The Design And Research On Online Sensor Of The Water In Oil Used In Crude Oil Tank

Oil tanks, used in crude oil gathering and transferring stations, oil refineries, oil depots, oil dock and oil chemistry factories, are necessary storage equipments. To measure water content of the oil tank precisely can detect the oil-gas and oil-water interface and calculate the oil storage accurately. It has significant sense in preventing accidents of oil tanks, increasing space efficiency and maintaining justice in oil trade.Firstly, the thesis analyses the methods about measuring water-cut in oil tank at home and aboard presently. Considering the water ratio in oil tank is uneven, the thesis proposes an online water-in-oil measure system which adopts removable sensor and designs the whole scheme of the design. The measure system drives a water-cut sensor to move erectly in the tank by a single-phase motor and detect the location of water-cut sensor by a displacement sensor. So the measure system can detect the water ratio of each oil level and complete the measure of the whole tank water-cut.Secondly, through the comparison of some methods of water-cut measure, the thesis designs a capacitive sensor for water-cut measure which based on the theory of charge transfer. The components of the sensor including the capacitive probe, C/V transfer circuit, lowpass filter, voltage modulation circuit and V/I transfer circuit are finished. Besides, considering the influence of temperature on the capacitive water-cut sensor, temperature sensor is designed to conduct temperature compensation for the water-cut sensor.Last, the PCB is designed and the hardware circuits of the water-cut sensor are finished. Experiment is conducted and the measure quality of the water-cut is calculated and analyzed. Experiment proves the designed sensor has high response speed, excellent accuracy and high resolution.