Firing index predicting method and method for operating dwight-lloyd type sintering machine

Abstract

To accurately estimate a firing index of sintered ore.SOLUTION: There is provided a firing index estimation method which estimates a firing index when producing sintered ore using a Dwight-Lloyd type sintering machine, and the following equation (I) is used in estimating the firing index. In the above formula (I), Tn is an exhaust gas temperature [°C] detected in a wind box of the Dwight-Lloyd type sintering machine, Tb is a base exhaust gas temperature [°C] that is a reference for the exhaust gas temperature after the firing is started, t is a firing time [s], which is the time when the sintered raw material moves from the ignition position by the ignition furnace by the pallet, ln(t) is a value obtained by natural logarithmic transformation of the firing time t, and each of a, b, and k is a coefficient and is determined from the firing time and exhaust gas temperature measured in advance.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for estimating a firing index when producing sintered ore using a Dwight Lloyd sinter machine, and a method for operating a Dwight Lloyd sinter machine based on the firing index estimated by this method. [Background technology]

[0002] In sintering machines that produce sintered ore to be supplied to blast furnaces, finely divided iron ore, the main raw material for pig iron, is baked together with coke and other fuels to produce sintered ore, adjusting its particle size, mechanical strength, and chemical composition.

[0003] In a Dwight Lloyd sintering machine, the firing condition, i.e., whether or not the fine iron ore on the pallet is properly melted and agglomerated by the combustion of coke, affects the quality of the sintered ore. Therefore, various indicators have been devised to grasp the firing condition.

[0004] For example, the position in the longitudinal direction of the Dwight Lloyd sinter machine where the exhaust gas temperature is highest is determined, and the highest temperature position is considered to be the end point of the red hot zone at the bottom of the sintering bed, i.e., the burn-through point (BTP), and operation is controlled based on where this BTP is located in the longitudinal direction of the Dwight Lloyd sinter machine.With the operational goals of satisfying the above-mentioned sinter ore quality and achieving high productivity, operation is performed by controlling the pallet movement speed so that the BTP is as close as possible to the end of the ore discharge section of the Dwight Lloyd sinter machine.

[0005] In the sinter ore manufacturing method described in Patent Document 1, the position where the exhaust gas temperature becomes the highest (highest temperature position: BTP) is predicted based on the exhaust gas temperature measured at multiple points in the machine length direction of the Dwight Lloyd sintering machine, and the pallet speed is controlled so that the highest temperature position becomes the set position. Here, the highest temperature position (BTP) is expressed by a quadratic function (T i =A i P i 2 +B iP i +C i ) is calculated based on the exhaust gas temperature curve.

[0006] The exhaust gas temperature curve (quadratic function) is specified by three coefficients A, B, and C. Here, by inputting information on three or more points that indicate the relationship between the wind box and the wind box temperature measured in the wind box into the exhaust gas temperature curve (quadratic function), each of the coefficients A, B, and C is specified. Then, the position where the exhaust gas temperature curve (quadratic function) that includes the specified coefficients A, B, and C has a maximum value is defined as the BTP. This method of calculating the BTP based on the exhaust gas temperature curve (quadratic function) is also described in Non-Patent Document 1. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 4826129 [Non-patent literature]

[0008] [Non-Patent Document 1] Iron and Steel Institute of Japan, Iron and Steel Handbook, 3rd Edition, Vol. II, Iron and Steel Making, Maruzen Co., Ltd., 2nd printing published February 25, 1980, pp. 116-117 Summary of the Invention [Problem to be solved by the invention]

[0009] When the exhaust gas temperature curve is expressed as a quadratic function as in Patent Document 1 and Non-Patent Document 1, the BTP calculated from the exhaust gas temperature curve (quadratic function) may deviate from the actual BTP, which may result in inappropriate operation.

[0010] Therefore, an object of the present invention is to provide a method for estimating baking indices such as BTP more accurately than conventional methods. [Means for solving the problem]

[0011] The present invention is a method for estimating a firing index when sintered ore is produced using a Dwight Lloyd sintering machine, and uses the following formula (I) in estimating the firing index.

[0012]

number

[0013] In the above formula (I), Tn is the exhaust gas temperature [°C] detected by the wind box of the Dwight Lloyd sintering machine, and Tb is the base exhaust gas temperature [°C] that serves as the reference for the exhaust gas temperature after firing has begun. t is the firing time [s], which is the time it takes for the sintering raw materials to be moved by the pallet from the ignition position in the ignition furnace, and ln(t) is the value obtained by natural logarithmically transforming the firing time t. a, b, and k are coefficients that are determined from the firing time and exhaust gas temperature measured in advance.

[0014] The coefficients a, b, and k can be set so as to minimize the error between the exhaust gas temperature Tn calculated from the above formula (I) and the measured exhaust gas temperature. The base exhaust gas temperature Tb can be the average value of the exhaust gas temperatures detected in multiple wind boxes located between the ignition position and the BTP. The burning index can include the BTP (Burn Through Point).

[0015] In the operating method of a Dwight Lloyd sintering machine, when BTPr, which is defined as the ratio of BTPt, defined as the firing time, to the time from ignition to discharge of ore, among the firing indices estimated by the above-mentioned firing index estimation method, exceeds 100%, the pallet moving speed can be reduced so that BTPr becomes 100% or less. [Effects of the Invention]

[0016] According to the present invention, the firing index of sintered ore can be estimated with high accuracy, and the Dwight Lloyd sintering machine can be operated efficiently based on the estimated firing index. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic diagram showing the structure of a DL-type sintering machine. [Figure 2] 3 is a flowchart illustrating a method for determining a temperature curve of exhaust gas in the present embodiment. [Figure 3] FIG. 2 is a diagram showing exhaust gas temperature curves and measured values ​​of exhaust gas temperature according to firing time in Examples and Comparative Examples. [Figure 4] FIG. 2 is a diagram showing the relationship between BTPr [%] and the yield of sintered ore in Examples and Comparative Examples. [Figure 5] FIG. 2 is a diagram showing exhaust gas temperature curves and measured values ​​of exhaust gas temperature according to firing time in Examples and Comparative Examples. DETAILED DESCRIPTION OF THE INVENTION

[0018] This embodiment is a method for estimating a firing index when producing sintered ore using a Dwight Lloyd sintering machine (hereinafter referred to as a "DL sintering machine"). Specifically, a temperature curve of the exhaust gas, which will be described later, is generated, and the firing index is estimated based on this temperature curve. Examples of firing indexes include the BTP (Burn Through Point) and the maximum temperature of the exhaust gas. This embodiment will be specifically described below.

[0019] (DL type sintering machine) First, the structure of a DL-type sintering machine will be explained using Figure 1. Figure 1 is a schematic diagram showing the structure of a DL-type sintering machine. In a DL-type sintering machine, fine iron ore, which is the main raw material, and coke, etc., which is used as fuel, are sintered to produce sintered ore with adjusted particle size, mechanical strength, and chemical composition.

[0020] In the DL-type sinter machine 1, a plurality of pallets 10 are connected endlessly and hung across two gear wheels 21, 22, and the gear wheels 21, 22 rotate in the directions of arrows D1, D2, respectively, causing the plurality of pallets 10 to move in the direction of arrow D3. At the top of the DL-type sinter machine 1, there are provided a raw material feeding hopper 30 that feeds sintering raw material to the pallets 10, and an ignition furnace 40 that ignites the upper part of the sintering raw material layer loaded on the pallets 10.

[0021] Below the multiple pallets 10 arranged on the upper side of the DL-type sintering machine 1, multiple wind boxes 50 are lined up along the movement direction of the pallets 10, and the wind boxes 50 take in air from below the pallets 10 on which the sintering raw materials are loaded. Each wind box 50 is connected to an intake pipe 60, and the air taken in from the wind box 50 is led to the intake pipe 60.

[0022] After the upper part of the sintering raw material layer is ignited by the ignition furnace 40, the pallet 10 is transported in the longitudinal direction of the DL-type sintering machine 1 (from left to right in Figure 1), and the sintering reaction progresses from the top to the bottom of the sintering raw material layer due to the intake air from the multiple wind boxes 50.

[0023] While the pallet 10 moves along the upper path of the DL-type sintering machine 1, firing of the sinter raw material layer loaded on the pallet 10 is completed, and as the pallet 10 moves along the gear wheel 22, the sintered ore is discharged from the pallet 10. Here, the position where the sintered ore is discharged from the pallet 10 is referred to as the "ore discharge position." The pallet 10, which has been emptied of the sintered ore after being discharged, moves along the lower path of the DL-type sintering machine 1 and returns to the position of the raw material supply hopper 30. Sintered ore can be continuously produced in accordance with the movement of the pallet 10 described above.

[0024] (DL-type sintering machine operation) The sintering raw material layer in the pallet 10 is ignited by the ignition furnace 40, and while the pallet 10 moves a certain distance, the temperature of the exhaust gas is maintained at a temperature of around 100°C, after which the temperature of the exhaust gas rises rapidly and reaches its maximum temperature. Here, the position immediately after the temperature of the exhaust gas starts to rise rapidly is called BRP (Burn Rising Point). Also, the position where the maximum temperature is reached is defined as BTPp.

[0025] In the operation of the DL-type sintering machine 1, operation management is performed based on the BTPp on the movement path of the pallet 10. The BTPp is the position when the temperature of the exhaust gas generated during the sintering reaction reaches the maximum temperature, and this position is identified, for example, by numbers assigned to the multiple wind boxes 50 (hereinafter referred to as "wind box numbers") or the distance to each wind box 50 on the movement path of the pallet 10.

[0026] As a method of allocating wind box numbers, for example, "1" can be allocated to the wind box located at a position where the sinter raw material is fed from the raw material feeding hopper 30 to the pallet 10 and then the sinter raw material layer is ignited by the ignition furnace 40 (hereinafter referred to as "ignition position"). Then, wind box numbers "2", "3" and so on can be allocated in order from the ignition position toward the discharge position. Here, if a reference position is determined for each of the multiple wind boxes 50, the distance from the ignition position to each reference position can be specified.

[0027] In the operation of the DL-type sinter machine 1, the moving speed of the pallet 10 is controlled so that the BTPp is stably located near the ore discharge position. By performing such an operation, it is possible to satisfy the quality of the sintered ore and improve the productivity of sintered ore [ton / h].

[0028] Examples of indices for evaluating the quality of sintered ore include the tumbler index (TI), reduction disintegration index (RDI), and reducibility index (RI). When transporting sintered ore or charging it into a blast furnace, it is necessary to suppress the pulverization of the sintered ore, so it is preferable that the cold strength index of the sintered ore is large. In order to suppress the reduction disintegration of the sintered ore charged into the blast furnace and to ensure gas permeability within the blast furnace, it is preferable that the reduction disintegration index of the sintered ore is small. Since the sintered ore is reduced in the blast furnace, it is preferable that the reducibility index of the sintered ore is large.

[0029] (Method for generating exhaust gas temperature curves) A method for generating an exhaust gas temperature curve used to estimate the firing index will be explained using the flowchart shown in Figure 2. The exhaust gas temperature curve is a curve that shows the behavior of the exhaust gas temperature with respect to the firing time, and is expressed in a coordinate system with the firing time and the exhaust gas temperature as the coordinate axes. The firing time is the elapsed time [s] from the ignition furnace 40 igniting the sintering raw material layer in the pallet 10.

[0030] In step S101, the temperature of the exhaust gas is detected at a plurality of locations in the machine longitudinal direction of the DL-type sintering machine 1. Specifically, the temperature of the exhaust gas is detected using a temperature sensor in a predetermined wind box 50 among a plurality of wind boxes 50 lined up in the machine longitudinal direction.

[0031] As will be described later, in order to obtain the temperature curve of the exhaust gas, the base exhaust gas temperature Tb and the temperature Tn of the exhaust gas after BRP are required. The base exhaust gas temperature Tb is the temperature of the exhaust gas discharged from the sintering raw material layer in the pallet 10 to the wind box 50 between the position where firing starts (i.e., the ignition position) and BRP, and is the reference temperature when understanding the temperature behavior of the exhaust gas.

[0032] To obtain the base exhaust gas temperature Tb, the temperature of the exhaust gas may be detected in a wind box 50 located downstream of the ignition position. For example, the temperature of the exhaust gas may be detected in one wind box 50 located closest to the ignition position, and this temperature may be used as the base exhaust gas temperature Tb. Alternatively, the temperature of the exhaust gas may be detected in each of a plurality (any number) of wind boxes 50 located between the ignition position and the BRP, and the average value of these temperatures may be used as the base exhaust gas temperature Tb.

[0033] To obtain the exhaust gas temperature Tn, the temperature of the exhaust gas can be detected in a wind box 50 located close to the ore discharge position. However, the wind box 50 located closest to the ore discharge position may draw in outside air in addition to the exhaust gas, and the intake of outside air may cause the temperature of the exhaust gas to be lower than the actual temperature. For this reason, when obtaining the exhaust gas temperature Tn, it is preferable to exclude the temperature of the exhaust gas detected in the wind box 50 located closest to the ore discharge position.

[0034] For example, the temperature of the exhaust gas can be detected in each of a predetermined number Nw or more of wind boxes 50, excluding the wind box 50 closest to the ore discharge position, in order from the side closest to the ore discharge position. Here, the predetermined number Nw is preferably three or more. The temperature of the exhaust gas detected in each wind box 50 is used as the exhaust gas temperature Tn.

[0035] In step S102, coefficients a, b, and k shown in the following formula (1) are calculated: The following formula (1) defines the temperature curve of the exhaust gas.

[0036]

number

[0037] In the above formula (1), Tn is the exhaust gas temperature [°C], Tb is the base exhaust gas temperature [°C], t is the firing time [s], ln(t) is the natural logarithmic transformation value of the firing time t (hereinafter referred to as the "logarithmic transformation value"), and a, b, and k are coefficients. The firing time t is the time it takes for the sintering raw materials loaded on the pallet 10 to move from the ignition position. Since the pallet 10 moves at a predetermined speed, the firing time t depends on the distance from the ignition position along the movement path of the pallet 10. According to the above formula (1), the temperature of the exhaust gas corresponding to the firing time t can be obtained.

[0038] The exhaust gas temperature Tn and the base exhaust gas temperature Tb can be obtained in the processing of step S101 described above. As described above, the exhaust gas temperature Tn is detected in each of the predetermined number Nw or more of wind boxes 50, and since these detection positions are predetermined, it is possible to identify the distance L [m] from the ignition position to each detection position on the movement path of the pallet 10. In addition, the movement speed PS [m / s] of the pallet 10 is set to a constant speed.

[0039] Therefore, the baking time t [s] at the position where each exhaust gas temperature Tn is detected can be calculated from the distance L [m] from the ignition position to each detection position and the moving speed PS [m / s] of the pallet 10. That is, the baking time t can be calculated based on the following formula (2).

[0040]

number

[0041] By calculating the baking time t based on the above formula (2), it is possible to obtain a correspondence relationship between the exhaust gas temperature Tn detected in each of the predetermined number Nw or more of wind boxes 50 and the baking time t corresponding to each distance L between the predetermined number Nw or more of wind boxes 50 (in other words, the exhaust gas temperature Tn detected in each of the predetermined number Nw or more of wind boxes 50).

[0042] The coefficients a, b, and k shown in the above formula (1) can be determined by substituting the base exhaust gas temperature Tb, each exhaust gas temperature Tn, and the firing time t corresponding to the exhaust gas temperature Tn, which are obtained as described above, into the above formula (1).Since the above formula (1) contains three coefficients a, b, and k, each of the coefficients a, b, and k can be identified by preparing at least three parameter sets consisting of the base exhaust gas temperature Tb, the exhaust gas temperature Tn, and the firing time t.

[0043] The known steepest descent method can be used to determine the coefficients a, b, and k. In the steepest descent method, initial values ​​a0, b0, and k0 are first arbitrarily set for the coefficients a, b, and k, respectively. Then, using the above formula (1) including the coefficients (initial values) a0, b0, and k0, the exhaust gas temperature (estimated value) Tn is calculated from the acquired base exhaust gas temperature Tb and the firing time t, and the mean square error MSE is calculated between this exhaust gas temperature (estimated value) Tn and the acquired exhaust gas temperature (measured value) Tn. Note that the error between the exhaust gas temperature (estimated value) Tn and the exhaust gas temperature (measured value) Tn is not limited to the mean square error MSE; for example, the mean absolute error (MAE) can be used.

[0044] Next, the steepest descent direction for the coefficients (initial values) a0, b0, and k0 is determined, and the coefficients a, b, and k are updated by changing them from the initial values ​​a0, b0, and k0 by a predetermined amount in this steepest descent direction. Using the above formula (1) including the updated coefficients a, b, and k, the exhaust gas temperature (estimated value) Tn is determined from the acquired base exhaust gas temperature Tb and firing time t, and the mean square error MSE is calculated between this exhaust gas temperature (estimated value) Tn and the acquired exhaust gas temperature (measured value) Tn. The process of determining the steepest descent direction and updating the coefficients a, b, and k described above is repeated to identify the coefficients a, b, and k when the mean square error MSE is minimized.

[0045] In step S103, the exhaust gas temperature curve (the above formula (1)) is determined using the coefficients a, b, and k identified in the processing of step S102. The above formula (1) including the identified coefficients a, b, and k is used as the exhaust gas temperature curve for determining the firing index of the sintered ore during operation of the DL-type sintering machine 1. By using this exhaust gas temperature curve, the firing index (BTP, etc.) can be accurately estimated during operation of the DL-type sintering machine 1.

[0046] Here, the exhaust gas temperature curve (the above formula (1)) can be determined for each type (composition) of sintering raw material, and when sintered ore is produced using the same type of sintering raw material, the sintering index can be estimated using the exhaust gas temperature curve (the above formula (1)) corresponding to this sintering raw material.

[0047] (Estimation of sintering index) As described above, by determining the temperature curve of the exhaust gas (the above formula (1)), the firing index of the sintered ore can be estimated. An example of the firing index is BTPt. Here, BTPt is the maximum temperature position BTPp expressed in time, and indicates the time from ignition until the exhaust gas temperature reaches the maximum temperature. A method for estimating BTPt will be described below.

[0048] When estimating BTPt based on the above formula (1), the following formula (3) can be used: a and b shown in the following formula (3) are the coefficients a and b shown in the above formula (1).

[0049]

number

[0050] If BTPt is estimated as described above, it is possible to control the operation of the DL-type sintering machine 1 based on the estimated BTPt. Here, an index for controlling the operation of the DL-type sintering machine 1 is, for example, the moving speed PS of the pallet 10, and the moving speed PS can be increased or decreased based on the estimated BTPt.

[0051] When controlling the operation of the DL-type sintering machine 1, BTPr [%] (= 100 × BTPt [s] / td [s]), defined as the ratio of BTPt [s] to the ore discharge time td [s], is calculated, and it is determined whether BTPr [%] exceeds 100%. Here, the ore discharge time td [s] is the time it takes for the pallet 10 to move from the ignition position to the ore discharge position. If BTPr [%] exceeds 100%, the moving speed PS of the pallet 10 can be controlled so that BTPr [%] is 100% or less. In this case, it is sufficient to reduce the moving speed PS, and the amount of reduction of the moving speed PS can be determined appropriately. If BTPr [%] still exceeds 100% after reducing the moving speed PS, the moving speed PS can be further reduced.

[0052] On the other hand, if BTPr [%] does not exceed 100%, the operation of the DL-type sintering machine 1 can be continued at the current moving speed PS. Also, if BTPr [%] is too low compared to 100%, the moving speed PS can be increased to bring BTPr [%] closer to 100%.

[0053] In the above-mentioned Non-Patent Document 1, BTPp is estimated based on the exhaust gas temperature curve (quadratic function) on the assumption that BTPp does not exceed the discharge position, so if BTPp exceeds the discharge position, it becomes difficult to accurately determine BTPp. According to this embodiment, BTPt can be estimated based on the exhaust gas temperature curve (the above formula (1)) regardless of whether BTPp exceeds the discharge position, and BTPp can be calculated by multiplying BTPt by the pallet movement speed PS. [Example]

[0054] Examples of this embodiment will be described below. The specifications of the DL-type sintering machine 1 used are shown in Table 1 below. [Table 1]

[0055] The wind box 50 at the ignition position is assigned the wind box number "1", and as the wind box moves from the ignition position toward the ore discharge position, the wind box numbers are assigned in the order of "2", "3", etc. In the DL-type sintering machine 1 of this embodiment, 27 wind boxes 50 are provided, and therefore the wind box numbers range from "1" to "27".

[0056] To obtain the base exhaust gas temperature Tb, the exhaust gas temperatures were measured in three wind boxes 50 with wind box numbers "2," "6," and "9," and the average of these exhaust gas temperatures was calculated. Furthermore, the exhaust gas temperatures were measured in six wind boxes 50 with wind box numbers "21" to "26" to obtain the exhaust gas temperature Tn. The wind box 50 closest to the ore discharge position (wind box number: "27") was not used to estimate the exhaust gas temperature Tn.

[0057] Table 2 below shows the measurement results of the exhaust gas temperature described above, the distance L from the ignition position to the center of each wind box 50 (the reference position described above), and the firing time t calculated from the distance L and the movement speed PS of the pallet 10.

[0058] [Table 2]

[0059] In the above formula (1), the base exhaust gas temperature Tb was set to 89.7°C, and the coefficients a, b, and k were determined using the steepest descent method described above. Here, the coefficient a was 7.64, the coefficient b was 0.15, and the coefficient k was 12807. Based on this result, the above formula (1) can be expressed as the following formula (4).

[0060]

number

[0061] On the other hand, as a comparative example, a temperature curve of exhaust gas was obtained using a quadratic function. The quadratic function is expressed by the following formula (5), and the coefficients c1, c2, and c3 shown in the following formula (5) were determined based on the measurement results shown in Table 2 above.

[0062]

number

[0063] In the above formula (5), Tn is the exhaust gas temperature [°C], t is the firing time [s], and c1, c2, and c3 are coefficients. When the coefficients c1, c2, and c3 were determined using the exhaust gas temperature Tn and firing time t for wind box numbers "23" to "26," the coefficient c1 was -0.0015, the coefficient c2 was 6.3, and the coefficient c3 was -6266. Therefore, the above formula (5) can be expressed as the following formula (6).

[0064]

number

[0065] FIG. 3 shows the exhaust gas temperature curves (the above formulas (4) and (6)) in the example and the comparative example. In FIG. 3, the vertical axis represents the exhaust gas temperature [°C], and the horizontal axis represents the firing time t [s]. The exhaust gas temperature curve in the comparative example was obtained from the measurement results in wind boxes 50 with wind box numbers "23" to "26" (i.e., measurement results during the period when the exhaust gas temperature was rising), and therefore shows the temperature change during the firing time t after BRP. The ore discharge time (firing time t up to the discharge position) was 1976 [s].

[0066] The firing index (BTPt) was estimated based on the temperature curve of the exhaust gas (the above formula (4)) in the example. According to the above formula (3), the BTPt was 2037 [s].

[0067] The firing index (BTPt) was estimated based on the temperature curve of the exhaust gas (the above formula (6)) as a comparative example. Here, BTPt was calculated from the following formula (7) and was found to be 2123 [s].

[0068]

number

[0069] To evaluate the sintering index (BTPt) estimated by the examples and comparative examples, we focused on the relationship between BTPr [%] and the sinter yield Ry [mass %]. BTPr [%] is the ratio of BTPt [s] to the ore discharge time td [s] (= 100 × BTPt / td), where td is the time [s] it takes for the pallet 10 to move from the ignition position to the ore discharge position. The yield Ry is the mass (mass %) of the sintered ore sieved through a 5 mm sieve divided by the mass (Mt) of the original sintered cake.

[0070] 4 shows the relationship between BTPr [%] and yield Ry [mass %] for each of the example and comparative example, where the vertical axis represents yield Ry [mass %] and the horizontal axis represents BTPr [%].

[0071] As can be seen from Figure 4, for the Example, the higher the BTPr [%] above 100 [%], the lower the yield Ry. In other words, the closer the BTPr [%] is to 100 [%], the higher the yield Ry. Generally, a negative correlation is observed between BTPr [%] and yield Ry, so the Example proved that BTPr could be estimated with high accuracy. On the other hand, as can be seen from Figure 4, for the Comparative Example, no correlation was observed between BTPr [%] and yield Ry. The correlation coefficient R for the Example was -0.81, and the correlation coefficient R for the Comparative Example was -0.43.

[0072] As described above, according to this embodiment, it is easier to grasp the change in yield Ry when BTPr [%] is changed compared to the comparative example, and therefore it is easier to control the operation of the DL-type sintering machine 1 based on BTPt.

[0073] Figure 5 shows the temperature distribution of exhaust gas in another experiment. In Figure 5, the vertical axis represents the temperature of the exhaust gas [°C], and the horizontal axis represents the firing time t [s]. Figure 5 shows the distribution of the exhaust gas temperature as a measured value, the temperature curve of the exhaust gas (formula (1) above) of the example, and the temperature curve of the exhaust gas (formula (5) above) of the comparative example.

[0074] For the exhaust gas temperature curve (the above formula (1)) of the example, the coefficients a, b, and k were calculated based on the above-mentioned method for generating an exhaust gas temperature curve, and the coefficient a was 7.1, the coefficient b was 0.1, and the coefficient k was 164103. Then, the base exhaust gas temperature Tb and the firing time t were measured, and the exhaust gas temperature Tn was estimated based on the exhaust gas temperature curve (the above formula (1)) of the example.

[0075] When the coefficients c1, c2, and c3 were calculated for the exhaust gas temperature curve (the above formula (5)) as a comparative example, the coefficient c1 was −0.0174, the coefficient c2 was 42.3, and the coefficient c3 was −25108. Then, the firing time t was measured, and the exhaust gas temperature Tn was estimated based on the exhaust gas temperature curve (the above formula (5)) as a comparative example.

[0076] As can be seen from Figure 5, the exhaust gas temperature curve (formula (1) above) of the example follows the distribution of the exhaust gas temperature as the measured value, and it was found that the estimation accuracy of the example was ensured. For the exhaust gas temperature curve (formula (5) above) of the comparative example, the BTPt deviated from the measured value, and the exhaust gas temperature after BTPt also deviated from the measured value. [Explanation of symbols]

[0077] 1: DL type sinter machine, 10: pallet, 21, 22: gear wheels, 30: raw material feeding hopper, 40: Ignition furnace, 50: Wind box, 60: Intake pipe

Claims

1. A method for estimating a sintering index when producing sintered ore using a Dwight Lloyd sintering machine, comprising: A method for estimating a baking index, characterized in that the baking index is estimated using the following formula (I): [Equation 1] In the above formula (I), Tn is the exhaust gas temperature [°C] detected by the wind box of the Dwight Lloyd sintering machine, Tb is the base exhaust gas temperature [°C] serving as a reference for the exhaust gas temperature after the start of firing, t is the firing time [s] which is the time it takes for the sintering raw materials to be moved by the pallet from the ignition position by the ignition furnace, ln(t) is a value obtained by natural logarithmically transforming the firing time t, and a, b, and k are coefficients which are determined from the firing time and the exhaust gas temperature which are measured in advance.

2. The method for estimating a firing index according to claim 1, characterized in that the coefficients a, b, and k are set so as to minimize the error between the exhaust gas temperature Tn calculated from the above formula (I) and the measured exhaust gas temperature.

3. 2. The method for estimating a firing index according to claim 1, wherein the base exhaust gas temperature Tb is an average value of exhaust gas temperatures detected in a plurality of wind boxes located between the ignition position and a BRP (Burn Rising Point).

4. 4. The method for estimating a baking index according to claim 1, wherein the baking index includes a BTP (Burn Through Point).

5. 5. A method for operating a Dwight Lloyd sintering machine, characterized in that, when BTPr, defined as the ratio of BTPt, defined in terms of firing time, to the ore discharge time, among the firing indices estimated by the firing index estimation method according to claim 4, exceeds 100%, the pallet moving speed is reduced so that BTPr becomes 100% or less.

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