EP3173495A1 - Verfahren und vorrichtung zur reaktionskontrolle - Google Patents

Verfahren und vorrichtung zur reaktionskontrolle Download PDF

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Publication number
EP3173495A1
EP3173495A1 EP15196189.3A EP15196189A EP3173495A1 EP 3173495 A1 EP3173495 A1 EP 3173495A1 EP 15196189 A EP15196189 A EP 15196189A EP 3173495 A1 EP3173495 A1 EP 3173495A1
Authority
EP
European Patent Office
Prior art keywords
section
sheet
furnace
oxidizing medium
flow
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.)
Withdrawn
Application number
EP15196189.3A
Other languages
English (en)
French (fr)
Inventor
Michel Dubois
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.)
John Cockerill SA
Original Assignee
Cockerill Maintenance and Ingenierie SA
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 Cockerill Maintenance and Ingenierie SA filed Critical Cockerill Maintenance and Ingenierie SA
Priority to EP15196189.3A priority Critical patent/EP3173495A1/de
Priority to PCT/EP2016/059123 priority patent/WO2016177590A1/en
Priority to CA2983069A priority patent/CA2983069C/en
Priority to JP2017554601A priority patent/JP6684825B2/ja
Priority to US15/571,504 priority patent/US11193196B2/en
Priority to EP16718352.4A priority patent/EP3292224B1/de
Priority to CN201680023760.1A priority patent/CN107532227B/zh
Priority to EA201792395A priority patent/EA032952B1/ru
Publication of EP3173495A1 publication Critical patent/EP3173495A1/de
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
    • C21D9/54—Furnaces for treating strips or wire
    • C21D9/56—Continuous furnaces for strip or wire
    • C21D9/561—Continuous furnaces for strip or wire with a controlled atmosphere or vacuum
    • 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
    • F27B9/04—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity adapted for treating the charge in vacuum or special atmosphere
    • F27B9/045—Furnaces with controlled atmosphere
    • 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
    • F27B9/145—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 along a serpentine path
    • 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
    • F27D7/00—Forming, maintaining, or circulating atmospheres in heating chambers
    • F27D7/06—Forming or maintaining special atmospheres or vacuum within heating chambers
    • 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
    • F27D9/00—Cooling of furnaces or of charges therein
    • F27D2009/0002—Cooling of furnaces
    • F27D2009/0005—Cooling of furnaces the cooling medium being a gas
    • F27D2009/0008—Ways to inject gases against surfaces

Definitions

  • the invention relates to a device and a method for controlling the surface reaction on steel sheets transported in a continuous galvanizing or annealing line.
  • High strength steel grades generally comprise high contents of elements like silicon, manganese and chromium (respectively typically between 0.5 and 2%, 1.5 and 6%, 0.3 and 1% in wt) making them difficult to coat because an oxide layer of those elements is formed during the annealing preceding the dipping in the galvanizing bath. This oxide layer harms the wetting ability of the steel surface when submerged in the bath. As a result, uncoated areas and a poor adhesion of the coating are obtained.
  • a well-known method to improve the wetting of these steel grades consists in fully oxidizing the steel surface in a specific chamberwhen the steel has a temperature typically between 600 and 750°C.
  • the resulting oxide layer comprises a high amount of iron oxides which are then reduced during the end of heating and holding section of the annealing furnace and the following thermal treatment.
  • the target is to obtain an oxide thickness between around 50 and 300nm, what corresponds to an iron oxide below 2gr/m 2 .
  • this oxidation can be performed in a direct fired furnace running the combustion with air excess.
  • Another way consists in making this oxidation in a dedicated chamber located in the middle of the annealing furnace and supplied with a mixture of nitrogen and an oxidant. Such implementation is described in the patent EP 2 010 690 B1 and in figure 1 .
  • the oxidation section is separated from the other parts of the annealing furnace by seals to minimize the introduction of the oxidant in the first and final sections.
  • the formation of the oxide layer must be carefully controlled to avoid the formation of too thick layers, too thin layers or non-uniform layers, all resulting in quality problems on the finished product.
  • a change in these parameters has a direct impact on the oxide formation and must be compensated.
  • a change in the line speed what is usual in a production line, results in a change of the residence time.
  • Changing the oxygen concentration in the chamber is the easiest way to compensate this variation.
  • the adjustment of the oxygen content in a fully fresh inert gas is quite easy by controlling the relative volume, it is much more complicated when the oxidizing medium not fully consumed is recirculated.
  • Dimensional parameters such as the frequent change in the strip width or a non-symmetric positioning of the strip in the chamber can also influence the oxide formation.
  • a different oxide layer formation between both sides of the strip can also be observed because, due to internal buoyancy flow or due to strip entrainment, the mass transport of the oxidant to the steel surface can be different.
  • the present invention aims to provide a solution to these problems of non-uniform oxide layer formation.
  • the present invention relates to a furnace for annealing a sheet comprising a first section, a second vertical section and a third section, said second section comprising openings supplied with an oxidizing medium, an opening facing each side of the sheet, wherein the second section comprises means for separately controlling the flow of the oxidizing medium through each opening.
  • the furnace according to the invention further comprises at least one or a suitable combination of the following features:
  • the present invention also relates to a method for controlling a surface reaction on a sheet running through the second section of the furnace as described above, comprising a step of separately controlling the flow of the oxidizing medium on each side of the sheet, the flow being adjusted by changing the rotation speed of the fan.
  • the method according to the invention further comprises at least one or a suitable combination of the following features:
  • the invention aims to provide a method with process parameters adjusted to control separately the oxide formation on each side of the steel sheet.
  • This method allows easily adjusting the concentration and flow of the oxidant medium according to the strip width, the line speed and the steel grade.
  • an annealing furnace comprising specific control means in the oxidation chamber has been developed.
  • the furnace 1 represented in figure 2 is dedicated to anneal steel sheets to be coated by a liquid metal comprising Zn, Al or a combination of those two in various proportions with an eventual addition of Mg and Si in proportion higher than 0.1%.
  • the furnace according to the invention can also be used in a continuous annealing line without hot-dip galvanizing facilities.
  • the furnace has different sections, each located in a distinct casing.
  • the first section 2 of the furnace 1 is a classical heating section comprising heating elements and rolls. It can be a resistance heating, an inductive heating or a radiant tube heater. This section is slightly oxidizing to limit the risk of external oxidation of the alloying elements and potentially to start forming a Fe oxide in some cases.
  • the H 2 content is below 2%
  • the O 2 level is below 0.1%
  • the H 2 O or CO 2 content or the sum H 2 O and CO 2 (H 2 O+CO 2 ) is superior to 0.03% and, preferably superior to 0.035%, but inferior to 10% to obtain this atmosphere slightly oxidizing.
  • the second section 3 is the oxidation chamber wherein an oxidizing mixture composed of an oxidant such as O 2 and an inert gas like N 2 is injected to form a controlled iron oxide layer on the surface of the steel sheet. This section will be further detailed below.
  • the third section 4 has a reducing atmosphere to reduce the iron oxide formed in the second section.
  • the classical practice is to use H 2 mixed with an inert gas, the concentration of H 2 being adjusted between 3 and 30% and preferably between 5 and 20%.
  • the second section 3 is a vertical section with sealing devices 11 like rolls or gates at the entry and exit of the section to separate this section from the first and third sections.
  • the oxidizing medium is injected on the sheet surface by openings, preferably forming slots, which ensure a uniform distribution of the flow all across the chamber.
  • the openings 10 are located on each side of the sheet 5 and preferably located transversally at one end of the oxidation chamber 3 as shown in figure 3 . More preferably and for reasons explained hereafter, they are located at the top of the oxidation chamber.
  • the chamber comprises extraction openings 12 to reduce the pressure inside the second section.
  • the second section 3 is provided with means for controlling separately the flow of the oxidizing medium on each side of the steel sheet.
  • it also comprises means for controlling separately the oxidant concentration and the temperature of the oxidizing medium for each side of the steel sheet.
  • the control system according to a first embodiment of the invention is described in figure 5 .
  • the flow, the oxidant concentration and its temperature are separately controlled for each side.
  • the injecting pipes 7 of the two sides are independent and the flow on each side is controlled by a fan 9 whose speed is adjusted depending on the desired flow.
  • the injected flow is extracted.
  • the gas extracted from the chamber is preferably recirculated.
  • a fresh oxidant is injected with a concentration based on the measurement of the residual oxidant in the extracted flow and the flow is fixed by the fan rotation speed.
  • the amount of added air is calculated on the basis of a mass balance as follows:
  • the control system is simplified with only a single fan 9 and heater for both sides.
  • the injection pipe 7 of one side is mounted on the injection pipe 7 of the other side.
  • the flow for each side is controlled by means of a valve 8 installed on the injection pipe 7 of each side or by means of a single valve 8 installed on one of the injection pipes 7 as shown in figure 6 .
  • the flow may be measured by dedicated devices.
  • the latter configuration with a single valve is preferred. Indeed, the total flow being known by the rotation speed of the fan, the valve can be used to balance each side separately.
  • the second section can also be provided with additional means to control specifically the oxidation on the edges of the sheet as disclosed in the application EP 151 831 69 .
  • the temperature of the oxidizing mixture e.g. N 2 +O 2
  • the temperature of the oxidizing mixture is between 50°C and 200°C below the sheet temperature to take benefit of the buoyancy principle whereby the gas colder than the strip moves down.
  • the transversal openings are located at the top of the chamber and, preferably, the strip moves down.
  • the gas could be warmer than the strip and the openings located at the bottom of the chamber.
  • the temperature for each side is controlled separately as shown in figure 5 .
  • the chamber can also be provided with heating elements to compensate for the heat losses.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Strip Materials And Filament Materials (AREA)
EP15196189.3A 2015-05-07 2015-11-25 Verfahren und vorrichtung zur reaktionskontrolle Withdrawn EP3173495A1 (de)

Priority Applications (8)

Application Number Priority Date Filing Date Title
EP15196189.3A EP3173495A1 (de) 2015-11-25 2015-11-25 Verfahren und vorrichtung zur reaktionskontrolle
PCT/EP2016/059123 WO2016177590A1 (en) 2015-05-07 2016-04-25 Method and device for reaction control
CA2983069A CA2983069C (en) 2015-05-07 2016-04-25 Method and device for reaction control
JP2017554601A JP6684825B2 (ja) 2015-05-07 2016-04-25 反応制御のための方法及び装置
US15/571,504 US11193196B2 (en) 2015-05-07 2016-04-25 Method and device for reaction control
EP16718352.4A EP3292224B1 (de) 2015-05-07 2016-04-25 Verfahren und vorrichtung zur reaktionskontrolle
CN201680023760.1A CN107532227B (zh) 2015-05-07 2016-04-25 反应控制的方法和装置
EA201792395A EA032952B1 (ru) 2015-05-07 2016-04-25 Способ и устройство для управления реакцией

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP15196189.3A EP3173495A1 (de) 2015-11-25 2015-11-25 Verfahren und vorrichtung zur reaktionskontrolle

Publications (1)

Publication Number Publication Date
EP3173495A1 true EP3173495A1 (de) 2017-05-31

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP15196189.3A Withdrawn EP3173495A1 (de) 2015-05-07 2015-11-25 Verfahren und vorrichtung zur reaktionskontrolle

Country Status (1)

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EP (1) EP3173495A1 (de)

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2010690B1 (de) 2006-04-26 2010-02-24 ThyssenKrupp Steel Europe AG Verfahren zum schmelztauchbeschichten eines stahlflachproduktes aus höherfestem stahl
US20100173072A1 (en) * 2007-09-03 2010-07-08 Siemens Vai Metals Technologies Sas Method and device for controlling oxidizing-reducing of the surface of a steel strip running continuously through a radiant tubes furnace for its galvanizing
US20100269367A1 (en) * 2007-12-28 2010-10-28 Langevin Stephane device for blowing gas onto a face of a traveling strip of material
US20110018178A1 (en) * 2008-03-14 2011-01-27 Arcelormittal France Method and device for blowing gas on a running strip
CN201908124U (zh) * 2010-12-17 2011-07-27 鞍钢新轧-蒂森克虏伯镀锌钢板有限公司 镀锌线预氧化装置
EP2458022A1 (de) * 2010-11-30 2012-05-30 Tata Steel UK Limited Verfahren zum Verzinken eines Stahlstreifens in einer kontinuierlichen Feuerverzinkungsanlage
US20140203482A1 (en) * 2011-05-10 2014-07-24 Thyssenkrupp Steel Europe Ag Apparatus and Method for the Treatment of a Flat Steel Product, Taking Place in Throughput

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2010690B1 (de) 2006-04-26 2010-02-24 ThyssenKrupp Steel Europe AG Verfahren zum schmelztauchbeschichten eines stahlflachproduktes aus höherfestem stahl
US20100173072A1 (en) * 2007-09-03 2010-07-08 Siemens Vai Metals Technologies Sas Method and device for controlling oxidizing-reducing of the surface of a steel strip running continuously through a radiant tubes furnace for its galvanizing
US20100269367A1 (en) * 2007-12-28 2010-10-28 Langevin Stephane device for blowing gas onto a face of a traveling strip of material
US20110018178A1 (en) * 2008-03-14 2011-01-27 Arcelormittal France Method and device for blowing gas on a running strip
EP2458022A1 (de) * 2010-11-30 2012-05-30 Tata Steel UK Limited Verfahren zum Verzinken eines Stahlstreifens in einer kontinuierlichen Feuerverzinkungsanlage
CN201908124U (zh) * 2010-12-17 2011-07-27 鞍钢新轧-蒂森克虏伯镀锌钢板有限公司 镀锌线预氧化装置
US20140203482A1 (en) * 2011-05-10 2014-07-24 Thyssenkrupp Steel Europe Ag Apparatus and Method for the Treatment of a Flat Steel Product, Taking Place in Throughput

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