An On-line Soft Sensor for Wood Moisture

摘要

A novel, on-line soft sensor for wood moisture is proving accurate and robust. A prototype is currently under test at a large manufacturing facility that transforms green logs into a dried wood product. The innovative sensor technology uses the entire industrial drying process as the primary sensing element. Readily available operating variables from the process combined with fundamental thermodynamic principles allow inference of the water content of the raw material. Test data are presented to demonstrate the reliability of the sensor values under both upset and normal conditions. The readings generated by the software method agree closely with those from a conventional hardware moisture meter. However, unlike conventional hardware sensors, the soft sensor i) measures the entire feedstock, not just a sample, ii) does not require periodic calibration, and iii) is immune to instrument errors due to wood species, temperature, particle size, surface condensation, sample presentation, color, salt content, etc. With high quality moisture information in-hand, management can more readily optimize the energy intensive drying process and make log purchasing decisions that avoid paying for water.