Study of the Group Hydrocarbon Composition of Kerosene-Gas Oil and Oil Fractions of Tomsk Crude Oil
Abstract Generated abstract
This paper examines the group hydrocarbon composition of kerosene, gas oil, and higher boiling oil fractions from Tomsk crude oil from well 18 of the Sosninsko-Sovetsko-Medvedevskoe field. Fifty degree distillation fractions boiling above 200°C were separated by adsorption chromatography on silica gel into methane-naphthene hydrocarbons and several aromatic groups, with comparisons between KSS and KSK silica gels. The study finds that methane-naphthene hydrocarbons decrease and total aromatics increase with rising boiling range, while kerosene and gas oil fractions contain predominantly methane-naphthene hydrocarbons and relatively moderate aromatics. The results support preliminary judgments on the possible use of these fractions for jet fuel, summer diesel fuel, and lubricating oil components, pending evaluation of finished product properties.
Full Text
STUDY OF THE GROUP HYDROCARBON COMPOSITION OF THE KEROSENE–GAS-OIL AND OIL FRACTIONS OF TOMSK CRUDE OIL
N. M. Smolyaninova, N. V. Zorkaltseva, S. I. Smolyaninov,
M. V. Shlykova
(Presented by the scientific-methodological seminar of the Faculty of Chemical Technology)
Kerosene–gas-oil fractions are used as fuel for tractor and jet aircraft engines, and also for obtaining illuminating kerosene. Gas-oil and diesel fractions are used as feedstock for cracking and pyrolysis, and also as diesel fuel. Higher-boiling oil fractions (above 350°), after appropriate treatment and purification, yield commercial lubricating oils or their components.
The quality and performance properties of these products are directly related to their chemical nature. Thus, for example, aromatic hydrocarbons impair the quality of fuels for jet engines, adversely affecting engine operation, since they increase carbon formation. Consequently, according to the technical specifications for jet-engine fuel, the content of aromatics in it must not exceed 20–25% [1]. The best diesel fuels are characterized by a high content of paraffinic hydrocarbons, especially of normal structure. Naphthenic hydrocarbons have a very favorable effect on the quality of lubricating oils. Hence the importance of studying the chemical composition of crude oil and its fractions is clear.
Table 1
Characteristics of 50-degree crude-oil fractions boiling at temperatures above 200°C
| No. | Temperature limits for fraction collection | Yield on crude oil, % | Specific gravity, $d_4^{20}$ | Refractive index, $n_D^{20}$ | Molecular weight |
|---|---|---|---|---|---|
| 1 | 200—250 | 10,3 | 0,8250 | 1,4642 | 176 |
| 2 | 250—300 | 9,9 | 0,8485 | 1,4790 | 204 |
| 3 | 300—350 | 9,1 | 0,8753 | 1,4950 | 246 |
| 4 | 350—400 | 9,8 | 0,8985 | 1,5010 | 288 |
| 5 | 400—450 | 9,8 | 9,9195 | 1,5123 | 350 |
The present work is devoted to studying the group hydrocarbon composition of fractions of crude oil from well 18 of the Sosninsko-Sovetsko-Medvedevskoe field, boiling above 200°C.
Table 3
Group hydrocarbon composition of kerosene–gas oil and oil fractions of crude oil from well 18 (Sovetskaya area)
| No. | Marking | Methano-naphthenic, $n_D^{20}$ | Methano-naphthenic, % | 1st group of aromatics, $n_D^{20}$ | 1st group of aromatics, % | 2nd group of aromatics, $n_D^{20}$ | 2nd group of aromatics, % | 3rd group of aromatics, $n_D^{20}$ | 3rd group of aromatics, % | 4th group of aromatics, $n_D^{20}$ | 4th group of aromatics, % | Total aromatics, % | Content of heteroatomic compounds, % |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | CK | 1,4380—1,4805 | 71 | 1,4880—1,5203 | 13 | 1,5350—1,5475 | 3 | 1,5500—1,5650 | 12 | — | — | 28 | 1 |
| 2 | CK | 1,4461—1,4790 | 64 | 1,4890—1,5270 | 13 | 1,5310—1,5390 | 5 | 1,5580—1,5660 | 15 | — | — | 33 | 2 |
| 3 | CK | 1,4528—1,4657 | 50 | 1,4878—1,5236 | 22 | 1,5748—1,5835 | 4 | 1,5748—1,5835 | 23 | — | — | 49 | 1 |
| 4 | CK | 1,4535—1,4775 | 47 | 1,4921—1,5328 | 25 | 1,5393—1,5461 | 7 | 1,5573—1,5890 | 11 | 1,5970—1,6013 | 8 | 51 | 2 |
| 5 | CK | 1,4618—1,4743 | 41 | 1,4833—1,5384 | 32 | 1,5300—1,5489 | 6 | 1,5522—1,5824 | 9 | 1,5931—1,6113 | 10 | 57 | 2 |
| 1 | KCC | 1,4372—1,4529 | 77 | 1,4929—1,5223 | 12 | 1,5470 | 10 | — | — | — | — | 22 | 1 |
| 2 | KCC | 1,4438—1,4830 | 70 | 1,5180 | 14 | 1,5439 | 11 | 1,5682 | 4 | — | — | 29 | 1 |
| 3 | KCC | 1,4490—1,4782 | 59 | 1,4959—1,5258 | 23 | 1,5493 | 4 | 1,5610—1,5845 | 13 | — | — | 40 | 1 |
| 4 | KCC | 1,4510—1,4700 | 52 | 1,4788—1,5274 | 24 | 1,5362—1,5481 | 8 | 1,5640—1,5859 | 11 | 1,5918—1,6014 | 3 | 46 | 2 |
| 5 | KCC | 1,4670—1,4870 | 43 | 1,4928—1,5280 | 25 | 1,5388—1,5485 | 9 | 1,5539—1,5957 | 12 | 1,5930—1,6009 | 9 | 55 | 2 |
For the study, 50-degree fractions were used, obtained during distillation of the crude oil in an ARN-2 apparatus (GOST 11011-64). Fractions from 200 to 300°C were distilled off at a residual pressure of 10 mm Hg; above 300°—at 1–2 mm Hg. The characteristics of the fractions studied are given in Table 1.
The group hydrocarbon composition was determined by an adsorption method according to the procedure recommended by VNII NP [2]. The method provides for separation of the initial fraction into methane-naphthene hydrocarbons and 4 groups of aromatic hydrocarbons, differing in the number of benzene rings in the average molecule. As adsorbent we used silica gel of the KSS and KSK grades, with a grain size of 28–50 mesh. Petroleum ether with an end boiling point of 60°C served as the solvent and desorbent. For fractions boiling above 350°C, a fractional solvent consisting of a mixture of benzene and petroleum ether in various ratios was used as the desorbing liquids [3].
Table 2 presents the results of determining the group composition of kerosene-gas-oil and oil fractions of crude oil from well No. 18. First of all, it should be noted that the separating capacity of KSK silica gel is considerably poorer than that of KSS silica gel. The latter also separates aromatic hydrocarbons into groups more distinctly.
As can be seen from the data presented, with an increase in the temperature limits for collecting the fractions, the content of methane-naphthene hydrocarbons decreases, while the content of the sum of aromatic hydrocarbons correspondingly increases. In the kerosene-gas-oil fractions (200–300°C), methane-naphthene hydrocarbons predominate; the content of aromatics is relatively low and amounts to 22–29%. The aromatics of the first fraction are represented mainly by benzene homologues; those of the second, by diphenyl derivatives, etc. [3]. Heavy aromatic (polycyclic) hydrocarbons appear only in the higher-boiling distillates.
On the basis of the indicators of the group composition of the fractions studied, a preliminary conclusion may be drawn regarding their suitability for producing T-1 jet fuel, summer diesel fuel, and also components of oils of various grades. Investigation of the properties of commercial products prepared from combinations of the indicated fractions will make it possible to draw final conclusions about the assortment of commercial products and their quality.
REFERENCES
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- Methods for the Study of Crude Oils and Petroleum Products. Moscow, Gostoptekhizdat, 1955.
- V. N. Zrelov, G. I. Kichkin. Chromatography in the Petroleum and Petrochemical Industry. Moscow, Gostoptekhizdat, 1963.