JP4899567B2 - Heat insulation method and heat insulation device for hot metal in chaotic vehicle - Google Patents

Description

  The present invention relates to a heat retaining method and a heat retaining device for hot metal in a kneading vehicle, and particularly to a technology effective for a kneading vehicle having a long waiting time for discharging molten iron to a converter.

  The hot metal melted in a blast furnace and containing about 4.4 to 4.6% by mass of carbon is received by a kneading vehicle (commonly called “topped”) at the time of unloading and is transported to a steelmaking factory. In the steelmaking factory, the hot metal pretreatment was used, and the kneading vehicle was used as a reaction vessel in order to reduce the refining (excluding impurity elements) load in the converter in advance for the hot metal before being discharged to the converter. Hot metal desiliconization and dephosphorization are performed. In addition, the desiliconization process is carried out by using a tapping or tilting iron disposed upstream of the kneading vehicle. Also, the molten iron after dephosphorization is transferred to a ladle, a desulfurizing agent is added, and the mixture is mechanically stirred to desulfurize. May be processed.

  Therefore, the kneading vehicle reciprocates between the blast furnace and the converter plant with a certain cycle time, and conveys the hot metal. An example of cycle time was compared between two steelmaking factories (referred to as factory A and factory B) using a chaotic vehicle with a capacity of 350 tons and having converters with capacities different from 350 tons and 180 tons, respectively. As shown in FIG. Using an index with the total cycle time at factory A being 100, it takes 10 hours to receive from the blast furnace and 12 hours to move to the dephosphorization field. Then, dephosphorization treatment is performed in 15 hours, and after the completion, it is transported to the converter over 5 hours. Since the hot metal is discharged to the converter according to the amount required for one heat of decarburization refining, the remaining hot metal is put on standby for use in the next heat. In the example of factory A, it takes 29 hours to pay out the molten iron from the chaotic car, and after the paying out, the chaotic car is immediately returned to the blast furnace over 29 hours.

  On the other hand, the cycle time at factory B is considerably longer than 150 hours as compared with factory A (see FIG. 4). The reason is that the target phosphorus value for the dephosphorization process is low, so that the dephosphorization time is long and it takes more time to move to the steel mill, and the converter capacity is small, so one heat is required. This is because the amount of hot metal is small. By the way, the waiting time for hot metal discharge to the converter is 57 hours.

  When there is such a long waiting time, the temperature of the hot metal in the kneading vehicle is greatly reduced, and the melting point of the hot metal (near 1150 ° C.) is approached. Therefore, at the time of final dispensing, as shown in FIG. 3, the metal 4 is placed on the surface of the lining refractory 3 in the vicinity of the opening 2 of the kneading wheel 1 (which serves as a hot metal receiving port and a dispensing port). The deposits referred to as grow. Discharge of the hot metal 5 is performed by tilting the kneading wheel 1 in the lateral direction. However, when such a metal 4 is attached, the hot metal 5 to be finally discharged is dammed up and not discharged. There is a problem that the utilization efficiency of the molten iron is lowered.

  By the way, as a means for preventing such a temperature drop of the hot metal 5 during the waiting time of the kneading vehicle 1, a technique of providing a heat insulating lid in the opening 2 of the kneading vehicle 1 is disclosed (for example, Patent Document 1). reference.). The heat insulating lid is formed of a lid member that is supported by a frame that is fixed at one end in a cantilevered manner on a mounting frame for a kneading vehicle trunnion shaft (a shaft that supports and tilts the chaotic vehicle at both ends), and can be opened and closed left and right. It has been done. Accordingly, if the opening is covered with this lid during the above-described waiting time for hot metal discharge, the hot metal held inside is temporarily maintained. Further, in order to preheat the inside of the kneading vehicle after the molten iron has been dispensed (see Patent Document 2) or to preheat the inside of the kneading vehicle before inserting the molten iron from the blast furnace, a heating burner is provided in the opening. There is also a technology to install (see Patent Document 3).

However, the heat insulation lid described in Patent Document 1 has a problem that the heat retention effect is not sufficient today, and the heat retention effect is not sufficient, and it is not possible to completely prevent the reduction of the hot metal temperature and the generation of metal. In addition, the techniques described in the cited documents 2 and 3 preheat the interior of the kneading vehicle, and do not exert an effect on heat retention of the hot metal.
Japanese Utility Model Publication No. 56-34850 Japanese Utility Model Publication No. 58-75742 JP-A-2005-76065

  In view of such circumstances, an object of the present invention is to provide a heat-retaining method and heat-retaining device for hot metal in a kneading vehicle that can smoothly discharge hot metal even when the waiting time for hot metal discharge becomes longer than before. .

  The inventor has intensively studied to achieve the above object, and the results have been embodied in the present invention.

  That is, the present invention allows the hot metal held in the kneading vehicle and subjected to the hot metal pretreatment to stand by at the upstream position of the converter, and is divided into several times or paid out to the next process once. In the heat-retaining method for hot metal in a kneading vehicle, the opening is covered with a heat-retaining lid and the inside of the kneading vehicle is heated with combustion exhaust gas from a burner attached to the heat-retaining lid. Here, heating the inside of the kneading car includes heating the atmosphere of the free board (the space above the hot metal bath) in addition to directly heating the hot metal inside the kneading car.

In this case, heating of the hot metal is divided into the above several times or delivered to the next process in one time, and based on the amount and temperature of the hot metal remaining in the kneading vehicle, the hot metal is maintained at a temperature above the freezing point. It is preferable to calculate the necessary amount of heat by the following formula and adjust the combustion of the burner so as to give the amount of heat corresponding to the calculated value.
[−100 × (T ₁ −T ₀ ) × W] / (L × A) ≦ ΔQ ≦ [−300 (T ₁ −T ₀ ) × W] / (L × A) (1)
Here, ΔQ: change amount of burner fuel supply amount (m ³ (standard state) / hr)
L: Elapsed time from the previous time to the current sampling time (hr)
T ₁ : Hot metal temperature in the chaotic vehicle after L hours (° C.)
T ₀ : Temperature of the hot metal sampled in the previous kneading car (° C)
W: Amount of hot metal in the chaotic car (ton)
A: Combustion heat of burner fuel (kcal / m ³ (standard state))
The burner is preferably a gas burner using C gas, propane or heavy oil as fuel. Here, the next process means a converter that performs decarburization refining, a storage furnace that temporarily stores hot metal to retain heat, adjusts components and temperature, or melts scrap.

  Furthermore, the present invention is a heat retention apparatus for the hot metal, which is installed in a standby position for discharging the hot metal held in the mixed car to the next process, by stopping the mixed car on the upstream side of the converter. A frame is provided beside the frame, one end is locked to the frame, and the frame can be extended to the opening of the kneading vehicle, and a lid member that is attached to the tip of the frame and covers the opening, A through hole is opened in the lid member, a burner nozzle inserted into the through hole, a pipe for supplying fuel and combustion air to the burner nozzle, and divided into the above-mentioned several times and discharged to the converter, A heat-retaining device for hot metal in a chaotic vehicle, comprising a calculation means for calculating the amount of heat necessary to maintain the hot metal at a temperature above the freezing point based on the amount and temperature of the hot metal remaining in the chaotic vehicle. is there.

  Further, the present invention is a heat retention apparatus for the hot metal, which is installed at a standby position for discharging molten iron held in the kneading vehicle to the converter by stopping the chaotic wheel on the upstream side of the converter. A frame is provided beside the position, one end is locked to the frame, and a frame that can be extended to the opening of the kneading vehicle; a lid member that is attached to the tip of the frame and covers the opening; A through-hole is opened in the lid member, a burner nozzle inserted into the through-hole, a pipe for supplying fuel and combustion air to the burner nozzle, and divided into the above-mentioned several times and discharged to the converter. A heat retaining device for hot metal in a chaotic vehicle, comprising: a calculation means for calculating the amount of heat necessary to maintain the hot metal at a temperature equal to or higher than the freezing point based on the amount and temperature of the hot metal remaining in the chaotic vehicle. But there is.

  According to the present invention, even if the waiting time for hot metal discharge becomes longer than before, not only the temperature drop of the hot metal in the kneading vehicle is suppressed, but also the adhesion of the metal near the opening can be prevented, and the hot metal discharge Can be implemented smoothly.

  Hereinafter, the best embodiment of the present invention will be described based on the background of the invention.

  First, the inventor decided to carry out heat insulation of the hot metal only with the heat insulation lid and to examine specific equipment. The heat insulating lid may be directly attached to the kneading vehicle as described in Patent Document 1, but the heat retaining place stops the kneading vehicle at the upstream side of the converter or storage furnace, Since the hot metal held in the kneading vehicle is a standby position where the hot metal held in the converter or storage furnace is discharged to the hot metal ladle, it was considered sufficient to provide the hot metal in the standby position. Then, as shown in FIG. 1, a frame 6 is provided beside the standby position, one end of the frame 6 is locked, and the frame 7 can be extended to the opening of the kneading vehicle, and attached to the tip of the frame 7. Therefore, the lid member 8 can be freely opened and closed to cover the opening.

  Since this lid member 8 needs to be heat resistant, it may be made of a refractory material or a steel plate with a refractory attached thereto. The size corresponds to the opening of the chaotic vehicle. Further, since it is necessary to support the gantry 6 in a cantilever manner and reach the opening of the kneading vehicle, it is supported by a frame 7 that can be extended to the opening. Since there are various means for closing or opening the opening, there is no particular limitation. In FIG. 1, the vertical position adjustment is performed by the jack 9, the fulcrum 10 of the frame 7 is provided on the gantry 6, the rear end 11 of the frame 7 is moved up and down with respect to the fulcrum 10, and the lid member 8 also moves up and down. The example which enabled it to do is given.

  However, only by using such a heat insulating lid, when the hot metal is divided into several times and discharged to the converter, and when the standby time becomes 100 or more in the cycle time index, It turned out that the growth of bullion cannot be prevented sufficiently. Therefore, the inventor decided to heat the hot metal with a burner.

  As specific means, a through-hole 12 is opened in the lid member 8, and a burner nozzle 13 inserted into the through-hole 12 and a pipe 14 for supplying fuel and combustion air to the burner nozzle 13 are provided. I prepared. As the burner, various fuels using heavy oil, gas, pulverized coal or the like as fuel can be used. However, since a large amount of C gas is obtained from the coke plant at the steelworks, it is preferable to use a gas burner as part of its effective use.

  By heating the hot metal with the combustion exhaust gas of the burner attached to such a heat insulating lid, the hot metal in the kneading vehicle is maintained at a temperature higher than the freezing point even if the hot metal discharge waiting time is prolonged, and It has become possible to prevent growth.

  Next, the inventor considered that an efficient and economical use of the burner was necessary, and examined a specific method. In other words, the amount of residue remaining in the kneading car is divided into several times and discharged to the converter, and the temperature can be measured directly. Based on these values, the residue is more than the freezing point. The amount of heat required to maintain a certain temperature was calculated. Then, the hot metal was heated while adjusting the combustion of the burner so as to give the amount of heat corresponding to the calculated value. The burner combustion adjustment may be performed by adjusting the combustion time including the combustion stop or by reducing the amount of fuel. It should be noted that the calorie calculation required to maintain the residue at a temperature equal to or higher than the freezing point can be easily performed by providing a computer. Data such as solidification temperature and specific heat of hot metal and calculation software may be stored in advance in the computer.

Molten steel was smelted in a steelmaking factory equipped with a converter having a capacity of 180 tons using a kneading car with a capacity of 350 tons. At that time, the heat retention device according to the present invention was provided at the hot metal discharge standby position and applied to a part of the operation. FIG. 5 shows changes in the temperature and amount of hot metal in the kneading vehicle before and after applying the present invention. The hot metal temperature index before the final dispensing was 100 before application of the present invention, but increased to 101 after application, increasing by 1%. Considering that the normal payout temperature is 1500 to 1200 ° C., it corresponds to 15 to 12 ° C. Here, C gas (combustion heat A of 4500 kcal / m ³ (standard state) was used as the fuel for the burner. Note that when the present invention is applied, the residual gas is used for efficient and economical burner combustion. Based on the amount and temperature of the hot metal, the calorific value is calculated by the above equation (1), and the combustion of the burner is also adjusted.

  Further, the amount of residue when the hot metal dispensing from the kneading vehicle is completed is investigated after many operations are performed, and the result is shown in FIG. The arrow indicates the position of the data after the application of the present invention, but it is clear that the distribution of the residual amount at the temperature when the conventional average residual amount is 100 is also reduced.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the heat insulating apparatus of the hot metal in a kneading vehicle which concerns on this invention, (a) is a top view, (b) is a front view, (c) It is an enlarged view of a heat insulating lid. It is the figure which compared the amount of residue which remains in a chaotic vehicle after final payout. It is a cross-sectional view which shows the condition where bullion grows in a chaos car. It is a figure explaining the cycle time required when a chaotic vehicle is used once between a blast furnace and a converter. It is a figure which shows the change of the temperature and quantity of hot metal in a kneading vehicle before and after applying this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Chaotic wheel 2 Opening part 3 Lined refractory material 4 Metal 5 Hot metal 6 Base 7 Frame 8 Lid member 9 Jack 10 Support point 11 Frame rear end 12 Through-hole 13 Burner nozzle 14 Piping 15 Blower

Claims (4)

When the hot metal held in the kneading vehicle and subjected to the hot metal preliminary treatment is waited at the upstream side position of the converter and divided into several times or paid out to the next process once,
A heat retaining method for hot metal in a chaotic vehicle, wherein the chaotic vehicle is heated with a combustion exhaust gas from a burner attached to the heat retaining lid while the opening of the chaotic vehicle is covered with a heat retaining lid. The amount of heat required to maintain the hot metal at a temperature equal to or higher than the freezing point based on the amount and temperature of the hot metal that is divided into the above several times or delivered to the next process and is left in the kneading vehicle. The heat-retaining method for hot metal in a kneading vehicle according to claim 1, wherein the heat is calculated by the following formula and the combustion of the burner is adjusted so as to give the amount of heat corresponding to the calculated value.
[−100 × (T ₁ −T ₀ ) × W] / (L × A) ≦ ΔQ ≦ [−300 (T ₁ −T ₀ ) × W] / (L × A) (1)
Here, ΔQ: change amount of burner fuel supply amount (m ³ (standard state) / hr)
L: Elapsed time from the previous time to the current sampling time (hr)
T ₁ : Hot metal temperature in the chaotic vehicle after L hours (° C.)
T ₀ : Temperature of the hot metal sampled in the previous kneading car (° C)
W: Amount of hot metal in the chaotic car (ton)
A: Combustion heat of burner fuel (kcal / m ³ (standard state))   3. The heat-retaining method for hot metal in a kneading vehicle according to claim 1 or 2, wherein a gas burner using C gas, propane or heavy oil as fuel is used as the burner. A hot metal heat retention device installed at a waiting position for discharging the hot metal held in the chaotic vehicle to the next process, stopping the chaotic vehicle on the upstream side of the converter,
A frame is provided beside the standby position, one end of the frame is locked to the frame, and the frame can be extended to the opening of the kneading vehicle, and an openable / closable lid member that is attached to the tip of the frame and covers the opening A through-hole in the lid member, a burner nozzle inserted into the through-hole, a pipe for supplying fuel and combustion air to the burner nozzle, and dividing into the above-mentioned several times and paying to the converter And a calculation means for calculating the amount of heat required to maintain the hot metal at a temperature equal to or higher than the freezing point based on the amount and temperature of the hot metal left in the chaotic vehicle. Thermal device.

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