RU2297440C2 - Lube fraction purification process - Google Patents

Abstract

FIELD: petroleum processing and petrochemistry.

SUBSTANCE: lube fractions are brought into contact with N-methylpyrrolidone in extraction tower according to three-step countercurrent purification scheme to form raffinate and extract solutions. When distillate fraction II (300-400°C) is purified, of sulfoxide is preliminarily added in amount of 0.1-0.5% based on the weight of solvent. Distillate fraction III (350-420°C) is then purified after addition to solvent of 0.5-1.5% of extract obtained from purification of distillate fraction II.

EFFECT: deepened purification of raffinate, increased yield of raffinate as commercial product, and enabled qualified application of extract by-product.

11 tbl, 6 ex

Description

The invention relates to the field of oil refining and can be used for the production of selective refined raffinates.

A known method of purification of oil fractions by mixing the raw material with a solvent in an extraction column with the formation of raffinate and extract solutions in the presence of an excess of solvent-free extract. In countercurrent, the raw materials are repeatedly contacted with a solvent with the formation of raffinate and extract solutions, followed by treatment of the extract solution with an excessive amount of extract to replenish the raffinate phase with the desired oil components / Goldberg D.O. and others. "Lubricating oils from oils of eastern deposits", M .: Chemistry, 1972, p.77-78 /.

A known method of purification of oil fractions by countercurrent multiple contacting of raw materials with a solvent - phenol and treatment of the extract solution with phenolic water to replenish the raffinate phase with the desired oil components. However, phenolic water degrades the selectivity of the solvent, a portion of the valuable desired hydrocarbons remains in the extract solution, and a portion of the unwanted remains in the raffinate solution. When the ratio of solvent to feedstock is 2.5: 1 by volume, 55-57% of resinous compounds and up to 80% of polycyclic aromatics are removed from the distillate fraction / NI Chernozhukov "Technology of oil and gas processing", Part 3, M .: Chemistry, 1978, p.120 /.

A known method of purification of oil fractions by adding various additives and surfactants to the solvent:

- ethyl or a mixture of isopropyl phosphates, in an amount of 0.1-1.0 wt.% based on the solvent;

- Quaternary ammonium salts and alkylomidazoline, in an amount of 0.001-5.0 wt.% based on the solvent;

- polymethylsiloxane, in an amount of 0.005-0.1 wt.% calculated on the solvent;

- mixtures of ethers, boiling off at temperatures of 130-150 ° C, in an amount of 0.3-1.0 wt.% based on the solvent;

etc. / RF patent No. 2059686 "Method for the purification of oil fractions" /.

The objective of the invention is to improve the quality of the raffinates and increase their yields when cleaning distillates II with an oil fraction (300-400 ° C) and III oil fraction (350-420 ° C) obtained from a mixture of sulfur oils, while reducing the cost of an expensive solvent.

The problem is solved in that:

1) when cleaning the distillate II with an oil fraction (300-400 ° C), oil sulfoxide in the amount of 0.1-0.5 wt.% Calculated on methylpyrrolidone is added to methylpyrrolidone;

2) when purifying the distillate of the III oil fraction (350-420 ° C), the extract is preliminarily added to methylpyrrolidone in an amount of 0.5-1.5 wt.% Obtained by purifying the distillate of the II oil fraction with sulfoxide.

This method allows you to:

- choose the optimal process temperature to obtain the maximum possible yield of raffinate with the required quality;

- increase the yield of raffinates by 2-3% without changing the temperature regime, the multiplicity of the solvent or the quality of the raffinate;

- deepen the purification of the raffinate without increasing the consumption of expensive solvent;

- use a by-product - extract to reduce costs during the cleaning process

and increase the yield of the main product - raffinate.

Petroleum sulfoxides reduce the solvent capacity of the solvent due to the formation of hydrogen bonds of methylpyrrolidone molecules with the oxo group of sulfoxides, which, in turn, increases the dipole moment and polarity of the solvent, thereby increasing its selectivity. In this case, the dissolution temperatures of hydrocarbon groups also change accordingly: the dissolution temperature of resinous substances and polycyclic aromatic hydrocarbons practically does not change or slightly decreases, and the dissolution temperature of alkanes and naphthenes increases, sulfoxides are introduced into the solvent in the form of a concentrate, the quality of which is presented in Table 1.

It is also well known that the additional introduction of an aromatic hydrocarbon concentrate (in our case, the extract obtained by purification of the II oil fraction) during extraction creates a supersaturation with readily soluble hydrocarbons, as a result, the secondary phase is separated from the extract solution, increasing the yield of raffinate.

Stage 1. The effect of adding sulfoxide to methylpyrrolidone at a constant temperature extraction mode:

Example 1. According to a three-stage purification scheme in countercurrent by the method of countercurrent periodic extraction (Nash and Hunter), the extraction of the II oil fraction with methylpyrrolidone containing 0.1 wt.% Sulfoxide was carried out. The conditions for extraction were selected taking into account industrial purification. The ratio of solvent to feed ratio is 2.5: 1 by volume. The temperature in the first stage of extraction (bottom of the extraction column) is 51 ° C, the temperature in the second stage of extraction (middle of the extraction column) is 56 ° C, the temperature in the third stage of extraction (top of the extraction column) is 61 ° C. Equilibrium raffinate and extract solutions were selected from the 5th row of countercurrent purification. The results are shown in tables 3, 4, 5.

Example 2. According to a three-stage purification scheme in countercurrent by the method of countercurrently periodic extraction (Nash and Hunter), extraction of the II oil fraction with methylpyrrolidone containing 0.3 wt.% Sulfoxide was carried out. The conditions for extraction were selected taking into account industrial purification. The ratio of solvent to feed ratio is 2.5: 1 by volume. The temperature in the first stage of extraction (bottom of the extraction column) is 51 ° C, the temperature in the second stage of extraction (middle of the extraction column) is 56 ° C, the temperature in the third stage of extraction (top of the extraction column) is 61 ° C. Equilibrium raffinate and extract solutions were selected from the 5th row of countercurrent purification. The results are shown in tables 3, 4, 5.

Example 3. According to a three-stage purification scheme in countercurrent by the method of countercurrent periodic extraction (Nash and Hunter), the extraction of the II oil fraction with methylpyrrolidone containing 0.5 wt.% Sulfoxide was carried out. The conditions for extraction were selected taking into account industrial purification. The ratio of solvent to feed ratio is 2.5: 1 by volume. The temperature in the first stage of extraction (bottom of the extraction column) is 51 ° C, the temperature in the second stage of extraction (middle of the extraction column) is 56 ° C, the temperature in the third stage of extraction (top of the extraction column) is 61 ° C. Equilibrium raffinate and extract solutions were selected from the 5th row of countercurrent purification. The results are shown in tables 3, 4, 5.

Based on the data obtained, it can be seen that with a significant increase in the concentration of petroleum sulfoxides in the solvent, its solvent capacity at a constant temperature regime decreases, which is unacceptable for economic reasons, an increase in the temperature regime or temperature gradient of the process, necessary to improve the quality of the raffinate, is also impractical. With a small concentration of sulfoxides in the solvent, its selectivity increases slightly, which allows, without changing the mode and multiplicity of the solvent, to obtain a larger amount of raffinate (an increase in the yield of the target product is 2.36% for light oil distillates), working on one raw material, with the target quality unchanged product. It was experimentally found that the optimal amount of additive content is a concentration of 0.1%.

Stage 2. The effect of adding sulfoxide to methylpyrrolidone under varying temperature conditions of extraction. When another functional group is added to the polar solvent, which differs chemically and by dipole moment, its selectivity increases as opposed to dissolving, which in turn affects the critical temperature of dissolution, and the greatest increase occurs when the concentration changes from zero to the minimum concentration value (at concentration sulfoxide 0.1% there is an increase in CTE by 5.7 ° C compared with a pure solvent). Accordingly, with a higher KTP value, a higher degree of purification can be achieved, but it is necessary to increase the extraction temperature. But with an increase in the temperature regime of the process, the yield of raffinate will decrease, since the solvent capacity of the solvent increases.

Example 4. According to a three-stage purification scheme, countercurrent extraction using a countercurrent extraction method (Nash and Hunter) carried out the extraction of the II oil fraction with methylpyrrolidone not containing sulfoxide. The conditions for extraction were selected taking into account industrial purification. The ratio of solvent to feed ratio is 2.5: 1 by volume. The temperature in the first stage of extraction (bottom of the extraction column) is 46 ° C, the temperature in the second stage of extraction (middle of the extraction column) is 51 ° C, and the temperature in the third stage of extraction (top of the extraction column) is 56 ° C. Equilibrium raffinate and extract solutions were selected from the 5th row of countercurrent purification. The results are summarized in tables 6, 7, 8.

Example 5. According to a three-stage purification scheme in countercurrent by the method of countercurrent periodic extraction (Nash and Hunter), the extraction of the II oil fraction with methylpyrrolidone containing 0.1 wt.% Sulfoxide was carried out. The conditions for extraction were selected taking into account industrial purification. The ratio of solvent to feed ratio is 2.5: 1 by volume. The temperature in the first stage of extraction (bottom of the extraction column) is 51 ° C, the temperature in the second stage of extraction (middle of the extraction column) is 56 ° C, the temperature in the third stage of extraction (top of the extraction column) is 61 ° C. Equilibrium raffinate and extract solutions were selected from the 5th row of countercurrent purification. The results are summarized in tables 6, 7, 8.

Example 6. According to a three-stage purification scheme in countercurrent by the method of countercurrently periodic extraction (Nash and Hunter), the extraction of the II oil fraction with methylpyrrolidone containing 0.3 wt.% Sulfoxide was carried out. The conditions for extraction were selected taking into account industrial purification. The ratio of solvent to feed ratio is 2.5: 1 by volume. The temperature in the first stage of extraction (bottom of the extraction column) is 52 ° C, the temperature in the second stage of extraction (middle of the extraction column) 57 ° C, the temperature in the third stage of extraction (top of the extraction column) 62 ° C. Equilibrium raffinate and extract solutions were selected from the 5th row of countercurrent purification. The results are summarized in tables 6, 7, 8.

Based on the data obtained, we draw the following conclusions: with an increase in the concentration of sulfoxide in the solvent and a corresponding change in the temperature regime, a significant change in the yield of raffinate occurs with a change in the concentration of sulfoxide from zero to a minimum value (the yield decreases by 1.24%), then the yield of the raffinate changes slightly, and raffinate quality, in contrast, improves almost linearly. The process temperature changes similarly to the yield of the raffinate, increases by 5 ° C with a change in the concentration of sulfoxide from zero to the minimum value, then the temperature increases by 1 ° C. Solubility decreases due to the formation of hydrogen bonds of N-methylpyrrolidone molecules with the oxo group of sulfoxides. The selective ability of the solvent with sulfoxide increases because the hydrogen bonds formed increase the dipole moment and the polarity of the solvent, the dissolution temperatures of hydrocarbon groups also change accordingly, the dissolution temperature of resinous substances and polycyclic aromatic hydrocarbons practically does not change or decreases slightly, and the dissolution temperature of alkanes and naphthenes increases.

Table 1
Quality of petroleum sulfoxide concentrate. The name of indicators Quality indicators Density at 20 ° C, kg / cm ³ 1020 Kinematic viscosity at 50 ° С, mm ² / s 18.9 Pour point, ° C -thirty Sulfur content,% (mass.): - general 11.35 - sulfoxide 10.66 table 2
Characterization of distillate II oil fraction. Refractive Index at 50 ° C Kinematic viscosity at 50 ° С, mm ² / s Melting point, ° С Color on the colorimeter CNT, units CNT Flash point in a closed crucible, ° С 1,4859 8,724 11.5 2.0 161.1 Table 3
Material balances of processes. The amount of sulfoxide in the solvent,% 0 0.1 0.3 0.5 The yield of raffinate,% 50.45 52.81 53.21 53.66 The yield of extract,% 49.26 46.99 46.30 46.18 Loss% 0.29 0.20 0.49 0.16 Table 4
Characterization of the raffinate II oil fraction. The amount of sulfoxide in the solvent,% 0 0.1 0.3 0.5 Refractive Index at 50 ° C 1.4570 1.4570 1.4581 1.4583 Kinematic viscosity at 50 mm ² / s 7,428 7,426 7,430 7,431 Melting point, ° С 17.0 16.9 16.9 16.8 Table 5
Characterization of extracts II oil fraction. The amount of sulfoxide in the solvent,% 0 0.1 0.3 0.5 Refractive Index at 50 ° C 1,5122 1,5122 1,5120 1,5120 Kinematic viscosity at 50 ° C mm ² / s 9,870 9,812 9,790 9,732 Melting point, ° С 3.9 4.7 4.9 5.2 Table 6
Material balances of processes. The amount of sulfoxide in the solvent,% 0 0.1 0.3 The yield of raffinate,% 50.45 49.21 48.63 The yield of extract,% 49.26 50.55 51.19 Loss% 0.29 0.24 0.18

Table 7
Characterization of the raffinate II oil fraction. The amount of sulfoxide in the solvent,% 0 0.1 0.3 Refractive Index at 50 ° C 1.4570 1.4568 1.4565 Kinematic viscosity at 50 mm ² / s 7,428 7,412 7,410 Melting point, ° С 17.0 17.4 17.5 Table 8
Characterization of extracts II oil fraction. The amount of sulfoxide in the solvent,% 0 0.1 0.3 Refractive Index at 50 ° C 1,5122 1,5115 1.5112 Kinematic viscosity at 50 mm ² / s 9,870 9,865 9,864 Melting point, ° С 3.9 4.0 4.2

Stage 3. The effect of adding the extract obtained by purification of the II oil fraction with methylpyrrolidone containing 0.1 wt.% Sulfoxide - during purification of the III oil fraction at a constant temperature extraction mode. The quality of the distillate III of the oil fraction is shown in table 9. The quality of the extract during purification of the II oil fraction is shown in table 10.

Example 7. According to a three-stage purification scheme in countercurrent by the method of countercurrent periodic extraction (Nash and Hunter), the III oil fraction was extracted with methylpyrrolidone containing 0.1 wt.% Sulfoxide. The conditions for extraction were selected taking into account industrial purification. The ratio of solvent to feedstock is 2: 1 by volume. The temperature in the first stage of extraction (bottom of the extraction column) is 65 ° C, the temperature in the second stage of extraction (middle of the extraction column) is 70 ° C, the temperature in the third stage of extraction (top of the extraction column) is 75 ° C. Equilibrium raffinate and extract solutions were selected from the 5th row of countercurrent purification. The results are shown in table 11.

Example 8. According to a three-stage countercurrent purification scheme according to the countercurrent extraction method (Nash and Hunter), the III oil fraction was extracted with methylpyrrolidone containing 0.1 wt.% Sulfoxide. The conditions for extraction were selected taking into account industrial purification. The ratio of solvent to feedstock is 2: 1 by volume. The temperature in the first stage of extraction (bottom of the extraction column) is 65 ° C, the temperature in the second stage of extraction (middle of the extraction column) is 70 ° C, the temperature in the third stage of extraction (top of the extraction column) is 75 ° C. Equilibrium raffinate and extract solutions were selected from the 5th row of countercurrent purification. The concentration of the extract in methylpyrrolidone was 0.5 wt.%. The results are shown in table 11.

Example 9. According to a three-stage purification scheme in countercurrent by the method of countercurrently periodic extraction (Nash and Hunter), the III oil fraction was extracted with methylpyrrolidone containing 0.1 wt.% Sulfoxide. The conditions for extraction were selected taking into account industrial purification. The ratio of solvent to feedstock is 2: 1 by volume. The temperature in the first stage of extraction (bottom of the extraction column) is 65 ° C, the temperature in the second stage of extraction (middle of the extraction column) is 70 ° C, the temperature in the third stage of extraction (top of the extraction column) is 75 ° C. Equilibrium raffinate and extract solutions were selected from the 5th row of countercurrent purification. The concentration of the extract in methylpyrrolidone was 1.5 wt.%. The results are shown in table 11.

Claims (1)

The method of purification of oil fractions by contacting them with N-methylpyrrolidone in an extraction column according to a three-stage purification scheme in countercurrent with the formation of raffinate and extract solutions, characterized in that when cleaning the distillate II with an oil fraction (300-400 ° C), they are preliminarily added to N-methylpyrrolidone petroleum sulfoxide in an amount of 0.1-0.5 wt.% based on the solvent, then when cleaning the distillate of the III oil fraction (350-420 ° C), an extract in the amount of 0.5-1.5 wt is preliminarily added to N-methylpyrrolidone .% received pr II purified distillate oil fraction to a sulfoxide.