Removing Malt Production Bottleneck with Flexible Screw, Bulk Bag Filler, Unloader
HERNE BAY, UK — Muntons Malt, a division of Britain's Muntons plc, began manufacturing malt (fermented cereal grains that contain sugars) and liquid malt extracts in 1921 for brewing, distilling and food industries worldwide. The independently owned company currently sells more than 231,500 tons (210,000 metric tonnes) of malt annually, and is one of the UK's five major malt producers.
In producing dried malt, a vacuum band dryer converts liquid malt extracts into a coarse powder, which undergoes final granulation in a cone mill. Originally, the final granulation was fed from the cone mill into 1,764 lb (800 kg) tote bins stored in a 200-bin capacity holding area, before bagging and shipping. A worker filled orders by lifting a tote bin by fork lift to a mezzanine where a second worker transferred the bin about 33 ft (10 m) to the tipping unit, which unloaded the malt into the hopper feeding the bagging machine. Each tote then was cleaned to comply with Muntons' strict hygiene standards. On the bagging line, another operator applied labels to the 55 lb (25 kg) bags and fit each bag to the fill head, after which the bags were sealed, palletized and shipped.
Downtime on the manual bagging line led to bottlenecking on the tote fill line, disrupting product shipment to customers, raising operating costs and adversely affecting operating efficiency. The downtime also threatened to interrupt operation of the band dryer, which would necessitate a costly and time consuming washdown that would vastly increase wastewater treatment and water use.
In-line conveying system bypasses bottleneck
Muntons replaced the tote bin handling operation with an in-line conveying system in a new, hygienic packaging room built directly beneath the cone mill. The system would ensure an uninterrupted work flow from band dryer to bagging machine resulting in improved reliability, higher throughput and reduced manpower. The bagging line was also automated.
In the in-line system, designed and installed by Flexicon (Europe) Ltd., the dried malt extract exits the cone mill via two feed chutes into a pneumatically operated wye diverter valve, which allows the operator to direct the flow to the bagging line or, should the bagging line be shut down for service, to a bulk bag filler, which loads the malt into 1.1 ton (1 tonne) bags for temporary storage. Muntons can now supply malt in bulk bags as well as 55 lb (25 kg) bags.
Transporting malt to the bagging line and bulk bag filler are two flexible screw conveyors, one 20 ft (6 m) long and the other 13 ft (4 m) long. Both conveyors, at a 45-degree incline, have a flexible, round wire screw rotating in a polymer tube.
The TWIN-CENTERPOST™ bulk bag filler is mounted on load cells that transmit weight gain information to a controller, which stops the conveyor once the filler has gained a user-selectable weight. An inflatable inlet seal connects the bag inlet spout, after which a bulk bag liner inflator expands the bag to remove wrinkles prior to filling. An exhaust port allows for dust collection during filling, after which the bag is tied and released from the pneumatically retractable bag hooks.
Bulk bag discharger introduces product to bagging line
When product is needed, a bulk bag is retrieved from storage and positioned in the bulk bag discharger frame. The operator inserts the bag spout through an iris valve, then closes the valve, enabling the bag tie to be untied and the valve opened slowly, reducing the displacement of dust from the hopper. Additionally, a collection plenum, mounted above the iris valve, can reduce the release of dust into the plant environment.
The discharger is equipped with FLOW-FLEXER® bag activators that raise and lower the opposing bottom edges of the bags, promoting material flow from the bulk bag. As the bag empties, the FLOW-FLEXER® stroke increases, raising the bottom of the bag into a steep "V" shape that eliminates dead spots and promotes complete evacuation from the bag. From the hopper beneath the bag, a flexible screw conveyor transports malt powder to the bagging line at a rate of 140 cu ft/hour (4.0 cu m/hour).
The powdered malt material, although free-flowing, is hygroscopic and can generate a potentially explosive dust. The in-line equipment meets EU standards for potentially explosive atmospheres, and has product contact surfaces of 304 stainless steel manufactured to a food-grade finish.