Patent ID: 7048827
Filing Date: 2006-05-23
Classification: D21G,D21H,Y10S

Abstract:
1. A method of monitoring the formation of a sheet of wet stock comprising fibers wherein the wet stock is formed on a water permeable movable wire of a de-watering machine that has a headbox with a plurality of apertures through which wet stock is introduced onto the wire at a controlled flow rate, said method comprising the steps of: (a) positioning three or more water weight sensors (measurement sensors) underneath and adjacent to the wire and upstream from a dry line which develops during operation of the machine wherein the measurement sensors all have substantially the same configuration; (b) positioning a reference sensor so that it will measure the wet stock under saturated conditions; (c) calibrating the measurement sensors to equate conductance measurements made by the three or more water weight sensors to water weight above the three or more water weight sensors to develop a calibration equation, wherein step (c) comprises of (i) measuring conductance of the wet stock with a conductance detector while simultaneously recording reference sensor readings over a range of wet stock conductances to calibrate the reference sensor; (ii) measuring a range of water weights with a range of wet stock conductances using the measurement sensors to characterize their responses; (iii) developing a universal calibration relationship between wet stock conductivity and conductance measured by the measurement sensors over a range of water weight samples using data produced in steps (i) and (ii); and (iv) developing a universal calibration equation that provides a water weight as a function of wet stock conductivity, measured conductance, and relationship between the wet stock conductivities and measured conductances for the reference sensor and the measurement sensors, and following step (c); (d) measuring the conductance of the wet stock with one or more of the measurement sensors and using the calibration equation to provide the absolute water weight(s) in substantially real time.