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Title: A study of an electrostatic flow meter
Author: Zhang, Jianyong
ISNI:       0000 0001 2425 3334
Awarding Body: University of Teesside
Current Institution: Teesside University
Date of Award: 2002
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On-line metering of pulverized materials in pneumatic conveying systems presents many challenging problems especially for lean phase flow conditions due to very complex flow regimes such as non-uniform and unstable solids concentration and velocity profiles. To date, only a few types of meters are used in the industry, although many methods are still being studied. Meters based on passive electrostatic method are among the products commercially available. The sensor studied in this thesis contained circular electrodes, and this work analyses the static and dynamic characteristics of the electrode and the complete sensor. The effects of velocity, particle size and electrode geometry are analysed. Based on certain assumptions, the effects of velocity on the net charge and on the electrode characteristics are separated. The relationship between fluctuations in concentration and the sensor's output is established, which leads to a method of compensation for the effect of velocity on the characteristics of the sensor. The model for measurements of solids concentration and solids mass flow rate is presented and verified experimentally by comparison with the weighed solids. Comparing the model developed by theoretical analysis with that based on experimental results, the influence of velocity on the net charge carried by solids is given. The effects of the sensor characteristics on both auto-correlation and cross-correlation functions are discussed. A method to improve the accuracy of cross correlation velocity measurement is suggested. Prior to the above knowledge, it was not possible to use the meters to control solids distribution or split at pipe junctions. The first experimental split trials were carried out at EMC and the split was calculated from the mass flow rate, which was taken as the feedback variable (PV-process variable) to form a closed-loop control. A PID control algorithm was used for the experiments. The results show both velocity and split can be controlled in a bifurcator system using a simple constricting valve. Although not intended as an industrial solution, it does demonstrate the principle.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available