INTEGRATED PROCESS FOR THE THERMAL CONVERSION AND INDIRECT COMBUSTION OF A HEAVY HYDROGEN PREPARATION MATERIAL IN A CHEMICAL REDOX LOOP FOR THE PRODUCTION OF HYDROGEN FLOWS AND SEPARATION OF COPRODUCTS

Description

Scope of the invention

[0001] The invention relates to an integrated process for the thermal conversion of a heavy hydrocarbon feedstock and indirect combustion in a redox chemical loop for the production of hydrocarbon streams while capturing the gases emitted during combustion, and more particularly CO2. The invention is particularly suited to the treatment of heavy hydrocarbon feedstocks that are not in solid form, and which contain, in particular, high levels of sulfur. Previous art

[0002] Some petroleum products are difficult to process due to their high sulfur content. They can nevertheless be treated by thermal conversion processes, such as catalytic cracking, thermal cracking, hydrocracking, visbreaking, and pyrolysis. This type of feedstock tends to contaminate and deactivate catalysts, necessitating frequent and costly replacement of the catalysts used in catalytic processes. Therefore, catalyst-free processes have been developed.

[0003] In particular, the HTL (“Heavy to light”) process allows heavy loads to be treated by thermal conversion using a heat transfer fluid made of mineral particles, the heat required for the conversion being supplied by the circulating mineral particles.

[0004] US patent 5,792,340, for example, describes a process in which a feedstock undergoes rapid thermal conversion (by pyrolysis or cracking) in a reactor by mixing and rapid heat transfer with a stream of hot, inorganic solid particles (sand) injected into the reactor. The particles are then separated from the conversion products, heated (for example, by burning the coke deposited on them during thermal conversion), and then reinjected into the reactor.

[0005] Documents US2004069682A1 and US2004069686A1 describe a rapid thermal conversion (pyrolysis) process for a heavy feedstock in the presence of inorganic heat-carrying particles and a calcium-containing compound. The inorganic heat-carrying particles (e.g., sand) are then separated from the conversion products and regenerated before being returned to the thermal conversion zone. The presence of a calcium-based compound helps to reduce nitrogen oxide emissions.

[0006] Certain processes help limit CO2 production. Document WO2014140175A1 describes a thermal cracking process in which the heat required for cracking is supplied by mineral particles and combustion gases from a regenerator. The feedstock (a heavy, very heavy, or bitumen feedstock) is converted into gas and coke, which is deposited on the mineral particles. The coked mineral particles are carried along with the gases from the converted feedstock and regenerated in the regenerator before being returned with the combustion gases to the thermal cracking zone, while the converted gases are condensed and then fractionated.

[0007] Most processes, however, leave ultimate residues, such as coke, which are of little or no value and emit fumes containing substantial amounts of carbon dioxide (CO2).

[0008] For all industrial sectors, greenhouse gases, and in particular CO2, are considered pollutants whose emissions need to be controlled and reduced.

[0009] In particular, in the refining sector, many processes emit CO2-containing flue gases during operation, including the thermal conversion processes mentioned earlier. Most often, CO2 capture is achieved through a treatment that separates the CO2 from the other components of these flue gases, for example, by chemical absorption with a liquid solvent, usually an amine. After absorption in a first column, the solvent flows into a regeneration column where changing the pressure and temperature conditions (heating) desorbs the CO2 and "regenerates" the solvent. This heating is generally achieved using steam and is an energy-intensive step.

[0010] Chemical absorption carbon capture is the most widely used process, particularly because it offers a good balance between capture rate and the purity of the recovered CO2. However, other CO2 separation techniques exist, such as the use of membranes, cryogenic distillation, and adsorption.

[0011] Flue gas treatment can be energy-intensive when it comes to separating CO2 from nitrogen, such as in the flue gases of combustion plants. Other CO2 capture, or more precisely, separation, techniques can then be used. Oxy-combustion is a process that produces energy while capturing the CO2 generated during combustion. It involves burning the fuel with pure oxygen or oxygen-enriched air. As a result, the combustion gas will mainly contain CO2 and water, which can be easily separated and recovered. This process involves recirculating the combustion gases and mixing them with oxygen upstream of the combustion chamber to control and limit the combustion temperature. The most energy-intensive step is the upstream production of oxygen, which itself generates CO2.Alternative processes exist, such as chemical loop combustion (CLC), in which oxygen is supplied chemically. The CLC process also allows for energy production while capturing CO2.

[0012] The CLC process involves breaking down the combustion reaction into two successive reactions. A first oxidation reaction of an active mass, using air or another gas as an oxidant, oxidizes the active mass. A second reduction reaction of the oxidized active mass, using a reducing gas, then yields a reusable active mass and a gaseous mixture consisting primarily of CO2 (generally over 90% vol., sometimes even 98% vol.) and water, or possibly synthesis gas containing dihydrogen and nitric oxide. This technique thus allows the isolation of CO2 or synthesis gas from a gaseous mixture practically devoid of oxygen and nitrogen, thereby facilitating the separation and recovery of the CO2 or synthesis gas. The active mass, alternately changing from its oxidized to its reduced form and vice versa, undergoes a redox cycle.Thus, in the reduction reactor, the active mass (M x O y ), where M is a metal, is first reduced to the state M x O y-2n-m / 2 , via a hydrocarbon C n H m (n, m, x and y being non-zero integers), which is correlatively oxidized to CO 2 and H 2 O, according to reaction (1), or possibly to a mixture CO + H 2 depending on the proportions used. C n H m + MxOy -> n CO 2 + m / 2 H 2 O + M x O y-2n-m / 2 (1) .

[0013] In the oxidation reactor, the active mass is restored to its oxidized state (M x O y ) upon contact with air according to reaction (2), before returning to the first reactor. M x O y-2n-m / 2 + (n+m / 4) O 2 -> M x O y (2)

[0014] Oxycombustion, like the CLC process, thus makes it possible to produce energy, and not hydrocarbon flows, while capturing CO2.

[0015] US patent 10125323 describes a processing method in which a heavy feedstock is subjected to a cracking reaction in a reactor in the presence of metal oxides to form cracking products and coke deposited on the metal oxides. These products are then sent to a reduction reactor in a CLC loop where the coke is gasified in the presence of steam, producing synthesis gas and reduced metal oxides. Some of these reduced metal oxides are returned to the cracking reactor, and some are sent to an oxidation reactor in the CLC loop for reoxidation before being returned to the reduction reactor. However, implementing this process can be problematic. If the coke is not fully burned, the metal oxides will be difficult to reoxidize, which will limit coke combustion in the next cycle and again create difficulties in oxidizing the reduced metal oxides.

[0016] US9707532 discloses a process and installation for converting hydrocarbon feedstocks. Description of the invention

[0017] In order to overcome all or part of the aforementioned disadvantages, a thermal conversion process of a petroleum feedstock into lighter hydrocarbon products is proposed, this process producing little or no ultimate hydrocarbon residue, allowing for the capture of the CO2 produced. Definitions

[0018] By "inert particles" we mean chemically inert (solid) particles under normal reaction conditions, in other words, particles that are not likely to undergo chemical changes or catalyze chemical reactions.

[0019] By "hydrocarbon charge" or "hydrocarbon flux" we mean a mixture of hydrocarbon compounds, a hydrocarbon compound containing carbon and hydrogen, and possibly heteroatoms such as sulfur, nitrogen, metals, ....

[0020] By "non-carried bed" we mean a bed of particles whose level is controlled in order to maintain a constant bed height.

[0021] The term "fine particles" refers to particles whose average diameter has been reduced by abrasion, due to the friction of particles against each other, in other words, by attrition. Such particles therefore have an average diameter smaller than the average diameter of the particles before attrition.

[0022] The term "average diameter" refers to the diameter of a spherical particle of the same mass. This average diameter can be determined by any appropriate technique, including optical diffraction techniques (e.g., laser diffraction).

[0023] Downstream and upstream refer to the directions of fluid flow within the different zones of the installation. Summary of the invention

[0024] A first object of the invention relates to a process as defined in the claims.

[0025] In the process according to the invention, two distinct particle streams circulate: a first stream of hot, inert particles flows between the thermal conversion zone and the reduction zone of the redox chemical loop, and a second stream of oxygen-carrying particles flows between the reduction zone and the oxidation zone of the chemical loop. The inert particles thus act as heat transfer fluids. In particular, within the reduction zone, the oxygen-carrying solid particles and the inert particles flow in opposite directions, with the oxygen-carrying solid particles typically flowing from bottom to top.

[0026] During the thermal conversion stage, for example thermal cracking, a hydrocarbon stream is produced containing products lighter than the heavy hydrocarbon feedstock to be treated.

[0027] Furthermore, the coke, the final residue of the thermal conversion, is burned in the reduction zone of the thermal loop. The combustion of the coke thus provides the energy required for the thermal conversion of the heavy material. Moreover, the coke combustion process does not require a costly supply of oxygen but instead utilizes the oxygen-carrying solid particles.

[0028] Thus, the process according to the invention as a whole does not produce any ultimate residue and makes it possible to produce a hydrocarbon stream of interest while capturing the combustion gases generated, such as CO2, at a lower operating cost.

[0029] The oxygen-bearing solid particles, in a reduced or partially reduced state, form a bed situated above a bed formed by inert particles in the reduction zone. To this end, the process exhibits one or more of the following characteristics: a particle size distribution of the oxygen-bearing solid particles sufficiently smaller than that of the inert particles, for example, smaller by a factor of 1 to 1000, 100 to 1000, 1 to 10, or 1 to 2, or by a factor within a range defined by any two of these limits, in particular such that the oxygen-bearing solid particles are lighter than the inert particles; an appropriate choice of the average particle diameter, in particular such that the oxygen-bearing solid particles are lighter than the inert particles, for example, an average diameter of 50 µm to 2 mm or 50 µm to 500 µm; an appropriate choice of the density of the oxygen-bearing and inert particles, in particular such that the oxygen-bearing solid particles are lighter than the inert particles, for example, a density of 1500 to 6000 km / m³ or 1500 to 5000 kg / m³, an appropriate choice of hydrodynamic conditions for the reduction zone,in particular a surface velocity of a fluidizing gas in the reduction zone of 30 to 300% of the average terminal settling velocity of the inert particles, of 50 to 100% or of 75 to 125%.

[0030] Advantageously, the combustion of coke in the reduction zone can be total, which makes it possible to produce a second gaseous effluent concentrated in CO2, containing in particular 90% vol or more of CO2.

[0031] Advantageously, the second gaseous effluent produced in the reduction zone can be recovered and separated from the solid particles carrying oxygen in the reduced or partially reduced state.

[0032] The second gaseous effluent can then be cooled in at least one heat exchanger by exchanging heat with a fluid, for example, liquid water. Optionally, the heated fluid can be used to generate thermal or electrical energy. The energy from the combustion gases can thus be recovered and utilized.

[0033] Advantageously, the hot inert particles can form an undisturbed bed in the thermal conversion zone traversed by the circulating heavy load, particularly from bottom to top. This ensures good contact with the hot load and facilitates the recovery of the coked inert particles, which do not need to be separated from the initial effluent, which is, for example, recovered above the undisturbed bed.

[0034] Advantageously, the first gaseous effluent from the thermal conversion zone can be subjected, optionally directly, to fractionation in a fractionation zone, or optionally after separation of fines from coked inert particles, particularly immediately after this separation. This allows for the separation of the various hydrocarbon constituents of the first effluent for subsequent direct use or after further treatment. Specifically, sending the first gaseous effluent directly to the fractionation zone (possibly directly after fines separation) allows the heat from the first effluent exiting the thermal conversion zone to be utilized for fractionation, thus limiting the energy input required for the process.

[0035] In particular, the fractionation zone can separate the first gaseous effluent at least into a non-condensable gaseous fraction and a liquid fraction, preferably into at least a non-condensable gaseous fraction, a condensable gaseous fraction and a liquid fraction.

[0036] Optionally, at least part of said non-condensable gaseous fraction can be sent to the thermal conversion zone, in particular to improve hydrodynamic conditions and therefore performance in terms of heavy load conversion.

[0037] Advantageously, the oxygen-carrying solid particles in reduced or partially reduced state, from the reduction zone and separated from the second effluent, can be partially recycled back into the reduction zone to continue the coke conversion.

[0038] Advantageously, the hot inert particles, at least partially freed of coke, can be cooled before being returned to the thermal conversion zone in at least one heat exchanger by heat exchange with a fluid, for example, liquid water. This can allow the temperature of the hot inert particles returned to the thermal conversion zone to be regulated.

[0039] Advantageously, the second gaseous effluent, after separation of the reduced or partially reduced oxygen-carrying solid particles, and optionally after cooling, can be subjected to at least one purification treatment, in particular to remove any impurities present such as dust, nitrogen oxides (NOx), sulfur oxides (SOx), and carbon monoxide (CO). The purification treatment(s) can be carried out in one or more purification zones.

[0040] Advantageously, the oxidizing gas used in the oxidation zone of the thermal loop is air, so there is no need to supply the process with expensive dioxygen, the production of which generates CO2.

[0041] Advantageously, the oxidizing gas reduced during the re-oxidation of the oxygen-carrying solid particles can be separated from the re-oxidized oxygen-carrying solid particles and then subjected to at least one purification treatment, in particular to remove any impurities present such as dust, nitrogen oxides, sulfur oxides, and carbon monoxide. The purification treatment(s) can be carried out in one or more purification zones, preferably separate from any zones intended for the treatment of the second gaseous effluent.

[0042] The heavy hydrocarbon feed treated by the process according to the invention can be chosen from hydrocarbon feeds with high sulfur content, atmospheric residues, vacuum residues, alone or in mixture.

[0043] The process according to the invention is particularly suitable for the treatment of heavy petroleum products, and in particular petroleum distillation residues, effluents from thermal conversion processes, catalytic cracking processes, hydrocracking processes, deep hydroconversion processes, atmospheric or vacuum residue hydrotreatment processes (ARDS or VRDS) or even fuel oils from mixtures of heavy products.

[0044] The heavy hydrocarbon feedstock can be a mixture of heavy hydrocarbon compounds with a boiling point greater than or equal to 350°C, denoted 350°C+. In particular, the process according to the invention is suitable for the treatment of heavy hydrocarbon feedstocks with a high sulfur content, namely having a sulfur content greater than or equal to 0.5% w(m), 1% w, 1.5% w, 2% w, 3% w, or more.

[0045] The invention is not suitable for treating heavy solid hydrocarbon feedstocks of the coke, coal, and coked catalyst type from a fluidized bed catalytic cracking (FCC) process.

[0046] The invention also relates to an installation as defined in the claims.

[0047] The installation may include one or more of the following features: a second gas-solid separation device for separating a second gaseous effluent from the reduced or partially reduced oxygen-bearing solid particles located on the discharge line for the reduced or partially reduced oxygen-bearing solid particles from the reduction zone; a third gas-solid separation device for separating the reduced oxidizing gas exiting the oxidation zone from the re-oxidized oxygen-bearing solid particles located on the discharge line for the re-oxidized oxygen-bearing solid particles from the oxidation zone; a fractionation zone fed by the first gaseous effluent from the thermal conversion zone, optionally downstream of the first gas-solid separation device, the fractionation zone being optionally equipped with a recycle line for a non-condensable gaseous fraction feeding the thermal conversion zone.a recycling line for reduced or partially reduced oxygen-carrying solid particles from the second gas-solid separation device to the reduction zone feed; one or more heat exchangers selected from a heat exchanger to cool the second gaseous effluent from the second gas-solid separation device and a heat exchanger to cool the recycled inert particles in the thermal conversion zone; at least one purification system to purify the second gaseous effluent from the second gas-solid separation device; optionally, downstream of said system, at least one heat exchanger; and at least one other purification system for the reduced oxidizing gas from the third gas-solid separation device. Detailed description of the invention Thermal conversion of heavy hydrocarbon feedstock

[0048] The thermal conversion reaction of the heavy hydrocarbon feed takes place in the thermal conversion zone, in the absence of dioxygen and catalyst, in which the feed is brought into contact with inert particles producing a first gaseous effluent which can then be evacuated and coke which is deposited on the inert particles.

[0049] This first step is similar to the thermal conversion carried out in the previously mentioned HTL process.

[0050] It should be noted that the thermal conversion reaction can be carried out in the presence of dihydrogen, which can help stabilize the conversion products and further desulfurize the feedstock. The unconsumed dihydrogen can then be recovered, for example by fractionating the initial gaseous effluent.

[0051] These inert particles can, for example, be chosen from silica or any other heat-transfer material, preferably with a hardness equivalent to that of silica to avoid the formation of fines. Magnesium oxides, aluminum oxides, copper oxides, or similar materials could be used.

[0052] Within the thermal conversion zone, the feed to be treated circulates, preferably through a bed of inert particles whose level is controlled. In other words, under normal operating conditions, the inert particles are not carried away with the initial gaseous effluent but form a bed that is not swept away.

[0053] The feedstock to be treated can, for example, flow from bottom to top in one or more riser-type reactors. It is first vaporized before being converted into a gas that exits the reaction zone from the top and into coke that is deposited on the inert particles. The coked inert particles leave the thermal conversion zone by withdrawal, preferably near the top of the inert particle bed.

[0054] Alternatively, inert particles could also circulate from the thermal conversion zone to the reduction zone of the thermal loop and vice versa, using, for example, circulating fluidized bed technology. In this case, coked inert particles are recovered at the outlet (e.g., in the upper zone) of the thermal conversion zone mixed with the first effluent, from which they are separated by the first gas-solid separation device before being sent to the reduction zone.

[0055] Under the operating conditions of the process according to the invention, namely at atmospheric pressure, at a temperature advantageously ranging from 450°C to 600°C, preferably from 480°C to 550°C (inclusive).

[0056] In general, the contact time between the charge to be treated and the hot inert particles in the reaction zone can be from a few seconds to several minutes, for example 5 seconds to 10 minutes.

[0057] In general, the ratio of inert particles to the load to be treated within the thermal conversion zone can be determined by a person skilled in the art based on the residence times of the load.

[0058] Thermal conversion produces coke and hydrocarbon compounds that are lighter than those initially contained in the heavy hydrocarbon feedstock.

[0059] The gaseous hydrocarbon stream produced by thermal conversion generally contains a liquid fraction forming a synthetic crude oil (also called "syncrude" or "synthetic crude") with olefins and a valuable gaseous fraction containing many olefins.

[0060] The performance of the thermal conversion process can be controlled in the usual way by monitoring the flow rate of the feed being treated, the temperature of the inert particles entering the reaction zone, the ratio of feed flow rate to inert particle flow rate entering the reaction zone, and the hydrodynamic conditions. The hydrodynamic conditions can be improved, in particular, by injecting one or more of the following fluids: the non-condensable gaseous fraction resulting from the fractionation of the first gaseous effluent, water vapor, or dihydrogen.

[0061] When the feed to be treated includes compounds containing heteroatoms (sulfur, nitrogen, metals), these are deposited onto the inert particles during thermal conversion. Thus, despite the absence of a catalyst, the process reduces the nitrogen, sulfur, and metal content of the converted feed.

[0062] At the outlet of the thermal conversion zone, a first gaseous effluent is collected, consisting of hydrocarbon compounds, coke, and inert particles. The coke (and possibly nitrogen, sulfur, and / or metals) has been deposited on these particles. This first gaseous effluent is then collected, notably at the top of the reaction zone, optionally after separation of the coked inert particles in a gas-solid separation device, such as one or more cyclone separators. The coked inert particles are then removed from the reaction zone and sent, often directly, to the reduction zone of the chemical loop. There, they are partially or completely stripped of coke, and optionally of any sulfur and / or nitrogen present, before being returned to the thermal conversion zone for another cycle.

[0063] The inert particles thus circulate continuously between the thermal conversion zone and the reduction zone of the redox chemical loop.

[0064] Since the thermal conversion reaction is endothermic, the energy required is supplied at least in part by the exothermic combustion of all or part of the coke produced in the redox chemical loop, via the at least partially decoked inert particles exiting the reduction zone of the chemical loop and entering the thermal conversion zone.

[0065] During the various cycles, inert particles can disintegrate through attrition. They can also become increasingly saturated with metals, or even unburned coke. It is therefore possible to regularly remove some of these particles, for example, before they enter the reduction zone of the thermal loop, particularly at the outlet of the thermal conversion zone, and to add new particles, for example, before they enter the thermal conversion zone. This method also allows for the control of the heat released in the reduction zone or supplied to the thermal conversion zone.

[0066] The temperature of the inert particles coming from the reduction zone of the thermal loop and entering the thermal conversion zone can also be regulated by means of one or more heat exchangers arranged on the pipe transporting the inert particles from the chemical loop to the thermal conversion zone. Chemical loop coke combustion reaction

[0067] The closed-loop redox combustion plant comprises an oxidation zone and a reduction zone. Oxygen-carrying solid particles circulate from one reaction zone to the other, using, for example, circulating fluidized bed technology with a fluidizing gas. This allows the oxygen-carrying solid particles to flow continuously from one zone to the other.

[0068] The oxygen-carrying solid is oxidized by an oxidizing gas, usually air, in an oxidation zone comprising at least one fluidized bed at a temperature typically ranging from 700 to 1200°C, preferably from 800 to 1000°C. It is then transferred to a reduction zone comprising at least one fluidized bed reactor where it is brought into contact with the fuel (here, the coke deposited on the inert particles, which may contain, in addition to carbon, nitrogen, sulfur, hydrogen, and metals) at a temperature typically ranging from 800 to 1200°C, preferably from 900 to 1100°C. The contact time typically varies between 10 seconds and 10 minutes, preferably from 1 to 5 minutes. The oxygen-carrying solid is then transferred back to the oxidation zone.

[0069] The ratio between the circulating active mass and the amount of oxygen to be transferred between the two reaction zones can advantageously be from 20 to 100.

[0070] Usable oxygen-bearing solid particles are generally composed of a couple or set of redox couples chosen from CuO / Cu, Cu 2 O / Cu, NiO / Ni, Fe 2 O 3 / Fe 3 O 4 , FeO / Fe, Fe 3 O 4 / FeO, MnO 2 / Mn 2 O 3 , Mn 2 O 3 / Mn 3 O 4 , Mn 3 O 4 / MnO, MnO / Mn, Co 3 O 4 / CoO, CoO / Co, and often a binder providing physico-chemical stability.

[0071] Many types of binders can be used, such as yttrium-stabilized zirconia, also called yttrium zirconia (YSZ), alumina, metallic aluminate spinels, titanium dioxide, silica, zirconia, kaolin, or a cerium-zirconia type binder. The mass ratio of the redox couple to the binder is generally around 60 / 40 in order to obtain particles with good mechanical strength as well as sufficient redox properties (oxidation and reduction rates and oxygen transfer capacity).

[0072] One can also use ilmenite ore (FeTiO 3) or even spent silica and alumina-based catalysts impregnated with metallic salts preferably based on iron, nickel, copper, cobalt or manganese, as described in FR2930733B1, these catalysts come from fluidized bed catalytic cracking plants.

[0073] The coke deposited on the inert particles is thus introduced into the reduction zone where it is oxidized by the oxygen-carrying solid, which is in an oxidized state when introduced into the reduction zone. The maximum oxygen capacity actually available can vary considerably depending on the nature of the oxygen-carrying solid, and is generally between 0.1 and 15% by mass, and often between 0.3 and 6% by mass.

[0074] In the reduction zone, coke combustion can be partial or total, preferably total in order to produce a second effluent rich in CO2, namely containing 90% vol. or more CO2. Partial combustion with the production of dihydrogen is however conceivable.

[0075] In the case of complete combustion, the gas stream exiting the reduction reactor consists primarily of CO₂ and water vapor (i.e., containing 90% vol. or more of CO₂ and water vapor), and possibly NO₂ and SO₂, with metals remaining on the inert particles. A CO₂ stream ready for sequestration is then obtained by condensing the water vapor.

[0076] In the case of partial combustion, the active mass / fuel ratio can be adjusted to achieve partial oxidation of the fuel, producing a synthesis gas in the form of a CO + H₂ mixture. The process can therefore be used for the production of synthesis gas. Furthermore, the CO produced can then be converted back into CO₂ using well-established technologies.

[0077] If the fluidizing gas used is steam or a mixture of steam and other gases, the reaction of CO₂ with water (or water gas shift, CO + H₂O → CO₂ + H₂) can also occur, resulting in the production of a CO₂ + H₂ mixture at the reactor outlet. In this case, the combustion gas can be used for energy production due to its calorific value. This gas can also be used for hydrogen production, for example, to supply hydrogenation units, hydrotreating units in refining, or a hydrogen distribution network (after the water gas shift reaction).

[0078] Depending on the intended use of the combustion gases, the process pressure will be adjusted. For complete combustion, it is advantageous to operate at low pressure to minimize the energy cost of gas compression and thus maximize the plant's energy efficiency. To produce syngas by partial combustion, it may be beneficial in some cases to operate at higher pressures to avoid compressing the syngas upstream of the downstream synthesis process. For example, since the Fischer-Tropsch process operates at pressures between 20 and 40 bar, producing the gas at a higher pressure may be advantageous.

[0079] It should be noted that when metals are deposited on inert particles during thermal conversion, these metals remain on the particles exiting the reduction zone. It may then be necessary to remove the metal-laden inert particles from circulation and inject new inert particles.

[0080] On the contrary, sulfur and nitrogen are respectively transformed into sulfur oxides and nitrogen oxides in the reduction zone and are discharged with the second effluent.

[0081] The particle size of the oxygen-carrying solid is chosen to be sufficiently smaller than that of the inert particles so that the oxygen-carrying solid particles float above the inert particles in the fluidized bed of the reduction zone. In other words, two distinct particle beds are formed: the lower bed consists primarily (more than 80% by mass) of inert particles, while the upper bed consists primarily of oxygen-carrying solid particles. This allows the oxygen-carrying solid particles to be recovered from the upper part of the reduction zone, mixed with the second gaseous effluent, and the inert particles from the lower part of the reduction zone. The latter are then returned to the feed of the thermal conversion zone.

[0082] Advantageously, in general, two distinct particle beds can be obtained by selecting particles of different size distributions, possibly with oxygen-bearing solid particles lighter than inert particles (in the absence of coke), and appropriate hydrodynamic conditions in the reduction zone. While oxygen-bearing solid particles lighter than inert particles (in the absence of coke) can be achieved by appropriately selecting the particle size based on the density of the constituent material, it is still preferable to use a smaller particle size for the oxygen-bearing solid particles than for the inert particles.Typically, oxygen-carrying solid particles and inert particles with a density of 500 to 6000 kg / m³, preferably 1500 to 5000 kg / m³, and an average diameter of 50 µm to 2 mm, or even 50 µm to 500 µm, can be used. In particular, the average diameter of the oxygen-carrying particles can be smaller than the average diameter of the inert particles by a factor of 1 to 1000, or even 100 to 1000, preferably 1 to 10, most often 1 to 2, or by a factor within an interval defined by any two of these limits. The value 1 can be excluded from these intervals. The person skilled in the art will know how to choose the average diameters and densities of these particles in these ranges and the appropriate hydrodynamic conditions in order to obtain two distinct beds of particles: a bed of solid particles carrying oxygen and, below this, a bed of inert particles.

[0083] Appropriate hydrodynamic conditions can be achieved by adjusting the surface velocity of the bottom-flowing gaseous fluid as a function of the average terminal settling velocity of the inert particles, sufficient to separate the heavier inert particles from the lighter oxygen-carrying solid particles. This bottom-flowing gaseous fluid is the fluidizing gas of the reduction zone and can be composed of combustion gases (i.e., the second effluent of the present invention, injected at the bottom of the reduction zone via a recycling line), water vapor, or a mixture of both. The surface velocity of the gaseous fluid, particularly for particles in the ranges of average diameter and density mentioned above, can be set at a value ranging from 30 to 300% of the average terminal settling velocity of the inert particles, preferably from 50 to 150%, and more preferably from 75 to 125%.A person skilled in the art will be able to determine the surface velocity of the fluidizing gas in the reduction zone based on the average diameter and density of the different particles, and in particular on the difference in mass between these particles and / or the difference in particle size. Each of the ranges mentioned above for average diameter, density, mass difference, and difference in average diameter can be combined with one or more of the other ranges for one or more of these characteristics.

[0084] The average terminal fall velocity is obtained from the following formula (3): Vt = 4 d p ρ s − ρ g g 3 ρ g C D 1 2 Or : dp is the average diameter of the particles ρ s is the density of the particles (kg / m³) ρ g is the density of the gaseous fluid (kg / m³) CD is the drag coefficient g, acceleration due to the force of gravity (m / sec 2< ).

[0085] Advantageously, the oxygen-bearing solid particles from the oxidation zone are introduced into the reduction zone in a lower part of it, below the introduction of the inert particles. In other words, the oxidized oxygen-bearing solid particles enter the reduction zone upstream of the coked inert particles from the thermal conversion zone, relative to their direction of flow. This promotes contact between the two types of particles and coke reduction, particularly through counter-current flow of the coked inert particles, which flow from top to bottom, and the oxygen-bearing particles, which flow from bottom to top.This counter-current circulation can be promoted by the injection of the fluidizing gas (water vapor and / or combustion gas) circulating from bottom to top, this injection being advantageously carried out below the introduction of the oxygen-carrying solid particles.

[0086] In particular, the introduction of inert coked particles from the thermal conversion zone can preferably be carried out at the top of the lower bed.

[0087] Advantageously, the decoked inert particles (at least partially) can be drawn from the bottom of the reduction zone to be returned to the thermal conversion zone.

[0088] Advantageously, the oxygen carrier particles can be micrometer-sized and the inert particles millimeter-sized. The size difference between the two types of particles can thus be from 100 to 1000; however, particles with an average diameter differing by a factor of 1 to 1000, preferably 1 to 10, most often 1 to 2, or by a factor within an interval defined by any two of the aforementioned limits, may be chosen. The value 1 may be excluded from these intervals. Such a size difference promotes separation into two beds, particularly when the hydrodynamic conditions are met, namely when the fluidizing gas flows from bottom to top.

[0089] The solid particles carrying oxygen, reduced totally or partially following the oxidation of the coke, are thus found in the upper part of the reduction zone from which they are removed.

[0090] The oxygen-carrying solid particles are generally discharged mixed with the second gaseous effluent. They can then be separated from the latter in a second gas-solid separation device, comprising, for example, one, two, or more cyclone separation devices, preferably at least three.

[0091] The oxygen-carrying solid particles thus recovered can then either be sent entirely to the oxidation zone, or be sent partly to the oxidation zone and the remainder to the entrance of the reduction zone to continue the reduction of the coke.

[0092] The second gaseous effluent consists primarily of carbon dioxide and water (i.e., 90% vol. or more of CO₂ and water), particularly when combustion is complete. It may also contain dust, nitrogen oxides, and sulfur oxides, which can be removed by appropriate treatment in one or more purification systems. For example, condensation systems can be used to recover water and potentially NOx or SOx, along with NOx reduction systems (DeNOx), SOx reduction systems (DeSOx), dust collection systems (using filters, electrostatic precipitators, etc.), and systems for converting residual CO₂ to CO₂. Heat from the second gaseous effluent can be recovered using one or more heat exchangers, preferably located upstream of the purification system(s).Such purification treatments make it possible to separate / recover CO2, in other words to capture it, for later use, these separations / recoveries being facilitated by the high levels of CO2 produced during total combustion in the second effluent.

[0093] In the oxidation zone, the oxygen-bearing solid particles are re-oxidized, at least partially, preferably completely, by the oxidizing gas. Advantageously, they are introduced at the lower end of the oxidation zone, along with the oxidizing gas, most often air. They are then collected at the upper end of the oxidation zone, for example, mixed with oxygen-depleted air, from which they can then be separated in a third gas-solid separation device, such as one or more cyclone separators. The oxygen-depleted air can then be purified to remove any impurities such as dust. The recovered re-oxidized oxygen-bearing solid particles are then reinjected into the reduction zone, preferably at its lower end, following the introduction of inert particles.Optionally, some of the re-oxidized oxygen-carrying solid particles can be reinjected into the oxidation zone to continue their oxidation.

[0094] During the different cycles, the oxygen-carrying solid particles can disintegrate by attrition: it is then possible to regularly remove some of them, for example after they exit the oxidation zone, especially after their separation from the air, and to add new ones, for example at the entrance to the oxidation zone or upstream of this entrance. Fractionation of the first gaseous effluent

[0095] The first gaseous effluent exiting the thermal conversion zone, after possible separation of the fines from the coked inert particles, can be used directly or treated.

[0096] In a preferred embodiment, the first gaseous effluent, after separation of the inert coked particles, can advantageously be sent to a fractionation zone in order to recover and separate several fractions of hydrocarbon compounds.

[0097] This fractionation zone may include one or more distillation columns chosen from an atmospheric pressure distillation column and a vacuum distillation column, preferably an atmospheric pressure distillation column.

[0098] Fractionation can advantageously allow the separation of at least one non-condensable gaseous fraction and one liquid fraction.

[0099] In one embodiment, fractionation can allow the separation of at least one non-condensable gaseous fraction, one condensable gaseous fraction and one liquid fraction.

[0100] The non-condensable gas fraction may include gases such as methane, ethane, propane, butane, dihydrogen sulfide, olefins (ethylene, propylene, butene, etc.), primarily methane, ethane, propane, and dihydrogen sulfide. These gases can advantageously be partially directed to the conversion zone to improve hydrodynamic conditions.

[0101] The condensable gaseous fraction may include hydrocarbons that have at least 5 carbon atoms (e.g., from 5 to 35 carbon atoms). It can be mixed with the liquid fraction.

[0102] Part of the condensable gaseous fraction, particularly the heavier part, can be recycled as a charge for thermal conversion to produce more gas and middle distillates.

[0103] The liquid fraction can form a syncrude, which can be sent to conventional refining processes if necessary. This liquid fraction can also be fractionated into several cuts (naphtha, middle distillate, atmospheric residue).

[0104] These different fractions can then possibly be subjected to further conventional refining or synthesis treatments depending on the desired use. Description of the figures

[0105] The invention is now described with reference to the accompanying, non-limiting drawings, in which: The figure 1 represents an example of the realization of an installation implementing the process according to the invention.

[0106] In the figure, references relating to circulating fluids are in parentheses.

[0107] Initially, the heavy hydrocarbon load 1,For example, a petroleum product with a high sulfur content is subjected to thermal conversion in a reaction zone. 100, Here, a fluidized bed reactor is not carried away, in the presence of hot inert particles. 2. For this purpose, the reaction zone 100 includes a power supply 101 heavy hydrocarbon load 1 and a diet 102 into hot inert particles 2. Heavy hydrocarbon load 1 and hot inert particles 2 are introduced into the lower part of the reaction zone 100. Hot inert particles 2 form a bed 3 not carried at a constant height. The power supply 101 heavy hydrocarbon load 1 is located here above the power supply 102 into hot inert particles 2. Upon contact with hot inert particles 2at high temperature, the heavy hydrocarbon load 1 undergoes thermal conversion, generating a gaseous effluent 4 (hereafter referred to as the first gaseous effluent) progressing vertically upwards in the reaction zone 100 and coke depositing on hot inert particles 2. Generally, the heavy hydrocarbon load 1 is introduced into the reaction zone 100 via injectors that spray it.

[0108] The reaction zone 100 also includes a drain pipe 103 of the first gaseous effluent 4 essentially composed of hydrocarbon compounds most often mixed with fine inert coke particles 5. The drain pipe 103, located in the upper part of the reaction zone 100, is equipped with a primary gas-solid separation device 104to separate the first gaseous effluent 4 fine inert particles of coked 5. As an example, the first gas-solid separation device 104 may include two cyclones.

[0109] The fine inert particles of coked 5 are evacuated from the system (5") by driving 105, but part of it can be recycled (5') towards the reaction zone 100 via a pipe 106 opening into the bed 3 of inert particles. The inert particles coked 16 are evacuated from the reaction zone 100 via driving 107. Driving 107 extract the inert coke particles here 16 from an upper part, especially from the top, of the bed 3 of inert particles inside the reaction zone 100. The coke deposited on the surface of the inert coked particles 16is then burned in a chemical loop 200 which includes a reduction zone 300 and an oxidation zone 400.

[0110] The reduction zone 300, Here, a fluidized bed reactor includes a power supply. 301 in inert coke particles 16 originating from the reaction zone 100, a diet 302 in solid particles carrying oxygen in an oxidized state 17 originating in part from the oxidation zone 400 and a gas-solid separator 305, a drain pipe 303 inert particles at least partially free of coke 7, which form at least a part of the hot inert particles 2 entering the thermal conversion zone 100.

[0111] The reduction zone 300 also includes a drain pipe 304of solid particles carrying oxygen in a reduced or partially reduced state mixed with a second gaseous effluent 8, rich in CO2 and H2O when combustion is complete. This exhaust pipe 304 is equipped with a second gas-solid separation device 305 to separate the second gaseous effluent 8 particles of solid carrying oxygen in a reduced or partially reduced state 9.

[0112] Food 302 in solid particles carrying oxygen in an oxidized state 17 is located in the lower part of the reduction zone 300, under the food supply 301 in inert coke particles 16. This promotes a counter-current of inert coke particles 16 and oxygen carrier particles in an oxidized state 17 To achieve coke combustion, a fluidizing gas, in this case steam, is injected via a feed.19 planned under the power supplies 301 And 302. The difference in particle size between these particles, the gas generated by the combustion of coke and / or the injection of steam via the feed 19 allow this counter-current movement and the formation of two particle beds: a lower bed 306 composed essentially of inert particles through which solid particles carrying oxygen in an oxidized state pass 17 transferring their oxygen for coke combustion. an upper bed 307 composed essentially of solid particles carrying oxygen in a reduced or partially reduced state 9.

[0113] A diet 18 of the reduction zone 300 (located here under the food 301 in inert coked particles and above the food supply 302 in solid particles carrying oxygen in an oxidized state 17)allows for the replenishment of inert particles 2' (attrition loss drawn in 106' or subtraction from the installation via the pipe 106"). However, the invention is not limited to this position of the fresh inert particle supply. 2', nor to these positions of extractions of worn / degraded inert particles.

[0114] The drain pipe 303 mostly inert particles 7 refers these to the food supply 102 of the thermal conversion zone 100. This drain pipe 303 is located here at the bottom of the reduction zone 300. A heat exchanger 105 allows control of the temperature at which inert particles reach the thermal conversion zone 100.

[0115] The oxidation zone 400, Here, a fluidized bed reactor includes a power supply. 401in oxidizing gas 10, a diet 402 in solid particles carrying oxygen in a reduced or partially reduced state 9' coming from the second separation device 305 and a drain pipe 403 solid particles carrying oxygen in an oxidized or partially oxidized state 6.

[0116] In this example, this drain pipe 403 is equipped with a third gas-solid separation device 404 for the separation of solid particles carrying oxygen in an oxidized or partially oxidized state 6 and oxidizing gas with a reduced oxygen content 11. The flow of solid particles carrying oxygen in an oxidized or partially oxidized state 6 is returned in part or in whole, mixed with some of the solid particles carrying reduced or partially reduced oxygen 9", towards the reduction zone 300via a pipe 405 connected to the power supply 302. Part 6' solid particles carrying oxygen in an oxidized state 6 can also be returned to the inlet of the oxidation zone to continue their oxidation. In order to maintain the capacity of the oxygen-carrying solid particles to transfer oxygen, some of the particles at equilibrium can be removed from the system (via the conduit) 403') and a supplement of fresh particles (20) can be carried out, for example, upstream of the reduction zone 300.

[0117] Since the oxidizing gas is generally air, the oxidizing gas has a reduced oxygen content. 11 This is then air enriched with nitrogen. This flow of air enriched with nitrogen 11 may possibly be sent for further purification treatment.

[0118] The installation shown also includes a splitting zone 500fed by the first gaseous effluent 4 of the thermal conversion zone 100. The split zone 500 This is a distillation column under atmospheric pressure.

[0119] At the exit of the fractionation zone, a non-condensable gaseous fraction is recovered. 13, a condensable gaseous fraction 14 and a liquid fraction 15. The distillation column can optionally be equipped with additional draw-offs to produce middle distillate cuts and a residue (or bottoms). The sulfur content of the different liquid fractions will be significantly lower than that of the feed. 1. Depending on the sulfur content of the initial feedstock, certain fractions can be used as marine fuel with a sulfur content below 0.5% wt%. At a minimum, the distillation column will produce a fraction in non-condensable gas. 13and a liquid fraction (syncrude) by mixing the fractions 14 And 15. The non-condensable gaseous fraction 13 can be partially recycled to the reaction zone 100 to improve hydrodynamic conditions and therefore performance in terms of heavy load conversion 1. For this purpose, a compressor 502 may be planned for driving 501 recycling part of the non-condensable gaseous fraction 13 towards the reaction zone 100.

[0120] The installation shown here includes a heat exchanger 311 used to cool the second gaseous effluent 8 and produce, on the utility side, water vapor 21 which can be used either as a heat transfer fluid or to generate electricity via a turbine. The installation shown also includes a purification system 312to condense water and remove SOx and NOx, or even to remove dust from the stream and / or convert any CO produced (in case of incomplete combustion of coke) into CO2, thus producing a concentrated CO2 stream that can be transported and used or stored.

Claims

1. A method for converting a heavy hydrocarbon feedstock into a lighter hydrocarbon stream and coke by thermal conversion and coke conversion by combustion in a redox chemical loop wherein: - a thermal conversion of the heavy hydrocarbon feedstock is carried out in a thermal conversion zone by bringing it into contact with hot inert particles to produce, in the absence of dioxygen and a catalyst, optionally in the presence of water vapour and / or dihydrogen, a first gaseous effluent of hydrocarbon compounds and coke, the latter being deposited on the inert particles, - the coked inert particles are discharged from the thermal conversion zone and are sent to a reduction zone of a redox chemical loop in which particles of an oxygen-carrying solid flow, - a combustion of the coke deposited on the discharged coked inert particles is carried out in the reduction zone to produce a second gaseous effluent, hot inert particles at least partially freed from coke and oxygen-carrying solid particles in the reduced or partially reduced state, the oxygen-carrying solid particles having a particle size sufficiently smaller than that of the inert particles and / or an average diameter and / or a density such that they are lighter than the inert particles and that the oxygen-carrying solid particles in the reduced or partially reduced state form a bed located above a bed formed by the inert particles in the reduction zone, - the oxygen-carrying solid particles in the reduced or partially reduced state are discharged from the reduction zone and at least partially returned to an oxidation zone of the chemical loop to oxidise them by means of an oxidising gas before reintroducing them into the reduction zone, - the hot inert particles which are at least partially freed from coke are discharged from the reduction zone and at least partially returned to the thermal conversion zone, the energy necessary for the thermal conversion reaction being at least partially provided by the exothermic combustion of all or part of the coke in the reduction zone.

2. The method according to claim 1, wherein the second gaseous effluent produced in the reduction zone is recovered and separated from the oxygen-carrying solid particles in the reduced or partially reduced state.

3. The method according to claim 2, wherein the second gaseous effluent, produced in the reduction zone and separated from the oxygen-carrying solid particles in the reduced or partially reduced state, is cooled in at least one heat exchanger by heat exchange with a fluid, for example water in liquid form, and, optionally, the heated fluid is used to generate thermal or electrical energy.

4. The method according to any one of claims 1 to 3, wherein the hot inert particles form a non-entrained bed in the thermal conversion zone passed through by the flowing heavy feedstock.

5. The method according to any one of claims 1 to 4, wherein the first gaseous effluent originating from the thermal conversion zone is subjected, optionally directly, to fractionation in a fractionation zone, optionally after separation of coked inert particle fines.

6. The method according to claim 5, wherein the fractionation zone separates the first gaseous effluent at least into an incondensable gaseous fraction and a liquid fraction, and, optionally, at least one portion of said incondensable gaseous fraction is returned to the thermal conversion zone.

7. The method according to any one of claims 1 to 6, wherein the oxygen-carrying solid particles in the reduced or partially reduced state originating from the reduction zone and separated from the second effluent, are partially recycled in the reduction zone.

8. The method according to any one of claims 1 to 7, wherein the hot inert particles, which are at least partially freed from coke, are cooled before they are returned to the thermal conversion zone in a heat exchanger by heat exchange with a fluid, for example water in liquid form.

9. The method according to any one of claims 1 to 8, wherein at least one fluid selected from: - the second gaseous effluent after separation of the oxygen-carrying solid particles in the reduced or partially reduced state and optionally after cooling, - the oxidising gas reduced during the re-oxidation of the oxygen-carrying solid particles after separation of the re-oxidised oxygen-carrying solid particles, is subjected to a purification treatment.

10. The method according to any one of claims 1 to 9, wherein the heavy hydrocarbon feedstock is selected from hydrocarbon feedstocks with high sulphur content, atmospheric residues, vacuum residues, alone or in combination.

11. The method according to any one of claims 1 to 10, comprising one or more of the following features: - a particle size of the oxygen-carrying solid particles which is sufficiently lower than that of the inert particles, optionally lower by a factor from 1 to 1000, - an average diameter of the oxygen-carrying solid particles and inert particles from 50 µm to 2mm, - a density of oxygen-carrying solid particles and inert particles from 500 to 6000 kg / m3, - a superficial velocity of a fluidisation gas of the reduction zone from 30 to 300% of the terminal average fall velocity of the inert particles.

12. An installation for converting a heavy hydrocarbon feedstock for implementing the method according to any one of claims 1 to 11, comprising at least: - one thermal conversion reaction zone (100), devoid of supply of dioxygen and catalyst, optionally equipped with a supply of water vapour and / or dihydrogen, comprising a supply (101) of heavy hydrocarbon feedstock, a supply (102) of hot inert particles, a first conduit (103) for discharging a first gaseous effluent comprising hydrocarbon compounds and a second conduit (107) for discharging coked inert particles, the first discharge conduit (103) being optionally equipped with a first gas-solid separation device (104) to separate the first gaseous effluent from the coked inert particle fines, - one redox chemical loop (200) comprising a reduction zone (300) and an oxidation zone (400) in which particles of an oxygen-carrying solid flow, the reduction zone (300) comprising at least one fluidised bed, a supply (301) of hot coked inert particles connected to the second conduit (107) for discharging coked inert particles from the thermal conversion zone (100), a supply (302) of oxygen-carrying solid particles originating from the oxidation zone (400), a conduit (303) for discharging the inert particles, which are at least partially freed from coke, connected to the supply (102) of hot inert particles of the thermal conversion zone, a conduit (304) for discharging the oxygen-carrying solid particles in the reduced or partially reduced state, a supply (302) of oxygen-carrying solid particles being located in the lower portion of the reduction zone (300), under the supply (301) of coked inert particles, and the oxidation zone (400) comprising at least one fluidised bed, a supply (401) of oxidising gas, a supply (402) of oxygen-carrying solid particles in the reduced or partially reduced state connected to the discharge conduit of the reduction zone and a conduit (403) for discharging the re-oxidised oxygen-carrying solid particles connected to the supply (302) of oxygen-carrying solid particles of the reduction zone.

13. The installation according to claim 12, comprising at least one of the following features: - a second gas-solid separation device for separating a second gaseous effluent from the oxygen-carrying solid particles in the reduced or partially reduced state located on the conduit for discharging the oxygen-carrying solid particles in the reduced or partially reduced state from the reduction zone, - a third gas-solid separation device for separating the reduced oxidising gas exiting the oxidation zone from the re-oxidised oxygen-carrying solid particles located on the conduit (403) for discharging the re-oxidised oxygen-carrying solid particles from the oxidation zone.

14. The installation according to claim 13, comprising a conduit for recycling oxygen-carrying solid particles in the reduced or partially reduced state originating from the second gas-solid separation device to the supply of the reduction zone.

15. The installation according to any one of claims 12 to 14, comprising one or more heat exchangers selected from a heat exchanger (311) to cool the second gaseous effluent originating from the second gas-solid separation device and a heat exchanger (105) to cool the recycled inert particles in the thermal conversion zone.

16. The installation according to any one of claims 13 or 14 or 15 when it depends on claims 13 or 14, comprising at least one of the following features: - at least one purification system (312) to purify the second gaseous effluent originating from the second gas-solid separation device, optionally downstream of said at least one heat exchanger, - at least one other system for purifying the reduced oxidising gas originating from the third gas-solid separation device.

17. The installation according to any one of claims 12 to 16, further comprising a fractionation zone (500) supplied by the first conduit (103) for discharging the first gaseous effluent from the thermal conversion zone, optionally downstream of the first gas-solid separation device, the fractionation zone being optionally equipped with a conduit (501) for recycling an incondensable gaseous fraction supplying the thermal conversion zone.