EP1883603A2

EP1883603A2 - Device provided with a reaction chamber in which pre-heated fluid reagents are introduced for generating a high-temperature reaction

Info

Publication number: EP1883603A2
Application number: EP06726284A
Authority: EP
Inventors: Didier Grouset; Samuel Lecoq; Christophe Hoguet
Original assignee: N Ghy SA
Current assignee: N Ghy SA
Priority date: 2005-03-31
Filing date: 2006-03-28
Publication date: 2008-02-06
Also published as: WO2006103369A3; FR2883774A1; WO2006103369A2

Abstract

The invention relates to a device provided with a reaction chamber (12) in which fluid reagents are introduced in such a way that a high-temperature reaction is generated. The inventive device comprises a first substantially cylindrical area (14) which surrounds the reaction chamber, in which at least one type of reagent introducible therein, apart from reaction products, flows and which is separated from said reaction chamber in such a way that, a heat lost in the reaction chamber is, at least partially, recovered and used for preheating the reagent(s) flowing in the first area, wherein said reagent(s) are in direct contact with the first area walls, thereby making it possible to carry out heat exchanges, and a second substantially cylindrical area (16) which surrounds the first area and in which at least one type of reagent also introducible into the reaction chamber, apart from reaction products, flows, wherein the separation between the first and second areas is constructed such that the reagent(s) flowing in the second area recover(s) the heat of the second area, thereby preheating said reagent(s) which are in direct contact with the walls thereof.

Description

REACTION CHAMBER DEVICE

IN WHICH ARE INTRODUCED REAGENT FLUIDS PREHEATED TO REALIZE A HIGH TEMPERATURE REACTION

The invention relates to a reaction chamber device in which preheated reactive fluids are introduced to perform a high temperature reaction. It is often necessary, for example in self-recuperating burners or for the manufacture of hydrogen in a reforming operation, to preheat reactive fluids. It is also often necessary to achieve, for the same applications, high temperature reactions without heat loss. To achieve this goal, it has already been proposed to provide a reaction chamber surrounded by an annular zone in which the hot products of the reaction circulate in order to preheat the reactants, circulating against the current or cocurrent, in a coil-type exchanger. , to be introduced into the reaction chamber.

The invention results from the observation that this realization is complex since the annular zone must channel two fluids (the reaction products and the reagents) which must not mix. In addition, the hot products of the reaction must be fed, by high temperature conduits and with changes of direction, towards the annular zone. To remedy this drawback, the invention proposes a reaction chamber device in which reactive fluids are introduced to carry out a reaction at high temperature, this device comprising: a first substantially cylindrical zone surrounding the reaction chamber in which circulates at least one of the reactants to be introduced into the reaction chamber, excluding the products of the reaction, this zone being separated from this reaction chamber so as to recover, at least in part, the heat lost by the reaction chamber. reaction, so as to preheat the reactant (s) circulating in the first zone, the reagent or reagents being in direct contact with the walls of this first zone to perform heat exchange,

a second substantially cylindrical zone surrounding the first zone and in which circulates at least one reagent also intended to be introduced into the reaction chamber, excluding the products of the reaction, the separation between the first and the second zone being such that the reactant (s) circulating in the second zone recover (s) from the heat lost by the first zone in order to preheat this reagent or reagents, which is (are) in direct contact with the walls of this zone; second zone, the assembly being such that the external wall of the device, which is constituted by the outer wall of the second zone, is at a temperature substantially lower than the temperature of the reaction chamber, the device being, in addition, such that that the reaction chamber has two parts, the first of which is the seat of the reaction and the second is a channel for discharging the products of the reaction, this evacuation channel being of substantially rectilinear configuration in which the products circulate in only one direction, these two parts being such that the heat exchange between the second part of the reaction chamber, the closest to the output of the products of the reaction, and the first area is significantly larger that the heat exchange between the first part of the reaction chamber and the first zone.

Thus, in each of the two annular zones surrounding the reaction chamber, only one type of fluid will be circulated: a reagent or a mixture of reagents. It is therefore not necessary to organize a separate circulation of the two fluids (reagents and products of the reaction), which considerably simplifies the mechanical realization of these annular zones. In addition, it is not necessary to make pipes subject to significant thermomechanical stresses to change the flow directions and drive the hot products of the reaction to the annular zone.

In addition, with the first and second zones, a good insulation is obtained with respect to the outside of the reaction chamber at high temperature.

Since the outlet channel of the reaction products is of substantially rectilinear configuration and the products circulate in only one direction, there is no obstacle to the evacuation and thus, the evacuation performs faster and more simply.

Due to the configuration of the device, the realization is easy and inexpensive.

In addition, the reliability of the device is important since there is no transverse wall subjected to too much heat flow. In particular, there is no coil or bundle of tubes, or fin immersed in the flow of hot products. Thus, the mechanical stresses are minimized, in particular because the temperature is more homogeneous and therefore, on average, lower. Because of this lower temperature, corrosion is minimized. As a result, the service life is increased.

In one embodiment, the device is for performing a reforming reaction to generate hydrogen from water, hydrocarbon and an oxygenated stream. The water, the hydrocarbon and the oxygenated flux are the reactants whose least one of them is preheated in the first and / or second zone.

In one embodiment, the oxygenated stream is air, for example at low pressure; the air preferably circulates in the first and second zones.

In general, the temperature profile of the fluids in the reaction chamber can be adapted by choosing the characteristics of the wall between this reaction chamber and the first zone. In one embodiment, the device comprises a third zone inside the second part of the reaction chamber, this third zone being intended to recover by heat exchange of the heat of this second part of the reaction chamber in order to preheat reagents or fluids circulating in this third zone, the wall separating the reagents or fluids, on the one hand, and the products of the reaction at high temperature, on the other hand, being substantially cylindrical and smooth.

Thus, the hot flows flow along the walls without encountering obstacles or surfaces orthogonal to the flow which would, if they existed, be weakened because subjected to high temperatures and high thermomechanical stresses by this flow. In particular, no coil type exchanger or bundle of exchanger tubes, with or without fins (s), is provided in this hot gas stream.

In one embodiment, for reforming for hydrogen generation, air is circulated in the first and second zones, the preheating of the other reagents being carried out in the third zone.

In one embodiment, for the generation of hydrogen by a reforming operation from liquid hydrocarbon, water and an oxygenated flow, the third zone inside the second part of the reaction chamber comprises : means for circulating water in order to preheat, vaporise and overheat it,

means for vaporizing the liquid hydrocarbon and mixing it with the steam, and means for superheating the steam and hydrocarbon mixture.

In a variant, which has the same advantages, there is provided a device for the generation of hydrogen by a reforming operation from gaseous hydrocarbon, water and an oxygenated flow, the third zone, to the inside the second part of the reaction chamber, comprises:

means for circulating water in order to preheat, vaporise and overheat it,

means for mixing the gaseous hydrocarbon with the water vapor, and

means for overheating the mixture of water vapor and hydrocarbon.

With this embodiment, because of the provision of the third zone, the reagents are optimally preheated. In addition, optimum cooling of the products of the reaction is obtained. Finally, the compactness of the device is increased and therefore the hot bonds are reduced, the whole of the chemical reaction, the preheating of the reactants and the cooling of the reaction products being carried out in a single chamber.

In one embodiment, the device comprises:

means for creating fine droplets of liquid of a component to be introduced in gaseous form into the reaction chamber; means for mixing these droplets with a hot gas also intended to be introduced into the reaction chamber; hot gas for vaporizing at least a fraction of the droplets, and

a hot surface, in particular heated by the heat exchange with the reaction chamber, at a temperature sufficient to vaporize the fraction of the unvaporized droplets by mixing with the hot gas, the means for creating droplets projecting these droplets towards the hot surface. For example, if the liquid is diesel, it is vaporized quickly and avoided coking, that is to say the cracking of the hydrocarbon with the production of soot especially if the hot gas is steam. water. This means can moreover be used independently of the previously described structure of the reforming device (hydrogen generation). In other words, this provision of the invention can be used generally to achieve a mixture of water vapor and hydrocarbon without risk of coking.

In addition, this arrangement of the invention makes it possible to grant the flow of liquid with the flow of steam. In particular, it is ensured that all the liquid produced is vaporized almost instantaneously.

Droplet spraying maximizes the liquid exchange surface with the hot gaseous environment and contributes to the equal result between the instantaneous flow rates of introduced liquid and vaporized liquid.

This arrangement can also be used to spray the water, vaporize it and possibly start overheating. The hot gas is constituted by the possibly superheated water vapor which helps to initiate the vaporization of the droplets that arrive, before their impact on the hot surface.

In one embodiment, a series combination of these spray means devices is used with, first of all, for example a chamber with a water sprayer and a hot surface for the vaporization of the water, and then a a chamber with a hydrocarbon spray for the vaporization of heavy liquid hydrocarbon, with a higher vaporization temperature than water, using superheated steam and a hot surface, In another embodiment, of the parallel combination type, it is possible, in the same chamber, to vaporize water and a light liquid hydrocarbon with a boiling point close to that of water, such as ethanol for example, using two sprayers, one for water and the other for hydrocarbon or a single sprayer for the water / hydrocarbon mixture, the vaporization taking place on the same hot surface.

In another embodiment, a gaseous hydrocarbon is used to assist in spraying water.

In one embodiment, which can also be used independently of the arrangements previously described, the device comprises an annular space, for example in one of the zones, comprising means for ensuring a helical circulation of fluids intended to be introduced into the reaction chamber. in order to homogenize the temperature of the walls and the fluid flowing in this annular space, these helical circulation means being furthermore arranged to perform a spacer function between the walls of this annular space.

Preferably, the annular space constitutes a heat exchange space arranged so that the pitch of the helical circulation is such that heat exchange is optimized. In one embodiment, which can be used independently of the arrangements previously described, the device comprises:

an injector for generating the droplets of a fluid intended to be introduced into the reaction chamber, of small size and of high speed for rapid vaporization, the injector being dimensioned for a flow rate substantially greater than the flow rate necessary for introduction in the reaction chamber, and

means for operating this injector intermittently and at a high frequency in order to obtain the low flow rate desired for introduction into the reaction chamber and the desired quality of the droplets.

In one embodiment, the reaction chamber comprises orifices for the quasi-tangential arrival of the oxygenated flow to create a film in the vicinity of the wall of a combustion portion (26) of the combustion chamber, this film forming a vortex or vortex thereby creating a depression in the vicinity of the axis of the combustion chamber that sucks hydrocarbon fuel vapors and ensures the stabilization of combustion near the axis and at the bottom of the combustion portion of the combustion chamber reaction.

According to one embodiment, the device comprises an injector delivering water and hydrocarbons into the combustion chamber against the flow of the products of the reaction so as to carry out a rapid mixing of the water vapor and the hydrocarbons with the hot gases to propagate the reforming reaction.

In one embodiment, the reagent supplying means comprise means for one part of the reagents to move towards the bottom of the combustion chamber and the other part to go directly to the reaction chamber.

Other features and advantages of the invention will become apparent with the description of some of its embodiments, this being done with reference to the accompanying drawings in which: Figure 1 shows a device according to one invention.

An embodiment of a hydrogen generating device (or reformer) will now be described with reference to FIG. The device described below runs on diesel, water and air. Variants of this device can operate from other hydrocarbons including petroleum cuts such as diesel, naphtha, kerosene, gasoline, liquefied petroleum gas, alcohols, or natural gas and still biofuels such as biogas, vegetable oils or their esters, ethanol or methanol. Other variants of this device can operate using, instead of air, an oxygenated stream such as pure oxygen or a mixture of air and oxygen. This device produces a mixture of H ₂ and CO, also containing CO ₂ and H ₂ O, which is introduced into another device (not shown) which still produces hydrogen by the action of H ₂ O on CO for turn into CO ₂ .

The reforming operation that provides CO + H ₂ is an endothermic reaction, i.e., a reaction to which heat must be provided. For this purpose, an exothermic reaction is used which consists of the combustion of a fraction of the flow of the hydrocarbon with an oxygenated flow. Thus, a fraction of the hydrocarbon is a fuel for providing heat and the hydrocarbon fraction is the main reagent that will supply the hydrogen. It is therefore understood that the burned hydrocarbon fraction must be minimized to maximize the reformed hydrocarbon fraction. The reforming gases are produced at high temperature and the heat they contain is recovered to preheat the incoming fluids in the reaction chamber, or reagents, namely water, hydrocarbon and oxygenated stream. Thus, the reforming reaction is carried out with hot reactants, which makes it possible to reduce the burned hydrocarbon fraction.

The invention provides a device for minimizing thermal losses to the external environment and thus improving the efficiency of the hydrogen generator.

The invention also makes it possible, by assembling the various operations in the same enclosure, to limit or eliminate the connections of hot fluids or reactants between the various modules or stages of the hydrogen generation process (preheating of the water, evaporation, overheating , preheating of the oxygenated flow, preheating of the hydrocarbon, chemical reaction, cooling of the reforming gases, etc.), this which reduces thermal losses and thermomechanical problems of hot connections between several speakers, including pressure vessels.

In the example shown in FIG. 1, the oxygenated flow is oxygen in the air, preferably at low pressure, for example at a pressure between atmospheric pressure and 6 bar. However, variants of this device can operate at pressures of 1 to 100 bar.

The device shown in the figure comprises a central portion constituting the reaction chamber 12. This chamber is surrounded by a first zone or annular space 14 in which circulates air at a temperature of 400 to 900 ⁰ C which recovers the heat lost by the reaction chamber 12.

This annular zone 14 itself is surrounded by a second annular zone 16 in which low-pressure air also circulates at a temperature of 25 to 400 ^° C., which recovers the heat lost by the zone 14.

The air is first introduced into the outer zone 16 through an opening 18. A communication 20 is established between the zones 14 and 16. This communication is located at one end of these zones, as opposed to the entrance 18. Thus, it is after having circulated in the zone 16 that the air is introduced into the zone 14.

The wall 22 between the zones 14 and 16 is constituted by an insulating wall or by a wall packed on a calculated thickness of a material chosen for its low thermal conductivity. The annular zone 16 is surrounded by an external insulator 17.

The air thus preheated in the annular zones 16 and 14 penetrates through orifices 24 in the combustion portion 26 of the chamber 12. Most of the heat lost by the reaction chamber is recovered by the air introduced into this chamber. reaction chamber. Thus, in the embodiment presented here, less than 2% of the heat developed in the reaction chamber is lost in the environment. The orifices 24 open in the same plane perpendicular to the axis 30 of the device whose general shape is cylindrical. These preheated air injection orifices 24 are at the end of pipes (not shown) which do not have a radial direction but a direction close to a direction tangential to the circumference of the combustion part 26.

The almost tangential arrival of the air creates a film in the vicinity of the wall 32 of the combustion chamber 26. Under these conditions, the injected air forms a vortex or vortex which thus creates a depression in the vicinity of the axis which draws the combustible vapors and stabilizes the combustion at a temperature level of 1600 to 2000 ^° C., close to the axis 30 and at the bottom of the combustion portion 26 of the chamber 12.

At the end of the combustion part, there is also a nozzle 34 for the introduction of diesel fuel at the start of the device. Also for start-up, there is provided, in a channel opening at the end of the combustion part 26, a retractable spark plug 36.

The preheating and the introduction of the other reagents (water and hydrocarbon), after the start-up periods, take place in an area 40 at the end of the reaction chamber 12 which is opposite to the part 26 of combustion. More specifically, the reaction chamber 12 comprises a first portion 42 in which the reactions take place and a second portion 44 in which the reaction products are evacuated. The first part 42 is itself composed of the combustion part 26 and the reforming part 28 itself. Thus, the preheating zone 40 is located inside the part 44 of the chamber 12 which is intended for the evacuation of the gases from the reaction.

The zone 40 for introducing and preheating the water and the hydrocarbon is extended by a rod 50 penetrating into the reaction chamber, in particular in its portion 28 of reforming, and ends with an injector 52 delivering reactants in the combustion chamber 26 as well as in the reforming chamber 28. The injector 52 thus comprises, on the one hand, at least one axial outlet 54 which injects the gaseous mixture water and hydrocarbon to the combustion chamber and, on the other hand, radial or oblique outlets which open directly into the reforming portion 28 of the chamber 12.

The injector 52 is in an area 58 of smaller section than that of the portion 28 of the reaction chamber 12. Thus, in this zone 58, the gas velocities are greater than in the other sections. As a result, the mixture of the reactants injected through the orifices 56 with the hot combustion gases is rapidly carried out so that the reforming reaction is, in the part 28, rapid and at temperature levels of the order of 1000 to 1400 ^° C.

The zone 40 for preheating and injecting water and hydrocarbon comprises two chambers 62 and 64 in series. The chamber 62, furthest from the rod 50, receives by an injector 66 water droplets which are projected towards a concave face 68 of a wall 70 heated by the heat provided by the reaction products. Part of the water droplets evaporates when in contact with the surface 68. This creates water vapor that flows along the surface 68, heats up and creates a warm atmosphere, at a temperature of 100 at 160 ^° C., contributing to the vaporization of another part of the droplets, as soon as they are ejected, before their impact against the face 68.

The volumes 62 and 64 are sufficiently small for the steam to evacuate immediately and the water vapor thus produced is introduced into an annular zone 74 between the wall 70 and an outer wall 72 of the zone 40. this wall 72 is in contact with the products of the reaction. Thus, by the circulation in the annular zone 74, the steam is continued to overheat at temperatures of 400 ° to 700 ° C. This annular zone 74 is in connection with the second chamber 64 through an opening 76. In addition, in the chamber 64, opens an injector 78 for the introduction of diesel fuel. The chamber 64 ends, like the chamber 62, by a concave face 80 of a wall 82 also heated. In this chamber 64, the diesel droplets introduced by the injector 78 are largely vaporized by contact and mixing with the water vapor and the gas oil droplets not yet vaporized evaporate by contact with the heated face 80. The mixture of water vapor and diesel fuel is discharged at a temperature of the order of 350 to 500 ⁰ C to another annular zone 84 between the wall 82 and the wall 72 where it is superheated at a temperature of 600 to 800 ⁰ C to be then introduced into the rod 50 at the end of which is the injector 52.

At the end of the chamber 12 opposite the combustion portion 26, there is provided an outlet 90 for the reaction gases. These reaction or reforming gases undergo cooling because they yield their heat to air through walls 110 and 112 and to water vapor and diesel in zone 40 through wall 72. Without further cooling, the outgoing gases have a temperature of the order of 600 to 85O ⁰ C. It is also possible to provide additional cooling, for example by water spray in an annular zone 92 near the outlet. In this case, the exit temperature of the reforming gases can be adjusted between 300 and 45O ⁰ C.

In one embodiment, the water which is introduced by the injector 66 arrives in the form of pulses.

Indeed, an injector is sized to provide determined droplet sizes for a given flow rate and pressure. If only one type of injector is available and this injector is sized for the nominal flow rate, it can not be operated satisfactorily at a reduced flow rate. If, for example, the reduced flow rate is 30% of the nominal flow, then the pressure will not be that of the order of 10% of the nominal pressure and the droplets will have an average size 10 times greater than the rated speed. Under these conditions, the evaporation time of these droplets will be approximately 100 times greater.

Therefore, since it is practically impossible to operate the device with an injector operating at a small fraction of its nominal flow rate, according to the invention, the injector is operated at its nominal flow rate and at its pressure. nominal but in the form of periodic pulses, that is to say for only a fraction of each period. The repetition frequency of the pulses must be relatively high, of the order of a few tens to a few hundreds of Hertz, to avoid disrupting the operation of the device because it must be fed constantly droplets. In one example, the frequency of the pulses is of the order of 250 Hz.

In addition, a pulsed fluid supply is effected by means of a valve (not shown) with a low response time which is periodically open and closed. However, pulses transmitted from a valve to an injector can be damped if the pipe is deformable or elastic and / or the liquid is compressible. If the pressure variation slots over time did not show stiff edges at the injector, droplets of large dimensions would be obtained when the pressure is too low. It is therefore preferable to limit the volume between the valve and the injector and to provide pipes with rigid walls. The same device can be used for injecting and spraying low flow water in zone 92.

The walls 110 separating the first portion 42 of the chamber 12 from the first annular zone 14 are insulating so that the reforming reaction is carried out as adiabatically as possible. On the other hand, the wall 112 of the chamber 12 in the second portion 44 for evacuating the reforming product has heat conduction properties to allow efficient heating of the air in the annular zone 14. The walls 110 and 112 are coated on the side of the chamber 12 of refractory ceramic so that these walls are protected against the effect of hot reforming gases. The refractory ceramic of the wall 110 is insulating while the refractory ceramic of the wall 112 is heat conducting. On the outer side, these walls 110 and 112 are metallic.

In one embodiment, so that the wall 72 of the zone 40 is not excessively heated, a thermal protection 120, for example made of refractory ceramic, is provided at the end of the zone 40. Indeed, the wall 72 is metallic. Its temperature is of the order of 600 to 800 ^° C. Without the layer 120, this wall 72 would be brought to a temperature of between 900 and 1400 ^° C.

The rod 50 is also made of ceramic so as to withstand the high temperatures of the reaction chamber.

Each of the various annular zones 14, 16, 74 and 84 comprises a rib arranged in a helix having the reference 130 in the annular zone 14. This helical rib 130 is integral with the exchange wall 140 that constitutes the outer metal part of the walls 110. and 112.

The helical ribs make it possible to increase heat exchange. Indeed, it is known that the heat exchange is more effective than the hydraulic diameter is small. The hydraulic diameter is equal to 4S / P, S being the passage section of the gas, and P the perimeter corresponding to this section S. The passage section is delimited by the two walls of each annular zone and the pitch of the propeller . Thus, a proper choice of distance between walls and pitch of the propeller can minimize the hydraulic diameter.

In addition, the helical rib increases the rate of passage of gases, which further improves the heat exchange in the annular zone where the rib.

Thus, the exchange wall 140 is almost at the temperature prevailing in the annular space 14. In fact, the exchange coefficient on the side of the reaction chamber, which is devoid of helical rib, is lower. In other words, the wall is brought to a temperature close to that of the circulating fluid on the side where the heat exchange coefficients are the highest.

The helical ribs also have the advantage of allowing a better circumferential homogenization of the temperature around the axis 30 because the gases do not circulate in a single generator but circulate all around this axis. As a result, there is no deformation that would be due to circumferential temperature differences or circumferential flow differences. Finally, the helical ribs constitute spacers between the cylindrical walls, for example between the walls 80 and 72 for the annular zone 84 of the third zone 40. The rigidity is thus increased and the distance between the facing walls is kept constant and thus still avoids the axial or circumferential deformations and the circumferential heterogeneities of temperature and flow that would result.

The helical ribs can be made from a round profile (solid or hollow) with a diameter greater than the annular space. This round profile is welded to one of the walls and the opposite portion is truncated, for example by machining so that the profile can be housed in the annular space. However, it is necessary to take into account the differential thermal expansion between the two walls. Tight machining and welding of the profile to the walls would introduce strong thermomechanical stresses. The machining is thus such that it leaves a sufficient clearance between the truncated crown of the rib and the opposite wall (to which the profile is not welded) to absorb the differential thermal expansions. This game induces a leakage flow for the gas. But the laminar nature of the flow in this very small space also contributes significantly to the heating of the gas, which limits the negative effect of this part of the flow whose path is not helical. In a variant, the helical rib is made by machining the wall in which a helical groove is formed. The channel is then closed by point-to-point welding of the complementary wall.

The embodiment in which the wall is machined is more particularly advantageous for rib heights of 0.5 to 1.5 mm whereas a realization using a profile is preferable for rib heights of 1.5. at 4 mm.

In the embodiment described in connection with FIG. 1, two spray chambers 62 and 64 are provided, one for water and the other for hydrocarbon.

In a variant (not shown), only one vaporization chamber is provided. This arrangement is useful in the case where the hydrocarbon is of the liquid type with an evaporation temperature close to that of water, which is the case for example for ethanol. In this case, the mixture of water and ethanol is sprayed into the same chamber and the assembly evaporates and overheats and is then led to the cane 50.

This arrangement can also be used in the case where the fuel or the hydrocarbon would be of gaseous type such as methane or propane. In this case, it is possible to use the gaseous fuel to spray the water into fine droplets and the fuel gas and the water are thus simultaneously obtained by the injector 66.

Claims

REVENDIC-VTIONS

A reaction chamber apparatus (12) in which reactive fluids are introduced to effect a high temperature reaction, said apparatus comprising:

a first substantially cylindrical zone (14) surrounding the reaction chamber in which at least one of the reactants to be introduced into the reaction chamber, with the exception of the reaction products, circulates, this zone being separated from this chamber; reaction so as to recover, at least in part, the heat lost by the reaction chamber and so as to preheat the reagent (s) circulating in the first zone, the reagent (s) being in direct contact with the walls of this first zone for carrying out heat exchange, a second substantially cylindrical zone (16) surrounding the first zone and in which at least one reagent intended to be introduced into the reaction chamber, excluding the products of the reaction, circulates; , the separation between the first and the second zone being such that the reactant (s) circulating in the second zone recover (s) from the heat of the first zone e in order to preheat this reagent or these reagents, which is (are) in direct contact with the walls of this second zone, the assembly being such that the external wall of the device, which is constituted by the external wall of the second zone, or at a temperature substantially lower than the temperature of the reaction chamber, the device being, furthermore, such that the reaction chamber comprises two parts, the first (42, 28) is the seat of the reaction and the second (44) is ) constitutes a channel for evacuation of the products of the reaction, this evacuation channel being of substantially rectilinear configuration in which the products circulate in only one direction, these two parts being such that the heat exchange between the second part of the reaction chamber, the closest to the output of the products of the reaction, and the first zone is substantially larger than the heat exchange between the first portion of the reaction chamber and the first zone.

The device of claim 1 wherein the reaction is a reforming reaction to generate hydrogen from water, hydrocarbon and an oxygenated stream; the water, the hydrocarbon and the oxygenated stream being the reactants of which at least one of them is preheated in the first and / or second zone.

3. Device according to claim 2 wherein only the oxygen flow circulates in the first and second zones and comprises air, especially at low pressure.

4. Device according to one of the preceding claims comprising a third zone (40) inside the second part of the reaction chamber, this third zone being intended to recover heat from this second part of the reaction chamber. in order to preheat reagents or fluids circulating in this third zone, the wall separating the reagents or fluids, on the one hand, and the products of the high temperature reaction, on the other hand, being substantially cylindrical and smooth.

5. Device according to claim 4 for the hydrogen generation by a reforming operation, from liquid hydrocarbon, water and an oxygenated flow, the third zone, inside the second part of the reaction chamber having means for circulating water to preheat, vaporize and superheat, means for vaporizing the liquid hydrocarbon and mixing it with the water vapor, and means for circulation in this third zone and heat exchange with the reaction chamber, allow to overheat the mixture of water vapor and hydrocarbon.

6. Device according to claim 4 for the generation of hydrogen by a reforming operation from gaseous hydrocarbon, water and an oxygenated flow, the third zone, inside the second part of the reaction chamber, comprising means for circulating water to preheat, vaporize and superheat, means for mixing the hydrocarbon gas with the vapor water and means which, by circulation in this third zone and heat exchange with the reaction chamber, allow the mixture of water vapor and hydrocarbon to overheat.

7. Device according to one of the preceding claims comprising:

means for creating fine droplets of liquid of a component to be introduced in gaseous form into the reaction chamber,

means for mixing these droplets with a hot gas also intended to be introduced into the reaction chamber, the temperature of the hot gas allowing the vaporization of at least a fraction of the droplets, and

a hot surface, in particular heated by heat exchange with the reaction chamber, at a temperature sufficient to vaporize the fraction of the non-vaporized droplets by mixing with the hot gas,

the means for creating droplets projecting these droplets towards the hot surface.

8. Device according to one of the preceding claims comprising an annular space, for example in one of the zones, comprising means (130) for ensuring a helical flow of fluid to be introduced into the reaction chamber to homogenize the temperature in this annular space, these helical circulation means being furthermore arranged to perform a spacer function between the walls of this annular space and a heat exchange function in the annular zone where the helical circulation means are located.

9. Device according to one of the preceding claims comprising an injector for generating droplets of a fluid intended to be introduced into the reaction chamber, of small size and high speed for rapid vaporization, the injector being dimensioned for a flow rate substantially greater than the flow rate required for introduction into the reaction chamber, and means for operating this injector intermittently and at a high frequency in order to obtain the desired low flow rate for introduction into the reaction chamber and the desired quality of the droplets.

10. Device according to claim 2 or 3 wherein the reaction chamber has orifices (24) for the quasi-tangential arrival of the oxygenated flow to create a film in the vicinity of the wall (32) of a combustion portion ( 26) of the combustion chamber (12), this film forming a vortex or vortex thereby creating a depression in the vicinity of the axis of the combustion chamber which sucks hydrocarbon fuel vapors and ensures the stabilization of combustion in the vicinity of the axis (30) and at the bottom of the combustion part (26) of the reaction chamber (12).

11. Device according to claim 10 comprising an injector (52) delivering water and hydrocarbons in the combustion chamber (26) against the flow of the products of the reaction so as to perform a rapid mixing of the steam of water and hydrocarbons with the hot gases to propagate the reforming reaction.

12. Device according to claim 11 wherein the reagent supply means comprises means for a portion of the reagents to the bottom of the combustion chamber and the other goes to the reaction chamber.