Homogenization of the Spatial Sensitivity of Electrostatic Sensors for the Flow Measurement of Pneumatically Conveyed Solids in a Square-Shaped Pipe

Abstract

Abstract-The spatial sensitivity of an electrostatic sensor is recognized as an important factor that affects the accuracy of solids flow measurement in a pneumatic conveying pipe. However, the distribution of the spatial sensitivity is generally inhomogeneous due to the physical structure of the electrostatic sensor and the inherent electrostatic sensing mechanism. This paper proposes a sensitivity homogenization method based on differential measurement, i.e., using the differential outputs from two electrodes with different axial widths. The validity of the sensitivity homogenization method for a square-shaped electrostatic sensing head, which consists of strip-shaped electrode arrays with different widths, is validated through mathematical analysis. Furthermore, the response of the electrostatic sensing head incorporating the sensitivity homogenization method to roping flow regimes was evaluated on a gravity-fed solids flow test rig. Results from both modeling and experimental tests indicate that the homogeneity of the spatial sensitivity is improved significantly. The mean non-uniformity of the outputs from the sensing head is 11.7% as a result of the homogenization method.Index Terms-electrostatic sensor, spatial sensitivity, sensitivity homogenization, square-shaped pipe, gas-solids two-phase flow.

Electrostatic sensors – Their principles and applications

“…However, this entails innovative sensor design and construction as well as the development of novel signal processing algorithms. There have been attempts to improve the sensing field uniformity of a strip-type electrostatic sensor through a differential arrangement of two electrodes with different axial widths [137].…”

Reweighting Signal Spectra to Improve Spatial Sensitivity for an Electrostatic Sensor

“…This type of sensor modeling mainly involves two different aspects. One is the establishment of the relationship between the output and flow rate or concentration considering the effects of various parameters such as velocity and particle size [2,3,4], and the other relates to the dependency of the sensor’s dynamic characteristics on particle distributions [5,6,7,8]. The focus of this paper was on the latter.…”