US3672654A - Soaking pit furnace - Google Patents

Soaking pit furnace Download PDF

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Publication number
US3672654A
US3672654A US72772A US3672654DA US3672654A US 3672654 A US3672654 A US 3672654A US 72772 A US72772 A US 72772A US 3672654D A US3672654D A US 3672654DA US 3672654 A US3672654 A US 3672654A
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United States
Prior art keywords
heating means
enclosure
hot gases
combination
percent
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Expired - Lifetime
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US72772A
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English (en)
Inventor
Rudiger Knaak
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Koppers Wistra Ofenbau GmbH
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Koppers Wistra Ofenbau GmbH
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    • 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
    • C21D9/70—Furnaces for ingots, i.e. soaking pits

Definitions

  • ABSTRACT [30] Foreign Application Priority Data
  • a soaking pit furnace used for preparing metal ingots or blooms is provided with two sets of heating means, a principal Sept Germany 19 47 391? burner means and an auxiliary burner means mounted in the upper portion of one wall of the furnace.
  • the furnace also has [52] [1.5. CI. ..263/40 R, 263/52 an evacuating means in the lower portion of the same wall.
  • the auxiliary heating means can supply only a minor portion 58 Field of Search ..263/40, 43, 52 of the heat requirement. but is capable of injecting hot gases into the furnace enclosure at a velocity of at least 70 meters per second.
  • Blocks to be heated are generally placed vertically in the heating chamber. Temperature differences occur most frequently between the tops and bottoms of the pieces. Metallurgists refer to this temperature difference as being between the head and the foot of the ingot. Temperature differences also occur between opposite faces of the blocks where the face turned toward the source of heat is hotter than the opposite face. Bringing all parts of the ingot to a uniform temperature is rendered more difficult by the fact that the blocks may be introduced cold as well as hot.
  • the temperature of the blocks must be raised rapidly which requires that a large source of heat be used.
  • the rate of heat introduction into the chamber need only be about l percent of the full capacity of the source of heat. Since, usually, the blocks are hot when introduced into the heating chamber, the rate of heat input into the chamber need only be to percent of the full capacity of the heat source for the most part, and performance during equilibrating the blocks is crucial.
  • Applicant has found that the process of heating up ingots or blooms in a soaking pit furnace can be improved by placing several burners in the front wall of the furnace and controlling these in response to the demand.
  • the demand is low, only one or two of the burners are put into operation; as the demand increases, more burners are used to supply the heat.
  • This technique is distinguished by the fact that at low demands, the one or two burners used to supply the heat should be capable of supplying not more than 20 percent of the maximum output of all burners operating together.
  • the gas velocity at the orifices or nozzles of the one or two burners should be more than 70 meters per second at full load.
  • This type of arrangement is desirable because the workpieces are generally put into the furnace while hot and consequently the required burner load for the final phases of the heating process is apt to be 20 percent or less.
  • the auxiliary burner or burners have a function in addition to supplying up to 20 percent of the total heat requirement: this is to cause turbulence in the chamber gases, this turbulence being largely responsible for the excellent temperature equilibration achieved in the furnace, according to the invention.
  • the gas emerging from the auxiliary burner to burners at 70 m/sec. causes turbulence by entraining the atmosphere of the furnace. Gas velocities higher than m/sec. can be achieved by burning the gases of the auxiliary burner or burners in an auxiliary chamber and leading the combustion products into the furnace chamber.
  • FIG. 1 shows a horizontal section through the furnace chamber
  • FIG. 2 is a vertical section through the line I-I.
  • FIG. I shows a rectangular soaking pit furnace 1 having a front wall la, a principal burner 2 flanked by auxiliary burners 3 and a back wall 5.
  • the billets are designated by the reference numeral 4.
  • FIG. 2 is a vertical section along the line II.
  • This Figure shows the location of the evacuating means 6 through which the gas in the chamber vents.
  • the Figure also indicates the direction of flow of the gas as shown by the arrows.
  • gas enters the furnace through the burners travels for the most part across the tops of the workpieces to the back wall 5 where it is deflected downward, and then travels across the bottom of the furnace leaving through the vent 6.
  • the general course of the gaseous combustion product is as shown in FIG. 2, it will be realized that considerable mixing takes place as a result of the injection of combustion products from burners 3 at high velocity.
  • the streams from the burners be emitted with the highest possible velocity.
  • the velocity at each point in the stream is proportional to the orifice velocity and the orifice diameter.
  • the quantity of heating medium entering the chamber per unit of time, and thereby the quantity of heat introduced, is proportional to the product of the orifice velocity and the square of the orifice diameter. More exact investigation has shown that the stream velocity at any random point in the stream is proportional to the root of the orifice velocity for equal volumes issuing from the orifice that is, for equal input.
  • This principal burner should supply from 85 to 90 percent of the total load.
  • Two auxiliary burners are located at the same level as the principal burner and flank the principal burner on either side.
  • the auxiliary burners are so constructed that after the initial portion of the heating where the maximum heat input is required, and the heat requirements decrease, that the auxiliary burners can be throttled down. Initially the burners are run at a constant setting and after reaching some minimum level, they are operated on an otT-on mode. In this way, the opera tion of these burners at a rate lower than the minimum at which they can give satisfactory performance is avoided.
  • combination comprising wall means defining an enclosure having a portion for reception of a charge; at least one principal and a plurality of auxiliary heating means provided in the region of said wall means for discharging hot gases into said enclosure at a total maximum heating capacity of 100 percent, the combined maximum heating capacity of said plurality of auxiliary heating means being at most equal to 20 percent of the total heating capacity of all of said heating means, and each of said plurality of auxiliary heating means being arranged to discharge hot gases into said enclosure at a velocity of at least 70 meters per second when operated at its maximum heating capacity.
  • each of said heating means comprises at least one fuel hunter.
  • At least one of said auxiliary heating means comprises a high velocity burner having a combustion chamber provided with at least one orifice for discharge of hot combustion products into said enclosure at a velocity of at least 90 m/sec.
  • said principal heating means comprises at least one fuel burner whose heating capacity constitutes between and percent of the total capacity of said heating means.
  • auxiliary heating means comprises two fuel burners flanking said principal heating means.
  • Process of bringing metal workpieces to a required high temperature by means of hot gases comprising the steps of placing said workpieces in an enclosure; introducing into a first region in said enclosure hot gases in such quantity that such gases supply at least 80 percent of the required heat energy; and introducing into a plurality of additional regions of said enclosure hot gases at a velocity of at least 70 m/sec, whereby the gases introduced at said additional regions supply the remaining heat energy required.
  • Process as defined in claim 9, further comprising the steps of gradually reducing the rate of introduction of hot gases at at least one of said regions when the temperature within said enclosure rises to a predetermined value; and thereupon maintaining constant the rate ofintroduction of hot gases at said regions.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Tunnel Furnaces (AREA)
  • Combustion Of Fluid Fuel (AREA)
US72772A 1969-09-19 1970-09-16 Soaking pit furnace Expired - Lifetime US3672654A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19691947391 DE1947391A1 (de) 1969-09-19 1969-09-19 Tiefofen

Publications (1)

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US3672654A true US3672654A (en) 1972-06-27

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Application Number Title Priority Date Filing Date
US72772A Expired - Lifetime US3672654A (en) 1969-09-19 1970-09-16 Soaking pit furnace

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US (1) US3672654A (enrdf_load_stackoverflow)
DE (1) DE1947391A1 (enrdf_load_stackoverflow)
FR (1) FR2060572A5 (enrdf_load_stackoverflow)
GB (1) GB1264749A (enrdf_load_stackoverflow)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4120642A (en) * 1976-05-25 1978-10-17 Nippon Kokan Kabushiki Kaisha Method for heating ingot in soaking pit
US20130209948A1 (en) * 2010-05-04 2013-08-15 Rudiger Eichler Method for increasing the temperature homogeneity in a pit furnace
RU2521772C1 (ru) * 2013-05-21 2014-07-10 Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Тверской государственный технический университет" Рекуперативный нагревательный колодец

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2638334A (en) * 1948-01-29 1953-05-12 Jones John Frederick Robert Furnace for the heat treatment of materials
US2849221A (en) * 1955-04-06 1958-08-26 Surface Combustion Corp Heat treating furnace
US3198855A (en) * 1962-04-24 1965-08-03 Loftus Engineering Corp Method of operating soaking pits

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2638334A (en) * 1948-01-29 1953-05-12 Jones John Frederick Robert Furnace for the heat treatment of materials
US2849221A (en) * 1955-04-06 1958-08-26 Surface Combustion Corp Heat treating furnace
US3198855A (en) * 1962-04-24 1965-08-03 Loftus Engineering Corp Method of operating soaking pits

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4120642A (en) * 1976-05-25 1978-10-17 Nippon Kokan Kabushiki Kaisha Method for heating ingot in soaking pit
US20130209948A1 (en) * 2010-05-04 2013-08-15 Rudiger Eichler Method for increasing the temperature homogeneity in a pit furnace
RU2521772C1 (ru) * 2013-05-21 2014-07-10 Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Тверской государственный технический университет" Рекуперативный нагревательный колодец

Also Published As

Publication number Publication date
GB1264749A (enrdf_load_stackoverflow) 1972-02-23
DE1947391A1 (de) 1971-03-25
FR2060572A5 (enrdf_load_stackoverflow) 1971-06-18

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