EP0809067A1 - Process and installation for reducing by recombustion of nitric oxides in exhaust gases from a primary combustion in a furnace - Google Patents

Process and installation for reducing by recombustion of nitric oxides in exhaust gases from a primary combustion in a furnace Download PDF

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Publication number
EP0809067A1
EP0809067A1 EP97400984A EP97400984A EP0809067A1 EP 0809067 A1 EP0809067 A1 EP 0809067A1 EP 97400984 A EP97400984 A EP 97400984A EP 97400984 A EP97400984 A EP 97400984A EP 0809067 A1 EP0809067 A1 EP 0809067A1
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Prior art keywords
zone
fuel
recombustion
pressure
combustion
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German (de)
French (fr)
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EP0809067B1 (en
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Thierry Ferlin
Jean-Charles Joigneault
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Engie SA
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Gaz de France SA
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    • 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
    • F23C6/045—Combustion apparatus characterised by the combination of two or more combustion chambers or combustion zones, e.g. for staged combustion in series connection with staged combustion in a single enclosure
    • F23C6/047—Combustion apparatus characterised by the combination of two or more combustion chambers or combustion zones, e.g. for staged combustion in series connection with staged combustion in a single enclosure with fuel supply in stages
    • 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 
    • F23C2201/00—Staged combustion
    • F23C2201/10—Furnace staging
    • F23C2201/101—Furnace staging in vertical direction, e.g. alternating lean and rich zones

Definitions

  • the invention relates to a process for reduction by recombination, nitrogen oxides contained in the fumes from primary combustion produced in an oven, as well as an installation for the implementation of this process.
  • This process consists in injecting a hydrocarbon according to very precise operating conditions, downstream of a first combustion during which the nitrogen oxides are produced.
  • the purpose of injecting this hydrocarbon is to create a reducing atmosphere which has the consequence, when the temperature is sufficiently high (generally above 1000 ° C.), of cracking the components of the hydrocarbon and of producing radicals (CH ° , H °, ..) which will combine with nitrogen monoxide and the other precursors of nitrogen oxides from the main combustion (first combustion) by complex chemical transformations to form molecular nitrogen and oxygen.
  • the zone in which the injection of this hydrocarbon is carried out is called the reduction or overcombustion zone.
  • the unburnt materials formed in the reductive overcombustion zone are then oxidized in a third step known as post-combustion.
  • the hydrocarbon which will supply the radicals necessary for the destruction of nitrogen oxides, is thus used both as a reactive depollution agent and as energy.
  • the efficiency of a recombustion process depends on many factors such as the temperature, the residence time in the recombustion zone, the nature and mode of injection of the hydrocarbon, the quantity of hydrocarbon injected, the rate initial nitrogen oxides, etc.
  • the recombination process of the prior art described above only achieves efficiency rates for the reduction of nitrogen oxides of the order of 50 to 60%.
  • the rate of effectiveness of the reduction of nitrogen oxides corresponds to the ratio of the number of moles of nitrogen oxides destroyed by the recombination / number of moles of nitrogen oxides before the recombustion.
  • the present invention aims to overcome the above drawbacks by ensuring better penetration and distribution of the fuel in the combustion zone and thus obtaining satisfactory nitrogen oxide reduction rates even when the dimensions of the furnace do not did not allow a good mixture of fuel and fumes, as in the process of the prior art.
  • the invention proposes a process for reducing the nitrogen oxides contained in the fumes from primary combustion, in an oven, by recombination of said fumes characterized by an injection of fuel into the recombustion zone of said oven according to at least two jets associated with relatively high and relatively low pressure respectively.
  • the low pressure fuel jet is externally concentric with the higher pressure fuel jet.
  • the fuel is a gas at a pressure of between a few millibars and a few hundred millibars for the low pressure jet and between a few hundred millibars and a few bars for the high pressure jet.
  • the pressure and the gas flow rates of the two above-mentioned jets are controlled so as to adapt to the dimensions of the combustion zone and to the characteristics of the fumes.
  • furnace's recombustion zone is subjected to acoustic waves.
  • the above-mentioned acoustic waves have a frequency of less than about 20 Hz.
  • the invention also provides an installation for implementing the method described above comprising an oven equipped with a primary combustion zone supplied by a main fuel and followed by a recombustion zone supplied by a secondary fuel, characterized in that that said recombustion zone is provided with at least two secondary fuel inlets at different pressures.
  • the two aforementioned inputs are coaxial.
  • the two aforementioned inlets are respectively provided with a device for controlling the flow rate and the pressure of the secondary fuel forming the two aforementioned jets.
  • the installation according to the invention has an acoustic wave generator mounted on the wall of the furnace so as to be able to homogenize the mixture in the recombustion zone.
  • One of the problems encountered during the implementation of the recombination process of the prior art resides in the mixing of the fuel (natural gas or any other hydrocarbon used) with the fumes containing the nitrogen oxides originating from the combustion zone and arriving in the recombustion zone. Indeed, a good homogenization of the fuel and the fumes in the recombustion zone is essential from the point of view of the temperature and mass exchanges. In fact, if there are flow zones where the radicals (CH °, etc.) are not produced and diffused, no destruction of the nitrogen oxides will take place in these zones.
  • the temperature must be sufficient to crack the radicals which will react with the nitrogen oxides to give molecular nitrogen and oxygen.
  • hydrocarbon used is dispersed and cracked as quickly as possible. Otherwise, the hydrocarbon (fuel) will burn with the residual oxygen from the fumes from the main combustion and create nitrogen oxides which is contrary to the desired goal.
  • the homogenization of the mixture is all the more difficult to obtain that the dimensions of the furnace are large and that the volume of fuel injected represents only about 1% of the volume of the fumes of the main combustion.
  • the homogenization of the fuel and smoke mixture is often limited by the residence time of the fuel-smoke mixture in the combustion zone. Indeed, this residence time is limited by the dimensions of the oven which are most often limited in height.
  • FIG. 1 a combustion oven for implementing the process for reducing nitrogen oxides according to the invention is illustrated in FIG. 1.
  • This oven has the three combustion zones mentioned above, that is to say say a first zone A of main combustion, a second zone B of recombustion and a third zone C of post-combustion. Above the post-combustion zone, there is a gas cooling zone D.
  • the main combustion zone A comprises supply orifices 3 for a mixture of a so-called fuel primary fuel and air.
  • the primary fuel can be of any kind: coal, fuel oil, waste, wood, natural gas, etc.
  • the primary fuel will be natural gas.
  • the aeration rate of this main combustion zone i.e., the ratio of the actual combustion air volume to the theoretical combustion air (stoichiometric combustion) generally varies in the range of 1.05 at 1.1.
  • the nitrogen oxides contained in the fumes from this primary combustion are then reduced in zone B of reductive combustion or overcombustion.
  • the reduction of nitrogen oxides is achieved by injecting a fuel called secondary fuel by the feed marked 2 in FIG. 1.
  • the secondary fuel is injected through inlet 2 in a volume representing 10 to 20% of the volume of the primary fuel, in order to obtain a ventilation rate close to 0.9 in zone B.
  • the secondary fuel used for the recombustion injected into the reducing zone B can, like the primary fuel, be of any kind: coal, fuel oil, waste, wood, natural gas, etc. However, according to the invention, natural gas is preferably used.
  • the oxidation stage of unburnt materials is called the post-combustion stage, and is then carried out.
  • the post-combustion stage is carried out thanks to the introduction, by the inlet marked 1 in FIG. 1, of air to complete the combustion.
  • the injection of the secondary fuel, preferably natural gas, into the recombustion zone B must be carried out in a temperature range between 1100 and 1500 ° C. and it must be carried out at a corresponding flow rate and pressure.
  • sufficient residence time in the recombination zone to allow satisfactory homogenization of the fuel-smoke mixtures as well as to allow reduction reactions to take place.
  • the residence time must generally be of the order of 0.5 to 1 second depending on the operating conditions.
  • the reduction temperature used for the recombustion step, in the recombustion zone B, can be lowered to approximately 1000 ° C. but it is then necessary to increase the residence time.
  • a balance must therefore be found between the residence time-temperature parameters, in order to obtain a satisfactory homogenization between the secondary fuel used in zone B of combustion and the fumes from zone A of primary or main combustion containing the oxides d nitrogen to reduce.
  • the secondary fuel behaves like a jet in a transverse flow and the homogenization of a mixture of a jet (secondary fuel) in a transverse flow (fumes from primary combustion) is subject to antagonistic constraints, d 'all the more difficult as the volume flow rate of the jet on the wall of the furnace is low compared to the main transverse flow.
  • the present invention consists in injecting the secondary fuel, preferably natural gas, via a system with several pulses. More particularly, in the installation illustrated in FIG. 1, the secondary fuel is injected by a double pulse system into the recombustion zone.
  • the secondary fuel preferably natural gas
  • the double pulse injection according to the invention has two gas supply circuits 2, 2 ′, a low pressure supply circuit 2 ′, adjusted and controlled by any suitable means noted 4 in FIG. 1, and a high pressure gas supply circuit 2 adjusted and controlled by any suitable means noted 5 in FIG. 1.
  • the double pulse makes it possible to improve the penetration of the jet of secondary fuel up to the center of the oven and also to distribute this fuel throughout the oven enclosure.
  • the central high pressure jet also entrains part of the fuel injected at lower pressure, which also improves its mixing.
  • This double pulse of gaseous fuel can be very easily adjusted, the variations in flow rate and pressure of the gaseous fuel are very easy to achieve in order to optimize the mixture, that is to say in order to adapt to the dimensions of the combustion zone, to the characteristics of the smoke, and at the desired reduction rates.
  • the two inlets 2, 2 ′ of the secondary fuel are coaxial and the inlet of the low pressure fuel is externally concentric with the inlet of the high pressure fuel.
  • the invention is therefore particularly advantageous in cases in which the dimensions of the furnace do not allow good mixing of the fuel in the flue gases, in particular.
  • the invention also makes it possible, by improving the mixture, to reduce the quantities of secondary fuel to be injected in order to obtain a given rate of reduction of nitrogen oxides.
  • the nitrogen reduction rates obtained are of the order of 50 to 60% in moles, by substituting, for coal, 20% in energy supply of natural gas.
  • an infrasound generator denoted 6 in FIG. 1 appended is mounted on one of the walls of the combustion furnace at the level of the recombination zone B.
  • the reduction rate of nitrogen oxides contained in the fumes from primary combustion is generally greater than 80%, more precisely in the range of about 80 to about 90%, in moles.
  • the process for reducing nitrogen oxides by recombining the fumes from primary combustion therefore makes it possible to achieve an NOx reduction efficiency of the order of 70 to 80% by performing the injection.
  • secondary fuel preferably natural gas, in the combustion zone, following at least two jets associated with relatively high and relatively low pressure respectively.
  • the low pressure fuel jet is externally concentric with the higher pressure fuel jet, which improves the penetration of the secondary fuel to the center of the furnace thanks to the high pressure jet and also distributes the gas throughout the enclosure.
  • the central high-pressure jet entraining part of the gas injected at a lower pressure, the mixture of the gaseous secondary fuel with the fumes of the primary combustion containing the nitrogen oxide to be reduced is thus improved.
  • the gaseous fuel is injected for the low pressure jet at a pressure between a few millibars and a few hundred millibars and for the high pressure jet, between a few hundred millibars and a few bars.
  • the acoustic waves used have a frequency of less than about 20 Hz.
  • the use of multiple pulse injection and the production of infrasound in the nitrogen oxides recombination process makes it possible to achieve NOx reduction efficiency rate of around 50% but using less fuel.
  • the reduction in the quantity of secondary fuel is of the order of 50% by volume, which makes it possible to reduce the cost of the process.
  • a method and a device comprising a double-pulse injection have been described, devices and methods using a multiple-pulse injection of the secondary fuel in the recombination zone can be used.
  • a triple pulse injection of the secondary fuel can be envisaged, in which the gaseous fuel will be injected according to two high pressure jets concentric with one another and a low pressure jet concentrically external to the two high pressure jets.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Incineration Of Waste (AREA)

Abstract

The reduction of oxides of nitrogen contained in furnace smoke is carried out by recombustion of the smoke, using a secondary fuel injected into a recombustion zone in at least two jets at relatively high and relatively low pressure respectively. The low-pressure jet is situated outside and concentrically with the high-pressure jet. The secondary fuel is a gas at a pressure of a few millibars to a few hundred millibars for the low pressure jet, and a few hundred millibars to a few bars to the high-pressure one. The pressure and flow of the gas in the two jets are regulated according to the dimensions of the recombustion zone and the characteristics of the smoke. The recombustion zone is also subjected to acoustic waves at a frequency of below some 32 Hz. The procedure is carried out in a recombustion zone (B) fed with secondary fuel through two coaxial inlets (2,2') equipped with pressure regulators (4,5). One wall of the recombustion zone is equipped with an acoustic wave generator (6) to homogenise the mixture inside the zone.

Description

L'invention concerne un procédé de réduction par recombustion, des oxydes d'azote contenus dans les fumées issues d'une combustion primaire réalisés dans un four, ainsi qu'une installation pour la mise en oeuvre de ce procédé.The invention relates to a process for reduction by recombination, nitrogen oxides contained in the fumes from primary combustion produced in an oven, as well as an installation for the implementation of this process.

On sait que la combustion de combustibles de toute nature est à l'origine de la production d'oxydes d'azote par réaction avec l'air, en quantité plus ou moins importante selon le type du combustible et les conditions de la combustion. Ces oxydes d'azote émis dans l'atmosphère sont la cause de diverses pollutions. Ils contribuent notamment à la formation des pluies acides. Par ailleurs, combinés avec le monoxyde de carbone et les composés organiques volatils présents dans l'atmosphère , ils produisent de l'ozone troposphérique qui est à l'origine de l'augmentation des affections respiratoires (asthme, insuffisance respiratoire, etc.).It is known that the combustion of fuels of all kinds is at the origin of the production of nitrogen oxides by reaction with air, in more or less quantity depending on the type of fuel and the conditions of combustion. These nitrogen oxides emitted into the atmosphere are the cause of various types of pollution. They notably contribute to the formation of acid rain. In addition, combined with carbon monoxide and volatile organic compounds present in the atmosphere, they produce tropospheric ozone which is at the origin of the increase of respiratory affections (asthma, respiratory insufficiency, etc.).

Il est donc important de réduire ou d'éliminer ces oxydes d'azote.It is therefore important to reduce or eliminate these nitrogen oxides.

Dans ce but, on connaît un procédé dit de recombustion ou de surcombustion réductrice.For this purpose, a process known as reductive combustion or overcombustion is known.

Ce procédé consiste à injecter un hydrocarbure selon des conditions opératoires très précises, en aval d'une première combustion au cours de laquelle les oxydes d'azote sont produits. L'injection de cet hydrocarbure a pour but de créer une atmosphère réductrice qui a pour conséquence, lorsque la température est suffisamment élevée (généralement supérieure à 1000°C), de craquer les composants de l'hydrocarbure et de produire des radicaux (CH°, H°, ..) qui vont se combiner avec le monoxyde d'azote et les autres précurseurs des oxydes d'azote issus de la combustion principale (première combustion) par des transformations chimiques complexes pour former de l'azote moléculaire et de l'oxygène. La zone dans laquelle l'injection de cet hydrocarbure est effectuée est appelée zone de recombustion ou de surcombustion réductrice.This process consists in injecting a hydrocarbon according to very precise operating conditions, downstream of a first combustion during which the nitrogen oxides are produced. The purpose of injecting this hydrocarbon is to create a reducing atmosphere which has the consequence, when the temperature is sufficiently high (generally above 1000 ° C.), of cracking the components of the hydrocarbon and of producing radicals (CH ° , H °, ..) which will combine with nitrogen monoxide and the other precursors of nitrogen oxides from the main combustion (first combustion) by complex chemical transformations to form molecular nitrogen and oxygen. The zone in which the injection of this hydrocarbon is carried out is called the reduction or overcombustion zone.

Les imbrûlés formés dans la zone de surcombustion réductrice sont ensuite oxydés dans une troisième étape dite de post-combustion. L'hydrocarbure qui va fournir les radicaux nécessaires à la destruction des oxydes d'azote, est ainsi utilisé à la fois comme agent réactif de dépollution et comme énergie.The unburnt materials formed in the reductive overcombustion zone are then oxidized in a third step known as post-combustion. The hydrocarbon which will supply the radicals necessary for the destruction of nitrogen oxides, is thus used both as a reactive depollution agent and as energy.

Le procédé de recombustion comporte donc trois étapes :

  • une première étape dite de combustion principale ou primaire effectuée dans une première zone d'un four de combustion, dite zone de combustion principale ou primaire. Cette étape correspond à l'étape proprement dite de combustion des combustibles, étape au cours de laquelle les oxydes d'azote se forment et sont entraînés dans les fumées;
  • une deuxième étape dite de recombustion ou de surcombustion réductrice effectuée dans une deuxième zone, dite zone de recombustion ou de surcombustion réductrice, du four de combustion lui-même.
The recombustion process therefore comprises three stages:
  • a first stage called main or primary combustion carried out in a first zone of a combustion furnace, said zone of main or primary combustion. This stage corresponds to the stage proper of combustion of fuels, stage during which nitrogen oxides are formed and are entrained in the fumes;
  • a second stage known as reductive combustion or overcombustion carried out in a second zone, known as reductive combustion or overcombustion zone, of the combustion furnace itself.

Dans cette étape, un combustible dit combustible secondaire est injecté dans la zone de recombustion pour réduire les oxydes d'azote contenus dans les fumées issues de la combustion principale; et

  • une troisième étape dite de post-combustion effectuée dans une troisième zone du four de combustion en aval de la zone de recombustion, consistant à injecter de l'air dans cette troisième zone pour achever la combustion.
In this step, a fuel called secondary fuel is injected into the combustion zone to reduce the nitrogen oxides contained in the fumes from the main combustion; and
  • a third step called post-combustion carried out in a third zone of the combustion furnace downstream of the recombustion zone, consisting in injecting air into this third zone to complete the combustion.

L'efficacité d'un procédé de recombustion dépend de nombreux facteurs tels que la température, le temps de séjour dans la zone de recombustion, la nature et le mode d'injection de l'hydrocarbure, la quantité d'hydrocarbure injectée, le taux d'oxydes d'azote initial, etc.The efficiency of a recombustion process depends on many factors such as the temperature, the residence time in the recombustion zone, the nature and mode of injection of the hydrocarbon, the quantity of hydrocarbon injected, the rate initial nitrogen oxides, etc.

Mais, le procédé de recombustion de l'art antérieur décrit ci-dessus ne permet d'atteindre que des taux d'efficacité de la réduction des oxydes d'azote de l'ordre de 50 à 60%. Le taux d'efficacité de la réduction des oxydes d'azote correspond au rapport du nombre de moles d'oxydes d'azote détruits par la recombustion/nombre de moles d'oxydes d'azote avant la recombustion.However, the recombination process of the prior art described above only achieves efficiency rates for the reduction of nitrogen oxides of the order of 50 to 60%. The rate of effectiveness of the reduction of nitrogen oxides corresponds to the ratio of the number of moles of nitrogen oxides destroyed by the recombination / number of moles of nitrogen oxides before the recombustion.

Or, les études théoriques de cinétique montrent que si le mélange du combustible introduit dans la zone de recombustion et des fumées issues de la zone de combustion principale était parfaitement homogène on pourrait atteindre une efficacité de réduction des oxydes d'azote de près de 90%.However, theoretical kinetic studies show that if the mixture of the fuel introduced into the combustion zone and the fumes from the main combustion zone were perfectly homogeneous, an efficiency of reduction of nitrogen oxides could be reached of almost 90%. .

La présente invention a pour but de pallier les inconvénients précédents en permettant d'assurer une meilleure pénétration et répartition du combustible dans la zone de recombustion et ainsi d'obtenir des taux de réduction des oxydes d'azote satisfaisants même lorsque les dimensions du four ne permettaient pas un bon mélange du combustible et des fumées, comme dans le procédé de l'art antérieur.The present invention aims to overcome the above drawbacks by ensuring better penetration and distribution of the fuel in the combustion zone and thus obtaining satisfactory nitrogen oxide reduction rates even when the dimensions of the furnace do not did not allow a good mixture of fuel and fumes, as in the process of the prior art.

Ces buts sont atteints par l'invention qui propose un procédé de réduction des oxydes d'azote contenus dans les fumées issues d'une combustion primaire, dans un four, par recombustion desdites fumées caractérisé par une injection de combustible dans la zone de recombustion dudit four suivant au moins deux jets associés à pression relativement haute et relativement basse respectivement.These objects are achieved by the invention which proposes a process for reducing the nitrogen oxides contained in the fumes from primary combustion, in an oven, by recombination of said fumes characterized by an injection of fuel into the recombustion zone of said oven according to at least two jets associated with relatively high and relatively low pressure respectively.

Plus précisément dans ce procédé le jet de combustible basse pression est extérieurement concentrique au jet de combustible à pression plus élevée.More precisely in this process the low pressure fuel jet is externally concentric with the higher pressure fuel jet.

De préférence, selon l'invention le combustible est un gaz à une pression comprise entre quelques millibars et quelques centaines de millibars pour le jet basse pression et entre quelques centaines de millibars et quelques bars pour le jet haute pression.Preferably, according to the invention, the fuel is a gas at a pressure of between a few millibars and a few hundred millibars for the low pressure jet and between a few hundred millibars and a few bars for the high pressure jet.

Egalement selon l'invention, la pression et les débits du gaz des deux jets précités sont commandés de façon à s'adapter aux dimensions de la zone de recombustion et aux caractéristiques des fumées.Also according to the invention, the pressure and the gas flow rates of the two above-mentioned jets are controlled so as to adapt to the dimensions of the combustion zone and to the characteristics of the fumes.

De plus, la zone de recombustion du four est soumise à des ondes acoustiques.In addition, the furnace's recombustion zone is subjected to acoustic waves.

De préférence, les ondes acoustiques précitées ont une fréquence inférieure à environ 20 Hz.Preferably, the above-mentioned acoustic waves have a frequency of less than about 20 Hz.

L'invention propose également une installation pour la mise en oeuvre du procédé décrite ci-dessus comprenant un four équipé d'une zone de combustion primaire alimentée par un combustible principal et suivie par une zone de recombustion alimentée par un combustible secondaire, caractérisée en ce que ladite zone de recombustion est munie d'au moins deux entrées de combustible secondaire à des pressions différentes.The invention also provides an installation for implementing the method described above comprising an oven equipped with a primary combustion zone supplied by a main fuel and followed by a recombustion zone supplied by a secondary fuel, characterized in that that said recombustion zone is provided with at least two secondary fuel inlets at different pressures.

Plus précisément, les deux entrées précitées sont coaxiales.More specifically, the two aforementioned inputs are coaxial.

Selon l'invention, les deux entrées précitées sont respectivement munies d'un appareil de commande du débit et de la pression du combustible secondaire formant les deux jets précités.According to the invention, the two aforementioned inlets are respectively provided with a device for controlling the flow rate and the pressure of the secondary fuel forming the two aforementioned jets.

De plus, l'installation selon l'invention a un générateur d'ondes acoustiques monté sur la paroi du four de façon à pouvoir homogénéiser le mélange dans la zone de recombustion.In addition, the installation according to the invention has an acoustic wave generator mounted on the wall of the furnace so as to be able to homogenize the mixture in the recombustion zone.

L'invention sera mieux comprise et d'autres buts, caractéristiques, détails et avantages de celle-ci apparaîtront plus clairement au cours de la description explicative qui va suivre et qui est faite en référence au dessin unique annexé qui représente un mode de réalisation préféré d'un four dans lequel on effectue l'ensemble des opérations ci-dessus décrites de combustion principale, recombustion et post-combustion.The invention will be better understood and other objects, characteristics, details and advantages thereof will appear more clearly during the explanatory description which follows and which is made with reference to the single appended drawing which represents a preferred embodiment. of an oven in which all of the above-described operations of main combustion, recombustion and post-combustion are carried out.

Un des problèmes rencontrés lors de la mise en oeuvre du procédé de recombustion de l'art antérieur réside dans le mélange du combustible (gaz naturel ou tout autre hydrocarbure employé) avec les fumées contenant les oxydes d'azote issus de la zone de combustion et parvenant dans la zone de recombustion. En effet, une bonne homogénéisation du combustible et des fumées, dans la zone de recombustion est indispensable du point de vue de la température et des échanges massiques. En effet s'il existe des zones d'écoulements où les radicaux (CH°, etc...) ne sont produits et diffusés, aucune destruction des oxydes d'azote n'aura lieu dans ces zones.One of the problems encountered during the implementation of the recombination process of the prior art resides in the mixing of the fuel (natural gas or any other hydrocarbon used) with the fumes containing the nitrogen oxides originating from the combustion zone and arriving in the recombustion zone. Indeed, a good homogenization of the fuel and the fumes in the recombustion zone is essential from the point of view of the temperature and mass exchanges. In fact, if there are flow zones where the radicals (CH °, etc.) are not produced and diffused, no destruction of the nitrogen oxides will take place in these zones.

De même, il faut qu'en tout point du mélange la température soit suffisante pour craquer les radicaux qui vont réagir avec les oxydes d'azote pour donner de l'azote moléculaire et de l'oxygène.Likewise, at any point in the mixture, the temperature must be sufficient to crack the radicals which will react with the nitrogen oxides to give molecular nitrogen and oxygen.

Par ailleurs il est crucial que l'hydrocarbure utilisé soit le plus rapidement possible dispersé et craqué. Dans le cas contraire, l'hydrocarbure (combustible) va brûler avec l'oxygène résiduel des fumées issues de la combustion principale et, créer des oxydes d'azote ce qui est contraire au but recherché.Furthermore, it is crucial that the hydrocarbon used is dispersed and cracked as quickly as possible. Otherwise, the hydrocarbon (fuel) will burn with the residual oxygen from the fumes from the main combustion and create nitrogen oxides which is contrary to the desired goal.

L'homogénéisation du mélange est d'autant plus délicate à obtenir que les dimensions du four sont importantes et que le volume de combustible injecté ne représente que environ 1% du volume des fumées de la combustion principale.The homogenization of the mixture is all the more difficult to obtain that the dimensions of the furnace are large and that the volume of fuel injected represents only about 1% of the volume of the fumes of the main combustion.

De plus, l'homogénéisation du mélange du combustible et des fumées est souvent limitée par le temps de séjour du mélange combustible-fumées dans la zone de recombustion. En effet, ce temps de séjour est limité par les dimensions du four qui sont le plus souvent limitées en hauteur.In addition, the homogenization of the fuel and smoke mixture is often limited by the residence time of the fuel-smoke mixture in the combustion zone. Indeed, this residence time is limited by the dimensions of the oven which are most often limited in height.

A titre d'exemple, un four de combustion pour la mise en oeuvre du procédé de réduction des oxydes d'azote selon l'invention est illustré en figure 1. Ce four comporte les trois zones de combustion citées précédemment, c'est-à-dire une première zone A de combustion principale, une seconde zone B de recombustion et une troisième zone C de post-combustion. Au-dessus de la zone de post-combustion, il existe une zone D de refroidissement des gaz.By way of example, a combustion oven for implementing the process for reducing nitrogen oxides according to the invention is illustrated in FIG. 1. This oven has the three combustion zones mentioned above, that is to say say a first zone A of main combustion, a second zone B of recombustion and a third zone C of post-combustion. Above the post-combustion zone, there is a gas cooling zone D.

La zone de combustion principale A comporte des orifices d'alimentation 3 d'un mélange d'un combustible dit combustible primaire et d'air. Le combustible primaire peut être de toute nature : charbon, fioul, déchets, bois, gaz naturel, etc...The main combustion zone A comprises supply orifices 3 for a mixture of a so-called fuel primary fuel and air. The primary fuel can be of any kind: coal, fuel oil, waste, wood, natural gas, etc.

De préférence dans l'invention, le combustible primaire sera du gaz naturel.Preferably in the invention, the primary fuel will be natural gas.

Le taux d'aération de cette zone de combustion principale c'est-à-dire, le rapport du volume d'air réel de combustion sur l'air de combustion théorique (combustion stoechiométrique) varie généralement dans l'intervalle de 1,05 à 1,1.The aeration rate of this main combustion zone i.e., the ratio of the actual combustion air volume to the theoretical combustion air (stoichiometric combustion) generally varies in the range of 1.05 at 1.1.

Les oxydes d'azote contenus dans les fumées issues de cette combustion primaire sont ensuite réduits dans la zone B de recombustion ou surcombustion réductrice. La réduction des oxydes d'azote est réalisée grâce à l'injection d'un combustible dit combustible secondaire par l'alimentation notée 2 en figure 1. De préférence, le combustible secondaire est injecté par l'entrée 2 en un volume représentant 10 à 20% du volume du combustible primaire, afin d'obtenir un taux d'aération voisin de 0,9 dans la zone B.The nitrogen oxides contained in the fumes from this primary combustion are then reduced in zone B of reductive combustion or overcombustion. The reduction of nitrogen oxides is achieved by injecting a fuel called secondary fuel by the feed marked 2 in FIG. 1. Preferably, the secondary fuel is injected through inlet 2 in a volume representing 10 to 20% of the volume of the primary fuel, in order to obtain a ventilation rate close to 0.9 in zone B.

De cette façon, l'atmosphère réductrice (en défaut d'oxygène) voulue est créée dans la zone de recombustion.In this way, the desired reducing atmosphere (lacking oxygen) is created in the recombination zone.

Le combustible secondaire utilisé pour la recombustion injecté dans la zone réductrice B, peut, comme le combustible primaire, être de toute nature : charbon, fioul, déchet, bois, gaz naturel, etc. Cependant, selon l'invention, le gaz naturel est de préférence utilisé.The secondary fuel used for the recombustion injected into the reducing zone B, can, like the primary fuel, be of any kind: coal, fuel oil, waste, wood, natural gas, etc. However, according to the invention, natural gas is preferably used.

L'étape d'oxydation des imbrûlés est dite étape de post-combustion, est ensuite effectuée.The oxidation stage of unburnt materials is called the post-combustion stage, and is then carried out.

L'étape de post-combustion est réalisée grâce à l'introduction, par l'entrée notée 1 en figure 1, d'air pour achever la combustion.The post-combustion stage is carried out thanks to the introduction, by the inlet marked 1 in FIG. 1, of air to complete the combustion.

Pour être efficace, l'injection du combustible secondaire, de préférence le gaz naturel, dans la zone de recombustion B doit se faire dans une plage de température comprise entre 1100 et 1500°C et elle doit être réalisée à un débit et une pression correspondant à un temps de séjour suffisant dans la zone de recombustion pour permettre une homogénéisation des mélanges combustible-fumées satisfaisante ainsi que pour permettre aux réactions de réduction de se produire. Le temps de séjour doit généralement être de l'ordre de 0,5 à 1 seconde selon les conditions opératoires.To be effective, the injection of the secondary fuel, preferably natural gas, into the recombustion zone B must be carried out in a temperature range between 1100 and 1500 ° C. and it must be carried out at a corresponding flow rate and pressure. sufficient residence time in the recombination zone to allow satisfactory homogenization of the fuel-smoke mixtures as well as to allow reduction reactions to take place. The residence time must generally be of the order of 0.5 to 1 second depending on the operating conditions.

La température de réduction utilisée pour l'étape de recombustion, dans la zone de recombustion B, peut être abaissée à environ 1000°C mais il faut alors augmenter le temps de séjour.The reduction temperature used for the recombustion step, in the recombustion zone B, can be lowered to approximately 1000 ° C. but it is then necessary to increase the residence time.

Si l'élévation de la température augmente l'efficacité de la destruction des précurseurs des oxydes d'azote dans la zone de recombustion, il y a cependant un risque dans ce cas de produire des oxydes d'azote au niveau de l'injection d'air dans la zone de post-combustion au-delà d'une certaine température.If the rise in temperature increases the efficiency of the destruction of the precursors of nitrogen oxides in the recombination zone, there is however a risk in this case of producing nitrogen oxides at the level of the injection d air in the post-combustion zone above a certain temperature.

Un équilibre doit donc être trouvé entre les paramètres temps de séjour-température, afin d'obtenir une homogénéisation satisfaisante entre le combustible secondaire utilisé dans la zone B de recombustion et les fumées issues de la zone A de combustion primaire ou principale contenant les oxydes d'azote à réduire.A balance must therefore be found between the residence time-temperature parameters, in order to obtain a satisfactory homogenization between the secondary fuel used in zone B of combustion and the fumes from zone A of primary or main combustion containing the oxides d nitrogen to reduce.

En fait le combustible secondaire se comporte comme un jet dans un flux transversal et l'homogénéisation d'un mélange d'un jet (combustible secondaire) dans un flux transversal (fumées issues de la combustion primaire) est soumise à des contraintes antagonistes, d'autant plus difficile que le débit volumique du jet sur la paroi du four est faible en comparaison au flux transversal principal.In fact the secondary fuel behaves like a jet in a transverse flow and the homogenization of a mixture of a jet (secondary fuel) in a transverse flow (fumes from primary combustion) is subject to antagonistic constraints, d 'all the more difficult as the volume flow rate of the jet on the wall of the furnace is low compared to the main transverse flow.

Ceci est le cas dans le procédé de recombustion où le volume de combustible, de préférence du gaz naturel, injecté représente 1% et parfois moins du débit des fumées.This is the case in the recombustion process where the volume of fuel, preferably natural gas, injected represents 1% and sometimes less than the flow rate of the fumes.

Afin d'améliorer l'homogénéisation, la présente invention consiste à injecter le combustible secondaire, de préférence du gaz naturel, par l'intermédiaire d'un système à plusieurs impulsions. Plus particulièrement, dans l'installation illustrée en figure 1, le combustible secondaire est injecté par un système à double impulsion dans la zone de recombustion.In order to improve homogenization, the present invention consists in injecting the secondary fuel, preferably natural gas, via a system with several pulses. More particularly, in the installation illustrated in FIG. 1, the secondary fuel is injected by a double pulse system into the recombustion zone.

L'injection à double impulsion selon l'invention possède deux circuits 2, 2' d'alimentation en gaz, un circuit d'alimentation à basse pression 2', réglé et contrôlé par tout moyen approprié noté 4 dans la figure 1, et un circuit d'alimentation en gaz haute pression 2 réglé et contrôlé par tout moyen approprié noté 5 sur la figure 1.The double pulse injection according to the invention has two gas supply circuits 2, 2 ′, a low pressure supply circuit 2 ′, adjusted and controlled by any suitable means noted 4 in FIG. 1, and a high pressure gas supply circuit 2 adjusted and controlled by any suitable means noted 5 in FIG. 1.

La double impulsion permet d'améliorer la pénétration du jet du combustible secondaire jusqu'au centre du four et également de répartir ce combustible dans l'ensemble de l'enceinte du four. Le jet central à haute pression entraîne également une partie du combustible injecté à plus basse pression, ce qui améliore également son mélange. Cette double impulsion de combustible gazeux peut être très facilement réglée, les variations de débit et des pressions du combustible gazeux sont très faciles à réaliser pour optimiser le mélange, c'est-à-dire de façon à s'adapter aux dimensions de la zone de recombustion, aux caractéristiques des fumées, et aux taux de réduction recherchés.The double pulse makes it possible to improve the penetration of the jet of secondary fuel up to the center of the oven and also to distribute this fuel throughout the oven enclosure. The central high pressure jet also entrains part of the fuel injected at lower pressure, which also improves its mixing. This double pulse of gaseous fuel can be very easily adjusted, the variations in flow rate and pressure of the gaseous fuel are very easy to achieve in order to optimize the mixture, that is to say in order to adapt to the dimensions of the combustion zone, to the characteristics of the smoke, and at the desired reduction rates.

Dans le mode de réalisation représenté en figure 1, les deux entrées 2, 2' du combustible secondaire sont coaxiales et l'entrée du combustible basse pression est extérieurement concentrique à l'entrée du combustible à haute pression.In the embodiment shown in FIG. 1, the two inlets 2, 2 ′ of the secondary fuel are coaxial and the inlet of the low pressure fuel is externally concentric with the inlet of the high pressure fuel.

L'utilisation d'un tel système d'injection à double impulsion permet d'obtenir une réduction des oxydes d'azote contenus dans les fumées issues de la combustion primaire de l'ordre de 70 à 80%, en moles, alors qu'avec le procédé et le dispositif de l'art antérieur ne comportant ni cette étape d'injection à double impulsion du combustible secondaire et ni le système d'injection du combustible secondaire à plusieurs impulsions, les taux de réduction des NOx sont de l'ordre de 50 à 60%, en moles.The use of such a double-pulse injection system makes it possible to obtain a reduction of the nitrogen oxides contained in the fumes from the primary combustion of the order of 70 to 80%, in moles, whereas with the method and the device of the prior art comprising neither this step of double pulse injection of the secondary fuel and nor the injection system of the secondary fuel with several pulses, the NOx reduction rates are of the order from 50 to 60%, in moles.

L'invention est donc particulièrement avantageuse dans les cas dans lesquels les dimensions du four ne permettent pas un bon mélange du combustible dans les fumées, en particulier.The invention is therefore particularly advantageous in cases in which the dimensions of the furnace do not allow good mixing of the fuel in the flue gases, in particular.

L'invention permet également, en améliorant le mélange, de réduire les quantités de combustible secondaire à injecter pour obtenir un taux donné de réduction des oxydes d'azote.The invention also makes it possible, by improving the mixture, to reduce the quantities of secondary fuel to be injected in order to obtain a given rate of reduction of nitrogen oxides.

Ceci est particulièrement avantageux, par exemple, dans le cas d'une chaudière où le combustible primaire est du charbon et le combustible secondaire ou de recombustion est du gaz naturel.This is particularly advantageous, for example, in the case of a boiler where the primary fuel is coal and the secondary or recombination fuel is natural gas.

Actuellement dans un procédé de recombustion les taux de réduction d'azote obtenus sont de l'ordre de 50 à 60% en moles, en substituant, au charbon, 20% en apport énergétique de gaz naturel.Currently in a recombination process, the nitrogen reduction rates obtained are of the order of 50 to 60% in moles, by substituting, for coal, 20% in energy supply of natural gas.

Avec l'utilisation du procédé et/ou de l'installation de l'invention, on peut obtenir ce même taux de réduction avec seulement 10 à 15% en valeur énergétique de gaz naturel injecté, ce qui représente un avantage économique.With the use of the process and / or the installation of the invention, this same reduction rate can be obtained with only 10 to 15% in energy value of natural gas injected, which represents an economic advantage.

Afin d'améliorer encore le mélange, en particulier dans les zones proches des parois du réacteur, et également entre les couches du jet haute pression et du jet basse pression du combustible secondaire gazeux, un générateur d'infrasons noté 6 dans la figure 1 annexée est monté sur une des parois du four de combustion au niveau de la zone B de recombustion.In order to further improve the mixing, in particular in the areas close to the walls of the reactor, and also between the layers of the high pressure jet and the low pressure jet of the gaseous secondary fuel, an infrasound generator denoted 6 in FIG. 1 appended is mounted on one of the walls of the combustion furnace at the level of the recombination zone B.

Avec l'ajout de ce générateur d'infrasons, le taux de réduction des oxydes d'azote contenus, dans les fumées issues de la combustion primaire, est généralement supérieur à 80%, plus précisément dans l'intervalle d'environ 80 à environ 90%, en moles.With the addition of this infrasound generator, the reduction rate of nitrogen oxides contained in the fumes from primary combustion is generally greater than 80%, more precisely in the range of about 80 to about 90%, in moles.

Le procédé de réduction des oxydes d'azote par recombustion des fumées issues d'une combustion primaire, selon l'invention, permet donc d'atteindre une efficacité de réduction des NOx de l'ordre de 70 à 80% en réalisant l'injection du combustible secondaire, de préférence du gaz naturel, dans la zone de recombustion, suivant au moins deux jets associés à pression relativement haute et relativement basse respectivement.The process for reducing nitrogen oxides by recombining the fumes from primary combustion, according to the invention, therefore makes it possible to achieve an NOx reduction efficiency of the order of 70 to 80% by performing the injection. secondary fuel, preferably natural gas, in the combustion zone, following at least two jets associated with relatively high and relatively low pressure respectively.

Dans ce procédé, le jet de combustible à basse pression est extérieurement concentrique au jet de combustible à pression plus élevée, ce qui permet d'améliorer la pénétration du combustible secondaire jusqu'au centre du four grâce au jet haute pression et également de répartir les gaz dans l'ensemble de l'enceinte. Le jet central à haute pression entraînant une partie du gaz injecté à plus basse pression, le mélange du combustible secondaire gazeux avec les fumées de la combustion primaire contenant l'oxyde d'azote à réduire est ainsi amélioré.In this process, the low pressure fuel jet is externally concentric with the higher pressure fuel jet, which improves the penetration of the secondary fuel to the center of the furnace thanks to the high pressure jet and also distributes the gas throughout the enclosure. The central high-pressure jet entraining part of the gas injected at a lower pressure, the mixture of the gaseous secondary fuel with the fumes of the primary combustion containing the nitrogen oxide to be reduced is thus improved.

En associant à cette injection du combustible secondaire, dans la zone de recombustion, suivant au moins deux jets associés, concentriques, à pression relativement haute et pression relativement basse respectivement, le jet étant extérieurement concentrique au jet combustible à pression plus élevée, une production d'ondes acoustiques dans la zone de recombustion, l'efficacité du procédé de l'invention atteint près de 80 à 90%.By associating with this injection of secondary fuel, in the recombustion zone, following at least two associated jets, concentric, at relatively high pressure and relatively low pressure respectively, the jet being externally concentric with the fuel jet at higher pressure, a production of acoustic waves in the recombustion zone, the efficiency of the process of the invention reaches nearly 80 to 90%.

De préférence, le combustible gazeux est injecté pour le jet à basse pression à une pression comprise entre quelques millibars et quelques centaines de millibars et pour le jet à haute pression, entre quelques centaines de millibars et quelques bars.Preferably, the gaseous fuel is injected for the low pressure jet at a pressure between a few millibars and a few hundred millibars and for the high pressure jet, between a few hundred millibars and a few bars.

Les ondes acoustiques utilisées ont une fréquence inférieure à environ 20 Hz.The acoustic waves used have a frequency of less than about 20 Hz.

Lorsque les contraintes réglementaires ne nécessitent pas d'atteindre une réduction aussi importante que celle citée précédemment, l'utilisation de l'injection à impulsion multiple et la production d'infrasons dans le procédé de recombustion des oxydes d'azote permet d'atteindre des taux d'efficacité de réduction des NOx de l'ordre de 50% mais en utilisant moins de combustible. Par exemple, la réduction de la quantité de combustible secondaire est de l'ordre de 50% en volume, ce qui permet de réduire le coût du procédé.When regulatory constraints do not require achieving a reduction as large as that mentioned above, the use of multiple pulse injection and the production of infrasound in the nitrogen oxides recombination process makes it possible to achieve NOx reduction efficiency rate of around 50% but using less fuel. For example, the reduction in the quantity of secondary fuel is of the order of 50% by volume, which makes it possible to reduce the cost of the process.

Bien entendu l'invention n'est nullement limitée aux modes de réalisation décrits et illustrés qui n'ont été donnés qu'à titre d'exemple.Of course, the invention is in no way limited to the embodiments described and illustrated which have been given only by way of example.

Ainsi bien que l'on ait décrit un procédé et un dispositif comportant une injection à double impulsion, des dispositifs et des procédés utilisant une injection à impulsion multiple du combustible secondaire dans la zone de recombustion pourront être utilisés. Ainsi une injection à triple impulsion du combustible secondaire peut être envisagée, dans laquelle le combustible gazeux sera injecté selon deux jets à haute pression concentriques l'un avec l'autre et un jet à basse pression concentriquement extérieur aux deux jets haute pression.Thus although a method and a device comprising a double-pulse injection have been described, devices and methods using a multiple-pulse injection of the secondary fuel in the recombination zone can be used. Thus, a triple pulse injection of the secondary fuel can be envisaged, in which the gaseous fuel will be injected according to two high pressure jets concentric with one another and a low pressure jet concentrically external to the two high pressure jets.

Par conséquent, l'invention comprend tous les équivalents techniques des moyens décrits ainsi que leurs combinaisons si celles-ci sont effectuées suivant son esprit.Consequently, the invention includes all the technical equivalents of the means described as well as their combinations if these are carried out according to the spirit.

Claims (10)

Procédé de réduction des oxydes d'azote contenus dans les fumées issues d'une combustion primaire, dans un four, par recombustion desdites fumées caractérisé par une injection d'un combustible secondaire dans la zone de recombustion dudit four suivant au moins deux jets associés à pression relativement haute et relativement basse respectivement.Process for the reduction of nitrogen oxides contained in the fumes from primary combustion, in an oven, by recombination of said fumes, characterized by an injection of a secondary fuel into the recombustion zone of said oven using at least two jets associated with relatively high and relatively low pressure respectively. Procédé selon la revendication 1, caractérisé en ce que le jet de combustible basse pression est extérieurement concentrique au jet de combustible à pression plus élevée.Method according to claim 1, characterized in that the low pressure fuel jet is externally concentric with the higher pressure fuel jet. Procédé selon la revendication 1 ou 2, caractérisé en ce que le combustible est un gaz à une pression comprise entre quelques millibars et quelques centaines de millibars pour le jet basse pression et entre quelques centaines de millibars et quelques bars pour le jet haute pression.A method according to claim 1 or 2, characterized in that the fuel is a gas at a pressure between a few millibars and a few hundred millibars for the low pressure jet and between a few hundred millibars and a few bars for the high pressure jet. Procédé selon l'une quelconque des revendications 1 à 3, caractérisé en ce que la pression et les débits du gaz des deux jets précités sont commandés de façon à s'adapter aux dimensions de la zone de recombustion et aux caractéristiques des fumées.Process according to any one of Claims 1 to 3, characterized in that the pressure and the gas flow rates of the two aforementioned jets are controlled so as to adapt to the dimensions of the recombustion zone and to the characteristics of the fumes. Procédé selon l'une quelconque des revendications 1 à 3, caractérisé en ce que la zone de recombustion du four est soumise à des ondes acoustiques.Method according to any one of Claims 1 to 3, characterized in that the recombination zone of the oven is subjected to acoustic waves. Procédé selon la revendication 5, caractérisé en ce que les ondes acoustiques précitées ont une fréquence inférieure à environ 20 Hz.Method according to claim 5, characterized in that the above-mentioned acoustic waves have a frequency of less than about 20 Hz. Installation pour la mise en oeuvre du procédé selon l'une quelconque des revendications 1 à 6, comprenant un four comprenant une zone de combustion primaire (A) alimentée par un combustible principal et suivie par une zone de recombustion (B) alimentée par un combustible secondaire, caractérisée en ce que ladite zone de recombustion est munie d'au moins deux entrées (2, 2') de combustible secondaire à des pressions différentes.Installation for implementing the method according to any one of Claims 1 to 6, comprising an oven comprising a primary combustion zone (A) supplied with a main fuel and followed by a recombustion zone (B) supplied with a fuel secondary, characterized in that said recombustion zone is provided with at least two inlets (2, 2 ') of secondary fuel at different pressures. Installation selon la revendication 7, caractérisée en ce que les deux entrées (2, 2') précitées sont coaxiales.Installation according to claim 7, characterized in that the two above-mentioned inputs (2, 2 ') are coaxial. Installation selon la revendication 7 ou la revendication 8, caractérisée en ce que les deux entrées précitées sont respectivement munies d'un appareil de commande du débit et de la pression (4, 5) du combustible secondaire formant les deux jets précités.Installation according to claim 7 or claim 8, characterized in that the two aforementioned inlets are respectively provided with an apparatus for controlling the flow and pressure (4, 5) of the secondary fuel forming the two aforementioned jets. Installation selon l'une quelconque des revendications 7 à 9, caractérisée en ce qu'un générateur d'ondes acoustiques (6) est monté sur la paroi du four de façon à pouvoir homogénéiser le mélange dans la zone de recombustion.Installation according to any one of claims 7 to 9, characterized in that an acoustic wave generator (6) is mounted on the wall of the furnace so as to be able to homogenize the mixture in the recombination zone.
EP97400984A 1996-05-21 1997-04-30 Process and installation for reducing by recombustion of nitric oxides in exhaust gases from a primary combustion in a furnace Expired - Lifetime EP0809067B1 (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999008045A1 (en) * 1997-08-08 1999-02-18 Gas Research Institute Nitrogen oxide reduction by gaseous fuel injection in low temperature, overall fuel-lean flue gas
FR2834774A1 (en) * 2002-01-16 2003-07-18 Saint Gobain Emballage Burner for reducing nitrogen oxide emissions in a glass melting furnace, incorporates an injector with at least three coaxial feed conduits for identical or different fuels
NL2001797C2 (en) * 2008-07-14 2010-01-18 Essent En Produktie B V Method for burning a second solid fuel in combination with a first solid fuel.

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS59173605A (en) * 1983-03-23 1984-10-01 Hitachi Zosen Corp Uniform feeding method of powder fuel in combustion furnace
EP0159492A2 (en) * 1984-03-24 1985-10-30 Steag Ag Process and firing equipment for reducing the generation of NOx in coal dust furnaces, particularly slag tap furnaces
EP0182063A2 (en) * 1984-11-15 1986-05-28 L. & C. Steinmüller GmbH Method for the reduction of the NOX content in combustion gases
US4779545A (en) * 1988-02-24 1988-10-25 Consolidated Natural Gas Service Company Apparatus and method of reducing nitrogen oxide emissions
EP0512156A1 (en) * 1991-05-07 1992-11-11 Ente Nazionale Per L'energia Elettrica - (Enel) A process for reducing nitric oxides in a flue gas
US5181475A (en) * 1992-02-03 1993-01-26 Consolidated Natural Gas Service Company, Inc. Apparatus and process for control of nitric oxide emissions from combustion devices using vortex rings and the like
JPH0727313A (en) * 1992-08-27 1995-01-27 Tokyo Gas Co Ltd High temperature furnace

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS59173605A (en) * 1983-03-23 1984-10-01 Hitachi Zosen Corp Uniform feeding method of powder fuel in combustion furnace
EP0159492A2 (en) * 1984-03-24 1985-10-30 Steag Ag Process and firing equipment for reducing the generation of NOx in coal dust furnaces, particularly slag tap furnaces
EP0182063A2 (en) * 1984-11-15 1986-05-28 L. & C. Steinmüller GmbH Method for the reduction of the NOX content in combustion gases
US4779545A (en) * 1988-02-24 1988-10-25 Consolidated Natural Gas Service Company Apparatus and method of reducing nitrogen oxide emissions
EP0512156A1 (en) * 1991-05-07 1992-11-11 Ente Nazionale Per L'energia Elettrica - (Enel) A process for reducing nitric oxides in a flue gas
US5181475A (en) * 1992-02-03 1993-01-26 Consolidated Natural Gas Service Company, Inc. Apparatus and process for control of nitric oxide emissions from combustion devices using vortex rings and the like
JPH0727313A (en) * 1992-08-27 1995-01-27 Tokyo Gas Co Ltd High temperature furnace

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 9, no. 29 (M - 356) 7 February 1985 (1985-02-07) *
PATENT ABSTRACTS OF JAPAN vol. 95, no. 001 *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999008045A1 (en) * 1997-08-08 1999-02-18 Gas Research Institute Nitrogen oxide reduction by gaseous fuel injection in low temperature, overall fuel-lean flue gas
FR2834774A1 (en) * 2002-01-16 2003-07-18 Saint Gobain Emballage Burner for reducing nitrogen oxide emissions in a glass melting furnace, incorporates an injector with at least three coaxial feed conduits for identical or different fuels
NL2001797C2 (en) * 2008-07-14 2010-01-18 Essent En Produktie B V Method for burning a second solid fuel in combination with a first solid fuel.
WO2010008280A1 (en) * 2008-07-14 2010-01-21 Essent Energie Productie B.V. Method for combusting a second solid fuel in combination with a first solid fuel

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ATE195999T1 (en) 2000-09-15
FR2749066B1 (en) 1998-08-21
HUP9700845A1 (en) 2000-05-28
DE69702950T2 (en) 2001-03-29
FR2749066A1 (en) 1997-11-28
EP0809067B1 (en) 2000-08-30
PL320054A1 (en) 1997-11-24
ES2152070T3 (en) 2001-01-16
CZ135297A3 (en) 1997-12-17
SK55397A3 (en) 1998-01-14
DE69702950D1 (en) 2000-10-05
HU9700845D0 (en) 1997-06-30
SI0809067T1 (en) 2001-04-30
PT809067E (en) 2001-02-28

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