Blast furnace operational status evaluation method and operation method

Abstract

To provide a method for evaluating an operation state of a blast furnace capable of evaluating excess and deficiency of a supply heat quantity in a radial direction of the blast furnace.SOLUTION: In a method for evaluating an operation state of a blast furnace, a radial distribution of an ore amount and a coke amount is calculated based on a piling shape of ore and coke, a radial distribution of a gas flow velocity is calculated based on the radial distribution of the ore amount and the coke amount, a radial distribution of a passing speed of oxygen moles is calculated based on the radial distribution of the gas flow velocity, a radial distribution of a passing speed of iron moles is calculated based on the piling shape of the ore and the coke and a production rate of molten iron, a radial distribution of a molar ratio of oxygen to iron is calculated based on the radial distributions of the passing speeds of the oxygen moles and the iron moles, a radial distribution of a ratio of the number of moles of oxygen to the number of moles of carbon contained in CO and CO2 in gas components is calculated based on a distribution state of the gas components, a radial distribution of a direct reduction rate during operation is calculated by applying the radial distribution of the molar ratio of oxygen to iron and the radial distribution of the ratio of the number of moles of oxygen to the number of moles of carbon to a Rist model, and excess and deficiency of a supplied heat quantity in a radial direction is evaluated using the calculated radial distribution of the direct reduction rate.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for evaluating the operational state of a blast furnace and a method for operating a blast furnace. [Background technology]

[0002] Stable operation of a blast furnace requires maintaining the molten pig iron temperature within a predetermined range. Specifically, when the molten pig iron temperature is low, the viscosity of the molten pig iron and the slag generated with the molten pig iron increases, making it difficult to discharge the molten pig iron and slag from the taphole. On the other hand, when the molten pig iron temperature is high, the silicon concentration in the molten pig iron increases, increasing the viscosity of the molten pig iron. As a result, the molten pig iron clings to the tuyere, increasing the risk of tuyere melting. Therefore, it is necessary to suppress fluctuations in the molten pig iron temperature. Against this background, techniques have been proposed for estimating the amount of heat supplied to the lower part of the blast furnace and the molten pig iron temperature. For example, Patent Document 1 describes a technique for estimating the amount of heat supplied before the tuyere by evaluating the heat of combustion, reaction endotherm, and heat loss before the tuyere, and using this as an indicator of the thermal conditions in the lower part of the furnace. Furthermore, Patent Document 2 describes a technique for predicting the future molten iron temperature in a steady state using operational data including solution loss carbon and operational data including actual values ​​of the molten iron temperature. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2-115311 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-144265 [Non-patent literature]

[0004] [Non-Patent Document 1] Iron and Steel, 1993, pp. N618-N624 Summary of the Invention [Problem to be solved by the invention]

[0005] However, all of the conventional technologies evaluate the heat balance of the entire blast furnace, but are unable to evaluate the excess or deficiency of heat supply in the radial direction of the blast furnace. Generally, there are variations in the amount of ore and the amount of gas flowing in the radial direction of the blast furnace. If gas is not flowing sufficiently to a location with a large amount of ore, the ore cannot be sufficiently heated, and operation must be performed to increase the amount of gas flowing to that location or reduce the amount of ore. However, as described above, the conventional technologies are unable to evaluate the excess or deficiency of heat supply in the radial direction of the blast furnace, and therefore are unable to identify locations where the ore cannot be sufficiently heated and reacted. Therefore, there has been a demand for technology that can evaluate the excess or deficiency of heat supply in the radial direction of the blast furnace and enable low reducing agent ratio operation.

[0006] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a method for evaluating the operational state of a blast furnace that can evaluate the excess or deficiency of the heat supply in the radial direction of the blast furnace. Another object of the present invention is to provide a method for operating a blast furnace that can realize low reducing agent ratio operation. [Means for solving the problem]

[0007] The method for evaluating the operational state of a blast furnace according to the present invention includes a first step of calculating the radial distribution of the amount of ore and the amount of coke based on the piled shapes of the ore and the coke in the blast furnace; a second step of calculating the radial distribution of the flow rate of gas supplied from the lower part of the blast furnace based on the radial distribution of the amount of ore and the amount of coke; a third step of calculating the radial distribution of the passing speed of oxygen moles based on the radial distribution of the flow rate of the gas; a fourth step of calculating the radial distribution of the passing speed of iron moles based on the piled shapes of the ore and the coke in the blast furnace and the production rate of molten pig iron; a fifth step of calculating a radial distribution of the ratio of the number of moles of oxygen to iron based on the radial distribution of the velocity; a sixth step of calculating a radial distribution of the ratio of the number of moles of oxygen to carbon contained in CO and CO2 in the gas components based on the distribution state of the gas components in the radial direction of the upper part of the blast furnace; a seventh step of calculating a radial distribution of the direct reduction rate during operation by applying the radial distribution of the ratio of the number of moles of oxygen to iron and the radial distribution of the ratio of the number of moles of oxygen to carbon to a list model; and an eighth step of evaluating an excess or deficiency of the amount of heat supplied in the radial direction using the calculated radial distribution of the direct reduction rate.

[0008] The eighth step may include a step of evaluating whether the amount of heat supplied in the radial direction is excessive or insufficient based on a value obtained by dividing the sum of the sensible heat required to heat the ore and the amount of heat absorbed by the direct reduction by the sensible heat of the gas.

[0009] The blast furnace operation method according to the present invention includes a step of controlling the operational state of the blast furnace using the evaluation results of the blast furnace operational state evaluation method according to the present invention. [Effects of the Invention]

[0010] According to the method for evaluating the operational state of a blast furnace of the present invention, it is possible to evaluate the excess or deficiency of the heat supply in the radial direction of the blast furnace. Furthermore, according to the method for operating a blast furnace of the present invention, it is possible to realize low reducing agent ratio operation of the blast furnace. [Brief explanation of the drawings]

[0011] [Figure 1]FIG. 1 is a block diagram showing the configuration of a blast furnace operation system according to one embodiment of the present invention. [Figure 2] FIG. 2 is a flowchart showing the flow of an operational status evaluation process according to one embodiment of the present invention. [Figure 3] FIG. 3 is a diagram for explaining the process of step S1 shown in FIG. [Figure 4] FIG. 4 is a diagram for explaining the process of step S2 shown in FIG. [Figure 5] FIG. 5 is a diagram showing a list model. [Figure 6] FIG. 6 is a diagram for explaining the process of step S7 shown in FIG. [Figure 7] FIG. 7 is a diagram showing the distribution of the shaft efficiency and heat balance in the radial direction of the blast furnace obtained by the operational state evaluation process. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, the configuration and operation of a blast furnace operation system according to one embodiment of the present invention will be described with reference to the drawings.

[0013] [System Configuration] First, with reference to FIG. 1, the configuration of a blast furnace operation system according to one embodiment of the present invention will be described.

[0014] FIG. 1 is a block diagram showing the configuration of a blast furnace operation system according to one embodiment of the present invention. As shown in FIG. 1, the blast furnace operation system 1 according to one embodiment of the present invention includes a blast furnace 2, a control device 3, and an evaluation device 4. The control device 3 is configured with an information processing device such as a computer, and includes a sensor group 3a that detects information related to the operational state of the blast furnace 2. The control device 3 controls the operational state of the blast furnace 2 according to various information input from the sensor group 3a, the evaluation device 4, a host computer (not shown), an operation input device (not shown), and the like. The evaluation device 4 is configured with an information processing device such as a computer. The evaluation device 4 evaluates the operational state of the blast furnace 2 and outputs information related to the evaluation results to the control device 3 and an output device.

[0015] In the blast furnace operation system 1 having such a configuration, the evaluation device 4 executes the operation state evaluation process described below to evaluate the excess or deficiency of the heat supply amount in the radial direction of the blast furnace 2. Hereinafter, the operation of the evaluation device 4 when executing the operation state evaluation process will be described with reference to the flowchart shown in FIG.

[0016] [Operational status evaluation process] 2 is a flowchart showing the flow of an operational state evaluation process according to one embodiment of the present invention. The flowchart shown in FIG. 2 starts when the operation of the blast furnace 2 is started, and the operational state evaluation process proceeds to the processing of step S1. The operational state evaluation process shown below is realized by an arithmetic processing unit such as a CPU in an information processing device constituting the evaluation device 4 executing a computer program.

[0017] In the processing of step S1, first, the evaluation device 4 calculates the pile shape of the ore and coke in the blast furnace 2 using a burden distribution model. Specifically, as shown in FIG. 3(a), the burden distribution model is a mathematical model whose input variables include the supply amounts of ore and coke from the furnace top bunker 11 and the rotation angle of the rotating chute 12, which controls the drop position of the ore and coke in the blast furnace 2. The burden distribution model then calculates and outputs, as output variables, the pile shapes of the ore and coke for each rotation of the rotating chute 12 between the center position of the blast furnace 2 and the furnace wall, which correspond to the input variables. The evaluation device 4 calculates the pile shapes of the ore and coke in the blast furnace 2 by inputting the input variables to be processed into this burden distribution model. Then, based on the calculated pile shapes of the ore and coke, the evaluation device 4 calculates the distribution state of the ore amount and the coke amount in the radial direction of the blast furnace 2, as shown in FIG. 3(b). This completes the process of step S1, and the operational status evaluation process proceeds to step S2.

[0018] In the process of step S2, the evaluation device 4 calculates the radial flow velocity distribution of the gas supplied from the tuyere of the blast furnace 2 into the blast furnace 2 based on the radial distribution of the ore and coke amounts of the blast furnace 2 calculated in the process of step S1. Specifically, the evaluation device 4 distributes the gas G supplied from the tuyere of the blast furnace 2 into the blast furnace 2 along the radial direction so as to achieve equal pressure loss, as shown in FIG. 4, according to the thickness, particle size, and porosity of the ore layer and coke layer in the radial direction of the blast furnace 2. The evaluation device 4 then calculates the radial flow velocity distribution of the gas G in the radial direction of the blast furnace 2 according to the distribution result. The thicknesses of the ore layer and coke layer are obtained from the process result of step S1, and the particle size and porosity of the ore layer and coke layer are preset. This completes the process of step S2, and the operational state evaluation process proceeds to the process of step S3.

[0019] In the process of step S3, the evaluation device 4 uses the gas flow velocity distribution state in the radial direction of the blast furnace 2 calculated in the process of step S2, CO and CO in gas components in the radial direction of the blast furnace 2 By calculating the rate of passage of the number of moles of oxygen contained in In the radial direction of blast furnace 2 Number of moles of oxygen (hereafter referred to as oxygen moles)The distribution of the passing speeds inside the ore layer and the coke layer is calculated. This completes the process of step S3, and the operational state evaluation process proceeds to the process of step S4.

[0020] In the process of step S4, the evaluation device 4 calculates, using the pile shapes of the ore and coke in the blast furnace 2 calculated in the process of step S1 and the molten iron production rate at the time when the pile shapes are calculated, By calculating the passing speed of the moles of iron contained in the charged iron oxide in the radial direction of the blast furnace, Inside the ore layer and coke layer in the radial direction of blast furnace 2 Number of moles of iron (hereafter referred to as iron moles) The distribution state of the passing speeds of the vehicles is calculated. This completes the processing of step S4, and the operational state evaluation processing proceeds to the processing of step S5.

[0021] In the process of step S5, the evaluation device 4 uses the distribution of the passing speed of oxygen moles calculated in the process of step S3 and the distribution of the passing speed of oxygen moles derived from iron moles and iron oxide or impurities calculated in the process of step S4 to calculate the distribution of the ratio of the number of moles of oxygen to the number of moles of iron (O / Fe) in the radial direction of the blast furnace 2. This completes the process of step S5, and the operational state evaluation process proceeds to the process of step S6.

[0022] In the process of step S6, the evaluation device 4 uses data on the exhaust gas components in the radial direction of the upper part of the blast furnace 2 detected by the sensor group 3a to calculate the distribution state of the ratio of the number of moles of oxygen to the number of moles of carbon (O / C) contained in CO and CO2 in the exhaust gas in the radial direction of the blast furnace 2. This completes the process of step S6, and the operational state evaluation process proceeds to the process of step S7.

[0023] In the process of step S7, the evaluation device 4 calculates the distribution state of the direct reduction ratio in the radial direction of the blast furnace 2 by applying the data of the distribution states of O / Fe and O / C calculated in the processes of steps S5 and S6 to the list model shown in FIG. 5. Here, the list model is an operation diagram showing a partial heat balance and material balance with O / C on the X axis and O / Fe on the Y axis, and shows the relationship between the operation factors and operation indicators of the blast furnace. For details of the list model, please refer to Non-Patent Document 1. Specifically, first, the evaluation device 4 calculates the gas utilization rate Xa using the data of the distribution state of O / C calculated in the process of step S6, thereby calculating the coordinate value (Xa, Ya) of point A in the list model shown in FIG. 5. The Y coordinate value Ya of point A can be calculated from the conditions of the raw materials charged into the blast furnace 2.

[0024] Next, the evaluation device 4 calculates the coordinate value (0, Yb) of point E in the list model shown in FIG. 5 using the data on the O / Fe distribution state calculated in the processing of step S5. Next, the evaluation device 4 calculates the reducing agent ratio from the slope of a straight line AE connecting point A and point E. Next, the evaluation device 4 calculates the direct reduction rate from the Y coordinate value of the intersection D (1, Ysl) between the line of X=1 and the straight line AE and the coordinate value of point E. Note that Ysl of the intersection D indicates the solution loss carbon consumption unit. Then, as shown in FIG. 6, the evaluation device 4 calculates the distribution state of the direct reduction rate in the radial direction of the blast furnace 2 by repeatedly performing the above processing for each position in the radial direction of the blast furnace 2. This completes the processing of step S7, and the operational state evaluation processing proceeds to the processing of step S8.

[0025] In the process of step S8, the evaluation device 4 calculates the distribution state of the gas sensible heat in the radial direction of the blast furnace 2 using the gas temperature at the upper part of the blast furnace 2 detected by the sensor group 3a. Furthermore, the evaluation device 4 calculates the distribution state of the heat quantity (ore sensible heat quantity) required to heat the ore in the radial direction of the blast furnace 2 using the data on the distribution state of the ore amount in the radial direction of the blast furnace 2 calculated in the process of step S1. Furthermore, the evaluation device 4 calculates data on the distribution state of the heat quantity (endothermic heat quantity) absorbed by direct reduction in the radial direction of the blast furnace 2 using the data on the distribution state of the direct reduction rate in the radial direction of the blast furnace 2 calculated in the process of step S7. Next, the evaluation device 4 uses these calculation results to calculate the distribution state of the value of (ore sensible heat quantity + endothermic heat quantity) / gas sensible heat quantity in the radial direction of the blast furnace 2 as a heat balance distribution (distribution of the ratio of the required heat quantity to the supplied heat quantity). Then, the evaluation device 4 determines the excess or deficiency of the heat quantity at each radial position of the blast furnace 2 based on the obtained heat balance distribution. 7(a) and (b) show examples of the shaft efficiency distribution and heat balance distribution in the radial direction of the blast furnace 2 obtained by the processing of steps S7 and S8. For example, an operator refers to the heat balance distribution shown in FIG. 7(b) and determines that the amount of heat supplied is insufficient in a region where the value of (ore sensible heat amount + endothermic heat amount) / gas sensible heat amount is 1 or greater, and performs an operation to increase the amount of gas flowing to that region or reduce the amount of ore. This processing reduces the reducing agent rate and enables low reducing agent rate operation. This completes the processing of step S8, and the series of operational state evaluation processing ends.

[0026] Although the present invention has been described above as an embodiment, the present invention is not limited to the descriptions and drawings that form part of the disclosure of the present invention. In other words, other embodiments, examples, and operational techniques that can be made by those skilled in the art based on the present invention are all included in the scope of the present invention. [Explanation of symbols]

[0027] 1 Blast furnace operation system 2 blast furnace 3. Control device 3a Sensor group 4 Evaluation equipment

Claims

1. A first step of calculating a radial distribution of an amount of ore and an amount of coke based on the piled shapes of the ore and the coke in the blast furnace; a second step of calculating a radial distribution of the flow velocity of gas supplied from the lower part of the blast furnace based on the radial distribution of the ore amount and the coke amount; A third step of calculating a radial distribution of the passing speed of the number of moles of oxygen contained in CO and CO 2 in the gas components in the radial direction of the blast furnace based on the radial distribution of the flow speed of the gas; a fourth step of calculating a radial distribution of the passing speed of the number of moles of iron contained in the charged iron oxide in the radial direction of the blast furnace based on the pile shape of the ore and coke in the blast furnace and the production rate of the molten iron; a fifth step of calculating a radial distribution of the ratio of the number of moles of oxygen to the number of moles of iron based on the radial distribution of the passage rates of the number of moles of oxygen and the number of moles of iron; Based on the distribution of gas components in the radial direction of the upper part of the blast furnace, CO and CO ２ a sixth step of calculating a radial distribution of the ratio of the number of moles of oxygen to carbon contained in the a seventh step of calculating the radial distribution of the direct reduction ratio during operation by applying the radial distribution of the ratio of the number of moles of oxygen to iron and the radial distribution of the ratio of the number of moles of oxygen to carbon to a list model which is an operation diagram showing the partial heat balance and material balance of a blast furnace, with the ratio of the number of moles of oxygen to the number of moles of carbon contained in CO and CO 2 in the gas components in the radial direction of the blast furnace on the X axis and the ratio of the number of moles of oxygen to the number of moles of iron in the radial direction of the blast furnace on the Y axis; an eighth step of evaluating an excess or deficiency of the amount of heat supplied in the radial direction using the calculated radial distribution of the direct reduction rate; A method for evaluating the operational status of a blast furnace, including:

2. 2. The method for evaluating the operational state of a blast furnace according to claim 1, wherein the eighth step includes a step of evaluating an excess or deficiency in the amount of heat supplied in the radial direction based on a value obtained by dividing the sum of sensible heat required to heat the ore and the amount of heat absorbed by direct reduction by the sensible heat of the gas.

3. A method for operating a blast furnace, comprising a step of controlling the operational state of the blast furnace using an evaluation result of the method for evaluating the operational state of a blast furnace according to claim 1 or 2.

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