27/01/2007 - Multisorb Technologies Inc. increased productivity at its new European facility for producing silica gel granule adsorption packets with an automated multi-line bulk solids handling system that simultaneously feeds four form/fill/seal machines. The system consists of a bulk bag discharger, four flexible screw conveyors, and four feed hoppers gravity discharging material simultaneously.
Multisorb chose this layout over a simpler, lower capacity single line of flexible screw conveyors supplying the form/fill/seal machines one at a time.
The company selected mechanical over pneumatic conveying for gentle product handling to maintain particle size of 1-4 mm. A flexible screw conveyors self-centering stainless steel spiral rotates within a UHMWPe (ultra-high molecular weight polyethylene) tube, providing clearance between the screw and tube wall for the silica gel particles to flow undamaged.The bulk handling system, which is expandable for future market growth, was designed, built and commissioned by Flexicon (Europe) Ltd.
Forklift loading of discharger frame
Granules arrive in 1-ton bulk bags, which are lined to prevent entry of moisture or oxygen that would affect the hygroscopic material. The entire conveying system is airtight, conferring the same benefit.
A forklift operator attaches the bulk bag to four Z-CLIPÔ bag strap holders on a bag-lifting frame, then maneuvers the forklift to secure the frame on a 3.6 m high discharger frame above the 225 liter capacity receiving hopper.
Bulk Bags discharge dust-free
The bulk bag/hopper interface consists of a manual Spout-Lockâ clamp ring positioned above a pneumatically actuated Tele-Tubeâ telescoping tube, which facilitates dust-tight connections between bag spout and hopper, and automatically elongates the bag as it empties to promote flow and evacuation.
The telescoping tube pneumatically raises the clamp ring assembly allowing connection to the bulk bag spout, sealing the clean side of the bag spout to the clean side of the telescoping tube. It then lowers until the bag spout is pulled taut. Once the spout is untied, the telescoping assembly exerts continual downward tension on the spout, elongating the bag as it empties. The dust-tight seal between bag spout and clamp ring allows full-open discharge from the bag with no dusting.
From the hopper, a 6m long, 80 mm diameter flexible screw conveyor, at a 45 degree angle, draws the material to 4.4 m height into the first of four 130 ltr capacity feed hoppers. Three 4.5m long, 80 mm diameter flexible screw conveyors connect the feed hoppers horizontally in series. Each hopper gravity feeds material to an auger and form/fill/seal machine.
PLC control allows simultaneous filling of any combination of the four feed hoppers, dictating how much material fills a hopper by opening or closing a slide valve between the discharge of the flexible screw conveyor and hopper inlet. High and low level warning indicators on the hoppers and above each slide valve tell the control to stop or resume flow through the conveyors.
Expandable for future production
The system permits installing a parallel line of flexible screw conveyors to meet expanded production. The inlet on each of the four feed hoppers is offset so an additional flexible screw conveyor can discharge into a second inlet opposite the first.
The bulk solids handling system has been fulfilling production expectations and will allow higher productivity as the plant expands into different products for new markets.
