RU2802477C2 - Method for in-depth oil processing - Google Patents

Abstract

FIELD: oil refining.

SUBSTANCE: invention relates to a method for advanced oil refining by vacuum distillation of fuel oil and deasphalting. During vacuum distillation of fuel oil in a complex vacuum column, in addition to vacuum distillates, a dark fraction is obtained, it is removed from the strengthening section of the complex vacuum column below the selection of vacuum distillates, the content of paraffin-naphthenic hydrocarbons in the bottom product of the complex vacuum column is ensured to be no more than 10% wt., then the dark fraction is subjected to a deasphalting process with light hydrocarbons to obtain a deasphalted product. The deasphalting oil is used as a feedstock for catalytic processes, and the deasphalting residue is mixed with the bottom product of vacuum distillation and, depending on the oil being processed, unoxidized bitumens or raw materials for producing oxidized bitumens are obtained or used as coking feedstock.

EFFECT: increase in the depth of oil refining, expansion of the raw material base for obtaining high-quality bitumen and obtaining valuable raw materials for coking processes.

4 cl, 9 tbl, 5 ex

Description

The invention relates to oil refining, and specifically to vacuum distillation of fuel oil, deasphalting of heavy petroleum products with light hydrocarbons (propane, n-butane, isobutane), production of petroleum bitumen, raw materials for catalytic processes and coking.

During the atmospheric distillation of oil, along with light (gasoline) and middle distillates (kerosene and diesel fuel), a large amount of heavy residue is obtained (60-40% by weight of crude oil). This residue is subjected to vacuum distillation at elevated temperatures (390-410°C) to obtain vacuum distillates as raw materials for the production of base oils and/or raw materials for deep catalytic processing (catalytic cracking or hydrocracking).

As a rule, the boiling points of isolated distillates are limited to 520°C, since at higher boiling points, significant amounts of nickel and vanadium from organometallic compounds that have a similar boiling point begin to appear (the exception is light oils containing a small amount of organometallics).

Nickel and vanadium are poisons for catalysts for the conversion of heavy hydrocarbons and, as indicated in the method for processing the residue after oil distillation according to patent No. 2337939 (C10C 3/08, op. 11/10/2008, BI No. 31), the content of nickel and vanadium in deasphalted products going to catalytic conversion should preferably not exceed 2 ppm each.

However, with such a limitation of the end of the boiling point of vacuum distillates, a large amount of heavy bottom residue remains (from 30% for heavy oil and up to 15% by weight for light oil). Due to sharply increased requirements for the environmental friendliness of fuels and marine fuels, the consumption of these residues in unprocessed form has sharply decreased and continues to decrease.

Therefore, rational processing of heavy oil residues is an urgent task for the oil refining industry.

A significant number of processes for processing heavy residues have been developed, such as delayed and contact coking (flexicoking), production of petroleum bitumen, hydrocracking of heavy residues in a fluidized (three-phase) bed, catalytic cracking of residual raw materials and combined processes - deasphalting of the residue with hydrocracking (catalytic cracking) of deasphalted oil and coking asphalt or hydrocracking it in a fluidized bed.

The simplest and most inexpensive way is to obtain petroleum bitumen from the residue. It is known to obtain petroleum bitumen by vacuum concentration of fuel oil from a number of unique oils (certain Venezuelan oils, oils from the Yarega and Russian fields of the Russian Federation). However, there are few such oils and extremely expensive logistics make this possibility extremely limited. At the same time, serial oil refineries process oils that make it possible to obtain bitumen of standard quality by oxidizing the vacuum residue with air oxygen at 220-270°C.

But for a number of oils, obtaining petroleum bitumen by oxidation of the vacuum residue is difficult. There are three types of oils from which it is difficult to obtain petroleum bitumen by air oxidation:

- oils containing large amounts of solid paraffin;

- oil of a mixed composition, one part of which, according to the group chemical composition of the vacuum residue, is optimal for producing oxidized petroleum bitumen, and the other has a high paraffin content;

- oils with a low content of resins and asphaltenes.

Sometimes from oils of the first and third types by deep vacuum distillation it is possible to obtain a heavy residue of optimal group composition for oxidation. But in most cases, this leads to the production of a lower distillate with a high content of resins and organometallics (catalyst poison). With oils of the second type it is even more difficult - if we remove solid paraffins by vacuum distillation, we get tar with a low oil content, and if we do not deeply remove fractions containing solid paraffins, then the residue contains them in excess and the bitumen also turns out to be of low quality.

The method for producing road bitumen according to patent No. 2142493 (C10C 3/08, op. 12/10/1999) proposes a method for producing road bitumen by deasphalting tar with hydrocarbon solvents followed by mixing deasphalting asphalt with petroleum diluents, deasphalting is carried out in such a way that in the resulting bitumen, the content of paraffin-naphthenic hydrocarbons did not exceed 10-11%, and the mass ratio of asphaltenes and saturated hydrocarbons was 1.4-1.7.

In example 1 of this patent, asphalt is obtained from Arlan oil tar by deasphalting with a propane-butane mixture with a yield of 40.8% for raw materials with a softening point of 72°C, and in example 3 the resulting asphalt is mixed with an extract for the selective purification of residual oils in a ratio of 81:19 mass. This produces straight-run road bitumen of high quality. However, the quality of the resulting deasphalted oil, which constitutes 59.2% by weight of the original tar, was not studied.

Reproduction of the experiment in example 1 and analysis of the resulting deasphalted oil showed that its coking capacity according to Conradson is 3.9%, nickel content is 8 ppm, vanadium is 14 ppm. These indicators are not optimal, as shown in patent No. 2337939 for further processing of deasphalted oil in catalytic processes.

A study of the deasphalted product obtained from West Siberian oil tar (Conradson coking capacity 12.4%) in example 4, where the yield of asphalt was 24.8%, and the deasphalted product was 75.2% by weight, showed that the deasphalted product contained 6 ppm nickel and 8 ppm vanadium.

Despite all the attractiveness of the method for producing petroleum bitumen proposed in patent No. 2142493, large quantities of deasphalted oil with a relatively high content of nickel 6-8 ppm and vanadium 8-14 ppm and the associated difficulties with its processing did not allow the implementation of this method and since 2020 the patent is no longer valid.

The search for possible ways to obtain high-quality petroleum bitumen using the deasphalting process to remove excess amounts of paraffin-naphthenic hydrocarbons from the residue led to the analysis of the method of fuel oil fractionation according to patent No. 2205856 (C10G 7/06, op. 06/10/2003, BI No. 16), which provides for fuel oil fractionation distillation of heated raw materials in a complex vacuum column equipped with strengthening, stripping, stripping sections, contact devices, with the removal of side streams and stripping of light fractions from them in stripping sections, with the selection of light, medium, heavy distillate fractions and residue, with the removal of the light distillate fraction the upper side rung of the column, cooling part of it and feeding it to the top of the column as circulation irrigation, with the selection of the strengthening section of the darkened fraction from the lower plate.

The purpose of the invention according to patent No. 2205856 states that the invention is aimed at increasing the productivity of the column, selecting target products, as well as improving the quality of distillate fractions.

An analysis of Table 1 of this patent shows that when distilling 65 t/h of fuel oil, 9.4 t/h of the dark fraction (520-600°C) and 5.4 t/h of the fraction above 520°C (residue) are obtained. At the same time, the authors focused their attention on the productivity of the column and the yield of target fractions (n.c. - 340°C, 340-370°C, 370-450°C, 450-520°C) and the minimum residue and dark fraction.

An analysis of the operation of vacuum columns showed that many of them are equipped with the removal of the darkened fraction, however, the lack of its intended use has led to the fact that this section is used as a washing section from resins and asphaltenes rising with vapors in the form of spray and minimal removal of the darkened fraction from its possible potential.

For an in-depth analysis of the residue and dark fraction, the vacuum distillation process specified in example 2 given in patent No. 2205856 was reproduced, while processing 57 tons per hour of West Siberian oil fuel oil at an inlet temperature of the vacuum column of 392 ° C and a residual pressure at the top of the column 23 mmHg. a dark fraction of 8.3 t/hour and a bottom residue of 4.7 t/hour were obtained.

The objective of the proposed invention is to increase the depth of oil refining, expand the raw material base for obtaining high-quality bitumen and obtain valuable raw materials for coking processes.

The technical result consists in obtaining, at the stage of vacuum distillation of fuel oil, a residue as a component of raw materials for the production of petroleum bitumen and a dark fraction, which is subjected to a deasphalting process to produce deasphalted oil with a low content of nickel and vanadium as a raw material for catalytic processes and asphalt as a component of raw materials for the production of petroleum bitumen.

The technical result is achieved by the fact that in the method of advanced oil refining by vacuum distillation of fuel oil and deasphalting, during vacuum distillation in a complex vacuum column, in addition to vacuum distillates, a darkened fraction is obtained, removed from the strengthening section of the complex vacuum column below the selection of vacuum distillates, ensuring the content of paraffin-naphthenic hydrocarbons in the bottom product of a complex vacuum column are no more than 10% by weight, then the darkened fraction is subjected to the process of deasphalting with light hydrocarbons to obtain deasphalting oil, the deasphalting oil is used as a raw material for catalytic processes, and the deasphalting residue is mixed with the bottom residue of vacuum distillation and, at the same time, depending on processed oil, obtain unoxidized bitumen or raw materials for the production of oxidized bitumen.

It is advisable to obtain deasphalted oil with a nickel and vanadium content below 1 ppm each.

It is advisable for the bulk of the dark fraction to boil to 570-610°C, while when distilling fuel oil containing a large amount of resins, it is closer to 570°C, and fuel oil containing a smaller amount of resin is closer to 610°C.

Instead of producing bitumen, the bottom residue from vacuum distillation and the residue from deasphalting the dark fraction can be used as coking raw material, preferably flexicoking.

The method is carried out as follows.

Heated fuel oil is introduced between the strengthening and stripping sections of a complex vacuum column. Non-condensable gases and vapors are removed from the top of the column to a vacuum-creating system. Distillate fractions are removed from the middle part of the strengthening section of a complex vacuum column. From the bottom of the strengthening section of a complex vacuum column, below the selection of vacuum distillates, a darkened fraction is removed. Water vapor may be supplied to the bottom of the stripping section of a complex vacuum column. The residue is removed from the bottom of a complex vacuum column. The temperature of the raw material input into the complex vacuum column and the temperature on the dark fraction selection plate are adjusted to regulate the volume of the dark fraction removed in order to ensure that the content of paraffin-naphthenic hydrocarbons in the residue (bottom product of the complex vacuum column) is no more than 10% by weight. The darkened fraction is subjected to a deasphalting process at high pressure with liquefied light hydrocarbons (C ₃ , C ₄ ) as a solvent. During the deasphalting process, the darkened fraction is separated into two products - deasphalted product and residue. To ensure the required quality of products, the temperature of the deasphalting process, the composition of the solvent and its ratio to the raw material (darkened fraction) are changed depending on the group chemical composition of the darkened fraction. The bulk of the dark fraction boils to 570-610°C, while during the distillation of fuel oil containing a large amount of resins, it is closer to 570°C, and fuel oil containing a smaller amount of resins is closer to 610°C. The deasphalted oil obtained from the darkened fraction is fed to catalytic processing processes as a raw material. The deasphalting residue is mixed with the bottoms of the vacuum distillation process and, depending on the type of oil being processed, unoxidized bitumen is obtained after mixing or supplied to the bitumen plant as a raw material for the production of oxidized bitumen. In the absence of a need for bitumen, the vacuum residue and its mixture with the residue from deasphalting are the raw materials for the coking process, while the uniquely low content of paraffin-naphthenic hydrocarbons and high aromatic hydrocarbons suggest that medium and heavy coke distillates will be highly aromatized and are a good raw material for the production of carbon black (soot).

The proposed method is illustrated by the following data.

Tar obtained from West Siberian oil without removing the dark fraction, the dark fraction and the bottom residue were examined for group chemical composition, coking ability and metal content. The data are shown in Table 1. The resulting darkened fraction was subjected to deasphalting in example 1 with a yield of 81 wt% and in example 2 with a yield of 72 wt%. The results obtained are shown in Table 2. As a result, instead of 100% of the mass of standard West Siberian oil tar, the following was obtained:

- deasphalted fraction of the darkened fraction (8.3×81) / (8.3+4.7)=51.7% wt.

- bottom residue 4.7 / (8.3+4.7) = 36.1% wt.

- residue from deasphalting of the darkened fraction (8.3×19) / (8.3+4.7) = 12.2% wt.

And in the second case, example 2, it was obtained:

- deasphalted fraction of the darkened fraction (8.3×72) / (8.3+4.7) = 46.0% wt.

- bottom residue 4.7 / (8.3+4.7) = 36.1% wt.

- residue from deasphalting the darkened fraction (8.3×28) / (8.3+4.7) = 17.9% wt.

The vacuum residue and the residue from deasphalting the darkened fraction from examples 1 and 2 were mixed and the resulting mixture was studied, the results are shown in Table 3. The mixing products are high-quality non-oxidized bitumens. When compared with analogs according to patent RU 2142493, they contain less paraffin-naphthenic hydrocarbons (5.8-6.3 wt. instead of 9.1-11.0% wt. with equal asphaltenes content 15.2% versus 15.5-16 .6 wt.% No extraneous diluent (selective oil purification extract or cracking residue) is required.

Under the same conditions, vacuum distillation of Arlan oil fuel oil was carried out and studies of standard Arlan oil tar, dark fraction and bottom residue were carried out. The data obtained are summarized in table 4. The darkened fraction was subjected to deasphalting under the conditions of example 3 and the resulting products were analyzed, the analysis data are given in table 5. In addition, the darkened fraction obtained during the study of Arlan oil was subjected to vacuum distillation and it was found that the end of the boiling point of the darkened fraction of Arlan oil is 583°C - 17°C lower than the analogue obtained from West Siberian oil. This is due to the fact that Arlan oil is heavier, more resinous, contains more asphaltenes and sulfur and, as a result, is more difficult to accelerate. The vacuum distillation residue was mixed with the deasphalting residue of the darkened fraction and the mixture was examined. The results of the study are shown in Table 6. It was possible to obtain unoxidized bitumen, which in terms of its group chemical composition turned out to be close to the bitumen obtained according to patent RU 2142493 from Arlan oil, however, the deasphalted product had a low nickel and vanadium content, making it a valuable raw material for further catalytic processing .

The results for obtaining the darkened fraction and vacuum residue were obtained in the autumn-winter period, when the residual pressure at the top of the vacuum column could be kept no higher than 25 mm Hg. Art. However, for example, the operating experience of the AVT-3 installation at the Turkmenbashi Oil Refinery (Turkmenistan), equipped with a bromine-lithium refrigeration machine on a vacuum-creating equipment unit and providing a residual pressure of the top of the vacuum column of 20-22 mm Hg. even at an ambient temperature of +35°C, these results will be achieved year-round.

Additionally, the possibilities of producing bitumen from low-sulfur oils such as light West Siberian oil were investigated. An industrial sample of tar from the Yaya Oil Refinery was studied (the results of the analysis are shown in Table 7). Due to the extremely low asphaltene content, it is impossible to obtain bitumen from this type of raw material.

Vacuum distillation of this tar was carried out in a pilot plant with a resolution of 2 theoretical stages at high vacuum (residual pressure 12 mmHg and column bottom temperature 405°C). 71% of the distillate mass and 29% of the bottom residue were obtained. The performed analyzes are summarized in Table 8. Then, deasphalting of the darkened fraction was carried out under the conditions of example 4. The results of the analyzes are shown in Table 9.

The vacuum distillation residue, containing 7.1% asphaltenes, was subjected to oxidation with atmospheric oxygen in a laboratory installation, which was a round-bottomed three-neck flask with a volume of 2 dm ³ mounted on a heating mantle. Two tubes with a drawn-out end were inserted into the two necks of the flask to introduce air. A thermometer and a stirrer were placed in the third neck of the flask. The remainder of the distillation was placed in the flask and the temperature was raised to the required temperature with the stirrer and heating mantle turned on. The temperature was maintained within ±2°С. The air flow was maintained at a volume of 5 dm ³ /min (or 0.25 m ³ /kg of oxidized raw material). Samples were periodically taken for the softening temperature of the oxidized product, determined by the “Ring and Ball” method (using the R&I method). At the same time, it was possible to obtain petroleum bitumen with a softening point using the KiSh method of 46°C, penetration at 25°C (needle penetration depth) of 89⋅10 ^-1 mm and ductility at 25°C of more than 100 cm. The residue from deasphalting was not used for mixing, so how the asphaltene content in the bottom product did not allow it to be diluted before oxidation. It should be noted that in cases where there is no need for petroleum bitumen, heavy bottoms can be processed by coking processes. At the same time, the unique ratio of paraffin-naphthenic and aromatic hydrocarbons will make it possible to obtain highly aromatized middle and heavy distillates, which are high-quality raw materials for the production of carbon black and do not require expensive hydroprocessing.

It should be noted that given that the residue does not contain low-boiling fractions, its processing by delayed coking will require increased recirculation coefficients in order to avoid coking of the chimney pipes. At the same time, the contact coking process (flexicoking) does not have strict requirements for heating the raw materials, since the bulk of the heat is introduced with the carrier and can be recommended as preferable.

The proposed method is illustrated by the following examples 1-5.

Example 1. The dark fraction obtained from the distillation of fuel oil was subjected to deasphalting in a pilot plant with 600 g of raw material. N-butane served as a solvent. Process temperature 85°C. The volume ratio of solvent: raw material is 6:1. The deasphalted product yield was 81 wt%. The quality of the deasphalting product and the deasphalting residue of the dark fraction are given in Table 2.

Example 2. The experiment was carried out similarly to example 1, with the solvent being a mixture of propane and n-butane with a propane content of 25 wt%. The yield of deasphalted product was 72% wt. The quality of the deasphalting product and the deasphalting residue of the dark fraction is given in Table 2.

Example 3. The darkened fraction of Arlan oil was subjected to deasphalting similar to example 1. The process temperature was 80°C, and the solvent was n-butane. The quality of the obtained deasphalting oil and the deasphalting residue is shown in Table 5. The yield of deasphalting oil was 80.2 wt%.

Example 4. The darkened fraction of light West Siberian oil was subjected to deasphalting similar to example 1. The process temperature was 78°C, the solvent was n-butane. A deasphalted product yield of 89 wt.% was obtained. The quality of deasphalting product and deasphalting residue is given in Table 9.

Example 5. Bottom residue from the distillation of light West Siberian oil, obtained with maximum recovery of the dark fraction

oxidized in a 2 dm ³ flask with an air supply of 5 dm ³ /min (0.25 m ³ /kg of raw material). At the same time, the temperature stabilized ±2°C and samples were periodically taken for analysis to determine the softening temperature of the oxidized product, determined by the K&I method. At an oxidation temperature of 260°C, it was possible to obtain road bitumen with a softening point according to the KiSh method of 47°C, penetration at 25°C - 89⋅10 ^-1 mm and ductility at 25°C more than 100 cm.

The results of examples and analyzes of the resulting intermediates and their mixtures in Tables 1-9 fully reveal the originality and high inventive level of the proposed method for advanced oil refining.

The proposed method is distinguished, along with its simplicity and efficiency, by the ability to adjust the process parameters depending on the oil being processed.

In the first case, adjustment is possible at the stage of vacuum distillation by changing the output of the dark fraction, also adjusting the temperature of the input of raw materials into a complex vacuum column and the temperature at the dark fraction selection plate.

In the second case, at the stage of deasphalting the darkened fraction, changing the yield of deasphalted product by changing the process temperature, the composition of the solvent and its ratio to the darkened fraction, depending on the group chemical composition of the darkened fraction.

Thirdly, you can change the mixture ratio of the bottom of the vacuum distillation - the residue from the deasphalting process of the darkened fraction, achieving the optimal ratio.

The method makes it possible to additionally obtain a significant amount of deasphalting product with a low content of nickel and vanadium, which is unattainable during traditional deasphalting processes with light hydrocarbons (C ₃ , C ₄ ).

The method expands the possibilities of obtaining high-quality bitumen from oils, from which previously it was difficult to obtain bitumen, and in some cases impossible.

The method makes it possible to obtain raw materials for coking processes with a low content of paraffin-naphthenic hydrocarbons and a high content of aromatic hydrocarbons, which suggests that medium and heavy distillates will have a high content of aromatic hydrocarbons and will be a good raw material for the production of carbon black (soot).

Claims (4)

1. A method of advanced oil refining by vacuum distillation of fuel oil and deasphalting, during vacuum distillation of fuel oil in a complex vacuum column, in addition to vacuum distillates, a dark fraction is obtained, removed from the strengthening section of the complex vacuum column below the selection of vacuum distillates, ensuring the content of paraffin-naphthenic hydrocarbons in the bottom product complex vacuum column no more than 10% wt., then the darkened fraction is subjected to the process of deasphalting with light hydrocarbons to obtain deasphalting product, the deasphalting product is used as a raw material for catalytic processes, and the deasphalting residue is mixed with the bottom product of vacuum distillation and, depending on the oil being processed, is obtained unoxidized bitumens or raw materials for the production of oxidized bitumens or used as coking raw materials. 2. The method of advanced oil refining according to claim 1, in which a deasphalted product is obtained with a nickel and vanadium content below 1 ppm each. 3. The method of advanced oil refining according to claim 1, in which the bulk of the dark fraction boils to 570-610°C, while during the distillation of fuel oil containing a large amount of resins, it is closer to 570°C, and fuel oil containing a smaller amount of resins, closer to 610°C. 4. Method of advanced oil refining according to paragraphs. 1-3, in which, instead of producing bitumen, the bottom product of vacuum distillation and the residue from the deasphalting of the dark fraction are used as coking raw materials, preferably flexicoking.