STUDY OF THE PYROLYSIS PROCESS OF FRACTIONS OF SAMOTLOR CRUDE OIL

M. D. Medvedev

(Presented by the scientific-methodological seminar of the organic departments of the Faculty of Chemical Technology)

In Western Siberia, enormous potential resources of oil, gas, and gas condensate have been discovered. The directives of the 25th Congress of the CPSU provide for the construction of the Tomsk and Tobolsk petrochemical complexes. One of the main processes for processing the above-mentioned raw materials at these petrochemical complexes will be pyrolysis for the purpose of obtaining monoolefins.

The novelty of the raw material makes it necessary to study both the chemical composition of the product and the options for its processing, as well as the optimal operating conditions of the process.

This work presents the results of studies of the pyrolysis process of gasoline fractions 32–120, 32–180, and 120–180°C of Samotlor crude oil. The studies were carried out on an enlarged laboratory unit with a flow-type reactor according to a method developed at NIISS.

The physicochemical characteristics of the above-mentioned fractions are presented in Table 1.

Table 1

Physicochemical characteristics and group composition of the 32–120, 32–180, and 120–180°C fractions of Samotlor crude oil

The results of the studies are shown in Tables 2, 3, and 4. In studying these fractions, a simplex method of experiment planning was used.

Table 2 shows the results of the pyrolysis process for the 32–120°C fraction of Samotlor crude oil. In the sixth experiment, the ethylene yield was 40.1 wt. % of the initial feedstock; subsequent experiments confirmed—

Table 2

Matrix of simplex planning of experiments for the 32–120°C fraction of Samotlor crude oil

Table 3

Matrix of simplex planning of experiments for the 32–180°C fraction of Samotlor crude oil

... that the optimum region was reached and that the following parameters correspond to it:

temperature at the reactor outlet, °C — 805;
feed supply to the reactor, ml/min — 3.2;
dilution with steam, wt. % — 63.

Table 3 presents the results of pyrolysis of the gasoline fraction 32–180°C. In this case the optimum region was reached in the eighth experiment at the following parameter values:

temperature at the reactor outlet, °C — 790;
feed supply to the reactor, ml/min — 2.1;
dilution of the feed with steam, wt. % — 62.

At the same time, the ethylene yield was 34.2 wt. %.

It is seen from Table 4 that the “ethylene” regime for the 120–180°C fraction was identified in the seventh experiment. The ethylene yield in this case was 29.4 wt. % based on the initial feedstock and was obtained at the following values of the varied variables:

Table 4

Matrix of simplex planning of experiments for the 120–180°C fraction of Samotlor crude oil

temperature at the reactor outlet, °C — 780;
feed supply to the reactor, ml/min — 2.1;
dilution of the feed with steam, wt. % — 54.

Mathematical processing of the research results for all the above-mentioned fractions showed that the response functions have significant surface curvature, which indicates the correctness of the optimal regimes found.

Conclusions

1. A study was carried out of the pyrolysis process of the 32–120, 32–180, and 120–180°C fractions of Samotlor crude oil.

2. Optimal conditions for conducting the pyrolysis process in the “ethylene” regime were found.

3. It was shown that the fractions studied can be used as a good feedstock for the production of monoolefins.