JP2014055350A - Method for protecting throat of torpedo car - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit deformation or erosion of an iron shell around a throat of a torpedo car even when subjecting molten iron in the torpedo car to desiliconization treatment and dephosphorization treatment under a high oxygen partial pressure.SOLUTION: A method for protecting a throat of a torpedo car includes supplying a nitrogen gas or an AR gas of normal temperature to the inside of a flow passage 6 contacting an iron shell 3 around the throat of the torpedo car and cooling the iron shell around the throat with the nitrogen gas or the Ar gas passing through the flow passage. In this case, it is preferable that the flow passage is made of a metal pipe in a half-split shape of a circular form and is formed by welding and joining both ends of the metal pipe in a half-split shape to the iron shell, or it is preferable that the flow passage is made of a metal pipe and is formed either by filling a high thermal conductive substance in the space between the metal pipe and the iron shell or by welding and joining the metal pipe and the iron shell.

Description

  The present invention accepts hot metal discharged from a blast furnace and transports the received hot metal to the next process, or carries out a refining process on the received hot metal and then transports it to the next process. About.

  In the iron making process, the hot metal produced in the blast furnace and discharged from the blast furnace is generally received by a kneading car (also referred to as “topped car”) and conveyed to the next steel making process. In the middle of this conveyance, a hot metal preliminary process such as a desiliconization process, a dephosphorization process or a desulfurization process may be performed by blowing a flux or the like into the hot metal in the kneading vehicle.

  Oxygen sources such as oxygen gas and iron oxide are used for desiliconization and dephosphorization. Conventionally, desiliconization and dephosphorization performed in a kneading car have a low oxygen source supply flow rate, and the furnace of a kneading car The heat load around the mouth was not very high. Therefore, as disclosed in Patent Document 1, an arc-shaped rectangular steel plate whose inside of the furnace port is curved in a concave shape is embedded in the refractory at the corner portion of the furnace port, and the furnace core is doubled. With some measures, it was possible to protect the iron shell shape of the furnace opening and the refractory shape of the furnace opening.

  However, in recent years, the operation under high oxygen partial pressure has been aimed at also in the desiliconization process and the dephosphorization process performed in the kneading vehicle. In the operation under a high oxygen partial pressure, the combustion of CO gas around the furnace port becomes intense, the heat load around the furnace port increases, and only the countermeasure disclosed in Patent Document 1 is the iron skin around the furnace port. The deformation and melting damage of the car became severe, and the life of the chaotic car was shortened, resulting in an increase in cost.

  On the other hand, although the heat load is not so high, the durability of the chaotic vehicle is affected by the heat load, so several methods for reducing the heat load have been proposed in the past in order to improve the durability of the chaotic vehicle. .

  For example, Patent Document 2 discloses a furnace in which a refractory furnace port fitting that is formed so that it can be cooled with a cooling medium is detachable or can be moved up and down in a furnace port portion of a molten metal container such as a kneading vehicle. Mouth structure has been proposed. According to Patent Document 2, the furnace opening fitting is damaged by a thermal load, but when the furnace opening fitting is damaged, the durability of the furnace opening is improved by replacing the furnace opening fitting. If so.

  Patent Document 3 proposes a method for forcibly cooling the iron shell of the kneading vehicle during the hot metal pretreatment in order to prevent deformation of the kneading vehicle outer shell due to heat accompanying the hot metal pretreatment.

JP 2001-11518 A Japanese Utility Model Publication No. 3-18157 JP-A-10-265818

  As described above, the hot metal pretreatment under the high oxygen partial pressure in recent years causes severe deformation or melting of the iron shell around the furnace port of the kneading car, shortening the life of the kneading car and increasing the cost. .

  When the methods proposed in Patent Document 2 and Patent Document 3 described above are applied to prevent deformation and melting of the iron shell around the furnace port of the kneading vehicle, the following problems occur.

  In Patent Document 2, the inside of the furnace port fitting is cooled with a cooling medium, but this cooling medium only cools the refractory applied to the furnace port fitting, and the furnace port fitting is cooled by the cooling medium. It is not cooled, and it cannot prevent deformation and melting of the furnace mouthpiece. In addition, as the heat load near the furnace port, the influence of the heat generated when the CO gas generated from the hot metal burns with the air that has entered through the gap between the furnace port and the exhaust gas duct is very large. It is not possible to suppress the deformation of the iron skin simply by surrounding it with the fitting. Also, the opening area of the kneading car furnace opening is narrow, and during the hot metal pretreatment, an injection lance and an upper blowing lance are inserted through this furnace opening, and the furnace opening fitting is attached to the furnace opening. Thus, the opening area of the furnace opening is further narrowed, and there is a possibility that the free insertion of the injection lance and the upper blowing lance may be hindered. Furthermore, there is a possibility that the furnace opening fitting and the furnace opening may be welded due to the splash generated during the pretreatment, and in that case, there is a possibility that the furnace opening may be damaged when the furnace opening fitting is replaced. .

  In Patent Document 3, cooling water is sprayed directly on the iron skin of a kneading vehicle to suppress deformation of the iron skin, and there is a risk that the cooling water is mixed into the molten iron and causes a steam explosion. That is, there is a serious safety problem. Further, since the cooling is too strong and water dripping occurs, it is difficult to control the thermal strain, and there is a possibility that another problem such as the entire deformation of the iron skin into an ellipse may occur.

  The present invention has been made in view of the above circumstances. The purpose of the present invention is to provide iron around the furnace port of a kneading car even if the molten iron in the kneading car is desiliconized or dephosphorized under a high oxygen partial pressure. It is an object of the present invention to provide a method for protecting the furnace port of a chaotic vehicle that can suppress deformation and melting of the skin.

The gist of the present invention for solving the above problems is as follows.
[1] Supply normal temperature nitrogen gas or Ar gas into the flow path in contact with the iron shell around the furnace port of the kneading vehicle, and cool the iron skin around the furnace port with nitrogen gas or Ar gas passing through the flow path A method for protecting a furnace port of a chaotic vehicle characterized by the above.
[2] The flow path is formed of a circular half-cracked metal tube, and both end portions of the half-cracked metal pipe are welded to the iron skin, or the flow path is formed of a metal tube. [1], wherein the metal tube and the iron skin are filled with a high thermal conductivity material, or the metal tube and the iron skin are welded and joined. The method for protecting the furnace port of a chaotic vehicle as described in 1.
[3] Nitrogen gas or Ar gas that has passed through the flow path and cooled the iron skin around the furnace port is blown out from the flow path around the furnace port of the kneading car to suppress secondary combustion of CO gas A method for protecting a furnace opening of a chaotic vehicle according to the above [1] or [2].
[4] The chaotic vehicle according to [3], wherein nitrogen gas or Ar gas is ejected from the flow path toward the furnace port center of the chaotic vehicle at an elevation angle of 45 ° to 90 °. Furnace port protection method.

  According to the present invention, normal temperature nitrogen gas or Ar gas is supplied to the inside of the flow path in contact with the iron skin around the furnace port of the kneading vehicle to forcibly cool the iron skin around the furnace port. Even if the contained hot metal is subjected to a desiliconization process or a dephosphorization process under a high oxygen partial pressure, it is possible to suppress the deformation or melting of the iron shell around the kneading car furnace opening.

It is the schematic which looked at the furnace port part of the kneading vehicle by which this invention was applied and the iron skin around a furnace port was cooled from the upper side of the kneading vehicle. It is the schematic which looked at the furnace port part of the chaotic vehicle shown in FIG. 1 from the side of the chaotic vehicle. It is a schematic sectional drawing by A-A 'arrow of FIG. It is the schematic which has arrange | positioned the protector on the upper side of a half-cracked metal pipe. It is the schematic which shows the example which used the flow path as the metal pipe.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic view (plan view) of a furnace port portion of a kneading vehicle in which the present invention is applied and the iron skin around the furnace port is cooled, as viewed from above the kneading vehicle, and FIG. FIG. 3 is a schematic view (side view) of the furnace port portion viewed from the side of the kneading vehicle, and FIG.

  As shown in FIG. 1, a furnace port 2 is disposed as an opening formed by the refractory 4 at the center in the length direction of the kneading vehicle 1, and a furnace port iron skin 3 is installed around the furnace port 2. Has been. The hot metal discharged from the blast furnace passes through the furnace port 2 and is accommodated in the kneading wheel 1. On the other hand, the molten iron accommodated in the kneading wheel 1 is inclined by tilting the kneading wheel 1 about its longitudinal axis. The hot water is discharged into a holding container such as a ladle through the furnace port 2.

When performing desiliconization treatment or dephosphorization treatment as a preliminary treatment on the hot metal accommodated in the kneading wheel 1, an injection lance immersed in the hot metal via the furnace port 2, or an upper blow lance passing through the furnace port 2 or Oxygen gas or oxygen gas and iron oxide such as iron ore are supplied to the hot metal from the top blowing lance installed immediately above the furnace port 2, and silicon and phosphorus in the hot metal are oxidized and removed with these oxygen sources. . The hot metal contains more than 4% by mass of carbon, and this carbon reacts with the supplied oxygen source, and CO gas is generated in the desiliconization process and the dephosphorization process. The generated CO gas is combusted by the oxygen gas in the atmosphere or the supplied oxygen gas at the furnace port 2 and immediately above it, and becomes CO ₂ gas. This phenomenon of CO gas combustion is called “secondary combustion”. The temperature of the furnace port 2 and its surroundings is increased by the secondary combustion, and if the supply flow rate of the oxygen source is increased by desiliconization and dephosphorization. The higher the partial pressure of oxygen in the reaction atmosphere, the higher the secondary combustion increases and the temperature of the furnace port 2 and its surroundings increases.

  In recent years, in hot metal desiliconization and dephosphorization, it has been directed to increase the supply flow rate of the oxygen source from the viewpoint of productivity improvement. In other words, desiliconization and dephosphorization under high oxygen partial pressure. The refining under high oxygen partial pressure is also directed to the desiliconization process and the dephosphorization process in the kneading vehicle 1. Thereby, the temperature of the furnace port 2 and the furnace port iron shell 3 rose, and the problem that these service life fell was generated.

  Since the furnace port 2 can cope with this problem by changing the material and characteristics of the refractory 4, in the present invention, the furnace port 2 is removed for the purpose of extending the service life of the furnace port core 3. In the case of performing the silicon treatment and the dephosphorization treatment, the furnace core 3 was cooled (air-cooled) using nitrogen gas or Ar gas at room temperature. However, before and after the desiliconization treatment and the dephosphorization treatment, cooling may be performed using nitrogen gas or Ar gas.

  That is, as shown in FIGS. 1 to 3, a plurality of (9 in FIG. 1) half-cracked metal tubes 6 are welded to the surface of the furnace core 3 so as to face each other with the furnace port 2 interposed therebetween. To the inside of a metal channel formed by the surface of the half-cracked metal tube 6 and the furnace core 3 from the supply main pipe 5 connected to the half-cracked metal tube 6 at room temperature ( Room temperature) nitrogen gas or Ar gas is supplied, and the surface of the furnace iron core 3 is cooled by room temperature nitrogen gas or Ar gas. Nitrogen gas and Ar gas can be supplied from a gas cylinder loaded on the kneading vehicle 1, and the place where desiliconization and dephosphorization are performed is determined. It is also possible to connect one pipe.

  In this case, it is preferable to install the half-cracked metal tube 6 over the entire surface of the furnace opening core 3 so that the entire surface of the furnace opening core 3 is cooled. In FIG. 1, half-cracked metal pipes 6 are installed at nine places, but may be nine places or more or less than nine places. In FIG. 1, the half-cracked metal pipes 6 are linearly arranged, but may be meandered in a curved manner.

  Further, by blowing the nitrogen gas or Ar gas used for cooling from the periphery of the furnace port toward the dust collecting hood disposed at the upper part of the furnace port 2 from the half-cracked metal tube 6, the furnace port 2 and The ambient temperature can be lowered. This is because the partial pressure of oxygen in the atmosphere is suppressed to a low level by the nitrogen gas or Ar gas ejected from the half-cracked metal tube 6, and secondary combustion of CO gas directly above and around the furnace port 2 is suppressed. Because. Due to this effect, it is possible to reduce the heat load in the vicinity of the furnace port as well as the cooling of the furnace core 3. However, when nitrogen gas or Ar gas is jetted upward, the tip of the half-cracked metal tube 6 is a circular metal tube 6a.

  At this time, it is preferable that the gas is ejected at an elevation angle of 45 ° or more and 90 ° or less toward the center of the furnace port 2. If the angle is lower than 45 °, the dust collection efficiency is lowered, which is disadvantageous. On the other hand, if it is directed to the outside of 90 °, particularly when the kneading vehicle 1 is tilted to discharge hot water, high-temperature gas tends to be ejected to the side where the distance between the dust collecting hood and the kneading vehicle is widened. The temperature of the mouth 2 and its surroundings tends to rise.

  Further, in order to improve the service life of the furnace opening core 3, it is preferable that a protector 10 made of a heat resistant material is further disposed on the upper side of the half-cracked metal tube 6 as shown in FIG. 4. The role of the protector 10 is to reinforce the furnace opening iron skin 3. In addition, the code | symbol 8 shown in FIG. 4 is a weld metal for welding, and the both ends of the half-cracked metal pipe 6 are weld-joined with the furnace opening iron skin 3 with the weld metal 8. In FIG.

  In the above description, an example in which the flow path of nitrogen gas or Ar gas is formed by the half-cracked metal tube 6 and the surface of the furnace opening iron skin 3 is used. It may be formed. FIG. 5 is a schematic view showing an example in which the flow path is made of a metal tube. In order to make the furnace port iron shell 3 and the metal tube 7 in close contact with each other and to improve heat conduction, FIG. It is the figure which filled high thermal conductivity substance 9 between. Instead of the high thermal conductive material 9, the furnace core 3 and the metal tube 7 may be joined using a weld metal 8. In any case, it is necessary for the furnace opening 3 and the metal tube 7 to be in close contact with each other. If they are not in close contact with each other, the cooling capacity is insufficient, and the deformation and erosion of the furnace opening 3 can be suppressed. Can not.

  As described above, according to the present invention, normal temperature nitrogen gas or Ar gas is supplied to the inside of the flow passage in contact with the furnace opening core 3 disposed around the furnace opening of the kneading vehicle 1 to supply the furnace opening iron skin. 3 is forcibly cooled, so that even if the molten iron accommodated in the kneading vehicle 1 is subjected to desiliconization treatment or dephosphorization treatment under a high oxygen partial pressure, it is possible to suppress deformation and erosion of the furnace shell 3. Realized.

In a kneading vehicle in which dephosphorization is performed while blowing oxygen gas as a hot metal pretreatment, as shown in FIG. In other words, a total of 18 half-cracked metal tubes for cooling were disposed on the furnace cores on both sides of the furnace port, 9 on each side. Moreover, the edge part of a half-cracked metal tube was made into the metal tube, and opened upwards 75 degree | times from the horizontal direction toward the furnace port center. Nitrogen gas was flowed at a flow rate of 10 Nm ³ / min through one supply main pipe so as to be evenly branched into nine JIS-32A pipes.

  The amount of furnace body deformation (diameter displacement) before and after the adoption of this method was compared. Before the invention was applied, it was 10 mm / year, but after the invention was applied, it was markedly improved to 2 mm / year.

DESCRIPTION OF SYMBOLS 1 Chaotic car 2 Furnace port 3 Furnace iron bar 4 Refractory 5 Supply main pipe 6 Half cracked metal tube 7 Metal tube 8 Weld metal 9 High thermal conductivity material 10 Protector

Claims (4)

  Supplying nitrogen gas or Ar gas at room temperature into the flow path in contact with the iron skin around the furnace port of the kneading vehicle, and cooling the iron skin around the furnace port with nitrogen gas or Ar gas passing through the flow path The method of protecting the furnace port of a chaotic car.   The flow path is made of a circular half-cracked metal tube, and both end portions of the half-cracked metal pipe are welded to the iron skin, or the flow path is made of a metal pipe, 2. The kneading according to claim 1, wherein the metal tube and the iron skin are filled with a high thermal conductivity material, or the metal tube and the iron skin are joined by welding. Car furnace opening protection method.   Nitrogen gas or Ar gas that has passed through the flow path and cooled the iron skin around the furnace port is jetted from the flow path around the furnace port of the kneading vehicle to suppress secondary combustion of CO gas. The furnace port protecting method for a chaotic vehicle according to claim 1 or 2, characterized in that it is characterized in that:   The method for protecting a furnace port of a kneading vehicle according to claim 3, wherein nitrogen gas or Ar gas is ejected from the flow path toward the furnace port center of the kneading vehicle at an elevation angle of 45 ° or more and 90 ° or less. .

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