Flat-top chemical looping combustion reactor

Abstract

The present invention relates to a combustion reactor (300) for chemical looping combustion (CLC), which is configured to operate in a fluidized bed, comprising: - a lower chamber (320), which forms a first reaction zone for burning hydrocarbon feedstock in the presence of redox active material particles, comprises a first side wall and is configured to include a dense fluidized bed; - an elongated upper chamber (340) with a channel cross-section smaller than the channel cross-section of the lower chamber, which forms a second reaction zone for burning gaseous effluents from the combustion in the lower part, comprises a second side wall and is configured to include a dilute phase fluidized bed; - an intermediate part (330), which connects the two chambers and comprises an inner wall forming a right angle with the side walls of the two chambers. The present invention also relates to a facility and a CLC method comprising the reactor (300).

Description

Technical Field

[0001] The present invention relates to the field of combustion of hydrocarbon feedstocks by chemical looping oxidation / reduction (CLC) operated as a fluidized bed, and more particularly to a CLC combustion reactor operated as a fluidized bed particularly suitable for the combustion of solid or liquid hydrocarbon feedstocks. Prior art

[0002] The chemical looping combustion (CLC) process is a process that involves an active substance (usually a metal oxide) undergoing oxidation / reduction reactions to divide the combustion reaction of a hydrocarbon feedstock into the following two consecutive reactions: in at least one oxidation zone, the active substance is contacted with an oxidizing gas (usually air) to undergo a first oxidation reaction; and in at least one combustion zone, the active substance is contacted with a feedstock to be burned to undergo a second reduction reaction.

[0003] The oxidation / reduction active substance releases part of the oxygen it contains when it comes into contact with the feedstock in the combustion zone and thus serves as an oxygen transporter between the combustion zone and the oxidation zone, where it is oxidized again.

[0004] The solid material is provided in the form of fluidizable particles belonging to the A, B or C class of the Geldart classification (based on the size of the particles and their density difference with the gas), and usually belongs to class B. The particles are contacted with the oxidizing gas or feedstock in the form of a fluidized bed in the reaction zone and are usually transported from one zone to another in a fluidized form. The body of particles transported in a fluidized form is usually called a circulating or transporting fluidized bed.

[0005] These particles are oxidized in contact with an oxidizing gas, usually air (or water vapor), in at least one first reaction zone, called an oxidation reactor or air reactor. They are then transported to at least one second reaction zone, called a reduction reactor or combustion reactor or fuel reactor, where they are contacted with a solid hydrocarbon feedstock (e.g., coal, coke, "pet-coke", biomass, oil sands, household waste), a liquid hydrocarbon feedstock (e.g., fuel oil, asphalt, diesel, gasoline, shale oil, etc.) or a gaseous hydrocarbon feedstock (e.g., natural gas, synthesis gas, biogas, shale gas) to be burned. The oxygen transported by the active material particles provides the combustion of the feedstock. This produces a gaseous effluent formed by the combustion of the feedstock and a reduced particle stream. The particles are returned to the air reactor to be reoxidized therein, thereby closing the loop.

[0006] By producing CO 2 The CLC process can generate energy (steam, electricity, etc.) by recovering the heat provided by the combustion reaction, while helping to capture the carbon dioxide (CO 2). This is because CO can be captured after steam condensation and flue gas compression. 2 , and can subsequently be stored, for example, in deep aquifers, or raised, for example, by using CO 2 To improve the productivity of oilfield operations during enhanced oil recovery (EOR) or enhanced gas recovery (EGR).

[0007] By controlling the combustion and carrying out the required purification downstream of the combustion process, the CLC process can also produce synthesis gas and even hydrogen.

[0008] Another advantage arises from this combustion mode: a stream is produced which is very rich in nitrogen, which is the depleted air obtained after the oxidation of the active substances in the air reactor. Depending on the purity obtained, this nitrogen stream can be boosted in various applications, in particular in the field of the oil industry. For example, it can be used in refineries as an inert gas in various refining processes, or for the treatment of production water, or as gas injected underground in EOR processes.

[0009] Different fluidization states can be used in different units of a CLC plant, in particular in the oxidation and reduction reactors operated as fluidized beds. This is because the fluidization state used depends on the operation to be carried out (combustion of feedstock, oxidation of oxygen carrier particles, transport of particles, solid / solid separation, solid / gas separation) and the type of feedstock to be processed.

[0010] For example, the combustion of a solid feedstock in the form of particles requires a longer contact time with the oxygen carrier particles than the combustion of a gaseous feedstock, which is generally reflected in the use of a zone comprising a dense fluidized bed in the combustion reactor, which operates according to a heterogeneous fluidization regime corresponding to a so-called boiling (bubbles in the bed) bed or a turbulent (preferred flow regime) bed, wherein the oxygen carrier particles and the solid feedstock particles are brought into contact to carry out a first combustion stage consisting mainly of the gasification of the solid feedstock. A second stage is generally required to move towards complete combustion, bringing the oxygen-carrying particles into contact with the gasified feedstock. This second stage is generally carried out in a first reaction zone, and can also be carried out in a second reaction zone comprising a dilute phase fluidized bed, which operates according to a transport fluidization scheme involving higher gas velocities (a scheme corresponding to a circulating fluidized bed). This reaction zone generally corresponds to a portion of the reactor forming a substantially elongated and vertical pipe, which is generally called a "riser", a term commonly used by those skilled in the art. This configuration comprises a first combustion zone as a dense fluidized bed, above which is a riser-type second combustion zone operating as a dense fluidized bed, as described, for example, in patent application WO11151535 relating to a CLC process dedicated to solid hydrocarbon feedstocks.

[0011] In the case of chemical looping combustion of gaseous feedstocks, a riser-type reactor may be sufficient for the combustion of the feedstock, since the required contact time between the feedstock and the particles of the reactive material is shorter than in the case of solid or liquid feedstocks.

[0012] Increasing the gas velocity in a fluidized bed generally produces different flow regimes. Depending on the Geldart classification to which the solid particles belong, different fluidization regimes can be achieved when the gas velocity is increased.

[0013] For example, for type B particles in Geldart's classification, as the gas flow rate gradually increases, the flow changes from a bubbling regime (ebullating bed, a type of dense bed) to a plug-flow regime (called slugging) (depending on the bed height and bed diameter), to a turbulent regime, to a fast fluidization regime (circulating bed), and then to a transport regime. Although at low gas velocities, the fluidization regime may vary depending on the particle group, regardless of which group it belongs to, when the gas velocity increases, it reaches a turbulent fluidization regime, then a fast fluidization regime, and then a transport regime.

[0014] When the diameter of the bubbles is comparable to the diameter of the column, the plug flow regime occurs: for type B particles, the bubbles grow as they rise in the reactor, and their size may potentially reach the limiting diameter of the reactor. In this case, the regime reached is the plug flow regime, resulting in a flow that acts as a "plug". Large bubbles burst on the surface or wall of the bed, entraining dense solid aggregates with their wake, creating violent flow inhomogeneities that manifest as violent pressure fluctuations and vibrations.

[0015] The turbulent regime is, for its part, particularly advantageous for industrial processes, since it presents a more uniform mixing of the phases and a very significant mass and heat transfer compared to the boiling and plug flow regimes. This is a regime corresponding to a violent agitation of the particles: with increasing fluidization speed, the size and number of the bubbles gradually increase, and the agitation of the suspension becomes increasingly violent. This agitation is caused by the fact that the bubbles rise and that they entrain part of the suspension in their wake. At high speeds, the shape of the bubbles becomes irregular. However, even if the large bubbles formed do not reach the reactor diameter, they can generate greatly fluctuating pressures and vibrations in the bed, on the surface of the bed and on the walls of the reactor, usually during their rupture in the bed.

[0016] Plug flow conditions and the formation of large bubbles are undesirable for several reasons: the mixing of solids and gases is poor (less uniform), the uniformity of the reactor temperature is no longer ensured, and the strong fluctuations in pressure and vibrations on the reactor walls and bottom are detrimental to the mechanical strength of the reactor.

[0017] In the case of a fluidized bed reactor connected via its upper part to an elongated pipe of smaller diameter (riser), such as the CLC reactor described above and in application WO11151535, the formation of large bubbles can prove to be more problematic, since dense aggregates of entrained solids can in turn lead to plug flow phenomena in the elongated pipe.

[0018] Devices for reducing the plug flow phenomenon are known. For example, patent US9512364 B2, which relates to a hydropyrolysis process for converting biomass in granular form into liquid fuels using a catalytic fluidized bed, discloses an anti-plug flow reactor comprising lateral inserts, which are disruptive, obstructive or constrictive elements placed at regular intervals in the bed to inhibit plug flow in the reactor. Such inserts are not always easy to use, and reactors of this type may require a lot of maintenance related to possible coking of the inserts.

[0019] The present invention proposes to provide another solution dedicated to CLC to reduce the problems associated with the plug flow phenomenon, in particular to limit the severe pressure fluctuations in the combustion reactor, especially in the elongated part of the reactor (riser).

[0020] OBJECTIVE AND SUMMARY OF THE INVENTION

[0021] The object of the present invention is to provide a CLC combustion reactor capable of limiting the adverse effects of the turbulent and plug flow fluidization schemes used in the reactor, in particular limiting the strong pressure fluctuations caused by the formation and collapse of large bubbles. The aim is therefore to maintain the mechanical strength of the combustion reactor, ensure temperature uniformity in the reactor, and ensure homogeneity of the gas / particle mixture in the reactor in order to achieve optimal combustion.

[0022] Therefore, in order to achieve at least one of the above objects and other objects, according to a first aspect, the present invention provides a combustion reactor for chemical looping combustion configured to operate as a fluidized bed, comprising:

[0023] - a lower chamber forming a first reaction zone for combusting a hydrocarbon feedstock in the presence of particles of an oxidation / reduction active substance, said lower chamber comprising a first side wall and configured to include a dense fluidized bed;

[0024] - an elongated upper chamber, the passage cross section of which is smaller than the passage cross section of the lower chamber, forming a second reaction zone for combustion of the gaseous effluent resulting from the combustion in the lower portion, the upper chamber comprising a second side wall and configured to include a dilute phase fluidized bed;

[0025] - an intermediate portion connecting the lower chamber to the upper chamber, the intermediate portion comprising an inner wall forming a right angle with the first side wall of the lower chamber and the second side wall of the upper chamber.

[0026] According to one embodiment, the lower chamber comprises a main injection system for the mainstreaming gas, which is located at the base of the lower chamber.

[0027] According to one embodiment, the lower chamber additionally comprises a second injection system for a second fluidizing gas, which is located at the top of the lower chamber.

[0028] According to one embodiment, the lower chamber further comprises a tertiary injection system for a tertiary fluidizing gas, located between the main injection system and the top of the lower chamber, configured to control the level / level / level height of the dense bed.

[0029] According to one embodiment, the upper part of the combustion reactor comprises a section penetrating into the lower part of the chamber at a height h preferably between 0.01 xH and 0.3 xH, H being the height of the lower chamber of the combustion reactor.

[0030] According to one embodiment, the ratio of the channel cross section of the lower chamber to the channel cross section of the upper chamber is 2 to 15, preferably 3 to 10.

[0031] According to one embodiment, the upper chamber and the lower chamber of the reactor have a parallelepiped shape, preferably a rectangular shape.

[0032] According to a second aspect, the present invention provides an apparatus for chemical looping combustion of hydrocarbon feedstocks using oxidation / reduction active material particles circulating between a combustion reactor and an oxidation reactor, the apparatus comprising:

[0033] - a combustion reactor according to the present invention, which is operated as a fluidized bed so that the hydrocarbon feedstock is combusted in contact with the oxidation / reduction active material particles;

[0034] - An oxidation reactor operated as a fluidized bed, wherein the reduced oxidation / reduction active material particles originating from the combustion reactor are brought into contact with an oxidizing gas to oxidize the reduced oxidation / reduction active material particles.

[0035] According to a third aspect, the invention proposes a method for chemical looping combustion of a hydrocarbon feedstock using a combustion reactor according to the invention or an apparatus according to the invention, said method comprising the following stages:

[0036] - contacting the hydrocarbon feedstock in the lower chamber of the combustion reactor with the particles of the oxidation / reduction active substance in a dense fluidized bed formed by injecting a mainstream fluidizing gas;

[0037] - In the upper chamber of the combustion reactor, in a dilute fluidized bed, the gaseous effluent from the lower chamber is combusted in the presence of particles of an oxidation / reduction active substance;

[0038] The oxidation / reduction active material particles remaining in the combustion reactor are oxidized in an oxidation reactor operated as a fluidized bed and then returned to the combustion reactor.

[0039] According to one embodiment, the hydrocarbon feedstock is a solid feedstock, preferably selected from coal, coke, petroleum coke, biomass, oil sands and domestic waste.

[0040] According to one embodiment, unburned residue particles and oxidation / reduction active substance particles contained in a gas mixture containing combustion gas generated by an upper chamber of a combustion reactor can be separated in a solid / solid particle separator; the oxidation / reduction active substance particles thus separated are sent to an oxidation reactor, and the unburned residue particles (optionally separated from the combustion gas in at least one gas / solid separation stage) are recycled in the combustion reactor.

[0041] According to one embodiment, the superficial velocity of the gas in the lower chamber of the combustion reactor is 0.3 m / s to 3 m / s, wherein the superficial velocity of the gas in the upper chamber of the combustion reactor is 3 m / s to 15 m / s.

[0042] According to one embodiment, the temperature in the combustion reactor is from 600°C to 1400°C, preferably from 800°C to 1000°C.

[0043] According to one embodiment, the second fluidizing gas is injected at the top of the lower chamber of the combustion reactor, preferably forming a jet in a direction forming an angle β of 0° to 90° with the vertical direction.

[0044] Preferably, the flow rate of the second fluidizing gas is 0.02xQ MG To 0.2xQ MG , Q MG is the flow rate of the mainstream normalizing gas.

[0045] According to one embodiment, the third fluidizing gas is injected into the dense bed zone in the lower chamber of the combustion reactor to control the level / level / level height of the dense bed.

[0046] According to one embodiment, the oxidation / reduction active material particles belong to class B according to the Geldart classification.

[0047] Other objects and advantages of the invention will become apparent on reading the following description of particular exemplary embodiments of the invention, given by way of non-limiting example, which description is made with reference to the accompanying drawings described below.

[0048] List of Figures

[0049] Figure 1 It is the implementation block diagram of the CLC process.

[0050] FIG. 2 shows a CLC combustion reactor according to the prior art.

[0051] Figure 3 A CLC combustion reactor according to a first embodiment of the present invention is shown.

[0052] Figure 4 A CLC combustion reactor according to a second embodiment of the present invention is shown.

[0053] In the drawings, the same reference numerals refer to the same or similar elements.

[0054] Description of Embodiments

[0055] The object of the present invention is to propose a combustion reactor for chemical looping combustion having a specific geometry suitable for the combustion of solid or liquid hydrocarbon feedstocks, preferably solid feedstocks, so as to make it possible to limit the strong pressure fluctuations associated with the plug flow phenomena and the presence of large bubbles encountered when setting the fluidized bed in a turbulent state.

[0056] Before describing the combustion reactor according to the present invention in more detail, Figure 1 A CLC process and apparatus using such a reactor is described.

[0057] In this specification, the expressions "oxidation / reduction active material" or the abbreviated forms "active material", "oxygen transport material", "solid oxygen carrier", and "oxygen carrier" are synonymous. An oxidation / reduction material is said to be active in relation to its reactivity, in the sense that it is capable of acting as an oxygen transporter in a CLC process by capturing and releasing oxygen.

[0058] It should be noted that, in general, the terms "oxidation" and "reduction" are used with respect to the oxidized state or reduced state, respectively, of the active material. The oxidation reactor is also called an air reactor, in which the oxidizing / reducing material is oxidized, and the reduction reactor is also called a fuel reactor, in which the oxidizing / reducing material is reduced. The reactor is operated as a fluidized bed, and the active material circulates between the oxidation reactor and the reduction reactor. The use of circulating fluidized bed technology enables the active material to be continuously transferred from the oxidized state in the oxidation reactor to the reduced state in the reduction reactor.

[0059] CLC method and apparatus according to the present invention

[0060] Figure 1 is a diagram showing the general operating principle of chemical looping combustion. It does not limit in any way the CLC method and apparatus combined with the combustion reactor according to the present invention.

[0061] The reduced oxygen carriers 15 are brought into contact with the air stream 10 in a reaction zone 110, defined as an oxidation reactor (or air reactor) as above. This produces a depleted air stream 11 and a reoxidized particle stream 14. The oxidized oxygen carrier particle stream 14 is conveyed to a reduction zone 100, defined as a fuel reactor (or reduction reactor) as above. The particle stream 14 is brought into contact with a fuel 12, which is a hydrocarbon feedstock. This produces a combustion effluent 13 and a reduced oxygen carrier particle stream 15. For simplicity, Figure 1 The illustration does not include the various equipment items that may form part of a CLC unit for solid / gas separation, solid / solid separation, heat exchange, pressurization, gas tightness between reactors (e.g., siphons), solids storage, control of solids flow (e.g., mechanical or pneumatic valves), or any recycling of material around the oxidation and combustion reactors.

[0062] In the combustion zone 100, the hydrocarbon feedstock 12 is contacted in co-current flow with an oxidation / reduction active material in particulate form to combust the feedstock by reduction of the oxidation / reduction active material.

[0063] According to the following reaction (1), the oxidation / reduction active substance M x O y (M stands for metal) using C n H m Hydrocarbon feedstock is reduced to M x O y-2n-m / 2 state, and C n H m The hydrocarbon feedstock is oxidized accordingly to provide CO according to the ratio used. 2 and H 2 O, or optionally CO + H 2 mixture.

[0064] C n H m +M x O y →nCO 2 +m / 2H 2 O+M x O y-2n-m / 2

[0065] Complete combustion of the hydrocarbon feedstock is generally aimed at.

[0066] The raw material contacted with the active substance is burned at a temperature of generally 600° C. to 1400° C., preferably 800° C. to 1000° C. The contact time varies depending on the type of combustible raw material used. For solid or liquid raw materials, the contact time generally varies between 1 second and 20 minutes, for example, preferably between 1 minute and 10 minutes, and, more preferably, between 1 minute and 8 minutes, and for example, for gaseous raw materials, the contact time is preferably 1 second to 20 seconds.

[0067] A mixture including gases produced by combustion and active material particles is discharged from the top of the reduction zone 100. A gas / solid separation device (not shown) (e.g., a cyclone) can be used to separate the combustion gas 13 from the active material solid particles 15 in the maximum reduced state. In the case where unburned residues may occur when the hydrocarbon feedstock is solid, a solid / solid separation device capable of separating the unburned residue particles from the active material particles can be used at the outlet of the combustion reactor. This type of separator can be combined with one or more gas / solid separators arranged downstream of the solid / solid separator. The active material particles remaining in the combustion reactor and separated from the combustion gas are sent to the oxidation zone 110 for reoxidation. The unburned residue can be recycled to the reduction reactor 100.

[0068] In the oxidation reactor 110, before returning to the reduction reactor 100, and after having been separated from the oxygen-depleted gas 11 (usually "depleted" air) discharged from the top of the oxidation reactor 110, the active material contacts the oxidizing gas 10 (usually air or water vapor) to restore its M according to the following reaction (2): x O y Oxidation state.

[0069] M x O y-2n-m / 2 +(n+m / 4)O 2 →M x O y

[0070] Here, n and m represent the number of carbon atoms and hydrogen atoms, respectively, that react with the active species in the combustion reactor.

[0071] The temperature in the oxidation reactor is generally from 600°C to 1400°C, preferably from 800°C to 1000°C.

[0072] The active species describes a redox cycle, alternately converting from its oxidized form to its reduced form and vice versa.

[0073] The processed hydrocarbon feedstock (or fuel) can be a solid or liquid hydrocarbon feedstock. The solid feedstock can be selected from coal, coke, petroleum coke, biomass, tar sands and domestic waste. The liquid feedstock can be selected from: petroleum, asphalt, diesel or gasoline. Preferably, the processed hydrocarbon feedstock is a solid feedstock, as described above.

[0074] The oxidizing / reducing material may comprise a metal oxide, for example, an oxide of Fe, Ti, Ni, Cu, Mn, Co, or V, used alone or as a mixture, which is derived from minerals (e.g., ilmenite or pyrolusite) or is synthetic (e.g., copper oxide particles supported on alumina CuO / Al 2 O 3 , or nickel oxide particles supported on alumina NiO / NiAl 2 O 4 , preferably copper oxide particles CuO / Al supported on alumina 2 O 3 ), with or without a binder, and exhibiting the desired oxidation / reduction properties and the characteristics required for fluidization. The oxygen storage capacity of the oxidation / reduction material is advantageously between 0.5% and 15% by weight, depending on the type of material. Advantageously, the amount of oxygen effectively transported by the metal oxide is between 0.5 and 3% by weight, and only a portion of the total oxygen transport capacity can be used, ideally less than 30% of the total oxygen transport capacity, in order to limit the risks of mechanical aging or agglomeration of the particles. Using only a portion of the oxygen transport capacity also has the advantage that the fluidized bed acts as a thermal ballast, thereby smoothing temperature variations on the path of the oxygen carriers.

[0075] The active substance is in the form of fluidizable particles, which belong, alone or in combination, to class A, B, C or D of the Geldart classification. Preferably, the oxidation / reduction active substance particles belong to class B of the Geldart classification. By way of example, and in a non-limiting manner, the class B particles used exhibit a particle size such that more than 90% of the particles have a size of 100 μm to 500 μm, preferably 150 μm to 300 μm.

[0076] Preferably, the density of the redox active material particles (which may be metal oxides, synthetic or natural ores, supported or unsupported) is 1000 kg / m 3 Up to 5000kg / m 3 , preferably 1200kg / m 3 Up to 4000kg / m 3 .

[0077] For example, nickel oxide particles supported on alumina (NiO / NiAl 2 O4 ) particle density is usually 2500kg / m 3 Up to 3500kg / m 3 , usually about 3200kg / m 3 .

[0078] Ilmenite is an ore composed of titanium and iron (titanium iron oxide) with a density of 4700 kg / m 3 .

[0079] The oxidation / reduction active substances may be subjected to an activation phase in order to increase their reactivity, which activation phase may consist of a temperature increase phase, preferably a gradual temperature increase phase, and preferably is carried out in an oxidizing atmosphere (for example air).

[0080] The oxidation reactor and the combustion reactor are operated as fluidized beds. They each contain at least one system for injecting a fluidizing gas. In the combustion reactor, the fluidizing gas may be CO 2 (It can be CO produced during combustion and circulation 2 ) or water vapor. In the oxidation reactor, the fluidizing gas is an oxidizing gas, preferably air.

[0081] The oxidation reactor preferably comprises a transport fluidized bed. Advantageously, the gas (gas phase of the bed) velocity is from 2 m / s to 15 m / s, preferably from 3 m / s to 10 m / s. For example, the reactor has a diameter of from 1 m to 6 m and a height of from 10 m to 30 m.

[0082] The combustion reactor 100 is configured to include a dense bed and a conveying bed. Specifically, the combustion reactor 100 includes a lower chamber below the upper chamber, the lower chamber includes a dense fluidized bed, and the upper chamber includes a conveying fluidized bed. The channel cross section of the upper chamber is smaller than the channel cross section of the lower chamber, and the gas / particle mixture discharged from the lower chamber can be accelerated and conveyed. Preferably, the gas velocity of the lower chamber is 0.3 m / s to 3 m / s. Advantageously, the gas velocity in the upper chamber of the combustion reactor is 3m / s to 15m / s.

[0083] For example, the combustion reactor 100 may have a diameter of 1 meter to 10 meters and a height of 3 meters to 40 meters.

[0084] Preferably, the cross-sectional ratio of the lower chamber to the upper chamber is 2 to 15, preferably 3 to 10.

[0085] A dense fluidized bed is understood to mean an ebullating bed or a turbulent bed. In the dense fluidized bed, the solid volume fraction is generally between 0.25 and 0.50.

[0086] A dilute fluidized bed is understood to mean a transport bed. The volume fraction of solids is usually less than 0.25.

[0087] The geometry of the reactor may be parallelepipedal, cylindrical or any other three-dimensional geometry which preferably comprises rotational symmetry. Cylindrical means a cylinder of rotation.

[0088] Advantageously, the combustion reactor, in particular the upper chamber and the lower chamber, has a parallelepiped shape, preferably a rectangular shape. In particular, the upper chamber and the lower chamber of the combustion reactor have such a shape. This reactor shape is very suitable for the industrial implementation of CLC (including large-scale equipment projects). "Large-scale" is understood to mean a reactor whose channel cross-section is measured in tens of square meters (m 2 ) and tens of meters (m) in height. For example, the scale-up of CLC devices can be promoted by replicating the reactor in one dimension to increase its capacity. In addition, this specific geometry also has the advantage of simplifying the possible installation of refractory materials on the inner surface so as to protect the reactor chamber wall (usually a metal wall) from high temperatures. For the purpose of limiting manufacturing costs, the refractory material can be used in combination with standard steel. For example, a reinforced refractory cement layer (whose thickness is generally 2 to 50 cm, generally close to 20 cm) on the inner surface exposed to flow and high temperature makes it possible to use standard steel for the outer part of the reactor. Bricks can also be used as refractory materials on the inner surface of the reactor chamber wall.

[0089] The materials used to construct the reactor and its constituent elements (inlet, discharge point, outlet, etc.) can be selected from: refractory materials (for example, refractory concrete, refractory bricks or ceramic types), high temperature steels (for example or type), or conventional steel (e.g. stainless steel or carbon steel type combined with refractory materials or cooling devices), for example, pipes in which a heat exchange fluid circulates

[0090] In the combustion reactor, the lower chamber comprises a dense fluidized bed and the upper chamber comprises a transport fluidized bed. This geometry is very suitable for the combustion of solid or liquid raw materials, especially solid raw materials, which need to be in contact with the particles of the active substance for a long enough time to tend to complete combustion, and involves a first stage of gasification of the solid or liquid raw materials (as in the dense fluidized bed), followed by combustion of the gasified raw materials (as in the dense fluidized bed and the transport fluidized bed). The gasification of the raw materials helps to increase the velocity of the gas in the lower chamber, where the channel cross section is substantially constant. This increase in gas velocity is also caused by the narrowing of the channel interface in the upper chamber.

[0091] In the lower chamber of the combustion reactor, as the gas velocity increases, a transition is made from a heterogeneous state (resulting in a boiling bed constituting a dense bed in the lower chamber) to a turbulent state to achieve a transport state in the upper chamber.

[0092] During the state change in the lower chamber, the size of the bubbles may become very large until it approaches the size of the cross-section of the lower chamber channel, which is characterized by a plug-flow phenomenon during the transient plug-flow state between the boiling bed state and the turbulent state, and causes pressure fluctuations, vibrations, temperature non-uniformity and solid / gas mixing problems, which are detrimental to the integrity of the CLC equipment and the performance quality of the CLC process as described above.

[0093] A known combustion reactor 1 is schematically shown in FIG2 . This combustion reactor is described, for example, in the application WO11151535. It comprises a lower chamber 2 comprising a dense bed and an upper chamber 4 comprising a dilute bed. The upper chamber 4 has an elongated shape and its channel cross section is strictly smaller than that of the lower chamber, for example at least 25%, in fact even at least 50%. The upper chamber 4 is a riser. The change in cross section makes it possible to increase the velocity between the lower chamber 2 and the upper chamber 4 and to ensure the transition between the dense phase flow and the dilute phase flow.

[0094] Thus, the lower chamber 2 comprises: a feed conduit for hydrocarbon feedstock; a conduit for feeding the active material particles produced by the oxidation reactor; a system for injecting fluidizing gas, which is located at the base of the chamber 2, at a level lower than the feed conduit for hydrocarbon feedstock and active material particles, and which can form a dense bed. For example, the fluidizing gas is introduced through a specific device, which can be a perforated plate arranged downstream of a distributor, which can be a wind box fed through the conduit for feeding said gas. These plates can be inclined at an angle of generally 30° to 70° relative to the horizontal plane, and space can be left in the central part for the flow of particles, so that a part of the particles deposited in this area and mainly composed of aggregated ash can be extracted through the distributor.

[0095] The lower chamber 2 may also include one or more pipes for recovering unburned residue particles, which are connected to a solid / solid separation system (a device for separation by elutriation) and / or a gas / solid separation system (eg, a cyclone separator).

[0096] For simplicity, not all of these components are shown in FIG. 2 .

[0097] The upper chamber 4 comprises at its top a discharge point for the gas mixture comprising combustion gases and particles of active substance and possibly particles of ash and unburned residues. The upper chamber 4 may also comprise means for feeding particles of active substance.

[0098] In the upper chamber 4, the gaseous effluent from the lower chamber 2 can be burned. The gaseous effluent includes partially converted, or even completely converted, gasified solid feedstock. With regard to the gas velocity, the average residence time of the gas in the upper chamber 4 is generally between 1 and 20 seconds, and the average residence time of the solid varies between 2 seconds and 1 minute. Under these conditions, and in view of the dilute phase release nature of the flow and the presence of the oxygen active material particles, the reaction is essentially a reaction between the gas phase (gasified feedstock) and the active material particles.

[0099] According to the known reactor 1, a duct 3 of variable cross-section can be connected between the lower chamber 2 and the upper chamber 4 and can discharge the gaseous effluent and the entrained particles to the upper chamber 4. For example, in the case of a cylindrically shaped chamber, the duct is a cone 3. The walls of the cone 3 form a non-zero angle α with the walls of the lower and upper chambers (i.e. with the vertical).

[0100] In this configuration, bubbles entrained by solid aggregates slide over the conical wall 3, gather at the entrance of the upper chamber 4, and then cause violent pressure fluctuations when they break. Solid (or solid particle) aggregates should be understood to refer to particles that slightly aggregate to form larger size clusters. These clusters can be entrained by bubbles. Entraining aggregates into the upper chamber produces uneven flow and also produces pressure fluctuations in the upper chamber 4. Ultimately, entraining solid particle aggregates into the upper chamber 4 is harmful because these particles in turn produce plug flow in the upper chamber 4, which is a phenomenon that is more likely to occur as the cross section decreases.

[0101] Combustion reactor according to the invention

[0102] In order to reduce these strong pressure fluctuations in the combustion reactor, especially in the upper chamber, a new combustion reactor is proposed.

[0103] Figure 3 and Figure 4 Two main embodiments of the combustion reactor of the invention are shown schematically in a non-limiting manner. In the figures, the same reference numerals indicate the same or similar elements.

[0104] See also Figure 3 The combustion reactor 300 according to the present invention is configured to operate in a fluidized bed mode. It includes:

[0105] - a lower chamber 320 forming a first reaction zone for burning hydrocarbon feedstock in the presence of oxidation / reduction active material particles, the lower chamber 320 comprising a first side wall and configured to include a dense fluidized bed;

[0106] an elongated upper chamber 340 (riser) having a smaller channel cross section than the lower chamber 320, forming a second reaction zone for the combustion of the gaseous effluent resulting from the combustion in the lower part 320, the upper chamber 340 comprising a second side wall and configured to include a dilute fluidized bed;

[0107] A middle portion 330 connecting the lower chamber 320 to the upper chamber 340 , the middle portion 330 comprising an inner wall forming a right angle with a first side wall of the lower chamber 320 and a second side wall of the upper chamber 340 .

[0108] This middle portion forms a flat ceiling of the lower chamber 320 in a certain manner.

[0109] The steep restriction of the channel cross section between the lower chamber 320 and the upper chamber 340 is imposed by the specific right-angle geometry of the intermediate portion 330 forming the connection between the two chambers in the combustion reactor, making it possible to break up solid particle aggregates before they enter the upper chamber 340, preventing the solid particle aggregates from being entrained into the riser with a smaller cross-section, thereby limiting pressure fluctuations.

[0110] The inner wall of the middle portion 330 is understood to mean the surface forming the wall of the middle portion 330 located inside the chamber 320 and in contact with the fluidized bed.

[0111] According to an alternative embodiment, the intermediate portion 330 comprises an outer wall, i.e. a surface forming a wall of the intermediate portion 330 located outside the chamber 320, which is slightly curved to help the refractory material anchor. The curvature may have an elliptical shape and its semi-axis ratio (ratio of major axis to minor axis) is preferably 2 to 30, and more preferably 5 to 20. The shape of the outer wall may have different shapes, for example those described in the normative document NFE81-100 for dished ends. Examples of refractory materials have been described above in conjunction with Figure 1 A description of the CLC process and apparatus shown is given. According to this alternative form, the flat top of the lower chamber in the reactor [i.e., the right angle at the junction between the side wall of the lower chamber 320 and the side wall of the upper chamber 340 in the reactor (the inner wall of the middle part 330)] is preserved intact.

[0112] The combustion reactor according to the invention may comprise: other elements similar to those described above for the combustion reactor 1 according to the prior art, which are not Figure 3 Displayed in.

[0113] Thus, the lower chamber 320 advantageously comprises:

[0114] - a feed pipeline for hydrocarbon feedstock;

[0115] - a conduit for feeding the active material particles produced by the oxidation reactor;

[0116] - A main injection system for the mainstream fluidizing gas, located at the base of the chamber. This main injection system is preferably located at a lower level than the feed pipes for the hydrocarbon feedstock and the active substance particles, and a dense bed can be formed. For the lower chamber 2 of the reactor of the prior art according to Figure 2, the fluidizing gas is introduced through a specific device, which can be a perforated plate arranged downstream of a distributor, and the distributor can be a bellows fed through a pipe for feeding the gas. These plates can be inclined at an angle of generally 30° to 70° relative to the horizontal plane, and space can be left in the central part for the flow of particles, so that a part of the particles deposited in this area and mainly composed of aggregated ash can be extracted through the distributor.

[0117] The lower chamber 320 may further include one or more pipes for recovering unburned residue particles, which are connected to a solid / solid separation system (a device for separation by elutriation) and / or a gas / solid separation system (eg, a cyclone separator).

[0118] The upper chamber 340 advantageously comprises at its top a discharge point for the gas mixture comprising combustion gases and particles of the active substance and possibly particles of ash and unburned residues.

[0119] The upper chamber 340 may also include a device for feeding active material particles.

[0120] For the reactor upper chamber 4 of the prior art according to Fig. 2, the channel cross section of the upper chamber 340 can be at least 25% smaller, in fact even at least 50% smaller, than the channel cross section of the lower chamber 320. The passage of reduced cross section from the cross section of the lower chamber 320 to the upper chamber 340 can increase the flow velocity between the two chambers and ensure the transition between the dense phase flow and the dilute phase flow.

[0121] In the upper chamber 340, the gaseous effluent from the lower chamber 320 can be burned. The gaseous effluent includes partially converted or even completely converted gasified solid feedstock. Taking into account the gas velocity, the average residence time of the gas in the upper chamber is generally 1 second to 20 seconds, and the average residence time of the solid varies between 2 seconds and 1 minute. Under these conditions, and given the dilute nature of the flow and the presence of oxygen reactive material particles, the reaction is essentially a reaction between the gas phase (gasified feedstock) and the reactive material particles.

[0122] Preferably, the upper chamber comprises a dilute phase fluidized bed having a solid volume fraction of less than 0.10.

[0123] According to one alternative, the lower chamber 320 additionally comprises a second injection system for a second fluidizing gas, which is situated at the top of the lower chamber 320 .

[0124] According to this alternative, the second fluidizing gas can be injected into the top of the lower chamber 320 of the combustion reactor 300, and preferably forms at least one jet in a direction forming an angle β of 0° to 90° with the vertical direction. Thus, horizontal gas injection 352 (angle β equal to 90°) or vertical gas injection 351 (angle β equal to 0°) can be performed, or gas injection can be performed according to an angle β between these two values ​​(excluding the extreme values), or gas injection can be performed according to a combination of these different directions.

[0125] These additional gas injections at the top of the upper chamber 320 may further reduce pressure fluctuations by breaking up large solids aggregates before they reach the upper chamber 340 .

[0126] Advantageously, the flow rate of the second fluidizing gas is less than 0.02xQ MG , Q MG is the flow rate of the main fluidizing gas. Preferably, the flow rate of the second fluidizing gas is 0.02xQ MG To 0.2xQ MG , more preferably 0.05xQ MG To 0.15xQ MG .

[0127] According to one alternative, the lower chamber additionally comprises a tertiary injection system (not shown) for a tertiary fluidizing gas, located between the main injection system and the top of the lower chamber, configured to control the level / level / level height of the dense bed.

[0128] Therefore, the third fluidizing gas is injected into the dense bed zone in the lower chamber of the combustion reactor to control the level / horizontal plane / horizontal plane height of the dense bed, and the entrainment amount of solid particles is varied. In this way, the distance between the bed surface and the entrance of the upper chamber 340 can be increased, that is, it has a larger disengagement zone height, which is conducive to breaking up solid aggregates before the solid particles enter the upper zone of the lower section. Recall that the disengagement zone is the dilute phase zone above the dense bed (between the interface of the dense bed and the top of the chamber).

[0129] According to this alternative form, the injection can be performed to form at least one jet in the chamber along a direction forming an angle of 90° (including end values ​​(horizontal direction)) to 180° (excluding end values) relative to the vertical direction. Jets can also be generated along multiple directions in these directions.

[0130] The mainstream gas can be CO 2 (For example, CO generated during combustion and circulation 2 ) or water vapor. The additional, second and third fluidizing gases may be of the same nature and originate from the same source as the mainstream fluidizing gas.

[0131] A combustion reactor 400 according to a second embodiment of the present invention is shown in FIG. Figure 4 and all aspects combined with the above Figure 3 The reactor 300 described is identical, except for the upper chamber 440 which comprises a penetration section 441 in the lower part of the chamber of a height h preferably 0.01 xH to ​​0.3 xH, H being the height of the lower chamber 320 of the combustion reactor.

[0132] As a non-limiting example, the height H of the lower chamber 320 may be 3 meters to 40 meters, for example, 20 meters.

[0133] Likewise, as a non-limiting example, the height H of the upper chamber 440 may be 3 meters to 40 meters, such as 20 meters.

[0134] The ratio of the channel cross section of the lower chamber to the channel cross section of the upper chamber can be 2 to 15, preferably 3 to 10.

[0135] The same is true for the sizes of the upper chamber 340 and the lower chamber 320 of the reactor 300 according to the first embodiment.

[0136] The present invention also relates to a CLC device, comprising: a combustion reactor according to the present invention as described above, which operates as a fluidized bed to contact the hydrocarbon feedstock with oxidation / reduction active material particles for combustion, and an oxidation reactor operating as a fluidized bed to oxidize by contacting the reduced oxidation / reduction active material particles from the combustion reactor with an oxidizing gas. Detailed information of the device is provided in Figure 1 Given in.

[0137] The present invention also relates to a CLC process using the combustion reactor of the present invention as described above, thus mainly comprising the following stages:

[0138] - contacting the hydrocarbon feedstock in the lower chamber of the combustion reactor with the oxidation / reduction active material particles in a dense phase fluidized bed formed by injecting a mainstream fluidizing gas;

[0139] - In the upper chamber of the combustion reactor, in a dilute fluidized bed, the gaseous effluent from the lower chamber is combusted in the presence of particles of an oxidation / reduction active substance;

[0140] The oxidation / reduction active material particles remaining in the combustion reactor are oxidized in an oxidation reactor operated as a fluidized bed and then returned to the combustion reactor.

[0141] The gaseous effluent from the lower chamber includes the gasified solid raw material, as well as the effluent from the combustion carried out in the lower chamber. The upper chamber of the combustion reactor also receives the active material particles produced by the lower part, as well as possible unburned residue particles and possible fly ash, especially in the case of solid raw material combustion. Unburned residue particles are understood to mean solid hydrocarbon raw material particles that have not undergone complete combustion and therefore still contain hydrocarbon compounds. Ash is formed by incombustible components, which are produced by the complete combustion of solid fuel particles that stay in the combustion reactor for a sufficient time. Ash is mainly inorganic in nature. It generally includes the following compounds: SiO 2 、Al 2 O 3 , Fe 2 O 3 , CaO, MgO, TiO 2 , K 2 O、Na 2 O、SO 3 , P 2 O 5 It is characterized by a smaller particle size and density than the active material particles (ie, less than 100 μm) and is usually also smaller than the unburned residue particles.

[0142] Before being fed into the oxidation reactor for oxidation, the particles of the oxidation / reduction active substance remaining in the combustion reactor are separated from the combustion gases by at least one solid / solid separator and / or solid / gas separator. Such separators are described, for example, in patent applications WO11151535 and WO11151537. A solid / solid separator is understood to be a device that can separate the following two solid particle groups: oxygen carrier particles and unburned residue particles discharged from the combustion reactor.

[0143] Therefore, in the solid / solid particle separator, unburned residue particles and oxidation / reduction active substance particles contained in the gas mixture containing the combustion gas generated by the upper chamber of the combustion reactor can be separated; the oxidation / reduction active substance particles thus separated are sent to the oxidation reactor, and the unburned residue particles (optionally separated from the combustion gas in at least one gas / solid separation stage) can be recycled in the combustion reactor.

[0144] Other details of the CLC method have been incorporated above. Figure 1 is given in the description section.

Claims

1. A combustion reactor (100, 300, 400) for chemical looping combustion (CLC), configured to operate as a fluidized bed, the combustion reactor comprising: - a lower chamber (320) forming a first reaction zone for burning a hydrocarbon feedstock in the presence of particles of an oxidation / reduction active substance, said lower chamber (320) comprising a first side wall and configured to include a dense fluidized bed; - an elongated upper chamber (340, 440) having a channel cross section smaller than that of the lower chamber (320), forming a second reaction zone for burning gaseous effluents generated by combustion in the lower chamber (320), the upper chamber (340, 440) comprising a second side wall and configured to include a dilute phase fluidized bed; - an intermediate portion (330) connecting the lower chamber (320) to the upper chamber (340, 440), the intermediate portion (330) comprising an inner wall forming a right angle with a first side wall of the lower chamber (320) and a second side wall of the upper chamber (340, 440).

2. The reactor according to claim 1, wherein The lower chamber (320) includes a main injection system for the mainstreaming gas, which is located at the base of the lower chamber.

3. The reactor according to claim 2, wherein The lower chamber (320) further comprises a second injection system (350) for a second fluidizing gas, which is located at the top of the lower chamber.

4. The reactor according to claim 2 or 3, wherein The lower chamber (320) further comprises a third injection system for a third fluidizing gas, located between the main injection system and the top of the lower chamber, configured to control the level of the dense bed.

5. The reactor according to claim 1, wherein The upper portion (440) of the combustion reactor includes a section (441) penetrating into the lower chamber (320) of the chamber.

6. The reactor according to claim 5, wherein The upper part (440) of the combustion reactor comprises a section (441) penetrating into the lower chamber (320) of the chamber at a height h of 0.01 xH to ​​0.3 xH, H being the height of the lower chamber (320) of the combustion reactor.

7. The reactor according to claim 1, wherein The ratio of the channel cross section of the lower chamber (320) to the channel cross section of the upper chamber (340, 440) is 2 to 15.

8. The reactor according to claim 1, wherein The ratio of the channel cross section of the lower chamber (320) to the channel cross section of the upper chamber (340, 440) is 3 to 10.

9. The reactor according to claim 1, wherein The lower chamber (320) and the upper chamber (340, 440) of the reactor have a parallelepiped shape.

10. The reactor according to claim 1, wherein The lower chamber (320) and the upper chamber (340, 440) of the reactor have a rectangular shape.

11. An apparatus for chemical looping combustion of hydrocarbon feedstock, using oxidation / reduction active material particles circulating between a combustion reactor (100) and an oxidation reactor (110), the apparatus comprising: - A combustion reactor (300, 400) according to any one of claims 1 to 10, which is operated as a fluidized bed to allow the hydrocarbon feedstock to contact with the oxidation / reduction active material particles for combustion; - an oxidation reactor (110) operated as a fluidized bed, oxidizing the reduced oxidation / reduction active material particles from the combustion reactor (100, 300, 400) by bringing the reduced oxidation / reduction active material particles into contact with an oxidizing gas.

12. A method for chemical looping combustion of a hydrocarbon feedstock using a combustion reactor (100, 300, 400) as claimed in any one of claims 1 to 10 or an apparatus as claimed in claim 11, the method comprising the following stages: - contacting the hydrocarbon feedstock in the lower chamber (320) of the combustion reactor (100, 300, 400) with the oxidation / reduction active material particles in a dense fluidized bed formed by injecting a mainstream fluidizing gas; - In the upper chamber (340, 440) of the combustion reactor, in a dilute fluidized bed, the gaseous effluent from the lower chamber (320) is combusted in the presence of particles of an oxidation / reduction active substance; - The oxidation / reduction active material particles remaining in the combustion reactor (100, 300, 400) are oxidized in the oxidation reactor (110) operated as a fluidized bed and then returned to the combustion reactor (100, 300, 400).

13. The method of claim 12, wherein: The hydrocarbon feedstock is a solid feedstock.

14. The method of claim 13, wherein: The hydrocarbon feedstock is selected from the group consisting of coal, coke, petroleum coke, biomass, oil sands and domestic waste.

15. The method according to claim 13 or 14, wherein: Unburned residue particles and oxidation / reduction active material particles contained in a gas mixture containing combustion gas generated by an upper chamber (340, 440) of a combustion reactor (100, 300, 400) are separated in a solid / solid particle separator; the oxidation / reduction active material particles thus separated are sent to an oxidation reactor (110), and the unburned residue particles are recycled in the combustion reactor (100, 300, 400), and the unburned residue particles are optionally separated from the combustion gas in at least one gas / solid separation stage.

16. The method of claim 12, wherein: The superficial velocity of the gas in the lower chamber (320) of the combustion reactor is 0.3 m / s to 3 m / s, wherein the superficial velocity of the gas in the upper chamber (340, 440) of the combustion reactor is 3 m / s to 15 m / s.

17. The method of claim 12, wherein: The temperature in the combustion reactor (100, 300, 400) is 600°C to 1400°C.

18. The method of claim 12, wherein: The temperature in the combustion reactor (100, 300, 400) is 800°C to 1000°C.

19. The method of claim 12, wherein: The second fluidizing gas is injected at the top of the lower chamber (320) of the combustion reactor.

20. The method of claim 19, wherein: The second fluidizing gas is injected at the top of the lower chamber (320) of the combustion reactor to form jets (351, 352, 353) in a direction forming an angle β of 0° to 90° with the vertical direction.

21. The method of claim 19, wherein: The flow rate of the second fluidizing gas is 0.02xQ MG To 0.2xQ MG , Q MG is the flow rate of the mainstream normalizing gas.

22. The method of claim 12, wherein: The third fluidizing gas is injected into the dense bed region in the lower chamber (320) of the combustion reactor (100, 300, 400) to control the level of the dense bed.

23. The method of claim 12, wherein: According to the Geldart classification, particles of redox-active substances belong to class B.

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