A feasibility study of real-time monitoring techniques for scale deposition thickness in pneumatic conveying pipelines

In this study, the feasibility of two techniques for real-time monitoring of scale deposition thickness
were evaluated. Traditional pressure drop measurements and a variant of the heat pulse monitoring
technique which was developed in this study were tested and compared in a lab scale experiment.
Measurements were performed on test pipes while transportation air was led through the conveying
system. Coating layers of different thicknesses were applied to the inner walls of the test pipes to
simulate scaling. Prediction models were calibrated from the experimental data by multivariate
methods and were used to assess the performance of the techniques. It was found that the heat pulse
method provided the most accurate predictions for scale thickness. The pressure drop method did not
give acceptable results for the application considered in this paper. Results show that the heat pulse
method is somewhat sensitive to changes in the feed air temperature. However, it will still provide
reliable results for online monitoring of industrial applications in which the conveying air temperature is
relatively stable.