US3781166A - Industrial furnace - Google Patents

Industrial furnace Download PDF

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Publication number
US3781166A
US3781166A US00171675A US3781166DA US3781166A US 3781166 A US3781166 A US 3781166A US 00171675 A US00171675 A US 00171675A US 3781166D A US3781166D A US 3781166DA US 3781166 A US3781166 A US 3781166A
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US
United States
Prior art keywords
furnace
burners
floor
burner
scale
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.)
Expired - Lifetime
Application number
US00171675A
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English (en)
Inventor
E Bunzel
R Spessert
K Rieskamp
W Hildebrand
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.)
OFU Ofenbau Union GmbH
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OFU Ofenbau Union GmbH
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
Application filed by OFU Ofenbau Union GmbH filed Critical OFU Ofenbau Union GmbH
Application granted granted Critical
Publication of US3781166A publication Critical patent/US3781166A/en
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Expired - Lifetime legal-status Critical Current

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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
    • F27B9/14—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
    • F27B9/22—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 on rails, e.g. under the action of scrapers or pushers

Definitions

  • This invention relates to industrial furnaces having heating chambers in which the material to be heated is conveyed in a generally horizontal plane spaced from both the ceiling and the floor.
  • Upper heating means preferably a plurality of burners are distributed over the width and length of the furnace roof and discharge a downwardly directed fuel jet for combustion above the plate.
  • Such furnaces per se are known and have a relatively high capacity since the plates can be conveyed through the heating space of the furnace while in a horizontal position. The capacity can be further increased by conveying the plates through the furnace at a more rapid rate. This, however, necessitates l a correspondingly longer heating space.
  • Industrial furnaces having increasingly large hearth areas. and heating spaces often give rise to a non-uniform heating of the material. Even with burners arranged in the furnace ceiling satisfactory results cannot be obtained since the burners only heat the upper side of the plate as the plate moves through the furnace. The lower side of the plate is not contacted by the flame and is. heated by heat transmission through the plate. Its temperature, therefore, varies substantially from the temperature of the upper plate side which is contacted by the flame.
  • Another prior art furnace of the general type discussed above transports the material to be'heated in an upright, vertically standing position through the furnace past burners positioned on both sides of the material and mounted to the furnace ceiling. To the extend necessary additional burners are provided in the furnace floor which direct flame in a generally upward direction.
  • the aforementioned problems of non-uniform heating do not exist in this furnace because the material is subjected to direct heat or flame on both sides thereof.
  • the transport of plates in an upright position particularly when heated is difficult and can result in a deformation of the plates, buckling, warping or the like.
  • the present invention provides an industrial furnace for heating large objects such as flat plate and the like in which the plate is conveyed through the furnace in a fully supported, essentially horizontal position and in which the plate is heated from both the upper and lower sides to assure a uniform heating of the material at a high speed.
  • the industrial furnace of the present invention em- I
  • the floor burners apply heat directly to the underside of the plates. This is particularly important once relatively large amounts of heat energy are withdrawn from the plate underside through its contact with cooled slide rails and supports. Clogging of the upwardly directed burner nozzles from falling scale is prevented since the burners automatically blow themselves clean. Between adjacent floor burners and the underside of the plate there is a downwardly directed flow which directs scale to and deposits the scale in the area between adjacent burners.
  • the burner nozzles preferably are elevated above the furnace bottom level on which scale collects.
  • the burner nozzles are arranged in parallel rows and on continuous banks defined by the furnace floor.
  • a trough is defined between the banks from which the scale is easily removed with scrapers or the like.
  • transverse support members are provided in the furnace which mount longitudinally extending slide rails upon which the plates or other material moves through the furnace.
  • the burner nozzles are aligned with the support members to thereby more effectively maintain a substantially uniform heat and/or heat build-up as the plate moves through the furnace by more evenly supporting the burners flames over the underside of the plate.
  • each burner is preferably provided with a free, straight and vertically disposed burner tube or duct that has a radially extending fuel supply conduit adjacent its lower end.
  • the lower end of the tube or duct is connected to a lower scale bag or collector which is closed with a suitable door for periodic cleaning. If scale falls on to the burner it drops through the vertical burner tube for subsequent removal from the scale collector.
  • the burners are preferably high speed burners which can be regulated from a full-load operating mode at which the heel and/or flame (hereafter gas) is discharged at a speed at least about to meters per second to a throttled operating mode at which the gas is discharged at a speed as little as one-seventh that speed or a minimum gas discharge speed of about 11 meters per second.
  • the burners are preferably free jet burners, that is burners which discharge gases in a substantially uniform stream that spreads into a cone after the gas is released by the burner nozzle.
  • the burner further preferably imparts a swirl or rotating component to the discharged gas. Without such swirl component the discharged gas cone is smaller. With the swirl component the cone is upwardly and outwardly flared. If, therefore, burners having a swirl component are used the overall number of burners can be smaller since each covers a larger area than that covered by a burner discharging the gas without swirl component.
  • FIG. 1 is a front elevational schematic representation of an industrial furnace
  • FIG. 2 is a side elevational representation of the furnace shown in FIG. 1.
  • the industrial furnace shown in the drawings is a pusher type, slab heating furnace. It is apparent that the furnace can be any other type of industrial furnace as, for example, a lifting hearth furnace.
  • the furnace In the heating space 1 of the furnace are a plurality of parallel rows of support members 2 arranged side by side in the transport direction V in which slabs 6 move through the furnace.
  • the supports are cooled with water flowing through suitable cooling pipes 3.
  • Mounted on top of the support members are a plurality of side by side, parallel slide rails which extend in the transport direction V and which are cooled by water flown through cooling pipes 5.
  • the heating space of the furnace has a sufficient width so that two slabs 6 can be simultaneously conveyed through the furnace side by side in the transport direction.
  • a plurality of downwardly facing upper burners 8 are installed in furnace ceiling 7 and equally distributed over the ceiling area. To simplify the drawings only few upper burners 8 are shown. It will be understood, however, that in actuality they are evenly distributed as above described.
  • the upper burners discharge the gas downwardly against the upper surface of the slab.
  • a plurality of lower or floor burners 10 are installed in furnace floor and are evenly distributed over the floor as more fully described hereinafter.
  • the floor burners discharge a fuel jet in an upward direction against the underside of slab 6. To simplify the drawing again only a few of the floor burners are illustrated in detail.
  • the floor burners are arranged in parallel rows on banks 12 which extend perpendicular to the transport direction V and which are vertically aligned with slide rail support members 2. Adjacent banks 12 form between each other troughs 13 in which decending scale collects during operation of the furnace. Scale accumulated in the troughs can be removed from time to time through doors 14 arranged at the ends of the troughs.
  • Discharge nozzles 23 of the burners are thus elevated above the furnace floor defined by the bottom of troughs 13.
  • Floor burners 10 include vertically oriented, straight free burners tubes or ducts 15 which define the burner nozzles. The lower end of each tube is attached to a scale bag 17 closed by a door 16. Radially extending fuel gas conduits l8 and 19 connected to burner tube 15 adjacent the lower end thereof and are arranged to impart the above described radial or swirl component to the gas discharged by the burner nozzle.
  • the straight burner tubes 15 effect a fuel gas discharge from burner discharge nozzles 23 at high speed. If, for example, the gases in the lower region of the burner tube have a valocity of say 15 meters per second then the velocity of the gas discharged by the nozzle is substantially increased as a result of the gas combustion and the accompanying increase in the gas volume to as much as about seven times the initial gas speed at the burner tube bottom. This assures that the gas exit velocity is sufficiently high over the entire regulation range of the burner to blow all scale falling from the slabs away from the floor burners and thus prevent the clogging of the burners.
  • FIG. 1 shows the gas flow of two free jet burners which have a swirl component 22.
  • two free jet floor burners which discharge gas without such swirl component.
  • a back flow 20, 21 is formed between the burners which discharge gas without such swirl component.
  • a back flow 20, 21 is formed between the burners which allows scale to descend between adjacent burner nozzles and settle in trough 13.
  • the swirl component of the free jet also insures that falling scale is projected radially outward. A considerable part of the scale, therefore does not have to travel upward along the entire path of the free jet. For example, as high as about one-half the vertical distance between the burner nozzle and the plate the scale passes from the ranges of the upwardly directed discharged gas into the back flow 20, 21 from where it settles in trough 13.
  • an industrial furnace having a heating space disposed between a furnace ceiling and a furnace floor and means for conveying scale shedding objects to be heated such as steel slabs horizontally through the furnace at an elevation spaced from both the floor and the ceiling
  • the improvement comprising a plurality of spaced apart substantially vertically oriented floor burners, each burner having an upwardly facing fuel discharge nozzle for vertically directing fuel towards an underside of the object, and means for supplying each burner when operating in its turned-down mode with gas of sufficient pressure so that the gas discharge speed at the nozzle exceeds the free fall speed of scale descending from the object above the nozzles.
  • An industrial furnace for heating a debris shedding object moving through the furnace along a horizontal path comprising: means for movably supporting the object in a substantially horizontal position between a furnace floor and a furnace ceiling, means for directly heating an upper side of the object as it moves through the furnace, a plurality of floor burners evenly distributed beneath the trabel path of the object, each burner having an upwardly facing nozzle for the discharge of fuel jet towards an underside of the object, the nozzle defining an opening through which the jet escapes in an upward, substantially vertical direction, and means for the discharge of gas by the nozzles at a speed which is greater than the free-fall speed of debris dropping off an underside of the object when the floor burners are in their turned-down operating mode to thereby directly heat the underside and prevent debris from entering and clogging the nozzles and floor burners.
  • a furnace in accordance with claim 2 including means raising the discharge nozzle above the furnace bottom.
  • a furnace according to claim 2 including a plurality of floor burners arranged in parallel rows extending in the direction of movement of the object throughthe object support means includes support members extending perpendicularly to the object transport direction through the furnace, and wherein floor burner nozzles are vertically aligned with the support members.
  • each floor burner includes straight burner tube means, a scale collecting container secured to a lower end of the tube means, means for selectively opening the 9al99 2tr ma @n mans o intwqysins a gas flow into the burner tube in a generally radial direction.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Tunnel Furnaces (AREA)
  • Furnace Charging Or Discharging (AREA)
US00171675A 1970-08-17 1971-08-13 Industrial furnace Expired - Lifetime US3781166A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19702040766 DE2040766B2 (de) 1970-08-17 1970-08-17 Industrieofen

Publications (1)

Publication Number Publication Date
US3781166A true US3781166A (en) 1973-12-25

Family

ID=5779951

Family Applications (1)

Application Number Title Priority Date Filing Date
US00171675A Expired - Lifetime US3781166A (en) 1970-08-17 1971-08-13 Industrial furnace

Country Status (9)

Country Link
US (1) US3781166A (es)
JP (1) JPS5134366B1 (es)
AT (1) AT308271B (es)
BE (1) BE768476A (es)
DE (1) DE2040766B2 (es)
ES (1) ES198455Y (es)
FR (1) FR2101472A5 (es)
GB (1) GB1335753A (es)
LU (1) LU63725A1 (es)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3841614A (en) * 1971-12-06 1974-10-15 Kawasaki Heavy Ind Ltd Apparatus for preheating steel ingot or blooms by the use of high-speed jet streams as well as heating furnace using the same
US3985496A (en) * 1973-10-01 1976-10-12 Eickelberg Henry L Walking beam device for conveying materials at high temperature

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2637970C2 (de) * 1976-08-24 1982-04-08 OFU Ofenbau-Union GmbH, 4000 Düsseldorf Durchlaufofen, insbesondere Hubbalkenofen

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3841614A (en) * 1971-12-06 1974-10-15 Kawasaki Heavy Ind Ltd Apparatus for preheating steel ingot or blooms by the use of high-speed jet streams as well as heating furnace using the same
US3985496A (en) * 1973-10-01 1976-10-12 Eickelberg Henry L Walking beam device for conveying materials at high temperature

Also Published As

Publication number Publication date
DE2040766B2 (de) 1971-12-16
FR2101472A5 (es) 1972-03-31
GB1335753A (en) 1973-10-31
LU63725A1 (es) 1972-01-04
ES198455U (es) 1975-06-01
DE2040766A1 (es) 1971-12-16
ES198455Y (es) 1975-10-16
JPS5134366B1 (es) 1976-09-25
AT308271B (de) 1973-06-25
BE768476A (fr) 1971-11-03

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