Norway’s leading supplier of candy, Nidar AS, manufactures 150 products under 35 brands on 10 production lines. Built in 1950, the company’s plant has been periodically updated with newer bulk handling equipment to improve productivity and working conditions. The five-level plant has been extended six times to accommodate growth in production, but due to the building’s design, the space presents challenges for the company. “As with most old buildings, the original layout has not always been optimal for modern production,” explains Tor Ove Kvingedal, one of Nidar’s three maintenance engineers.
Tight places make gravity feeding of materials impossible in some sections of the plant. In these areas, bulk materials are transferred using bulk bag dischargers, flexible screw conveyors, rigid augers and pneumatic conveyors. These pieces of equipment not only reduce manual labor and contain dust, they also fit in the allotted space.
Ingredients such as milk powder, sugar and starch arrive in 1.2-ton bulk bags. A number of bulk bag discharge stations are dedicated to unloading them, including six supplied by Flexicon Ltd. The newest bulk bag discharger is a twin half-frame unit that handles two types of starch in a small space on the plant’s fourth floor. Previously, operators carried 55-lb. bags of starch from the third to the fourth floor where it was dumped into two large vessels, each holding 440 to 660 lb. Thirty-two bags were handled manually each eight-hour day.
“The operators were climbing stairs numerous times every day to keep the vessels filled,” says Kvingedal. He adds unloading the bags of starch by hand was hard work and dusty too. “Starch dust is not harmful, but it can be very sticky.”
The starch powder flowed by gravity from two large vessels through a pair of knife gate valves and 6-in. diameter steel chutes. The large vessels could not be replaced with two separate bulk bag dischargers because the distance between the discharger outlets would have exceeded the distance between the existing chutes. Also, the ceiling is less than 15-ft. high, which does not provide enough headroom above the units to use a forklift for loading and removing bulk bags.
To surmount both problems, a Flexicon Bulk-Out BFH-C-X 4-ft. high, twin half-frame bulk bag discharger was installed. The unit discharges through two outlets spaced closely enough to avoid relocating the knife gate valves and chutes, while the low profile design allows suspension of bulk bags from a hoist, saving 4 in. of headroom. The discharger holds two bulk bags side-by-side that provide enough starch to keep the line running for two or more days.
Removing the original tanks and installing the twin half-frame discharger above the chutes was straightforward, says Kvingedal. Only a compressed air supply is required to power the unit.
“We installed the discharger in two days,” he remembers. “A local company provided the hoist. It was critical to have the equipment installed quickly, because starch is a key ingredient on this production line.”
Once a bag is hoisted into position, an operator pulls the bag spout over a clamp ring to create a secure, dust-tight connection between the clean side of the bag spout and the clean side of a telescoping tube. Nidar considered installing extraction fans, but decided they were unnecessary since the discharger’s bag spout interface contains the dust.
As the bag empties and elongates, the telescoping tube maintains constant downward tension, promoting complete discharge. Additional support of flow through the spout is provided by the bag activators that raise opposite bottom sides of the bag into a steep “V” shape.
After descending through the telescoping tube, the starch passes through the knife gate valve and then through one of the two vertical chutes to a weighing station on the second floor. A horizontally oriented 6.7-in. diameter auger on the third floor can run in either direction, so each discharger can supply either of the two weighing stations that send the signals to open or close the knife gate valves.
“The twin half-frame bulk bag discharger is easy to keep clean using compressed air or a damp rag, and maintenance needs are very low,” says Kvingedal. “It reduces manual effort, contains dust and improves the working environment.”