Sieves & Screens
System moves DE dust-free
The DE bulk handling equipment, produced by Flexicon Corp., Bethlehem, PA, consists of two identical systems, allowing cleaning and maintenance of either system with no interruption in the movement of DE from the bulk bags to the dilution tank where it is utilised.
Each system consists of a bulk bag unloader with loss-in- weight batching controls and an integral flexible screw conveyor. The bulk bag unloaders measure 1.5 m square. Four vertical extension posts are adjustable in overall height from 4.3 m to 5.8 m to accommodate bulk bags from 600 mm to 2000 mm tall. The unloaders are equipped with Flow-Flexer bag activators that raise and lower opposite bottom edges of the bulk bag at timed intervals, improving material flow into the bag’s discharge spout. As the bag lightens, the stroke of the pneumatic bag activators lengthens, producing a steep “V” bag shape to promote evacuation of material.
Also promoting flow are a Spout-Lock clamp ring that creates a high-integrity, sealed connection with the bag spout, and a Tele-Tube telescoping tube that applies continual downward tension on the bag as it empties and elongates. Above the clamp ring is a Power-Cincher flow-control valve whose curved, articulated rods cinch the bag spout concentrically, allowing the operator to control the flow of material through the spout after releasing the bag spout drawstring, as well as to close and re-tie the spout of partially empty bags with no leakage or dusting.
m3
DE flows from the bulk bag through the bag spout into a 1.8 capacity surge bin able to hold the entire contents of one
ABOVE: One of two 1.8 cu m capacity hoppers holds the contents of a 408 kg bulk bag allowing diatomaceous earth to transfer, unattended, through the flexible screw conveyor to the tank.
bulk bag, effectively doubling the unattended run time of dischargers having small surge hoppers.
The sealed system is vented through a port in the hopper lid to a dust collector that vacuums displaced air and dust, and collapses empty bags dust-free prior to tie-off and removal, eliminating manual flattening and associated dusting. Reverse- jet filter cleaning allows the vacuum system to operate at high efficiency, while extending filter life.
The hopper discharges into an intake adapter that charges a Model 1250 flexible screw conveyor with DE. A cantilevered arm on the bulk bag unloading frame supports the discharge end of the 4.6 m long conveyor tube which is inclined at 30-degrees. At the discharge end, a gear-drive assembly with a 0.75 kw motor rotates the flexible screw, propelling DE through the 67 mm OD plastic tube.
ABOVE: A Bag-Vac dust collector, mounted on the bulk bag unloader frame, vacuums displaced air and dust, and collapses empty bags dust-free prior to tie-off and removal. The bulk bag is supported in a lifting frame
www.solidsandbulk.co.uk
Loss-in weight batching provides accurate dosing of DE When the DE dilution tank has discharged its contents, a level indicator signals the PLC that controls the weigh batching system to initiate a weigh batching cycle by running one of the flexible screw conveyors. Load cells supporting the bulk bag unloader frame with integral conveyor, transmit weight loss information to the PLC which reduces the conveyor speed immediately before stopping the conveyor, achieving an accurate batch weight. Based on the amount of weight lost, the PLC also indicates when the operator needs to load a full bag of DE into the unloader, Weight loss information is shown on an LCD, part of a control centre that includes a keypad, custom-engineered software, and an A/C inverter with adjustable speed control and a reversing feature for the conveyor drive. When operating at full capacity, the plant provides the Tampa Bay region with approximately 10 percent of its drinking water.
For more information contact Flexicon on tel: +44 (0) 1227 374710 or visit:
www.flexicon.co.uk
May 2010 • Solids & Bulk Handling 25
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