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WO2024100435A1 - Lance de post-combustion - Google Patents

Lance de post-combustion Download PDF

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Publication number
WO2024100435A1
WO2024100435A1 PCT/IB2022/060834 IB2022060834W WO2024100435A1 WO 2024100435 A1 WO2024100435 A1 WO 2024100435A1 IB 2022060834 W IB2022060834 W IB 2022060834W WO 2024100435 A1 WO2024100435 A1 WO 2024100435A1
Authority
WO
WIPO (PCT)
Prior art keywords
lance
oxygen
ejection
primary
mean
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
PCT/IB2022/060834
Other languages
English (en)
Inventor
Hamzeh HAMADEH
Damien WAGNER
Jean-Christophe HUBER
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.)
ArcelorMittal SA
Original Assignee
ArcelorMittal 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 ArcelorMittal SA filed Critical ArcelorMittal SA
Priority to PCT/IB2022/060834 priority Critical patent/WO2024100435A1/fr
Publication of WO2024100435A1 publication Critical patent/WO2024100435A1/fr
Anticipated expiration legal-status Critical
Ceased 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
    • C21C5/28—Manufacture of steel in the converter
    • 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
    • C21C5/28—Manufacture of steel in the converter
    • C21C5/30—Regulating or controlling the blowing
    • C21C5/305—Afterburning
    • 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
    • C21C5/28—Manufacture of steel in the converter
    • C21C5/30—Regulating or controlling the blowing
    • C21C5/32—Blowing from above
    • 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
    • C21C5/28—Manufacture of steel in the converter
    • C21C5/42—Constructional features of converters
    • C21C5/46—Details or accessories
    • C21C5/4606—Lances or injectors
    • 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
    • F27B3/22—Arrangements of air or gas supply devices
    • 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
    • F27D3/00—Charging; Discharging; Manipulation of charge
    • F27D3/16—Introducing a fluid jet or current into the charge
    • 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
    • C21C5/28—Manufacture of steel in the converter
    • C21C5/30—Regulating or controlling the blowing
    • C21C5/34—Blowing through the bath
    • 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
    • C21C5/28—Manufacture of steel in the converter
    • C21C5/30—Regulating or controlling the blowing
    • C21C5/35—Blowing from above and through the bath
    • 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
    • F27D3/00—Charging; Discharging; Manipulation of charge
    • F27D3/16—Introducing a fluid jet or current into the charge
    • F27D2003/168—Introducing a fluid jet or current into the charge through a lance
    • F27D2003/169—Construction of the lance, e.g. lances for injecting particles

Definitions

  • the invention is related to a lance for blowing oxygen onto a bath of molten steel, and more particularly to a lance for post-combustion in steelmaking.
  • the main starting materials are usually a mixture of liquid pig-iron and scrap.
  • the quantity of scrap which can be added depends notably on the temperature of the liquid pig iron and on the quantity of heat generated in the converter by oxidation of chemical elements. Most of it concerns the transformation of carbon into carbon monoxide CO and then into dioxide CO2. The more CO2 is formed, the more heat is created and may be transferred to bath so as to provide energy for additional scrap melting. The transformation of CO to CO2 is known as postcombustion.
  • the first one consists in having a single oxygen flow supply and then split it in a primary flux for standard decarburization and a secondary flow for enhancing post-combustion.
  • This first technology has the advantage of requiring few modifications of existing lances and for example to keep same lance diameter and weight, thus not impairing the overall support structure of the lance and reducing investment costs.
  • Disadvantage is that the secondary flow rate of oxygen being defined by the surface ratio between primary and secondary oxygen ejection means, it cannot be managed independently form the primary flow according to the process phases. Also, if oxygen supply is limited, primary oxygen flow is reduced, which impairs the decarburization process and productivity.
  • the second technology consists in having a dual flow lance, wherein primary and secondary flows of oxygen have their own supply and are independently controlled.
  • An example of a lance according to this technology is illustrated in patent US 5,681 ,526.
  • Main advantage of this technology is that primary and secondary flows of oxygen are independently controlled which allows to more accurately control the post-combustion process and thus to increase the post-combustion rate.
  • Disadvantage of this technology is that it requires an overall change on the installation and thus high investment cost.
  • Document WO/2022/074430 discloses a dual flow lance equipped with a distributor to eject a secondary jet of oxygen.
  • a distributor to eject a secondary jet of oxygen.
  • the combustion generated by the oxygen is too close to the lance which is thus damaged each time post-combustion process is used.
  • the post-combustion rate achieved is lower than expected.
  • the post combustion lance must be able to inject the secondary flux of oxygen so as to provide enough oxygen at the right location for the post-combustion to happen without damaging the internal refractory layer of the steelmaking vessel.
  • the lance according to the invention must allow to reach a Post combustion rate comprised between 12 and 25%. Upper limit is needed as part of energy will be transferred to the bath, but another part will be transferred to the exhaust gas, whose temperature will thus increase which could damage exhaust gas treatment system.
  • a post-combustion lance comprising a plurality of tubes which surround one another and are concentric to a central longitudinal axis of the lance Z, among this plurality of tubes being a first central tube forming a supply duct for a primary flux of oxygen, and at least one second tube surrounding said first central tube so as to form a gap for the circulation of a secondary flux of oxygen, the lance further comprising a tip located at one end of the lance and provided with at least a primary oxygen ejection mean for ejection of the primary flow of oxygen and a distributor comprising at least four channels in fluid connection with the gap for the circulation of the secondary flux of oxygen of the lance, each channel being provided with at least one secondary oxygen ejection mean designed so that it forms an ejection angle p from 20 to 60°with the central longitudinal axis Z of the lance and so that it ejects the secondary flux of oxygen at a supersonic speed.
  • the method of the invention may also comprise the following optional characteristics considered separately or according to all possible technical combinations: the secondary oxygen ejection mean outlet is located at a distance d above the primary oxygen ejection mean outlet of the tip, the ratio between the distance d and the internal diameter D of the converter being set from 0,04 to 0,15, the distance d is from 250mm to 750mm, the distance d is from 500mm to 750mm, the ejection angle p with the central longitudinal axis Z of the lance is from 20 to 45°, the secondary oxygen ejection mean has a Laval nozzle design, the secondary oxygen ejection mean has a bell-shape Laval nozzle design, the distributor comprises five channels, the number of primary oxygen ejection mean is the same as the number of secondary oxygen ejection mean, the outlets of the secondary oxygen ejection mean of the distributor are shifted from the outlets of the primary oxygen ejection mean of the tip.
  • the invention is also related to a steelmaking method using a lance according to anyone of the previous embodiments, wherein the flow of secondary oxygen is from 50 to 135 Nm3/min.
  • Figure 1 illustrates a post-combustion process in a converter
  • Figure 2 illustrates a first embodiment of a lance according to the invention
  • Figure 3 illustrates a second embodiment of a lance according to the invention
  • Figure 4 illustrates results of simulations of a post-combustion process using a lance according to the invention
  • Figure 1 illustrates a converter 2 containing a bath of molten metal 20.
  • the converter is internally covered with a wall of refractories 3 and have an internal diameter D.
  • the molten metal is pig iron which needs to be decarburized to produce steel.
  • a lance 1 is inserted into the converter and blows a primary flux of oxygen 21 towards the molten metal 20 through an outlet provided in the tip 15 of the lance.
  • This decarburization allows to remove carbon from the bath as CO.
  • a second flux of oxygen 22 is injected towards uprising exhaust gas. This reaction is exothermic and releases a lot of energy which can be further used to melt scrap into the molten bath.
  • This double oxygen injection is performed with a post combustion lance, as the one illustrated in figure 2, according to one embodiment of the invention.
  • a lance is usually more than 20 meters long.
  • the post-combustion lance 1 according to the invention comprises a plurality of tubes which surround one another and are concentric to a central longitudinal axis of the lance Z.
  • the lance according to the invention is made of an upper part 1A and of a lower part 1 B joined together by a distributor 17.
  • the lower part 1 B of the lance is the one closest to the bath 20 when inserted into the steelmaking vessel 2.
  • the lance is composed of a first tube 11 which supplies the primary flux of oxygen 21 , a second tube 12, which surrounds the main tube 11 thus forming a first annular gap 31 for the supply of cooling water within the lance 1.
  • the lance being subjected to high temperature during the steelmaking process it needs to be constantly cooled down so as to avoid being quickly damaged.
  • Those two first tubes go along the whole length of the lance, each in a single part, which allows reducing risks of tightness issues.
  • the first tube 11 is preferentially made of a material allowing the passage of a flow at a speed of at least 60m/s, such as stainless steel.
  • the lance 1 then comprises a third tube 13, surrounding the second tube 12 to form a second annular gap 32 for the supply of the secondary flux of oxygen 22 necessary for the post-combustion.
  • This third tube does not extend all along the length of the lance 1 but only along the upper part 1 A.
  • This third tube is preferentially designed so that there is a ratio of 1/5 between the section of the gap for the circulation of the primary of oxygen and the section of the gap for the circulation of the secondary flux of oxygen.
  • a fourth tube 14, comprising two parts, a first part 14A, which surrounds the third tube 13 along the upper part 1A of the lance, and a second part 14B surrounding the second tube 12 along the lower part 1 B of the lance.
  • This fourth tube 14 thus form a third annular gap 33 allowing to draw off the cooling water.
  • this first annular gap 31 may be designed for the drawn off of the cooling water from the lance 1 while the third annular gap 33 allows the entry of the water within the lance 1.
  • the lance 1 further comprises a tip 15, closing the lower part of the lance 1 B.
  • This tip is in fluid connection with both first 31 and third annular gaps 33 so as to close the water circuit and provide circulation of water within the lance. This furthermore allows the cooling down of the tip 15 itself which is the closest part to the molten steel and thus subjected to the highest temperatures.
  • the tip is provided with at least one primary oxygen ejection mean 16 for blowing primary flow of oxygen 21 onto the bath of molten steel and allowing decarburization.
  • the tip is provided with at least four primary oxygen ejection means 16, the optimal number depending notably on the size of the ladle and thus of the circumference of the molten bath.
  • the diameter of the primary oxygen ejection means exit depends on the same parameters. In a preferred embodiment those primary oxygen ejection means 16 have an exit diameter comprised between 40 and 50mm, preferentially between 40 and 45mm.
  • these ejection means are designed so as to eject the primary flux of oxygen with an ejection angle a with the central axis Z of the lance 1 comprised between 10 and 20°, preferentially between 14 and 18°. This allows to find the good compromise between maximisation of the surface of the molten bath receiving oxygen ang keeping sufficient distance from the refractory walls to avoid damaging them.
  • the lance is designed to receive a distributor 17 making the junction between the upper 1 A and the lower part 1 B of the lance and ensuring the circulation of water between the upper 14A and the lower 14B parts of the fourth tube.
  • This distributor 17 comprises at least four channels 6 in fluid connection with the gap 32 for the circulation of the secondary flux of oxygen 22 of the lance.
  • Each channel 6 is provided with at least one secondary oxygen ejection mean for blowing the secondary flux of oxygen 22 towards the uprising gas flux. This secondary flux of oxygen will provide necessary fuel for the further combustion of CO and the release of additional energy for scrap melting.
  • Secondary oxygen ejection means 18 are located at a distance d above the primary oxygen ejection means 16 of the tip 15 such as the ratio between the distance d and the internal diameter D of the converter 2 is preferably from 0,04 to 0,15, and even preferentially from 0,08 to 0,15.
  • They may be located between 250 and 750mm above the first oxygen ejection means 16 of the tip 15, preferentially between 500 and 750mm.
  • the secondary 18 ejection mean may be simple ports located at the exit of the channels 6 or nozzles inserted at the exit of the channel 6.
  • the distributor 17 is provided with the same number of secondary ejection means 18 as the number of primary ejection means 16 provided on the tip 15. Their respective exist are preferentially shifted.
  • the exit diameter of the secondary ejection mean may be comprised between 10 and 25mm.
  • the exits may have an oblong or circular shape.
  • the secondary ejection means 18 are designed so as to have an ejection angle p with the longitudinal axis Z of the lance comprised between 20 and 60° and to eject the secondary oxygen flux at supersonic speed. This range of angles allows to avoid damaging both the lance itself, with angles inferior to 20°, and the refractory walls whose temperature would increase too much with angles higher than 60°.
  • supersonic speed it is meant speed of an object that exceeds the speed of sound in the same physical conditions, which includes notably pressure, temperature, and humidity rate.
  • the ejection speed of the secondary flux of oxygen is preferably superior or equal to 1 ,9 Mach, preferentially superior or equal to 1 ,96 Mach.
  • the secondary ejection means have a Laval nozzle design. They may preferentially have a bell-shape Laval nozzle design, which allows to increase lifetime of the distributor 17.
  • the distributor is mounted on the lance 1 so as to be able to slide of few centimetres, less than 5 cm, along the pipe 12 in order to follow the thermal expansion of the external tube 14 due to thermal constraints it is subjected to. This is done by appropriate means, such as O-rings.
  • the distributor is furthermore provided with sealing means preventing water leakage in the annular gaps supplying the oxygen flows. These sealing means are for example O-rings.
  • FIG. 3 illustrates a lance 1 according to a second embodiment of the invention.
  • the layout of the different tubes forming gaps for fluid supply is different from the previous one.
  • the lance provides primary oxygen, secondary oxygen and inlet and outlet water.
  • Configuration of the tip 15 and of the distributor 17 are adapted to be compatible with this embodiment but all parameters of the previous embodiment, namely size, shape, angle and location of the ejection means apply to this embodiment.
  • flow of secondary oxygen is preferably comprised between 50 and 135 Nm 3 /min.
  • ANSYS Fluent software was used, which is a commercial finite volume solver used for CFD.
  • the model is independent of time, i.e. steady state.
  • the governing equations are conservation of mass, momentum and energy.
  • the turbulence was described by the standard k-£ turbulence model.
  • Post Combustion rate is representative of the amount of CO gas which is transformed into CO2, thus releasing energy. Absorbed energy by the bath will impact the amount of scrap which can be additionally loaded into the bath.
  • Figure 4A illustrates a simulation performed with same ANSYS fluent software to simulate temperatures at the exit of a lance equipped with a post-combustion distributor.
  • Figure 4A illustrates results obtained with a lance according to prior art, with a secondary jet ejected at subsonic speed while in Figure 4B are illustrated results obtained with a lance according to the invention equipped with Laval nozzles to eject the secondary flux of oxygen at supersonic speed. In both cases angle of ejection p was of 30°.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Carbon Steel Or Casting Steel Manufacturing (AREA)

Abstract

Lance (1) de post-combustion comprenant une pluralité de tubes placés l'un autour de l'autre qui sont concentriques par rapport à un axe longitudinal central de la lance Z, une pointe (15) située à une extrémité de la lance (1) et pourvue d'au moins une sortie d'oxygène principale (16) permettant l'éjection du flux principal d'oxygène (21) et un distributeur (17) comprenant au moins quatre canaux (6), chacun étant pourvu d'une sortie d'oxygène secondaire (18) et étant conçu de manière à former avec l'axe longitudinal central de la lance un angle d'éjection β compris entre 20 et 60° et pour éjecter le flux secondaire d'oxygène à une vitesse supersonique.
PCT/IB2022/060834 2022-11-10 2022-11-10 Lance de post-combustion Ceased WO2024100435A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/IB2022/060834 WO2024100435A1 (fr) 2022-11-10 2022-11-10 Lance de post-combustion

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/IB2022/060834 WO2024100435A1 (fr) 2022-11-10 2022-11-10 Lance de post-combustion

Publications (1)

Publication Number Publication Date
WO2024100435A1 true WO2024100435A1 (fr) 2024-05-16

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ID=84360869

Family Applications (1)

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PCT/IB2022/060834 Ceased WO2024100435A1 (fr) 2022-11-10 2022-11-10 Lance de post-combustion

Country Status (1)

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WO (1) WO2024100435A1 (fr)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5681526A (en) 1996-04-23 1997-10-28 Usx Corporation Method and apparatus for post-combustion of gases during the refining of molten metal
EP1530648A1 (fr) * 2002-08-21 2005-05-18 Voest-Alpine Industrieanlagenbau GmbH & Co. Procedes et dispositif de decarburation d'une fonte d'acier
WO2022074555A1 (fr) * 2020-10-06 2022-04-14 Arcelormittal Lance pour souffler de l'oxygène dans l'élaboration de l'acier
WO2022074430A1 (fr) 2020-10-06 2022-04-14 Arcelormittal Lance de post-combustion

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5681526A (en) 1996-04-23 1997-10-28 Usx Corporation Method and apparatus for post-combustion of gases during the refining of molten metal
EP1530648A1 (fr) * 2002-08-21 2005-05-18 Voest-Alpine Industrieanlagenbau GmbH & Co. Procedes et dispositif de decarburation d'une fonte d'acier
WO2022074555A1 (fr) * 2020-10-06 2022-04-14 Arcelormittal Lance pour souffler de l'oxygène dans l'élaboration de l'acier
WO2022074430A1 (fr) 2020-10-06 2022-04-14 Arcelormittal Lance de post-combustion

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