The Research of measurement system of oil tank liquid level based on differential capacitance sensing

摘要

Oil tank liquid level is one of the most important measurement parameters in storing and transmitting crude oil technology, but it is not easy to obtain in severe environment, especially when the measurement site is under inflammable and explosive condition. In order to realize high precision and automatic measurement of the oil liquid level, in this paper a method combining the idea of hydrostatic tank gauging (HTG) with the technology of fiber-optic transmission is described and the mathematical model of measuring liquid level is established. Meanwhile, the characteristics of differential capacitance and thermistor are investigated, and the relationship between pressure and capacitance is deduced. The experiments on oil tank liquid level measurement system based on differential capacitance sensing, such as experiments of pressure-capacitance relationship, calibration of temperature and liquid level, are performed, and parameters calculation and display are accomplished by hardware and software. All results obtained demonstrate that the system has high accuracy and stability, and is immune to electro-magnetic interference. It is hoped to help us to promote the automatic measurement and calibration and information management of oil tank liquid level.