CN1729275A - Process for the conversion of heavy feedstocks such as heavy crude oil and distillation residues - Google Patents

Abstract

The present invention provides a process for the conversion of heavy feedstocks selected from heavy crude oils, distillation residues, heavy oils coming from catalytic treatment, thermal tars, oil sand bitumens, various kinds of coals and other high-boiling feedstocks of a hydrocarbon origin known as black oils, by the combined use of the following three process units: hydroconversion with catalysts in slurry phase (HT), distilla tion or flash (D), deasphalting (SDA), comprising the follow ing steps: mixing at least part of the heavy feedstock and/or at least most of the stream containing asphaltenes obtained in the deasphalting unit with a suitable hydrogenation catalyst and sending the mixture obtained to a hydrotreatment reactor (HT) into which hydrogen or a mixture of hydrogen and H2S is charged; sending the stream containing the hydrotreatment reaction product and the catalyst in dispersed phase to one or more distillation or flash steps (D) whereby the different frac tions coming from the hydrotreatment reaction are separated; recycling at least part of the distillation residue (tar) or liquid leaving the flash unit, containing the catalyst in dispersed phase, rich in metal sulfides produced by demetallation of the feedstock and possibly coke, to the deasphalting zone (SDA) in the presence of solvents, optionally also fed with at least a fraction of the heavy feedstock, obtaining two streams, one consisting of deasphalted oil (DAO) and the other containing asphaltenes, characterized in that the stream containing the hydrotreatment reaction product and the catalyst in dispersed phase, before being sent to one or more distillation or flash steps, is subjected to a high pressure separation pre-step in order to obtain a light fraction and a heavy fraction, the heavy fraction alone being sent to said distillation step(s) (D).

Description

Process for the conversion of heavy feedstocks such as heavy crude oil and distillation residues

The present invention relates to a method for converting heavy feedstocks, including heavy crude oil, oil sand bitumen, distillation residues and various coals, by using a properly connected mixture consisting of fresh feedstock and conversion products Three main process units with feed streams: hydroconversion of heavy feedstock with dispersed phase catalyst unit, distillation unit and deasphalting unit, a unit that treats the purge stream from the deasphalting unit to reduce its presence, The feedstock is further upgraded to an oil product and at least a portion of the recovered catalyst is recycled to the hydroprocessing reactor.

The conversion of heavy crude oil, oil sands bitumen, and petroleum residues into liquid products can be achieved essentially in two ways: one using only the heated hand zone, and the other through a hydrotreating step.

Current research is mainly focused on hydroprocessing, since the thermal treatment process has some problems with the disposal of by-products, especially coke (obtained in quantities greater than 30% by weight relative to the feedstock), and the poor quality of the conversion products.

Hydroprocessing is the treatment of feedstock in the presence of hydrogen and a suitable catalyst.

Hydroconversion processes currently on the market use fixed-bed reactors or ebullated-bed reactors and usually consist of one or more transition metals (Mo, W, Ni, Catalysts composed of Co, etc.).

Fixed-bed processes have considerable problems in handling exceptionally heavy feedstocks with high heteroatom, metal and asphaltene content, since these impurities can deactivate the catalyst rapidly.

A variety of ebullating bed processes have been developed and commercialized for processing these feedstocks, their performance is interesting, but they are complex and expensive.

Hydroprocessing processes operating with catalysts in the form of dispersed phases may offer an attractive solution to the disadvantages encountered with fixed or ebullated bed processes. In fact, slurry processes are able to combine the advantages of great feedstock flexibility with high performance in terms of conversion and upgrading, making them simpler in principle from a process point of view.

The characteristic of the slurry process is that the catalyst particles exist in the form of small average particle size and can be effectively dispersed in the medium, so the hydrogenation process is simpler and plays a greater role in all positions of the reactor. The amount of coke generated is greatly reduced, and the quality of the modified raw material is higher.

The catalyst can be introduced in the form of a powder or an oil-soluble precursor of sufficiently small size. In the latter case, the active form of the catalyst (usually a metal sulfide) is formed in situ during its reaction or after appropriate pretreatment by means of thermal decomposition of the compounds used.

The metal fraction of the dispersed phase catalyst is typically one or more transition metals (preferably Mo, W, Ni, Co or Ru). Molybdenum and tungsten have more satisfactory properties than nickel, cobalt or ruthenium and even vanadium and iron (N. Panariti et al., Appl. Catal. A: Gen. 2000, 204 , 203).

Although the use of dispersed phase catalysts solves most of the problems listed in the above process, there are still some disadvantages related to the lifetime of the catalyst itself and the quality of the resulting product.

In fact, the conditions of use of these catalysts (type of precursor, concentration, etc.) are extremely important from both an economic point of view as well as environmental impact.

Catalysts can be used in low concentrations (hundreds of ppm) in a "single-pass" process layout, but in this case modification of the reaction product is usually insufficient (A. Delbianco et al., Chemtech, November 1995, 35). When operating with very high activity catalysts (such as molybdenum) and high catalyst concentrations (thousands of ppm metals), the resulting product is of much better quality, but it is necessary to recycle the catalyst.

The catalyst leaving the reactor can be recovered by separating it from the hydrotreated product (preferably obtained from the bottom of the distillation column downstream of the reactor) by conventional methods such as decantation, centrifugation or filtration (US-3240718, US-4762812). A portion of the catalyst is recycled back to the hydrogenation process without further treatment. However, catalyst recovered using known hydroprocessing methods is generally less active than fresh catalyst, and appropriate regeneration steps are necessary to restore catalytic activity and to recycle at least a portion of said catalyst to the hydroprocessing reactor. Furthermore, these methods of catalyst recovery are expensive and extremely complicated from a process point of view.

All of the above hydroconversion processes are capable of higher or lower conversion levels depending on the feedstock and the type of process used, but in any case the unconverted residue (here referred to as tar) produced at the limit of stability depends on the It can vary from 15% to 85% of the starting material. The product is used to produce fuel oil, bitumen or as a feedstock for gasification processes.

In order to increase the overall conversion level of the resid cracking process, various schemes have been proposed which include the step of recycling more or less large amounts of tar in the cracking unit. In the hydroconversion method that adopts catalyst to be dispersed in slurry phase, the circulation of tar makes catalyst be recovered, and for this reason, the same applicant has described a kind of while obtaining high-quality product and not producing residual oil (no residual oil) Residue refinery) conditions, the recovered catalyst is recycled to the hydrotreating reactor without additional regeneration steps.

This method includes the following steps:

Mixing heavy crude oil or distillation residue with a suitable hydrogenation catalyst and feeding the resulting mixture into a hydrotreating reactor filled with hydrogen or a mixture of hydrogen and _H2S ;

Send the stream containing the hydroprocessing reaction product and the catalyst in the dispersed phase state to the distillation zone to separate the volatile fraction (naphtha or gas oil);

The high boiling fraction from the distillation step is fed to the deasphalting step, thus producing two streams, one comprising deasphalted oil (DAO) and the other comprising asphaltenes, catalyst in dispersed phase state and possibly coke and enriched in metals from the original raw material;

• Recycle at least 60%, preferably at least 80%, of the metal-rich stream comprising asphaltenes, catalyst in dispersed phase state and possibly coke to the hydrotreatment zone.

As described in patent application IT-MI2001A-001438, it was later found that, in the case of the above-mentioned processes, the upgrading of heavy crude oil or oil sands bitumen into complex hydrocarbon mixtures for further conversion into distillates When processing raw materials, different process layouts are available.

The heavy feedstock conversion process described in patent application It-MI2001A-001438 uses the following three process units in combination: a hydroconversion unit (HT) with the catalyst in the slurry phase, a flash or distillation unit (D), a deasphalting unit ( SDA), characterized in that the three units start operating with a mixed stream of fresh raw material and recycle material, using the following steps:

Sending at least a portion of the heavy feedstock to a deasphalting zone (SDA) in the presence of a solvent to produce two streams, one comprising deasphalted oil (DAO) and the other comprising asphaltenes;

Mixing the asphaltenes stream with the remainder of the heavy feedstock not sent to the deasphalting zone and a suitable hydrogenation catalyst and sending the resulting mixture to a hydrotreating reactor (HT) charged with hydrogen or a mixture of hydrogen and _H2S );

Sending the stream containing the product of the hydroprocessing reaction and the catalyst in the dispersed phase state to one or more distillation or flash distillation steps (D), thereby separating the volatile fraction, which contains gases, stones, Naphtha and gas oil;

At least 60% and preferably at least 80% of the distillation residue (tar) or liquid leaving the flash unit comprising catalyst in dispersed phase state, metal-rich sulfides from the demetallization step of the feedstock and possibly coke and various carbonaceous residues % More preferably at least 95% is recycled to the deasphalting zone.

Flushing of the asphaltene stream leaving the deasphalting area (SDA) is usually required to ensure that these elements do not accumulate too much in the hydrotreating reactor and, in the event of catalyst deactivation, to remove a portion of the catalyst and replace it with fresh catalyst. This is generally unnecessary when the catalyst retains its activity for a long period of time, but when flushing is necessary for the reasons mentioned above, it is clear that some catalysts must be discarded even if they are far from completely deactivated. Furthermore, although the amount of purge streams (0.5-4% relative to feedstock) is extremely limited compared to other hydrotreating processes, they still present considerable utilization or disposal problems.

When it is necessary to use the heavy fraction of the complex hydrocarbon mixture (distillation column bottoms) produced by the process as feedstock for a catalytic cracking unit carrying out simultaneous hydrocracking (HC) and fluid catalytic cracking (FCC), the The above application is particularly applicable.

The combination of catalytic hydrogenation unit (HT) and extraction process (SDA) enables the production of deasphalted oil with low content of impurities (metals, sulfur, nitrogen, carbonaceous residues), which can be more easily processed in the catalytic cracking process. be processed in.

However, another aspect to consider is that the naphtha and gas oil directly produced by the hydrotreating unit still contain many impurities (sulphur, nitrogen...) which must in any case be reprocessed in order to obtain the final product.

It has now been found that the two processes described in patent application IT-MI2001A-001438 and patent application IT-95A001095 (incorporated by reference in their entirety into this patent application) can be processed by inserting an additional flush stream solids fraction to post-treat the hydrogenation section ) for further improvement.

The purpose of this solid fraction hydrogenation section is to work up the flushing stream in order to significantly reduce its amount, allowing at least a portion of the still active catalyst to be recycled back to the hydrotreatment reactor.

The object of the present invention is to convert heavy feedstocks selected from heavy crude oils, distillation residues, heavy oils from catalytic processing processes, thermal tars, oil sands bitumen, various coals, and other heavy feedstocks derived from hydrocarbon high-boiling feedstocks known as black oils The method of conversion, this method has used following three process units in combination: adopt the hydroconversion (HT) unit of slurry phase state catalyst, distillation or flashing (D) unit, deasphalting (SDA) unit, comprise the following steps:

mixing at least a part of the heavy feedstock and/or at least the majority of the asphaltene-containing stream obtained in the deasphalting unit with a suitable hydrogenation catalyst and sending the resulting mixture to a charge of hydrogen or hydrogen and _H2S Hydrotreating reactor (HT) for the mixture;

- sending the stream containing the product of the hydroprocessing reaction and the catalyst in the dispersed phase state to one or more distillation or flashing steps (D), thereby separating the different fractions from the hydroprocessing reaction;

Recycle at least a portion of the distillation residue (tar) or liquid leaving the flash unit containing catalyst in the dispersed phase state, metal-rich sulphides from the demetallization of the feedstock and possibly coke to the deasphalting area (SDA) in the presence of solvent, either Selecting also at least a portion of heavy feedstock as feed, resulting in two streams, one comprising deasphalted oil (DAO) and the other comprising asphaltenes, the process is characterized in that a portion from the deasphalting section ( SDA) The bitumen-containing stream, known as the purge stream, is sent to a treatment zone with a suitable solvent in order to separate the product into a solid fraction and a liquid fraction, from which the solvent is subsequently removed.

The wash effluent (preferably 0.5-10% by volume of the fresh feedstock) treatment section consists of a solvent (toluene or gas oil or other stream rich in aromatics fraction) deoiling step and a liquid and solid fraction separation step.

At least a portion of said liquid fraction may be sent to:

· "Fuel oil pool", fed as is or after separation of solvent and/or addition of appropriate diluent liquid;

• and/or sent as such to the hydrotreating reactor (HT).

In some specific cases, solvent and diluent liquid can be the same.

The solid fraction can be treated as such or, more advantageously, sent to a process for the selective recovery of transition metals or metals contained in transition metal catalysts such as molybdenum (nickel and vanadium relative to other metals present in the feed residue ) in order to be able to optionally recycle the transition metal (molybdenum) rich stream back to the hydrotreatment reactor (HT).

Compared with traditional methods, this comprehensive approach has the following advantages:

The number of flushing parts is greatly reduced;

Most of the flushing fraction can be upgraded to fuel oil by separating out metals and coke;

• The amount of fresh catalyst added to the feed to the first hydroprocessing step is reduced since at least a portion of the molybdenum extracted from the selective recovery treatment step is recycled.

The deoiling step is to treat the purge stream, which represents a minimum asphaltenes fraction from the deasphalting section (SDA) of the heavy feedstock first hydrotreater, using solvents that bring the maximum possible amount of organic compounds into the liquid phase Instead, metal sulphides, coke, and more refractory carbonaceous residues (insoluble in toluene or similar products) remain in the solid phase.

Given the potential for spontaneous combustion of metallic fractions under very dry conditions, it is reasonable to operate in an inert atmosphere containing as little oxygen and moisture as possible.

Various solvents are advantageously used in this deoiling step; among which may be mentioned aromatic solvents such as toluene and/or xylene blends, hydrocarbon feedstocks obtained in the plant such as gas oil produced, or refinery Hydrocarbon feedstocks available in the plant are eg light cycle oil from FCC unit or thermal gas oil from visbreaking/thermal cracking unit.

The operating rate can be increased by increasing the temperature and reaction time within a certain range, but for economic reasons, an excessive increase is not desirable.

The operating temperature depends on the solvent used and the pressure conditions employed; however, the recommended temperature range is 80-150°C; the reaction time may vary from 0.1-12 hours, preferably 0.5-4 hours.

The solvent/flush stream volume ratio is also an important variable to consider and can vary from 1-10 (vol/vol), preferably 1-5, more preferably 1.5-3.5.

Once the intermixing phase of the solvent and rinse streams is complete, the effluent is sent to the separation of liquid and solid phases while maintaining agitation.

The operation method of this step can be one of the commonly used operation methods in industrial practice, such as decantation, centrifugation or filtration.

The liquid phase is then sent to the solvent stripping and recovery section, where the solvent is recycled back to the purge stream first treatment step (deoiling). The remaining heavy fraction is better for the refinery because of the fact that this stream is metal-free and has a lower sulfur content. If, for example, gas oil is used for processing operations, a portion of the gas oil may remain in the heavy product, bringing it into compliance with fuel oil pool specifications.

Alternatively the liquid phase is recycled to the hydrogenation reactor.

The solid portion can be disposed of as is, or otherwise treated to selectively recover catalyst (molybdenum) for recycling back to the hydroprocessing reactor.

In fact, it has been found that by adding a metal-free heavy feed such as a portion of deasphalted oil (DAO) from the plant's own deasphalting unit to the above solid phase and combining said system with acidified water (usually with a mineral acid) ) mixing, almost all of the molybdenum remains in the organic phase, while most of the other metals move into the aqueous phase. The two phases can be easily separated, after which the organic phase is preferably recycled to the hydrotreating reactor.

The solid phase is dispersed in a sufficient amount of organic phase (eg deasphalted oil from the same process) to which acidified water is added.

The ratio of the aqueous phase to the organic phase may vary from 0.3 to 3; the pH value of the aqueous phase may vary from 0.5 to 4, preferably from 1 to 3.

In addition to the purge stream work-up section, there may also be a section for the second treatment hydrogenation of the C ₂ -500° C. fraction, preferably the C ₅ -350° C. fraction, from the high-pressure separation section upstream of the distillation process.

In this case, the stream containing the hydroprocessing reaction product and the catalyst in the dispersed phase state is subjected to a high-pressure separation pretreatment step to obtain light and heavy fractions before being sent to one or more distillation or flash distillation steps , separately sending the heavy fraction to the distillation step (D).

The light fraction from the high pressure separation step can be sent to the hydrotreating section to produce a lighter fraction containing C ₁ -C ₄ gases and H ₂ S and a heavier fraction containing hydrotreated naphtha and gas oil.

The optional insertion of the _C2-500 °C fraction, preferably the _C5-350 °C fraction, in the second aftertreatment hydrogenation section develops the possibility of simultaneously obtaining this fraction and hydrogen at a higher pressure close to the hydrotreating reactor, enabling the following benefit:

It can produce fuels that can meet the most stringent sulfur content specifications (<10-50ppm sulfur) from extremely sulfur-rich oil feedstocks, and other characteristics of diesel engine gas oils such as density, PAH content and sixteenth Improvement in alkane number;

·The produced distillate has no stability problem.

The post-hydrotreatment process on a fixed bed is the pre-separation of the reaction effluent from the hydrotreatment reactor (HT) by means of one or more separators operating at high pressure and temperature. The heavy part taken from the bottom is sent to the main distillation unit, and the part taken from the top, that is, the C ₂ -500°C fraction, preferably the C ₅ -350°C fraction, is sent to the second treatment zone where high-pressure hydrogen exists, and the reactor is a fixed-bed reaction The reactor is equipped with a typical desulfurization/dearomatization catalyst to obtain a product with very low sulfur content and low nitrogen content, low overall density, and an increase in cetane number for the gas oil fraction of interest.

The hydrotreating section usually consists of one or more reactors in series; the product of this system can then be further fractionated by distillation to produce fully desulfurized naphtha and diesel gas oil meeting fuel specifications.

The fixed bed hydrodesulfurization step usually uses a typical gas oil hydrodesulfurization fixed bed catalyst. This catalyst may also be a catalyst mixture or a set of reactors equipped with various catalysts with different properties. Through the following effects, the light gas The fraction is considerably refined: significantly lower sulfur and nitrogen content, higher degree of hydrogenation of the feedstock, resulting in lower density and higher cetane number of the gas oil fraction, while reducing coke formation.

The catalyst usually contains an amorphous part based on alumina, silica, silica-alumina and mixtures of various inorganic oxides, on which the hydrodesulfurized fraction is deposited (in various ways) together with the hydrogenation agent. Catalysts based on molybdenum or tungsten are typical catalysts for this type of operation, in addition to nickel and/or cobalt deposited on an amorphous material support.

The post-treatment hydrogenation reaction is carried out at an absolute pressure slightly lower than the pressure of the first hydrotreatment step, usually 7-14 MPa, preferably 9-12 MPa; the hydrodesulfurization temperature is 250-500 ° C, preferably 280- 420°C; temperature usually depends on the level of desulfurization required. The space velocity is another important variable when the quality of the product obtained is to be controlled: it may be from 0.1 to 5 hours −1 , preferably from 0.2 to 2 hours −1 .

The amount of hydrogen mixed with the feedstock and fed into the stream is between 100-5000 Nm ₃ /m ₃ , preferably 300-1000 Nm ₃ /m ₃ .

A wide range of heavy feedstocks can be processed: they can be selected from heavy crude oil, oil sands bitumen, various types of coal, distillation residues, heavy oils from catalytic processes such as heavy cycle oil from catalytic cracking processes, hydroconversion Process bottoms, thermal tars (e.g. from visbreaking or similar thermal processes) and other high boiling hydrocarbon feedstocks derived from what is commonly referred to in the art as black oil.

As far as common process conditions are concerned, reference may be made to the conditions specified in patent applications IT-MI2001A-001438 and IT-95A001095.

As described in patent application IT-95A001095, all heavy feedstocks can be mixed with a suitable hydrogenation catalyst before being sent to the hydrotreatment reactor (HT), provided that at least 60%, preferably at least 80% of the asphaltene-containing And the stream also containing catalyst in dispersed phase state and possibly coke and enriched in metals from the initial feedstock is recycled to the hydroprocessing zone.

As described in patent application IT-MI2001A-001438, a part of the heavy feedstock and at least mostly asphaltene-containing stream, which also contains catalyst in the dispersed phase state and possibly coke, is mixed with a suitable hydrogenation catalyst and sent to hydrotreatment reactor, while the rest of the heavy feedstock is sent to the deasphalting section.

As described in patent application IT-MI2001A-001438, at least a major part of the asphaltenes-containing stream (consisting essentially of said asphaltenes) is mixed with a suitable hydrogenation catalyst and fed to a hydrotreatment reactor, whereas All heavy feedstock is sent to the deasphalting section.

When only a portion of the distillation residue (tar) or liquid leaving the flash unit is recycled back to the deasphalting section (SDA), at least a portion of the remaining amount of said distillation or flash residue is optionally combined with at least a portion from the deasphalting The asphaltene-containing stream from section (SDA) is sent together to the hydrotreating reactor.

The catalyst used is selected from precursors decomposable in situ (metal naphthenates, metal derivatives of phosphoric acid, metal carbonyls, etc.) or from catalysts based on one or more transition metals such as Ni, Co, Ru, W and Mo The preformed compound of the latter is preferred because of its high catalytic activity.

The catalyst concentration ranges from 300 to 20000 ppm, preferably from 1000 to 10000 ppm, based on the metal or multimetal concentration present in the hydroconversion reactor.

The hydrotreating step is preferably carried out at 370-480°C, more preferably 380-440°C and 3-30 MPa, more preferably 10-20 MPa.

The hydrogen is fed into the reactor, which can be operated in both downflow and upflow modes and is preferably operated in an upflow mode. Said gases can be fed to different sections of the reactor.

The distillation step is preferably carried out under reduced pressure in the range of 0.0001-0.5 MPa, more preferably 0.001-0.3 MPa.

The hydroprocessing step may consist of one or more reactors operating within the conditions specified above. Part of the distillate produced in the first reactor can be recycled to subsequent reactors.

The deasphalting step by means of solvent, hydrocarbon or non-hydrocarbon (eg _C3 - _C6 alkanes or isoparaffins) extraction is usually carried out at a temperature in the range 40-200°C and a pressure in the range 0.1-7 MPa. It can also be composed of one or more sections operating with the same or different solvents, and the solvent recovery step can be carried out in one or more steps under subcritical or supercritical conditions, so that the deasphalted oil (DAO) and residual oil can be further processed Fractionation.

The deasphalted oil (DAO) containing stream can optionally be blended with distillates and used as such as a synthetic crude, or as a feedstock for a fluid catalytic cracking or hydrocracking process.

Preferably, according to the characteristics of the crude oil (metal content, sulfur and nitrogen content, carbonaceous residues), the feeding mode of the whole process can be varied by the following measures: the heavy residue is sent either to the deasphalting unit or to the The hydrotreating unit, or feeding both units at the same time, adjusts:

· The ratio between the heavy residue (fresh feedstock) sent to the hydrotreatment section and the heavy residue to be sent to deasphalting, said ratio is preferably 0.01-100, more preferably 0.1-10, even more preferably 1-5;

· The circulation ratio between the fresh raw material and tar sent to the deasphalting section, said ratio preferably varies between 0.01-100, more preferably 0.1-10;

· The recycle ratio of fresh feedstock to asphaltenes fed to the hydrotreatment section, said ratio can be varied according to the variation of these ratios mentioned above;

• The recycle ratio of tars and asphaltenes fed to the hydrotreatment section, said ratio being variable according to variations of the aforementioned ratios.

This flexibility is particularly useful for fully exploiting the complementary characteristics of the deasphalting unit (reduction of dispersed nitrogen and removal of aromatics) and the hydrogenation unit (high removal of metals and sulfur).

Depending on the type of crude oil, the stability of the stream under study and the quality of the product obtained (also related to the specific downstream processing steps), the fraction of fresh feedstock fed to the deasphalting and hydrotreatment stages can be optimally adjusted.

When the heavy fraction (distillation bottoms) of the complex hydrocarbon mixture produced by the process is used as feedstock to a catalytic cracking unit that simultaneously performs hydrocracking (HC) and fluid catalytic cracking (FCC), the application states that Be applicable.

The combination of catalytic hydrogenation unit (HT) and extraction process (SDA) enables the production of deasphalted oil with low content of impurities (metals, sulphur, nitrogen, carbonaceous residues) and thus easier to process in catalytic cracking process deal with.

A preferred embodiment of the invention is presented below with the aid of the accompanying drawing 1, which should in no way be considered as limiting the scope of the invention itself.

The heavy feedstock (1) or at least a part thereof (1a) is sent to a deasphalting unit (SDA), which is operated by means of solvent extraction.

Two streams are produced from the deasphalting unit (SDA): one is the deasphalted oil (DAO) containing stream (2) and the other is the asphaltene containing stream (3).

Combine the asphaltene-containing stream except the flushing stream (4) with the additional fresh catalyst (5) required to compensate for the loss with the flushing stream (4), and a part of the heavy raw material (1b) that has not been sent to the deasphalting section , a portion of the tar (24) not sent to the deasphalting section (SDA) and optionally a stream (15) from the flushing treatment section (described further below) are mixed to form a stream (6) which is sent to hydrogen charging ( or hydrogen and H ₂ S mixture) (7) of the hydroprocessing reactor (HT). A stream ( 8 ) comprising hydrogenation products and catalyst in dispersed phase state leaves the reactor and is first fractionally distilled in one or more high-pressure-operated separators (HPSep). The overhead fraction (9) is sent to a fixed-bed hydrotreating reactor (HDTC _5-350 ) to produce a light fraction (10) containing C ₁ -C ₄ gas and H ₂ S and hydrogenated naphtha and C ₅ -350°C fraction of gas oil (11). The heavy fraction (12) leaves the bottom of the high pressure separator and undergoes fractionation in a fractionation column (D) to separate the vacuum gas oil (13) from the distillation residue containing dispersed catalyst and coke. This stream, known as tar (14), is recycled to the deasphalting reactor (SDA) in its entirety or in its major part (25) excluding the above-mentioned fraction (24).

The flushing stream (4) can be sent together with the solvent (16) to a hydrotreatment section (deoiling), forming a mixture (17) comprising a liquid fraction and a solid fraction. The mixture is sent to a solids treatment section (solid separation), from which a solid effluent ( 18 ) is separated, as well as a liquid effluent ( 19 ), the latter being sent to a solvent recovery section (solvent recovery). The recovered solvent (16) is sent back to the deoiling section, while the heavy effluent (20) is sent to the fuel oil fractionation process (22) as it is or with the addition of possible diluent liquid (21).

The solid fraction (18) can be disposed of as such, or optionally it can be sent to a further treatment zone (filter cake treatment) as described below and in the examples, resulting in a substantially molybdenum-free fraction (23), which is sent to treatment , and a molybdenum-rich fraction (15) that can be recycled back to the hydrotreating reactor.

In order to better illustrate the present invention, some examples are provided below, but they should in no way be regarded as limiting the scope of the present invention.

Example 1

According to the flowchart shown in Figure 1, the following experiments were carried out.

Deasphalting step

Feedstock: 300 g vacuum residue from Urals crude oil (Table 1)

· Deasphalting reagent: 2000 ml liquid propane (repeated extraction three times)

·Temperature: 80℃

·Pressure: 35 bar

Table 1: Properties of 500°C ⁺ Ural Vacuum Residue API severe 10.8 Sulfur (% (weight)) 2.6 Nitrogen (% (weight)) 0.7 Kang's carbon residue (% (weight)) 18.9 Ni+V(ppm) 80+262

Hydrotreating step

Reactor: 3000 ml, steel, suitable shape and equipped with magnetic stirrer

Catalyst: 3000ppm Mo/adding raw material, using molybdenum naphthenate as precursor

·Temperature: 410℃

·Pressure: 16 MPa hydrogen pressure

·Stay time: 4 hours

flash step

· Performed with a liquid evaporation laboratory apparatus (T = 120°C)

Experimental results

In order to fully recycle the catalyst added in the first experiment, 10 consecutive deasphalting experiments were carried out, each experiment using the usual deasphalting reaction obtained from the Ural residue (fresh feedstock) and the _C3 asphaltene hydrotreating reaction in the previous step. Raw material composed of pressed residue. For each step, a certain amount of feedstock consisting of Urals vacuum residue (fresh feedstock) and _C3 asphaltenes from the deasphalting unit is fed into the autoclave so that the total mass of fed feedstock (fresh feedstock + The recycled _C3 asphaltenes) reached an initial value of 300 g.

Under these operating conditions, the ratio between the amount of fresh feedstock and the amount of recycled product is 1:1.

The relevant data (% by weight relative to starting material) for the discharge stream after the last cycle are given below.

Gas: 7%

Naphtha (C ₅ -170°C): 8%

Atmospheric gas oil (AGO, 170-350°C): 17%

·Deasphalted oil (VGO+DAO): 68%

The asphaltene stream recovered at the end of the experiment contained all the catalyst initially fed, metal Ni and V sulfides formed during the 10 hydrotreating reactions, and about 1 wt. coke. In the described examples, no flushing step of the recycle stream is required. Table 2 lists the properties of the products obtained.

Table 2: According to the experimental reaction product characteristic of embodiment 1 Sulfur (% (weight)) Nitrogen (ppm) Specific gravity (g/ml) RCC (% (weight)) Ni+V(ppm) Naphtha C ₅ -170°C 0.06 450 0.768 - - AGO 170-350°C 0.52 2100 0.870 - - VGO+DAO 1.45 2500 0.938 3 1

Example 2

20.7 g of the flush stream from the Ural resid 500°C ⁺ conversion unit (composition listed in Table 3) was treated with 104 g of toluene (solvent/flush stream weight ratio 5) at 100°C for 3 hours. The resulting fractions were filtered. 3.10 g of solids (composition listed in Table 4) and 17.60 g of heavy oil (after evaporative removal of toluene) with the metal content listed in Table 5 were collected.

Table 3: Properties of flushing stream from Ural residue processing 500°C ⁺ Specific gravity (g/ml) 1.1 S (% (weight)) 2.4 Mo (% (weight)) 0.68 Ni (% (weight)) 0.12 V(%(weight)) 0.36 Fe(%(weight)) 0.07

Table 4: Solids (filter cake) properties from treatment of Urals residue 500°C ⁺ flush stream with toluene C (% (weight)) 82.0 H (% (weight)) 3.9 S (% (weight)) 4.8 Mo (% (weight)) 4.1 Ni (% (weight)) 0.6 V(%(weight)) 2.2 Fe(%(weight)) 0.4

Table 5: Metal content in heavy oil extracted from Ural residue 500°C ⁺ treatment flush stream Mo (ppm) 10 Ni(ppm) 26 V(ppm) twenty three Fe(ppm) 10

Example 3

Using the same procedure described in Example 2, 10.6 grams of flushing stream (composition listed in Table 3) was treated with 62 milliliters of gas oil (produced during the Ural residue hydrotreating experiment carried out by the steps described in Example 1 above) and have the quality listed in Table 2) for treatment, the ratio of gas oil/flushing stream is 5, and the operation is carried out at 130° C. for 6 hours. The resulting fractions were centrifuged (5000 rpm). 1.78 grams of solids (composition listed in Table 6) and 8.82 grams of heavy oil (after gas oil removal by evaporation) were collected.

Table 6: Solids (filter cake) properties obtained from treatment of Ural 500°C ⁺ flush stream with gas oil Mo (% (weight)) 3.43 Ni (% (weight)) 0.53 V(%(weight)) 1.75

Example 4

1.0 g of the solid residue (obtained from the process described in Example 2, composition listed in Table 4) was mixed with 50 ml of acidified water (pH=2) and 50 ml of deasphalted oil (DAO) of the composition listed in Table 7 to process.

After 24 hours at 70°C, the liquid phase was decanted and both phases were analyzed for metals.

The entire amount (>99%) of molybdenum remained in the organic phase, while nickel and vanadium were found in the aqueous phase, in amounts corresponding to extraction yields of 23.5% and 24.4%, respectively.

Then the molybdenum-containing organic phase is sent to the hydrotreating experiment together with the fresh Ural residue oil, and the steps described in Example 1 are carried out, and the molybdenum keeps its catalytic activity property.

Table 7: DAO characteristics from Ural 500°C ⁺ residue treatment process Sulfur (% (weight)) Nitrogen (ppm) Specific gravity (g/ml) RCC (% (weight)) Ni+V(ppm) DAOs 1.02 2100 0.934 3 <1

Example 5

The same procedure as described in Example 4 was followed, but using gas oil produced during the hydrotreatment of the Ural residue (see Example 1) (in place of DAO) and acidified water (pH = 2).

The entire amount of molybdenum remained in the organic phase, while nickel and vanadium were found in the aqueous phase in amounts corresponding to extraction yields of 41.0% and 26.8%, respectively.

Example 6

Following the scheme shown in Figure 1, the product exiting the top of the high pressure separator is sent to a fixed bed reactor where it is fed with a downwardly flowing reagent stream. The reactor was loaded with a typical commercially available hydrodesulfurization catalyst based on molybdenum and nickel.

The operating conditions are as follows:

LHSV: 0.5 hours ^-1

Hydrogen pressure: 10 MPa

Reactor temperature: 390°C

Table 8 shows the quality of the feed to the fixed bed reactor and the quality of the product produced.

Table 8: Hydrotreating of C ₅ -350°C fraction obtained from 500°C ⁺ Ural residue treatment raw material product Specific gravity (g/ml) 0.8669 0.8294 Monocyclic aromatic hydrocarbons (% (weight)) 30.1 19.5 Bicyclic aromatic hydrocarbons (% (weight)) 8.3 1.2 Tricyclic aromatic hydrocarbons (% (weight)) 2.8 0.4 PAH (% (weight)) 11.1 1.6 Sulfur (ppm) 5300 37 Nitrogen (ppm) 2280 3 distillation curve T ₁₀ (℃) 187 145 T ₅₀ (℃) 271 244 T ₉₀ (℃) 365 335

Claims (36)

1. A conversion of heavy feedstocks selected from heavy crude oils, distillation residues, heavy oils from catalytic processes, thermal tars, oil sands bitumen, various coals and others derived from hydrocarbon high boiling feedstocks known as black oils The method, described method uses following three process units in combination: adopt the hydroconversion (HT) unit of slurry phase state catalyst, distillation or flashing (D) unit, deasphalting (SDA) unit, comprise the following steps: mixing at least a part of the heavy feedstock and/or at least the majority of the asphaltene-containing stream obtained in the deasphalting unit with a suitable hydrogenation catalyst and sending the resulting mixture to a charge of hydrogen or hydrogen and _H2S Hydrotreating reactor (HT) for the mixture; - sending the stream containing the product of the hydroprocessing reaction and the catalyst in the dispersed phase state to one or more distillation or flashing steps (D), thereby separating the different fractions from the hydroprocessing reaction; recycling at least a portion of the distillation residue (tar) or liquids leaving the flash unit containing catalyst in dispersed phase state, metal-rich sulphides from the demetallization of the feedstock and possibly coke to the deasphalting zone (SDA) where solvent is present, Optionally also feeding at least a portion of the heavy feedstock, resulting in two streams, one comprising deasphalted oil (DAO) and the other comprising asphaltenes; Characteristically, a portion of the bitumen-containing stream from the deasphalting section (SDA), called the purge stream, is sent to a treatment zone with a suitable solvent in order to separate the product into a solid fraction and a liquid fraction, from which the liquid fraction is subsequently removed the above solvent. 2. The method according to claim 1, wherein the flow rate of flushing material is in the range of 0.5-10% (volume) of fresh raw material. 3. The process according to claim 1, wherein at least a part of the liquid fraction obtained from the flushing stream treatment section is fed to the fuel oil fraction as such or after separation of the solvent and/or addition of a suitable dilution liquid. 4. Process according to claim 1, wherein at least a part of the liquid fraction from the flushing treatment zone is recycled to the hydrotreatment reactor (HT). 5. The process according to claim 1, wherein the solvent used in the flushing stream treatment section is an aromatic solvent or a gas oil mixture produced by the process or provided by a refinery. 6. A process according to claim 5, wherein the aromatic solvent is a mixture of toluene and/or xylene. 7. The process according to claim 1, wherein the solvent/flushing stream volume ratio is 1-10. 8. The process as claimed in claim 7, wherein the solvent/flushing stream volume ratio is 1-5. 9. The process as claimed in claim 8, wherein the solvent/flushing stream volume ratio is 1.5-3.5. 10. Process according to at least one of claims 1-9, wherein all heavy feedstocks are mixed with suitable hydrogenation catalysts and fed to the hydrotreatment reactor (HT), while at least 60% of the bituminous A stream which is qualitative and also contains catalyst in dispersed phase state and possibly coke and is rich in metals from the initial feedstock is recycled to the hydroprocessing zone. 11. A process according to claim 10, wherein at least 80% of the asphaltene-containing stream is recycled to the hydrotreating zone. 12. Process according to at least one of claims 1 to 9, wherein a part of the heavy feedstock and at least mostly asphaltenes-containing stream which also contains catalyst in dispersed phase state and possibly coke is mixed with a suitable hydrogenation catalyst, And sent to the hydrotreating reactor, and the remaining part of the heavy raw material sent to the deasphalting section. 13. Process according to at least one of claims 1 to 9, wherein at least a major part of the asphaltene-containing stream (essentially consisting of said asphaltenes) is mixed with a suitable hydrogenation catalyst and sent to the hydrotreatment reactor, while all the heavy feedstock is sent to the deasphalting section. 14. Process according to claim 1, wherein a portion of the distillation residue (tar) or liquid leaving the flash unit is recycled back to the deasphalting zone (SDA), and at least a portion of the remaining amount of said distillation or flash residue is sent to into the hydrotreating reactor. 15. The process according to claim 14, wherein at least a portion of the distillation or flash residue is fed to the hydrotreatment reactor together with at least a portion of the asphaltene-containing stream from the deasphalting section (SDA). 16. The process according to claim 1, wherein at least 80% by weight of the distillation residue is recycled to the deasphalting zone. 17. A process according to claim 16, wherein at least 95% by weight of the distillation residue is recycled to the deasphalting zone. 18. The process according to claim 1, wherein at least a part of the remaining amount of distillation residue (tar) not recycled to the deasphalting zone is recycled to the hydrotreatment section. 19. The process according to claim 1, wherein the distillation step is carried out under reduced pressure in the range of 0.0001-0.5 MPa. 20. The method according to claim 19, wherein the distillation step is carried out under reduced pressure in the range of 0.001-0.3 MPa. 21. The process according to claim 1, wherein the hydrotreating step is carried out at a temperature in the range of 370-480°C and a pressure of 3-30 MPa. 22. A process according to claim 21, wherein the hydrotreating step is carried out at a temperature in the range of 380-440°C and a pressure in the range of 10-20 MPa. 23. The method according to claim 1, wherein the deasphalting step is carried out at a temperature in the range of 40-200°C and a pressure of 0.1-7 MPa. 24. The method according to claim 1, wherein the deasphalting solvent is a C ₃ -C ₇ light paraffin. 25. The method according to claim 1, wherein the deasphalting step is carried out in one or more steps under subcritical or supercritical conditions. 26. The process according to claim 1, wherein the stream consisting of deasphalted oil (DAO) is fractionated by conventional distillation. 27. The process according to claim 1, wherein a stream consisting of deasphalted oil (DAO) is mixed with the product separated in the distillation step after condensation. 28. The method of claim 1, wherein the hydrogenation catalyst is a decomposable precursor or preformed compound based on one or more transition metals. 29. The method of claim 28, wherein the transition metal is molybdenum. 30. The process according to claim 1, wherein the concentration of catalyst in the hydroconversion reactor is 300-20,000 ppm based on the concentration of metal present. 31. The method according to claim 30, wherein the concentration of the catalyst in the hydroconversion reactor is 1000-10000 ppm. 32. Process according to at least one of claims 1-9, wherein the stream containing the hydrotreating reaction product and the catalyst in the dispersed phase state carries out a high-pressure separation pretreatment step before being sent to one or more distillation or flashing steps , in order to obtain a light fraction and a heavy fraction, only the heavy fraction is sent to said distillation step (D). 33. The method according to claim 32, wherein the light fraction obtained in the high-pressure separation step is sent to the second post-treatment hydrogenation section to generate a lighter fraction containing C ₁ -C ₄ gas and H ₂ S and hydrogenated stones Heavier fractions of naphtha and gas oil. 34. A process according to claim 33, wherein the post-treatment hydrogenation reaction is carried out at a pressure in the range of 7-14 MPa. 35. A process according to claims 1 and 28, wherein the solid fraction of the treated product is sent to a further treatment for the selective recovery of transition metals contained in the hydrogenation catalyst. 36. The method according to claim 35, wherein the recovered transition metals are recycled to the hydrotreatment reactor (HT).

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