Moisture Measurement in Paper Pulp Using Fringing Field Dielectrometry Kishore Sundara-Rajan Xiaobei Li Nick Semenyuk Alexander Mamishev Department of Electrical Engineering, University of Washington, Seattle,USA.

10/23/2003SEAL Lab, Dept. of EE, University of Washington.2 Outline n Motivation n Introduction to FEF Sensors n Experimental Setup n Experimental Results n Data Analysis n Conclusion

10/23/2003SEAL Lab, Dept. of EE, University of Washington.3 Motivation n Annual worldwide paper production is nearly 312 million tons  Huge application market. n Machine controlled using feedback systems  Stable, but slow. n 10 sec delay on a 2000 m/min machine leads to over 0.2 miles of bad quality paper !! Solution: Incorporate Feed Forward Control Wet EndCalendaringDry end Sensors FEF Sensors

10/23/2003SEAL Lab, Dept. of EE, University of Washington.4 Fringing Field Interdigital Sensor n For a semi-infinite homogeneous medium placed on the surface of the sensor, the periodic variation of the electric potential along the X-axis creates an exponentially decaying electric field along the Z-axis, which penetrates the medium.

10/23/2003SEAL Lab, Dept. of EE, University of Washington.5 Experimental Setup n Pulp is blended using a blender to a consistency of a suspension. n Sensor is attached to the outer side of the base of an acrylic tray. n A guard plane is placed underneath the sensor electrodes to provide shielding from external electric fields.

10/23/2003SEAL Lab, Dept. of EE, University of Washington.6 Experimental Setup n Sensor Used: ä Spatial Wavelength : 40 mm ä Finger Length : 160 mm ä Penetration Depth : 8 mm n Wall thickness of the tray : 5 mm n RCL Meter : ( Fluke Manufactured, Model PM6304 ) ä Single Channel Measurements ä One Volt RMS Sinusoidal AC Voltage ä 50 Hz to 100 kHz Frequency Range

10/23/2003SEAL Lab, Dept. of EE, University of Washington.7 Electrical Measurements n All electrical parameters are near-linearly dependent on moisture concentration.

10/23/2003SEAL Lab, Dept. of EE, University of Washington.8 Cole-Cole Plots n The phase variation is inadequate to obtain a semi- circle  Greater frequency range is required.

10/23/2003SEAL Lab, Dept. of EE, University of Washington.9 Choice of Parameter n Very small resolution required  Higher error

10/23/2003SEAL Lab, Dept. of EE, University of Washington.10 Choice of Parameter n Better slope as compared to that of conductance.

10/23/2003SEAL Lab, Dept. of EE, University of Washington.11 Measurement Accuracy n Standard deviation is two orders of magnitude lower than the mean.

10/23/2003SEAL Lab, Dept. of EE, University of Washington.12 Data Fitting ä m is the slope (% / pF) ä k is the offset (%) ä C is the measured capacitance (pF) ä P is the estimated moisture content (%) n m and k are determined by least square fit.

10/23/2003SEAL Lab, Dept. of EE, University of Washington.13 Goodness of Fit n Average normalized error of 1.7%, 2.1% being state of the art.

10/23/2003SEAL Lab, Dept. of EE, University of Washington.14 Conclusion n The ability of the sensor to accurately measure moisture concentration of paper pulp, even in the presence of additives, was demonstrated. n The algorithms were developed to estimate the concentrations of the constituents of the pulp. n The measurements and the estimation algorithms were validated.

10/23/2003SEAL Lab, Dept. of EE, University of Washington.15 Acknowledgements n A special thanks goes out to: ä Sponsors –Centre for Process Analytical Chemistry, UW –Electric Energy Industrial Consortium, UWEE –National Science Foundation ä Undergraduate Research Assistants –Leslie Byrd II –Nick Semenyuk –Cheuk Wai-Mak –Alexei Zyuzin