JP2008223121A - Method for repairing furnace wall surface at upper part of blast furnace shaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for repairing a furnace wall surface at the upper part of a blast furnace shaft, in which a portion to be repaired on the operation can simply be specified in a short time by detecting a sign of giving the large damage to the furnace wall before becoming the unstability in the blast furnace operation. <P>SOLUTION: Relative descending speed of charging materials in the furnace near the furnace wall at the upper part of the blast furnace shaft is measured at the plurality of points in the circular direction, and when the relative descending speed at any measuring point exceeds the prescribed value, it is determined that there is the sign of the macroscopic wearing state of the furnace wall at the upper part of the shaft bringing about the unstability to the operation in the blast furnace and also, it is specified that the damage portion of the furnace wall exists in the circumference of the measuring point exceeding the prescribed value, and at the stopping time of blowing, the level of the charging material in the furnace is lowered, and the repairing material is injected and repaired onto this specified damaging portion on the furnace wall. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a method for repairing a blast furnace shaft upper furnace wall surface, which detects the worn state of a shaft upper furnace wall brick and stave in an iron blast furnace during operation and systematically repairs it during scheduled wind breaks.

  Furnace walls such as lining bricks and staves on the shaft part that forms the upper part of the furnace body of the blast furnace are eroded, so repairing the eroded surface of the furnace wall and maintaining the circumferential balance of the expansion of the shaft part This is important for the stable operation of the blast furnace.

  That is, when the furnace wall surface of the shaft portion formed in a truncated cone shape that spreads downward toward the lower side is eroded, a recess that is a partially eroded portion occurs in the furnace wall surface in the circumferential direction of the shaft portion, The balance in the circumferential direction of the shaft furnace wall surface is not uniform, which affects the descending behavior of the furnace interior material and the balance of the gas flow passing through the furnace interior material in the circumferential direction.

  Therefore, various repair methods for the furnace wall surface including the upper part of the shaft of the blast furnace have been proposed (Patent Documents 1 to 5).

  The repair method described in Patent Document 1 relates to a method for suppressing deterioration in air permeability at the time of air blow-up due to rebound loss of the repair material, and the repair method described in Patent Document 2 prevents blockage of the furnace wall through hole due to repair. It is about how to do.

  Moreover, all the repair methods of patent documents 3-5 are related with the enforcement technique for performing furnace wall repair efficiently.

  On the other hand, the macro-detection of the state of wear on the furnace wall such as the lining bricks and staves above the shaft that make up the furnace body of the blast furnace enables systematic preparation for early shaft upper repairs, thus ensuring high-productivity and stable operation of the blast furnace. It is important to maintain.

  Therefore, in order to detect macroscopically the state of wear of the furnace wall at the upper part of the shaft, a technique for monitoring the temperature and erosion status of the refractory has been proposed, and mainly a technique for measuring the remaining thickness of the furnace wall (Patent Documents 6 to 6). 9) and a technique (Patent Document 10) for measuring the wear of the furnace body cooling device using ultrasonic waves has been proposed.

  In the method for measuring the remaining thickness of the furnace wall described in Patent Documents 6 to 9, a sensor is embedded in the furnace wall in advance, and in the measurement method described in Patent Document 10, an ultrasonic probe is attached to the end of the mounting bolt of the stave. It is in contact.

It has also been proposed to measure the furnace wall profile using a sensor having a three-dimensional camera system function to which laser radar technology is applied (Patent Document 11).
JP-A-2005-023392 JP 2004-293951 A JP 09-041010 A JP 09-125115 A Japanese Patent Laid-Open No. 08-218107 JP 57-151803 A JP 59-041783 A JP 59-096600 JP 58-088106 A JP 61-264110 A JP-A-10-237517

  In the repair method of the blast furnace shaft upper furnace wall described in Patent Documents 1 to 5 described above, when the furnace wall erodes and a blowout occurs in which a large amount of gas in the furnace is rapidly discharged, the fall of the furnace interior material is reduced. Repairs are performed in the case where a suddenly progressing slip occurs or a shelf hanging occurs where the descent of the furnace interior material stops.

  Therefore, repair work on the furnace wall surface will be carried out during scheduled breaks after the actual blast furnace operation has become unstable. However, in this case, the erosion part is large and large repairs are required. There is a risk that the wind rest time will be longer. For this reason, significant heat compensation is required at the time of resting for repair, and the productivity is significantly reduced for a certain period after the air blow-up is started. At the same time, there is no guarantee of the start-up of a smooth operation, and there is a possibility of long-term production decline.

  In addition, it is difficult to specify a site to be repaired, and it is necessary to specify a site to be damaged by a pre-scaled wind break.

  Thus, the conventional repair of the upper furnace wall surface of the blast furnace shaft can only solve one of trouble avoidance at the time of air blow-up by repairing the furnace wall, repair effect of the damaged part of the furnace wall, and improvement of repair efficiency.

  In addition, macro-detection of the state of wear on the furnace wall such as lining bricks and staves above the shaft that forms the furnace body of the blast furnace makes it possible to systematically prepare for the early repair of the shaft upper part. It is important to maintain.

  However, since the techniques described in Patent Documents 6 to 10 described above measure the remaining thickness of the furnace wall at the sensor placement location, information on the local wear state of the furnace wall such as lining bricks and staves at the upper part of the shaft. This information is important from a facility management perspective. However, since the information obtained is the remaining thickness of the furnace wall and there is no direct correlation with the operating condition of the blast furnace, it is not possible to immediately evaluate the effect on the operating condition of the blast furnace using this remaining thickness value. Moreover, it cannot be said that it is sufficient information as information on the macro wear state of the upper part of the shaft for determining whether the upper part of the shaft needs to be repaired in order to continue stable operation.

  That is, the remaining thickness information of the furnace wall indicates the thickness of the current lining brick and stave, and for example, the current remaining thickness can be an indicator for determining whether or not there is a problem in blast furnace operation, but it has occurred If the wear of the furnace wall is left unattended, it cannot be a sign of a worn state that large repairs will be required in the future.

  Further, in the technique described in Patent Document 11, the furnace wall profile at the upper part of the shaft can be measured, but in this case as well, the furnace wall profile shows a sign of a worn state that a large repair is required in the future. I don't get it.

  The present invention has been made in view of such a conventional problem. By detecting a sign of significant damage to the furnace wall before the operation of the blast furnace becomes unstable, the present invention is simple and short in the scheduled rest wind immediately after. By repairing parts that should be repaired on time, troubles at the time of air blow-up can be avoided, and the parts to be repaired during operation can be identified during blast furnace operation, thereby effectively repairing the furnace wall surface. It aims at providing the repair method of the blast furnace shaft upper furnace wall which can be done.

According to the results of experiments using the blast furnace model of the inventors,
(A) At the upper part of the shaft, the furnace interior particles are in a solid state that is still easy to flow, and the shape of the particles is a divergent shape having a predetermined shaft angle. The particle descent rate tends to be fast, and the wear state of the furnace wall at the top of the shaft has a greater effect on the descent rate of the particles inside the furnace near the furnace wall than at the bottom of the shaft or the belly of the furnace,

(B) When the wear of the furnace wall such as the lining brick or stave surface on the shaft progresses, the porosity of the charge in the vicinity increases, the gas flow near the blast furnace wall increases, and the heat load of the furnace increases. , Instability of blast furnace operation such as reduction of reduction efficiency and lowering of furnace bottom temperature is likely to occur,
I found out.

  In the present invention, based on these findings, the relationship between the relative descent speed of the furnace interior adjoining the furnace wall near the furnace wall and the shaft angle of the surface of the worn part of the furnace wall (furnace wall evaluation characteristics) Based on this, the furnace body heat due to the gas flow drift caused by the current state and future furnace wall wear state and furnace wall wear from the relative descending speed of the furnace interior input measured during blast furnace operation. Using the technical concept to evaluate the blast furnace operating state based on the impact of load increase, etc., the precursor of the macro-wall wear state at the top of the shaft and the location of the furnace wall damage are identified, and the furnace wall damage is caused during scheduled wind breaks. The part was repaired.

  The gist of the present invention is as follows.

  (1) Measure the relative descent speed of the furnace interior in the vicinity of the furnace wall above the blast furnace shaft at multiple points in the circumferential direction, and if the relative descent speed at any one of the measurement points exceeds a predetermined value, the blast furnace operation It is judged that it is a precursor to the macroscopic wall wear state of the upper part of the shaft that causes instability, and it is determined that there is a furnace wall damage site around the measurement point that exceeds the predetermined value, and at the time of planned rest A method of repairing an upper furnace wall surface of a blast furnace shaft, wherein a repair material is blown into the identified furnace wall damage site by reducing the level of furnace interior entry.

  (2) Based on the evaluation characteristics of the furnace wall surface showing the relationship between the change in the relative descent speed and the shaft angle of the upper furnace wall of the blast furnace shaft, the macroscopic condition of the furnace wall wear at the upper part of the shaft that causes instability of the blast furnace (2) The method for repairing the upper furnace wall surface of the blast furnace shaft, characterized in that it is determined that the harbinger is in a precursor.

  (3) The relative descent rate is a value obtained by dividing the descent rate obtained by a plurality of sounding devices arranged in the vicinity of the furnace wall by the calculated descent rate of the furnace interior contents at the top of the furnace based on the required oxygen amount. (1) or (2) the method of repairing the upper furnace wall surface of the blast furnace shaft.

  (4) The method of repairing the upper furnace wall surface of the blast furnace shaft according to any one of (1) to (3), wherein the relative descent speed of the predetermined value is 1.15.

  According to the present invention, it is only necessary to measure the relative descent speed of the furnace interior material in the vicinity of the furnace wall at the top of the shaft at the time of blast furnace operation, and based on the evaluation characteristics of the furnace wall surface, It is possible to know the furnace wall surface condition such as lining brick and stave. For this reason, it is possible to avoid the trouble at the time of air blow-up by repairing the upper furnace wall of the blast furnace shaft, which was impossible with the prior art, and to improve the repair effect of the damaged part of the furnace wall by simultaneously identifying the damaged part of the furnace wall. This will enable long-term stable operation of the blast furnace.

  Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

  FIG. 1 is a furnace wall evaluation characteristic diagram showing the relationship between the shaft angle of the shaft upper furnace wall and the relative descent speed near the furnace wall near the blast furnace shaft. The vertical axis represents the relative descent speed and the horizontal axis represents the shaft upper furnace wall. Indicates the shaft angle. FIG. 2 is a schematic diagram of the upper part of the blast furnace shaft, and is a diagram showing a method for measuring the relative descent rate of the furnace interior in the vicinity of the furnace wall above the blast furnace shaft, and the shaft angle of the upper furnace wall of the blast furnace shaft.

  The relative descent speed of the furnace interior material in the vicinity of the furnace wall above the blast furnace shaft can be measured as follows.

  At the top of a normal blast furnace, a microwave type profilometer or sounding type is used to measure the charging distribution or descending speed of furnace interior materials consisting of iron-containing raw materials such as iron ore and sintered ore and coke. A measuring device is provided. Although these apparatuses are used for the relative descent speed of the furnace interior material in the present invention, a case where measurement is performed using a sounding type measuring apparatus will be described below.

  In FIG. 2, four sounding type measuring devices 5, 6, 7, 8 are installed at equal intervals in the circumferential direction at the furnace top of the shaft portion 1, and a weight is provided at the lower end from each sounding type measuring device 5-8. Wire ropes 5a, 6a, 7a, and 8a marked with are suspended so as to be wound up. The wire ropes 5a, 6a, 7a and 8a suspended from the sounding type measuring devices 5 to 8 have measuring points m1 and m2 near the furnace wall where the weight at the lower end is relative to the uppermost surface 4 of the furnace interior deposit layer. Land on m3 and m4. The landing is detected by a change in the tension of the wire ropes 5a, 6a, 7a, 8a. Based on the feeding length of the wire ropes 5a, 6a, 7a, 8a at this time, A level is obtained. And the wire rope 5a, 6a, 7a, 8a is wound up after a detection. And by repeating this operation | movement, the descent | fall speed of the furnace interior entrance in each measurement point m1, m2, m3, m4 is calculated | required.

  In this example, the relative descending speed of the furnace interior entrance at the four measurement points m1, m2, m3, m4 in the vicinity of the furnace wall (the descending speed of the furnace interior entrance is divided by the average descending speed of the furnace interior entrance). Value), the average descent rate of the furnace interior was estimated at the top of the furnace estimated based on the pig iron production rate calculated from the required oxygen quantity per ton of pig iron determined by the oxygen quantity of the blast volume and the reduction ratio. Calculated descent speed. That is, the relative descent speed of the furnace interior material is a value obtained by dividing the descent speed at each measurement point m1, m2, m3, m4 by the calculated descent speed at the top of the furnace based on the required oxygen amount.

  FIG. 1 shows an example of the relationship between the shaft angle of the furnace wall surface above the blast furnace shaft and the relative descent speed in the vicinity of the furnace wall obtained by a blast furnace three-dimensional half-cut model experiment.

  The positions of the measurement points m1 to m4 in the vicinity of the furnace wall are set to a relative radius of 0.95.

  In actual operation of the blast furnace, when the erosion of the furnace wall such as the lining brick surface and stave surface above the shaft progresses, the porosity in the vicinity of the furnace wall increases and the gas in the periphery (periphery of the furnace interior deposit layer) It is known that the flow increases and the operation becomes unstable such as an increase in the furnace heat load.

  At the top of the shaft, the furnace interior particles are still in a solid state that is easy to flow, and the shape of the particles is a divergent shape having a predetermined shaft angle. The speed tends to increase, and the state of wear of the furnace wall on the upper part of the shaft is more greatly influenced by the descending speed of the particles inside the furnace wall near the furnace wall than the lower part of the shaft and the belly part.

  Generally, the shaft angle (initial shaft angle P0) of the furnace wall surface at the top of the shaft when the blast furnace is started up is set to 80 to 83 degrees, and the relative descent speed of the particles inside the furnace wall near the furnace wall at this time Is 1, which is the same speed as the descent speed of the furnace interior. From the result of FIG. 1 by the above model experiment, the relative descending speed of the particles inside the furnace wall near the furnace wall is relatively decreased when the shaft angle (Pn) at the time of wear of the furnace wall becomes smaller than the initial shaft angle (P0). The speed increases, and particularly increases rapidly under the condition that the shaft angle is smaller than 73 degrees.

  This suggests that the descent speed of the furnace interior entry to the vicinity of the furnace wall increases as the shaft angle decreases due to the progress of wear of the furnace wall surface such as the lining brick surface and stave surface above the blast furnace shaft. . In other words, based on the relationship between the shaft angle of the furnace wall surface at the top of the blast furnace shaft and the relative descent speed in the vicinity, the relative descent speed of the furnace interior material near the furnace wall at the top of the shaft during blast furnace operation In addition to detecting the degree of wear of the furnace wall, it is possible to predict the future state of wear of the furnace wall.

  In addition, since the porosity of the furnace interior inclusions near the furnace wall wear-out part increases due to the wear of the furnace wall surface such as the lining brick surface and the stave surface above the blast furnace shaft, this region (the peripheral part of the furnace interior deposit accumulation layer) ) Gas flow increases relatively. The drift of the gas flow in the vicinity of the furnace wall causes instability of the blast furnace operation such as an increase in the furnace heat load, a reduction in reduction efficiency, and a decrease in the temperature at the bottom of the furnace.

  Therefore, based on the relationship between the shaft angle of the furnace wall surface at the top of the blast furnace shaft and the relative descent speed in the vicinity, it will occur in the future from the relative descent speed of the furnace interior material near the furnace wall at the top of the shaft during blast furnace operation. It is possible to predict the state of blast furnace operation such as an increase in the furnace thermal load, a reduction in reduction efficiency, and a decrease in the temperature at the bottom of the furnace due to the drift of the gas flow at the worn part of the obtained furnace wall.

  As shown in FIG. 1, when the relative descending speed of the furnace interior near the furnace wall surface of the shaft portion during blast furnace operation exceeds 1.15, the shaft angle is smaller than 73 degrees due to the wear of the furnace wall. As a result, the drift of the gas flow near the worn part of the furnace wall becomes prominent, and it is expected that the blast furnace operation will become unstable in the future, such as an increase in the furnace thermal load, reduction in reduction efficiency, and a decrease in the furnace bottom temperature. Is done.

  Therefore, the degree of erosion of the lining brick or stave on the shaft upper part can be predicted from the change in the relative descending speed of the furnace interior material near the furnace wall.

  When the shaft angle is about 73, it cannot be said that the wear of the furnace wall surface is large. However, when the relative descent speed exceeds 1.15 corresponding to this shaft angle, the erosion of the furnace wall surface such as the brick surface on the shaft or the stave surface. It can be determined that the state indicates a sign that the peripheral flow in the vicinity of the furnace wall rises.

  That is, when the relative descent speed in the vicinity of the furnace wall is more than 1.15, it is determined that it is a precursor of a macro-type furnace wall wear state at the upper part of the shaft that causes unstable operation.

  In this embodiment, the sounding measuring devices 5, 6, 7, and 8 measure the level of the uppermost surface 4 of the furnace interior deposit layer at four points in the circumferential direction at the upper part of the shaft. If even one of the points exceeds the relative descent speed of 1.15, it can be determined that a furnace wall damage site exists around the measurement point. Of course, if the relative descent speed at a plurality of measurement points exceeds 1.15, it can be determined that a furnace wall damage site exists around these measurement points. Therefore, in this embodiment, four measurement points are used, but if the number of measurement points is larger than this, the position determination accuracy of the furnace wall damaged part can be improved. In addition, when it is sufficient to determine whether the furnace wall damage site is located in any one of the halves in the circumferential direction of the shaft 1, the measurement may be performed at two points on both ends of the diameter line.

  If the furnace wall at the top of the shaft can be determined to be a precursor to a macro-type furnace wall wear state and the range of the damaged part of the furnace wall in the circumferential direction of the shaft 1 can be identified, Reducing the charge level from the line level to around 10m) and resting. Then, repair is performed by blowing a repair material made of an irregular refractory into the specified furnace wall damage site.

  In this case, since the damaged part of the furnace wall is small, small-scale repairs are required, and repairs are completed in a short time efficiently within the scheduled wind-off time. Can do. For this reason, the decrease in productivity after the start-up of the air blow is small, and the start-up of the operation is also smooth. And it can contribute to the long-term stable operation of a blast furnace, can maintain a high production stable operation, and can also reduce a reducing material ratio.

The furnace wall evaluation characteristic view which shows the relationship between the shaft angle which shows the Example of this invention, and the relative descent speed in the furnace wall vicinity. Schematic of the upper part of a blast furnace shaft.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shaft part 2 Inner wall surface 3 at the time of start-up Worn inner wall surface 4 Uppermost surface 5-8 of a furnace interior deposit layer 5a, 6a, 7a, 8a Wire rope m1, m2, m3, m4 with a weight Measurement point

Claims (4)

  The relative descent speed of the furnace interior material near the furnace wall at the top of the blast furnace shaft is measured at multiple points in the circumferential direction, and the operation of the blast furnace becomes unstable when the relative descent speed at any one of the measurement points exceeds a predetermined value. It is determined that there is a precursor to the macroscopic wall wear state of the upper part of the shaft that causes damage, and it is determined that a furnace wall damage site exists around the measurement point exceeding the predetermined value. A method of repairing the upper furnace wall surface of a blast furnace shaft, wherein a repair material is blown into the identified furnace wall damage site by reducing the level of the object.   Based on the furnace wall evaluation characteristics indicating the relationship between the change in the relative descent speed and the shaft angle of the upper furnace wall of the blast furnace shaft, it is a precursor to the macro-type furnace wall wear state at the upper part of the shaft that causes unstable operation of the blast furnace. It is judged that there exists, The repair method of the blast furnace shaft upper furnace wall surface of Claim 1 characterized by the above-mentioned.   The relative descent speed is a value obtained by dividing the descent speed obtained by a plurality of sounding devices arranged near the furnace wall by the calculated descent speed of the furnace interior material at the top of the furnace based on the required oxygen amount. The repair method of the blast furnace shaft upper furnace wall surface of Claim 1 or 2 to do. The method for repairing an upper furnace wall surface of a blast furnace shaft according to any one of claims 1 to 3, wherein a relative descending speed of the predetermined value is 1.15.

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