GB660951A - Pneumatic feeding and conveying systems - Google Patents

Abstract

660,951. Pneumatic conveyers. BOZICH, M. J. July 7, 1949. No. 17957/49. Class 78 (i). A conveying system (Fig. 1) comprises a feed hopper 1 discharging into a pneumatic conveying conduit 8, means 11 for supplying a stream of air into said conduit, to move the material thereby and a device 46 operative when the pressure in said conduit rises above or falls below a pre-determinal value to control the movement of the material into the conduit. Fig. 1. Material falls from hopper 1 past pivoted valve 21 into hopper 2 until the level of material in the latter actuates switch 38 which then switches on motor 12 to drive fan 11. Fan 11 drives air along conduit 9 to discharge the material out by conduit 8, the pressure in conduit 9 being sufficiently high to actuate switch 46 which maintains the motor circuit when switch 38 automatically closes. The air also passes by conduit 13 and blows against valve 21 to swing it anticlockwise to keep the latter closed to prevent further inlet of material. When the material in hopper 2 is completely or nearly completely discharged the air pressure in conduit 9 falls and actuates switch 46 to cut out the motor. Switch 46, alternatively, may vent the fan to atmosphere or may cut out the motor when the hopper 2 is incompletely discharged. Also the loss of pressure allows valve 21 to fall and to open and then the cycle of operations begins again. Fig. 4. When the material surges (due to arching) it tends to cause excessive material discharge and therefore wear on the motor, and to prevent this there is included in conduit 13 a valve 60 which is actuated by the air pressure to operate solenoid 70 to close the conduit by means of valve plate 69. Thus the material is discharged chiefly by pressure from conduit 9, and therefore more slowly, without straining the motor until the pressure inside hopper 2 falls to normal value and allows valve plate 69 to return to its normal position to free conduit 13. Fig. 3. Valve 21 is pivoted at 24 and is counterweighted at 27 so that normally it is biassed against gasket 19 of valve seat 18 but yields when the air stream through pipe 13 is cut off and then allows material to fall.