Parameters Measurement Of The Gas-Liquid Two-Phase Flow Based On The Electrical Capacitance Tomography

Two-phase flow widely exists in many industries such as chemical industry, metallurgical industry, energy industry, light industry and so on. The research on the two-phase flow, which has been one of the frontier subjects, is developing rapidly. However, the inherent complexity of the two-phase mixture makes it difficulty to measure the parameters of the two-phase flow. In many cases, the measurement technology for the two-phase flow has been one of the bottlenecks in the research field of the two-phase flow.Mass quality and flowrate are two important parameters of the two-phase flow. The thesis researches the application of electrical capacitance tomography (ECT) to the measurement of the mass quality and the flowrate of the oil-gas two-phase flow. The main work of the thesis includes:1. Based on the electrical capacitance tomography technique and the model which indicates the relationship between the voidage and the mass quality, a method is proposed to measure the mass quality of the oil-gas two-phase flow. Several models which indicate the relationship between the voidage and the mass quality of the gas-liquid two-phase flow are analyzed. A suitable model is selected to obtain the mass quality, and the model parameters are optimized based on the flow pattern. The model parameters for various flow patterns are obtained by the least square method. In the measurement process, the flow pattern of the oil-gas two-phase flow is identified firstly, and then, combined with the voidage obtained from the ECT system, the mass quality is obtained by using a suitable model of which parameters are corresponding to the identified flow pattern. Experimental results show that the proposed method is effective and the root-mean-square errors of the mass quality for various flow patterns are less than 7%.2. Combining the mass quality measurement method with the Venturi meter, the flowrate of the oil-gas two-phase flow can be achieved. Five flowrate measurement models of Venturi meter are analyzed. Primary study has been taken to measure the total mass flowrate and the liquid-phase mass flowrate. Experimental results show that de Leeuw relation can give a good measurement result for the bubble flow, the stratified flow, the slug flow and the annular flow, the root-mean-square errors of the total mass flowrate for various flow patterns are less than 11%, Lorenzi relation is suitable for the bubble flow and the stratified flow.