Intrusive Effect of Wire Mesh Tomography on Gas-liquid Flow Measurement

Abstract

To investigate the accuracy of wire mesh tomography (WMT) for gas-liquid flow measurement, the experimental study focused on its intrusive feature has been carried out. The WMT principle is based on the dependency upon electrical conductivity on the local void fraction. The applied wire mesh sensor (WMS) consists of two measuring planes. Each plane has 8×32 crossing points with spatial resolution of 2.22×3.03 mm 2 and wire diameter of 0.125 mm.The disturbance level is estimated from the deviation of flow properties between each measuring plane of WMT and also from the alternative image processing for low gas intensity range. The results show the dependency of disturbance level on the void fraction shape. Furthermore, the contribution of deceleration and deformation on the flow disturbance related to the flow condition are presented. In addition, the capability of gas velocity evaluation method is confirmed and the intrusive effect becomes only one important parameter for gas velocity measurement.

Measurement of Bubbly Two-phase Flow in Vertical Pipe Using Multiwave Ultrasonic Pulsed Dopller Method and Wire Mesh Tomography

“…Moreover, it is able to measure instantaneous two-dimensional local void fraction distribution of two-phase flow at high measuring frequency. The accuracy of WMT method for the measurement of void fraction of bubbly co-current and counter-current flows has been confirmed [19][20][21]. The error of the measured void fraction averaged over a cross-section by WMT is less than 1% compared with the measured result by a fast X-ray scanner [20].…”

On the accuracy of wire-mesh sensors in dependence of bubble sizes and liquid flow rates

“…The intrusive effects appear in form of bubble fragmentation [7] and bubble deceleration when it touches the wires [1,7,14]. As reported by Wangjiraniran et al [14], the deceleration due to the presence of wire was observed to reach 40-50% in case of liquid superficial velocity lower than 0.2 m/s.…”

Applications of tomography in bubble column and trickle bed reactors

“…Of course, the disadvantage of wire mesh sensors is that they are inherently invasive, and therefore the application of these devices in certain processes may be problematic. The intrusive effects of wire mesh sensors have been studied by comparison with high speed camera measurements in transparent systems (Fuangworawong, Kikura, Aritomi, & Komeno, 2007;Ito, Prasser, Kikura, & Aritomi, 2011;Wangjiraniran et al, 2003). These studies revealed that the wire mesh can cause bubbles to break up and to either slow or accelerate, depending on the liquid velocity.…”