Experiment Study On The Characteristic Of Crude Oil Fouling

With the developments of oil extraction, oil property is getting worsen, and the impurity in oil is still very high, the fouling in the crude oil heat exchanger is becoming serious. So far, systematic experimental study on the fouling feature of crude oil is absent at home, the quantitative experimental data is even less, which holds back the development of the anti-scaling and cleaning technology. This thesis which is aimed at this situation researches the fouling character of the Lungu crude oil.On the basis of the thermal conduction rule, this thesis firstly analyzed the determination method and principle of thermal fouling resistance. Secondly we simulate the process of heat transfer and fouling in crude oil by using the autoclave test apparatus, record the measured surface temperature, bulk temperature and heating capacity by using the King-View software. According to analyze the change of heat transfer coefficient we get the fouling resistance and fouling rate.We investigate the bulk temperature, surface temperature, Reynolds number and pressure effects separately. With the increase of surface temperature, the reaction induction period shorten, the fouling rate quicken, the initial surface temperature increased from 290℃to 350℃, and the fouling rate added about three times. Compared to surface temperature, the influence of efficiency film temperature to fouling rate is much stronger, and the reaction activation energy is 51.07kJ/mol. At a constant operation condition, with the elevated of bulk temperature the fouling rate is decreased in the range of 290℃to 350℃. The main reason is that with the elevated of bulk temperature, viscidity of the oil is decreased, and the Reynolds number increased evidently. At the same time, with increase of the solubility of asphaltene, the sediment reduced. Reynolds number has a very complex impact on fouling, with the continuously increase of Reynolds number from 4000 to1000, the fouling rate of crude oil presented a reductive trend, and The Reynolds number in 4000 is five times higher than it in 10000, which show that the deposition and adhesion or the chemical reaction near the thermal bound layer controlled the whole fouling reaction. The fouling tendency was almost identity at the pressure of 2.0~6.0MPa. That is to say, the pressure has a much smaller impact on the fouling of crude oil, even can be ignored.This thesis also calculated the activation energy of fouling on the base of Polley threshold fouling model, by using film temperature instead of wall temperature. Then we used this temperature as the standard to calculate the oil property and Prandtl number in the fouling reaction, and set up a new fouling rate forecast module. We also used the experiment data to validate and found the average absolute relative deviation is 29.12%.In the end, we investigate the influence of operating condition to the scale inhibitor particulate. We find that the thermal fouling resistance has been reduced to two to four times after adding scale inhibitor particulate, at the same operating condition. The scale inhibitor particulate has little influence to the reaction induction period and fouling rate. That is to say, adding scale inhibitor is a very efficient method to scale controlling.