What Are The Properties Of Petroleum? – 2 Distillation curves For crude oil or crude oil fractions of unknown composition, the boiling point can be represented by a curve of temperature vs. % by volume (or fraction) of the vaporized mixture. The initial boiling point (IBP) is the boiling point of the lightest component of the petroleum mixture, and the final boiling point (FBP) is the boiling point of the heaviest component. In some references, FBP is also called endpoint.
3 Distillation curves The difference between FBP and IBP is called the boiling range or simply the boiling range. Oil fractions with a wider boiling range contain more compounds than fractions with a narrower boiling range. Crude oil boiling points are higher than 550 oC, but FBPs are not accurate. For heavy wastes and crude oil, the FBPs can be very large or even infinite as the heavy components may not change at all. In general, reported values such as IBP and FBP are less reliable than other endpoints.
What Are The Properties Of Petroleum?
4 Distillation points There are several methods for measuring and reporting the boiling points (distillation points) of crude oil and oil fractions. Some of these methods are: 1- True Boiling Point ASTM D (TBP) 3- Simulated Distillation (SD) or ASTM D Equilibrium Evaporation (EFV) 5- ASTM D 1160
Crude Oil & Fractional Distillation (4.2.1)
ASTM D 86 is one of the simplest and oldest methods for measuring and reporting the boiling points of crude oil and its fractions. The test is carried out at atmospheric pressure using 100 ml of the sample and the result is evaporated at 0, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90% by volume. For raw and heavy products, the maximum temperature is 90, 70 or 50% of the conveyed volume. This is due to the decomposition of heavy hydrocarbons at high temperatures.
The cracking effect is significant at temperatures above 350 °C, however temperatures listed in ASTM D 86 above 250 °C should be used with caution. The corrections used to find cracking effects range from 250 to 500 oC, but these methods are not widely used and are not generally accepted. The following is an instrument for measuring the distillation of crude oil particles according to the ASTM D 86 method.
ASTM D 86 distillation data does not reflect the actual boiling points of the petroleum fraction components. Actual atmospheric boiling point (TBP) data is obtained by distilling petroleum mixtures using a theoretical distillation column with relatively high boiling ratios (1-5 or higher). The high degree of fineness of these distillates ensures precise distribution of the components of the mixtures. The lack of standardized equipment and operating procedure is a disadvantage, but there are differences between TBP data reported by different laboratories for the same small sample.
The IBP TBP curve is lower than the ASTM D 86 IBP curve while the FBP TBP curve is higher than the ASTM curve. Therefore, the boiling range based on ASTM D 86 is lower than the actual boiling range.
Properties Of Petroleum Fluids Book William Mccain Isbn: 9781593703738
The distillation method produced by GC is called simulated distillation (SD) and this method is described in the ASTM D 2887 test method. The simulated distillation method is simple, consistent and repeatable and can reliably indicate the boiling point of a crude oil mixture. Distillation curves are shown in terms of SD in terms of boiling point vs. wt%. % of the evaporated mixture when the gas chromatography composition is calculated as wt%. or a weight fraction. The SD curves are very close to the actual boiling points shown in the TBP curves.
For crude oil and products such as heavy fuel oils, which contain heavy compounds and may crack during vaporization at atmospheric pressure, distillation figures are calculated at lower pressures, 1, 2, 10 or 50 mmHg. The test procedure is described in the ASTM D 1160 test method. ASTM D 1160 distillation data is measured more accurately than ASTM D 86 because it is conducted at a lower pressure. For this reason, the ASTM D 1160 curves are close to the TBP curves with the same stress base.
12 K UOP Watson’s characteristic coefficient (Kw) is one of the oldest characteristic coefficients first described by Watson et al. Universal Oil Production (UOP) in the mid-1930s. Therefore, this parameter is sometimes called the UOP characteristic and as naphthenic hydrocarbons have Kw values between paraffinic and aromatic compounds. In general, aromas have low Kw values and paraffins have high values.
13 K UOP Watson K was developed in the 1930s based on data on crude oil and products available at the time. Today, the main sources of oil in general have changed a lot since the 1930s. However, because it combines the two characteristic parameters of boiling point and specific gravity, it is widely used in developing many physical properties of hydrocarbons and petroleum fractions.
Solved Poly. (tbp Curve) 0 10 20.30 40 70 50 60 Vol% 80 90
14 RVP Reid Vapor Pressure (RVP) is the total pressure of the mixture at 37.8 oC (100 °F) with a steam to water ratio of 4 for various things. RVP is also a useful measure for estimating losses from storage tanks during filling or emptying. Equipment and methods for standard RVP measurement are described in ASTM D 323 test method. In general, the true vapor pressure is higher than the RVP due to gases dissolved in the liquid fuel.
For a pure compound, the freezing point is the temperature at which a liquid freezes under a pressure of 1 atm. Similarly, the melting point is the temperature at which a solid changes to a liquid state at a pressure of 1 atm. Pure matter has the same freezing and melting points; however, for petroleum mixtures, the melting and freezing ranges are given as the percentage of the mixture that has melted or frozen. for petroleum mixtures, the initial freezing point is higher than the initial melting point.
16 Pour point The pour point of an oil component is the lowest temperature at which the oil pours out or liquefies when operating under normal refrigeration conditions. The pour point represents the lowest temperature at which the oil can be stored and still flow underground. The petroleum product cannot be stored or transported by pipeline when the temperature is below the pour point. Test methods for measuring the freezing point of petroleum particles are given in ASTM D 97 and ASTM D 5985 methods.
17 Cloud point The cloud point is the lowest temperature at which wax crystals begin to form under normal conditions by gradual cooling. At this temperature, the oil turns cloudy and the first wax crystals appear. The standard method for measuring the cloud point is ASTM D. Low cloud point results are desirable under low temperature conditions. Wax crystals can clog fuel system lines and filters, which can stop aircraft and diesel engines in cold weather. Cloud points are calculated for oils that contain waxy paraffin, so cloud point data are not provided for the lighter fractions (kerosene or gasoline).
The Science Of Petroleum: Crude Oils, Chemical And Physical Properties, Vol. V, Part I. Benjamin T. Brooks And A. E. Dunstan, Eds. New York: Oxford Univ. Press, 1950. 200 Pp. $11.00.
18 Crude oil properties The flash point of a hydrocarbon or fuel is the lowest value at which the vapor pressure of the hydrocarbon is sufficient to generate the steam necessary to ignite the hydrocarbon in air in the presence of an external source, i.e. spark or spark. . ASTM D 93 is the standard method for measuring flash point. The flash point is a key parameter from the point of view of safety, especially during the storage and transport of volatile petroleum products (e.g. LPG, light petrol, petrol). The temperature around the storage tank should always be below the fuel level to prevent ignition.
Flash point should not be confused with flash point, which is defined as the lowest temperature at which a hydrocarbon remains on fire for at least 5 seconds after ignition. The auto-ignition temperature is the lowest temperature at which hydrocarbon vapors ignite spontaneously when mixed with air without an external source. Auto temperature values are usually higher than the flash point. This is especially important for safety when compressing hydrocarbons. The standard test is ASTM D 2155.
20 Scope Ignition Combustion requires three elements: fuel (hydrocarbon gas), oxygen (ie air) and a spark to initiate combustion. One of the important parameters for good combustion is the ratio of air to hydrocarbon fuel. If there is too much air (too little fuel) or too little air (too much fuel), ignition will not occur. This means that combustion occurs when the concentration of hydrocarbons in the air is within a certain range. This ratio is called the flammability range and is usually expressed as a decreasing percentage of the mixture of hydrocarbon vapors and air.
21 Octane number Octane number is a measure used to indicate the anti-ignition properties of fuel (gasoline and jet fuel) for spark ignition engines. The octane number is a measure of the fuel’s resistance to oxidation during and before compression.
Pdf) Certain Relationships Between Chemical Composition And Properties Of Petroleum Asphalts From Different Origin
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