JPH10298621A - Operation of blast furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for restraining the wearing of brick thickness by precisely detecting the wearing of the brick thickness in the side wall part of a furnace bottom at early time. SOLUTION: Heat flux from the inner part of the furnace to the outside direction of the furnace in the side wall part of the furnace bottom in a blast furnace is measured or calculated at one position or plural positions, and in the case of rising the heat flux to a reference value or more, blasting quantity of tuyere is adjusted with a blasting quantity control valve for branched tube. As the other way, the remaining thickness of the total of the brick and the high consistency layer in the side wall of the furnace bottom in the blast furnace is measured or calculated at one position or plural positions and in the case of lowering the remaining thickness to a reference value or less, the blasting quantity of the tuyere is adjusted with the branched tube blasting quantity control valve. As the other way, the heat flux from the inner part of the furnace at the center position of the furnace bottom in the blast furnace to the outside direction of the furnace is measured or calculated and in the case of lowering the heat flux to a reference value or less, the blasting quantity of the tuyere is adjusted with the branched tube blasting quantity control valve.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blast furnace operating method for detecting a worn state of a brick thickness of a furnace bottom side wall at an early stage and accurately and suppressing the brick thickness wear.

[0002]

2. Description of the Related Art In order to reduce the cost of hot metal in a blast furnace, it is necessary to reduce various variable costs and extend the life of the blast furnace as much as possible. The parts that control the furnace life of the blast furnace are the lower part of the shaft and the furnace bottom. In recent years, with the progress of repair technology, that is, the progress of stave replacement technology during a calm, the shaft portion is not necessarily a factor that limits the furnace life.

[0003] On the other hand, the technique of replacing the bricks at the time of the calm of the furnace bottom has not been established, and the thickness of the bricks at the furnace bottom, especially at the side walls of the furnace bottom, is a factor that determines the life of the furnace of the blast furnace. Is the current situation. Therefore, in order to extend the furnace life of the blast furnace as much as possible, from the viewpoint of hot metal resistance, molten slag resistance and cooling effect, technology to suppress the wear of bricks on the bottom wall of the furnace made of carbonaceous refractory At the same time, there is a need for a technique for quickly and accurately detecting and managing the thickness of the brick on the bottom wall of the furnace.

[0004] As a technique for detecting the thickness of the brick on the bottom wall of the furnace, the temperature at the tip (normal insertion depth: 50 to 100 mm) of a thermocouple inserted into the brick on the bottom wall of the furnace is measured. A method of estimating the remaining brick thickness from a value is known. When the temperature exceeds the upper limit value of the temperature corresponding to the lower limit value of the preset brick residual thickness, or when it is predicted to exceed, the furnace bottom side wall portion brick thickness wear suppression technology is applied. .

[0005] Furnace As a technique for suppressing wear of the bottom side wall of the brick thickness, furnace bottom methods watering amount increased to enhance the cooling, high viscosity hot metal present in the vicinity allowed hearth bricks increasing the TiO ₂ dosages Method to protect the furnace bottom brick by reducing the diameter of the tuyere at the point of wear to reduce or eliminate the amount of hot metal slag dripping in front of the tuyere, and hot air valves installed at each tuyere A method has been implemented in which the opening degree is adjusted to reduce the amount of hot metal slag dripped in front of the tuyere. In particular, it is empirically known that a method of reducing or eliminating the amount of hot metal slag dripping in front of the tuyere by reducing or blinding the tuyere diameter is empirically effective.

For example, Japanese Patent Application Laid-Open No. Sho 60-243207 discloses that a furnace bottom thermometer and a furnace bottom side plate thermometer are provided at a plurality of locations around the circumference of a blast furnace to measure the furnace bottom temperature and the furnace bottom side plate temperature. A method is disclosed in which, when any one of the furnace bottom temperature and the side plate temperature rises above a set value, the amount of the raised tuyere blast of the thermometer unit is controlled by a hot blast control valve installed in a blast branch pipe. I have.

[0007]

However, the above-described method of detecting the state of wear of the brick thickness of the furnace bottom side wall from the brick temperature of the furnace bottom side wall has the following problems. The temperature of the brick at the tip of the thermocouple inserted into the bottom wall of the furnace bottom is determined not only by the heat state inside the furnace, but also by the cooling conditions (eg, cooling water temperature difference depending on the season) It is easily affected by changes.

For example, the temperature of the brick at the tip of the thermocouple inserted in the bottom wall of the furnace changes depending on the difference between the cooling water temperature in summer and the temperature in winter. In particular, in a blast furnace where the thermophysical property value of the stamp material changes greatly due to the deterioration state of the stamp material, when estimating the remaining brick thickness or the total remaining thickness of the brick and the viscous layer from the brick temperature value at the thermocouple tip Error increases. In the above method, there is a possibility that the life of the blast furnace may be shortened due to an erroneous or delayed control means execution time due to an error in the remaining brick thickness.

The present invention has been made in view of such a conventional problem of a time delay in detection caused by an error in the thickness of the brick at the bottom wall of the furnace due to the temperature indication value at the tip of the thermocouple inserted into the brick at the bottom wall of the conventional furnace. By using a method different from the detection method based on the brick temperature indicating value of the hearth side wall portion, by detecting the wear state of the brick on the hearth side wall portion early and accurately, the object is to solve the above problems. I have.

[0010]

According to the present invention, the following means are taken to solve the above-mentioned problems. (1) Measure or calculate the heat flux from the inside of the furnace to the outside of the furnace at the bottom wall of the blast furnace at one or a plurality of locations, and when the heat flux rises above the reference value, reduce the amount of air blown from the tuyere. It is characterized by being adjusted by a branch pipe air flow control valve. (2) In (1), the air flow rate of one or a plurality of tuyeres out of the tuyeres located within at least ± 30 ° in the circumferential angle of the place where the heat flux rises above the reference value. Is controlled by a branch pipe air flow control valve.

(3) The air flow rate of the tuyere is adjusted by the method of (1) or (2), and when the heat flux falls below the reference value, the air flow rate of each tuyere is adjusted by the branch air flow rate control valve. Is returned to be substantially the same value. (4) Measure or calculate the remaining thickness of the brick and viscous layer total at one or more locations on the bottom wall of the blast furnace, and when the remaining thickness falls below the reference value, determine the airflow from the tuyere A blast furnace operating method characterized by adjusting by a control valve.

[0012] In (5) and (4), at least ±± the angle in the circumferential direction of the location where the remaining thickness is reduced below the reference value.
The air flow rate of one or more of the tuyeres located within 30 ° is adjusted by a branch pipe air flow control valve. (6) The air flow rate of the tuyere is adjusted by the methods of (4) and (5), and when the remaining thickness rises above the reference value, the air flow rate of each tuyere is substantially the same by the branch pipe air flow control valve. It is characterized by returning to a value.

(7) The heat flux from the inside of the furnace to the outside of the furnace at the center position of the blast furnace hearth is measured or calculated, and when the heat flux falls below the reference value, the amount of air blown from the tuyere is changed to the branch air flow. It is characterized by being adjusted by a control valve. (8) Measure or calculate the heat flux from the inside of the furnace to the outside of the furnace at the center of the blast furnace bottom, and when the heat flux falls below the reference value, the total of the brick and viscous layer on the side wall of the furnace bottom Is characterized in that the amount of air blown through the tuyere above the portion where the remaining thickness has become equal to or less than the reference value in the past is adjusted by the branch pipe air volume control valve.

(9) The heat flux from the inside of the furnace to the outside of the furnace at the center position of the blast furnace bottom is measured or calculated. The amount of air blown to the upper tuyere at a location where the total thickness of the dense layer is relatively thin or at a location where the rate of reduction of the remaining thickness is large is adjusted by a branch pipe air volume control valve. (10) The flow rate of the tuyere is adjusted by the method described in any one of (7) to (9), and the heat flux from the inside of the furnace to the outside of the furnace at the center position of the blast furnace bottom exceeds the reference value. In this case, when the air flow rate rises, the air flow rate of each tuyere is returned to substantially the same value by the branch air flow rate control valve.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The temperature of a brick at the tip of a thermocouple inserted into a brick on a conventional furnace bottom side wall is detected, and when the temperature exceeds a temperature upper limit value corresponding to a lower limit brick remaining thickness, a furnace bottom side wall is detected. In contrast to the method of judging that the brick wear of the furnace part is progressing, the method of the present invention detects the brick wear state of the furnace bottom side wall at an early stage with high accuracy, and before the furnace bottom side wall brick is worn or the brick wear state. In the initial stage of the above, brick wear on the furnace bottom side wall is suppressed. There are several methods for early and accurate detection of the brick wear state on the furnace bottom side wall.

The first method is a method of measuring or calculating the heat flux from inside the furnace to outside the furnace on the bottom wall of the blast furnace.
Heat flux is the amount of heat transfer per unit area per unit time
(kW / m ² ) and is defined by the following equation (1). Q = ΔT × λ / L (1) where Q is the heat flux (kW / m ² ), ΔT is the temperature difference between two points (° C.), and λ is the thermal conductivity of the material between the two points ( kW / (m · K)) L is the distance (m) between two points.

According to the one-dimensional steady-state heat transfer analysis, the change in heat flux at the same position as the change in the brick temperature at the tip of the thermocouple due to the difference in the cooling water temperature between summer and winter, and the tip of the thermocouple before and after the deterioration of the stamp material Compare the change in heat flux at the same position with the change in brick temperature. The basic formula is shown in the following formula (2). d ² T / dx ² = 0 (2) where T is a temperature (° C.) x is a position (m).

FIG. 1 shows boundary conditions in a calculation example. The thickness of steel skin, stamp material, brick, viscous layer is 60m each
m, 100 mm, 700 mm, and 100 mm, and the brick insertion position of the thermocouple was assumed to be 150 mm from the outer surface of the brick. In addition,
The thermal conductivity of the iron shell, stamp material, brick, and viscous layer was assumed to be 6, 16, 29, and 52 (W / (m · K)), respectively. The inside temperature of the viscous layer is assumed to be 1150 ° C, and the cooling water temperature is 30 ° C.
Calculation was performed assuming that the temperature was 35 ° C, 35 ° C, and 25 ° C. The effect of the deterioration of the stamp material was calculated on the assumption that a gap of 1 mm occurred between the stamp material and the steel.

[0019]

[Table 1]

Table 1 shows the results of the one-dimensional steady-state heat transfer analysis. As apparent from Table, the absolute value of the relative change in the brick temperature T ₂ by the cooling water temperature difference summer (35 ° C.) and winter (25 ℃), 2.4% ( = | (297-290) / 290 × 100 |), The absolute value of the relative change in heat flux is 0.9% (= | (16.71-16.86) /16.86×100 |)
The absolute value of the relative change of the heat flux is smaller than the absolute value of the relative change of the brick temperature, and the error is smaller when detecting and managing the brick wear state with the heat flux.

Further, when a gap of 1 mm is formed between the stamp material and the steel bar, the absolute value of the relative change in the brick temperature is 9
0.1% (= | (557-293) / 293 × 100 |), relative change of heat flux is 30.8% (= | (11.62-16.78) /16.78×100 |), and relative change of heat flux is brick temperature It is overwhelmingly small compared to the relative change of, and the error is smaller when detecting and managing the brick wear state with the heat flux.

More importantly, when judging from the heat flux, the influence of the growth of the viscous layer or the deterioration of the stamp material can be easily estimated. Is not implemented. However, when judging from the temperature, it is not possible to easily judge the effect of the inside of the furnace, that is, the effect of brick wear or the effect of stamp material deterioration, and from the standpoint of the safety side of protecting the furnace bottom side wall brick, Measures to control excessive brick wear (eg, increase in fuel ratio, temporary shutoff, wind reduction, blindness of tuyere, etc.) may be implemented, which may result in significant reduction in production and operational fluctuations. is there.

Next, a one-dimensional unsteady heat transfer analysis is used to compare the time change of the heat flux and the temperature with respect to the step response change in the furnace. The basic equation is shown in the following equation (3). ∂T / ∂t = α∂ ² T / ∂x ² (3) where T is temperature (° C) x is position (m) t is time (h) α is temperature conductivity (m ² / h). At the time of this calculation, at some point the viscous layer peeled off,
Assuming that the brick surface reached 1150 ° C, the change of heat flux and temperature at the bottom wall of the furnace from that point was calculated.

As shown in FIG. 2, the time derivative of the heat flux rises sharply from about one hour earlier than the time derivative of the temperature. Therefore, when judging by heat flux,
It can be seen that, in addition to the good estimation accuracy of the brick thickness wear state described above, the brick thickness wear state can be detected earlier than the temperature. As means for measuring the heat flux, there are a method of measuring with a heat flux meter, a method of calculating from the temperatures of thermocouple tips of different depths inserted in the brick in the furnace bottom side wall in the radial direction, and the like. The heat flux meter can be embedded not only in the steel skin but also in the outer surface of the brick or in the brick.

If the heat flux rises above the reference value,
Among the tuyeres located within at least ± 30 ° of the circumferential angle of the place where the heat flux has risen to the reference value or more, the blowing amount of one or more tuyeres is relatively reduced. As the method, either the opening degree of the tuyere air flow control valve at the tuyere at the location is reduced, or the opening degree of the branch pipe air flow control valve at the tuyere at a location other than the location is increased. Adjust the air volume by using According to the above method, when the heat flux becomes less than the reference value, the flow rate of each tuyere is adjusted to be substantially the same value by the branch air flow control valve, and the operation is returned to the normal operation.

The second method is to measure or calculate the remaining thickness of the total of the brick and the viscous layer on the bottom wall of the blast furnace. The viscous layer is a solidified layer inside the furnace, and is determined from the temperature in the furnace of 1100 ° C to 1200 ° C in the heat transfer calculation. As a means for measuring the residual thickness, there are a method of measuring by an elastic wave and a method of calculating from a temperature difference between thermocouple tips at different depths inserted in the brick in the furnace bottom side wall in the radial direction.

When the remaining thickness falls below the reference value, one or more of the tuyeres located within ± 30 ° of the circumferential angle of the place where the remaining thickness falls below the reference value. Of the tuyere is relatively reduced. As the method, either the opening degree of the tuyere air flow control valve at the tuyere at the location is reduced, or the opening degree of the branch pipe air flow control valve at the tuyere at a location other than the location is increased. Adjust the air volume by using When the remaining thickness rises above the reference value by the above method, the flow rate of each tuyere is adjusted by the branch air flow rate control valve to be substantially the same value, and the operation is returned to the normal operation.

The third method is a method of measuring or calculating the heat flux from the inside of the furnace to the outside of the furnace at the center of the blast furnace bottom. In this method, based on the conventional knowledge that the brick temperature on the bottom wall of the furnace rises after the heat flux from the inside of the furnace at the center of the blast furnace bottom to the outside of the furnace changes at a low level, 1 to 3 from the heat flux from inside the furnace to outside the furnace
Predict the state of brick wear on the bottom wall after a month.
As a means for measuring the heat flux, a method of measuring with a heat flux meter embedded in the outer surface of the brick or in the brick, a temperature difference between thermocouple tips of different depths inserted in the depth direction in the brick at the center of the furnace bottom. There is a method to calculate from.

When the heat flux falls below the reference value,
Where the residual thickness of the brick and viscous layer total on the hearth side wall part was below the reference value in the past, or the residual thickness of the brick on the hearth side wall part or the residual thickness of the brick and viscous layer total is relatively It reduces the amount of air blown from the tuyere above the thinner part, the part where the remaining thickness decreases at a high rate, or any of these parts. As the method, either the opening degree of the tuyere air flow control valve at the tuyere at the location is reduced, or the opening degree of the branch pipe air flow control valve at the tuyere at a location other than the location is increased. Adjust the air volume by using According to the above method, when the heat flux from the inside of the furnace to the outside of the furnace at the center of the furnace bottom rises above the reference value, the blower air flow control valve adjusts the flow rate of each tuyere to substantially the same value. And return to normal operation.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a specific description will be given based on embodiments shown in the drawings. (Example 1) 29 pieces of medium-sized blast furnace wings talkative in internal volume of 3000 m ³ grade, the heat flux from the furnace in the blast furnace bottom side wall portion to the outside the furnace direction measured at six locations, the heat flux of a portion The heat flux rises at the same time as the time derivative of
00W / m ² or more. Therefore, it is predicted that brick wear on the bottom wall of the furnace will progress, and the amount of air blown from tuyeres located within ± 30 ° in the circumferential angle of the place where the heat flux has risen above the reference value will be installed in the blower branch pipe. The control was started by the branch pipe air flow control valve.

As shown in FIG. 3, the flow rate of air from the five tuyeres located within ± 30 ° in the circumferential direction at the point where the heat flux has risen to the reference value or more is determined by controlling the air flow in the branch pipe over the entire circumference. By adjusting the valve, the average amount of tuyere blown by dividing the amount of blown air by the number of tuyeres is 10
Control was performed so that the relative tuyere ventilation rate was 0% or less and 70% or less. The number of tuyeres located within ± 30 ° of the circumferential angle is the total number of tuyeres in the blast furnace (depending on the internal volume of the blast furnace)
Of the blast furnaces, five were found.

After this action was continued for one week, the heat flux on the bottom wall of the blast furnace started to decrease, and after 10 days, it fell below the reference value. After a further 5 days, the relative tuyere airflow of the five tuyeres at the top of the ascending point is controlled by the branch pipe airflow control valve so as to be 80%. The tuyere's relative tuyere airflow is controlled by the branch pipe airflow control valve so that the tuyere's relative tuyere airflow becomes 90%.
Returned to 100%. As a result, 30 days after the heat flux at the furnace bottom side wall increased and exceeded the reference value, the heat flux at the furnace bottom side wall calmed down and returned to almost the original level.

FIG. 4 shows a conventional method, that is, the position of the tip of a thermocouple inserted into a brick on the side wall of the furnace bottom (normal insertion depth:
Measure the brick temperature at 50 to 100 mm), and if the measured temperature approaches the upper limit set in advance or exceeds the upper limit, suppress the above-described wear of the furnace bottom side wall brick. Although the case where the countermeasure was implemented was shown, the implementation of the measure for suppressing the brick abrasion is more difficult than the case where the method of the present invention is implemented due to the problem of accuracy and sensitivity of the temperature measurement value.
It can be as late as a few hours to an entire day. The delay in the implementation of the measures for suppressing brick wear may have a fatal effect on the progress of brick wear on the furnace bottom side wall.

[0034] (Example 2) internal volume is feather number of units in the ^tertiary 4000m
In a large blast furnace 11 years after 35 burns, the residual thickness including the viscous layer on the bottom wall of the blast furnace was measured at four locations, and the residual thickness at one location was below the standard value of 700 mm. Therefore, it is predicted that brick wear on the bottom wall of the furnace will progress, and the amount of air from the tuyere located within ± 30 ° in the circumferential angle of the place where the remaining thickness has fallen below the reference value will be installed in the air duct. The control was started by the branch pipe air flow control valve.

As shown in FIG. 5, the angle in the circumferential direction is ± 3.
Blower air volume control so that the relative volume of the tuyere is less than 70% with the average volume of the tuyere divided by the number of tuyeres being 100% of the volume of air from six tuyeres located within 0 ° Controlled by a valve. The number of tuyeres within ± 30 ° of the circumferential angle of the place where the remaining thickness has dropped below the reference value is the total number of tuyeres in the blast furnace (depending on the internal volume of the blast furnace), Were six places.

After this action was continued for one week, the remaining thickness of the portion where the remaining thickness was reduced started to increase, and after 10 days, the value exceeded the reference value. After a further 5 days, the relative tuyere airflow of the six tuyeres above the remaining thickness-reduced portion was controlled by a branch pipe airflow control valve so as to be 80%. The relative amount of the tuyere at the six points at the lowered point is controlled by a branch pipe air flow control valve so as to be 90%. The tuyere blowing volume was returned to 100%. As a result, 30 days after the residual thickness including the viscous layer on the bottom wall of the blast furnace decreased below the reference value, the residual thickness including the viscous layer on the high side wall portion was almost the original. Back to level.

(Example 3) The inner volume is 5000m ³ class and the number of tuyeres
In 38 large blast furnaces, the heat flux from the inside of the furnace to the outside of the furnace at the center of the blast furnace bottom was measured at one point, and the heat flux was below the standard value of 700 W / m ² . One month after that point, it was determined that a viscous layer had developed on the bottom of the blast furnace, and there was a danger that the flow of the melt at the bottom of the furnace would flow toward the annular flow. If the flow of the melt at the bottom of the furnace goes to the annular flow, it is predicted that brick wear on the bottom wall of the furnace will progress, and where the remaining thickness including the viscous layer on the bottom wall of the furnace has fallen below the reference value in the past. The air flow rate of the three tuyeres at the upper part was adjusted by a branch air flow control valve installed on the air blow branch pipe.

More specifically, as shown in FIG. 6, the relative tuyere airflow control valve is set so that the average tuyere airflow obtained by dividing the airflow by the number of tuyeres is 100% and the relative tuyere airflow control valve is 70% or less. Adjusted by Twenty days after the action was taken, the heat flux at the center of the hearth first started to increase, and after 10 days, it exceeded the standard value. Then, at that time, the heat flux of the furnace bottom side wall, which once started rising, also started to fall.

After a lapse of 10 days, the relative tuyere ventilation rate of the upper two or three tuyeres above the places where the residual thickness including the viscous layer became below the reference value in the past was reduced to 80%. It is adjusted by a branch pipe air flow control valve so that after 10 days, the relative thickness of the upper two or three upper tuyeres of the upper part where the residual thickness including the viscous layer has become below the reference value in the past. The tuyere blowing volume was returned to 100%. As a result, 50 days after the heat flux from the inside of the furnace at the center of the hearth to the outside of the furnace fell below the reference value, the heat flux from the inside of the furnace at the center of the hearth to the outside of the furnace decreased. It rose and returned to almost its original level.

When the method of the present invention was carried out, the temperature of the brick at the tip position (normal insertion depth: 50 to 100 mm) of the thermocouple inserted into the brick on the bottom wall of the furnace was measured by the conventional method. When the temperature measurement value approaches the upper limit set in advance, or when the temperature exceeds the upper limit, the brick temperature of the bottom wall of the hearth when the above-described measures to suppress the wear of the bottom wall of the hearth are performed. Are shown in FIG.

In the case of implementing the method of the present invention, since the state of brick wear on the bottom wall of the furnace is predicted earlier than in the case of implementing the conventional method, the time for implementing the measures is earlier. For this reason, the rise level of the brick temperature on the furnace bottom side wall is small, and the time required for the brick temperature on the furnace bottom side wall to fall to the original level after the countermeasure is taken is shorter than in the conventional method.

[0042] (Example 4) internal volume is feather number of units in the ^tertiary 5000m
In 38 large blast furnaces, the heat flux from the inside of the furnace to the outside of the furnace at the center of the blast furnace bottom was measured at one point, and the heat flux was below the standard value of 700 W / m ² . One month after that point, it was determined that a viscous layer had developed at the bottom of the blast furnace, and there was a danger that the flow of the melt at the bottom of the furnace would flow toward the annular flow. If the flow of the melt at the bottom of the furnace goes to an annular flow, it is predicted that brick erosion on the bottom wall of the furnace will progress, and the remaining thickness including the viscous layer on the bottom wall of the furnace is relatively thin at the moment. The airflow at the upper tuyere at the minimum and second and third smallest locations was adjusted by a branch pipe airflow control valve installed in the ventilation branch pipe.

As shown in FIG. 8, the relative tuyere airflow was adjusted by the branch airflow control valve so that the relative tuyere airflow was 70% or less, with the average airflow being the airflow divided by the number of tuyeres being 100%. Twenty days after this action was taken, the heat flux in the center of the hearth began to rise first, and after 10 days, exceeded the standard value. At that time, the heat flux on the bottom wall of the furnace, which had once started to rise, also began to fall.

After a further 10 days have passed, at the point where the remaining thickness including the viscous layer is relatively thin at the present time, the relative tuyere airflow at the top of the minimum, second and third smallest points is calculated. It is controlled by the branch pipe air flow control valve so that it becomes 80%, and after further 10 days,
The relative tuyere blow rate at the top of the portion where the remaining thickness was the smallest and the second and third smallest was returned to 100%. As a result, 50 days after the heat flux from the inside of the furnace at the center of the hearth to the outside of the furnace fell below the reference value, the heat flux from the inside of the furnace at the center of the hearth to the outside of the furnace decreased. It rose and returned to almost its original level.

When the method of the present invention was carried out, the brick temperature was measured at the tip position (normal insertion depth: 50 to 100 mm) of the thermocouple inserted into the brick on the bottom wall of the furnace. When the temperature measurement value approaches the upper limit set in advance, or when the temperature exceeds the upper limit, the brick temperature of the bottom wall of the hearth when the above-described measures to suppress the wear of the bottom wall of the hearth are performed. 9 is shown in FIG.

In the case of implementing the method of the present invention, since the state of brick wear on the bottom wall of the furnace is predicted earlier than in the case of implementing the conventional method, the implementation time of the countermeasure is earlier. For this reason, the rise level of the brick temperature on the furnace bottom side wall is small, and the time required for the brick temperature on the furnace bottom side wall to fall to the original level after the countermeasure is taken is shorter than in the conventional method.

[0047]

According to the method of the present invention, which is different from the conventional method for detecting the remaining thickness of the bricks on the bottom wall of the furnace based on the indicated brick temperature, the state of wear of the bricks on the bottom wall of the furnace is detected quickly and accurately. By adjusting the branch pipe air flow control valve of a tuyere or a plurality of tuyeres with a high degree of brick wear or a high brick wear rate, compared to the conventional method of detecting brick temperature and taking countermeasures, The situation in which the brick temperature of the furnace bottom side wall portion is greatly increased due to the progress of brick wear can be prevented. As a result, it has become possible to avoid a situation in which a significant reduction in production over a long period of time and an increase in hot metal cost due to measures for suppressing brick wear on the bottom wall of the furnace are taken.

[Brief description of the drawings]

FIG. 1 is a diagram showing boundary conditions at the time of heat transfer calculation.

FIG. 2 is a diagram showing a comparison of a time derivative of a heat flux and a temperature with respect to a step response change in a furnace by a one-dimensional transient heat transfer analysis.

FIG. 3 is a diagram showing a change in the heat flux from the inside of the furnace to the outside of the furnace at a certain place of the bottom wall of the furnace before and after the method of the present invention is performed, and a change in the relative amount of the tuyere of the tuyere in which the action is performed.

FIG. 4 is a diagram showing a comparison between the implementation timings of the brick wear reduction measures when the present invention method is implemented and when the conventional method is implemented.

FIG. 5 is a diagram showing a transition of a remaining thickness including a viscous layer of a furnace bottom side wall portion at a certain place before and after the method of the present invention is performed, and a transition of a relative tuyere blowing amount of a tuyere where an action is performed.

FIG. 6 shows the transition of the heat flux from the inside of the furnace to the outside of the furnace at the center of the furnace bottom before and after the method of the present invention and the tuyere at the upper portion where the residual thickness including the viscous layer has become below the reference value in the past. Figure showing changes in relative tuyere airflow

FIG. 7 is a diagram showing a comparison between the implementation timing of the brick wear prevention measure when the method of the present invention is performed and the conventional method.

FIG. 8 shows the transition of the heat flux from the inside of the furnace at the center of the furnace bottom to the outside of the furnace before and after the method of the present invention and the two upper blades at the point where the remaining thickness including the viscous layer is currently at a minimum. Diagram showing transition of relative tuyere ventilation volume at the mouth

FIG. 9 is a diagram showing a comparison between the implementation timing of the brick wear prevention measure when the method of the present invention is performed and the conventional method.

[Explanation of symbols]

 1. 1. viscous layer Brick 3. Stamp material 4. Iron skin 5. 5. Insertion position of thermocouple 6. Furnace (hot metal, slag) Watering section

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takashi Kumaoka 1 Kimitsu, Kimitsu-shi, Chiba Nippon Steel Corporation Kimitsu Works (72) Inventor Kazuyuki Morii 2-6-3 Otemachi, Chiyoda-ku, Tokyo Nippon Steel Corporation

Claims (10)

[Claims] 1. Measurement or calculation of the heat flux from the inside of the furnace to the outside of the furnace at the bottom wall of the blast furnace at one or a plurality of places, and when the heat flux rises above a reference value, the amount of air blown from the tuyere Is controlled by a branch pipe air flow control valve. 2. The air flow control of one or a plurality of tuyeres, among the tuyeres located at least within ± 30 ° of the circumferential angle of the place where the heat flux rises above the reference value, is a branch pipe airflow control. The blast furnace operating method according to claim 1, wherein the blast furnace is adjusted by a valve. 3. A method according to claim 1, wherein the amount of air blown to the tuyere is adjusted by adjusting the amount of air blown to the tuyere when the heat flux falls below a reference value. A blast furnace operation method characterized by returning the values to approximately the same value. 4. A method for measuring or calculating the remaining thickness of the brick and the viscous layer on the bottom wall of the blast furnace at one or a plurality of locations and, when the remaining thickness falls below a reference value, determines the amount of air blown from the tuyere. A blast furnace operating method characterized in that the blast furnace is adjusted by an air flow control valve. 5. A branch pipe air volume control for one or a plurality of tuyeres, among the tuyeres located at least within ± 30 ° in a circumferential angle of a location where the remaining thickness is reduced below a reference value. The blast furnace operating method according to claim 4, wherein the adjustment is performed by a valve. 6. A method according to claim 4 or 5, wherein the amount of air blown from each tuyere is adjusted by a branch pipe airflow control valve when the remaining thickness rises above a reference value. A blast furnace operation method characterized by returning the values to approximately the same value. 7. A method for measuring or calculating the heat flux from the inside of the furnace to the outside of the furnace at the center position of the blast furnace hearth, and when the heat flux falls below a reference value, adjusts the amount of air blown from the tuyere to a branch pipe air flow control valve. Blast furnace operation method characterized by adjusting by. 8. A method for measuring or calculating the heat flux from the inside of the furnace to the outside of the furnace at the center position of the blast furnace bottom, and when the heat flux falls below a reference value, the bricks and the viscous layer on the side wall of the furnace bottom. A method for operating a blast furnace, comprising: adjusting a blowing amount of a tuyere above a portion where a total remaining thickness has become equal to or less than a reference value in the past by a branch pipe air flow control valve. 9. A method for measuring or calculating the heat flux from the inside of the furnace to the outside of the furnace at the center position of the blast furnace bottom, and when the heat flux falls below a reference value, bricks and a viscous layer on the side wall of the furnace bottom. A method for operating a blast furnace, characterized in that the amount of air blown from the tuyere above the portion where the total remaining thickness is relatively thin or where the rate of reduction of the remaining thickness is large is adjusted by a branch air flow control valve. 10. The method according to claim 7, wherein the amount of air blown from the tuyere is adjusted so that the heat flux from the inside of the furnace to the outside of the furnace at the center of the blast furnace bottom exceeds the reference value. A method for operating a blast furnace, comprising: returning a flow rate of each tuyere to substantially the same value by a branch pipe flow rate control valve when the temperature rises.