GB568146A - Improvements in alarm devices for use in systems for feeding aggregate materials - Google Patents

Abstract

568,146. Alarm devices for materialfeeding systems. STOCK, A. J. Dec. 30, 1942, No. 18548. Convention date, Dec. 12, 1941. [Class 143] [Also in Group XII] Apparatus for detecting stoppages in the flow of bulk material through a feeder system, for example, for feeding coal or coke to the boilers ] of a power plant, comprises a batch delivery device (for example, a weighing-apparatus), a feeding device (for example, a pulverizer-feeder or stoker), means driven by a rotating part of the feeding device to actuate an alarm signal if an abnormal predetermined angular displacement of the rotating part occurs, and means operated by the batch delivery device (upon the delivery of a batch) to reset, if normal operation occurs, the means driven by the rotating part of the feeding device and thus prevent the actuation of the alarm. In Fig. 2 is shown an alarm unit for use with the usual elements of a coal supply system, viz. an automatic weighing-apparatus 18, Fig. 1, fed from a bunker 11 by an intermittently-running belt conveyer 16, and a pulverizer-feeder or stoker 14 for feeding a furnace. Preferably, two of the alarm units 21, 22 are used, one driven with the belt conveyer 16 and the other by the stoker 14. Each unit has a driven shaft 27 and is provided with a resetting device operated by the weighing mechanism. If a stoppage occurs above the weigh hopper, the belt conveyer 16 operates for an abnormally long time before the weighing mechanism operates. The shaft 27 (driven with the conveyer) drives a mutilated wormwheel 29 sufficiently to cause a pin 38 thereon to engage an arm 37 and rock a mercury switch 36, thereby giving an alarm. In normal operation, however, the pin fails to reach the mercury switch before the weighing machine operates, and stops the driving motor 17, Fig. 1, of the conveyer, and with it the shaft 27. A solenoid 43 in the motor circuit is de-energized and allows a dashpot plunger 50 to fall. When the motor 17 is restarted for a further weighing operation, the solenoid, acting through the dashpot lifts the worm-wheel 29 out of gear with its driving worm 28, and a spring 44 revolves the worm-wheel until the pin 38 abuts against an adjustable slider 45 and the wheel is permitted by the dashpot' to re-engage its worm in readiness for a new cycle. The second alarm unit operates in a similar manner if the coal piles up under the weighing-apparatus, preventing its operation and thus causing the pulverizer-feeder or stoker to operate for an unusually long period between the operations of the weighing-apparatus. Shortage of coal supplied to the weighing-machine causes both alarms to be given. If it is desired to render the stoker alarm inactive upon actuation of the scale alarm, a further mercury switch, tilting with the scale switch 36, is arranged to break the circuit of the stoker alarm. Specification 568,147 is referred to.