EP0745427A1 - Monitoring device for ball mills - Google Patents

Monitoring device for ball mills Download PDF

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Publication number
EP0745427A1
EP0745427A1 EP96401133A EP96401133A EP0745427A1 EP 0745427 A1 EP0745427 A1 EP 0745427A1 EP 96401133 A EP96401133 A EP 96401133A EP 96401133 A EP96401133 A EP 96401133A EP 0745427 A1 EP0745427 A1 EP 0745427A1
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EP
European Patent Office
Prior art keywords
balls
mill
coal
receiver
electronic circuit
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Granted
Application number
EP96401133A
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German (de)
French (fr)
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EP0745427B1 (en
Inventor
Daniel Fontanille
Jacques Barbot
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Alstom Power Boiler SA
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GEC Alsthom Stein Industrie
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Publication of EP0745427A1 publication Critical patent/EP0745427A1/en
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B02CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02CCRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C17/00Disintegrating by tumbling mills, i.e. mills having a container charged with the material to be disintegrated with or without special disintegrating members such as pebbles or balls
    • B02C17/18Details
    • B02C17/1805Monitoring devices for tumbling mills
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B02CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02CCRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C25/00Control arrangements specially adapted for crushing or disintegrating

Definitions

  • the present invention relates to a device for monitoring a ball mill.
  • It relates more precisely to a device for monitoring a ball mill with a cylindrical casing, containing a mass of balls which are arranged during the rotation of the mill at its normal speed between two generators (1 b , 1 b ') spaced apart by a minimum angle ⁇ min and a maximum angle ⁇ max and a mass of coal which is disposed during the rotation of the mill at its normal speed between two generators (1 c , 1 c ') spaced by an angle ⁇ .
  • a first system is based on the variation of the measurement of the power absorbed by the electric motor causing the rotation of the ball mill. This method is not very sensitive; in addition, it requires frequent recalibration according to the wear of the balls or the addition of new balls.
  • level probes Pneumatic probes, each comprising a pneumatic hose, one end of which is inserted inside the mill, make it possible to carry out measurements of the pressure difference existing between two levels; we can deduce the amount of coal in the grinder.
  • the level sensors are installed in a hostile environment (carbon dust, falls balls, risk of blockage, etc ...) making the risk of breakdowns significant; the probes are connected to a complex pneumatic cabinet, therefore expensive, costly to maintain. The availability of such a system is average.
  • Another system is based on measuring the noise emitted by the mill.
  • This method has the disadvantage of providing a signal which is very dependent on the flow rate of the mill, the size of the pieces of coal introduced, the quantity of balls present in the mill and the wear of the armor plates fitted to the internal walls of the mill. .
  • the object of the invention is to provide a monitoring device for a ball mill, which allows continuous control of these three parameters (quantity of coal, quantity of balls, wear of the casing) using sensors external to the polluting atmosphere inside the grinder and independent of the grinding medium.
  • the device according to the invention also allows a direct measurement of these parameters which is reliable.
  • the monitoring device comprises a wave transmitter, chosen from electromagnetic waves, placed inside the mill and at least one wave receiver placed outside the envelope, the receiver being associated with an electronic circuit for determining at least one parameter of the mill chosen from the quantity of balls, quantity of coal and wear of the envelope.
  • the receiver in order to monitor the quantity of balls, it comprises at least one wave receiver arranged opposite the generator l b and at least one wave receiver arranged opposite the generator l b ', corresponding to the angle ⁇ min , the receiver being associated with an electronic circuit for determining the quantity of balls.
  • the envelope in order to monitor the wear of the envelope, it comprises at least one wave receiver arranged outside the angular sectors ⁇ max and ⁇ , the receiver being associated with an electronic determination circuit the wear of the envelope.
  • the receiver in order to monitor the quantity of coal, it comprises at least one wave receiver arranged in the angular sector ⁇ not common to the angular sector ⁇ max , the receiver being associated with an electronic circuit for determining the quantity of coal.
  • the receiver in order to monitor the three parameters, it comprises at least one wave receiver arranged rotatably around the longitudinal axis of the envelope on an angular sector ⁇ greater than the angular sector encompassing ⁇ and ⁇ , the receiver being associated with an electronic circuit for determining the wear of the shell of the mill, the quantity of balls and the quantity of coal, the ball mill containing a mass of balls being arranged during the rotation of the mill its normal speed between two generators (l b , l b ') spaced by an angle ⁇ and a mass of coal disposing during rotation of the mill at its normal speed between two generators (l c , l c ') spaced by an angle ⁇ .
  • the transmitter is arranged on the longitudinal axis of the mill.
  • the emitter is a gamma photon emitter.
  • the electronic circuit for determining the quantity of balls comprises associated with each receiver a converter and a linearizer, the signals of each linearizer being associated to carry out the calculation of the quantity of balls.
  • the electronic circuit for determining the wear of the envelope, for its part, comprises a converter associated with a device for reading the degree of wear.
  • the electronic circuit for determining the quantity of coal, for its part comprises a converter whose signal is corrected by the wear signal of the envelope measured previously.
  • Figure 1 is a longitudinal sectional view of a coal grinding installation provided with the monitoring device according to the invention.
  • Figure 2 is a sectional view along line II-II of Figure 1 of a first embodiment of the monitoring device according to the invention.
  • Figure 3 is an electronic circuit diagram of the monitoring device according to the invention.
  • Figure 4 is a sectional view along line II-II of Figure 1 of a second embodiment of the monitoring device according to the invention.
  • FIG. 5 is a graph representing the monitoring signal obtained using the device shown in FIG. 4.
  • FIG. 1 schematically represents a coal grinding installation comprising at least one feed device 10 supplying coal to a ball mill generally designated by the reference 20.
  • the feed device 10 comprises a storage hopper 1 from which the coal 2 is extracted, which is brought by a chain conveyor 3 placed in a box 4 and driven by a motor 5, at a first end of a vertical pipe 6.
  • the crusher 20 comprises a cylindrical metallic envelope or ferrule 11 terminated by two conical portions 12 and 13 to which are fixed respectively two pins 14 and 15 intended to support the ferrule.
  • the pins are placed respectively on two bearings 16 and 17 provided with bearings.
  • the crusher is rotated by means of a toothed ring 18 cooperating with a pinion not shown driven by an electric geared motor not shown.
  • tubular portions 21 and 22 respectively provided with a coaxial elastic Archimedes screw 23 and 24 and driven in rotation with the crusher.
  • Hot air is introduced through pipes 25 and 26 respectively inside the tubular portions 21 and 22 under a pressure of a few tens of hectopascals.
  • the coal arrives by gravity through the pipe 6, the second end of which opens out in line with the tubular portion 22.
  • the coal also arrives on the other tubular portion 21 via a pipe 16 'from another non-feeding device. represented.
  • the coal is entrained inside the mill by the rotation of the Archimedes screws 23 and 24.
  • the mill is lined with balls 27, for example of steel.
  • the balls crush the coal; the fine particles of carbon are entrained by hot air, in the annular spaces 28, 29 included respectively between the ferrules 14, 15 and the tubular portions 21, 22, and evacuated towards the burners by conduits 30 and 31.
  • the monitoring device comprises a wave emitter 33, chosen from electromagnetic waves, disposed inside the envelope 11. It is fixed and rotatably supported for example in a socket carried by an arrangement of stays 36 welded to inside the tube carrying the Archimedes screw 23.
  • a wave emitter 33 chosen from electromagnetic waves
  • the monitoring device is arranged on the longitudinal axis of the envelope 11.
  • it is a transmitter of gamma photons.
  • a support assembly of receivers 34 arranged outside the envelope 11 and which will be specified below.
  • Figure 2 is an enlarged sectional view of the envelope, in operation.
  • the mass of balls 27 offset by the rotation of the casing 11 in the direction of the arrow.
  • the mass of coal 32 resulting from the grinding overcomes this mass 27.
  • the mass of balls 27 is arranged during the rotation of the mill at its normal speed between two generators l b , l b 'spaced by an angle ⁇ comprised between a minimum angle ⁇ min and a maximum angle ⁇ max .
  • the coal mass 32 is arranged during the rotation of the mill at its normal speed between two generators l c , l c 'spaced at an angle ⁇ .
  • the transmitter 33 scans a beam of waves inside the envelope 11.
  • the signals generated by the receivers 34A and 34B make it possible to know the total absorption zone due to the presence of the balls 27 or at least to check that this area is greater than the minimum allowable area.
  • the signal generated by the receiver 34C makes it possible to measure the wear of the envelope 11 by determining the variation in absorption as a function of the thickness of the envelope 11.
  • the signal generated by the receiver 34D makes it possible to measure the quantity of carbon 32 by determining the variation in absorption through this mass 32, taking into account the variation due to the thickness of the envelope 11 determined by means of the receiver 34C.
  • FIG. 3 schematically represents an example of an electronic circuit for measuring the three parameters.
  • the electronic circuit for determining the quantity of balls comprises associated with each receiver 34A, 34B a converter 40A, 40B and a linearizer 41A, 41B, the signals of each linearizer 41A, 41B being associated by summation 42A then linearized 43A to perform the calculation of the quantity of balls 27 transmitted on a reading device 44A.
  • the electronic circuit for determining the wear of the envelope comprises a converter 40C associated with a device for reading the degree of wear 44C.
  • the electronic circuit for determining the quantity of coal comprises a converter 40D, the signal of which is corrected by differentiation by the wear signal 41D of the casing 11 measured at the output of the converter 40C.
  • FIG. 4 A second embodiment is shown in FIG. 4.
  • a wave receiver 34 disposed outside the envelope 11 rotates at a speed ⁇ around the longitudinal axis of the envelope 11 over an angular sector ⁇ greater than the angular sector encompassing ⁇ and ⁇ , the receiver 34 being associated with an electronic circuit for determining the wear of the shredder shell, the quantity of balls and the quantity of coal.
  • the elements to be monitored and observed are "scanned" using a position indexing system depending on the areas to be observed and the type of measurement to be performed.
  • FIG. 5 An example of a signal obtained using this monitoring device is shown in FIG. 5.
  • This signal represents the amplitude A of the wave received by the receiver 34 as a function of its position x when it traverses the angular sector ⁇ at the speed ⁇ .
  • the first zone D1 makes it possible to follow the wear of the envelope 11, by determining the evolution of the curve.
  • the curve C2 represents a degree of wear with respect to the initial curve C1.
  • the second zone D2 makes it possible to control the quantity of carbon by monitoring the attenuation of the signal as a function of the abscissa x1.
  • Curve C1 ′ shows the evolution of the signal in the case of an empty mill, the set of curves C1 giving the appearance of this same signal as a function of filling with coal.
  • the third zone D3 makes it possible to control the quantity of balls 27 by measuring its length on the abscissa.
  • curve C2 represents a reduction in this quantity of balls compared to the initial curve C1.
  • such a signal can be read and thus allows the continuous monitoring of the three parameters which are the wear of the envelope, the quantity of coal and the quantity of balls of the grinder.

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  • Engineering & Computer Science (AREA)
  • Food Science & Technology (AREA)
  • Crushing And Grinding (AREA)
  • Disintegrating Or Milling (AREA)
  • Metal Rolling (AREA)
  • Sampling And Sample Adjustment (AREA)
  • Constituent Portions Of Griding Lathes, Driving, Sensing And Control (AREA)

Abstract

The grinder has a cylindrical casing containing a number of balls which, when the grinder is rotating at its nominal speed, takes up a position between two generatrices spaced by an angle between a minimal angle alphamin and a maximal angle alphamax. An amount of coal is also included which, when the grinder is rotating at its nominal speed, takes up a position between two generatrices spaced by an angle beta. An electromagnetic wave emitter is disposed inside the grinder and at least one wave receiver is disposed outside the grinder. The receiver is associated with an electronic circuit for determining at least one parameter of the grinder selected from the quantity of balls, the quantity of coal and the wear of the cylinder.

Description

La présente invention se rapporte à un dispositif de surveillance d'un broyeur à boulets.The present invention relates to a device for monitoring a ball mill.

Elle concerne plus précisément un dispositif de surveillance d'un broyeur à boulets à enveloppe cylindrique, contenant une masse de boulets se disposant lors de la rotation du broyeur à sa vitesse normale entre deux génératrices (1b, 1b') espacées d'un angle minimal αmin et d'un angle maximal αmax et une masse de charbon se disposant lors de la rotation du broyeur à sa vitesse normale entre deux génératrices (1c, 1c') espacées d'un angle β.It relates more precisely to a device for monitoring a ball mill with a cylindrical casing, containing a mass of balls which are arranged during the rotation of the mill at its normal speed between two generators (1 b , 1 b ') spaced apart by a minimum angle α min and a maximum angle α max and a mass of coal which is disposed during the rotation of the mill at its normal speed between two generators (1 c , 1 c ') spaced by an angle β.

Lors de l'utilisation d'un broyeur à boulets, il est nécessaire de s'assurer en permanence que la quantité de charbon soit constante, de manière à assurer un broyage et un séchage optimaux. Si la quantité de charbon introduite est trop importante, le broyage est insuffisant et le séchage imparfait; si la quantité de charbon introduite est trop faible, la chaudière en aval est insuffisamment alimentée.When using a ball mill, it is necessary to constantly make sure that the quantity of coal is constant, so as to ensure optimal grinding and drying. If the quantity of coal introduced is too great, the grinding is insufficient and the drying imperfect; if the quantity of coal introduced is too low, the downstream boiler is insufficiently supplied.

Des systèmes ont été envisagés pour estimer la quantité de charbon contenue dans un broyeur à boulets en fonctionnement.Systems have been envisaged for estimating the quantity of coal contained in a ball mill in operation.

Un premier système est fondé sur la variation de la mesure de la puissance absorbée par le moteur électrique entraînant la rotation du broyeur à boulets. Cette méthode est peu sensible; en outre, elle nécessite un réétalonnage fréquent en fonction de l'usure des boulets ou de l'adjonction de nouveaux boulets.A first system is based on the variation of the measurement of the power absorbed by the electric motor causing the rotation of the ball mill. This method is not very sensitive; in addition, it requires frequent recalibration according to the wear of the balls or the addition of new balls.

Un autre système est fondé sur l'utilisation de sondes de niveau. Des sondes pneumatiques, comprenant chacune un tuyau pneumatique dont une extrémité est introduite à l'intérieur du broyeur, permettent d'effectuer des mesures de la différence de pression existant entre deux niveaux; on peut en déduire la quantité de charbon se trouvant dans le broyeur. Cependant, les sondes de niveau sont installées dans un environnement hostile (poussière de charbon, chutes de boulets, risques de bouchage, etc...) rendant le risque de pannes important; les sondes sont reliées à une armoire pneumatique complexe, donc onéreuse, de maintenance coûteuse. La disponibilité d'un tel système est moyenne.Another system is based on the use of level probes. Pneumatic probes, each comprising a pneumatic hose, one end of which is inserted inside the mill, make it possible to carry out measurements of the pressure difference existing between two levels; we can deduce the amount of coal in the grinder. However, the level sensors are installed in a hostile environment (carbon dust, falls balls, risk of blockage, etc ...) making the risk of breakdowns significant; the probes are connected to a complex pneumatic cabinet, therefore expensive, costly to maintain. The availability of such a system is average.

Un autre système est fondée sur la mesure du bruit émis par le broyeur. Cette méthode présente l'inconvénient de fournir un signal très dépendant du débit du broyeur, de la taille des morceaux de charbon introduits, de la quantité de boulets présente dans le broyeur et de l'usure des plaques de blindage équipant les parois internes du broyeur.Another system is based on measuring the noise emitted by the mill. This method has the disadvantage of providing a signal which is very dependent on the flow rate of the mill, the size of the pieces of coal introduced, the quantity of balls present in the mill and the wear of the armor plates fitted to the internal walls of the mill. .

Il est également nécessaire de contrôler la quantité ou la masse des boulets présents dans le broyeur, ceux-ci s'usant jusqu'à atteindre une masse insuffisante non efficace.It is also necessary to control the quantity or the mass of the balls present in the grinder, these wearing out until reaching an insufficient mass which is not effective.

Il existe certaines méthodes indirectes de suivi de l'évolution du bruit ou de la puissance électrique absorbée par le moteur électrique d'entraînement permettant par corrélation de connaître la quantité de boulets. Toutefois, ces méthodes sont toutes indirectes et ne se fondent pas sur une mesure physique directe.There are certain indirect methods of monitoring the evolution of the noise or of the electrical power absorbed by the electric drive motor making it possible by correlation to know the quantity of balls. However, these methods are all indirect and do not rely on direct physical measurement.

Il est enfin important de contrôler le degré d'usure de l'enveloppe d'un broyeur à boulets.It is finally important to check the degree of wear of the envelope of a ball mill.

En effet, ce contrôle permet de s'assurer de l'efficacité des releveurs, parties longitudinales saillantes à l'intérieur de l'enveloppe du broyeur, dont dépend le bon malaxage du mélange du charbon et des boulets.Indeed, this control makes it possible to make sure of the efficiency of the lifters, protruding longitudinal parts inside the envelope of the crusher, on which depends the good kneading of the mixture of coal and balls.

Le but de l'invention est de réaliser un dispositif de surveillance d'un broyeur à boulets, qui permette le contrôle en continu de ces trois paramètres (quantité de charbon, quantité de boulets, usure de l'enveloppe) à l'aide de capteurs extérieurs à l'atmosphère polluante de l'intérieur du broyeur et indépendants du milieu broyant.The object of the invention is to provide a monitoring device for a ball mill, which allows continuous control of these three parameters (quantity of coal, quantity of balls, wear of the casing) using sensors external to the polluting atmosphere inside the grinder and independent of the grinding medium.

Le dispositif conforme à l'invention permet de plus une mesure directe de ces paramètres qui soit fiable.The device according to the invention also allows a direct measurement of these parameters which is reliable.

Pour ce faire, le dispositif de surveillance conforme à l'invention, comporte un émetteur d'ondes, choisies parmi les ondes électromagnétiques, disposé à l'intérieur du broyeur et au moins un récepteur d'ondes disposé à l'extérieur de l'enveloppe, le récepteur étant associé à un circuit électronique de détermination d'au moins un paramètre du broyeur choisi parmi la quantité de boulets, la quantité de charbon et l'usure de l'enveloppe.To do this, the monitoring device according to the invention comprises a wave transmitter, chosen from electromagnetic waves, placed inside the mill and at least one wave receiver placed outside the envelope, the receiver being associated with an electronic circuit for determining at least one parameter of the mill chosen from the quantity of balls, quantity of coal and wear of the envelope.

Selon un premier mode de réalisation, afin de surveiller la quantité de boulets, il comporte au moins un récepteur d'ondes disposé face à la génératrice lb et au moins un récepteur d'ondes disposé face à la génératrice lb', correspondantes à l'angle αmin, le récepteur étant associé à un circuit électronique de détermination de la quantité de boulets.According to a first embodiment, in order to monitor the quantity of balls, it comprises at least one wave receiver arranged opposite the generator l b and at least one wave receiver arranged opposite the generator l b ', corresponding to the angle α min , the receiver being associated with an electronic circuit for determining the quantity of balls.

Selon un premier mode de réalisation, afin de surveiller l'usure de l'enveloppe, il comporte au moins un récepteur d'ondes disposé à l'extérieur des secteurs angulaires αmax et β, le récepteur étant associé à un circuit électronique de détermination de l'usure de l'enveloppe.According to a first embodiment, in order to monitor the wear of the envelope, it comprises at least one wave receiver arranged outside the angular sectors α max and β, the receiver being associated with an electronic determination circuit the wear of the envelope.

Selon un premier mode de réalisation, afin de surveiller la quantité de charbon, il comporte au moins un récepteur d'ondes disposé dans le secteur angulaire β non commun au secteur angulaire αmax, le récepteur étant associé à un circuit électronique de détermination de la quantité de charbon.According to a first embodiment, in order to monitor the quantity of coal, it comprises at least one wave receiver arranged in the angular sector β not common to the angular sector α max , the receiver being associated with an electronic circuit for determining the quantity of coal.

Selon un second mode de réalisation, afin de surveiller les trois paramètres, il comporte au moins un récepteur d'ondes disposé rotatif autour de l'axe longitudinal de l'enveloppe sur un secteur angulaire δ supérieur au secteur angulaire englobant α et β, le récepteur étant associé à un circuit électronique de détermination de l'usure de l'enveloppe du broyeur, de la quantité de boulets et de la quantité de charbon, le broyeur à boulets contenant une masse de boulets se disposant lors de la rotation du broyeur à sa vitesse normale entre deux génératrices (lb, lb') espacées d'un angle α et une masse de charbon se disposant lors de la rotation du broyeur à sa vitesse normale entre deux génératrices (lc, lc') espacées d'un angle β.According to a second embodiment, in order to monitor the three parameters, it comprises at least one wave receiver arranged rotatably around the longitudinal axis of the envelope on an angular sector δ greater than the angular sector encompassing α and β, the receiver being associated with an electronic circuit for determining the wear of the shell of the mill, the quantity of balls and the quantity of coal, the ball mill containing a mass of balls being arranged during the rotation of the mill its normal speed between two generators (l b , l b ') spaced by an angle α and a mass of coal disposing during rotation of the mill at its normal speed between two generators (l c , l c ') spaced by an angle β.

De préférence, l'émetteur est disposé sur l'axe longitudinal du broyeur.Preferably, the transmitter is arranged on the longitudinal axis of the mill.

Avantageusement, l'émetteur est un émetteur de photons gamma.Advantageously, the emitter is a gamma photon emitter.

Le circuit électronique de détermination de la quantité de boulets, quant à lui, comprend associé à chaque récepteur un convertisseur et un linéarisateur, les signaux de chaque linéarisateur étant associés pour réaliser le calcul de la quantité de boulets.The electronic circuit for determining the quantity of balls, for its part, comprises associated with each receiver a converter and a linearizer, the signals of each linearizer being associated to carry out the calculation of the quantity of balls.

Le circuit électronique de détermination de l'usure de l'enveloppe, quant à lui, comprend un convertisseur associé à un dispositif de lecture du degré d'usure.The electronic circuit for determining the wear of the envelope, for its part, comprises a converter associated with a device for reading the degree of wear.

Le circuit électronique de détermination de la quantité de charbon, quant à lui, comporte un convertisseur dont le signal est corrigé par le signal d'usure de l'enveloppe mesuré précédemment.The electronic circuit for determining the quantity of coal, for its part, comprises a converter whose signal is corrected by the wear signal of the envelope measured previously.

L'invention est décrite ci-après plus en détail à l'aide de figures ne représentant que des modes de réalisation préférés de l'invention.The invention is described below in more detail using figures representing only preferred embodiments of the invention.

La figure 1 est une vue en coupe longitudinale d'une installation de broyage de charbon pourvu du dispositif de surveillance conforme à l'invention.Figure 1 is a longitudinal sectional view of a coal grinding installation provided with the monitoring device according to the invention.

La figure 2 est une vue en coupe selon la ligne II-II de la figure 1 d'un premier mode de réalisation du dispositif de surveillance conforme à l'invention.Figure 2 is a sectional view along line II-II of Figure 1 of a first embodiment of the monitoring device according to the invention.

La figure 3 est un schéma de circuit électronique du dispositif de surveillance conforme à l'invention.Figure 3 is an electronic circuit diagram of the monitoring device according to the invention.

La figure 4 est une vue en coupe selon la ligne II-II de la figure 1 d'un second mode de réalisation du dispositif de surveillance conforme à l'invention.Figure 4 is a sectional view along line II-II of Figure 1 of a second embodiment of the monitoring device according to the invention.

La figure 5 est un graphe représentant le signal de surveillance obtenu grâce au dispositif représenté sur la figure 4.FIG. 5 is a graph representing the monitoring signal obtained using the device shown in FIG. 4.

Dans l'exemple décrit maintenant et représenté dans la figure 1, il est question d'un broyeur cylindrique avec alimentation par vis d'Archimède. Il est bien clair que l'invention s'applique à tout type de broyeurs à boulets (broyeurs biconiques par exemple) quel que soit le dispositif d'introduction du charbon à l'intérieur du broyeur.In the example now described and shown in Figure 1, there is a cylindrical mill with feed by Archimedes screw. It is clear that the invention applies to all types of ball mills (biconical mills for example) regardless of the device for introducing carbon inside the mill.

La figure 1 représente schématiquement une installation de broyage de charbon comprenant au moins un dispositif d'alimentation 10 alimentant en charbon un broyeur à boulets globalement désigné par la référence 20.FIG. 1 schematically represents a coal grinding installation comprising at least one feed device 10 supplying coal to a ball mill generally designated by the reference 20.

Le dispositif d'alimentation 10 comprend une trémie de stockage 1 dont est extrait le charbon 2 qui est amené par un convoyeur à chaîne 3 placé dans un caisson 4 et entraîné par un moteur 5, à un première extrémité d'une tuyauterie verticale 6.The feed device 10 comprises a storage hopper 1 from which the coal 2 is extracted, which is brought by a chain conveyor 3 placed in a box 4 and driven by a motor 5, at a first end of a vertical pipe 6.

Le broyeur 20 comprend une enveloppe ou virole métallique cylindrique 11 terminée par deux portions coniques 12 et 13 auxquelles sont fixés respectivement deux tourillons 14 et 15 destinés à supporter la virole. Les tourillons sont posés respectivement sur deux paliers 16 et 17 munis de coussinets. Le broyeur est entraîné en rotation grâce à une couronne dentée 18 coopérant avec un pignon non représenté entraîné par un moto-réducteur électrique non représenté.The crusher 20 comprises a cylindrical metallic envelope or ferrule 11 terminated by two conical portions 12 and 13 to which are fixed respectively two pins 14 and 15 intended to support the ferrule. The pins are placed respectively on two bearings 16 and 17 provided with bearings. The crusher is rotated by means of a toothed ring 18 cooperating with a pinion not shown driven by an electric geared motor not shown.

Dans l'axe des viroles 14 et 15 sont disposés deux portions tubulaires 21 et 22 munies respectivement d'une vis d'Archimède élastique coaxiale 23 et 24 et entraînées en rotation avec le broyeur. De l'air chaud est introduit par des canalisations respectivement 25 et 26 à l'intérieur des portions tubulaires 21 et 22 sous une pression de quelques dizaines d'hectopascals. Le charbon arrive par gravité à travers la canalisation 6 dont la seconde extrémité débouche au droit de la portion tubulaire 22. Le charbon arrive également sur l'autre portion tubulaire 21 par une canalisation 16' d'un autre dispositif d'alimentation non représenté. Le charbon est entraîné à l'intérieur du broyeur par la rotation des vis d'Archimède 23 et 24.In the axis of the ferrules 14 and 15 are arranged two tubular portions 21 and 22 respectively provided with a coaxial elastic Archimedes screw 23 and 24 and driven in rotation with the crusher. Hot air is introduced through pipes 25 and 26 respectively inside the tubular portions 21 and 22 under a pressure of a few tens of hectopascals. The coal arrives by gravity through the pipe 6, the second end of which opens out in line with the tubular portion 22. The coal also arrives on the other tubular portion 21 via a pipe 16 'from another non-feeding device. represented. The coal is entrained inside the mill by the rotation of the Archimedes screws 23 and 24.

Le broyeur est garni de boulets 27, par exemple d'acier. Lorsque la virole tourne, les boulets écrasent le charbon; les particules fines de charbon sont entraînées par l'air chaud, dans les espaces annulaires 28, 29 compris respectivement entre les viroles 14, 15 et les portions tubulaires 21, 22, et évacuées vers les brûleurs par des conduits 30 et 31.The mill is lined with balls 27, for example of steel. When the ferrule turns, the balls crush the coal; the fine particles of carbon are entrained by hot air, in the annular spaces 28, 29 included respectively between the ferrules 14, 15 and the tubular portions 21, 22, and evacuated towards the burners by conduits 30 and 31.

Le dispositif de surveillance comporte un émetteur d'ondes 33, choisies parmi les ondes électromagnétiques, disposé à l'intérieur de l'enveloppe 11. Il est fixe et supporté rotatif par exemple dans une douille portée par un agencement d'étais 36 soudés à l'intérieur du tube porteur de la vis d'Archimède 23. Avantageusement, il est disposé sur l'axe longitudinal de l'enveloppe 11. Selon le mode de réalisation préféré de l'invention, il s'agit d'un émetteur de photons gamma.The monitoring device comprises a wave emitter 33, chosen from electromagnetic waves, disposed inside the envelope 11. It is fixed and rotatably supported for example in a socket carried by an arrangement of stays 36 welded to inside the tube carrying the Archimedes screw 23. Advantageously, it is arranged on the longitudinal axis of the envelope 11. According to the preferred embodiment of the invention, it is a transmitter of gamma photons.

Supporté par un châssis fixe 35, est disposé autour de l'enveloppe 11 un ensemble support de récepteurs 34 disposés à l'extérieur de l'enveloppe 11 et qui seront précisés plus loin.Supported by a fixed frame 35, is arranged around the envelope 11 a support assembly of receivers 34 arranged outside the envelope 11 and which will be specified below.

La figure 2 est une vue agrandie en coupe de l'enveloppe, en fonctionnement. On distingue la masse des boulets 27, déportée par la rotation de l'enveloppe 11 dans le sens de la flèche. La masse de charbon 32 résultant du broyage surmonte cette masse 27. La masse de boulets 27 se dispose lors de la rotation du broyeur à sa vitesse normale entre deux génératrices lb, lb' espacées d'un angle α compris entre un angle minimal αmin et un angle maximal αmax. La masse de charbon 32 se dispose lors de la rotation du broyeur à sa vitesse normale entre deux génératrices lc, lc' espacées d'un angle β.Figure 2 is an enlarged sectional view of the envelope, in operation. We distinguish the mass of balls 27, offset by the rotation of the casing 11 in the direction of the arrow. The mass of coal 32 resulting from the grinding overcomes this mass 27. The mass of balls 27 is arranged during the rotation of the mill at its normal speed between two generators l b , l b 'spaced by an angle α comprised between a minimum angle α min and a maximum angle α max . The coal mass 32 is arranged during the rotation of the mill at its normal speed between two generators l c , l c 'spaced at an angle β.

Selon le premier mode de réalisation représenté sur la figure 2, l'ensemble support 34 comporte quatre récepteurs:

  • un récepteur d'ondes 34A disposé face à la génératrice lb et un récepteur d'ondes 34B disposé face à la génératrice lb', correspondantes à l'angle αmin, le récepteur étant associé à un circuit électronique de détermination de la quantité de boulets,
  • un récepteur d'ondes 34C disposé à l'extérieur des secteurs angulaires αmax et β, le récepteur étant associé à un circuit électronique de détermination de l'usure de l'enveloppe,
  • un récepteur d'ondes 34D disposé dans le secteur angulaire β non commun au secteur angulaire α, le récepteur étant associé à un circuit électronique de détermination de la quantité de charbon.
According to the first embodiment shown in FIG. 2, the support assembly 34 includes four receivers:
  • a wave receiver 34A arranged opposite the generator l b and a wave receiver 34B arranged opposite the generator l b ', corresponding to the angle α min , the receiver being associated with an electronic circuit for determining the quantity balls,
  • a 34C wave receiver placed outside the angular sectors α max and β, the receiver being associated with an electronic circuit for determining the wear of the envelope,
  • a 34D wave receiver arranged in the angular sector β not common to the angular sector α, the receiver being associated with an electronic circuit for determining the quantity of coal.

L'émetteur 33 balaie un faisceau d'ondes à l'intérieur de l'enveloppe 11. Les signaux engendrés par les récepteurs 34A et 34B permettent de connaître la zone d'absorption totale due à la présence des boulets 27 ou au moins de vérifier que cette zone est supérieure à la zone minimale admissible. Le signal engendré par le récepteur 34C permet de mesurer l'usure de l'enveloppe 11 par détermination de la variation d'absorption en fonction de l'épaisseur de l'enveloppe 11. Le signal engendré par le récepteur 34D permet de mesurer la quantité de charbon 32 par détermination de la variation d'absorption à travers cette masse 32, en tenant compte de la variation due à l'épaisseur de l'enveloppe 11 déterminée grâce au récepteur 34C.The transmitter 33 scans a beam of waves inside the envelope 11. The signals generated by the receivers 34A and 34B make it possible to know the total absorption zone due to the presence of the balls 27 or at least to check that this area is greater than the minimum allowable area. The signal generated by the receiver 34C makes it possible to measure the wear of the envelope 11 by determining the variation in absorption as a function of the thickness of the envelope 11. The signal generated by the receiver 34D makes it possible to measure the quantity of carbon 32 by determining the variation in absorption through this mass 32, taking into account the variation due to the thickness of the envelope 11 determined by means of the receiver 34C.

La figure 3 représente schématiquement un exemple de circuit électronique de mesure des trois paramètres.FIG. 3 schematically represents an example of an electronic circuit for measuring the three parameters.

Le circuit électronique de détermination de la quantité de boulets comprend associé à chaque récepteur 34A, 34B un convertisseur 40A, 40B et un linéarisateur 41A, 41B, les signaux de chaque linéarisateur 41A, 41B étant associés par sommation 42A puis linéarisés 43A pour réaliser le calcul de la quantité de boulets 27 transmise sur un dispositif de lecture 44A.The electronic circuit for determining the quantity of balls comprises associated with each receiver 34A, 34B a converter 40A, 40B and a linearizer 41A, 41B, the signals of each linearizer 41A, 41B being associated by summation 42A then linearized 43A to perform the calculation of the quantity of balls 27 transmitted on a reading device 44A.

Le circuit électronique de détermination de l'usure de l'enveloppe comprend un convertisseur 40C associé à un dispositif de lecture du degré d'usure 44C.The electronic circuit for determining the wear of the envelope comprises a converter 40C associated with a device for reading the degree of wear 44C.

Le circuit électronique de détermination de la quantité de charbon comporte un convertisseur 40D dont le signal est corrigé par différenciation par le signal d'usure 41D de l'enveloppe 11 mesuré en sortie du convertisseur 40C.The electronic circuit for determining the quantity of coal comprises a converter 40D, the signal of which is corrected by differentiation by the wear signal 41D of the casing 11 measured at the output of the converter 40C.

Un second mode de réalisation est représenté sur la figure 4.A second embodiment is shown in FIG. 4.

Selon ce mode de réalisation, un récepteur d'ondes 34 disposé à l'extérieur de l'enveloppe 11 tourne à une vitesse ω autour de l'axe longitudinal de l'enveloppe 11 sur un secteur angulaire δ supérieur au secteur angulaire englobant α et β, le récepteur 34 étant associé à un circuit électronique de détermination de l'usure de l'enveloppe du broyeur, de la quantité de boulets et de la quantité de charbon.According to this embodiment, a wave receiver 34 disposed outside the envelope 11 rotates at a speed ω around the longitudinal axis of the envelope 11 over an angular sector δ greater than the angular sector encompassing α and β, the receiver 34 being associated with an electronic circuit for determining the wear of the shredder shell, the quantity of balls and the quantity of coal.

Ainsi, les éléments à surveiller et à observer sont "scannérisés" grâce à un système d'indexation de position en fonction des zones à observer et du type de mesure à réaliser.Thus, the elements to be monitored and observed are "scanned" using a position indexing system depending on the areas to be observed and the type of measurement to be performed.

Un exemple de signal obtenu grâce à ce dispositif de surveillance est représenté sur la figure 5.An example of a signal obtained using this monitoring device is shown in FIG. 5.

Ce signal représente l'amplitude A de l'onde reçue par le récepteur 34 en fonction de sa position x lorsqu'il parcourt le secteur angulaire δ à la vitesse ω.This signal represents the amplitude A of the wave received by the receiver 34 as a function of its position x when it traverses the angular sector δ at the speed ω.

La première zone D1 permet de suivre l'usure de l'enveloppe 11, par détermination de l'évolution de la courbe. Par exemple la courbe C2 représente un degré d'usure par rapport à la courbe C1 initiale.The first zone D1 makes it possible to follow the wear of the envelope 11, by determining the evolution of the curve. For example, the curve C2 represents a degree of wear with respect to the initial curve C1.

La seconde zone D2 permet de contrôler la quantité de charbon par surveillance de l'atténuation du signal en fonction de l'abscisse x1. La courbe C1' montre l'évolution du signal dans le cas d'un broyeur vide, le jeu de courbes C1 donnant l'allure de ce même signal en fonction du remplissage en charbon.The second zone D2 makes it possible to control the quantity of carbon by monitoring the attenuation of the signal as a function of the abscissa x1. Curve C1 ′ shows the evolution of the signal in the case of an empty mill, the set of curves C1 giving the appearance of this same signal as a function of filling with coal.

La troisième zone D3 permet de contrôler la quantité de boulets 27 par mesure de sa longueur en abscisses. Par exemple, la courbe C2 représente une diminution de cette quantité de boulets par rapport à la courbe initiale C1.The third zone D3 makes it possible to control the quantity of balls 27 by measuring its length on the abscissa. For example, curve C2 represents a reduction in this quantity of balls compared to the initial curve C1.

A chaque instant, un tel signal peut être lu et permet ainsi la surveillance en continu des trois paramètres que sont l'usure de l'enveloppe, la quantité de charbon et la quantité de boulets du broyeur.At any time, such a signal can be read and thus allows the continuous monitoring of the three parameters which are the wear of the envelope, the quantity of coal and the quantity of balls of the grinder.

Claims (10)

Dispositif de surveillance d'un broyeur à boulets à enveloppe cylindrique, contenant une masse de boulets se disposant lors de la rotation du broyeur à sa vitesse normale entre deux génératrices (lb, lb') espacées d'un angle minimal αmin et d'un angle maximal αmax et une masse de charbon se disposant lors de la rotation du broyeur à sa vitesse normale entre deux génératrices (lc, lc') espacées d'un angle β, caractérisé en ce qu'il comporte un émetteur d'ondes, choisies parmi les ondes électromagnétiques, disposé à l'intérieur du broyeur et au moins un récepteur d'ondes disposé à l'extérieur du broyeur, le récepteur étant associé à un circuit électronique de détermination d'au moins un paramètre du broyeur choisi parmi la quantité de boulets, la quantité de charbon et l'usure de l'enveloppe.Monitoring device for a ball mill with a cylindrical casing, containing a mass of balls arranged during rotation of the mill at its normal speed between two generators (l b , l b ') spaced at a minimum angle α min and of a maximum angle α max and a mass of coal which is disposed during the rotation of the mill at its normal speed between two generators (l c , l c ') spaced by an angle β, characterized in that it comprises a wave emitter, chosen from electromagnetic waves, placed inside the mill and at least one wave receiver arranged outside the mill, the receiver being associated with an electronic circuit for determining at least one parameter of the grinder chosen from the quantity of balls, the quantity of coal and the wear of the envelope. Dispositif selon la revendication 1, caractérisé en ce qu'il comporte au moins un récepteur d'ondes (34A) disposé face à la génératrice 1b et au moins un récepteur d'ondes (34B) disposé face à la génératrice 1b', correspondantes à l'angle αmin, les récepteurs (34A, 34B) étant associés à un circuit électronique de détermination de la quantité de boulets.Device according to claim 1, characterized in that it comprises at least one wave receiver (34A) arranged facing the generator 1 b and at least one wave receiver (34B) arranged opposite the generator 1 b ', corresponding to the angle α min , the receivers (34A, 34B) being associated with an electronic circuit for determining the quantity of balls. Dispositif selon la revendication 1, 2, caractérisé en ce qu'il comporte au moins un récepteur d'ondes (34C) disposé à l'extérieur des secteurs angulaires αmax et β, le récepteur (34C) étant associé à un circuit électronique de détermination de l'usure de l'enveloppe.Device according to claim 1, 2, characterized in that it comprises at least one wave receiver (34C) disposed outside the angular sectors α max and β, the receiver (34C) being associated with an electronic circuit of determination of the wear of the envelope. Dispositif selon la revendication 1, 2 ou 3, caractérisé en ce qu'il comporte au moins un récepteur d'ondes (34D) dans le secteur angulaire β non commun au secteur angulaire α, le récepteur (34D) étant associé à un circuit électronique de détermination de la quantité de charbon.Device according to claim 1, 2 or 3, characterized in that it comprises at least one wave receiver (34D) in the angular sector β not common to the angular sector α, the receiver (34D) being associated with an electronic circuit determining the quantity of coal. Dispositif selon la revendication 1, de surveillance d'un broyeur à boulets, contenant une masse de boulets (27) se disposant lors de la rotation du broyeur à sa vitesse normale entre deux génératrices (lb, lb') espacées d'un angle α et une masse de charbon (32) se disposant lors de la rotation du broyeur à sa vitesse normale entre deux génératrices (lc, lc') espacées d'un angle β, caractérisé en ce qu'il comporte au moins un récepteur d'ondes (34) disposé rotatif autour de l'axe longitudinal de l'enveloppe (11) sur un secteur angulaire δ supérieur au secteur angulaire englobant α et β, le récepteur (34) étant associé à un circuit électronique de détermination de l'usure de l'enveloppe du broyeur, de la quantité de boulets et de la quantité de charbon.Device according to claim 1, for monitoring a ball mill, containing a mass of balls (27) which are arranged during the rotation of the mill at its normal speed between two generators (l b , l b ') spaced by an angle α and a mass of coal (32) which are arranged during the rotation of the mill its normal speed between two generators (l c , l c ') spaced by an angle β, characterized in that it comprises at least one wave receiver (34) arranged to rotate around the longitudinal axis of the envelope (11) on an angular sector δ greater than the angular sector encompassing α and β, the receiver (34) being associated with an electronic circuit for determining the wear of the mill casing, the quantity of balls and the quantity of coal. Dispositif selon l'une des revendications précédentes, caractérisé en ce que l'émetteur (33) est disposé sur l'axe longitudinal de l'enveloppe (11).Device according to one of the preceding claims, characterized in that the transmitter (33) is arranged on the longitudinal axis of the envelope (11). Dispositif selon l'une des revendications précédentes, caractérisé en ce que l'émetteur (33) est un émetteur de photons gamma.Device according to one of the preceding claims, characterized in that the emitter (33) is a gamma photon emitter. Dispositif selon la revendication 2 ou 5, caractérisé en ce que le circuit électronique de détermination de la quantité de boulets comprend associé à chaque récepteur (34A, 34B) un convertisseur (40A, 40B) et un linéarisateur (41A, 41B), les signaux de chaque linéarisateur étant associés pour réaliser le calcul de la quantité de boulets.Device according to claim 2 or 5, characterized in that the electronic circuit for determining the quantity of balls comprises associated with each receiver (34A, 34B) a converter (40A, 40B) and a linearizer (41A, 41B), the signals of each linearizer being associated to calculate the quantity of balls. Dispositif selon la revendication 3 ou 5, caractérisé en ce que le circuit électronique de détermination de l'usure de l'enveloppe comprend un convertisseur (40C) associé à un dispositif de lecture du degré d'usure (44C).Device according to claim 3 or 5, characterized in that the electronic circuit for determining the wear of the envelope comprises a converter (40C) associated with a device for reading the degree of wear (44C). Dispositif selon la revendication 4 ou 5, caractérisé en ce que le circuit électronique de détermination de la quantité de charbon comporte un convertisseur (40D) dont le signal est corrigé par le signal 5 d'usure de l'enveloppe mesuré selon la revendication 9.Device according to claim 4 or 5, characterized in that the electronic circuit for determining the quantity of coal comprises a converter (40D) whose signal is corrected by the signal 5 of wear of the envelope measured according to claim 9.
EP96401133A 1995-06-01 1996-05-24 Monitoring device for ball mills Expired - Lifetime EP0745427B1 (en)

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FR9506523A FR2734739B1 (en) 1995-06-01 1995-06-01 DEVICE FOR MONITORING A BALL MILL
FR9506523 1995-06-01

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ES2147905T3 (en) 2000-10-01
ATE192670T1 (en) 2000-05-15
EP0745427B1 (en) 2000-05-10
US5698797A (en) 1997-12-16
DK0745427T3 (en) 2000-10-02
DE69608163D1 (en) 2000-06-15
FR2734739A1 (en) 1996-12-06
FR2734739B1 (en) 1997-07-11
DE69608163T2 (en) 2000-12-21
CA2177932A1 (en) 1996-12-02
CN1142988A (en) 1997-02-19

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