Concentration Measurement of Dilute Pulverized Fuel Flow by Electrical Capacitance Tomography

In order to eliminate the effects of flow regimes on phase concentration measurements, electrical capacitance tomography (ECT) was employed to improve the measurement accuracy. The solid particle distribution in the flow pipelines were characterized by measuring capacitance to obtain flow patterns. An improved offline iteration online reconstruction (OIOR) algorithm was proposed as the image reconstruction for the ECT system and a method of two-dimension maximum entropy threshold image segmentation was used for further image processing. Dynamic experiments were carried out for gas/solid two-phase flows. First, the flow regime was identified by the ECT, and the results were used to trace the fluctuation of the dynamic two-phase flow online. The volume concentrations were then calculated based on the reconstructed results. The experimental results indicate that the average relative error of the concentration measurements was about 1.5% over a pulverized coal volume concentration range 0.96-4.97%.