Another way to mitigate dust accumulation is through sufficient cleaning to remove any potential powdered debris. For this, tubular cable conveyor systems from leading manufacturers like Cablevey Conveyors offer options for dry and wet cleaning to remove accumulations of dust and food residue. The Iowa-based company has designed, engineered, and serviced enclosed cable and disc tube conveyors for almost 50 years, and operates in more than 66 countries. The company currently offers cleaning accessories such as brush boxes, urethane wipers, air knives, in-line sponges, in-line bristle brushes, as well as complete, multistep, fully automated CIP wet cleaning systems.
Specific powdered food challenges
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.
“When conveying powders, understanding the requirements is critical because an explosion can injure people as well as destroy essential equipment, causing lengthy downtime,” says Gary Schliebs, a process engineer and director of Plus One Percent, a consulting firm that works in the food industry and globally markets food industry conveyor equipment. “So any conveyor system that handles such material must be designed and engineered to comply with all safety codes and have dust-mitigation procedures in place.”
The distances and rate of speed required to move the material are also considerations. Does the conveyor need to pick up from, feed multiple locations, or follow a complex route around other equipment or structures? Are there any special safety considerations based on area classification, traffic, or other processes?
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Ideal solutions for conveying powdered food
Preventing caking and packing
The most critical aspect to consider is the type of product you’re trying to convey. Issues such as product flow, abrasiveness, and cohesiveness should always be considered, whereas product degradation or the need to maintain a blend may be key aspects to consider in some applications.
When conveying flour where degradation is a concern, an aero mechanical conveyor is also a good choice. Along with high-speed discs and a stainless-steel cable, it creates an airstream that conveys flour up the tubes. The material is transported gently through the airstream between the discs, ensuring minimal handling and no dust generation due to the nonfriable nature of flour. Any dust generated will remain suspended in the airflow together with the material and won’t accumulate or come into contact with potential ignition sources.
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Because sugar, grains, flour, and other powdered food products can combust, it’s critical that the conveyor system minimizes or eliminates potential sources of ignition, such as sparks or fire. Improper maintenance of conventional open, mechanical conveying systems can become an ignition source since they use numerous moving parts. Bearings and out-of-alignment belt conveyors, for example, can be problem areas if they cause sparks or generate heat from friction.
Although enclosed conveyors can be used effectively to convey powders in the food industry, the choice may be dictated by the specific product and size of powder.
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In the end, implementing a conveyor that minimizes the risk of dust escape and explosion along with problems like caking and packing can be the recipe for better health and safety as well as greater productivity and profitability.
Flour
Flexible screw conveyors are an ideal choice for flour. The flexible screw conveyor’s only moving part, the spiral, continuously mixes as it conveys. The conveyor can be configured with a drop-out trap, quick-release flanges, and a reverse bung that facilitates hygienic flour conveying when switching between different batches of flour.
However, enclosed, pneumatic systems can still create a “dust cloud” inside the tube as well as on exit. Because tubular cable conveyors don’t suspend material in high-velocity airstreams, less “energy” is imparted into the conveyance, and the slower velocity reduces any friction and heat generated to well below an ignition point, limiting it to about 10°F to 20°F above ambient temperature.
Sugar
Because powdered sugar is highly flammable and explosive, conveying-system design should minimize this risk. In fact, due to recent industrial accidents, government regulatory bodies like OSHA and the National Fire Protection Association have issued heightened regulations governing the handling of sugar. Furthermore, powdered sugar tends to pack and cake while conveyed. Like powdered sugar, granulated sugar is highly combustible, potentially explosive, and will ignite at high temperatures.
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.
The quandary for processors is selecting the right conveyor from the variety of options and brands available, which can involve considering all these factors as well as the material’s characteristics, flow rate, and other requirements.
An experienced conveyor supplier can advise food processors on the ideal options for resolving common challenges associated with conveying powdered food products, such as caking, packing, and hazardous dust emissions.
Ground coffee and mixes
When conveying ground coffee or mixes, dust control is of utmost importance due to combustible properties and the need for operator safety. Since ground coffee is hygroscopic, it easily absorbs moisture and is prone to clumping. Maintaining the consistency and size of the ground coffee is also essential for brewing a good final product. In addition, conveying systems processing different types of flavored coffees or mixes often must be quickly and thoroughly cleaned between product changeovers to prevent flavor cross-contamination.
Mackrill offers the following examples.
For food-grade applications, hygiene specifications and the ability to clean-in-place are key considerations.
According to Mackrill, there are several categories of enclosed conveyors that meet these requirements, including aero mechanical, flexible screw, and tubular cable-drag designs. However, factors such as the type and size of the powder and the specific challenges those materials create when conveyed often dictate the ultimate choice.
With powders, care must be taken to prevent the powder from caking and clogging the conveyor, which can result in downtime and increased safety hazards during maintenance and cleaning.
To resolve these 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.
“One of the best ways to prevent fugitive dust is to use an enclosed conveyor. This prevents spillage, the release of airborne dust, the need for additional cleanup of the surrounding area, as well as the potential for powder contamination from the external environment,” says Mackrill.
Given the variety of conveyor choices and powdered food ingredients that must be safely moved during processing, the potential risks warrant careful examination of the available equipment options in consultation with experts.
For more information, call 704–215–2624, email [email protected], or visit www.spiroflow.com.
“While there are many conveyor options in the market, some are more effective at addressing issues like dust escape and explosion risk as well as caking, packing, and cleaning out residue between batches,” says Don Mackrill, regional sales manager at Automated Handling Solutions (AHS). “Processors that minimize or eliminate these issues in the conveyor design will improve their safety, productivity, and product quality.”
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