Moisture Mass Reconciliation Protocols in Recycled Paper Mill Furnish Audits
Auditing recycled furnish requires converting weighbridge gross mass to bone-dry fiber to prevent water inflation in CoC ledgers and commercial settlements.
Capacitive Moisture Sensor
Dielectric Measurement Device
Continuous inline monitoring of water content in moving paper webs relies on changes in electrical permittivity between sensor plates. A capacitive moisture sensor measures the dielectric constant of the paper sheet as it passes through the fringing field of an electrode array. Water possesses a dielectric constant near eighty, whereas dry cellulose fiber registers between two and three.
This contrast allows high-frequency electrical fields to register minute shifts in web moisture during high-speed paper machine runs.
Surface Moisture Penetration
Electrodes arranged on a non-conductive ceramic substrate generate an alternating electric field that penetrates the top layers of the paper or containerboard sheet. As the wet web travels over the measuring head, variations in water concentration alter the capacitance recorded by the detection circuit. High basis weight board grades require specific sensor electrode spacing to ensure field penetration reaches the center of the web rather than measuring surface moisture alone.
Temperature compensation circuits correct the signal because water dielectric permittivity shifts predictably with temperature changes during drying. Continuous output signals feed directly into steam valve controllers to maintain target reel moisture profiles across the machine width.
Calibration Drift Threshold
Contact with high-speed paper webs causes gradual physical wear and surface contamination on the sensor faceplate. Mills perform daily off-line oven drying checks to verify sensor readings against gravimetric standards. Recalibration occurs when dielectric drift exceeds zero point two percent moisture content.