EP0286984A1 - Four de réchauffage muni de brûleurs à flamme rotative pour plaques et billettes - Google Patents

Four de réchauffage muni de brûleurs à flamme rotative pour plaques et billettes Download PDF

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Publication number
EP0286984A1
EP0286984A1 EP88105593A EP88105593A EP0286984A1 EP 0286984 A1 EP0286984 A1 EP 0286984A1 EP 88105593 A EP88105593 A EP 88105593A EP 88105593 A EP88105593 A EP 88105593A EP 0286984 A1 EP0286984 A1 EP 0286984A1
Authority
EP
European Patent Office
Prior art keywords
furnace
burners
rotating
burner
flame
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.)
Granted
Application number
EP88105593A
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German (de)
English (en)
Other versions
EP0286984B1 (fr
Inventor
Vittorio Levaggi
Catello Bruno
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.)
Italimpianti SpA
Original Assignee
Italimpianti SpA
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority claimed from IT8712465A external-priority patent/IT1208279B/it
Priority claimed from IT8712587A external-priority patent/IT1213939B/it
Application filed by Italimpianti SpA filed Critical Italimpianti SpA
Priority to AT88105593T priority Critical patent/ATE68528T1/de
Publication of EP0286984A1 publication Critical patent/EP0286984A1/fr
Application granted granted Critical
Publication of EP0286984B1 publication Critical patent/EP0286984B1/fr
Expired legal-status Critical Current

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Classifications

    • 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
    • F27D99/00—Subject matter not provided for in other groups of this subclass
    • F27D99/0001—Heating elements or systems
    • F27D99/0033—Heating elements or systems using burners
    • F27D99/0035—Heating indirectly through a radiant surface
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/34—Methods of heating
    • C21D1/52—Methods of heating with flames
    • 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
    • C21D9/0081—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for slabs; for billets
    • 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
    • F27B9/201—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 walking beam 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
    • F27B9/30—Details, accessories, or equipment peculiar to furnaces of these types
    • F27B9/36—Arrangements of heating devices

Definitions

  • the invention relates to a reheating furnace for iron and steel products, particularly for slabs, billets, and the like.
  • a furnace is provided on the furnace roof and/or on at least one of the longitudinal sidewalls and/or transversal endwalls thereof with a plurality of burners having their flame rotatin around the central axis of the respective burner.
  • the rotating-flame burners for a reheating furnace for iron and steel products are known, for example, from the document DE-A-2 801 367.
  • the flame is rotated by the combustion air flowing around the fuel nozzle and being imparted a rotary motion by suitably inclined means for guiding the combustion air flow, such as inclined guide vanes or inclined ports, or by any other suitable swirl device.
  • the fluid-dynamic conditions of the combustion air flow and speed of rotation may be so selected as to obtain a longer or a shorter rotating flame, or a disc-shaped flat flame.
  • Burners with their flame being a flat or a disc-shaped rotating flame i.e., the so-called radiant burners
  • the so-called radiant burners are preferably, but not exclusively installed on the roof of a reheating furnace for iron and steel products, and are arranged, for example, in one or more parallel rows extending in the longitudinal direction of the furnace.
  • the flames of all the rotating-­flame burners fitted on the furnace roof rotate in the same, either clockwise or anticlockwise direction, which results in the following inconveniences.
  • the rotating-flame burners on the furnace roof are flat-­flame burners, these flames bring about a turbulence in the furnace atmosphere only in a limited zone which is near to the furnace roof.
  • the turbulence in the furnace atmosphere decreases to an almost zero value, so that the flue gases become stratified, and the vertical exchanges in the furnace atmosphere are sensibly reduced. This determines a deficiency of the oxygen content in the furnace atmosphere, at the level of the iron and steel products to be reheated.
  • the oxygen contained in the furnace atmosphere forms a superficial layer of oxides on the iron and steel products to be reheated.
  • the oxygen content in the furnace atmosphere at the level of the products to be reheated has an optimum value, such as, for example, in the order of 1-2%, a layer of oxides is formed on the surface of the reheated iron and steel products, which can be entirely removed in a relatively easy manner.
  • the oxygen content in the furnace atmosphere at the level of the to-be-reheated iron and steel products goes down below the said optimum value, such as in the case of the said lack of vertical exchanges in the furnace atmosphere, owing to the unidirectional rotation of the flames of all the burners on the furnace roof, a layer of oxides is formed on the surface of the to-be-reheated products, which is thinner, but which is a harder and rather firmly sitcking layer.
  • This latter layer of oxides is difficult to be removed, so that on the reheated iron and steel products there is still left a residue of oxides, that gives rise to some inconveniences on the subsequent rolling of the reheated products, and that sensibly lowers the grade of the rolled products.
  • a unidirectional horizontal circulation of flue gases is thus produced, particularly in the upper part of the furnace.
  • a circulation of flue gases consists of a flue gas stream in one direction, close to one longitudinal sidewall of the furnace, and a reversed flue gas stream, i.e., in the opposite direction, close to the other longitudinal sidewall of the furnace.
  • the average flue gas temperature near the wall beside which the flue gases stream horizontally in the direction of the moved forward products to be reheated is lower than the temperature which is attained near the opposite longitudinal sidewall of the furnace, where the flue gase stream is a reversed stream, which runs in the opposite direction to the moved forward products to be reheated.
  • Burners having a longer or shorter rotating flame are preferably, but non exclusively installed on the longitudinal sidewalls and/or on the transversal endwalls of a furnace for reheating iron and steel products, and are arranged, for example, in at least one horizontal row. Also in this case, in the known embodiments the flames of all the rotating-flame burners fitted on the longitudinal disewalls and/or transversal endwalls of the furnace rotate in the same, either clockwise or anticlockwise direction, which leads to the following inconveniences.
  • the unidirectional rotation of the flame of the burners provided on one or the longitudinal sidewalls of the furnace produces beside the respective wall a stable vertical circulation of flue gases, with a horizontal flue gas stream in one direction under the burner row or rows, and with a reversed horizontal stream in the opposite direction over the burner row or rows.
  • a flue gas circulation brings about an undesired not uniform distribution of pressure in the inside of the furnace, so that difficulties are encountered in the control of said pressure.
  • the said vertical circulation of flue gases along one of the longitudinal sidewalls of the furnace gives rise in a furnace provided with a chimney at either ends thereof, to a sensibly unbalanced distribution of flue gases between the two chimneys, which involves a considerable lowering of the furnace efficiency, since the two heat recuperators associated with the two chimneys are operating respectively at a lower and at a higher flue gas outflow rate than their established rate.
  • the said not uniform distribution of temperature is of a higher degree in a bilaterally heated furnace, when at least one row of rotating-flame burners are provided on both of the longitudinal sidewalls of the furnace.
  • burners of the same type i.e. with their flame rotating in the same, either clockwise or anticlockwise direction
  • a known furnace for both of the longitudinal sidewalls of the furnace. Consequently, on the two facing longitudinal sidewalls of the furnace vertically circulating currents will be generated, which rotate in the same, either clockwise or anticlockwise direction, while their horizontal streams which have formed under a row or under respective rows of burners, and which take in any cold air inleakage from below, run in opposite directions.
  • the temperature drop under the burner row or rows then occurs at both longitudinal sidewalls of the furnace and, particularly in the reheating furnaces for slabs or billets extending transversely to the furnace throughout its length, leads to a correspondingly lower heating of both of the slabs or billets ends.
  • Such an uneven heating of slabs or billets gives rise to difficulties in the subsequent rolling of the same, due to their not uniform hardness.
  • the object of the invention is to eliminate the above disclosed inconveniences in the known furnaces, and this object is achieved by the provision in a furnace of the type as described in the preamble, of two different types of burners, one burner type with the flame rotating in clockwise direction, and the other burner type with the flame rotating in anticlockwise direction.
  • the flames of at least two adjacent burners rotate in opposite directions.
  • the burners in each row alternately have their flames rotating in opposite directions.
  • each burner belonging to one row and having its flame rotating in one direction is located at the side of a burner belonging to an adjacent row and having its flame rotating in the opposite direction. Irrespective of the arrangement of the burners, it is generally aimed at having each burner with its flame rotating in one direction, at least partly encircled by burners with their flames rotating in the opposite direction.
  • the rotation in opposite directions of the flames of the burners in a furnace according to the invention can be achieved by means of any suitable means.
  • the means for guiding the combustion air flow which, for example, consist of inclined guide vanes or inclined ports, are inclined in opposite directions.
  • FIG. 1 As an example of a reheating furnace for iron and steel products, in Figure 1 there is shown a walking beam furnace for reheating slabs B, billets, or the like.
  • the invention may be however applied to any other types of reheating furnaces, for example, to pusher furnaces or pit furnaces, and for any other kind of iron and steel products.
  • numeral 1 denotes the stationary beams
  • numeral 2 denotes the walking beams supported by uprights 3 passed through openings 4 provided in the furnace bottom 5.
  • each burner A1, A2 comprises a central fuel pipe 6 opening into an inwardly curved flared portion 17 in the furnace wall.
  • the pipe 6 is connected through the pipe fitting 106 to the fuel distribution system, and this pipe is surrounded by a casing 7 for the supply of combustion air.
  • the casing 7 is connected through the pipe fitting 107 to the combustion air distribution system, and this casing opens into the inwardly curved flared portion 17 through a diffuser 8 provided around the outlet of the fuel pipe 6.
  • the diffuser 8 comprises a circular arrangement of stationary guide vanes 108 which are substantially tangent to the central fuel pipe 6. In the burner type A1 the guide vanes 108 in the diffuser 8 are inclined in one direction, while in the burner type A2 the guide vanes 108 in the diffuser 8 are inclined in the opposite direction.
  • the combustion air flowing through the diffuser 8 in the burner type A1 is imparted a rotation in the opposite direction to the rotation of the combustion air flowing through the diffuser 8 in the burner type A2.
  • the flame generated by the burner type A1 rotates in one direction, for example, in clockwise direction
  • the flame generated by the burner type A2 rotates in the opposite direction, for example, in anticlockwise direction.
  • Both types of rotating-flame burners A1, A2 shown in Figures 3, 4 and 5, are operated particularly with gaseous fluid that is also imparted a rotary motion by a helical swirl device 9 provided in the outlet end of the fuel pipe 6.
  • the two types of rotating-flame burners A1, A2 can be operated even or only with liquid fuel when a suitable spray nozzle, or the like, is provided at the end of the fuel pipe 6.
  • the casing 7 for the supply of combustion air may be set in communication with any other suitable type of diffuser provided around the outlet of the fuel pipe 6, and adapted for imparting a clockwise or anticlockwise rotation to the outflowing combustion air, and so to the generated flame.
  • a diffuser of this type may, for example, consist of a plurality of air outflow ports provided in the bottom of the inwardly curved flared portion 17, and inclined in one direction for the burner type A1, and in the opposite direction for the burner type A2.
  • a set of burners A1, A2 are provided and arranged in a plurality of parallel rows F1, F2, F3, F4 extending in the longitudinal direction of the furnace 1.
  • Each burner row F1, F2, F3, F4 is formed by a succession of the two alternated burner types A1, A2, i.e., by a row of burners A1, A2 having by turns their flames rotating in clockwise and in anticlockwise direction.
  • the two alternated types of burners A1, A2 in each row F1, F2, F3, F4 are also offset with respect to the two alternated burner types A1, A2 in the adjacent row or rows, so that at the side of each burner A1 or A2 belonging to one of the rows F1, F2, F3, F4 and having its flame rotating in one direction, for example, in clockwise direction, one or two burners A2 or A1 are located, which belong to the adjacent row or rows, and have their flame rotating in the opposite, for example, anticlockwise direction.
  • the furnace C according to Figure 1 may be heated by burners provided on at least one of the two longitudinal sidewalls of the furnace, and/or on at least one of the two transversal endwalls thereof.
  • a horizontal row F5 of rotating-flame burners is provided over the beams 1, 2 and then over the slabs B or billets to be reheated, and a horizontal row F6 of rotating-­flame burners is provided thereon, under the beams 1, 2 and then under the slabs B or billets to be reheated.
  • Each burner row F5, F6 is formed by the above-­disclosed two burner types A1, A2, and the flame of one burner type (A1) rotates in clockwise direction, while the flame of the other burner type (A2) rotates in anticlockwise direction.
  • each row F5 F6, these two types of burners A1, A2 are alternated, so that on one or both sides of each burner A1 with its flame rotating in clockwise direction, there is placed a burner A2 with its flame rotating in anticlockwise direction, and vice-versa.
  • the fluid-dynamic conditions of the combustion air flow and rotation in the two types of rotating-flame burners A1, A2 fitted on the longitudinal sidewall or sidewalls 11 of furnace C, are so selected that these burners will generate a longer or a shorter flame.
  • a similar alternated arrangement of burners A1, A2 with their flames rotating in clockwise and in anticlockwise direction, may be provided also on at least one of the transversal endwalls 12 of the furnace C.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Tunnel Furnaces (AREA)
  • Heat Treatment Of Articles (AREA)
EP19880105593 1987-04-16 1988-04-08 Four de réchauffage muni de brûleurs à flamme rotative pour plaques et billettes Expired EP0286984B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT88105593T ATE68528T1 (de) 1987-04-16 1988-04-08 Erwaermungsofen mit rotierende flammen erzeugenden brennern fuer brammen und bloecke.

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
IT1246587 1987-04-16
IT8712465A IT1208279B (it) 1987-04-16 1987-04-16 Forno di riscaldo per bramme e billette equipaggiato con bruciatori radianti con rotazione controversa dell aria comburente
IT8712587A IT1213939B (it) 1987-11-26 1987-11-26 Forno di riscaldo per bramme e billette equipaggiato con bruciatori la cui fiamma ruota in un senso per alcuni e nel senso inverso per altri
IT1258787 1987-11-26

Publications (2)

Publication Number Publication Date
EP0286984A1 true EP0286984A1 (fr) 1988-10-19
EP0286984B1 EP0286984B1 (fr) 1991-10-16

Family

ID=26326530

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19880105593 Expired EP0286984B1 (fr) 1987-04-16 1988-04-08 Four de réchauffage muni de brûleurs à flamme rotative pour plaques et billettes

Country Status (5)

Country Link
EP (1) EP0286984B1 (fr)
BR (1) BR8801816A (fr)
CA (1) CA1294126C (fr)
DE (1) DE3865493D1 (fr)
ES (1) ES2025720T3 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1500889A1 (fr) * 2003-07-25 2005-01-26 Tck S.R.L. Systême de contrôle d'un four pour des céramiques
JP2012078082A (ja) * 2010-09-30 2012-04-19 Linde Ag 工業用炉の炉内燃焼制御法

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT1287626B1 (it) * 1996-02-27 1998-08-06 Sacmi Forni Spa Forno monostrato per piastrelle

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1432434A (fr) * 1965-05-10 1966-03-18 Armco Steel Corp Procédé et four pour le chauffage de pièces métalliques
FR2124881A5 (en) * 1971-02-02 1972-09-22 British Steel Corp Continuous annealing of steel strip -with heat exchange between - outgoing and ingoing strip
EP0137362A2 (fr) * 1983-09-23 1985-04-17 VEB Rohrkombinat Stahl- und Walzwerk Riesa Elément radiant de gros format pour four industriels

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1432434A (fr) * 1965-05-10 1966-03-18 Armco Steel Corp Procédé et four pour le chauffage de pièces métalliques
FR2124881A5 (en) * 1971-02-02 1972-09-22 British Steel Corp Continuous annealing of steel strip -with heat exchange between - outgoing and ingoing strip
EP0137362A2 (fr) * 1983-09-23 1985-04-17 VEB Rohrkombinat Stahl- und Walzwerk Riesa Elément radiant de gros format pour four industriels

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
STEEL IN THE U.S.S.R., vol. 10, no. 4, April 1980, pages 224-227; L.G. ORKIN et al.: "Operating experience with roof-fired continuous furnace of 1700 mill" *
STEEL IN THE U.S.S.R., vol. 9, no. 2, February 1979, pages 99-100; O.I. GOLOLOBOV et al.: "Use of disc-flame burner for roof firing of heating furnaces" *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1500889A1 (fr) * 2003-07-25 2005-01-26 Tck S.R.L. Systême de contrôle d'un four pour des céramiques
JP2012078082A (ja) * 2010-09-30 2012-04-19 Linde Ag 工業用炉の炉内燃焼制御法

Also Published As

Publication number Publication date
BR8801816A (pt) 1988-11-16
EP0286984B1 (fr) 1991-10-16
DE3865493D1 (de) 1991-11-21
CA1294126C (fr) 1992-01-14
ES2025720T3 (es) 1992-04-01

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