NBE automated Bag Discharger provides loss-in-weight feeding of various food ingredients in a safe and efficient manner.
A multi-national household products conglomerate had an application to introduce a dry powder, methyl cellulose, into a liquid mix tank without agglomerates or fisheyes. Methyl cellulose is a finely divided, extremely hygroscopic powder that has poor flow properties. It is used as a thickening or extending agent.
The methyl cellulose is available in both 50 lb. sacks and bulk bags. This necessitated the need for equipment that could handle both types of package in the same unit. A further requirement was to discharge the 50 lb. sacks or bulk bags in a dustfree environment to prevent operator exposure and eliminate slip hazards as methyl cellulose becomes slippery when wet. The final application requirement was to deliver the product into the liquid system in batch weighments over a controlled time period.
As a result of all the application requirements and the poor flow characteristics of the methyl cellulose, NBE provided a Bulk Bag Discharger with a Combination Hopper incorporating a selfcontained, reverse pulse-jet cleaned Dust Collector; and discharge Screw Feeder with integral, slow- speed agitator all mounted on load cells with PLCbased controls. The complete equipment assembly discharges the product into a closed-loop, liquid eductor system that was provided by others.
To ensure complete, consistent, discharge of bulk bag contents; NBE provided their patented Loop Retractor Bag Hanger and pneumatically operated Bridgebuster massage paddles. The Loop Retractor Bag Hanger raises the bag loops by 10 inches as the bag looses weight to assist in complete material discharge from the bag without operator involvement. The Bridgebuster massage paddles have appropriate geometry and power to discharge the most difficult of materials.
The top of the Combination Hopper includes an inflatable pneumatic bladder seal that provides a dust-tight seal of the outer bulk bag spout. The pneumatic bladder seal transitions to an iris diaphragm valve. The iris valve prevents operator exposure to the bag contents when opening the bulk bag poly liner and, when 50 lb. sacks are in use, prevents external debris from entering and dust from exiting the hopper. The Combination Hopper has a small door for untying bulk bags and a large door for breaking sacks. When sacks are used, a removable bag break grate is included to assist the operator in this procedure. Proximity sensors on the hopper doors and bag break grate provide automatic control of the changes to the dust collector fan speed required to provide the appropriate negative airflow velocity to prevent fugitive dust depending on the bag type being handled. The dust collector is integrated directly into the Combination Hopper allowing the collected dust to be deposited back into the process without inter-connecting chutes that can plug with dust or product loss to central dust collectors.
Discharging the methyl cellulose at a controlled rate is accomplished by incorporating a Screw Feeder specifically designed for materials with difficult material flow properties . The consistent feeder discharge output assures consistent, accurate product flow into the liquid eductor while preventing agglomerates or fisheyes from forming . It also includes a poppet-type discharge shut-off valve to prevent liquid from entering the powder system when not in operation or in the event of a liquid system upset.