Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
  • F23C5/00—Disposition of burners with respect to the combustion chamber or to one another; Mounting of burners in combustion apparatus
  • F23C5/08—Disposition of burners
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
  • F23C3/00—Combustion apparatus characterised by the shape of the combustion chamber
  • F23C3/006—Combustion apparatus characterised by the shape of the combustion chamber the chamber being arranged for cyclonic combustion
  • F23C3/008—Combustion apparatus characterised by the shape of the combustion chamber the chamber being arranged for cyclonic combustion for pulverulent fuel
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
  • F23C6/00—Combustion apparatus characterised by the combination of two or more combustion chambers or combustion zones, e.g. for staged combustion
  • F23C6/04—Combustion apparatus characterised by the combination of two or more combustion chambers or combustion zones, e.g. for staged combustion in series connection
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
  • F23C7/00—Combustion apparatus characterised by arrangements for air supply
  • F23C7/02—Disposition of air supply not passing through burner
  • F23C7/04—Disposition of air supply not passing through burner to obtain maximum heat transfer to wall of combustion chamber
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23D—BURNERS
  • F23D1/00—Burners for combustion of pulverulent fuel
  • F23D1/02—Vortex burners, e.g. for cyclone-type combustion apparatus
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23D—BURNERS
  • F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
  • F23D14/20—Non-premix gas burners, i.e. in which gaseous fuel is mixed with combustion air on arrival at the combustion zone
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
  • F23L2900/00—Special arrangements for supplying or treating air or oxidant for combustion; Injecting inert gas, water or steam into the combustion chamber
  • F23L2900/07007—Special arrangements for supplying or treating air or oxidant for combustion; Injecting inert gas, water or steam into the combustion chamber using specific ranges of oxygen percentage
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E20/00—Combustion technologies with mitigation potential
  • Y02E20/34—Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery

Definitions

• the present invention relates to a method of combustion of a fuel and oxidant with a high oxygen content and to a thermal generator using such a method.
• the combustion is therefore very localized and takes place in a minority space in relation to the total volume of the home. This combustion takes place in the form of a flame, which leads to temperature peaks with the formation of thermal NO and a difficult control of thermal fluxes that are intense and localized.
• the present invention proposes to overcome the disadvantages mentioned.
• the invention relates to a combustion process in which a fuel and a oxidizer with a high oxygen content are injected into a furnace, in particular a heat generator, said furnace comprising at least one fuel injection means and at least one wall substantially parallel to the axis of said injection means, characterized in that it comprises:
• the injection at a speed of between 1 and 300 m / s, of an oxidant at a distance from said axis and meeting the fuel in the vicinity of said wall so as to produce a mixture which is distributed over the entire volume of the hearth before going into reaction.
• the injection of the oxidant can be carried out counter-current to the injection of the fuel.
• the injection of the oxidant may be carried out in a helical or circular movement around the axis of the fuel injection means.
• the injection of the oxidant may be carried substantially perpendicular to the axis of the fuel injection means.
• the injection speed of the oxidant may be between 50 and 150 m / s.
• the oxidizing oxidant may be a fluid containing at least 90% oxygen.
• the fuel injection can be performed in the form of a cone.
• the method may comprise a post combustion of the fumes at the exit of the hearth.
• the invention also relates to a heat generator comprising a combustion chamber in which the combustion of a mixture of a fuel and an oxidizing oxidant occurs, said combustion chamber comprising at least one fuel injection means and at least one substantially parallel to the axis of said injection means, characterized in that it comprises at least one means for injecting the fuel in the direction of the wall and at least one means for injecting the oxidant so that it meets the fuel in the vicinity of said wall at a speed of between 1 and 300 m / s so that said fuel and said oxidant are distributed over the entire volume of the furnace before being reacted.
• the fuel injection means may further carry a baffle.
• the fuel injection means can be carried by one of the faces being disposed substantially in the axis of the focus.
• the oxidant injection means may be carried by the other of the faces being disposed at a distance from the axis of the focus and near the wall. At least one oxidant injection means may be carried by the peripheral wall.
• the oxidant injection means may be located remote from the fuel injection means.
• the fuel injection means may be carried by the wall being disposed substantially orthogonal to the axis of the hearth.
• the oxidant injection means may be carried by the wall substantially orthogonal to the axis of the fuel injection means.
• the oxidant injection means may be inclined to obtain a circular or helical movement of the oxidant around the axis of the fuel injection means.
• FIG. 1 is a schematic axial sectional view of a heat generator using the method according to the invention
• FIG. 2 is a diagrammatic view in axial section of a generator variant using the method according to the invention.
• FIG. 3 is a diagrammatic view in axial section of a variant of the generator of FIG. 1; - Figure 4 is a sectional view along the line 4-4 of Figure 3;
• FIG. 5 is a sectional view showing a variant of FIG. 2;
• FIG. 6 is a sectional view along the line 6-6 of FIG. 5 and - Figure 7 is a perspective view with local section showing another embodiment of the invention.
• a heat generator 10 successively comprises a fireplace 20 with heat recovery at the walls, a connection zone 12 between this fireplace and an afterburner zone 14, a complementary heat recovery zone 16 and a zone exhaust and / or treatment 18 fumes from combustion.
• the walls of the generator 10 are advantageously constituted by membrane walls formed by tubes interconnected by fins welded so as to render said walls watertight with respect to the outside.
• These membrane walls preferably have the function of providing heating and / or vaporization of water in the case of steam production.
• Parts of these walls may be covered with insulating materials to limit heat exchange and / or contact of the tubes with locally corrosive atmospheres. Externally, the walls are also covered with insulating materials to limit heat losses.
• the focal point 20 of longitudinal axis XX ' may be of the cylindrical type, as illustrated in the figure, or of any parallelepipedal type.
• This focus comprises a peripheral wall 22, here a horizontal cylindrical wall concentric with the axis XX ', delimited by two substantially vertical lateral faces 24 and 26 which, for reasons of simplification in the following description, are called front face 24 and rear face 26, the rear face being that towards the connection zone 12.
• the front face 24 carries a fuel injection means preferably located in the axis XX 'of the generator and for this reason it is kept the same axis designation for this fuel injection means.
• this injection means is preferably an injector 28, advantageously provided with internal ensuring mixing the fuel with a spray fluid.
• the injector 28 may consist of a rod in which said fuel is transported by a fluid such as steam.
• This injector whose axis coincides with that of the axis of the hearth, is configured in such a way that it projects the fuel from the axis XX 'in the whole hearth, as well towards the center the focus only to the peripheral wall 22 of the fireplace, in the form of a cone as shown by the arrows A so as to distribute the fuel in the entire volume of the fireplace.
• the apex angle of this cone is between 15 and
• 180 ° and preferably between 60 and 150 ° and the injection speed is chosen by those skilled in the art depending on the operating conditions so as to promote good penetration of the fuel droplets in the home.
• the total volume of the hearth is preferably between 0.5 and 50 m3.
• An industrial boiler or a thermal power station may consist of an assembly of fireplaces 20, said foci having or not a common face, and the combustion products generated in these foci pouring into a common zone (s) to several or all of said homes.
• said face may or may not be gas-tight, that is to say be constituted for example by a membrane wall or by non-contiguous tubes.
• liquid fuel such as heavy fuel oil or pitch
• it is preheated to a temperature between 50 and 300 ° C, to obtain a suitable viscosity that allows a good spray of the fuel.
• This spraying can be provided under the sole effect of pressure or with the assistance of an auxiliary spray fluid, such as water vapor.
• an auxiliary spray fluid such as water vapor.
• the fuel is introduced into the generator in spray form with a majority of the mass flow rate having a particle size of less than 500 .mu.m.
• the transport of this fuel and its dispersion are provided by an auxiliary fluid, such as water vapor, the mass ratio between the fuel and the transport fluid being between 0.1 and 10.
• the present invention is not limited to the types of fuels described above but also encompasses the use of gaseous fuels, such as natural gas, refinery fuel oil, etc.
• the rear face 26 carries at least one oxidant oxidant injection means which is either a gas with a very high concentration of oxygen, usually greater than 90%, or pure oxygen.
• This oxidant injection means is an injector 30, preferably tubular and of refractory material, the axis of which is substantially parallel to the axis XX 'while being arranged at a distance from it and, preferably, in the vicinity 22.
• the injection of oxidant can also be assisted by any means, such as by fumes recycled from the dust collector, which has the advantage of accelerating the speed of injection of the oxidant and to promote operation in the reactor stirred the focus 20, limiting the concentration heterogeneities due to the injection of oxygen. It can also be envisaged to assist the injection of oxidant with water vapor which reduces the formation of unburnt solids, such as soot for example.
• the injection speed of the oxidant is between 1 and 300 m / s and more particularly between 50 and 150 m / s.
• the number of oxidizer injectors 30, their locations and the oxidant injection rate will be determined by any means, including numerical simulations, to obtain a significant fuel flow as will be explained in the following description.
• the fuel is injected into said hearth, from the injector 28, in all directions of space and in particular in the direction oxidizer injectors 30, as indicated by the arrows A, so as to ensure interpenetration of the fuel and the oxidant.
• the injection of the oxidant and the injection of the fuel are performed so as to ensure intense turbulence in the entire hearth 20.
• interpenetration it is understood that the direction of the oxidant current is substantially in opposition to that fuel and that the angle formed by the direction of the flow of the oxidant with that of the fuel is between 90 ° and 180 °.
• the oxidant injection is carried out in such a way as to meet this fuel in an extended volume near the wall 22 to create turbulences which will make it possible to obtain a fuel / oxidant mixture in the vicinity of this wall and then extend over the entire section of the fireplace.
• the fuel injection conditions such as initial fuel velocity, spatial fuel distribution, particle size of the droplets or particles, number of injectors, spray or transport fluid flow, as well as the oxidant injection conditions, such as the number of injection points, the oxidizer velocity, the orientation of the jets with respect to the axis of the combustion chamber, the possible flow rate of vector gas, for example recycled steam or fumes, are determined, for example by means of numerical simulations, so that the characteristic time of the turbulent mixing of the fuel remains below the characteristic time of the chemical kinetics. Under these conditions, the reactants and the products are mixed by the turbulence before reacting.
• the hearth 20 functions as a perfectly stirred reactor.
• the temperature and the composition of the fumes are substantially homogeneous throughout the firebox 20. This temperature is, in nominal operation, between 600 and 2000 ° C and preferably between 800 and 1500 0 C in such a way as to limit the formation of NOx linked to any parasitic air inlet or to the nitrogen of the oxidizer.
• the fuel and oxidant flows injected into the furnace 20 are such that a mixture is obtained whose overall stoichiometry is less than 1, that is to say with an excess of fuel with respect to the oxidant. This makes it possible to limit the formation of nitrogen oxides from the constituent nitrogen of the fuel.
• the homogeneity of temperature makes it possible to avoid the formation of thermal NO with the nitrogen coming from possible air inlets in the hearth.
• Oxidant injections can be organized, always with the help of numerical simulation, in order to maintain a slightly oxidizing atmosphere close to the wall, while having a generally rich atmosphere, in order to preserve the wall of reducing corrosion phenomena.
• the connecting zone 12 which is here in tubular form, makes it possible to connect the outlet of the hearth 20 to the post-combustion zone 14 which precedes the heat recovery zone 16 at the outlet of which are evacuated and / or treated. combustion fumes.
• connection zone carries, on its periphery, at least one additional oxidizing oxidizer injector 32 which makes it possible to ensure the mixing of this oxidant with the fumes from the furnace 20.
• This fuel / oxidant mixture then enters the post-combustion zone. combustion 14 where the combustion ends.
• the heat resulting from the combustion in the post-combustion zone is recovered directly in said post-combustion zone, for example by means not shown, such as membrane walls or suspended tubes, or in the heat recovery zone. by all means, such as a heat exchanger 34 or a train of exchangers housed in this recovery zone.
• the fumes from this recovery zone which are generally at a temperature of between 150 and 300 ° C., are directed by zone 18 towards an evacuation and / or treatment means, for example a dust collector and a chimney (not shown in the figure).
• an evacuation and / or treatment means for example a dust collector and a chimney (not shown in the figure).
• FIG. 2 shows a variant of Figure 1 and which has for this the same references as this figure.
• the fuel injection is via an injector 28, carried by the front face 24, extending inside the home 20 in the form of a cane.
• This rod 28 whose axis is also coincident with the axis XX 'of the hearth 20, carries at its end a deflector 36 whose role is to transform the fuel jets coming out of the cane into jets directed towards the peripheral wall 22 of the hearth 20 and to its front face 24.
• the fuel may be a solid, liquid or gaseous fuel and the injection may be assisted or not.
• this rod is cooled either by a fluid, such as water, or by the fuel mixture / fluid assistance.
• the oxidant injection means is an injector 30, or a series of injectors spaced axially along the axis of the hearth, which is disposed on the peripheral horizontal wall 22 of the hearth 20.
• the fuel injection conditions such as the initial fuel velocity, the spatial distribution of the fuel, the particle size of the droplets or the particles, the number of injectors, the flow rate of the spray or transport fluid , as well as the oxidant injection conditions, such as the number of injection points, the oxidizer velocity, the orientation of the jets with respect to the axis of the furnace, the possible flow rate of carrier gas, for example steam or fumes recycled, are determined, for example by means of numerical simulations, so that the characteristic time of the turbulent mixture remains below the characteristic time of the chemical kinetics.
• the fuel injection conditions such as the initial fuel velocity, the spatial distribution of the fuel, the particle size of the droplets or the particles, the number of injectors, the flow rate of the spray or transport fluid , as well as the oxidant injection conditions, such as the number of injection points, the oxidizer velocity, the orientation of the jets with respect to the axis of the furnace, the possible flow rate of carrier gas, for example steam or fumes recycled, are determined, for example by means of numerical
• the fuel is injected into said furnace 20, from the injector 28, in all the directions of space and in particular towards the oxidizer injectors 30, as indicated by the arrows A, so as to ensure interpenetration of fuel and oxidant.
• the not completely burned fuel leaves the hearth 20 to cross the connection zone 12 where it completes its combustion in the zone 14 through additional oxidizer injectors 32 as previously described.
• FIGS 3 and 4 show a variant of Figure 1 and which include, for reasons of clarity, the same references as this figure.
• the fuel is injected into the furnace 20 and towards the oxidizer injectors 30, by a fuel injector 28 carried by the front face 24 and axis coincident with that of the focus.
• This injector is configured in such a way that it generates, at its exit, a cone 38 of fuel.
• the apex angle of this cone is between 15 and
• 180 ° and preferably between 60 and 150 ° and the operating conditions of the injector are determined, for example by numerical simulation, so as to promote a good distribution of the fuel throughout the focus 20 and a good interpenetration of the fuel and the fuel. oxidizer.
• This cone can be achieved by an injector projecting a multiplicity of jets inclined relative to the axis XX 'forming a cone whose peripheral surface of said cone is of revolution with respect to XX'.
• oxidizer injectors 30 regularly distributed circumferentially on the rear face 26. These injectors are inclined, that is to say that their axes are axially parallel to the XX 'axis but are slightly offset radially relative to this axis so as to create, in the focus 20, a turbulent flow of the oxidizer which develops, in a helical movement of the oxidant, towards the front face 24..
• the oxidant is injected into the hearth in a helical movement coaxial with the axis XX 'of the fuel injector, as shown by the arrows D on the FIGS.
• the oxidant promotes mixing between the fuel and the oxidant inside the fireplace 20 through the circulation of the oxidizer which creates turbulence causing a mixing of the fuel with the oxidizer and which will provide a comburent / fuel mixture occupying any the section of the hearth.
• the connecting zone 12 carries at least one additional oxidizing oxidizer injector 32 which makes it possible to mix this oxidant with the fumes from the furnace 20, this fuel / oxidant mixture then penetrating in the post-combustion zone 14 to complete the combustion.
• the fuel is also injected into the hearth 20 in the form of a fuel cone 38.
• This cone of fuel results from the action of the deflector 36 which generates this cone whose base is opposite the front face 24.
• the injectors 30 or the series of injectors are distributed circumferentially around the peripheral wall 22 and are inclined so as to introduce the oxidizer tangentially into the hearth 20.
• it creates a circular movement of the oxidant around the axis XX ', as shown by the arrows E in Figure 6.
• it can be expected to shift the axes of the injectors 30 in the axial direction towards the rear face 26, as shown in dotted line in Figure 5, so that the movement of the oxidant is helical.
• this provision aims to promote the interpenetration of fuel and oxidant.
• This oxidizer which is injected circularly or helically, encounters the fuel near the wall 22 by mixing with it and generating a mixture that develops over the entire focus.
• the combustion can develop on a large volume of the hearth 20.
• the unused fuel leaves the furnace 20 through the connecting zone 12 where it completes its combustion through additional oxidizer injectors 32 as previously described.
• FIG. 7 shows another embodiment of the invention and which comprises the references of the previously described examples increased by the index 100.
• a heat generator 110 comprises a furnace 120, a connection zone 112, a heat recovery zone 116 and a discharge and / or treatment zone 118 of the flue gases from the combustion.
• the generator comprises a focal point 120 of longitudinal axis XX 'which may be of cylindrical or substantially parallelepipedal shape.
• the hearth is of rectangular parallelepipedal shape whose peripheral wall 122 is formed of a succession of walls around the axis.
• This succession of walls comprises vertical walls 140 and 142 and upper horizontal walls 144 and lower 146.
• the generator also comprises a front face 124 and a rear face 126.
• the vertical wall 142 carries at least one fuel injector 128 of axis ZZ 'substantially perpendicular to the axis XX' of the hearth 120 and the horizontal wall 144 carries at least one oxidizer injector 130 in a manner such that the axis the oxidizer injector is substantially perpendicular to the axis ZZ 'of the fuel injector. It is at the intersection of the horizontal upper wall 144 and the vertical wall 142 that is located the connection zone 112 and more particularly in the right part of the generator as shown in this figure.
• the hearth may also be subdivided into watertight compartments or not, through walls, which may be for example membranées walls, substantially parallel to the two vertical faces 124, 126 which close the two ends of the hearth. This provision is intended to limit the volume of each unit hearth to less than 50 m3 as indicated above.
• the fuel injector 128 of axis ZZ ' projects the fuel into the hearth 120 in very open jets (arrow A) so as to ensure a good distribution of the fuel throughout the hearth 120 and a good interpenetration of the fuel and the oxidant .
• a substantially horizontal row of fuel injectors spaced regularly from each other and that along the axis XX 'of the hearth.
• the injectors may also be used according to other arrangements, such as staggered, for example, and / or inclined relative to the wall 142.
• the oxidizer injector 130 is located on the upper horizontal wall 144.
• a row of oxidizer injectors 130 regularly spaced along the axis XX 'whose positions are in concordance or not with those of the row of fuel injectors.
• the fuel is injected into the furnace 120, from the injector 128, in all the directions of the space and in particular towards the oxidizer injectors 30, as indicated by the arrows A, so as to ensure interpenetration of the fuel and the oxidant near the walls 140, 144, 146 to mix and then occupy the entire section of the hearth. Then, the fumes resulting from the combustion leave the hearth 120 through the connecting zone 112 to reach the heat recovery zone 116. It may be noted that, thanks to this arrangement of injectors, the whole hearth is at a homogeneous temperature.
• the walls of the hearth 120 are advantageously constituted by membranous walls formed by tubes connected together by fins welded so as to render said walls watertight with respect to the outside. Parts of these walls may be covered with insulating materials to limit heat exchange and / or contact of the tubes with locally corrosive atmospheres. The walls are also externally covered with insulating materials to limit heat losses.
• the combustion zone occupies the entire hearth due to a very strong turbulence generated by the oxidant injection.
• this turbulence may also be possible to increase this turbulence by fuel injection while ensuring a distribution of this fuel as homogeneous as possible over the entire home. To do this, it acts, as described above, on the fuel injection conditions and possibly the oxidant to obtain an adequate particle size distribution so as to have small fuel droplets that vaporize near the injection point fuel and larger droplets that spread the fuel along the entire path

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• 2004
  • 2004-07-07 FR FR0407514A patent/FR2872887B1/fr not_active Expired - Fee Related
• 2005
  • 2005-07-07 EP EP05788679A patent/EP1766289A1/de not_active Withdrawn
  • 2005-07-07 WO PCT/FR2005/001762 patent/WO2006013290A1/fr active Application Filing
  • 2005-07-07 US US11/571,699 patent/US20080131823A1/en not_active Abandoned

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