Direct 3-D Imaging Based on Parallel-Helical ECT

Multiphase flows in annular pipes have important applications, such as in the drilling pipes in the oil industry and some pneumatic transport lines. Due to the complexity of the flow patterns, more advanced measurement techniques will be needed to see more insights. In this paper, phase distribution in an annular space is visualized by means of 3-D electrical capacitance tomography (ECT). A sensor with a double helical electrode arrangement is developed to facilitate 3-D measurement. The sensitivity map of the sensor is generated via inner product of the values of the electric fields generated by the finite-element methods. Landweber algorithm is used to reconstruct the ECT images. An experimental platform of multiphase flow detection using the 3-D ECT is built and measurements of different material distributions are made. The experimental results show that this technology can identify the shapes and positions of the working medium in the sensor.