JP5440321B2 - Immersion lance for blowing oxygen gas - Google Patents

Description

  The present invention relates to a double tube structure oxygen gas blowing method in which an inner tube and an outer tube are concentrically used in a hot metal pretreatment such as a desiliconization process or a dephosphorization process performed by blowing an oxygen-containing gas into the hot metal. It relates to a dipping lance for use.

  In recent years, dephosphorization of hot metal has been widely performed in converters, kneading cars (also called “topped cars”), hot metal ladles, etc., for the purpose of measures to reduce the phosphorus content accompanying the upgrading of steel materials or rationalize the steel making process. ing. Moreover, in order to perform this dephosphorization process efficiently, the desiliconization process which removes the silicon in a hot metal beforehand is also performed before the dephosphorization process. Since phosphorus and silicon in the hot metal are removed by an oxidation reaction, the dephosphorization process and desiliconization process of the hot metal supply oxygen source such as oxygen gas or iron oxide to the hot metal, and phosphorus or silicon in the hot metal is supplied by the oxygen source. Is removed by oxidation. At that time, a medium solvent such as quick lime is also added to increase the reaction efficiency or adjust the composition of the slag to be generated.

  There are two methods for supplying oxygen gas to the hot metal: a method in which oxygen gas is blown toward the hot metal bath surface from a non-contact upper blowing lance (top blowing acid method), a lance immersed in the hot metal, From the tuyere provided at the bottom of the reaction vessel, it is classified into two types: a method in which oxygen gas is directly blown into the molten iron (blowing and feeding acid method), and these have their respective characteristics. In the top blowing acid method, the reaction efficiency is not good, and the blowing acid method is adopted. This is because, in the case of a kneading vehicle, the container shape is difficult to stir and mix, and in addition to that, there are few openings with respect to the amount of hot metal accommodated, and the desired efficiency of reaction cannot be obtained by the top blowing acid method. It is.

  The immersion lance used in the blown acid feeding method is generally composed of a lance body immersed in the hot metal and a lance holder that holds the lance body. Although the refractory coating layer is applied to the immersion part, since the refractory is melted severely, the operation is performed while replacing the lance body in which the immersion part is damaged. Replacing the lance body is an online operation, and it takes a long time to replace the lance, which leads to a decrease in productivity. Therefore, various means have been proposed to quickly replace the lance body. .

  For example, in Patent Document 1, the lower end portion of the lance holder is formed on a male tapered surface that is reduced in diameter downward, a sealing O-ring is disposed on the tapered surface, and the upper end portion of the lance body is increased in diameter upward. It has been proposed to form a dipping lance by forming a female taper surface and pressing the female taper surface and the male taper surface with a force of a cylinder or the like. According to Patent Document 1, the lance body can be exchanged easily and with a reliable seal of the connecting portion.

  Patent Document 2 discloses an immersion lance in which an upper end portion of a lance main body is attached to and detached from a lance holder via a screw. According to Patent Document 2, with the lance body held rotatably via a plurality of support rollers, the tip of the lance body is brought into contact with the lance holder, and the lance body is rotated forward or backward. As a result, the lance body and the lance holder can be attached and detached, and mechanization and automation of the connection work between the lance body and the lance holder are achieved.

  By the way, in recent years, in order to prevent the refractory from melting at the tip of the lance body (gas discharge section) due to the heat generated by blowing oxygen gas, the lance body has a double-tube structure consisting of an inner tube and an outer tube, At the same time that oxygen-containing gas is blown from the inner pipe, a hydrocarbon gas is blown from the gap between the inner pipe and the outer pipe, and the lance body is cooled by utilizing the endotherm of the decomposition reaction of the hydrocarbon gas. (For example, refer to Patent Document 3).

  If the lance body has a double tube structure, not only will the mass of the core metal increase, but the body diameter will also increase, so the mass of the refractory covering the core metal will also increase, and the mass of the lance body will increase significantly. . When such a lance body with increased mass is supported on the lance holder by the method disclosed in Patent Document 1 and Patent Document 2, the following problems may occur.

  That is, when oxygen gas is blown into the hot metal, the lance body vibrates vigorously, and when the lance body and the lance holder are pressure-bonded as in Patent Document 1, the acceleration of vibration increases as the mass increases. This acceleration may cause the pressure-bonding surface to leave.

  Further, the lance body used in a chaotic vehicle has many shapes having a bent portion at the tip, that is, the center of gravity of the lance body does not coincide with the center of the core metal. In order to rotate the mandrel around the core, naturally it is not possible with human power, and since heavy objects are joined via screws, the thread, especially the thread on the lance holder side, should not be deformed. For this purpose, it is necessary to accurately align the center of the lance body and the lance holder, which increases the work time.

JP-A-8-295918 JP-A-10-195522 JP 58-22212 A

  The present invention has been made in view of the above circumstances. The object of the present invention is to immerse an oxygen-containing gas from the inner pipe and a hydrocarbon gas from the gap between the inner pipe and the outer pipe. In an immersion lance for oxygen gas injection consisting of a lance body with a double-pipe structure for blowing into hot metal and a lance holder that holds the lance body, accurate alignment of the lance body and lance holder is required. The connection between the lance body and the lance holder is strong and does not separate during operation. Furthermore, even if there is a thermal load due to scattering of hot metal, etc. It is an object of the present invention to provide an immersion lance for blowing an oxygen gas that can withstand the above.

  An immersion lance for injecting oxygen gas according to the present invention for solving the above-mentioned problems has concentric inner and outer tubes, oxygen-containing gas from the inner tube, and hydrocarbons from the gap between the inner tube and outer tube. In the immersion lance for injecting oxygen gas composed of a lance body having a double-pipe structure for injecting gas into the hot metal and a lance holder for holding the lance body, the lower end portion of the lance holder has An internal thread is formed, an adapter having an external thread to be attached to and detached from the internal thread is joined to the lower end of the lance holder via the screw, and a flange is provided on each of the lower end of the adapter and the upper end of the lance body, The lance body is fixed to the lance holder by bolts passing through the flanges and nuts for fixing the bolts, and each bolt arranged on the flange is fixed to the lance. It is configured to be cooled by a water spray installed on the rudder side, and hydrocarbon gas is supplied to the lance body below the flange and into the gap between the inner tube and the outer tube. For this purpose, a hydrocarbon gas introduction pipe communicating with the gap between the inner pipe and the outer pipe is installed, and the gap between the inner pipe and the outer pipe is sealed at the upper end of the lance body, and the upper end of the lance body is Only the inner pipe is opened, and the oxygen-containing gas supplied through the inside of the lance holder is configured to flow into the inner pipe.

  According to the present invention, since the lance body and the lance holder are connected by a flange structure using bolts and nuts, the lance body and the lance holder can be firmly connected without requiring accurate alignment, and Since the bolt is forcibly cooled by sprinkling of cooling water, thermal deformation of the flange portion and the bolt is prevented and seizure between the bolt and the nut is prevented, so that the lance body can be smoothly exchanged. Also, if the bolts and nuts cannot be separated due to welding of the molten iron due to the splashing hot metal, the adapter joined to the lower end of the lance holder via a screw must be disconnected from the lance holder. Even in such a situation, the lance body can be replaced smoothly.

It is the schematic which shows the condition which implements the hot metal pre-processing using the immersion lance for oxygen gas blowing which concerns on this invention. It is a schematic sectional drawing which shows the connection structure of the lance main body and lance holder in the immersion lance for oxygen gas blowing which concerns on this invention.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic view showing a state in which hot metal pretreatment is performed using the immersion lance for blowing oxygen gas according to the present invention, and FIG. 2 is a lance in the immersion lance for blowing oxygen gas according to the present invention. It is a schematic sectional drawing which shows the connection structure of a main body and a lance holder.

  First, the overall configuration of an immersion lance 1 for blowing oxygen gas according to the present invention will be described with reference to FIG. As shown in FIG. 1, a rotating shaft 7 is provided at the end of a lance traveling carriage 4 that travels on a rail (not shown) installed on the work floor 9, and the tilting frame 5 is provided via the rotating shaft 7. However, the tilting hydraulic cylinder 6 is disposed so as to be tiltable, and the lance lifting carriage 8 is attached to the tilting frame 5. The lance elevating carriage 8 is configured such that the tilting frame 5 can be raised and lowered from the upper end to the lower end by an appropriate means such as a combination of an electric motor and a chain and can be stopped at an arbitrary position.

  A cylindrical lance holder 3 having an oxygen-containing gas flow path is fixed to the lance lifting carriage 8, and a lance body 2 is attached to the lower end of the lance holder 3. The lance holder 3 constitutes an immersion lance 1 for blowing oxygen gas. The lower portion of the lance body 2 is immersed in the hot metal 11 and oxygen gas is blown into the hot metal from the tip of the lance body 2 at the same time as hydrocarbon gas is blown. A refractory coating layer 29 is applied to the surface of the lance body 2.

  The upper end of the lance holder 3 is connected to an oxygen-containing gas supply flexible pipe 13, and a cooling water introduction pipe 27 connected to the cooling water supply flexible pipe 15 is fixedly attached to the lance holder 3. It has been. Further, a hydrocarbon gas introduction pipe 26 connected to the hydrocarbon gas supply flexible pipe 14 is attached to the upper side of the lance body 2.

  Next, a connection structure between the lance body 2 and the lance holder 3 will be described with reference to FIG. As shown in FIG. 2, a tapered female screw 3a that expands downward is formed at the lower end of the cylindrical or single-tube lance holder 3, and the diameter of the female screw 3a is reduced upward. A cylindrical adapter 16 having a tapered male screw 16a is joined to the lower end of the lance holder 3 via a screw. A flange 17 is formed at the lower end of the adapter 16.

  On the other hand, the lance body 2 has a double tube structure of a concentric inner tube 19 and an outer tube 20, and an inner tube 19 and an outer tube 20 are provided on the outer peripheral side of the outer tube 20 at the upper end of the lance body 2. A cylindrical support member 18 for supporting is disposed, and a flange 21 is formed at an upper end portion of the cylindrical support member 18. In the gap between the inner tube 19 and the outer tube 20, a distance piece for making the interval constant is installed at an appropriate position, but is omitted in FIG.

  In the circumferential direction of the flange 17 provided on the adapter 16 and the flange 21 provided on the cylindrical support member 18, a plurality of holes (nine in FIG. 2) for passing the bolts 22 are provided at equal intervals. Bolts 22 are inserted into the respective holes, and the flange 17 and the flange 21 are brought into close contact with each other by the bolts 22 and the nuts 23 fitted to the bolts 22, whereby the lance body 2 is connected to the lower end portion of the lance holder 3. It is configured as follows. It is also possible to provide a circumferential groove on the joint surface of the flange 17 or the flange 21 and arrange an O-ring for sealing in this groove.

  The cylindrical support member 18 and the outer surface of the inner tube 19 are joined by the fixing member 24 in a state in which the airtightness of the joining surface with the fixing member 24 is ensured, and the upper end portion of the outer tube 20 is It is joined to the fixing member 24 in a state in which the airtightness of the joint surface with the fixing member 24 is ensured. That is, the gap between the inner tube 19 and the outer tube 20 is sealed at the upper end portion of the lance body 2, and only the inner tube 19 is opened at the upper end portion of the lance body 2, passing through the internal flow path of the lance holder 3. The supplied oxygen-containing gas is configured to flow into the inner pipe 19 through the adapter 16.

  That is, the oxygen-containing gas introduced from the oxygen-containing gas supply flexible pipe 13 into the internal flow path of the cylindrical lance holder 3 passes through the internal flow path of the lance holder 3 and enters the inner pipe 19 of the lance body 2. It is supplied and passes through the inner tube 19 of the lance body 2 and is blown into the hot metal from the inner tube 19 at the lower end of the lance body 2.

  In the lance body 2, a hydrocarbon gas introduction pipe 26 that passes through the cylindrical support member 18 and communicates with the gap between the inner pipe 19 and the outer pipe 20 is installed below the flange 21. The other end of the hydrocarbon gas introduction pipe 26 is connected to the hydrocarbon gas supply flexible pipe 14 by a pipe detachment coupling or the like, and the hydrocarbon gas supplied from the hydrocarbon gas supply flexible pipe 14 is It is introduced into the gap between the inner pipe 19 and the outer pipe 20 via the hydrocarbon gas introduction pipe 26, passes through the gap between the inner pipe 19 and the outer pipe 20 of the lance body 2, and the inner pipe 19 at the tip of the lance body 2. And the outer pipe 20 are configured to be blown into the hot metal.

  A cooling water introduction pipe 27 is fixedly attached to the lance holder 3, and the cooling water introduction pipe 27 is connected to an annular cooling water header pipe 28 arranged around the lance holder 3, so that the cooling water header The pipes 28 are provided with water sprays 25 for spraying cooling water toward the nut mounting side of each bolt 22. The other end of the cooling water introduction pipe 27 is connected to the cooling water supply flexible pipe 15 by a pipe detachment coupling or the like, and the cooling water supplied from the cooling water supply flexible pipe 15 is the cooling water introduction pipe 27. In addition, water is sprayed from the water spray 25 toward the nut mounting side of each bolt 22 via the cooling water header pipe 28.

  Thus, the immersion lance 1 according to the present invention is configured. Using this immersion lance 1, a hot metal pretreatment, that is, a desiliconization treatment and a dephosphorization treatment is performed as follows. The hot metal desiliconization treatment and dephosphorization treatment are both refining performed by blowing oxygen-containing gas such as oxygen gas into the hot metal, and the desiliconization treatment mainly removes silicon (Si) in the hot metal by oxidation. The purpose of dephosphorization is to remove phosphorus (P) in the hot metal by oxidation. However, silicon has a stronger affinity for oxygen than phosphorus, and dephosphorization without desiliconization. In the case of carrying out, desiliconization reaction first occurs, and after the silicon concentration in the hot metal is lowered to some extent, dephosphorization reaction occurs. In this case, it should be called desiliconization / dephosphorization treatment, but it is defined as dephosphorization treatment in the present invention.

  Thus, since the desiliconization process and the dephosphorization process are the same processing method, here, the dephosphorization process is demonstrated with reference to FIG. However, quick lime is added as a solvent in both the dephosphorization treatment and the desiliconization treatment. The quick lime plays a role in absorbing the phosphorous oxide produced in the dephosphorization treatment, whereas the slag base produced in the desiliconization treatment. It plays a role of adjusting the degree, and in the dephosphorization process, the addition of quick lime is essential, but in the desiliconization process, the addition of quick lime is not essential, and there is a slight difference between them.

  The lance lifting carriage 8 is positioned at the end opposite to the rotating shaft 7 and the lance body 2 is lifted by a crane (not shown) or the like while the tilting frame 5 is kept horizontal or at an appropriate inclination angle. The upper end portion is positioned immediately below the lower end portion of the lance holder 3, the flange 17 and the flange 21 are brought into close contact with each other, and the flange 17 and the flange 21 are connected by the bolt 22 and the nut 23. In this way, the lance body 2 is attached to the lance holder 3 in advance.

  The kneading vehicle 10 containing the molten iron 11 is positioned directly under the dust collection hood 12 and the work floor 9, and the lance traveling cart 4 and the tilting frame 5 are installed at appropriate positions, and the cooling water is sprayed from the water spray 25. At the same time, while the oxygen-containing gas is blown from the inner pipe 19 and the hydrocarbon gas is blown from the gap between the inner pipe 19 and the outer pipe 20, the lance lifting carriage 8 is lowered to immerse the lance body 2 in the hot metal. As the oxygen-containing gas, oxygen gas, a mixed gas of oxygen gas and inert gas, air, or the like is used, and as the hydrocarbon gas, propane gas, methane gas, butane gas, or the like is used.

  In this case, a solid oxygen source such as powdered iron ore can be supplied from the inner pipe 19 as a carrier gas, and powdery lime is supplied from the inner pipe 19 as oxygen-containing gas. It is also possible to blow in as a carrier gas.

  The oxygen gas in the blown oxygen-containing gas reacts with phosphorus in the hot metal to oxidize phosphorus as a phosphorus oxide. The produced phosphorous oxide is absorbed in the slag by reacting with at least one of quick lime blown from the inner pipe 19, quick lime added to the kneading car from the furnace port, or quick lime blown and added from another immersion lance, The dephosphorization reaction proceeds. The injected hydrocarbon gas decomposes and absorbs heat, and suppresses melting of the tip of the lance body 2.

  If the phosphorus concentration in the hot metal is reduced to the target value, the lance lifting carriage 8 is raised, the lance body 2 is lifted from the hot metal 11, the supply of oxygen-containing gas and hydrocarbon gas is stopped, and dephosphorization processing is performed. finish. The water spray from the water spray 25 is continued until a predetermined time elapses by a timer or the like. The kneading wheel 10 containing the molten iron 11 subjected to the dephosphorization process is dispensed, and another kneading wheel 10 accommodating the molten iron 11 which has not been subjected to the dephosphorizing process is prepared immediately below the work floor 9. Repeat the phosphorus treatment.

  When the refractory coating layer 29 of the lance body 2 is melted and cannot be used due to repeated dephosphorization, the lance body 2 is used in the reverse process of attaching the lance body 2 to the lance holder 3 The lance body 2 is removed and a new lance body 2 is newly attached. When the used lance body 2 is removed, if the bolt 22 and the nut 23 are welded and the flange 17 and the flange 21 cannot be separated, the adapter 16 is rotated, and the adapter 16 and the lance holder 3 are moved. Separate and attach another adapter 16 to the lance holder 3 to replace the lance.

  As described above, according to the present invention, since the lance body 2 and the lance holder 3 are connected by the flange structure using the bolts 22 and the nuts 23, the lance body 2 and the lance holder 3 are accurately aligned. The bolts 22 are forcibly cooled by the sprinkling of cooling water, so that the thermal deformation of the flange 17 and the bolts 22 is prevented and the seizure between the bolts 22 and the nuts 23 is prevented. Thus, a smooth exchange of the lance body 2 is realized. Further, when it becomes impossible to separate the flange 17 and the flange 21 for some reason, the adapter 16 can be disconnected from the lance holder 3, and in such a situation, the replacement of the lance body 2 can be smoothly performed. Can be performed.

  In the above description, the lance body 2 has a structure in which an oxygen-containing gas and a hydrocarbon gas are blown from the tip of the lance body 2, but the flow path is divided into two in an inverted T shape near the tip of the lance body 2. It is good also as a structure blowing separately, and it does not have a bending part in the front-end | tip part of the lance main body 2, and it does not matter even if it is linear. Furthermore, in the above description, the immersion lance 1 is immersed obliquely in the vertical direction with respect to the hot metal 11, but it may be immersed in the vertical direction.

DESCRIPTION OF SYMBOLS 1 Immersion lance 2 Lance main body 3 Lance holder 3a Female thread 4 Lance traveling cart 5 Tilt frame 6 Tilt hydraulic cylinder 7 Rotating shaft 8 Lance lift cart 9 Work floor 10 Chaotic wheel 11 Hot metal 12 Dust collection hood 13 Oxygen-containing gas flexible tube DESCRIPTION OF SYMBOLS 14 Hydrocarbon gas supply flexible pipe 15 Cooling water supply flexible pipe 16 Adapter 16a Male thread 17 Flange 18 Cylindrical support member 19 Inner pipe 20 Outer pipe 21 Flange 22 Bolt 23 Nut 24 Fixing member 25 Water spray 26 Hydrocarbon gas introduction pipe 27 Cooling water introduction pipe 28 Cooling water header pipe 29 Refractory coating layer

Claims (1)

A lance body having a double-tube structure having concentric inner and outer pipes, for injecting oxygen-containing gas from the inner pipe and hydrocarbon gas into the molten metal from the gap between the inner pipe and outer pipe, and the lance body In the immersion lance for oxygen gas blowing composed of a lance holder for holding
A female screw is formed at the lower end of the lance holder, and an adapter having a male screw to be attached to and detached from the female screw is joined to the lower end of the lance holder via the screw,
A flange is provided at each of the lower end of the adapter and the upper end of the lance body, and the lance body is fixed to the lance holder by bolts passing through these flanges and nuts for fixing the bolts.
Each bolt arranged on the flange is configured to be cooled by a water spray installed on the lance holder side,
The lance body has a hydrocarbon gas introduction pipe communicating with the gap between the inner pipe and the outer pipe, for supplying hydrocarbon gas to the gap between the inner pipe and the outer pipe, below the flange. The gap between the inner tube and the outer tube is sealed at the upper end of the lance body, and only the inner tube opens at the upper end of the lance body, and oxygen supplied through the interior of the lance holder An immersion lance for injecting oxygen gas, characterized in that the contained gas flows into the inner pipe.

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