Abstract: The method of monitoring the level of filling of a ball mill which is fed with material to be pulverized and is provided with a drum mounted to rotate on two bearings which are relatively far apart, consists in measuring the weight of the drum using strain gauge weight sensors (11-16) under the bearings supporting the drum of the ball mill and comparing the measured weight to a predefined set point value to regulate the feeding of material to be pulverized to the ball mill. In addition, before the comparison step, the measured weight is corrected by a first weight value (Fv) representative of the vertical component of the force created by the torque driving rotation of the drum.

Abstract: The ball mill is of the type including: a rotary drum (11, 12, 13) having a horizontal axis (XX′) and each end of which is supported by a journal (14, 15) which terminates it and through which passes an axial tube (41) around which it delimits an annular duct (35), a vertical pipe (6) discharging in the vicinity of the journal at the level of a guide member (31) for directing material to be pulverized from the pipe towards the drum, and an outlet duct (36) communicating with the annular duct for ejecting from the drum the mixture consisting of the gas and the pulverized material. Each journal contains a rigid helicoidal Archimedes screw structure (32) fixed to it and turning with it about the tube, when the drum rotates, which tube is a rigid immobile gas injector tube.

Abstract: A device for continuously measuring the quantity of coal inside a ball grinder including an ultrasound wave or electromagnetic wave emitter and a wave receiver. The emitter and the receiver are disposed so that the wave passes through at least part of the interior of the grinder. The receiver is associated with an electronic circuit for deducing the quantity of coal by comparing the signal received with data obtained from previous calibration measurements.

Abstract: The present invention relates to a ball mill having a substantially horizontal axis of rotation and including a drum supported by two trunions having the same axis of rotation and situated at respective ends of the drum, raw coal being conveyed by substantially vertical pipework to the vicinity of a cylinder having the same axis of rotation and disposed within each trunion so as to open out into the drum, with the space lying between each trunion and its cylinder being connected to a pulverized coal outlet duct via a separator. A raw coal guide member is disposed beneath the pipework, conveying coal under gravity into the inside of the cylinder which includes a rigid Archimedes' screw on its inside surface, a main air feed being provided on said pipework upstream from the separator, all of said air being channeled towards the inside of the cylinder.

Abstract: The present invention concerns a device for monitoring a ball grinder having a cylindrical casing containing a mass of balls which, when the grinder is rotating at its nominal speed, takes up a position between two generatrices (1.sub.b, 1.sub.b') spaced by an angle between a minimal angle .alpha..sub.min and a maximal angle .alpha..sub.max and a mass of coal which, when the grinder is rotating at its nominal speed, takes up a position between two generatrices (1.sub.c, 1.sub.c') 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.

Abstract: An adjustable temperature gas feed is available that feeds firstly the grinder and secondly pre-drying means. At the outlet from the grinder, the gas that has passed through the grinder is combined with the gas that has passed through the pre-drying means to convey the ground material. The total gas flow rate Q.sub.A at the oulet lies between a minimum flow rate and a maximum flow rate, and the flow rate Q.sub.1 of the gas passing through the grinder (1) is proportional to the quantity Q.sub.c of material placed in the grinder. According to the invention, a temperature T to be reached by the gas outlet temperature is set (optionally as a function of the moisture content of the material), and the gas feed is adjusted in such a manner that the feed gas is as hot as possible with the quantity of gas passing through the pre-drying means being limited to as little as possible. The method adapts to the material having different moisture contents and improves efficiency while leading to combustion with low NO.sub.x.

Abstract: A method of regulating the operation of a material-crusher (1) in which the noise emitted by the crusher, the power absorbed thereby and the supply and removal flow rates of the material therein are detected. The flow rate (2) of the material fed into the crusher is regulated so as to maintain the quantity of material therein at a high and constant value close to that at which the efficiency of the crusher is at its best.