JP4498929B2 - Methods for converting heavy charges such as heavy crude oil and distillation residues - Google Patents

Description

Detailed Description of the Invention

The present invention comprises three processing units suitably coupled and fed with a mixed stream consisting of fresh charge and conversion product, hydrogen conversion of the charge using catalyst in the dispersed phase, distillation and history. Of the heavy crude oil, the tar derived from oil sand and the distillation residue, to convert the heavy charge material.
The conversion of heavy crude oil, oil sand tar and liquid product oil residue can be effected in substantially two ways: one exclusively thermally and the other by hydrotreating.
Recent research has shown that thermal methods have problems related to the treatment of by-products, in particular coke (which can also be obtained in amounts higher than 30% by weight with respect to the charge) and the low quality of the conversion product. , Mainly for hydroprocessing.
Hydroprocessing consists of treating this charge in the presence of hydrogen and a suitable catalyst.
Currently, the hydrogen conversion technology on the market is generally from fixed or ebullated bed reactors and one or more transition metals (Mo, W, Ni, Co, etc.) supported on silica / alumina (or equivalent material) A catalyst consisting of
Fixed bed technology has a number of problems, particularly in the processing of heavy charges containing a high proportion of heteroatoms, metals and asphaltenes. This is because these pollutants cause rapid deactivation of the catalyst.
Ebule bed technology has been developed and commercialized for the treatment of these charge materials and provides interesting properties, but is complex and expensive.

Hydro-treatment technology operated by a catalyst in the dispersed phase can provide an attractive solution to these disadvantages encountered in the use of fixed bed or ebulate bed technology. In fact, the slurry process combines the advantages of wide flexibility of the charge with the high performance in terms of conversion and improvement, and is therefore basically simpler from a technical point of view.
Slurry technology has a very small average size and is characterized by the presence of catalyst particles that are effectively dispersed in the medium, so that hydroprocessing is simpler and immediate at all points in the reactor. Is. The formation of coke is significantly reduced and the charge material improvement is high.
The catalyst can be charged as a powder having substantially reduced dimensions (US Pat. No. 4,303,634) or as an oil-soluble precursor (US Pat. No. 5,288,681). In this latter case, the active form of the catalyst (generally a metal sulfide) is formed in situ by pyrolysis of the compounds used during the reaction itself or after a suitable pretreatment (US) Patent No. 4,470,295).
The metal component of the dispersed catalyst is generally one or more transition metals (preferably Mo, W, Ni, Co or Ru). Molybdenum and tungsten have a more satisfactory performance than nickel, cobalt or ruthenium and thus even more than vanadium and iron (N. Panariti et al., Appl. Catal. A: Jan. 2000, 204 , 203). .
Although the use of a dispersed catalyst solves most of the problems mentioned for the above technique, there are disadvantages mainly related to the life cycle of the catalyst itself and the quality of the resulting product.
The procedure for the use of these catalysts (precursor type, concentration, etc.) is actually very important from an economic point of view and even from an environmental impact point of view.

The catalyst can be used at low concentrations (hundreds of ppm) in “once-through” form, but in this case the improvement of the reaction product is generally insufficient (N. Panariti et al., Appl. Catal. A: Jan. 2000, 204 , 203 and 215). Operating with a very active catalyst (eg molybdenum) and a high concentration of catalyst (thousands of ppm metal), the quality of the resulting product is greatly improved, but the catalyst must be recycled. Don't be.
The catalyst exiting the reactor is obtained from hydro-treatment (preferably from the bottom of the distillation column downstream of the reactor) using conventional methods such as decanting, centrifugation or filtration. Can be recovered by separation from the resulting product. (U.S. Pat. Nos. 3,240,718 and 4,762,812). A portion of the catalyst is recycled to the hydrotreatment without further treatment. However, the catalyst recovered using known hydroprocessing methods usually has reduced activity relative to fresh catalyst, and thus a suitable regeneration step is performed to restore the catalyst activity and at least the catalyst. A portion must be recycled to the hydrotreating reactor. Furthermore, these recovery procedures for the catalyst are expensive and very complex from a technical point of view.

With regard to the chemical description of the conversion process, it is convenient to introduce the concept of stability, with crude oil or oil residues being diluted or cracked in hydrocarbon fractions, by chemical rearrangements induced by hydrogenation, etc. , Represents the tendency to precipitate asphaltene components caused by operating conditions or changes in the chemical composition of oil and / or asphaltenes (incompatible).
Hydrocarbons that can be precipitated by an oil residue or crude oil treated with n-heptane under the standard conditions defined by Regulation I-143 are conventionally defined as asphaltenes.
From a qualitative point of view, the incompatibility phenomenon is the result of a mixture of paraffin crude oil and aromatic crude oil or a paraffinic cutter stock (cutter stock), with respect to the nature of the marten or non-asphalten component. As in the case of dilution of the oil residue by), a typical case is the flushing of tar from visbreaking with a slight aromatic gas oil.
In the process of converting oil residues, oil sand tar and heavy crude oil to distillates, the maximum conversion level is limited by the stability of the resulting residue. In fact, these methods alter the chemical properties of oils and asphaltenes that result in an increased degree of severity and a continuous decrease in stability. Beyond certain limits, asphaltenes present in the charge will cause phase separation (or precipitation), thereby activating the coke forming process.

From a physicochemical point of view, the phase separation phenomenon can be explained by the fact that asphaltene phase becomes increasingly aromatic due to dealkylation and condensation reactions as the conversion reaction proceeds.
Thus, beyond a certain limit, the asphaltenes are no longer soluble in the martens phase, during which the marten phase becomes more “paraffinic”.
During the thermal and / or catalytic conversion process, control of loss of stability of the heavy charge is therefore not necessary to achieve maximum conversion without leading to problems with coke and soil formation.
In a once-through process, the optimum operating conditions (mainly reaction temperature and residence time) are simply determined based on the reactor effluent stability data by direct measurement of unconverted residue (P value, hot filtration). Test, spot test, etc.).
With all these methods, more or less high conversion levels are reached depending on the type of charge and technology used, but produce unconverted residues at the limit of stability, which we specialize in In some cases, it is called tar and can vary from 30 to 85% of the initial charge. This product is used to produce fuel oil, tar, which can be used as a charge for the gasification process.
In order to increase the overall conversion of the residue cracking process, a scheme was proposed that included a step of recycling a more or less significant amount of tar to the cracking unit. In the case of a hydroconversion method using a catalyst dispersed in a slurry phase, it is possible to recover the catalyst by recirculating tar. For this reason, in the patent application IT-95A001095, the same applicant uses the recovered catalyst as a hydroprocessing reactor. A process that allows recycle, without the need for further regeneration steps, and at the same time obtaining a high quality product without residual products (“zero residue refinery”) has been described.

The method comprises the following steps:
(1) mixing heavy crude oil or distillation residue with a suitable hydrogenation catalyst and sending the resulting mixture to a hydrotreating reactor charged with hydrogen or a mixture of hydrogen and H ₂ S;
(2) sending a stream containing the hydroprocessing reaction product and catalyst in the dispersed phase to a distillation zone where the most volatile fraction is separated;
(3) Sending the high boiling fraction obtained in the distillation process to the desaturation process, the two resulting streams, one consisting of desaturation oil (DAO), the other asphalt, the catalyst in the dispersed phase and Producing a metal-rich stream, optionally made of coke and derived from the initial charge,
(4) recycling at least 60%, preferably at least 80% of the stream, consisting of asphalt, catalyst in the dispersed phase and optionally coke, rich in metal, in the hydrotreating zone;
including.

When using heavy crude oil or tar from oil sands as a raw material for the process of converting tar to complex hydrocarbon mixture and further converting to further distillate, use different process forms from the previous point of view. Can be convenient, thereby the following advantages,
(1) Maximizing the conversion yield of distillable products (derived from atmospheric and vacuum distillation), and history oil (DAO), which can exceed up to 95%,
(2) The degree of improvement of the charging material, that is, the removal of existing poisons (metal, sulfur, nitrogen, carbonized residue) is maximized, and the amount of coke produced is minimized.
(3) Maximum flexibility of charge materials with different nature (density) of hydrocarbon components and levels of contaminants,
(4) The possibility of completely recycling the hydrogenation catalyst without the need for regeneration,
Is obtained.
By the combined use of the following three processing units, slurry phase catalyst hydrogen conversion (HT), distillation or flash (D), and history removal (SDA), which is the object of the present invention, The three devices are operated on a mixed stream consisting of fresh charge and recirculated stream to obtain at least one fraction of heavy charge in the presence of the following step (1) solvent: , The process of obtaining two streams consisting of history oil (DAO) and asphalt, sent to the history area (SDA),
(2) mixing the asphalt with a suitable hydrogenation catalyst and optionally the remaining fraction of heavy charge not sent to the degassing section, and mixing the resulting mixture with hydrogen or a mixture of hydrogen and H ₂ S Sending it to the hydroprocessing reactor (HT)
(3) The above stream containing the hydroprocessing reaction product and catalyst in the dispersed phase is sent to one or more distillation or flashing step (D), which is the most volatile of the gases generated in the hydroprocessing reaction. Separating the sex fraction,
(4) at least 60% by weight of a distillation residue (tar) or liquid that flows out of the flash unit, contains the catalyst in the dispersed phase, is rich in metal sulfides produced by demetallization of the charge and optionally contains coke, Preferably recycling at least 80% by weight, more preferably at least 95%, to the history zone;
It is characterized by using.

The heavy charge to be processed can be of different types, including heavy crude oil, distillation residue, heavy oil derived from catalyst treatment, eg heavy cycle oil from catalyst cracking treatment, hot tar ( (E.g., derived from visbreaking process or similar heat treatment), tars derived from oil sands, various coals and any other high boiling charge of hydrocarbon origin commonly known in the art as black oil The
Distillation residue (tar) or remaining portion of liquid exiting the flash unit is not recycled to the desaturation zone, but may be wholly or partially recycled to the hydrotreating section.
Catalysts can be obtained from easily decomposable oil-soluble precursors (metal naphthalene, metal derivatives of phosphonic acid, metal carbonyl, etc.) or from one or more transition metals such as Ni, Co, Ru, W and Mo. The latter can be selected, and the latter is preferable from the viewpoint of high catalytic activity.
The concentration of the catalyst defined based on the concentration of metal present in the hydroconversion reactor is in the range of 350 to 10000 ppm, preferably 1000 to 8000 ppm, more preferably 1500 to 5000 ppm.
The hydrotreating step is preferably carried out in the temperature range of 370 to 480 ° C., preferably 380 to 440 ° C., and in the pressure range of 3 to 30 MPa, preferably 10 to 20 MPa.
Hydrogen is fed to the reactor, which can operate under downflow conditions, preferably upflow conditions.
The distillation step is preferably carried out under reduced pressure at a pressure in the range of 0.001 to 0.5 MPa, preferably 0.05 to 0.3 MPa.
The hydroprocessing step can consist of one or more reactors operated within the above conditions. A portion of the distillate produced in the first reactor can be recycled to the next reactor.

The history process resulting from extraction with a solvent that may or may not be a hydrocarbon (e.g., with paraffins having 3 to 6 carbon atoms) is generally at a temperature in the range of 40-200C. It is carried out at a pressure in the range of 0.1-7 MPa. It can consist of one or more parts operated with the same solvent or different solvents, which can be recovered under supercritical conditions to further allow for fractionation of asphalt and resin.
A stream consisting of a history oil (DAO), such as a synthetic crude oil (synthetic crude oil), is optionally used in admixture with a distillate, or as a charge for fluid bed catalytic cracking or hydrogen cracking. Can be used.
Depending on the properties of the crude oil (metal content, sulfur and nitrogen content, carbonization residue), it is possible to adjust advantageously under the following conditions:
(1) The ratio between the heavy residue to be sent to the hydrogen treatment unit (fresh charging material) and the heavy residue to be sent to the history, wherein the ratio is 0 to 100, preferably 0.1 to It can vary from 10, more preferably from 1 to 5.
(2) Recycle ratio of fresh charge material and tar that can be sent to the history part, this ratio preferably changing in the range of 0.1-100, more preferably 0.1-10.
(3) A recycle ratio between fresh charge and asphalt to be sent to the hydrotreater, which ratio can change in relation to the change in ratio described above.
(4) Tar and asphalt recirculation ratio to be sent to the hydrotreating section, which ratio can vary in relation to the aforementioned ratio change.

This flexibility is particularly useful to better utilize the complementary properties of dehistoric devices (appropriate HDN and dearomatization) and hydrogenation devices (high HDM and HDS).
Depending on the type of crude oil, the stability of the stream in question and the quality of the product to be obtained (in connection with the particular downstream), the history and fresh equipment supplied to the hydrotreater The fraction of incoming material can be adjusted in the most possible way.
Furthermore, to achieve the most possible operation of these processes, ensure the compatibility of the streams to be mixed, or
(1) Fresh charge and tar (2) Fresh charge and asphalt (optionally including resin or aliquot thereof)
(3) Tar and asphalt (including resin or aliquots depending on the case)
It is desirable to ensure that streams having different physicochemical properties are mixed in a ratio that prevents precipitation of asphaltenes in all process phases.
As far as the compatibility of the streams to be mixed is concerned, the process which is the object of the present invention has a recirculation between streams containing asphaltenes or fresh charge, tar and asphalt in the following proportions:
(ν _mix / RT) (δ _asph -δ _mix ) ² <k
(Where
ν _mix is the molar volume of the marten component of the mixture (ie non-asphalten) (cm ³ / mol),
δ _mix is the solubility parameter (cal / cm ³ ) ^1/2 of the marten component of the mixture,
δ _asph is the asphaltene solubility parameter of the mixture (the highest value of the two components of this mixture is considered) (cal / cm ³ ) ^1/2 ,
R is a gas constant (1.987 cal / mol ° K),
T is the temperature expressed in Kelvin degrees. )
It can be further improved by controlling to have

Asphaltenes to be used as a reference to determine the above properties is insoluble n- heptane fraction (C ₇ asphaltenes).
The value shown in this equation is calculated as follows.
ν _mix is the molar average of the molar volume of the marten component,
δ _mix is the volume average of the solubility parameter of the marten component,
k is a constant whose value ranges from 0.2 to 0.5.
In the above application, the heavy fraction of the complex hydrocarbon mixture produced in this way must be used as a charge for catalytic cracking plants, i.e. hydrogen cracking (HC) and fluidized bed catalytic cracking (FCC). It is sometimes particularly suitable.
In fact, the combined action of the catalytic hydrogenator (HT) and the extraction process (SDA) makes it possible to produce history oil with a reduced content of contaminants (metal, sulfur, nitrogen, carbonized residue). Can therefore be more easily processed by catalytic cracking.
Furthermore, the investment cost of the entire complex also increases with respect to the same charging unit being processed, while the size of the history part is increased, for the scheme described in patent application IT-95A001095. Since the hydrotreater size (and downstream distillation column) is reduced, that is, this deregistration device results in a lower investment cost than the hydrotreater, resulting in savings in the overall complex investment cost, Can be minimized.
A preferred embodiment of the present invention is provided by the attached FIG. 1, but should not be construed as a limitation on the scope of the invention itself.

A heavy charge (1), or at least a part (1a) thereof, is sent to a deregistration device (SDA), the operation of which is performed by extraction with a solvent.
Two streams are obtained from the deregistration device (SDA). One stream (2) consists of de-historic oil (DAO) and the other stream (3) consists of asphalt and resin, the latter being further separated into two groups of formed compounds, the resin fraction (4) can be separated into DAO and asphalt.
A stream consisting of asphalt and resin (or a fraction thereof) consists of fresh constituent catalyst (5) required for reintegration used in the flushing stream (14) and heavy charge (1b ), Optionally from the bottom of the distillation column (D), with stream (15) (described further herein) to form stream (6), which is hydrogen (or hydrogen and H ₂ S ) (7) is fed to the hydrotreating reactor charged. The stream (8) containing the hydrogenation product and catalyst in the dispersed phase exits the reactor and is fractionated in a distillation column (D) from which a light fraction (9) and a distillable product (10) , (11) and (12) are separated from the distillation residue containing the dispersed catalyst and coke. This stream (13), referred to as tar, is recirculated to the history reactor (SDA), completely or largely, except for the flushing (14). This portion (15) can optionally be sent to a hydrotreater (HT).
Some examples are provided below for a better illustration of the invention without limiting its scope.

水素処理工程
・反応器：3000cc、鋼製、適当な形状で磁気攪拌子を備える。
・触媒：先駆物質としてモリブデンナフテネートを使用して添加されたMo/装入材料を3000ppm。
・温度：410℃
・圧力：水素の16MPa
・滞留時間：4時間

フラッシュ工程
・液体蒸発の実験装置によって達成される(T=120℃)。

実験結果
１０個の連続した脱歴試験を、それぞれの試験に対して、ウラル真空残渣（純粋な装入材料）と前工程のC₃アスファルテンの水素処理反応から得られる大気残渣とからなる装入材料を使用して行い、第一試験の間添加される触媒を完全に再循環できるようにした。各工程において、ウラル真空残渣（新鮮な装入材料）及び脱歴から由来するC₃アスファルテンからなる装入材料を、全装入材料質量（新鮮な装入材料+再循環されたC₃アスファルテン）を初期値の300gとなるようにオートクレーブに供給した。
これらの操作条件下到達した、新鮮な装入材料の量と再循環された装入材料の量間の比率は、1:1であった。
最後の再循環（装入材料に関する質量%）の後、流出流(out-going)に関するデータは、以下の通りである。
・ガス：7%
・ナフタ(C₅-170℃):8%
・大気ガス油(AGO 170-350℃):17%
・脱歴油(VGO+DAO):68%
この試験の最後に回収されたアスファルテン流は、最初に供給されるすべての触媒、水素処理から10回再循環される間に、生成した金属Ni及びVのスルフィド及びコークスを、供給されたウラル残渣の全量に対して約1質量%のオーダーで含む。示された例において、再循環された流れをフラッシング作用にかける必要はなかった。
表２は、得られた生成物の特性を示す。








表２：実施例１の試験反応生成物の特性

The following examples were performed according to the scheme shown in FIG.
Deregistration process and charging material: 300 g of vacuum residue from ural crude oil (Table 1)
・ Dehistoric agent: liquid propane (extraction times 3 times) 2000cc
・ Temperature: 80 ℃
・ Pressure: 0.035 MPa (35 bar)

Table 1 : Characteristics of Ural vacuum residue 500 ℃ +

Hydrogen treatment process / reactor: 3000cc, made of steel, equipped with magnetic stirrer in appropriate shape.
Catalyst: 3000 ppm Mo / charge added using molybdenum naphthenate as precursor.
・ Temperature: 410 ℃
・ Pressure: 16MPa of hydrogen
・ Residence time: 4 hours

Achieved by flash process / liquid evaporation experimental equipment (T = 120 ° C).

Experimental results Ten consecutive history tests, for each test, were made up of an ural vacuum residue (pure charge) and an atmospheric residue from the hydrotreating reaction of C ₃ asphaltenes in the previous step. The material was used so that the catalyst added during the first test could be completely recycled. In each step, Ural vacuum residue (fresh charging material) and the charge material consisting of C ₃ asphaltenes deriving from deasphalting, total charge material weight (fresh Charge + recycled C ₃ asphaltenes) Was supplied to the autoclave so as to have an initial value of 300 g.
The ratio between the amount of fresh charge and the amount of recycled charge reached under these operating conditions was 1: 1.
After the last recirculation (mass% on charge), the data on out-going is as follows:
・ Gas: 7%
・ Naphtha (C ₅ -170 ℃): 8%
・ Atmospheric gas oil (AGO 170-350 ℃): 17%
・ History oil (VGO + DAO): 68%
The asphaltene stream recovered at the end of this test was recirculated 10 times from all initially fed catalyst, hydrotreating, and the metal Ni and V sulfides and coke produced were fed to the Ural residue. In the order of about 1% by mass with respect to the total amount of In the example shown, it was not necessary to subject the recirculated stream to a flushing action.
Table 2 shows the properties of the product obtained.








Table 2 : Properties of the test reaction product of Example 1

Experiments similar to those described in Test 1 were performed, except that the hydrogen treatment step was performed at 420 ° C.
The ratio between the amount of fresh charge reached under these operating conditions and the amount of recycled product was 1: 1.5.
After the last recirculation (mass% on charge), the data on the effluent is as follows:
・ Gas: 9%
・ Naphtha (C ₅ -170 ℃): 11%
・ Atmospheric gas oil (AGO 170-350 ℃): 24%
・ History oil (VGO + DAO): 56%
In the example shown, it was not necessary to flush the recycle stream.
Table 3 provides the properties of the resulting product.

Table 3 : Properties of the test reaction product of Example 2

グラフから、二つの別個の流れが安定であり(k≦0.5)、一方、真空残渣装入材料は、再循環流の少量の添加によりすぐに不安定(k値＞0.5)となることが分かる。25%より多い再循環された流れの添加に対して、混合物は、再び安定となる(k値≦0.5)。 The following example illustrates the correlation shown in the present invention to evaluate the compatibility limits of various streams subjected to hydroprocessing:
(ν _mix / RT) (δ _asph -δ _mix ) ² <k
Indicates the use of.
The flow used in Examples 1 and 2 was characterized to determine the characteristics used in the above relation.
Starting from the properties shown in Table 4 and using the above relationship, the parameter k value was calculated for all possible mixing states of the two streams: ie, the first component is 0% and the second component is From 100% to the opposite state, ie 100% of the first component and 0% of the second component. The reference temperature for determining properties is 140 ° C.
The values obtained are shown in the graph of FIG.








Table 4 : Flow characteristics used in Examples 1 and 2

From the graph, it can be seen that two separate streams are stable (k ≦ 0.5), while the vacuum residue charge is immediately unstable (k value> 0.5) with the addition of a small amount of recirculation stream. . For the addition of more than 25% of the recycled stream, the mixture becomes stable again (k value ≦ 0.5).

The scheme of this conversion method is shown. The amount of change of the k parameter with respect to the structure of the mixture is shown.

Claims (18)

The following three treatment devices: heavy crude oil, distillation residue, heavy oil derived from catalyst treatment, hot tar, tar derived from oil sand, various by using a combination of hydrogen treatment device, distillation or flash device and history history device, various A method of converting a heavy charge selected from other high boiling charge of a hydrocarbon source known as coal or black oil of the following steps:
(1) sending a fresh heavy charge fraction in the presence of a hydrocarbon solvent to a de-history device to obtain two streams , a stream consisting of de-history oil and a stream consisting of asphalt;
(2) mixing the asphalt stream with a suitable hydrogenation catalyst and the remaining fraction of heavy charge that is not sent to the degassing section to obtain a mixture;
(3) the resulting said mixture, Ri sent to hydrotreater where a mixture of hydrogen or hydrogen and H ₂ S is charged, Ru obtain a stream comprising hydrogen treatment reaction product and the catalyst in the dispersed phase Process,
( 4 ) The stream containing the hydrotreating reaction product and catalyst in the dispersed phase is sent to one or more distillation or flash devices to separate the most volatile fraction of the gas produced in the hydrotreating reaction. A stream consisting of a distillation residue (tar) or liquid that exits the distillation or flash unit, contains the catalyst in the dispersed phase, is rich in metal sulfides, and optionally contains coke, produced by demetalization of the charge. The resulting Ru process,
( 5 ) recirculating at least 60% by weight of the distillation residue (tar) or liquid to a de-history device ;
The method is characterized in that the three devices are operated on a mixed stream consisting of fresh charge and recirculated stream.   The method of claim 1, wherein at least 80% by weight of the distillation residue or liquid exiting the flash unit is recycled to the history zone.   3. The method of claim 2, wherein at least 95% by weight of the distillation residue or liquid exiting the flash unit is recycled to the history zone.   The method according to claim 1, wherein at least a part of the distillation residue (tar) or the remaining portion of the liquid that flows out of the flash unit and is not recycled to the history zone is recycled to the hydrotreating section.   The method according to claim 1, wherein the distillation step is performed in the range of 0.001 to 0.5 MPa. The method according to claim 5 , wherein the distillation step is carried out in the range of 0.05 to 0.3 MPa.   The method according to claim 1, wherein the hydrotreating step is performed at a temperature in the range of 370 ° C. to 450 ° C. and at a pressure in the range of 3 to 30 MPa (30 to 300 atm). The method according to claim 7 , wherein the hydrotreating step is carried out at a temperature in the range of 380 ° C. to 440 ° C. and at a pressure in the range of 10 to 20 MPa (100 to 200 atm).   The method according to claim 1, wherein the history removal step is performed at a temperature in the range of 40 ° C. to 200 ° C. and at a pressure in the range of 0.1 to 7 MPa (1 to 70 atm).   The method of claim 1, wherein the history solvent is light paraffin having 3 to 6 carbon atoms.   The method of claim 1, wherein the history step is performed by solvent extraction operated in a supercritical phase.   The process according to claim 1, wherein the stream consisting of history oil (DAO) is fractionated by conventional distillation.   The process according to claim 1, wherein the stream comprising the desaturated oil (DAO) is mixed with the product separated in a flash step after concentration.   The process according to claim 1, wherein the hydrogenation catalyst is an easily decomposable precursor or a preformed compound based on one or more transition metals. The method of claim 14 , wherein the transition metal is molybdenum.   The process according to claim 1, wherein the concentration of catalyst in the hydroconversion reactor, defined on the basis of the concentration of metal present, is between 350 and 10,000 ppm. The process according to claim 16 , wherein the catalyst concentration in the hydroconversion reactor is 1000 to 8000 ppm. The process according to claim 17 , wherein the catalyst concentration in the hydroconversion reactor is 1500 to 5000 ppm.

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