US3627857A - Heating controlling system in a multizone type continuously heating furnace - Google Patents

Heating controlling system in a multizone type continuously heating furnace Download PDF

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Publication number
US3627857A
US3627857A US798729A US3627857DA US3627857A US 3627857 A US3627857 A US 3627857A US 798729 A US798729 A US 798729A US 3627857D A US3627857D A US 3627857DA US 3627857 A US3627857 A US 3627857A
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United States
Prior art keywords
zone
temperature
heating
heated object
heated
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Expired - Lifetime
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US798729A
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English (en)
Inventor
Hiroshi Matuno
Toshiya Morisue
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Yawata Iron and Steel Co Ltd
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Yawata Iron and Steel Co Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • 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
    • F27B9/40—Arrangements of controlling or monitoring devices
    • 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
    • C21D11/00—Process control or regulation for heat treatments
    • 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
    • F27D19/00—Arrangements of controlling devices
    • F27D2019/0003—Monitoring the temperature or a characteristic of the charge and using it as a controlling value
    • 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
    • F27D19/00—Arrangements of controlling devices
    • F27D2019/0006—Monitoring the characteristics (composition, quantities, temperature, pressure) of at least one of the gases of the kiln atmosphere and using it as a controlling value
    • F27D2019/0018—Monitoring the temperature of the atmosphere of the kiln
    • 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
    • F27D19/00—Arrangements of controlling devices
    • F27D2019/0028—Regulation
    • F27D2019/0034—Regulation through control of a heating quantity such as fuel, oxidant or intensity of current
    • 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
    • F27D19/00—Arrangements of controlling devices
    • F27D2019/0028—Regulation
    • F27D2019/0059—Regulation involving the control of the conveyor movement, e.g. speed or sequences
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27M—INDEXING SCHEME RELATING TO ASPECTS OF THE CHARGES OR FURNACES, KILNS, OVENS OR RETORTS
    • F27M2003/00—Type of treatment of the charge
    • F27M2003/02—Preheating, e.g. in a laminating line

Definitions

  • FIG. III FIG. 2
  • the temperature of the heated object in a three-zone-type continuously heating furnace it is to note in general that, as the temperature of the heated object in the preheating zone is represented only as a function of the time required for the passage of the heated object and the residual temperature and the amount of the exhaust gas discharged out of the heating zone, that is, the quantity of the sensible heat of the exhaust gas, it is generally almost impossible to control the heating of the heated material and further, as the heated object does not come to be red hot, it is difficult to measure the temperature of the heated object even at the end of the preheating zone.
  • the present invention has for its object the control of combustion in each zone as in an independent state by determining the inlet temperature of the heated object in each zone, taking also the moving velocity, physical constant and dimension of the heated materials into consideration so that any desired rolling temperature of the heated object may be finally obtained.
  • Another object of the present invention is to carry out an economical operation by reducing personnel and saving fuel consumption by efficiently and automatically operating a continuously heating furnace so that the heated object may be extracted out of the heating furnace at any desired temperature. That is, the present invention is to provide a heating controlling system in a multizone-type continuously heating furnace, in which furnace a preheating zone, heating zone and soaking zone being formed in sequence, characterized by determining by calculation the temperature of a heated object at the inlet of the heating zone according to a relative formula of a predetermined temperature of the heated object from the controlled or uncontrolled atmospheric temperature in the preheating zone and the dimension, moving velocity and physical constant of the heated object, controlling the quantity of fed heat in the heating zone from the said determined temperature, the dimension, moving velocity and physical constant of the heated object and a predetermined rolling temperature and further adjusting the quantity of the fed heat or the moving velocity of the heated zone in the soaking zone from the difference between the above-mentioned predetermined rolling temperature and soaking zone inlet temperature and the dimension and physical constant of the heated zone.
  • FIG. 3 is a graph comparing the set values according to the 7 present invention and set values in actual operation.
  • FIGS. 4(a) and (b) show fuel (heavy oil) flow volumes (amounts of feed) in a continuously heating furnace controlled by the system of the present invention and in a continuously heating furnace not using the system of the present invention, in which (a) shows the former and (b) the latter.
  • FIG. 5 is a graph showing the measured temperatures of the heated object (slab) at the soaking zone outlet in the case of the control by the system of the present invention.
  • FIG. 6 shows a simplified model of a continuously heating furnace.
  • FIG. 7 shows a heat balance model of a heated object in any heating zone according to FIG. 6.
  • FIG. 1 in which is a schematic view of a three-zone-type continuously heating furnace, l is a preheating zone, 2 and 3 are respectively an upper heating zone and lower heating zone, 4 is a soaking zone and 5 is a part of objects to be heated. Further, in FIG. 2, 6 is an outlet of the heating zone and 8 is an inlet of the same. 7 is an inlet of the soaking zone and 13 is an outlet of the same. 9 is a heating zone fuel inflow volume. 10 is a combustion air volume. 11 is a heating furnace set temperature. 12 is a thermometer.
  • the temperature of the heated object at the end of the preheating zone 1 can be represented by the following formula as a function of the quantity of sensible heat of the exhaust gas from the heating zone and the time of the passage of the heated object through the preheating zone:
  • time is a mean temperature of the heated object at the outlet of the preheating zone
  • V is a moving velocity of the heated object
  • D is a dimension of the heated object and C is a specific heat of the exhaust gas.
  • the temperature at the end of the preheating zone that is, at the inlet of the heating zone can be determined 10 by calculation by the above-mentioned formula from the physical constant and dimension of the heated object given in advance by detecting the atmospheric temperature in the preheating zone and the moving velocity of the heated object.
  • One of the features of the present invention is to determine the temperature at the preheating zone outlet of the heated object.
  • the thus determined average temperature at the preheating zone outlet of the heated object is then used for the base of the heating control of the heating zone.
  • the heating of the object is mostly carried out in the upper heating part and lower heating part with the heated object path in the heating zone as a boundary between both parts.
  • the control of the heating zone and soaking zone shall be described with reference to FIG. 2 in the following.
  • the control of the heating in the heating zone 2 is mostly carried out with the heating temperature, independently of the control of the soaking zone 4 following the heating zone 2.
  • the temperature of the heated object at the outlet of the heating zone 2, h that is, at the inlet 7 of the soaking zone is so set as to coincide with the temperature required for the hot-working in the subsequent step.
  • the temperature of the heated object 5 in the heating zone 2 is controlled by controlling the heating temperature as mentioned above.
  • the temperature 0 mo of the heated object at the above-mentioned heating zone outlet 6 is represented by the following formula as a function of the heatingzone heating temperature 0 heated object moving velocity V heated object temperature 67ml at the heating zone inlet 8, heated object dimension D and physical constant P of the heated object:
  • the actual temperature m0 of the object thus heated in the heating zone and the temperature m! of the soaking zone inlet 7 should be ideally equal to each other.
  • the temperature of the heated object leaving the heating zone is measured with the thermometer 12 in anticipation of the case that, due to any external disturbance, the actual temperature Hmo of the heated object 5 might not reach the predetermined temperature at the soaking zone inlet.
  • control of the heating or soaking in the soaking zone 4 is carried out by utilizing the following relative formula in the same manner as in the heat control in the heating zone:
  • 5m is an objective temperature for extracting the heated object
  • 0 is a heating temperature in the soaking zone
  • Omi' is a temperature of the heated object at the soaking zone inlet
  • P is a physical constant of the heated object and D is a dimension of the heated object.
  • the objective temperature of the heated object is controlled by adjusting the soaking zone heating or soaking temperature,'asis determined by The above-mentioned is of the case of a three-zone type which has no burner in the preheating zone and therefore in which the heated object cannot be controlled in the preheating zone.
  • the independent furnace set heating temperature or moving velocity for the heated object to pass through the outlet at the objective temperature can be determined by regarding the preheating zone, heating zone and soaking zone respectively as independent furnaces and measuring or calculating the temperature of the heated object at the inlet of the independent furnace or from the above-mentioned formula model if the objective temperature at the outlet is determined. Therefore, a temperature adapted to roll the heated object can be obtained automatically and accurately by carrying out the same operation for each independent furnace.
  • FIG. 6 there is shown a usual continuously heating furnace, the interior of which is divided into five parts, that is, the first, second, third, fourth and fifth heating zones, seen from the inlet for charge at the left end, each of which being regarded as an independent furnace and being divided into an upper part and a lower part respectively.
  • the fifth heating zone may be regarded as a soaking zone, and the temperature in each upper part and lower part of the respective zones can be controlled separately.
  • GB GI ()t' is the temperature ratio between the upper part and lower part of the i-heating zone).
  • Q ⁇ , Q can be obtained by substituting the formula (9) and integrating the substituted over a range of 0 to L
  • an average temperature of a heated object is calculated according to the formula (9)
  • temperatures set in the furnace or quantity of fed heat by utilizing the formulas l0) and l 1
  • the maximum set temperature which is realizable in the upper part of the heating zone is made t the maximum treated amount of a heated object M corresponding to said maximum set temperature can be obtained by modifying the formula 10).
  • F IG. 3 shows the case of the operating a continuously heating furnace by the system of the present invention.
  • shown with the solid line are planned values by the system of the present invention and shown with the dotted line are corrected values (actual operation values) based on the differences between said planned values and actual values. As evident from this graph, a very accurate control can be made.
  • FIG. 4 comparatively shows the amounts of fuel (heavy oil) fed to the upper heating zones in a continuously heating furnace controlled by the system of the present invention and in a continuously heating furnace not using the system of the present invention.
  • a far more precise control can be made and the fuel consumption can be made efficient.
  • FIG. 5 shows the results of measuring the temperature of the heated object (slab) at the soaking zone outlet in the case that the system of the present invention was worked. It is found that said temperature varied depending on the thickness of the heated object but was substantially constant for the same thickness and that therefore the control was made properly and accurately.
  • a continuously heating furnace can be operated automatically under optimum condition so that the heated object may be extracted at a fixed temperature, therefore the operation can be carried out efficiently and its effect is very high.
  • a process for controlling the direct heating of a steel material in a multizone type continuously heating furnace comprising the steps of measuring the atmospheric temperature in said preheating zone, determining the temperature of said heated steel material at an inlet of said heating zone from said measured value of said atmospheric temperature in said preheating zone and the dimension, moving velocity and physical constant of said heated steel material, controlling the fuel inflow volume and combustion air volume in said heating zone from said temperature, simultaneously adjusting the quantity of heat fed to or the moving velocity of said heated steel material in said soaking zone from the difference between a predetermined rolling temperature and the measured value of the temperature of said heated steel material at the inlet of said soaking zone and the dimension and physical constant of said heated steel.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Thermal Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Heat Treatment Processes (AREA)
  • Tunnel Furnaces (AREA)
  • Heat Treatments In General, Especially Conveying And Cooling (AREA)
US798729A 1968-02-15 1969-02-12 Heating controlling system in a multizone type continuously heating furnace Expired - Lifetime US3627857A (en)

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Application Number Priority Date Filing Date Title
JP954068 1968-02-15

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US3627857A true US3627857A (en) 1971-12-14

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US (1) US3627857A (de)
BE (1) BE728391A (de)
DE (1) DE1907551B2 (de)
FR (1) FR2001974A1 (de)
GB (1) GB1256561A (de)
NL (1) NL6902415A (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4357135A (en) * 1981-06-05 1982-11-02 North American Mfg. Company Method and system for controlling multi-zone reheating furnaces
US5164015A (en) * 1986-12-01 1992-11-17 Siemens Aktiengesellschaft Method for cleaning a vessel

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3604695A (en) * 1969-12-15 1971-09-14 Gen Electric Method and apparatus for controlling a slab reheat furnace
DE2600626B2 (de) * 1976-01-09 1978-06-01 Aeg-Elotherm Gmbh, 5630 Remscheid Verfahren zur Erwärmung mindestens zweier Metallröhren endlicher Länge insbesondere aus Stahl zum Zweck ihrer Wärmebehandlung
JPS572843A (en) * 1980-06-04 1982-01-08 Mitsubishi Electric Corp Control method for heating in continuous type heating furnace
DE3332989A1 (de) * 1983-09-09 1985-03-28 Mannesmann AG, 4000 Düsseldorf Durchlaufofensteuerung
IT1187220B (it) * 1985-11-29 1987-12-16 Mauro Poppi Procedimento e forno per la cottura rapida di materiali ceramici quali piastrelle e simili
NL8702689A (nl) * 1987-11-11 1989-06-01 Hoogovens Groep Bv Werkwijze voor het op walstemperatuur brengen van een aantal staalplakken en besturingsinrichting geschikt voor het uitvoeren van de werkwijze.

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2620174A (en) * 1948-04-30 1952-12-02 Allegheny Ludlum Steel Billet heating furnace
US3252693A (en) * 1963-05-07 1966-05-24 Jones & Laughlin Steel Corp Control system for continuous annealing lines and the like

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB700390A (en) * 1951-07-19 1953-12-02 Internat Construction Company Improvements in or relating to furnaces for heating steel billets preparatory to rolling
US3022056A (en) * 1957-11-29 1962-02-20 Midland Ross Corp Combustion controls for metallurgical heating furnaces
FR1498393A (fr) * 1966-06-22 1967-10-20 Heurtey Sa Procédé et dispositif pour la régulation automatique de fours

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2620174A (en) * 1948-04-30 1952-12-02 Allegheny Ludlum Steel Billet heating furnace
US3252693A (en) * 1963-05-07 1966-05-24 Jones & Laughlin Steel Corp Control system for continuous annealing lines and the like

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4357135A (en) * 1981-06-05 1982-11-02 North American Mfg. Company Method and system for controlling multi-zone reheating furnaces
US5164015A (en) * 1986-12-01 1992-11-17 Siemens Aktiengesellschaft Method for cleaning a vessel

Also Published As

Publication number Publication date
FR2001974A1 (de) 1969-10-03
GB1256561A (de) 1971-12-08
BE728391A (de) 1969-07-16
DE1907551A1 (de) 1970-11-26
NL6902415A (de) 1969-08-19
DE1907551B2 (de) 1974-11-14

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