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
  • C21C5/42—Constructional features of converters
  • C21C5/46—Details or accessories
• • 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

Definitions

• the present invention relates to a blowing lance nose, intended for the mixing of baths, comprising a central tube for supplying mixing gas, closed at one end facing the bath by a first front wall provided with at least one opening, an internal tube forming with the central tube a first annular cavity for the passage of a coolant and closed at one end facing the bath by a second front wall having a central opening and an opening for passage provided in said first front wall, an external tube forming with the internal tube a second annular cavity for the passage of coolant and closed at one end facing the bath by a third front wall having an outlet orifice by opening provided in said first wall front, a heat exchange space which is located between, on the one hand, said second fron wall tale and said third front wall and, on the other hand, said central opening and said second annular cavity, and in which the coolant flows, and an outlet conduit for the stirring gas leaving each opening in said first front wall and going to a corresponding aforesaid outlet orifice passing through a said aforesaid or
• blowing lance nose has been known for a long time.
• the lance noses work at a distance from the bath of 1 to 2.5 m, while the bath has a temperature of the order of 1400 ° C.
• the temperature of the nose can rapidly increase to 400 ° C., and must remain in this environment for approximately 20 minutes. Then, when the lance is removed, the nose quickly returns to room temperature, that is to say at 20 ° C.
• the front walls of the lance noses in a very good conductive material of heat, for example copper, to allow a heat exchange as efficient as possible with a coolant which flows at high speed the along this wall, inside the nose.
• the already known lance noses have the drawback of offering cooling which is not uniform over the entire surface of this wall exposed to variations in extremely critical thermal conditions. This results in mechanical tensions between the different zones of the wall.
• cavitation phenomena are frequently observed in the coolant as a result of local depressions therein. This cavitation has the effect of causing poor cooling between the coolant and the wall to be cooled, the heat exchanges being much less good between a gas phase and a solid phase than between a liquid phase and a solid phase.
• the object of the present invention is to provide a lance nose which is capable of undergoing the significant stresses to which it is subjected, during a significant number of successive uses, while providing a lance nose which is simple to manufacture and of defensible cost.
• a blowing lance nose as described at the start, in which said third front wall has a central depression which is directed towards said central opening and which has a relationship between depression height and vacuum base equal to or greater than 0.35, and the aforementioned heat exchange space has a section for the passage of the coolant which is substantially constant, so as to obtain a speed of passage of the coolant through this space which is approximately constant, in the presence of said depression.
• said central depression has a ratio between height and base equal to or greater than 0.4, in particular 0.5, and preferably even 0.8.
• section for the passage of coolant it is meant that the intended sections are taken perpendicular to the direction of flow of the coolant in the heat exchange space. In this way, at constant flow, the flow / section ratio remains constant and therefore the speed of passage of the liquid also remains constant.
• a speed of passage of the flow liquid will be provided between 8 and 12 m / sec.
• the lance nose comprises several said passage conduits arranged around a central axis and in that said central depression extends from said outlet orifices of these conduits.
• the base of the depression is thus advantageously maximum and allows an improved efficiency of the heat exchange in the depression.
• the third front wall has an external diameter and the base of said depression is a circle having a diameter equal to at least 0.25 x said external diameter, preferably to at least 0.33 x this external diameter .
• the central depression is thus according to the invention in no way a small central recess arranged in the wall of the nose to reinforce the rigidity of the latter.
• said third front wall has a central depression in the shape of a cone.
• said second front wall has, around the central opening, a central deformation in the form of a truncated cone, which is directed towards said first front wall.
• said cone and said truncated cone have a common axis and the central depression in the form of a cone forms with this axis an angle greater than the angle formed between this axis and the central deformation in the form of a truncated cone.
• the central depression is covered at least partially with a protective screen made of a material with high thermal resistance. It can be a disc-shaped plate which is carried by the central depression or pressed against it and which therefore does not require any welding for its fixing.
• the heat exchange between the coolant and the third front wall remains unchanged, while a large part of the area of the third front wall is protected from excessive overheating.
• Figure 1 shows an axial sectional view of a blowing lance nose according to the invention.
• FIG. 2 shows an axial sectional view of an alternative embodiment.
• FIG. 3 shows a detail of a lance nose according to the invention, to illustrate the method of measuring the parameters necessary for the invention.
• FIG 1 there is shown a nose 1 of blowing lance.
• This nose includes a central tube 2 for supplying stirring gas.
• This central tube 2 is closed by a front wall 3 which, in the example illustrated, is provided with several openings 4.
• An internal tube 5 is arranged coaxially around the central tube 2 and these tubes form between them an annular cavity 6 which, in the example illustrated, is used for the supply of cooling water in the direction of the arrow F ⁇ Ce inner tube 5 is closed by a front wall 7 which is called a separator.
• This front wall 7 is provided with a central opening 8 and an orifice 9 in alignment with each opening 4 in the central tube 2.
• An external tube 10 is arranged coaxially around the central tube 2.
• This external tube is generally made of steel and it forms with the internal tube 5 an annular cavity 11 which, in the example illustrated, is used for the outlet of water from cooling in the direction of arrow F 2 .
• This external tube 10 is closed by a front wall 12 which faces the brewing bath and which is therefore subjected to critical thermal stresses, as explained above.
• this front wall is made of a material which is a good conductor of heat, for example copper, to allow a heat exchange as efficient as possible between the front wall 12 heated and the cooling water passing through the heat exchange space 13 which is located between the front wall 7 of the inner tube 5 and the front wall 12 of the outer tube 10.
• the cooling water coming from the cavity 6 passes through the central opening 8 in the heat exchange zone 13. There it flows in the direction of the arrow F 3 towards the outside, that is to say towards the cavity 11.
• the front wall 12 is also provided with an outlet orifice 14 in alignment with each opening 4 provided in the front wall 3 and with each through orifice 9 provided in the front wall 7.
• an outlet conduit 15 for the ejection of stirring gas outside the lance nose.
• These conduits are advantageously made of an erosion-resistant material, for example bronze, and are directed obliquely to the axis 19 of the lance nose.
• the outer front wall 12 is, according to the invention, provided in its center with a depression 16 in the form of a cone, which is directed towards the central opening.
• this depression is sufficiently pronounced to present a ratio between the height of the internal wall of the cone (h) and the base diameter (B) equal to or greater than 0.35. In the illustrated case this ratio is equal to approximately 0.5. In this way, the heat exchange zone 13 is greatly increased for the same heat front undergone by the lance nose, hence an increased efficiency of the cooling of the front wall 12. It is entirely advantageous, as shown , that this depression 16 extends from the outlet conduits 15 and therefore forms a cone whose base is maximum. In the example illustrated, the ratio between the base B of the depression and the external diameter D of the front wall 12 is approximately 0.33. In addition, by the deep depression, the central area of the front wall outer 12, which is the most stressed thermally, is separated as far as possible from the surface of the bath.
• FIG. 3 illustrates how the parameters h and B of the lance nose according to the invention must be measured.
• the height h is calculated between, on the one hand, the lower tangent plane 30 of the lance nose perpendicular to the axis 19 and the parallel plane 31 tangent to the top of the depression. If an element foreign to the depression is provided at the top thereof, such as for example the tie 20 in FIG. 2, the plane 31 remains in the position it would have if this foreign element did not exist. The summit of the depression must then be considered as a virtual point to be taken into account in the measurement.
• the base B is located in the lower tangent plane 30. It is circumscribed by the line 32 resulting from the crossing between this plane 30 and the extension 33 of the internal faces 34 of the depression. Rounding is therefore not taken into account.
• the outer diameter of the front wall 12 is taken where its value is maximum.
• This deformation 17 has the shape of a truncated cone open towards the high through the central opening 8.
• This truncated cone 17 is coaxial with the cone formed by the depression 16, their common axis being the axis 19 of the lance nose.
• the cone of the depression 16 forms with the axis 19 an angle greater than the angle formed between this axis and the imaginary extension of the truncated cone 17 to this axis.
• the truncated cone is narrower. So the section of the heat exchange space between the front walls 7 and 12, which is measured in a plane perpendicular to the direction of flow of the coolant, remains constant even in the presence of the central depression 16 provided in the embodiment illustrated in FIG. 1. Furthermore, at the outlet conduits 15, the coolant can only pass through the interstices situated circumferentially between these conduits in the heat exchange space 13. Consequently, to maintain a constant passage section for the liquid at this location cooling and therefore a constant passage speed at a given flow rate, an inward bulge 18 in the front wall 7 serving as a separator is provided in each of the aforementioned interstices.
• the lance nose according to the invention is therefore arranged so as to provide over the entire extent of the heat exchange zone 13 a constant passage section for the coolant.
• a ratio is obtained between this flow rate (d) and the section (S) which remains constant during the operation of the lance, this ratio corresponding to a speed of passage of the flow liquid expressed in m / sec.
• the flow rate and the section will be determined to obtain an approximately constant speed of passage of between 8 and 12 m / sec. The cavitation phenomenon can thus be avoided as much as possible, which greatly improves the efficiency of the heat exchange obtained in the nose.
• a lance nose which differs from that shown in Figure 1 in that the depression 16 is more pronounced.
• the top of the depression 16 projects through the opening 8 and therefore even opens into the space between the front walls 3 and 7, which makes it possible to obtain a ratio between h and B equal to or greater than 0.8.
• a retaining element can be provided, for example a tie rod 20, between the top of the depression and a nut arranged on or in the front wall 3 of the central tube 2.
• the depression central 16 is, in this embodiment, completely covered by a thermally resistant plate 21. In this way, while allowing an unchanged heat exchange between the cooling water and the cone formed by the depression 16, the central part of the lance nose is thermally insulated from the heat of the bath, which reinforces the efficiency of the heat exchange and allows a longer life of the lance nose.
• the plate 21 is composite, that is to say that it has an outer layer of a refractory material, for example ceramic, or of refractory steel and an inner layer in a thermally insulating material, such as for example fibrous alumina.
• a refractory material for example ceramic
• a thermally insulating material such as for example fibrous alumina
• this plate is simply clamped between the head 22 of a threaded rod 23 passing through the plate 21 and screwed into a thread provided in the head of the tie rod 20.
• Other methods of fixing this plate could of course be planned.
• the lifespan of a nose is calculated on the number of flows that could have been brewed before having to discard that nose. As can be seen from this table, the improvement in the average lifespan of the noses according to the invention is remarkable and completely unexpected.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Carbon Steel Or Casting Steel Manufacturing (AREA)
• Treatment Of Steel In Its Molten State (AREA)
• Furnace Charging Or Discharging (AREA)
• Nozzles (AREA)
• Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Heterocyclic Carbon Compounds Containing A Hetero Ring Having Oxygen Or Sulfur (AREA)
• Furnace Details (AREA)
• Furnace Housings, Linings, Walls, And Ceilings (AREA)

Applications Claiming Priority (3)

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• 2000
  • 2000-09-15 BE BE2000/0588A patent/BE1013686A3/fr not_active IP Right Cessation
• 2001
  • 2001-09-11 AU AU2001289429A patent/AU2001289429A1/en not_active Abandoned
  • 2001-09-11 JP JP2002527332A patent/JP2004524437A/ja active Pending
  • 2001-09-11 EP EP01969081A patent/EP1325161B1/de not_active Expired - Lifetime
  • 2001-09-11 WO PCT/BE2001/000148 patent/WO2002022892A1/fr active IP Right Grant
  • 2001-09-11 BR BR0113900-2A patent/BR0113900A/pt not_active IP Right Cessation
  • 2001-09-11 DE DE60110446T patent/DE60110446D1/de not_active Expired - Lifetime
  • 2001-09-11 KR KR10-2003-7003810A patent/KR20030046454A/ko not_active Application Discontinuation
  • 2001-09-11 CN CNB018156258A patent/CN1201024C/zh not_active Expired - Fee Related
  • 2001-09-11 AT AT01969081T patent/ATE294245T1/de not_active IP Right Cessation
  • 2001-09-11 US US10/380,216 patent/US6849228B2/en not_active Expired - Lifetime

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