BELTS & CONVEYORS
Hannah’s Sweets improve sack dumping and plant hygiene with a new handling system
Scottish confectionery maker, Hannah’s Sweets produces a variety of confectionery – Jazzies and Snowies, which are chocolate discs covered in coloured candy pieces. It processes large quantities of sugar, milk powder, whey
powder, wheat fl our and other dry ingredients received in 25kg bags. Often around 300 of these bags need to be emptied in a day at a rate of 1,675 kg/hour. To reduce manual bag handling and dust and to
prevent pallets from entering the hygienic mixing room, the company installed a Flexicon bag dump station and pneumatic conveying system which was integrated with an existing roller conveyor and vacuum sack lifter. The delivery system needed to be able to handle material with bulk densities from 208 kg/m3 for milk powder to 705 kg/ m3 for granulated sugar. Using the vacuum lifter, an operator moves the sacks
from pallets onto the roller conveyor, which transports them through a wall into the mixing room where the bag dump station is located. Equipped with a high velocity vacuum fan, the unit draws airborne dust generated by the manual dumping process away from the operator onto two cartridge fi lters. Dust accumulation on outer fi lter surfaces is dislodged on a timed cycle by alternating blasts of air
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from nozzles located within each fi lter, maintaining dust collection effi ciency. Material is then fed through a pickup adapter mounted
below the base of the hopper, into the pneumatic conveying system. Powered by a 7.5 kW blower, this transports ingredients through a 12m long, 75mm diameter line with three pneumatically-actuated diverter. Once separated from the airstream, material is metered through the fi lter receiver’s rotary valve into a surge hopper that discharges into a mixing tank, where dry ingredients are blended with vegetable fats. The system is controlled by a programmable logic
controller (PLC) that opens and closes each diverter valve, starts and stops each rotary valve as signals are received from each hopper’s high-level sensors, and stops the conveying system’s blower when a signal is received from the bag dump station’s low-level sensor. The enclosed system precludes contamination of the
product and plant environment, while the pneumatic blower evacuates the conveying line. This eliminates the need to fl ush the system during material changeovers, and ensures all batch ingredients reach the mixing tanks, eliminating waste.
Kennedy’s Confection August/September 2023 55
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