hot gas for coarse comminution and a tube mill for comminution, a screening device and a centrifugal separator being provided between these two mills.
  • the material discharged from the hammer mill first arrives at the screening device, the coarse fraction being fed back to the hammer mill, while the fine fraction is fed to the centrifugal classifier.
  • the semolina accumulating in the centrifuge goes to the tube mill for further crushing, while the fine fraction of the centrifuge forms the finished product.
  • the coarse material fed back from the screening device to the hammer mill is dosed as a function of the pressure difference of the hot gases at the outlet and inlet of the hammer mill.
  • the invention has for its object to provide a method of the type required in the preamble of claim 1 so that the amount and grain composition of the goods conveyed via the bucket elevator (ie the material in circulation) is kept constant and at the same time possible operational disruptions (such as filling up or emptying) Mill) can be avoided.
  • the roller mill schematically illustrated in FIGS. 1 and 2 contains an annular grinding plate 2 rotating about a vertical axis 1, on which two pairs of rollers 3, 4 roll.
  • a stationary nozzle ring 5 is arranged, which serves to supply an air flow which detects the fine components of the crushed ground material discharged over the edge of the grinding plate and carries them upwards, while the coarse components through the nozzle ring 5 counter to that Airflow falling down.
  • the nozzle ring 5 is divided into several segments, of which the segment 5a is illustrated in detail in FIG. 1.
  • the segment 5a of the nozzle ring 5 contains an inner stationary wall part 6 which is connected to the housing 9 of the mill via two lateral guide parts 7, 8.
  • the stationary inner wall part 6 carries a number of webs 6a which point outwards.
  • segment 5a of the nozzle ring 5 contains an outer adjustable wall part 10 which is connected to the push spindle 11 of a pneumatic cylinder 12.
  • the thrust spindle 11 is guided radially in slide guides 13, 14.
  • the pneumatic cylinder 12 is supported by a flange 15 which is fastened to the housing 9 by means of struts 16, 17.
  • the outer wall part 10 of the segment 5a of the nozzle ring 5 is adjustable by means of the spindle 11 of the pneumatic cylinder 12 in the radial direction (double arrow 18), namely between a radially outer position in which the wall part 10 is located near the housing 9 and one Position 10 'indicated by dashed lines, in which the adjustable wall part 10 touches the struts 6a of the stationary inner wall part 6 and in which it limits the clear cross-section of the interior 19 of the segment 5a through which the air flows, to a minimum.
  • the adjustable wall part 10 of the segment 5a is guided in the region of the ends facing the adjacent segments on parallel guide surfaces 7a, 8a of the guide parts 7, 8.
  • a link guide can be provided in the area of these guide surfaces 7a, 8a in order to exclude the risk of the adjustable outer wall part 10 tilting with respect to a horizontal plane.
  • the number of segments of the nozzle ring 5, each provided with a separate drive, ventilated and adjustable, is adapted to the respective application.
  • the nozzle ring can also contain individual non-ventilated segments between ventilated and adjustable segments. For example, a version with eight ventilated, adjustable segments and four non-ventilated segments arranged between them is conceivable.
  • Fig. 3 shows in schematic form an embodiment in which four air inlets 20, 21, 22, 23 are provided, to which separately adjustable segments 5'a, 5'b, 5'c and 5'd are assigned.
  • These four segments 5'a to 5'd of the nozzle ring 5 ' have, as in the exemplary embodiment already explained with reference to FIGS. And 2, a wall which is adjustable from the outside during operation and which provides the clear opening Cross-section of the nozzle ring is limited and the flow conditions of the air in the area of the relevant segment can be changed by adjusting them.
  • the devices for adjusting the cross section of the nozzle ring are likewise not illustrated in FIG. 3.
  • Adjusting flaps 24 to 27 are provided in the air inlets 20 to 23, which allow a more or less severe throttling of the supplied air streams.
  • the air supplied by the air inlets 20 to 23 is distributed in the manner schematically indicated by the arrows over the circumferential length of the segments 5'a to 5'd of the nozzle ring 5 '.
  • the circumferential zones of the grinding table assigned to the individual segments 5'a to 5'd of the nozzle ring 5 ' can be ventilated differently (with regard to the flow quantities and flow velocities), which is due to the different material accumulation in the individual zones Optimization of the pneumatic good discharge possible.
  • the air also flows essentially from bottom to top through the nozzle ring 5 '.
  • the air flow through the nozzle ring 5 is indicated by the arrow 28.
  • the fine constituents of the comminuted material discharged over the edge of the grinding plate 2 are taken upward - arrow 29 -, while the coarse constituents of the ground material fall downward against the air flow (arrow 29 ').
  • Fig. 4 shows the diagram of a grinding plant operated according to the inventive method.
  • This grinding system contains a ring or roller mill 31, a classifier 32 arranged above the mill 31, a fan 33, an electrostatic filter 34, a bucket elevator 35 and a dosing belt scale 36.
  • the fan 33 generates a hot gas flow which is fed to the mill 31 via a line 37, which passes through the mill with the nozzle ring 5 already explained, then flows through the classifier 32 and is discharged via a line 38 and the electrostatic filter 34 into a chimney 39 .
  • a return air line 40 with a flap 41 arranged therein enables the return of an adjustable portion of the gas flow from line 38 to line 37.
  • the material to be ground is fed from a silo 42 via the dosing belt scale 36 and a material line 43 to the mill 31.
  • the fine constituents of the comminuted ground material discharged over the edge of the grinding plate 2 are caught by the gas stream and transported upwards to the classifier 32, where the finished material is separated.
  • the coarse constituents of the comminuted ground material discharged through the nozzle ring 5 fall down through a feed line 44 into the bucket elevator 35, which conveys them upwards to a sieving or distribution device 45.
  • a certain proportion, for example a certain grain fraction, of the circulating material can be drawn off, while the circulating material is otherwise guided back to the mill 31 via the material line 43.
  • the system according to FIG. 4 contains a first control circuit which keeps the amount of the hot gas flow passing through the mill 31 and the classifier 32 constant.
  • This first control circuit includes a controller 46, which receives a signal from a Venturi tube 47 in line 38 via the amount of gas passing through line 38 and which controls the fan 33 via a motor 48 in order to keep the amount of gas constant.
  • the system contains a second control circuit by means of which the gas velocity in the nozzle ring 5 is changed as a function of the power consumption of the bucket elevator 35 in such a way that the quantity of the material conveyed via the bucket elevator 35 and its grain composition are kept constant.
  • This second control loop contains a higher-level controller 49 and downstream controllers 50a, 50b, 50c etc., the interaction of which will be explained in detail with reference to FIG. 6.
  • a third control loop is also provided. which reduces the material feed to the mill 31 when the gas speed in the nozzle ring 5 exceeds a predetermined maximum value, while it increases the material feed when the gas speed in the nozzle ring 5 falls below a predetermined minimum value steps.
  • This third control circuit contains a controller 51, which is connected to one or more of the downstream controllers 50a, 50b, 50c and acts on the dosing belt scale 36.
  • a fourth control circuit which controls the temperature of the hot gas flow passing through the mill 31 and the classifier 32 in such a way that the gas temperature after the classifier 32 is used as a guide variable for the setpoint value of the gas temperature before the mill 31.
  • This fourth control circuit contains a controller 52, to which the gas temperature downstream of the classifier 32 is supplied by a temperature measuring element 53 as a reference variable for the target value of the gas temperature upstream of the mill 31.
  • the corresponding gas temperature upstream of the mill 31 is set via a motor 54, which acts on the flap 41 arranged in the return air line 40.
  • a fresh air flap (not shown) can of course also be adjusted.
  • the quantity of the material conveyed via the bucket elevator 35 and its grain composition are kept constant by the second control loop. If the amount of the coarse constituents of the comminuted material to be discharged, which falls downward against the gas flow through the nozzle ring, increases, and as a result the power consumption of the bucket elevator 35 increases, the controller 49 increases the gas velocity in the nozzle ring 5 by correspondingly reducing the clear nozzle ring -Section. Accordingly, the gas velocity in the nozzle ring 5 is reduced when the power consumption of the bucket elevator 38 is reduced.
  • the third control circuit comes into operation when the gas speed in the nozzle ring 5 exceeds a predetermined maximum value or falls below a predetermined minimum value.
  • the material feed to the mill 31 is reduced by the controller 51 via the dosing belt scale 36
  • the material feed to the mill is increased.
  • FIG. 5 illustrates the devices for changing the clear cross section of the nozzle ring 5, which is divided into several, separately adjustable segments 5a to 5h. Hydraulic or pneumatic cylinders 12 are used for the adjustment, as was explained in detail with reference to FIGS. 1 to 3. Non-contact displacement transducers 55 are provided to determine the free cross-sectional area of the nozzle ring 5 in the individual segments 5a to 5h.
  • the interaction of the higher-level controller 49 and the downstream controllers 50a, 50b, 50c ... assigned to the individual segments 5a, 5b, 5c ... can be seen from FIG. 6.
  • the higher-level controller 49 receives an actual value (arrow 56) of the current clear cross section of the nozzle ring 5 from a selected segment (for example from segment 5b).
  • the controller 49 receives the setpoint (arrow 57) as a function of the power consumption of the bucket elevator 35.
  • the signal formed by the higher-level controller 49 (arrows 58a, 58b, 58c ...) is then used as the setpoint for the downstream controllers 50a, 50b, 50c. .. supplied, the hydraulically unlockable shut-off valves 59a, 60a, 59b, 60b, 59c, 60c ... actuate the cylinder 12 of the individual segments 5a to 5h.
  • the zero positions of the individual segments can be set differently, i. H. are assigned to a different clear cross-sectional side of the nozzle ring in the area of the individual segments, so that 5 different amounts of gas (corresponding to the different material loading in these peripheral areas) are set in the individual peripheral areas of the nozzle ring.

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  • Engineering & Computer Science (AREA)
  • Food Science & Technology (AREA)
  • Crushing And Grinding (AREA)
  • Disintegrating Or Milling (AREA)

Description

Die Erfindung betrifft ein zum Stand der Technik gehörendes Verfahren entsprechend dem Oberbegriff des Anspruches 1, ferner eine nach diesem Verfahren arbeitende, gleichfalls zum Stand der Technik gehörende Mahlanlage entsprechend dem Oberbegriff des Anspruches 5.The invention relates to a prior art method according to the preamble of claim 1, furthermore to a grinding system operating according to this method and also belonging to the prior art according to the preamble of claim 5.

Beim Betrieb von Mahlanlagen der im Oberbegriff des Anspruches 1 vorausgesetzten Art wird die Menge des die Mühle und den Sichter durchsetzenden Heißgasstromes durch einen Regelkreis konstantgehalten, wobei sich auch eine konstante Gasgeschwindigkeit im Düsenring der Mühle einstellt. Aufgrund von dynamischen Vorgängen innerhalb des Mahlsystemes schwankt jedoch auch bei konstanter Gasgeschwindigkeit im Düsenring die durch den Düsenring nach unten hindurchfallende und vom Becherwerk wieder hochtransportierte Gutmenge sowie deren Kornverteilung. Diese Änderung der Menge und Kornverteilung des Umlaufgutes ist nachteilig, da es bei der Erzeugung von Sonderprodukten oder beispielsweise auch bei der Zementvermahlung oft erwünscht ist, die Menge und Kornverteilung des Umlaufgutes konstantzuhalten, etwa um ein bestimmtes Kornband aus dem Umlaufgut abzuziehen.When operating grinding plants of the type required in the preamble of claim 1, the amount of hot gas flow passing through the mill and the classifier is kept constant by a control circuit, a constant gas speed also being established in the nozzle ring of the mill. Due to dynamic processes within the grinding system, however, the amount of material falling through the nozzle ring and transported back up by the bucket elevator and its particle size distribution fluctuate even at constant gas velocity in the nozzle ring. This change in the quantity and grain distribution of the circulating material is disadvantageous, since when producing special products or, for example, also during cement grinding, it is often desirable to keep the quantity and grain distribution of the circulating material constant, for example in order to pull a certain grain belt from the circulating material.

Zum Stand der Technik gehört ein Verfahren (CH-A-435940), das zur Grobzerkleinerung des Mahlgutes eine mit Heißgas beheizte Hammermühle und zur Nachzerkleinerung eine Rohrmühle verwendet, wobei zwischen diesen beiden Mühlen eine Siebeinrichtung sowie ein Schleudersichter vorgesehen sind. Das aus der Hammermühle ausgetragene Gut gelangt zunächst zur Siebeinrichtung, wobei der anfallende Grobanteil zurück zur Hammermühle geleitet wird, während der Feinanteil dem Schleudersichter zugeführt wird. Die im Schleudersichter anfallenden Grieße gelangen zur Nachzerkleinerung in die Rohrmühle, während der Feinanteil des Schleudersichters das Fertiggut bildet. Bei diesem Verfahren erfolgt eine Dosierung des von der Siebeinrichtung zurück zur Hammermühle geführten Grobgutes in Abhängigkeit von der Druckdifferenz der Heißgase am Auslaß und Einlaß der Hammermühle.The prior art includes a process (CH-A-435940) which uses a hammer mill heated with hot gas for coarse comminution and a tube mill for comminution, a screening device and a centrifugal separator being provided between these two mills. The material discharged from the hammer mill first arrives at the screening device, the coarse fraction being fed back to the hammer mill, while the fine fraction is fed to the centrifugal classifier. The semolina accumulating in the centrifuge goes to the tube mill for further crushing, while the fine fraction of the centrifuge forms the finished product. In this method, the coarse material fed back from the screening device to the hammer mill is dosed as a function of the pressure difference of the hot gases at the outlet and inlet of the hammer mill.

Der Erfindung liegt die Aufgabe zugrunde, ein Verfahren der im Oberbegriff des Anspruches 1 vorausgesetzten Art so auszubilden, daß die Menge und die Kornzusammensetzung des über das Becherwerk geförderten Gutes (d. h. des Umlaufgutes) konstantgehalten wird und zugleich mögliche Betriebsstörungen (wie ein Vollaufen oder Leerfahren der Mühle) vermieden werden.The invention has for its object to provide a method of the type required in the preamble of claim 1 so that the amount and grain composition of the goods conveyed via the bucket elevator (ie the material in circulation) is kept constant and at the same time possible operational disruptions (such as filling up or emptying) Mill) can be avoided.

Diese Aufgabe wird erfindungsgemäß durch die kennzeichnenden Merkmale des Anspruches 1 gelöst.This object is achieved by the characterizing features of claim 1.

Zweckmäßige Ausgestaltungen der Erfindung sind Gegenstand der Unteransprüche und werden im Zusammenhang mit der Beschreibung einiger Ausführungsbeispiele näher erläutert.Appropriate embodiments of the invention are the subject of the dependent claims and are explained in connection with the description of some exemplary embodiments.

In der Zeichnung zeigen

  • Figur 1 eine Aufsicht auf die für das Verständnis der Erfindung wesentlichen Teile einer Rollenmühle,
  • Figur 2 einen Schnitt längs der Linie 11-11 der Fig. 1,
  • Figur 3 eine schematische Aufsicht auf ein zweites Ausführungsbeispiel einer erfindungsgemäßen Rollenmühle,
  • Figur 4 eine Schemadarstellung einer nach dem erfindungsgemäßen Verfahren betriebenen Mahlanlage,
  • Figur 5 eine Aufsicht auf eine Rollenmühle mit gesondert verstellbaren Segmenten des Düsenringes,
  • Figur 6 ein Schema des Regelkreises für die Verstellung der einzelnen Segmente des Düsenringes.
Show in the drawing
  • FIG. 1 shows a top view of the parts of a roller mill that are essential for understanding the invention,
  • 2 shows a section along the line 11-11 of FIG. 1,
  • FIG. 3 shows a schematic plan view of a second exemplary embodiment of a roller mill according to the invention,
  • FIG. 4 shows a diagram of a grinding plant operated according to the method according to the invention,
  • FIG. 5 shows a top view of a roller mill with separately adjustable segments of the nozzle ring,
  • Figure 6 is a schematic of the control loop for the adjustment of the individual segments of the nozzle ring.

Die in den Fig. 1 und 2 schematisch veranschaulichte Rollenmühle enthält einen um eine vertikale Achse 1 rotierenden ringförmigen Mahlteller 2, auf dem zwei Rollenpaare 3, 4 abrollen.The roller mill schematically illustrated in FIGS. 1 and 2 contains an annular grinding plate 2 rotating about a vertical axis 1, on which two pairs of rollers 3, 4 roll.

Am äußeren Umfang des Mahltellers 2 ist ein ortsfester Düsenring 5 angeordnet, der zur Zuführung eines Luftstromes dient, der die feinen Bestandteile des über den Rand des Mahltellers ausgetragenen, zerkleinerten Mahlgutes erfaßt und nach oben trägt, während die groben Bestandteile durch den Düsenring 5 entgegen dem Luftstrom nach unten fallen.On the outer periphery of the grinding plate 2, a stationary nozzle ring 5 is arranged, which serves to supply an air flow which detects the fine components of the crushed ground material discharged over the edge of the grinding plate and carries them upwards, while the coarse components through the nozzle ring 5 counter to that Airflow falling down.

Der Düsenring 5 ist in mehrere Segmente unterteilt, von denen in Fig. 1 das Segment 5a im einzelnen veranschaulicht ist.The nozzle ring 5 is divided into several segments, of which the segment 5a is illustrated in detail in FIG. 1.

Das Segment 5a des Düsenringes 5 enthält einen inneren stationären Wandteil 6, der über zwei seitliche Führungsteile 7, 8 mit dem Gehäuse 9 der Mühle verbunden ist. Der stationäre innere Wandteil 6 trägt eine Anzahl von Stegen 6a, die nach außen weisen.The segment 5a of the nozzle ring 5 contains an inner stationary wall part 6 which is connected to the housing 9 of the mill via two lateral guide parts 7, 8. The stationary inner wall part 6 carries a number of webs 6a which point outwards.

Weiterhin enthält das Segment 5a des Düsenringes 5 einen äußeren verstellbaren Wandteil 10, der mit der Schubspindel 11 eines pneumatischen Zylinders 12 verbunden ist. Die Schubspindel 11 ist in Gleitführungen 13, 14 radial geführt. Der pneumatische Zylinder 12 wird von einem Flansch 15 getragen, der über Streben 16, 17 am Gehäuse 9 befestigt ist.Furthermore, the segment 5a of the nozzle ring 5 contains an outer adjustable wall part 10 which is connected to the push spindle 11 of a pneumatic cylinder 12. The thrust spindle 11 is guided radially in slide guides 13, 14. The pneumatic cylinder 12 is supported by a flange 15 which is fastened to the housing 9 by means of struts 16, 17.

Der äußere Wandteil 10 des Segmentes 5a des Düsenringes 5 ist mittels der Spindel 11 des pneumatischen Zylinders 12 in radialer Richtung (Doppelpfeil 18) verstellbar, und zwar zwischen einer radial äußeren Position, in der sich der Wandteil 10 nahe dem Gehäuse 9 befindet, und einer gestrichelt angedeuteten Position 10', in der der verstellbare Wandteil 10 die Streben 6a des stationären inneren Wandteiles 6 berührt und in der er den lichten Querschnitt des von der Luft durchströmten Innenraumes 19 des Segmentes 5a auf ein Minimum begrenzt.The outer wall part 10 of the segment 5a of the nozzle ring 5 is adjustable by means of the spindle 11 of the pneumatic cylinder 12 in the radial direction (double arrow 18), namely between a radially outer position in which the wall part 10 is located near the housing 9 and one Position 10 'indicated by dashed lines, in which the adjustable wall part 10 touches the struts 6a of the stationary inner wall part 6 and in which it limits the clear cross-section of the interior 19 of the segment 5a through which the air flows, to a minimum.

Der verstellbare Wandteit 10 des Segmentes 5a ist im Bereich der den benachbarten Segmenten zugewandten Enden an parallelen Führungsflächen 7a, 8a der Führungsteile 7, 8 geführt. Zusätzlich kann im Bereich dieser Führungsflächen 7a, 8a noch eine Kulissenführung vorgesehen sein, um die Gefahr eines Verkantens des verstellbaren äußeren Wandteiles 10 gegenüber einer horizontalen Ebene auszuschließen.The adjustable wall part 10 of the segment 5a is guided in the region of the ends facing the adjacent segments on parallel guide surfaces 7a, 8a of the guide parts 7, 8. In addition, a link guide can be provided in the area of these guide surfaces 7a, 8a in order to exclude the risk of the adjustable outer wall part 10 tilting with respect to a horizontal plane.

Während bei dem in den Fig. 1 und 2 dargestellten Ausführungsbeispiel die äußeren Wandteile 10 der einzelnen Segmente des Düsenringes 5 mittels' pneumatischer Zylinder 12 verstellbar sind, kann im Rahmen der Erfindung auch eine Verstellung durch einen elektrischen oder hydraulischen Antrieb vorgesehen werden.While in the embodiment shown in FIGS. 1 and 2 the outer wall parts 10 of the individual segments of the nozzle ring 5 are adjustable by means of a pneumatic cylinder 12, an adjustment by an electric or hydraulic drive can also be provided within the scope of the invention.

Die Zahl der jeweils mit einem gesonderten Antrieb versehenen, belüfteten und verstellbaren Segmente des Düsenringes 5 wird dem jeweiligen Anwendungsfall angepaßt. Der D'üsenring kann ferner zwischen belüfteten und verstellbaren Segmenten auch einzelne nicht belüftete Segmente enthalten. Denkbar ist beispielsweise eine Ausführung mit acht belüfteten, verstellbaren Segmenten und vier dazwischen angeordneten, nicht belüfteten Segmenten.The number of segments of the nozzle ring 5, each provided with a separate drive, ventilated and adjustable, is adapted to the respective application. The nozzle ring can also contain individual non-ventilated segments between ventilated and adjustable segments. For example, a version with eight ventilated, adjustable segments and four non-ventilated segments arranged between them is conceivable.

Fig. 3 zeigt in schematischer Form ein Ausführungsbeispiel, bei dem vier Luftzuführungen 20, 21, 22, 23 vorgesehen sind, denen gesondert verstellbare Segmente 5'a, 5'b, 5'c und 5'd zugeordnet sind. Diese vier Segmente 5'a bis 5'd des Düsenringes 5', deren Einzelheiten in Fig. 3 nicht veranschaulicht sind, besitzen wie bei dem anhand der Fig. und 2 bereits erläuterten Ausführungsbeispiel eine während des Betriebes von außen verstellbare Wand, die den lichten Querschnitt des Düsenringes begrenzt und durch deren Verstellung damit die Strömungsverhältnisse der Luft im Bereich des betreffenden Segments verändert werden können. Die Einrichtungen zur Verstellung des Düsenring-Querschnitts sind in Fig. 3 gleichfalls nicht veranschaulicht.Fig. 3 shows in schematic form an embodiment in which four air inlets 20, 21, 22, 23 are provided, to which separately adjustable segments 5'a, 5'b, 5'c and 5'd are assigned. These four segments 5'a to 5'd of the nozzle ring 5 ', the details of which are not illustrated in FIG. 3, have, as in the exemplary embodiment already explained with reference to FIGS. And 2, a wall which is adjustable from the outside during operation and which provides the clear opening Cross-section of the nozzle ring is limited and the flow conditions of the air in the area of the relevant segment can be changed by adjusting them. The devices for adjusting the cross section of the nozzle ring are likewise not illustrated in FIG. 3.

In den Luftzuführungen 20 bis 23 sind Stellklappen 24 bis 27 vorgesehen, die eine mehr oder weniger starke Drosselung der zugeführten Luftströme gestatten. Die durch die Luftzuführungen 20 bis 23 zugeführte Luft verteilt sich in der durch die Pfeile schematisch angedeuteten Weise auf die Umfangslänge der Segmente 5'a bis 5'd des Düsenringes 5'. Bei diesem Ausführungsbeispiel gemäß Fig. 3 können die den einzelnen Segmenten 5'a bis 5'd des Düsenringes 5' zugeordneten Umfangszonen des Mahltellers unterschiedlich belüftet werden (und zwar hinsichtlich der Strömungsmengen und Strömungsgeschwindigkeiten), was wegen des unterschiedlichen Materialanfalles in den einzelnen Zonen eine Optimierung des pneumatischen Gutaustrages ermöglicht.Adjusting flaps 24 to 27 are provided in the air inlets 20 to 23, which allow a more or less severe throttling of the supplied air streams. The air supplied by the air inlets 20 to 23 is distributed in the manner schematically indicated by the arrows over the circumferential length of the segments 5'a to 5'd of the nozzle ring 5 '. In this embodiment according to FIG. 3, the circumferential zones of the grinding table assigned to the individual segments 5'a to 5'd of the nozzle ring 5 'can be ventilated differently (with regard to the flow quantities and flow velocities), which is due to the different material accumulation in the individual zones Optimization of the pneumatic good discharge possible.

Wie bei dem Ausführungsbeispiel der Fig.1 1 und 2 strömt auch bei der Ausführung gemäß Fig. die Luft im wesentlichen von unten nach oben durch den Düsenring 5'. In Fig. ist die Luftströmung durch den Düsenring 5 durch den Pfeil 28 angedeutet. Dabei werden die feinen Bestandteile des über den Rand des Mahltellers 2 ausgetragenen zerkleinerten Gutes nach oben mitgenommen - Pfeil 29 -, während die groben Bestandteile des Mahlgutes entgegen dem Luftstrom nach unten fallen (Pfeil 29').As in the exemplary embodiment in FIGS. 1 1 and 2, in the embodiment according to FIG. 1 the air also flows essentially from bottom to top through the nozzle ring 5 '. In Fig. The air flow through the nozzle ring 5 is indicated by the arrow 28. The fine constituents of the comminuted material discharged over the edge of the grinding plate 2 are taken upward - arrow 29 -, while the coarse constituents of the ground material fall downward against the air flow (arrow 29 ').

Fig. 4 zeigt das Schema einer nach dem erfindungsgemäßen Verfahren betriebenen Mahlanlage.Fig. 4 shows the diagram of a grinding plant operated according to the inventive method.

Diese Mahlanlage enthält eine Ring- bzw. Rollenmühle 31, einen oberhalb der Mühle 31 angeordneten Sichter 32, einen Ventilator 33, ein Elektrofilter 34, ein Becherwerk 35 sowie eine Dosierbandwaage 36.This grinding system contains a ring or roller mill 31, a classifier 32 arranged above the mill 31, a fan 33, an electrostatic filter 34, a bucket elevator 35 and a dosing belt scale 36.

Der Ventilator 33 erzeugt einen Heißgasstrom, der der Mühle 31 über eine Leitung 37 zugeführt wird, der die Mühle mit dem bereits erläuterten Düsenring 5 durchsetzt, anschließend durch den Sichter 32 strömt und über eine Leitung 38 und das Elektrofilter 34 in einen Kamin 39 abgeführt wird. Eine Rückluftleitung 40 mit einer darin angeordneten Klappe 41 ermöglicht die Rückführung eines einstellbaren Anteiles des Gasstromes aus der Leitung 38 in die Leitung 37.The fan 33 generates a hot gas flow which is fed to the mill 31 via a line 37, which passes through the mill with the nozzle ring 5 already explained, then flows through the classifier 32 and is discharged via a line 38 and the electrostatic filter 34 into a chimney 39 . A return air line 40 with a flap 41 arranged therein enables the return of an adjustable portion of the gas flow from line 38 to line 37.

Das zu mahlende Gut wird von einem Silo 42 über die Dosierbandwaage 36 und eine Gutleitung 43 der Mühle 31 aufgegeben. Die feinen Bestandteile des über den Rand des Mahltellers 2 ausgetragenen zerkleinerten Mahlgutes werden vom Gasstrom erfaßt und nach oben zum Sichter 32 transportiert, wo das Fertiggut abgeschieden wird.The material to be ground is fed from a silo 42 via the dosing belt scale 36 and a material line 43 to the mill 31. The fine constituents of the comminuted ground material discharged over the edge of the grinding plate 2 are caught by the gas stream and transported upwards to the classifier 32, where the finished material is separated.

Die durch den Düsenring 5 nach unten fallenden groben Bestandteile des über den Rand des Mahltellers ausgetragenen zerkleinerten Mahlgutes gelangen über eine Gutleitung 44 in das Becherwerk 35, das sie nach oben zu einer Sieb- bzw. Verteilereinrichtung 45 fördert. Hier kann ein bestimmter Anteil, beispielsweise eine bestimmte Kornfraktion des Umlaufgutes abgezogen werden, während das Umlaufgut im übrigen über die Gutleitung 43 zurück zur Mühle 31 geführt wird.The coarse constituents of the comminuted ground material discharged through the nozzle ring 5 fall down through a feed line 44 into the bucket elevator 35, which conveys them upwards to a sieving or distribution device 45. Here, a certain proportion, for example a certain grain fraction, of the circulating material can be drawn off, while the circulating material is otherwise guided back to the mill 31 via the material line 43.

Die Anlage gemäß Fig. 4 enthält einen ersten Regelkreis, der die Menge des die Mühle 31 und den Sichter 32 durchsetzenden Heißgasstromes konstanthält. Zu diesem ersten Regelkreis gehört ein Regler 46, der von einem Venturirohr 47 in der Leitung 38 ein Signal über die die Leitung 38 durchsetzende Gasmenge erhält und der über einen Motor 48 den Ventilator 33 im Sinne einer Konstanthaltung der Gasmenge regelt.The system according to FIG. 4 contains a first control circuit which keeps the amount of the hot gas flow passing through the mill 31 and the classifier 32 constant. This first control circuit includes a controller 46, which receives a signal from a Venturi tube 47 in line 38 via the amount of gas passing through line 38 and which controls the fan 33 via a motor 48 in order to keep the amount of gas constant.

Weiterhin enthält die Anlage einen zweiten Regelkreis, durch den die Gasgeschwindigkeit im Düsenring 5 in Abhängigkeit von der Leistungsaufnahme des Becherwerks 35 so geändert wird, daß die Menge des über das Becherwerk 35 geförderten Gutes und seine Kornzusammensetzung konstantgehalten werden. Dieser zweite Regelkreis enthält einen übergeordneten Regler 49 sowie nachgeschaltete Regler 50a, 50b, 50c usw., deren Zusammenwirken anhand von Fig. 6 noch im einzelnen erläutert wird.Furthermore, the system contains a second control circuit by means of which the gas velocity in the nozzle ring 5 is changed as a function of the power consumption of the bucket elevator 35 in such a way that the quantity of the material conveyed via the bucket elevator 35 and its grain composition are kept constant. This second control loop contains a higher-level controller 49 and downstream controllers 50a, 50b, 50c etc., the interaction of which will be explained in detail with reference to FIG. 6.

Weiterhin ist ein dritter Regelkreis vorgesehen. der die Materialzuführung zur Mühle 31 verringert, wenn die Gasgeschwindigkeit im Düsenring 5 einen vorgegebenen Maximalwert übersteigt, während er die Materialzuführung vergrößert, wenn die Gasgeschwindigkeit im Düsenring 5 einen vorgegebenen Minimalwert unterschreitet. Dieser dritte Regelkreis enthält einen Regler 51, der an einen oder mehrere der nachgeschalteten Regler 50a, 50b, 50c, angeschlossen ist und auf die Dosierbandwaage 36 einwirkt.A third control loop is also provided. which reduces the material feed to the mill 31 when the gas speed in the nozzle ring 5 exceeds a predetermined maximum value, while it increases the material feed when the gas speed in the nozzle ring 5 falls below a predetermined minimum value steps. This third control circuit contains a controller 51, which is connected to one or more of the downstream controllers 50a, 50b, 50c and acts on the dosing belt scale 36.

Schließlich ist noch ein vierter Regelkreis vorgesehen, der die Temperatur des die Mühle 31 und den Sichter 32 durchsetzenden Heißgasstromes in der Weise regelt, daß die Gastemperatur nach dem Sichter 32 als Führungsgröße für den Sollwert der Gastemperatur vor der Mühle 31 verwendet wird. Dieser vierte Regelkreis enthält einen Regler 52, dem von einem Temperaturmeßelement 53 die Gastemperatur nach dem Sichter 32 als Führungsgröße für den Sollwert der Gastemperatur vor der Mühle 31 zugeführt wird. Die entsprechende Gastemperatur vor der Mühle 31 wird über einen Motor 54 eingestellt, der auf die in der Rückluftleitung 40 angeordnete Klappe 41 einwirkt. Statt dessen kann selbstverständlich auch eine (nicht dargestellte) Frischluftklappe verstellt werden.Finally, a fourth control circuit is provided, which controls the temperature of the hot gas flow passing through the mill 31 and the classifier 32 in such a way that the gas temperature after the classifier 32 is used as a guide variable for the setpoint value of the gas temperature before the mill 31. This fourth control circuit contains a controller 52, to which the gas temperature downstream of the classifier 32 is supplied by a temperature measuring element 53 as a reference variable for the target value of the gas temperature upstream of the mill 31. The corresponding gas temperature upstream of the mill 31 is set via a motor 54, which acts on the flap 41 arranged in the return air line 40. Instead of this, a fresh air flap (not shown) can of course also be adjusted.

Im Normalbetrieb erfolgt die Konstanthaltung der Menge des über das Becherwerk 35 geförderten Gutes und seiner Kornzusammensetzung durch den zweiten Regelkreis. Steigt die Menge der entgegen dem Gasstrom durch den Düsenring nach unten fallenden groben Bestandteile des über den Rand des Mahltellers ausgetragenen zerkleinerten Mahlgutes und vergrößert sich infolgedessen die Leistungsaufnahme des Becherwerks 35, so vergrößert der Regler 49 die Gasgeschwindigkeit im Düsenring 5 durch entsprechende Verkleinerung des lichten Düsenring-Querschnitts. Entsprechend wird bei einer Verringerung der Leistungsaufnahme des Becherwerks 38 die Gasgeschwindigkeit im Düsenring 5 verkleinert.In normal operation, the quantity of the material conveyed via the bucket elevator 35 and its grain composition are kept constant by the second control loop. If the amount of the coarse constituents of the comminuted material to be discharged, which falls downward against the gas flow through the nozzle ring, increases, and as a result the power consumption of the bucket elevator 35 increases, the controller 49 increases the gas velocity in the nozzle ring 5 by correspondingly reducing the clear nozzle ring -Section. Accordingly, the gas velocity in the nozzle ring 5 is reduced when the power consumption of the bucket elevator 38 is reduced.

Um jedoch bei einer wesentlichen Änderung der Mahlbarkeit des Gutes ein Vollaufen oder Leerfahren der Mühle zu verhindern, tritt der dritte Regelkreis in Funktion, wenn die Gasgeschwindigkeit im Düsenring 5 einen vorgegebenen Maximalwert übersteigt oder einen vorgegebenen Minimalwert unterschreitet. Im ersten Falle (bei drohendem Vollaufen der Mühle) wird durch den Regler 51 über die Dosierbandwaage 36 die Materialzuführung zur Mühle 31 verringert, im zweiten Falle (bei drohendem Leerfahren der Mühle) wird die Materialzuführung zur Mühle vergrößert.However, in order to prevent the mill from filling up or emptying when there is a significant change in the grindability of the material, the third control circuit comes into operation when the gas speed in the nozzle ring 5 exceeds a predetermined maximum value or falls below a predetermined minimum value. In the first case (when the mill threatens to run full), the material feed to the mill 31 is reduced by the controller 51 via the dosing belt scale 36, in the second case (when the mill threatens to run empty) the material feed to the mill is increased.

Fig. 5 veranschaulicht die Einrichtungen zur Veränderung des lichten Querschnitts des in mehrere, gesondert verstellbare Segmente 5a bis 5h unterteilten Düsenringes 5. Zur Verstellung dienen hydraulische oder pneumatische Zylinder 12, wie im einzelnen anhand der Fig. 1 bis 3 erläutert wurde. Berührungslose Wegaufnehmer 55 sind zur Feststellung der freien Querschnittsfläche des - Düsenringes 5 in den einzelnen Segmenten 5a bis 5h vorgesehen.FIG. 5 illustrates the devices for changing the clear cross section of the nozzle ring 5, which is divided into several, separately adjustable segments 5a to 5h. Hydraulic or pneumatic cylinders 12 are used for the adjustment, as was explained in detail with reference to FIGS. 1 to 3. Non-contact displacement transducers 55 are provided to determine the free cross-sectional area of the nozzle ring 5 in the individual segments 5a to 5h.

Das Zusammenwirken des übergeordneten Reglers 49 und der den einzelnen Segmenten 5a, 5b, 5c... zugeordneten nachgeschalteten Regler 50a, 50b, 50c... geht aus Fig. 6 hervor. Der übergeordnete Regler 49 erhält einen Istwert (Pfeil 56) des derzeitigen lichten Querschnitts des Düsenringes 5 von einem ausgewählten Segment (beispielsweise vom Segment 5b). Den Sollwert (Pfeil 57) erhält der Regler 49 in Abhängigkeit von der Leistungsaufnahme des Becherwerks 35. Das vom übergeordneten Regler 49 gebildete Signal (Pfeile 58a, 58b, 58c...) wird dann als Sollwert den nachgeschalteten Reglern 50a, 50b, 50c... zugeführt, die hydraulisch entriegelbare Absperrventile 59a, 60a, 59b, 60b, 59c, 60c... der Zylinder 12 der einzelnen Segmente 5a bis 5h betätigen.The interaction of the higher-level controller 49 and the downstream controllers 50a, 50b, 50c ... assigned to the individual segments 5a, 5b, 5c ... can be seen from FIG. 6. The higher-level controller 49 receives an actual value (arrow 56) of the current clear cross section of the nozzle ring 5 from a selected segment (for example from segment 5b). The controller 49 receives the setpoint (arrow 57) as a function of the power consumption of the bucket elevator 35. The signal formed by the higher-level controller 49 (arrows 58a, 58b, 58c ...) is then used as the setpoint for the downstream controllers 50a, 50b, 50c. .. supplied, the hydraulically unlockable shut-off valves 59a, 60a, 59b, 60b, 59c, 60c ... actuate the cylinder 12 of the individual segments 5a to 5h.

Die Nullpositionen der einzelnen Segmente können unterschiedlich eingestellt, d. h. einer unterschiedlichen lichten Querschnittsseite des Düsenringes im Bereich der einzelnen Segmente zugeordnet werden, so daß in den einzelnen Umfangsbereichen des Düsenringes 5 unterschiedliche Gasmengen (entsprechend der in diesen Umfangsbereichen unterschiedlichen Materialbeladung) eingestellt werden.The zero positions of the individual segments can be set differently, i. H. are assigned to a different clear cross-sectional side of the nozzle ring in the area of the individual segments, so that 5 different amounts of gas (corresponding to the different material loading in these peripheral areas) are set in the individual peripheral areas of the nozzle ring.

Claims (13)

1. Process for operating a crushing mill,
a) containing a ring mill (31) having a circular grinding plate (2) which rotates about a vertical axis (1) and co-operates with grinding elements (3, 4) and a nozzle ring (5) arranged stationary on the outer periphery of the grinding plate (2),
b) a sifter (32) arranged above the mill (31),
c) a blower (33) for producing a hot gas stream which passes through the nozzle ring (5) and the sifter (32), picks up the fine constituents of the comminuted material for grinding discharged over the edge of the grinding plate (2) and carries them upwards towards the sifter (32),
d) a bucket conveyor (35) by means of which the coarse constituents of the comminuted material for grinding discharged over the edge of the grinding plate (2) and falling downwards through the nozzle ring (5) are conveyed upwards,
e) in which the quantity of the hot gas stream passing through the mill (31) and the sifter (32) is kept constant by a first control circuit, characterised by the following features :
f) the gas speed in the nozzle ring (5) is altered by a second control circuit as a function of the power consumption of the bucket conveyor (35) so that the quantity of material conveyed by the bucket conveyor and the gradation of grain sizes thereof are kept constant,
g) a third control circuit reduces the material supply to the mill (31) when the gas speed in the nozzle ring (5) exceeds a predetermined maximum value, whereas the material supply is increased when the gas speed in the nozzle ring (5) falls below a predetermined minimum value.
2. Method as claimed in claim 1, characterised in that a fourth control circuit regulates the temperature of the hot gas stream passing through the mill (31) and the sifter (32) in such a way that the gas temperature after the sifter (32) is used as a command variable for the theoretical value for the gas temperature before the mill (31), and the gas temperature before the mill is preferably influenced by supplying fresh air and/or return air.
3. Method as claimed in claim 1, characterised in that the gas speed in the nozzle ring (5) is altered by adjustment of a wall (1) which limits the internal cross-section of the nozzle ring.
4. Method as claimed in claim 1, characterised in that in the individual peripheral regions (segments 5a to 5h) of the nozzle ring (5) different quantities of gas corresponding to the different material load in these peripheral regions can be set.
5. Crushing mill worked by the process as claimed in claim 1, containing
a) a ring mill (31) having a circular grinding plate (2) which rotates about a vertical axis (1) and co-operates with grinding elements (3, 4) and a nozzle ring (5) arranged stationary on the outer periphery of the grinding plate (2),
b) a sifter (32) arranged above the mill (31),
c) a blower (33) for producing a hot gas stream which passes through the nozzle ring (5) and the sifter (32),
d) a bucket conveyor (35) by means of which the coarse constituents of the comminuted material for grinding discharged over the edge of the grinding plate and falling downwards through the nozzle ring (5) are conveyed upwards,
e) a first control circuit for keeping the quantity of the hot gas stream passing through the mill (31) and the sifter (32) constant, characterised by
f) a second control circuit for altering the gas speed in the nozzle ring (5) as a function of the power consumption of the bucket conveyor (35),
g) a third control circuit for influencing the material supply to the mill (31) when the gas speed in the nozzle ring (5) exceeds a predetermined maximum value or falls below a predetermined minimum value.
6. Crushing mill as claimed in claim 5, characterised in that at least one wall (10) which limits the internal cross-section of the nozzle ring (5) is adjustable from the outside during operation.
7. Crushing mill as claimed in claim 5, characterised in that the nozzle ring (5) is divided into a plurality of separately adjustable segments (5a).
8. Crushing mill as claimed in claim 7, characterised in that a plurality of air supplies (20, 21, 22, 23) are provided with which separately adjustable segments (5'a. 5'b, 5'c. 5'd) are associated.
9. Crushing mill as claimed in claim 7, characterised in that the wall parts (10) which limit the internal cross-section of the individual segments (5a) of the nozzle ring (5) towards the outside are adjustable in the radial direction by an electric, hydraulic or pneumatic drive (12).
10. Crushing mill as claimed in claim 9, characterised in that the adjustable wall parts (10) are guided in the region of their ends facing the adjacent segments on parallel guide surfaces (7a, 8a) of stationary guide parts (7, 8).
11. Crushing mill as claimed in claim 7, characterised in that the nozzle ring (5) has individual unventilated segments between ventilated and adjustable segments.
12. Crushing mill as claimed in claim 7, characterised in that non-contact displacement pickups (55) are provided for determining the free cross- sectional surface of the nozzle ring (5) in the individual segments (5a to 5h).
13. Crushing mill as claimed in claim 7, characterised by
a) a master regulator (49) which receives its actual value from a segment (e. g. 5b) of the. nozzle ring (5) and its theoretical value from the bucket conveyor (35),
b) regulators (50a to 50h) which are associated with the individual segments (5a to 5h) of the nozzle ring (5) and receive their theoretical value from the master regulator (49) and their actual value from the appertaining segment of the nozzle ring.
EP85105567A 1984-05-16 1985-05-07 Process for operating a crushing mill, and crushing mill working by this process Expired EP0165429B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3418196A DE3418196A1 (en) 1984-05-16 1984-05-16 RINGMILL WITH ADJUSTABLE NOZZLE RING
DE3418196 1984-05-16

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EP0165429A1 EP0165429A1 (en) 1985-12-27
EP0165429B1 true EP0165429B1 (en) 1986-12-30

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EP (1) EP0165429B1 (en)
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US5312052A (en) * 1992-06-01 1994-05-17 Dellekamp Michael D Method for reclaiming fiber reinforcement from a composite
DE4223151C2 (en) * 1992-07-14 1994-11-10 Loesche Gmbh Process for grinding raw lignite
DE4412197A1 (en) * 1994-04-08 1995-10-19 Loesche Gmbh Method and device for comminuting material of different grain sizes, in particular an airflow mill
DE19844112A1 (en) * 1998-09-25 2000-03-30 Loesche Gmbh Bucket ring for airflow roller mills
DE19844113A1 (en) * 1998-09-25 2000-03-30 Loesche Gmbh Bucket ring for airflow roller mills
US6213415B1 (en) 1999-09-13 2001-04-10 W.R. Grace & Co.-Conn. Process for improving grinding of cement clinker in mills employing rollers
US6409108B1 (en) 2000-12-22 2002-06-25 Sure Alloy Steel Corporation Damage-resistant deflector vane
GB2451457B (en) * 2007-07-31 2010-04-14 Paul Andrew Comer Improvement in relation to grinding mills
CN104759338B (en) * 2015-03-13 2017-06-13 东莞市美力自动化设备有限公司 Automatic grinding machine
WO2018016104A1 (en) * 2016-07-21 2018-01-25 株式会社Ihi Vertical roller mill

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DE818721C (en) * 1949-05-11 1952-08-04 Ernst Guenter Loesche Spring roller mill
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DE3134601C2 (en) * 1981-09-01 1985-10-31 Loesche GmbH, 4000 Düsseldorf Roller bowl mill

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DE3418196A1 (en) 1985-11-21
ES8703297A1 (en) 1987-02-16
DE3560034D1 (en) 1987-02-05
EP0165429A1 (en) 1985-12-27
ES543134A0 (en) 1987-02-16
US4598872A (en) 1986-07-08

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