Wet Gas Measurement Based On An Inner And Outer Ring Capacitance Sensor

In this paper, a new design method was proposed. This method was based on the detected medium, the detected material field and the capacitance sensor. According to this method, a new inner and outer ring capacitance sensor was designed for the measurement of the wet gas. This research provided a new way to detect the wet gas in the condition of mixture. And an intelligent information process system was developed to realize the measurement of the wet gas. This system was based on the real-time embedded operation system with ARM kernel. The main research works of the dissertation are as following:The space filtering effect of the inner and outer ring capacitance sensor was analyzed. Particle kinetic theory was introduced to study on the space filtering function and the transfer function of the capacitance sensor. Based on this work, the rule of the space filtering of inner and outer ring capacitance sensor and the impacts of the structure of the electrode on the space filtering function were concluded.The simulation platform of the inner and outer ring capacitance sensor used to measure the cross-correlation flow velocity was established. Through the finite element analysis and orthogonal experimental study methods, the numerical simulation platform of a two-ring inner and outer capacitance sensor was established. This numerical simulation platform can provide a practical design method for the design of capacitance sensors. At the same time, this methodology can offer a practical platform to optimize the design of other sensors.The sensitivity characteristics of the inner and outer ring capacitance sensor used to measure the cross-correlation flow velocity was researched. Using the established simulation platform, the two-dimensional and three-dimensional simulation models of the sensor were simulated. The results of the simulation indicated that the inner and outer ring capacitance sensors have a very homogeneous sensitivity distribution and the homogeneous error in the detection field is less than 1%, which is far more superior to other capacitance sensors with homogeneous error in the detection field was 10%. At the same time, according to these results, the best set of structural parameters can be attained from the aspect of sensitivity field detection. And the most important factor is the electrode width of 10mm.The axial sensitivity of the inner and outer ring capacitance sensor used to measure the cross-correlation flow velocity was researched. The result of the simulation not only provided the extent and trend of the impacts of the electrode structure parameters on the axial sensitivity and the spatial filtering properties, but also established the theoretical basis for the velocity correction factor in cross-correlation flow measurement.The experiments researching on the inner and outer ring capacitance sensor used to measure the cross-correlation flow velocity was performed. According to the conclusion of the simulations on detection field sensitivity and the axial sensitivity, the inner and outer ring capacitance sensor for cross-correlation velocity measurement of the wet gas was designed. The inner and outer ring capacitance sensor obtained the effective information of the cross-correlation velocity. The focus of the experiment was to find the influencing factors and the change trends of the velocity correction factor.The experiment environment for the inner and outer ring capacitance sensor used to measure the wet gas holdup was researched. Using the three-phase flow experiment device in Tianjin University, the factors impacting the size of the droplets and the flow pattern in the pipe were analyzed. According to the research, we can conclude that the flow patterns of the wet gas both in the vertical and the horizontal pipes are stable. The conclusion provided a practical foundation for the measurement of the wet gas holdup.The experiment research on the inner and outer ring capacitance sensor used to measure the wet gas holdup was performed. The experiment, which implemented on the three-phase flow experiment device in Tianjin university and the experiment device for wet gas, indicated that, using such method, the full error was within±10%. This measurement accuracy of the liquid holdup was the same as the differential pressure flow measurement device.The real-time intelligent information processing embedded system for wet gas measurement was realized. Depending on ARM9 microprocessor and embedded real-time operation system Linux2.6.21, the friendly user interface, real-time data collection and processing and the transfer of data through U disk, wireless network and RS232/485 are implemented.