Study On Vapor Pressure Measurement Accuracy Of Petroleum Products

With the development of industrialization,the demand for oil is growing,the study of the nature of oil is essential,in which the vapor pressure of petroleum products in the winter and spring requirements is less than 90 kPa;summer and autumn gasoline vapor pressure is less than 70 kPa.At home and abroad,there are many effective methods to measure the saturated vapor pressure of petroleum products.Therefore,this paper mainly studies is the measurement precision of saturated vapor pressure about petroleum products from four kinds test methods and test conditions.The 92# and 95# gasoline was repeated measured and the uncertainty of measurement was calculated.Then,used blend oil 1# as the object of study to determine the expansion uncertainty,and the homogeneity and stability were investigated.By comparing the current standard of vapor pressure at home and abroad with four standard methods.The results show that the four basic methods are the same,but the accuracy is different,the respectively and reproducibility of Reid method are 0.7 kPa~3.2kPa and 2.4 kPa~ 5.2 kPa.The dry method is 3.65 kPa~4.00 kPa and 5.38 kPa ~ 5.52 kPa.The mini method is between 1.06 kPa~2.05 kPa and 2.11 kPa~4.09 kPa,The Three Expansion Method Reproducibility is within 0.5 kPa and reproducibility does not exceed 1.63 kPa.And Reid method and dry operation process is complex,so this article selects the high accuracy and easy operation of the three expansion method as a test method.The results showed that the experimental conditions such as container volume,pre-treatment,injection temperature and saturation time had no obvious effect on the test results,and the curve was not changed obviously.The results showed that the influence of different test conditions on the measurement results and the uncertainty analysis The Maximum Uncertainty is 0.69 kPa,and the curve shows a significant decrease trend.The test temperature has obvious effect on the test,and the maximum uncertainty is 0.269 kPa.At 37.8? temperature around,when the temperature change ± 1?,the vapor pressure size change ±1.2 kPa,so the instrument temperature control equipment should be regularly tested.According to the uncertainty of MINIVAP instrument,the results show that the uncertainty mainly includes three categories: pressure sensor indication,temperature sensor indication,repeated measurement uncertainty.Among them,the instrument temperature sensor shows the uncertainty of 0.012 kPa,pressure sensor indication uncertainty of 0.058 kPa,used the 92# gasoline and 95# gasoline as object of study,the 92# gasoline measurement uncertainty was 0.855 kPa and the repeatability uncertainty of 95# gasoline was 0.608 kPa.Based on the above discussion and the characteristics of gasoline that volatile and unstable,the stability of the system with the adjustment of the blend oil 1# for the study,the measurement uncertainty is 0.017 kPa,and its stability and uniformity are qualified,can apply to become a vapor Pressure standard material for calibration and verification of the instrument,used in the field of petroleum product measurement.