Fully automatic vacuum saturated vapor pressure tester and test method for petroleum products

Abstract

The invention relates to the technical field of petroleum product physical property measurement, in particular to a method and a device for improving measurement for petroleum product saturated vapor pressure by utilizing the vacuum technology. The invention provides a novel design of measurement for the petroleum product saturated vapor pressure under full-automatic vacuum condition. Namely, through automatic control over clockwise rotation or anticlockwise rotation and two-in-one motion of up-and-down movement of a measuring section, self-control operation of a system valve, on-line full-automatic collection of petroleum products and parameters, and automatic monitoring on operational parameters under vacuum condition, the measurement of full automation, high fidelity and high accuracy for the petroleum product saturated vapor pressure under different temperatures is achieved.

Description

technical field [0001] The invention relates to the technical field of measuring the physical properties of petroleum products, in particular to a method and a device for improving the measurement of saturated vapor pressure of petroleum products by using vacuum technology. Background technique [0002] At a certain temperature, when the liquid evaporates in a closed vacuum container and reaches equilibrium with the vapor above it, the pressure generated by the vapor molecules hitting the wall of the device per unit area is called the saturated vapor pressure of the liquid, often referred to as the vapor pressure; The level of vapor pressure indicates the ability of the molecules in the liquid to vaporize or evaporate. At the same temperature, the higher the vapor pressure of the liquid, the easier it is for the liquid to vaporize; the saturated vapor pressure is the basic thermodynamic data of a substance. , electronics, metallurgy, medicine, environmental engineering and e...

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Problems solved by technology

[0004] At present, there are many methods for measuring vapor pressure, but not all methods can provide accurate measurement data for specific substances; there are usually two situations for the evaluation of vapor pressure of petroleum products: one is when the vaporization rate is zero. Vapor pressure, that is, bubble point vapor pressure, or true vapor pressure; the other is the widely used Reid vapor pressure. The Reid vapor pressure of petroleum products is based on the volume of the air chamber is about 500 mL, and the volume of the fuel chamber is about 500 mL. It is 125 mL, that is, the volume ratio of gas and liquid phases is 4:1, and the maximum vapor pressure measured with a special Lett vapor pressure tester at a temperature of 37.8 °C is the saturated vapor pressure (refer to the national standard GB / T 8017-87 "Petroleum Products Vapor Pressure Measurement Method (Reid Method)"); this experimental method has the following defects: (1) During the measurement process, even if the sample is cooled and filled into the fuel chamber of the vapor pressure tester, some of the oil sample The light fraction is evaporated, and the sample composition has changed when the gas-liquid phase equilibrium is reached, so the measured value is actually the saturated vapor pressure of the changed sample, which is lower than the saturated vapor pressure of the original sample or real vapor pressure; (2) Reid's method is suitable for determining the vapor pressure of gasoline, volatile crude oil and other volatile petroleum products, but not for determining the vapor pressure of liquefied petroleum gas, and this method must have l L The sampler is cleaned by hot water to ensure 100% humidity in the measurement chamber, that is, the air is saturated, so it is not suitable for testing oxygen-containing compounds (such as ethanol, MTBE), gasoline, alcohol, ketone and other polar solvents; (3) Determination by Reid method At saturated vapor pressure, the volume of the air chamber contains three gases: air, water vapor and oil vapor. When installed at the initial room temperature, although there is air and water vapor in the air chamber, it does not show pressure. When placed in a 37.8 ℃ water bath Finally, due to the increase in temperature, in addition to the vaporization of light components, it also causes the pressure of air and water vapor to increase, so the value indicated on the pressure gauge is actually the sum of the three pressures of air, water vapor and oil vapor, called The uncorrected saturated vapor pressure of the test oil, the value minus the increased value of the air and water vapor pressure, that is, the correction value ΔP, is the saturated vapor pressure of the test oil. Since the pressure of the air and water vapor pressure is difficult to accurately determine, it is used There are errors in the determination of the saturated vapor pressure of petroleum products by the Reid method; (4) The vapor pressure measured by the Reid method can be used as the quality evaluation data of whether the commercial crude oil has been stably processed, when the precise original vapor of the liquid at different temperatures is required Generally, the Reid method cannot be used for pressure data, because the error is large when using the Reid method to measure the saturated vapor pressure of crude oil at different temperatures, and the error increases with the increase of the measurement temperature; (5) Traditional manual operation, The test time is long, and there are many factors affecting the measurement, such as the temperature change during the oscillation process and the reading of the pressure gauge with the naked eye. A large number of manual operations not only easily lead to experimental errors, but also increase the pressure on the experimenter.

[0007] There is a patent application number: 201120142223.3, and a fully automatic vapor pressure tester for petroleum products is designed. The device is installed horizontally with the experimental device, and uses a rotating mechanism to automatically stir the petroleum products, which reduces the labor intensity of the test to a certain extent and improves the test. Efficiency, accuracy and repeatability; but the process is also tested under normal pressure, not suitable for measuring the vapor pressure of liquefied petroleum gas and oxygenated compound (such as ethanol, MTBE) gasoline; in addition, the invention has not yet explained how to enter the oil ( That is, automatic oil feeding cannot be realized) and the mechanism of the rotating mechanism, it is difficult to reach the level of fully automatic testing

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