EP1065461B1 - Combustion process, applicable in cement production - Google Patents

Combustion process, applicable in cement production Download PDF

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Publication number
EP1065461B1
EP1065461B1 EP00401748A EP00401748A EP1065461B1 EP 1065461 B1 EP1065461 B1 EP 1065461B1 EP 00401748 A EP00401748 A EP 00401748A EP 00401748 A EP00401748 A EP 00401748A EP 1065461 B1 EP1065461 B1 EP 1065461B1
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Prior art keywords
fuel
primary
process according
flame
oxidizer
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German (de)
French (fr)
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EP1065461A1 (en
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Jacques Dugue
Ovidiu Marin
Thierry Borissoff
Dora Sophia Alves
Michel Viardot
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LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
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Air Liquide SA
LAir Liquide SA a Directoire et Conseil de Surveillance pour lEtude et lExploitation des Procedes Georges Claude
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B7/00—Rotary-drum furnaces, i.e. horizontal or slightly inclined
    • F27B7/20—Details, accessories, or equipment peculiar to rotary-drum furnaces
    • F27B7/36—Arrangements of air or gas supply devices

Definitions

  • the present invention relates to a combustion method, applicable more particularly to the calcination of a material based on ore in particular the manufacture of cement in which a material is heated in contact with a source of heat essentially created by a flame generated by at least one fuel and at least one oxidizer. This calcination process is integrated into a cement preparation process.
  • the invention also relates to the use of the combustion process for heating a charge whether it is for melting a metal, maintain it in temperature, destruction of waste, etc ...
  • Clinker is a product that is obtained by baking a material based on ore and in particular clay and limestone.
  • the material in the form of powder can be supplied to a rotary kiln, either in dry form (dry process) or in the form of a water-based paste ("slurry") (wet process).
  • the composition of clinker is generally carefully controlled in order to obtain the proportions different mineral materials and especially calcium carbonate, silica, alumina, iron oxide and magnesium carbonate.
  • the precursor material for the manufacture of clinker first undergoes drying and heating.
  • this material undergoes a calcination in which the carbonates of the different minerals are converted into the oxide of these minerals by removal of carbon dioxide. With temperatures still high, minerals thus obtained chemically react with each other to produce mainly calcium silicates and calcium aluminates.
  • This last process is called “clinkerization” process and it is performed in the hot zone of a rotary oven. The resulting clinker is then cooled and sprayed then mixed with additional ingredients to form a cement such as Portland type cement.
  • Cement manufacturing processes involve many similarities and essential differences between these different processes reside essentially in the method used to dry, preheat or calcine the precursor of clinker.
  • the process of clinker manufacturing is almost always the same ie a process in which uses a rotary kiln in which the clinker precursors descend by gravity while hot gases are flowing against the current from of an area in which combustion has taken place.
  • Common fuels that burn easily in rotary clinker furnaces are coal, heavy fuel oil, and natural gas. These fuels have a lower calorific value (PCI) having a value between 30 and 45 x 10 6 joules / kg. Heavy fuels can be preheated and atomized into droplets of sizes less than 200 microns with a fraction of their mass transformed into droplets of diameter less than 50 microns. The smallest droplets evaporate quickly, allowing the flame to ignite near the end of the burner.
  • PCI calorific value
  • the carbon particles are pulverized with a size distribution between 10 and 200 microns.
  • the rapid and stable ignition of the combustion is improved by the control of the size but also by the combustible volatile matter released by the particles when they are heated.
  • cement manufacturers make continuous efforts to lower the cost of fuels used in the production of clinker and today try to burn in particular liquid or solid waste with low combustible qualities and often lower calorific value (PCI) at 15 x 10 6 joule / kg.
  • PCI calorific value
  • These bad fuels however, often have a water content greater than 20% by mass, or a large particle size (for example 75% of the mass consisting of particles or droplets larger than 200 microns).
  • the problem underlying the invention results from the observation by the inventors that the fuel injected into the furnace and in particular the fuels to low calorific value lower could only participate in combustion before to have traveled a fairly long distance inside the rotary kiln. If the distance the oven is too short, the combustion is of poor quality.
  • the flame comprises a primary combustion zone created by the combustion of a first fuel and of a first oxidizer, this primary zone being located near the injection points of the first oxidizer and of the first fuel, as well as a secondary combustion zone located downstream of the primary zone, for the combustion of a second fuel having a lower calorific value (PCI) less than or equal to 15 ⁇ 10 6 J / kg and a second oxidant, the second fuel being preheated by passage into or near the primary flame area.
  • PCI calorific value
  • the distance of passage of the second fuel in contact of the primary zone flame will be sufficient for at least part of the second fuel has been preheated to a temperature of at least about 400 ° C, preferably about 600 ° C and more preferably 800 ° C.
  • the secondary fuel will be a fuel whose lower calorific value (PCI) will be less than 15 x 10 6 joule / kg.
  • the secondary fuel may be a fuel whose mass content in water will be greater than or equal to approximately 20% and less than or equal to approximately 95%, preferably less than or equal to 70%.
  • the secondary fuel will contain ash in mass proportion greater than 20%.
  • the ignition distance defined as being the distance between the injection end of the oxidants and fuels and the start of the combustion zone will be less than 2 m, preferably less than about 1 m.
  • the primary flame area will be considered substantially ends when more than about 90% of the primary oxidant has reacted with the primary fuel.
  • the energy of the primary flame will be the lowest possible and will represent at most 30% and preferably at most 15% of the energy total brought by the flame.
  • the energy of the primary flame will represent approximately between 1% and 10% of the total energy provided by the flame, this primary flame preferably comprising a temperature zone also as high as possible, so as to raise the temperature as quickly as possible secondary fuel on contact.
  • the primary fuel will be a fuel preferably having a PCI greater than 30 x 10 6 joule / kg, that is to say a fuel which ignites easily.
  • this fuel having good qualities a fuel having a low lower calorific value or a fuel having poor ignition qualities as defined above in proportions such that a primary flame having the required temperature qualities and in particular having a temperature preferably greater than 800 ° C. and more preferably greater than 1000 ° C.
  • the primary oxidizer will be an oxidizer which will contain more than 21% of oxygen and preferably more than 35% of oxygen, more preferably more than 50% of oxygen and even more preferably will be industrially pure oxygen, that is to say of oxygen comprising more than about 88% by volume of oxygen such as the oxygen produced by oxygen production systems by adsorption such as VSA (Vaccum Swing Adsorption System) and may also consist of oxygen of cryogenic quality, that is to say having a purity often greater than 98%, possibly pure or mixed with air.
  • VSA Vacum Swing Adsorption System
  • the secondary fuel has already been described above, while the secondary oxidizer will preferably be air and in particular air which is usually used in the burner installed in cement kilns (still called primary air and / or secondary air).
  • the raw material from zone 1 is sent to the pre-calcination zone 3 (or according to some variant a Lepol type exchanger) in which the temperature of the raw material gradually heats up against current of hot gases flowing from left to right in the figure.
  • the pre-calcination zone 3 or according to some variant a Lepol type exchanger in which the temperature of the raw material gradually heats up against current of hot gases flowing from left to right in the figure.
  • FIG 2 is shown a detail view of the flame (12) shown in Figure 1.
  • the flame spreads over a large length of the rotary kiln (4) and the start of combustion actually begins a certain distance from the end of the burner (8), the visible non-combustion zone between the end of the burner and the start of the flame being represented by the area (13).
  • the primary air and main fuel are injected into the burner while secondary air is injected on the sides (according to the prior art).
  • Primary air is injected at a temperature of around 100 ° C, the secondary air has a temperature often between 500 and 900 ° C, while the flame temperature in its hottest part is around 1900 ° C at least.
  • the length of the flame in such a rotary kiln is typically 4 to 7 times the diameter of the rotary kiln (4).
  • FIGS. 3 A and 3 B the same figures show reference that in the previous figures the flames of the prior art, in the case where the ignition distance (D) represented by area (13) is correct for ensure good combustion, this distance (D) generally being less than 1 meter ( Figure 3a) while in Figure 3b is typically shown a flame degraded, that is to say that the zone (13) extends over a length D, which is unacceptable, which is in the range of 2 to 3 meters or more. Not only this ignition distance is too large but the ignition position, i.e. the tip of the non-inflamed area can fluctuate greatly and there are risk of flame release. Typically the injection of poor quality in an existing flame of the prior art as described above, leads to a degraded flame as shown in this figure 3b this which is unacceptable both from the point of view of combustion and from the point of view of installation security.
  • FIG. 4 shows a first solution according to the invention in which the hot oxy-fuel flame is located around the jet of poor quality secondary fuel, i.e. surrounds it.
  • the secondary fuel is injected in (24), while around it through the concentric orifice (23) is injected with the mixture of oxygen and first fuel so as to create a flame hot enough to preheat as it has
  • the fuel injected through the orifice (24) of poor quality has been described above.
  • the flame develops with in the center in the upstream flame area an area (25) in which the second fuel is preheated in contact with the generally oxy-combustible, hot flame, which develops in area (26) around poor quality fuel, while that a second downstream combustion zone develops substantially beyond the vertical line (40) shown in the figure, generally when about more than 90 % of the oxidizer, i.e. the oxygen used in the hot flame (26), has already reacted with the first fuel (usually of good quality) to create the hot flame which preheats the second fuel.
  • Downstream from line (40) we finds the second flame combustion zone resulting essentially from the combustion of the second fuel (of poor quality) with the surrounding air, i.e.
  • the entire flame (29) thus thus comprises a rear part upstream of the line (40), essentially formed by a short oxy-fuel flame which preheats the second fuel and a downstream part (27) in which produces the main combustion according to the invention, fuel from poor quality with air, combustion which can be carried out under conditions correct thanks to the preheating according to the invention of poor fuel quality in the upstream part of the flame.
  • FIG. 5 shows another variant of the invention, in which the flame which heats the poor quality fuel (25) is injected centrally in the injection system while the bad fuel quality to be heated surrounds this oxy-fuel flame injected through the orifice (23).
  • the other elements remain similar to those described in Figure 4, with the same operating principle, namely in the upstream zone preheating of the poor quality fuel which thus reaches the downstream part with a temperature generally preferably greater than or equal to 1000 ° C. which burns completely correctly with primary and / or secondary air from the annular cavities (22) and / or (21).
  • the second fuel of poor quality which should be preheated by the flame preferably oxygen and first fuel, will be injected into it or outside of it at a speed which will preferably not exceed 50 meters / s and more preferably which will not exceed 20 meters / s.
  • the speeds injection of this second fuel to be preheated of the order of 10 meters / s were suitable, particularly in the case of low PCI fuels or aqueous fuels such as sludge from sewage treatment plants, etc.
  • this solid waste such as carpet waste or plastic waste being generally made up of relatively coarse pieces and injected into speeds which are on the contrary high, for example of the order of 200 meters / s, of so as to be projected as far upstream as possible from the "clinkerization" zone of the clinker and can then be pyrolyzed and thus be associated with the formation of the clinker.
  • FIG. 6 represents an alternative embodiment of the invention corresponding to a modification of an existing burner on an oven (32).
  • All of the system (31) comprises in its lower part the existing burner (32) and in its upper part the whole added to implement the method according to the invention.
  • the fuel which possibly includes waste in particular solid waste is injected through the orifice (34), pneumatically using air primary while secondary air is injected into the annular duct (33) so as to produce the combustion system according to the prior art.
  • the second fuel to be preheated (35) is located in the center of an injected flame by the annular cover (36) preferably constituted as described above, of oxygen and a first fuel so as to preheat this second combustible.
  • This second fuel is preferably constituted as indicated above of a pulverulent or liquid fuel which needs to be preheated before to be able to react in the secondary combustion zone of the flame with air secondary especially not having reacted with the flame (33 - 34).
  • the elements of this flame (35 - 36) meets the elements of the aerocombustible flame by gravity.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Curing Cements, Concrete, And Artificial Stone (AREA)
  • Muffle Furnaces And Rotary Kilns (AREA)
  • Furnace Details (AREA)

Abstract

The flame comprises a primary combustion zone for e.g. fuel and oxidant, close to the fuel and oxidant injection points (23, 22). In addition the flame comprises a second combustion zone downstream, where a second fuel (24, 25) (low quality) and oxidant (21) burn. The second fuel is preheated by passage through the primary flame zone.

Description

La présente invention concerne un procédé de combustion, applicable plus particulièrement à la calcination d'un matériau à base de minerai notamment la fabrication de ciment dans lequel un matériau est chauffé au contact d'une source de chaleur essentiellement créée par une flamme engendrée par au moins un combustible et au moins un comburant. Ce procédé de calcination s'intègre dans un procédé de préparation de ciment. L'invention concerne également l'utilisation du procédé de combustion pour chauffer une charge que ce soit pour fondre un métal, le maintenir en température, la destruction des déchets, etc...The present invention relates to a combustion method, applicable more particularly to the calcination of a material based on ore in particular the manufacture of cement in which a material is heated in contact with a source of heat essentially created by a flame generated by at least one fuel and at least one oxidizer. This calcination process is integrated into a cement preparation process. The invention also relates to the use of the combustion process for heating a charge whether it is for melting a metal, maintain it in temperature, destruction of waste, etc ...

La fabrication de ciment passe par la fabrication d'un produit intermédiaire appelé « clinker ». Le clinker est un produit qui est obtenu par cuisson d'un matériau à base de minerai et notamment l'argile et le calcaire. Le matériau sous forme de poudre peut être fourni à un four rotatif, soit sous forme sèche (procédé sec) soit sous forme d'une pâte ("slurry") à base d'eau (procédé humide). La composition du clinker est en général soigneusement contrôlée afin d'obtenir les proportions désirées des différents matériaux minéraux et notamment le carbonate de calcium, la silice, l'alumine, l'oxyde de fer et le carbonate de magnésium. Après enfournement dans un four, le matériau précurseur pour la fabrication de clinker subit tout d'abord un séchage et un chauffage. Ensuite, ce matériau subit une calcination dans laquelle les carbonates des différents minéraux sont convertis en oxyde de ces minéraux par élimination de dioxyde de carbone. Les températures étant encore élevées, les minéraux ainsi obtenus réagissent chimiquement entre eux pour produire essentiellement des silicates de calcium et des aluminates de calcium. Ce dernier procédé est appelé procédé de « clinkerisation » (« clinkering » en anglais) et il est réalisé dans la zone chaude d'un four rotatif. Le clinker qui en résulte est alors refroidi et pulvérisé puis mélangé avec des ingrédients additionnels pour former un ciment tel que le ciment de type portland.The manufacture of cement involves the manufacture of an intermediate product called "clinker". Clinker is a product that is obtained by baking a material based on ore and in particular clay and limestone. The material in the form of powder can be supplied to a rotary kiln, either in dry form (dry process) or in the form of a water-based paste ("slurry") (wet process). The composition of clinker is generally carefully controlled in order to obtain the proportions different mineral materials and especially calcium carbonate, silica, alumina, iron oxide and magnesium carbonate. After charging in a furnace, the precursor material for the manufacture of clinker first undergoes drying and heating. Then, this material undergoes a calcination in which the carbonates of the different minerals are converted into the oxide of these minerals by removal of carbon dioxide. With temperatures still high, minerals thus obtained chemically react with each other to produce mainly calcium silicates and calcium aluminates. This last process is called "clinkerization" process and it is performed in the hot zone of a rotary oven. The resulting clinker is then cooled and sprayed then mixed with additional ingredients to form a cement such as Portland type cement.

Les procédés de fabrication de ciments comportent de nombreuses similitudes et les différences essentielles entre ces différents procédés résident essentiellement dans la méthode utilisée pour sécher, préchauffer ou calciner le précurseur du clinker. En règle générale dans tous ces systèmes le procédé de fabrication de clinker est sensiblement toujours le même c'est à dire un procédé dans lequel on utilise un four rotatif dans lequel les précurseurs de clinker descendent par gravité tandis que les gaz chauds sont circulés à contre courant en provenance d'une zone dans laquelle on a réalisé une combustion.Cement manufacturing processes involve many similarities and essential differences between these different processes reside essentially in the method used to dry, preheat or calcine the precursor of clinker. As a general rule in all these systems the process of clinker manufacturing is almost always the same ie a process in which uses a rotary kiln in which the clinker precursors descend by gravity while hot gases are flowing against the current from of an area in which combustion has taken place.

Il est connu, par exemple du brevet US 5,572,938, que l'utilisation d'oxygène dans les fours rotatifs de fabrication de clinker permet d'augmenter la production de clinker en améliorant essentiellement la combustion habituellement pratiquée à l'aide d'une combustion à l'air. Toutefois, jusqu'à ce jour, ces techniques ne sont pas très bien maítrisées et représentent souvent une augmentation sensible des coûts de production pour le fabricant.It is known, for example from US Patent 5,572,938, that the use oxygen in rotary clinker furnaces increases the clinker production by essentially improving combustion usually performed using air combustion. However, to date, these techniques are not very well controlled and often represent a significant increase production costs for the manufacturer.

Différentes techniques de fabrication de ciment sont décrites notamment dans les brevets US 3,302,938, US 3,404,199, US 3,925,091. D'autres procédés dans lesquels on utilise également de l'oxygène dans la fabrication de ciment sont décrits dans les brevets US 5,007,823 et 5.580.237.Different cement manufacturing techniques are described in particular in US patents 3,302,938, US 3,404,199, US 3,925,091. Other processes in which oxygen is also used in the manufacture of cement are described in US Patents 5,007,823 and 5,580,237.

D'une manière générale, les fabricants de clinker essaient d'incorporer comme combustibles dans leur four, afin de diminuer les coûts de production, des combustibles qui ont la propriété de brûler relativement mal, ainsi que des produits peu combustibles ayant un faible pouvoir calorifique inférieur (PCI). D'une manière générale ils cherchent à utiliser des déchets de toutes sortes relativement peu combustibles pour lesquels ils peuvent recevoir notamment des primes à la destruction desdits déchets. En effet, le procédé de fabrication de clinker consomme beaucoup d'énergie, en particulier parce que la réaction de décarbonation du carbonate de calcium dans l'opération de fabrication de clinker est une réaction très endothermique et donc grande consommatrice d'énergie.Generally speaking, clinker manufacturers are trying to incorporate as fuel in their furnace, in order to lower production costs, fuels that have the property of burning relatively poorly, as well as products low fuel with low lower calorific value (PCI). In a way generally they seek to use waste of all kinds relatively little fuels for which they can receive, in particular, destruction of said waste. Indeed, the clinker manufacturing process consumes a lot of energy, especially because the decarbonation reaction of the calcium carbonate in the clinker manufacturing operation is a very endothermic and therefore a large consumer of energy.

Les combustibles habituels qui brûlent facilement dans les fours rotatifs de fabrication de clinker sont le charbon, les fiouls lourds et le gaz naturel. Ces combustibles ont un pouvoir calorifique inférieur (PCI) ayant une valeur comprise entre 30 et 45 x 106 joules/kg. Les fuels lourds peuvent être préchauffés et atomisés en gouttelettes de tailles inférieures à 200 microns avec une fraction de leur masse transformée en gouttelettes de diamètre inférieure à 50 microns. Les gouttelettes les plus petites s'évaporent rapidement et permettent ainsi un allumage de la flamme près de l'extrémité du brûleur.Common fuels that burn easily in rotary clinker furnaces are coal, heavy fuel oil, and natural gas. These fuels have a lower calorific value (PCI) having a value between 30 and 45 x 10 6 joules / kg. Heavy fuels can be preheated and atomized into droplets of sizes less than 200 microns with a fraction of their mass transformed into droplets of diameter less than 50 microns. The smallest droplets evaporate quickly, allowing the flame to ignite near the end of the burner.

De la même manière, les particules de charbon sont pulvérisées avec une distribution de taille comprise entre 10 et 200 micron. L'allumage rapide et stable de la combustion est amélioré par le contrôle de la taille mais aussi par la matière volatile combustible dégagée par les particules lorsqu'elles sont chauffées. Cependant, les fabricants de ciment font des efforts continuels pour diminuer le coût des combustibles utilisés dans la production de clinker et essayent aujourd'hui de brûler notamment des déchets liquides ou solides ayant de faibles qualités combustibles et un pouvoir calorifique inférieur (PCI) souvent inférieur à 15 x 106 joule/kg. Ces mauvais combustibles ont cependant un contenu en eau souvent supérieur à 20 % en masse, ou une dimension de particules importante (par exemple 75 % de la masse consistant en des particules ou des gouttelettes de taille supérieure à 200 micron).Likewise, the carbon particles are pulverized with a size distribution between 10 and 200 microns. The rapid and stable ignition of the combustion is improved by the control of the size but also by the combustible volatile matter released by the particles when they are heated. However, cement manufacturers make continuous efforts to lower the cost of fuels used in the production of clinker and today try to burn in particular liquid or solid waste with low combustible qualities and often lower calorific value (PCI) at 15 x 10 6 joule / kg. These bad fuels, however, often have a water content greater than 20% by mass, or a large particle size (for example 75% of the mass consisting of particles or droplets larger than 200 microns).

L'utilisation de ces combustibles ayant des difficultés à brûler entraíne un certain nombre de problèmes dans la zone de combustion et en particulier dans la zone de calcination des fours rotatifs utilisés pour fabriquer le clinker et notamment un allumage de la flamme instable, des taux de combustion trop faibles, ce qui génère des concentrations en monoxyde de carbone qui sont incontrôlées, des émissions d'hydrocarbures dans les gaz issus de ces fours, des niveaux d'imbrûlés dans les cendres qui sont inacceptables en particulier les imbrûlés dans les gaz issus du four avec pour conséquence des diminutions de productivité, sauf à rajouter des quantités supplémentaires de combustibles afin de compenser les effets néfastes de ces mauvais combustibles.The use of these fuels having difficulty burning results in a number of problems in the combustion zone and in particular in the calcination zone of rotary ovens used to make clinker and in particular unstable flame ignition, too low burn rates, which generates uncontrolled carbon monoxide concentrations, hydrocarbon emissions in the gases from these ovens, unburnt levels in the ashes which are unacceptable especially the unburnt in the gases from the oven resulting in productivity reductions, unless added additional amounts of fuel to compensate for the effects harmful from these bad fuels.

Le problème à la base de l'invention résulte de la constatation par les inventeurs que le combustible injecté dans le four et notamment les combustibles à faible pouvoir calorifique inférieur ne pouvaient participer à la combustion avant d'avoir parcouru une assez longue distance à l'intérieur du four rotatif. Si la distance parcourue dans le four est trop courte, la combustion est de mauvaise qualité.The problem underlying the invention results from the observation by the inventors that the fuel injected into the furnace and in particular the fuels to low calorific value lower could only participate in combustion before to have traveled a fairly long distance inside the rotary kiln. If the distance the oven is too short, the combustion is of poor quality.

Dans le procédé de combustion selon l'invention la flamme comporte une zone primaire de combustion créée par la combustion d'un premier combustible et d'un premier comburant, cette zone primaire étant située à proximité des points d'injection du premier comburant et du premier combustible, ainsi qu'une zone secondaire de combustion située en aval de la zone primaire, pour la combustion d'un second combustible ayant un pouvoir calorifique inférieur (PCI) inférieur ou égal à 15·106 J/kg et d'un second comburant, le second combustible étant préchauffé par passage dans ou à proximité de la zone primaire de la flamme. In the combustion method according to the invention, the flame comprises a primary combustion zone created by the combustion of a first fuel and of a first oxidizer, this primary zone being located near the injection points of the first oxidizer and of the first fuel, as well as a secondary combustion zone located downstream of the primary zone, for the combustion of a second fuel having a lower calorific value (PCI) less than or equal to 15 · 10 6 J / kg and a second oxidant, the second fuel being preheated by passage into or near the primary flame area.

De préférence, la distance de passage du second combustible au contact de la flamme de la zone primaire sera suffisante pour qu'une partie au moins du second combustible ait été préchauffée à une température d'au moins environ 400°C, de préférence environ 600°C et plus préférentiellement 800°C.Preferably, the distance of passage of the second fuel in contact of the primary zone flame will be sufficient for at least part of the second fuel has been preheated to a temperature of at least about 400 ° C, preferably about 600 ° C and more preferably 800 ° C.

Selon un mode préférentiel de réalisation de l'invention, on a constaté que lorsque la distance de passage du second combustible au contact de la flamme s'effectuait dans des conditions telles que la température de ce second combustible était sensiblement de l'ordre de 1000°C au moins lorsque celui arrivait dans la seconde zone de combustion, la combustion du second combustible dans cette seconde zone s'effectuait dans de bonnes conditions, conduisant à une diminution du taux de NOx et de la quantité d'imbrûlés dans les fumées.According to a preferred embodiment of the invention, it has been found that when the passage distance of the second fuel in contact with the flame was carried out under conditions such as the temperature of this second fuel was about 1000 ° C at least when it reached the second combustion zone, the combustion of the second fuel in this second zone was performed in good conditions, leading to a decrease the NOx rate and the quantity of unburnt fumes.

Le combustible secondaire sera un combustible dont le pouvoir calorifique inférieur (PCI) sera inférieur à 15 x 106 joule/kg. Selon une variante de l'invention, le combustible secondaire pourra être un combustible dont la teneur massique en eau sera supérieure ou égale à environ 20 % et inférieure ou égale à environ 95 % de préférence inférieure ou égale à 70 %. Selon une autre variante de réalisation, le combustible secondaire contiendra des cendres en proportion massique supérieur à 20 %.The secondary fuel will be a fuel whose lower calorific value (PCI) will be less than 15 x 10 6 joule / kg. According to a variant of the invention, the secondary fuel may be a fuel whose mass content in water will be greater than or equal to approximately 20% and less than or equal to approximately 95%, preferably less than or equal to 70%. According to another alternative embodiment, the secondary fuel will contain ash in mass proportion greater than 20%.

Bien entendu, selon l'invention, on peut utiliser un combustible secondaire ou un mélange de combustibles secondaires (choisis notamment parmi ceux énumérés ci-dessus) ainsi qu'un mélange d'un ou plusieurs de ces combustibles secondaires avec un autre combustible tel que les combustibles primaires cités dans le cadre de la présente description et notamment ceux ayant un pouvoir calorifique inférieur (PCI) supérieur à 30 x 106 joule/kg. Selon un mode de réalisation de l'invention, la distance d'inflammation définie comme étant la distance entre l'extrémité d'injection des comburants et combustibles et le début de la zone de combustion sera inférieure à 2 m de préférence inférieure à environ 1 m.Of course, according to the invention, it is possible to use a secondary fuel or a mixture of secondary fuels (chosen in particular from those listed above) as well as a mixture of one or more of these secondary fuels with another fuel such as the primary fuels mentioned in the context of the present description and in particular those having a lower calorific value (PCI) greater than 30 x 10 6 joule / kg. According to one embodiment of the invention, the ignition distance defined as being the distance between the injection end of the oxidants and fuels and the start of the combustion zone will be less than 2 m, preferably less than about 1 m.

En règle générale, on considérera la zone de la flamme primaire se termine sensiblement lorsque plus de 90 % environ de l'oxydant primaire aura réagi avec le combustible primaire.As a general rule, the primary flame area will be considered substantially ends when more than about 90% of the primary oxidant has reacted with the primary fuel.

D'une manière générale, l'énergie de la flamme primaire sera la plus faible possible et représentera au plus 30 % et de préférence au plus 15 % de l'énergie totale apportée par la flamme. De façon préférentielle l'énergie de la flamme primaire représentera environ entre 1 % et 10 % de l'énergie totale apportée par la flamme, cette flamme primaire comportant de préférence une zone de température aussi élevée que possible, de manière à élever le plus rapidement possible la température du combustible secondaire à son contact.Generally, the energy of the primary flame will be the lowest possible and will represent at most 30% and preferably at most 15% of the energy total brought by the flame. Preferably the energy of the primary flame will represent approximately between 1% and 10% of the total energy provided by the flame, this primary flame preferably comprising a temperature zone also as high as possible, so as to raise the temperature as quickly as possible secondary fuel on contact.

Selon une autre variante de l'invention, le combustible primaire sera un combustible ayant de préférence avec un PCI supérieur à 30 x 106 joule/kg, c'est à dire un combustible qui s'enflamme facilement. Cependant, il sera possible de mélanger à ce combustible ayant de bonnes qualités, un combustible ayant un faible pouvoir calorifique inférieur ou un combustible ayant de mauvaises qualités d'allumage telles que définies ci-avant dans des proportions telles que l'on obtienne cependant une flamme primaire ayant les qualités de température requises et notamment ayant une température de préférence supérieure à 800°C et plus préférentiellement supérieure à 1000°C. Le comburant primaire sera un comburant qui comportera plus de 21 % en oxygène et de préférence plus de 35 % en oxygène, plus préférentiellement plus de 50 % en oxygène et encore plus préférentiellement sera de l'oxygène industriellement pur, c'est à dire de l'oxygène comportant plus d'environ 88 % en volume d'oxygène tel que l'oxygène produit par les systèmes de production d'oxygène par adsorption tels que les VSA (Vaccum Swing Adsorption System) et pourra être également constitué par de l'oxygène de qualité cryogénique c'est à dire ayant une pureté souvent supérieure à 98 %, éventuellement pur ou en mélange avec de l'air.According to another variant of the invention, the primary fuel will be a fuel preferably having a PCI greater than 30 x 10 6 joule / kg, that is to say a fuel which ignites easily. However, it will be possible to mix with this fuel having good qualities, a fuel having a low lower calorific value or a fuel having poor ignition qualities as defined above in proportions such that a primary flame having the required temperature qualities and in particular having a temperature preferably greater than 800 ° C. and more preferably greater than 1000 ° C. The primary oxidizer will be an oxidizer which will contain more than 21% of oxygen and preferably more than 35% of oxygen, more preferably more than 50% of oxygen and even more preferably will be industrially pure oxygen, that is to say of oxygen comprising more than about 88% by volume of oxygen such as the oxygen produced by oxygen production systems by adsorption such as VSA (Vaccum Swing Adsorption System) and may also consist of oxygen of cryogenic quality, that is to say having a purity often greater than 98%, possibly pure or mixed with air.

Le combustible secondaire a été déjà décrit ci avant, tandis que le comburant secondaire sera de préférence l'air et en particulier l'air qui est habituellement utilisé dans le brûleur installé dans les fours de cimenterie (encore appelé air primaire et/ou air secondaire).The secondary fuel has already been described above, while the secondary oxidizer will preferably be air and in particular air which is usually used in the burner installed in cement kilns (still called primary air and / or secondary air).

L'invention sera mieux comprise à l'aide des exemples de réalisation suivants donnés à titre non limitatif, conjointement avec les figures qui représentent :

  • la figure 1 représente une vue schématique en coupe latérale d'une installation de fabrication de clinker selon l'art antérieur ;
  • la figure 2 représente une vue de détails de la flamme utilisée dans le four rotatif pour la réalisation de clinker, selon l'art antérieur ;
  • la figure 3 représente schématiquement une flamme pour laquelle la distance d'inflammation est considérée comme correcte et une flamme dégradée c'est à dire non acceptable ;
  • la figure 4 représente une première variante de réalisation du procédé de combustion selon l'invention dans laquelle le second combustible est injecté à l'intérieur d'une flamme oxycombustible ;
  • la figure 5 représente une deuxième variante de la réalisation de l'invention dans laquelle la flamme primaire d'oxygène et de combustible est envoyée au centre du jet du second combustible ;
  • la figure 6 représente une troisième variante de la réalisation de l'invention dans laquelle la flamme primaire d'oxygène et de combustible entoure le second combustible afin de le préchauffer l'ensemble étant disposé au-dessus de la flamme air combustible existant sur le four.
The invention will be better understood with the aid of the following exemplary embodiments given without limitation, together with the figures which represent:
  • Figure 1 shows a schematic side sectional view of a clinker manufacturing installation according to the prior art;
  • 2 shows a detail view of the flame used in the rotary kiln for the production of clinker, according to the prior art;
  • FIG. 3 schematically represents a flame for which the ignition distance is considered to be correct and a degraded flame, that is to say not acceptable;
  • FIG. 4 represents a first alternative embodiment of the combustion method according to the invention in which the second fuel is injected inside an oxy-fuel flame;
  • FIG. 5 represents a second variant of the embodiment of the invention in which the primary flame of oxygen and fuel is sent to the center of the jet of the second fuel;
  • FIG. 6 represents a third variant of the embodiment of the invention in which the primary flame of oxygen and of fuel surrounds the second fuel in order to preheat it, the assembly being arranged above the flame of combustible air existing on the furnace .

Sur la figure 1, la matière crue issue de la zone 1 est envoyée dans la zone de pré-calcination 3 (ou selon certaine variante un échangeur de type Lepol) dans lequel la température de la matière crue s'échauffe progressivement à contre courant des gaz chauds circulant de la gauche vers la droite sur la figure.In Figure 1, the raw material from zone 1 is sent to the pre-calcination zone 3 (or according to some variant a Lepol type exchanger) in which the temperature of the raw material gradually heats up against current of hot gases flowing from left to right in the figure.

Sur la figure 2 est représentée une vue de détails de la flamme (12) représentée sur la figure 1. Sur cette figure, les mêmes éléments que ceux des autres figures portent les mêmes références. La flamme s'étend sur une grande longueur du four rotatif (4) et le début de la combustion commence effectivement à une certaine distance de l'extrémité du brûleur (8), la zone de non-combustion visible entre l'extrémité du brûleur et le début de la flamme étant représentée par la zone (13). Dans le brûleur est injecté l'air primaire et le combustible principal tandis que l'air secondaire est injecté sur les côtés (selon l'art antérieur). L'air primaire est injecté à une température d'environ 100°C, l'air secondaire a une température souvent comprise entre 500 et 900°C, tandis que la température de la flamme dans sa partie la plus chaude est de l'ordre de 1900°C au moins. La longueur de la flamme dans un tel four rotatif est typiquement de 4 à 7 fois le diamètre du four rotatif (4).In Figure 2 is shown a detail view of the flame (12) shown in Figure 1. In this figure, the same elements as those of other figures have the same references. The flame spreads over a large length of the rotary kiln (4) and the start of combustion actually begins a certain distance from the end of the burner (8), the visible non-combustion zone between the end of the burner and the start of the flame being represented by the area (13). The primary air and main fuel are injected into the burner while secondary air is injected on the sides (according to the prior art). Primary air is injected at a temperature of around 100 ° C, the secondary air has a temperature often between 500 and 900 ° C, while the flame temperature in its hottest part is around 1900 ° C at least. The length of the flame in such a rotary kiln is typically 4 to 7 times the diameter of the rotary kiln (4).

Sur les figures 3 A et 3 B on a représenté, avec les mêmes chiffres de référence que sur les figures précédentes les flammes de l'art antérieur, dans le cas où la distance d'inflammation (D) représentée par la zone (13) est correcte pour assurer une bonne combustion, cette distance (D) étant généralement inférieure à 1 mètre (figure 3a) tandis que sur la figure 3b est représentée typiquement une flamme dégradée c'est à dire que la zone (13) s'étend sur une longueur D, qui est inacceptable, qui est de l'ordre de 2 à 3 mètres ou plus. Non seulement cette distance d'inflammation est trop grande mais la position d'inflammation c'est à dire l'extrémité de la zone non-enflammée peut fluctuer grandement et il existe des risques de décrochement de flammes. Typiquement l'injection de combustibles de mauvaise qualité dans une flamme existante de l'art antérieur telle que décrite ci-avant, conduit à une flamme dégradée telle que représentée sur cette figure 3b ce qui est inacceptable tant du point de vue de la combustion que du point de vue de la sécurité de l'installation.In FIGS. 3 A and 3 B, the same figures show reference that in the previous figures the flames of the prior art, in the case where the ignition distance (D) represented by area (13) is correct for ensure good combustion, this distance (D) generally being less than 1 meter (Figure 3a) while in Figure 3b is typically shown a flame degraded, that is to say that the zone (13) extends over a length D, which is unacceptable, which is in the range of 2 to 3 meters or more. Not only this ignition distance is too large but the ignition position, i.e. the tip of the non-inflamed area can fluctuate greatly and there are risk of flame release. Typically the injection of poor quality in an existing flame of the prior art as described above, leads to a degraded flame as shown in this figure 3b this which is unacceptable both from the point of view of combustion and from the point of view of installation security.

Les figures suivantes (4, 5 et 6) représentent différentes variantes de réalisation de l'invention. Sur la figure 4 est représentée une première solution selon l'invention dans laquelle la flamme chaude oxy-combustible est situé autour du jet de combustible secondaire de mauvaise qualité, c'est à dire entoure celui-ci. Le combustible secondaire est injecté en (24), tandis qu'autour de celui-ci à travers l'orifice concentrique (23) est injecté le mélange d'oxygène et de premier combustible de manière à créer une flamme suffisamment chaude pour préchauffer comme il l'a été décrit ci-avant le combustible injecté à travers l'orifice (24) de mauvaise qualité. Ainsi que représentée sur la figure, la flamme se développe avec au centre dans la zone amont de la flamme une zone (25) dans laquelle le second combustible est préchauffé au contact de la flamme généralement oxy-combustible, chaude, qui se développe dans la zone (26) autour du combustible de mauvaise qualité, tandis qu'une deuxième zone de combustion aval se développe sensiblement au-delà de la ligne verticale (40) représentée sur la figure, généralement quand environ plus de 90 % du comburant, c'est à dire l'oxygène utilisé dans la flamme chaude (26), a déjà réagi avec le premier combustible (de bonne qualité généralement) pour créer la flamme chaude qui préchauffe le second combustible. En aval de la ligne (40) on retrouve la deuxième zone de combustion de la flamme résultant essentiellement de la combustion du second combustible (de mauvaise qualité) avec l'air environnant, c'est à dire l'air primaire injecté à travers la cavité annulaire (22) et/ou l'air dit secondaire injecté à travers la cavité annulaire (21), air qui comme dans le cadre de l'art antérieur a été généralement préchauffé à une température comprise entre 500 et 1000°C, ce préchauffage ayant lieu au contact du clinker formé dans le four rotatif de manière à refroidir celui-ci à partir d'air pompé de l'extérieur à température environnante. L'ensemble de la flamme (29) comporte donc ainsi une partie arrière en amont de la ligne (40), essentiellement formée par une flamme courte oxy-combustible qui préchauffe le second combustible et une partie avale (27) dans laquelle se produit la combustion principale selon l'invention, du combustible de mauvaise qualité avec l'air, combustion qui peut être réalisée dans des conditions correctes grâce au préchauffage selon l'invention du combustible de mauvaise qualité dans la partie amont de la flamme.The following figures (4, 5 and 6) show different variants of realization of the invention. FIG. 4 shows a first solution according to the invention in which the hot oxy-fuel flame is located around the jet of poor quality secondary fuel, i.e. surrounds it. The secondary fuel is injected in (24), while around it through the concentric orifice (23) is injected with the mixture of oxygen and first fuel so as to create a flame hot enough to preheat as it has The fuel injected through the orifice (24) of poor quality has been described above. As shown in the figure, the flame develops with in the center in the upstream flame area an area (25) in which the second fuel is preheated in contact with the generally oxy-combustible, hot flame, which develops in area (26) around poor quality fuel, while that a second downstream combustion zone develops substantially beyond the vertical line (40) shown in the figure, generally when about more than 90 % of the oxidizer, i.e. the oxygen used in the hot flame (26), has already reacted with the first fuel (usually of good quality) to create the hot flame which preheats the second fuel. Downstream from line (40) we finds the second flame combustion zone resulting essentially from the combustion of the second fuel (of poor quality) with the surrounding air, i.e. the primary air injected through the annular cavity (22) and / or the said air secondary injected through the annular cavity (21), air which as in the context of the prior art has generally been preheated to a temperature between 500 and 1000 ° C, this preheating taking place in contact with the clinker formed in the rotary kiln so as to cool it from air pumped from outside at temperature surrounding. The entire flame (29) thus thus comprises a rear part upstream of the line (40), essentially formed by a short oxy-fuel flame which preheats the second fuel and a downstream part (27) in which produces the main combustion according to the invention, fuel from poor quality with air, combustion which can be carried out under conditions correct thanks to the preheating according to the invention of poor fuel quality in the upstream part of the flame.

Sur la figure 5 est représentée une autre variante de l'invention, dans laquelle la flamme qui chauffe le combustible de mauvaise qualité (25) est injectée centralement dans le système d'injection tandis que le combustible de mauvaise qualité à chauffer entoure cette flamme oxy-combustible injectée à travers l'orifice (23). Les autres éléments restent similaires à ceux décrient sur la figure 4, avec le même principe de fonctionnement à savoir dans la zone amont un préchauffage du combustible de mauvaise qualité qui atteint ainsi la partie avale avec une température généralement de préférence supérieure ou égale à 1000°C ce qui permet de brûler de façon tout à fait correcte avec l'air primaire et/ou secondaire issue des cavités annulaires (22) et/ou (21).FIG. 5 shows another variant of the invention, in which the flame which heats the poor quality fuel (25) is injected centrally in the injection system while the bad fuel quality to be heated surrounds this oxy-fuel flame injected through the orifice (23). The other elements remain similar to those described in Figure 4, with the same operating principle, namely in the upstream zone preheating of the poor quality fuel which thus reaches the downstream part with a temperature generally preferably greater than or equal to 1000 ° C. which burns completely correctly with primary and / or secondary air from the annular cavities (22) and / or (21).

Selon une caractéristique de l'invention, le second combustible de mauvaise qualité, qui doit être préchauffé par la flamme de préférence oxygène et premier combustible, sera injecté dans celle-ci ou à l'extérieur de celle-ci à une vitesse qui n'excédera pas de préférence 50 mètres/s et plus préférentiellement qui n'excédera pas 20 mètres/s. D'une manière générale, on a constaté que les vitesses d'injection de ce second combustible à préchauffer, de l'ordre de 10 mètres/s étaient adaptées, particulièrement lorsqu'il s'agit de combustibles à faible PCI ou de combustibles aqueux tels que des boues de stations d'épuration, etc...According to a characteristic of the invention, the second fuel of poor quality, which should be preheated by the flame preferably oxygen and first fuel, will be injected into it or outside of it at a speed which will preferably not exceed 50 meters / s and more preferably which will not exceed 20 meters / s. In general, it has been found that the speeds injection of this second fuel to be preheated, of the order of 10 meters / s were suitable, particularly in the case of low PCI fuels or aqueous fuels such as sludge from sewage treatment plants, etc.

Dans le cadre de la présente invention, il n'est en effet pas exclu de pouvoir injecter également des déchets solides en addition du second combustible, ces déchets solides tels que des déchets de moquette ou des déchets de plastique étant généralement constitués de morceaux relativement grossiers et injectés à des vitesses qui sont au contraire élevées, par exemple de l'ordre de 200 mètres/s, de manière à être projetés le plus en amont possible de la zone de "clinkerisation" du clinker et à pouvoir ensuite être pyrolysés et ainsi s'associer à la formation du clinker.In the context of the present invention, it is in fact not excluded to be able to also inject solid waste in addition to the second fuel, this solid waste such as carpet waste or plastic waste being generally made up of relatively coarse pieces and injected into speeds which are on the contrary high, for example of the order of 200 meters / s, of so as to be projected as far upstream as possible from the "clinkerization" zone of the clinker and can then be pyrolyzed and thus be associated with the formation of the clinker.

La figure 6 représente une variante de réalisation de l'invention correspondant à une modification d'un brûleur existant sur un four (32). L'ensemble du système (31) comporte dans sa partie inférieure le brûleur existant (32) et dans sa partie supérieure l'ensemble rajouté pour mettre en ouvre le procédé selon l'invention. Dans sa partie inférieure, le combustible qui comporte éventuellement des déchets notamment des déchets solides est injecté à travers l'orifice (34), pneumatiquement à l'aide de l'air primaire tandis que de l'air secondaire est injecté dans la canalisation annulaire (33) de manière à réaliser le système de combustion selon l'art antérieur. Placé au-dessus de ce système de combustion et plus préférentiellement sur le même axe vertical, se trouve un système de combustion pour mettre en ouvre le procédé selon l'invention dans lequel le deuxième combustible à préchauffer (35) est situé au centre d'une flamme injectée par la couverture annulaire (36) constituée de préférence comme décrit ci-avant, d'oxygène et d'un premier combustible de manière à préchauffer ce deuxième combustible. Ce deuxième combustible est de préférence constitué comme indiqué ci-avant d'un combustible pulvérulent ou liquide qui nécessite d'être préchauffé avant de pouvoir réagir dans la zone de combustion secondaire de la flamme avec l'air secondaire notamment n'ayant pas réagi avec la flamme (33 - 34). Les éléments de cette flamme (35 - 36) rencontrent les éléments de la flamme aérocombustible par gravité. Bien entendu on peut là encore, selon une variante de l'invention, placer la flamme chaude (36) au centre et l'injection de seconds combustibles (35) autour cette flamme chaude (36).FIG. 6 represents an alternative embodiment of the invention corresponding to a modification of an existing burner on an oven (32). All of the system (31) comprises in its lower part the existing burner (32) and in its upper part the whole added to implement the method according to the invention. In its part lower, the fuel which possibly includes waste in particular solid waste is injected through the orifice (34), pneumatically using air primary while secondary air is injected into the annular duct (33) so as to produce the combustion system according to the prior art. Placed above of this combustion system and more preferably on the same axis vertical, there is a combustion system for implementing the method according to the invention in which the second fuel to be preheated (35) is located in the center of an injected flame by the annular cover (36) preferably constituted as described above, of oxygen and a first fuel so as to preheat this second combustible. This second fuel is preferably constituted as indicated above of a pulverulent or liquid fuel which needs to be preheated before to be able to react in the secondary combustion zone of the flame with air secondary especially not having reacted with the flame (33 - 34). The elements of this flame (35 - 36) meets the elements of the aerocombustible flame by gravity. Of course it is again possible, according to a variant of the invention, to place the hot flame (36) in the center and the injection of second fuels (35) around this hot flame (36).

Claims (20)

  1. Process for calcining an ore-based material, in which the said material is heated by contact with a heat source essentially created by a flame produced by at least one fuel and at least one oxidizer, the flame comprising a primary combustion zone created by the combustion of a first fuel called primary fuel and of a first oxidizer, this primary zone being located near the points of injection of the first oxidizer and of the primary fuel, as well as a secondary combustion zone located downstream of the primary zone, created by the combustion of a fuel called secondary fuel and of a secondary oxidizer, the secondary fuel being preheated by flowing through the primary zone of the flame, the said process being characterized in that the said secondary fuel has a net calorific value (NCV) which is less than or equal to 15 × 106 J/kg.
  2. Process according to Claim 1, characterized in that the distance that the secondary fuel flows in contact with the flame of the primary zone is sufficient for at least some of the secondary fuel to have been preheated to a temperature of at least 400°C.
  3. Process according to Claim 2, characterized in that the distance that the secondary fuel flows in contact with the flame of the primary zone is sufficient for at least some of the secondary fuel to have been preheated to a temperature of at least 600°C and preferably 800°C.
  4. Process according to Claim 2, characterized in that the distance that the secondary fuel flows in contact with the flame of the primary zone is sufficient for at least some of the secondary fuel to have been preheated to a temperature of at least 1000°C.
  5. Process according to one of Claims 1 to 4, characterized in that the secondary fuel is a fuel whose water content is greater than or equal to 20% by weight and less than or equal to 95% by weight, preferably 70% by weight.
  6. Process according to one of Claims 1 to 5, characterized in that the secondary fuel is a fuel containing ash in proportions greater than 20% by weight.
  7. Process according to one of Claims 1 to 6, characterized in that the ignition distance between the point of injection of the oxidizer or of the fuel and the beginning of the secondary flame is less than 2 metres, preferably less than 1 metre.
  8. Process according to one of Claims 1 to 7, characterized in that the secondary fuel comprises several secondary fuels and contains 0% to 50% by volume of fuel identical to the primary fuel.
  9. Process according to one of Claims 1 to 7, characterized in that the primary fuel comprises from 0% to 100% by volume of fuel used as secondary fuel.
  10. Process according to one of Claims 1 to 9, characterized in that the secondary combustion zone starts at a distance from the points of injection of the oxidizers and fuels such that 90% by volume of the primary oxidizer has reacted with the primary fuel.
  11. Process according to one of Claims 1 to 10, characterized in that the energy of the primary flame represents more than 30%, preferably more than 15%, of the total energy provided by the flame.
  12. Process according to one of Claims 1 to 11, characterized in that the energy of the primary flame represents between 1 and 10% of the total energy provided by the flame.
  13. Process according to one of Claims 1 to 12, characterized in that the primary fuel is chosen from natural gas and/or propane.
  14. Process according to one of Claims 1 to 13, characterized in that the primary oxidizer consists of oxygen-enriched air, comprising more that 21% oxygen by volume.
  15. Process according to Claim 14, characterized in that the primary oxidizer comprises more than 50% oxygen by volume, preferably more than 88% oxygen by volume.
  16. Process according to Claim 15, characterized in that the primary oxidizer comprises more than 98% oxygen by volume.
  17. Process according to one of Claims 1 to 16, characterized in that the secondary oxidizer essentially consists of air.
  18. Process according to one of Claims 1 to 17, characterized in that the primary oxidizer has an oxygen concentration greater than the oxygen concentration of the secondary oxidizer.
  19. Process according to one of the preceding claims, characterized in that the secondary fuel is injected at a velocity which does not exceed 50 metres/s, preferably which does not exceed a velocity of 20 metres/s.
  20. Process according to Claim 19, characterized in that the secondary fuel is injected at a velocity of about 10 metres/s.
EP00401748A 1999-07-02 2000-06-20 Combustion process, applicable in cement production Expired - Lifetime EP1065461B1 (en)

Applications Claiming Priority (2)

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FR9908562 1999-07-02
FR9908562A FR2795808B1 (en) 1999-07-02 1999-07-02 COMBUSTION PROCESS APPLICABLE TO THE MANUFACTURE OF CEMENT

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EP1065461B1 true EP1065461B1 (en) 2004-03-17

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EP (1) EP1065461B1 (en)
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CN (1) CN1208575C (en)
AT (1) ATE262150T1 (en)
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DE (1) DE60008970T2 (en)
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Cited By (3)

* Cited by examiner, † Cited by third party
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DE102011015317A1 (en) 2011-03-28 2012-10-04 Air Liquide Deutschland Gmbh Method and apparatus for operating a furnace
EP2717007A1 (en) 2012-10-08 2014-04-09 Air Liquide Deutschland GmbH Method and apparatus for improving the combustion of secondary fuel in a rotary kiln
WO2014056804A1 (en) 2012-10-08 2014-04-17 L'air Liquide,Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Process and apparatus for improving the combustion of secondary fuel in a rotary kiln and process for retrofitting a rotary kiln with a burner assembly

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WO2012130858A1 (en) 2011-03-28 2012-10-04 L'air Liquide Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Method and apparatus for operating a furnace
EP2717007A1 (en) 2012-10-08 2014-04-09 Air Liquide Deutschland GmbH Method and apparatus for improving the combustion of secondary fuel in a rotary kiln
WO2014056804A1 (en) 2012-10-08 2014-04-17 L'air Liquide,Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Process and apparatus for improving the combustion of secondary fuel in a rotary kiln and process for retrofitting a rotary kiln with a burner assembly

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ATE262150T1 (en) 2004-04-15
CA2312576A1 (en) 2001-01-02
FR2795808B1 (en) 2001-09-14
DE60008970D1 (en) 2004-04-22
ES2216834T3 (en) 2004-11-01
CN1290668A (en) 2001-04-11
JP2001064049A (en) 2001-03-13
CN1208575C (en) 2005-06-29
CA2312576C (en) 2009-08-18
EP1065461A1 (en) 2001-01-03
US6375456B1 (en) 2002-04-23
JP4642972B2 (en) 2011-03-02
FR2795808A1 (en) 2001-01-05

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