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14 March 2017 | PBEI T oo often, companies don't consider the savings an effi- cient loss-in-weight (LIW) bulk solids feeding system can provide over time, and instead consider only the upfront equipment cost. However, buying a more accurate feeding system and optimizing its performance can increase a pro- cess's product quality and overall profitability. An efficient LIW feeding system can improve feeding accuracy for even the lowest feedrates or high-value ingredients and reduce your process's overall costs. You can also take steps during the system design phase to ensure that your LIW feeder is optimized for accurate, effi- cient performance. Proper refill algorithms, weighing con- figurations, feeder controls, and instrumentation can increase feeding accuracy and help you avoid future process problems. Before learning how to improve LIW feeding accuracy, how- ever, it's important to understand how LIW feeding works. How LIW feeding works Bulk solids feeders can generally be categorized as volu- metric or gravimetric. A volumetric feeder discharges a given volume of material per unit time, while a gravimetric feeder discharges a given weight of material per unit time. A LIW feeder, as shown in Figure 1, is a gravimetric feeder that con- tinuously measures the weight of the material to be fed and adjusts the feeder speed to maintain a predetermined fee- drate. LIW feeders are used to dose ingredients into a variety of processes in bulk solids industries such as foods, pharma- ceuticals, chemicals, and plastics. A LIW feeding system consists of a hopper, one or more weight-sensing devices (typically either digital or analog load cells), a feed device (typically a screw powered by a variable-speed motor), a con- troller, and a refill hopper and refill device. The weight accuracy of individual recipe ingredients for a continuous blending, granulation, or extrusion process has a direct effect on product quality and bottom-line savings. This article explains how to optimize that feeding accuracy. Three ways to improve continuous loss- in-weight feeding accuracy Tres maneras de mejorar la precisión en la dosificación por pérdida de peso continua La precisión en el peso de los ingredientes de una receta específica en un proceso continuado de mezcla, granulado o extrusión repercute directamente en la calidad del producto y en el ahorro final. El artículo siguiente le explica cómo conseguir la máxima precisión en esa dosificación. impact direct sur la qualité du produit et sur le coût de l'opération. Cet article explique comment optimiser la précision du dosage. Trois moyens d'améliorer la précision du dosage continu par perte de poids Dans un système de mélange, de granulation ou d'extrusion en continu, la précision de la pesée des ingrédients individuels d'une recette a un Drei Möglichkeiten um die Genauigkeit der kontinuierlichen Differenzverwiegung zu verbessern Das genau Gewicht der individuellen Bestandteile einer Rezeptur für einen kontinuierlichen Misch-, Granulations-, oder Extrudierprozess hat einen unmittelbaren Einfluss auf die Produktqualität und die Netto-Einsparungen. Dieser Artikel erklärt, wie die Beschickungsgenauigkeit optimiert werden kann. Sharon Nowak Coperion K-Tron