JPH04308013A - Method for operating blast furnace - Google Patents

Abstract

PURPOSE:To make lowering speed of charging materials and heat flow ratio controllable by providing plural steps of projections in the inside wall of a bosh part in a blast furnace. CONSTITUTION:The plural projections 1 capable of advancing/retreating toward a furnace center, are disposed in the vicinity of the furnace wall of the bosh part from a lower shaft part in the blast furnace, and protruded length in a horizontal direction is independently made to controllable with this driving part 5. By the disturbance of the shape in the furnace inside wall with the projections 1, the lowering behaivior and the lowering speed of the charging materials and the heat flow ratio are controlled and the furnace control is always kept to a stable condition, and the operation having low fuel rate and high iron tapping rate can be efficiently executed, and at the same time, the service life of the blast furnace can be prolonged more than that of a conventional furnace.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of operating a blast furnace.

0002

BACKGROUND OF THE INVENTION It has been reported in the literature that the shape of the inner wall surface of a blast furnace has a large influence on the descending behavior of the charge in the blast furnace, that is, the formation behavior of a mixed layer and a stagnant layer near the furnace wall. For example, in "Tetsu to Hagane" (69 (1983) 4, S61), when several stages of protrusions are installed on the shaft part, a mixed layer is formed near the furnace wall, so the gas flow rate near the furnace wall is It was reported that there was an increase in
4, S75), it has been reported that when protrusions are installed in the lower part of the furnace below the furnace belly, a stagnation layer is formed near the furnace wall directly above the protrusions.

On the other hand, as the blast furnace has been in operation for a number of years since it was fired, the shape of the inner wall surface becomes increasingly uneven in the furnace height direction and in the circumferential direction due to wear and tear of the furnace bricks. Such disturbances in the shape of the inner wall surface form a mixed layer or stagnation layer near the furnace wall, which destabilizes blast furnace operation. It is common practice to repair non-uniform disturbances in wall surface shape using various repair techniques. And, special public service 63-315
In Publication No. 23, if a disturbance in the shape of the inner wall surface occurs in the lower part of the furnace below the furnace belly, which is extremely difficult to repair using current repair techniques, the Ore/Coke near the furnace wall can be increased. It is disclosed that the stagnant layer formed can be reduced.

0004

[Problems to be Solved by the Invention] However, with conventional repair methods, the inner wall shape is damaged in the furnace height direction and circumferential direction due to wear and fall of the furnace bricks from the middle to the end of the blast furnace life. If uniformity progresses, the number of repairs performed during wind breaks will increase significantly, resulting in an increase in repair costs and loss of repair materials, resulting in an increase in powder brought into the furnace. There is a problem of ventilation problems during raising, and it is not a fundamental solution for maintaining stable operation of the blast furnace. And the aforementioned special public service 1986-31
The method disclosed in Japanese Patent No. 523 has a problem in that it cannot be an effective means for operations where Ore/Coke near the furnace wall cannot be increased, such as all-coke operations.

Therefore, the present invention actively creates disturbances in the shape of the inner wall surface, which are currently a problem for stable operation of blast furnaces, and adjusts the disturbances in the shape of the inner wall surface. The purpose is to control the circumferential balance of the descending behavior of materials to ensure stable operation of blast furnaces.

[0006]

[Means for Solving the Problems] The present invention actively creates and adjusts the disturbance in the shape of the inner wall surface, which is currently a problem for the stable operation of blast furnaces. This aims to control the working surface profile of the charge as it descends, as well as the rate of descent of the charge near the furnace wall and the heat flow ratio.

Specifically, the present invention provides several steps of protrusions installed in each of a plurality of areas divided in the furnace height and circumferential direction from the bottom of the shaft of the blast furnace to the vicinity of the furnace wall of the bosh section. By moving the protrusion forward and backward toward the furnace, the protruding length of the protrusion can be adjusted independently for each of the multiple divided ranges in the furnace height and circumferential direction, and the profile of the operating surface, the descending speed near the furnace wall, and the heat flow can be adjusted independently. This is a method of controlling the ratio.

[0008] The method of the present invention can form a thin stagnant layer in the vicinity of the furnace wall in any range from the bottom of the shaft to the bosh section when the inner wall surface shape is disturbed, which has conventionally been a problem in blast furnace operation. It becomes possible to do so. Furthermore, by slowly lowering the charge near the furnace wall in an arbitrary range from the bottom of the shaft to the morning glory section, the heat between the charge and the high-temperature reducing gas can be increased in the arbitrary range of the lower part of the furnace, which is the most thermally severe. It is possible to prevent the replacement time from shortening. In the present invention, a case has been described in which the protrusions used in the present invention are installed in the entire range from the bottom of the shaft to the morning glory in the direction of the furnace height, and around the entire circumference, but it is also possible to install the protrusions locally. It will be done.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described with reference to the drawings and their functions. The method of the present invention is a method based on knowledge obtained from experimental results described below. The present inventors conducted an experiment using a model device that has a vertical cross-sectional structure as shown in FIG. 3 and is approximately one-twentieth the size of an actual blast furnace. The hearth diameter of this model device was 345 mm, the furnace belly diameter was 379 mm, and the effective height from the tuyere to the upper end of the shaft was 1217 mm. In addition, on the front of the model device, the falling and melting of coke and pseudo-ore (a mixture of easily melted metal and stearic acid whose solid-liquid flow rate ratio and packing density are adjusted to approximate actual blast furnace conditions) are shown. A heat-resistant glass was attached to the device so that its behavior could be observed.

Coke 6 and pseudo ore 7 were alternately charged in layers from a bell 8 at the top of the model device via a movable armor 9. On the other hand, heated air at 180 degrees Celsius was blown through 18 tuyeres 10 at the bottom of the device to cause the pseudo ore to melt and drip. After the molten material is collected in the hearth, it is passed through the tap hole 1.
It was ejected from 1. The coke was transported to a lower hopper by six rotary feeders 13 provided directly below the raceway 12, and further discharged into a closed storage by a tubular conveyor 14. In this blast furnace model device, a thermometer, a pressure gauge, and a hot wire anemometer are installed on the furnace wall or inside the furnace to detect the temperature state, air permeability, stress state near the wall, and gas flow inside the furnace. Colored coke was charged as a tracer for the isochrone line in order to detect the falling state of the loaded material.

FIG. 1 is a diagram illustrating the operation of the protrusion used in the present invention. 1 is a protrusion that can move back and forth in the horizontal direction from the bottom of the shaft of the blast furnace to the furnace height of the morning glory part and the furnace center installed in each area divided into multiple areas in the circumferential direction, and 2 is a protrusion that can move back and forth in the horizontal direction , 3 is the iron shell, 4 is the inside of the furnace, and 5 is a driving device for the protrusion. FIG. 2 is a cross-sectional view taken along line A-A' in FIG. Each can be adjusted independently.

[0012] The protrusion 1 forms a thin stagnant layer near the furnace wall in an arbitrary range from the lower part of the shaft to the morning glory part, and the protrusion length of the projection and the furnace wall in an arbitrary range from the lower part of the shaft to the morning glory part are formed. The relationship between the nearby fall rate and the furnace wall temperature was determined. As shown in Fig. 4, it was found that the thickness of the stagnant layer in any range from the bottom of the shaft to the morning glory part increases approximately in proportion to the protruding length of protrusion 1 shown in Figs. 1 and 2. .

Based on the above findings, the present inventors came up with the idea that the thickness of the stagnant layer can be controlled by the protruding length of the protrusions. Then, in the furnace in the range from the bottom of the shaft to the morning glory section of the blast furnace model device, a horizontally driven type is installed at each range divided into a plurality of areas in the furnace height and the circumferential direction from the bottom of the shaft to the morning glory section of the method of the present invention. Protrusion 1 was installed. The protrusion 1 consists of several stages for each region divided into a plurality of regions in the furnace height and circumferential direction from the lower part of the shaft to the morning glory part.

As shown in FIG. 5, the protrusion length of the protrusion toward the inside of the furnace in any range of the furnace belly is set from 0 mm to 5 mm.
As a result, a stagnation layer with a thickness of 10 mm (actual furnace equivalent: 200 mm) is formed near the furnace wall, and a stagnation layer of 25 mm from the furnace wall is formed in an arbitrary range of the furnace belly. (Actual furnace conversion value: 500 mm) The descending speed and heat flow ratio of the charge are compared to when the protrusion length is 0 mm.
70% and 80%, respectively, and the furnace wall temperature in any range of the furnace belly was 15% lower than when the protrusion length was 0 mm.

Next, as a result of changing the protrusion length of the protrusion toward the inside of the furnace from 5 mm (actual furnace equivalent value: 100 mm) to 2.5 mm (actual furnace equivalent value: 50 mm), it was found that the The thickness of the stagnation layer near the furnace wall in the range of The descending speed and heat flow ratio return to levels of 80% and 85%, respectively, compared to when the protrusion length is 0 mm, and the furnace wall temperature in any range of the furnace belly is lower than when the protrusion length is 0 mm. The level has returned to 90% compared to the previous case.

[0016] From this, the method of the present invention can control the descending speed, heat flow ratio, and load of the charge near the furnace wall in an arbitrary range divided into a plurality of areas from the bottom of the shaft to the furnace height of the bosh section and the circumferential direction. It can be seen that the profile of the working surface on which the container descends can be controlled.

In an actual furnace, the range from the bottom of the shaft to the morning glory section is divided into 5 to 15 parts in the furnace height direction, and 8 to 1 parts in the circumferential direction.
Divided into 6 parts. A protrusion that can move forward and backward toward the center of the furnace is installed using a hydraulic or pneumatic drive device, and the protrusion length of the protrusion is set independently for each range divided into multiple areas in the furnace height and circumferential direction. By adjusting the lowering speed of the charge, the heat flow ratio, and the operation of lowering the charge from the bottom of the shaft to the furnace height of the morning glory section and the vicinity of the furnace wall in an arbitrary range divided into multiple areas in the circumferential direction. The surface profile can be controlled.

However, in reality, if a stagnation layer is formed near the furnace wall in the lower part of the furnace, it may grow into deposits.
The growth of deposits that narrows the descending area of the charge in the lower part of the furnace has a negative effect on the descending behavior of the charge. Signs that such a stagnant layer is growing into deposits can be determined by information such as a sudden drop in furnace wall temperature or stave temperature, so in that case, after setting the fuel ratio higher, , drive-type protrusions were installed independently in each range divided into multiple areas from the bottom of the shaft to the furnace height and circumferential direction of the morning glory area. By horizontally inserting it into the inside of the furnace within an arbitrary range, deposits can be quickly removed without significantly disturbing the operating conditions.

[0019]

Effects of the Invention As explained above, in the present invention, there are a plurality of areas near the furnace wall in the range from the bottom of the shaft to the morning glory section in the blast furnace, and from the bottom of the shaft to the furnace height of the morning glory section and in the circumferential direction. A protrusion that can move back and forth toward the center of the furnace is installed in each divided area, and the horizontal protrusion length of the protrusion in any range divided into multiple areas from the bottom of the shaft to the furnace height of the morning glory part and the circumferential direction. By adjusting each independently of can control the profile of the working surface on which it descends. Therefore, since the furnace condition can always be maintained in a stable state, it is possible to operate efficiently with a low fuel ratio and high iron production ratio, and at the same time, it is possible to extend the life of the blast furnace than before.

[Brief explanation of drawings]

[Figure 1] Conceptual diagram of protrusions used in the present invention

[Figure 2] AA' cross-sectional view in Figure 1

[Figure 3] Blast furnace model used in the present invention

[Figure 4] Graph showing the relationship between the protrusion length of the protrusion and the thickness of the furnace wall stagnation layer in any range from the bottom of the shaft to the morning glory part

FIG. 5 is a diagram showing the profile of the working surface where the charge falls, the rate of fall of the charge near the furnace wall, the heat flow ratio, and the changes in the furnace wall temperature according to the method of the present invention.

[Explanation of symbols]

1.Protrusions 2. Bricks and staves 3 Iron skin 4 Inside the furnace 5 Drive device

Claims (2)

[Claims] Claim 1: A protrusion that can be moved back and forth toward the center of the furnace is installed in the vicinity of the furnace wall in the range from the bottom of the shaft to the morning glory section in the blast furnace, divided into multiple parts in the furnace height and circumferential direction. By independently adjusting the horizontal protrusion length of the protrusions for each divided range, the descending speed and heat flow ratio of the charge near the furnace wall in any range in the furnace height and circumferential direction can be adjusted. A blast furnace operating method characterized by controlling. [Claim 2] A protrusion that can be moved back and forth toward the center of the furnace is installed in the vicinity of the furnace wall in the range from the bottom of the shaft to the morning glory section in the blast furnace, divided into a plurality of parts in the furnace height and circumferential direction. By independently adjusting the horizontal protrusion length of the protrusions for each divided range, the profile of the operating surface on which the charge descends in any range in the furnace height and circumferential direction is controlled. A blast furnace operating method characterized by: