EP3114243B1 - Industrial furnace for heating products such as steel products - Google Patents

Industrial furnace for heating products such as steel products Download PDF

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Publication number
EP3114243B1
EP3114243B1 EP15705323.2A EP15705323A EP3114243B1 EP 3114243 B1 EP3114243 B1 EP 3114243B1 EP 15705323 A EP15705323 A EP 15705323A EP 3114243 B1 EP3114243 B1 EP 3114243B1
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EP
European Patent Office
Prior art keywords
combustion
duct
flow rate
predetermined flow
fumes
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Not-in-force
Application number
EP15705323.2A
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German (de)
French (fr)
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EP3114243A1 (en
Inventor
Ludovic Ferrand
Patrick Dubois
Eduardo PINTO DE SOUSA
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Cockerill Maintenance and Ingenierie SA
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Cockerill Maintenance and Ingenierie SA
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Publication of EP3114243A1 publication Critical patent/EP3114243A1/en
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Classifications

    • 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
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/30—Details, accessories, or equipment peculiar to furnaces of these types
    • F27B9/3044—Furnace regenerators
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
    • C21D9/54—Furnaces for treating strips or wire
    • C21D9/56—Continuous furnaces for strip or wire
    • C21D9/561—Continuous furnaces for strip or wire with a controlled atmosphere or vacuum
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
    • C21D9/54—Furnaces for treating strips or wire
    • C21D9/56—Continuous furnaces for strip or wire
    • C21D9/562—Details
    • 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
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/14—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment
    • F27B9/20—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment the charge moving in a substantially straight path tunnel furnace
    • 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
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/28—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity for treating continuous lengths of work
    • 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
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/30—Details, accessories, or equipment peculiar to furnaces of these types
    • F27B9/36—Arrangements of heating devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D17/00—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases
    • F27D17/004—Systems for reclaiming waste heat
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D17/00—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases
    • F27D17/008—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases cleaning gases
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D17/00—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases
    • F27D17/004—Systems for reclaiming waste heat
    • F27D2017/007—Systems for reclaiming waste heat including regenerators

Definitions

  • the invention relates to an industrial furnace for heating products such as steel products.
  • furnaces for heating steel products such as preheating furnaces for processing steel coils, comprise a thermally insulated enclosure and a plurality of burners arranged in the enclosure to heat the steel products circulating in the furnace. pregnant.
  • the burners are supplied with combustion air and with a natural gas type fuel, produce, by a first combustion, flames that heat the iron and steel products, and generate fumes circulating counter-cyclically. current of said steel products.
  • These fumes are usually themselves treated by a second combustion called "post-combustion", whose role is to ensure complete combustion to remove fumes at least a portion of polluting gases such as carbon monoxide. The resulting smoke and less polluting are then removed from the oven and released into the atmosphere by a chimney.
  • the energy consumption of preheating furnaces for processing steel coils is particularly high, of the order of 220 kWh of natural gas per tonne of heated steel. It is therefore particularly important, both from an environmental and an economic point of view, to try to improve the energy efficiency of these ovens.
  • a first method usually used is to equip the furnaces with means of recovery of energy to recover heat lost in the fumes, as disclosed in DE202013102653U1 .
  • These recovery means are typically constituted by a tubular bundle heat exchanger comprising metal tubes in which circulates the combustion air used by the burners.
  • the fumes circulating around the tubes, preheat the combustion air, which improves the efficiency of the first combustion mentioned earlier.
  • This heat recovery is, however, limited by the maximum permissible temperature that can withstand the tubes, which makes it necessary to dilute the fumes with cold air.
  • a second method, which has now largely supplanted the first method, is to use regenerative burners.
  • This solution has a number of disadvantages.
  • the regenerative burners are not suitable for sucking fumes that are unburned in the burner, because it then becomes impossible to carry out an afterburner.
  • This solution is moreover difficult to apply to compact furnaces because of the one hand, of the space of regenerative tanks which are equipped with the burners and, on the other hand, the need to install the double of regenerative burners compared to to the number of burners of a standard solution.
  • Regenerative burners operate in pairs, according to a cyclic operation: the burners are half of the time in one mode of combustion and the other half of the time in a mode of accumulation of heat.
  • the invention aims to improve the energy efficiency of an industrial furnace while having an acceptable size.
  • a industrial furnace for heating products such as steel products, the furnace comprising a thermally insulated enclosure and a plurality of burners arranged in the enclosure for heating the products flowing from one end to the other of the enclosure, the burners being distributed in a plurality of temperature controlled heating zones.
  • the oven further comprises recovery means for recovering thermal energy recovery fumes from a first combustion performed by the burners so as to improve energy efficiency of the furnace.
  • the recovery means comprise a rotating regenerator associated with each heating zone, each of the rotating regenerators being adapted to receive a predetermined flow rate of the recovery fumes via a first pipe, to receive a predetermined flow rate of an air of supply via a second pipe, to preheat this supply air to provide the burners of the associated heating zone a predetermined flow of preheated combustion air via a third pipe, and to exhaust exhaust gases via a fourth pipe the predetermined flow rate of the recovery fumes received by each rotating regenerator being regulated by first regulating means comprising a first valve mounted on the fourth line of said rotating regenerator.
  • the energy efficiency of the furnace is improved through a recovery of thermal energy achieved by means of rotating regenerators which have congestion acceptable for most industrial furnaces.
  • the invention relates to an industrial furnace for heating products such as steel products, and is here implemented in a non-oxidizing preheating furnace of steel strips for continuous lines for processing steel coils.
  • the furnace of the invention 1 comprises a thermally insulated enclosure 2, a plurality of burners 3 arranged in the enclosure 2 to achieve a first combustion and heat a steel strip 4 flowing from one end to the other of the enclosure 2, so-called "post-combustion" means 5 adapted to achieve a second combustion, and recovery means 6.
  • the plurality of burners 3 is constituted by ten burners 3 distributed according to a plurality of temperature-controlled heating zones, in this case according to three heating zones Z1, Z2, Z3.
  • This distribution makes it possible to regulate the temperature of the furnace 1 by virtue of only three thermocouples 7 positioned in the heating zones Z1, Z2, Z3, so as to conform the temperature of the furnace to predetermined heating curves which depend in particular on a heating temperature.
  • the heating zones Z1, Z2, Z3 are thus regulated according to temperature setpoints typically between 1200 and 1350 degrees Celsius for a desired band temperature at the level of the desired band at a strip output S1 of the furnace 1.
  • S1 band output of oven 1 between 550 and 750 degrees Celsius.
  • the first combustion performed by the burners 3 requires a fuel, here natural gas, and an oxidant, here combustion air Ac.
  • the burners 3 operate here in so-called "sub-stoichiometric" mode, also called combustion in air defect or combustion in rich gas.
  • a combustion air flow is always less than an air flow necessary to completely burn a flow of natural gas Gn introduced into the same burner.
  • Fumes of first combustion F1 are then generated by the burners 3, said fumes of first combustion F1 having a so-called "incomplete" combustion, an oxygen content of which is practically zero, the oxygen of the combustion air having combined entirely or almost with natural gas.
  • the sub-stoichiometric regime is particularly advantageous since it makes it possible to give the fumes of first combustion F1 a reducing power on the steel strip 4, which makes it possible to avoid the formation of oxides on the steel strip, type of iron oxide for example, and even to reduce some oxides possibly present on the steel strip before this first combustion. This improves the quality of the steel strip preheated by the furnace of the invention.
  • the fumes of first combustion F1 are loaded with intermediate compounds after the first incomplete combustion, for example dihydrogen or carbon monoxide. Carbon monoxide can not be released into the atmosphere because it is a pollutant whose emissions are regulated.
  • the post-combustion means 5 are thus used to carry out the second combustion, which consists in injecting air called "post-combustion air" Apc, whose role is to complete the first combustion, carried out by the burners 3, in order to suppress the first combustion fumes F1 the intermediate compounds. Since the fumes of first combustion F1 circulate generally against the current of the steel strip 4, the post-combustion means 5 are located in the furnace 1 upstream of the burners 3, that is to say they are located between an inlet E of the furnace and the burners 3. The post-combustion air Apc is injected by the post-combustion means 5 according to a post-combustion air flow Apc dosed to ensure complete combustion without adding unnecessary air.
  • post-combustion air Apc
  • the post-combustion air Apc is injected into an area of the enclosure in which the steel strip has a temperature that is too low to undergo the effects of oxidation caused by oxygen in the air. post-combustion Apc in excess.
  • the post-combustion air Apc can be injected from flue gas flues.
  • Recovery fumes F2 at least partially depolluted, are generated by the second combustion.
  • the recovery means 6 are intended to recover thermal energy from these recovery fumes F2, which are therefore derived from the first combustion and the second combustion. This improves the energy efficiency of the furnace 1.
  • the recovery means 6 comprise a rotating regenerator 7 associated with each heating zone Z1, Z2, Z3, and thus here three rotating regenerators 7.
  • the role of these rotating regenerators 7 is to heat a predetermined flow of supply air 8 so as to provide a predetermined flow rate of preheated combustion air 9.
  • the fact of using a preheated combustion air Ac makes it possible to significantly increase the efficiency of the first combustion by decreasing the amount of natural gas Gn required for that and, therefore, to increase the energy efficiency of the furnace of the invention 1.
  • Each rotary regenerator 7 is adapted to receive a predetermined flow of recovery fumes 10 via a first pipe 11, to receive the predetermined flow of supply air 8 via a second pipe 12, to preheat this supply air Aa for supplying to the burners 3 of the heating zone associated with the rotating regenerator 7 the predetermined flow rate of preheated combustion air 9 via a third pipe 14, and discharging exhaust fumes F3 via a fourth pipe 15.
  • Each rotating regenerator 7 is fed continuously by the predetermined flow of feed air 8 and by the predetermined flow rate of recovery fumes 10.
  • Each rotating regenerator 7 comprises, in a manner known per se, rotating compartments which are placed in communication a first half of the time with the first pipe 11, which allows a warming of the interior of the regenerator 7, then a second half of the time with the second pipe 12, which allows to supply air supply Aa the rotating regenerator 7.
  • the supply air Aa which is never in contact with the recovery fumes, is thus preheated, which allows to provide the associated burner 7 the predetermined flow of preheated combustion air 9 .
  • the recovery fumes F2 are distributed in each rotating regenerator 7 so as to always maintain a certain distribution ratio between the predetermined flow rate of supply air 8 and the predetermined flow rate of recovery fumes 10.
  • a distribution ratio is set between the predetermined flow rate of supply air 8 and the predetermined flow rate of recovery fumes 10 of between approximately 1 and 1.2, such a distribution ratio making it possible to optimize the energy efficiency of the furnace of the invention.
  • the predetermined flow rate of recovery fumes received by each rotating regenerator 7 is first regulated by first regulating means comprising a first valve 17 mounted on the fourth line 15 of said rotating regenerator 7.
  • first regulating means comprising a first valve 17 mounted on the fourth line 15 of said rotating regenerator 7.
  • the predetermined flow rate of recovery fumes 10 is regulated indirectly, through a regulation of the flow of exhaust fumes F3.
  • This regulation is effected by means in particular of the first valve 17 which is mounted downstream of said rotary regenerator 7, that is to say which is located between the rotating regenerator 7 and a furnace exhaust outlet S2 which is here implemented. communication with a chimney 25 through which the exhaust fumes are removed from the furnace 1.
  • the predetermined flow rate of supply air 8 received by each rotating regenerator 7 is further regulated by second regulating means comprising a second valve 20 mounted on the second pipe 12 of the said rotary regenerator 7.
  • second regulating means comprising a second valve 20 mounted on the second pipe 12 of the said rotary regenerator 7.
  • a flowmeter 21 is mounted on the third conduit 14 each rotating regenerator 7, each flowmeter 21 being adapted to measure the combustion air flow rate 9 supplied to the burners 3 of the heating zone Z1, Z2, Z3 associated with said rotating regenerator 7.
  • a flow measurement generating little loss of pressure in the pipe, which helps maintain combustion air at a relatively low pressure.
  • a flowmeter 21 of the Venturi tube or Pitot tube or Vortex effect type will be chosen.
  • the preheated combustion air is brought to temperatures typically between 800 degrees Celsius and 1000 degrees Celsius, while the exhaust fumes are brought to temperatures typically between 150 degrees Celsius and 250 degrees Celsius.
  • first and second regulating means comprising respectively the first 17 and second valves 20, are situated on the fourth and second conduits 8, which have relatively low temperatures relative to the first 11 and third lines 14. Control means are therefore a less expensive and more reliable solution than a similar solution located on the hotter pipes.
  • the third pipe 14 of each regenerator rotating two shutoff valves 22 is mounted on the third pipe 14, and inert gas injection means 23 is mounted on the third pipe 14. nitrogen, to fill a gas gap between the two valves of 23. This maintains a positive pressure between the two shutoff valves 23, so that in case of leakage at one of the shutoff valves, only an inert gas leakage flow can enter the enclosure 2.
  • the post-combustion air (Apc) comes in part from the preheated combustion air generated by at least one rotating regenerator, possibly oversized for this purpose. This allows to further improve the energy efficiency of the oven of the invention.

Description

L'invention concerne un four industriel pour chauffer des produits tels des produits sidérurgiques.The invention relates to an industrial furnace for heating products such as steel products.

ARRIERE PLAN DE L'INVENTIONBACKGROUND OF THE INVENTION

De nombreux fours industriels destinés à chauffer des produits sidérurgiques, comme par exemple les fours de préchauffe pour traitement de bobines d'acier, comportent une enceinte isolée thermiquement et une pluralité de brûleurs agencés dans l'enceinte pour chauffer les produits sidérurgiques circulant dans l'enceinte.Many industrial furnaces for heating steel products, such as preheating furnaces for processing steel coils, comprise a thermally insulated enclosure and a plurality of burners arranged in the enclosure to heat the steel products circulating in the furnace. pregnant.

Les brûleurs, classiquement répartis selon plusieurs zones de chauffage régulées en température, sont alimentés par un air de combustion et par un combustible de type gaz naturel, produisent par une première combustion des flammes chauffant les produits sidérurgiques, et génèrent des fumées circulant à contre-courant desdits produits sidérurgiques. Ces fumées sont généralement elles-mêmes traitées par une seconde combustion dite « post-combustion », dont le rôle est d'assurer une combustion complète permettant de supprimer des fumées au moins une partie de gaz polluants tels que du monoxyde de carbone. Les fumées résultantes et moins polluantes sont alors évacuées du four et rejetées dans l'atmosphère par une cheminée.The burners, conventionally distributed according to several temperature-controlled heating zones, are supplied with combustion air and with a natural gas type fuel, produce, by a first combustion, flames that heat the iron and steel products, and generate fumes circulating counter-cyclically. current of said steel products. These fumes are usually themselves treated by a second combustion called "post-combustion", whose role is to ensure complete combustion to remove fumes at least a portion of polluting gases such as carbon monoxide. The resulting smoke and less polluting are then removed from the oven and released into the atmosphere by a chimney.

La consommation énergétique des fours de préchauffe pour traitement de bobines d'acier est particulièrement élevée, de l'ordre de 220 kWh de gaz naturel par tonne d'acier réchauffé. Il est donc particulièrement important, aussi bien d'un point de vue environnemental que d'un point de vue économique, de tenter d'améliorer le rendement énergétique de ces fours.The energy consumption of preheating furnaces for processing steel coils is particularly high, of the order of 220 kWh of natural gas per tonne of heated steel. It is therefore particularly important, both from an environmental and an economic point of view, to try to improve the energy efficiency of these ovens.

Pour cela, une première méthode utilisée habituellement consiste à équiper les fours de moyens de récupération d'énergie pour récupérer la chaleur perdue dans les fumées, comme divulgué dans DE202013102653U1 .For this, a first method usually used is to equip the furnaces with means of recovery of energy to recover heat lost in the fumes, as disclosed in DE202013102653U1 .

Ces moyens de récupération sont typiquement constitués par un échangeur de chaleur à faisceaux tubulaires comportant des tubes métalliques dans lesquels circule l'air de combustion utilisé par les brûleurs. Les fumées, en circulant autour des tubes, préchauffent l'air de combustion, ce qui améliore le rendement de la première combustion évoquée plus tôt. Cette récupération de chaleur est cependant limitée par la température maximale admissible que peuvent supporter les tubes, qui rend nécessaire de diluer les fumées par de l'air froid.These recovery means are typically constituted by a tubular bundle heat exchanger comprising metal tubes in which circulates the combustion air used by the burners. The fumes, circulating around the tubes, preheat the combustion air, which improves the efficiency of the first combustion mentioned earlier. This heat recovery is, however, limited by the maximum permissible temperature that can withstand the tubes, which makes it necessary to dilute the fumes with cold air.

Une seconde méthode, qui a aujourd'hui nettement supplanté la première méthode, consiste à utiliser des brûleurs régénératifs. Cette solution présente cependant un certain nombre d'inconvénients. Tout d'abord, les brûleurs régénératifs ne sont pas adaptés à aspirer des fumées chargées en imbrûlés dans le brûleur, car il devient alors impossible d'effectuer une post-combustion. Cette solution est de plus difficilement applicable à des fours compacts du fait d'une part, de l'encombrement de bacs régénératifs dont sont équipés les brûleurs et, d'autre part, de la nécessité d'installer le double de brûleurs régénératifs par rapport au nombre de brûleurs d'une solution standard. Les brûleurs régénératifs fonctionnent en effet par paire, selon un fonctionnement cyclique : les brûleurs sont la moitié du temps dans un mode de combustion et l'autre moitié du temps dans un mode d'accumulation de chaleur.A second method, which has now largely supplanted the first method, is to use regenerative burners. This solution, however, has a number of disadvantages. First of all, the regenerative burners are not suitable for sucking fumes that are unburned in the burner, because it then becomes impossible to carry out an afterburner. This solution is moreover difficult to apply to compact furnaces because of the one hand, of the space of regenerative tanks which are equipped with the burners and, on the other hand, the need to install the double of regenerative burners compared to to the number of burners of a standard solution. Regenerative burners operate in pairs, according to a cyclic operation: the burners are half of the time in one mode of combustion and the other half of the time in a mode of accumulation of heat.

OBJET DE L'INVENTIONOBJECT OF THE INVENTION

L'invention a pour but d'améliorer le rendement énergétique d'un four industriel tout en présentant un encombrement acceptable.The invention aims to improve the energy efficiency of an industrial furnace while having an acceptable size.

RESUME DE L'INVENTIONSUMMARY OF THE INVENTION

En vue de la réalisation de ce but, on propose un four industriel pour chauffer des produits tels des produits sidérurgiques, le four comportant une enceinte isolée thermiquement et une pluralité de brûleurs agencés dans l'enceinte pour chauffer les produits circulant d'une extrémité à l'autre de l'enceinte, les brûleurs étant répartis selon une pluralité de zones de chauffage régulées en température. Le four comporte en outre des moyens de récupération destinés à récupérer une énergie thermique de fumées de récupération issues d'une première combustion réalisée par les brûleurs de manière à améliorer un rendement énergétique du four. Selon l'invention, les moyens de récupération comportent un régénérateur tournant associé à chaque zone de chauffage, chacun des régénérateurs tournants étant adapté à recevoir un débit prédéterminé des fumées de récupération via une première conduite, à recevoir un débit prédéterminé d'un air d'alimentation via une deuxième conduite, à préchauffer cet air d'alimentation pour fournir aux brûleurs de la zone de chauffage associée un débit prédéterminé d'air de combustion préchauffé via une troisième conduite, et à évacuer des fumées d'échappement via une quatrième conduite le débit prédéterminé des fumées de récupération reçu par chaque régénérateur tournant étant régulé par des premiers moyens de régulation comportant une première vanne montée sur la quatrième conduite dudit régénérateur tournant.In order to achieve this goal, we propose a industrial furnace for heating products such as steel products, the furnace comprising a thermally insulated enclosure and a plurality of burners arranged in the enclosure for heating the products flowing from one end to the other of the enclosure, the burners being distributed in a plurality of temperature controlled heating zones. The oven further comprises recovery means for recovering thermal energy recovery fumes from a first combustion performed by the burners so as to improve energy efficiency of the furnace. According to the invention, the recovery means comprise a rotating regenerator associated with each heating zone, each of the rotating regenerators being adapted to receive a predetermined flow rate of the recovery fumes via a first pipe, to receive a predetermined flow rate of an air of supply via a second pipe, to preheat this supply air to provide the burners of the associated heating zone a predetermined flow of preheated combustion air via a third pipe, and to exhaust exhaust gases via a fourth pipe the predetermined flow rate of the recovery fumes received by each rotating regenerator being regulated by first regulating means comprising a first valve mounted on the fourth line of said rotating regenerator.

Ainsi, le rendement énergétique du four est amélioré grâce à une récupération d'énergie thermique réalisée au moyen des régénérateurs tournants qui présentent en encombrement acceptable pour la plupart des fours industriels.Thus, the energy efficiency of the furnace is improved through a recovery of thermal energy achieved by means of rotating regenerators which have congestion acceptable for most industrial furnaces.

L'invention sera mieux comprise à la lumière de la description qui suit d'un mode de mise en oeuvre particulier non limitatif de l'invention.The invention will be better understood in the light of the following description of a particular non-limiting embodiment of the invention.

BREVE DESCRIPTION DES DESSINSBRIEF DESCRIPTION OF THE DRAWINGS

Il sera fait référence à la figure unique sur laquelle est représenté schématiquement un four industriel de l'invention.Reference will be made to the single figure on which is schematically represented an industrial furnace of the invention.

DESCRIPTION DETAILLEE DE L'INVENTIONDETAILED DESCRIPTION OF THE INVENTION

L'invention concerne un four industriel pour chauffer des produits tels que des produits sidérurgiques, et est ici mise en application dans un four de préchauffe non-oxydante de bandes d'acier pour lignes continues de traitement de bobines d'acier.The invention relates to an industrial furnace for heating products such as steel products, and is here implemented in a non-oxidizing preheating furnace of steel strips for continuous lines for processing steel coils.

Le four de l'invention 1 comporte une enceinte isolée thermiquement 2, une pluralité de brûleurs 3 agencés dans l'enceinte 2 pour réaliser une première combustion et chauffer une bande d'acier 4 circulant d'une extrémité à l'autre de l'enceinte 2, des moyens dits « de post-combustion » 5 adaptés à réaliser une deuxième combustion, et des moyens de récupération 6.The furnace of the invention 1 comprises a thermally insulated enclosure 2, a plurality of burners 3 arranged in the enclosure 2 to achieve a first combustion and heat a steel strip 4 flowing from one end to the other of the enclosure 2, so-called "post-combustion" means 5 adapted to achieve a second combustion, and recovery means 6.

La pluralité de brûleurs 3 est ici constituée de dix brûleurs 3 répartis selon une pluralité de zones de chauffage régulées en température, en l'occurrence selon trois zones de chauffage Z1, Z2, Z3. Cette répartition permet de réguler la température du four 1 grâce à seulement trois thermocouples 7 positionnés dans les zones de chauffage Z1, Z2, Z3, de manière à conformer la température du four à des courbes de chauffage prédéterminées qui dépendent notamment d'une température de bande souhaitée au niveau d'une sortie de bande S1 du four 1. Les zones de chauffage Z1, Z2, Z3 sont donc régulées selon des consignes de température comprises typiquement entre 1200 et 1350 degrés Celsius pour une température souhaitée de bande au niveau de la sortie de bande S1 du four 1 comprise entre 550 et 750 degrés Celsius.The plurality of burners 3 is constituted by ten burners 3 distributed according to a plurality of temperature-controlled heating zones, in this case according to three heating zones Z1, Z2, Z3. This distribution makes it possible to regulate the temperature of the furnace 1 by virtue of only three thermocouples 7 positioned in the heating zones Z1, Z2, Z3, so as to conform the temperature of the furnace to predetermined heating curves which depend in particular on a heating temperature. The heating zones Z1, Z2, Z3 are thus regulated according to temperature setpoints typically between 1200 and 1350 degrees Celsius for a desired band temperature at the level of the desired band at a strip output S1 of the furnace 1. S1 band output of oven 1 between 550 and 750 degrees Celsius.

La première combustion réalisée par les brûleurs 3 nécessite un combustible, ici du gaz naturel, et un comburant, ici de l'air de combustion Ac.The first combustion performed by the burners 3 requires a fuel, here natural gas, and an oxidant, here combustion air Ac.

Les brûleurs 3 fonctionnent ici en régime dit « sub-stoechiométrique », appelé également combustion en défaut d'air ou bien combustion en gaz riche. Dans le régime sub-stoechiométrique, un débit d'air de combustion est toujours inférieur à un débit d'air nécessaire pour brûler complètement un débit de gaz naturel Gn introduit dans un même brûleur. Des fumées de première combustion F1 sont alors générées par les brûleurs 3, lesdites fumées de première combustion F1 ayant une combustion dite « incomplète », dont une teneur en oxygène est quasiment nulle, l'oxygène de l'air de combustion s'étant combinée entièrement ou presque avec le gaz naturel. Le régime sub-stoechiométrique est particulièrement avantageux puisqu'il permet de conférer aux fumées de première combustion F1 un pouvoir réducteur sur la bande d'acier 4, ce qui permet d'éviter une formation d'oxydes sur la bande d'acier, de type oxydes de fer par exemple, et même de réduire certains oxydes éventuellement présents sur la bande d'acier avant cette première combustion. On améliore ainsi la qualité de la bande d'acier préchauffée par le four de l'invention.The burners 3 operate here in so-called "sub-stoichiometric" mode, also called combustion in air defect or combustion in rich gas. In the sub-stoichiometric regime, a combustion air flow is always less than an air flow necessary to completely burn a flow of natural gas Gn introduced into the same burner. Fumes of first combustion F1 are then generated by the burners 3, said fumes of first combustion F1 having a so-called "incomplete" combustion, an oxygen content of which is practically zero, the oxygen of the combustion air having combined entirely or almost with natural gas. The sub-stoichiometric regime is particularly advantageous since it makes it possible to give the fumes of first combustion F1 a reducing power on the steel strip 4, which makes it possible to avoid the formation of oxides on the steel strip, type of iron oxide for example, and even to reduce some oxides possibly present on the steel strip before this first combustion. This improves the quality of the steel strip preheated by the furnace of the invention.

Les fumées de première combustion F1 sont chargées en composés intermédiaires après la première combustion incomplète, par exemple en dihydrogène ou en oxyde de carbone. L'oxyde de carbone ne peut être rejeté dans l'atmosphère, car il s'agit d'un polluant dont les émissions sont réglementées.The fumes of first combustion F1 are loaded with intermediate compounds after the first incomplete combustion, for example dihydrogen or carbon monoxide. Carbon monoxide can not be released into the atmosphere because it is a pollutant whose emissions are regulated.

Les moyens de post-combustion 5 sont donc utilisés pour réaliser la deuxième combustion, qui consiste à injecter de l'air appelé « air de post-combustion » Apc, dont le rôle est de compléter la première combustion, réalisée par les brûleurs 3, de manière à supprimer des fumées de première combustion F1 les composés intermédiaires. Comme les fumées de première combustion F1 circulent globalement à contre-courant de la bande d'acier 4, les moyens de post-combustion 5 sont situés dans le four 1 en amont des brûleurs 3, c'est-à-dire qu'ils sont situés entre une entrée E du four et les brûleurs 3. L'air de post-combustion Apc est injecté par les moyens de post-combustion 5 selon un débit d'air de post-combustion Apc dosé pour assurer une combustion complète sans ajouter d'air inutile. Avantageusement, l'air de post-combustion Apc est injecté dans une zone de l'enceinte dans laquelle la bande d'acier a une température trop basse pour subir des effets d'une oxydation provoquée par de l'oxygène de l'air de post-combustion Apc en excès. Alternativement, l'air de post-combustion Apc peut être injecté depuis des carneaux d'évacuation des fumées.The post-combustion means 5 are thus used to carry out the second combustion, which consists in injecting air called "post-combustion air" Apc, whose role is to complete the first combustion, carried out by the burners 3, in order to suppress the first combustion fumes F1 the intermediate compounds. Since the fumes of first combustion F1 circulate generally against the current of the steel strip 4, the post-combustion means 5 are located in the furnace 1 upstream of the burners 3, that is to say they are located between an inlet E of the furnace and the burners 3. The post-combustion air Apc is injected by the post-combustion means 5 according to a post-combustion air flow Apc dosed to ensure complete combustion without adding unnecessary air. Advantageously, the post-combustion air Apc is injected into an area of the enclosure in which the steel strip has a temperature that is too low to undergo the effects of oxidation caused by oxygen in the air. post-combustion Apc in excess. Alternatively, the post-combustion air Apc can be injected from flue gas flues.

Des fumées de récupération F2, au moins partiellement dépolluées, sont générées par la deuxième combustion.Recovery fumes F2, at least partially depolluted, are generated by the second combustion.

Les moyens de récupération 6 sont destinés à récupérer une énergie thermique de ces fumées de récupération F2, qui sont donc issues de la première combustion et de la deuxième combustion. On améliore ainsi un rendement énergétique du four 1.The recovery means 6 are intended to recover thermal energy from these recovery fumes F2, which are therefore derived from the first combustion and the second combustion. This improves the energy efficiency of the furnace 1.

Les moyens de récupération 6 comportent un régénérateur tournant 7 associé à chaque zone de chauffage Z1, Z2, Z3, et donc ici trois régénérateurs tournants 7. Le rôle de ces régénérateurs tournants 7 est de réchauffer un débit prédéterminé d'air d'alimentation 8 de manière à fournir un débit prédéterminé d'air de combustion préchauffé 9. Le fait d'utiliser un air de combustion Ac préchauffé permet en effet d'augmenter nettement le rendement de la première combustion en diminuant la quantité de gaz naturel Gn nécessaire à celle-ci, et donc d'augmenter le rendement énergétique du four de l'invention 1.The recovery means 6 comprise a rotating regenerator 7 associated with each heating zone Z1, Z2, Z3, and thus here three rotating regenerators 7. The role of these rotating regenerators 7 is to heat a predetermined flow of supply air 8 so as to provide a predetermined flow rate of preheated combustion air 9. The fact of using a preheated combustion air Ac makes it possible to significantly increase the efficiency of the first combustion by decreasing the amount of natural gas Gn required for that and, therefore, to increase the energy efficiency of the furnace of the invention 1.

Chaque régénérateur tournants 7 est adapté à recevoir un débit prédéterminé de fumées de récupération 10 via une première conduite 11, à recevoir le débit prédéterminé d'air d'alimentation 8 via une deuxième conduite 12, à préchauffer cet air d'alimentation Aa pour fournir aux brûleurs 3 de la zone de chauffage associée au régénérateur tournant 7 le débit prédéterminé d'air de combustion préchauffé 9 via une troisième conduite 14, et à évacuer des fumées d'échappement F3 via une quatrième conduite 15.Each rotary regenerator 7 is adapted to receive a predetermined flow of recovery fumes 10 via a first pipe 11, to receive the predetermined flow of supply air 8 via a second pipe 12, to preheat this supply air Aa for supplying to the burners 3 of the heating zone associated with the rotating regenerator 7 the predetermined flow rate of preheated combustion air 9 via a third pipe 14, and discharging exhaust fumes F3 via a fourth pipe 15.

Chaque régénérateur tournant 7 est alimenté en continu par le débit prédéterminé d'air d'alimentation 8 et par le débit prédéterminé de fumées de récupération 10. Chaque régénérateur tournant 7 comporte, de façon connue en elle-même, des compartiments en rotation qui sont mis en communication une première moitié du temps avec la première conduite 11, ce qui permet un réchauffement de l'intérieur du régénérateur 7, puis une deuxième moitié du temps avec la deuxième conduite 12, ce qui permet d'alimenter en air d'alimentation Aa le régénérateur tournant 7. L'air d'alimentation Aa, qui n'est jamais en contact avec les fumées de récupération, est ainsi préchauffé, ce qui permet de fournir au brûleur 7 associé le débit prédéterminé d'air de combustion préchauffé 9.Each rotating regenerator 7 is fed continuously by the predetermined flow of feed air 8 and by the predetermined flow rate of recovery fumes 10. Each rotating regenerator 7 comprises, in a manner known per se, rotating compartments which are placed in communication a first half of the time with the first pipe 11, which allows a warming of the interior of the regenerator 7, then a second half of the time with the second pipe 12, which allows to supply air supply Aa the rotating regenerator 7. The supply air Aa, which is never in contact with the recovery fumes, is thus preheated, which allows to provide the associated burner 7 the predetermined flow of preheated combustion air 9 .

Les fumées de récupération F2 sont réparties dans chaque régénérateur tournant 7 de manière à toujours conserver un certain rapport de répartition entre le débit prédéterminé d'air d'alimentation 8 et le débit prédéterminé de fumées de récupération 10.The recovery fumes F2 are distributed in each rotating regenerator 7 so as to always maintain a certain distribution ratio between the predetermined flow rate of supply air 8 and the predetermined flow rate of recovery fumes 10.

Avantageusement, on vise un rapport de répartition entre le débit prédéterminé d'air d'alimentation 8 et le débit prédéterminé de fumées de récupération 10 compris entre 1 et 1,2 environ, un tel rapport de répartition permettant d'optimiser le rendement énergétique du four de l'invention.Advantageously, a distribution ratio is set between the predetermined flow rate of supply air 8 and the predetermined flow rate of recovery fumes 10 of between approximately 1 and 1.2, such a distribution ratio making it possible to optimize the energy efficiency of the furnace of the invention.

Pour obtenir le rapport de répartition souhaité, on régule tout d'abord le débit prédéterminé de fumées de récupération 10 reçu par chaque régénérateur tournant 7 par des premiers moyens de régulation comportant une première vanne 17 montée sur la quatrième conduite 15 dudit régénérateur tournant 7. Ainsi, pour chaque régénérateur tournant 7, le débit prédéterminé de fumées de récupération 10 est régulé indirectement, grâce à une régulation du débit des fumées d'échappement F3. Cette régulation est effectuée au moyen notamment de la première vanne 17 qui est montée en aval dudit régénérateur tournant 7, c'est-à-dire qui est située entre le régénérateur tournant 7 et une sortie de fumées S2 du four qui est ici mise en communication avec une cheminée 25 par laquelle les fumées d'échappement sont évacuées du four 1.In order to obtain the desired distribution ratio, the predetermined flow rate of recovery fumes received by each rotating regenerator 7 is first regulated by first regulating means comprising a first valve 17 mounted on the fourth line 15 of said rotating regenerator 7. Thus, for each rotating regenerator 7, the predetermined flow rate of recovery fumes 10 is regulated indirectly, through a regulation of the flow of exhaust fumes F3. This regulation is effected by means in particular of the first valve 17 which is mounted downstream of said rotary regenerator 7, that is to say which is located between the rotating regenerator 7 and a furnace exhaust outlet S2 which is here implemented. communication with a chimney 25 through which the exhaust fumes are removed from the furnace 1.

On régule de plus le débit prédéterminé d'air d'alimentation 8 reçu par chaque régénérateur tournant 7 par des deuxièmes moyens de régulation comportant une deuxième vanne 20 montée sur la deuxième conduite 12 dudit régénérateur tournant 7. Ainsi, pour chaque régénérateur tournant 7, le débit prédéterminé d'air d'alimentation 8 est régulé directement au moyen notamment de la deuxième vanne 20, ce qui permet d'éliminer d'éventuelles imprécisions de régulation dues à d'éventuelles fuites entre air d'alimentation et fumées de récupération à l'intérieur des régénérateurs tournants 7.The predetermined flow rate of supply air 8 received by each rotating regenerator 7 is further regulated by second regulating means comprising a second valve 20 mounted on the second pipe 12 of the said rotary regenerator 7. Thus, for each rotating regenerator 7, the predetermined flow rate of supply air 8 is regulated directly by means in particular of the second valve 20, which makes it possible to eliminate any regulatory inaccuracies due to possible leaks between feed air and recovery fumes. inside the rotating regenerators 7.

Il est nécessaire, pour réguler le débit prédéterminé des fumées de récupération 10 et le débit prédéterminé d'air d'alimentation 8, de mesurer le débit prédéterminé d'air de combustion 9. On monte pour cela un débitmètre 21 sur la troisième conduite 14 de chaque régénérateur tournant 7, chaque débitmètre 21 étant adapté à mesurer le débit d'air de combustion 9 fourni aux brûleurs 3 de la zone de chauffage Z1, Z2, Z3 associée audit régénérateur tournant 7. Avantageusement, on privilégie une mesure de débit générant peu de perte de pression dans la conduite, ce qui permet de maintenir l'air de combustion à une pression relativement faible. On choisira ainsi préférablement un débitmètre 21 de type à tube de Venturi ou à tube de Pitot ou à effet Vortex.It is necessary, in order to regulate the predetermined flow rate of the recovery fumes 10 and the predetermined feed air flow 8, to measure the predetermined flow rate of combustion air 9. To do this, a flowmeter 21 is mounted on the third conduit 14 each rotating regenerator 7, each flowmeter 21 being adapted to measure the combustion air flow rate 9 supplied to the burners 3 of the heating zone Z1, Z2, Z3 associated with said rotating regenerator 7. Advantageously, a flow measurement generating little loss of pressure in the pipe, which helps maintain combustion air at a relatively low pressure. Preferably, a flowmeter 21 of the Venturi tube or Pitot tube or Vortex effect type will be chosen.

L'air de combustion préchauffé est porté à des températures comprises typiquement entre 800 degrés Celsius et 1000 degrés Celsius, alors que les fumées d'échappement sont portées à des températures comprises typiquement entre 150 degrés Celsius et 250 degrés Celsius.The preheated combustion air is brought to temperatures typically between 800 degrees Celsius and 1000 degrees Celsius, while the exhaust fumes are brought to temperatures typically between 150 degrees Celsius and 250 degrees Celsius.

On note ici que les premiers et deuxièmes moyens de régulation, comportant respectivement les premières 17 et deuxièmes vannes 20, sont situés sur les quatrièmes 15 et deuxièmes conduites 8, qui présentent des températures relativement faibles par rapport aux premières 11 et troisièmes conduites 14. Ces moyens de régulation constituent donc une solution moins onéreuse et plus fiable qu'une solution similaire située sur les conduites plus chaudes.It should be noted here that the first and second regulating means, comprising respectively the first 17 and second valves 20, are situated on the fourth and second conduits 8, which have relatively low temperatures relative to the first 11 and third lines 14. Control means are therefore a less expensive and more reliable solution than a similar solution located on the hotter pipes.

On vise de plus à être en mesure d'assurer si nécessaire une étanchéité totale entre la troisième conduite 14 et l'intérieur de l'enceinte thermiquement isolé 2. En effet, lorsqu'une ou plusieurs zones de chauffage Z1, Z2, Z3 sont à l'arrêt, en raison par exemple d'une diminution d'une vitesse de circulation de la bande d'acier 4 dans l'enceinte 2, une pénétration d'air de combustion dans l'enceinte doit absolument être évitée. Une telle pénétration d'air aurait tendance à diminuer les avantages du régime sub-stoechiométrique évoqué plus tôt.It is furthermore intended to be able to ensure, if necessary, a complete seal between the third pipe 14 and the inside of the thermally insulated enclosure 2. In fact, when one or more heating zones Z1, Z2, Z3 are when stopped, for example due to a decrease in a speed of movement of the steel strip 4 in the chamber 2, a combustion air penetration into the chamber must absolutely be avoided. Such air penetration would tend to diminish the benefits of the sub-stoichiometric regime discussed earlier.

Comme une simple vanne ne peut être parfaitement étanche, on monte sur la troisième conduite 14 de chaque régénérateur tournant deux vannes de sectionnement 22, et on monte sur la troisième conduite 14 des moyens d'injection 23 de gaz inerte, en l'occurrence de l'azote, pour remplir de gaz un espace entre les deux vannes de sectionnement 23. On maintient ainsi une pression positive entre les deux vannes de sectionnement 23, de sorte qu'en cas de fuite au niveau de l'une des vannes de sectionnement, seul un débit de fuite de gaz inerte pourra pénétrer dans l'enceinte 2.As a simple valve can not be perfectly sealed, the third pipe 14 of each regenerator rotating two shutoff valves 22 is mounted on the third pipe 14, and inert gas injection means 23 is mounted on the third pipe 14. nitrogen, to fill a gas gap between the two valves of 23. This maintains a positive pressure between the two shutoff valves 23, so that in case of leakage at one of the shutoff valves, only an inert gas leakage flow can enter the enclosure 2.

Avantageusement, l'air de post-combustion (Apc) provient en partie de l'air de combustion préchauffé généré par au moins un régénérateur tournant, éventuellement surdimensionné à cet effet. Ceci permet améliorer encore le rendement énergétique du four de l'invention.Advantageously, the post-combustion air (Apc) comes in part from the preheated combustion air generated by at least one rotating regenerator, possibly oversized for this purpose. This allows to further improve the energy efficiency of the oven of the invention.

L'invention n'est pas limité au mode de réalisation particulier qui vient d'être décrit, mais, bien au contraire, couvre toute variante entrant dans le cadre de l'invention telle que définie par les revendications.The invention is not limited to the particular embodiment which has just been described, but, on the contrary, covers any variant within the scope of the invention as defined by the claims.

Il est notamment possible de prévoir un four comportant un nombre différent de brûleurs répartis selon un nombre différent de zones de chauffage.It is in particular possible to provide an oven having a different number of burners distributed according to a different number of heating zones.

Les gammes de température fournies le sont à titre indicatif, et peuvent bien sûr différer dans des applications différentes utilisant le four de l'invention.The ranges of temperature provided are indicative, and may of course differ in different applications using the oven of the invention.

Claims (9)

  1. An industrial furnace for heating products (4) such as steel products, the furnace comprising a thermally-insulated enclosure (2) and a plurality of burners (3) arranged in the enclosure (2) for heating the products passing from one end of the enclosure to the other, the burners (3) being distributed over a plurality of temperature-regulated heating areas (Z1, Z2, Z3), the furnace further comprising recovery means (6) designed for recovering heat energy from recovery fumes (F2) by means of a first combustion performed by the burners in such a manner as to improve energy efficiency of the furnace;
    the furnace being characterized in that the recovery means (6) comprise a rotary regenerator (7) associated with each heating area (Z1, Z2, Z3), each of the rotary regenerators (7) being suitable for receiving a predetermined flow rate of recovery fumes (10) via a first duct (11), for receiving a predetermined flow rate of supply air (8) via a second duct (12), for preheating said supply air in order to supply the burners (3) of the associated heating area with a predetermined flow rate of preheated combustion air (9) via a third duct (14), and for discharging exhaust fumes (F3) via a fourth duct (15), wherein the predetermined flow rate of recovery fumes (10) received by each rotary regenerator (7) is regulated by first regulator means comprising a first valve (17) mounted on the fourth duct (15) of said rotary regenerator (7).
  2. An industrial furnace according to claim 1, wherein the predetermined flow rate of supply air (8) received by each rotary regenerator (7) is regulated by second regulator means comprising a second valve (20) mounted on the second duct (12) of said rotary regenerator (7).
  3. An industrial furnace according to claim 1, wherein, for each rotary regenerator, a flowmeter (21) is mounted on the third duct (14) of said rotary regenerator (7).
  4. An industrial furnace according to claim 3, wherein at least one of the flowmeters is of the Venturi tube or Pitot tube or Vortex effect type flowmeter.
  5. An industrial furnace according to claim 1, wherein, for each rotary regenerator, two disconnector valves (22) are mounted on the third duct (11), and gas injection means (23) are mounted on the third duct (14) in order to fill the space between the two disconnector valves (22) with inert gas.
  6. An industrial furnace according to claim 5, wherein the injected gas is nitrogen.
  7. An industrial furnace according to any preceding claim, wherein the recovery fumes are generated by a second combustion making it possible to finish off the first combustion performed by the burners (3).
  8. An industrial furnace according to claim 7, wherein post-combustion air (Apc) used for the second combustion comes in part from the preheated combustion air (Ac) generated by at least one rotary regenerator (7).
  9. An industrial furnace according to any preceding claim, wherein a ratio between the predetermined flow rate of supply air (8) and the predetermined flow rate of recovery fumes (10) lies in the range 1 to 1.2.
EP15705323.2A 2014-03-04 2015-02-20 Industrial furnace for heating products such as steel products Not-in-force EP3114243B1 (en)

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FR1451767A FR3018344B1 (en) 2014-03-04 2014-03-04 INDUSTRIAL OVEN FOR HEATING PRODUCTS SUCH AS STEEL PRODUCTS
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EP3839340A1 (en) * 2019-12-18 2021-06-23 Linde GmbH Method and device for heating a furnace
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US20170082364A1 (en) 2017-03-23
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CN106164302A (en) 2016-11-23
FR3018344B1 (en) 2016-04-29

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