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EP4627121A1 - Procédé de préchauffage de matériau de charge métallique et appareil de préchauffage de matériau de charge métallique - Google Patents

Procédé de préchauffage de matériau de charge métallique et appareil de préchauffage de matériau de charge métallique

Info

Publication number
EP4627121A1
EP4627121A1 EP23817385.0A EP23817385A EP4627121A1 EP 4627121 A1 EP4627121 A1 EP 4627121A1 EP 23817385 A EP23817385 A EP 23817385A EP 4627121 A1 EP4627121 A1 EP 4627121A1
Authority
EP
European Patent Office
Prior art keywords
charge material
heating device
metallic charge
hot
bofg
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.)
Pending
Application number
EP23817385.0A
Other languages
German (de)
English (en)
Inventor
Saikat Chatterjee
Frank Nicolaas Hermanus SCHRAMA
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 Nederland Technology BV
Original Assignee
Tata Steel Nederland Technology 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 Tata Steel Nederland Technology BV filed Critical Tata Steel Nederland Technology BV
Publication of EP4627121A1 publication Critical patent/EP4627121A1/fr
Pending legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/56—Manufacture of steel by other methods
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/56—Manufacture of steel by other methods
    • C21C5/562—Manufacture of steel by other methods starting from scrap
    • C21C5/565—Preheating of scrap
    • 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
    • F27B3/00—Hearth-type furnaces, e.g. of reverberatory type; Electric arc furnaces ; Tank furnaces
    • F27B3/10—Details, accessories or equipment, e.g. dust-collectors, specially adapted for hearth-type furnaces
    • F27B3/18—Arrangements of devices for charging
    • 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
    • F27D13/00—Apparatus for preheating charges; Arrangements for preheating charges
    • F27D13/002—Preheating scrap
    • 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
    • F27D17/00—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases
    • F27D17/10—Arrangements for using waste heat
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • the present invention relates to a method and an apparatus for preheating metallic charge material for discharging into a converter of a BOS-plant for the production of molten metal.
  • the relatively cold scrap cools the pig iron to an average temperature and therefore when the oxygen lance is lowered into the vessel and the oxygen ignited, the heat needed to melt the scrap comes from the heat of combustion of the silicon, carbon and manganese in the pig iron, and possibly from the combustion of some iron from the pig iron.
  • considerable time and oxygen are required to bring up the heat to desired temperature and some of the pig iron may be consumed in this process. Consequently the implementation of solid scrap preheating in the metal industry has been a subject of interest due to the economic and energy saving benefits.
  • US 3479178 discloses a method wherein ferromagnetic steel scrap is preheated by radiant heating devices to an elevated temperature within an enclosure prior to charging the steel scrap into an adjacent basic oxygen furnace. The method comprises reheating the scrap to a temperature of at most just below the Curie temperature to avoid losing its ferromagnetic properties, and magnetically lifting and transferring the preheated scrap into the furnace.
  • US 3479178 employs a preheat furnace which is a tunnel-type furnace wherein a car or cars carrying scrap passes through the furnace and is being reheated during its progress through the furnace.
  • the disadvantage of this method is that the heating is quite inefficient due to the need to heat the furnace and the cars and the ferromagnetic steel scrap and also that it is a discontinuous process involving magnetic lifting and transferring the preheated scrap.
  • EP0747492-A1 discloses a method to improve the efficiency of an electric arc (EAF) melting furnace by introducing and burning complementary energy releasing material, such as tire rubber, which is intimately mixed with the ferrous material before being fed into the EAF.
  • EAF electric arc
  • EP0592723 discloses a method for the preheating of charge materials using the offgases of an EAF and using any chemical heat in the off-gases provided sufficient oxygen is injected into the furnace to create CO in the off-gases. Carbon is injected into the slag or slag-metal interface as powdered carbon or coke through underbath tuyeres to form a foaming slag and results in the formation of CO in the off-gases.
  • hot arc furnace off-gas exiting the REF or SAF and entering the heating device gas entry point (5a) wherein the hot off-gas moves in the opposite direction to the direction of movement of the metallic charge material through the heating device (countercurrent), and/or 2.
  • the chemical heat generated by post-combustion in burner means in a burner section (8) of the heating device of the combustible gases in the BOFG (9) or of the combustible gases in the AFG wherein the off-gases are optionally supplemented by a secondary fuel (10), thereby heating the metallic charge material and discharging the hot metallic charge material from the heating device exit point into the converter through a charging opening in the converter or the REF or SAF.
  • the process as described above could also be implemented in concurrent flow instead of countercurrent flow of metallic charge material and BOFG or AFG, but this is less efficient.
  • off-gases (COG, BFG, BOFG, REFG en SAFG) exit the furnaces at high temperatures and they therefore carry a significant amount of energy (sensible and chemical heat) that is to be considered as losses if not properly re-used.
  • Conventional EAF's are used to melt scrap, and the offgases do not contain combustible gases.
  • One of the ways to use the sensible energy contained in these gases, and of BOFG and REFG in particular, is to use the sensible heat to preheat scrap metal before introducing it into a converter or an AF.
  • BOF off-gas has the following typical characteristics:
  • the benefit is to reduce the time and energy needed to melt the scrap and thereby increase the overall energy efficiency. As the heat is coming from hot off-gases, the energy saving benefit is high. Another point of interest is that moisture has to be removed from the metal scrap before it is loaded into the melting furnace to avoid severe explosions known as molten metal splash. By pre-heating the scrap any moisture is removed and as a result of the heat in the heating device. According to the invention any VOC and low melting metals (such as zinc) that may still be present on the scrap is vaporised and as a result the scrap is cleaned before it is charged into the relevant steelmaking device. The limitation of the risk of molten metal splash is a big safety bonus of the method according to the invention. In addition the BOFG and REFG also contains large amounts of chemical energy in the form of combustible compounds like CO.
  • the invention preheats metallic charge material, such as metallic scrap or scrap, thus allowing higher metallic charge inputs in iron and steelmaking processes because of the reduced cooling effect of the hot charge and it reduces the energy consumption to maintain the temperature of the processes.
  • metallic charge material such as metallic scrap or scrap
  • other potential metallic charge material could be DRI pellets, HBI, iron ore or solid pig iron.
  • a process for producing a hot metallic charge material and for subsequent discharging the hot metallic charge material into a reducing electrical arc furnace (REF) or into a submerged electric arc furnace (SAF), by feeding cold metallic charge material through a heating device (3) provided with conveyor means (4) for conveying the metallic charge material from a heating device charging point (5) to a heating device discharging point (6) wherein said metallic charge material is preheated in a continuous process by 1. the sensible heat present in one or more of i. hot BOF off-gas (7, BOFG) exiting the converter (1) and entering the heating device gas entry point (5a) and/or ii.
  • hot arc furnace off-gas exiting the REF or SAF and entering the heating device gas entry point (5a) wherein the hot off-gas moves in the opposite direction to the direction of movement of the metallic charge material through the heating device, and/or 2.
  • the chemical heat generated by post-combustion in burner means in a burner section (8) of the heating device of the combustible gases in the BOFG (9) or of the combustible gases in the AFG wherein the off-gases are optionally supplemented by a secondary fuel (10), thereby heating the metallic charge material and discharging the hot metallic charge material from the heating device exit point into the converter through a charging opening in the REF or SAF.
  • CO2 (16) is captured from the flue gas exiting the heating device and sent to a CO2 processing facility for cleaning, storage or for further utilization.
  • the heating device is provided with dust and fume capturing means and VOC-capturing means for preventing release of dust and VOC and wherein the dust and fume capturing means and the VOC-capturing means are adapted to process the dust, fumes and/or VOC to minimize the environmental impact of the process and maximise the re-use of the resources present in the dust, fumes and VOC. Any SOx and NOx traces are removed by known systems.
  • the heating device may be equipped with a separate unit for combustion of VOC that may develop during the heating of the metallic charge material. Also any dust developed during the heating of the metallic charge material is collected, e.g. by employing a negative pressure technology which allows better control over flame direction and penetration into the scrap pieces.
  • temperature measurement means are provided between the first and the second heating zone and wherein the temperature reading is used as a 'feedforward' input parameter for controlling the burner settings of the second heating zone.
  • a burner/fuel mix controller assists in choosing the correct burner settings and the right fuel mix.
  • the following alternatives can be considered: hydrogen, natural gas, propane, syngas, cold BOFG or AFG, purified blast furnace off-gas, purified coke oven gas.
  • the hydrogen may be "green” (from electrolysis based on green electricity), “blue” (from steam methane reforming integrated with carbon capture for lower CO2 footprint) or “grey” (e.g. from steam methane reforming without carbon capture).
  • Syngas may be provided by gasification of coal I coke I municipal waste, integrated with or without carbon capture.
  • the first preheating zone (5) operates in a counter-current flow mechanism where the hottest BOFG or AFG contact the hottest metallic charge material and the cooled BOFG or AFG contact the colder metallic charge material.
  • the first heating zone may preferably be provided with a temperature resistant conveyor belt for conveying the metallic charge material while being preheated or with a rotating drum or rotating tube to increase the residence time and to increase the heat transfer.
  • the conveyor belt may be only moving forward, but it may also be provided with vibration means to increase the heating homogeneity.
  • the second heating zone is provided with one or more burners in a burner section, preferably with oxyfuel burners, enabling a controlled heating to reach the target discharge temperatures of the metallic charge material whilst fully utilising the calorific value of BOFG - or AFG gases.
  • the burners are of the direct flame impingement (DFI) type.
  • Option b charging from the top
  • the charging may be continuous or semicontinuous to increase productivity and to have a balanced (steady or semi-steady state) operation.
  • the charging of the converter is likely to be semicontinuous or batchwise.
  • An AF may be charged in a continuous way or semicontinuous, although also here a batchwise charging is possible.
  • a continuous way results in the lowest loss of heat of the charge as the hot metallic charge material is immediately processed without any delay.
  • the temperature of the hot metallic charge material exiting the heating device is controlled by one or more temperature measuring means and by adjusting 1. the flow of hot BOFG or 2. the flow of hot AFG or 3. the flow of hot BOFG and hot AFG or 4. adjusting the burners in the burner section, optionally by adding a secondary fuel to the cooled BOFG or to the cooled AFG to top up the caloric value of the gas supplied to the burners in the burner section.
  • cold metallic charge material is continuously provided to the heating device and/or wherein hot metallic charge material is continuously discharged from the heating device.
  • the process relates to producing the hot metallic charge material and for subsequent discharging the hot metallic charge material into a converter by feeding the cold metallic charge material through the heating device wherein the metallic charge material is preheated in a continuous process by the sensible heat present in BOFG and by the chemical heat generated by post-combustion in burner means in the burner section (8) of the heating device of the combustible gases in the BOFG wherein the BOFG is optionally supplemented by a secondary fuel, thereby heating the metallic charge material and discharging the hot metallic charge material from the heating device exit point into the converter.
  • This embodiment is particularly relevant for steel production sites that do not have access to AFG, for instance because the production facilities on the site do not include SAF's or REF's.
  • the invention is also embodied in an apparatus for preheating metallic charge material for use in the production of steel in a basic oxygen furnace (1) or a reducing or submerged arc furnace comprising a heating device (3) comprising a first heating zone (11) and a second heating zone (12) provided with conveyor means (4) for conveying the metallic charge material from a heating device charging point (5) to a heating device discharging point (6) wherein, in use, in the first heating zone said metallic charge material is heatable by 1. the sensible heat present in BOF off-gas (7) (BOFG) exiting the BOF and entering the hot gas entry point (5a) of the first heating zone (11) of the heating device or 2.
  • BOFG BOF off-gas (7)
  • This gas is led through the first heating zone of the heating device though which selected metallic charge material is conveyed in the opposite direction to benefit maximally from the exchange of heat between BOFG and scrap.
  • the conveying means belt preferably allow a good contact between gas and scrap. This may be achieved by agitating the scrap whilst conveying it.
  • the BOFG exits the heating device cooler and is temporarily stored in a gas holder.
  • the temperature of the off-gas is preferably below 100°C, more preferably below 75 °C and even more preferably below 50 °C. Mutatis mutandis this is also applicable in case the off-gas is AFG.
  • the preheated scrap meanwhile exits the first heating zone and enters the second heating zone.
  • the temperature T1 is measured and fed into the second heating zone, where the burner/fuel mix controller instructs mixing of appropriate fuels to allow the scrap to be preheated and leave the second heating zone with the target temperature T2 of about 780 to 800°C.
  • the preheated scrap is then charged to a BOF that is ready to receive it in preparation of receipt of liquid iron and the additives after which it can start the blowing process to produce steel.
  • Most steel plants have several BOF's, e.g. 3, so that BOFG from one BOF can be used to preheat metallic charge material for another BOF, etc..

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Furnace Details (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)

Abstract

La présente invention concerne un procédé et un appareil pour produire un matériau de charge métallique chaud et pour décharger ensuite le matériau de charge métallique chaud dans un convertisseur d'une installation BOS ou dans un four à arc électrique réducteur (REF) ou dans un four à arc électrique submergé (SAF), par alimentation d'un matériau de charge métallique froid dans un dispositif de chauffage.
EP23817385.0A 2022-11-30 2023-11-30 Procédé de préchauffage de matériau de charge métallique et appareil de préchauffage de matériau de charge métallique Pending EP4627121A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP22210587 2022-11-30
PCT/EP2023/083770 WO2024115674A1 (fr) 2022-11-30 2023-11-30 Procédé de préchauffage de matériau de charge métallique et appareil de préchauffage de matériau de charge métallique

Publications (1)

Publication Number Publication Date
EP4627121A1 true EP4627121A1 (fr) 2025-10-08

Family

ID=84367031

Family Applications (1)

Application Number Title Priority Date Filing Date
EP23817385.0A Pending EP4627121A1 (fr) 2022-11-30 2023-11-30 Procédé de préchauffage de matériau de charge métallique et appareil de préchauffage de matériau de charge métallique

Country Status (3)

Country Link
EP (1) EP4627121A1 (fr)
KR (1) KR20250115992A (fr)
WO (1) WO2024115674A1 (fr)

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3479178A (en) 1966-05-24 1969-11-18 James J Bowden Method of preheating and charging scrap to a bof
US3645515A (en) * 1970-10-12 1972-02-29 Waagner Biro American Metallurgical furnace installation and operating method
US5400358A (en) 1992-10-13 1995-03-21 Consteel, S.A. Continuous scrap preheating
CH690128A5 (it) 1995-06-08 2000-05-15 Elti Srl Procedimento di fusione di metalli ferrosi mediante un forno ad arco elettrico.
AUPP136398A0 (en) * 1998-01-16 1998-02-05 Noonan, Gregory Joseph Sustainable steelmaking by efficient direct reduction of iron oxide and solid waste minimisation

Also Published As

Publication number Publication date
KR20250115992A (ko) 2025-07-31
WO2024115674A1 (fr) 2024-06-06

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