JP2023136410A - Furnace bottom tapping method - Google Patents

Abstract

To provide a furnace bottom tap method for early determining whether or not to reach tapping in performing a drilling operation, and improving efficiency in a furnace bottom tapping operation.SOLUTION: A furnace bottom tapping method performs tapping by drilling a furnace bottom in a blast furnace by a hole opening machine. The hole opening machine comprises a temperature sensor at a hole opening bit. The furnace bottom tapping method has: a first step of continuing drilling regardless of a detection temperature till a drilling distance reaches a first drilling distance; a second step of continuing drilling as long as the detection temperature increase after the drilling distance reaches the first drilling distance; a third step of stopping drilling when the detection temperature does not increase after the drilling distance reaches the first drilling distance; and a fourth step of determining whether to continue drilling on the basis of a length of a delay region when the delay region where the temperature increase is delayed after the execution of the second step.SELECTED DRAWING: Figure 2

Description

The present invention relates to a furnace bottom tapping method.

In blast furnaces, the lining refractories, furnace body cooling equipment, etc. deteriorate due to long-term operation, so work to repair or replace these items is carried out periodically. A particular problem in this blast furnace renovation is that the hot metal remaining in the furnace after the blowdown operation solidifies at the bottom of the furnace and remains in large amounts as residual lumps. Removal of this residual mass is extremely difficult, leading to problems such as a prolonged repair period and an increase in repair costs. As a countermeasure for this, a taphole for removing residual pig iron is installed below the taphole to tap the residual hot metal, and bottom tapping is performed in which the hot metal is discharged outside the furnace from this taphole for removing residual pig iron. Sometimes.

During the operation period at the end of the furnace life up to blowdown, the temperature at the furnace bottom decreases due to lowering the tap iron ratio than during normal operation in order to protect the furnace bottom refractories, so the solidification of hot metal at the furnace bottom occurs. There is a problem with deposit growth. As a countermeasure against this problem, Patent Document 1 states that when renovating a blast furnace, the operating conditions are controlled from at least four months before blowdown to maintain the tap iron ratio at a high level and suppress the decline in production. A technique has been disclosed in which, after suppressing the growth of solidified deposits at the furnace bottom, remaining hot metal is tapped from the furnace bottom during blowdown to reduce the amount of solidified deposits at the furnace bottom.

Japanese Patent Application Publication No. 2006-137985

Since the size, shape, etc. of the solidified deposits vary depending on the excavation location, for example, when excavating an area with thick solidified deposits, it may not be possible to tap the iron. In this case, it is necessary to temporarily evacuate the drilling bit outside the furnace and restart the drilling operation by changing the approach angle of the drilling bit. Therefore, the workload is heavy, which may lead to longer working hours and increased costs. Patent Document 1 does not consider this issue at all.

An object of the present invention is to quickly determine whether or not to reach the stage of tapping during excavation work, and to make the furnace bottom tapping work more efficient.

(1) In order to solve the above problems, a hearth tapping method according to the present invention is (1) a hearth tapping method in which iron is tapped by excavating the hearth bottom of a blast furnace with a borehole drill, , the hole-drilling machine is equipped with a temperature sensor on the hole-drilling bit, and the first step is to continue drilling regardless of the detected temperature until the drilling distance reaches the first drilling distance. a second step of continuing the excavation as long as the detected temperature is rising after reaching the first excavation distance; and stopping the excavation if the detected temperature does not increase after the excavation distance reaches the first excavation distance. and a fourth step of determining whether or not to continue excavation based on the length of the stagnation area if a stagnation area where the temperature rise is stagnant occurs after the implementation of the second step. It is characterized by

(2) In the fourth step, when the maximum temperature, which is the highest detected temperature, is not updated and the excavation distance starting from the excavation position corresponding to the maximum temperature reaches the second excavation distance or more. The furnace bottom tapping method according to (1) above, characterized in that the drilling is stopped.

(3) The method for tapping the hearth iron according to (1) or (2) above, wherein the first excavation distance is a thickness design value of the side wall of the hearth brick in the excavation direction of the hole bit. .

(4) The furnace bottom tapping method according to any one of (1) to (3) above, wherein the second excavation distance is 0.3 m.

According to the present invention, during excavation work, it is possible to determine at an early stage whether or not iron will be tapped. Thereby, the furnace bottom tapping work can be performed efficiently.

FIG. 3 is a functional block diagram of the opening machine. FIG. 3 is an explanatory diagram of patterns A to D. This is a temperature distribution in the excavation direction (Example). 4 is an enlarged view of a part of FIG. 3. FIG.

FIG. 1 is a functional block diagram of a hole punching machine for carrying out the hearth tapping method of this embodiment, and dotted arrows indicate the direction in which signals flow.
The drilling machine 1 includes a drilling bit (not shown), a temperature sensor 11 , a bit drive motor 12 , a motor control section 13 , and a communication section 14 . The drilling machine 1 may be of a hydraulic type. The temperature sensor 11 is built into the drilling bit. The hole-opening bit is rotated by the power transmitted from the bit drive motor 12 to excavate the side wall bricks at the bottom of the furnace. Here, the drilling bit receives vibrations and shocks during drilling, and also receives radiant heat from the hot metal in the furnace as drilling progresses. Therefore, it is desirable to mount a protective structure (see, for example, Japanese Patent Application Laid-open No. 8-21768) on the drilling bit to protect the temperature sensor 11 from these vibrations, shocks, and radiant heat.

For example, a thermocouple that calculates temperature using the Seebeck effect can be used as the temperature sensor 11. If the drilling bit is located within the bottom side wall brick, the temperature of the brick is detected by the temperature sensor 11. When the drilling bit advances and reaches the solidified deposit inside the furnace, the temperature of the solidified deposit is detected by the temperature sensor 11. When the drilling bit advances further and reaches the residual pig iron slag in the furnace, the temperature of the residual pig iron slag in the furnace is detected by the temperature sensor 11.

The motor control unit 13 controls the drive of the bit drive motor 12 based on instruction information from the operator room 2, and also controls the moving distance of the drilling bit (in other words, the excavation distance) based on the rotation speed of the bit drive motor 12, etc. Calculate.

The temperature detected by the temperature sensor 11 can be transmitted to the operator room 2 via the communication unit 13. The excavation distance calculated by the motor control unit 13 can be transmitted to the operator room 2 via the communication unit 13. These temperatures and excavation distances can be displayed on a monitor screen installed in the operator room 2, for example. The operator can understand these relationships from the temperature and excavation distance displayed on the monitor screen. However, these temperatures and excavation distances may be displayed on a display provided in the drilling machine 1. Note that the communication means by the communication unit 13 may be wired or wireless.

The present inventor conducted a furnace bottom tapping operation using the above-mentioned hole drilling machine 1, and investigated the relationship between the excavation distance and the detected temperature. As a result, it was discovered that these relationships can be organized into patterns A to D described below.

FIG. 2 is an explanatory diagram for explaining patterns A to D (also referred to as "excavation availability determination information"), and the horizontal and vertical axes are the excavation distance and detected temperature, respectively. Referring to the figure, it was found that in all patterns there is a period 1 in which the temperature rise is slow.
In pattern A, the temperature rose rapidly immediately after period 1, and although there was a period after which the temperature rise slowed down, the temperature continued to rise until the time of tapping.
In pattern B, almost no temperature increase was observed after period 1, and iron tapping did not occur.
In pattern C, after the temperature rose rapidly immediately after period 1, a stagnation region C where the temperature rise stagnated occurred, and then the temperature rose again, leading to tapping. In addition, since the stagnation zone C occurs in a temperature range of about 1200° C., it is presumed to be a solid-liquid mixed layer of hot metal.
In pattern D, stagnation area D corresponding to stagnation area C of pattern C continued for a long time and did not lead to tapping.

Based on the above investigation results, the present inventor discovered an efficient furnace bottom tapping method consisting of the following steps 1 to 4.

Step 1: Continue digging regardless of the detected temperature until the digging distance reaches the first digging distance. The first excavation distance may be a thickness design value of the bottom brick side wall in the excavation direction of the hole bit. In other words, the thickness design value corresponds to the excavation distance (in other words, the penetration distance) in which the tip of the drilling bit excavates the bottom side wall brick, and corresponds to period 1 in FIG.
Therefore, when the drilling bit enters perpendicularly to the outer surface of the furnace bottom side wall brick, the excavation distance within the furnace bottom side wall brick in the vertical direction corresponds to the first excavation distance, and the vertical direction When the hole-drilling bit is moved in an inclined direction that is inclined to the ground, the excavation distance within the furnace bottom side wall brick in the inclination direction corresponds to the first excavation distance. Even if the excavation start position is the same, the first excavation distance may vary depending on the excavation direction.
The operator compares the excavation distance displayed on the monitor screen in the operator room 2 with the thickness design value based on the design information, and when they match, can understand that the excavation distance has reached the first excavation distance.

In this embodiment, the first excavation distance is determined from the thickness design value of the furnace bottom side wall brick, but the present invention is not limited to this. For example, it may be determined whether the excavation distance has reached the first excavation distance by monitoring the torque value of the bit drive motor 12, which varies before and after penetrating the furnace bottom side wall brick.

Step 2: After the excavation distance reaches the first excavation distance, continue excavation as long as the detected temperature is rising. In this case, since tapping according to pattern A or pattern C can be expected, excavation is continued.

Step 3: If it is determined that the detected temperature does not rise after the excavation distance reaches the first excavation distance, the excavation is stopped. In this case, it is classified as pattern B, and drilling is discontinued because iron extraction cannot be expected. Here, it is desirable that the determination timing in step 3 be performed at a predetermined position where the excavation has progressed further than the first excavation distance. This is because even in the case where the iron is tapped, the temperature does not necessarily change immediately after reaching the first excavation distance, and there may be a slight delay. The predetermined position is preferably a position where excavation has progressed by 0.75 m or more from the first excavation distance.
After stopping drilling, the drilling bit is temporarily removed from the furnace, and new drilling work (hereinafter also referred to as re-hole work) is performed. Reopening work can be performed by changing the entry angle of the drilling bit or by changing the drilling position.
By stopping excavation midway, it is possible to move on to the re-opening work at an early stage, thereby improving the work efficiency of the furnace bottom tapping work.

Step 4: If a stagnation area where the temperature rise is stagnant occurs after step 2 is performed, it is determined whether or not to continue excavation based on the size of the stagnation area. Referring to Fig. 2, if a stagnation region in which the temperature rise is stagnant occurs in the temperature range of about 1200°C, the transition will be to either pattern C where iron tapping can be expected or pattern D where iron tapping cannot be expected. . The difference between pattern C and pattern D is the length of the stagnation area. Therefore, if the stagnation area is short, it is assumed that the pattern will change to pattern D, in which no iron tapping can be expected, and the excavation will be stopped.

The length of the stagnation area is, for example, when the maximum temperature detected by the temperature sensor 11 is not updated and the excavation distance from the excavation position where the maximum temperature was recorded (hereinafter also referred to as non-updated excavation distance) is the first. This can be determined based on whether or not the excavation distance has reached the excavation distance of 2 or more. When the non-updated excavation distance reaches the second excavation distance or more, the excavation is stopped. The second excavation distance is a distance beyond which no iron can be expected to be tapped even if the excavation continues, and can be appropriately set based on empirical rules. The second excavation distance can be set to 0.3 m, for example.

In the embodiment described above, the length of the stagnation area is determined based on the non-updated excavation distance in which the maximum temperature is not updated, but the present invention is not limited to this. For example, the first detected temperature, which is the detected temperature immediately after the transition to the stagnation area, and the second detected temperature, which is the detected temperature at a position beyond the second excavation distance, are compared, and the second detected temperature is the first detected temperature. If it is lower than the temperature, it may be determined that the stagnation area is long, and excavation may be stopped.

According to this embodiment, it is possible to early determine whether or not tapping can be expected during excavation, and if tapping cannot be expected, the excavation process can be stopped midway. As a result, it is possible to proceed to the re-hole re-opening work at an early stage, thereby increasing the work efficiency of the furnace bottom tapping work.

(Example)
The present invention will be specifically explained by showing examples. After blowing down a 2903 m ³ blast furnace (heart diameter: 9.6 m, brick thickness: 1 m), hearth bottom tapping was performed using the borehole machine described in the embodiment, and temperature distribution in the excavation direction was measured. The first excavation distance was set to the design thickness of the furnace bottom side wall brick. In Examples 1 to 3, the first excavation distance was the thickness of the brick (that is, 1 m) because the excavation was carried out in the thickness direction of the hearth side wall brick. In Example 4, the first excavation distance was 1.5 m because the excavation was carried out in an inclined direction with respect to the thickness direction of the furnace bottom side wall brick. FIG. 3 shows the measurement results, with the horizontal and vertical axes representing the excavation distance and detected temperature, respectively. FIG. 4 is an enlarged view of a part of the graph of FIG. 3 (the rectangular area indicated by the dotted line).

In Example 1, the excavation distance reached the first excavation distance (1 m), and even if the excavation was further continued by 0.8 m, there was hardly any temperature rise, and the drilling was stopped within 2 m because iron tapping could not be expected.

In Example 2, after the excavation distance reached the first excavation distance (1 m), the temperature rose to around 1200°C at 2.2 m, but no iron tapping was observed at this point. Thereafter, the maximum temperature Tmax (Example 2) was reached at about 2.3 m, but the maximum temperature Tmax (Example 2) was not updated even after digging to 2.75 m. In other words, the stagnation area in which the maximum temperature Tmax (Example 2) was not updated was at least 0.45 m (450 mm). In this case, it is presumed that a large amount of solidified deposits or semi-molten pig slag is present at this excavation location.

In Example 3, after the excavation distance reached the first excavation distance (1 m), the temperature rose to around 1200°C at a point where the excavation distance exceeded 2 m, but no iron tapping was observed at this point. Thereafter, the maximum temperature Tmax (Example 3) was reached at about 2.2 m, and the maximum temperature Tmax (Example 3) was updated at a point exceeding about 2.3 m. In other words, the stagnation area in which the maximum temperature Tmax (Example 3) was not updated was about 0.1 m (100 mm). Furthermore, when excavation continued, a hole was opened at a point of 2.7 m, and tapping of hot metal slag with a high viscosity of about 1350°C began. After that, we were able to discharge the remaining pig iron slag from the furnace almost as scheduled.
By comparing Examples 2 and 3, it was found that whether or not to tap iron can be determined by the length of the stagnation region where the maximum temperature Tmax is not updated. From these examples, the second excavation distance can be determined to be 0.3 m.

In Example 4, after the excavation distance reached the first excavation distance (1.5 m), the temperature continued to rise consistently, and around the excavation distance of 2.4 m, hot metal was tapped at a temperature of 1400°C. At the same time, a thermocouple was damaged, but the remaining pig iron slag inside the furnace was successfully discharged. This is an ideal example in hearth tapping operations.

The results of Examples 1 to 4 are summarized in Table 1.

1 Drilling machine 2 Operator room 11 Temperature sensor 12 Pit drive motor 13 Motor control section 14 Communication section

Claims (4)

A bottom tapping method for tapping iron by drilling the bottom of a blast furnace with a hole-drilling machine, the method comprising:
The hole drilling machine is equipped with a temperature sensor on the hole bit,
a first step of continuing the excavation regardless of the detected temperature until the excavation distance reaches the first excavation distance;
a second step of continuing the excavation as long as the detected temperature increases after the excavation distance reaches the first excavation distance;
a third step of stopping the excavation if the detected temperature does not rise after the excavation distance reaches the first excavation distance;
If a stagnation area where the temperature rise is stagnant occurs after the second step, a fourth step of determining whether or not to continue excavation based on the length of the stagnation area;
A furnace bottom tapping method characterized by having the following. In the fourth step, if the maximum temperature, which is the maximum detected temperature, is not updated and the excavation distance starting from the excavation position corresponding to the maximum temperature reaches the second excavation distance or more, 2. The furnace bottom tapping method according to claim 1, wherein the drilling is stopped. 3. The furnace bottom tapping method according to claim 1, wherein the first excavation distance is a thickness design value of a side wall of the furnace bottom brick in the excavation direction of the hole bit. The furnace bottom tapping method according to any one of claims 1 to 3, wherein the second excavation distance is 0.3 m.