Applied Research On Electrical Capacitance Tomography In The Measurement Of Two-phase Flow

Process Tomography (PT) techniques, which have been developed rapidly in recent several ten years, have made certain progress in the field of measurement of two-phase flow/multiphase flow parameter's distribution status. It might become a means for two-phase flow measurement and could be widely applied in industry.Electrical Capacitance Tomography (ECT) is a kind of Process Tomography (PT) based on capacitance sensor. ECT has the advantage of being non-intrusive, fast in response, low in cost and safe. It has become one of important techniques for two-phase flow parameter measurement. But there are some problems and difficulties in ECT designs and ECT applications. This dissertation goes deep into research of ECT key technique .The main contribution and results are as follows:1. While analyzing the present flow imaging technique, this paper analyzes and sums up the features of two-phase flow, sort and parameter. It also analyzes the present status and the history of two-phase flow measurement. It points out the important meaning of multiphase flow measurement to the science and industry production, and sums up the research direction and developing trend of the future two-phase flow measurement.Through the brief introduction of the basic principles of process tomography, the system constitution, the basic features and developing status, the paper introduces the process tomography based on various sensing technique.2. Because ECT has strict demand for capacitance measurement, the design of capacitance/voltage converting circuit which is used to measure capacitance becomes a nodus. Through studying some kinds of capacitance measurement circuit, a practical one is given. The static characteristic indexes are given in this dissertation after some experiments have been done.3. The Digital Signal Processor (DSP) has been applied in the new system. Using the developed firmware program and application program, the communication between DSP and host computer based on USB is implemented.4. Image reconstruction algorithm research and increasing the number of projection data are two important aspects to improve the image reconstruction quality, and the several typical algorithms of Electrical Capacitance Tomography is researched.