JP2001011512A - Detection of deteriorated position of monolithic refractory at furnace bottom part in blast furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a detecting method of the deteriorated position of a monolithic refractory lined between a refractory brick and an iron shell at the side wall part of a furnace bottom in a blast furnace. SOLUTION: In the side wall part of the furnace bottom in the blast furnace constituted with the refractory brick, monolithic refractory and iron shell in order from the inside of the furnace, when detecting the temp. rising rates shown with two thermocouples at operational positions and at the same position in the blast furnace circumferential direction among plural thermocouples embedded at an interval in the blast furnace diameter direction of the refractory bricks, and when using dTi for the temp. rising rate shown with the thermocouple at the inside of the furnace and dTj for the temp. rising rate shown with the thermocouple at the monolithic refractory side, if these temp. rising rates of dTi and dTj satisfy dTi<dTj, it is decided that the monolithic refractory at the same position in the blast furnace circumferential direction is deteriorated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting a deteriorated portion of an irregular shaped refractory in a blast furnace bottom.

[0002]

2. Description of the Related Art Conventionally, when the temperature of refractory bricks rises excessively at the bottom wall of a blast furnace made of refractory bricks, irregular refractories and iron shells from the inside of the furnace, the refractory bricks are cooled. Measures such as increasing the amount of cooling water in the steel shell and lowering the water temperature are being implemented.

[0003] However, the amorphous refractory between the refractory brick and the iron shell is deteriorated, and the formation of an air layer becomes remarkable, and the cooling ability of the iron shell is reduced due to the heat insulating effect of the air layer. In fact, a sufficient cooling effect cannot be obtained.

[0004] In addition, since the amorphous refractory is heated from the refractory brick side, cooled from the steel shell side and constantly exposed to thermal stress of expansion and contraction, it is in an environment where cracks and the like are liable to deteriorate. When cracks or the like occur, air having low thermal conductivity is mixed into the amorphous refractory having a dense structure at the beginning, and the thermal conductivity of the entire amorphous refractory decreases.

In order to eliminate the air layer, it is necessary to repair the deteriorated amorphous refractory, but there is a problem that the deteriorated portion of the amorphous refractory cannot be specified accurately. Since the deteriorated part of the irregular-shaped refractory cannot be identified, it is necessary to repair the entire bottom of the blast furnace in the circumferential direction of the blast furnace, resulting in inefficient repair work. Therefore, there is a problem that the production amount is reduced, and therefore, improvement is required.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for detecting a deteriorated portion of an irregular refractory between a refractory brick and a steel shell on a bottom wall of a blast furnace.

[0007]

The present inventors have obtained the following findings. (A) A pair of thermocouples at three or more locations in the blast furnace radial direction are installed at a plurality of locations in the blast furnace circumferential direction in the refractory brick on the bottom wall of the blast furnace, and the amount of temperature change of each thermocouple in the blast furnace radial direction is measured. When the thermal load of the refractory brick of the blast furnace rises, the temperature of the thermocouple installed in the blast furnace radial direction rises.

[0008] The meaning that the heat load of the refractory brick increases includes not only the temperature rise in the furnace, but also the wear of the refractory brick or the peeling of the viscous layer (the layer in which the molten iron is solidified).

[0009] Further, in the initial process from when the thermal load rises to when thermal equilibrium is reached, the temperature change per unit time (hereinafter also referred to as the temperature rise rate) tends to be larger for the thermocouple inside the furnace. is there.

(B) Even when an air layer is formed in the amorphous refractory, the temperature of the thermocouple installed in the radial direction of the blast furnace rises.

However, it has been newly found that the temperature rise rate of the thermocouple inside the furnace tends to be smaller.

[0012] By checking in the circumferential direction of the blast furnace a position where the temperature rise rate of each thermocouple becomes smaller toward the inside of the furnace, and repairing the irregular refractory at the position in the circumferential direction of the blast furnace preferentially, the repair cost can be reduced. The blast furnace downtime can also be minimized.

The present invention has been made based on the above findings, and the gist thereof is as follows.

In the bottom wall of the blast furnace, which is composed of a refractory brick, an amorphous refractory and a steel shell in order from the inside of the furnace, the refractory bricks are embedded at the same position in the blast furnace circumferential direction at intervals in the blast furnace radial direction. 2 of arbitrary positions among multiple thermocouples
The temperature rising rate of the thermocouples on the inside of the furnace is dTi, and the temperature rising rate of the thermocouple on the amorphous refractory side is dTj.
When the temperature rise rate of j satisfies dTi <dTj, it is determined that the amorphous refractory at the same position in the circumferential direction of the blast furnace is deteriorated. Method.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION One set of thermocouples at two or more locations
A thermocouple set is also installed on the refractory brick on the bottom wall of the blast furnace in the blast furnace radial direction, and a plurality of thermocouples are installed in the circumferential direction of the blast furnace.

A method for embedding a thermocouple and a method for detecting the deterioration of the irregular shaped refractory at the bottom of a blast furnace will be described below with reference to conceptual diagrams.

FIG. 1 shows a blast furnace bottom wall composed of a refractory brick 1, an irregular refractory 2 and a steel shell 3 from the inside of the furnace.
To n, the distance from the outer surface of the steel shell and the temperature Tl at each point.
~ Tn, and the temperature rise rate dT when the temperature changes
It is a conceptual diagram which shows l-dTn.

When the thermal load on the refractory brick 1 rises, the temperatures Tl to Tn of each of the n thermocouples 4 in the radial direction of the blast furnace rise.

As shown by the dotted line in FIG. 1, in the initial process in which the thermal load of the refractory brick 1 rises and reaches thermal equilibrium, the temperature change rates dTl to dTn of each thermocouple 4 are dTl>dT2>.
--->dTn-1> dTn. It should be noted that the length of the triangle in the figure conceptually indicates the level of the temperature rise rate.

When an air layer is formed in the amorphous refractory, the temperatures Tl to Tn of the thermocouples also tend to increase, but the temperature change rates of the thermocouples differ from the above.

As shown by the dashed line in FIG. 1, in the initial stage of reaching thermal equilibrium, the temperature rise rate of each thermocouple 4 is low inside the furnace, and the temperature change rate dTl to dTn of each thermocouple is dTl.
1 <dT2 <−− <dTn−1 <dTn.

By grasping the changing tendency of the temperature rising rate of each thermocouple 4 in the initial process of reaching the thermal equilibrium indicated by the dotted line and the dashed line in FIG. Of the blast furnace in the circumferential direction can be estimated.

That is, of the n thermocouples embedded in the blast furnace at intervals in the blast furnace radial direction of the refractory brick, the thermocouple inside the furnace indicates the temperature rise rate indicated by the two thermocouples at an arbitrary position. Assuming that the temperature rise rate is dTi and the temperature rise rate indicated by the thermocouple on the amorphous refractory side is dTj, these dTi,
When the temperature rise rate of dTj satisfies dTi <dTj, it can be determined that the amorphous refractory at the same position in the circumferential direction of the blast furnace has deteriorated.

For example, assuming that the temperature rise rate indicated by the thermocouple 1 inside the furnace is dTi, it corresponds to the temperature rise rate dTj indicated by any thermocouple on the amorphous refractory side among the thermocouples 2 to n.

The temperature rise rate indicated by the thermocouple 2 inside the furnace is represented by d
If it is Ti, it corresponds to the temperature rise rate dTj indicated by any thermocouple on the amorphous refractory side among the thermocouples 3 to n.

The number of thermocouples to be installed is preferably about 2 to 10 because it is not only complicated to install thermocouples more than necessary, but also a problem in terms of maintenance.

The more the thermocouple sets are installed in the circumferential direction of the blast furnace, the more precise repair of irregular shaped refractories becomes possible.
Similar to the blast furnace radial direction, even if thermocouples are installed more than necessary, it is not only complicated but also a problem from the viewpoint of maintenance.

The installation intervals of the thermocouples in the radial direction of the blast furnace are preferably equal. It is desirable that the installation intervals of the thermocouple sets in the circumferential direction of the blast furnace are also equal.

[0029]

2 and 3 are graphs showing the transition of the temperature inside the refractory brick and the transition of the temperature change rate when the temperature inside the furnace is increased in the same blast furnace at two locations in the circumferential direction of the blast furnace.

At the two locations in the circumferential direction of the blast furnace (hereinafter referred to as locations A and B), three thermocouples (numbers 1, 2 and 3 from the inside of the furnace) were placed in the refractory brick in the radial direction of the blast furnace. Pairs), and measure the temperatures T1, T2, and T3 with the respective thermocouples, and measure the temperature rise rates dT1, dT of the respective thermocouples.
T2 and dT3 (° C./h) were calculated.

FIG. 2 is an example of a graph showing each temperature at a certain location A in the blast furnace circumferential direction when the temperature in the blast furnace rises, and the temperature rise rate (° C./h).

As shown in the figure, when the temperature in the furnace rises and the thermal load on the refractory brick rises, the temperature change rate of each thermocouple at the location A in the initial process (encircled portion in the figure) when thermal equilibrium is reached. dT1, dT2 and dT3 are dTl>dT2>
dT3.

It was determined that this result was not due to deterioration of the amorphous refractory. FIG. 3 is an example of a graph showing each temperature at a certain location B in the circumferential direction of the blast furnace when the temperature inside the blast furnace rises, and the temperature rising rate (° C./h).

As shown in the figure, when the temperature in the furnace rises and the thermal load on the refractory bricks rises, the temperature change rate dT1 of each thermocouple at the location B in the initial process (encircled portion in the figure) when thermal equilibrium is reached. , DT2 and dT3 are: dTl <dT2 <
dT3.

After the temperatures at the locations A and B in the circumferential direction of the blast furnace increased and the temperature became steady, the blast furnace was stopped, and the irregular refractories at the locations A and B were repaired.

However, at the location A, it was found that no air layer was found in the irregular-shaped refractory, and it was not necessary to repair it.
On the other hand, at the location B, an air layer was confirmed on the irregular-shaped refractory, and repair was performed.

After the start of the blast furnace, it was observed that the temperature of the refractory brick at the location B decreased. From this result, it was found that the amorphous refractory functioned normally and that cooling from the steel shell was effective.

FIG. 4 is a graph showing the transition of the monthly average usage of irregular-shaped refractories required for repair before and after the implementation of the present invention under a constant temperature operation of refractory bricks.

From the month when the present invention was carried out (the month indicated by the arrow), the amount of the amorphous refractories used could be reduced by half. Although not shown, the blast furnace downtime for repairing irregular-shaped refractories was reduced by half.

[0040]

According to the present invention, it is possible to detect and specify a deteriorated portion of an irregular refractory between a refractory brick and a steel shell on a bottom wall of a blast furnace furnace. As a result, problems such as an increase in cost and a decrease in production volume can be improved.

[Brief description of the drawings]

FIG. 1 shows a thermoblast brick in which n thermocouples 1 to n are arranged in the blast furnace radial direction at the bottom wall portion of a blast furnace composed of a refractory brick 1, an amorphous refractory 2 and a steel shell 3 from the inside of the furnace. , The distance from the outer surface of the steel shell, the temperature Tl to Tn at each point, and the temperature rise rate dTl to dTn when the temperature is changed
FIG.

FIG. 2 is an example of a graph showing each temperature at a certain location A in the blast furnace circumferential direction when the temperature inside the blast furnace rises, and a temperature rise rate.

FIG. 3 is an example of a graph showing each temperature at a certain location B in the blast furnace circumferential direction when the temperature inside the blast furnace rises, and a temperature rise rate.

FIG. 4 is a graph showing the transition of the monthly average usage of irregular-shaped refractories required for repair before and after implementation of the present invention under constant temperature operation of refractory bricks.

[Explanation of symbols]

 1: refractory brick, 2: refractory, 3: iron shell, 4: thermocouple.

Claims (1)

[Claims] 1. In a blast furnace bottom wall portion composed of a refractory brick, an irregular refractory and a steel shell in order from the inside of the furnace, the refractory bricks are embedded at the same position in the blast furnace circumferential direction at intervals in the blast furnace radial direction. Among the plurality of thermocouples, the temperature rise rate indicated by two thermocouples at an arbitrary position is the temperature rise rate indicated by the thermocouple inside the furnace, and the temperature rise rate indicated by the thermocouple on the amorphous refractory side is dTi. Let dTj be dTi, dTi
When the temperature rise rate of Tj satisfies dTi <dTj,
A method for detecting a deteriorated portion of an amorphous refractory at the bottom of a blast furnace, wherein it is determined that the amorphous refractory at the same position in the circumferential direction of the blast furnace is deteriorated.