Food Engineering

Ingredient shrinkage cut from 1.25 to 0.25 percent

February 1, 2011
Powder blending facility had dust everywhere-dust that should have been in products, not on floors, equipment.

The mezzanine-mounted dust collector allows efficient duct runs to the processing rooms on the floor below. The collector discharges cleaned air (upper right) into the warehouse area, eliminating need for make-up air and improving energy efficiency in the air-conditioned plant. Source: United Air Specialists.


As a supplier of baking mixes, dairy blends, premixes for cheese and tortillas, and other powdered ingredients for the food industry, and a provider of toll blending, Allied Blending & Ingredients, Inc., headquartered in Keokuk, IA, knows the challenges of handling powders, which easily become fugitive airborne dusts. The company had long struggled with two dust collectors at its original California plant, which handled only 10 million pounds of product per year. “We had substantial dust on our equipment, floors and in the air, and our shrink levels were around 1.25 percent,” says Matt Stelzer, Allied Blending’s vice president of operations at the California facility.

Stelzer aimed for a much lower shrinkage rate while planning for the company’s new 25 million-pound per year plant, and he knew a sister facility had been pleased with the long-term performance of a dust collection system from United Air Specialists (UAS). After evaluating three dust collection system suppliers for the new California plant, Stelzer and Plant Manager Juan Mora selected a central-system design using the UAS model SFC 32-4 down-flow cartridge collector rated at 15,000 cfm. This unit draws contaminated air in through its top and forces it downward through horizontal cartridge filters. Its high-efficiency filter media traps contaminants, and the air passes through an after-filter before being released back into the plant or outdoors. A reverse pulse of compressed air through the filter cartridges periodically dislodges captured dust, which falls into a receptacle for disposal.

With the core unit selected, the central system was then designed so it could handle dust generated in each of the new plant’s three separate 1200-sq.-ft. production rooms, while complying with FDA requirements. 

The dairy 3A blending and batch pack rooms required a custom stainless steel duct and CIP design to prevent ingredient cross-contamination. “We use one of the rooms to process whey, nonfat dry milk and yeast, and another for mixing tortilla premixes (batch packs) with salt, sugar and micro-ingredients. So to comply with FDA regulations, 304 and 316 SS duct is used as necessary, and the system is designed to minimize or eliminate areas that can harbor particles,” says Stelzer. 

To improve air handling efficiency, conserve floor space and address potential explosion venting requirements, the collector was located on a mezzanine above the control room in the center of the plant. From this spot, the collector functions as a central system, ducted to three precisely defined collection points in each processing room. This ensures optimum airflow is pulled from each room’s hoods and carried to the collector. Then clean, filtered air is recirculated back into the air-conditioned warehouse to save energy. With its proximity to the ceiling, the mezzanine location also provides contingency for explosion venting through an outside wall.

The reduction in product shrinkage from Allied’s old plant to the new one-1.25 to 0.25 percent-is more than modest, and well below the industry average of 1.0 percent. The improvement over the old plant is obvious, as Stelzer explains. “When people familiar with the appearance of a powdered food processing facility visit our plant, they are surprised to learn that we do blending here because it is so clean,” says Stelzer.

For more information:
David Gelb; 513-354-8704; davgel@uasinc.com.