In food processing, bulk bag discharge systems are used to transfer food ingredients such as flour, sugar and spices from bulk bags to mixing and blending equipment. However, when not designed or installed properly, bulk discharge systems can become a production bottleneck.
Complicating the issue, bulk bag dischargers are often integrated with other equipment such as conveyors that move ingredients downstream for further processing. In some cases, workers may still manually transfer material using totes or carts. The weakest – or in this case the slowest – link in this chain can slow production dramatically.
“A poorly designed bulk bag discharger (or discharger system) can decrease downstream process efficiency, and what should take five minutes might end up taking half an hour. Upgrading to better equipment can help food processors boost their overall processing rate by tackling a potential bottleneck,” said Don Mackrill of Automated Handling Solutions (AHS), which provides engineering solutions that incorporate specialty conveyor, material handling and automation technologies.
Mackrill, a material handling and system integration expert, provides key tips to optimize not only bulk bag discharge, but also the entire production process. Within AHS’s portfolio of solutions is Spiroflow, a company that offers a comprehensive range of discharging and filling equipment. This includes bulk bag unloaders, bulk bag fillers and automated material handling machinery and accessories.
Mackrill explains how the integration of specific upgrades can effectively manage dust, minimize waste and enhance overall throughput.
Optimal Dust Containment Reduces Product Loss
Simple bulk bag dischargers typically utilize a simple support frame for free-flowing products that don’t produce dust. The operator loads the bulk bag into the frame using a forklift or hoist and does not need to regulate the flow once the neck ties are released.
When discharging products where dust is an issue, bulk bag designs become more complex. The primary goal is to completely empty the contents, which are often in powdered form, while containing any dust within the system. This reduces the amount of material that accumulates in a dust collector or on the floor, lowering maintenance and clean-up requirements.
“Bulk bag unloaders should be designed to keep fugitive dust to an absolute minimum,” said Mackrill. “In our system, the goal is ‘maximum containment.’ This includes a specialized dish to support the bulk bag, an ‘untie’ box that allows the operator to open the spout without releasing any dust.”
According to Mackrill, optional accessories like a yoke type spout closure bar can prevent dust by allowing untying of the bag without product release. The aperture can also be set to control the flow rate from the bag. The closure bars can not only close off the spout if used in a batch weighing operation, but also allow the bag to be re-tied and removed from the discharging frame.
He points out that hygienic liner clamps offer easy management of loose liners, eliminating dust emissions as the bag empties. Combined with the tensioning action of spring-loaded bag support arms, this prevents liner distension into downstream equipment.
Consider Ergonomics to Boost Production
How operators place bulk bags on discharge equipment varies considerably, which can affect the production rate. Some systems are less operator friendly, and this increases the amount of time and effort to load each bulk bag.
To change a bulk bag, the operator typically ties off the outlet spout and removes the empty bag before placing a new bulk bag on the equipment and initiating the next discharge. However, operators can waste time and labor “struggling” with some systems.
“Choosing [a discharger] featuring a more ergonomic design can simplify bag replacement and decrease the amount of time required for changeovers,” said Mackrill.
Integrate Discharge and Weighing
Improving the weighing accuracy can further improve efficiency and reduce costs.
“Food processors want to discharge as close to the exact amount of ingredients the recipe requires as possible,” said Mackrill. “If they are batching out of bulk bags with plus or minus 1-2 pounds weighing accuracy, and sometimes less depending on the application, that increases waste and can also impact batch consistency.”
In many cases, ingredients can be dispensed in batches right out of the bulk bag, instead of transferring it to a weigh feeder or weighing it in metal totes and carts. This can be accomplished in several different ways.
Consequently, it often pays to collaborate with an OEM that can provide a range of bulk bag discharger choices, including volume and weight discharge options, which can improve flow and consistency.
As an example, Spiroflow’s Universal T2 bulk bag discharger provides controllable discharge by volume. Flow from the bulk bag is easily controlled with an integral conveyor directly coupled to the base of the discharger. The conveyor can be used to accurately meter bulk bag contents to the process vessel in an enclosed, controlled manner.
Alternatively, discharging by weight with a loss-in-weight model allows total control over the amount of product dispensed from the bag. This can be varied for individually selected batch amounts, or fully interfaced with plant process control for continuous batch production.
Integrate Conveyor Systems
Increasing the productivity of bulk bag fillers may also require an upgrade or redesign of the conveyor system that transports products to the fillers. According to Mackrill, there are several categories of enclosed conveyors that meet these requirements, including aero mechanical, flexible screw and tubular cable drag designs.
“Conveyors are almost always part of an integrated system with dischargers because as soon as you get material in or out of the bag, you need to take it somewhere. We want to do that in a fully enclosed environment so that we’re not letting dust out into the plant, not losing product and not leaving the conveyor open to humidity or rain [if some of the conveyor is outdoors],” said Mackrill.
Almost every industry has a powdered version of products or ingredients that will require transport throughout a production facility for further processing. Within the food processing industry, this encompasses a range of products including powdered sugar, flour, coffee, cocoa, food additives, protein concentrates and isolates.
However, there can be challenges in conveying these types of ingredients if the powder is sticky, hygroscopic or tends to cake or pack. Powdered food products and ingredients can also present significant health and safety hazards when they become airborne and are combustible or have explosive properties.
Work with an Experienced System Integration Partner
To resolve various difficult issues, food processors can benefit from the guidance of expert powder conveying integrators that have implemented various equipment types in complex applications over decades. An experienced integrator can not only help a processor select the best type of conveyor for their application but also optimize it for their specific type of food and process.
AHS offers a comprehensive suite of material handling equipment and industrial automation solutions, including from Spiroflow, a global manufacturer of material handling equipment and provider of control systems integration, and Cablevey Conveyors, a market leading manufacturer of patented tubular drag conveying systems for food and beverage and high value industrial applications.
Determining the best bulk discharge and conveying solution often requires substantial expertise as well as tailoring the system to the specific application.
In the case of conveying powders, Spiroflow may design the bulk bag discharger or conveyor to improve flowability and accommodate specific challenges.
“We may add flow aids, lump breakers or agitators to ensure that the powder safely and efficiently moves through the system,” said Mackrill. “If the powder is reactive, we assure that every contact surface is constructed of polished stainless steel.”
The bottom line for processors is that by improving their bulk bag discharge process with expert consultation and a wide range of the most suitable equipment, they can cost-effectively produce more product with less labor and time, which is always a recipe for success.