RU2394875C2 - PROCEDURE FOR PRELIMINARY PURIFICATION OF CRUDE FOR PRODUCTION OF AT LEAST TWO KINDS OF OIL Pa, Pb NOT CONTAINING PYROBITUMEN AND ONE KIND OF OIL Pc CONTAINING PYROBITUMEN - Google Patents

Abstract

FIELD: gas-and-oil industry. ^ SUBSTANCE: invention refers to oil industry. The invention particularly refers to the procedure of preliminary purification of at least one crude P. According to the procedure this crude P is divided for several fractions. Produced out of crude P column effluents, not containing pyrobitumen, possibly subjected to hydro-purification and/or hydro-conversion, and/or hydro-cracking, are separated into three elementary flows a, b, c. Further, flows a produced out of different column effluents on different installations are mixed with flows b produced out of different column effluents on different installations to obtain at least two kinds of oil - Pa and Pb not containing pyrobitumen. Successively, there is produced one residual oil Pc containing major part of at least residual pyrobitumen. Also kinds of oil Pa and Pb produced on base of crude P have different ratios E determined from formula: E=(0.9 N+0.5 VGO+)/(MD+0.1 VGO+), where: N=naphta: percent contents by weight of the fraction, boiling at temperature within the range from 30C to 170C; MD=average distillates: percent contents by weight of the fraction boiling at temperature above 170C and maximum at temperature 360C; VGO+ weight percent contents of fraction boiling at temperature above 360C. ^ EFFECT: increased efficiency of preliminary purification of crude. ^ 12 cl, 2 ex, 1 tbl, 1 dwg

Description

The scope of the invention

The present invention relates to the oil industry and to the use of heavy and sulfur-saturated residues of oil refining. Oil is traditionally refined at refineries using a combination of technological separation processes and chemical conversion in order to ensure the production of a set of final commercial products that meet regulatory documents or specific and well-defined technical requirements, such as distillation intervals, contents sulfur, characteristic technical indicators, such as, for example, octane number or diesel display Tel, etc.

The main commercial end products are petrochemical naphtha, gasoline, kerosene, gas oil (also called diesel fuel), fuel oil, as well as various categories of liquid fuels, more or less saturated with sulfur, bitumen for road use, liquefied petroleum gases and, in certain cases, other products, namely lubricating oils, solvents, paraffins, gas turbine fuels, etc. Thus, the refinery provides for the production of a relatively large number of final products of a commercial nature based on a certain number of types of crude oil, selected as a function of the chemical composition of this oil and its cost.

Changes in markets, on the one hand, associated, in particular, with increasing competition of natural gas, and strict regulation regarding polluting emissions of installations in which hydrocarbon fuels are burned, on the other hand (regulation of emission levels of sulfur oxides, nitrogen oxides and particulate emissions, in in particular in Europe), it leads to a very unfavorable situation for the sale of heavy and sulfur-containing liquid fuels, for example heavy liquid fuels, in which the sulfur content exceeds 3.5 or 4%. Thus, oil refineries face a very significant technical problem, which is the use of sulfur-containing oil refining residues, taking into account existing regulatory requirements. This sulfur-containing liquid fuel is usually redundant, and many countries seek to limit the sulfur content of the liquid fuel used to 1%, and in the future to 0.5% and even 0.3%.

Another trend in the use of petroleum products is the desire to increase the consumption of medium distillates and gasoline instead of liquid fuels, with the trend of increasing consumption of medium distillates being more significant than the trend of increasing consumption of gasoline.

The present invention relates to a method for pre-treatment of oil, usually carried out in the region of its production, designed to improve the quality of oil in the light of these market changes.

State of the art

The applicant has already proposed in patent application FR-04/02088 to use a gas associated with the oil field, usually cheap enough, to pre-treat conventional oil and to produce, on the one hand, Ra oil with a low sulfur content and essentially no asphaltenes, but with on the other hand, residual oil Pb (containing the starting asphaltenes, partially converted as a result of hydrogenation treatment). Ra oil produced in this way will produce, after distillation, very little, or not at all, liquid fuel containing sulfur, and may have a high content of middle distillates, which are increasingly in demand on the market. This oil is of high quality. Pb oil typically contains low quality fractions, in particular residual asphaltenes.

The corresponding method is a method for pre-refining crude oil, that is, a method for producing pre-refined oils Ra and Pb (improved quality, at least for oil Ra) as final products. These grades of oil (pre-refined) are usually marketed, exported, and delivered to refineries. This pre-treatment method also includes the secondary production, if necessary, of the final commercial petroleum products, such as naphtha, gas oil, etc.

This method from the existing level of technology thus provides the production of high quality Ra oil, which is in demand on the market. However, there is a need to further improve the relevance of the existing market and to improve the quality of the proposed high-quality oil in order to meet the needs of the market and add value to the proposed product.

SUMMARY OF THE INVENTION

The present invention proposes a method of pre-refining crude oil of ordinary quality, making it possible to produce not two, but at least three pre-refined oils Ra, Pb and Pc, two of which (Ra and Pb) are high-grade, essentially not containing asphaltenes, which after distillation will produce many products of high cost (naphtha, gasoline, middle distillates). In contrast, Pc oil is oil having a residue containing asphaltenes and will produce a significant amount of liquid fuel after distillation.

In accordance with the main distinguishing characteristic of the present invention, the two oils Pa and Pb have different relative potentials in terms of balance ((naphtha + gasoline) / middle distillate) after conventional distillation. Thus, this refinery will be able to supply itself not only with regard to its needs for liquid fuel (through the use of Pc oil), but also modulating its stocks with Pa and Pb oils in order to properly adapt to its own market, in in particular, to the balance (naphtha + gasoline) / middle distillate. An oil refinery, located mainly in the immediate vicinity of urban areas, will certainly not have the same distribution between gasoline and diesel fuel as an oil refinery located in rural areas. There will also be differences between refineries located in close proximity to petrochemical complexes that crack naphtha and refineries located near mountains (increased fuel oil consumption due to the colder climate). Thus, the present invention allows you to individually adapt each refinery to its own market. This invention also allows, by introducing a means of adaptation to the market, to provide the best access to this market and the highest cost of the proposed high-quality oil Ra and Pb.

This adaptation tool, subtle and effective, is not associated with the production of liquid fuel, but is mainly associated with the use of residual oil Pc. Thus, the balance (naphtha + gasoline) / middle distillates can be adjusted independently of the production of liquid fuel.

Detailed Description of the Invention

The present invention provides a method for pre-refining oil, which allows producing at least three grades of pre-refined oil Ra, Pb and Pc based on crude oil P (or several grades of crude oil P1, P2, etc.). Moreover, the oils Ra and Pb are high quality oil, that is, oil essentially free of asphaltenes. The method in accordance with the invention also allows, if necessary, to ensure the production of more than 3 grades of pre-refined oil, for example 3 oils that do not contain asphaltenes, and even more. You can also produce 2 or 3 residual oils (containing asphaltenes) and even more. At the same time, it will not be beyond the scope of the invention that this method allows for the by-product of final or refined products: liquid fuel, naphtha, kerosene, gas oil, liquid fuel for domestic purposes, oils or oil bases, etc.

One or more grades of crude oil P are usually conventional, but any available type of crude oil can be used, for example, conventional, heavy, bituminous and, in particular, any oil with an API in the range of 5 to 50.

In accordance with the proposed method, the separation of oil P into fractions is used using at least initial distillation (the so-called "atmospheric") and usually by vacuum distillation. This initial distillation preferably separates at least 2 fractions, one of which is relatively richer in middle distillates and the other is relatively richer in naphtha (or at least has a different ratio between naphtha and middle distillates).

The method in accordance with the invention also comprises at least one HDT hydrotreatment unit or a conversion unit, in particular a unit for hydrocracking distillation products in a VGO vacuum. This method also often comprises a vacuum deasphalting unit and a hydrotreating or hydrocracking unit for the produced and asphalt-free DAO oil. Finally, this method typically comprises an apparatus for hydroconversion of RHDC residues.

In accordance with one of the main characteristics of the invention, the character of fractionation, the conversion method carried out in the said plants, and the distribution of the components Ra and Pb are determined so that the component Ra is relatively rich in precursors of gasoline and naphtha and is relatively poor in middle distillates, namely kerosene and the diesel fraction, while the Pb component, on the contrary, is oil, relatively less rich in gas and naphtha precursors and relatively more rich in average and distillates.

In particular, it is possible to characterize oil, essentially free of asphaltenes, using the ratio:

R = (0.9 N + 0.5 VGO +) / (MD + 0.1 VGO +), where:

N = naphtha: represents the percentage by weight of the fraction (distillation of TBP) boiling at a temperature of 30 to 170 ° C;

MD = middle distillates: represents the percentage by weight of the fraction boiling at temperatures above 170 ° C but below 360 ° C;

VGO + = represents the percentage by weight of the fraction boiling at temperatures above 360 ° C. It should be noted here that when it comes to oil Ra and Pb, the VGO + component refers to the unconverted fractions (usually hydrotreated or hydrocracked) of VGO and DAO that are not asphaltene (or essentially free of asphaltenes).

If we consider the efficiency obtained as a result of conventional oil refining, we come to the following conclusions.

- Naphtha N can be converted to gasoline by approximately 90% through reforming and isomerization.

The VGO + component, which in this case does not contain asphaltenes and is usually hydrotreated, can be converted to gasoline by about 50% using catalytic cracking (called FCC, or “fluid catalysts cracking” in English, which can be translated as catalytic cracking into fluidized bed).

Thus, the term (0.9 N + 0.5 VGО +) is (for oil not containing asphaltenes) a good indicator of the gasoline potential of the oil during its subsequent refining.

- At the same time, it is usually possible to incorporate 10% by weight of catalytic cracking gas oil (often called LCO, or “light must oil” in English, which translates as light cyclic liquid oil) into middle distillates, with the rest of the LCO used as thinner (or thinner) of liquid fuel. Thus, the term (MD + 0.1 VGO +) is a good indicator of the potential of middle distillates of oil during the subsequent refining of this oil.

Therefore, the R ratio characterizes the potential for gasoline with respect to the potential for middle distillates: oil with a high ratio of R will produce a relatively larger amount of gasoline, while oil with a low ratio of R will produce a relatively larger amount of middle distillates.

According to the invention, the ratio Ra for oil Pa is generally higher than the ratio Rb for oil Pb. This can easily be achieved, for example, by introducing a relatively greater amount of naphtha N and / or the unconverted VGO component into the Pa oil than into the Pb oil, and vice versa, by introducing a relatively larger amount of middle distillates MD into the Pb oil than into the Pa oil. The decomposition of the original oil into fractions having different contents of naphtha, middle distillates and the VGO + component really makes it possible to easily provide a change in composition, making it possible to enrich one or another oil Ra or Pb with middle distillates or gasoline precursors. For the effluents of the conversion plants, it is possible to adapt this conversion and / or measure the content of the VGO + component in these effluents (by distillation, chromatographic analysis, etc.) in order to evaluate the content of naphtha, middle distillates and the VGO + component in order to effect the desired change composition of oil Ra and Pb.

In General, this invention provides a method for pre-treatment of at least one grade of crude oil P with catalytic hydrogenation purification of one or more distillation fractions obtained from oil P, including:

at least one first fractional fractionation step F1 using an initial distillation PRE-DIST intended to produce a first residue R1 and at least one first asphaltene-free (i.e. light) stream E1,

at least one second step F2 of fractionating at least a portion of residue R1 (i.e., fraction R1 or fraction obtained from residue R1) by vacuum distillation of VAC-DIST and / or by reducing the SDA asphalt content in the solvent for production according to at least one second stream E2 not containing asphaltenes and containing asphaltenes of residue R2,

at least one step of hydrotreating the HDT and / or hydroconverting the HDC and / or hydrocracking the HDK of at least a portion of component E2 to produce an HE2 effluent,

- and, if necessary, the hydroconversion step of the RHDC of at least a portion containing asphaltenes of the fraction obtained from residue R2,

in which the stages of separation into fractions and / or hydrogenating catalytic purification in accordance with this method are determined so that at least two of the effluents not containing asphaltenes and produced on the basis of crude oil P have different R values, defined by the ratio:

E = (0.9N + 0.5 VGO +) / (MD + 0.1VGO +), where:

N = naphtha: the percentage by weight of the fraction boiling at a temperature between 30 and 170 ° C; (for example, N = 25 if there is 25% by weight of naphtha in the considered effluent or hydrocarbon stream);

MD = middle distillates: percentage by weight of the fraction boiling at temperatures above 170 ° C and maximum at 360 ° C;

VGO + = percentage by weight of the fraction boiling at temperatures above 360 ° C,

and in accordance with this method, the following steps are further implemented:

a) change the composition and produce on the basis of effluents that do not contain asphaltenes (that is, substantially free of asphaltenes) produced on the basis of crude oil P, hydrotreated and / or hydroconverted and / or hydrocracked if necessary, at least two grades of asphaltene-free oil Ra and Pb having different ratios R, that is, different ratios Ra and Rb,

b) producing at least one residual Pc oil containing the predominant portion of at least asphaltenes from the asphaltene residue R2 or at least residual asphaltenes after RHDC hydroconversion, if the process comprises such a step. In this case, it will not be beyond the scope of the invention to produce not one but several varieties of residual oil Pc1, Pc2, which usually contains the largest part of the asphaltenes mentioned above.

Typically, the varieties of oil Ra and Pb are formed mainly on the basis of fractions obtained from the group of the following fractions, in turn, obtained from crude oil P, which, if necessary, are subjected to hydrotreating and / or hydroconversion and / or hydrocracking: naphtha N , middle distillates MD, intermediate gas oil IGO, light product of vacuum distillation LVGO, heavy product of vacuum distillation NVGO or complete product of vacuum distillation VGO, de-asphalted liquid oil DAO, with the corresponding temperature ranges of distillation TBP, and names about:

N: (30 ° C / 170 ° C); MD: (170 ° C / 360 ° C); IGO: (340 ° C / 420 ° C); LVGO: (360 ° C / 450 ° C); HVGO: (450 ° C / 565 ° C); VGO: (360 ° C / 565 ° C); DAO:> 565 ° C.

Since such a separation into fractions is not completely perfect, it will not go beyond the scope of the present invention if the above distillation fractions are formed, for example, at least 50% by weight of the total composition, in the corresponding distillation intervals mentioned above.

Typically, a ratio of 1.10 <Ra / Rb <4.5. However, most often this ratio has the form 1.15 <Ra / Rb <4. In a preferred manner, said ratio has the form 1.3 <Ra / Rb <3. And in a very preferred way, this ratio has the form 1.4 <Ra / Rb <2.5.

Usually we can say that 0.7 <Ra <2.0. Most often, this ratio has the form 0.8 <Ra <1.7. In a preferred manner, said ratio looks like 1.3 <Ra <3. And in a very preferred way it has the form 1.4 <Ra / Rb <2.5.

The preferred ratios are of the form 1.0 <Ra <1.5 and 0.35 <Rb <0.9.

In this case, usually 0.8 <Ra <1.7 and 0.3 <Rb <1.0.

Preferably, the Pc oil contains the largest portion of at least the RHDC hydroconversion effluent of residue R2 in a fluidized bed.

According to one embodiment of the invention, residue R2 is the product of the vacuum distillation of component VGO.

According to another embodiment of the invention, residue R2 is asphalt AS obtained by removing the SDA asphalt using a solvent. In this case, the asphalt AS is often hydroconverted in a fluidized bed with the addition of a liquid diluent DIL containing at least 30% by weight of components boiling at temperatures below 340 ° C.

Typically, the amount of said diluent is in the range of 4 to 40% by weight of the weight of the asphalt AS, preferably in the range of 5 to 30% by weight of the weight of asphalt AS, and very preferably in the range of 6 to 25% by weight of the weight of this asphalt is AS.

The DIL component usually contains from 3 to 25% by weight, and preferably from 4 to 20% by weight of the weight of asphalt AS, and in a very preferred way from 5 to 15% by weight of fractions boiling at a temperature of not more than 360 ° C.

The solvent used for deasphalting is preferably relatively heavy (significantly heavier than propane) and thus produces asphalt concentrated in asphaltene. All solvents suitable for use in this case contain mainly paraffin hydrocarbons (if necessary, olefinic hydrocarbons) having from 3 to 7 carbon atoms. However, in a very preferred manner they contain mixtures of propane and butane, butane, pentane, hexane, heptane, light gasoline, as well as mixtures based on the above solvents. Preferably, these solvents contain butane, pentane, hexane and mixtures thereof. In a highly preferred manner, these solvents contain butane, pentane and mixtures thereof.

The SDA deasphalting operation in a solvent can be carried out under normal conditions. In this case, one can refer to an article by BILLON and others, published in 1994 in Volume 49, No. 5 of the journal of the French Institute of Petroleum, pages 495-507, as well as the book "Raffinage et conversion des produits lourds du petrole" written by the authors of JFPage , SGChatila et M. Davidson, TECHNIP, pp. 17-32, or the description given in French patent FR-B-2480773, or in patent FR-B-2681871, or in patent application US-A-4715946 . The deasphalting operation, in particular, can be performed at a temperature ranging from 60 to 250 ° C, using one of the above solvents and adding, if necessary, one or another additive. The solvents and additives used in this case are described, in particular, in the above documents, as well as in patent documents US-A-1948296; US-A-2081473; US-A-2,587,643; US-A-2,882,219; US-A-3278415 and US-A-3331394. The solvent used can be recovered by evaporation or distillation, or by the optical method, i.e. under supercritical conditions. The deasphalting operation may be carried out using a sump mixer or extraction column.

In accordance with another embodiment of the invention, asphalt is not converted: untreated asphalt A3 is directly mixed with one or more oil fractions, usually obtained from crude oil P, in order to obtain oil PC, the remainder of which when processed in a vacuum in this case contains refined asphaltenes in an increased amount with respect to the vacuum residue of crude oil R. These oil fractions usually contain at least one fraction of crude oil which is mixed with asphalt AS.

In accordance with one embodiment of the invention, Pa, Pb, and Pc oils are obtained so that the percentage of components boiling at a temperature in the range from 360 to 400 ° C relative to the VGO fraction is reduced for Pb oil compared to crude oil P, as well as for at least one of the oils Ra and Pc. Thus, for example, the IGO or LVGO fraction is oriented after hydrotreating or light hydrocracking, preferably in the direction of component Pa and / or component Pc rather than in the direction of component Pa. You can also carry out the conversion with a degree of conversion of more than 50%, or more than 70%, of the components of IGO or LVGO and to apply the effluent in a more significant way in the direction of the components Ra and / or Pc. Such relative depletion of the Pb component with components boiling at a temperature in the range from 360 to 400 ° C allows easier distillation of middle distillates of oil Pb (fractionation of MD / VGO) and thus enables the inclusion of increased amounts of middle distillates of MD into component Pb without problems of refining Pb oil at the level of initial distillation.

In accordance with the invention, Ra, Pb, and Pc determine the oils representing the final products of the proposed method for the preliminary purification of oil, each of which is intended to be used as a feed for initial distillation carried out at one or usually several refineries.

The oils Ra, Pb, and Pc are the final products of the oil pre-refining process, which are conventional refinery feeds and are not final products, or intermediate distillation products, or final products intended for a particular use. Each of these grades of oil usually contains at least 6% by weight of naphtha N, at least 10% by weight of middle distillates MD (for example, at least 4% by weight of kerosene (170 ° C / 250 ° C), at least at least 6% by weight of the diesel fraction (250 ° C / 360 ° C) and at least 10% by weight of the distillation product in vacuum VGO).

Typically, the largest portion of at least the Ra and Pb oils is transported separately by pipeline or oil tankers, with a view to subsequently using this oil as a charge for initial distillation units at one or usually several refineries.

Description of the drawing

The following is a link to the drawing, which shows a diagram of a process plant designed to implement the method in accordance with the invention.

Conventional type crude oil P (e.g., light Arab oil) is supplied via line 1 to a device 2 designed to lower the salt content. This desalted oil is then fed via line 3 to the PRE-DIST pre-distillation column (often referred to as the initial distillation or atmospheric distillation column), indicated at 4, which typically operates under pressure in the range of 0.1 to 0.5 MPa. This distillation column, which, if necessary, is able to realize total fractionation, produces a stream of light oil products, usually naphtha and lighter distillation products, delivered via line 30, a stream of medium distillates MD, usually kerosene and diesel fractions, discharged through line 5, and a stream IGO intermediate gas oil, dispensed via line 6, which may contain fractions boiling mainly at a temperature in the range of 340 to 420 ° C. This intermediate gas oil, relatively heavy for an atmospheric distillation column, can be obtained by significantly distilling off the light fractions in a vapor state.

This distillation column 4 also produces an atmospheric residue discharged via line 7, which enters the VAC-DIST vacuum distillation column indicated at 8. This vacuum distillation column, which typically operates under pressure ranging from 0.004 to 0.04 MPa, produces a VGO vacuum distillation product stream discharged through line 10 and a vacuum distillation residue stream VR discharged through line 9. V if necessary, this distillation column can also produce a stream of light distillation product in a vacuum LVGO, issued via line 11.

The remainder of the VR distillation in vacuum enters the SDA asphalt removal unit in the solvent indicated at 12 (pentane is preferably used as solvent) in order to produce a liquid, asphalt-free DAO oil circulating in line 13, and an asphalt stream AS removed through line 14.

Asphalt AS is mixed with the DIL diluent stream coming in line 15. This stream usually contains a desalted oil stream coming from line 3 through line 15, and / or the middle distillate stream MD coming from line 5 through line 22, and / or an intermediate stream IGO gas oil coming from line 6 through lines 23 and 22. The diluent stream DIL may also contain naphtha N taken from line 30. The flow rate of said diluent with respect to the flow rate of asphalt AS usually has a value ranging from 3 to 50% by weight preferably chennuyu in the range from 4 to 40% by weight, usually enclosed in a range of from 5 to 30% by weight, and most preferably enclosed in a range of from 6 to 26% by weight.

The mixture of asphalt and diluent (i.e., diluted asphalt) then enters the fluidized bed hydroconversion RHDC unit, indicated at 16. This unit typically contains at least 2, and preferably at least 3 fluidized bed reactors arranged in series.

At the outlet of this RHDC unit, the hydroconversion effluent is supplemented by several flows coming through lines 30c, 31c, 32c, 33s and 34s. These streams typically contain naphtha N (line 30c), hydrotreated middle distillates MD (line 31c), hydrotreated or hydrocracked (usually partially) intermediate IGO gas oil (line 32c), hydrotreated or hydrocracked (usually partially) distillate under vacuum VGO ( line 33c), hydrotreated or hydrocracked (usually partially) asphalt-free oil (line 34c). In this way, the (pre-refined) Pc oil is reduced based on the hydroconversion effluent, which usually contains hydrotreated or hydrocracked fractions that do not contain asphaltenes, that is, fractions with a reduced sulfur content. This Pc oil has a sulfur content that is definitely lower than the sulfur content of the original crude oil P.

In this case, the fractions MD, IGO, VGO, DAO are hydrotreated or hydrocracked (usually partially) in process plants N1, indicated by 21, H2, indicated by 20, H3, indicated by 19, and H4, indicated by 18. Usually, a processing unit H1 (and often H2) carries out HDT hydrotreating, and process plants H3 and H4 are process plants for carrying out soft hydrocracking of M-HDK, medium-pressure hydrocracking MP-HDK or high-pressure hydrocracking HP-HDK. Preferably, the process unit H4 provides fluidized bed hydrocracking.

The light stream circulating in line 30 is divided into three elementary streams 30a, 30b, 30c.

The effluent coming from the process unit H1 and circulating in line 31 is divided into three elementary streams 31a, 31b, 31c.

The effluent coming from process plant H2 and circulating in line 32 is divided into three elementary streams 32a, 32b, 32c.

The effluent coming from the technological plant H3 and circulating in line 33 is divided into three elementary streams 33a, 33b, 33c.

The effluent coming from the process unit H4 and circulating in line 34 is divided into three elementary streams 34a, 34b, 34c.

Based on streams 30a, 31a, 32a, 33a and 34a, pre-refined grade Ra oil is obtained by mixing. This Ra oil is an oil essentially free of asphaltenes, since each of its components also does not contain asphaltenes (asphaltenes are contained only in the AS stream). This oil is also very low sulfur oil because most of its components are sulfur free, and the naphtha coming through line 30a is usually poor in sulfur (you can also hydrotreat it additionally).

Similarly, based on streams 30b, 31b, 32b, 33b and 34b, pre-refined Pb oil is obtained by mixing. For the same reasons as for Ra oil, Pb oil is also oil, essentially free of asphaltenes and with a very low sulfur content.

In accordance with the invention, the degree of conversion of process plants and the distribution of the components Ra and Pb are determined so that the oil Pa is relatively rich in gasoline and naphtha precursors and relatively poor in middle distillates, i.e. kerosene and diesel fractions, while oil Pb, on the contrary, is it is oil, relatively less rich in the precursors of gasoline and naphtha and relatively more rich in middle distillates.

Typically, in accordance with the invention, the ratio of Ra for oil Pa exceeds the ratio of Rb for oil Pb. This can easily be done, for example, by including a relatively larger amount of naphtha N and the unconverted VGO + component in the composition of oil Pa (via lines 30a and 33a) than in the composition of oil Pb (via lines 30b and 33b), and, conversely, by including more middle distillates MD in the composition of oil Pb (via line 31b) than in the composition of oil Ra (via line 31a). The decomposition of the original oil into fractions makes it possible to easily change its composition, which makes it possible to enrich one or the other oil Ra, Pb with middle distillates or gasoline precursors. For the effluents from the conversion process plants, it is possible to adapt this conversion and / or measure the content of the VGO + component in the mentioned effluents (by distillation, chromatographic analysis, etc.) in order to determine the content of the mentioned VGO + component in them.

Usually, the composition of the oil Ra and Pb is converted so that the ratio Ra / Rb has a value in excess of 1.08, or even 1.12, or 1.2, and that it has a value, in particular, in the range of 1, 08 to 3.0, often in the range of 1.12 to 2.50, preferably in the range of 1.20 to 2.0, and very preferably in the range of 1.25 to 1.80.

In accordance with the invention, before converting the composition of the oil Ra, Pb, Pc, one or more catalytic steps can be carried out, in which some processes are used that are well known from the prior art in this field, in particular, hydrogen pressure treatment designed to remove sulfur , which consumes a noticeable or very significant amount of hydrogen.

In accordance with the invention, the term “hydrogenation catalytic purification” will mean a treatment containing at least one of the processing methods described in the following description, indicated by the following names: HDT, HDC, HDK (which covers the processing methods of M-HDK, MP-HDK and HP-HDK), RHDT, RHDC. Thus, the following types of processing are distinguished.

a) Hydrotreating (symbolically indicated by the abbreviation NDT) of the asphaltene-free feed .

Methods for hydrotreating hydrocarbon products of distillation or asphalt-free petroleum oil (feeds essentially free of asphaltenes) are methods well known in the art. The main purpose of this purification is to at least partially remove unwanted substances, usually such as sulfur, nitrogen, and, if necessary, metals such as iron, nickel or vanadium, etc. These methods are also often used to carry out the hydrogenation of aromatic hydrocarbons, usually performed simultaneously with the removal of sulfur from a given charge.

In the usual way, for those of the above downloads that contain components boiling at temperatures above 371 ° C, hydrotreating is the process in which the conversion of these components to components having a boiling point below 371 ° C is less than or equal to 20% by weight . For processes that process the same load, but with a conversion exceeding 20% by weight, they speak of hydroconversion (symbolized by the abbreviation HDC) or hydrocracking (symbolized by the abbreviation HDK), and these processes are described in more detail in the following discussion.

Hydrotreating methods operate under hydrogen pressure and use supported solid catalysts, usually solid granules or extruded elements of a characteristic size (namely, a diameter for balls or an equivalent diameter (corresponding to the same cross section) for solid extruded elements), the value of which is enclosed in the range from 0.4 to 5 mm, and in particular in the range from 1 to 3 mm. Technological conditions and, in particular, spatial velocity (VVH) and the molar ratio of hydrogen to hydrocarbon (H ₂ / HC), varies depending on the characteristics of the processed fractions, the presence of contaminants in them and the final properties that need to be obtained.

Typical but non-limiting examples of process conditions are shown in the table below.

Oil fraction The boiling point of the fraction (° C) Spatial speed
(h-1) Pressure N ₂
(bar) Cycle start temperature
(° C) The ratio of N ₂ / NS (Nm ³ / m ³ ) Consumption of H ₂ (% by weight) Naphtha 70-180 4-10 5-10 260-300 one hundred 0.05-0.01 Kerosene 160-240 2-4 15-30 300-340 150 0.01-0.02 Diesel and gas oil 230-371 1-3 20-40 320-350 150-300 0.3-0.8 Vacuum gas oil 371-565 1-2 40-70 360-380 300-500 0.4-0.9 Deasphalted Oil > 565 0.5-1.5 50-110 360-380 500-1000 0.5-1

Hydrotreating catalysts typically comprise a metal or a composition of Group VIB metals and some metal, or a metal composition of Group VIII, on a support.

The most commonly used catalysts are an oxide carrier and an active phase in the form of a sulfur compound of molybdenum or tungsten, promoted with cobalt or nickel. Commonly used formulas are CoMo, NiMo, and NiW compounds for the active phase and aluminum hydroxide γ with a large specific surface area for the support. The metal content often ranges from about 9 to 15% by weight for molybdenum and from 2.5 to 5% by weight for cobalt or nickel.

Some of these catalytic formulas are sometimes supplemented with phosphorus. Other oxide carriers are also used, such as, for example, mixed oxides such as silica-aluminum hydroxide or titanium-aluminum hydroxide.

These supports usually have a weak enough acidity to provide an acceptable catalytic cycle duration.

Typical examples of catalysts and hydrotreating, in particular for diesel fractions, gas oil or vacuum gas oil, are catalysts HR 448 and HR 426 of the French company AXENS.

When traces of metals, in particular nickel and vanadium, are present in the feed, a catalytic support having porosity adapted to precipitate these metals is preferably used.

An example of such a catalyst is a catalyst NMS 841, supplied by ACHENS.

For hydrotreating asphalt-free liquid oil (DAO) containing metals, for example, you can use the first layer with a catalyst NMS 841 to remove metals, and then the second layer with a catalyst HR448 to remove sulfur and nitrogen.

Other technical elements related to hydrotreating can be found in the reference work: "Conversion processes", P. Leprince, Technip, Paris 15, pages 533-574.

b) Hydrocracking processes (symbolically designated by the NDK abbreviation) of asphaltene-free feeds.

Hydrocracking processes are also methods well known in the art. They apply exclusively to batches essentially free of asphaltenes or metals such as nickel or vanadium.

The hydrocracking charge typically consists of vacuum gas oil, to which gas oil and / or asphalt-free liquid oil is sometimes added (vacuum residue de-asphalted, usually with a solvent from the group consisting of propane, butane, pentane and mixtures thereof, and preferably formed with propane and butane).

You can also hydrocrack deasphalted DAO liquid oil. In this case, the DAO component should be of a sufficiently high quality: usually a loading for the use of hydrocracking contains asphaltenes less than 400 ppm (that is, parts per million by weight), preferably less than 200 ppm and very preferably less than 100 ppm. The metal content (usually nickel + vanadium) in the hydrocracking feed is typically less than 10 ppm, preferably less than 5 ppm and very preferably less than 3 ppm.

It is generally believed that said charge is substantially free of asphaltenes if the asphaltenes content is less than 400 ppm. For pre-refined oil, it is similarly considered that it does not contain asphaltenes or is not asphaltenic if the fraction boiling at temperatures above 524 ° C contains less than 400 ppm of asphaltenes.

A feed intended for hydrocracking is typically first pre-treated with a hydrotreating catalyst, typically different from the catalyst used for hydrocracking. This catalyst, typically having an acidity lower than the acidity of the catalyst used for hydrocracking, is selected so as to substantially remove the metals mentioned above, reduce traces of asphaltenes and reduce the amount of organic nitrogen that inhibits the hydrocracking reaction, down to a level that is usually less than 100 ppm, preferably 50 ppm, and very preferably less than 20 ppm.

Catalysts designed to perform hydrocracking are typically bifunctional catalysts that have a dual function, namely an acid function, on the one hand, and a hydrogenator / dehydrogenator function, on the other hand. Typically, the catalyst carrier has a relatively high acidity such that the ratio of the hydrogenating activity to the isomerizing activity of H / A, as defined in French Patent Document No. 2805276, page 1, line 24 to page 3, line 5, has a value greater than 8 , or preferably in excess of 10, or in a very preferred manner, in excess of 12, or even in excess of 15. Typically, hydrotreating is carried out in front of the reactor or in front of the hydrocracking zone with a hydrotreating catalyst, for which the above e H / A ratio is less than 8 and, in particular, less than 7.

Hydrotreating catalysts typically contain at least one metal or metal composition from group VIB (e.g., Mo and W) and some metal or metal composition from group VIII (e.g., Ni and the like) supported on a carrier. The atomic ratio of a metal from group VIII (M _VIII ) to the sum of the metals from groups VIII and VI _B , i.e. the atomic ratio of M _VIII / (M _VIII + M _VIB ), in particular for NiMo and NiW pairs, is often close to 0.25 and concluded, for example, in the range from 0.22 to 0.28.

The metal content often has a value in the range of 10 to 30% by weight.

The Group VIII metal may also be a noble metal, such as, for example, palladium or platinum, with a content in the range of about 0.5 to 1% by weight.

The acid support of the catalyst may contain aluminum hydroxide modified with a particular halogen, or silicon dioxide - aluminum hydroxide having a sufficiently high acidity, or a zeolite, for example zeolite Y or dealuminized zeolite USY, having a double pore distribution with a double porosity network, containing in particular, micropores, the sizes of which are mainly in the range of 4 to 10 angstroms, and mesopores, whose dimensions are mainly in the range of 60 to 500 angstroms. The ratio of silicon dioxide / aluminum hydroxide in the structure of the zeolite often has a value in the range from 6.5 to 12.

As an example, a sequence consisting of a hydrotreating operation followed by a hydrocracking operation using HR 448 (HDT) catalysts and then HYC 642 (HDK), marketed by the French company AXENS, can be used. If this charge contains metals, a catalyst layer can be used in front of the two catalytic beds to remove metals, such as the NMS 841 catalyst, also marketed by AXENS.

A typical example of technological conditions for the implementation of hydrocracking is as follows:

- spatial velocity VVH has a value in the range from 0.3 to 2 h ^-1 ,

- temperature in the range from 360 to 440 ° C,

- hydrogen recirculation has a value in the range from 400 to 2000 Nm ³ per cubic meter of load,

- the partial pressure of hydrogen and the total pressure of the gas can vary significantly depending on the characteristics of the load and on the desired degree of conversion. Relatively speaking, a degree of conversion greater than or equal to 20% by weight, but less than 42% by weight, corresponds to mild hydrocracking (symbolically indicated by the abbreviation M-HDK); a degree of conversion greater than or equal to 42% by weight, but less than 60% by weight, corresponds to medium pressure hydrocracking (symbolically indicated by the abbreviation MP-HDK); a degree of conversion greater than or equal to 60% by weight (and typically less than 95% by weight) corresponds to high pressure hydrocracking (symbolically referred to as HP-HDK).

By definition, said conversion is the conversion of products having a boiling point in excess of 371 ° C to products having a boiling point of less than 371 ° C.

Typically, the partial pressure of hydrogen, in accordance with the charge used, often has a value in the range of about 2 to 6 MPa for mild hydrocracking, in the range of about 5 to 10 MPa for medium-pressure hydrocracking, and in the range of about 9 to 17 MPa for high-hydrocracking pressure. The total pressure often has a value in the range of about 2.6 to 8 MPa for mild hydrocracking, in the range of about 7 to 12 MPa for medium pressure hydrocracking, and in the range of about 12 to 20 MPa for high pressure hydrocracking.

Hydrocracking processes are usually carried out in a fixed (fixed) layer using solid granules or extruded elements of characteristic sizes (namely, diameter for balls or equivalent diameter (corresponding to the same cross section) for solid extruded elements) having a value in the range of 0.4 up to 5 mm, in particular in the range from 1 to 3 mm. It will not be beyond the scope of the invention if the hydrocracking operation was carried out in a moving layer (a layer of granular catalyst, usually presented in the form of solid extruded elements, or preferably in the form of solid balls having dimensions similar to those specified in previous statement for a fixed layer).

Other technical elements related to the hydrocracking operation can be found in the reference work: "Hydrocracking Science and Technology", J. Scherzer, AJGruia, Editeur Marcel Dekker, New York, and also in the reference work : "Conversion processes", P. Leprince, Technip, Paris 15, pp. 334-364.

c) Hydroconversion processes (symbolically indicated by the abbreviation NDC) of a charge that does not contain asphaltenes (for example, a DAO-type charge) but contains a significant amount of metals (Ni, V).

Such processes are known that make it possible to achieve a conversion (with the same definition as for hydrocracking operations) that exceeds 20% by weight and often significantly exceeds this value (for example, in the range from 20 to 50% by weight, or in the range from 50 up to 85% by weight), for example, processes performed in a fluidized bed. In these processes, an alternating partial pressure of hydrogen can be used, varying, for example, in the range from 4 to 12 MPa, temperatures in the range from 380 to 450 ° C, and hydrogen recirculation in the range, for example, from 300 to 1000 Nm ³ per cubic meter of charge.

The catalysts used in this case are similar or close to the types of catalysts used in the hydrotreating or hydroconversion of the residues defined in the following statement, and have a porosity that allows a significant ability to remove metals.

You can, for example, use a catalyst like HTS 358, marketed by the French company AXENS.

d) Hydro-treatment of residues (symbolically designated by the abbreviation RHDT) or hydroconversion of residues (symbolically indicated by the abbreviation RHDC) .

Hydrotreating residues (and residual hydroconversion) are processes well known in the art.

The operating conditions for the implementation of these processes are usually as follows: hourly spatial speed (or VVH parameter) has a value in the range from 0.1 to 0.5. The partial pressure of hydrogen H ₂ has a value in the range from 1 to 1.7 MPa. Hydrogen recirculation has a value in the range from 600 to 1600 Nm ³ per cubic meter of said charge. The temperature ranges from 340 to 450 ° C. Catalysts of processes carried out in a fixed layer, in a moving layer or in a fluidized bed, most often are held macroscopic solids, such as balls or extruded elements having an average diameter in the range from 0.4 to 5 millimeters. In this case, usually we are talking about retained catalysts containing a metal or metal composition from group VIB (Cr, Mo, W) and some metal or a metal composition from group VIII (Fe, Co, Ni, etc.) on a mineral substrate, for example catalysts based on cobalt and molybdenum on a substrate of aluminum hydroxide; or catalysts based on nickel and molybdenum on a substrate of aluminum hydroxide.

To carry out hydrotreating or hydroconversion in a fixed bed, for example, the hydrometallic catalyst NMS 841 can be used, then the hydroconversion and hydrocracking catalysts HT 318, and then the HT 328 catalyst sold on the market by the French company AXENS.

For a fluidized bed, you can use a catalyst type HOC 458, also distributed on the market by the French company AXENS.

Slurry-type process catalysts are more diversified and may contain coal or ground lignite particles impregnated with iron or other metal sulfate, used hydrotreatment ground catalyst, molybdenum sulphide particles bound to a hydrocarbon matrix obtained by in situ decomposition of precursors such as molybdenum naphthenate and etc. The sizes of said particles are usually less than 100 micrometers, and they can even be significantly smaller.

Other characteristics of the hydroconversion processes and catalysts are given in the work generally indicated by A: “Raffinage et conversion des produits lourds du petrole” published by JF Le Page, SG Chatila, M. Davidson, Technip, Paris, 1990, chapter 4 (Catalytic conversion under hydrogen pressure), and chapter 3, paragraph 3.2.3. You can also refer to the work, generally indicated by position B: “Conversion processes”, P. Leprince, Technip, Paris 15, p. 411-450, in chapter 13 (hydroconversion of residues), as well as in the general work : "Upgrading petroleum residues and heavy oils", which means: Improving the quality of oil residues and heavy oil oils by Murray R. Gray, editeur Marcel Dekker inc., New York, in chapter 5.

The production of hydrogen to carry out these various catalytic hydrogenation treatments can be carried out on the basis of a gas purified, for example, by steam reforming on a nickel catalyst, followed by the conversion of CO gas to steam and its subsequent purification, is a well-known process described in the above work, indicated by B, pp. 451-502, or in the reference book "The desulfurization of heavy oils and residua" (J Speight, Editeur Marcel Dekker, Inc., New York.

Examples

The performance of the examples below is presented without sulfur, in weight percent relative to the weight of the load used.

Example 1 in accordance with the prior art

Carry out a preliminary refining of crude oil R coming from the Middle East, performing the following operations.

The oil P is separated into fractions by atmospheric distillation and then distillation in vacuo to obtain 4 fractions:

- fraction N or naphtha and lighter components, representing 20% by weight of the weight of the original crude oil P, where 18% is naphtha and 2% are lighter components;

- MD fraction of middle distillates, representing 25% by weight of the weight of the original oil P;

- fraction VGO of the distillation product in vacuum, representing 35% by weight of the weight of the original oil P;

- fraction VR of the residue in vacuum, representing 20% by weight of the weight of the original oil R.

The MD fraction is hydrotreated (HDT) and the VGO fraction is converted with a 25% conversion, where the composition is of the order of 1% C4 gas, 5% naphtha and 19% middle distillate, carried out using mild HD-M hydrocracking.

Converted using a RHDC fluidized bed hydroconversion, the residue is removed under vacuum VR with 60% conversion to the VGO component and lighter products.

The following fractions are mixed: naphtha N, hydrotreated MD fraction (effluent HDT), the VGO fraction subjected to hydrocracking (effluent M-HDK), and 75% by weight of the mixture for the production of P * a oil, which is a high quality oil, is separated that it does not contain asphaltenes and is characterized by a low sulfur content (this content is, for example, less than 0.3% by weight and even less than 0.1%). The remaining 25% by weight of the mixture is added to the RHDC residual hydroconversion effluent to obtain a second refined P * b oil that contains unreformed asphaltenes and is thus residual oil.

Example 2 in accordance with the invention

Subjected to pre-refining the same crude oil P as in example 1, performing the following operations.

Oil P is separated into fractions by atmospheric distillation and then distillation in vacuo to obtain 5 fractions:

- fraction N or naphtha (and lighter components), representing 20% by weight of the weight of oil P, where 18% is naphtha and 2% are lighter components;

- fraction MD of middle distillates, representing 25% by weight of the weight of oil P;

- the IGO fraction (or LVGO) of the vacuum distillation product, rich in components boiling in the temperature range from 360 to 420 ° C, and representing 15% by weight of the weight of oil P;

- fraction NVGO distillation product in vacuum, representing 20% by weight of the weight of oil P;

- fraction VR, representing the remainder of the vacuum distillation and constituting 20% by weight of the weight of oil R.

Hydrotreating the MD fraction, converted to IGO with 20% conversion, where the composition of the components contains 1% C4 gas, 4% naphtha and 15% middle distillates using mild HDLC cracking, and the HBGO fraction is converted with 30% conversion, where There is 2% C4 gas, 6% naphtha and 22% medium distillates, using mild HD-M hydrocracking.

Converted using a RHDC fluidized bed hydroconversion, the remainder of the vacuum distillation VR with 60% conversion to the VGO component and lighter products.

The first mixing of Ma with the following fractions is carried out: 60% by weight of naphtha N, 40% by weight of hydrotreated fraction MD (effluent НТТ) and hydrotreated fraction IGO, and 75% by weight of mixture Ma is separated to obtain Ra oil, which is a high quality oil : it does not contain asphaltenes and is characterized by a low sulfur content (for example, less than 0.3% by weight and even less than 0.1%). Ra oil is oil with a relatively high potential for gasoline and a relatively low potential for middle distillates: Ra = 1.209.

A second mixing of Mb with the following fractions is carried out: 40% by weight of naphtha N, 60% by weight of hydrotreated MD fraction (НТТ effluent) and hydrocracked НВГО fraction, and 75% by weight of Мb mixture is separated to obtain Рb oil, which is a high-grade oil qualities: it does not contain asphaltenes and is characterized by a low sulfur content (constituting, for example, less than 0.3% by weight and even less than 0.1%). Pb oil is an oil having a relatively low potential for gasoline and a relatively high potential for middle distillates: Rb = 0.7.

The remaining 25% by weight of the mixtures of Ma and Mb is added to the hydroconversion effluent of the RHDC residues to obtain a third refined PC oil, which contains unconverted asphaltenes and is thus residual oil.

Thus, the ratio Ra / Rb is set at 1.73. The refinery can routinely supply itself with PC oil in order to satisfy its residual liquid fuel market, and then evaluate, depending on the PC oil processing capacity, the relative demand for naphtha, gasoline and middle distillates. At the same time, this refinery has two grades of oil, Ra and Pb, which it can choose in the distribution it needs in order to adjust the balance (naphtha + gasoline) / middle distillates.

Claims (12)

1. The method of pre-treatment of at least one crude oil PC by catalytic hydrogenation purification of one or more distillation fractions obtained from oil P, including:
at least one first fractionation step F1 by initial distillation (PRE-DIST) to obtain a first residue R1 and at least a first asphaltene-free stream E1,
at least one second step F2 of fractioning at least some of the residue R1 by vacuum distillation (VAC-DIST) and / or by removing asphalt (SDA) in a solvent to obtain at least a second non-asphaltene stream E2 and asphaltene residue R2,
at least one step of hydrotreating (HDT) and / or hydroconversion (HDC) and / or hydrocracking (HDK) of at least a portion of stream E2 to produce HE2 effluent,
and if necessary, a hydroconversion step (RHDC) of at least a portion of the asphaltene fraction obtained from residue R2,
and in accordance with this method, the following steps are implemented
a) separating asphaltene-free effluents, possibly subjected to hydrotreating and / or hydroconversion and / or hydrocracking obtained from crude oil P, into three elementary streams a, b, c, and then streams a obtained from different effluents are mixed, coming from different plants, and streams b obtained from different effluents coming from different plants to get at least two oils Pa and Pb that do not contain asphaltenes,
b) produce at least one residual PC oil containing the predominant part of at least residual asphaltenes of the asphaltene residue R2 or at least residual asphaltenes after hydroconversion (RHDC) and elementary streams c obtained from effluent-free streams, if this method contains such stage,
in which Ra, Pb and Pc are three grades of oil, which are the final pre-treatment products, and each of which is intended to be used as a feed for initial distillation at one or more refineries, and each of which contains at least 6% by weight of naphtha (N), at least 10% by weight of middle distillates (MD) and at least 10% by weight of vacuum distillation product (VGO),
in which the stages of fractionation and / or hydrogenating catalytic treatment of this method are determined so that at least two of the asphaltenes-free effluents produced from crude oil P have different E ratios defined by the expression:
E = (0.9N + 0.5VGO +) / (MD + 0.1VGO +),
where N is naphtha: the percentage by weight of the fraction boiling at a temperature in the range from 30 to 170 ° C;
MD - middle distillates: the percentage by weight of the fraction boiling at a temperature above 170 ° C and a maximum at a temperature of 360 ° C;
VGO + is the percentage by weight of the fraction boiling at temperatures above 360 ° C. 2. The method according to claim 1, in which the oils Ra and Pb are formed mainly on the basis of fractions obtained from the group of the following fractions obtained from P, which may be subjected to hydrotreating, and / or hydroconversion, and / or hydrocracking: naphtha (N), middle distillates (MD), intermediate gas oil (IGO), light vacuum distillation product (LVGO), heavy vacuum distillation product (HVGO) or general vacuum distillation product (VGO), asphalt-free oil (DAO). 3. The method according to one of claims 1 and 2, in which the ratio of 1.15 <Ra / Rb <4 is satisfied. 4. The method according to one of claims 1 and 2, in which the ratio of 0.8 <Ra <1.7 and 0.3 <Rb <1.0. 5. The method according to one of claims 1 and 2, in which the PC oil contains the largest part of at least the hydroconversion effluent (RHDC) of residue R2 in a fluidized bed. 6. The method according to one of claims 1 and 2, in which the residue R2 is asphalt (AS) obtained by removing asphalt (SDA) in a solvent. 7. The method according to claim 6, in which asphalt (AS) is subjected to fluidized bed hydroconversion with the addition of a liquid diluent containing at least 30% by weight of components boiling at a temperature below 340 ° C. 8. The method according to claim 7, in which the amount of diluent has a value in the range from 4 to 40% by weight relative to asphalt (AS). 9. The method according to claim 6, in which the unprocessed asphalt (AS) is directly mixed with one or more oil fractions in order to form a PC oil for which the vacuum distillation residue in this case contains natural asphaltenes in an increased amount of relative to their content in the residue obtained by distillation in a vacuum of crude oil R. 10. The method according to claim 9, in which said oil fractions contain at least one fraction of crude oil P, which is mixed with asphalt (AS). 11. The method according to one of claims 1 and 2, in which the oils Ra, Pb and PC are formed so that the percentage of components boiling at temperatures in the range from 360 to 400 ° C, in relation to the fraction (VGO) was reduced for oil Pb compared with oil P, as well as with at least one of the oil Ra and Pc. 12. The method according to one of claims 1 and 2, in which the largest part of at least the oil Ra and Pb is transported separately by pipeline transport and oil tankers with the aim of subsequently using this oil as a load for initial distillation plants on one or usually on several refineries.