Study On The Key Technology Of Refined Oil Mixtures Detection By Terahertz Time-domain Spectroscopy

Different types of refined oil are transported through one pipeline to reduce the cost of pipeline transportation during batch transportation. It is inevitable that mixture generates in the junction of different types of oil. The mixture can't be sold directly because its quality can't reach the standard. If the arrival of the mixture can't be detected accurately, the storage tank of refined oil will be filled with mixture. Refined oil will be polluted so that huge economic losses will cause. Therefore, an accurate, reliable and efficient mixture detection technology is significant for reducing the economic losses caused by oil mixture.In this reason, our research group proposes a method of using terahertz time-domain spectroscopy(THz-TDS) technology to detect the oil mixture. At present, we have achieved mixture quantitative identification in the lab. To put the instrument into field use, there are still some problems need to be solved. First, an automatic sampling device to collect oil in real-time is needed. The fluid simulation technology is applied to explore the principle of the mixture motion and guarantee the feasibility of the sampling device. Second, the experiment of mixture identification is conducted under constant temperature, but it is difficult to guarantee that the sample is under constant temperature in the field. Experiments to determine the influence of temperature on the quantitative identification are needed. Third, we use pure product oil in lab experiments, but it is hard to guarantee that the oil is pure during batch transportation. Experiments to determine the influence of impurities in mixture quantitative identification are needed.The contents of my study are as follow:The influence of temperature change on the refractive index and absorption coefficient is analyzed using quantum mechanics and lorentz lorenz formula. The time domain spectroscopies of 90#, 97# gasoline under 0 ? to 40 ? are obtained using the terahertz time-domain spectroscopy device. The absorption coefficient and refractive index curves of 90 #, 97 # gasoline are acquired by signal processing. The relationships between the temperature and the absorption coefficient/refractive index are determined using curve fitting. The influence of temperature on the absorption coefficient and refractive index curves is confirmed.The main components of the impurity existing in pipeline, the causes of the impurity, and the influence of water content on the refractive index using lorentz lorenz formula are analyzed. The time domain spectroscopies of 90#, 97# gasoline with different water content are obtained using the terahertz time-domain spectroscopy device. The absorption coefficient and refractive index curves of 90 #, 97 # gasoline with different water content are acquired by signal processing. The relationships between water content and the absorption coefficient/refractive index curves are analyzed from different perspectives.The mathematical and physical models of different shapes of pipeline are established. Fluid simulations are conducted under the FLUENT software using multiphase fluid simulation technology. The principle of mixture motion in the pipeline is studied and some results are obtained to help the design of sampling device. Finally, a proposal of the sampling device design is proposed.