Method for evaluating operating state of blast furnace and operating method

Abstract

In the method for evaluating the operating state of a blast furnace according to the present invention, the radial distribution of the amount of ore and the amount of coke is calculated based on the packing shape of the ore and the coke, the radial distribution of the gas flow rate is calculated based on the radial distribution of the amount of ore and the amount of coke, the radial distribution of the passing speed of oxygen moles is calculated based on the radial distribution of the gas flow rate, the radial distribution of the passing speed of iron moles is calculated based on the packing shape of the ore and the coke and the production speed of molten iron, the radial distribution of the ratio of the number of moles of oxygen to the number of moles of iron is calculated based on the radial distribution of the passing speed of oxygen moles and the passing speed of iron moles, the radial distribution of the ratio of the number of moles of oxygen to the number of moles of carbon contained in CO and CO2 in the gas composition is calculated based on the distribution state of the gas composition, the radial distribution of the direct reduction rate at the time of operation is calculated by applying the radial distribution of the ratio of the number of moles of oxygen to the number of moles of iron and the radial distribution of the ratio of the number of moles of oxygen to the number of moles of carbon to the Rist model, and the excess or deficiency of the radial supply of heat is evaluated using the calculated radial distribution of the direct reduction rate.

Description

Technical Field

[0001] This invention relates to a method for evaluating the operating status of a blast furnace and to a method for operating it. Background Technology

[0002] To ensure stable operation of a blast furnace, the temperature of molten iron needs to be maintained within a specified range. Specifically, when the temperature of molten iron drops to a low level, the viscosity of the molten iron and the slag generated simultaneously with it increases, making it difficult to discharge both molten iron and slag from the taphole. On the other hand, when the temperature of molten iron rises to a high level, the Si concentration in the molten iron increases, and the viscosity of the molten iron also increases. As a result, molten iron adheres to the tuyeres, increasing the risk of tuyeres melting. Therefore, it is necessary to suppress fluctuations in the temperature of molten iron. Against this background, techniques for estimating the heat supplied to the lower part of the blast furnace and the temperature of molten iron have been proposed. For example, Patent Document 1 describes a technique that estimates the heat supplied to the tuyeres by evaluating the heat of combustion, reaction endothermics, and heat loss before the tuyeres, and uses this as an indicator of the thermal condition of the lower part of the furnace. In addition, Patent Document 2 describes a technique that predicts the future temperature of molten iron under steady-state conditions using operational data including dissolved carbon and operational data including actual values ​​of molten iron temperature.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2-115311

[0006] Patent Document 2: Japanese Patent Application Publication No. 2008-144265

[0007] Non-patent literature

[0008] Non-Patent Literature 1: Iron and Steel, 1993, pp. N618-N624 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] However, existing technologies evaluate the overall thermal balance of the blast furnace, but cannot assess the excess or deficiency of radial heat supply. Typically, the ore quantity and gas flow rate fluctuate radially within the blast furnace. In areas with abundant ore, insufficient gas flow prevents adequate heating of the ore, necessitating adjustments to either increase the gas flow rate or decrease the ore quantity in those areas. However, as mentioned above, existing technologies cannot assess the excess or deficiency of radial heat supply, thus failing to identify areas where the ore cannot be adequately heated for reaction. Therefore, there has been a strong demand for a technology capable of assessing the excess or deficiency of radial heat supply in the blast furnace, thereby enabling low reducing agent ratio operation.

[0011] This invention was made to solve the above-mentioned problems, and its object is to provide a method for evaluating the operating condition of a blast furnace capable of assessing the excess or deficiency of radial heat supply. Another object of this invention is to provide an operating method for a blast furnace capable of operating with a low reducing agent ratio.

[0012] Methods for solving problems

[0013] The blast furnace operation status evaluation method of the present invention includes: a first step, calculating the radial distribution of ore and coke quantities based on the packing shape of ore and coke in the blast furnace; a second step, calculating the radial distribution of the flow velocity of gas supplied from the bottom of the blast furnace based on the radial distribution of ore and coke quantities; a third step, calculating the radial distribution of the oxygen molar velocity based on the radial distribution of the gas flow velocity; a fourth step, calculating the radial distribution of the iron molar velocity based on the packing shape of ore and coke in the blast furnace and the iron production rate; and a fifth step, calculating the radial distribution of the oxygen molar velocity based on the iron molar velocity. The radial distribution of the molar velocity of the blast furnace is used to calculate the radial distribution of the ratio of the number of moles of oxygen to iron; the sixth step is to calculate the radial distribution of the ratio of the number of moles of oxygen to carbon in CO and CO2 in the gas composition based on the radial distribution of the gas composition in the upper part of the blast furnace; the seventh step is to calculate the 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 the Lister model; and the eighth step is to evaluate the excess or deficiency of radial heat supply using the calculated radial distribution of the direct reduction rate.

[0014] The eighth step mentioned above preferably includes the following steps: evaluating the excess or deficiency of radial heat supply based on the value obtained by dividing the sum of the sensible heat required to heat the ore and the heat absorbed by direct reduction by the sensible heat of the gas.

[0015] The blast furnace operation method of the present invention includes the following steps: using the evaluation results of the blast furnace operation status evaluation method of the present invention to control the operation status of the blast furnace.

[0016] Invention Effects

[0017] The blast furnace operation status evaluation method according to the present invention can evaluate the excess or deficiency of radial heat supply to the blast furnace. Furthermore, the blast furnace operation method according to the present invention can achieve low reducing agent ratio operation of the blast furnace. Attached Figure Description

[0018] Figure 1 This is a block diagram illustrating the configuration of the operating system of a blast furnace according to one embodiment of the present invention.

[0019] Figure 2 This is a flowchart illustrating the operation status evaluation process of one embodiment of the present invention.

[0020] Figure 3 It is used for explanation Figure 2 The diagram shows the processing of step S1.

[0021] Figure 4 It is used for explanation Figure 2 The diagram shows the processing of step S2.

[0022] Figure 5 This is a diagram illustrating the Lister model.

[0023] Figure 6 It is used for explanation Figure 2 The diagram shows the processing in step S7.

[0024] Figure 7 This is a diagram showing the radial furnace efficiency and heat balance distribution of a blast furnace obtained through operational status evaluation. Detailed Implementation

[0025] Hereinafter, with reference to the accompanying drawings, the configuration and operation of the operating system of a blast furnace according to one embodiment of the present invention will be described.

[0026] [System Composition]

[0027] First, refer to Figure 1 The configuration of the operating system of a blast furnace according to one embodiment of the present invention will be described.

[0028] Figure 1 This is a block diagram illustrating the configuration of an operating system for a blast furnace according to one embodiment of the present invention. Figure 1 As shown, in one embodiment of the present invention, the blast furnace operating system 1 includes a blast furnace 2, a control device 3, and an evaluation device 4. The control device 3 is composed of an information processing device such as a computer, and includes a sensor group 3a that detects information related to the operating state of the blast furnace 2. The control device 3 controls the operating state of the blast furnace 2 based on various information input from the sensor group 3a, the evaluation device 4, a host computer (not shown), and an operation input device (not shown). The evaluation device 4 is composed of an information processing device such as a computer. The evaluation device 4 evaluates the operating state of the blast furnace 2 and outputs information related to the evaluation results to the control device 3 and an output device.

[0029] In the operating system 1 of the blast furnace with this configuration, the evaluation device 4 evaluates the excess or deficiency of radial heat supply to the blast furnace 2 by performing the operating status evaluation process shown below. Hereinafter, refer to... Figure 2 The flowchart shown illustrates the operation of the evaluation device 4 during the execution of the operation status evaluation process.

[0030] [Operational Status Evaluation and Processing]

[0031] Figure 2 This is a flowchart illustrating the operation status evaluation process of one embodiment of the present invention. Figure 2 The flowchart shown begins at the start of operation of blast furnace 2, and the operation status evaluation process proceeds to step S1. It should be noted that the operation status evaluation process described below is implemented by a computer program executed by a processing unit such as a CPU within the information processing device constituting the evaluation device 4.

[0032] In step S1, firstly, the evaluation device 4 uses a burden distribution model to calculate the packing shape of ore and coke within the blast furnace 2. Specifically, as... Figure 3 As shown in (a), the furnace charge distribution model is a mathematical model that includes the supply rate of ore and coke from the top charge bin 11 and the rotation angle of the rotating chute 12, which controls the falling position of ore and coke within the blast furnace 2, as input variables. The furnace charge distribution model then calculates and outputs the packing shape of ore and coke between the center position of the blast furnace 2 and the furnace wall as the rotating chute 12 rotates, corresponding to the input variables, as the output variable. The evaluation device 4 calculates the packing shape of ore and coke within the blast furnace 2 by inputting the input variables of the object to be processed into the furnace charge distribution model. Then, based on the calculated packing shape of ore and coke, the evaluation device 4 calculates... Figure 3 (b) shows the radial distribution of ore and coke in blast furnace 2. Thus, step S1 is completed, and the operational status evaluation process proceeds to step S2.

[0033] In step S2, the evaluation device 4 calculates the radial velocity distribution of the gas supplied from the tuyeres of blast furnace 2 into the blast furnace 2, based on the radial distribution of ore and coke content calculated in step S1. Specifically, the evaluation device 4 calculates the radial velocity distribution of the gas supplied from the tuyeres of blast furnace 2 into the blast furnace 2, based on the thickness, particle size, and porosity of the radial ore and coke layers. Figure 4 The gas G supplied radially from the tuyeres of blast furnace 2 into the blast furnace is distributed to achieve equal pressure loss. Then, the evaluation device 4 calculates the radial velocity distribution of the gas G in blast furnace 2 based on the distribution results. It should be noted that the thicknesses of the ore layer and coke layer are obtained based on the processing results of step S1, and the particle size and porosity of the ore layer and coke layer are preset. Thus, step S2 is completed, and the operation status evaluation process proceeds to step S3.

[0034] In step S3, the evaluation device 4 uses the radial gas velocity distribution of the blast furnace 2 calculated in step S2 to calculate the radial oxygen molar velocity distribution within the ore and coke layers of the blast furnace 2. Thus, step S3 is completed, and the operation status evaluation process proceeds to step S4.

[0035] In step S4, the evaluation device 4 uses the ore and coke packing shape calculated in step S1, along with the iron production rate at the moment the packing shape was calculated, to calculate the distribution of the iron molar velocity within the radial ore and coke layers of the blast furnace 2. Thus, step S4 is completed, and the operation status evaluation proceeds to step S5.

[0036] In step S5, the evaluation device 4 uses the distribution of oxygen moles' passage velocity calculated in step S3, and the distribution of iron moles' passage velocity and oxygen moles' passage velocity originating from iron oxide or impurities calculated in step S4, to calculate the radial distribution of the ratio of oxygen moles to iron moles (O / Fe) in the blast furnace 2. Thus, step S5 is completed, and the operation status evaluation process proceeds to step S6.

[0037] In step S6, the evaluation device 4 uses data on the radial exhaust gas composition detected by sensor group 3a from the upper part of blast furnace 2 to calculate the distribution of the ratio (O / C) of the number of moles of oxygen to the number of moles of carbon in CO and CO2 in the radial exhaust gas of blast furnace 2. Thus, step S6 is completed, and the operation status evaluation process proceeds to step S7.

[0038] In step S7, the evaluation device 4 applies the data on the distribution states of O / Fe and O / C calculated in steps S5 and S6 to... Figure 5 The Lister model shown is used to calculate the radial distribution of the direct reduction rate of blast furnace 2. Here, the Lister model refers to an operation line diagram showing partial heat and mass balance with the X-axis as O / C and the Y-axis as O / Fe, illustrating the relationship between operating factors and operating parameters of the blast furnace. For details on the Lister model, please refer to Non-Patent Literature 1. Specifically, firstly, the evaluation device 4 uses the data on the O / C distribution calculated in step S6 to calculate the gas utilization rate Xa, thereby calculating... Figure 5 The coordinates (Xa, Ya) of point A in the List model are shown. It should be noted that the Y coordinate value Ya of point A can be calculated based on the conditions of the raw materials charged into blast furnace 2.

[0039] Next, the evaluation device 4 uses the O / Fe distribution data calculated in step S5 to calculate... Figure 5The coordinates of point E in the Lister model shown are (0, Yb). Next, evaluation device 4 calculates the reducing agent ratio based on the slope of the straight line AE connecting point A and point E. Next, evaluation device 4 calculates the direct reduction rate based on the Y-coordinate of the intersection point D (1, Ysl) of the line X=1 and the line AE, and the coordinates of point E. It should be noted that Ysl at intersection D represents the unit consumption of dissolved carbon. Then, as... Figure 6 As shown, the evaluation device 4 repeatedly performs the above process at various radial positions of the blast furnace 2 to calculate the radial distribution of the direct reduction rate of the blast furnace 2. Thus, step S7 is completed, and the operation status evaluation process proceeds to step S8.

[0040] In step S8, the evaluation device 4 uses the temperature of the gas above the blast furnace 2 detected by sensor group 3a to calculate the radial distribution of sensible heat of the gas in the blast furnace 2. Additionally, the evaluation device 4 uses the radial distribution of ore quantity in the blast furnace 2 calculated in step S1 to calculate the radial distribution of heat required to heat the ore (sensible heat of the ore). Furthermore, the evaluation device 4 uses the radial distribution of the direct reduction rate in the blast furnace 2 calculated in step S7 to calculate the radial distribution of heat absorbed by direct reduction (endothermic heat) in the blast furnace 2. Next, using these calculation results, the evaluation device 4 calculates the radial distribution of (sensible heat of the ore + endothermic heat) / sensible heat of the gas in the blast furnace 2 as the heat balance distribution (the distribution of the ratio of required heat to supplied heat). Then, based on the obtained heat balance distribution, the evaluation device 4 determines whether there is a heat surplus or deficit at each radial position of the blast furnace 2. Figure 7 (a) and (b) show an example of the radial furnace efficiency distribution and heat balance distribution of blast furnace 2 obtained through steps S7 and S8. For example, the operator refers to... Figure 7 (b) shows a heat balance distribution. In areas where the ratio of (sensible heat of ore + absorbed heat) / sensible heat of gas is greater than 1, it is determined that the heat supply is insufficient. Operations are then performed to increase the gas flow rate in these areas or decrease the amount of ore in them. This process reduces the reducing agent ratio, enabling low reducing agent ratio operation. Thus, step S8 is completed, and the series of operational status evaluation processes conclude.

[0041] The embodiments of the invention made by the inventors have been described above, but the present invention is not limited to the descriptions and drawings that constitute a part of the disclosure of the present invention based on these embodiments. That is, other embodiments, examples, and techniques made by those skilled in the art based on these embodiments are all included within the scope of the present invention.

[0042] Industrial availability

[0043] According to the present invention, a method for evaluating the operating condition of a blast furnace can be provided, capable of assessing excess or deficiency in the radial heat supply of the blast furnace. Furthermore, according to the present invention, an operating method for a blast furnace capable of achieving low reducing agent ratio operation can be provided.

[0044] Symbol Explanation

[0045] 1. Blast Furnace Operating System

[0046] 2 Blast Furnace

[0047] 3. Control device

[0048] 3a Sensor Group

[0049] 4. Evaluation device

Claims

1. A method for evaluating the operating status of a blast furnace, comprising: The first step is to calculate the radial distribution of ore and coke quantities based on the packing shape of ore and coke in the blast furnace. The second step is to calculate the radial distribution of the flow rate of the gas supplied from the bottom of the blast furnace based on the radial distribution of the ore and coke quantities. The third step is to calculate the radial distribution of the passing velocity of oxygen moles based on the radial distribution of the gas flow rate. The fourth step is to calculate the radial distribution of the iron molar's passing velocity based on the packing shape of the ore and coke in the blast furnace and the production rate of the molten iron. The fifth step is to calculate the radial distribution of the ratio of oxygen to iron moles based on the radial distribution of the passing velocities of oxygen moles and iron moles. The sixth step is to calculate the radial distribution of the ratio of oxygen to carbon in CO and CO2 in the gas components based on the radial distribution of gas components in the upper part of the blast furnace. The seventh step involves applying the radial distribution of the molar ratio of oxygen to iron and the radial distribution of the molar ratio of oxygen to carbon to the Lister model to calculate the radial distribution of the direct reduction rate during operation. as well as The eighth step is to use the calculated radial distribution of the direct reduction rate to evaluate the excess or deficiency of radial heat supply.

2. The method for evaluating the operating status of a blast furnace according to claim 1, wherein, The eighth step includes the following steps: evaluating the excess or deficiency of radial heat supply based on the value obtained by dividing the sum of the sensible heat required to heat the ore and the heat absorbed by direct reduction by the sensible heat of the gas.

3. A method for operating a blast furnace, comprising the following steps: using the evaluation results of the blast furnace operation status evaluation method according to claim 1 or 2 to control the operation status of the blast furnace.

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