EP1637576B1 - Hydroconversion of a heavy feedstock using a dispersed catalyst - Google Patents

Description

Field of the invention

The present invention relates to a process for hydroconversion of a heavy petroleum feedstock in which it undergoes cracking and / or purification reactions in the presence of hydrogen.

The invention is therefore particularly applicable to hydrocracking and hydrotreatment processes such as the hydrodesulphurization, hydrodenitrogenation, hydrodemetallization or hydrodearomatization processes of various petroleum fractions.

The feedstocks treated by this type of process are heavy feedstocks such as distillates or residues resulting from the distillation of oil under vacuum. The treated fillers may also be coals or cokes introduced into suspension in liquid petroleum fractions. More generally, the process is particularly suitable for the treatment of petroleum fractions such as atmospheric residues obtained by atmospheric distillation at the bottom of the column or a fraction of these residues, or the residues resulting from distillation under vacuum (bottom of column). These cuts are generally characterized by a boiling point greater than 340 ° C for at least 90% by weight of the cut. The process is particularly applicable to heavy loads having a boiling point greater than 540 ° C for at least 80% by weight of the feedstock. They have (fresh feeds) a viscosity of less than 40,000 cSt at 100 ° C, and preferably less than 20,000 cSt at 100 ° C. They usually have to be converted to produce finished products such as diesel, gasoline and LPG, with lower boiling point. These cuts are generally also purified because they contain amounts of sulfur, metals (especially nickel and vanadium), nitrogen, conradson carbon and asphaltenes which must decrease to allow lighter cuts produced by conversion of be processed in downstream purification processes or to meet final product specifications.

More specifically, said invention makes it possible to inject a dispersed phase containing a catalytic precursor promoting hydroconversion and to proceed with its activation by virtue of rapid contact under the conditions appropriate for its activation without thermally degrading it to form an active catalytic phase in the reactor. and then hydroconverting the heavy products in one or more reaction zones in the presence of hydrogen.

Preferably, the reaction zone of the process therefore operates in a bubbling bed (presence of a catalyst as defined below) or in slurry (in the presence of a circulating catalytic phase).

The present invention finds its application in the conversion of a heavy hydrocarbon feed introduced essentially liquid into a reaction zone, said conversion being carried out by contacting with a gaseous phase, comprising hydrogen (hydroconversion) and with a catalytic phase and / or a catalyst, under conditions favorable to hydroconversion, that is to say at a total pressure of 10 to 500 bar, preferably 20 to 300 bar, with a hydrogen partial pressure ranging from 10 to 500 bar, preferably from 20 to 300 bar, with a temperature of 350 to 500 ° C, the contact taking place for a certain time necessary for the conversion of the residue, ranging from 5 minutes to 20 hours, and preferably between 1 and 10 hours. hr. Depending on the applications, it is possible to envisage recycling with the feedstock some of the heavy fractions of the effluents having a boiling point substantially equal to or greater than that of the feedstock by fractionation by distillation, for example of the effluent downstream of the feedstock. the reaction zone or the process zone (downstream of the last reaction zone).

• la phase catalytique voyagera donc dans la (les) zone(s) réactionnelle(s) du procédé selon l'invention et sortira (au moins en partie) du réacteur, du procédé avec les effluents liquides.
• le catalyseur restera dans le réacteur

Subsequently, the term "catalytic phase" refers to the solid resulting from the conversion of a catalytic precursor injected into the process and which can be entrained by the liquid, the term catalyst refers to a solid present in the reaction zone having properties catalytic, and whose properties of size and density are such that it is not driven by the liquid out of the reactor. Thereby:

• the catalytic phase will therefore travel in the (the) zone (s) reaction (s) of the process according to the invention and will leave (at least in part) the reactor, the process with the liquid effluents.
• the catalyst will remain in the reactor

State of the art:

The ebullated bed process used for the hydroconversion of heavy hydrocarbon fractions or coal is a well-known method which generally involves contacting, in a co-current flow, a hydrocarbon feedstock. liquid phase and a gaseous phase in a reactor containing a hydroconversion catalyst. The reaction zone preferably comprises at least one reactor equipped with at least one catalyst removal means located near the bottom of the reactor and at least one additional catalyst means near the top of said reactor. This makes it possible to continuously add and remove the catalyst and maintain the activity thereof if deactivation phenomena are observed. Said reaction zone comprises most often at least one circuit for recycling the liquid phase, located inside or outside the reaction zone, said recycling being intended, according to a technique known to those skilled in the art , to maintain a sufficient level of expansion of the bed to ensure the proper functioning of the reaction zone in three-phase (gas / solid / liquid). Thanks to this recycling, the catalyst is maintained in the fluidized state.

The patent US Re25,770 describes for example such a method. A mixture of liquid hydrocarbons and hydrogen is injected through a catalyst bed in such a way that the bed is expanded. The level of catalyst is controlled by recycling the liquid, said catalyst level remaining below that of the liquid. The gas and the hydrogenated liquid pass through an interface defining an area containing most of the solid particles of the catalyst bed and are found in a zone substantially free of said particles. After a gas / liquid separation of the fluids resulting from the reaction, said fluids are then divided into two fractions: a fraction containing most of the liquid is recycled to the boiling pump and another part is withdrawn from the reactor with the gas.

The bubbling bed process employs a supported catalyst containing metals whose catalytic action is in the form of sulfide, the size of which is such that the catalyst remains in the reactor overall. The liquid velocity in the reactor makes it possible to fluidize this catalyst but does not make it possible to drive it outside the reaction zone with the liquid effluents. Continuous addition and removal of catalyst is possible and makes it possible to compensate for deactivation of the catalyst.

The patent US2003 / 0021738 shows a new implementation bubbling bed further to separate in the reactor effluent gas from liquid effluents. This new implementation is interesting because it makes it possible to evacuate the liquid effluents separately from the gaseous effluents, while ensuring a liquid recycling to the reactor. separation taking place at the temperature and pressure conditions of the reactor. It is an advanced implementation of slurry and ebullated bed technologies adapted to the hydroconversion of residues, making it possible to limit the number of high pressure equipment in the reaction zone while maintaining easy control of important operating parameters (liquid level and level). catalyst in the reactor).

The patent US 3,231,488 shows that it is also possible to obtain hydrorefining heavy loads in the presence of a soluble catalyst. In this patent, the inventors claim that metals injected in an organometallic form (the assembly forming a catalytic precursor) can form in the presence of other substances (such as asphaltenes colloids), in the presence of hydrogen and or of H2S a finely dispersed catalytic phase for hydrorefining the residue after injection into the feedstock. This catalytic agent then passes through the reaction zone without being separated from the liquid in the reactor. Although it is not known precisely, the size of the particles of the catalytic phase formed in this type of process remains small enough that it is difficult to fluidize these particles in the reaction zone without driving them with the liquid. This is then a slurry implementation unlike the previous method implemented in bouillonant bed. Examples of reactors operating according to the principles specific to slurry beds and bubbling beds and their main applications are for example described in "Chemical reagents, P. Trambouze, H. Van Landeghem and JP Wauquier, ed. Technip (1988) ).

In the patent US 4,244,839, CL Aldridge and R.Bearden claim a catalytic phase, especially for the hydroconversion of residues, prepared from a catalytic precursor containing a thermally decomposable metal compound which is contacted with a conradson carbon-containing feedstock and then contacted at high temperature in the presence of hydrogen and H2S. Many catalytic precursors can act as a thermally decomposable metal compound; in this patent mention is made of molybdenum, chromium, vanadium, cobalt, nickel naphthenate, tungsten or titanium resinate, phosphomolybdic acid, etc. The list is not exhaustive.

In general, the action of these metal compounds is now quite well known: under certain conditions, preferably in the presence of hydrogen sulphide and these salts, acids or compounds containing Group II, III, IV, V, VIB, VIIB or VIII metals decompose and become sulphurous to form metal sulphides whose catalytic activity in hydroconversion processes favors reactions of cracking, hydrogenation, hydrodesulfurization, hydrodenitrogenation and hydrodemetallation (...) of heavy hydrocarbons. The complexing of the metal atom (s) with complex organic structures such as resins or asphaltenes present in heavy feeds appears to be acquired and makes it possible to form a catalytic phase of very small particles containing an active phase based on metal sulphide and coke. Thus, for this type of slurry process, a catalytic precursor in a heavy hydrocarbon feedstock was injected into an upstream zone of the reactor and then this precursor was activated to obtain a finely dispersed catalytic phase which was then injected into the reactor and which will flow with liquid products.

This implementation in slurry could be advantageous compared to the implementation in bubbling bed under certain conditions. In fact, the fine dispersion of the catalytic phase in slurry mode can make it possible to promote the hydrogenation and the conversion of very large hydrocarbon structures, such as resins and asphaltenes, the ultimate conversion of which is made difficult on the catalysts supported by the more limited accessibility of active sites inside the pores. In the case of highly metallized fillers as well, a slurry process can be very advantageous because the metals, known to promote the deactivation of the catalyst, are discharged continuously with the finely dispersed catalyst and no longer accumulate on the supported catalyst. (This would then require the implementation of very important additions and catalyst withdrawals). It is clear that this implementation is particularly interesting if the deactivation is important.

Let's also mention the patent EP 0559 399 which proposes to simultaneously implement a catalyst supported in the presence of a dispersed slurry catalyst, formed by decomposition of a catalytic precursor such as a metal naphthenate. In the presence of aromatic injection, this makes it possible to limit the amount of insolubles formed in the products and thus to improve the stability of the products.

However, for slurry processing to be effective, the conversion of the catalytic precursor must be perfectly controlled. Thus, Cyr et al., In the patent US 5578197 mention that the catalytic precursor, if heated for a certain time under unsuitable conditions, can lead to significant coke formation during hydroconversion reactions (they mention the formation of large particles up to at 4 mm, these particles would behave in the reactor as a catalyst and not a catalytic phase and would therefore have great difficulty to be entrained with the liquid, which would induce risks of agglomeration and clogging inside the reactor) . Cyr et al. provide a controlled mixture under mild conditions to promote dispersion prior to heating the precursor and introducing the precursor or catalyst phase into the reactor.

Many implementations of the molybdenum precursor are presented in the literature. So the patent 4244839 proposes the mixture of the catalytic precursor with the feedstock upstream of the reactor and the direct injection into it ( Fig.1 cited patent) in the presence of hydrogen and H2S. There is no mention of preheating the load upstream of the reactor. However, for a process of hydroconversion of residues to operate under favorable conditions, it is essential to preheat the load and increase its pressure in accordance with the conditions required to carry out the reaction, before its introduction into the reactor. It is therefore likely that such a device leads to a thermal degradation of the molybdenum precursor before its introduction into the reactor and adversely affects its subsequent catalytic activity.

In the patent 3674682 a slurry hydroconversion process is claimed. Here again, the dispersed catalyst is injected upstream of the reactor with the feedstock and hydrogen, which will presumably produce its thermal degradation as mentioned in the previous paragraph.

In the patent 6043182 a method of preparing a catalytic precursor upstream of a reactor is claimed. The catalytic precursor in aqueous form is mixed with a hydrocarbon to form an emulsion and then heated to remove water before the reactor. Again, there is a risk of thermal degradation of the organometallic complex formed with the heavy compounds once the aqueous phase evaporated before introduction into the reactor.

In the patent 5108581 a process for the hydroconversion of residues including a catalytic precursor preparation zone is proposed: mixing with a heavy hydrocarbon and then sulphurizing in an enclosure at least 500 ° F for a certain time necessary for the conversion of the molybdenum precursor to the sulphide before introduction into the hydroconversion reactor. Such a device is complex because it requires contact with a sulphurizing agent in a specific enclosure. To avoid thermal degradation of the charge, it is necessary to maintain the temperature presumably under 350 ° C which certainly imposes a long enough sulphurization time and therefore requires a sufficiently large enclosure for the mixture to stay for the time necessary.

We can also quote US 5094991 in which the catalytic precursor is injected into the recycling line of the unconverted residue obtained after distillation followed by deasphalting, and the flux containing the asphaltenes and the catalyst is subjected to regeneration, the decontaminated regenerated catalyst then being added with the precursor and then sulphurized before to be injected into the load to be treated.

In GB-2,123,025 the coal is liquefied and after liquid-gas separation and deasphalting, the catalyst slurry is recycled. Before being sent to the reactor, the coal particles are mixed, in a mixing zone upstream of the reactor, with an asphaltenic solvent and optionally with recycled slurry, the precursor being able to be added again.

Thus, in all the processes of the prior art, in the absence of strict control of the temperature conditions (ie operating below 350 ° C.), there is partial thermal degradation of the catalytic precursor. This results in a limited activation of the precursor in the catalytic phase and the formation of large particles, often sticky, difficult to remove from the reaction zone and which could sediment, coker and plug the reactor.
Nevertheless, the activation of the catalyst requires the contact, in the presence of heavy molecules, of the catalytic precursor with a sulfurizing agent such as hydrogen sulphide (H2S). This contact generates sulphidation of the metal or metals contained in the catalytic precursor and this reaction is even faster than the temperature is high. If the temperature is not high enough, thermal degradation reactions of the precursor making it more difficult its sulfurization can be observed during the course of the sulfurization.

To overcome these drawbacks, the prior art proposes the control of the conditions of mixing and exposure to temperature. However, this lengthens the catalyst preparation time and induces additional investments.

Another method has been investigated which allows sufficient activation but without degradation of the catalytic precursor. Unexpectedly, and contrary to the prior art, the method of the invention provides a solution of extreme simplicity of implementation, and for embodiments bubbling bed, it uses provisions already existing in industrial units, thus reducing installation costs. The invention also overcomes the disadvantages of the methods of the prior art.

Summary of the invention

More specifically, the invention relates to a process for hydroconversion in a reaction zone of sulfur-containing liquid heavy hydrocarbon feedstocks, in the presence of hydrogen and a catalytic solid phase as described by claim 1.

The invention therefore consists in injecting the catalytic precursor into a part of the liquid products of the reaction containing dissolved hydrogen sulphide, under conditions as close as possible to the temperature and pressure conditions at the outlet of the reactor. In hydroconversion processes, the reaction is in fact generally exothermic and the highest temperature is generally encountered at the outlet of the reactor. The liquid products of the reaction contain a substantial portion of dissolved hydrogen sulfide from the hydrodesulfurization of the charge molecules which occurs during the hydroconversion reactions. Finally, the liquid products of the reaction also contain unconverted fractions of the feedstock in non-negligible amounts, such as asphaltenes, which will form the desired catalytic phase with the metal sulphide.

It is important to remain, at the time of injection of the precursor into the process, under conditions close to those encountered at the reactor outlet. The temperature must indeed remain as high as possible close to the temperature of the reactor to promote the sulphurization of the catalytic precursor. If, on the other hand, the temperature is much higher than in the reactor, a drop in the concentration of sulfur in the liquid resulting from the desorption of sulfur-containing molecules such as dissolved H2S will be observed also limiting the sulphidation of the catalytic precursor. . The pressure must also remain close to the outlet pressure of the reactor; an excessive pressure drop would have an effect similar to an increase in temperature; an increase in pressure would, on the other hand, have no detrimental effect on the conditioning of the precursor.

It will therefore be ensured that the temperature Tmel, mixing temperature, resulting from the contact of the precursor with the liquid conversion products, is in the range (Ts = temperature of their exit from the reaction zone) Ts +/- 10 ° C. , and that the total pressure of contacting

Pmel is (Ps = total pressure Ps at the outlet of the reaction zone) Ps +/- 10 bar, preferably Ps +/- 5 bar.

Generally the temperature Tmel greater than 350 ° C, and preferably between 380 and 500 ° C.

The temperature Tmel is between 380 and 500 ° C.

These favorable conditions are found in the recycling line (s) of the reaction effluents (before total separation of the hydrogen sulphide), whether they are (are) external or internal to the reactor.

The invention thus relates more precisely to the injection of a catalytic precursor in the presence of products of the hydroconversion reaction, in a line for recycling the liquid internal to the reaction zone where the presence of hydrogen sulphide is found. , a high temperature favorable to the rapid sulphurization of the precursor and asphaltenes. The pressure and temperature conditions encountered under these conditions are indeed very close to the reactor outlet conditions, the pressure drop and the hydrostatic pressure variation in the near recycling line, to the possible thermal losses.

More particularly, the present invention relates to a heavy charge hydroconversion process using a catalytic precursor injected, preferably regularly, into one or more reactors that can be provided with internal recycling means of the liquid fractions, under conditions allowing its activation. optimal without degradation.

These internal recycling lines of the liquid are known to those skilled in the art and already widely used in bubbling bed reactors to recycle a portion of the liquid and increase the superficial velocity of the liquid in the reactor and promote the boiling of the supported catalyst in processes employing this type of catalyst, such as H-Oil residue hydroconversion processes. Their use as an initial contact zone of a catalytic precursor is an innovation proposed in the context of this invention.

In the case where the conversion products from the reaction zone are separated in an internal liquid / gas separator, the catalytic precursor is injected into the recycled liquid portion to the reaction zone.

In the case where the conversion products from the reaction zone are separated in an external liquid / gas separator, the catalytic precursor is injected into the recycled liquid portion to the reaction zone.

In the case where the catalytic precursor is injected before the liquid / external gas separation, the catalytic precursor is recycled to the reaction zone with the recycled conversion products.

All these embodiments are used alone or in combination.

The catalytic precursors that can be envisaged in the context of the invention are typically organometallic compounds, salts or acids, linked to one or more metals of groups II, III, IV, V, VIB, VIIB or VIII, such as molybdenum compounds such as molybdenum naphthenate, molybdenum octoate, ammonium heptamolybdate or phosphomolybdic acid.

• Pression totale comprise entre 10 et 500 bars, préférentiellement 20-300 bars
• Pression partielle d'hydrogène comprise entre 10 et 500 bars, préférentiellement 20-300 bars
• Température comprise entre 350 et 500°C
• Temps de séjour des hydrocarbures liquide dans la zone réactionnelle entre 5 mn et 20hr, préférentiellement entre 1h et 10hr.

The conditions for hydroconversion are as follows:

• Total pressure between 10 and 500 bar, preferably 20-300 bar
• Partial hydrogen pressure of between 10 and 500 bar, preferably 20-300 bar
• Temperature between 350 and 500 ° C
• The residence time of the liquid hydrocarbons in the reaction zone between 5 min and 20 h, preferably between 1 h and 10 h.

According to a preferred embodiment of the invention, the temperature in the injection line (before contacting the catalytic precursor with the liquid conversion products) will be less than 200 ° so as to avoid any thermal degradation of the precursor before its transformation. in the catalytic phase. The catalytic precursor will then be brought into contact with at least a portion of the effluents of the reaction, under conditions close to the conditions of the outlet of the reactor considered for injection, as described above.

The precursor is preferably injected regularly and preferably continuously. It can also be injected intermittently according to the needs of the process.

For this process, a supported catalyst may be disposed in the reaction zone and used as a bubbling bed; the process in the reaction zone can also be carried out in slurry form.

Several reaction zones can be linked to one or more reactors in series or to several trains in parallel of series reactors, the reactors may comprise clean recycling means of the liquid, and separation means downstream of the reactors.

In the case of a set of several reactors in series, the catalytic precursor will preferably be injected in contact with the reaction effluents of the first reactor.

Said first reactor will preferably comprise internal recycling means of the liquid. The other reactors may also comprise said means. Between 2 successive reactors, at least one external separation means is advantageously arranged in order to at least partially degas the effluent.

Moreover, separation means by distillation will eventually allow the heavy fractions to be separated (boiling point generally equal to or greater than that of the feedstock). reaction effluents from the zone (or zones) reaction (s) (and preferably the last zone when the process has several). At least part is recycled as well as part of the catalytic phase (contained in said fractions) upstream of the process, at the inlet of one of the reactors (generally in the first reactor) mixed with its liquid feed. The conversion of the residual fractions is favored and the amount of catalytic phase is increased in the reaction zone.

Usually, there is provided a preheating zone of the charge and the gas containing hydrogen.
In order to limit the flocculation (under certain conditions) of unconverted heavy compounds such as asphaltenes, an aromatic section (with high aromaticity such as, for example, a catalytic cracking HCO section) can be injected into the process, for example with the feedstock. upstream of one of the zones (reactors) of the process or with the effluent before the distillation and for example with the fresh feed, or at the level of the external separator when it exists or distillation.
These modes can be combined.

The conversion products will, after the hydroconversion, usually be separated, preferably by distillation.

The invention also relates to a device including at least one reactor with a reaction zone (6) containing a catalytic phase formed from a catalytic precursor, at least one pipe (4) for the introduction of a heavy liquid charge containing sulfur, asphaltenes and / or resins, and a hydrogen-conducting conduit (3), at least one liquid conversion product discharge line and at least one catalytic precursor injection line in at least one part of the liquid conversion products, saturated with H2S and containing asphaltenes and / or resins.

Preferably, this device comprises, connected to the discharge line of the liquid conversion products, a recycling line (8) towards the reaction zone of at least a portion of the liquid conversion products, saturated with H2S and containing asphaltenes. and / or resins, and a line for injecting the catalytic precursor into said recycling line (8). Advantageously, the recycled liquid has been at least partially degassed by passing through a liquid / gas separator external or internal to the reactor, to separate a liquid-gas or liquid fraction.

In an advantageous embodiment, the device is provided with a conduit external to the reactor for discharging the effluents (including the liquid conversion products) out of the reactor, of a pipe (14) for injecting the catalytic precursor into the reactor. pipe (7), a liquid / gas separation means (20) external to the reactor for separating a part of the liquid conversion products containing dissolved hydrogen sulphide, asphaltenes and / or resins, said part being at least partially recycled to the reaction zone via a pipe (8).

In another embodiment, the device is provided with a conduit external to the reactor for discharging the effluents (including the liquid conversion products) out of the reactor, a liquid / gas separation means (20) external to the reactor to separate a reactor. part of the liquid conversion products containing dissolved hydrogen sulphide, asphaltenes and / or resins, said part being at least partially recycled to the reaction zone via a pipe (8) and the device being provided with a pipe (10). or 11) for injecting the catalytic precursor into the recycle line (8).

In another mode, the device is provided with an internal liquid / gas separator (20) for separating a portion of the liquid conversion products containing dissolved hydrogen sulphide, asphaltenes and / or resins, said portion being removed and at least partly recycled to the reaction zone via a pipe (8), and the device being provided with a pipe (10 or 11) for injecting the catalytic precursor into the recycling pipe (8).

The modes described are used alone or in combination.

The device may comprise at least two successive reactors each having a reaction zone (6) containing a catalytic phase formed from a catalytic precursor, with a first reactor as described above, provided with a recycling line of effluent from the first reactor to said first reactor, the separated non-recycled liquid being sent to the next reaction zone or discharged.

In a preferred embodiment, the device comprises at least 2 successive reactors each having a reaction zone (6) containing a catalytic phase formed from a catalytic precursor, with a first reactor as described above, said device comprising for each reactor a liquid recycle line after at least partial degassing in a liquid / gas separator, the separated non-recycled liquid being sent to the next reaction zone or discharged.

Furthermore, the device (in its generality) advantageously comprises at least one distillation column located after the last reaction zone, for separating the heavy fractions from the reaction effluents which contain a part of the catalytic phase, and a pipe for recycling a part at least said upstream fractions with its liquid charge.

Advantageously, the device is provided with at least one pipe for introducing an aromatic section into the feedstock upstream of at least one reactor and / or in the effluent before distillation.

• la figure 1 représente un réacteur avec une ligne de recyclage issue d'un séparateur externe et des modes de réalisation de l'injection de précurseur catalytique.,
• la figure 2 montre une ligne de recyclage issue d'un séparateur interne et également des modes de réalisation de l'injection de précurseur catalytique,
• la figure 3 inclut les 2 types de ligne de recyclage issue d'un séparateur gaz/liquide interne,
• la figure 4 représente une zone à 2 réacteurs ,chacun ayant une ligne de recyclage issue de séparateur interne.

The Figures 1 to 4 illustrate the invention:

• the figure 1 represents a reactor with a recycling line from an external separator and embodiments of the catalytic precursor injection.
• the figure 2 shows a recycling line from an internal separator and also embodiments of the catalytic precursor injection,
• the figure 3 includes the 2 types of recycling line from an internal gas / liquid separator,
• the figure 4 represents a zone with 2 reactors, each having a recycling line from internal separator.

According to a first embodiment of the invention ( figure 1 ), the hydroconversion of the residues is carried out in a reaction zone consisting of a single reactor. Load of heavy hydrocarbons, advantageously consisting essentially of compounds derived from the bottom of the atmospheric distillation or of the vacuum distillation of a petroleum fraction, flows in a line (1) at a temperature permitting its flow, generally ranging between 50 ° and 180 ° depending on the nature of the charge and its boiling properties.

The charge is then pressurized (generally between 10 and 500 bar, often around 100-300 bar), for example by means of pumps (15) and then preheated without thermal cracking, for example in an oven (16). On residue-type petroleum feeds, the temperature at the outlet of the furnaces is voluntarily limited to 300-380 °, preferably 350 ° C., in order to avoid any cracking and any thermal degradation related to the temperature.

The pressure and thus preheated charge (2) is then mixed with a gas (3) containing hydrogen and preferably a very large proportion of preheated hydrogen, preferably in a separate oven (17), at a temperature of from 100 to 800 °, and preferably between 300 and 600 °.

Mixing the feedstock with the gas containing the hydrogen makes it possible to adjust the temperature of the feed + gas mixture (4) to a temperature close to that of the reaction (typically 380-500 ° C.) without degrading the heat load.

The assembly is then introduced into the reactor (18) in a mixing zone (5) located upstream of distribution means (19) (on the fig.1 reactor distribution chamber) allowing uniform distribution over the section of the reaction zone of the gas and the liquid. Other methods of conditioning the charge are also possible: for example, the charge (1) and the gas (3) containing the hydrogen can be mixed before the charge preheating furnace (16). It is also possible to introduce, on the one hand, the liquid under pressure and preheated, and on the other hand the gas under pressure and preheated separately in the reaction zone. It is then simply necessary to increase the pressure of the charge and the temperature of each flow to meet the temperature and pressure conditions required to perform the reaction.

The gas (3) mixed with the feedstock and containing hydrogen generally comes partly from the recycling of uncondensed gaseous fractions downstream of the reaction zone, optionally purified to remove the H 2 S formed during the reaction and to which will be added a adding hydrogen to compensate for the consumption of a part of this gas in the reaction zone.

The mode of introduction of the charge and the hydrogen described in the present case is only illustrative and does not limit the invention. All these types of charge conditioning are well known to those skilled in the art.

The reaction is carried out in the zone of the reactor (6) (reaction) located above distribution means (19) in which there is optionally a supported catalyst, in the form of balls or extrudates of equivalent diameter generally between 0.25 and 10 mm and density of dry grain generally between 1000 and 5000 kg / m3. The reaction zone is preferably a substantially elongated zone in which the superficial velocity of the liquid is sufficient to maintain the boiled supported catalysts (VSL> VMF) and to avoid settling and sedimentation of all the particles formed from the catalytic precursor in the reaction zone. reactor and avoid entrainment of all supported catalyst particles (VSL <UT).

At the outlet of the reactor, the gas and liquid effluents (7) (including the catalytic phase consisting of particles formed from the catalytic precursor) are discharged to a degasser (20) external to the reaction chamber. The supported catalyst remains in the reaction chamber because the superficial velocity of the liquid is not sufficient to cause its entrainment. The function of the degasser (20) is to disengage most of the gas (at least large bubbles) from a portion of the liquid. The at least partially degassed liquid (8) is recycled to the inlet of the reactor (18) through a pump (21) to restore the necessary pressure. The gas and the non-degassed liquid are discharged through the pipe (9). The degassed liquid (8) and the non-degassed liquid (7) still contain a large portion of dissolved H2S, since the temperature and the pressure are substantially those of the reactor (18), the thermal losses and the pressure losses of the equipment close to the reactor. . It is therefore possible to add the catalytic precursor downstream of the reactor (18). Thanks to the internal recycling, this one will then be reintroduced in the reactor (18) the precursor will be immediately subjected to a high temperature in the presence of H2S which will allow the sulphuration of the precursor and the formation of fine particles in contact with asphaltenes not converted to the outcome of the passage in the reactor.

The catalytic precursor is injected by a pump directly into contact with the products of the reaction

On the figure 1 and the other figures, several possible points have been represented for the injection of the catalytic precursor. These modes are not limited to the precise embodiments of the figures and can be used alone or in combination.

The catalytic precursor may be injected into a liquid saturated with H2S and at least partially degassed (circulating in the recycle line (8)) upstream (reference 10) or (reference 11) downstream of the boiling pump (21) or upstream of the degasser (reference 14).

In each of these cases, the catalytic precursor will encounter high temperature H2S and unconverted asphaltenes. Injections (10) and (11), thanks to the absence of gas bubbles, however, allow better control of the mixture and therefore represent a preferred embodiment of the invention. In addition, the contact temperature between the precursor and the effluents is higher there than in (12) for example, because the effluent is not diluted with the fresh feed. This will result in more effective activation.

It will be noted that the figure 1 presents a preferred mode with recycling of a portion of the effluent from the reaction.

At the outlet of the degasser, a liquid gas separation is carried out under pressure in the flask (22). The liquid leaving the bottom of the separator (22) is generally sent after expansion to a fractionation to recover the converted petroleum fractions and residual fractions. The gas leaving the top of the separator (22) then passes into a separator train, from which incondensables including hydrogen can be extracted which are often recompressed and recycled in the process upstream of the reaction zone after treatment.

The figure 2 represents another embodiment of the invention different from the first in that the outgassing at the outlet of the reactor is carried out internally in the reactor (18), the other arrangements described above being valid for this embodiment.
The mixture of liquid hydrocarbons and hydrogen is injected through a distributor (19) into the reactor (18). We will not repeat here the description of the conditioning of the load identical to the previous figure.
If catalyst is present in the reactor, the liquid flow rate in the reactor resulting from the fresh feed rate (4) and the internal recycle (8) is controlled so that the catalyst bed is expanded. The level of catalyst is controlled by the recycling (8) of the liquid.

At the outlet of the reaction zone (6), after a gas / liquid separation in an internal separator (20) from the fluids resulting from the reaction, said fluids are then divided into two fractions: a fraction containing most of the liquid is recycled by the pipe (8) to the boiling pump (21) and another part is withdrawn from the reactor with the gas (9). The recycled liquid is reintroduced into the reaction zone preferably via a separate pipe ( figure 2 ).

Possible points are recognized for the injection of the catalytic precursor, as described from FIG. figure 1 . The catalytic precursor can be injected into a liquid saturated with H2S and at least partially degassed (flowing in the discharge pipe (7) or recycling (8)) upstream (reference 10 or reference 11) downstream of the pump. boiling (21).
The conditions Ps and Ts are those prevailing at the internal separator (20). Advantageously, on the liquid / gas part withdrawn by the pipe (9) a gas / liquid separation is carried out in the balloon (22), the provisions relating to this part which are described in fig.1 suitable.

For the figures 3 and 4 , we will not repeat here the description of the conditioning of the load identical to that of the previous figures.

The figure 3 represents a third embodiment of the invention, differing from the second in that the separator (20) located in the reactor (18) is now a set of means for separating the liquid from the gas and not the liquid of a gas-liquid mixture. As a result, the reactor effluent (24) is now a substantially gaseous phase (possibly containing unseparated liquid traces). The non-recycled part of liquid products is now evacuated by a line (23) located upstream or downstream (preferred) means for pumping the liquid (21), but upstream of the distribution chamber (19).
At the outlet of the reactor from the reaction zone (6), after a gas / liquid separation in an internal separator (20) from the fluids resulting from the reaction, said fluids are then divided into two fractions: a fraction containing most of the liquid is recycled via line (8) to the boiling pump (8) (21) and another gaseous portion is withdrawn from the reactor via line (24).
The recycled liquid is reintroduced into the reaction zone preferably via a separate pipe ( figure 3 ).
Possible points are recognized for the injection of the catalytic precursor, as described from FIG. figure 1 . The catalytic precursor may be injected into a liquid saturated with H2S and at least partially degassed (flowing in the pipe (7) or recycling (8)) upstream (reference 10) or (reference 11) downstream of the pump. boiling (21).

The conditions Ps and Ts are those prevailing at the internal separator (20).
It will be noted that the gas separation of the liquid is carried out in the separator (20), so that the balloon (22) describes on the figures 1 and 2 is not always useful.

The figure 4 represents an embodiment of the invention in which several reactors are connected in series
We recognize the provisions referenced (1) to (23) of the fig.2 for the first reactor equipped with an internal separator.

In the specific case of figure 4 the second reactor is fed (line 26) by the non-vaporized fractions from the first reactor containing the bulk of the unconverted fractions, separated by an external separator of the type (22) from that of the figure (2 ).
In another arrangement (not shown), the second reactor can be fed by the non-recycled liquid portion of the first reactor provided with an internal separator of the type (20) of the figure 3 this part having preferably been degassed at least partially.
Preheated or unheated hydrogen is then generally introduced into the liquid feedstock of the second reactor (line 26). It is also possible to cool the liquid effluent from the first reactor before its introduction to the second reactor.

Adding a second reactor allows for an identical reactor volume to improve the conversion. Indeed, the succession of two mixed conversion areas of small volume allows a better conversion than a single mixed zone of equivalent volume. Such a device also makes it possible to impose a temperature gradient between the two reactors, which can make it possible to better control the stability of the products formed, especially when the conversion of the residue is very high. The operation of the second reactor is generally substantially similar to the operation of the first reactor. A distributor (29) allows the good distribution of gas and liquid. The reaction is carried out in the reaction zone (30) located in the reactor above the distributor (19), in the presence or absence of catalyst.

The effluents are separated in an internal separator (31) as in the fig.2 , allowing to recycle a portion of the liquid effluents from the reaction (evacuation-recycling line 32) and to evacuate the non-recycled gas-liquid effluents (line 34).
Downstream of the reactor, a separator (35) separates the gas, discharged at the top (line 37) and liquid discharged at the bottom (line 36).

The conversion products are recycled via a pump (33) to the reaction zone.

In the case of multiple reaction zones as shown on the figure 4 the catalytic precursor is injected by a pump directly into contact with the reaction products of the first reactor, alone. In order to avoid any thermal degradation of the catalytic precursor, its temperature is preferably maintained at 190 ° C.

Possible points are recognized for the injection of the catalytic precursor, as described from FIG. figure 2 . The catalytic precursor may be injected into a liquid saturated with H 2 S and at least partially degassed (circulating in the recycle line (8)) upstream (reference 10) or (reference 11) downstream of the boiling pump (21) .

In each of these cases, the catalytic precursor will encounter high temperature H2S and unconverted asphaltenes. Injections (10) and (11), thanks to the absence gas bubbles, however, allow better control of the mixture and therefore represent a preferred embodiment of the invention.
It is also possible to inject a quantity of catalytic precursor in a manner similar to the second reactor. The injection can take place at the second reactor, alone or in combination with an injection at the first reactor. Therefore, the possible injection points are the same as before.

However, since the dispersed catalyst circulates in the process following the liquid, all of the dispersed catalyst injected into the first reactor will pass to the second reactor. It is therefore not generally necessary, even if it is possible to inject dispersed catalyst into the downstream reactors

It is also possible to envisage a succession of several successive reactors greater than 2.

Claims (8)

1. Process for hydroconversion in a reaction zone of heavy hydrocarbon feedstocks containing sulphur, in the presence of hydrogen and a catalytic solid phase, said solid phase being obtained from a catalytic precursor, said process being operated at a total pressure that can range from 10 to 500 bar, with a partial hydrogen pressure varying from 10 to 500 bar, at a temperature of 350 to 500°C, a residence time of the liquid hydrocarbons in the reaction zone between 5 mn and 20 h, a process in which the conversion products from the reaction zone are separated in an internal or external liquid/gas separator, and the catalytic precursor is directly injected into the part of the liquid conversion products which contain dissolved hydrogen sulphide and asphaltenes and/or resins which is recycled to the reaction zone, said injection being performed into the part of recycled liquid conversion products before the separation of said conversion products in the liquid/gas separator when an external liquid/gas separator is used, or after the separation of said conversion products in the liquid/gas separator when an internal liquid/gas separator is used, the temperature Tmel, resulting from the contact of the catalytic precursor with said liquid products, is comprised in the range Ts +/- 10°C (Ts is the temperature at which said liquid products leave the reaction zone), and the total pressure Pmel is comprised in the range Ps +/- 10°C (Ps is the pressure at which said liquid products leave the reaction zone), said temperature Tmel being comprised in the range 380°C and 500°C, and the obtained mixture reacts in the reaction zone.
2. Process according to claim 1 in which the catalytic precursor is an organometallic compound, a salt or a molybdenum-based acid.
3. Process according to one of the preceding claims in which a supported catalyst is arranged in the reaction zone and used in the form of a bubbling bed.
4. Process according to one of the preceding claims in which the process being used in the reaction zone is in the form of a slurry bed.
5. Process according to one of the preceding claims in which the heavy feedstock has a boiling point above 340°C for at least 90% by weight of the feedstock.
6. Process according to one of the preceding claims in which the heavy feedstock has a boiling point above 540°C for at least 80% by weight of the feedstock.
7. Process according to one of the preceding claims in which the heavy feedstock has a viscosity below 40,000 cSt at 100°C.
8. Process according to one of the preceding claims in which a heavy aromatic cut is injected into the process.

Images