Characterization of Gas Condensate from the Myldzhinskoye Field as a Feedstock for Petrochemistry
Abstract Generated abstract
The paper evaluates gas condensate from the Myldzhinskoye field in Tomsk Oblast as a potential feedstock for petrochemical processing. Fractions obtained by atmospheric-vacuum rectification were analyzed by aniline-point methods, adsorption on silica gel and molecular sieves, gas-liquid chromatography, and adsorption methods for heavier cuts. The condensate was found to contain predominantly paraffinic hydrocarbons, with low aromatics, about 4 percent in the 28 to 320°C fraction, and high methane-series hydrocarbons, about 68 percent. On this basis, several gasoline cuts are assessed as suitable feedstocks for pyrolysis to gaseous monoolefins and for catalytic reforming, with selected reforming fractions considered especially favorable because of low sulfur content and appreciable six-membered naphthenes.
Full Text
CHARACTERIZATION OF GAS CONDENSATE FROM THE MYLDZHINSKOYE FIELD AS A FEEDSTOCK FOR PETROCHEMISTRY
N. M. SMOLYANINOVA, V. A. KUZNETSOVA, M. E. SHLYKOVA
By decision of the government, the creation of a large petrochemical complex in Western Siberia is envisaged, based on the oil and gas fields discovered there.
Primary attention will be directed toward the processing of natural and associated gases and gas condensates.
In recent years, gasoline fractions of gas condensates have come to occupy an important place among the various types of feedstock for pyrolysis and catalytic reforming.
The chemical composition of the condensate is of great importance for evaluating this petrochemical feedstock.
We have determined the hydrocarbon composition of the gas condensate from the Myldzhinskoye field, the largest in Tomsk Oblast, and characterized the target fractions of this condensate as feedstock for pyrolysis and catalytic reforming.
The fractions studied were obtained by atmospheric-vacuum rectification on an ARN-2 unit.
The group hydrocarbon composition of the fractions boiling up to 200°C was determined by the aniline-point method, with removal of aromatic hydrocarbons by adsorption on silica gel.
The individual hydrocarbon composition of fractions up to 122°C was determined by gas-liquid chromatography on a “KhROM-2” chromatograph with a flame-ionization detector.
The amount of paraffinic hydrocarbons of normal structure was found by their adsorption on molecular sieves of the CaA type (1).
The hydrocarbon composition of fractions above 200°C was determined by an adsorption method (2). The separate content of paraffinic and naphthenic hydrocarbons in the paraffin-naphthene portion was found by the aniline-point method (3).
Data on the group hydrocarbon composition (Table 1) show that paraffinic hydrocarbons predominate in all fractions of the Myldzhinskoye gas condensate. The largest amount of normal alkanes (42%) occurs in the 28–60°C fraction; in the other cuts it amounts to 25–26%.
The amount of naphthenic hydrocarbons varies over a wide range—from 17 to 35%.
The aromatic content in the condensate is low: only 4%, calculated for the broad fraction from the beginning (28°C) to the end of boiling (320°C).
Feedstock for pyrolysis should contain the maximum amount of paraffinic hydrocarbons, especially those of normal structure; the aromatic content should not exceed 4%, and the sulfur content, 0.1% (4).
Table 1
Group hydrocarbon composition of the Myldzhinskoye gas condensate
| Fraction distillation temperature limits, °C | Condensate yield, wt % | Density $\rho_4^{20}$ | Refractive index $n_D^{20}$ | Aromatic hydrocarbons, wt % | Naphthenic hydrocarbons, total, wt % | Naphthenic hydrocarbons, six-membered, wt % | Paraffinic hydrocarbons, total, wt % | Paraffinic hydrocarbons, n-structure, wt % |
|---|---|---|---|---|---|---|---|---|
| 28—60 | 9,0 | 0,6493 | 1,3668 | 0,0 | 0,0 | 0,0 | 100,0 | 42,0 |
| 60—95 | 22,6 | 0,7055 | 1,3938 | 1,0 | 35,0 | 13,0 | 64,0 | 28,0 |
| 95—122 | 14,8 | 0,7304 | 1,4089 | 2,0 | 35,0 | 27,5 | 63,0 | 22,0 |
| 122—150 | 13,7 | 0,7472 | 1,4178 | 5,5 | 24,0 | — | 70,5 | 25,0 |
| 150—200 | 17,2 | 0,7668 | 1,4783 | 7,0 | 17,0 | — | 76,0 | 26,0 |
| 200—250 | 9,5 | 0,7895 | 1,4420 | 9,0 | 26,0 | — | 65,0 | — |
| 250—300 | 4,8 | 0,8180 | 1,4550 | 11,0 | 19,0 | — | 70,0 | — |
| 300—320 | 1,2 | 0,8279 | 1,4610 | 14,0 | 16,0 | — | 70,0 | — |
| 28—320 | 92,8 | 0,7415 | 1,4147 | 4,0 | 28,0 | — | 68 | — |
Table 2
Characteristics of feedstocks for pyrolysis and catalytic reforming
| Fraction boiling limits, °C | Condensate yield, wt % | Density $\rho_4^{20}$ | Mol. wt. | Sulfur content, % | Aromatic hydrocarbons, wt % | Naphthenic hydrocarbons, wt % | Paraffinic hydrocarbons, total, wt % | Paraffinic hydrocarbons, n-structure, wt % |
|---|---|---|---|---|---|---|---|---|
| Feedstock for pyrolysis | ||||||||
| 28—90 | 25,4 | 0,6790 | 81 | abs. | 0,5 | 21,0 | 78,5 | 32,0 |
| 40—160 | 58,8 | 0,7288 | 105 | abs. | 2,0 | 32,0 | 66,0 | 24,0 |
| 40—190 | 68,9 | 0,7330 | 111 | traces | 3,0 | 30,0 | 67,0 | 28,0 |
| 140—180 | 15,8 | 0,7565 | 135 | 0,01 | 6,0 | 16,0 | 78,0 | 27,0 |
| 140—200 | 21,4 | 0,7602 | 138 | 0,01 | 7,0 | 16,0 | 77,0 | 26,0 |
| 90—210 | 54,4 | 0,7455 | 123 | traces | 4,0 | 28,5 | 67,5 | 26,0 |
| Feedstock for catalytic reforming | ||||||||
| 62—85 | 9,6 | 0,6995 | — | abs. | 1,0 | 33,0 | 66,0 | 32,0 |
| 85—105 | 16,0 | 0,7215 | — | " | 2,0 | 38,0 | 60,0 | 23,0 |
| 62—105 | 26,0 | 0,7155 | — | " | 1,5 | 36,0 | 62,5 | 26,0 |
| 85—120 | 23,5 | 0,7264 | — | " | 2,0 | 35,0 | 63,0 | 23,0 |
| 85—180 | 50,1 | 0,7363 | — | " | 4,0 | 27,0 | 69,0 | 25,0 |
| 105—120 | 7,5 | 0,7330 | — | " | 2,5 | 28,5 | 69,0 | 23 |
| 105—140 | 18,3 | 0,7364 | — | traces | 4,0 | 27,0 | 69,0 | 24 |
| 120—140 | 10,8 | 0,7430 | — | " | 5,0 | 26,0 | 69,0 | 25 |
| 140—180 | 15,8 | 7565 | — | 0,01 | 6,0 | 16,0 | 78,0 | 27 |
Judging from the group hydrocarbon composition of the condensate studied, it may be concluded that its gasoline cuts most fully meet the requirements imposed on feedstock for pyrolysis aimed at obtaining gaseous monoolefins. There are no definite requirements for the fractional composition of feedstock for pyrolysis; therefore, fractions known from the literature (4–6), 28–90°C, 40–160°C, and others were tested for this purpose. Their characteristics are given in Table 2.
The content of paraffinic hydrocarbons in the indicated cuts is 66–78%. Among them, normal paraffins are present in the greatest amount (32%) in the 28–90°C fraction; in the others, 26–28%.
As for the considerable content of isoparaffinic and naphthenic hydrocarbons, during pyrolysis they will yield mainly n-butylenes and divinyl (7).
The low aromatic content eliminates the need for dearomatization of certain cuts (29–90, 40–160, 40–190, 90–210°C).
The fractions that serve as feedstock for catalytic reforming (Table 2) are practically sulfur-free, are characterized by a low content of aromatics (1–6%) and a considerable content of naphthenic hydrocarbons (up to 38%). This makes it possible to assess them as valuable feedstock for reforming, requiring no sulfur removal.
However, the best feedstock for the indicated purposes may be the 62–105°C, 85–105°C, and 85–120°C fractions, since determination of the individual hydrocarbon composition of gas-condensate fractions has established that six-membered representatives in the naphthenic part predominate in the 95–122°C fraction, while cyclohexane is present in maximum amount in the benzene fraction.
Conclusions
-
The group hydrocarbon composition of the gas condensate from the Myldzhinskoye field has been investigated.
-
It has been established that the condensate is characterized by a low content of aromatics (4%) and a high content of methane-series hydrocarbons (68%).
-
It has been shown that the gasoline cuts of the Myldzhinskoye condensate can be good feedstock for pyrolysis and catalytic reforming.
LITERATURE
-
L. P. Kvitkovskii, V. V. Grushetskaya. Determination of n-paraffinic hydrocarbons with the aid of molecular sieves. Khimiya i tekhnologiya topliv i masel, 3, 1962.
-
Methods for the Investigation of Petroleums and Petroleum Products. Gostoptekhizdat, 1955.
-
Chemical Composition of Petroleums and Petroleum Products. NKhTI, Oil, 1935.
-
I. R. Chernyi. Preparation of Feedstock for Petrochemistry. Izd. “Khimiya,” Moscow, 1965.
-
Z. A. Sultanov. Izvestiya vysshikh uchebnykh zavedenii “Neft’ i gaz,” 12, 1958.
-
S. E. Itsek, T. N. Mukhina. Influence of the chemical composition of feedstock on the distribution of pyrolysis products. Neftepererabotka i neftekhimiya, 7, 1967.