Up-flow reactor with high hydrogenation capacity for hydroconversion of heavy oils to light hydrocarbons

Abstract

By using an up-flow reactor equipped with a gas distributor having a high orifice density, a rise in hydrogenation capacity required for the complete hydroconversion of heavy oils to light hydrocarbons (350 DEG C.), which is capable of causing bubble filling, which is the most advantageous hydrodynamic condition, is obtained. The resulting conversion product is suitable as a petrochemical feedstock.

Description

[0001] Field of application of the present invention

[0002] The high hydrogenation capacity upflow reactor guest of the present invention can be used for the hydroconversion of heavy oil (including crude oil) and the hydroprocessing of vacuum distillates.

[0003] Overview of the prior art

[0004] It is known that the hydroconversion of heavy oils by using the technology of ebullating catalytic bed (supported catalyst) reactors allows only partial conversion, since some unconverted residues remain together with the light distillates (350°C-) and the heavy distillates (350°C+).

[0005] A different technology using slurry-type catalysts (slurry technology) has recently been demonstrated several times on a commercial scale, allowing an alternative to carrying out complete chemical conversions.

[0006] Slurry technology, due to the completeness of the chemical conversion and the fact that it operates according to a closed liquid loop, will be suitable for the complete conversion of heavy oils and crude oils into light hydrocarbons (350°C-), a goal that has never been achieved so far. This requires a slurry bubble column reactor with the required hydrogenation capacity that is not currently achieved with upflow reactors.

[0007] In an upflow reactor for the hydroconversion of heavy oils, hydrogen is fed simply by bubbling.

[0008] When such reactors are used: a) in the hydroconversion of heavy oils by slurry catalysts; b) in the hydroconversion of heavy oils by supported catalysts, limited hydrogenation capacity is exhibited due to the low gas-liquid contact surface created by the feed hydrogen without special precautions. The problem of limited hydrogenation capacity of upflow reactors was studied in U.S. Pat. No. 11241673. However, the solution described therein does not allow to increase the hydrogen content in the conversion product, but requires complete hydrogenation of the heavy oil into light hydrocarbons (350°C-).

[0009] In order to increase the hydrogen content in the conversion products (product composition), it is necessary to increase the gas-liquid contact surface through which the hydrogen must diffuse in order to feed all the reactants required for the hydroconversion process.

[0010] The first upflow reactor capable of increasing the gas-liquid contact surface has been described in Italian Patent No. 102020000009880 (corresponding to WO 2021 / 224949 A1).

[0011] In the bubbling state, the contact surface between the bubble and the liquid (in m 2 / m 3 liquid) is called the specific air-liquid surface and is expressed as as For purely geometric reasons, the specific surface area a s and gas holdup rate e g is proportional to the average bubble diameter d s Inversely proportional, this produces a s =6e g / d s , where e g Expressed in fractional units, and d s In the aforementioned Italian Patent No. 102020000009880, in order to obtain a higher specific gas-liquid surface, the usual flow of hydrogen fed to the upflow reactor is divided into m 2 At least 64 and at most 2500 input streams. This hydrogen split reduces the bubble diameter d s , and at the same time the holdup rate e g to values ​​above 0.33, up to 0.5 and higher, which results in a specific air-liquid surface area s increase.

[0012] However, increasing the gas holdup reduces the volume of the reaction liquid in the reactor. This means that while the hydrogenation capacity increases, the loss of cracking capacity (due to the lower amount of liquid loading in the reactor) must be taken into account. The lower cracking capacity can be compensated by the catalyst (when it is a supported catalyst) because it catalyzes molecular cracking in addition to hydrogenation, as in case b) above, but not in case a) of the process involving the hydroconversion of heavy oils by slurry catalysts, because these unsupported catalysts have no effect on cracking kinetics. Alternatively, the cracking rate can be increased by increasing the reactor temperature, but this path is not feasible when the goal is to increase the hydrogenation capacity, because the hydrogenation kinetics decrease as the temperature increases.

[0013] In the case of hydroconversion of heavy oils using slurry catalysts, the use of the reactor described in Italian Patent No. 102020000009880 means that a limit must be maintained on the increase in the specific gas-liquid surface in order not to burden the capacity of the system, which is insufficient to increase the hydrogenation capacity to the level required for complete conversion of the heavy oil into light hydrocarbons (350°C-).

[0014] Invention Objectives

[0015] The object of the present invention is to overcome the above drawbacks by enabling the hydroprocessing process to be scaled up to a specific gas-liquid surface, using an upflow reactor, without increasing the gas holdup level, thus enabling the hydrogenation capacity to be increased without compromising the capacity of the system. Summary of the invention

[0016] By equipping the reactor with 2A gas distributor with at least 100 orifices increases the hydrogenation capacity of a slurry bubble column reactor used in hydroconversion of heavy oils and in hydrotreating vacuum distillates by enlarging the gas-liquid unit surface without increasing the gas holdup, the gas distributor feeding hydrogen at a certain superficial velocity to cause the filling of bubbles, regardless of the orifice density of the gas distributor used. Bubble filling is the fluid dynamic condition that allows the highest liquid filling of the reactor while the gas-liquid unit surface is maximized.

[0017] The achievable increase in hydrogenation capacity allows the complete hydrogenation conversion of heavy oils into light hydrocarbons (350° C. -). The resulting set of conversion products can reach a certain hydrogen weight-average content, which makes it particularly suitable as a petrochemical feedstock.

[0018] Other innovative features of the invention are set forth in the following description and are recited in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Other objects and advantages of the present invention will become apparent from the following detailed description of examples of embodiments of the present invention and from the accompanying drawings, in which:

[0020] - Figure 1 shows how the holdup in a bubble column reactor increases linearly with the superficial velocity of hydrogen (expressed as uG / uG^) until the bubbles are filled (uG^ is the superficial velocity at which the bubbles are filled, cm / s). The gas-liquid unit surface (by multiplying a s ×(1-e g ) gives) which only grows with the ratio uG / uG^ until the bubble is filled (see solid points);

[0021] - Figure 2 An upper limit on the superficial velocity as a function of the orifice density of the gas distributor used when feeding hydrogen to expand the specific gas-liquid surface while maintaining the gas holdup value at a limit of no more than 0.33 is provided;

[0022] - Figure 3 A process is shown by which light hydrocarbons (350°C-) are removed more quickly from the reactor to prevent asphaltenes from separating from the reaction liquid.

[0023] Detailed description of some preferred embodiments of the present invention

[0024] In the following description of the invention, reference may also be made to elements not explicitly shown in a figure but shown in other figures to explain the figure. The dimensions and proportions of the various elements depicted do not necessarily correspond to the actual dimensions and proportions.

[0025] Reactor hydrogenation capacity

[0026] The hydrogenation unit capacity of the bubble column reactor (per m 3 The hydrogenation capacity per unit is proportional to the gas-liquid surface area per unit, expressed in m 2 / m 3 The reactor volume is expressed as a s ×(1-e g ) is given, where (1-e g ) is the volume fraction of the reactor occupied by the reaction liquid, and a s is the specific air-liquid surface, see above.

[0027] When the gas-liquid unit surface a s ×(1-e g ) is the maximum capacity of the hydrogenation unit.

[0028] Gas-liquid unit surface

[0029] In a bubble column, when a gas (in this application, hydrogen) is fed at a superficial velocity uG (expressed as uG / uG^), a gas holdup e is observed. g Linear increase, see Figure 1 , where uG^ is the surface velocity of hydrogen gas when the bubble is filled (cm / s). The bubble rise velocity (group velocity) is calculated by the ratio uG / e g Given, with their diameter d s is proportional to (Word Academy of Science, Engineering and Technology, Terminal velocity of a bubble rise in a liquid column, 28 2007 Talaia), therefore, it can be written as uG / e g =kd s . Among them, g When the / uG ratio remains constant, its reciprocal uG / e g This means that the bubble diameter d s In e g Remains constant during linear growth, at d s ^Values ​​shown.

[0030] As the superficial velocity (volume flow rate) of the gas (hydrogen) increases, the number of bubbles N present per unit volume of the reactor increases. b This results in the reactor gas holdup rate increasing linearly according to e g =N b ×π / 6×(d s ^) 3 And it increases linearly. g The linear growth with uG is followed by as The linear growth of s =6e g / d s .

[0031] e g and a s As the linear increase in the gas (hydrogen) surface velocity continues until the number of bubbles reaches a maximum, N b ^=e g ^ / [π / 6×(d s ^) 3 ], at which point their filling is complete. Since the gas (hydrogen) surface velocity is greater than uG^, the bubbles begin to merge and their diameter increases.

[0032] In the case of uniform bubble diameter, and for any bubble diameter, the bubble packing geometry is theoretically predicted at a holdup value of 0.296≌0.3 (International Journal of Chemical Reactor Engineering, A Review on Flow Regime Transition in Bubble Column, Vol. 5

[2007] , Review R1, 4.2.1.2 Mishima and Ishii). Since, as will be shown later, the value of 0.299 is substantially confirmed by experiment, it follows that with a naturally distributed bubble diameter, at Figure 1 The gas holding rate e when the bubbles are filled is g ^Set to equal 0.299.

[0033] In this application, when the filling of hydrogen bubbles has been completed, the physical quantity N b ,uG,e g 、a s and d s Assumptions are indicated by "^".

[0034] Once the bubble is filled, the gas (hydrogen) surface velocity uG is increased to exceed uG^, and the bubble diameter (which was previously constant and equal to d s ^) Start with a first approximation s ^×(uG / uG^) 1 / 3 Growth. The growth of bubble diameter (which increases their ascent velocity, slowing the e from continued bubble filling) g The growth of g ^×(uG / uG^) 2 / 3 Rising. Due to the gas-liquid surface a s Always equal to 6e g / ds , so once the filling is complete, a s becomes equal to 6e g ^×(uG / uG^) 2 / 3 / d s ^×(uG / uG^) 1 / 3 , which is equal to a s ^×(uG / uG^) 1 / 3 .

[0035] Although the gas-liquid surface s With a s ^×(uG / uG^) grows until the bubble is filled, but grows more slowly beyond it, as in a s ^×(uG / uG^) 1 / 3 Like that.

[0036] a s The decrease in growth together with (1-e g ) continues to decrease, resulting in the product a s ×(1-e g ) once the bubble filling has been reached, it will no longer increase, such as Figure 1 As shown by the solid points in the figure. For uG=uG^, when in e g =e g ^=0.299When the bubble filling is completed, the gas-liquid unit surface a s ×(1-e g ) reaches a maximum value, then remains constant for a moment, and then decreases ( Figure 1 not shown).

[0037] Figure 1 The holdup rate e shown g The trend of is shown as a function of the surface velocity of the gas (hydrogen), which is not measured in cm / s as is usually the case, but as a ratio relative to the surface velocity of the gas (hydrogen) uG^ during bubble filling. This has been done so that the e described g The trend of can be maintained for any value of uG^. Therefore, although uG^ varies with the orifice density of the gas distributor used, as will be seen later, Figure 1 Remains effective regardless of the orifice density of the gas distributor used.

[0038] Furthermore, since uG^ also varies with the liquid density (which determines the bubble rise speed), expressing the surface velocity of the gas as uG / uG^ ensures that Figure 1This is valid for both: the gas-liquid mixture of a boiling catalytic bed reactor, where uG^ is typically between 4.5 and 5.5 cm / s due to the high density of the reaction medium; and the gas-liquid mixture of a reactor using a slurry catalyst, which does not change the density of the liquid and where uG^ is typically limited to 2.5 cm / s.

[0039] Specifically, from Figure 1 It can be seen that the gas-liquid unit surface a s ×(1-e g Once the holdup is 0.299 and the hydrogen superficial velocity uG / uG^=1, a consistent with bubble filling is reached. s ^×(1-e g ^) value, then the further increase of uG / uG^ stops growing, and the liquid filling of the reactor (1-e g ) continues to decrease. This means that a reactor operated with a hydrogen superficial velocity uG / uG^ close to 1 and therefore a gas holdup close to 0.299 will have the highest possible liquid filling, while the gas-liquid unit surface is maximized. A hydrogen superficial velocity uG / uG^ above 1 can be used to ensure a higher flow of hydrogen, for example to support the partial pressure of hydrogen and / or the evaporation of conversion products in the reactor. However, in this case, the increase in hydrogen superficial velocity will be limited to include a gas holdup of no more than 0.33, so as not to compromise the liquid filling of the reactor.

[0040] The maximum value reached by the air-liquid unit surface (through a s ^×(1-e g ^) gives) is e g ^ = 0.299 becomes 0.701a s ^. That is, when a s ^When the gas-liquid unit surface is the largest.

[0041] Therefore, the specific air-liquid surface area a s ^ is the physical quantity to be increased to increase the hydrogenation capacity, but a gas holdup of no more than 0.33 and preferably equal to or close to 0.299 is used to operate with the reactor at maximum liquid fill.

[0042] Raise ratio gas-liquid surface a s ^

[0043] As mentioned above, in the liquid-gas mixture produced by a given gas distributor in a bubble column, uG / e g The ratio is proportional to the average diameter of the bubbles, i.e. uG / e g =kd s , which becomes uG^ / e when the bubble is filled g ^ = kd s^, that is, uG^ = 0.299kd s ^. Therefore, it results in that the surface velocity uG^ of the gas (hydrogen) (which completes the bubble filling) is proportional to the bubble diameter generated. The smaller uG^, the smaller the bubble diameter d s ^ will be smaller. In addition, for bubble filling, equation a s =6e g / d s becomes a s ^=1.794 / d s ^. Use uG^=0.299kd s ^, which eventually becomes a s ^=0.536k / uG^.

[0044] This means that the surface velocity of the gas (hydrogen) during bubble filling is completely inverted by the proportionality constant 0.536k, which is the specific gas-liquid surface a generated by the gas distributor. s Using a given gas distributor, the lower the superficial velocity uG^ of the gas (hydrogen) when bubble filling is complete, the larger the specific gas-liquid surface area produced by the gas distributor will be.

[0045] Using a gas distributor with a given orifice density, the surface velocity uG^ of the gas (hydrogen) at the completion of bubble filling can be detected experimentally. As described above, the uG^ value is the surface velocity of the gas (hydrogen) after which g The growth of the product begins to slow down and deviates from the previous linear trend, which is due to the beginning of the coalescence phenomenon. This can be seen in the aforementioned U.S. Patent No. 5,308,476 Figure 1 and more in detail in Figure 5. According to this last reference, when the superficial velocity of hydrogen reaches 0.139 fps (= 4.23 cm / s), the e given by the first three black squares g The initial growth trend of e deviates from the linearity obtained in the slower growth trend (which intersects the first trend). For this value of hydrogen superficial velocity, it is assumed that bubble filling has been achieved. Alternatively and in a simpler manner, the hydrogen superficial velocity at the completion of bubble filling can be obtained by dividing e g The linear trend toward uG intersects with the ordinate 0.299, as Figure 1 Using this mode, a hydrogen superficial velocity of 0.144 fps (= 4.38 cm / s) was obtained, which is a value substantially different from the previous one. Such a method therefore allows to detect in a simpler and in any case sufficiently accurate way the superficial velocity uG^ of the hydrogen, which produces the bubble filling when fed to a given gas distributor.

[0046] Therefore, it has been found that by using a bubble column at every m2 Gas distributors with increasing numbers of orifices (100, 400, 800, 1350 and more orifices) in horizontal cross section distribute the gas (hydrogen), continuously reducing the superficial velocity uG^ of the gas (hydrogen) that produces bubble filling. Therefore, each gas distributor will have a specific uG^ value depending on its orifice density.

[0047] If the gas (hydrogen) is fed at a surface velocity uG^ characteristic of the gas distributor used, consistent with the use of a gas distributor having a given orifice density equal to 100 or greater, then the gas-liquid surface a s ^ will increase, and this does not require increasing the holdup rate above the bubble filling value of 0.299.

[0048] The superficial velocity of the gas (hydrogen) may be slightly higher, but in any case it will be such that the holdup does not exceed 0.33 in order to maintain the liquid filling of the reactor.

[0049] The hydrogenation capacity of a bubble column reactor using a dispersed catalyst (a slurry bubble column reactor, which can be used, for example, for hydroconversion of heavy oils or hydrotreating of vacuum distillates) is achieved by equipping the upflow reactor at its base with a slurry bubble column reactor having at least 100 orifices / m 2 The increase is due to a gas distributor having a pore density of at least 100, which is immersed in the reaction liquid between the reactor walls and is limited to 2.5 / (pore density / 50). 1 / 3 The hydrogen is fed at a superficial velocity of cm / s, which is a function of the orifice density of the same distributor used, such as Figure 2 Therefore, the hydrogenation capacity is increased by enlarging the specific gas-liquid surface, and the value of the gas holdup ratio does not necessarily have to exceed 0.33.

[0050] It is preferred that the hydrogen concentration should not exceed 2.08 / (pore density / 50). 1 / 3 cm / s superficial velocity feed to run with the highest reactor liquid fill while maximizing the gas-liquid unit surface. In this case, the gas holdup will be 0.299 or close to that value.

[0051] In the hydroconversion of heavy oil by conventional upflow reactors (characterized by the use of a low input number / m 2 (less than 64) of hydrogen distribution members), gas holdup values ​​were found to be close to 0.3 (see aforementioned U.S. Patent No. 5,308,476, column 5, line 1), and in no case higher than 0.33. This means that based on practical experience, conditions consistent with or close to favorable bubble filling conditions are constantly used; this is not necessarily intentional, as the impact of the bubble filling phenomenon on the hydroconversion process does not seem to have been fully considered previously.

[0052] However, if a distribution member having a greater number of inlets or orifices is used to split the hydrogen flow while keeping the general feed flow rate constant, the filling of the bubbles is a condition that cannot be maintained. This is confirmed by the resulting increase in gas holdup.

[0053] The present invention thus describes how to maintain favorable bubble packing conditions even when the upflow reactor is equipped with a gas distributor having a high orifice density in order to enlarge the gas-liquid contact surface.

[0054] The method according to the invention always and in any case produces a liquid-gas bubbling mixture under bubble filling conditions, as is currently done, which optimizes the liquid filling of the reactor, but uses bubbles of reduced diameter, by selecting the orifice density of the gas distributor and then by uG^ to achieve the desired increase in hydrogenation capacity as required.

[0055] For a given gas sparger, following the above procedure, at least equivalent measurements of the gas superficial velocity uG^ at which bubble filling is complete can be obtained in the column without being under pressure, or even when not reacting.

[0056] A higher hydrogenation capacity will result in a faster decay of the hydrogen partial pressure along the reactor height. This decay of the partial pressure can be compensated by inserting one or more distribution members along the reactor height to integrate the hydrogen. However, as long as the hydrogen is fed at a superficial velocity shown of not less than 1 cm / s, the reduction in partial pressure can be compensated by over-increasing the orifice density.

[0057] Preferably, by superimposing two or more 2 A simpler structure of a grid with a limited number of openings is obtained with a large number of openings (exemplarily per m 2 For example, a gas distributor with three overlapping grids (each grid has 100 holes per m2) 2 The gas distributor with 270 holes and a hole spacing of 6.08 cm is approximately equivalent to a gas distributor with 270 holes and a hole spacing of 6.08 cm. 2 A gas distributor consisting of a grid with 800 orifices, but with the orifice spacing limited to 3.53 cm. 2 With 270 holes, a total of 10 holes per m 2 The specific gas-liquid surface of the gas distributor composed of 1350 orifices is 2 A sparger with 100 orifices produces three times the specific gas-liquid surface.

[0058] The grids are superimposed at a distance no less than the horizontal spacing between the orifices.

[0059] It is preferred to use a multi-grid gas distributor operating with the high orifice density required to obtain the highest expansion of the gas-liquid contact surface.

[0060] Even in the case of a multi-grid gas distributor, the ability to reduce the uG value can be tested in the reaction as described above.

[0061] In order to obtain a specific expansion of the gas-liquid surface area so as to allow a significant increase in the unit capacity of a slurry reactor for heavy oil hydroconversion or for vacuum distillate hydrotreatment, it is necessary to use the above-mentioned 100 m2 / min. 2 A gas distributor having at least 100 orifices. Since the gas holdup is s ^ does not contribute, so a minimum orifice density of 100 is required. Gas distributors with higher orifice densities must be used to significantly increase hydroconversion capacity and enable complete conversion of heavy oil to light hydrocarbons (350°C-), as will be seen below.

[0062] Heavy oil complete slurry hydrogenation into light hydrocarbons (350℃-)

[0063] In the slurry hydroconversion of vacuum residues with a hydrogen content of 10.5%, a set of conversion products (product composition) is generally obtained, the average hydrogen content of which has risen to 14% by weight. This corresponds to an incorporation of hydrogen in the products equal to 3.5% of the conversion charge (a percentage rising to 4% including gases).

[0064] For usually about 0.1t / h / m 3 The unit capacity of the hydroconversion and the hydrogen addition of 3.5% of the conversion product produce 0.0035t / h / m 3 The hydrogenation capacity of the slurry reactor.

[0065] Now referring to the product composition, it comprises:

[0066] - Light hydrocarbon fraction (350℃-), consisting of LPG, naphtha, and atmospheric gas oil;

[0067] -Heavy fraction (350-540° C.), corresponding to vacuum gas oil.

[0068] If one intends to convert a heavy fraction (350-540°C) which typically has a hydrogen content of 12.5% ​​into a light fraction (350°C-) which has an average hydrogen content of 15.2%, the hydrogen incorporation in the product will rise from 3.5 (14-10.5)% to 4.7 (15.2-10.5)%, which is an increase of 1.34 times. In order to achieve the necessary increase in hydrogenation capacity, the hydrogenation capacity is increased by using a gas distributor equipped with a gas distributor (which has been 2 The number of orifices was selected for the purpose) of the slurry reactor to obtain a specific gas-liquid surface a sSince the specific gas-liquid surface produced by the gas distributor is proportional to 1 / uG^, the orifice density required to obtain an appropriate uG^ value is determined as described below.

[0069] With hydrogen fed at a superficial velocity of 1.98 cm / s per m 2 Gas distributor with 100 holes (see Figure 2 ) compared to the feed rate of hydrogen at a surface velocity of 1.45 cm / s per m 2 A gas distributor with 256 orifices will produce a specific gas-liquid surface area that is increased by a factor of (1 / 1.45):(1 / 1.98)=1.36. 2 Compared with conventional slurry reactors operating with less than 64 orifices, the use of a reactor equipped with 2 The increase in specific gas-liquid surface resulting from a slurry reactor with a gas distributor having 256 orifices would be greater than 1.36 times and would therefore undoubtedly be sufficient to ensure the increase in hydrogenation capacity required for complete conversion of heavy oil into light hydrocarbons (350°C-).

[0070] For a product composition in which the hydrogen content is further increased (e.g., to 16%) so that the hydrogen content of atmospheric gas oil approaches that of paraffins, the hydrogenation capacity of the slurry reactor will have to be increased in proportion to the greater amount of hydrogen incorporated into the product, which will increase from 3.5 (=14-10.5)% of the charge to 5.5 (=16-10.5)%, that is, it will increase by a factor of 1.57. This will be achieved by further increasing the orifice density of the gas distributor. Figure 2 The increase in the pore density (e.g. from 100 pores / m 2 Increased to 800 pieces / m 2 ) results in a halving of the hydrogen surface velocity (from 1.98 cm / s to 0.99 cm / s) and, as a result, a doubling of the gas-liquid surface. Product formation with a hydrogen content in excess of 16% is desired.

[0071] The slurry upflow reactor described in the present application allows to achieve a suitable hydrogenation capacity, which not only fully hydrogenates heavy oil into light hydrocarbons (350°C-), but also obtains a product composition with a high heavy average hydrogen content, which can be used as a petrochemical feedstock.

[0072] In order to completely convert heavy oil to light hydrocarbons (350°C-), the first but not the only necessary condition is a slurry bubble column reactor with the required hydrogenation capacity.

[0073] Due to the following reasons, it is also necessary to use the following Figure 3 The specific slurry hydroconversion process described herein is operated. Figure 3In the embodiment of the invention, the upflow reactor is a bubble column using a dispersed catalyst (slurry catalyst). The concentration of the slurry catalyst increases in proportion to the increase in the specific gas-liquid surface. The slurry catalyst comprises one or more transition metals and is introduced into the reactor via an oil-soluble precursor. Hydrogen is fed to a gas distributor 14 (which has an orifice density selected in relation to the amount of hydrogen to be incorporated into the product composition) with a superficial velocity limited as a function of the orifice density to at least 2.5 / (orifice density / 50) 1 / 3 cm / s, such as Figure 2 It is contemplated and shown in the above, and is preferably limited to 2.08 / (pore density / 50) 1 / 3 cm / s.

[0074] The liquid-gas mixture leaving the reactor 2 at the top is sent to a phase separator 3, which separates a gas phase 10 containing the conversion products in the vapor state and in gaseous form, and unreacted hydrogen. The liquid phase at the bottom of 3 is sent to a reducer (flash tank) 4, at the top of which a further portion of the conversion products 11 is obtained. The liquid at the base of the reducer 4 is sent to a distillation column 5 operating at atmospheric pressure to obtain a distillate 12. The bottom temperature of the column 5 can be reduced to increase the hydrogen content in the product composition. The bottom of the atmospheric column 5 containing the slurry catalyst is usually sent to a distillation column operating under vacuum, in this case after collection in the tank 1, and recycled to the reactor, into which the feed to be converted is also fed.

[0075] The content described in this application is applicable to crude oil, atmospheric residue (usually 350°C +), vacuum distillation residue (usually 540°C +), and 350°C + heavy distillates (such as vacuum distillates) and hydrocarbon mixtures containing them. If the charge consists of crude oil, the feed to the atmospheric column 5 is carried out so that the liquid in the tank 1 does not contain light hydrocarbons (350°C -) in any case.

[0076] In the present invention, the 350-540°C fraction taken out under vacuum in the column is usually returned to the reaction, where it will be converted into light hydrocarbons (350°C -).

[0077] After the conversion of the 350-540°C fraction, the increase in the concentration of light hydrocarbons (350°C-) makes the reaction liquid unstable due to the separation of asphaltenes.

[0078] By feeding the atmospheric bottoms 13 directly into the reactor, significant inhomogeneities appeared in the axial temperature profile of the reactor after a short time. This was a result of the separation of a high viscosity-high density asphaltene phase at the bottom of the reactor, which caused failure of the gas distributor, making hydroconversion unfeasible.

[0079] In order to manage the concentration of light hydrocarbons (350°C-) in the reaction liquid so that this can be restored as required, both the atmospheric residue 13 and the charge 6 are collected in the same tank 1 to form a mixture (350°C+) free of light hydrocarbons (350°C-), which is fed to the reactor through pipeline 9 at a flow rate equal to twice the charge feed, and this is carried out at a flow rate greater than twice, thereby reducing the concentration of light hydrocarbons (350°C-) in the reaction liquid by about half and more than half.

[0080] Since a closed loop recirculation system is described, the flow rate of the feed charge is that at which a constant liquid level 7 is maintained in the tank 1 .

[0081] Feeding a mixture of atmospheric residue and charge in this way, light hydrocarbons (350°C -) are removed more quickly from the reaction liquid, which will allow the reactor to return to its initial conditions. The restoration of axial temperature uniformity will confirm the restoration of reactor functionality. Based on the description provided for exemplary embodiments, it is obvious that a person skilled in the art may introduce some modifications without thereby departing from the scope of the invention as defined in the following claims.

Claims

1. A method for hydroconverting heavy oils including crude oil and hydrotreating vacuum distillates by an upflow bubble column reactor using a slurry-type catalyst, the reactor having an internal gas distribution member, the distribution member: The feed contains hydrogen or a gas including hydrogen, housed in the lower part of the reactor so as to be immersed in the reaction liquid, and comprising a plurality of orifices for injecting hydrogen or a gas comprising hydrogen into the reaction liquid, Each m of the distribution member 2 There are at least 100 orifices in the horizontal cross section, Each m of the distribution member 2 The number of orifices on a horizontal cross section is called the "orifice density". The method comprises: removing the conversion products in a distillation section downstream of the reactor, and recycling the residue of the distillation section to the reactor, The method is characterized in that hydrogen or a gas comprising hydrogen is fed to the distribution member at a superficial velocity expressed in cm / s not exceeding: 2.5 / (pore density / 50) 1 / 3 , The ratio (pore density / 50) is dimensionless.

2. The method according to claim 1, characterized in that hydrogen or a gas comprising hydrogen is fed to the distribution member at a superficial velocity not exceeding the following, the superficial velocity being expressed in cm / s: 2.08 / (pore density / 50) 1 / 3 , The ratio (pore density / 50) is dimensionless.

3. The method according to claim 1 or 2, characterized in that: Feeding the charge (6) to be converted into the tank (1), sending the residue to the tank (1) to form a mixture comprising the charge and the residue, and feeding the mixture into the reactor (2) at a flow rate at least equal to twice the flow rate at which the charge is fed into the tank (1), The charge is fed into the tank (1) at a flow rate such that the level of the mixture in the tank (1) is kept constant.

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