Cement Americas

WIN 2018

Cement Americas provides comprehensive coverage of the North and South American cement markets from raw material extraction to delivery and tranportation to end user.

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www.cementamericas.com • Winter 2018 • CEMENT AMERICAS 23 FEATURE I n nearly every industry, operators use solids level mea- surement to track and monitor material stored in large vessels, silos or tanks. They need to know the value of their inventory and to be able to conduct process monitoring. Key examples include corn milling, grains and powders, cement, wood chips and even sand used for oil and gas drill- ing applications. Solids can be challenging to gauge. There are numerous available measuring methods, with varying degrees of accuracy. New contactless radar technology has recently come on the market that provides a high degree of accuracy, even in the extremely dusty conditions found in silos. Solids level Measurement Challenges Material costs vary considerably by industry – the more valuable the inventory, the greater the push for improving measurement accuracy. The drive is increased by the recent trend towards vendor-managed inventory (VMI), in which outsourced vendors ensure a company's tanks are full of material needed and bill monthly for usage. These inven- tory management vendors install measurement devices on vessels, which send out signals to distribution via telemetry. However, solid level measurement is inherently difficult, due to the challenges posed by what actually takes place inside a vessel during measurement. Unlike liquids, which are always level, filling a vessel with solids creates a pyramid or cone wherever the fill enters the silo. Therefore, one is not measuring a flat surface. Conversely, when pulling product out of the silo with a cen- ter auger, surface tension permits a hole to be created at the bottom around the auger. At one point one can see the auger visibly pulling material from the bottom of the silo and the level will not change. But eventually, gravity will cause a collapse, which will result in a rapid change in the level of the product. This is often referred to as "rat-holing." There can be a significant error if the level instrument can- not react quickly enough to a rat-holing event near a mea- surement location. Measuring Up New Radar Technology for Solids Level Measurement Handles Low Dielectric Materials and Tracks Very Rapid Changes. By Joe Incontri

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