JP7567765B2 - Method for measuring refractory thickness in ladles - Google Patents

Description

The present invention relates to a method for measuring the thickness of refractory in a ladle lined with refractory.

A ladle, which is a container for transporting molten steel tapped from a converter, has a ladle body and a refractory material lined on the inner surface of the ladle body. The ladle body includes a steel shell and permanent bricks lined on the inner surface of the steel shell. The inner surface of the permanent bricks is lined with work bricks as the refractory material. This refractory material (work bricks) gradually wears out due to spalling, abrasion, peeling, melting by slag, etc. during the molten steel processing process. When the refractory wears out, it needs to be replaced, so the amount of wear needs to be properly managed. If the replacement is not performed sooner, the remaining thickness of the refractory may be insufficient, causing holes in the steel shell of the ladle and causing steel leakage problems. If the replacement is performed too soon, the refractory material will be replaced unnecessarily, leading to an increase in the unit cost of production. Therefore, it is desirable to accurately measure the thickness of the refractory material inside the ladle. As an example of a method for measuring the thickness of a refractory material in a ladle, as described in Patent Document 1, a method is known in which the surface of the refractory material in a molten metal container lined with the refractory material is captured by a camera to obtain a surface profile of the refractory material.

JP 2009-2765 A

Instead of the camera used in Patent Document 1, it is also possible to obtain a surface profile of the refractory using a laser range finder to measure the thickness of the refractory. In this method, it is assumed that the upper end position of the ladle is detected by the laser range finder, and a position at a certain depth from the detected upper end position of the ladle is set as a virtual position of the inner surface of the ladle body at the bottom of the ladle (a virtual position of the boundary between the ladle body and the refractory, i.e., a virtual position where the thickness of the refractory is 0 mm). Since the distance between the upper end position of the ladle before use and the position of the inner surface of the ladle body at the bottom of the ladle is known, it is assumed that this distance is adopted as the "certain depth". In this case, the position of the surface of the refractory at the bottom of the ladle is detected by the laser range finder, and the measured thickness of the refractory at the bottom of the ladle can be obtained from the difference between the detected position of the surface of the refractory and the set virtual position of the inner surface of the ladle body.

In this case, as shown in FIG. 1 (left side), if the upper end position of the ladle detected by the laser distance meter is the true upper end position of the ladle, referring to FIG. 2 as well, the position of a certain depth X from the upper end position is the position of the inner surface of the ladle body (i.e., the true refractory 0 mm line). Therefore, in principle, the measured thickness of the refractory is equal to the true remaining thickness D' of the refractory. However, as shown in FIG. 1 (right side), during the process of using the ladle, deposits such as slag and metal accumulate on the upper end of the ladle. In this case, referring to FIG. 2 as well, the upper end position of the ladle detected by the laser distance meter is not the true position of the upper end of the ladle, but the upper end position of the deposit. In this case, the position of a certain depth X from the upper end position is higher than the true position of the inner surface of the ladle body (i.e., the true refractory 0 mm line) by the thickness Y of the deposit. In other words, the virtual position set as the inner surface of the ladle body is higher than the true position of the inner surface of the ladle body (the true 0 mm refractory line) by the thickness Y of the deposit. As a result, the measured refractory thickness A' is smaller than the true remaining refractory thickness D' by the thickness Y of the deposit, which results in a measurement error in the thickness of the refractory at the bottom of the ladle. During the process of using the ladle, the thickness Y of the deposit at the upper end of the ladle gradually increases or peels off at a certain stage. For this reason, the thickness Y of the deposit is not constant at each timing when the thickness of the refractory is measured, and the measurement error is also not constant. In other words, the conventional method has a problem in that it is not possible to accurately measure the thickness of the refractory at the bottom of the ladle.

In view of the above problems, the present invention aims to provide a method for measuring the thickness of refractory material that can accurately measure the thickness of the refractory material at the bottom of a ladle.

In order to solve the above problems, the present inventors have conducted research and found that
(i) When measuring the thickness of the refractory, a rod-shaped jig is inserted through the molten steel outlet located at the bottom of the ladle (i.e., no material is attached to the top end of the jig);
(ii) the height of the upper end of the jig from the inner surface of the ladle body at the bottom of the ladle is a known fixed value;
(iii) measuring the height of the upper end of the jig from a virtual position defined as the inner surface of the ladle body;
The inventors came up with the idea that it is possible to obtain a measurement error corresponding to the thickness Y of the adhesion, and by correcting the initial thickness measurement value based on this measurement error, it is possible to obtain a highly accurate thickness measurement value.

The essential configuration of the present invention, which was completed based on this concept, is as follows.
[1] A method for measuring the thickness of a refractory material in a ladle having a ladle body and a refractory material lined on an inner surface of the ladle body, comprising the steps of:
A method for measuring the thickness of a refractory material in a ladle, comprising the steps of:

[2] A method for measuring the thickness of a refractory material in a ladle as described in [1] above, in which the jig is inserted into the refractory material attached to the inner surface of the ladle body.

[3] A method for measuring the thickness of a refractory material in a ladle as described in [1] or [2] above, in which the jig is rod-shaped and is inserted from an outlet located at the bottom of the ladle.

[4] Detecting the upper end position of the ladle;
Using the detected upper end position of the ladle as a reference, a position at a certain depth from the upper end position is set as a virtual position of the inner surface of the ladle body at the bottom of the ladle;
Detecting the position of the surface of the refractory at the bottom of the ladle;
A provisional thickness value A of the refractory at the bottom of the ladle is obtained from a difference between the detected position of the surface of the refractory and a set virtual position of the inner surface of the ladle body.
The jig is inserted from a discharge port located at the bottom of the ladle, and a height B of an upper end of the jig from an inner surface of the ladle body at the bottom of the ladle is known;
Detecting the position of the upper end of the jig;
calculating a height C of the upper end of the jig relative to the set virtual position of the inner surface of the ladle body from a difference between the detected position of the upper end of the jig and the set virtual position of the inner surface of the ladle body;
The difference between B and C is taken as the measurement error.
The method for measuring the thickness of a refractory material in a ladle according to any one of the above-mentioned [1] to [3], further comprising a step of correcting the provisional thickness value A based on the measurement error to obtain a measured thickness value D of the refractory material at the bottom of the ladle.

[5] The method for measuring the thickness of a refractory material in a ladle according to the above [4], wherein the thickness measurement value D is obtained by the following correction formula (1):
D=A+(B-C)...(1)

[6] A method for measuring the thickness of a refractory material in a ladle as described in [4] or [5] above, in which the detection is performed using a laser distance meter.

The method for measuring the thickness of refractory in a ladle of the present invention allows the thickness of the refractory at the bottom of the ladle to be measured with high accuracy.

FIG. 2 is a schematic diagram illustrating a reference point (the upper end position of the ladle) when measuring the thickness of the refractory material 12 in the ladle 100 using a laser distance meter 20. 1 is a schematic diagram illustrating a measurement error in the thickness of the refractory material 12 at the bottom of the ladle 100 that occurs when an attachment is present at the upper end position of the ladle 100. FIG. FIG. 2 is a schematic diagram showing a state in which a rod-shaped jig 40 is inserted from a discharge port 16 located at the bottom of a ladle 100 in one embodiment of the present invention. FIG. 2 is a schematic diagram illustrating the principle of measuring the thickness of the refractory 12 at the bottom of the ladle 100 in one embodiment of the present invention. FIG. 2 is a top view of a ladle for explaining measurement points of the thickness of the refractory material in the examples.

The configuration of a ladle 100 to which the present invention is directed will be described with reference to FIG. 1. The ladle 100 is a vessel for transporting molten steel tapped from a converter, and has a ladle body 10 and a refractory material 12 lined on the inner surface of the ladle body 10. The ladle body 10 includes a steel shell and permanent bricks lined on the inner surface of the steel shell. Work bricks are lined on the inner surface of the permanent bricks as the refractory material 12. The steel shell, permanent bricks, and work bricks all have flat bottoms, cylindrical sides, and open tops. The upper ends of the steel shell, permanent bricks, and work bricks are at approximately the same height, which is the upper end position (initial position) of the ladle.

A trunnion 14 is provided on the outer periphery of the ladle body 10, which is used when hoisting the ladle 100 with a crane. A discharge port 16 is provided at the bottom of the ladle 100 to discharge the molten steel contained in the ladle 100. The molten steel discharged from the discharge port 16 is poured into the tundish of a continuous casting machine, etc.

The procedure for measuring the thickness of the refractory 12 in the ladle 100 according to one embodiment of the present invention is described below. As shown in FIG. 1, the empty ladle 100 from which the molten steel has been discharged is placed in a temporary storage area 30 in which a laser distance meter 20 is set up. At this time, by placing the trunnion 14 on the receiving platform 32 of the temporary storage area 30, the ladle 100 can be placed in the same orientation every time.

The laser range finder 20 emits a laser toward the surface of the refractory 12 in the ladle body 10 and measures the distance between the laser range finder 20 and the surface. By performing this operation over the entire surface of the refractory 12 while changing the direction of laser emission, the distance between the entire surface of the refractory 12 and the laser range finder 20 can be measured, and the surface profile of the refractory 12 as viewed from the position of the laser range finder 20 can be determined in three dimensions. The laser range finder 20 is installed in a position where it can irradiate the entire surface of the refractory 12 with a laser. Note that any device capable of detecting the desired position may be used instead of the laser range finder 20.

As shown in FIG. 1 (right side), during the use of the ladle 100, deposits such as slag and metal accumulate on the upper end of the ladle 100. This embodiment relates to a method for correcting measurement errors in the thickness measurement of the refractory 12 at the bottom of the ladle 100 caused by these deposits. Specifically, the method is characterized by using a jig 40 with a known length. The jig 40 is inserted into the refractory 12 that is attached to the inner surface of the ladle body. Specifically, as shown in FIG. 3, the jig 40 is rod-shaped, and is inserted from the outlet 16 located at the bottom of the ladle.

Below, the principle of measuring the thickness of the refractory 12 at the bottom of the ladle 100 according to this embodiment will be explained with reference to Figures 3 and 4.

First, the laser distance meter 20 detects the position of the top end of the ladle 100. Here, if there is no attachment at the top end of the ladle, the position of the top end of the ladle 100 detected by the laser distance meter 20 will be the true position of the top end of the ladle 100. However, if there is an attachment at the top end of the ladle, the position of the top end of the ladle 100 detected by the laser distance meter 20 will be the top end position of the attachment, not the true position of the top end of the ladle 100.

Next, referring to FIG. 4, the detected top end position of the ladle 100 (top end position of the deposit) is used as a reference, and a position at a certain depth X from the top end position is set as a virtual position on the inner surface of the ladle body 10 at the bottom of the ladle 100. In FIG. 4, this virtual position is described as the "refractory 0 mm line based on the top end position."

Next, the laser range finder 20 detects the position of the surface of the refractory 12 at the bottom of the ladle 100, and a provisional thickness value A of the refractory 12 at the bottom of the ladle 100 is obtained from the difference between the detected position of the surface of the refractory 12 and the set virtual position of the inner surface of the ladle body 10.

Here, the virtual position set as the inner surface of the ladle body 10 is higher than the true position of the inner surface of the ladle body (the "true refractory 0 mm line" in Figure 4) by the thickness Y of the deposit. As a result, the provisional refractory thickness value A is smaller than the true remaining refractory thickness D by the thickness Y of the deposit, which results in a measurement error in the thickness of the refractory 12 at the bottom of the ladle 100.

This embodiment relates to a method for correcting the measurement error of the provisional thickness value A and accurately measuring the thickness of the refractory material 12 at the bottom of the ladle 100.

3 and 4, the outlet 16 located at the bottom of the ladle 100 is opened, and a rod-shaped jig 40 is inserted through the outlet 16. The jig 40 has a flange 40A that can be attached to the flange surface at the bottom of the outlet 16, and is fixed to the outlet 16. Here, the length of the rod-shaped member 40B protruding from the flange 40A is known and constant, so the height B of the upper end of the jig 40 from the inner surface of the ladle body 10 at the bottom of the ladle 10 is known and fixed. The upper end of the jig 40 is flat, and is placed at a position where the laser can be irradiated from the laser range finder 20. The jig 40 can be made of various materials such as metal and refractory materials as long as it is made of a material that can withstand an atmosphere exceeding 1000°C inside the ladle 100. It is preferable that the jig 40 is made of steel so that it is not damaged during handling, such as insertion into the outlet 16.

In this state, the position of the upper end of the jig 40 is detected by the laser range finder 20, and the height C of the upper end of the jig 40 relative to the set virtual position of the inner surface of the ladle body 10 is calculated from the difference between the detected position of the upper end of the jig 40 and the set virtual position of the inner surface of the ladle body 10.

If there is no adhesion and no measurement error in the thickness of the refractory 12 at the bottom of the ladle 100 due to this, this height C should be the same as the height B of the upper end of the jig 40 from the inner surface of the ladle body 10 at the bottom of the ladle 10. Therefore, the difference between B and C is understood to be the measurement error.

Therefore, the provisional thickness value A is corrected based on this measurement error to obtain a measured thickness value D of the refractory 12 at the bottom of the ladle 100. Specifically, the measured thickness value D can be obtained by the following correction formula (1). According to this correction formula, the measured thickness value D is, in principle, equivalent to the true thickness of the refractory 12 at the bottom of the ladle 100.
D=A+(B-C)...(1)

For example, if the provisional thickness value A of the refractory material 12 is 100 mm, the height B of the upper end of the jig 40 from the inner surface of the ladle body 10 at the bottom of the ladle 10 is 327 mm, and the height C of the upper end of the jig 40 relative to the set virtual position of the inner surface of the ladle body 10 is 260 mm, the measurement error is determined to be 327-260=67 mm, and 100+67=167 mm is adopted as the measured thickness value D.

In this way, the method for measuring the thickness of refractory in a ladle according to this embodiment allows the thickness of the refractory at the bottom of the ladle to be measured with high accuracy. This allows the refractory to be relined at the appropriate time, reliably avoiding steel leakage problems while minimizing the reline costs.

By performing the thickness measurement of this embodiment at any location on the surface of the refractory 12 at the bottom of the ladle 100, the thickness at that location can be measured with high accuracy. Also, by performing the thickness measurement of this embodiment on the entire surface of the refractory 12 at the bottom of the ladle 100, the thickness profile of the refractory 12 at the bottom of the ladle 100 can be obtained with high accuracy.

Instead of the correction formula (1), the thickness measurement value D can be obtained by the following correction formula (2). In the case of the correction formula (1), the thickness measurement value D is, in principle, equivalent to the true thickness of the refractory 12 at the bottom of the ladle 100, and even if the refractory is replaced when the thickness measurement value D reaches 0 mm, the risk of steel leakage is high. Therefore, the thickness measurement value D obtained by adding the measurement error (B-C) to the provisional thickness value A and then subtracting the safety margin E (within the range of 1 to 20 mm) can be adopted as the control value. In this case, even if the refractory is replaced when the thickness measurement value D reaches 0 mm, the risk of steel leakage is low. However, if E is set to more than 20 mm, the effect of the present invention of reducing the measurement error is lost, so E is set to 20 mm or less.
D=A+(B-C)-E...(2)

The thickness of the refractory was measured using a ladle capable of holding 180 tonnes of molten steel. The ladle was repeatedly charged and discharged with 27 charges of molten steel from the start of use, and then placed on a receiving platform in the temporary storage area. The sliding gate of the discharge outlet on the bottom of the ladle was opened, and a rod-shaped jig was inserted into the ladle from below the discharge outlet. The jig was made of stainless steel and was 1m long. The flange on the bottom end of the jig was fixed to the flange on the bottom of the discharge outlet, so that the top surface of the jig protruded 327mm above the top surface of the permanent bricks at the bottom of the ladle. A laser range finder was placed in the temporary storage area to measure the surface of the refractory in the ladle. At this time, the thickness of the refractory was measured using the following three methods at measurement points I and II on the bottom of the ladle as shown in Figure 5 below.

[Example of the Invention]
The thickness measurement value D was calculated based on the above correction formula (1). Since B = 327 mm and C = 276 mm, the measurement error was determined to be B - C = 51 mm. The results are shown in Table 1.

[Comparative Example]
The provisional thickness value A in the above correction formula (1) was directly adopted as the measured value. The results are shown in Table 1.

[Actual measurements by core boring]
In order to verify the accuracy of the measurements in the examples and comparative examples, the refractories were core-bored to examine the remaining thickness. The results are shown in Table 1.

As shown in Table 1, at all points, the measurements made by the invention example were within ±10 mm of the actual measurements made by core boring, and the thickness of the refractory material at the bottom of the ladle was measured with high accuracy.

The method for measuring the thickness of refractory in a ladle of the present invention allows the thickness of the refractory at the bottom of the ladle to be measured with high accuracy.

100 Ladle 10 Ladle body (iron shell and permanent bricks)
12 Refractory materials (work bricks)
14 Trunnion 16 Discharge port 20 Laser distance meter 30 Temporary storage area 32 Receiving base 40 Jig 40A Flange 40B Rod-shaped member

Claims (5)

A method for measuring a thickness of a refractory material in a ladle having a ladle body and a refractory material lined on an inner surface of the ladle body, comprising the steps of:
1. A method for measuring the thickness of a refractory material in a ladle, comprising the steps of: using a jig having a known length ; said jig being rod-shaped and being inserted through a discharge port located at the bottom of said ladle . The method for measuring the thickness of a refractory material in a ladle according to claim 1, wherein the jig is inserted into the refractory material attached to the inner surface of the ladle body. Detecting the upper end position of the ladle;
Using the detected upper end position of the ladle as a reference, a position at a certain depth from the upper end position is set as a virtual position of the inner surface of the ladle body at the bottom of the ladle;
Detecting the position of the surface of the refractory at the bottom of the ladle;
A provisional thickness value A of the refractory at the bottom of the ladle is obtained from a difference between the detected position of the surface of the refractory and a set virtual position of the inner surface of the ladle body.
The jig is inserted from a discharge port located at the bottom of the ladle, and a height B of an upper end of the jig from an inner surface of the ladle body at the bottom of the ladle is known;
Detecting the position of the upper end of the jig;
calculating a height C of the upper end of the jig relative to the set virtual position of the inner surface of the ladle body from a difference between the detected position of the upper end of the jig and the set virtual position of the inner surface of the ladle body;
The difference between B and C is taken as the measurement error.
3. The method for measuring the thickness of a refractory material in a ladle according to claim 1, further comprising a step of correcting the provisional thickness value A based on the measurement error to obtain a measured thickness value D of the refractory material at the bottom of the ladle. 4. The method for measuring a thickness of a refractory material in a ladle according to claim 3 , wherein the thickness measurement value D is obtained by the following correction formula (1):
D=A+(B-C)...(1) 5. The method for measuring the thickness of a refractory material in a ladle according to claim 3 or 4 , wherein the detection is performed by a laser distance meter.

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