Numerical calculation method, calculation apparatus, numerical calculation program, and method for producing sintered ore for iron ore sintering process

Abstract

This invention provides a method for calculating the state within a sintered layer, taking into account heat and gas mass transfer in two directions: the thickness direction and the machine length direction. [Solution] A numerical calculation method for an iron ore sintering process, comprising the steps of: creating a computational mesh in a region on the sintering machine composed of raw materials and sinter cake, in a sintering process in which a powdered material containing iron ore is sintered in a sintering machine to produce sintered ore; and calculating the state inside the sintering machine by calculating the amount of chemical reaction inside each cell, the heat of reaction, the amount of heat transfer between gas molecules and solids, the physical properties of each substance, the temperature change, the amount of heat transfer between each cell in the machine length direction and the layer thickness direction, and the amount of gas molecule movement between each cell in the machine length direction and the layer thickness direction.

Description

Technical Field

[0001] The present disclosure relates to a numerical calculation method for an iron ore sintering process, a calculation device, a numerical calculation program, and a method for producing sintered ore.

Background Art

[0002] Sintered ore, which is one of the raw materials for the blast furnace ironmaking process, is produced by adding several percent of moisture to the main raw material, iron ore, auxiliary raw materials containing CaO such as limestone, auxiliary raw materials containing SiO2 such as silica, returned ore, and solid fuel, mixing and granulating them to form pseudo-granules, and then sintering them by the combustion heat of the solid fuel. After filling the pseudo-particles after granulation into a circulating pallet, ignition is carried out on the surface layer of the raw material filling layer, and air is sucked from below, so that the solid fuel in the filling layer is burned from top to bottom, and the raw material is sintered to produce a sinter cake. After crushing the sinter cake with a crusher, it is sieved to collect lumpy products of 5 mm or more and used as sintered ore for blast furnaces.

[0003] In the sintering process, various in-layer conditions such as temperature and air permeability affect the process productivity and the quality of sintered ore. For example, when the porosity in the layer is low and the air permeability is poor, the gas flow rate passing through the layer decreases. When the gas flow rate in the layer decreases, the ignition and combustion of the solid fuel in the unburned region are delayed, the sintering rate decreases, and the productivity deteriorates. In addition, when the temperature in the layer is low, the melting reaction of the raw material becomes insufficient, leading to a decrease in the lump rate after crusher crushing and a decrease in the cold strength of the sintered ore. Since the in-layer conditions affect the process productivity and the quality of the finished product, etc., the estimation of the in-layer conditions by numerical simulation is expected to be a useful tool for determining operating conditions and controlling the quality of sintered ore, and various simulation models have been developed so far.

[0004] As models for calculating the conditions in the sintering layer and methods for utilizing them, the following have been reported so far.

[0005] In Patent Document 1, based on a combustion model that takes into account each substance in the sintering layer and the heat balance, the sintering layer temperature and the combustion gas composition calculated are used as input values to calculate the gas composition in the gas boundary layer of the coke particles, and NO generated by combustion is calculated from the ratio of CO to O2 in the gas boundary layer. x An evaluation method for evaluating the amount of

[0006] In Patent Document 2, using a physical model that takes into account chemical reactions and heat transfer phenomena, variables observable in the sintering process are calculated, and the unknown parameters in the physical model are corrected from the deviation between the calculated value and the actual value, so that the state of the sintering process can be estimated with high accuracy. Furthermore, by accurately estimating the temperature change in the layer, it is said that operation guidance aimed at improving the yield can be provided for the ratio of coke in the raw material and the pallet speed.

[0007] In Non-Patent Document 1, a simulation model is proposed that applies a combustion rate equation for coke that takes into account the diffusion of oxygen inside the pseudo-particles. By calculating the combustion rate of the coke contained in the fine powder that constitutes the pseudo-particles, taking into account the diffusion of oxygen in the fine powder layer, it is said that a calculation result of the temperature distribution in the layer closer to the actual phenomenon can be obtained.

[0008] In Non-Patent Document 2, the development of a three-dimensional model capable of predicting the quality of sintered ore is reported. By using a three-dimensional model that takes into account various reactions, heat transfer, mass transfer, etc. in the sintering layer, the temperature, porosity, liquid phase ratio, and mineral structure in the layer can be calculated, and it is said that the quality of the sintered ore can be predicted.

[0009] In Non-Patent Document 3, an analysis by numerical simulation of the influence on the layer when blowing in gaseous fuel is reported. A combustion reaction of gaseous fuel is introduced into a simulation model that performs calculations so as to satisfy the mass conservation law, the momentum conservation law, and the energy conservation law, and the influence of blowing in gaseous fuel into the sintering layer is analyzed.

[0010] Non-patent document 4 reports a simulation model that takes into account various reactions occurring within the layer, as well as the pressure drop and wind speed within the layer. The temperature within the layer is calculated by calculating the temperature at minute time intervals using transient heat conduction equations for the heat balance of solids and gases in the sintered layer, and then evolving the model over time. By calculating the pressure drop and wind speed within the layer at each time step, wind speed and pressure close to experimental values ​​are obtained. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Patent No. 5447192 [Patent Document 2] Japanese Patent Publication No. 2024-50752 [Non-Patent Document 1] Iron and Steel, 101(2015), 19. [Non-Patent Document 2] Iron and Steel, 92(2006), 769. [Non-Patent Document 3] ISIJ Int., 51(2011), 913. [Non-Patent Document 4] Iron and Steel, 70(1984), 1567. [Overview of the project] [Problems that the invention aims to solve]

[0012] Conventionally, simulation programs that take into account various phenomena within the sintered layer have been proposed, as shown in Non-Patent Documents 1 and 2. Furthermore, as shown in Patent Documents 1 and 2 and Non-Patent Document 3, simulation programs that take into account NO, which is subject to environmental regulations, have been proposed. x Simulations of conditions within a sintered layer have been used for purposes such as predicting the amount of material produced, improving yield through operational guidance, and analyzing the effects of introducing flammable gases into the layer. However, conventional simulations still have unconsidered factors, and there is still room for improvement in the calculation methods for conditions within the layer. One of the unconsidered factors is the transfer of heat and mass in the direction of the sintering machine's length.

[0013] Furthermore, the sintering process involves drawing gas from below and advancing the combustion chamber from the upper layer to the lower layer. Therefore, the movement of heat and gas molecules within the layer is predominantly in the thickness direction. However, within the sintered layer, temperature and pressure gradients occur not only in the thickness direction but also in the length direction of the machine. Consequently, within the sintered layer, heat and gas molecule movement occurs in accordance with the temperature and pressure gradients not only in the thickness direction but also in the length direction of the machine. In particular, in processes such as those described in Non-Patent Document 3, where flammable gas is drawn into the layer from above, the location within the layer where the injected gas is transported and combusted is a crucial factor, and a simulation program capable of analyzing the two-dimensional movement of gas molecules within the layer is necessary.

[0014] However, most conventional simulation programs, as described in Non-Patent Documents 1 and 4, were one-dimensional models that defined space only in the thickness direction. This is because, as mentioned above, heat and gas molecule transfer within a sintered layer is predominantly in the thickness direction, and therefore, few simulation programs focusing on heat and mass transfer in the machine length direction have been developed. Non-Patent Document 2 reports the development of a three-dimensional simulation program, but it does not show a calculation method for determining heat and mass transfer in the machine length direction. In particular, there is no description of how to determine the pressure distribution within the layer and the two-dimensional gas velocity distribution that satisfy the boundary conditions around the sintering machine. Therefore, there was a need to develop a simulation program that could perform two-dimensional gas transfer analysis taking into account heat and mass transfer in both the thickness direction and the machine length direction.

[0015] The purpose of this disclosure is to provide a method for calculating the state within a sintered layer, taking into account heat and gas mass transfer in two directions: the thickness direction and the machine length direction. The method disclosed also enables two-dimensional analysis of gas transfer amounts. [Means for solving the problem]

[0016] [1] In a sintering process in which a powdered material containing iron ore is sintered in a sintering machine to produce sintered ore, The steps include creating a computational mesh in the region consisting of raw materials and sinter cake on the sintering machine, The process includes the step of calculating the state inside the sintering machine by calculating the amount of chemical reaction inside each cell, the heat of reaction, the amount of heat transfer between gas molecules and solids, the physical properties of each substance, the temperature change, and the amount of heat transfer between cells in the machine length direction and the layer thickness direction, as well as the amount of gas molecule transfer between cells in the machine length direction and the layer thickness direction. Numerical calculation method for the iron ore sintering process.

[0017] [2] In calculating the amount of gas molecule transfer between each of the cells in the machine length direction and the layer thickness direction, Ergun's equation relating pressure difference and gas flow velocity in the layer thickness direction, Ergun's equation relating pressure difference and gas flow velocity in the longitudinal direction of the machine, A numerical calculation method for the iron ore sintering process described in [1] above, characterized in that convergence calculations are performed such that both the equation for continuity and the equation for continuity are satisfied.

[0018] [3] In calculating the amount of gas molecule transfer between each of the cells in the machine length direction and the layer thickness direction, The steps include calculating the amount of gas molecule movement in the layer thickness direction between each cell using the continuity equation, The steps include: calculating the pressure inside each cell using Ergun's equation relating the amount of gas molecule movement in the thickness direction and the pressure difference and gas flow velocity in the thickness direction; The process involves repeatedly performing the steps of calculating the amount of gas molecule movement between cells in the longitudinal direction using Ergun's equation relating the pressure inside each cell, the pressure difference in the longitudinal direction, and the gas flow velocity. A numerical calculation method for the iron ore sintering process described in [1] or [2] above, characterized by performing convergence calculations of the amount of gas molecule transfer between cells and the pressure inside each cell so that the pressure in the outer part of the sintered layer matches the atmospheric pressure around the sintering machine and the pressure inside the windbox.

[0019] [4] In a sintering process in which a powdered material containing iron ore is sintered in a sintering machine to produce sintered ore, A computational mesh is created in the region consisting of the raw materials and sinter cake on the sintering machine. A control unit calculates the state inside the sintering machine by calculating the amount of chemical reaction, heat of reaction, amount of heat transfer between gas molecules and solids, physical properties of each substance, temperature changes, and the amount of heat transfer between cells in the longitudinal and thickness directions, as well as the amount of gas molecule movement between cells in the longitudinal and thickness directions. A numerical calculation device for the iron ore sintering process, equipped with the necessary components.

[0020] [5] To the computer, In a sintering process in which a powdered substance containing iron ore is sintered in a sintering machine to produce sintered ore, Creating a computational mesh in the region consisting of raw materials and sinter cake on the sintering machine, The system calculates the state inside the sintering machine by calculating the amount of chemical reaction, heat of reaction, amount of heat transfer between gas molecules and solids, physical properties of each substance, temperature changes, and the amount of heat transfer between cells in the longitudinal and thickness directions, as well as the amount of gas molecule movement between cells in the longitudinal and thickness directions. A numerical calculation program for the iron ore sintering process.

[0021] [6] A method for producing sintered ore, comprising calculating the state inside a sintering machine using the numerical calculation method for the iron ore sintering process described in any one of the above items [1] to [3], and sintering a powdered substance containing iron ore in a sintering machine to produce sintered ore. [Effects of the Invention]

[0022] According to this disclosure, it is possible to calculate the state within the sintered layer, taking into account heat and gas mass transfer in two directions: the thickness direction of the sintered layer and the length direction of the machine. [Brief explanation of the drawing]

[0023] [Figure 1] This figure shows an example of a numerical calculation system for an iron ore sintering process according to one embodiment of the present disclosure. [Figure 2] This figure schematically represents the structure of the sintering machine included in the numerical calculation system related to this disclosure. [Figure 3A] This is a schematic diagram of the computational domain related to this disclosure. [Figure 3B] This is a diagram showing an enlarged view of a portion of the computational area related to this disclosure. [Figure 4A] This is a flowchart for calculating gas molecule transfer and pressure related to this disclosure. [Figure 4B] This is a flowchart for calculating the amount of gas molecule movement in the layer thickness direction related to this disclosure. [Figure 4C] This is a flowchart for calculating the pressure inside each cell related to this disclosure. [Figure 4D] This is a flowchart for calculating the amount of gas molecule movement in the length direction of the machine related to this disclosure. [Figure 5] This flowchart shows the method for calculating the in-layer state related to this disclosure. [Figure 6] This figure shows the temperature of each cell in the calculation target region according to one embodiment of the present disclosure. [Figure 7] This figure shows a graph illustrating the relationship between temperature and time at a specific layer thickness location according to one embodiment of the present disclosure. [Figure 8A] This figure shows the wind velocity in the layer thickness direction of each cell in the calculation target region according to one embodiment of the present disclosure. [Figure 8B] This figure shows the wind speed in the machine length direction for each cell in the calculation area according to one embodiment of the present disclosure. [Figure 8C] This figure shows the pressure of each cell in the calculation area according to one embodiment of the present disclosure. [Figure 9A] This figure shows a graph of the relationship between the wind speed in the thickness direction and the machine length position at a specific thickness location according to one embodiment of the present disclosure. [Figure 9B] This figure shows a graph illustrating the relationship between the wind speed in the machine's longitudinal direction and the machine's longitudinal position at a specific layer thickness location according to one embodiment of this disclosure. [Figure 9C] This figure shows a graph illustrating the relationship between pressure at a specific layer thickness position and machine length position according to one embodiment of the present disclosure. [Modes for carrying out the invention]

[0024] The embodiments for carrying out the present invention will be described in detail below. The embodiments described below are merely examples of the present invention and do not limit the configuration of the present invention.

[0025] Figure 1 shows an example of a numerical calculation system for an iron ore sintering process according to one embodiment of the present disclosure. The numerical calculation system 1 comprises a calculation device 10 and a sintering machine 20.

[0026] The computing device 10 is a general-purpose computer such as a workstation or personal computer. Alternatively, the computing device 10 may be a dedicated computer configured to function as the computing device 10 of the numerical calculation system 1.

[0027] The computing device 10 comprises a control unit 11, an input unit 12, an output unit 13, and a storage unit 14.

[0028] The control unit 11 includes at least one processor, at least one dedicated circuit, or a combination thereof. The processor is a general-purpose processor such as a CPU (Central Processing Unit) or GPU (Graphics Processing Unit), or a dedicated processor specialized for a specific process. The dedicated circuit is, for example, an FPGA (Field-Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit).

[0029] The control unit 11 reads programs, data, etc., stored in the memory unit 14 and executes various functions.

[0030] The input unit 12 includes one or more input interfaces that detect user input and acquire input information based on user operations. The input unit 12 includes, for example, physical keys, capacitive keys, a touchscreen integrated with the display of the output unit 13, or a microphone that accepts voice input.

[0031] The output unit 13 includes one or more output interfaces for outputting information and notifying the user. The output unit 13 includes, for example, a display for outputting information as an image, a speaker for outputting information as sound, etc. The display included in the output unit 13 may be, for example, an LCD (Liquid Crystal Display), a CRT (Cathode Ray Tube) display, etc.

[0032] The storage unit 14 is, for example, a flash memory, a hard disk, or an optical memory. Part of the storage unit 14 may be located outside the computing device 10. In this case, part of the storage unit 14 may be a hard disk, memory card, or the like, connected to the computing device 10 via any interface.

[0033] The memory unit 14 stores programs for the control unit 11 to execute various functions, data used by those programs, and so on.

[0034] Figure 2 is a schematic diagram of the structure of the sintering machine 20. The sintering machine 20 sintersects the sintering raw material and produces agglomerated sintered ore. The sintering raw material may be, for example, a mixture containing powdered iron ore and limestone.

[0035] The sintering machine 20 comprises a raw material charging section 21, an ignition furnace 22, a waste discharge section 23, and a wind box 24.

[0036] The raw material charging section 21 charges the sintering raw material into the sintering machine 20. After being charged into the sintering machine 20, the sintering raw material may be in the form of multiple layers.

[0037] The ignition furnace 22 ignites the sintering raw material, which has been charged into the sintering machine 20 via the raw material charging section 21. The ignited sintering raw material is transported to the ore discharge section 23 by pallets or the like. During the transport process to the ore discharge section 24, the sintering raw material is ignited in the ignition furnace 22, and combustion proceeds to produce sintered ore. The sintered ore produced during the sintering process is discharged from the ore discharge section 23. Multiple window boxes 24 provided in the sintering machine 20 draw in gas.

[0038] Next, we will explain the processes executed by the control unit 11 of the computing device 10.

[0039] (Method for creating computational meshes) The control unit 11 of the calculation device 10 sets the calculation target area, which consists of the raw material layer and sinter cake on the sintering machine strand. After setting the calculation target area, the control unit 11 of the calculation device 10 divides the calculation target area into meshes in the machine length direction and the layer thickness direction, and calculates the state of the entire calculation area by calculating the state within each mesh. The number of divisions of the machine length and layer thickness with meshes is arbitrary, but as an example, the layer thickness is divided into 50 divisions and the machine length into 30 divisions.

[0040] (Method for calculating inter-cell gas transfer and intra-cell pressure) The control unit 11 of the calculation device 10 calculates the amount of gas molecules moving in two directions, the sintered layer thickness direction and the sintering machine length direction, and the pressure inside each cell. Here, the calculation of gas molecule movement and pressure is performed so that all three equations below, which are the relationship between the pressure difference in the layer thickness direction and the machine length direction and the gas flow velocity, are satisfied: continuity equation (1) and Ergun's equations (2) and (3).

number

[0041] The control unit 11 of the computing device 10 calculates the gas molecule movement amount in the layer thickness direction by a continuous equation, calculates the pressure inside each cell by Ergun's equation, and calculates the gas molecule movement amount in the machine length direction from Ergun's equation, and repeats these steps to calculate the pressure and gas molecule movement amount that satisfy all three equations.

[0042] Hereinafter, a method for calculating the gas molecule movement amount and pressure will be described using FIGS. 3A to 4D. FIG. 3A is a schematic diagram of the calculation target region. FIG. 3B is an enlarged view of the shaded portion of FIG. 3A. FIG. 4A is a calculation flowchart of the gas molecule movement amount and pressure. FIG. 4B is a calculation flowchart of the gas molecule movement amount in the layer thickness direction. FIG. 4C is a calculation flowchart of the pressure inside each cell. FIG. 4D is a calculation flowchart of the gas molecule movement amount in the machine length direction. In the following description, i is the cell number in the layer thickness direction, and j is the cell number in the machine length direction. i max is the number of cell divisions in the layer thickness direction, and j max is and the number of cell divisions in the machine length direction. U x (i,j) is the gas molecule movement amount in the layer thickness direction between each cell, U y (i,j) is the gas molecule movement amount in the machine length direction, and P(i,j) is the pressure inside each cell. n is the number of calculation repetitions, and n max is its maximum value.

[0043] The control unit 11 of the computing device 10 calculates the gas molecule movement amount U x (i,j) in the layer thickness direction between each cell. The method for calculating the gas molecule movement amount in the layer thickness direction is as follows.

[0044] From the above formula (1), the following relationship holds for the gas molecule movement amount of each cell.

number

[0045] Also, U x (i,j) is the amount of gas molecule movement on a molar basis, and the gas flow velocity u x (i,j) is calculated using the following formula (5).

number

[0046] According to the above formula (4), U x (1,j) and U y Given (i,j), from i=1, i=i max The amount of gas molecule migration in the layer thickness direction U x and gas flow velocity u x This can be calculated. Here, in the first iteration of the calculation, n=0, U y (i,j) may be assumed to be 0, and P(i,j) may be assumed to be equal to the ambient pressure around the sintering machine. The control unit 11 of the calculation device 10 sets i=i max The amount of gas molecule migration in the layer thickness direction U x The amount of gas molecule migration in the layer thickness direction U is calculated one line at a time until the calculation is complete. x Calculate.

[0047] The control unit 11 of the calculation device 10 calculates the pressure P(i,j) in each cell. The method for calculating the pressure in each cell is as follows:

[0048] From equation (2) above, the following relationship (6) holds between the pressure and gas flow velocity in each cell.

number

[0049] Here, P(i max ,j) is U x The larger (1,j) is, the higher it becomes. Therefore, the control unit 11 of the computing device 10 will keep U until the condition of equation (7) below is satisfied. x (1,j) A small amount ΔU x Increase it by only that much and repeat the above calculation. By performing this process, the pressure conditions inside the window box and on the sintering machine are satisfied. x (i,j) and P(i,j) can be found.

number

[0050] The calculations shown in Figures 4B and 4C above are performed from j=1 to j=j max By performing this, the control unit 11 of the calculation device 10 determines P(i,j) and U that satisfy the pressure conditions inside the window box and on the sintering machine. x (i,j) can be calculated across the entire computational domain.

[0051] Here, similar to equation (6), the gas flow velocity u in the longitudinal direction of the machine y The following relationship (8) holds between (i,j) and pressure P(i,j).

number

[0052] Equation (8) above is the gas flow velocity u in the direction of the machine length. y This is a quadratic equation in which P(i,j) and P(i,j+1) are given, and u yThis can be easily calculated. As shown in Figures 4B and 4C, P(i,j) has been calculated for all cells constituting the calculation area, so as shown in Figure 4D, the control unit 11 of the calculation device 10 calculates the gas flow velocity u in the machine length direction for all cells using equation (8). y It is possible to calculate . Note that u y When calculating (i,jmax), that is, the flow velocity in the machine's longitudinal direction at a point adjacent to the ore discharge section, the ambient pressure around the sintering machine is applied instead of P(i,j+1) in equation (8).

[0053] Similar to equation (5), the amount of gas molecule transfer U based on the amount of substance in the longitudinal direction of the machine. y (i,j) and gas flow velocity u y The relationship shown in equation (9) below holds for (i,j). Therefore, the control unit 11 of the computing device 10 calculates U for all cells. y (i,j) can be calculated.

number

[0054] U obtained by this convergence calculation x , U y , P, u x u yThis satisfies equations (1), (2), and (3) throughout the entire calculation area, thereby achieving the calculation of gas molecule migration in the layer thickness direction and machine length direction that is the target of this disclosure.

[0055] (Method for calculating intercellular heat transfer) The control unit 11 of the computing device 10 calculates the amount of heat transferred between each cell. In this disclosure, two factors are considered for heat transfer between cells: the amount of heat transferred by conduction in the solid and the amount of sensible heat in the gas moving between cells. For the amount of heat transferred by conduction in the solid, the amount of heat transferred in the thickness direction Q when moving from cell (i,j) to cell (i+1,j) is calculated. x (i,j) is represented by the following equation (10). Also, the amount of heat transfer Q in the machine length direction when moving from cell (i,j) to cell (i,j+1) is also given. y (i,j) is expressed by the following equation (11).

number

[0056] Regarding the sensible heat of the gas moving between cells, the heat quantity q in the thickness direction moving from cell (i,j) to cell (i-1,j) is defined. x (i,j) is represented by the following equation (12). Also, the amount of heat q moving in the length direction from cell (i,j) to cell (i,j+1) is given by... y (i,j) is expressed by the following equation (13).

number

[0057] (Method for calculating heat transfer between gas and solid) The control unit 11 of the computing device 10 calculates the amount of heat transfer that occurs between the gas phase and the solid in each cell. The amount of heat H transferred from the gas to the solid is expressed by the following equation (14).

number

[0058] Next, we will describe how numerical calculation system 1 calculates numerical values ​​in the process of sintering iron ore. Figure 5 is a flowchart showing the method for calculating the in-layer state according to this disclosure.

[0059] In the method for calculating the in-layer state of this disclosure, t=0 is the start time of the calculation, and a predetermined time t max The state within the sintered layer after a certain period of time is calculated. In calculating the state of the region to be calculated, the state of all cells is calculated at small time intervals Δt, and then the state is calculated at a predetermined time t. max The state of the entire computational domain is calculated. Here, Δt can be set arbitrarily as long as the calculation result does not diverge, for example it is 2 seconds. max It is preferable to set a time that is sufficiently longer than the time required for the sintering process, for example, 3000 seconds.

[0060] In step S101, the control unit 11 of the calculation device 10 acquires various calculation conditions for calculating the in-layer state of the sintering raw material. When acquiring the calculation conditions, for example, values ​​obtained from operational performance data in actual operations or arbitrarily set values ​​may be used as calculation conditions.

[0061] The calculation conditions include the sintering machine strand length, raw material layer thickness, pressure inside the windbox, ambient pressure around the sintering machine, position of the ignition furnace on the sintering machine strand, temperature inside the ignition furnace, pallet speed, charging density of sintering raw materials, pseudo particle size, porosity of the raw material layer, blending ratio of solid fuel in the sintering raw materials, blending ratio of limestone in the sintering raw materials, blending ratio of Fe2O3 in the sintering raw materials, and water content of the sintering raw materials.

[0062] In this disclosure, the region consisting of the raw material layer and sinter cake on the sintering machine strand, as shown in the shaded area of ​​Figure 2, is the subject of the calculation. Furthermore, in the calculation of the intralayer state, two-dimensional heat and mass transfer in the layer thickness direction and the machine length direction is calculated. Therefore, the calculation conditions include the layer thickness and the sintering machine strand length as the size of the region to be calculated.

[0063] In this disclosure, the gas transfer rate and pressure within the layer, which is the calculation target region, are calculated using the surrounding pressure as a boundary condition. Therefore, the pressure of the atmosphere surrounding the calculation target region, i.e., inside the wind box and around the sintering machine, is included in the calculation conditions.

[0064] Furthermore, the calculation of gas movement and pressure within the layer involves solving Ergun's equation and the continuity equation simultaneously. Here, the porosity and particle size introduced in Ergun's equation are included in the calculation conditions.

[0065] Generally, in a sintering machine, the surface layer of the sintering material is ignited in the ignition furnace, and combustion proceeds from the upper layer to the lower layer by downward suction. In this disclosure, the heating of the solid directly below the ignition furnace and the ignition of the solid fuel are calculated by calculating the heat exchange between the high-temperature gas drawn into the layer from the ignition furnace and the solid within the layer. Here, the heat exchange between the high-temperature gas in the ignition furnace and the solid directly below it occurs during the period that the material remains in the ignition furnace, and the longer the ignition furnace length and the slower the pallet speed, the longer the ignition time. Also, the higher the gas temperature in the ignition furnace, the greater the amount of heat received by the solid directly below the ignition furnace, and the higher the temperature of the solid. Since the length of the ignition furnace, the temperature inside the ignition furnace, and the pallet speed are necessary to calculate the temperature below the ignition furnace, the calculation conditions include the position of the ignition furnace on the strand and the pallet speed.

[0066] This disclosure describes how to calculate the amount of chemical reaction and the heat of reaction within each cell delimited by the calculation mesh shown in Figure 2. Reactions occurring within the layers during the sintering process include evaporation and condensation of water, thermal dissociation of limestone, combustion of solid fuel, melting of Fe2O3 and CaO, and solidification of the Fe2O3-CaO molten material. To calculate the amount of reaction and the heat of reaction for these chemical reactions, the mixing ratio of solid fuel, water content, limestone mixing ratio, Fe2O3 mixing ratio, and the mass of raw materials in the raw material layer, i.e., the charging density, are required. Therefore, the calculation conditions include the charging density of the sintering raw materials, the mixing ratio of solid fuel, water content, limestone mixing ratio, and Fe2O3 mixing ratio.

[0067] In step S102, the control unit 11 of the calculation device 10 sets the calculation target area, which consists of the raw material layer and sinter cake on the sintering machine strand. After setting the calculation target area, the control unit 11 of the calculation device 10 divides the calculation target area into meshes in the machine length direction and the layer thickness direction, and calculates the state of the entire calculation area by calculating the state within each mesh. The number of divisions of the machine length and layer thickness with meshes is arbitrary, but as an example, the layer thickness is divided into 50 divisions and the machine length into 30 divisions.

[0068] In step S103, the control unit 11 of the computing device 10 sets t to 0. Then, in step S104, the control unit 11 of the computing device 10 adds a small time interval Δt to t.

[0069] In step S105, the control unit 11 of the calculation device 10 calculates the amount of chemical reaction and the heat of reaction in each cell included in the calculation area. The chemical reactions within each cell include evaporation and condensation of water, thermal dissociation of limestone, combustion of solid fuel, melting of Fe2O3 and CaO, and solidification of the Fe2O3-CaO molten liquid. For each cell, the amount of reaction product and the heat of reaction are calculated within a small time interval Δt. For calculating the amount of reaction within a small time interval Δt, for example, the reaction rate equation shown in Non-Patent Document 1 may be applied.

[0070] In step S106, the control unit 11 of the computing device 10 calculates the amount of gas molecule movement in two directions, the sintered layer thickness direction and the sintering machine length direction, and the pressure inside each cell.

[0071] In step S107, the control unit 11 of the computing device 10 calculates the amount of heat transferred between each cell.

[0072] In step S108, the control unit 11 of the computing device 10 calculates the amount of heat transfer occurring between the gas phase and the solid in each cell.

[0073] In step S109, the control unit 11 of the calculation device 10 calculates various physical properties of the solid and gas in the cell. The physical properties calculated here include the specific heat of the solid and gas.

[0074] In step S110, the control unit 11 of the calculation device 10 calculates the temperature change of the gas and solid in each cell from the heat transfer amount, reaction heat amount, and specific heat calculated up to this point. In this step, the temperature change over a small time interval is calculated using the transient heat conduction equation. The calculation in this step can be performed using the same calculation method as shown in Non-Patent Documents 1 and 4.

[0075] In step S111, the control unit 11 of the computing device 10 determines that the value of t is t max Check if it is equivalent to t. max If it is equivalent to (Step S112: Yes), proceed to Step S113. The value of t is t max If the result is not equivalent (step S112: No), the control unit 11 of the computing device 10 repeats the process in step S104.

[0076] In step S112, the control unit 11 of the computing device 10 outputs the calculation result to the output unit 13.

[0077] By performing the calculations described above, it is possible to estimate the state within the sintered layer, taking into account heat and mass transfer in the layer thickness direction and the machine length direction. Furthermore, since the amount of gas molecule transfer in both the layer thickness direction and the machine length direction, as well as the pressure of each cell, are calculated at each time step so as to satisfy both Ergun's equation and the continuity equation, two-dimensional gas transfer analysis is also possible. [Examples]

[0078] The following describes embodiments of the present invention. However, the embodiments of the present invention are not limited to the following embodiments and can be modified as appropriate without departing from the spirit of the invention.

[0079] In this embodiment, a mesh is created by dividing it into 50 sections in the layer thickness direction and 30 sections in the machine length direction, and the state of each cell separated by the mesh is calculated. Figure 6 shows the temperature of each cell in the calculation area. In Figure 6, the vertical axis represents the layer thickness, and the horizontal axis represents the position in the machine length direction. The horizontal axis also shows the elapsed time at each machine length position calculated from the pallet speed. A heat pattern typical of the sintering process, where the high-temperature region expands as you go to the lower layers, is calculated.

[0080] Figure 7 shows a plot of elapsed time on the horizontal axis and temperature on the vertical axis for the layer thickness positions (i), (ii), and (iii) shown in Figure 6. (i), (ii), and (iii) are located at 100 mm, 300 mm, and 500 mm from the surface, respectively, relative to a total layer thickness of 600 mm. The dashed lines in Figure 7 represent the temperature measurements at 100 mm, 300 mm, and 500 mm from the surface during firing tests in a sintering pot tester under the same layer thickness, composition, and suction pressure conditions as shown in Table 1. The calculation results agree well with the experimental results shown by the dashed lines, indicating that the temperature within the layer is appropriately calculated using this calculation method. [Table 1]

[0081] Figures 8A to 8C show the calculated wind speed and pressure for each cell. Figures 8A to 8C show the wind speed in the layer thickness direction, the wind speed in the machine length direction, and the pressure for each cell, respectively. Because the calculation method described in this disclosure is adopted, as shown in Figure 8B, not only the wind speed in the layer thickness direction but also the wind speed in the machine length direction for each cell is calculated. Note that the wind speed in the machine length direction is considered positive in the pallet travel direction and negative in the opposite direction.

[0082] Figures 9A to 9C show plots of the calculated wind speed and pressure on the vertical axis, with the machine length position on the horizontal axis, for each layer thickness position shown in (i) to (iii) in Figures 8A to 8C. In Figure 9A, the wind speed in the layer thickness direction is plotted on the vertical axis. In Figure 9B, the wind speed in the machine length direction is plotted on the vertical axis. In Figure 9C, the pressure is plotted on the vertical axis. In all layer thickness positions (i) to (iii), a relatively large wind speed is generated in the direction of pallet movement near machine length position 0m. This indicates that gas is being drawn from the area in front of the ignition furnace toward the ignition furnace due to suction from the wind box. In addition, for each layer thickness position (i) to (iii), a wind speed in the opposite direction to the pallet movement direction is generated at machine length positions of approximately 20m, 40m, and 70m. This indicates that near the high-temperature section shown in Figure 5, the pressure is higher on the ore discharge side than on the ignition furnace side, resulting in a gas flow in the opposite direction to the pallet movement direction.

[0083] In order to actually measure the velocity distribution of gas flowing within a layer in the direction of the machine's length, it is extremely difficult, as it would require installing a flow meter inside the actual sintering machine layer. By applying the calculation method presented in this disclosure, it becomes possible to estimate the gas flow in the direction of the machine's length within the layer, which is difficult to measure in practice.

[0084] This disclosure is not limited to the embodiments described above. For example, multiple blocks described in the block diagram may be combined, or a single block may be divided. Instead of executing multiple steps described in the flowchart in chronological order as described, they may be executed in parallel or in a different order, depending on the processing capacity of the device performing each step, or as necessary. Other modifications are possible without departing from the spirit of this disclosure. [Explanation of Symbols]

[0085] 1. Numerical Calculation System 10 Computing equipment 11 Control Unit 12 Input section 13 Output section 14 Storage section 20 Sintering machine 21 Raw material loading section 22 Ignition Furnace 23. Mining Unit 24 Window Box

Claims

1. A numerical calculation method for the iron ore sintering process, In a sintering process in which a powdered substance containing iron ore is sintered in a sintering machine to produce sintered ore, The steps include creating a computational mesh in the region consisting of raw materials and sinter cake on the sintering machine, The process includes the step of calculating the state inside the sintering machine by calculating the amount of chemical reaction inside each cell, the heat of reaction, the amount of heat transfer between gas molecules and solids, the physical properties of each substance, the temperature change, and the amount of heat transfer between cells in the machine length direction and the layer thickness direction, as well as the amount of gas molecule transfer between cells in the machine length direction and the layer thickness direction. Numerical calculation method for the iron ore sintering process.

2. In calculating the amount of gas molecule transfer between each of the aforementioned cells in the machine length direction and the layer thickness direction, Ergun's equation relating pressure difference in the layer thickness direction and gas flow velocity, Ergun's equation relating pressure difference and gas flow velocity in the longitudinal direction of the machine, A numerical calculation method for an iron ore sintering process according to claim 1, characterized in that convergence calculations are performed such that both the equation for continuity and the equation for continuity are satisfied.

3. In calculating the amount of gas molecule transfer between each of the aforementioned cells in the machine length direction and the layer thickness direction, The steps include calculating the amount of gas molecule movement in the layer thickness direction between each cell using the continuity equation, The steps include: calculating the pressure inside each cell using Ergun's equation relating the amount of gas molecule movement in the thickness direction and the pressure difference and gas flow velocity in the thickness direction; The process involves repeatedly performing the steps of calculating the amount of gas molecule movement between cells in the longitudinal direction using Ergun's equation relating the pressure inside each cell, the pressure difference in the longitudinal direction, and the gas flow velocity. A numerical calculation method for an iron ore sintering process according to claim 1, characterized in that the amount of gas molecule movement between cells and the pressure inside each cell are calculated to converge so that the pressure in the outer part of the sintered layer matches the atmospheric pressure around the sintering machine and the pressure inside the windbox.

4. A computing device for the iron ore sintering process, In a sintering process in which a powdered substance containing iron ore is sintered in a sintering machine to produce sintered ore, A computational mesh is created in the region consisting of the raw materials and sinter cake on the sintering machine. A control unit calculates the state inside the sintering machine by calculating the amount of chemical reaction, heat of reaction, amount of heat transfer between gas molecules and solids, physical properties of each substance, temperature changes, and the amount of heat transfer between cells in the longitudinal and thickness directions, as well as the amount of gas molecule movement between cells in the longitudinal and thickness directions. A computing device for the iron ore sintering process, equipped with the necessary components.

5. A numerical calculation program for the iron ore sintering process, On the computer, In a sintering process in which a powdered substance containing iron ore is sintered in a sintering machine to produce sintered ore, Creating a computational mesh in the region consisting of raw materials and sinter cake on the sintering machine, The system calculates the state inside the sintering machine by calculating the amount of chemical reaction, heat of reaction, amount of heat transfer between gas molecules and solids, physical properties of each substance, temperature changes, and the amount of heat transfer between cells in the longitudinal and thickness directions, as well as the amount of gas molecule movement between cells in the longitudinal and thickness directions. A numerical calculation program for the iron ore sintering process.

6. A method for producing sintered ore, comprising calculating the state inside a sintering machine using the numerical calculation method for an iron ore sintering process described in any one of claims 1 to 3, and sintering a powdered material containing iron ore in a sintering machine to produce sintered ore.

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