Study On Intelligent Detection Of Water Content In Crude Oil

Water content in crude oil plays a vital role in crude oil secure exploiting,storage, transportation, subsequent process and so on.Because of long-time exploit,oil wells in our country have already come into a high water content period. Based on our country crude oil character, a new method to measure water content in crude oil is studied. It is important to develop new sensors, exploit instruments with high accuracy, stabilization and large measure scope. Actually there are many methods to measure water content in crude oil,for example density method, shortwave absorb method, capacitance method, microwave method.Microwave method is selected in this paper to measure water content in crude oil.Microwave is a kind of high frequence electromagnetic wave, because the permittivity of water molecule is more larger than pure oil, the power attenuation of microwave is mainly absorbed by water when microwave pass through oil with water. Though measuring microwave attenuation the rate of water content in crude oil is known, which is the principle of microwave method measure water content in crude oil. This method can meet the demand of online and sequence measure and has some merits, such as strong resist interfere, good reliability, high accuracy and so on. So this paper select microwave method to realize measure water content in crude oil.The main design of this paper are microwave test system, signal processing system, MCU system. Traditional single channel method is improved in this paper,double channels including measuring channel and reference channel are used to achieve automatic calibration. Because of microwave is high frequency, it is difficult to measure the moisture content in crude oil directly by the analysis of the attenuation of microwave energy. Instead, it is simple to use a 1KHz square wave to modulate it and analysis the amplitude changes of low frequency square wave after demodulation to measure the moisture content in crude oil. So this paper designs a modulation and demodulation microwave measurement signal processing system, including selected frequency amplifier, rectifier circuit,filter circuit, A/D converter, realize microwave measure signal detect. STC89C52 is used in MCU system to control A/D converter to collect and process data.Temperature compensation is achieved by controlling temperature sensor and numerical control attenuator is used to realize automatic calibration zero, such to realize automatic calibration adjust. At last LCD display is used to display water content in crude oil.This experiment device could accurately measure high water content in simulate crude oil sample from 10% to 60% and the measure error is less than 2%.