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
  • C21C5/4606—Lances or injectors
• • 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
  • C21C2005/4626—Means for cooling, e.g. by gases, fluids or liquids

Definitions

• the present invention relates to a blowing nozzle nose, intended for brewing baths, comprising
• a central tube for supplying stirring gas closed at one end facing the bath by a first end wall provided with at least two openings,
• an inner tube forming, with the central tube, a first annular cavity for the passage of a cooling liquid and terminated at one end facing the bath by a second end wall, called a separator, having a central opening and a through-hole; opening provided in said first front wall,
• an outer tube forming with the inner tube a second annular cavity for the passage of the cooling liquid and closed at one end facing the bath by a third end wall having an opening opening opening provided in said first end wall and presenting a inner surface comprising a conical central zone which is directed towards said central opening and which has a curved envelope surface in axial section,
• an outlet duct for the stirring gas called an injector, starting from each opening in said first end wall and going up to said corresponding outlet orifice passing through said corresponding through orifice in a manner that is impervious to the cooling liquid.
• central conical zone which is directed towards said central opening and which has a surface
• the curved envelope in axial section will sometimes only be expressed by the words "central depression”.
• the blowing nozzle nose as described in the present invention is used, inter alia, in oxygen converters for the manufacture of steel (BOF Basic Oxygen Furnace, AOD Argon Oxygen Decarburization).
• the converters make it possible to obtain steel by injecting oxygen into a bath of molten iron in order to burn the carbon contained therein.
• the basic principle in the field of oxygen blowing in the converters (for example LD (for Linz-Donawitz)) is to propel 3 to 6 jets of oxygen arranged in a ring on a bath of molten iron. The lance that allows the formation of these jets of oxygen is then placed at a distance of 1 to 5 m above a bath of molten iron whose temperature can reach 1700 ° C.
• the temperature of the nose of the lance can then grow rapidly up to 400 ° C and have to stay in this environment for about 20 minutes.
• the nose is then removed and returns to room temperature, ie 20 ° C.
• a coolant can circulate along the inner wall facing the bath of the lance nose.
• a coolant usually water
• the calories of the metal forming the wall are transferred to this coolant.
• the temperature of the lance nose is uniformized over the nose, and no longer elevated only at the walls exposed to the bath.
• Poor circulation of the coolant can also cause a local rise in coolant temperature.
• locally the liquid can pass into the vapor phase under thermal stress. This results in the formation of cavities filled with trapped gas within the coolant. This formation of gaseous cavities in a liquid is known as the phenomenon of cavitation.
• US4432534 and WO9623082 have, for example, lance noses designed to allow the flow of a coolant at high speed along the inner surface of the front wall, the same front wall has a slight central depression to to optimize this flow.
• the document WO0222892 attempts to further improve the flow of the coolant in the heat exchange space of the lance nose by developing a central depression in the face facing the bath having a well-defined ratio between height and base of this depression. This ratio allows the heat exchange space to have a section for the passage of the coolant substantially constant so as to obtain a coolant flow rate through this space which is approximately constant.
• DE 19506718 discloses a blow lance nose used in or above liquid steel and having a cooling system based on the difference in roughness between the two walls of the heat exchange space, namely the separator and the inner surface of the third end wall.
• the ratio between the roughness difference and the minimum radius of curvature of the surface exposed to the liquid steel must be kept constant to ensure good cooling.
• the diameter of the outlets of the injectors tends to increase following the erosion of the edges thereof. This increase in diameter deforms the oxygen jets, which causes, in addition to the destruction of the lance nose, a dispersion of these jets and consequently a decrease in the effectiveness thereof.
• the carbon oxidation reaction is, in fact, favored by the depth of penetration of the jets in the bath and by stirring thereof.
• the lance noses are placed at a distance of 1 to 5 m above the cast iron bath, in order to be effective, the jets must present a coherent profile over a longest possible distance. The reaction yield is then decreased when these jets are dispersed because they penetrate less deeply into the melt.
• the reaction efficiency in the bath is therefore not optimal and in addition has a significant variability over the lifetime of the nose lance.
• Effective cooling is therefore important for the proper functioning of the lance noses, because it has the advantage of increasing the life of these but also to ensure a better reaction performance stability throughout their service life. and this by minimizing erosion at the edges of the front wall. Only such cooling is also very difficult to implement, in the extreme conditions encountered during the use of spear noses.
• the object of the present invention is to overcome these drawbacks of the state of the art by providing a simple lance nose to be manufactured whose life is increased and which makes it possible to ensure a reaction efficiency in the improved pigtank and stable throughout the life of the lance nose.
• a lance nose as indicated at the beginning in which the separator has at the central opening an edge in axial section which is curved such that a height H3 is defined between a front of said edge and said inner surface of the third end wall and that in the heat exchange space a predetermined minimum height H1 is present on the side of said central opening such that the ratio H1 / H3 is between 5% and 80 %, advantageously between 5% and 75%, preferably between 5% and 70%, preferably between 5% and 65%, particularly advantageously between 5% and 60%, preferably between 10% and 60%; , advantageously between 15% and 60%, preferably between 20% and 60%, preferably between 25% and 60%, particularly advantageously between 25% and 55%, preferably between 30% and 55%.
• the flow of coolant can be surprisingly improved by acting on both the configuration of the separator, in particular its edge at the central opening, and on its positioning relative to the third front wall.
• the edge of the separator at the central opening thanks to its curved axial section, allows the cooling liquid, coming from the first annular cavity, to make a progressive rotation between this curved edge and the central depression of the inner surface of the third end wall to arrive without disturbance in the heat exchange space.
• the injectors in the lance nose represent obstacles that are in the path of the coolant, firstly between the first and second end wall and then in the heat exchange space between the second and third walls end. It is therefore appropriate to "calm" the coolant after the bypass of the first obstacle that is the injectors between the first and second end wall.
• This role is achieved according to the present invention by the edge of the separator which is curved in axial section and which makes it possible to form at the central opening and in the heat exchange space optimized passage sections for the cooling liquid.
• this curved edge in axial section of the separator makes it possible to minimize energy losses in the flow of the coolant, which improves the acceleration of this liquid as it passes between the curved edge of the separator and the conical central zone. of the inner surface of the third end wall, before its arrival in the heat exchange space.
• This first acceleration is regulated by the passage section of the coolant between the edge of the separator and the central depression.
• H1 is the height minimum of the water passage along the inner surface of the third end wall, in the heat exchange space.
• passage section is meant, according to the present invention, a section taken perpendicularly to the direction of flow of the coolant.
• the positioning of the separator relative to the third end wall makes it possible to form a heat exchange space having a predetermined height which regulates the acceleration of the coolant.
• the separator according to the present invention is substantially flat and substantially parallel to the third end wall thus ensuring a flow of the coolant with reduced turbulence and cavitation phenomenon.
• the lance nose according to the present invention thus makes it possible both to optimize the path of the coolant, which minimizes turbulence, and to improve the acceleration of this liquid to effectively cool the wall exposed to thermal stresses. Therefore, the life of the lance nose according to the present invention is greatly increased and the erosion of the outlet edges of the injectors is minimized so that the reaction efficiency in the bath is improved and maintained stable throughout. the life span of the spearhead. In fact, good cooling makes it possible to reduce the erosion of the outlet edges for the stirring gas, which makes it possible to obtain more coherent jets at the outlet of the injectors. These more consistent jets penetrate deeper into the melt and provide better mixing thereof, thus ensuring an improved reaction performance in the bath.
• the gases and dust emitted on the surface of the bath and rising towards the lance nose have less impact on the degradation of the nose when the cooling thereof is improved, as for the nose of the nose. present invention. As a result, the life of the nose according to the present invention is increased.
• the lance nose according to the present invention has a predetermined outside diameter Dext and said edge of the separator is defined by a thickness e1 so that the ratio e1 / D ex t is between 3% and 30%, preferably between 4% and 25%, advantageously between 5% and 20%, preferably between 5% and 15%.
• the thickness, e1 of the edge of the separator is the distance, taken parallel to the axis of revolution of the injectors, between the surface facing the first end wall and the surface facing the bath of the separator.
• This particular thickness of the edge of the separator allows on the one hand to further improve the rotation of the coolant around the edge of the separator which faces the central depression.
• the particular thickness of the edge of the separator advantageously reduces the energy losses during the flow of the coolant. The reduction of energy losses leads in turn to the maintenance of the acceleration of the liquid and thus to the optimization of the cooling of the nose.
• the separator of the lance nose has a surface, facing the bath, substantially sinusoidal.
• sinusoidal surface is meant a surface which forms a wavy curve, that is to say which has for example a convex part between two concave parts.
• the separator having a sinusoidal surface therefore has a convex portion between two concave portions with respect to the third end wall. A minimum thickness is therefore located between two maximum thicknesses of the separator.
• This sinusoidal surface has the advantage of offering the coolant a passage section in the improved heat exchange space. Indeed, as mentioned above, a first Coolant acceleration occurs before entering the heat exchange space.
• the sinusoidal surface of the separator results in increasing the flow section for the coolant substantially in the center of the separator. Indeed, the injectors that pass through the separator substantially in its center, encumber the heat exchange space. This is where the separator is made concave (has a bulge inwards) to leave room for the passage of coolant.
• the sinusoidal shape of the surface facing the bath of the separator thus makes it possible to reduce the energy losses during the second bypass of the injectors between the separator and the internal surface of the third end wall. This sinusoidal surface is advantageous for the good cooling of the wall exposed to the molten iron bath.
• said surface facing the substantially sinusoidal bath of said separator is such that the heat exchange space has a maximum height substantially in the center of said separator.
• the lance nose according to the invention has a pillar comprising a first end located opposite the bath and a second end facing the bath connected to the central zone of the third end wall.
• This pillar on the one hand improves the flow of coolant when it dives into the central opening.
• the central opening may be a collision site and the pillar present in the center of this central opening allows, therefore, minimize turbulence.
• the liquid will then go along the pillar before arriving in the heat exchange space.
• this pillar advantageously consists of a material of good thermal conductivity, such as copper, ensures a good transfer of calories accumulated in the front wall exposed to the bath to the coolant. This phenomenon of calorie transfer is called "cold well". The heat transferred by the pillar then diffuses to the coolant circulating around it.
• the pillar has between said first and second ends a thinned portion connected to the central zone which has a predetermined length L1 and an axial section decreasing continuously towards the central zone so that the pillar forms with the central zone. from the inner surface of the third end wall a continuous curved surface.
• continuous curved surface means a surface which has a “continuity of curves”, preferably a “continuity of tangents”.
• discontinuity of tangents is meant, according to the present invention, that, in an axial section of the pillar, the curve of the thinned portion of the pillar and the curve of the central conical zone of the inner surface of the third front wall have equal tangents at their common end, that is to say at their junction (second end of the pillar).
• the tangents are the first derivatives of the curves at their common end.
• a second degree of “continuity of curves” may possibly be a “continuity of curvature”, which means that the radii of curvature of the two curves (thinned portion of the pillar and the conical central zone of the inner surface of the third wall frontal) are equal at their common end, that is to say at their junction (second end of the pillar).
• the curves of the thinned portion of the pillar and the conical central zone of the inner surface of the third end wall have the same direction at their junction and also have the same radius at this point.
• the radii of curvature are the second derivatives of the curves at their common end, that is to say at their junction at the second end of the pillar.
• the coolant coming from the peripheral part of the nose converges in the central opening where it rotates about 80 ° between the pillar and the edge of the separator before arriving in the exchange space thermal, for example frontal.
• This pillar having a particular geometry makes it possible, on the one hand, to further optimize the flow of the cooling liquid passing through the central opening where it passes between the thinned portion of the pillar and the edge of the separator and other part of accelerating the coolant before its arrival in the heat exchange space.
• the edge of the separator according to the present invention has a complementary shape with the thinned portion of the central pillar advantageously present in the center of the central opening.
• This complementary form between these two elements is particularly advantageous for accompanying the cooling liquid during its rotation of about 180 ° in the central opening thus reducing the turbulence in the liquid, the "tranquilize", and to maintain a good contact with the pillar serving as “cold well” and then with the third front wall. Furthermore, this geometry also allows the acceleration of the coolant before it passes through the heat exchange space.
• the pillar has a second portion of predetermined length L2 joining said thinned portion and said first end, said second portion having a circular cross section defined by a predetermined diameter D2, constant over the entire length.
• length L2 such that the ratio D2 / D ex t is between 2% and 30%, advantageously between 7.5% and 17.5%, preferably between 10% and 15% of said outer diameter (D ex t) of spear nose.
• the pillar can be considered “massive" in view of the volume it occupies in the nose.
• This massive pillar made of a material of good thermal conductivity, such as the copper, ensures a good transfer of calories accumulated in the front wall exposed to the bath to the coolant, thus improving the phenomenon of "cold well".
• the heat transferred by the pillar then diffuses to the coolant circulating around it and the metal / liquid heat exchange surface is increased by the thinned portion having a curved profile.
• the heat is, therefore, better distributed within the lance nose which ensures more particularly a good cooling of the area most exposed to extreme temperatures, namely the center of the third end wall.
• the lance nose according to this embodiment therefore results in further improvement of nose cooling.
• said thinned portion I of the pillar has a predetermined minimum diameter D3 at its second end and said central zone has a height h and a base b such that the ratio h / (b-D3) is between 20% and 120%, preferably between 20% and 110%, advantageously between 30% and 110%, preferably between 30% and 100%, in particular between 40% and 100%, particularly advantageously between 40% and 90%, preferably between 45% and 85%, advantageously between 50% and 80%.
• the heat exchange surface is thus increased with respect to the same surface of the heat front coming from the bath, and this without causing swirling or cavitation in the liquid.
• the passage section of the liquid in the heat exchange space is such that the coolant has a suitable speed profile so that the cooling of the front wall exposed to the bath is further improved.
• the lance nose according to the present invention is characterized by a distance R, for the passage of the cooling liquid, taken perpendicular to the longitudinal axis L of the nose in the central opening.
• this passage distance is then called Ri and is measured between the front of the separator and the longitudinal axis of the nose, and therefore corresponds to the minimum radius of the central opening.
• the passage distance R for the liquid is then measured between the front of the separator and the outer surface of the thinned portion i of the pillar, the distance is then called i3 ⁇ 4.
• this passage distance R is such that the ratio R / H3 is between 20% and 150%, preferably between 30% and 140%, advantageously between 30% and 130%, preferably between 40% and 130%, particularly advantageously between 50% and 130%, preferably between 60% and 120%, advantageously between 60% and 1%, of reference between 70% and 1%, with R corresponding to R 1 in the absence of a pillar or corresponding to R2 in the presence of a pillar.
• This particular passage distance for the coolant further improves the flow of coolant which will converge in the central opening before reaching the heat exchange space.
• the passage distance of the liquid in the central opening in combination with the aforementioned nose characteristics, further improves the flow by improving the reduction of disturbances and the acceleration of the coolant.
• said separator has a surface facing said first substantially sinusoidal front wall.
• a deflector is present substantially in the center of said central tube for supplying the mixing gas of the lance nose according to the present invention.
• This deflector makes it possible to appropriately divert the gas leaving the central duct to engage in the outlet ducts for the stirring gas.
• said outlet ducts for the gas of stirring have axes of revolution placed obliquely to a longitudinal axis of the lance nose.
• the aforesaid elements of the nose are made separately and fixed in a zone of mutual attachment by high-energy welding, preferably electron beam welding.
• the aforementioned nose is made of several nose elements each consisting of a material chosen according to the function to be filled. These elements are then fixed together by high-energy welding, preferably by electron beam. This type of welding ensures copper-steel junctions easily achievable and having a good liquid tightness and this despite fatigue constraints due to successive thermal cycles to which the nose is subjected.
• Figure 1 is a front view of a lance nose.
• FIG. 2 illustrates a sectional view along line II-II of FIG.
• Figure 1 a particular embodiment of the lance nose according to the invention.
• Figure 3 shows a detail of a lance nose according to the invention, to illustrate the characterizing part of the invention.
• FIG. 4 represents a view similar to FIG. 2 of a variant of a blowing nozzle nose according to the invention.
• FIG. 5 represents a detail of a lance nose according to the invention, to illustrate the measurement mode of the parameters necessary for an advantageous embodiment of the invention.
• FIG. 1 illustrates the third end wall 12 of the lance nose 1 which faces the bath.
• the lance nose 1 has six brewing gas outlet ports 13 arranged in a ring around a central zone 14 of the third end wall 12.
• FIG. 2 represents the lance nose according to the present invention. in which the stirring gas is fed by the central tube 2.
• This central tube 2 is closed by a front wall 3 directed towards the bath provided with at least two openings 4.
• An inner tube 5 is arranged coaxially around the central tube 2 so as to form between them an annular cavity 6 for supplying cooling liquid in the direction of the arrow Fi.
• This inner tube 5 is terminated 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.
• the separator 7, according to the present invention, has a geometry and an arrangement with respect to the third particular front wall 12 which will be developed below.
• An outer tube 10 is arranged coaxially around the inner tube 5.
• This outer tube forms with the inner tube 5 an annular cavity 11 which serves for the outlet of the coolant in the direction of the arrow F ?.
• This outer tube is closed by a front wall 12 which faces the bath to be stirred and which has an inner surface 30.
• the inner surface 30 of the third end wall 12 is provided with a central zone 14. conical which is directed towards the central opening 8 and which has a curved envelope surface in axial section.
• the front wall 12 is also provided with an outlet orifice 13 in alignment with each opening 4 provided in the front wall 3 and with each passage opening 9 provided in the front wall 7.
• an outlet duct 17 for the ejection of mixing gas outside the lance nose.
• the axes of revolution m of the ducts 17 are advantageously placed obliquely to the longitudinal axis L of the lance nose.
• this front wall 12 is ensured by the circulation of the cooling liquid in the heat exchange space 16 which is located between the separator 7 and the inner surface 30 of the front wall 12.
• the coolant coming from the cavity 6 passes through the central opening 8 in the heat exchange zone 16 along the arrow F 3 .
• the liquid then flows in the direction of the arrow F 2 outwards, that is to say towards the cavity 11.
• the separator 7, is substantially plane and substantially parallel to the inner surface 30 of the third end wall 12.
• This separator 7 has, at the central opening 8, an edge 18 of curved axial section. .
• a minimum diameter of the central opening 8 can then be measured from the front 19 of the edge 18 of the separator 7.
• the tangent passing through this front 19 and parallel to the longitudinal axis L of the lance nose makes it possible to measure the diameter the smallest of the central opening 8.
• the height taken along the tangent passing through the front 19 and parallel to the longitudinal axis L of the lance nose and measured between said front 19 and the inner surface 30 of the third end wall 12 corresponds to the height H3, such that 'shown in Figure 3.
• the height H1 is itself measured "parallel to the axis of rotation m of the injectors 1, between the surface facing the bath 20 of the separator 7 and the inner surface 30 of the third end wall 12 on the side of the central opening 8.
• This height H1 defines a minimum passage height for the coolant in the heat exchange space 16 at the central opening 8.
• H1 is the minimum height of the water passage along the inner surface of the third end wall, in the space heat exchange.
• the ratio H1 / H3 is advantageously between 30% and 55%.
• the curved axial section of the edge 18 of the separator 7 has the advantage of accompanying the cooling liquid during its convergence in the central opening 8.
• the liquid is kept in contact with the inner surface of the third end wall 12 the most exposed to thermal stresses. Therefore, a disturbance coolant flow and reduced cavitation phenomena can be obtained and maintained throughout its trajectory.
• the coolant thus "tranquilized” can then calmly bypass the obstacles represented by the injectors 17 in the heat exchange space 16 before emerging from the nose by the second annular cavity 11 along the arrow F 2 .
• the outer diameter D ext of the lance nose 1 according to the present invention corresponds to the diameter measured between the outer surfaces of the outer tube 10, as shown in FIG. 2.
• a thickness of the separator 7 is measured between the surface 21 facing the first end wall 3 and the surface facing the bath 20 of the separator 7.
• the thickness e1 of the edge 18 of the separator 7 is thus measured parallel to the axis of revolution m of the injector 17 in the continuity of the minimum height H1 of the heat exchange space 16 at the central opening 8.
• This thickness allows the separator to occupy a substantial volume in the lance nose and allows in combination with the curved section of the edge 18 to maintain a reduced disturbance flow and a good acceleration of the coolant.
• the ratio e1 / D ext is between 5% and 15%,
• the bath-facing surface 20 of the separator 7 is substantially sinusoidal.
• the maximum thickness, e1 is measured between the surface 21 facing the first end wall 3 and the tangent passing through the minimum of the part concave surface facing the bath 20.
• a minimum thickness is measured between the surface 21 facing the first end wall 3 and the tangent passing through the maximum of the convex portion of the surface facing the bath 20,
• the separator 7 has in addition to its thickness e1 at the central opening 8, a minimum thickness substantially at its center such that the heat exchange space 16 has a maximum height Hmax substantially in the center of the separator 7.
• This maximum height H max is intended to leave more space for the coolant during its passage at the injectors 17 in the heat exchange space 16.
• Figure 4 shows a particular embodiment of the lance nose according to the present invention.
• a central pillar 22 of particular configuration is present in the center of the central opening 8.
• the pillar 22 has a first end E1 on the side of the first end wall 3 and a second end E2 connected to the central zone 14 of the inner surface 30 of the third end wall 12.
• This pillar preferably has a thinned portion I between the first end E1 and the second end E2 which makes it possible to form a continuous curved surface 23 with the conical central zone 14 of the inner surface 30 of the third end wall 12. In this way, the coolant coming from the first cavity ring 6 along the arrow Fi, along the upper face 21 of the separator 7 where it must bypass the injectors which represent a first obstacle in the path of the liquid and then converges in the central opening 8.
• the pillar 22 present in the center of this central opening 8 then guides the cooling liquid to the inner surface 30 of the third end wall 12 where the thinned portion I of the pillar provides the passage of the liquid between this pillar 22 and the edge 18 of the separator 7, along the arrow F 3 .
• the junction of the conical central zone 14 of the inner surface 30 of the third end wall 12 with the pillar 22 has a continuous curved surface 23 ensuring a progressive rotation of the liquid along the arrow F 3 .
• the turbulence in the coolant then arriving in the heat exchange space 16 is reduced and the liquid can quietly bypass the injectors occupying a large volume in the heat exchange space 18.
• the calories accumulated in the front wall 12 exposed to the bath of liquid iron are transferred to the pillar 22, the contact surface with the cooling liquid is increased thanks to its thinned portion I, which improves the heat transfer metal / liquid
• the pillar 22 advantageously has a second portion II of predetermined length L2 joining said thinned portion I and said first end E1, said second portion II having a circular cross section defined by a predetermined diameter D2, constant over the entire length L2 , such that the ratio D 2 / D ex t is advantageously between 10% and 15%.
• the pillar 22 being made of a material of good thermal conductivity, the heat from the bath and transmitted to the third end wall 12 and its central zone 14 where it can then be driven by the pillar 22 to the coolant .
• the latter circulating around the pillar 22 ensures a constant capture of the heat of the third end wall 12.
• the parts most exposed to the bath namely the third front wall 12 and the pillar 22, are made of wrought copper which provides better thermal conductivity than cast copper.
• the first thinned portion I is further characterized by a predetermined diameter D1 which varies progressively from the diameter D2 at the junction with the second portion 11 to a value preferably between 60% and 80% from D2 to the second E2 end of the pillar 22.
• the diameter D1 of the thinned portion I of the pillar 22 therefore decreases progressively as one moves along the longitudinal axis L of the lance nose to the bath until reaching a minimum value, then called D3 corresponding to the second end E2 of the pillar.
• the continuous curved surface 23 between the thinned portion I of the pillar 22 and the central conical zone 14 of the inner surface 30 of the third end wall 12 is characterized by a radius of curvature greater than or equal to 30% of the diameter D2 of second part II of pillar 22.
• the separator 7 and the thinned portion I of the abutment 22 facing each other have a complementarity of shape thus ensuring a most delicate accompaniment of the coolant possible.
• the edge 18 of the separator 7 and the thinned portion I of the pillar 22 can form for the coolant a trajectory decreasing turbulence in the liquid.
• a deflector 24 may also be placed in the center of the mixing gas supply tube 2. This deflector 24 makes it possible to appropriately divert the oxygen leaving the central pipe 2 to engage the injectors 17.
• FIG. 5 represents a detail of the conical central zone 14 in order to explain how to measure the parameters relating to this central zone 14 of the inner surface 30 of the third front wall 12.
• the height h is measured between the tangent plane 32 the inner wall 30 of the lance nose perpendicular to the longitudinal axis L and the parallel plane 31 tangential to the top of the central conical zone 14. If an additional element to the conical central zone 14 is provided at the top thereof, like example the pillar 22, the plane 31 remains in the position it would have if this additional element did not exist.
• the top of the conical central zone 14 coinciding with the cross section of the thinned portion i of the pillar 18 having a minimum diameter D3, the plane 31 also passes through this minimum diameter section D3 of the pillar 22.
• the base b is located in the tangent plane 32 of the inner wall 30. It is circumscribed by the points of intersection 33 with the extension of the inner wall 30.
• the nose according to the present invention has a ratio h / (b-D3) of between 50% and 80%. Therefore, in the case where no additional element, such as for example a pillar, is present on the central zone 14, D3 is impaired and the h / b ratio is preferably between 50% and 80%.
• FIG. 5 also shows the distance R for the passage of the coolant taken perpendicular to the longitudinal axis L of the nose in the central opening 8.
• the distance R is measured between the front 19 of the separator 7 and the longitudinal axis L, this distance for the passage of the coolant is then called Ri and corresponds to the minimum radius of the central opening 8.
• Ri corresponds to the minimum radius of the central opening 8.
• the passage distance R for the liquid is then measured between the separator front 7 and the outer surface of the thinned portion I of the pillar 22, the distance is then called R 2 .
• this distance for the passage of the cooling liquid is such that the ratio R / H3 is preferably between 70% and 110%, with R corresponding to R1 in the absence of a pillar or corresponding to R2 in the presence of a pillar.

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• 2016
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