CS252661B1 - A method of treating sulfur-containing crude oil - Google Patents

Abstract

Sulfur-containing crude oil treatment process first by distillation at atmospheric pressure and by hydrogenation catalytic refining, followed by vacuum distillation of the atmospheric residue and subsequent hydrocracking and distillation processing of the hydrogenated product, wherein a larger amount of light fuel fraction is separated from the crude oil by atmospheric distillation oil and a portion of the hydrogenate and recycled to atmospheric distillation and part of the hydrocracking production returns to vacuum distillation. Light fuel oil and other sulfur-containing fuel oil components are obtained.

Description

The invention relates to the processing of crude oil containing sulfur compounds by desulfurization of primary oil fractions obtained by atmospheric distillation of crude oil and vacuum distillation of the atmospheric residue.

It solves the complex use of operational and qualitative reserves in the refining practice of crude oil processing, which arise mainly from the processing of crude oil of variable quality and the temporary non-use of refinery capacities. The process according to the invention can be used to achieve desulfurization of medium-sulfur petroleum oil distillates, boiling in the range of 300 to 460 ° C, which in the current state of processing represent mainly a component of high-sulfur heavy fuel oils. At the same time, the method according to the invention does not require the single-purpose use of hydrofinancier capacities for desulfurization of oil fractions.

The usual technology for processing medium-sulfur crude oils usually includes atmospheric vacuum distillation of crude oil in order to obtain atmospheric gas oil products, which are hydrotreated, and medium-sulfur fractions of light fuel oil, which are usually obtained in the amount of 1 to 6% by weight per crude oil. Obtaining a fraction of light fuel oil with a higher yield of crude oil at the expense of reducing the yield of the atmospheric residue is not suitable because there is an increased transition of asphaltic-resinous substances containing trace metals, in addition to sulfur compounds, especially vanadium and nickel, to the light fuel oil fraction and also because there is an unacceptable increase in the freezing point of light fuel oil due to the content of fractions boiling in the range of 400 to 500 °C.

In practice, the method of obtaining uncontaminated higher-boiling fractions by vacuum distillation of the atmospheric residue, which can be hydrodesulfurized in a dedicated operating facility, is therefore chosen. This method of processing sulfur raw materials is therefore very demanding on the processing desulfurization capacity.

These shortcomings are solved by the method of processing crude oil containing sulfur compounds according to the invention, first by distillation separation at atmospheric pressure and hydrogenation catalytic refining of middle distillates with the addition of hydrogen-containing gas, whereby in addition to light fractions including the kerosene fraction, light fuel oil with a reduced sulfur content of 5 to 80% and hydrogenated gas oil are obtained, and further, by vacuum distillation of the atmospheric residue with subsequent catalytic hydrocracking of the middle fractions and distillation processing of the hydrocracking product, whereby an oil hydrogenate for the production of lubricating oils with a reduced sulfur content is obtained.

The principle of this method consists in that the fraction of light fuel oil 5, 11. boiling in the distillation range with the beginning of the boiling point of 220 to 360 °C and the end of the boiling point of 370 to 460 °C, which are produced in an amount of 1 to 15 wt. % per crude oil injection depending on the composition of the crude oil, in a mixture with the fraction of gas oil 4_ boiling in the range of 18% to 390 °C in a volume ratio of 1:1 to 1:20, is hydrotreated D and a part of the hydrotreated product 8 in a volume ratio to the total hydrotreated product of 1:1 to 1:20 is recycled to atmospheric distillation.

A and the middle oil fraction of vacuum distillation B in a mixture 13 with light oil fraction 16 in a volume ratio of 1:1 to 20:1 are subjected to hydrocracking E, with a portion of the hydrocracked product 17 in a volume ratio to the total hydrocracking product of 1:1 to 1:50 being recycled to vacuum distillation B. A portion of the hydrotreated product 2 is recycled to atmospheric distillation A either directly to the crude oil injection 2» or to the gas oil reflux 22.

The method according to the invention is schematically illustrated in the attached drawing, Fig. 1, where Part I. shows the processing of crude oil by atmospheric distillation and hydrorefining, Part II. shows the processing of the atmospheric residue by vacuum distillation and hydrocracking.

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According to the process of the invention (see scheme I in Fig. 1), a fraction of atmospheric light fuel oil, or a mixture of atmospheric and vacuum light fuel oil, with a yield of 1 to 15% by weight of crude oil, boiling in the distillation range with an initial boiling point of 220 to 360 °C and an end boiling point of 370 to 460 °C, obtained after adjusting the distillation regime of atmospheric distillation A, respectively. vacuum distillation B, leads through pipes 2 ^and 24 in a mixture with gas oil £ by injection 2 to the hydrorefining reactor D in a volume ratio of 1:1 to 1:20 to the amount of gas oil 4_, boiling usually in the range with the beginning of the boiling point of 180 to 300 °C and the end of the boiling point of 320 to 390 °C, which goes through pipe 2 ^{and in} a mixture with the light fuel oil fraction through pipe Ί_ to the inlet of reactor D, in which pellets or extrudates containing cobalt or nickel and molybdenum sulfides on a carrier formed mainly of a refractory metal oxide, especially aluminum, are stored as catalysts, together with a gas containing hydrogen in a volume ratio of raw material to gas of 1:50 to 800, at temperatures on the catalysts in the range of 390 to 420 °C with a volume velocity of 0.5 to 6 volumes of raw material per volume of catalyst per hour, at a pressure of 2.5 up to 6.0 MPa.

After separation of the gas phase, the resulting liquid product is fed through a return circuit in a volume ratio of 1:1 to 1:20, based on the outlet stream 2 ² of reactor D, back to atmospheric distillation column A through line 2 ^and preferably through line 22 via the 2nd reflux circuit or to the crude oil injection into line 2. ^After reaching equilibrium conditions between the hydrotreating unit p and column A, 5 to 80% desulfurization of the light fuel oil fraction is achieved, with a slightly deteriorated quality of the hydrogenated gas oil p, which can usually be influenced either by adjusting the catalytic and technological conditions in the hydrogenation reactor D, or in the extreme case by redistillation of the hydrogenate.

Part II of Fig. 1 shows the current technological scheme for processing atmospheric residue by vacuum distillation into the products vacuum oil 11, light 12, medium, heavy 14 oil fraction and vacuum residue 15, with pipes 16 and 17 closed.

One of the main raw materials for the production of lubricating oils are oil hydrogenates, obtained under mild hydrocracking conditions by treating medium vacuum distillates, which usually have a distillation range of 450 to 500 °C, in the reactor of the hydrocracking unit E. Usually, due to the blurring of the operating distillation cuts due to low efficiency, the beginnings and ends of the distillation ranges of individual cuts overlap, which is disadvantageous from the point of view of the production of oil hydrogenates. In connection with the process according to the invention, shown in Scheme 2' ^ ^to limit these unfavorable aspects and to use the improved conditions for the production of process hydrogenates in parallel to obtain partially desulfurized light and medium vacuum distillates.

Based on procedure II, it is possible to achieve a lower proportion of oil fractions in the distillation range of 360 to 440 °C, which creates the prerequisites for a more advantageous arrangement of the connection between the hydrocracking unit E and the vacuum column B, which includes: mixing the light oil fraction in a volume ratio of 1:1 to 1:30 through the pipe 16 into the feed 12 consisting of the medium oil fraction, to the hydrocracking unit E, in which it is advantageous to narrow the fractional range in the lower part of the section.

In the reactor of the hydrocracking unit E, pellets or extrudates containing tungsten, nickel or molybdenum sulfides on a carrier consisting mainly of aluminum oxide or aluminosilicates with the addition of an acidic component are usually stored as catalysts. A hydrogen-containing gas is fed into the reactor in a volume ratio of raw material to gas of 1:500 to 1:2000 at catalyst temperatures of 380 to 430 °C and a volume velocity of 0.3 to 3 volumes of fraction per volume of catalyst per hour, at a pressure of 10 to 300 MPa.

The resulting reaction product, after separation of gas and water, is partly returned in a volume ratio to the total reaction product of 1:1 to 1:50 through line 17 and 2. reflux circuit 23 after separation of lighter fractions in vacuum column B to injection line 13. The remaining reaction product is then fed in the usual manner to atmospheric distillation C to obtain overhead distillate 21, side draw 20 and distillate residue, the so-called oil hydrogenate 19.

The main features and benefits of the invention resulting from the above arrangement are: improvement of the separation efficiency of the atmospheric distillation column and prevention of the transition of asphaltene-resinous substances and higher-boiling fractions in the fractional range of 430 to 490 °C to the light fuel oil fraction, as a result of which there will be a slight decrease in the sulfur content in the light fuel oil; compensation of the consequences of the higher volume velocity of the hydrotreating units p and E by the effect of recycling the hydrogenation product into the feed to maintain the quality of the reaction products 9 (hydrogenated gas oil) and 19 (oil hydrogenate); the light fuel oil fraction 10 is preceded in column A by hydrodesulfurized fractions boiling in the temperature range of 300 to 430 °C, thereby obtaining a light fuel oil distillate with a reduced sulfur content of 5 to 80%; a narrower atmospheric residue is obtained, meaning an intensification of the column penetration in the area of medium and heavy oil vacuum fractions by 5 to 25 í; in column B, hydrodesulfurized fractions boiling in the temperature range of 200 to 460 products 11 and 12 by 5 to 50 % pass into the vacuum light fuel oil fraction 11 and light oil fraction 12.

^J C, thereby reducing the sulfur content in distillation

Example

In a refinery with a capacity of 3 million tons of oil/year, West Siberian crude oil is processed into the following petroleum products, which, with the exception of hydrogenated gas oil, differ in yield and properties from the characteristics of petroleum products obtained by the process according to the invention:

Oil recovery/% wt. according to the invention current! status hydrogenated gas oil 15.0 15.1 atmospheric LTO 7.1 2.3 atmospheric residue 43.3 46.6 injection of atmospheric residue into vacuum column B 23.3 23.3 vacuum LTO 0.3 1.8

Characteristics of atmospheric LTO according to the invention current situation distillation test according to ASTM D-1160 °C °C Start of distillation °C 301 248 10% vol. 328 346 50% vol. 368 402 95% vol. 396 448 End of distillation °C 402 457 Physical-chemical properties; yield (% wt. on oil) 7.7 2.3 density (kg/ ^m3 ) 878 896 freezing point °C +7 +23 sulfur content (% wt.) 1.1 1.8 trace metal content (V + Ni) ppm 0.2 1.1 Potential content distribution (% by weight) shares in oil, boiling within the true range boiling points 350 to 400 °C, into petroleum products:

according to the invention current situation Hydrotreatment product 9 2.45 2.36 Light heating oil 2 4.48 0.89 Atmospheric residue 6a 1.60 3.20 Light vacuum fuel oil 11 0.27 1.62 Unsweetened light oil fraction 12 0.80 /1.58 Oil 9.60 9.60

Due to the possible penetration of high-boiling oil fractions into reactor D in the start-up phase of the process according to the invention, a mixture of vacuum light fuel oil (LTO) with a distillation range of 300 to 400 °C and gas oil in a volume ratio of 1:2 was prepared in a tank, which was sprayed onto hydrogenation reactor D, in which a cobalt-molybdenum catalyst on gamma alumina in 5x5 mm tablets is stored, under the following conditions of the process according to the invention:

according to the invention current state temperature (°C) pressure (MPa) space velocity (h ⁴ ) gas to raw material ratio (N 1/1) Hj in gas (% vol.)

362

2.95

3.3

450

366

2.95

2.5

450 part of the resulting hydrogenated product 2 ^with P° separation of the gas phase was led through the reflux circuit in a volume ratio of 1:2.0 to the outlet stream 9 of the reactor D via the 2nd reflux circuit 22 to the distillation column A. At the same time, the distillation mode of column A was adjusted to the parameters enabling the above-mentioned yield of products according to the method of the invention to be achieved and the auxiliary injection mixture was replaced with the raw material obtained by mixing the light fuel oil fraction and gas oil, via the pipes j5- ^and A of column A in a volume ratio of 1. 1/2.1.

The yield and properties of the obtained products according to the invention were evaluated after the equilibrium conditions in the recycle between column A and reactor D had been established.

The above mixing ratios at pipeline nodes 8 and 24 ^were chosen so as to maintain the quality parameters of the hydrogenated gas oil of the current quality:

Distillation test according to ASTM D-86 °C according to the invention current situation Beginning of distillation 245 258 10% vol. 272 283 50% vol. 324 309 95% vol. 368 368 End of distillation 370 370 Physicochemical properties: yield (% wt. on oil) 15.0 15.1 density (kg/ ^m3 ) 853 856 freezing point (°C) -1 -1 sulfur content (% wt.) 0.12 0.12

The above example allows us to assess the degree of achievement of the effects of the invention according to procedure 1 in Fig. 1: ‘

-improvement of the separation efficiency of column A due to a more optimal fractional composition of crude oil and achievement of a higher natural internal reflux in column A in the fractional region of gas oil 2 ^and atmospheric light fuel oil 2. Improvement of the qualitative indicators of the mixed streams A ^and its injection T_ of reactor D then limits the mixing ratios in the hydrogenation recycle 2» 24 to achieve the desired quality of the hydrogenation product 2.

-Increased yield of light fuel oil from crude oil: after the recycle between reactor D and column A is started, the auxiliary vacuum light fuel oil cut almost disappears and an analogous cut with a reduced content of trace metals V and Ni is obtained in addition in the atmospheric distillation process of crude oil.

-Rational use of existing distillation and hydrogenation capacity for the preparation of light fuel oil with reduced sulfur content and other improved quality parameters.

Example 2

The refinery processes 1.5 million tons/year of atmospheric distillation residue into the following petroleum products, differing, with the exception of oil hydrogenates, from the characteristics of petroleum vacuum distillation products obtained by the process according to the invention:

according to the invention current situation 4 oil yield % wt. sulfur content % wt. oil yield % wt. sulfur content % wt. vacuum LTO (11) 1.27 0.64 1.8 1.50 light oil. fr. (12) 4.65 1.55 5.22 2.05 heavy oil. fr. (14) 1.52 - 1.48 - vac. rest gr. 80 p. u. (15) 11.58 - ' 10.60 - rest of column C (19) 2.55 0.03 2.52 0.03 column C overhead (21) 0.46 0.02 0.46 0.02 side exhaust of column C (20) 1.07 0.03 1.02 0.03 hydrogen off-gas and losses 0.2 - 0.2 -

The atmospheric residue obtained by the procedure given in Example 1 was partly processed according to procedure II in Fig. 1 while maintaining the existing throughput of vacuum column B. The obtained vacuum light oil fraction in the distillation range of 390 to 460 °C was mixed in a volume ratio of 1:3 through line 16 with the injection of the middle oil fraction in the distillation range of 460 to 530 °C, coming from vacuum column B to inlet 13 of reactor E, in which 5x5 mm catalyst tablets containing tungsten and nickel on a carrier formed by aluminosilicate with the addition of an acidic fluorine component, together with hydrogen gas, are placed under the following hydrocracking conditions:

according to the invention current situation temperature (°C) 400 402 pressure (MPa) 20 20 volume velocity (h ^_3 ) 0.99 0.79 gas to raw material (N 1/1) 1,000 1,000 H ₂ in gas (% vol.) 87 87

The resulting reaction product, after separation of gas and water, is returned in a volume ratio of 1:3 to the total reaction product through pipe 17 and reflux circuit 23 after separation of the fractions up to 460 °C in a vacuum column to feed 13 of reactor E, in which a more optimal fractional composition occurred, especially in the upper half of the section, as follows from the following data:

Distillation test according to ASTM D-1160% vol. according to the invention °C current status °C 5 378 382 10 393 427 30 465 453 50 482 471 80 495 500 90 515 527 95 525 533 end of distillation 529 548

The remaining reaction product is processed in the atmospheric column C in the usual manner to produce overhead distillate 21, overhead draw-off 20 and oil hydrogenate 19.

The above mixing ratios at pipeline nodes 18 and 16 were chosen so as to maintain the quality parameters of the oil hydrogenate 19, of the existing quality.

Properties of oil hydrogenate 19.

according to the invention current situation specific gravity 20 °C (kg/m^) 923 929 viscosity 100 °C (mm^/s) 11.2 12.1 residue above 390 °C (% wt.) 58.0 64.6 Sample after dewaxing: Vi-index 90 90 viscosity 100 °C 6.7 6.8

The above example allows us to assess the achievement of the effect of the invention according to procedure II in Fig. 1:

- 25% desulfurization of the light oil fraction 12 is achieved 56% desulfurization of the vacuum light fuel oil 11, which contains light components of the hydrocracked vacuum fraction 3 ^{It is} advantageous to use this product for the production of diesel fuels by mixing it into the feed T_ of the reactor D according to procedure I, Fig. 1

- higher yields of potential middle oil distillates from crude oil due to improved efficiency of column B, which allows expanding the feedstock base for hydrocracking processes.

The examples given only document the effects of the invention without regard to the quality standardized parameters of the output petroleum products.

Claims (2)

OBJECT OF THE INVENTION « Process for the treatment of sulfur-containing crude oil by first distillation at atmospheric pressure and hydrotreating catalytic raffinates of middle distillates with the addition of hydrogen-containing gas, wherein in addition to light petroleum fractions a light fuel oil having a reduced sulfur content of 5 to 80 S and hydrogenated gas oil and vacuum distillation of the atmospheric residue followed by catalytic hydrocracking of the middle fractions and distillation treatment of the hydrocracking products to obtain an oil hydrogenate for the production of lubricating oils and a component for producing fuel oils with reduced sulfur content, characterized in that the light fuel oil fraction , boiling in the distillation range with a boiling point of 270 to 360 ° C and a boiling point of 370 to 460 ° C, which are produced in an amount of 1 to 15 wt. for the oil feed, depending on the composition of the oil, in a mixture with a gas oil fraction boiling in the range of 180 to 390 ° C in a ratio of 1: 1 to 1:20 by volume hydrotreating and a part of the hydrotreated product in a volume ratio of total 1: 1 to 1 1:20 is recycled to atmospheric distillation, and the middle oil fraction of the vacuum distillation in a 1: 1 to 1:20 by volume light oil fraction is subjected to hydrocracking, wherein a portion of the hydrocracking product is by volume relative to the total hydrocracking product 1: 1 to 1:50 is recycled to vacuum distillation. 2. The process of claim 1 wherein the hydrotreated product is recycled to atmospheric distillation either directly into the oil feed or to the reflux of the gas oil. 1 drawing i