Solids content determination of lime mud for kiln operations relies mainly on oven-dry testing of manual grab-samples from the process line. Many challenges exist with manual sampling: infrequent sampling, inherent dangers with sampling from moving conveyors, test methods where samples immediately evaporate, as well as difficulty in retrieving representative samples. Mills are challenged with finding solutions that provide high-quality and frequent mud solids data to optimize kiln operations. Belt weightometers provide total weight, but do not account for moisture content. Some available conductance measurements require a probe be in contact with the moving lime mud, posing mechanical issues of the probe and a loss of quality measurements.
FITNIR LMS addresses the gap in measurement frequency as well as mechanical challenges inherent with technology available today. Based on NIR spectroscopy, FITNIR LMS characterizes lime mud solids content, and has the potential to analyze other metal oxide properties (i.e., Al2O3, Fe2O3, etc.). Online measurement is performed via an over-the-conveyor, remote sensing head situated above the conveyor that does not contact the moving lime mud.
A broadband light source illuminates the lime mud sample, and its energy is absorbed by the sample’s molecules. The diffusely reflected light is collected and analyzed, directly measuring solids content based on the water absorption. Measurements are done in real-time at an average frequency of one measurement output per minute.
FITNIR LMS measures the mud solids content feeding the kiln, providing information for feedback control of mud thickener and feedforward control of the kiln FET (feed-end-temperature). Consequently, fuel consumption and potential kiln operating issues are reduced. When used with a weightometer, dry mass flow can be calculated.
Also see related application, FITNIR MC, that measures moisture content.
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