TW201928272A - Refractory material loss management device of electric furnace, refractory material loss management system of electric furnace, refractory material loss management method of electric furnace, and computer readable memory medium characterized by precisely monitoring the loss of refractory material used to construct the wall of electric furnace which uses the arc discharge to melt the waste material - Google Patents

Abstract

The present invention provides a refractory material loss management device which performs an analysis of the inverse unsteady state heat conduction problem according to the temperature measured by the thermocouple in each temperature sampling time. Thereby, the relationship of the heat flux of the inner surface of a furnace wall and the time is derived. In addition, the time integral value of the heat flux corresponding to one operation period is derived according to the result and then is output.

Description

Refractory loss management device for electric furnace, refractory loss management system for electric furnace, refractory loss management method for electric furnace, and computer readable memory medium

FIELD OF THE INVENTION The present invention relates to a refractory loss management device for an electric furnace, a refractory loss management system for an electric furnace, a refractory loss management method for an electric furnace, and a computer readable memory medium, particularly suitable for managing a furnace wall of an electric furnace. In the state of the refractory material, the electric furnace described above uses an arc discharge to melt the waste.

BACKGROUND OF THE INVENTION In an electric furnace (alcmelting furnace), raw materials such as scraps are placed in a furnace every time (charge) (ch). Thereafter, the raw material is melted/melted by an electric arc generated from the arc electrode to obtain a molten metal and molten waste. Since the furnace wall of such an electric furnace is exposed to a high temperature, it is made of a refractory material such as refractory brick.

However, even if a furnace wall is formed using a refractory material, the refractory material is worn out due to the reverse operation, and the thickness thereof is reduced. One of the reasons can be exemplified by the fact that the arcs generated from the plurality of arc electrodes repel each other, the arc being directed toward the inner peripheral surface of the furnace wall, whereby the arc locally heats the refractory material. In particular, when the raw material charged into the furnace is melted and dropped, the refractory material is locally subjected to a large amount of radiant heat, and the loss of the refractory material is rapidly performed. Therefore, it is important to manage the loss state of the refractory material from the viewpoint of ensuring safe operation or extending the service life of the refractory material.

Techniques for grasping the loss state of the refractory material constituting the furnace wall of the electric furnace are as described in Patent Documents 1 and 2. Patent Document 1 discloses that the residual thickness of the refractory material is estimated from the relationship between the temperature measured by the temperature measuring sensor disposed inside the refractory material, the temperature obtained beforehand, and the amount of loss of the refractory material. Further, Patent Document 1 also discloses the residual thickness of the refractory material from the temperature measured by the temperature measuring sensor and the thermal conductivity of the refractory material.

Patent Document 2 discloses that the delay time is calculated by comparing the time at which the temperature measured by the temperature sensor disposed inside the refractory material shows the maximum value/minimum value and the tapping start time/iron tapping end time. When the calculated delay time is less than the reference time, it is judged that the refractory material has been lost. Further, Patent Document 2 discloses that the delay time is calculated by comparing the time at which the temperature measured by the temperature sensor detects the maximum value/minimum value with the energization start time/energization end time. Advanced technical literature

[Patent Document 1] Japanese Laid-Open Patent Publication No. 8-94264 (Patent Document 2)

[Non-Patent Document 1] Hon, YC and Wei, T., "The method of fundamental solution for solving multidimensional inverse heat conduction problems", Comput. Model. inEng. and Sci., 7(2005), no.2, 119 -132 [Non-Patent Document 2] PC Hansen, "Regularization Tools. A matlab Package for Analysis and Solution of Discrete Ill-Posed Problems", http://www.imm.dtu.dk (2008), 1~36 [Non- Patent Document 3] GH Golub, CF Van Loan, "Matrix Computations 3rd edition", The Johns Hopkins University Press (1996), 69~73

SUMMARY OF THE INVENTION Problem to be Solved by the Invention In the method disclosed in Patent Document 1, the amount of loss of the refractory material is estimated from the measured temperature inside the refractory material. According to this method, in order to obtain a fixed relationship between the temperature and the amount of loss of the refractory material, the following first premise or second premise is necessary. The first premise is that the temperature inside the furnace wall is the same and the temperature inside the refractory material is stable. The second premise is that the temperature history up to the point at which the temperature is measured is equal. Further, in the method disclosed in Patent Document 1, the residual thickness of the refractory material is estimated from the measured temperature inside the refractory material and the thermal conductivity of the refractory material. In this method, the premise is that the temperature of the inner surface of the furnace wall is known and the temperature inside the refractory material is stable. However, in normal operation, it is a matter of course that there is temperature variation in one feed. Further, various temperature conversion modes are also available in the feed compartment. In such a situation of strong non-steady state, any of the above-mentioned estimation methods is a premise collapse, and a good estimation accuracy cannot be obtained.

Further, in the method disclosed in Patent Document 2, the delay time from the energization start time/energization end time at the time when the minimum value/maximum value of the internal temperature of the refractory material is displayed is calculated, and the residual of the refractory material is estimated from the delay time. thickness. In this method, there is a problem that the timing at which the minimum/maximum value of the internal temperature of the refractory material is displayed is not necessarily limited to the one corresponding to the energization start/energization end. For example, in general, at the start of energization, due to the influence of unmelted waste, there is almost no heat input to the inner surface of the furnace wall, and the temperature of the refractory material is not affected. Therefore, the start of energization does not correspond to the minimum value of the internal temperature of the refractory material. Moreover, the supply of electric power during operation is finely controlled, and even if the energization is not completed, the supply of electric power is reduced, because of its relationship with the temperature of the refractory material, and heat is dissipated in the inner surface of the furnace wall. The temperature change on the inner surface of the furnace wall may correspond to the maximum value of the internal temperature of the refractory material. Further, in the technique described in Patent Document 2, it is not possible to dynamically manage the amount of loss of the refractory material in operation (that is, the amount of refractory loss in the time other than the start of the operation of the first feed and the end of the operation).

The present invention has been made in view of the above problems, and an object thereof is to accurately monitor the loss of a refractory material for constituting an electric furnace wall which melts waste by arc discharge. Means of solving problems

The refractory material loss management device of the electric furnace of the present invention is for managing the loss of the refractory material constituting the furnace wall of the electric furnace, the electric furnace is melted by the arc discharge generated at the arc electrode, and the refractory material loss management of the electric furnace is performed. The apparatus is characterized in that the heat flux deriving means is disposed at a plurality of positions in which the position of the furnace wall of the electric furnace and the outer peripheral surface of the furnace wall of the electric furnace are different in the thickness direction of the furnace wall of the electric furnace. The temperature measured at the temperature detecting end is subjected to an unsteady heat transfer inverse problem analysis, thereby deriving the relationship between the heat flux and the time on the inner circumferential surface of the furnace wall of the electric furnace; the heat flux integral mechanism is based on The relationship between the heat flux on the inner circumferential surface of the furnace wall of the electric furnace and the time derived by the heat flux deriving means, and deriving a time integral value corresponding to the heat flux during the period of one operation; and output The mechanism includes information including a time integral value derived from the heat flux integration means corresponding to the heat flux during the one-time operation period. In the evaluation of the loss of the refractories is output.

The refractory loss management system for an electric furnace according to the present invention is characterized in that: the refractory material loss management device of the electric furnace; and the suppression measure actuator are configured to output heat including a period corresponding to the one-time operation by the output mechanism After the information of the time integral value of the flux, measures for suppressing the loss of the refractory material are taken based on the result of the output.

The refractory material loss management method of the electric furnace of the present invention is for managing the loss of the refractory material constituting the furnace wall of the electric furnace, the electric furnace is melting the waste material by the arc discharge generated at the arc electrode, and the refractory material loss management method of the electric furnace It is characterized in that the heat flux deriving step is based on a plurality of positions in which the position of the furnace wall of the electric furnace and the outer peripheral surface of the furnace wall of the electric furnace are different in the thickness direction of the furnace wall of the electric furnace. The temperature measured at the temperature detecting end is analyzed, and the unsteady heat transfer inverse problem analysis is performed, whereby the heat flux deriving mechanism derives the relationship between the heat flux and the time on the inner circumferential surface of the furnace wall of the electric furnace; The flux integration step is based on the relationship between the heat flux and the time in the inner circumferential surface of the furnace wall derived from the heat flux deriving step, and is derived from the heat flux integration mechanism for one operation. The time integral value of the heat flux during the period; the output step is to include the one derived by the heat flux integration step, corresponding to the previous one The information of the time integral value of the heat flux during the period is outputted by the output means as an index for evaluating the loss of the refractory material; and the step of executing the suppression measure is performed by the output step output After the information on the time integral value of the heat flux during the first operation period, measures for suppressing the loss of the refractory material are taken according to the operator's instruction.

The computer readable memory medium of the present invention is a computer program for storing a refractory material useful for causing a computer to perform management of a furnace wall constituting an electric furnace, wherein the electric furnace melts waste by arc discharge generated at an arc electrode, and The computer readable memory medium is characterized by a computer program for causing the computer to perform the following steps: the heat flux deriving step is based on the inside of the furnace wall of the electric furnace and the outer peripheral surface of the furnace wall of the electric furnace, The temperature measured at the temperature detecting end of the plurality of positions at different positions in the thickness direction of the furnace wall of the electric furnace is subjected to an unsteady heat transfer inverse problem analysis, thereby extracting heat in the inner circumferential surface of the furnace wall of the electric furnace. The relationship between the flux and the time; the heat flux integration step is based on the relationship between the heat flux and the time on the inner circumferential surface of the furnace wall derived from the heat flux deriving step, and is derived corresponding to one time. The time integral value of the heat flux during the operation period; and the outputting step, which is included in the heat flux integration step, corresponding to the previous one Information time integral value of the heat flux within the period, as an index for the evaluation of the loss of the refractories and outputs.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. [Schematic Configuration of Electric Furnace and Position of Temperature Detection End] FIGS. 1 and 2 are views showing an example of a schematic configuration of a refractory loss management system of the electric furnace 1 and the electric furnace 1. Regarding the electric furnace 1, a plan view is shown in Fig. 1, and a cross-sectional view taken along line A-A of Fig. 1 is shown in Fig. 2. In FIG. 1, for convenience of explanation, the illustration of the upper lid portion 2 shown in FIG. 2 is omitted. In the following description, the refractory loss management system of the electric furnace 1 is referred to as a refractory loss management system as needed.

In Fig. 1 and Fig. 2, in the present embodiment, the electric furnace 1 includes an upper cover 2, and three arc electrodes 3a provided around the central axis S of the electric furnace 1 at equal angular intervals (interval 120) in the furnace. 3c; a furnace bottom electrode 4 disposed at the bottom of the electric furnace 1; and a furnace wall 5.

The furnace wall 5 is constructed using a refractory material such as refractory brick or refractory cement. The outer peripheral surface of the furnace wall 5 is covered with iron sheets constituting the furnace frame. In the present embodiment, a case where the thickness of the refractory material constituting the furnace wall 5 is 450 mm will be described as an example. In the following description, the refractory material constituting the furnace wall 5 may be referred to as "furnace refractory material" as needed.

As shown in Fig. 1, a plurality of thermocouples 6a to 6i are embedded in the furnace wall refractory. In the present embodiment, the thermocouples 6a to 6i are embedded at three points of coordinates of 0 mm on the inner surface 5a of the furnace wall and coordinates of 150 mm, 300 mm, and 450 mm on a line perpendicular to the inner surface 5a of the furnace wall. . Here, the inner wall surface 5a of the furnace wall is a surface which may directly receive the radiant heat generated by the arc discharge in the electric furnace 1 among the inner peripheral surfaces of the furnace wall. That is, the inner wall surface 5a of the furnace wall is a surface that may directly contact the molten steel or scrap in the electric furnace 1. Further, in the present embodiment, since the thickness of the furnace wall refractory material is 450 mm, the point on the straight line perpendicular to the inner surface 5a of the furnace wall is 450 mm, and becomes a point on the outer peripheral surface of the furnace wall 5.

The thermocouples 6a to 6c, 6d to 6f, and 6g to 6i are respectively arranged on the straight lines 7a, 7b, and 7c which are straight lines orthogonal to the central axis S of the electric furnace 1, and are passed through the arc electrode 3a. , the straight line of the central axis of 3b, 3c. In the following description, such a straight line may be referred to as a "orthogonal axis" as needed.

Further, the intersection of the right-angle axes 7a, 7b, 7c and the furnace inner surface 5a is referred to as a hot spot 8a, 8b, 8c. The hot spot is that there is one arc electrode, so if there are multiple arc electrodes, there will be the same number of hot spots. In the electric furnace 1 of the present embodiment, since there are three arc electrodes 3a, 3b, and 3c, there are three hot spots 8a, 8b, and 8c. The thermocouples 6a to 6c, 6d to 6f, and 6g to 6i are arranged in a line on the right-angle axes 7a, 7b, and 7c, respectively, with respect to the hot spots 8a, 8b, and 8c. That is, it can be said that the average of the positions of the thermocouples 6a to 6c, 6d to 6f, and 6g to 6i in one row, that is, the position of the center of gravity, are located on the right-angle axes 7a, 7b, and 7c passing through the hot spots 8a, 8b, and 8c, respectively.

The height positions of the hot spots 8a, 8b, 8c should be set such that when the waste material 9 is completely melted and dropped, it will be located above the furnace surface of the molten steel 10. The height positions of the hot spots 8a, 8b, and 8c are located at height positions of the thermocouples 6a to 6c, 6d to 6f, and 6g to 6i which are arranged in a row on the right-angle axes 7a, 7b, and 7c with respect to the hot spots 8a, 8b, and 8c. Further, in such a height position, it is preferable to directly receive the height position of the radiant heat which is a radiant heat generated by the arc discharge when the waste material 9 is melted and dropped (in other words, it is assumed that the refractory material of the furnace wall is highly depleted) The height position of the hotspots 8a, 8b, 8c.

When the thermocouples 6a to 6c, 6d to 6f, and 6g to 6i are arranged under the same height, the furnace inner surface 5a is disposed at a position rotated by 45° around the central axis S of the electric furnace 1, such as The time change of the heat flux in the inner surface 5a of the furnace wall calculated later is slow. Further, if the thermocouples 6a to 6c, 6d to 6f, and 6g to 6i are arranged under the same height, the furnace inner surface 5a is disposed at a position rotated by 60° around the central axis S of the electric furnace 1. In the same case, the time change of the heat flux of the inner surface 5a of the furnace wall becomes slow. Therefore, the time integral value of the heat flux of the inner surface 5a of the furnace wall calculated as described later cannot be correctly derived, and it becomes impossible to accurately determine the loss of the refractory material of the furnace wall (whether the furnace wall refractory material is worn out and the furnace wall is fireproof). The degree of material loss). Therefore, in order to suppress the loss of the refractory material of the furnace wall, if measures for reducing the supply of electric power are taken, it may be impossible to adjust the supply electric power to an appropriate value. When the supply electric power cannot be adjusted to an appropriate value, not only the power is lowered, but also the radiant heat received from the arc electrodes 3a, 3b, 3c of the furnace inner surface 5a cannot be appropriately controlled, and the heat load is more. Therefore, it is feared that the loss of the refractory material of the furnace wall becomes severe, and the life of the refractory material of the furnace wall becomes short.

Therefore, it is understood that the columns of the thermocouples 6a to 6c, 6d to 6f, and 6g to 6i are disposed as described above by the right-angle axes 7a, 7b of the hot spots 8a, 8b, 8c located above the furnace surface of the molten steel 10, On 7c, it is most effective for both the increase in power and the longer life of the refractory material of the furnace wall.

In the present embodiment, an example has been described in which the thermocouples 6a to 6c, 6d to 6f, and 6g to 6i are arranged in a line with respect to the respective hot spots 8a, 8b, and 8c. However, the positional relationship of the plurality of thermocouples arranged with respect to each of the hot spots 8a, 8b, and 8c is not limited to the one-dimensional column. For example, a plurality of thermocouples may be inserted into the furnace wall 5 in a two-dimensional or three-dimensional manner in a staggered arrangement.

Among them, the thermocouple group is preferably disposed in the vicinity of the right-angle axes 7a, 7b, and 7c. Specifically, as shown in FIG. 1, the distance from the central axis of the arc electrodes 3a, 3b, 3c to the hot spots 8a, 8b, 8c corresponding to the respective arc electrodes 3a, 3b, 3c is L. The thermocouple group with respect to the hot spots 8a, 8b, and 8c corresponding to the arc electrodes 3a, 3b, and 3c is preferably concentrated in a region within 0.2 L from the right-angle axes 7a, 7b, and 7c to the upper, lower, left, and right sides. The upper and lower sides are parallel to the central axis S of the electric furnace 1, and the left and right directions are perpendicular to the vertical direction (the circumferential direction of the furnace wall 5). Further, the distance between the upper and lower sides is a linear distance measured in parallel with the furnace wall actuating surface 5a. That is, the thermocouple group is a cubic region in which the inside of the furnace wall refractory material is set to enter a rectangle having a side of 0.4L centered on the hot spots 8a, 8b, and 8c. This is because when the thermocouple group is located outside the cube region, the heat flux in the hot spots 8a, 8b, and 8c that are severely depleted cannot be correctly calculated, and it becomes difficult to accurately determine the loss of the refractory material of the furnace wall. Whether the wall refractory material has a loss and the degree of loss of the furnace wall refractory). The thermocouple group is preferably located near the hot spots 8a, 8b, 8c, so that the thermocouple group is more preferably concentrated in a region within 0.1 L from the right-angle axes 7a, 7b, 7c to the upper, lower, left and right.

In the present embodiment, L = 1500 mm. Therefore, the thermocouple group is embedded in the furnace wall refractory material, and is concentrated in a region of 0.2 × 1500 = 300 mm from the right-angle axes 7a, 7b, and 7c to the upper, lower, left, and right sides. Further, the average of the positions of the plurality of thermocouples in a group, i.e., the position of the center of gravity, is preferably set on the right-angle axes 7a, 7b, 7c passing through the hot spots 8a, 8b, 8c.

In the present embodiment, since there are three arc electrodes 3a, 3b, and 3c, there are three hot spots 8a, 8b, and 8c corresponding to the three arc electrodes 3a, 3b, and 3c. If these three places are arranged, one of the thermocouples 6a~6c, 6d~6f, and 6g~6i (or a two-dimensional or three-dimensional group) can be used to determine the loss of the refractory material of the furnace wall (furnace wall). Whether the refractory material has a loss and the degree of loss of the refractory material of the furnace wall). Specifically, since the degree of loss of the refractory material of the furnace wall is different at the three places, the most severe loss of the refractory material of the furnace wall can be determined early, and measures for suppressing the loss of the refractory material of the furnace wall can be taken early.

When the number of arc electrodes disposed in the electric furnace 1 is one, the central axis S of the electric furnace 1 coincides with the central axis of the arc electrode. Therefore, the influence of the radiant heat generated by the arc discharge on the inner surface 5a of the furnace wall is high. Therefore, like the hotspots 8a, 8b, and 8c, it is not clear that the heat influence is easily manifested locally. Therefore, the height positions of the plurality of thermocouples may be located above the furnace bath surface of the molten steel 10 when the waste material 9 is completely melted and dropped. Further, in the present embodiment, a thermocouple is used for the temperature detecting end, but another temperature detecting end such as a radiation thermometer may be used. Further, in the present embodiment, three thermocouples 6a to 6c, 6d to 6f, and 6g to 6i are disposed for each of the hot spots 8a, 8b, and 8c. However, if the inside of the furnace wall 5 (the furnace wall refractory material) of the electric furnace 1 and the outer peripheral surface of the furnace wall 5 of the electric furnace 1 include a plurality of positions inside the furnace wall 5 of the electric furnace 1, and it is in the electric furnace 1 When a plurality of temperature detecting ends are disposed at a plurality of positions in which the position of the furnace wall 5 in the thickness direction is different, the number of temperature detecting ends with respect to one hot spot is not limited to three. That is, the plurality of positions may be positions inside the furnace wall 5 of the electric furnace 1, or the positions of the inner and outer peripheral surfaces of the furnace wall 5 of the electric furnace 1 (in other words, the plurality of positions are the inner surfaces of the furnace wall). The position except the position of 5a).

[Refractory Material Loss Management System] As shown in Fig. 2, the refractory loss management system of the present embodiment includes a refractory loss management device 101, a temperature sampling device 102, a supply power control device 103, and a power supply device 104.

The temperature sampling device 102 obtains the temperatures measured by the thermocouples 6a to 6i in the respective temperature sampling times which are repeated over a predetermined period. The refractory loss management device 101 is an indicator for the operator to evaluate the loss of the refractory material of the furnace wall (whether or not the refractory material of the furnace wall is depleted and the degree of loss of the refractory material of the furnace wall) by performing various calculation processes and the like described later. News. Details of the refractory loss management device 101 will be described later.

The supply power control device 103 controls the operation of the power supply device 104 in accordance with an instruction from the operator. The power supply device 104 supplies electric power to the arc electrodes 3a, 3b, 3c and the hearth electrode 4 in accordance with control by the supply power control device 103.

<Refractory Loss Management Device 101> The refractory loss management device 101 performs an unsteady heat transfer inverse problem analysis based on the temperature measured by the thermocouples 6a to 6i in each temperature sampling time, thereby calculating the furnace inner surface 5a ( The relationship between the heat flux of the hotspots 8a, 8b, 8c) and time, from which the time integral value of the heat flux is calculated.

FIG. 3 is a view showing an example of the functional configuration of the refractory loss management device 101. The hardware of the refractory loss management device 101 can be realized by using, for example, an information processing device including a CPU, a ROM, a RAM, an HDD, and various interfaces, a PLC (Programmable Logic Controller), or a dedicated hardware.

The refractory loss management device 101 includes a heat flux deriving unit 110, a heat flux integrating unit 120, and an output unit 130. Hereinafter, an example of the functions of the respective units will be described.

<<Heat flux derivation unit 110>> The heat flux derivation unit 110 calculates the temperature in the furnace inner surface 5a (hot spots 8a, 8b, 8c) from the temperatures measured by the thermocouples 6a to 6i in each temperature sampling time. And heat flux. Hereinafter, an example of a method of calculating the temperature and heat flux in the inner surface 5a (hot spots 8a, 8b, 8c) of the furnace wall will be described.

<<<Solution of Unsteady Heat Conduction Equation and Calculation of Incident Heat Flux>>> In the present embodiment, the heat flux in the inner surface 5a of the furnace wall is the temperature measured from the thermocouples 6a to 6i. The gradient calculated by the heat transfer inverse problem analysis satisfying the internal and external interpolation function of the unsteady heat conduction equation was calculated by the gradient in the normal direction of the furnace inner surface 5a. In the following description, the temperature measured by the thermocouples 6a to 6i is referred to as "temperature information" as needed. The unsteady heat conduction equation is such that the temperature of the inner surface 5a of the furnace wall is T, the density of the refractory material of the furnace wall is ρ, the specific heat of the refractory material of the furnace wall is C, and the thermal conductivity of the refractory material of the furnace wall is k _x , y The thermal conductivity in the direction is k _y , and the thermal conductivity in the z direction is k _z , which is expressed by the following formula (1).

[Expression 1]

Let the position vector be (x, y, z) and the time be t. Next, x, y, z, t which gives the exact solution of the unsteady heat conduction equation are used as the inner and outer interpolation functions F, the parameter α _j,i , the reference position vector (x ^j , y ^j , y ^j ), the reference The time t ⁱ , the number of reference position vectors N _j and the number of reference times N _i , and the function of giving an exact solution to the unsteady heat conduction equation are expressed using the following equation (2).

[Expression 2]

The (x ^k , y ^k , y ^k ) is used to measure the position vector for temperature information, t ^l is the temperature sampling time, and the temperature information measured in the temperature information measurement position is a _{k, l} , using the following equation (3) Connect the cubic program to determine the parameter α _j,i .

[Expression 3]

The internal and external interpolation function F(x, y, z, t) can be given by the following formula (4).

[Expression 4]

As shown in Fig. 1, in the present embodiment, in the electric furnace 1, the thermocouples 6a to 6c, 6d to 6f, and 6g to 6i are linearly embedded in the furnace wall 5 in a furnace wall refractory having a thickness of 450 mm. The position on the outer peripheral surface and the distance from the outer peripheral surface of the furnace wall 5 are 150 mm and 300 mm. That is, the number N _k of temperature information measurement positions is "3" (N _k = 3). The hot spot for calculating the heat flux is one place, and the heat flux is calculated separately for each of the hot spots 8a, 8b, and 8c. Hereinafter, an example of a method of calculating the heat flux in the hot spot at one of the inner surfaces 5a of the furnace wall from the temperature information inside the furnace wall refractory will be described. Wherein, the thickness direction of the furnace wall refractory material is x, the coordinates of the inner surface 5a of the furnace wall are x=0 mm, and the coordinates of the outer surface of the furnace wall 5 are x=450 mm. Further, the furnace wall refractory has the same isotropic thermal conductivity, so the thermal conductivity is represented by k. The heat flux is calculated by estimating the one-dimensional temperature distribution in the thickness direction of the furnace wall refractory material by using the primary heat conduction equation. That is, the unsteady heat conduction equation corresponding to the formula (1) becomes the following formula (5).

[Expression 5]

Further, the extrapolation function F corresponding to the equation (4) is expressed by the following equation (6).

[Expression 6]

The equation corresponding to the equation (2) indicating the temperature at any position x and time t is expressed by the following equation (7). Where x ^j and t ⁱ are the reference position and the reference time, respectively.

[Expression 7]

Equation (7) considers that there is a virtual heat source at the reference time t ^j at the reference time t ⁱ , and the influence of the virtual heat source is an influence on the temperature in the position x and the time t. Therefore, the reference time t ⁱ is a time that is more past than the time t. Further, the function indicating the influence of the aforementioned virtual heat source is F(xx ^k , tt ^l ). The parameter α _j,i is a weight indicating an influence on the aforementioned imaginary heat source. If the weight can be determined, the temperature at time t in position x can be estimated. However, when the reference time t ^{i is} set to a relatively close past, F(xx ^k , tt ^l ) becomes a sharp function, and the error becomes large.

N _k set temperatures measured location information, and performing the sampling temperature followed by N _l point, t ⁱ obtains the right to influence the reference time from the reference position x ^j in the weight. Here, the number of reference positions x ^j is N _j , and the number of reference times t ⁱ is N _i . That is, using N _k × N _l temperature information, N _j × N _i parameters α _{j, i are obtained} . The method of obtaining the parameter α _j,i is basically determined so as to allow the measured temperature information to be correctly reproduced. Let the temperature information measured at position x ^k and time t ^l be a _k,l . Since T(x ^k , t ^l )=a _k,l , a simultaneous equation of the following equation (8) whose parameter α _j,i is unknown is obtained.

[Expression 8]

In the formula (8), values other than the parameter α _j,i are known. Equation (8) is the basic continuous equation for determining the parameter α _j,i . However, there is no guarantee that the equations of equation (8) will often be solved. Also, sometimes temperature information is placed due to random measurement errors, and a stable solution cannot be obtained.

Using equation (6), and using function F again to represent the right side of equation (8), the equation of equation (8) will become the following equation (9).

[Expression 9]

The right side of equation (9) indicates the estimated value of the temperature information in the temperature information measurement position x ^k and the temperature sampling time t ^l when the parameter α _j,i is determined. Therefore, the right side of equation (9) can be expressed only by T _k,l (index k, l). That is, the equation of the equation (9) becomes the following equation (10). However, T _k,l is expressed by the following formula (11).

[Expression 10]

Here, if the number N _{j of the} reference position x ^j is coincident with the number N _{k of the} temperature information measurement position, and the number N _{i of} the reference time t ⁱ is equal to the number N _{j of the} sampling time j, it is a parameter of the unknown number. The number of α _j,i N _j ×N _{i is} identical to the number N _k ×N _{l of the} equation, and in principle, the simultaneous equation of equation (10) is solved. However, since the reference position x ^j and the reference time t ^{i are taken} , N _j ×N _i and N _k ×N _{l do} not necessarily coincide, and the solution of the simultaneous equation of the equation (10) may not be obtained. Further, even if the number N _j × N _i of the parameter α _j,i of the unknown number coincides with the number N _k ×N _{l of the} equation, it is not guaranteed that a stable solution can be obtained. Such a problem is called "ill-posed problem" as in Non-Patent Documents 1 and 2.

Here, in order to succinctly express the simultaneous equations of the equations (10) and (11), the sets of the double indices (k, l) and (j, i) are each replaced by an index s and p. This can use, for example, the following method. If N _j ×N _i =Q, N _k ×N _l =R, s=N _l (k-1)+l(k=1, 2, ..., N _k , l=1, 2, ... , N _l ), the double exponent (k, l) can be replaced by an exponent s (s = 1, 2, ..., R). Similarly, if p = N _i (j-1) + i (j = 1, 2, ..., N _j , i = 1, 2, ..., N _i ), the double exponent (j, i) Can be replaced by an index p (p = 1, 2, ..., Q).

That is, T _k,l and a _k,l which are matrix vectors of N _k columns N _l rows can be represented by vector components T _s and a _{s of the} R dimension. The α _j,i of the matrix vector of the N _j row N _i row can represent the vector component α _{p of the} Q dimension. F(x ^k -x ^j , t ^l -t ⁱ ) can be represented by a matrix vector F _{s,p of the} R column Q rows. That is, it is represented by T _k,l =T _s , a _k,l =a _s ,α _j,i =α _p ,F(x ^k -x ^j , t ^l -t ⁱ )=F _s,p . These vectors are represented by T, a, and α, and the matrix is represented by F. In this case, the formulas (10) and (11) can be expressed by the following formulas (12) and (13), respectively.

[Expression 11]

Here, a _s is a measured value, and F _s,p is a function value and is a known value. That is, the problem is that the coefficient α _p which can accurately give the measured value of the temperature information is obtained. As mentioned above, the number Q of the unknowns is generally inconsistent with the number R of the equations. In this case, the formula (12) cannot be solved. That is, it will become an "ill-posed problem." Non-patent documents 1 and 2 describe a method called "regularization method" which deals with such a problem. Basically, the coefficient α _p is determined in such a manner that the sum of the squares of the errors of the measured value a _s and the estimated value T _s is the smallest. The sum of such errors is expressed by the following formula (14).

[Expression 12]

The coefficient α _p can be determined in such a manner that the value of the formula (14) can be minimized. However, according to Non-Patent Document 2, a stable solution is often not obtained even in such a manner. According to Non-Patent Document 2, when the amount that can be minimized is set to the following formula (15), a stable solution can be obtained. However, r is a positive constant and will vary depending on the problem. Here, r uses 2.25 × 10 ^-6 .

[Expression 13]

A method of obtaining the coefficient α _p having the smallest formula (15) is described in Non-Patent Documents 1 and 2. According to these Non-Patent Documents 1 and 2, a technique called "Singular Value Decomposition" is used. According to the "Singular Value Decomposition", as shown in Non-Patent Document 3, a matrix of arbitrary R columns and Q rows can be represented by a product of three rectangular matrices. Among the three rectangular matrices, one of them is a matrix in which only the diagonal component is not 0, and the other two are inverse matrices such as the respective transposed matrix, that is, the matrix after the column component and the row component are replaced. The matrix (orthogonal matrix) representation. Therefore, if the singular value decomposition method is applied to the aforementioned matrix F, it is ensured that the above three rectangular matrices satisfying the following formula (16) are definitely present. That is, there are matrices W, W, and V satisfying the following formula (16).

[Expression 14]

Here, Σ is a matrix in which only the aforementioned diagonal component is not 0, and W and V are the aforementioned orthogonal matrix. Also, V' is a transposed matrix of V. However, W is a rectangular matrix of R times, V is a rectangular matrix of Q times, and Σ is a matrix of R rows and Q rows, and the number of diagonal components is a smaller number U of R and Q. That is, U is expressed by the following formula (17).

[Expression 15]

Here, if the nth diagonal component of the matrix Σ is described as σ _n , the components of the matrix W and the s column n rows are described as w _{s,n ,} v _s,n , and the equation (16) can be written as The following formula (18).

[Expression 16]

Bringing the equation (18) into F _s,p of the equation (15), find the coefficient α _{p as} the value of the equation (15) is the smallest. Such a problem can be obtained by the following formula (19) according to Non-Patent Document 1 and Non-Patent Document 2. [Expression 17]

Here, r is a constant and changes depending on the thermal characteristics of the object to be measured by the temperature. If r = 0, the solution of the formula (16) is minimized, but the temperature in this case becomes a temperature which is largely unstable between the temperature information measurement positions and unstable. In the present embodiment, a stable solution is obtained by using a value of r of 1.0 × 10 ^-6 to 5.0 × 10 ^-6 , and the temperature can be accurately estimated. It is also possible to cut a small amount of the test piece which is the same as the target refractory material, and carry out a small-scale preliminary test at a laboratory level, thereby determining the optimum value of r. In the above description, the case where the number N _k × N _l = R of the measurement data of the temperature information related to the calculation of the parameter α _{j, i} is different from the number N _j × N _i = Q of the reference position data is included. However, if the calculation accuracy is considered, the two should be consistent. That is, it is preferably P=Q. If further calculation accuracy is considered, it is preferable that the number of temperature information measurement positions coincides with the number of reference positions, and the number of temperature sample data related to the calculation of the parameter α _{j, i} coincides with the number of reference times.

Substituting the obtained coefficient α _p into the equation (13), the index p is returned to the index j, i, and the index s is returned to the index k, l. That is, the index j is one obtained by dividing p by N _i , and the remainder obtained by the above division calculation becomes the index i. Further, the index k is one obtained by dividing s by N _l plus one, and the remainder obtained by the above division calculation becomes the index l.

Again, the incident heat flux can be calculated as follows. Let (x ₀ , y ₀ , z ₀ ) be the coordinate of the incident heat flux estimation point of the inner surface 5a of the furnace wall. Further, let b be a unit normal vector of the direction of the incident heat flux estimation point outward in the furnace inner surface 5a (i.e., a unit normal vector from the furnace inner surface 5a toward the molten steel side). Further, let K be a matrix composed of thermal conductivity. Further, the following equation (20) is used, that is, the inner product of the unit normal vector b and the temperature gradient in the incident heat flux estimation point is given to the incident heat flux q.

[Number 18]

Here, ∇ is a gradient vector operator, and K is expressed by the following formula (21).

[Expression 19]

In the present embodiment, the thermocouples 6a to 6c, 6d to 6f, and 6g to 6i for temperature information measurement are arranged in one dimension, and the refractories of the thermocouples 6a to 6c, 6d to 6f, and 6g to 6i are embedded. The thermal conductivity is isotropic, so it is set to k _x = k _y = k _z = k. In other words, when the coordinate of the incident heat flux estimation point is x ₀ and the equation (20) is the equation (7), the following equation (22) is obtained.

[Expression 20]

As described above, the incident heat flux in the predetermined position can be calculated from the temperature information.

[Temperature sampling of the interval time and the reference time interval] In this embodiment, the temperature detecting means 102 is the temperature of the sampling start time τ ₁ starts at time intervals Δ ₁ will be N _l views temperature information N _k positions of sampling. The heat flux deriving unit 110 obtains the coefficient α _p from the equation (19) using the sampled temperature information, and obtains the parameter α _j,i in the equation (2). That is, the heat flux deriving unit 110 beginning from the temperature samples, after the temperature of the sample N _l times, before starting the calculation to obtain the coefficients α _p. Thereafter, the heat flux deriving unit 110 calculates the coefficient α _{p in} accordance with the progress of the temperature sampling. The coefficient α _p , that is, the parameter α _j,i is as described above, among the N _j reference positions x ^j , the hypothetical heat source existing in the N _i reference times t ⁱ can be thought of as affecting any coordinates at any time The weight of the temperature. Therefore, the reference time t ⁱ should be considered as the past time. That is, the reference time t ^{i is} preferably from the past time τ ₂ to τ ₂ +(N _i -1) Δ ₂ , and N _i are set at the time interval Δ ₂ . That is, the temperature sampling time t ^l and the reference time t ⁱ are expressed by the following formula (23).

[Expression 21]

Further, in the present embodiment, since one dimension is considered, the influence from the heat source in the past is F(x ^{k -} x ^j , t ^{l -} t ⁱ ) as expressed by the formula (2) or the formula (11), and It is represented by the following formula (24).

[Expression 22]

After the temperature of sample N _l times, the heat flux F function deriving unit 110 is inserted from the inside and outside of formula formula (4) or (6) it, and if [unsteady state heat conduction equation of the solution of the heat flux In the calculation, the matrix F is subjected to singular value decomposition, coefficients are obtained, the estimated temperature is obtained, and the heat flux is obtained.

The reference time t ⁱ is not affected by the calculation even if it is not updated for a certain period of time in the past. However, in order to improve the accuracy of the calculation, it is preferable to update the reference time t ⁱ . For example, if the temperature exceeds the reference number of the sampling number N _{ⁱ i} at time t, the time interval Δ ₂ at the reference time update. However, the reference time t ⁱ associated with the calculation of the coefficient α _j,i must be more than the sampling time of the temperature information associated with the calculation of the parameter α _j,i of the reference time t ⁱ . If the temperature sampling times are larger than both N _{l and} N _i , the temperature sampling number can be expressed by the remaining number system of N _l or N _i . That is, an appropriate number M ₁ or M ₂ can be used, with M ₁ N _l + l (M ₁ =1, 2, ..., l = 1, 2, ..., N _l ), or, M ₂ N _i + i (M ₂ =1, 2, ..., i = 1, 2, ..., N _i ) is expressed. In this case, the temperature information sampling time t ^l and the reference time t ⁱ are expressed by the following equation (25).

[Expression 23]

In this case, the internal and external interpolation function is expressed by the following equation (26).

[Expression 24]

If it is expected that the waste will begin to melt and fall from the beginning of the temperature measurement, the aforementioned M ₁ and M ₂ can be determined beforehand. Therefore, if F is expressed in the equation (26) in advance for each of M ₁ and M ₂ , and Singular Value Decomposition is first performed on each F, the temperature estimation can be performed in a short time. Further, the F of the equation (26) may be obtained together with the progress of the temperature sampling, and the singular value decomposition method may be performed to obtain the coefficient α _p . In this case, I am afraid that the number of calculation steps will increase, and the calculation efficiency will decrease.

Here, let N _l =N _i and let Δ ₁ =Δ ₂ =Δ. That is, the number of reference times associated with the calculation of the coefficient α _j,i is equal to the number of temperature sampling times, so that the time interval of the progress of the temperature sampling is equal to the time interval of the progress of the reference time. At this time, since M ₁ = M ₂ , the formula (26) becomes the following formula (27).

[Expression 25]

Equation (27) is that even if the temperature sampling is progressing, the reference time is updated. Therefore, the heat flux deriving unit 110 first obtains the F shown in the equation (27), and applies the singular value decomposition method described in the previous section [calculation of the solution of the non-steady heat conduction equation and the calculation of the incident heat flux]. The coefficient α can be obtained from the equation (19) according to the progress of the temperature sampling. Thereby, the number of calculation steps is greatly reduced, and the calculation time can be significantly reduced without the accuracy being lowered. Further, when the coefficient α is obtained in advance, the heat flux deriving unit 110 can obtain the heat flux in the furnace inner surface 5a from the equation (20) or the equation (22).

<<Heat Flux Integration Unit 120>> The heat flux integration unit 120 derives the heat flux corresponding to the period of one operation based on the heat flux in each temperature sampling time derived by the heat flux deriving unit 110. Time integral value.

In the electric furnace 1, in order to suppress the loss of the furnace wall 5, the spray material is sprayed onto the furnace inner surface 5a by the time during the operation of the batch type operation or the like. The inventors operated the electric furnace 1 by spraying the sprayed material to the inner surface 5a of the furnace wall at various thicknesses and setting other conditions to be the same, and statistically examined the amount of loss of the refractory material of the furnace wall. The findings of the inventors obtained in this way will be explained. In addition, when it is called a furnace wall, it is a thing which does not contain a spray material.

<<< Insights Obtained by the Inventors>>> FIG. 4 is a view showing an example of electric power (voltage × current) supplied to the arc electrode 3a. Fig. 5 is a view showing an example of the temperature of the furnace wall refractory. 6 is an example of the heat flux of the inner surface 5a of the furnace wall.

In Fig. 5, a curve 501 is a thermocouple showing a position of 150 mm which is embedded in a position where the coordinates on the inner surface 5a (hot spot 8a) of the furnace wall are 0 mm and the line perpendicular to the inner surface 5a of the furnace wall is 150 mm. The temperature measured by the thermocouple 6a shown in Fig. 1. Curve 502 is a thermocouple showing a position embedded at a position of 0 mm on the inner surface 5a (hot spot 8a) of the furnace wall, and a coordinate of 300 mm on a line perpendicular to the inner surface 5a of the furnace wall (Fig. The temperature measured by thermocouple 6b) shown in 1. A curve 503 is a temperature measured by a thermocouple disposed on the inner surface 5a (hot spot 8a) of the furnace wall. In Fig. 5, the case where the value of the curve 503 is fixed means that the temperature on the inner surface 5a (hot spot 8a) of the furnace wall has exceeded the upper limit of the temperature of the thermocouple (the disconnection of the thermocouple has been generated). The curve 504 is a temperature showing the inner surface 5a (hot spot 8a) of the furnace wall which is derived using the curves 501 and 502 as described above.

In Fig. 6, a curve 601 is a heat flux showing the inner surface 5a (hot spot 8a) of the furnace wall which is derived as described above using the curves 501, 502. As described above, the electric furnace 1 is operated in a batch type, and therefore, as shown in Fig. 4, in each operation, electric power is intermittently supplied repeatedly to the arc electrode 3a (in the example shown in Fig. 4, the display is performed 5 Example of secondary operation).

As shown in Fig. 5, the calculated value (curve 504) and the measured value (curve 503) of the temperature of the inner surface 5a (hot spot 8a) of the furnace wall are disposed during the first half of the operation (the inner surface 5a of the furnace wall (hot spot 8a) The period between the thermocouple and the disconnection is slightly uniform. Therefore, it is understood that the temperature of the furnace inner surface 5a (hot spot 8a) is highly accurately derived by the heat flux deriving unit 110 as described above.

Further, when the plotted point of FIG. 4 is compared with the curve 601 of FIG. 6, the time point at which the heat flux shows the peak is slower than the time point at which the power (voltage × current) shows the peak, and a time delay occurs. This is considered to be because the waste which is present in front of the furnace wall refractory material has become a shield for the radiant heat from the arc electrode 3a from the start of operation until the waste material is melted and dropped. Therefore, as described above, it is understood that the heat flux of the furnace inner surface 5a (hot spot 8a) derived by the heat flux deriving unit 110 accurately reflects the state of the electric furnace 1.

Fig. 7 is a view showing an example of the relationship between the thickness of the spray material before the start of the operation (the remaining thickness of the spray before the start of the operation) and the thickness of the spray material after the completion of the operation (the remaining thickness of the spray after the operation is completed). As described above, when the spray material is sprayed to operate the electric furnace 1, the following operation is performed: the spray material remains in the state of the surface of the furnace wall refractory, and the furnace wall refractory is suppressed as much as possible. Loss. If the thickness of the spray material before the start of the operation is sufficient, the spray material remains after the operation, and the loss of the refractory material of the furnace wall can be avoided. On the other hand, when the thickness of the spray material before the start of the operation is insufficient, the thickness of the spray material during operation will be 0 (zero), and it is expected that the loss of the refractory material of the furnace wall will be obtained.

In Fig. 7, the area i, the area ii, and the area iii are distinguished by a one-dot chain line. Since the thickness of the spray material before the start of the operation is insufficient in the area i, the thickness of the spray material is 0 (zero) between the end of the operation, and corresponds to the state in which the loss of the refractory material of the furnace wall is performed. On the other hand, in the region iii, since the thickness of the spray material before the start of the operation is sufficient, the spray material remains after the operation is completed, and the state in which the loss of the refractory material of the furnace wall can be avoided. The area ii is an intermediate state between the area i and the area iii.

Fig. 8A is an example of heat flux showing the inner surface 5a (hot spot 8a) of the furnace wall. Fig. 8B is an example showing a gradient of the heat flux (amount of change in heat flux per unit time) of the furnace inner surface 5a (hot spot 8a). In Fig. 8A, a curve 801 is a heat flux of the inner surface 5a (hot spot 8a) of the furnace wall. In Fig. 8A, the temperature (curve 802) of the inner surface 5a (hot spot 8a) of the furnace wall and the effective electric power to the arc electrode 3a (curve 803) are shown together. Further, in Fig. 8A, the numbers indicated on the curves 801 to 803 indicate the thickness of the spray material before the start of the operation in each operation (the residual thickness of the spray before the start of the operation) and the spray material after the operation is completed. The thickness (the residual thickness of the spray after the end of operation) and the amount of loss of the refractory material of the furnace wall. For example, "62→3(0)" means that the thickness of the spray material before the start of the operation is 62 mm, the thickness of the spray material after the operation is 3 mm, and the loss of the refractory material of the furnace wall is 0 (zero) mm. . Further, "3 → 0 (-30)" means that the thickness of the spray material before the start of the operation is 3 mm, the thickness of the spray material after the operation is 0 mm, and the loss of the refractory material of the furnace wall is 30 mm (the furnace wall) The thickness of the refractory material is reduced by 30 mm). Moreover, in two consecutive operations, the thickness of the spray material before the start of operation in the latter operation is thicker than the thickness of the spray material before the start of operation in the previous operation, because in the two operations The spray material is sprayed to the inner surface 5a of the furnace wall.

The damage mechanism of the refractory material in the hot spot is considered as follows. The melting or volatilization of the refractory material is caused by the high temperature of the arc, in addition to the erosion of waste and smoke. Further, the temperature change in the furnace causes heat to be peeled off, and the formation of the altered layer by the penetration of the waste is closely related to the peeling of the structure. It is also known that the ambient gas in the furnace has an effect on the melting loss of the refractory material. It has also been pointed out that the electromagnetic induction phenomenon in the surface tension is related to the damage. As such, due to the complexity of the damage mechanism, effective indicators for evaluating the amount of refractory loss in operation have not yet been identified. The inventors have judged that the main cause of the loss of the refractory material of the furnace wall is the heat load of the refractory material of the furnace wall, and the time integral value of the heat flux of the inner surface 5a of the furnace wall. Therefore, the amount of loss of the refractory material of the furnace wall is evaluated by the time integral value of the heat flux of the inner surface 5a of the furnace wall.

Further, from the result shown in Fig. 7, it is considered that when the thickness of the spray material before the start of the operation is less than a certain value (the example shown in Fig. 7 is about 30 mm), the effect of suppressing the heat load of the refractory material is lost. The heat flux of the inner surface 5a of the furnace wall will rise sharply. This condition was found to correspond to the gradient of the heat flux of the inner surface 5a of the furnace wall. As can be seen from Fig. 8A, when the thickness of the spray material after the completion of the operation is 30 mm or more, the heat flux of the inner wall surface 5a of the furnace wall is not increased sharply (see the numerical value of the tip end of the arrow mark in Fig. 8A and the curve 801). In addition, as shown in FIG. 8B, the heat flux of the inner surface 5a of the furnace wall rises sharply at a time point when the gradient of the heat flux of the furnace inner surface 5a becomes 60 kcal/m ² ·Hr/s or more.

Thus, the inventors have obtained the following observation: the time point at which the time integral value of the heat flux of the inner surface 5a of the furnace wall is started to be calculated is the time point at which the gradient of the heat flux of the inner surface 5a of the furnace wall exceeds the critical value. . On the other hand, the time point at which the time integral value of the heat flux of the inner surface 5a of the furnace wall is calculated is the time point corresponding to the timing at which the operation ends. Here, a case where the time point at which the effective electric power of the arc electrode is 0 (zero) is set as the time point at which the calculation of the time integral value of the heat flux of the inner surface 5a of the furnace wall is completed is exemplified.

The inventors reviewed the causal relationship between the time integral value of the heat flux of the inner surface 5a of the furnace wall and the amount of loss of the refractory material of the furnace wall. Fig. 9 is a graph showing the relationship between the amount of loss of the furnace wall refractory in each feed (ch) and the time integral value (cumulative heat flux) of the heat flux of the inner surface 5a of the furnace wall. Furthermore, the amount of loss of the refractory material of the furnace wall is a reduction amount of the thickness of the refractory material of the furnace wall when the state in which the refractory material of the furnace wall is not lost is 0 (zero), and the larger the reduction amount is displayed in the negative direction. Larger value (the value itself will become smaller).

In Fig. 9, according to the three groups of regions i, ii, and iii shown in Fig. 7, the amount of loss of the furnace wall refractories in each feed (ch) is recorded, and the inner surface of the furnace wall in the feed is recorded. The relationship between the time integral value (cumulative heat flux) of the heat flux of 5a. That is, in Fig. 9, when the thickness of the spray material before the start of the operation (the remaining thickness of the spray before the start of the operation) d is 120 mm or more, it is recorded at 30 mm or more, less than 120 mm, and less than 30 mm.

Referring to Fig. 7, the extent to which the loss of the refractory material of the furnace wall is performed may vary depending on the thickness (regions i, ii, iii) of the spray material before the start of the operation. Therefore, the inventors have thought of the loss of the refractory material of the furnace wall in each feed (ch) according to the three groups of regions i, ii, iii shown in Fig. 7 and the furnace wall in the feed. Whether the correlation of the time integral value (cumulative heat flux) of the heat flux of the surface 5a is clearly obtained.

Figure 10 is a time integral value (cumulative heat flux) of the amount of refractory of the furnace wall in each of the feeds (ch) shown in Figure 9 and the heat flux of the inner surface 5a of the furnace wall of the feed. In the relationship, only the relationship in which the thickness of the spray material before the start of the operation (the residual thickness of the spray before the start of operation) d is less than 30 mm is shown. Figure 11 is a time integral value (cumulative heat flux) of the amount of refractory of the furnace wall in each of the feeds (ch) shown in Figure 9 and the heat flux of the inner surface 5a of the furnace wall of the feed. In the relationship, only the relationship between the thickness of the spray material before the start of the operation (the residual thickness of the spray before the start of the operation) d is 120 mm or more is displayed.

As explained with reference to Fig. 7, when the thickness of the spray material before the start of the operation (the residual thickness of the spray before the start of operation) d is less than 30 mm, the deterioration of the refractory material of the furnace wall becomes remarkable. As shown in Fig. 10, when the thickness of the spray material before the start of the operation (the residual thickness of the spray before the start of operation) d is less than 30 mm, the time integral value of the heat flux with the inner surface 5a of the furnace wall (accumulated heat flux) The amount of refractory loss of the furnace wall increases linearly in the negative direction (the value itself decreases).

Further, as described with reference to Fig. 7, when the thickness of the spray material before the start of the operation (the remaining thickness of the spray before the start of the operation) d is 120 mm or more, the loss of the refractory material of the furnace wall can be avoided. As shown in Fig. 11, if the thickness of the spray material before the start of the operation (the residual thickness of the spray before the start of operation) d is 120 mm or more, the time integral value of the heat flux with the inner surface 5a of the furnace wall (cumulative heat flux) Regardless of the amount of damage to the furnace wall refractories, it almost becomes 0 (zero).

As described above, the inventors have found that if the thickness of the spray material is significantly reduced, the amount of loss of the furnace wall refractory in each feed (ch) and the heat of the inner surface 5a of the furnace wall of the feed The relationship of the time integral value (cumulative heat flux) of the flux can be approximated to a proportional relationship, which clearly corresponds to both.

According to the above findings, in the present embodiment, the heat flux integrating unit 120 derives the period corresponding to one operation based on the heat flux in each temperature sampling time derived by the heat flux deriving unit 110. The time integral value of the heat flux of the inner surface 5a (hotspots 8a, 8b, 8c) of the inner wall of the furnace wall.

<<Output Unit 130>> The output unit 130 outputs information derived from the heat flux integrating unit 120 and including a time integral value corresponding to the heat flux during the period of one operation. This information is used as an indicator for the operator to evaluate the loss of the refractory material of the furnace wall (whether the refractory material of the furnace wall is depleted and the degree of refractory loss of the furnace wall). The output unit 130 outputs, for example, information including a time integral value corresponding to the heat flux in the period of one operation and a time transition of the heat flux in the operation. As a form of outputting related information, for example, any of a memory medium or a portable memory medium inside the refractory loss management device 101, a display to a computer display, and a transmission to an external device can be employed.

When the time integral value of the heat flux outputted by the output unit 130 corresponding to the one-time operation exceeds a predetermined threshold value, the operator determines that the loss of the furnace wall refractory material is continuing, and operates the supply. The power control device 103 issues an instruction to lower the supply of electric power to the arc electrodes 3a, 3b, 3c or to suspend operation. The critical value can be appropriately set according to the upper limit value of the amount of loss of the refractory material of the furnace wall and the management policy. The supply power control device 103 controls the operation of the power supply device 104 in accordance with an instruction from the operator, and causes the supplied power to be a positive value or 0 (zero) lower than the current value.

[Operation Flowchart] Next, an example of the operation of the refractory loss management device 101 will be described with reference to the flowchart of Fig. 12 . First, in step S1201, the heat flux deriving unit 110 derives the heat flux of the furnace inner surface 5a (the hot spots 8a, 8b, 8c). Further, the heat flux of the furnace inner surface 5a (the hot spots 8a, 8b, 8c) is individually derived depending on the hot spots 8a, 8b, 8c.

Next, in step S1202, the heat flux integrating unit 120 derives the gradient of the heat flux (the amount of change in the heat flux per unit time) of the furnace inner surface 5a (the hot spots 8a, 8b, 8c) derived in step S1201.

Next, in step S1203, the heat flux integrating unit 120 determines whether or not the gradient of the heat flux of the furnace inner surface 5a (the hot spots 8a, 8b, 8c) derived in step S1202 exceeds the critical value. If the result of this determination is that the gradient of the heat flux of the furnace inner surface 5a (the hot spots 8a, 8b, 8c) does not exceed the critical value, the process returns to step S1201, and the processes of steps S1201 to S1203 are repeated until the furnace wall The gradient of the heat flux of the inner face 5a (hotspots 8a, 8b, 8c) exceeds the critical value.

Next, when the gradient of the heat flux of the furnace inner surface 5a (the hot spots 8a, 8b, 8c) exceeds the critical value, the process proceeds to step S1204. When the process proceeds to step S1204, the heat flux integrating unit 120 derives the time integral value of the heat flux of the furnace inner surface 5a (the hot spots 8a, 8b, 8c).

Next, in step S1205, the heat flux integrating unit 120 determines whether or not the effective electric power to the arc electrodes 3a, 3b, and 3c is 0 (zero). If the result of this determination is that the effective power to the arc electrodes 3a, 3b, 3c is not 0 (zero), the process returns to step S1204, and the processes of steps S1204, S1205 are repeated until it is determined that the arc electrodes 3a, 3b, 3c are present. The effective power is 0 (zero). In this case, the time integral value of the heat flux of the inner wall surface 5a (hot spots 8a, 8b, 8c) of the furnace wall is continued.

Next, when it is determined that the effective electric power to the arc electrodes 3a, 3b, 3c is 0 (zero), the process proceeds to step S1206. At this time, after the gradient of the heat flux of the furnace inner surface 5a (the hot spots 8a, 8b, 8c) exceeds the critical value, the effective electric power to the arc electrodes 3a, 3b, 3c is 0 (zero). The value is the time integral value of the heat flux of the inner surface 5a (hot spots 8a, 8b, 8c) of the furnace wall.

When the process proceeds to step S1206, the output unit 130 outputs information including the time integral value of the heat flux of the furnace inner surface 5a (the hot spots 8a, 8b, 8c) in the period corresponding to the one-time operation.

Next, in step S1207, the refractory loss management device 101 determines whether or not the operation of the electric furnace 1 is completed. The operator can operate the refractory loss management device 101 and perform the determination by instructing the end of the operation of the electric furnace 1. If the result of this determination is that the operation of the electric furnace 1 is not completed, the process returns to step S1201, and the processes of steps S1201 to S1207 are repeated until it is determined that the operation of the electric furnace 1 is completed. Next, when it is determined that the operation of the electric furnace 1 is completed, the processing of the flowchart of Fig. 12 is ended.

Next, an example of the processing performed by the heat flux deriving unit 110 (step S1201) will be described with reference to the flowcharts of FIGS. 13 to 16. The heat flux deriving unit 110 mainly performs processing including a pre-preparation step (Fig. 13), a temperature information sampling step (Fig. 14), a memory operation step (Fig. 15), and a heat flux calculation step (Fig. 16). Here, the interval between the temperature sampling time and the reference time interval is also Δ. That is, there is only one matrix F set to require prior calculation.

In the pre-preparation step shown in FIG. 13, first, in step S1301, the heat flux deriving unit 110 inputs various parameters. Deriving heat flux input portion 110, for example, the number of times the measurement position of the reference position vector ^{(x j, y j, y} j), the temperature information N _k, the temperature of the sample N _l, the number N _j x ^j of the reference position, the reference time t ⁱ number N _i , temperature information measurement position vector (x ^k , y ^k , y ^k ), temperature sampling time / reference time interval Δ, temperature sampling start time τ ₁ , past time τ ₂ , internal and external interpolation function F ( x, y, z, t), thermal conductivity k _x , k _y , k _{z of the} refractory material and a positive constant r.

Next, in step S1302, the heat flux deriving unit 110 derives the matrix vector F _s,p from the inner extrapolation function F composed of the equation (4) or the equation (6). Specifically, the matrix vectors F _{s,p are} derived using the following equations (28) to (31). F(x ^k -x ^j , y ^k -y ^j , z ^k -z ^j , t ^l -t ⁱ )=F(x ^k -x ^j , y ^k -y ^j , z ^k -z ^j , τ ₂ - τ ₁ +(li)Δ) (28) s=N _l (k-1)+l (k=1,2,...,N _k :l=1,2,...,N _l ) (29) p=N _i (j-1)+i(j=1,2,...,N _j :i=1,2,...,N _i ) (30) F _s,p =F(x ^k -x ^j ,y ^k -y ^j ,z ^k -z ^j ,τ ₂ -τ ₁ +(li)Δ) (s=1,2,...,N _k × N _l =R:p=1,2,..., N _j ×N _i =Q)...(31)

Next, in step S1303, the heat flux deriving unit 110 performs singular value decomposition on the matrix vectors F _s,p to derive matrices W, V, and 满足 satisfying the equation (16) or (18). The method of singular value decomposition can be realized by using a general method shown in Non-Patent Document 1 to Non-Patent Document 3. When the pre-preparation step of FIG. 13 is completed, the temperature information acquisition preparation state is obtained. Furthermore, the time point at which the pre-preparation step of FIG. 13 is performed may be any time point before the temperature information sampling step of FIG. 14 is executed. The pre-preparation step of FIG. 13 can also be performed before starting the flowchart of FIG.

After the preparatory step of FIG. 13 is completed, the heat flux deriving unit 110 executes the temperature information sampling step of FIG. First, in step S1401, the heat flux derivation unit 110 stands by until the reception start signal. The start signal is, for example, a signal from an external device or a signal generated by an operator operating the refractory loss management device 101.

When the start signal is received, the process proceeds to step S1402. When the process proceeds to step S1402, the heat flux deriving unit 110 sets the start time t to "0 (zero)" (t = 0). Further, the heat flux derivation unit 110 sets the counter variable c to "1" (c = 1). Next, in step S1403, the heat flux deriving unit 110 stands by to become the temperature sampling start time τ ₁ . When the temperature sampling start time τ ₁ is reached, the process proceeds to step S1404.

When the process proceeds to step S1404, the temperature sampling device 102 performs sampling of the temperature information in the N _k temperature information measurement positions. That is, the temperature sampling device 102 acquires N _k pieces of temperature information in one temperature sampling. The heat flux derivation unit 110 temporarily stores the N _k pieces of temperature information acquired by the temperature sampling device 102 in the buffer memory together with the counter variable c. Here, the buffer memory can be said to be an area in which information is temporarily stored first.

Next, in step S1405, the heat flux deriving unit 110 calls the memory operating step. Thereby, the processing performed by the memory operation step of Fig. 15 is started. Next, in step S1406, the heat flux derivation unit 110 adds the counter variable c to "1", and updates the counter variable c.

Next, in step S1407, the heat flux derivation unit 110 determines whether or not the end signal has been received. The end signal is, for example, a signal from an external device or a signal generated by an operator performing an operation on the refractory loss management device 101. If the result of this determination is that the end signal has not been received, the process returns to step S1403 and waits until the next sampling start time. On the other hand, when the end signal is received, the processing performed by the flowchart of Fig. 14 is ended. Thus, in the temperature information sampling step, the sampling of the temperature information, the update of the counter variable c, the temperature information, and the transmission of the counter variable are repeated each time the sampling start time is reached. This continues until the reception end signal.

In step S1405 of Fig. 14, the memory operation step of Fig. 15 is started each time the memory operation step is called (each time N _k temperature information and counter variable c are temporarily stored in the buffer memory). In the memory operation step, the temperature information of the buffer memory and the counter variable c are stored in the working memory. Here, the working memory refers to an area for storing information used for calculation of heat flux.

Specifically, first, in step S1501, the heat flux derivation unit 110 determines whether or not the counter variable c temporarily stored in the buffer memory is lower than the number N _{l of} temperature samples. If the result of this determination is that the counter variable c is lower than the number N _{1 of} temperature samples, the process proceeds to step S1502. When the process proceeds to step S1502, the heat flux deriving unit 110 sets the temperature information temporarily stored in the buffer memory to a _k,c (k=1, 2, . . . , N _k , c=1, 2, .. ., N _l ) is stored in working memory. Further, the heat flux deriving unit 110 stores the counter variable c corresponding to the temperature information in the working memory. Next, the processing performed by the flowchart of Fig. 15 is ended.

On the other hand, if the counter variable c is lower than the number N _{l of} temperature samples, the flow proceeds to step S1503. When the process proceeds to step S1503, the heat flux derivation unit 110 determines whether or not the counter variable c temporarily stored in the buffer memory is equal to the number N _{l of} temperature samples. If the result of the determination is that the counter variable c is equal to the number of times of the temperature sampling N _l , the process proceeds to step S1504.

When the process proceeds to step S1504, the heat flux deriving unit 110 sets the temperature information temporarily stored in the buffer memory to a _k,c (k=1, 2, . . . , N _k , c=1, 2, .. ., N _l ) is stored in working memory. Further, the heat flux deriving unit 110 stores the counter variable c corresponding to the temperature information in the working memory. Thereby, N _k × N _l temperature information a _{k, l} and the latest counter variable c are stored in the working memory.

Therefore, in step S1505, the heat flux deriving unit 110 calls the heat flux calculating step. Thereby, the processing performed by the heat flux calculation step of Fig. 16 is started. Next, the processing performed by the flowchart of Fig. 15 is ended.

In step S1503, when it is determined that the counter variable c temporarily stored in the buffer memory is not equal to the number N _{l of} temperature samples (that is, when the counter variable c temporarily stored in the buffer memory is equal to or greater than the number N ₁ of temperature samples), Proceed to step S1506. When the process proceeds to step S1506, the heat flux deriving unit 110 deletes N _k × N _l temperature information a _{k, l} (k=1, 2, ..., N _k , l already stored in the working memory from the working memory. =1, 2, ..., N _l ) The oldest l = 1 temperature information, l l 2, let l → l-1, rewritten as a new a _{k, l} (k = 1, 2 , ..., N _k , l=1, 2, ..., N _l -1), and updated. Next, the heat flux deriving unit 110 stores the latest N _k temperature information temporarily stored in the buffer memory as a _{k, l} (l=N _l ) and stores it in the working memory, and further, corresponds to the temperature information. The counter variable c is stored in the working memory. Thereafter, the process proceeds to step S1505, and the heat flux deriving unit 110 calls the heat flux calculating step. In this way, in the memory operation step, each time the temperature information and the counter variable c are temporarily stored in the buffer memory, the working memory is updated. As a result, if N _k × N _l temperature information a _{k, l is} stored in the working memory, the heat flux calculation step is called.

In step S1505 of Fig. 15, the heat flux calculation step of Fig. 16 is started each time the heat flux calculation step (N _k × N _l temperature information a _{k, l} update in each working memory) is called. First, in step S1601, the heat flux deriving unit 110 is based on N _k × N _l temperature information a _{k, l} (k=1, 2, . . . , N _k , l=1, stored in the working memory. 2,..., N _l ), the coefficient α _{p is} obtained from the equation (19). Next, the heat flux deriving unit 110 replaces the index p with the index j, i and derives the parameter α _j,i .

Next, in step S1602, the heat flux deriving unit 110 derives the latest data acquisition time t = τ ₁ + (c - 1) Δ based on the counter variable c stored in the working memory. Next, in step S1603, the heat flux deriving unit 110 calculates the heat flux q in the inner surface 5a of the furnace wall from the equation (20) or the equation (22). Next, the processing performed by the flowchart of Fig. 16 is ended. Further, in the case where there is a problem such as failure in temperature sampling, a step having redundancy may be placed between the above steps, but the problem is not particularly found in the present embodiment.

FIG. 17 shows an example of the hardware configuration of the refractory loss management device 101. In FIG. 17, the refractory loss management apparatus 101 includes a CPU 1701, a main memory device 1702, an auxiliary memory device 1703, a communication circuit 1704, a signal processing circuit 1705, an image processing circuit 1706, an I/F circuit 1707, a user interface 1708, Display 1709 and bus bar 1710.

The CPU 1701 integrates and controls the entire refractory loss management device 101. The CPU 1701 executes the program stored in the auxiliary storage device 1703 using the main memory device 1702 as a work area. The main memory device 1702 temporarily stores the data. The auxiliary storage device 1703 stores various materials in addition to the program executed by the CPU 1701.

The communication circuit 1704 is a circuit for performing external communication with the refractory loss management device 101. The communication circuit 1704 can also perform wireless communication with the outside of the refractory loss management device 101, or can perform wired communication.

The signal processing circuit 1705 performs various kinds of signal processing on the signal received by the communication circuit 1704 or the signal input according to the control of the CPU 1701. The heat flux derivation unit 101 and the heat flux integration unit 120 are realized by using, for example, the CPU 1701 and the signal processing circuit 1705.

The image processing circuit 1706 performs various kinds of image processing on signals input in accordance with control by the CPU 1701. The signal subjected to the image processing is output to the display 1709. The user interface 1708 is the portion of the operator that indicates the refractory loss management device 101. User interface 1708 has, for example, buttons, switches, dials, and the like. Further, user interface 1708 can have a graphical user interface using display 1709.

The display 1709 displays an image according to a signal output from the image processing circuit 1706. The I/F circuit 1707 performs data access between it and the device connected to the I/F circuit 1707. In Fig. 17, as a device connected to the I/F circuit 1707, a user interface 1708 and a display 1709 are displayed. However, the devices connected to the I/F circuit 1707 are not limited to the devices. For example, a portable memory medium can also be connected to the I/F circuit 1707. Moreover, at least a portion of the user interface 1708 and the display 1709 can also be external to the refractory loss management device 101. The output unit 130 is realized by, for example, the communication circuit 1704 and the signal processing circuit 1705, and at least one of the image processing circuit 1706, the I/F circuit 1707, and the display 1709.

Further, the CPU 1701, the main memory device 1702, the auxiliary memory device 1703, the signal processing circuit 1705, the image processing circuit 1706, and the I/F circuit 1707 are connected to the bus bar 1710. Communication between the constituent elements is performed through the bus bar 1710. Further, the hardware of the refractory loss management device 101 is not limited to that shown in Fig. 17 as long as the function of the refractory loss management device 101 described above can be realized.

[Conclusion] As described above, in the present embodiment, the problem of the unsteady heat transfer inverse problem is analyzed based on the temperature measured by the thermocouples 6a to 6i in each temperature sampling time, thereby deriving the inner surface 5a of the furnace wall (hot spot). The relationship between the heat flux of 8a, 8b, 8c) and time. Further, from this result, the time integral value corresponding to the heat flux during the period of one operation is derived and output. Therefore, the heat flux of the furnace inner surface 5a (the hot spots 8a, 8b, 8c) can be derived in consideration of the temperature of the non-steady state change. Further, it is apparent that the amount of loss of the refractory material of the furnace wall in each of the feeds corresponds to the time integral value of the heat flux of the inner surface 5a of the furnace wall of the feed. Therefore, the loss of the refractory material constituting the furnace wall of the electric furnace which melts the waste by the arc discharge can be monitored with high precision. Thereby, the productivity in the electric furnace can be maintained, and the maintenance cost of the refractory material can be reduced.

[Modification] In the present embodiment, when the time integral value of the heat flux of the furnace inner surface 5a is derived, the time point at which the integration is started/ended is not limited as long as it corresponds to the period of one operation. For example, the timing at which the operation is started may be set as the time point at which the time integral value of the heat flux of the inner surface 5a of the furnace wall is started to be derived. Further, after starting to derive the time integral value of the heat flux of the inner surface 5a of the furnace wall, the time point at which the operation time is assumed to be set in advance may be set as the end of the heat flux of the inner surface 5a of the furnace wall. The point in time of the time integral value. According to the above embodiment, the time point at which the effective electric power is set to 0 (zero) for the arc electrode can be set as the time point at which the time integral value of the heat flux of the inner wall surface 5a of the furnace wall is ended.

However, in the electric furnace 1 in operation, the heat flux of the inner surface 5a of the furnace wall is sometimes negative. In the present embodiment, when the heat flux of the inner surface 5a of the furnace wall is positive, the refractory material receives a heat load and causes loss. When the heat flux is negative, the refractory material cannot be recovered. Therefore, when the heat flux is negative, if the heat flux is integrated, it becomes a factor that reduces the accuracy of the evaluation index as the loss amount. Therefore, in the present embodiment, it is preferable to set the time point at which the gradient of the heat flux of the furnace inner surface 5a exceeds the critical value as the time point at which the time integral value of the heat flux of the inner wall surface 5a of the furnace wall is started.

Further, the time point at which the heat flux of the inner surface 5a of the furnace wall is negative from 0 (zero) or a positive predetermined value may be set as the time integral value at which the heat flux of the inner wall surface 5a of the furnace wall is started to be derived.

Further, after starting to derive the time integral value of the heat flux of the inner surface 5a of the furnace wall, the time at which the value of the heat flux of the inner surface 5a of the furnace wall starts to be 0 (zero) may be set to end the discharge into the furnace wall. The time point of the time integral value of the heat flux of face 5a.

Further, while the time integral value of the heat flux of the inner surface 5a of the furnace wall is derived, if the value of the heat flux of the inner surface 5a of the furnace wall is negative, the negative value may be 0 (zero), and the furnace may be led out. The time integral value of the heat flux of the inner surface 5a of the wall.

Further, in the present embodiment, the case where the time integral value of the heat flux in the period of one operation exceeds a predetermined threshold value and the supply of electric power to the arc electrodes 3a, 3b, and 3c is reduced is exemplified. And the explanation. However, if measures are taken to suppress the loss of the refractory material of the furnace wall, it is not necessary to take measures to reduce the supply of electric power to the arc electrodes 3a, 3b, 3c. For example, by forming the waste material, the measure of the waste between the hot spots 8a, 8b, 8c and the arc electrodes 3a, 3b, 3c may be added or replaced to reduce the supply of electric power to the arc electrodes 3a, 3b, 3c. Measures.

Alternatively, the equation or list indicating the relationship between the amount of loss of the refractory material of the furnace wall and the time integral value of the heat flux of the inner surface 5a of the furnace wall as shown in FIG. 10 may be memorized first, according to which the inner surface of the furnace wall is The time integral value of the heat flux of 5a, the amount of loss of the refractory material of the furnace wall is derived and output.

Furthermore, the embodiment of the present invention described above can be realized by executing a program by a computer. Further, a computer program product in which a recording medium capable of supplying power brain reading and a program such as the above program can be applied to the embodiment of the present invention. The recording medium can use, for example, a flexible disc, a hard disc, a compact disc, a magneto-optical disc, a CD-ROM, a magnetic tape, a non-volatile memory card, a ROM, or the like. Further, the embodiments of the present invention described above are merely illustrative of specific examples when the present invention is implemented, and the technical scope of the present invention is not limited by the above. That is, the present invention can be implemented in various forms without departing from the technical idea or its main features. Industrial availability

The present invention can be utilized for management of an electric furnace for melting waste, and the like.

1‧‧‧Electric furnace

2‧‧‧Upper cover

3a~3c‧‧‧Arc Electrode

4‧‧‧ bottom electrode

5‧‧‧ furnace wall

5a‧‧‧ inner surface of the furnace wall

6a~6i‧‧‧ thermocouple

7a, 7b, 7c‧‧‧ straight line

8a, 8b, 8c‧‧‧ hotspots

9‧‧‧ scrap

10‧‧‧Fused steel

101‧‧‧ Refractory loss management device

102‧‧‧ Temperature sampling device

103‧‧‧Supply power control unit

104‧‧‧Power supply unit

110‧‧‧Heat Flux Export Department

120‧‧‧Heat Flux Integration Department

130‧‧‧Output Department

501‧‧‧ Curve

502‧‧‧ Curve

503‧‧‧ Curve

504‧‧‧ Curve

601‧‧‧ Curve

801~803‧‧‧ Curve

1701‧‧‧CPU

1702‧‧‧Main memory device

1703‧‧‧Auxiliary memory device

1704‧‧‧Communication circuit

1705‧‧‧Signal Processing Circuit

1706‧‧‧Image Processing Circuit

1707‧‧‧I/F circuit

1708‧‧‧User interface

1709‧‧‧ display

1710‧‧‧ Busbar

S1201~S1207‧‧‧Steps

S1301~S1030‧‧‧Steps

S1401~S1407‧‧‧Steps

S1501~S1505‧‧‧Steps

S1601~S1603‧‧‧Steps

F‧‧‧Interpolation function

T‧‧‧temperature

L‧‧‧ distance

S‧‧‧ central axis

Fig. 1 shows an example of a schematic configuration of a refractory loss management system together with a plan view of an electric furnace. Fig. 2 is a view showing an example of a schematic configuration of a refractory loss management system together with a cross-sectional view of an electric furnace. Fig. 3 is a view showing an example of the functional configuration of the refractory loss management device. Fig. 4 is a view showing an example of supply of electric power (voltage × current) to an arc electrode. Fig. 5 is a view showing an example of the temperature of the furnace wall refractory. Fig. 6 is a view showing an example of heat flux on the inner surface of the furnace wall. Fig. 7 is a view showing an example of the relationship between the thickness of the spray material before the start of the operation (the remaining thickness of the spray before the start of the operation) and the thickness of the spray material after the completion of the operation (the remaining thickness of the spray after the operation is completed). Fig. 8A is an example of a heat flux showing a hot spot. Fig. 8B is an example showing the gradient of the heat flux of the hot spot (the amount of change in the heat flux per unit time). Fig. 9 is a view showing an example of the relationship between the amount of loss of the refractory material of the furnace wall at each feed (ch) and the time integral value (cumulative heat flux) of the heat flux on the inner surface of the furnace wall. Figure 10 is a graph showing the amount of refractory loss of the furnace wall at each feed (ch) and the furnace wall at the feed when the thickness of the spray material before the start of operation (the residual thickness of the spray before the start of operation) is less than 30 mm. An example of the relationship between the time integral value (cumulative heat flux) of the heat flux inside. Figure 11 is a graph showing the amount of refractory loss of the furnace wall at each feed (ch) and the furnace in the feed when the thickness of the spray material before the start of operation (the residual thickness of the spray before the start of operation) is 120 mm or more. An example of the relationship between the time integral value (cumulative heat flux) of the heat flux inside the wall. Fig. 12 is a flow chart showing an example of the operation of the refractory loss management device. FIG. 13 is a flowchart illustrating an example of processing (pre-preparation step) performed by the heat flux deriving unit. FIG. 14 is a flowchart illustrating an example of processing (temperature information sampling step) performed by the heat flux deriving unit. Fig. 15 is a flowchart for explaining an example of processing (memory operation step) performed by the heat flux deriving unit. FIG. 16 is a flowchart illustrating an example of processing (heat flux calculation step) performed by the heat flux deriving unit. Fig. 17 is a view showing an example of a hardware configuration of the refractory loss management device.

Claims (5)

A refractory material loss management device for an electric furnace is for managing loss of a refractory material constituting a furnace wall of an electric furnace, wherein the electric furnace is melted by an arc discharge generated at an arc electrode, and the refractory material loss management device of the electric furnace is The heat flux deriving means is a temperature which is disposed at a plurality of positions different from each other in the thickness direction of the furnace wall of the electric furnace according to the inside of the furnace wall of the electric furnace and the outer peripheral surface of the furnace wall of the electric furnace Measuring the temperature measured at the detection end, performing an unsteady heat transfer inverse problem analysis, thereby deriving the relationship between the heat flux and the time on the inner circumferential surface of the furnace wall of the electric furnace; the heat flux integration mechanism is based on the foregoing The relationship between the heat flux and the time on the inner circumferential surface of the furnace wall of the electric furnace derived from the heat flux deriving mechanism, and deriving a time integral value corresponding to the heat flux during the period of one operation; and an output mechanism, It is to include information on the time integral value of the heat flux in the period corresponding to the one-time operation derived by the heat flux integration mechanism. Evaluation of the index outputs of the refractory material loss. The refractory material loss management device of the electric furnace according to claim 1, wherein the plurality of temperature detecting ends are disposed near a straight line passing through a central axis of the arc electrode, and when the scrap is completely melted and dropped, the furnace is located in a furnace of molten steel. At a position above the bath surface, the straight line is a straight line orthogonal to the central axis of the electric furnace. A refractory loss management system for an electric furnace, comprising: the refractory loss management device of the electric furnace according to claim 1 or 2; and the suppression measure actuator, wherein the output by the output mechanism comprises the one operation corresponding to the foregoing After the information on the time integral value of the heat flux during the period, measures for suppressing the loss of the refractory material are taken based on the result of the output. A method for managing refractory loss of an electric furnace is for managing loss of a refractory material constituting a furnace wall of an electric furnace, wherein the electric furnace is melted by an arc discharge generated at an arc electrode, and the refractory material loss management method of the electric furnace is characterized by The heat flux deriving step is configured according to a plurality of positions in which the inside of the furnace wall of the electric furnace and the outer peripheral surface of the furnace wall of the electric furnace are different in the thickness direction of the furnace wall of the electric furnace. The temperature measured at the temperature detecting end is subjected to an unsteady heat transfer inverse problem analysis, whereby the heat flux deriving mechanism derives a relationship between the heat flux and the time on the inner circumferential surface of the furnace wall of the electric furnace; The integration step is based on the relationship between the heat flux in the inner circumferential surface of the furnace wall and the time derived from the heat flux deriving step, and is derived from the heat flux integration mechanism for the period corresponding to one operation. The time integral value of the heat flux; the output step is to include the one derived by the heat flux integration step, corresponding to the previous one The information of the time integral value of the heat flux during the period is outputted by the output mechanism as an index for evaluating the loss of the refractory material; and the step of performing the suppression measure is performed by the output step of the output step corresponding to After the information on the time integral value of the heat flux during the first operation period, measures for suppressing the loss of the refractory material are taken based on the result of the output. A computer readable memory medium is a computer program for storing a refractory material useful for causing a computer to perform management of a wall of an electric furnace, the electric furnace melting the waste material by arc discharge generated at the arc electrode, and the computer The readable memory medium is characterized by a computer program for causing the computer to perform the following steps: The heat flux deriving step is based on the inside of the furnace wall of the electric furnace and the outer peripheral surface of the furnace wall of the electric furnace, in the electric furnace The temperature measured at the temperature detecting end of the plurality of positions at different positions in the thickness direction of the furnace wall is subjected to an analysis of the unsteady heat transfer inverse problem, thereby deriving the heat flux on the inner circumferential surface of the furnace wall of the electric furnace. The relationship with time; the heat flux integration step is based on the relationship between the heat flux and the time on the inner circumferential surface of the furnace wall derived from the heat flux deriving step, and is derived corresponding to one operation. The time integral value of the heat flux during the period; and the outputting step comprising the step of deriving by the heat flux integration step corresponding to the previous operation Information time integral value of the heat flux within the period, as an index for the evaluation of the loss of the refractories and outputs.