Process for processing hydrocarbon feedstocks with continuous catalyst regeneration - Patents.com

Abstract

The present invention relates to a process for catalytic reforming of a hydrocarbon feedstock with continuous catalyst regeneration, comprising: a) continuously flowing said feedstock through a plurality of reaction zones (R1, R2, R3, R4) in series; b) continuously flowing a catalyst as a moving bed through the plurality of reaction zones, said catalyst flowing from the upstream end to the downstream end of each of said reaction zones and being transported from the downstream end of one reaction zone to the upstream end of the next reaction zone by a carrier gas phase g1, said carrier gas phase g1 having a density of 1 kg / m, measured under operating conditions of a temperature T of 200-550° C. and an absolute pressure P of 0.1-0.7 MPa. 3 The present invention relates to a method for producing a medicament for use in a pharmaceutical composition comprising the steps of:

Description

[Technical field]

[0001] The present invention relates to a process for the catalytic treatment of hydrocarbon feedstocks with continuous catalytic regeneration, also known by the abbreviation CCR (continuous catalytic regeneration). These processes include, among others, the catalytic reforming of hydrocarbon feedstocks, especially those of naphtha type, in order to convert them into aromatics and / or gasoline, and the dehydrogenation of paraffins in order to convert them into olefins. [Background technology]

[0002] In general, the purpose of a catalytic reforming unit is to convert naphthenic and paraffinic (n-paraffins and isoparaffins) compounds to aromatics. The main reactions involved are the dehydrogenation of naphthenes and the dehydrocyclization of paraffins to give aromatics, and the isomerization of paraffins and naphthenes. Other "side" reactions may occur, such as hydrocracking and hydrocracking of paraffins and naphthenes, hydrodealkylation of alkylaromatics to produce light compounds and lighter aromatics, and also the formation of coke at the surface of the catalyst.

[0003] Consider first the case of a catalytic reforming process with continuous catalyst regeneration: the feedstocks typically sent to a catalytic reforming unit are paraffinic and naphthenic. The feedstocks are rich in aromatic compounds and relatively poor in aromatic compounds. They are generally naphthas resulting from the distillation of crude oil or natural gas condensates. Other feedstocks may be available, containing variable contents of aromatic compounds, i.e. heavy catalytic cracking naphtha, heavy coker naphtha or heavy hydrocracking naphtha, or also steam cracking gasoline. The present invention will focus more particularly on the conversion of naphtha type feedstocks.

[0004] Furthermore, it may be necessary to pretreat the feedstocks, especially those of naphtha type, before processing them by catalytic reforming: this pretreatment is generally hydrotreating. The term "hydrotreating" refers to all the refining methods that make it possible to remove, through the action of hydrogen, the various impurities contained in the hydrocarbon feedstock. Hydrotreating processes therefore make it possible, through the action of hydrogen, to remove impurities present in the feedstock, such as nitrogen (referred to as hydrodenitrification), sulfur (referred to as hydrodesulfurization), oxygen (referred to as hydrodeoxygenation) and metal-containing compounds (referred to as hydrodemetalization) that can poison catalysts and cause operational problems during downstream processes, such as reforming. An example of a hydrotreating process is described in US Pat. No. 5,399,323.

[0005] Examples of catalytic reforming processes of the regenerative type and with optimized catalyst distribution are described in US Pat. Nos. 5,993,333 and 5,993,525, in which the reforming unit uses a series of reactors mounted in series, each equipped with a moving catalyst bed, and the effluent from each reactor, except the last (the furthest downstream), is heated before introduction into the next reactor to balance the endothermic nature of the reforming reactions and maintain a sufficient temperature in each of the reactors for the desired conversion reactions to occur.

[0006] Let us now consider the case of a catalytic dehydrogenation process with continuous catalyst regeneration: in the case of the dehydrogenation of paraffins, for example the dehydrogenation of propane to give propylene, the paraffinic feedstock, after being pretreated (adsorption, drying, removal of C4+ fractions, etc.), enters the actual dehydrogenation unit, which includes a reaction section and a continuous catalyst regeneration (CCR) section. The dehydrogenation reaction takes place in a reactor, where the feedstock comes into contact with the catalyst, which circulates in a moving bed. This reaction is highly endothermic, and the effluent leaving the first reactor must therefore be heated in an oven to obtain the desired temperature when entering the second reactor. This sequence is then repeated in the following reactors. A propane dehydrogenation unit generally consists of four reactors in series, whereas for butane, three reactors may be sufficient. Upon leaving the reaction section, the effluent undergoes selective hydrogenation of diolefins to monoolefins and is treated to remove light compounds (C2-); finally, a propane-propylene splitter separates the resulting propylene from the residual propane, which is recycled. Examples of paraffin dehydrogenation processes using continuous catalytic circulation (CCR) are given in US Pat. No. 5,399,693 for a configuration of overlapping reaction zones and in US Pat. No. 5,499,693 for a configuration of reactors in series.

[0007] The invention focuses more particularly on the transport in a moving bed of catalyst in a reforming or dehydrogenation unit: the catalyst flows continuously through the reactors in series, flowing by gravity from the top to the bottom in each of them, for example in vertically oriented reactors arranged side by side, as described in the above mentioned patents. To flow from one reactor to the next, the catalyst is continuously withdrawn from the bottom part of one reactor and transported to the top part of the next reactor through one or more pipes external to the reactors. Once withdrawn from the bottom part of the last reactor, the spent catalyst is sent to a regeneration reactor and, once regenerated, it is again sent to the top part of the first reactor in the series to start the production-regeneration cycle again.

[0008] In patent 6 the means used for distributing the catalyst from one reactor to the next and then from the last reactor in the series to the regeneration reactor are described in more detail. In said patent the problem is to introduce the catalyst into the top part of the first reactor of the series, therefore the most upstream, through a number of pipes, in which it is conveyed in the form of a moving bed. It is then withdrawn through a number of pipes, which converge into a common pipe, through which it reaches a vessel known as the "lift pot". This withdrawal is carried out continuously, the regularity of the catalyst flow rate being ensured by an appropriate regulation by a carrier gas, which may be hydrogen, generated by the reforming unit itself, or high-purity hydrogen or recycled hydrogen, which is injected into this "lift pot" through a pipe. The catalyst is then entrained by the carrier gas from the "lift pot" to the next reactor, via a lift device called "lift"; it then reaches a container, from which, via pipes, it reaches the top part of the second reactor, where the same path resumes in the third reactor, and so on. It is finally withdrawn from the bottom part of the last reactor in the series, via pipes, called "spent" catalyst, which transport it to an "accumulator-decanter" vessel, via another lift means of the "lift" type. It is then transported to the regeneration reactor via another carrier gas, generally nitrogen. The catalyst must be purged beforehand from any traces of hydrogen, since the regeneration of the catalyst is carried out under oxidizing conditions: a transition device must therefore be provided between the circuits under hydrogen and under nitrogen.

[0009] These means implemented by pneumatic transport to distribute the catalyst from one reactor to another are efficient, but in certain operating configurations they may have certain drawbacks, in particular they include a certain number of pipes, which have a specific geometric shape and in particular elbows, which may lead to the risk of deposits in the pipes or else to the risk of erosion of the pipe walls, and even to unwanted wear on the catalyst particles.

[0010] An object of the present invention is therefore to improve the design of the means for transporting catalyst from one reactor to the next in a unit for the reforming of hydrocarbon feedstocks (for example the treatment of naphtha type feedstocks) or for the dehydrogenation of hydrocarbon feedstocks (for example the treatment of paraffin type feedstocks). [Prior art documents] [Patent documents]

[0011] [Patent Document 1] French Patent Application Publication No. 2966835 [Patent Document 2] French Patent Application Publication No. 2657087 [Patent Document 3] French Patent Application Publication No. 3024460 [Patent Document 4] U.S. Pat. No. 3,978,150 [Patent Document 5] U.S. Pat. No. 5,336,829 [Patent Document 6] French Patent Application Publication No. 2657087 Summary of the Invention [Means for solving the problem]

[0012] (Summary of the invention) One subject of the invention is firstly a method for the catalytic treatment of a hydrocarbon feedstock with continuous catalyst regeneration, in which the feedstock is continuously circulated through a plurality of reaction zones in series, the catalyst being circulated continuously through the plurality of reaction zones as a moving bed, flowing from the upstream end to the downstream end of each of the reaction zones, being transported from the downstream end of one reaction zone to the upstream end of the next reaction zone by a carrier gas phase, the density of which, according to the invention, is less than 1 kg / m 3 Above, especially 1.2 kg / m 3 or more than 1.4kg / m 3 or more than 1.6kg / m 3 or more than 1.8kg / m 3 or more than 2kg / m 3 or more than 3kg / m 3 More than 5kg / m 3 Less than or equal to 4kg / m 3 The following is the result.

[0013] This density is measured under the operating conditions (temperature and pressure) of the method under consideration, in particular at a temperature T between 200 and 550° C., and an absolute pressure P between 0.1 and 0.7 MPa.

[0014] It is measured inter alia at a temperature of 300° C. and a pressure of 0.55 MPa.

[0015] In the case of catalytic reforming, this density is measured in particular at a temperature T1 between 200° C. and 450° C., in particular at 300° C., and at an absolute pressure P1 between 0.4 MPa and 0.7 MPa, in particular 0.5 MPa, which are the temperatures and pressures usually encountered in lift pipes in reforming.

[0016] In the case of dehydrogenation, this density is measured in particular at a temperature T2 of 300 to 550° C., in particular 400° C., and at an absolute pressure P2 of 0.1 to 0.4 MPa, in particular 0.25 MPa, which are the temperatures and pressures usually encountered in lift pipes in dehydrogenation.

[0017] Advantageously, the catalytic process according to the invention is a catalytic reforming, in particular the treatment of a naphtha-type feedstock with the purpose of producing aromatic hydrocarbons and / or gasoline, or a catalytic dehydrogenation, in particular the treatment of a paraffin-type feedstock with the purpose of producing olefins.

[0018] Advantageously, to achieve these densities, the carrier gas phase (g1) is heated at a temperature T between 200 and 550 ° C and at an absolute pressure P between 0.1 and 0.7 MPa, in particular in the case of reforming, at a temperature T1 between 200 ° C and 450 ° C, in particular 300 ° C, and at an absolute pressure P1 between 0.4 MPa and 0.7 MPa, in particular 0.5 MPa, in the case of dehydrogenation, at a temperature T2 between 300 and 550 ° C, in particular 400 ° C, and at an absolute pressure P2 between 0.1 and 0.4 MPa, in particular 0.25 MPa; It has a density that is at least 30% higher than the density of hydrogen to be measured, in particular at least 50%, preferably at least two or three times higher.

[0019] Throughout this specification, the terms "upstream" and "downstream" are understood with reference to the general direction of flow of the feedstock through the reactor of a reforming or dehydrogenation facility.

[0020] Throughout this specification, the term "gas phase" refers to a gas or a mixture of different gases, which may contain impurities.

[0021] A "reaction zone" is to be understood as a reactor, or reactors, or a separate portion of a reactor, equipped with all ad hoc equipment known to those skilled in the art (e.g., inlet and outlet openings connected to pipes, valves, heat control means, etc.).

[0022] The naphtha type (in the case of reforming) or paraffin type (in the case of dehydrogenation) feedstock according to the invention may undergo one or more treatments, in particular hydrotreatment, before reforming or dehydrogenation.

[0023] The invention therefore focuses not on the perplexity in the choice of mechanical means used to transport the catalyst, such as pipes, valves, containers, etc., or on their arrangement, but rather on a particular choice of carrier gas characteristics, i.e. the choice of increasing density. Surprisingly, it has been found that choosing a carrier gas with a higher density than the usual one (i.e. hydrogen or "enriched" hydrogen, i.e. hydrogen containing up to 10% by volume of other gases of light hydrocarbon type under the operating conditions of pressure P and temperature T usually used) has a very favorable effect on the circulation of the catalyst particles in the various pipes that convey them from one reactor to another: in particular, the risk of deposition of particles on the walls of the pipes, and more particularly in horizontal or oblique (not vertical) pipe sections or in "elbow" connecting pipe sections (non-straight sections thereof), is greatly reduced or even completely eliminated. This also applies to the risk of erosion of the walls, which makes it possible to reduce the inspection / maintenance operations (replacement, cleaning) of these pipes. A reduction or even elimination of the risk of particle attrition was observed, which may uncontrollably alter their particle size characteristics, which should be avoided / limited if it is desired to control their catalytic efficiency.

[0024] Preferably, the density of the carrier gas phase is at least 30% higher, in particular at least 50% higher, preferably at least 2 or 3 times higher than the density of hydrogen measured at a temperature T between 200 and 550° C. and an absolute pressure P between 0.1 and 0.7 MPa. The invention therefore preferentially targets densities significantly higher than the usual densities (relative to hydrogen and also relative to “enriched” hydrogen) in order to maximize the effects obtained.

[0025] To obtain a dense carrier gas, several embodiments exist according to the present invention, which may be selected or stacked together.

[0026] According to a first embodiment, the invention chooses to modify the chemical composition of the carrier gas phase: advantageously, said carrier gas phase comprises at least one gas having a molar mass higher than that of hydrogen, in particular nitrogen and / or at least one C1-C6 light hydrocarbon.

[0027] Nitrogen has the advantage of being much denser than enriched hydrogen, by more than six times, and it also has the advantage of being the gas commonly used to serve as a carrier gas for the spent catalyst from the last reactor to the regenerator and from the regenerator to the first reactor.

[0028] The light hydrocarbons have the advantage that they may already be available in the reforming unit by being formed during the reforming reaction steps: they are in the form of a mixture of C1-C6 hydrocarbons, generally with a majority of C1-C3 hydrocarbons.

[0029] The carrier gas phase may comprise a mixture of these various types of gases and may combine hydrogen with at least one of these various gases, its density being understood as the average density of the mixture of gases under consideration.

[0030] The carrier gas phase may therefore comprise at least 25% by volume, in particular at least 45% by volume or at least 50% by volume or at least 80% by volume, and at most 100% by volume, of a gas having a molar mass greater than the molar mass of hydrogen.

[0031] In the 100% case, said carrier gas phase g1 comprises only one or more gases (not taking into account impurities) having a molar mass greater than the molar mass of hydrogen.

[0032] The gas or gases having a molar mass greater than that of hydrogen may originate from the reforming process (or dehydrogenation process) itself, such as recycled reactants or products or by-products of reforming. This is the case for C1-C6 hydrocarbons or hydrogen (or rather "enriched" hydrogen, which, as mentioned above, generally contains up to 10% of another gas).

[0033] According to a second embodiment, the density of the carrier gas phase is increased while its temperature is reduced relative to a conventional temperature T (200-550 ° C): the temperature of said carrier gas phase g1 is adjusted to a temperature T3 below 200 ° C, in particular between 50 ° C and 150 ° C, so as to increase its density. The temperature of the carrier gas phase may be reduced by any type of known means, for example a heat exchanger or a cooler. It may then be necessary to heat the particles before they enter the next reactor.

[0034] According to a third embodiment, the density of the carrier gas phase is increased while its pressure is increased relative to the conventional pressure P (0.1-0.7 MPa): the pressure of said carrier gas phase g1 is adjusted to a pressure P3 of at least 1 MPa, in particular 1.5 MPa-4 MPa, to increase its density. The gas pressure is modified / increased by any known means, in particular by changing the dimensions of an already existing compressor, generally to put the gas under pressure, to make it flow and to compress the gas to transport the particles in the desired way.

[0035] The invention may be applied to a wide variety of reaction zone designs: the reaction zones may be located side-by-side in a reactor, respectively. The reaction zones may be superimposed on one another, with the most upstream zone located at the top and the most downstream zone at the bottom. This therefore gives a "stack" of reaction zones from top to bottom: this is the configuration described, for example, in patent US 3 647 680.

[0036] In either configuration, the catalyst flows continuously in each reactor / reaction zone from its upstream top end to its downstream bottom end, then is transported by said carrier gas phase through the fluid connections from the downstream bottom end of one reactor / reaction zone to the upstream top end of the next reactor / reaction zone in the series, and finally it is transported from the most downstream reaction zone to the regenerator and finally from the regenerator to the most upstream reaction zone.

[0037] The fluid connections allowing the transport of the catalyst particles in the gas phase include, inter alia, one or more pipes connecting at least one outlet of one reactor / reaction zone to at least one inlet of the next reactor / reaction zone and possibly to a vessel or pot. Possible configurations are described in the abovementioned patent FR 2 657 087.

[0038] Advantageously, the catalyst is transported via the regeneration gas phase g2 from the downstream end of the last reaction section of the series of reaction sections to the regeneration zone and from the regeneration zone to the upstream end of the first reaction zone of the series of reaction sections.

[0039] Preferably, the regeneration gas phase g2 is inert, in particular based on nitrogen, although it may be necessary to first purge the catalyst from any non-inert gas before it is transported to the regeneration zone.

[0040] According to one variant of the invention, the regeneration gas phase g2 and the carrier gas phase g1 have the same composition and / or are under the same temperature and / or pressure conditions. Said gas phase may be, for example, nitrogen.

[0041] The subject of the invention is also any installation for the catalytic treatment, in particular catalytic reforming or dehydrogenation, of a hydrocarbon feedstock with continuous catalyst regeneration, using the method described above.

[0042] The subject of the invention is also an installation for the catalytic treatment of a hydrocarbon feedstock with continuous catalyst regeneration, in particular for the catalytic reforming of a naphtha-type hydrocarbon feedstock with the aim of obtaining aromatic hydrocarbons and gasoline, or for the dehydrogenation of paraffins with the aim of obtaining olefins. This installation comprises, according to the invention, a number of reaction zones connected in series through which the feedstock flows continuously, and fluid connections which ensure the transport of the catalyst from the downstream end of one reaction zone to the upstream end of the next reaction zone via a carrier gas phase g1. The installation comprises a device for regulating the temperature and / or pressure and / or composition of the carrier gas phase g1, and for controlling its density within the range of 1 kg / m 3 Above 1.2kg / m 3 or more than 1.4kg / m 3 or more than 1.6kg / m 3 or more than 1.8kg / m 3 More than or especially 2kg / m 3 or more than 3kg / m 3 More than 5kg / m 3 Less than or equal to 4kg / m 3 Adjust to the following density (under equipment operating conditions):

[0043] The device for regulating the pressure of the carrier gas phase g1 may advantageously comprise one or more compressors.

[0044] The device for regulating the temperature of the carrier gas phase g1 may advantageously comprise one or more heat exchangers and / or one or more cooling groups.

[0045] The device for adjusting the composition of the carrier gas phase g1 may advantageously comprise a gas mixer, which is fed with a source of hydrogen and a source of nitrogen and / or a source of C1-C6 hydrocarbons, said sources of hydrogen and C1-C6 hydrocarbons being preferably obtained from a catalytic process (especially reforming) carried out in the installation. Pipes for the introduction of enriched hydrogen and pipes for the introduction of light hydrocarbons produced by the installation may thus be provided, which converge into a single pipe, with the desired ratio between the two types of gas, and which configure the desired carrier gas phase to be conveyed into the "lift" pipe transporting the catalyst particles, using any means known for doing so (valves, ratio of pipes, compressors, etc.).

[0046] As mentioned above, the various embodiments of the invention may be combined in pairs or all together, for example, by modifying both the chemical composition of the gas phase and its temperature (or its pressure), or both its pressure and its temperature.

[0047] The present invention will be detailed below with non-limiting implementation examples for a reforming process with continuous catalyst regeneration (CCR), which can be transposed in a very similar manner to a dehydrogenation process with continuous catalyst regeneration. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0048] (List of Drawings) 1 shows part of a catalytic reforming installation to which the present invention may be applied, in particular the reaction section and the regeneration section of the process. It is very schematic and the various elements shown are not necessarily to scale: it is a flow diagram.

[0049] FIG. 2 shows diagrammatically the flow regime of the various catalyst streams as a function of the carrier gas velocity in the vertical straight pipe section used in the installation of FIG.

[0050] FIG. 3 shows diagrammatically the flow regime of various catalyst flows as a function of the carrier gas velocity in a horizontal straight pipe section.

[0051] FIG. 4 is a graph showing the choking rate for a vertical pipe and the saltation rate for a horizontal pipe as a function of carrier gas density.

[0052] FIG. 5 is a graph showing the difference between carrier gas velocity and choking velocity as a function of density for a vertical pipe section.

[0053] FIG. 6 is a graph showing the difference between the carrier gas velocity and the saltation velocity as a function of its density for an oblique pipe section.

[0054] Figure 7 is an image of a simulation of the "lift" pipe that transports catalyst from one reactor to the next.

[0055] (Description of the embodiment) In the following examples, "naphtha" refers to a petroleum fraction of any chemical composition, preferably having a distillation range of 50°C to 250°C. The distribution of chemical families identified by PONA (P(paraffins), O(olefins), N(naphthenes) and A(aromatics)) may be any distribution.

[0056] The term "petroleum" refers to petroleum fractions having a distillation range similar to that of naphtha and having an octane number greater than 95, preferentially greater than 98.

[0057] The term "aromatic base" refers broadly to xylenes (para-xylene, meta-xylene, ortho-xylene), ethylbenzene, toluene and benzene, and optionally heavier aromatic compounds such as styrene monomer, cumene or linear alkylbenzenes.

[0058] The term "reformate" refers to a petroleum fraction having a high octane number produced by catalytic reforming.

[0059] In the remainder of the description of the figures, the term "reactor" should be understood as reaction zone.

[0060] The feedstocks to be treated in the context of the below described examples of the process of the invention are naphtha type hydrocarbon feedstocks which it is desired to treat by catalytic reforming. This feedstock is a hydrocarbon fraction rich in paraffinic and naphthenic compounds but relatively poor in aromatic compounds. Naphtha feedstocks originate, for example, from atmospheric distillation of crude oil or natural gas condensates. The process according to the invention also applies to catalytic cracking (FCC), coking or hydrocracking of heavy naphthas or alternatively to steam cracking of gasoline. These feedstocks are more or less rich in aromatic compounds and may be used to feed catalytic reforming units for the production of gasoline-based or aromatic-based products.

[0061] Generally, this naphtha is pretreated in a hydrotreating unit to remove or sufficiently reduce the content of impurities that may poison the reforming catalyst, including at least one of the following impurities: sulfur, nitrogen, water, halogens, olefins and diolefins (if applicable), mercury, arsenic and other metals. This hydrotreating step is known per se and will not be described here.

[0062] The reforming or dehydrogenation installations use conventional catalysts. As reforming or dehydrogenation catalysts, mention may be made of catalysts comprising a support of silica and / or alumina type and a metal from the platinum group, tin, phosphorus, optionally a halogen, for example chlorine, and optionally a third metal, such as those described in patent FR 2 947 465, and optionally an alkali metal or alkaline earth metal, for example potassium.

[0063] The catalyst is in the form of shaped bodies, for example in the form of substantially spherical beads, the diameter of which is generally from 1 to 3 mm, in particular from 1.5 to 2 mm, and the bulk density of which is generally from 0.4 to 1, preferably from 0.5 to 0.9 or from 0.55 to 0.8.

[0064] FIG. 1 shows a portion of a catalytic reforming plant that functions with continuous regeneration (CCR) and can be applied to the present invention: (the dehydrogenation plant is of the same / similar design).

[0065] Said naphtha feedstock (1) is fed to a catalytic reforming plant, which comprises four reactors R1, R2, R3, R4, which are equipped with moving beds of catalytic reforming catalyst. The reforming plant functions under operating conditions and in the presence of a catalyst that allows the optimization of the conversion of naphthenic (cycloalkanes) and / or paraffinic compounds to aromatic hydrocarbons. To limit the formation of coke on the reforming catalyst, the reforming step is carried out in the presence of hydrogen.

[0066] The installation also includes a spent catalyst regenerator RG, and ovens F1, F2, F3, F4: the feedstock (1) is heated in oven F1 and then sent to an inlet at the top of the first reactor R1, it flows from top to bottom in reactor R1, then the effluent from reactor R1 is withdrawn at the bottom, heated in oven F2 and then sent to an inlet at the top of the next reactor R2, the same is done in oven F3 and reactor R3, then oven F4 and the last R4. The effluent from the last reactor R4 then continues to other processes.

[0067] In a very schematic view, FIG. 1 shows the path of the catalyst from one reactor to another, accompanied by a carrier gas g1 and a regenerating carrier gas g2: as described in the above-mentioned patent FR 2 657 087, pipes and "lift pots" are used to ensure the required fluid connections, and the carrier gas g1 conveys the catalyst by pneumatic transport from the bottom part of the reactor to the top part of the next reactor, from the most upstream reactor R1 to the most downstream reactor R4 through a system of pipes and "lift pots": these are paths a, b, c in FIG. 1. At the outlet of the reactor R4, the spent catalyst is conveyed via gas g2 along path d to the regenerator RG, also through a fluid connection that includes a pipe. Finally, the regenerated catalyst is conveyed via gas g2 along path e from the outlet of the regenerator RG to the inlet at the top part of the reactor R1, resuming the production cycle through the installation.

[0068] The catalytic reforming unit generally operates within the following operating ranges: - the average reactor inlet temperature is 420℃-600℃; - the pressure is 0.3-1MPa; - the H2 / feedstock molar ratio is 0.2-8 mol / mol; - Mass hourly space velocity is expressed as the ratio of the mass flow rate of the feedstock to the mass of the catalyst, and is expressed as 0.5-8 h -1 It is.

[0069] In this case of reforming, the lift pipes transporting the catalyst from one reactor to the next are at temperatures of the order of 200-450°C and their pressures are within absolute pressure values ​​of 0.4MPa-0.7MPa.

[0070] It should be noted that catalytic dehydrogenation units generally function within the following operating ranges: - the average reactor inlet temperature is 500℃-700℃; - The pressure is 0.1-0.4MPa; the H2 / feedstock molar ratio is in the range of 0.2-8 mol / mol, in particular in the range of 1-4 mol / mol or in the range of 0.5 mol / mol; - Liquid hourly space velocity is expressed as the ratio of the volumetric flow rate of the feedstock to the volume of the catalyst, and is typically expressed as 2-6 h -1 It is.

[0071] In the case of dehydrogenation, the lift pipes transporting the catalyst from one reactor to the next are at temperatures of the order of 300-550°C and their pressures are within absolute pressure values ​​of 0.1 MPa to 0.4 MPa.

[0072] The carrier gas (also known as vector gas) g1 is conventionally enriched hydrogen and the regenerative carrier (vector) gas g2 is nitrogen.

[0073] In the case of a reforming (or dehydrogenation) unit, the gas g1 is conventionally a gas consisting mainly of hydrogen (at least about 90% by volume) and may contain small amounts of impurities. It is characterized by a relatively low density under the operating conditions (absolute pressure 0.4-0.7 MPa, temperature 200-450 °C): its density is generally less than 1 kg / m 3 Less than 0.4-0.8 kg / m 3 It is.

[0074] Pneumatic transport of solid catalyst particles (beads or other objects) is governed by characteristic velocities to distinguish between different flow regimes and to identify any turbulence. For a vertical pipe section, the choking velocity Uch corresponds to the minimum velocity of the carrier gas that allows transporting the particles into the dilute phase in the pipe.

[0075] Figure 2 shows the schematic flow of catalyst particles used in the installation of Figure 1, with the velocity of carrier gas g1 in a vertical straight pipe section. It is taken from the publication Yang W.-C. (2003) Handbook of Fluidization and Fluid-Particle Systems, CRC Press. The arrows indicate the increasing carrier gas velocity from one case to the next: In case 2a, the gas velocity is insufficient and the particles remain in the bottom part of the pipe section in the fixed bed; - In case 2b, the gas velocity is higher than in case 2a and there is a "particle" flow regime. In case 2c, the gas velocity is higher than that in case 2b and there is a boiling flow regime. In case 2d, the gas velocity is higher than in case 2c and there is a pulsatile flow regime. - In case 2e, there is a chaotic flow regime; - In case 2f, there is a rapid fluidization flow regime. In case 2g there is pneumatic transport, which is the desired mode of transport of particles in the present invention for the vertical pipe section.

[0076] For a horizontal or oblique straight section, the saltation velocity Usalt corresponds to the minimum velocity of the carrier gas that makes it possible to maintain a uniform transport and prevents deposition of particles at the bottom of the transport pipe.

[0077] Figure 3 shows the schematic flow of catalyst particles used in the installation of Figure 1, with the velocity of the carrier gas in a horizontal or oblique straight pipe section. The figure is taken from the publication Ph. Eeynier et al., Review of Modelling of Slush Hydrogen Flows, Journal of Computational Multiphase Flows 3(3): 123-146. As the gas velocity increases from the case of Figure 3a to the case of Figure 3d (arrow f indicates the direction of particle flow in the pipe section), the small graph on the right side of the pipe section indicates the particle concentration in the pipe section: - In case 3a, there is a fixed / stopped floor, - In case 3b, there is a saltation flow regime. - In case 3c, there is a non-uniform flow, - In case 3d there is uniform flow, which is the flow regime targeted by the present invention for catalyst particles in horizontal or oblique pipe sections.

[0078] As shown in Figures 2 and 3, for insufficient carrier gas velocity (i.e. below the limit velocity for choking and / or saltation), the flow may become non-uniform and particle concentration and velocity gradients may occur in the transport pipe. This type of functioning should be avoided, especially in the particular case of CCR type reforming units, since it may lead to deterioration (by erosion) of the constituent materials of the "lift" line (the term "line" is to be understood as a pipe or an assembly of pipes), or of the catalyst particles (by friction), but may also lead to clogging, which may result in substantial pressure losses.

[0079] These limiting velocities may be estimated by various correlations based on experimental observations: they depend on the operating conditions and the properties of the gas and solids under consideration (limiting fall velocity, flow rate, size, etc.), and they have also been shown to depend, among other things, on the density of the carrier gas used to transport the particles.

[0080] Therefore, FIG. 4 is a graph showing the choking and saltation rates as a function of the carrier gas density for a characteristic example of an industrial CCR reforming unit: the y-axis shows the velocity (m / s) and the x-axis shows the carrier gas density (kg / m 3 ) is shown. The curve with diamond points corresponds to the saltation velocity (horizontal pipe) and the curve with square points corresponds to the choking velocity (vertical pipe). Figure 4 shows that the gas velocity required to ensure dilution and uniform flow in the lift line / pipe is proportionally slower the higher the gas density. However, Figure 4 shows that this dependence on density is not linear and that it is proportionally larger in the low density zone, which is characteristic of lift lines using hydrogen-enriched type carrier gas g1.

[0081] In CCR reforming, it is necessary to control the velocity of the catalyst particles in the lift line to avoid causing deterioration of the pipes and catalyst, and to limit the pressure loss in the pipes: the target catalyst velocity (Ucata) is taken into account, which may be calculated by various correlations, from which the velocity of vector gas g1 (Ugas) required to achieve this target velocity may be determined. The following relationship may be used to a first approximation: Ugas = Ucata + Ut Ut is the critical falling velocity of the catalyst particles.

[0082] FIG. 5 shows the relationship between the gas velocity Ugas calculated to achieve a desired catalyst rate Ucata and the density of the carrier gas (kg / m 3) and the choking velocity Uch (m / s) in the vertical pipe as a function of the choking velocity Ugas (m / s): the figure shows that for the lowest densities, the gas velocity Ugas is of the order of magnitude of the choking velocity Uch, or even lower, which can cause disruptions in the flow (non-dilute flow regimes). If the density of the vector gas increases, the gas velocity required to achieve the desired catalyst particle velocity becomes higher than the choking velocity, which makes it possible to ensure dilute flow regimes in the vertical lift pipe.

[0083] Figure 6 is a graph showing the difference between the gas velocity Ugas calculated to achieve a desired particle velocity Ucata and the carrier salutation velocity Usalt (m / s) as a function of the carrier gas density for horizontal or oblique pipe sections: As in the previous figure, Figure 6 shows that for a given catalyst velocity Ucata, the gas velocity Ugas can be lower than the salutation velocity Usalt if the gas density is too low, thus causing particle deposition in the horizontal or oblique sections of the line and disruption to the flow.

[0084] Taking advantage of these results, the present invention contemplates modifying the density of the vector gas g1 to improve the transport of catalyst particles in the lift line, more specifically in its vertical and oblique portions, as well as in the horizontal portions, if any, and thus avoiding any choking or saltation that may cause disruptions in the flow.

[0085] The density of the carrier gas depends on the following multiple parameters: density and size of the catalyst, catalyst flow rate, target velocity Ucata, diameter and length of the line, vector gas velocity; the invention can be adapted according to the above parameters, but in any case it is generally conventionally 1 kg / m 3 remains much lower.

[0086] The density of gas g1 is chosen according to the invention to be greater than that of enriched hydrogen under the same operating conditions.

[0087] This increased density may be obtained in various ways, which will form the subject of the following examples.

[0088] All the following examples refer to catalytic reforming processes. The invention is applied very similarly to catalytic dehydrogenation processes, and the same technical effects and the same improvements are observed by applying the invention: however, the given operating conditions, especially the pressure and temperature, may be different, as already described above.

[0089] (Example) Examples 1 to 5 correspond to the first embodiment of the present invention and consist of modifying the chemical composition of the carrier gas to increase its density, either by removing the enriched hydrogen and replacing it with another denser chemical species, or by adding one or more denser gases to the enriched hydrogen to increase the average density of the gas phase, or by removing the enriched hydrogen and replacing it with some denser gas.

[0090] Example 1 The increase in density of the vector gas is obtained by modifying the composition of gas g1, which here is, according to the invention, a gas composed 100% of nitrogen (but which may contain small amounts of impurities). For an average lift line temperature of 300° C. and an average absolute pressure of 0.55 MPa, the nitrogen density is 3.23 kg / m 3 is equal to.

[0091] Example 2 The increase in the density of the vector gas is obtained by modifying the composition of gas g1, which here is in accordance with the invention and is a gas composed 100% of C1-C6 light hydrocarbons (but may contain small amounts of impurities): an example composition is given in Table 1 below.

[0092] [Table 1]

[0093] The molar mass of this gas mixture is equal to 34.3 g / mol. For an average lift line temperature of 300° C. and an average absolute pressure of 0.55 MPa, the density of this gas mixture is 3.96 kg / m 3 is equal to.

[0094] Example 3 The increase in the density of the vector gas is obtained by modifying the composition of gas g1, which is in accordance with the present invention a gas partially composed of nitrogen and partially composed of C1-C6 light hydrocarbons according to the composition given in Table 2 below.

[0095] [Table 2]

[0096] The molar mass of this gas mixture is equal to 35.8 g / mol. For an average lift line temperature of 300° C. and an average absolute pressure of 0.55 MPa, the density of this gas mixture is 4.14 kg / m 3 is equal to.

[0097] Example 4 The increase in density of the vector gas is obtained by modifying the composition of gas g1, which is in accordance with the invention and is a gas partially composed of hydrogen (less than 35% by volume) and partially composed of C1-C6 light hydrocarbons: an example composition is given in Table 3 below.

[0098] [Table 3]

[0099] The molar mass of this gas mixture is equal to 25.9 g / mol. For an average lift line temperature of 300° C. and an average absolute pressure of 0.55 MPa, the density of this gas mixture is 2.99 kg / m 3 is equal to.

[0100] Example 5 The increase in the density of the vector gas is obtained by modifying the composition of gas g1, which is in accordance with the invention and is a gas partially composed of hydrogen (less than 35% by volume) and partially composed of nitrogen: an example composition is given in Table 4 below.

[0101] [Table 4]

[0102] The molar mass of the gas mixture is equal to 23.6 g / mol. For an average lift line temperature of 300° C. and an average absolute pressure of 0.55 MPa, the density of this gas mixture is 2.72 kg / m 3 is equal to.

[0103] Example 6 The increase in density of the vector gas is obtained by modifying the composition of gas g1, which is in accordance with the invention and is a gas partially composed of hydrogen (less than 35% by volume), partially composed of nitrogen and partially composed of C1-C6 light hydrocarbons: an example composition is given in Table 5 below.

[0104] [Table 5]

[0105] The molar mass of the gas mixture is equal to 32.4 g / mol. For an average lift line temperature of 300° C. and an average absolute pressure of 0.55 MPa, the density of this gas mixture is 3.74 kg / m 3 is equal to.

[0106] Example 7 Example 7 corresponds to a second embodiment of the invention, which consists in modifying the pressure of the carrier gas: in this case, gas g1 remains hydrogen-enriched, its operating temperature is 300° C. and its absolute pressure is increased to a value P2 of 2.2 MPa, which is four times higher than the average pressure P1 commonly used. The density of the hydrogen-enriched gas is, under these conditions, 2.62 kg / m3 It is.

[0107] Example 8 Example 8 corresponds to the third embodiment of the present invention, which consists in modifying the temperature of the carrier gas g1: in this case, the gas g1 remains hydrogen-enriched, and its working temperature T2 is lower than 50° C., which is 6 times lower than the commonly used temperature T1 of 300° C. Its pressure remains at the conventional pressure P1 of 0.55 MPa.

[0108] The density of enriched hydrogen under these conditions is 1.16 kg / m 3 It is.

[0109] The present invention may combine these various embodiments, as illustrated in Examples 9 and 10, for example by modifying both the chemical composition of the carrier gas and its pressure or its temperature, or alternatively by maintaining the gas, e.g., hydrogen, but modifying both its pressure and its temperature.

[0110] Example 9 In this case, the gas g1 is enriched hydrogen. Its operating temperature is reduced to 100° C., which is three times lower than the commonly used temperature T1 of 300° C., and its absolute pressure is increased to a value P2 of 1.65 MPa, which is three times higher than the commonly used average pressure P1. The density of the gas g1 is, under these conditions, 3.02 kg / m 3 It is.

[0111] Example 10 The increase in density of carrier gas g1 is obtained by combining several modifications. First, the composition of gas g1 is modified, which in this case is a gas partially composed of hydrogen (less than 35% by volume), partially composed of nitrogen, and partially composed of C1-C6 light hydrocarbons. An example composition is given in Table 6 below.

[0112] [Table 6]

[0113] The molar mass of the gas mixture is equal to 16.1 g / mol. Its temperature is also modified, lowering it to a temperature of 200° C., which is 1.5 times lower than the commonly used temperature T1 of 300° C. Its absolute pressure is also modified, increasing it to a value P2 of 0.825 MPa, which is 1.5 times higher than the commonly used average pressure P1. The density of gas g1 is, under these conditions, 3.38 kg / m 3 It is.

[0114] Example 11 In this example, the catalyst transport in a lift line representative of an industrial CCR reforming unit was reproduced by CFD simulation using ANSYS Fluent® software. Figure 7 shows the first part of the simulated lift line: it consists, among other things, of an oblique section with an angle of 60° relative to the horizontal. The reference case is taken from the distribution of catalyst particles transported in the line shown in Figure 7 at the first elbow and in the zone at the beginning of the oblique section, using a carrier gas of enriched hydrogen type. The density of this carrier gas is 0.5 kg / m 3 and flows at a velocity of 10.4 m / s. Under these conditions, it is observed that after passing the first elbow, the catalyst flows in the diagonal line, mainly on the bottom of the tube, and that a particle velocity gradient is established between the lower part of the pipe, where the catalyst velocity is close to 0 m / s, and the upper part, which is characterized by a higher bead velocity.

[0115] The same simulation was run, but this time, in accordance with the present invention, the density of the vector gas was set to 3 kg / m 3and increasing the operating pressure as in the case of Example 7 above. The carrier gas velocity was reduced to 6.6 m / s, in order to keep the average bead velocity the same as in the reference case. It is then observed that under these conditions, after passing through the first elbow, the catalyst flows in a much more dilute manner in the diagonal line and that the catalyst velocity in this line section is more uniform than in the reference case. [Brief description of the drawings]

[0116] [Figure 1] 1 shows the parts of a catalytic reforming plant to which the present invention may be applied, in particular the reaction section and the regeneration section of the process. [Diagram 2] 2 shows diagrammatically the flow regime of various catalyst streams as a function of the carrier gas velocity in a vertical straight pipe section used in the installation of FIG. 1. [Diagram 3] 1 shows a schematic representation of various flow regimes of catalyst as a function of carrier gas velocity in a horizontal straight pipe section. [Figure 4] 1 is a graph showing choking velocity for a vertical pipe and saltation velocity for a horizontal pipe as a function of carrier gas density. [Diagram 5] 1 is a graph showing the difference between carrier gas velocity and choking velocity as a function of density for a vertical pipe section. [Figure 6] 1 is a graph showing the difference between the carrier gas velocity and the saltation velocity depending on its density for an oblique pipe section. [Figure 7] This is an image of a simulation of the "lift" pipe that transports catalyst from one reactor to the next.

Claims

1. A method for catalytic reforming or dehydrogenation of a hydrocarbon feedstock with continuous catalyst regeneration, comprising continuously flowing the feedstock through a plurality of reaction zones (R1, R2, R3, R4) in series, continuously flowing a catalyst through a moving bed in the plurality of reaction zones, the catalyst flowing from the upstream end to the downstream end of each reaction zone and being transported by a carrier gas phase g1 from the downstream end of one reaction zone to the upstream end of the next reaction zone, wherein the density of the carrier gas phase g1 is measured under operating conditions of a temperature T of 200 to 550 °C and an absolute pressure P of 0.1 to 0.7 MPa to be 1 kg / m ３ super, especially 1.2 kg / m ３ or more or 1.4 kg / m ３ or more or 1.6 kg / m ３ or more or 1.8 kg / m ３ or more or 2 kg / m ３ or more or 3 kg / m ３ or more, and preferably 5 kg / m ３ or less or 4 kg / m ３ or less, characterized by the method.

2. The contacting treatment is catalytic reforming for treating naphtha-type feedstock for the purpose of producing aromatic hydrocarbons and / or gasoline, or catalytic dehydrogenation for treating paraffin-type feedstock for the purpose of producing olefins, according to the method of Claim 1, characterized in that.

3. The density of the carrier gas phase g1 is at least 30%, especially at least 50%, preferably at least 2 or 3 times greater than the density of hydrogen measured at the same temperature T of 200 to 550 °C and the same absolute pressure P of 0.1 to 0.7 MPa, according to the method of Claim 1 or 2, characterized in that.

4. The carrier gas phase g1 contains at least one gas having a molar mass higher than the molar mass of hydrogen, especially nitrogen and / or at least one C1-C6 light hydrocarbon, according to the method of Claim 1, characterized in that.

5. The carrier gas phase g1 contains at least 25% by volume, especially at least 45% by volume or at least 50% by volume or at least 80% by volume of a gas having a molar mass greater than the molar mass of hydrogen, according to the method of Claim 4, characterized in that.

6. The carrier gas phase g1 contains only one or a plurality of gases having a molar mass greater than the molar mass of hydrogen, according to the method of Claim 5, characterized in that.

7. One or a plurality of gases having a molar mass greater than the molar mass of hydrogen originate from the reforming process itself as reactants or products or by-products of the reforming recycle, according to the method of Claim 4, characterized in that.

8. The temperature of the carrier gas phase g1 is adjusted to less than 200 °C, especially to a temperature T3 of 50 °C to 150 °C, to increase its density, according to the method of Claim 1, characterized in that.

9. The pressure of the carrier gas phase g1 is adjusted to at least 1 MPa, especially to a pressure P3 of 1.5 MPa to 4 MPa, to increase its density, according to the method of Claim 1, characterized in that.

10. The reaction zone is placed in reactors (R1, R2, R3, R4) arranged side by side or superposed on each other, and the catalyst continuously flows from its upstream top end to its downstream bottom end in each reactor and is transported from the downstream bottom end of one reactor of a series of reactors to the upstream top end of the next reactor through a fluid connection by the carrier gas phase, according to the method of Claim 1, characterized in that.

11. The fluid connection includes one or more pipes and connects at least one outlet of one reactor to at least one inlet of the next reactor and optionally to a vessel or pot, according to the method of claim 10.

12. The catalyst is transported via a regeneration gas phase g2 from the downstream end of the last reaction section (R4) of a series of reaction sections to the regeneration zone (RG) and from the regeneration zone to the upstream end of the first reaction zone (R1) of the series of reaction sections (R1, R2, R3, R4), the regeneration gas phase g2 being preferably inert, especially nitrogen-based, and optionally, after purging the catalyst from any non-inert gas, transporting it to the regeneration zone, according to the method of claim 1.

13. The regeneration gas phase g2 and the carrier gas phase g1 have the same composition and / or are under the same temperature and / or pressure conditions, according to the method of claim 12.

14. A facility for the catalytic treatment of a hydrocarbon feedstock with continuous catalyst regeneration, wherein the catalytic treatment is the catalytic reforming of a naphtha-type hydrocarbon feedstock for the purpose of producing aromatic hydrocarbons and / or gasoline, or the dehydrogenation of paraffins for the purpose of producing olefins, the facility comprising a plurality of reaction zones (R1, R2, R3, R4) connected in series and a fluid connection, in which reaction zones the feedstock flows continuously and the fluid connection ensures the transport of the catalyst by means of a carrier gas phase g1 from the downstream end of one reaction zone to the upstream end of the next reaction zone, the facility comprising a device for adjusting the temperature and / or pressure and / or composition of the carrier gas phase g1 in order to adjust its density, which density is measured under operating conditions at a temperature T of 200 to 550 °C and an absolute pressure P of 0.1 to 0.7 MPa and is ３ super, especially 1.2 kg / m ３ or more or 1.4 kg / m ３ or more or 1.6 kg / m ３ or more or 1.8 kg / m ３ or more or 2 kg / m ３ or more or 3 kg / m ３ or more, and preferably 5 kg / m ３ or less or 4 kg / m ３ or less. The facility is characterized by this.

15. The device for adjusting the pressure of the carrier gas phase g1 includes one or more compressors, and / or the device for adjusting the temperature of the carrier gas phase g1 includes one or more heat exchangers and / or one or more coolers, and / or the device for adjusting the composition of the carrier gas phase g1 includes a gas mixer feeding a hydrogen source and a nitrogen source and / or a C1-C6 hydrocarbon source, the hydrogen source and the C1-C6 hydrocarbon source being obtained from catalytic processes carried out in the installation, especially reforming, according to the installation of claim 14.

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