Case History: Loss-in-Weight Feeders Meter Solids at Custom Detergent Processing Plant

Korex, Wixom, Mich., custom blends and packages powdered automatic dish-washing and laundry detergents for the detergent industry and for supermarket chains. To produce detergent, Korex uses weigh feeders that continuously meter the detergent ingredients at rates varying by as much as two to three orders of magnitude. Some ingredients, such as hydrated sodium tripolyphosphate and hydrated soda ash, are sticky and can cause bridges or ratholes in hoppers. Despite the wide range of Korex's ingredient proportions and their handling characteristics, the processor aims for ingredient ratios that are accurate to ± 0.5 percent. Korex may switch several times a day between different product formulations, a process that's accelerated by central control. Korex's equipment is controlled by a central control room equipped with programmable logic controllers (PLCs), a central computer, and software. Ingredient and feedrate information for each formulation is stored in the control room so the PLCs can make the correct feeder adjustments. A statistical process control system continuously checks product formulation ratios for accuracy, and Korex's quality lab tests the finished products. Korex blends up to 150,000 pounds of ingredients per hour and then agglomerates and packages the finished products.