Microwave Moisture Measurements of Flowing Biomass

Abstract. Production of pelleted biomass is a significant emerging industry in the United States. A primary quality attribute of pelleted biomass is moisture content. This parameter is critical in pricing, binding, combustion, and storage of pelleted biomass. In order to produce pellets of a high quality moisture content must be tightly controlled. In this study, a microwave system designed for moisture sensing on flowing bulk material was utilized to determine feasibility in sensing biomass. Two types of pelleted biomass derived from peanut hulls and pine were used for moisture content determination. Moisture contents from 5.4%-9.9% were tested for pine and 8.9% - 14.5% were tested for peanut hull pellets. At each moisture content three different material flow rates were tested and compared to the static measurement. Using a calibration function developed using static measurements; moisture content of flowing material was predicted. Standard error of calibration was computed for comparisons between reference moisture content, predicted static moisture content, and predicted flowing moisture content. Results showed that static and flowing measurements were comparable.