Correlation Analysis of Relationships Between the Yield of Light Oil Fractions and Its Specific Gravity
Abstract Generated abstract
This paper examines the relationship between oil specific gravity and the yield of light fractions distilling up to 200 and 300°C. Using data from oils studied under a unified program, the authors apply correlation and regression analysis, with statistical calculations performed on a MIR-1 computer and significance assessed by Student’s and F criteria. The results show strong reliable correlations between specific gravity and the two fraction yields, and the derived regression equations are judged adequate for practical estimation of light oil fraction yields from specific gravity.
Full Text
only traces of diopside.
-
The formation of diopside at the stages of solid-phase reactions in the charge based on tremolite promotes rapid glass formation and clarification of the melt. Glass based on oxides at melting temperatures (1425–1450°C) is not fully clarified.
-
The formation of diopside at the stages of silicate formation promotes an increase in the crystallization ability of the glass. In this case, the principal crystalline phase is diopside of stoichiometric composition.
Literature
-
L. A. Zhunina, Z. I. Govorushko, V. D. Mazurenko. Change in the structure and properties of glasses of pyroxene compositions as a function of heat-treatment conditions. In the collection Glass, glass-ceramics, and silicate materials. Issue I, “Vysshaya shkola,” Minsk, 1970.
-
L. A. Zhunina. Study and synthesis of pyroxene glass-ceramics. In the collection Glass, glass-ceramics, and silicate materials. Issue I, “Vysshaya shkola,” Minsk, 1970.
-
V. I. Vereshchagin, E. P. Tsymbaluk. Preparation and study of glass-ceramics based on tremolite with a diopside and crystalline phase. Abstracts of reports at the XVI Regional Scientific and Technical Conference, Novosibirsk, 1973.
CORRELATION ANALYSIS OF RELATIONSHIPS BETWEEN THE YIELD OF LIGHT OIL FRACTIONS AND ITS SPECIFIC GRAVITY
T. T. Blagopoluchnaya, N. M. Smolyaninova, A. F. Fedorov
Long-standing practice has established a number of indices of oil and petroleum products that characterize their properties with sufficient completeness. Such characteristics include: specific gravity, fractional composition, viscosity, pour point, coking capacity, flash point /1/.
Specific gravity, being among the most widespread
of the indicators measured in the study of oils and petroleum products depends on the elemental composition of the oil. The higher the content of carbon, oxygen, and sulfur in the oil, the higher its specific gravity. Thus, the greater the content in the oil of hydrocarbons rich in carbon and relatively poor in hydrogen, and the greater the amount of oxygen-containing substances (resins, naphthenic acids), the higher the specific gravity of the oil, which may serve as a criterion of the chemical composition and quality of oils and petroleum products.
In addition to chemical composition, the fractional composition of oil is of decisive importance for the magnitude of its specific gravity. A very low specific gravity of oil is a consequence of a high content of low-boiling fractions. Conversely, a relatively high specific gravity is explained primarily by a low content of gasoline fractions. Fractional composition is the most important characteristic of oil, showing the presence and quantity of fractions distilling over within definite temperature intervals. Since all low-boiling products—gasoline, ligroin, kerosene—are characterized by quite definite values of the beginning and end of boiling, the fractional composition of an oil makes it possible to judge the absolute content in it of each of the listed products, and the fractional composition of a product—its compliance with the relevant technical specifications.
Thus, between the specific gravity of oil and its fractional composition (the yield of fractions up to \(200^\circ\mathrm{C}\)—\(\beta_{200}\), and up to \(300^\circ\mathrm{C}\)—\(\beta_{300}\)) there exists a quite definite relationship, which we attempted to express analytically.
The problem posed was solved by means of correlation analysis, which at present has become widely used for establishing relationships between various parameters of the object under study. A sufficient quantity of data has been accumulated on oils studied according to a single unified program /2–4/. Verification of the initial data by the density function of the normalized deviation /5/ gave satisfactory results. Proceeding from the accuracy, duration, and labor intensity of the methods for determining the specific gravity and fractional composition of oils, we chose the specific gravity \(\left(\rho^{20}_{4}\right)\) as the argument.
In the statistical analysis of the above-mentioned properties cor-
thereby their means, standard deviations, pair correlation coefficients, the regression coefficient and its standard deviation were calculated on the “MIR-1” computer. The reliability of the pair correlation coefficients was checked by Student’s criterion, and the adequacy of the regression equations by the \(F\)-criterion /5/. The results of the calculations are given in Tables 1 and 2.
Table 1
Statistical characteristics
| Indicators | \(N\) | \(\overline{X}\) | \(\sigma\) | \(r\) | \(a\) |
|---|---|---|---|---|---|
| \(\rho_{4}^{20}\) \(\beta_{200}\) |
182 | 0,8594 26 |
0,027 10,6 |
0,81 | 313 |
| \(\rho_{4}^{20}\) \(\beta_{300}\) |
176 | 0,8587 46,6 |
0,027 12,2 |
0,82 | 279 |
Designations: \(N\) — sample size, \(\overline{X}\) — mean value of the indicator, \(\sigma\) — standard deviation, \(r\) — pair correlation coefficient, \(a\) — regression coefficient.
Table 2
Regression equations for determining the yields of fractions
up to 200°C and up to 300°C from the specific gravity of oil
| Regression equation | \(\sigma_a\) | \(F\) calc. | \(F\) tab. | Note |
|---|---|---|---|---|
| \(\beta_{200}=294-313\rho_{4}^{20}\) | 28,6 | 58 | 4 | adequate |
| \(\beta_{300}=313-311\rho_{4}^{20}\) | 27,5 | 63 | 4 | adequate |
Conclusions
- The obtained pair correlation coefficients indicate a reliable strong relationship between the specific gravity of oil and the yields of fractions up to 200 and 300°C.
-
The calculated regression equations adequately describe the true dependencies.
-
The regression equations make it possible, with accuracy sufficient for practical purposes, to predict the yield of light fractions of oil.
References
-
S. S. Nametkin. Chemistry of Petroleum. Moscow, Publishing House of the Academy of Sciences of the USSR, 1955.
-
Oils of the Eastern Regions of the USSR. Edited by S. N. Pavlova and Z. V. Driatskaya. Moscow, Gostoptekhizdat, 1962.
-
New Oils of the Eastern Regions of the USSR. Edited by S. N. Pavlova and Z. V. Driatskaya. Moscow, Khimiya Publishers, 1967.
-
Oils of the USSR. Vol. I. Edited by S. N. Pavlova and Z. V. Driatskaya. Moscow, Khimiya Publishers, 1971.
-
M. A. Plokhinsky. Biometrics. Moscow State University Press, 1970.
EFFECT OF PARAFFIN CONTENT, NAPHTHENIC ACIDS, MECHANICAL STIRRING, AND HEAT-TREATMENT TEMPERATURE ON THE POUR POINT OF WEST SIBERIAN OILS
N. V. Nikolaeva, S. I. Smolyaninov
One of the most important operational characteristics of oils and petroleum products, giving an idea of the mobility of these materials at low temperatures, is the pour point (GOST 1533-42), which, however, is not regarded as a physical constant [1].
Studies have established the influence of various factors on the pour point of oils [2–4]. West Siberian oils are the least studied object in this respect.
Using a number of oil samples from various fields (Table 1), we studied the influence of heat-treatment temperature, paraffin content, naphthenic acids, and mechanical stirring on the pour point.
The heat-treatment process consisted in heating the oil to a specified temperature followed by cooling to room temperature. Preservation of the temperature-depression effect after heat treatment was evaluated for oils over several days.