US2687817A - Method and apparatus for controlling the flow of solid materials - Google Patents

Description

Patented Aug. 31, 1954 METHOD AND APPARA LING THE FLOW O TUS FOR CONTROL- F SOLID MATERIALS Kenneth A. Browne, Lakewood, Ohio, assignor to The Chesapeake and Ohio Railway Company,

a corporation of Virginia Application February 1, 1952, Serial No. 269,558

'7 Claims.

This invention relates to a method and apparatus for controlling the flow of solid materials and more particularly to the control of the level of solid materials flowing downwardly through a substantially vertical conduit. The invention is described herein in its application to an apparatus for loading coal into ships but it is to be understood that the invention may be adapted to other purposes and uses.

Coal loaders for ships have been constructed in which coal is conveyed from a car dumper or other source of supply to a dockside tower which is provided with a boom that can be extended over a vessel to be loaded. The boom carries a substantially horizontal conveyor belt which delivers coal to a downwardly extending conduit or chute supported near the outer end of the boom, the coal falling off, the end of the conveyor into the top of the conduit. The conduit is adapted to be disposed in the hold of the vessel and its lower end is curved toward a horizontal direction and is provided with a gate to control the rate of discharge of coal. These loaders operate satisfactorily so long as the level of coal in the conduit is maintained near the upper end of the conduit so that the coal falling freely from the end of the horizontal conveyor strikes the coal in the conduit before it has attained a high velocity. However, if the gate at the bottom of the conduit is controlled improperly so that the coal e is discharged from the conduit at such a rate that the. level of the coal in the conduit is far below the discharge end .of the horizontal conveyor or at such a rate that there is no body of coal moving through the conduit, but only freely falling coal, then the lumps of coal falling freely either to the bottom of the chute or to the low level of coal in the chute are broken by the force of their fall, creating large quantities of dust and degrading the coal as well as damaging the surfaces which they strike at the end of the fall.

Accordingly, a general object vof the present invention is to provide a method and apparatus for automatically controlling the flow of solid material in a downwardly extending chute or conduit, whereby the level of the material in the upper end of the conduit can be maintained substantially constant. A further object of the invention is the provision of a simple and reliable apparatus for so controlling the flow of solid materials. Another object is the provision of such an apparatus which can be installed on existing structures at reasonable cost. A more specific object is the provision of a method and apparatus for controlling the level of coal in the vertical chute or conduit of a coal loader embodying a horizontal conveyor discharging coal into the conduit and a gate for controlling the flow of coal from the bottom of the conduit.

Further objects and advantages of the invention will become apparent from the following description of a preferred form thereof, reference being made to the accompanying drawings in which Figure 1 isa somewhat diagrammatic illustration of a coal loader embodying my invention. Figure 2 is a View on an enlarged scale showing the conduit, partially cut-away and the control mechanism of Figure 1 and Figure 3 is a diagram of, the preferred electrical circuits for the ap paratus.

As shown in Figure 1, my invention is particularly adapted for use in conjunction with a coal loader constructed on a dock D and adapted to deliver coal to a ship tied up at the dock. The coal loader comprises a tower in to which coal is delivered by any suitable system of conveyors (not shown) from a car dumper or other supply to agenerally horizontal belt conveyor II that is supported by a boom I2. Boom I2 is pivotally mounted on the tower as at. l3, and cables it are provided for hoisting or swinging the boom. At its outer end, belt conveyor II is adapted to discharge material into the tubular chute or conduit l5 which is supported from the boom and extends downwardly to deliver coal to the hold of a ship. Cables 5 and I 1 are provided for swinging the conduit to various positions. The lower part of the conduit, is curved as shown at it so that coal is delivered from the conduit in a somewhat horizontal direction and the lower por.- tion 2.0a of the lower section to of the conduit may berotated with respect to the upper portion 20b of the lower section is by means actuated by motor 22 so that the direction of discharge of the coal can be controlled. The lower section 20 also telescopes with respect to the upper section 2! thus making it possible to control the length of the conduit. At the bottom of the conduit, there is a gate 23' which is pivotally supported as at 24 and which is, adapted to be moved from the fully open position shown in full lines in Figure 2 to the closed position shown in broken lines by means of motor 25 which drives pinion 26 through slidable reduction gearing, pinion 2t engaging gear segment 21 which is rigidly secured to the supports 28 for the gate 23. Appropriate limit switches are provided for stopping motor 25 at the extreme positions of gate 23. vAll of these elements just described are well known er to the left in the embodiment shown, again tending to restore the bridge to balance and preventing overcorrection. The repeat-back arrangement also tends to keep the level at the upper portion of its range when the gate is nearly open and at the lower portion of its range when the gate is nearly closed; this mode of operation lessens the likelihood of the conduit overflowing or becoming completely empty because of wide fluctuations in the rate of delivery of coal thereto.

Switch 46 provides a manually-operated override control for use in the event of improper functioning of the automatic control. When the switch is thrown to contacts 46a the operation is automatic as described above. However, when the switch is thrown to contacts 46b, the relay 44 is connected across the supply lines 35 through conductors 56 and resistor 51, energizing the relay in such manner that contact 49 is closed, thereby energizing contactor 5| and operating motor 25 to open gate 23 completely, if desired, and thus preventing the possibility of overflow of, coal at the top of the conduit l5.

In service, the apparatus operates to maintain the level of coal in the conduit within a range of a few feet regardless of variations in the rate of delivery of coal to the conduit by the conveyor I I and regardless of ordinary changes in the characteristics of the coal without requiring excessive operation of the gate. Maintenance of the level within a few feet is what is intended by term substantially constant in the specification and claims hereof. By the use of the apparatus, the level of the coal can be maintained in the upper portion of the conduit I5, thereby preventing degradation of the coal and the creation of excessive quantities of dust and, at the same time, the control acts quickly enough to prevent overflowing of the conduit I5 by reason of an increase in therate of delivery of coal to the conduit by the conveyor I I.

Those skilled in the art will appreciate that various changes and modifications can be made in my invention without departing from the spirit and scope thereof and that the invention, while particularly adapted to the control of the flow of coal in coal loaders, can .be adapted to other purposes and uses.

I claim:

1. In an apparatus for controlling the level of solid material flowing downwardly through a substantially vertical conduit having associated with it a conveyor for delivering material to said conduit positioned so that material falls from said conveyor into said conduit and a gate for controlling the discharge of material from said conduit, the improvement which comprises an elongated element extending from a zone above the desired level of the flowing material downwardly into the flowing material with its longitudinal axis substantially parallel to direction of travel of material in the conduit, means for rotating said element about its longitudinal axis and means responsive to the torque required to rotate said element for controlling the position of said gate whereby an increase in the torque results in movement of said gate toward open position and a decrease in said torque results in movement of said gate toward closed position.

2. In an apparatus for controlling the level of solid material flowing downwardly through a conduit, said conduit having associated with it a conveyor for delivering material to said conduit positioned so that material falls from said conveyor into the upper part of said conduit, and a gate for controlling the discharge of material from the bottom of said conduit, the improvement which comprises an elongated flexible element disposed in the path of the material falling from said conveyor into said conduit and extending from a zone above the desired level of the flowing material downwardly into the flowing material to a zone below the desired level with its longitudinal axis substantially parallel to the conduit, an electric motor for rotating said element about its longitudinal axis, and means responsive to the armature voltage of said motor for controlling the position of said gate whereby a decrease in the armature voltage results in movement of said sate toward open position and an increase in said voltage results in movement of said gate toward closed position.

3. The apparatus defined in claim 2 wherein the armature of said motor constitutes one leg of a bridge circuit which includes a potentiometer controlled by the position of said gate.

4. The apparatus defined in claim 2 wherein said bridge circuit includes a manually adjustable resistor for adjusting the desired level of material in the conduit.

5. In an apparatus for conveying solid material embodying a downwardly extending conduit, a conveyor for delivering material to the upper portion of said conduit, a gate at the lower end of said conduit for controlling the discharge of material from said conduit, and an electric motor for adjusting the position of said gate, the improvement which comprises an elongated flexible element extending from a zone above the desired level of the flowing material downwardly into the flowing material to a zone below the desired level with its longitudinal axis substantially parallel to the conduit, an electric motor for rotating said element aboutits longitudinal axis, and means responsive to the torque required to rotate said element for controlling the operation of said gate adjusting motor whereby an increase in the torque results in movement of said gate toward open position and a decrease in said torque results in movement of said gate toward closed position, said means comprising a bridge circuit including the armature of said element-rotating motor and a polarized relay, responsive to unbalancing of said bridge resulting from changes in voltage across said armature, for operating said gate adjusting motor.

6. The apparatus defined by claim 5 wherein the bridge circuit includes a potentiometer which is mechanically connected to said gate and adjusted in response to movements thereof in a direction tending to restore said bridge to a balanced condition.

7. The apparatus defined by claim 5 wherein the bridge circuit includes an adjustable resistor.

References Cited in the file of this patent UNITED STATES PATENTS Sept. 14, 1954 J. A. ALBANO ZERO DRAG VERTICAL "I" ANTENNA Filed June 20. 1950 R.0 W E; 1 m4 4. b w Z w F a W 0 4 1 J m N N Y m p m 2 a H B W W W F r R J Ma m w w a w m I 7 a :4 w i k n C L) M i W w a M F r 1 W Y 5 5 4, e -1 m 7 N n/ 9 s M z y I y a m I w

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