GB1063351A - Methods of and means for automatically controlling the rate of flow of granular material - Google Patents

Abstract

1,063,351. Automatic flow control, fluid pressure servomotor systems. COAL INDUSTRY (PATENTS) Ltd. Dec. 6, 1963 [Sept. 25, 1962], No.36402/62. Headings G3P and G3R. A first stream of particulate material flowing at a variable rate is mixed with a second stream flowing at a substantially constant but adjustable rate, the difference between the rate of flow of the first stream and a reference rate being used to control the rate of flow of the second stream with modification in dependence on the error between the sum of the two rates of flow and the reference rate. In Fig. 1 a steady flow of coal is supplied by a vibratory feeder 4 from a hopper 3 to a conveyer 1 the output of which is mixed with the output of a conveyer 2 the supply to which fluctuates. The rate of supply of coal by conveyer 2 is measured by a weighing section 14 the variable signal from which is compared in a device 15 with a signal X representing a desired total flow so that the difference is effective to adjust the feed of the vibratory feeder. The total flow is computed by adding in a device 16 signals from weighing sections 12, 13 appropriately positioned on the two conveyers and the output of device 16 is compared in a damped control unit 17 with the signal X representing the desired total flow so that any error controls a device 18 to modify the signal from device 15 controlling the vibratory feeder 4 and ensure the desired total flow. In one modification a single weighing section replaces the two sections 13, 14 and in another a weighing section of a conveyer handling the total flow after mixing replaces the two sections 12, 13. Controlling the speed of conveyer 1 is referred to. Fluid-pressure or electrical signals may be employed.