CN118222326A - Method for processing heavy petroleum feedstock - Google Patents

Abstract

The present invention relates to the field of petroleum processing, and in particular to a process that allows the production of valuable products from heavy residues. A process for processing a heavy petroleum feedstock is presented, the process comprising subjecting the feedstock to hydrocracking (slurry phase hydrocracking, SPH) in a slurry phase, followed by separation into a stream of feedstock subjected to SPH and a heavy residue stream, wherein the heavy residue stream is a slurry of unconverted high boiling residue and depleted coal additive; subjecting the SPH-subjected feedstock to hydrocracking in the gas phase, followed by fractionation of the hydrocracked product; separating the depleted coal additive and the unconverted high boiling residue by using a solvent; supplying the mixture of unconverted high boiling residue and solvent to a vacuum column after the separation step to obtain a separated heavy residue; evaporating at least a portion of the separated heavy residue in a thin film evaporator to obtain a concentrated hydrocracking residue and a heavy vacuum gas oil (heavy vacuum gas oil, HVOG); and using at least a portion of the HVOG to obtain the solvent. The technical result is to ensure the possibility of obtaining valuable products from products that are difficult to use, and to ensure the stability of the hydrocracking process of heavy petroleum feedstocks.

Description

Method for processing heavy petroleum feedstock

Technical Field

The present invention relates to the field of petroleum processing, in particular a process for processing heavy petroleum feedstock, which allows the production of valuable products, typically refractory products, from heavy residues, which process is characterized by improved stability and efficiency, in particular in hydrocracking processes of heavy residues derived from petroleum processing.

Background

There are a variety of processes known in the art for processing heavy hydrocarbons in the presence of specific solid additives, adsorbents and catalysts, such as VCC, uniflex, EST, GT-SACT, H-Oil, LC-Fining, and the like. Among these processes, the combined hydrocracking process is the most effective process for processing heavy petroleum feedstock such as tar obtained after fractional distillation of heavy uraer crude oil.

However, each of these processes has problems associated with processing the residual hydrocracked product to obtain the desired and high quality product.

For the combined hydrocracking process, document CA 2157052 discloses the use of a solidified residue from liquid phase cracking, which residue contains coal additives and has been subjected to a separation and subsequent vacuum distillation step, which residue is used as a binder to be added to the coal for the production of metallurgical coke.

However, although described for residues from processing of Arabian light crude oil, this process is not suitable for residues from processing of heavy crude oil, as the high content of heavy hydrocarbons and asphaltenes in these residues will inevitably lead to coking of the equipment and failure to provide the necessary sintering characteristics.

The problem faced by the present invention is to develop an efficient and stable process for processing heavy petroleum feedstocks, such as heavy urale crude oil, which enables valuable products to be obtained from the residues formed by such processing, in particular sintered additives or bitumen products, and streams of heavy vacuum gas oil which can be converted into aromatic light gas oil by any known oil refining and petrochemical processes for increasing the aromatic content, wherein the aromatic light gas oil can in turn be used for processing heavy petroleum feedstocks, thereby amplifying their efficiency and reducing their resource strength.

Disclosure of Invention

The present invention relates to a process for processing a heavy petroleum feedstock, the process comprising:

-hydrocracking the feedstock in a slurry phase (slurry phase hydrocracking (slurry phase hydrocracking, SPH)) comprising the heavy petroleum feedstock and coal additive, followed by separation into a stream of feedstock subjected to SPH and a heavy residue stream, wherein the heavy residue stream is a slurry of unconverted high boiling residue and depleted coal additive;

-hydrocracking the SPH-subjected feedstock in the gas phase, followed by fractionation of the hydrocracked product;

-separating the depleted coal additive and the unconverted high boiling residue by using a solvent;

-feeding the mixture of unconverted high boiling residue and solvent to a vacuum column after the separation step to obtain a separated heavy residue;

-evaporating at least part of the separated heavy residue in an evaporator to obtain a concentrated hydrocracking residue and a heavy vacuum gas oil (heavy vacuum gas oil, HVGO); and

-Using at least part of the HVGO to obtain the solvent.

To obtain this solvent, HVGO may be supplied for catalytic cracking.

Preferably, the HVGO is supplied as a mixture with one or more components from the group consisting of straight run vacuum gas oil, fuel oil from a gas condensate processing unit, and hydrotreated vacuum gas oil to perform catalytic cracking.

In one embodiment of the invention, the catalytic cracking mixture is characterized by the following ratios based on the weight of the mixture:

-10 to 80 hydrotreated vacuum gas oil and/or fuel oil; and

-20 To 90 HVGO and optionally straight run vacuum gas oil.

In one embodiment of the invention, the at least a portion of the HVGO and the separated heavy residue are recycled into the evaporator as a mixture.

In one embodiment of the invention, the heavy petroleum feedstock is characterized by an initial boiling point of 510 ℃ and a density of greater than 1000kg/m ³ at 20 ℃, particularly wherein the heavy petroleum feedstock is tar.

In one embodiment of the invention, the resulting concentrated hydrocracking residue has an ash content of not more than 1.0%, preferably not more than 0.6%.

Preferably, the coal additive used in the SPH step is a carbon material consisting of two size fractions of particles, wherein the average particle size of one of the size fractions (coarse size fraction) is greater than the average particle size of the other size fraction (fine size fraction), wherein the coarse size fraction and the fine size fraction are characterized by different mesoporous volumes.

Preferably, the fine fraction has a mesoporous volume of not less than 0.07cm ³/g and not more than 0.12cm ³/g, and the coarse fraction has a BJH mesoporous volume of not less than 0.12cm ³/g and not more than 0.2cm ³/g, as determined by the Barrett-Joyner-Halenda, BJH method.

Preferably, the carbon material has a BET specific surface area of not less than 230m ²/g and not more than 1250m ²/g, preferably not less than 250m ²/g and not more than 900m ²/g, most preferably not less than 270m ²/g and not more than 600m ²/g.

In one embodiment of the present invention, the solvent used in the step of separating the spent coal additive and the unconverted high boiling residue is aromatic light gas oil from catalytic cracking and comprises at least 80wt.% aromatic hydrocarbons having C8-C16 carbon atoms.

Preferably, the evaporation takes place in a double jacketed thin film evaporator heated by flue gas.

Preferably, the separated heavy residue is fed to the thin film evaporator through a header comprising discrete feed points.

Preferably, the evaporation is performed from a film having a constant thickness, wherein the film thickness is not more than 1.5mm, preferably not more than 1.3mm, even more preferably the thickness is in the range of 1.1 to 1.2 mm.

Preferably, a flow intermediate redistributor is provided, which is a circular metal plate mounted along the height of the thin film evaporator.

Preferably, the circulation of the bottom product in the thin film evaporator is provided by tangential introduction.

The evaporation process may be carried out under atmospheric oxygen supply to enhance the process.

Preferably, the process of evaporation from the constant thickness film is carried out for a specific time at a temperature and evaporation pressure that ensures such a product: the product has a ring and ball softening point of at least 105 ℃ of the concentrated residue with a mass fraction of volatile components in the concentrated hydrocracking residue of no more than 60%.

HVGO can be produced by condensing vapor from the thin film evaporator using a refrigerator, followed by collection of distillate.

In one aspect, the claimed invention relates to a concentrated hydrocracking residue produced by the process of the present invention characterized by an ash content of not greater than 1.0%, preferably not greater than 0.6%, and a ring and ball softening point of not less than 105 ℃.

In another aspect of the invention, there is provided the use of this particular concentrated residue as a sintering additive in the preparation of various forms of coke (including metallurgical coke, foundry coke, molded coke) or in the production of carbon-based products, industrial products, carbon electrodes (including anodes and cathodes in galvanic processes in aluminum production), and self-sintering electrodes.

According to yet another aspect of the invention, there is provided the use of the concentrated residue for the production of petroleum coke, anode coke.

Drawings

FIG. 1 is a flow chart of the claimed method.

Fig. 2 is a cross-sectional view of the thin film evaporator housing.

Fig. 3 is a full view of the feed distributor of the thin film evaporator.

Fig. 4 is a full view of the rotor with mounted flights in the thin film evaporator.

FIG. 5 is a schematic diagram of a feedstock redistributor.

Detailed Description

Fig. 1 shows a flow chart of a process for processing a heavy petroleum feedstock according to the present invention.

A slurry of a heavy petroleum feedstock and coal additives (typically added in an amount of 1% to 2% by weight based on the heavy petroleum feedstock) is fed into a slurry phase hydrocracking (slurry phase hydrocracking, SPH) reactor to perform SPH step 1. Special cases of heavy petroleum feedstocks include tar, atmospheric tower (atmospheric column) bottoms, vacuum tower (vacuum column) bottoms, heavy recycle gas oil, shale oil, liquid fuel from coal, crude oil bottoms, distilled crude oil, and heavy bitumen crude oil from oil sands.

An exemplary SPH process is the process described in RU patent No. 2707294.

A hydrogen-containing gas, particularly hydrogen, is used in SPH step 1 and is supplied to a slurry of preformed heavy oil tar (particularly tar) and a coal additive for adsorbing heavy hydrocarbons (such as asphaltenes). The additive comprises a porous carbon material having two different particle size compositions (coarse fraction and fine fraction), wherein the fine fraction has a particle size of 0.063 to 0.4mm and the coarse fraction has a particle size of 0.4 to 1.2mm. The SPH process may be carried out in one or more reactors. The amount of this additive depends on the reactor productivity and the number of reactors in the first SPH step-the lower the productivity and the smaller the number and volume of reactors, the smaller the size of the additive. Carbon materials that can be used to produce coal additives for combined hydrocracking are known in the art. They include, for example, firewood coal, activated lignite, activated coal, in particular anthracite.

In SPH step 1, hydrocarbons are decomposed and saturated in a hydrogen atmosphere, while asphaltenes and metals (such as Ni, V, fe, etc.) that are catalyst poisons for gas phase hydrocracking are adsorbed on the coal additive.

About 95% of the hydrocarbons are converted into a gaseous, partially hydrogenated mixture of hydrocarbons, which are the lighter components of liquid phase hydrocracking products, such as H ₂S,NH₃,H₂O,C₁、C₂、C₃、C₄、C₅ hydrocarbons, naphtha, diesel fractions, and vacuum gas oils.

The remaining approximately 5% of the material is a slurry consisting of the coal additive with adsorbed asphaltenes and metals and unconverted high boiling residues, which are mixtures of mainly high boiling hydrocarbons with an initial boiling point above 525 ℃. For the purposes of this patent, this coal additive from step 1 will be referred to as a spent coal additive after adsorbing asphaltenes and metals.

The product obtained in step 1 (SPH) is separated in a separation step 2 into gaseous products and a slurry of unconverted high boiling residues and depleted coal additive. The separation section is located between the SPH section and the gas phase hydrocracking section.

The gaseous product is supplied to undergo the gas phase hydrocracking of step 3, followed by fractionation of the resulting product stream to obtain a light oil product.

A slurry of unconverted high boiling residue and spent coal additive is fed to a wash section to carry out separation step 4.

Preferably, the additive is characterized by a mesoporous volume (i.e., a total pore volume greater than 25%) that is sufficiently large, i.e., pores having a pore diameter in excess of 10nm, to achieve more efficient adsorption of asphaltenes. Such pores allow the heavy hydrocarbons of macromolecules to enter and deposit on the pore surfaces.

Developed specific surface areas (at least 230m ²/g), especially when such specific surface areas are provided by a large number of mesopores, further contribute to the broad "liquid-solid" phase boundaries on which cracking reactions take place, and the more developed surfaces facilitate the entry of asphaltenes into the pores, thereby minimizing the risk of asphaltenes "escaping" due to the complex pore geometry, i.e. acting as a kind of pore "lock" for asphaltenes.

However, not all asphaltenes in the feedstock (including the carbonaceous green and carbonaceous pitch formed by the secondary condensation/polymerization reaction during hydrocracking) are adsorbed by the coal additive. About 10wt.% of these materials remain as a dispersed phase surrounded by a dispersion medium, which results in an imbalance between asphaltenes on the one hand and aromatic hydrocarbons that disperse the asphaltenes and on the other hand, and saturated hydrocarbons that contribute to the precipitation of the asphaltenes. As a result, the unconverted high boiling residue becomes generally unstable, causing it to segregate and form challenging deposits in the form of asphaltene sediment. These deposits adversely affect the operation of the equipment, leading to wear, downtime, and complications in cleaning and replacing equipment susceptible to such deposits.

In view of this, it is desirable to increase the content of aromatic hydrocarbons in the dispersion medium, thereby preventing precipitation of those asphaltenes not adsorbed by the additive.

In addition, unconverted high boiling residue is a fairly viscous liquid and the stream it supplies for further processing may entrain spent coal additives along with asphaltenes and metals adsorbed thereon. Therefore, it is necessary to effectively reduce the viscosity of the unconverted high boiling residue in order to separate the spent coal additive therefrom. By effectively reducing viscosity herein is meant creating a viscosity and density gradient between the unconverted residue and the depleted coal additive such that the created gradient facilitates separation of the depleted additive. In view of these factors, aromatic solvents that are free of paraffins, which are natural precipitants for asphaltenes, are suitable for reducing viscosity while preventing segregation.

The process of separating the spent coal additive from the unconverted high boiling residue is carried out in a separation step4, in which the additive is washed with solvent in a washing section.

Preferably, the washing section is a mating section consisting of a mixing tank and a separation tank. The number of mating segments may vary depending on the desired production rate and the efficiency required for separation of the depleted additive. In the mixing tank, a suspension of the coal additive and unconverted high boiling residue is mixed with a solvent.

The separation of the spent coal additive from the unconverted high boiling residue occurs in a separation tank equipped with, for example, a cyclone unit, decanter, or flotation device as a mixture with the solvent and a portion of the unconverted high boiling residue; the separation is performed, for example, using centrifugal force, gravity, or flotation.

Suitable solvents for washing the spent coal additive section may include heavy reformate, heavy gas oil from catalytic cracking, and toluene.

Preferably, in the present invention, the more efficient separation of the depleted additive is provided by using aromatic light gas oils from petroleum processing and petrochemical processes with the aim of increasing the aromatic content by increasing the aromatic C8-C16 hydrocarbon content to greater than 80wt.% (especially by catalytic cracking).

Such a solvent allows to effectively reduce the viscosity of the unconverted high boiling residue and eliminate asphaltene precipitation, since it increases the fraction of aromatic compounds in the dispersion system and is free of paraffins, which are natural precipitants for asphaltenes. Thus, the provided hydrocarbon content (comprising greater than 80wt.% aromatic hydrocarbons) in the aromatic light gas oil provides better separation of the coal additive from unconverted high boiling residues.

This provides the further advantage that if the product obtained from said residue purified from the depleted coal additive is used as a sintering additive for carbon products, the ash content of such sintering additive will be significantly reduced.

Light aromatic gas oils from petroleum processing are commonly used to produce diesel fuel and therefore their use as solvents is impractical and unprofitable. Thus, as described below, in order to provide additional light aromatic gas oils, the present invention proposes the use of heavy vacuum gas oils produced by the process of the present invention. The use of this additional amount as solvent in the separation step not only increases efficiency but also reduces the resource strength of the process. Thus, the present invention provides an additional raw material source for the production of light aromatic gas oils, at least a portion of which is advantageously used as solvent according to the present invention. The description of the process that follows will clarify the characteristics of providing the source of the feedstock.

It should be noted that as the coal additive adsorbs asphaltenes more effectively, less asphaltenes remain in the unconverted high boiling residue, thus reducing the need for aromatic solvent in step 4 to separate the depleted coal additive from the unconverted high boiling residue. Furthermore, the enhanced separation of the depleted additive from the unconverted high boiling residue in separation step 4 helps to make the unconverted high boiling residue more stable in the oil dispersion system.

After the washing section, spent coal additive is extracted from the process and the separated unconverted high boiling residue continues as a mixture with solvent into a vacuum column for step 5, wherein the solvent is extracted from the separated unconverted high boiling residue, among other processes.

The products obtained from the vacuum distillation process are:

-a solvent separated during vacuum distillation;

-light vacuum gas oil (light vacuum gas oil, LVGO) and vacuum purified gas oil (vacuum purified gas oil, VPGO), and

-An isolated heavy residue, which is tar-hydrocracking residual product (tar-hydrocracking residual product, THRP).

The resulting THRP is uniform in composition, viscous, low in ash, has a fairly low sulfur content due to the hydrocracking step, and is benzopyrene-free (unlike coal tar pitch), which is important to the environment. Such a combination of characteristics is possible due to several factors:

1. Residual products after distillation using petroleum feedstock (for a combined hydrocracking process in a hydrogen environment) are utilized to reduce sulfur levels and avoid benzopyrene in the process products, particularly in the residual products;

2. coal additives with high mesoporous content are adopted, so that asphaltenes of raw materials are effectively adsorbed; and

3. The solvent is applied in the additive wash stage to ensure optimal removal of spent additive from unconverted high boiling hydrocracking residues before feeding to the thin film evaporator after the vacuum column. This efficient removal of spent additives from the hydrocracking residue can significantly reduce the ash content in the concentrated hydrocracking residue.

The inventors hypothesize that the resulting residue has properties and composition that are advantageous for its use as a feedstock for preparing sintering additives used in the production of metallurgical or foundry coke or electrode blocks in the manufacture of carbon anodes (e.g., for the aluminum industry). This assumption has been verified through a number of experiments.

In addition, the concentrated residue can be used to prepare petroleum coke or anode coke, such as in a delayed coking unit.

Preferably, the residue is concentrated in an evaporator. From the prior art, it is known that devices for concentrating highly viscous media are, for example, devices with natural circulation or devices in which the evaporation process takes place from the membrane.

The best results were obtained using a thin film evaporator.

The particular bottoms (separated heavy residue) is directed to a Thin Film Evaporator (TFE) for evaporation step 6 for concentration.

In this case, the main point for the quality of the sintering additive and distillate is to prevent local overheating of the TFE, which can lead to local coking of the film, with the risk of forming a large volume of coke deposits inside the device. In sintering additives, such coking prone inclusions deteriorate sintering characteristics because the solid carbon fraction remains in the coking material, which loses its sintering characteristics and acts as ballast in the sintering additive composition.

Based on extensive testing, such an apparatus is considered to be most effective for producing sintering additives, i.e. in which the process takes place in a film formed on the inner surface of a stationary housing by rotating the rotor.

The main element of these devices is a housing with a coaxially mounted rotor and distribution device. The film is produced on the vertical surface of the housing by using a rotor with a distribution blade mounted thereon.

In order to prevent certain adverse effects, namely the formation of localized coking, the design was modified as follows. TFE is equipped with a double jacket heated by flue gases that are fed into the outer jacket and then distributed into the inner jacket. As depicted in fig. 2, this double jacket configuration ensures a uniform distribution of flue gas over the entire outer surface of the reactor vessel and avoids localized overheating.

Under otherwise identical conditions, the higher the heating temperature of the feedstock, the better the quality of the sintering additive in terms of the "ring and ball softening temperature (ring and ball softening temperature, R & B)", but the lower its yield becomes. The maximum temperature in the chamber is limited by the likelihood of coke formation and the residence time of the mixture in the evaporator. The temperature is optimally maintained between 400 ℃ and 450 ℃.

The vacuum in the system can significantly reduce the temperature at which the light hydrocarbons begin to vaporize, thus reducing the risk of coking in the released heavy residues. The reduction in pressure facilitates the reduction in the content of volatile components in the sintering additive due to the enhanced evaporation conditions of the intermediate product (or secondary source resin). The pressure is preferably set between minus 90 and minus 100 kPa.

The residence time of the feedstock in the apparatus is calculated based on the conditions required to obtain a product having a residual mass fraction of volatile components of no more than 60% and preferably ranges between 20 and 30 seconds.

Desirably, the process is performed from a film having a thickness of no greater than 1.5mm, most preferably no greater than 1.2mm, and in the range of 1.1 to 1.15. Evaporating the material from the thin film of this particular thickness on the evaporator surface ensures high heat and mass transfer rates. Furthermore, the film thickness directly influences the quality of the resulting sintering additive, in particular the reduced amount of volatile substances and the enhanced sintering ability. In addition, films with a specific thickness according to the claimed method reduce the risk of coking. As the film thickness increases, there is a risk of coking on the wall, and the squeegees may not be able to cope with, causing the rotor to seize. If the thickness is less than a certain value, the evaporation becomes too severe, impeding adequate drainage of the residue and leading to local build-up, which in turn leads to coking.

The feedstock (a stream of separated heavy residues from a vacuum distillation column) is fed to the top of the reactor through a distribution device as shown in fig. 3 via discrete feed points evenly spaced along the diameter of the distribution device. This input ensures further protection of the equipment from coking over time and eliminates coking inclusions in the resulting sintering additive.

As shown in fig. 4, an even distribution of the raw material along the height of the device is ensured by the working elements (blades) of the rotor being distributed in the form of helical segments along the height of the rotor.

Flow redistributors are provided along the height of the apparatus, which are circular metal plates mounted along the height of the reactor. The plates have grooves for the flights. The purpose of this is to ensure a uniform application of the feed stream to the walls along the height of the reactor, thus preventing stagnation areas from occurring. Such an arrangement is shown in fig. 5.

The process may be enhanced by supplying atmospheric oxygen to the lower portion of TFE at a rate of 40-50L/h, preferably 44-47L/h, even more preferably 45L/h, depending on the feedstock composition and the requirements necessary for sintering additive quality. In this case, the process temperature may be reduced to 210 ℃ to 240 ℃.

Tar-hydrocracking concentrated residue (tar-hydrocracking concentrated residue, THCR) was extracted from the TFE bottom. In some embodiments, continuous circulation at TFE bottom THCR is achieved by introducing it tangentially into the lower portion of TFE.

TFE overhead product (distillate vapor) is withdrawn from the reactor and condensed in a refrigerator. The condensed distillate is a Heavy Vacuum Gas Oil (HVGO) at least a portion of which is subjected to processing step 7, particularly catalytic cracking, to increase the aromatic content to produce a solvent for the additive wash stage.

At least a portion of the HVGO is supplied for catalytic cracking in a mixture with one or more of the following components: straight run vacuum gas oil, hydrotreated vacuum gas oil from a combined hydrocracking unit, and fuel oil. The ratio (wt.%) between these four feed streams to the catalytic cracking unit can vary over a wide range:

10 to 80 (hydrotreated vacuum gas oil from a combined hydrocracking unit and/or fuel oil from a gas condensate processing unit); and

20 To 90 of non-hydrotreated feedstock (HVGO and optionally straight run vacuum gas oil).

It is important to recognize that an increase in the fraction of the feedstock that is not hydrotreated results in a higher yield of light gas oil from catalytic cracking. However, in order to extend catalyst life, it is suggested to dilute the non-hydrotreated feedstock with the hydrotreated feedstock. In addition, the fraction of the feedstock that is not hydrotreated should not be increased, as this may have an adverse effect on the quality of the main product, the catalytic product (which is subsequently used to produce motor gasoline).

In the case of using fuel oil, it is important to note that straight-run fuel oil obtained from petroleum by distillation cannot be used for catalytic cracking in the conventional sense. For catalytic cracking, fuel oil obtained from a gas condensate processing unit (gas condensate processing unit, GCPU) is used, because in this case its properties are similar to vacuum gas oil obtained from petroleum by distillation, i.e. GCPU fuel oil is free of heavy fractions (tar).

The TFE bottom product is a concentrated hydrocracking residue that can be used as a sintering additive for producing metallurgical coke.

The concentrated residue may be subjected to additional treatment (e.g., in a delayed coking unit) to obtain petroleum coke or anode coke.

Modifications implemented in the integrated hydrocracking process enable the integrated hydrocracking unit to operate stably and uninterruptedly, resulting in the production of enhanced quality products. These modifications facilitate sustained conversions up to 95% while also effectively solving the difficulties associated with processing the residual hydrocracked product into marketable products.

In the context of the present invention, the operational stability of a combined hydrocracking unit means continuous operation in a given mode at a given production rate.

Examples:

a heavy petroleum feedstock (which is tar obtained after distillation of low boiling fractions from heavy urarel crude oil and has an initial boiling point of 510 ℃ and a density of greater than 1000kg/m ³ at 20 ℃) was mixed with 1.5wt.% (based on the mass of tar) of a coal additive having the following two particle size compositions: coarse fraction having a particle size of about 1mm and fine fraction having a particle size of about 0.3 mm. Coarse fraction and fine fraction are characterized by different mesoporous volumes: the fine fraction of BJH mesoporous volume is at least 0.07cm ³/g and the coarse fraction of BJH mesoporous volume is at least 0.12cm ³/g for more efficient adsorption of asphaltenes with 40 to 90nm molecular size for tar from Ula crude oil. The coal additive has a BET specific surface area of not less than 230m ²/g and not more than 1230m ²/g.

The feedstock in slurry form is supplied to the SPH, wherein hydrogen is supplied at a temperature of 430 ℃ to 470 ℃ and a pressure of 18 to 22 MPa. The mixture of coal additive, tar and gas was passed through three SPH reactors. Resulting in a resulting mixture consisting of gaseous products and a slurry comprising spent coal additives and unconverted high boiling residues. The mixture is supplied to a separation step, after which a gaseous stream is supplied to gas phase hydrocracking, and the slurry is supplied to an additive washing section consisting of a mixing tank and a cyclone separation tank.

The slurry of unconverted high boiling residue together with depleted additives of solids (flow rate of 15-20 tons/hour, temperature of about 420 ℃ and pressure of not more than 0.3 MPa) is mixed with aromatic light gas oil from catalytic cracking (flow rate of 30-35 tons/hour, temperature of about 220-260 ℃) in a mixing tank. The pressure in the mixing tank is exceeded by 0.15 to 0.35MPa and regulated by a control valve system to avoid excessive evaporation of the solvent.

The stream is then fed to a separation tank equipped with a cyclone unit, wherein the depleted additive is separated by centrifugal force from unconverted high boiling residue mixed with aromatic light gas oil from catalytic cracking.

After the washing section, spent coal additives are extracted from the process and the separated unconverted high boiling residue, heated to a temperature of not more than 385 ℃ and mixed with aromatic light gas oil from catalytic cracking, is supplied to a vacuum column. At the top of the vacuum column, the vacuum is 10 to 150mmHg, preferably 40 to 70mmHg, even more preferably 10 to 30mmHg, wherein the pressure difference between the bottom portion of the vacuum column and the lower layer of packing (including the "blind (blind)" plate) is not more than 15mmHg, and the temperature at the bottom of the vacuum column is not more than 305 ℃.

The products obtained from the vacuum distillation process are:

-light vacuum gas oil (light vacuum gas oil, LVGO) and vacuum purified gas oil (vacuum purified gas oil, VPGO); and

-An isolated heavy residue, which is tar-hydrocracking residual product (tar-hydrocracking residual product, THRP).

The heavy residue (bottom residue) obtained by the above process has the following physical and mechanical properties:

TABLE 1

The bottom residue (separated heavy residue) described above is fed to a thin-film evaporator (TFE) via a manifold comprising discrete feed points for concentration.

The temperature in the reactor was maintained at 400 ℃. The pressure in the reactor was maintained at minus 95kPa.

The film thickness was 1.12mm and was constant along the height of the device.

For the bottom residue and the specific film thickness, the residence time of the feedstock in the apparatus was 20 seconds.

The distillate obtained by the process of the invention has the following characteristics:

TABLE 2

The concentrated tar-hydrocracking residue produced by the proposed process has the characteristics given in table 3:

TABLE 3 Table 3

These parameters enable the use of THCR as a sintering additive to produce metallurgical coke, foundry coke, or anodes for the aluminum industry, which have excellent sintering characteristics similar to those of coal tar pitch.

As a result of industrial testing of the claimed process, the feedstock (particularly tar) achieves a production rate of at least 2,600,000 tons/year.

Claims (26)

1. A method for processing a heavy petroleum feedstock comprising:

Hydrocracking a feedstock in a slurry phase (slurry phase hydrocracking SPH), the slurry phase comprising a heavy petroleum feedstock and a coal additive, followed by separation into a stream of feedstock subjected to SPH and a heavy residue stream, wherein the heavy residue stream is a slurry of unconverted high boiling residue and depleted coal additive;

-hydrocracking the SPH-subjected feedstock in the gas phase, followed by fractionation of the hydrocracked product;

-separating the depleted coal additive and the unconverted high boiling residue by using a solvent;

-feeding the mixture of unconverted high boiling residue and solvent to a vacuum column after the separation step to obtain a separated heavy residue;

-evaporating at least part of said separated heavy residue in an evaporator to obtain a concentrated hydrocracking residue and a heavy vacuum gas oil HVGO; and

-Using at least part of the HVGO to obtain the solvent.

2. The method of claim 1, wherein the at least a portion of the HVGO is catalytically cracked to produce the solvent.

3. The method of claim 1, wherein the HVGO is supplied as a mixture with at least one of the following components for catalytic cracking: straight run vacuum gas oil, fuel oil, and hydrotreated vacuum gas oil.

4. A process according to claim 3, wherein the mixture for catalytic cracking is characterized by the following ratio based on the weight of the mixture:

-10 to 80 hydrotreated vacuum gas oil and/or fuel oil; and

-20 To 90 HVGO and optionally straight run vacuum gas oil.

5. The method of claim 1, wherein at least a portion of the HVGO and the separated heavy residue are supplied to the evaporator as a mixture for recycling.

6. The process according to claim 1, wherein the heavy petroleum feedstock is characterized by an initial boiling point of 510 ℃ and a density of greater than 1000kg/m ³ at 20 ℃, and in particular wherein the heavy petroleum feedstock is tar.

7. The process according to claim 1, wherein the concentrated hydrocracking residue has an ash content of not more than 1.0%, preferably not more than 0.6%.

8. The method of claim 1, wherein the coal additive used in the SPH step is a carbon material composed of two size fractions of particles, wherein the average particle size of a coarse fraction is greater than the average particle size of a fine fraction, and wherein the coarse fraction and the fine fraction are characterized by different mesoporous volumes.

9. The method of claim 8, wherein the fine fraction has a mesopore volume of not less than 0.07cm ³/g and not greater than 0.12cm ³/g as determined by the barrett-gahner-halenda-BJH method, and the large fraction has a BJH mesopore volume of not less than 0.12cm ³/g and not greater than 0.2cm ³/g.

10. The method according to claim 8, wherein the carbon material has a BET specific surface area of not less than 230m ²/g and not more than 1250m ²/g, preferably not less than 250m ²/g and not more than 900m ²/g, most preferably not less than 270m ²/g and not more than 600m ²/g.

11. The process of claim 1, wherein the solvent is an aromatic light gas oil from catalytic cracking comprising at least 80wt.% aromatic hydrocarbons having C8-C16 carbon atoms.

12. The method of claim 1, wherein the evaporating occurs in the evaporator, which is a thin film evaporator.

13. The method of claim 12, wherein the thin film evaporator has a double jacket heated by flue gas.

14. The method of claim 12, wherein the separated heavy residue is fed to the thin film evaporator through a header comprising discrete feed points.

15. A method according to claim 12, wherein the evaporation is performed from a film having a constant thickness, wherein the film thickness is not more than 1.5mm, preferably not more than 1.3mm, even more preferably the thickness is in the range of 1.1 to 1.2.

16. The method of claim 12, wherein an intermediate flow redistributor is provided along the height of the thin film evaporator, the intermediate flow redistributor being a circular metal plate mounted along the height of the reactor.

17. The method of claim 12, wherein the thin film evaporator comprises a bottom portion for recycling the bottom product of the thin film evaporator by introducing the bottom product into the bottom portion of the thin film evaporator tangentially.

18. The method of claim 1, wherein the evaporation process is performed under an oxygen supply of air.

19. The method of claim 1, wherein the process of evaporating from a film of constant thickness is carried out at a specific temperature and pressure for a specific time such that the volatile components evaporate to a mass fraction of volatile components in the concentrated residue of not more than 60% and the concentrated residue has a ring and ball softening point of not less than 105 ℃.

20. The method of claim 1, wherein the HVGO is obtained by condensing vapor from a thin film evaporator using a refrigerator, followed by collecting distillate thus obtained.

21. A method according to claim 3, wherein the fuel oil is fuel oil from a gas condensate processing unit.

22. Concentrated hydrocracking residue obtained by the process according to any one of claims 1 to 21, which is used as sintering additive for carbon products, characterized in that the ash content is not more than 1.0% and the ring and ball softening point is not less than 105 ℃.

23. Use of the concentrated residue according to claim 22 as sintering additive for the preparation of coke, more particularly metallurgical coke, foundry coke, in particular molded coke.

24. Use of the concentrated residue according to claim 22 as sintering additive for the production of carbon electrodes, such as for galvanic processes, in particular for the production of anodes or cathodes of aluminum.

25. Use of the concentrated residue according to claim 22 as sintering additive for the preparation of self-sintered electrodes.

26. Use of the concentrated residue according to claim 22 for the preparation of petroleum coke or anode coke.