On the Coupled Influence of Solids Concentration and Water Content in ECT Measurements of Solids Flow in Pipes

Jiangtao Chena, Zhiying Chena, Di Wua, Fengmin Xiaoa, Minghao Zhoua, Shi Liub,*

aSchool of Energy and Power Engineering, North China Electric Power University, Beijing, 102206, China

bSchool of Control and Computer Engineering, North China Electric Power University, Beijing, 102206, China,email: liushi_ncepu@yahoo.com.cn

ABSTRACT

Pneumatic transport lines are usually associated with abrasion inside a pipe and the opaque nature of the transported material. These inevitably cause difficulties for conventional flow meters to measure the flow of the solids. Electric Capacitance Tomography (ECT in short) has emerged as one of the most recent and effective techniques that can simultaneously measure the solids concentration profile inside a pipe and the speed of the bulk of the solids, hence the flow rate. However, in many situations of real industrial application, the coupled influence of the solids concentration and the water content inside the solids very often cause errors in determining the flow rate. This problem is tackled in this study. Both simulation and experiments are conducted to evaluate the influence of each of the parameters on ECT images using different sensor structures, as well as on the output from the specially designed and purposely installed electrodes. Numerical analyses and experimental results both demonstrated that the influence of the water content in the solids and the solids concentration varies in different locations, and is particularly significant within a very thin layer adjacent to the surface of the electrodes. Correlations between the water content, the solids concentration and the geometry of the sensor are made, which can be a good reference for error correction due to the uncertainty of the water content in real measurement.

Keywords ECT, velocity measurement, dense phase pneumatic convey