Gasification plant and use thereof

Abstract

One aspect of the invention relates to a gasification system comprising a fuel injection (5) comprising at least one fuel injection point (11) arranged above a primary air injection inlet (4), the primary air injection inlet (4) being arranged such that a gasification air flow (F1) is injected into the reactor (2) in a direction substantially tangential to the wall (3) of the reactor (2), the wall (3) comprising a substantially cylindrical upper portion (6) and a substantially frustoconical lower portion (7), the primary air injection (4) and the fuel injection point (11) being provided through the lower portion (7) of the wall (3).

Description

GASIFICATION SYSTEM TECHNICAL FIELD OF THE INVENTION

[0001] The invention relates to the general technical field of heat generation installations for industrial processes, and more specifically to solid fuel gasification installations, in particular in cement processes. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0002] Gasifiers are conventionally used to produce combustible gases from solid fuels, typically plant biomass, coal, or alternative solid fuels that can be used to recover combustible waste. Organic matter is converted into gas during a pyrolysis process, by heating the solid fuel in the presence of a small amount of oxygen and water vapor, depending on the type of fuel being converted. Long-chain hydrocarbon molecules are split in a process based on the splitting of long-chain molecules, which release volatile compounds, including hydrogen, methane, and carbon oxides, producing a combustible gas mixture, according to known processes.

[0003] Conventionally, the main phenomena at work in a gasification process involve the following transformations:- drying of the fuel, during which the fuel is subjected to temperatures between 100°C and 160°C causing the water contained in the fuel to evaporate;- pyrolysis, taking place at temperatures between 120°C and 600°C, during which the fuel is gradually heated in the absence of oxygen, decomposes and results in the formation of by-products, in particular carbon, carbon oxides, methane, tars and volatile compounds;- oxidation, taking place at temperatures between 1200°C and 1500°C, during which oxygen is injected to react with the gases formed during pyrolysis, releasing energy so as to reach the temperatures necessary for the various gasification reactions and forming carbon dioxide and water vapor;- reduction, taking place at temperatures between 800°C and 1200°C, during which the carbon obtained by pyrolysis reduces water vapor and carbon dioxide, forming dihydrogen and carbon monoxide.;

[0004] Classically, three main categories of gasifiers are known: fixed bed gasifiers, fluidized bed gasifiers, and entrained bed gasifiers.

[0005] Fixed-bed gasifiers typically include a vertical reactor. Inside the reactor is a mass, called a "bed," formed by solid fuel, char produced by pyrolysis of the solid fuel, and ash, which descends by gravity as the fuel is transformed. This type of gasifier can be downdraft or updraft.

[0006] In fixed-bed updraft, or countercurrent, gasifiers, solid fuel is injected from the top of the reactor. It then reacts with a gasification stream (air and / or oxygen, steam) that rises from the bottom of the reactor, countercurrent to the direction of solid fuel feed. The solid fuel undergoes a pyrolysis process that transforms it into a solid mass of carbonaceous material that moves downward. In the carbonaceous mass, gasification reactions occur until the carbon mass is reduced to a residue combined with ash, inert materials, etc. The ash is removed from the bottom of the reactor, powdery or in the form of slag. The resulting gas, rich in tar and laden with dust, must be purified before use. This type of gasifier is more suitable than others for relatively non-uniform biomass with high moisture content.On the other hand, the synthesis gas obtained is humid, and loaded with tars and particles.

[0007] In downdraft, or co-current, fixed-bed gasifiers, the gasification flow is introduced into the reactor from the top, in the same direction as the fuel. For the gasifier to operate, the upper part of the bed can be heated simply by conduction from the high-temperature reaction zones, by burning small amounts of fuel, or by using an external heat source. The tar produced must pass through a high-temperature coal bed, and then the syngas produced is cleaner than that obtained in countercurrent gasifiers, other conditions remaining unchanged. In addition, the moisture content is also lower. On the other hand, the gasifier only accepts fuel with optimal uniformity characteristics, small sizes, and low initial water content, and therefore typically uses plant biomass.

[0008] Fixed bed gasifiers are also generally limited in power, typically around 10 MW, and are therefore not suitable for industrial applications requiring high power, such as in cement works.

[0009] In fluidized bed gasifiers, the solid fuel is generally introduced into the lower part of the reactor in the form of small particles, of the order of 5 mm. A fluidization medium is also introduced into the vertical part of the reactor, typically small solid particles, either inert (sand) or catalytic (olivine, dolomite), conveyed by a high-speed air flow. The bed then behaves like a fluid, presenting a great homogeneity of temperature and concentration of reactants. Unlike the fixed bed, fluidization allows the use of more varied fuels, in particular ASF type fuels (Alternative Solid Fuel, a type of fuel mainly prepared from combustible waste to be burned).

[0010] On the other hand, the gas produced is highly loaded with particles, requiring the implementation of treatments before its recovery, making its implementation complexity unsuitable for low-power installations.

[0011] In entrained bed gasifiers, the fuel is sprayed into the gaseous stream of gasifying agent and kept in suspension until completely consumed. The reaction zone can be heated to high temperatures (1300°C to 2000°C). At these temperatures, the reactions are very rapid, on the order of a few seconds, promoting the formation of CO and H2 as well as the steam reforming of methane and the destruction of tars. The ash becomes liquid. A fraction of the molten ash particles is recovered on the reactor walls, or can be partially separated from the gas stream by inertial separation. A portion of the carbonaceous solid can be entrained by the gas. This technology eliminates the problems posed by the use of a fluidizing material and promotes the production of CO and H2 as well as the reforming of methane and the destruction of tars.

[0012] However, this technology requires finely pulverized fuel, typically with a particle size of less than a millimeter, which requires significant fuel preparation upstream.

[0013] However, in the context of the search for industrial solutions that consume less fossil fuels, the use of alternative fuels, particularly ASF-type fuels, presents itself as an interesting alternative. However, the gasifiers of the prior art have disadvantages that degrade the efficiency of the gasification of ASF-type fuels.

[0014] Fixed bed gasifiers do not allow efficient gasification of this type of fuel, fluidized bed gasifiers require regular replacement and treatment of the fluidization medium, and fluidized bed gasifiers require the use of fuel with a very restrictive particle size, which precludes the use of ASF type fuels due to fuel preparation being too energy-intensive.

[0015] There is therefore a need for gasification solutions that can efficiently transform solid alternative fuels.

[0016] To this end, the invention proposes a gasification installation comprising a reactor comprising a substantially cylindrical wall extending along a vertical axis and externally delimiting a cavity configured to contain a gasification reaction, the reactor comprising:- a primary air injection inlet,- a fuel injection comprising at least one fuel injection point arranged above the primary air injection inlet, the primary air injection inlet being arranged in such a way that a gasification air flow is injected into the reactor in a direction substantially tangential to the wall of the reactor,- the wall comprising a substantially cylindrical upper portion, a substantially frustoconical lower portion, for injecting primary air and the fuel injection point being arranged through the lower portion of the wall.

[0017] Such an installation therefore makes it possible to generate a mixing flow in the reactor preventing the fuel bed from falling back by gravity, and thus making it possible to improve the residence time of the fuel in the reactor, thus improving the transformation of the fuel. The separate injection of air and fuel makes it possible to admit a greater variety of fuels, thus making it possible to use ASF type fuels and to transform them efficiently.

[0018] Optionally but advantageously, the following features may complete the invention, taken alone or in combination:

[0019] - the at least one fuel injection point is arranged on the lower portion of the wall so as to inject a gasification air flow into the reactor in an injection direction at the fuel injection point, the injection direction having an inclination relative to a radius R of the reactor at the fuel injection point, so as to give the gasification air flow a tangential displacement component at the fuel injection point; this makes it possible to improve the generation of a circulation of the mixing flow along an upward helical trajectory in the reactor, which makes it possible to improve the homogenization of the temperatures in the reactor;

[0020] - the primary air injection inlet comprises a plurality of fuel injection points distributed regularly along an annular section of the lower portion of the wall; this makes it possible to homogenize the fuel distribution in the reactor and to improve the temperature homogeneity in the reactor;

[0021] - the installation comprises a lift injection configured to inject a lift flow into the reactor so as to oppose the gravity fall of the fuel, the lift injection comprising at least a first stage of injection points arranged above the primary air injection and below the fuel injection point; this makes it possible to improve the entrainment of the fuel towards the upper part of the reactor, limiting its gravity fall, which makes it possible to increase the residence time of the fuel in the reactor and to improve the reaction of the fuel;

[0022] – the installation further comprises a secondary air injection comprising at least one secondary injection stage comprising a plurality of injection openings provided through the upper part of the wall, configured to inject gasification air into the reactor; this makes it possible to inject the gasification air in a distributed manner at several points in the reactor, which makes it possible to improve the control of the reaction at different points in the reactor;

[0023] - the fuel injection comprises a fuel supply circuit comprising a vertical pipe opening onto each fuel injection inlet; this makes it possible to inject the fuel into the reactor at a reduced speed, improving its drive by the mixing flow, while limiting the consumption of the fuel supply circuit;

[0024] – the installation comprises a separation device configured to separate suspended particles from the combustible gas formed in the reactor, the separation device connected to the reactor by means of a channel extending between an upper portion of the separation device and the upper portion of the reactor; this makes it possible to obtain a quality syngas at the outlet of the installation, allowing it to be used as soon as it is produced;

[0025] – the installation further comprises a recovery device configured to reinject the fuel particles which have not completely reacted from the separation device into the reactor; this makes it possible to improve the quantity of fuel used compared to the quantity of fuel injected into the reactor;

[0026] - the channel opens into the reactor in a substantially tangential direction configured to be substantially tangent to the circulation of the mixing flow at the channel; this allows the channel to face the circulation of the mixing flow and thus to limit its deviation to redirect it towards the separation device, which makes it possible to improve the channeling of the mixing flow from the reactor to the separation device. BRIEF DESCRIPTION OF THE FIGURES

[0027] The figures are presented for information purposes only and in no way limit the invention.

[0028] represents an overall view of a gasification installation according to the invention.

[0029] represents a sectional view from above of a gasification installation according to the invention.

[0030] represents a side sectional view of a gasification installation according to the invention.

[0031] represents a side sectional view of a gasification installation according to the invention, more precisely centered on the recovery device.

[0032] represents a profile view of the conical part of the reactor and the associated air injections;

[0033] represents a sectional view at the level of the primary air injection (6A), the lift air injection (6B), and the secondary air injection (6C) according to the invention;

[0034] represents a study of the trajectories of fuel of different 2D granulometries in the reactor according to the invention; and

[0035] represents a study of the axial velocity flow of the fuel in the reactor as a function of the distance from the inlet of the according to the invention. DETAILED DESCRIPTION

[0036] The invention relates to a gasification installation 1, shown in the, comprising a reactor 2 configured to contain a gasification reaction of a fuel. The reactor 2 comprises a substantially cylindrical wall 3 extending along a vertical axis Y under normal conditions of use of the installation, and externally delimiting a cavity configured to contain the gasification reaction. The geometric concepts, in particular top, upper, bottom, lower take as reference the normal conditions of use of the installation, and the references relating to axial, radial and tangential relate to a cylindrical reference frame along the vertical axis Y. The concepts of upstream and downstream refer to the circulation of gases in the installation under normal conditions of use.

[0037] The reactor 2 comprises a primary air injection inlet 4 configured to convey into the reactor 2 a gasification air flow F1 intended to start the gasification reaction of the fuel, and a fuel injection 5 arranged above the primary air injection inlet 4, the fuel injection 5 being configured to introduce fuel into the reactor 2. The wall 3 of the reactor 2 comprises an upper portion 6 having a substantially cylindrical geometry, and a lower portion 7 having a substantially frustoconical geometry widening as it flows from the bottom to the top.

[0038] The primary air injection inlet 4 is arranged on the lower portion 7 of the wall 3 in such a way that the gasification air flow F1 is injected into the reactor 2 in an injection direction at the primary air injection inlet 4. The injection direction advantageously has an inclination relative to a radius R of the reactor at the primary air injection inlet 4. The inclination may be between 30° and 90°, so as to give the gasification air flow F1 a tangential displacement component at the primary air injection inlet 4, so as to generate a highly turbulent mixing flow F2 circulating in an upward helical trajectory in the reactor 2.

[0039] Alternatively, the gasification air flow F1 is introduced into the reactor 2 in a radial injection direction. The gasification air flow F1 is introduced into the reactor at a first speed configured to prevent fuel from falling back. The upwardly widening frustoconical shape of the lower portion 7 of the reactor 2 guides the gasification air flow F1 so as to generate a circulation of the mixing flow F2 in an upward helical trajectory in the reactor 2, the mixing flow F2 gradually slowing down until it reaches a second speed at the upper end of the lower portion 7, the second speed being configured to allow sufficient residence time for the mixing flow in the upper portion 6 of the reactor 2. The introduction of the gasification air flow F1 in a substantially tangential direction makes it possible to promote the guidance of the mixing flow F2 by the frustoconical lower portion 7.

[0040] Preferably, the half-angle at the apex of the lower frustoconical portion 7 is between 15° and 20°. Such a circulation of stirring flow F2 in the reactor 2 makes it possible to drive the fuel particles towards the core of the reactor 2, so as to prevent the fuel particles from falling back towards a lower part of the reactor 2 and to improve the reaction of the fuel. This stirring of the fuel bed makes it possible to accelerate the gasification reaction and to prevent the bed from forming a mass in the center of the reactor 2, which makes it possible to homogenize the temperatures in the reactor 2, and thus to avoid temperature peaks which can cause a problem of melting and sticking of the liquid ash. As in a fluidized bed, the drying, pyrolysis, oxidation and reduction reactions take place in the same zone of the reactor 2, in which the temperature is homogeneous.This limits the formation of tars, particularly those obtained during the pyrolysis phase.

[0041] Injecting primary air without the need for it to transport the fuel makes it possible to use fuels with a more permissive particle size, typically ASF type fuels, the processing of which is complex to achieve a very fine particle size. This therefore increases the compatibility of gasification installation 1 with the different types of fuels available.

[0042] Furthermore, the primary air injection inlet 4 is connected to a main air heating device configured to heat the air to be injected to a chosen gasification temperature T1.

[0043] In practice the main heating device can be a burner.

[0044] As a non-limiting example, the chosen gasification temperature T1 can be between 300°C and 800°C.

[0045] Furthermore, such a configuration of the mixing flow F2 makes it possible to limit, or even do without, a fluidization medium to set the fuel bed in motion. Avoiding the use of a fluidization medium injected with the gasification air flow F1 makes it possible to significantly limit the wear of the installation, as well as to promote the control of the temperature of the reactor 2. Indeed, by limiting the heated mass to only the reactants, the thermal inertia of the bed is thus greatly reduced, and it is thus possible to more precisely control the temperature of the bed by varying the flow rate of the gasification air flow F1. The flow rate of the reactor 2 is also increased compared to a solution using a fluidization medium, because it is possible to assign the total mass capacity of the reactor 2 to reactants.

[0046] In addition, the F2 mixing flow has an upward velocity component which prevents the phenomenon of ash falling back to the bottom of reactor 2.

[0047] The fuel injection 5 is supplied by means of a fuel supply circuit 8, comprising a conveying device 9 arranged to supply fuel to a vertical pipe 10 connected to the fuel injection 5. Thus, the fuel supply to the reactor 2 is carried out by gravity, the fuel being injected into the reactor 2 through the fuel injection 5 with a low horizontal speed. This ensures that all of the fuel is effectively entrained by the mixing flow F2 circulating in a helical trajectory along the wall 3 of the reactor 2.

[0048] The fuel injection 5 comprises two fuel injection inlets 11, arranged through the lower part 7 of the wall 3 and positioned relative to each other in a diametrically opposite manner relative to the vertical axis Y, each being connected to a respective vertical pipe 10, the conveying device 9 being arranged to uniformly supply the two vertical pipes 10. Such a configuration makes it possible to distribute the fuel injection at several points, so as to promote the homogenization of the entrainment of the fuel particles by the mixing flow F2.

[0049] Advantageously, the reactor also comprises a lift injection 12, configured to allow the injection into the reactor 2 of a lift flow F3 configured to blow the fuel bed of the reactor and prevent it from falling by gravity towards the bottom of the reactor 2.

[0050] Advantageously, the lift injection 12 comprises a stage of injection points 13, comprising a plurality of injection points arranged through the lower part 7 of the wall 3 and arranged in a straight section normal to the vertical axis Y, at an intermediate height between the primary air injection 4 and the fuel injection 5. Preferably, the stage of injection points 13 is located close to the fuel injection inlets 11.

[0051] In practice, the lift injection (12) is configured to inject air at an ambient temperature T3, which for example corresponds to 25°C + / -5°C. The reactor may also comprise a secondary air injection comprising a secondary injection stage 14, and advantageously a second secondary injection stage 15, or several stages of additional injection points, each secondary injection stage respectively comprising a plurality of injection openings arranged through the upper part 6 of the wall 3. The secondary air injection 14 is configured to distribute the gasification air injection along the reactor 3 so as to modulate and control the gasification air factor and therefore the temperature level according to the type of fuel, so as to produce a syngas of optimal quality.

[0052] The secondary air injection 14 is connected to a secondary air heating device configured to inject the heated air to at least a selected carrier temperature T2.

[0053] As a non-limiting example, the ratio of chosen gasification temperature T1 / support temperature T2 is between 1.4 and 6.

[0054] Advantageously, the injected air provides the thermal energy necessary for the gasification reaction.

[0055] The secondary air injection 14 is also configured to inject air at a lower speed than the primary 4 and lift 13 injections, due to its location on the upper cylindrical portion 6 of the reactor 2 and thus extend the time the fuel is present in the reactor 2.

[0056] In practice, the primary air injection inlet 4, the lift injection inlet 12 and the secondary air injection inlet 14 are arranged on the wall 3 in a horizontal orientation, following a direction normal to the vertical axis Y.

[0057] Horizontal injections create a cyclonic movement at the level of the truncated cone and a controlled increase in the residence time of the fuel in the reactor.

[0058] In practice, the direction on a horizontal plane of the primary injection 4, the lift injection 13 and the secondary injection 14 has a tangential component with respect to a segment representing between half of the radius R of the reactor 2 and two thirds of the radius R of the reactor 2 from the center of the reactor 2.

[0059] Advantageously, an injection whose tangential component relative to a segment representing half of the radius R of the reactor 2 promotes the increase in the speed of movement of the components at a peripheral circumferential part of the reactor 2, an injection whose tangential component relative to a segment representing two thirds of the radius R of the reactor 2 relative to the center of the reactor 2 promotes the increase in the speed of movement of the components at an axial part of the reactor 2.

[0060] According to a particular embodiment of the invention, the primary injection direction 4 has a tangential component relative to a segment representing half of the radius R of the reactor 2, the lift injection 13 has a tangential component relative to a segment representing two thirds of the radius R of the reactor 2 and the secondary injection 14 has a tangential component relative to a segment representing half of the radius R of the reactor 2.

[0061] The combination of three air injection levels arranged in a chosen structural sequence makes it possible to limit the number of fuel particles leaving reactor 2 through the upstream opening, while limiting temperature peaks in the reactor and controlling the residence time and temperature of the fuel so that a substantially complete reaction of the fuel is carried out.

[0062] Advantageously, the three air injection levels arranged according to a chosen structural sequence also make it possible to reduce the necessary height of the reactor 2 to allow a substantially complete reaction of the fuel while limiting the percentage of particles escaping through the upstream outlet of the reactor 2 to less than 10% when the fuel load in the reactor 2 is at 100%.

[0063] Furthermore, the optimization of the cyclonic effect with the structural choices according to the invention makes it possible to maintain an average efficiency of the cyclone between 80% and 90% when reactor 2 is loaded at 100%, and an average efficiency of the cyclone between 60% and 70% when reactor 2 is loaded at 50% while reducing the necessary height of the reactor and thus its weight and cost.

[0064] With reference to the, the combination of three air injection levels arranged according to a chosen structural sequence also makes it possible to obtain a percentage of the section of the reactor 2 having a positive axial velocity in the direction of fuel flow of between 60% and 90%, thus limiting the exit of fuel particles through the upstream outlet of the reactor 2 while ensuring an adequate suspension time of the fuel in the reactor 2.

[0065] The installation may advantageously comprise a separation device 16 in fluid connection with the reactor 2 by means of a channel 17. The separation device 16 is configured to allow separation of the suspended particles from the gases in the flow leaving the reactor 2 through the channel 17. The separation device 16 comprises an extraction pipe 18 configured to evacuate the gases resulting from the gasification, typically the synthetic gas (syngas) comprising hydrogen, carbon monoxide, and methane, from the separation device 16 to a network for consumption or elimination of the gas produced.

[0066] In the embodiment shown, the separation device 16 has a substantially cylindrical geometry, comprising a substantially cylindrical upper portion 19 extending along a second vertical axis Y', and a frustoconical lower portion 20 extending along the second vertical axis Y'. The channel 17 extends between the upper portion 6 of the reactor 2 and the upper portion 19 of the separation device 16. The extraction pipe 18 comprises an upstream portion 21 which extends along a vertical axis, here along the second vertical axis Y', from an inlet section 22 located in the upper portion 19 of the separation device 16, through an upper end 23 of the separation device 16. The inlet section 22 is advantageously located at a height lower than that of the channel 17 under normal conditions of use.

[0067] Thus, the gases and gasification products generated in the reactor 2, carried by the mixing flow F2 and the lift flow F3, circulate through the channel 17 arriving at an upper end of the reactor 2. They enter the separation device 16 and fall by gravity towards the lower portion 20. The most volatile compounds, typically the gaseous products, rise and are evacuated through the extraction pipe 18. The relative position of the inlet section 21 of the recovery pipe 20 with respect to the channel 17 makes it possible to prevent the ash and slag from the gasification from being able to circulate directly from the channel 17 to the extraction pipe 18. These solid products fall by gravity towards the lower portion 20 of the separation device 16.

[0068] Advantageously, the channel 17 extends from an upper end of the reactor and the upper end 23 of the separation device 16, and is configured so as to promote the circulation of the mixing flow F2 through the channel 17. The mixing flow F2 circulating in a helical trajectory along the wall 3 of the reactor 2, the channel 17 opens into the reactor in a tangential direction facing the circulation of the mixing flow F2, so as to limit as much as possible the bend made by the flow circulating in the reactor 2 when it enters the channel 17. In this way the flow circulating in the reactor 2 is efficiently channeled towards the separation device 16, with minimal disturbance to the flow direction of the mixing flow F2.

[0069] Advantageously, the channel 17 opens into the separation device 16 in a direction tangential to the second vertical axis Y'. Thus, the flow leaving the channel 17 maintains its speed by flowing along a helical trajectory, this time descending due to the gravity acting on the flow. This makes it possible in particular to eject the particles carried by the flow against the walls of the separation device, and to confine the flow evolving at high speed against the walls of the separation device 16. This thus makes it possible to limit mixing and turbulence in the central part, around the second vertical axis Y', and to prevent the particles from rising towards the inlet section 22 due to excessive mixing.

[0070] Advantageously, the separation device 16 comprises a recovery device 24 located at a lower end of the lower portion 20, configured to recover the solid products of the gasification, typically the ash, the slag, and the fuel residues which have not completely reacted. This makes it possible to avoid the accumulation of these particles in the separation device 16, which could lead to the evacuation of particles in the recovered gas through the extraction pipe 18.

[0071] The recovery device 24 advantageously comprises a sorting module 25 and a reinjection module 26. The sorting module 25 is configured to separate the ash from the unburned fuel particles, and to evacuate the material that can no longer gasify, typically the ash. The reinjection module 26 is configured to reinject into the reactor 2 the particles that have not been evacuated by the sorting module 25. This makes it possible to recycle the fuel particles that have not been completely consumed and thus to optimize the conversion of the carbon fraction of the fuel into gas. This is particularly advantageous for fuels whose gasification is slower, typically ASF type recovery fuels.

[0072] The reinjection module 26 is advantageously connected to the lower part 7 of the reactor 2, and opens at a height greater than that of the fuel injection 5. The reinjection module 26 is arranged in such a way that the recycled particles are injected into the reactor 2 by gravity. In this way, the recycled particles are efficiently entrained by the mixing flow F2 and the lift flow F3 and are reintegrated into the fuel bed.

[0073] The sorting module 25 is advantageously equipped with a draining device 27 for removing particles that are not recycled by the reinjection module 2. The draining device 27 may, for example, comprise an endless screw for removing the waste, and upstream of the endless screw an airlock comprising two valves configured to open alternately so as to allow the circulation of the waste while maintaining a seal between the sorting module 25 and the endless screw.

[0074] Advantageously, the recovery device 24 comprises a fluidization injection 28, arranged to inject a fluidization flow F4 configured to fluidize the particles collected in the recovery device 24 and facilitate their circulation, thus avoiding occlusions. The fluidization injection 28 advantageously comprises an upstream injection point 29 and a downstream injection point 30. The upstream injection point 29 is positioned at the inlet of the recovery device 24, in the direction of circulation of the particles in the recovery device 24. It is advantageously configured to blow the particles towards the recovery device 24, so as to impart an initial flow movement to the particles. The downstream injection point 30 is advantageously located in a lower part of the recovery device 24, and configured to inject the fluidization flow F4 into the particles in such a way that they behave like a fluid.

[0075] In the embodiment shown, the sorting module 25 of the recovery device 24 comprises a separation pipe 31 generally forming a “U” extending between the lower end of the lower portion 20 of the separation device 16, and the reinjection module 26. In the embodiment shown, the reinjection module 26 comprises a reinjection pipe 32 extending along a downward slope between the separation pipe 31 and the reactor 2, in the direction of circulation of the particles. The upstream injection point 29 of the fluidization injection 28 is located at an upstream end of the separation pipe 31. The separation pipe 31 comprises from upstream to downstream a first substantially vertical segment 311, a second substantially horizontal segment 312 and a third substantially vertical segment 313. The second segment 312 therefore connects the lower ends of the first segment 311 and the third segment 313.The downstream injection point 30 is located at the level of the second segment 312. Such a configuration makes it possible to prevent the return of higher pressure gas circulating in the reactor 3 to a lower pressure zone located in the lower part of the separation device 16.

[0076] Thus, the particles blown towards the first segment 311 by the upstream injection point 29 accumulate in the second segment 312 and are fluidized by the fluidization flow F4, and are therefore distributed in the second segment 312. By accumulation, the level of the accumulating particles rises along the first section 311 and third section 313, in the manner of a communicating vessel thanks to the fluidization flow F4. When the level of the particles reaches that of the reinjection pipe 32, the particles circulate by gravity towards the reactor 2, and are recycled. The fluidization allows the least dense phase, therefore all of the largest particles, to “float” on the densest phase, composed of ash of very small particle size. An opening equipped with a filter can be positioned at the level of the second segment 312 to prevent the accumulation of ash and prevent it from being recycled.

[0077] The fluidization stream F4 may include an inert gas, such as nitrogen, or carbon dioxide or water vapor, or a mixture of these gases, in order to avoid secondary combustion of residual carbon contained in the ash and a reactant contained in the gas, which could result in the formation of a molten ash magma leading to occlusion of the pipe.

[0078] Advantageously, the gasification installation 1 also comprises a control unit configured to control and pilot the various operating parameters of the gasification installation 1. The control unit is advantageously capable of piloting the flow rate of the gasification air flow F1 so as to adjust the circulation speed of the mixing flow F2, which makes it possible to control the gasification reaction speed.

[0079] Advantageously, the control unit is also capable of controlling the temperature of the gasification air flow F1. This makes it possible to modulate the speed of the gasification reaction. The gasification air flow F1 is heated to a gasification temperature T1 of between 300°C and 800°C.

[0080] Advantageously, the gasification air flow F1 comes at least in part from a hot air flow from a production process, typically when implemented in a cement production unit, the hot air from the cooling elements can be redirected to supply the gasification air flow F1.

[0081] Advantageously, the gasification flow F1 contains water vapor, or oxygen, which improves the quality of the gas produced by gasification.

[0082] Advantageously, the gas recovered by means of the extraction pipe 18 can be used to reheat the gasification flow F1 by means of a heat exchanger, and can be used in part to supply a burner configured to bring the gasification flow to the desired temperature. This makes it possible to limit the need for external energy input to supply the gasification reaction.

[0083] The implementation of safety devices, particularly at the gasifier level, following an Analysis of Failure Modes, Effects and Criticality (AMDEC) and the drafting of voluntary / safety / emergency start-up and shutdown sequences:

[0084] Advantageously, the upper portion 6 and the separation device 16 are equipped with vents (not shown), configured to allow circulation of the internal gases to the outside when the pressure of the gases in the reactor 2 or the separation device 16 exceeds a predefined threshold. This makes it possible in particular to limit the internal pressure in the event of an accidental explosion, in particular during transient phases such as the start-up or shutdown of the installation.

[0085] Advantageously, the upper portion 6 of the reactor 2 is equipped with an injection rod (not shown) configured to inject water into the reactor in the event of a need to rapidly reduce the temperature of the reactor 2. Advantageously, the injection rod is retractable so as to be located outside the reactor when it is not in use.

[0086] Advantageously, the reactor 2 comprises an injection of inert gas (N2 or CO2) at the level of the lower portion 7 so as to purge the gasification unit in the event of a critical situation (emergency shutdown, fire).

Claims

Gasification installation (1) comprising a reactor (2) comprising a substantially cylindrical wall (3) extending along a vertical axis (Y) and externally delimiting a cavity configured to contain a gasification reaction, the reactor (2) comprising: - a primary air injection inlet (4), - a fuel injection (5) comprising at least one fuel injection point (11) arranged above the primary air injection inlet (4), the primary air injection inlet (4) being arranged in such a way that a gasification air flow (F1) is injected into the reactor (2) in a direction substantially tangential to the wall (3) of the reactor (2), - a lift injection (12) configured to inject a lift flow (F3) into the reactor (2) so as to oppose the fall by gravity of the fuel,the lift injection (12) comprising at least a first stage of injection points (13) arranged above the primary air injection (4) and below the fuel injection point (11),- a secondary air injection comprising at least one secondary injection stage (14) comprising a plurality of injection openings arranged through the upper part (6) of the wall (3), configured to inject gasification air into the reactor (2).- the wall (3) comprising a substantially cylindrical upper portion (6), a substantially frustoconical lower portion (7), and in which the primary air injection (4) and the fuel injection point (11) are arranged through said lower portion (7) of the wall (3)., Gasification installation according to claim 1, in which the lift injection (12) comprises a plurality of injection points distributed regularly along a straight section normal to a vertical axis Y of the lower portion (7) of the wall (3) at an intermediate height between the primary air injection (4) and the fuel injection (5). Gasification installation (1) according to any one of the preceding claims, in which the fuel injection (5) comprises a fuel supply circuit (8) comprising a vertical pipe (10) opening onto each fuel injection inlet (11). Gasification plant (1) according to any one of the preceding claims, further comprising a separation device (16) configured to separate suspended particles from the combustible gas formed in the reactor, the separation device (16) connected to the reactor (2) by means of a channel (17) extending between an upper portion (19) of the separation device (16) and the upper portion (7) of the reactor (2), Gasification plant (1) according to claim 3, further comprising a recovery device (24) configured to reinject the fuel particles which have not completely reacted from the separation device (16) towards the reactor (2). Gasification installation (1) according to claim 4 or claim 5, wherein the channel (17) in the reactor (2) in a substantially tangential direction configured to be substantially tangent to the circulation of the mixing flow (F2) at the channel (17). Gasification installation (1) according to one of the preceding claims, characterized in that the primary air injection inlet (4), the lift injection inlet (12) and the secondary air injection inlet (14) are arranged on the wall (3) in a horizontal orientation. Gasification installation (1) according to one of the preceding claims, characterized in that the primary air injection (4) is connected to a main air heating device configured to inject the air heated to a chosen gasification temperature T1. Gasification installation (1) according to one of the preceding claims, characterized in that the secondary air injection (14) is connected to a secondary air heating device configured to inject the air heated to a chosen support temperature T2. Gasification installation (1) according to one of the preceding claims, characterized in that the lift injection (12) is configured to inject air at an ambient temperature T3. Use of the gasification installation (1) according to one of the preceding claims for the gasification of fuel comprising a total quantity of injected air according to an air factor of between 0.3 and 0.4.

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