Method for estimating firing index and method for operating a Dwightroid sintering machine

Abstract

To estimate a firing index of sintered ore.SOLUTION: A firing index estimation method 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, L(t) is a value obtained by logarithmic conversion 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 firing indexes when producing sintered ore using a Dwight Lloyd sintering machine, and a method for operating a Dwight Lloyd sintering machine based on the firing indexes estimated by this method.

Background Art

[0002] In a sintering machine for producing sintered ore to be supplied to a blast furnace, fine iron ore, which is the main raw material of pig iron, is baked together with coke or the like serving as fuel, and its particle size, mechanical strength, and chemical composition are adjusted to produce sintered ore.

[0003] In a Dwight Lloyd sintering machine, the firing state, i.e., whether the fine iron ore on the pallet is appropriately melted and agglomerated by the combustion of coke, affects the quality of the sintered ore. Therefore, various indexes for grasping the firing state have been devised.

[0004] For example, in the machine length direction of a Dwight Lloyd sintering machine, the position where the exhaust gas temperature reaches the highest temperature is determined. Assuming that this highest temperature position is the end point position of the red-hot zone at the bottom of the sintering layer, i.e., the burn-through point (BTP), the operation is managed based on where this BTP is located in the machine length direction of the Dwight Lloyd sintering machine. With the operation goal of satisfying the quality of the sintered ore as described above and achieving high productivity, the operation is performed by controlling the moving speed of the pallet so that the BTP approaches the discharge end of the Dwight Lloyd sintering machine as much as possible.

[0005] In the method for producing sintered ore described in Patent Document 1, based on the exhaust gas temperatures measured at multiple locations in the machine length direction of a Dwight Lloyd sintering machine, the position where the exhaust gas temperature reaches the highest temperature (highest temperature position: BTP) is predicted, and the pallet speed is controlled so that the highest temperature position becomes the set position. Here, the highest temperature position (BTP) is calculated based on an exhaust gas temperature curve represented by a quadratic function.

[0006] The exhaust gas temperature curve (quadratic function) is determined by three coefficients A, B, and C. Here, coefficients A, B, and C are determined by inputting information from three or more points showing the relationship between the wind box and the wind box temperature measured in that wind box into the exhaust gas temperature curve (quadratic function). Then, the position where the maximum value is obtained in the exhaust gas temperature curve (quadratic function) containing the determined coefficients A, B, and C is defined as BTP. This method of calculating 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] The Iron and Steel Institute of Japan, Iron and Steel Handbook, 3rd Edition, Volume II: Ironmaking and Steelmaking, Maruzen Co., Ltd., 2nd printing, February 25, 1980, pp. 116-117. [Overview of the project] [Problems that the invention aims to solve]

[0009] As described in Patent Document 1 and Non-Patent Document 1, when the exhaust gas temperature curve is represented by a quadratic function, the BTP calculated from the exhaust gas temperature curve (quadratic function) may deviate from the actual BTP, which may prevent proper operation.

[0010] Therefore, the present invention aims to provide a method for estimating firing indices such as BTP more accurately than conventional methods. [Means for solving the problem]

[0011] The present invention relates to a method for estimating the firing index when producing sintered ore using a Dwight-Royd sintering machine, wherein the following formula (I) is used in estimating the firing index.

[0012]

number

[0013] In the above equation (I), Tn is the exhaust gas temperature [°C] detected in the windbox of the Dwight-Loyd sintering machine, and Tb is the base exhaust gas temperature [°C] which serves as the reference for the exhaust gas temperature after firing has started. t is the firing time, which is the time it takes for the sintering material to move from the ignition position by the ignition furnace via the pallet. s ], where L(t) is the logarithmic value of the firing time t. a, b, and k are coefficients [-], which are determined from the previously measured firing time and exhaust gas temperature.

[0014] The coefficients a, b, and k can be set to minimize the error between the exhaust gas temperature Tn obtained 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 by multiple wind boxes located between the ignition point and the BRP. The burning index can include at least one of the BTP (Burn Through Point) and the highest exhaust gas temperature.

[0015] In the operation method of a Dwight-Loyd type sintering machine, if BTPr, which is defined as the ratio of BTPt (defined as firing time) to the time from ignition to ore discharge, exceeds 100% among the firing indexes estimated by the firing index estimation method described above, the pallet movement speed can be reduced so that BTPr is 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. Based on the estimated firing index, the Dwight-Royd type sintering machine can be operated efficiently. [Brief explanation of the drawing]

[0017] [Figure 1] It is a schematic diagram showing the structure of a Dwight-Lloyd sintering machine. [Figure 2] It is a flowchart for explaining a method of determining the temperature curve of exhaust gas in the present embodiment. [Figure 3] It is a diagram showing the temperature curve of exhaust gas in the examples and comparative examples, and the measured values of the exhaust gas temperature according to the firing time. [Figure 4] It is a diagram showing the relationship between BTPr[%] and the yield of sintered ore in the examples and comparative examples. [Figure 5] It is a diagram showing the temperature curve of exhaust gas in the examples, comparative examples and reference examples, and the measured values of the exhaust gas temperature according to the firing time.

Mode for Carrying Out the Invention

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

[0019] (Dwight-Lloyd sintering machine) First, the structure of the DL sintering machine will be described with reference to FIG. 1. FIG. 1 is a schematic diagram showing the structure of the DL sintering machine. In the DL sintering machine, sintered ore with adjusted particle size, mechanical strength (mechanical strength), and chemical composition is produced by baking and solidifying fine iron ore as the main raw material and coke or the like as fuel.

[0020] In the DL-type sintering machine 1, multiple pallets 10 are connected in an endless manner and stretched across two gear wheels 21 and 22. As the gear wheels 21 and 22 rotate in the directions of arrows D1 and D2, the multiple pallets 10 move in the direction of arrow D3. At the top of the DL-type sintering machine 1, there is a raw material supply hopper 30 for supplying sintering raw materials to the pallets 10, and an ignition furnace 40 for igniting the sintering raw material layer on top of the pallets 10.

[0021] Below the multiple pallets 10 positioned above the DL-type sintering machine 1, multiple window boxes 50 are lined up along the direction of movement of the pallets 10. The window boxes 50 draw in air from the bottom of the pallets 10 on which the sintering material is loaded. Each window box 50 is connected to an intake pipe 60, and the air drawn in from the window boxes 50 is guided to the intake pipe 60.

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

[0023] As pallet 10 moves along the upper path of the DL-type sintering machine 1, the sintering of the sintering raw material layer loaded on pallet 10 is completed, and as pallet 10 moves along the gear wheel 22, the sintered ore is discharged from pallet 10. Here, the position where the sintered ore is discharged from pallet 10 is called the "discharge position". After the sintered ore has been discharged and the pallet 10 is empty, it moves along the lower path of the DL-type sintering machine 1 and returns to the position of the raw material supply hopper 30. In accordance with the movement of pallet 10 as described above, sintered ore can be continuously produced.

[0024] (Operation of DL-type sintering machine) The ignition furnace 40 ignites the sintering material layer within the pallet 10, and while the pallet 10 moves a specified distance, the exhaust gas temperature is maintained at around 100°C. After that, the exhaust gas temperature rises rapidly and reaches the maximum temperature. The position immediately after the rapid rise in exhaust gas temperature begins is called the BRP (Burn Rising Point). The position where the maximum temperature is reached is defined as BTPp.

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

[0026] One way to assign window box numbers is, for example, to assign "1" to the window box located at the position where the sintering raw material layer is ignited by the ignition furnace 40 after the sintering raw material has been supplied from the raw material hopper 30 to the pallet 10 (hereinafter referred to as the "ignition position"). Then, the window box numbers can be assigned in order from "2", "3", and so on, moving from the ignition position toward the discharge position. If a reference position is determined for each of the multiple window boxes 50, the distance from the ignition position to the reference position can be determined.

[0027] In the operation of the DL-type sintering machine 1, the movement speed of the pallet 10 is controlled so that the BTPp remains stably located close to the ore discharge position. By performing this operation, the quality of the sintered ore can be satisfied, and the productivity of the sintered ore [ton / h] can be improved.

[0028] Indicators used to evaluate the quality of sintered ore include, for example, the Tumbler Index (TI), the Reduction Disintegration Index (RDI), and the Reducibility Index (RI). When transporting or charging sintered ore into a blast furnace, it is necessary to suppress pulverization of the sintered ore, so a high Tumbler Index is preferable. To suppress the reduction pulverization of sintered ore charged into a blast furnace and to ensure permeability within the blast furnace, a low Reduction Disintegration Index is preferable. Since sintered ore is reduced in the blast furnace, a high Reducibility Index is preferable.

[0029] (Method for generating exhaust gas temperature curves) The method for generating the 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 represented in a coordinate system with firing time and exhaust gas temperature as the coordinate axes. The firing time is the elapsed time [s] from when the ignition furnace 40 ignites the sintering material layer in the pallet 10.

[0030] In step S101, the exhaust gas temperature is detected at multiple locations along the length of the DL-type sintering machine 1. Specifically, the exhaust gas temperature is detected using a temperature sensor at a predetermined window box 50 among a plurality of window boxes 50 arranged along the length of the machine.

[0031] As will be described later, in order to determine the exhaust gas temperature curve, the base exhaust gas temperature Tb and the exhaust gas temperature Tn after the 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 window box 50 from the position where firing starts (i.e., the ignition position) to the 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 exhaust gas temperature can be detected in a windbox 50 located after the ignition point. For example, the exhaust gas temperature can be detected in one windbox 50 located closest to the ignition point, and this temperature can be taken as the base exhaust gas temperature Tb. Alternatively, the exhaust gas temperature can be detected in each of several (any number) windboxes 50 located between the ignition point and the BRP, and the average of these temperatures can be taken 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 near the mine discharge location. However, the wind box 50 closest to the mine discharge location may draw in outside air in addition to the exhaust gas, and this draw in outside air may cause the exhaust gas temperature to be lower than the actual temperature. Therefore, when obtaining the exhaust gas temperature Tn, it is preferable to exclude the temperature of the exhaust gas detected in the wind box 50 closest to the mine discharge location.

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

[0035] In step S102, the coefficients a, b, and k shown in equation (1) below are determined. Equation (1) below is the equation that defines the exhaust gas temperature curve.

[0036]

number

[0037] In the above equation (1), Tn is the exhaust gas temperature [°C], Tb is the base exhaust gas temperature [°C], and t is the firing time [ sThe equation is ], where L(t) is the logarithmic value of the firing time t (hereinafter referred to as the "logarithmic value"), and a, b, and k are coefficients [-]. The firing time t is the time it takes for the sintering material loaded on the pallet 10 to move from the ignition position, and the logarithmic value L(t) is the natural logarithm (ln(t)) or common logarithm (log(t)) of the firing time t. 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 equation (1), the temperature of the exhaust gas corresponding to the logarithmic value L(t) (in other words, the firing time t) can be determined.

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

[0039] Therefore, the firing time t [min] at each location where the exhaust gas temperature Tn is detected can be determined from the distance L [m] from the ignition point to each detection point and the moving speed PS [m / min] of the pallet 10. In other words, the firing time t can be determined based on the following equation (2).

[0040]

number

[0041] Based on equation (2) above, the firing time t can be determined to obtain a correspondence between the exhaust gas temperature Tn detected in each of the predetermined number Nw or more wind boxes 50 and the firing time t corresponding to the distance L between each of the predetermined number Nw or more wind boxes 50 (in other words, the exhaust gas temperature Tn detected in each of the predetermined number Nw or more wind boxes 50).

[0042] As described above, by substituting the obtained base exhaust gas temperature Tb, each exhaust gas temperature Tn, and the firing time t corresponding to the exhaust gas temperature Tn into equation (1), the coefficients a, b, and k shown in equation (1) can be determined. Since equation (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, exhaust gas temperature Tn, and 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 arbitrarily set for each of the coefficients a, b, and k. Then, using the above equation (1) which includes the coefficients (initial values) a0, b0, and k0, the exhaust gas temperature (estimated value) Tn is obtained from the acquired base exhaust gas temperature Tb and firing time t, and the mean squared 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 squared error MSE; for example, the mean absolute error (MAE) can be used.

[0044] Next, the steepest descent direction is determined for the coefficients (initial values) a0, b0, and k0. In this steepest descent direction, the coefficients a, b, and k are updated by changing them by a predetermined amount from the initial values ​​a0, b0, and k0. Using the above equation (1) which includes 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. The mean squared error MSE is then calculated for 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 is repeated to identify the coefficients a, b, and k that minimize the mean squared error MSE.

[0045] In step S103, the exhaust gas temperature curve (equation (1) above) is determined using the coefficients a, b, and k identified in step S102. Equation (1) above, including the identified coefficients a, b, and k, is used as the exhaust gas temperature curve to determine the firing index of the sintered ore during the operation of the DL-type sintering machine 1. Using this exhaust gas temperature curve, the firing index (such as BTP) can be estimated with high accuracy during the operation of the DL-type sintering machine 1.

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

[0047] (Estimation of the calcination indicator of sintered ore) As described above, by identifying the exhaust gas temperature curve (equation (1) above), the firing index of the sintered ore can be estimated. Examples of firing indices include BTPt and the maximum exhaust gas temperature Tmax. Here, BTPt is the maximum temperature position BTPp expressed in time, indicating the time from ignition until the exhaust gas temperature reaches the maximum temperature. The estimation methods for BTPt and the maximum temperature Tmax are described below.

[0048] When estimating BTPt based on equation (1) above, if, for example, the natural logarithm of the firing time t (ln(t)) is used as the logarithmic transformed value L(t), then the following equation (3) can be used. The a shown in equation (3) below is the coefficient a shown in equation (1) above.

[0049]

number

[0050] When estimating the maximum exhaust gas temperature Tmax based on equation (1) above, the following equation (4) can be used. In equation (4) below, b and k are the coefficients b and k shown in equation (1) above, and Tb in equation (4) below is the base exhaust gas temperature shown in equation (1) above.

[0051]

number

[0052] As described above, by estimating BTPt, the operation of the DL-type sintering machine 1 can be controlled based on the estimated BTPt. Here, an indicator 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.

[0053] When controlling the operation of the DL-type sintering machine 1, the BTPr[%] (=100 × BTPt[s] / td[s]), which is defined as the ratio of BTPt[s] to the ore discharge time td[s], is calculated, and it is determined whether or not 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 movement speed PS of the pallet 10 can be controlled so that BTPr[%] is 100% or less. In this case, the movement speed PS should be reduced, and the amount of reduction in the movement speed PS can be determined as appropriate. If BTPr[%] still exceeds 100% after reducing the movement speed PS, the movement speed PS should be reduced further.

[0054] On the other hand, if BTPr[%] does not exceed 100%, the DL-type sintering machine 1 can continue operating at the current movement speed PS. Also, if BTPr[%] is too low compared to 100%, increasing the movement speed PS can bring BTr[%] closer to 100%.

[0055] In Non-Patent Document 1 mentioned above, BTPp is estimated based on an exhaust gas temperature curve (quadratic function) on the premise that BTPp does not exceed the exhaust position. Therefore, if BTPp exceeds the exhaust position, it becomes difficult to determine the accurate BTPp. According to this embodiment, BTPt can be estimated based on the exhaust gas temperature curve (equation (1) above) regardless of whether BTPp exceeds the exhaust position, and BTPp can be calculated by multiplying BTPt by the pallet movement speed PS. [Examples]

[0056] The following describes an example of this embodiment. The specifications of the DL-type sintering machine 1 used are shown in Table 1 below. [Table 1]

[0057] The window box 50 located at the ignition position was assigned the window box number "1," and as you move from the ignition position towards the ore discharge position, the window box numbers were assigned in the order of "2," "3," and so on. In this embodiment of the DL-type sintering machine 1, there are 27 window boxes 50, so the window box numbers range from "1" to "27."

[0058] To obtain the base exhaust gas temperature Tb, the exhaust gas temperature was measured in three windboxes 50 with windbox numbers "2", "6", and "9", and the average of these exhaust gas temperatures was calculated. In addition, the exhaust gas temperature Tn was measured in six windboxes 50 with windbox numbers "21" to "26". The windbox 50 closest to the mine discharge location (windbox number: "27") was not used to estimate the exhaust gas temperature Tn.

[0059] Table 2 below shows the measurement results of the exhaust gas temperature as described above, the distance L from the ignition point to the center of each window box 50, and the firing time t calculated from the distance L and the moving speed PS of the pallet 10.

[0060] [Table 2]

[0061] In equation (1) above, the base exhaust gas temperature Tb was set to 89.7 [°C], and the coefficients a, b, and k were determined using the steepest drop method described above. Here, the coefficient a was 7.62 [-], the coefficient b was 0.14 [-], and the coefficient k was 120 [-]. Based on these results, equation (1) above can be expressed as equation (5) below.

[0062]

number

[0063] On the other hand, as a comparative example, an exhaust gas temperature curve using a quadratic function was obtained. Since the quadratic function is expressed by the following equation (6), the coefficients c1, c2, and c3 shown in equation (6) were determined based on the measurement results shown in Table 2 above.

[0064]

number

[0065] In the above equation (6), Tn is the exhaust gas temperature [°C], and t is the firing time [ s ], 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 in window boxes numbered "23" to "26", the coefficient c1 was -0.0015, the coefficient c2 was 6.3, and the coefficient c3 was -6266. Therefore, the above equation (6) can be expressed as the following equation (7).

[0066]

number

[0067] Figure 3 shows the exhaust gas temperature curves (equations (5) and (7) above) for the examples and comparative examples. In Figure 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 for the comparative example was obtained from measurement results in window box 50, where the window box numbers are "23" to "26" (i.e., measurement results during the period when the exhaust gas temperature was rising), and therefore shows the temperature change during firing time t after BRP. The discharge time (firing time t to the discharge position) was 1976 [s].

[0068] Based on the exhaust gas temperature curve (equation (5) above) of the example, the calcination index (BTPt and the maximum exhaust gas temperature Tmax) was estimated. According to equation (3) above, BTPt was 2048 [s], and according to equation (4) above, the maximum exhaust gas temperature Tmax was 399 [°C].

[0069] Based on the comparative example exhaust gas temperature curve (equation (7) above), the calcination index (BTPt and the maximum exhaust gas temperature Tmax) was estimated. Here, BTPt was obtained from equation (8) below and was 2123 [s]. The maximum exhaust gas temperature was the maximum value of the quadratic temperature curve and was 424 [°C].

[0070]

number

[0071] To evaluate the firing index (BTPt) estimated from the examples and comparative examples, we focused on the relationship between BTPr[%] and the yield Ry[mass%] of the sintered ore. BTPr[%] is the ratio of BTPt[s] to the discharge time td[s] (=100 × BTPt / td), where the discharge time td is the time [s] it takes for the pallet 10 to move from the ignition position to the discharge position. The yield Ry is the value [mass%] obtained by dividing the mass Ms of the sintered ore on the sieve separated by a sieve with a mesh size of 5 mm by the mass Mt of the original sintered cake.

[0072] Figure 4 shows the relationship between BTPr[%] and yield Ry[mass%] for both the examples and comparative examples. In Figure 4, the vertical axis represents yield Ry[mass%] and the horizontal axis represents BTPr[%].

[0073] As can be seen from Figure 4, in the example, the yield Ry decreased as BTPr[%] increased above 100[%], or in other words, the yield Ry increased as BTPr[%] approached 100[%]. Generally, a negative correlation is observed between BTPr[%] and yield Ry, so the example demonstrates that BTPr can be estimated with good accuracy. On the other hand, as can be seen from Figure 4, no correlation was observed between BTPr[%] and yield Ry in the comparative example. The correlation coefficient R for the example was -0.81, and the correlation coefficient R for the comparative example was -0.43.

[0074] As described above, this embodiment makes it easier to understand the change in yield Ry when BTPr[%] is changed, compared to the comparative example, thus making it easier to control the operation of the DL-type sintering machine 1 based on BTPt.

[0075] Figure 5 shows the exhaust gas temperature distribution in other experiments. In Figure 5, the vertical axis represents the exhaust gas temperature [°C], and the horizontal axis represents the firing time t [s]. Figure 5 shows the distribution of measured exhaust gas temperatures, the exhaust gas temperature curve for the example (equation (1) above), the exhaust gas temperature curve for the comparative example (equation (6) above), and, as a reference example, the exhaust gas temperature curve when the logarithmic transformed value L(t) shown in equation (1) above is replaced with the firing time t.

[0076] For the exhaust gas temperature curve of the example (equation (1) above), coefficients a, b, and k were determined based on the exhaust gas temperature curve generation method described above, and the coefficient a was 7.09[-], the coefficient b was 0.088[-], and the coefficient k was 126[-]. 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 of the example (equation (1) above). In the reference example, as described above, the logarithmic transformed value L(t) shown in equation (1) above was replaced with the firing time t to estimate the exhaust gas temperature Tn.

[0077] For the comparative example exhaust gas temperature curve (equation (6) above), the coefficients c1, c2, and c3 were determined to be -0.0174[-], c2 to 42.3[-], and c3 to -25108[-]. Then, the firing time t was measured, and the exhaust gas temperature Tn was estimated based on the comparative example exhaust gas temperature curve (equation (6) above).

[0078] As can be seen from Figure 5, the exhaust gas temperature curve of the example (equation (1) above) follows the distribution of measured exhaust gas temperatures, indicating that the estimation accuracy of the example is ensured. In the case of the exhaust gas temperature curve of the comparative example (equation (6) above), BTPt deviates from the measured value, and the exhaust gas temperature after BTPt also deviates from the measured value. When the logarithmic transformed value L(t) shown in equation (1) above is replaced with the firing time t, it was not possible to estimate the exhaust gas temperature after BRPt in the exhaust gas temperature curve. [Explanation of Symbols]

[0079] 1: DL type sintering machine, 10: pallet, 21, 22: gear wheel, 30: raw material supply hopper, 40: Ignition furnace, 50: Wind box, 60: Intake pipe

Claims

1. A method for estimating the firing index when producing sintered ore using a Dwight-Royd sintering machine, A method for estimating a firing index, characterized by using the following formula (I) in estimating the firing index. [Math 1] In the above formula (I), Tn is the exhaust gas temperature [°C] detected in the windbox of the Dwight-Loyd sintering machine, Tb is the base exhaust gas temperature [°C] which serves as the reference for the exhaust gas temperature after firing has started, t is the firing time [s] which is the time it takes for the sintering material to move from the ignition position by the ignition furnace via the pallet, L(t) is the logarithmically transformed value of the firing time t, and a, b, and k are each coefficients [-] which are determined from the firing time and exhaust gas temperature measured in advance.

2. The firing index estimation method according to claim 1, characterized in that the coefficients a, b and k are set such that the error between the exhaust gas temperature Tn obtained from the above formula (I) and the measured exhaust gas temperature is minimized.

3. The method for estimating a burning index according to claim 1, characterized in that the base exhaust gas temperature Tb is the average value of the exhaust gas temperatures detected by a plurality of window boxes located between the ignition position and the BRP (Burn Rising Point).

4. The method for estimating a firing index according to any one of claims 1 to 3, characterized in that the firing index includes at least one of the Burn Through Point (BTP) and the highest exhaust gas temperature.

5. A method for operating a Dwightroid sintering machine, characterized in that, among the firing indexes estimated by the firing index estimation method described in claim 4, if BTPr, defined as the ratio of BTPt, defined as firing time, to the ore discharge time, exceeds 100%, the pallet movement speed is reduced so that BTPr becomes 100% or less.

Images