|MCKEOWN, SEAN - University Of Georgia|
|NELSON, STUART - US Department Of Agriculture (USDA)|
|TOLLNER, ERNEST - University Of Georgia|
Submitted to: Biosystems Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/23/2016
Publication Date: 1/29/2017
Citation: Mckeown, S.M., Trabelsi, S., Nelson, S., Tollner, E.W. 2017. Microwave sensing of moisture in flowing biomass pellets. Biosystems Engineering. 155:152-160.
Interpretive Summary: The production of pelleted biomass represents a significant emerging industry in the United States. Solid biomass can be formed from the waste products of many different natural and manufactured products. Moisture content of biomass materials is an important factor in determining their behavior in handling, processing, and value determination. Dielectric properties are those electrical characteristics of materials that determine their interaction with electric fields, and they have been found useful for sensing the moisture content of such materials. Therefore, a study was initiated on the dielectric properties of pelleted biomass materials. In this study, a microwave system designed for moisture sensing on flowing bulk material was utilized to determine feasibility in sensing moisture content of biomass materials. Two types of pelleted biomass derived from peanut hulls and pine sawdust were used for moisture content determination by microwave measurements. Both pine pellets and peanut-hull pellets were conditioned to a range of moisture contents for the tests. At each moisture content three different material flow rates were tested and compared to the moisture content determined by measurements on static materials. By using a calibration function developed for static measurements; moisture content of flowing material was also predicted. Results showed that moisture contents determined by static and flowing measurements were comparable. These findings constitute a foundation for work aimed at implementing a microwave moisture meter in an industrial pelleting process, providing benefits for the biomass industry and consumers of biomass products.
Technical 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 5.4percent-9.9percent were tested for pine and 8.9percent - 14.5percent 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.