JP2008156717A - Method for determining repairing-timing of molten steel tapping hole in converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for determining a repairing-timing of a molten steel tapping hole in a converter with which in the case of determining whether the repair of the molten steel tapping hole is needed or not based on the damage and the worn state of the molten steel tapping hole in the converter, it is not necessary for the operator to directly observe the tapping hole by approaching the converter and there are no difference between operators and it is surely determined whether the repair is necessary or not. <P>SOLUTION: The method for determining the repairing-timing of the molten steel tapping hole in the converter in this invention comprises: measuring a radiant energy of the molten steel flow 2 flown down from the molten steel tapping hole 15 with an infrared camera 7 at the tapping time of the molten steel 1 from the converter 4; grasping the worn-state of the molten steel tapping hole based on the radiant ratio of the molten steel flowing decided with the measured radiant energy and the molten steel temperature; and determining whether the repair is needed or not. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for determining the repair timing of a converter steel outlet made of a refractory. Specifically, the molten steel flow flowing out from the steel outlet is observed with an infrared camera, and the steel output is based on the emissivity. The present invention relates to a method for estimating a wear situation of a mouth and determining a repair time.

  In a steelmaking integrated steelworks, hot metal produced in a blast furnace is decarburized and refined into a molten steel in a converter, and then steel products are produced through a continuous casting process and a rolling process. The converter for decarburizing and refining the hot metal is rotatable around the tilting axis (referred to as the “trunion shaft”). After the decarburization and refining, the converter that was standing upright is tilted, Steel is produced in a molten steel holding container such as a ladle from a steel outlet provided on the upper side wall. When the molten steel is discharged from the converter, the depth of the molten steel in the furnace becomes shallow at the end of the steel output, so a part of the slag generated in the converter is also mixed into the molten steel from the outlet. It flows out into the molten steel holding container.

  In the steel outlet, a plurality of hollow cylindrical sleeve bricks are inserted into guide bricks that form cylindrical through holes that connect the inside and outside of the converter, which are arranged on the side wall of the converter. It is composed of a refractory material, and the molten steel flows at a high speed through the central inner hole of the hollow cylindrical sleeve brick, and the slag that has an erosive action for the refractory material also flows down. The central hole in the brick is damaged and worn every time the steel is rolled out, leading to an expansion of the steel outlet. When the steel outlet is expanded, (1) the iron splash becomes intense with the increase in fall energy, and the iron yield decreases due to the scattered metal. (2) The slag mixed in the steel output increases and the molten steel. When the amount of slag in the holding container increases and the amount of Al used for deoxidation increases, and (3) when the sleeve brick is worn in a groove shape, the slag stopper can be used even if the slag stopper is used. The slag flows out from the damaged part, and the problem that the effect of the slag stopper cannot be exhibited sufficiently occurs.

  Therefore, in order to prevent these problems, repair of the steel outlet is carried out at the time when the wear of the sleeve brick becomes severe, and the converter operation is continued while repeating this steel outlet repair. This method of repairing the steel outlet is usually performed by removing the worn sleeve brick and inserting a new slave brick into the guide brick (see, for example, Patent Document 1 and Patent Document 2). In repairing the steel outlet, the gap between the new sleeve brick and the guide brick is filled with an irregular refractory.

Conventionally, the judgment of the damage and wear status of the steel outlet, that is, the necessity of repair of the steel outlet is determined by the operator approaching the converter and observing the inside of the steel outlet visually immediately after the steel exit. It was done. However, since it is determined visually, there is a problem that accurate determination is difficult and the optimal repair time is lost. In addition, there is a problem that a difference occurs in judgment criteria depending on individual operators. Furthermore, since the operator needs to look inside the hot steel outlet and observe it, the judgment work is also a dangerous work.
JP 2005-200704 A Japanese Patent Laid-Open No. 5-195038

  The present invention has been made in view of the above circumstances. The purpose of the present invention is to determine whether or not repairing of a steel outlet is necessary based on the damage / wear status of the steel outlet. By providing a method for determining the repair timing of a converter outlet that does not require close observation and directly observes the outlet, and does not cause individual differences among operators, and can accurately determine the necessity of repair. is there.

  The present inventors have intensively studied and studied to solve the above problems. The research and examination are explained below.

  When steel is output in the converter, the steel flow from the steel outlet is observed with an infrared camera, and the fact that the luminance of the slag is higher than the luminance of the molten steel, There is a method of obtaining the slag mixing rate and stopping the injection from the outlet at the time when the predetermined luminance distribution is reached, that is, when the predetermined slag mixing rate is reached, and preventing the outflow of slag from the converter. Widely practiced (see, for example, JP-A-2006-144114).

  In the infrared camera, the radiant energy of the slag flow and the radiant energy of the molten steel flow in the outgoing steel flow are measured as luminance, and both are identified based on the difference between the luminance of the slag and the luminance of the molten steel. While the present inventors have detected slag based on the difference in luminance between slag and molten steel, since the luminance of slag and the luminance of molten steel are significantly different from each other, when detecting the outflow of slag, Although not a problem, it was confirmed that the brightness of the molten steel flow changed even when the molten steel temperature was the same. In the present invention, the molten steel portion of the outgoing steel flow is referred to as a molten steel flow, and the slag portion is referred to as a slag flow.

  Here, the relationship between radiant energy and temperature is given by the following equation (1). In Equation (1), W is radiant energy, ε is emissivity, σ is Stiffan-Boltzmann constant, and T is absolute temperature.

W = εσT ⁴ (1)
Even if the temperature (T) of the molten steel flow is the same, the brightness of the molten steel flow, that is, the radiant energy (W) is different, which means that the emissivity (ε) varies depending on the state of the molten steel flow. As a result of further investigation, it was confirmed that the emissivity (ε) varies depending on the surface roughness of the molten steel flow, and the emissivity (ε) increases as the surface becomes rougher.

  The surface of the sleeve bricks that make up the steel outlet is smooth at the start of use, but as wear increases with the number of uses, the surface of the inner hole of the sleeve brick, that is, the inner wall of the steel outlet, becomes uneven. After repairing the steel outlet, as the number of times of steel output increases, the steel output flow tends to be disturbed, and the observed radiant energy increases even if the temperature of the molten steel flow is the same. That is, as the wear progresses, the emissivity (ε) in the equation (1) increases.

  From these results, it is possible to grasp the state of wear of the steel outlet based on the radiant energy (W) of the molten steel flow observed with an infrared camera and the emissivity (ε) of the molten steel flow determined by the molten steel temperature at that time. At the same time, the knowledge that it was possible to determine the necessity of repair was obtained.

  The present invention has been made on the basis of the above knowledge, and the method for determining the repair timing of a converter steel outlet according to the first invention flows down from the steel outlet by an infrared camera when the molten steel is discharged from the converter. The radiant energy of the molten steel flow is measured, and the necessity of repairing the outlet is determined based on the emissivity of the molten steel flow determined by the measured radiant energy and the temperature of the molten steel.

  In the first invention, a threshold value is set in advance for the emissivity, and the emissivity determined by the measured radiant energy and molten steel temperature is the threshold value. It is characterized that it is determined that the time of repairing the steel outlet is exceeded.

  According to the present invention, the wear status of the steel outlet is grasped based on the emissivity of the molten steel flow determined by the radiant energy measured by the infrared camera and the temperature of the molten steel, and the repair of the steel outlet is required depending on the wear status. Therefore, it is not necessary for the operator to approach the converter and observe the steel outlet directly, and there is no individual difference between the operators, and the necessity of repairing the steel outlet can be accurately determined. If a threshold value is set for the emissivity, it is possible to automatically determine the optimum timing for repairing the steel outlet.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a diagram illustrating an embodiment of the present invention, and is a schematic cross-sectional view illustrating an example in which the present invention is implemented when molten steel is discharged from a converter to a ladle.

  As shown in FIG. 1, the outer shell is an iron shell 13, and the molten steel 1 is discharged to the ladle 5 on the side wall on the upper side of the converter 4 in which the refractory 14 is constructed inside the iron shell 13. A steel outlet 15 that is an outflow hole is provided. The steel outlet 15 is configured by inserting a hollow cylindrical sleeve brick 16 into a cylindrical through hole formed by a guide brick 17 embedded in the refractory 14. In FIG. 1, both the sleeve brick 16 and the guide brick 17 are illustrated as one block, but each is composed of a plurality of blocks. Of course, one block may be used if it is allowed to be expensive. The gap between the sleeve brick 16 and the guide brick 17 is filled with an irregular refractory (not shown).

  A slag stopper 12 is installed on the iron skin 13 in the vicinity of the steel outlet 15, and the slag stopper 12 is controlled by a slag stopper control device 11 installed at a distance from the converter 4. ing. The slug stopper 12 includes a rotatable arm 18, a cast iron stopper 19 attached to the tip of the arm 18, and a hydraulic cylinder 20 for driving the arm 18. By operating, the stopper 19 at the tip of the arm 18 is fitted into the steel outlet 15. The stopper 19 is provided with a gas blowing hole (not shown) penetrating the central portion of the stopper 19, and nitrogen gas supplied from the gas blowing hole fits the stopper 19 into the steel outlet 15. When they are combined, they are injected into the flow path of the steel outlet 15. The flow rate of nitrogen gas flowing through the gas blowing holes and the hydraulic oil for operating the hydraulic cylinder 20 are controlled by the slag stopper control device 11. In FIG. 1, the hydraulic piping connected to the hydraulic cylinder 20, the gas supply pipe connected to the gas blowing hole, the flow rate adjusting valve, and the like are omitted.

  Moreover, from the infrared camera 7 for measuring the radiant energy of the outgoing steel flow 2 from the converter 4 to the ladle 5 as a brightness | luminance, and the calculating part 8 which inputs the measured value by the infrared camera 7, and performs a predetermined calculation A detecting device 6 is installed. The calculation unit 8 is connected to the process computer 9 so that the measured value of the molten steel temperature by the sublance measured at the decarburization refining end point in the converter is input to the calculation unit 8 via the process computer 9. It has become.

  The infrared camera 7 does not require any special function, and takes two-dimensional images of the steel flow 2 and its background, measures the radiant energy of each subject, and based on the radiant energy of each subject, Any device that displays the slag 3 and the background separately may be used. Even if it is not the infrared camera 7, for example, a CCD camera can measure the radiant energy of the subject, but since the detection sensitivity is high, the infrared camera 7 is used in the present invention. However, the present invention can be implemented even if a CCD camera is used instead of the infrared camera 7.

  The detection device 6 has two functions. The first function is to obtain the emissivity of the molten steel flow from the luminance of the molten steel flow in the outgoing steel flow 2, and from the obtained emissivity, the wear status of the outlet port 15 This is a function for determining the repair timing of the steel outlet 15 from the estimated wear situation, and the second function uses the fact that the luminance of the molten steel 1 and the luminance of the slag 3 are different from each other. 2 is a function for detecting the slag 3 mixed into the slag 3. The wear state of the steel outlet 15 and the determination result of the repair timing of the steel outlet 15 are sent to the display device 10 and displayed on the display device 10 or an alarm is issued. On the other hand, the detection result of the slag 3 is controlled by the slag stopper control. It is sent to the device 11 and the operation of the slag stopper 12 described above is performed. The present invention relates to the first function and does not require the second function, but it is preferable to have both functions because one infrared camera 7 can exhibit both functions. . Since the present invention is not directly related to the second function, a detailed description of the second function is omitted.

  Using the converter 4 and the detection device 6 having such a configuration, the present invention is carried out as follows.

  The hot metal is charged into the converter 4 and a slagging agent such as quick lime is further charged, and oxygen gas is supplied to the hot metal from the top blowing lance (not shown) or the bottom blowing tuyere (not shown). And decarburization refining. The hot metal is decarburized and refined to produce molten steel 1, and the ironmaking agent is melted to produce slag 3. In removing the molten steel 1 from the molten steel into the ladle 5, the converter 4 is tilted so that the steel outlet 15 is located on the lower surface side. Due to the tilting of the converter 4, the molten steel 1 flows down to the ladle 5 through the steel outlet 15. When the molten steel 1 progresses and the molten steel 1 staying in the converter 4 decreases, the slag 3 floating on the molten steel 1 is caught in the molten steel 1, mixed into the discharged steel flow 2, and flows out into the ladle 5. .

  This outgoing steel flow 2 is continuously or intermittently monitored by the infrared camera 7, the radiant energy of the outgoing steel flow 2 is measured, and a two-dimensional image of the radiant energy of the outgoing steel flow 2 is taken. Then, based on the radiant energy of the subject, the photographed two-dimensional image is classified into the molten steel 1, the slag 3, and the background, and the measured radiant energy and the image subjected to the separation process are transmitted to the calculation unit 8.

  Since the emissivity of the slag 3 in the infrared wavelength region is 1.2 to 1.5 times the emissivity of the molten steel 1, a difference occurs in the measured radiant energy level, so the infrared camera 7 should be used. Thus, the molten steel 1 and the slag 3 in the outgoing steel flow 2 can be clearly distinguished. Moreover, since the background of the outgoing steel flow 2 is a very low radiant energy level, it can be separated from the outgoing steel flow 2 naturally.

  The calculation unit 8 is described above from the radiant energy (W) of the molten steel flow measured by the infrared camera 7 and the molten steel temperature (T) in the converter at the end of decarburization refining input from the process computer 9 ( 1) The emissivity (ε) of the molten steel flow is calculated for each steel out using the formula. And the calculating part 8 estimates the wear condition of the steel outlet 15 from the calculated emissivity ((epsilon)), and determines the necessity of repair of the steel outlet 15 based on the estimated wear condition. This determination is performed as follows, for example.

That is, first, the emissivity (ε ₀ ) that is uniquely determined by the material of the molten steel 1 and the molten steel temperature is obtained in advance for each temperature of the molten steel, and then the optimum time for repairing the steel outlet 15 based on experience. Determine the emissivity (ε ^* ). Since the emissivity (ε ^* ) also changes depending on the temperature of the molten steel, the emissivity (ε ^* ) is also determined for each temperature of the molten steel. However, even if the emissivity (ε ^* ) is determined for each temperature, the temperature setting range of the molten steel at the time of steel output is narrow, and it is impossible to take data without fullness over all temperatures. Estimate the emissivity (ε ^* ) by analogy from several temperature data. Assuming that the emissivity (ε ^* ) for each temperature set in this way is a threshold value, and the calculated emissivity (ε) exceeds this threshold value, it is necessary to repair the steel outlet 15. This may be displayed on the display device 10 or an alarm may be issued.

  In this case, when the calculated emissivity (ε) is farther than the threshold, the wear of the steel outlet 15 has not progressed, and the calculated emissivity (ε) approaches the threshold. It is possible to grasp that the wear of the steel outlet 15 is progressing. In addition, although the temperature of the molten steel in the converter does not change as much as left during the steel output, since the temperature of the molten steel in the converter at the end of decarburization refining is used when calculating the emissivity (ε), When calculating the emissivity (ε) of the molten steel flow, it is preferable to use the radiant energy of the molten steel flow measured immediately after the start of steel production.

  If the slag outflow is detected by the calculation unit 8 during the steel output, a signal is sent to the slag stopper control device 11, the steel output flow 2 is stopped by the stopper 19, the converter 4 is erected, and the steel output operation is completed. Thereafter, the converter 4 is further tilted so that the steel outlet 15 becomes upward, and the slag 3 is discharged from the furnace port to a slag pot (not shown).

  Based on the indication or warning of “repair required” of the steel outlet 15 by the display device 10, the operator repairs the steel outlet 15 after the steel output or after the next steel output. The repair method of the steel outlet 15 is, for example, by breaking the old sleeve brick 16 from the guide brick 17 with a breaker or the like, removing the irregular refractory adhering to the inner surface of the guide brick 17, and then removing the new sleeve brick 16. This can be done by inserting it into the guide brick 17. A gap between the new sleeve brick 16 and the guide brick 17 is filled with an irregular refractory.

  As described above, according to the present invention, the wear state of the steel outlet 15 is grasped on the basis of the emissivity of the molten steel flow determined by the radiant energy measured by the infrared camera 7 and the temperature of the molten steel 1, and according to the wear state. Since it is determined whether or not the steel outlet 15 needs to be repaired, it is not necessary for the operator to approach the converter 4 and observe the steel outlet 15 directly, and there is no individual difference between operators, and the steel outlet is accurately repaired. Whether or not it is necessary can be determined.

It is a schematic sectional drawing which shows the example of embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Molten steel 2 Steel flow 3 Slag 4 Converter 5 Ladle 6 Detection apparatus 7 Infrared camera 8 Calculation part 9 Process computer 10 Display apparatus 11 Slag stopper control apparatus 12 Slag stopper 13 Iron skin 14 Refractory material 15 Steel outlet 16 Sleeve sleeve brick 17 Guide brick 18 Arm 19 Stopper 20 Hydraulic cylinder

Claims (2)

  When the molten steel is discharged from the converter, the radiant energy of the molten steel flow flowing down from the outlet is measured by an infrared camera, and based on the emissivity of the molten steel flow determined by the measured radiant energy and the temperature of the molten steel, A method for determining the repair timing of a converter steel outlet, wherein the necessity of repair is determined.   A threshold value is set in advance for the emissivity, and when the emissivity determined by the measured radiant energy and molten steel temperature exceeds the threshold value, it is determined as a repair timing of the steel outlet. The repair timing judgment method for converter outlets described in 1.

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