Online Lignin Sensor for High Speed Sorting of Newsprint from Recovered Paper
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Date
2005-08-30
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Abstract
A compact fluorescence based sensor for real time measurement of lignin content in paper has been developed to automate the sorting of newsprint from mixed waste. Lignin content predicted using this sensor correlates well with actual lignin content. However, as a binary sensor to identify low and high lignin content, the sensor works extremely well.
Effects of various parameters such as excitation wavelength, filter bandwidth and color were studied. These results were used to optimize the performance of the sensor. A commercial trial on a moving conveyor was carried out and the results were satisfactory.
Sensor response depends on the distance between the paper sample and the sensor head. In real-time, distance between paper samples and sensor head varies depending on the thickness of paper on the conveyor. Hence, a cascaded solenoid system has been developed to move the sensor head. Calibration curves in combination with sensor head movement make the sensor very effective over a wide range of distances.
Motorola HC12 micro controller interface is provided to the sensor for analog to digital conversion, computation and serial communication to a PC. Sensor output can be monitored at a remote location away from the sorting conveyor.
The sensor is capable of identifying news print samples moving at a speed of 1200 feet per minute.
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Keywords
lignin, fluorescence, automated sorting, sensor design
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Degree
MS
Discipline
Mechanical Engineering
