Research On The Intelligent Instrument For Monitoring Oil-water Interface

In the production process of crude oil, the crude oil exploited from the oil well has certain moisture content, because the specific gravity of oil and water is different, the water in the crude oil will subside the base of oil tank, must be separated from the water in separation tank and processed to be low water content oil. Therefore, the detection of oil-water interface is the important link to realize the auto-control of water level in oil tank. The real-time and accurate detection of oil-water interface in oil tank is the important guarantee to successfully separate oil from water, and is also the mainly basis of managing and computing the oil volume.After the comprehensive study of present theory and technology on oil-water interface examination at home and aboard, according to the principle that the dielectric constant of oil and water is different, we design a kind of oil-water interface intelligent monitoring instrument by sectional type capacitance sensor. This paper discusses the examination principles of oil-water interface and its systemic structure in detail, and both the hardware and software design for the whole system. The monitoring instrument is characteristic of its serial communication module and two kinds of working patterns. The monitoring instrument not only can work solely, but also can constitute the computer supervisory system based on the RS-485 bus as a slave.The detection of oil-water interface is the crucial technology of the monitoring instrument, the principle of sectional type capacitance sensor is that an entire measuring range length columnar capacitance sensor is separated into subsections, each section has the fixed length, measures each section with modern microelectronics technology, if the capacitance value detected is neither the corresponding value of pure oil nor the corresponding value of water, thus the oil-water interface in oil tank will be fixed on.The monitoring instrument transforms the dynamic change of oil-water interface in oil tank into the change of electric signals through the method that the dielectric constant of medium(oil and water) real-time detected by the sectional type capacitance sensor, and detects the corresponding capacitance of the different layers liquid, then transforms the result detected into the digital signal processed by the MCU, thus achieve the intention of oil-water interface real-time monitoring and adjusting in oil tank.Both the whole system's hardware and software design use the modular design method, the simulation result proves the design up to the desired goal.