GB774980A - Improvements in pneumatic conveying systems - Google Patents

Abstract

774,980. Pneumatic conveyers. FULLER CO. Feb. 22, 1954 [March 11, 1953], No. 5123/54. Class 78 (1). In a conveyer for pulverulent material, e.g. flour, material passes from a supply hopper to a first pneumatic conveyer which transfers it to separator in which it is divided into coarse and fine fractions. The fine fraction is carried by a second pneumatic conveyer to a second separator. This separator is connected by a third conveyer to a third separator. The material passes from the third separator to a weighing means. When a predetermined weight of material has been received by the weighing means, a distribution valve provided on the third conveyer is actuated and the passage of the material through the third separator is stopped. Flour contained in a hopper 1, Fig. 1, is fed into a conveyer line 43 by a rotary discharger 31. The bottom of the hopper comprises inclined gas permeable members 8, 9, Fig. 2, through which gas passes into the flour from plenum chambers 10, 11. The permeable members slope towards a discharge opening 16 leading to the discharger 31. The flow of material is regulated by a pivoted plate 19, which is shown in Fig. 2 in its extreme positions 19, 19<SP>1</SP> and in an intermediate position 19<SP>11</SP>. In its extreme positions 19, 19<SP>1</SP> the flow of material from the members 8, 9 respectively, is stopped. The plate 19 is fast on a shaft 20 which is connected by worm gearing 21, 23, Fig. 4, to a shaft 24. This shaft is rotated by a handwheel 27 and is locked in any position by screwing up a threaded member 28. An indicator 29 fast on the shaft 20 in conjunction with a scale 30 shows the position of the plate 19. If two materials having different conveying characteristics are dumped into opposite sides of the hopper, they can be blended in anv proportion by adjusting the position of the plate 19. Inclined plates 48, 49 are disposed in the hopper above the plate 19 to disperse the material blown upwards by the release of compressed air from the pockets of the discharger as they enter the opening 16. A guard grid 55 in the hopper prevents a flour bag from falling into the discharger if dropped accidentally. The flour is blown through the pipe 43 into a cyclone separator 59 from which it passes through a rotary air-lock 62 into a sifter 60. In this sifter the flour is separated into coarse and fine fractions which pass respectively, into collectors 63, 65. The coarse fraction is removed from the system, but the fine fraction passes from the collector 65 through a rotary discharger 67 into a pipe 72 along which it is blown to a cyclone separator 73 by the air discharged from the separator 59 into a pipe 71. The separated material passes into a receiver 74 from which it is delivered through a rotary discharger 75 into a pipe 79. The flour is blown through the pipe 79 to a distribution valve 80 from which it passes through a pipe 81 to a cyclone separator 82 disposed above and discharging into the scale hopper 83 of the four-point suspension type provided with a balance beam 84. Air from the separator 73 passes through a pipe 85 to the valve 80. A fan-type centrifugal separator 112, or a dynamic precipitator, communicates with the receiver 74 through a pipe 121. The separator 112 has a header 113 which is connected by a pipe 114 having a flow control valve 115 to the air discharge outlet of the separator 82. The header 113 is connected also by a pipe 116. having a valve 117 to the air discharge outlet of the separator 73. A third pipe 68 having a valve 118 connects the header directly to the collector 65 and via the pipe 70 and connection 69 to the sifter 60. The air discharge outlet of the separator 112 is connected by a pipe 119 to a filter box 120 and the material outlet is connected by a pipe 121 to the receiver 74. Bleeder ports 123, 124 and 125 provided with filter pads connect into the pipes 114, 116 and 68 to admit atmospheric air. The pipe 68 receives the air discharged from the collector 65. Specifications 774,981, 774,982 and 774,983, [Group XVIII], are referred to.