Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21B—MANUFACTURE OF IRON OR STEEL
  • C21B5/00—Making pig-iron in the blast furnace
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21B—MANUFACTURE OF IRON OR STEEL
  • C21B7/00—Blast furnaces
  • C21B7/24—Test rods or other checking devices

Definitions

• the present invention relates to a method for predicting blast furnace operation, a method for training in blast furnace operation, a method for designing blast furnace operation, a program, and a terminal device.
• the blast furnace process is the primary steelmaking process, accounting for more than 80% of Japan's crude steel production.
• the blast furnace process produces molten pig iron by charging raw materials into the furnace from the top and injecting oxygen-containing gas into the furnace from the bottom.
• This large-scale process with an internal volume of approximately 5,000 m3 , is essential.
• the goal of the blast furnace process is to produce molten pig iron stably with high productivity and a low reducing agent ratio (the amount of reducing agent required to produce one ton of molten pig iron).
• the ultimate goal of blast furnace operation is to perform appropriate operational procedures according to the furnace's condition and stabilize the furnace's condition.
• Blast furnaces have become larger in size to improve production efficiency, but their size means that the time constant for operations (the time required for the state of the blast furnace to actually change after an operation is performed) is large. Furthermore, there are many factors that affect the state of a blast furnace, such as the particle size and reaction characteristics of the raw materials, and the molten material present in the basin. For this reason, stable blast furnace operation relies heavily on the many years of experience of skilled operators. To achieve stable blast furnace operation without relying on the experience of skilled operators, it is effective to utilize simulation technology that predicts the state of the blast furnace, which has been developed in line with recent advances in computer technology, and to provide training aimed at improving operator operating techniques.
• Patent Document 1 proposes a method for predicting molten iron temperature using a physical model that can calculate the state inside a blast furnace under unsteady conditions. Furthermore, education aimed at improving operator operational skills has been carried out through a variety of methods, including textbook-based education, oral transfer of skills from experienced operators to younger operators, and methods that allow operators to experience simulated blast furnace operation (see Patent Document 2).
• Patent No. 6531782 Japanese Patent Application Laid-Open No. 2003-328017 International Publication No. 2022/168556
• the present invention was made to solve the above-mentioned problems, and its purpose is to provide a blast furnace operation prediction method and program that can accurately predict the state of a blast furnace, taking into account the effects of molten material present in the basin. Another purpose of the present invention is to provide a blast furnace operation training method and terminal device that can improve blast furnace operation techniques. Another purpose of the present invention is to provide a blast furnace operation design method and terminal device that can suppress operational fluctuations and equipment troubles.
• the blast furnace operation prediction method of the present invention is a method for predicting the state of a blast furnace using a non-steady mathematical model that calculates the state of the blast furnace, and includes a first step of calculating the liquid level of the molten material in the blast furnace, and a second step of adjusting a process constant related to the gas flow in the radial direction inside the blast furnace, which is included in the non-steady mathematical model, based on the liquid level of the molten material calculated in the first step.
• the process constants may include a heat extraction coefficient and a reduction rate constant.
• the first step may include a step of calculating the liquid surface height of the molten material using the calculation results of the unsteady mathematical model.
• the first step may include a step of calculating the liquid level of the molten material using operation monitoring information of the blast furnace.
• the blast furnace operation education method of the present invention is a method for educating trainees on blast furnace operation by presenting the trainee with the state of the blast furnace predicted using the blast furnace operation prediction method of the present invention, and includes a third step of calculating changes in the state of the blast furnace within the calculation period by changing the process constants included in the unsteady mathematical model within the calculation period based on a preset fluctuation pattern, and a fourth step of presenting to the trainee changes in the blast furnace operating parameters and/or monitoring information obtained from the calculation results of the third step.
• the method includes a fifth step of recalculating, in response to input of operational operation variables at any time within the calculation period, changes in the state of the blast furnace starting from the any time using the input operational operation variables and the unsteady mathematical model; and a sixth step of presenting to the trainee changes in the operational parameters and/or monitoring information of the blast furnace obtained from the recalculation results of the fifth step and changes in the operational parameters and/or monitoring information of the blast furnace obtained from the calculation results of the third step.
• the blast furnace operation design method of the present invention is a method for designing blast furnace operation based on the state of the blast furnace predicted using the blast furnace operation prediction method of the present invention, and includes a third step of calculating changes in the state of the blast furnace during the calculation period by changing the process constants included in the unsteady mathematical model during the calculation period based on a preset fluctuation pattern, and a fourth step of presenting to the designer changes in the blast furnace operating parameters and/or monitoring information obtained from the calculation results of the third step.
• the program according to the present invention causes an information processing device to execute the blast furnace operation prediction method according to the present invention.
• the terminal device is equipped with an output means for outputting information regarding the state of a blast furnace predicted using the blast furnace operation prediction method according to the present invention.
• the blast furnace operation prediction method and program of the present invention make it possible to accurately predict the state of a blast furnace by taking into account the effects of molten material present in the basin. Furthermore, the blast furnace operation training method and terminal device of the present invention make it possible to improve blast furnace operation techniques. Furthermore, the blast furnace operation design method and terminal device of the present invention make it possible to suppress operational fluctuations and equipment troubles.
• FIG. 1 is a diagram showing the configuration of a cold model.
• FIG. 2 is a diagram showing the relationship between the measured and calculated values of the liquid surface shape.
• FIG. 3 is a diagram showing the relationship between the measured and calculated values of the pressure drop on the outlet side of the tuyere.
• FIG. 4 is a diagram showing the calculation results of the gas flow in the cold model.
• FIG. 5 is a diagram showing the relationship between the heat removal coefficient of the lower furnace and the liquid level.
• FIG. 6 is a diagram showing the relationship between the reduction rate constant and the liquid level.
• FIG. 7 is a diagram showing the time changes in the operational parameters of a blast furnace.
• FIG. 8 is a diagram showing the change over time in the operation monitoring information of the blast furnace.
• FIG. 1 is a diagram showing the configuration of a cold model.
• FIG. 2 is a diagram showing the relationship between the measured and calculated values of the liquid surface shape.
• FIG. 3 is a diagram showing the relationship between the measured and calculated values of the pressure
• FIG. 9 is a block diagram showing the configuration of a blast furnace operation simulator according to one embodiment of the present invention.
• FIG. 10 is a diagram showing an example of a user interface screen.
• FIG. 11 is a diagram showing an example of the operation screen.
• FIG. 12 is a graph showing the time-dependent changes in blast flow rate, coke ratio, and Si concentration in molten iron.
• a numerical model was constructed that could calculate the pressure and liquid surface shape at the outlet side of the tuyere 2 based on the flow rate distribution (gas flow) of the injected air in the cold model 1.
• the pressure at the outlet side of the tuyere 2 and the liquid surface shape in the cold model 1 were calculated using the constructed numerical model.
• the numerical model was designed to calculate the entire furnace body of Cold Model 1, with tuyere 2 at the bottom of the furnace body and the assumption that packed particles and liquid exist within the furnace body. Then, in order to reproduce the phenomenon in which the liquid surface shape and the pressure at the outlet side of tuyere 2 change depending on the amount of liquid and the flow rate of air blown in from tuyere 2, simultaneous equations relating to the flow of air blown in from tuyere 2 and the liquid surface shape were solved. Other calculation conditions such as particle size, viscosity, and density used the values of the materials used in the actual test.
• the air flow was calculated according to the Ergin equation shown in the following formula (1), the continuity equation shown in the following formula (2), and the equation of state for an ideal gas shown in the following formula (3).
• ⁇ g is the density of air (kg/ m3 )
• p is the air pressure (Pa)
• ⁇ is the void ratio of the packed bed (-)
• dr is the packed particle diameter (m)
• q is the air flow velocity between the packed particles (m/s)
• ⁇ is the kinematic viscosity of air ( m2 /s)
• r is the radial distance of the furnace body (m)
• K is the gas constant (J/K/kg)
• T is the gas temperature (°C).
• liquid surface shape was calculated using the following formula (4), assuming that the drag force caused by the injected air is equal to the hydrostatic pressure.
• ⁇ 1 is the density of the liquid (kg/m 3 )
• g is the gravitational acceleration (m/s 2 )
• h is the height of the liquid (m).
• Figures 2(a) and (b) show the relationship between the measured and calculated liquid surface shape in Tests 1 and 2, which differ in the amount of water introduced into the cold model 1.
• Figures 3(a) and (b) show the relationship between the measured and calculated pressure drop at the outlet of the tuyere 2 in Tests 1 and 2.
• the calculated values for both the liquid surface shape and pressure drop agree well with the measured values. This indicates that the constructed numerical model is able to reproduce with sufficient accuracy the relationship between the molten material present in the blast furnace basin and the radial gas flow within the blast furnace.
• Figures 4(a) and 4(b) show the calculated results of gas flow within the cold model 1 in Tests 1 and 2.
• the above-mentioned numerical model makes it possible to quantitatively evaluate the effect of the molten material height in the blast furnace on blast furnace operation, i.e., the effect of the molten material height in the blast furnace on the radial gas flow within the blast furnace. Therefore, in the present invention, the relationship between the molten material height and the radial gas flow within the blast furnace is taken into account in an unsteady mathematical model, which is a physical model that can calculate the state within a blast furnace in an unsteady state.
• the unsteady-state mathematical model is a physical model for calculating the state of a blast furnace in an unsteady state, using the region from the furnace top to the hearth as a calculation domain. It is composed of a group of partial differential equations representing various reactions occurring in the blast furnace. Examples of input variables for the unsteady-state mathematical model include operational parameters such as blast conditions and raw material conditions, and the level of the molten material.
• This unsteady-state mathematical model can predict the state of a blast furnace, such as the temperature and pressure distribution in the blast furnace and the distribution of the raw material in the solid phase, by taking into account heat exchange and chemical reactions between the solid, liquid, and gas phases, pressure losses due to gas flow, etc.
• Examples of phenomena considered as chemical reactions include the reduction reaction of ore by reducing gas, the reduction reaction of ore by coke, the gasification reaction of coke with carbon dioxide and steam, the melting reaction of iron and slag, the combustion reaction of coke and materials injected into the tuyere (e.g., pulverized coal, hydrocarbon gas, etc.), and carburization reactions.
• the boundary conditions for the calculation include the conditions for the raw materials flowing in from the top of the furnace, the air flow conditions near the tuyere, the heat removal conditions from the furnace body, and the conditions for discharging the molten material from the taphole.
• the air flow conditions from the shaft can also be used as boundary conditions.
• the unsteady mathematical model also holds process constants for tuning the calculated values to the measured values. Examples of such process constants include constants that adjust the reaction rate and heat exchange rate, and the void ratio of the packed bed.
• the blast furnace operation method is a method for predicting the state of a blast furnace using the above-described unsteady mathematical model, and includes: a first step of calculating a liquid level of molten material in the blast furnace; and a second step of adjusting a process constant, included in the unsteady mathematical model and related to a radial gas flow in the blast furnace, based on the liquid level of molten material calculated in the first step.
• the liquid level of molten material in the blast furnace is calculated using a known method.
• the liquid level of molten material may be calculated using the calculation results of the unsteady mathematical model, or the liquid level of molten material may be calculated using blast furnace operation monitoring information (such as the iron-making rate, the iron-slag tapping rate, and the void fraction of the coke in the lower furnace) (see, for example, Patent Document 3).
• blast furnace operation monitoring information such as the iron-making rate, the iron-slag tapping rate, and the void fraction of the coke in the lower furnace
• the process constants related to gas flow in the radial direction inside the blast furnace are adjusted based on the smelt level calculated in the first step.
• the coefficient that adjusts the amount of heat removed from the furnace wall according to the smelt level is changed to simulate the increase in the amount of heat removed from the furnace wall due to the gas becoming a peripheral flow depending on the smelt level.
• the coefficient that adjusts the reduction rate is changed to simulate the decrease in reduction efficiency.
• the relationship between the smelt level and the various adjustment coefficients differs depending on the blast furnace, but the analysis method and results for a specific blast furnace are shown below.
• the operational parameters of a specific blast furnace for a specific period are input into a one-dimensional unsteady mathematical model to obtain calculated operational results for the blast furnace.
• the method described in Patent Document 3, etc. is then used to calculate the change in the liquid level height of the molten material over that specific period.
• several periods of eight hours or more in which the operational state does not change significantly are extracted, and the average values of the operational parameters and actual operational results for each period are calculated, with these calculated values being the average values of the operational parameters and actual operational results for each extracted period.
• the average values for the same period of calculated operational results obtained using the one-dimensional unsteady mathematical model are also calculated, and these calculated values are used as the average values of the calculated operational results for each period.
• a process constant related to the radial gas flow in the blast furnace is adjusted so that the average value of the actual operation results for each extraction period matches the average value of the calculated operation results.
• h is the heat transfer coefficient [kJ/m 2 /s/K]
• Tg is the furnace gas temperature [K]
• Te is the ambient temperature [K]
• Pr is the gas reduction potential [mol]
• Rr is the reduction resistance [s] determined by the gas flow rate, ambient temperature, and the reducibility of the raw material.
• Other adjustable process constants related to the radial gas flow in the blast furnace include a coefficient for adjusting the coke gasification rate, a coefficient for adjusting the apparent porosity (distribution) in the packed bed, and a coefficient for adjusting the heat transfer rate between the solid and gas phases.
• An example of a coefficient for adjusting the coke gasification rate is the dimensionless coefficient outer multiplied by the parameter k C * in Equation (15) described in Non-Patent Document 1.
• An example of a coefficient for adjusting the heat transfer rate between the solid and gas phases is the dimensionless coefficient outer multiplied by the parameter h in Equation (5) described in Non-Patent Document 1.
• adjustable process constants related to the radial gas flow inside the blast furnace include (a) the heat removal coefficient, (b) the reduction rate constant, (c) a coefficient for adjusting the coke gasification rate, (d) the apparent void fraction, and (e) a coefficient for adjusting the heat transfer rate between the solid and gas phases.
• process coefficients that can be adjusted are adjusted as fixed values
• process constants (a) to (e) are process constants (a) to (e) (in principle, adjustment is possible by simply adjusting process constant (d)).
• the actual and calculated heat loss values were matched using the lower furnace heat removal coefficient, and the actual and calculated gas utilization rates were matched using the reduction rate constant.
• the above process constants can be adjusted manually by trial and error, or mechanically using a search method or other technique.
• Figures 5 and 6 show the relationship between the lower furnace heat removal coefficient and reduction rate constant and the liquid level height, adjusted so that the actual and calculated values match.
• a linear relationship showing the correlation between the two was formulated, as shown by the solid line, and the formulated relationship was incorporated into a one-dimensional unsteady mathematical model.
• FIG. 9 is a block diagram showing the configuration of a blast furnace operation simulator according to one embodiment of the present invention.
• the blast furnace operation simulator according to one embodiment of the present invention includes an information processing device 10, an input device 11, and an output device 12.
• the information processing device 10 is configured by an information processing device such as a workstation or a personal computer.
• An operation simulation program 10a is stored in the information processing device 10.
• the information processing device 10 functions as a blast furnace operation simulator that executes the above-described blast furnace operation prediction method according to the present invention by having an arithmetic processing device such as a CPU in the information processing device 10 execute the operation simulation program 10a.
• the input device 11 is composed of operation input devices such as a mouse pointer and keyboard.
• the input device 11 inputs operation input information to the information processing device 10.
• the output device 12 is composed of output devices such as a printing device, display device, and audio output device.
• the output device 12 outputs various information in accordance with control signals from the information processing device 10.
• the input device 11 and output device 12 function as terminal devices according to the present invention.
• the input device 11 and output device 12 may be composed of a single device.
• the information processing device 10, the input device 11, and the output device 12 may be connected via telecommunications lines such as the Internet.
• the information processing device 10 predicts changes in the state of the blast furnace based on the input information and outputs the predicted information to the output device 12.
• the trainees can experience the operation of a blast furnace in a simulated manner, making the blast furnace operation simulator useful as a means of educating operators on operation.
• the trainee first selects the target blast furnace and case study example.
• the calculation domain, boundary conditions, and initial values for the state inside the furnace, which are determined by the furnace shape can be changed to suit the trainee's own experience.
• Case studies can be set up to simulate operational fluctuations or equipment troubles that could actually occur, such as an increase in the fineness ratio of charged raw materials, an inability to tap hot metal due to a malfunctioning drilling machine, or the shutdown of pulverized coal injection equipment.
• the information processing device 10 changes the calculation boundary conditions and internal variables in accordance with pre-set fluctuation patterns in response to the operational fluctuations or equipment troubles. This allows trainees to simulate operational fluctuations and equipment troubles.
• the unsteady mathematical model according to the present invention takes into account the effects of the molten liquid level, making it possible to learn operational procedures in response to changes in the molten liquid level that could not be reproduced with conventional calculation models.
• the information processing device 10 executes the unsteady mathematical model in accordance with the boundary conditions of the selected blast furnace and case study.
• the boundary conditions and internal variables either maintain constant values or change according to a pattern preset for each case study.
• the input and output items of the unsteady mathematical model are displayed sequentially in a graph within a user interface screen, such as that shown in Figure 10, and are updated at predetermined time intervals.
• the trainee should be able to select the input or output items to be displayed in the graph within the user interface screen.
• the trainee can also input operational control items and their operation amounts at any time within the calculation period into an operation screen, such as that shown in Figure 11, to reflect the input conditions in the unsteady mathematical model.
• Examples of operational control items include the coke ratio, blast volume, blast temperature, and the distribution of the ore coke ratio in the charging materials, which are items operated by operators in actual blast furnace operations.
• the unsteady mathematical model uses the state inside the furnace at the time the trainee inputs the operation as the initial condition, and the value reset based on the input operation value for the operation item as the boundary condition, and performs recalculation from the time the operation value is input. By displaying the results before and after recalculation on the same graph, trainees can learn about the impact of operational controls on blast furnace operation.
• a blast furnace with an internal volume of 5,000 m3 is used as the target, and a case is shown in which pulverized coal injection equipment trouble occurs, causing pulverized coal injection to stop one hour after the start of the calculation.
• the specifications are set so that the oxygen injection amount is set to 0 when pulverized coal injection stops, in line with the equipment specifications of an actual blast furnace.
• Example calculation results for the base and cases 1 to 4 are shown in Table 1.
• the blast furnace operation prediction method according to the present invention is intended to be used for the purpose of operation design, not for training trainees on operational fluctuations, and can also be used for blast furnace operation design that prevents operational fluctuations and equipment troubles.
• an operation designer inputs the operation control items and their operation amounts on behalf of the trainee and performs recalculation multiple times. Then, assuming a case such as start-up operation of a blast furnace after a long period of shutdown, the operation amount of the operation control items is repeatedly adjusted so that the recalculated blast furnace operation parameters and/or monitoring information approach the target results, thereby performing blast furnace operation design.
• FIG. 12(a)-(c) show the time-dependent changes in blast flow rate, coke ratio, and silicon concentration in molten pig iron.
• the solid lines and plots represent actual values
• the dashed lines represent planned values or values calculated using a mathematical model
• the dashed-dotted lines represent target values.
• the silicon concentration in molten pig iron is removed in the subsequent steelmaking process.
• the present invention provides a method for predicting blast furnace operation that can accurately predict the state of a blast furnace by taking into account the effects of molten material present in the basin.
• the present invention also provides a method for training in blast furnace operation and a terminal device that can improve blast furnace operation techniques.
• the present invention also provides a method for designing blast furnace operation and a terminal device that can reduce operational fluctuations and equipment troubles.

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