EP1872884A1 - Methode zur Verbesserung der Effizienz einer Stranggiessvorrichtung für gegossene Bramme aus Metall und Giessmaschine - Google Patents

Methode zur Verbesserung der Effizienz einer Stranggiessvorrichtung für gegossene Bramme aus Metall und Giessmaschine Download PDF

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Publication number
EP1872884A1
EP1872884A1 EP06013581A EP06013581A EP1872884A1 EP 1872884 A1 EP1872884 A1 EP 1872884A1 EP 06013581 A EP06013581 A EP 06013581A EP 06013581 A EP06013581 A EP 06013581A EP 1872884 A1 EP1872884 A1 EP 1872884A1
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EP
European Patent Office
Prior art keywords
casting
cooling
cooling chamber
air
slab
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.)
Ceased
Application number
EP06013581A
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English (en)
French (fr)
Inventor
Kees Verwij
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.)
Tata Steel Ijmuiden BV
Original Assignee
Corus Staal BV
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 Corus Staal BV filed Critical Corus Staal BV
Priority to EP06013581A priority Critical patent/EP1872884A1/de
Publication of EP1872884A1 publication Critical patent/EP1872884A1/de
Ceased legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/12—Accessories for subsequent treating or working cast stock in situ
    • B22D11/124—Accessories for subsequent treating or working cast stock in situ for cooling
    • B22D11/1246—Nozzles; Spray heads

Definitions

  • the present invention relates to a continuous casting process, as well as a device for continuously casting steel slabs.
  • Continuous casting of steel slabs is a well known process in the art.
  • molten metal is poured in a casting mold having an outlet opening in its bottom.
  • the molten metal is caused to adhere to a dummy bar initially filling the outlet opening.
  • This dummy bar is withdrawn at a constant speed in order to form a continuously growing slab having a solidified skin or shell.
  • This skin holds the still liquid core.
  • Below the mold the slab is guided over a conveyor system and cooled in a cooling chamber - also known as a secondary cooling box - adjacent the mold. This allows control of the surface temperature of the casted product.
  • the conveying system comprises guide rolls and driven rolls for withdrawal of the casted product.
  • Cooling of the casted slab is mainly achieved by applying cooling water from water nozzles or nozzles for a mix of water and atomizing air, onto the casted product. See e.g. " The book of steel”, Eds. Béranger and Henry, 1996, p. 1194-1195 and " The Making, Shaping and Treating of Steel", Eds. Lankford et al., 1984, 10th ed., p. 746 . Furthermore the casting device components contacting the slab like the guide and driven rolls are cooled themselves internally using a closed circuit thereby also contributing to some extent to the cooling of the slab.
  • the dummy bar is removed, and the continuously growing slab is cut into sections having a predetermined length. These sections can be individually processed, e.g. in a hot rolling mill.
  • the casting speed is set to a specified value depending on the device specifications, steel composition, required steel quality specifications and the like. Typical casting speeds are in the order of magnitude of metres per minute, ranging e.g. from less than one to several metres per minute. However, some product specifications allow to increase the casting speed. If the casting speed is increased, the cooling regime has to be adjusted. In the art cooling is increased by increasing the volume of water sprayed per unit of slab area and unit of time. However, the cooling rate offered by the water sprays may become insufficient for certain allowable casting speeds. This is usually recognized by an increase of the temperature of the water in the closed circuit cooling of the casting device components contacting the slab. Such a temperature increase is detrimental as it may cause damage to these components or parts thereof like bearings. In such a situation the casting speed needs to be reduced to a value, where no overheating of the components occurs. This is an economic disadvantage in view of operation of the casting device. Thus cooling may be a limiting factor in view of production rate increase.
  • An object of the invention is to provide a method of operating a casting device, which offers an increased flexibility towards operation, in particular with respect to casting speed.
  • Another object of the invention is to improve the performance of a casting device.
  • a further object of the invention is to provide a casting device wherein the disadvantages mentioned above do not occur or to a lesser extent.
  • Still another object of the invention is to improve the safe operation of a casting device.
  • a method of operating a continuous casting device for casting slabs wherein the casting device comprises a cooling chamber for cooling a casted slab, which method comprises the steps of
  • a casting device is operated by setting a predetermined casting speed together with adjustment of the cooling regime to this speed.
  • the cooling capacity of the cooling chamber is tuned to the set casting speed of the steel slabs by controlling the quantity of air withdrawn from the cooling chamber.
  • a part of this required heat transfer is brought about by the closed circuit cooling.
  • this kind of heat transfer is difficult to adjust to the required cooling and therefore not useful as a control means.
  • the potential range of adjustment is narrow and the effect on operation is restricted.
  • heat transfer may become difficult as well.
  • heat transfer has two components, that is to say heat required for heating up the sprayed water and evaporation. Evaporation is far more effective because it requires more enthalpy than only heating up.
  • cooling is controlled by adjusting the quantity of air laden with water vapour that is removed from the cooling chamber.
  • cooling is performed in a cooling chamber wherein the pressure is kept slightly below the ambient pressure. This prevents that escaping vapour could hamper operations on the casting platform.
  • Air in the cooling chamber is replenished by ambient air leaking into the cooling chamber. Evaporation at temperatures lower than 100°C is only possible as long as the absolute pressure is not higher than the partial vapour pressure. In other words, evaporation may occur if the water temperature is higher than the saturation temperature at the existing partial vapour pressure. However, if the partial vapour pressure increases, the saturation temperature increases, requiring a higher water temperature otherwise no evaporation can take place.
  • the method according to the invention allows to further increase cooling by removing more air containing water vapour, thereby keeping the partial vapour pressure at a relatively low level and consequently the saturation temperature also at a low level. Similarly, cooling can be suppressed by decreasing the flow of exhaust air from the cooling chamber.
  • the invention provides an effective way of operating a cooling chamber of a casting device in view of a desirable casting speed and its associated cooling rate of the steel slab.
  • the implementation of the present method requires an addition of a control means for the fan typically present in the exhaust of the cooling chamber.
  • this fan was set once at a predetermined value upon installation. Due to its height position in the exhaust usually the fan is not accessible for manual control and/or adjustment. Direct control of the rotational speed of the fan is an option.
  • the existing fan might be exchanged for a controlled fan having a larger capacity.
  • Another embodiment comprises a fixed speed fan with a flow controller such as a controllable (throttle) valve.
  • the method according to the invention also involves controlling the amount of water sprayed onto the casted slab.
  • This embodiment is advantageous as it provides double means for controlling cooling, i.e. by the amount of air laden with vapour removed from the cooling chamber as well as by the amount of water introduced into the chamber. The largest flexibility and/or accuracy of operating a casting device is achieved when both amounts are controlled simultaneously.
  • a useful embodiment comprises the situation, where in step a) the casting rate is reduced and in step b) the quantity of air discharged is reduced. This embodiment ensures the safe and continuous operation of a casting device, even if the casting speed has to be reduced substantially.
  • step a) comprises an increase of the casting rate
  • step b) comprises an increase of the quantity of air discharged.
  • the amount of water sprayed onto the casted slab is controlled as well.
  • the invention also relates to a casting device for continuous casting slabs, comprising a casting mold, a cooling chamber for solidifying a casting slab comprising a conveying means for conveying a casted slab through the cooling chamber, the cooling chamber being provided with a cooling water supply system for applying cooling water to the slab, and an air outlet for discharging air laden with water vapour from the cooling chamber, wherein the casting device comprises control means for controlling the quantity of air discharged.
  • control means allow for an active intervention in the amount of air that is removed from the cooling chamber.
  • the casting device according to the invention offers advantages similar to the beneficial effects described above with respect to the method of the invention.
  • Advantageously the conveying means are provided with cooling means as well.
  • a flow controller such as a (throttle) valve is provided in the exhaust the flow controller being controllable by the control means.
  • means for forcibly withdrawing air such as a fan may operate at a constant speed. It will be understood that such a valve can be dispensed with when the speed of the fan is directly adjustable.
  • the invention is illustrated in more detail in view of the attached drawing, wherein the sole figure is a schematic representation of an embodiment of a casting device according to the invention.
  • the casting device is generally indicated by reference numeral 10, comprising inter alia a casting mold 12 and a cooling chamber 14 (represented by a dashed line) below the casting mold 12.
  • a conveyor system is provided for withdrawal and guidance of a solidifying slab from the mold 12.
  • this conveyor system is exemplified by driven rolls 18. Downstream of the cooling chamber 14 the solidified slab is cut into suitably sized semi products.
  • the cooling chamber 14 is also provided with an exhaust 20 for removing air.
  • the casting mold 12 and separate driven rolls 18 each have an internally closed cooling circuit 22.
  • Each circuit 22 is connected to a heat exchanger 24 where water supplied by conduit 26 to lines 26a and to be fed by a pump 28 via conduit 30 to spray nozzle 32 is in heat exchanging contact with the return conduit 34 of circuit 22.
  • Water is supplied from a tank 36.
  • Spray nozzle 32 may also be provided with atomizing air.
  • a drain 38 provided at the bottom of cooling chamber 14 returns excess water back to tank 36 (e.g. from a cooling tower), to which also make up water can be added through conduit 40.
  • the amount of air laden with water vapour removed from the cooling chamber 14 and discharged to the atmosphere via stack 20 is controlled.
  • a fan 42 operating at a fixed speed withdraws the air from the cooling chamber.
  • a throttle valve 44 is mounted in a conduit 46 connecting the cooling chamber 14 to the stack 20. This throttle valve 44 is actuated by controller 48, which also controls the pump 28.
  • the spray nozzle 32 may also be directly fed with "cold" water, e.g. via a separate supply line 50, e.g. from tank 36 or other source. In that situation, the water heat exchanged in heat exchangers 24 is usually not used by the nozzle 32, but instead thereof returned to tank 36 (e.g. a cooling tower).
  • tank 36 e.g. a cooling tower

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Continuous Casting (AREA)
EP06013581A 2006-06-30 2006-06-30 Methode zur Verbesserung der Effizienz einer Stranggiessvorrichtung für gegossene Bramme aus Metall und Giessmaschine Ceased EP1872884A1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP06013581A EP1872884A1 (de) 2006-06-30 2006-06-30 Methode zur Verbesserung der Effizienz einer Stranggiessvorrichtung für gegossene Bramme aus Metall und Giessmaschine

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP06013581A EP1872884A1 (de) 2006-06-30 2006-06-30 Methode zur Verbesserung der Effizienz einer Stranggiessvorrichtung für gegossene Bramme aus Metall und Giessmaschine

Publications (1)

Publication Number Publication Date
EP1872884A1 true EP1872884A1 (de) 2008-01-02

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EP06013581A Ceased EP1872884A1 (de) 2006-06-30 2006-06-30 Methode zur Verbesserung der Effizienz einer Stranggiessvorrichtung für gegossene Bramme aus Metall und Giessmaschine

Country Status (1)

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EP (1) EP1872884A1 (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102049481A (zh) * 2010-09-20 2011-05-11 高毅夫 基于二冷配水量的连铸机蒸汽排出风机节能优化控制方法
CN112719250A (zh) * 2020-12-18 2021-04-30 四川福蓉科技股份公司 一种恒温恒压的冷却循环系统及其控制方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3759312A (en) * 1971-06-24 1973-09-18 Jones & Laughlin Steel Corp Process for cooling vacuum cast ingots
DE2512097A1 (de) * 1975-03-19 1976-09-30 Evertz Egon Verfahren zum stranggiessen von metallen und vorrichtung zur durchfuehrung dieses verfahrens
EP0650790A1 (de) * 1993-10-29 1995-05-03 DANIELI & C. OFFICINE MECCANICHE S.p.A. Verfahren und Vorrichtung zur thermischen Oberflächenbehandlung eines Stranges

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3759312A (en) * 1971-06-24 1973-09-18 Jones & Laughlin Steel Corp Process for cooling vacuum cast ingots
DE2512097A1 (de) * 1975-03-19 1976-09-30 Evertz Egon Verfahren zum stranggiessen von metallen und vorrichtung zur durchfuehrung dieses verfahrens
EP0650790A1 (de) * 1993-10-29 1995-05-03 DANIELI & C. OFFICINE MECCANICHE S.p.A. Verfahren und Vorrichtung zur thermischen Oberflächenbehandlung eines Stranges

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102049481A (zh) * 2010-09-20 2011-05-11 高毅夫 基于二冷配水量的连铸机蒸汽排出风机节能优化控制方法
CN112719250A (zh) * 2020-12-18 2021-04-30 四川福蓉科技股份公司 一种恒温恒压的冷却循环系统及其控制方法
CN112719250B (zh) * 2020-12-18 2022-04-01 四川福蓉科技股份公司 一种恒温恒压的冷却循环系统及其控制方法

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