Patent Application
20240368715
The present invention relates to a supply heat quantity estimating method, a supply heat quantity estimating device, a supply heat quantity estimating program, and a blast furnace operating method for estimating the quantity of heat supplied to pig iron in a blast furnace.
Generally, in order to stably operate a blast furnace, it is necessary to maintain the molten iron temperature within a predetermined range. Specifically, when the molten iron temperature becomes low, the viscosity of the molten iron and slag generated together with the molten iron increases, and it becomes difficult to discharge the molten iron or the slag from a tap hole. On the other hand, when the molten iron temperature becomes high, the Si concentration in the molten iron increases, and the viscosity of the molten iron increases, and thus there is a high risk that the molten iron sticks to a tuyere and melts the tuyere. Therefore, in order to stably operate a blast furnace, it is necessary to suppress the fluctuation of the molten iron temperature. From such a background, various methods for estimating the quantity of heat supplied into a blast furnace or the molten iron temperature are proposed. Specifically, Patent Literature 1 discloses a furnace heat controlling method for a blast furnace, in which the molten iron temperature after a specific period of time is sequentially estimated from a displacement amount in a furnace heat index at the current time from a furnace heat index reference level corresponding to a target molten iron temperature, a displacement amount in a descending speed at the current time from a descending speed reference level of a furnace top corresponding to the target molten iron temperature, and time of influence of both of the displacement amounts to the molten iron temperature, and furnace heat control operation is performed so as to reduce fluctuations in the molten iron temperature based on the estimation result. In addition, Patent Literature 2 discloses a molten iron temperature estimating method for a blast furnace for estimating a future molten iron temperature based on operation data including an actual value of blast condition data including at least one of a blast temperature, a blast humidity, a blast volume, a pulverized coal blowing amount, or an oxygen enrichment amount in the blast furnace, an actual value of disturbance factor data including at least a solution loss carbon amount, and an actual value of the molten iron temperature, the method including: a data accumulation step of accumulating the operation data; a stationary state estimation model constructing step of constructing a stationary state estimation model for estimating a molten iron temperature in a stationary state from the operation data in the stationary state accumulated in the data accumulation step; a non-stationary state estimation model constructing step of constructing a non-stationary state estimation model for estimating a molten iron temperature in a non-stationary state from the operation data in the non-stationary state accumulated in the data accumulation step, the non-stationary state estimation model obtained by reducing dimensions of the stationary state estimation model; and a molten iron temperature estimating step of estimating a molten iron temperature from the stationary state estimation model and the non-stationary state estimation model that have been constructed.
The timing at which the molten iron temperature is highly likely to greatly fluctuate is when the quantity of molten iron produced changes due to a change in the rate of operation such as the blast volume in a blast furnace, and the quantity of pig iron changes with respect to the quantity of heat supplied into the blast furnace. In particular, the molten iron temperature greatly fluctuates when a so-called slip occurs in which the raw material stops descending due to the force of gas pushing up the raw material in the blast furnace exceeding the descending force of the raw material and then the height of the raw material surface rapidly drops when this relationship is canceled. However, since the method described in Patent Literature 1 does not take into consideration factors such as carried-out sensible heat by blast sensible heat, which is considered to change due to an increase or decrease in the rate of operation, it is not possible to accurately estimate the quantity of heat supplied to pig iron when the rate of operation is greatly changed. In addition, in the method described in Patent Literature 2, it is conceivable that the estimation accuracy of the molten iron temperature decreases when an operation change that has not been accumulated previously is performed. In addition, in a case where the estimation accuracy of the molten iron temperature is low as described above, there are many cases where the heat is excessively supplied, which brings about concerns about equipment trouble. Meanwhile, excessive use of a reducing material, which is a carbon source, is not preferable also from the perspective of reducing carbon dioxide emissions.
The present invention has been made in view of the above disadvantages, and an object of the present invention is to provide a supply heat quantity estimating method, a supply heat quantity estimating device, and a supply heat quantity estimating program capable of accurately estimating the quantity of heat supplied to pig iron in a blast furnace even when the rate of operation greatly changes and, especially, when a slip occurs. Another object of the present invention is to provide a blast furnace operating method capable of accurately controlling the molten iron temperature within a predetermined range while maintaining the quantity of heat supplied to the pig iron in the blast furnace to an appropriate amount even when the rate of operation greatly changes and, especially, when a slip occurs.
A supply heat quantity estimating method according to the present invention estimates a quantity of heat supplied to pig iron in a blast furnace from a quantity of heat supplied into the blast furnace and a production speed of molten iron in the blast furnace, and includes: an estimating step of estimating a change in carried-out sensible heat by in-furnace passing gas and a change in carried-in sensible heat supplied by a raw material preheated by the in-furnace passing gas, and estimating a quantity of heat supplied to the pig iron in the blast furnace in consideration of the changes in the carried-out sensible heat and the carried-in sensible heat that have been estimated, wherein the estimating step includes: a step of estimating the carried-out sensible heat in consideration of the quantity of heat released to an outside of the blast furnace by a slip, and estimating the change in the carried-in sensible heat in consideration of a change in a surface height of the raw material by the slip; and a step of estimating a quantity of heat held in a deadman coke present in the blast furnace, and estimating the quantity of heat supplied to the pig iron in the blast furnace in consideration of the quantity of heat held in the deadman coke that has been estimated.
Moreover, the estimating step may include a step of estimating the carried-out sensible heat in consideration of the quantity of heat released to the outside of the blast furnace by the slip by calculating a multiplied value by multiplying specific heat of furnace top gas by a difference between a furnace top gas temperature and a reference temperature of the furnace top gas temperature and adding a value obtained by dividing the multiplied value by an ironmaking speed to the carried-out sensible heat.
Moreover, the estimating step may include a step of estimating the change in the carried-in sensible heat in consideration of the change in the surface height of the raw material due to the slip by obtaining a raw material temperature as a function of an integrated value of a difference between an estimated value and an actual value of the surface height of the raw material.
A supply heat quantity estimating device according to the present invention estimates a quantity of heat supplied to pig iron in a blast furnace from a quantity of heat supplied into the blast furnace and a production speed of molten iron in the blast furnace, and includes: an estimating unit configured to estimate a change in carried-out sensible heat by in-furnace passing gas and a change in carried-in sensible heat supplied by a raw material preheated by the in-furnace passing gas, and estimate a quantity of heat supplied to the pig iron in the blast furnace in consideration of the changes in the carried-out sensible heat and the carried-in sensible heat that have been estimated, wherein the estimating unit is configured to estimate the carried-out sensible heat in consideration of the quantity of heat released to an outside of the blast furnace by a slip, estimate the change in the carried-in sensible heat in consideration of a change in a surface height of the raw material by the slip, estimate a quantity of heat held in a deadman coke present in the blast furnace, and estimate the quantity of heat supplied to the pig iron in the blast furnace in consideration of the quantity of heat held in the deadman coke that has been estimated.
A supply heat quantity estimating program according to the present invention causes a computer to execute a process of estimating a quantity of heat supplied to pig iron in a blast furnace from a quantity of heat supplied into the blast furnace and a production speed of molten iron in the blast furnace, the supply heat quantity estimating program causing the computer to execute an estimating process of: estimating a change in carried-out sensible heat by in-furnace passing gas and a change in carried-in sensible heat supplied by a raw material preheated by the in-furnace passing gas and estimating a quantity of heat supplied to the pig iron in the blast furnace in consideration of the changes in the carried-out sensible heat and the carried-in sensible heat that have been estimated, wherein the estimating process includes: estimating the carried-out sensible heat in consideration of the quantity of heat released to an outside of the blast furnace by a slip, estimating the change in the carried-in sensible heat in consideration of a change in a surface height of the raw material by the slip, estimating a quantity of heat held in a deadman coke present in the blast furnace, and estimating the quantity of heat supplied to the pig iron in the blast furnace in consideration of the quantity of heat held in the deadman coke that has been estimated.
A blast furnace operating method according to the present invention includes: a step of controlling the quantity of heat supplied into the blast furnace based on the quantity of heat supplied to the pig iron in the blast furnace estimated by the supply heat quantity estimating method according to the present invention.
According to a supply heat quantity estimating method, a supply heat quantity estimating device, and a supply heat quantity estimating program according to the present invention, it is possible to accurately estimate the quantity of heat supplied to pig iron in a blast furnace even when the rate of operation greatly changes and, especially, when a slip occurs. In addition, according to a blast furnace operating method according to the present invention, it is possible to maintain the quantity of heat supplied to the pig iron in the blast furnace to an appropriate amount and to accurately control the molten iron temperature within a predetermined range even when the rate of operation greatly changes and, especially, when a slip occurs.
Hereinafter, a configuration and operation of a furnace heat controlling device as an embodiment of the present invention to which a supply heat quantity estimating method and a supply heat quantity estimating device according to the present invention are applied will be described with reference to the drawings.
First, with reference to
The furnace heat controlling device 1 having such a configuration accurately estimates the quantity of heat supplied to pig iron in the blast furnace 2 even when the rate of operation of the blast furnace 2 greatly changes and, especially, when a slip occurs, by execution of the furnace heat controlling process described below, maintains the quantity of heat supplied to the pig iron in the blast furnace 2 at an appropriate amount using the estimation result, and accurately controls the molten iron temperature within the predetermined range. Hereinafter, a flow of the furnace heat controlling process as an embodiment of the present invention will be described with reference to
The operation of the furnace heat controlling device 1 described below is implemented by an arithmetic processing device, such as a CPU in the information processing device included in the furnace heat controlling device 1, loading a program 1a from a storage unit such as a ROM to a temporary storage unit such as a RAM and executing the program 1a that has been loaded. The program 1a may be provided by being recorded in a computer-readable recording medium such as a CD-ROM, a flexible disk, a CD-R, or a DVD as a file in an installable format or an executable format. The program 1a may be stored in a computer connected to a network such as a telecommunication line such as the Internet, a telephone communication network such as a mobile phone, or a wireless communication network such as WiFi (registered trademark), and provided by being downloaded via the network.
In the process of step S2, the furnace heat controlling device 1 estimates sensible heat (gas-carried-out sensible heat) Q7 carried out to an upper portion of the blast furnace 2 by gas (in-furnace passing gas) passing from a lower portion to the upper portion of the blast furnace 2. Specifically, the gas-carried-out sensible heat Q7 (MJ/t-p: amount of heat per ton of pig iron. Hereinafter, t-p represents pig iron tonnage) can be calculated by (1) calculating a first multiplied value by multiplying a temperature difference between an estimated temperature (theoretical combustion temperature) of gas combusted in front of a tuyere and a reference temperature representing the temperature at an upper end of the lower portion of the blast furnace by the specific heat of the gas, (2) calculating a second multiplied value by multiplying the specific heat of furnace top gas by a difference between the furnace top gas temperature (temperature of furnace top exhaust gas) and a reference temperature of the furnace top gas temperature, and (3) dividing a value obtained by adding the first multiplied value and the second multiplied value by an ironmaking speed, and this is expressed by the following Equation (1). By dividing the value obtained by adding the first multiplied value and the second multiplied value by the ironmaking speed, it is possible to accurately evaluate the gas-carried-out sensible heat Q7 in consideration of the quantity of heat released to the outside of the furnace without exchanging heat with the raw material by a slip. As a result, the process of step S2 is completed, and the flow proceeds to the process of step S5.
Where Cbosh, i denotes the specific heat (MJ/m3/° C.) of a gas species i (nitrogen, carbon monoxide, and hydrogen) in the in-furnace passing gas (Bosch gas), Ctop, i denotes the specific heat (MJ/m3/° C.) of a gas species i (nitrogen, carbon monoxide, carbon dioxide, hydrogen, and water vapor) in the furnace top gas, Vbosh, i denotes the flow rate (m3 (s.t.p)/min) (m3 (s.t.p): volume at 0° C. and 1 atm (atmospheric pressure)) of the gas species i in the in-furnace passing gas, Vtop, i denotes the flow rate (m3 (s.t.p)/min) of the gas species i in the furnace top gas, TFT denotes the theoretical combustion temperature (° C.), Tbase denotes the reference temperature (° C.) (800 to 1200° C., preferably 900 to 1000° C.), Ttop denotes the furnace top gas temperature (° C.), Ttop, base denotes the reference temperature (° C.) of the furnace top gas temperature (80 to 300° C., preferably 100 to 200° C.), Pig denotes the ironmaking speed (t-p/min), and @bosh and @top denote influence coefficients that are modified depending on the blast furnace 2. These values can be acquired from a host computer 3 such as a process computer connected to the furnace heat controlling device 1 via a telecommunication line, for example.
In the process of step S3, the furnace heat controlling device 1 estimates sensible heat (raw-material-carried-in sensible heat) Q8 carried in to the lower portion of the blast furnace 2 by a raw material supplied from the upper portion to the lower portion of the blast furnace 2. Specifically, the material-carried-in sensible heat Q8 (MJ/t-p) can be calculated by multiplying a temperature difference between the raw material temperature T1 (=1450 to 1500° C.) at a lower end of a cohesive zone and a reference temperature Tbase by the specific heat of the raw material as expressed by the following Equation (2). Note that the raw material temperature T1 is a function of the differential value of the difference ΔLsurface between the estimated value and the actual value of the raw material surface height as in Equation (3) below. According to the setting of the raw material temperature T1, it is possible to consider that the raw material temperature T1 decreases depending on the magnitude of the surface height of the raw material that has slipped, and thus it is possible to accurately evaluate a decrease in the quantity of heat carried into the lower part of the furnace by the raw material that is not heated well due to a slip.
Specifically, in a normal operation situation, since the volumes of the raw material and the coke in the blast furnace decrease depending on the ironmaking speed, the surface height of a packed bed of the raw material in the blast furnace decreases. Here, the surface height of the packed bed of the raw material is measured using a sensor, and an operation of replenishing the raw material and the coke to bring the surface height of the packed bed of the raw material to the original height is repeatedly performed each time the surface height of the packed bed of the raw material descends to a predetermined height. Meanwhile, immediately before the slip occurs, the volume of the raw material in the blast furnace itself decreases depending on the ironmaking speed, however, the descent of the raw material is inhibited at a certain position, and thus the surface height of the packed bed of the raw material is constant or only slightly descends. Therefore, by always obtaining the difference ΔLsurface between the surface height of the packed bed of the raw material estimated from the ironmaking speed and a sensor measurement value, since a change amount dΔLsurface/dt when the difference is rapidly reduced represents the slip amount, and the influence of the raw material not heated well due to the slip can be evaluated depending on the magnitude of the quantity of the slip. It is also possible to perform similar evaluation by always simply measuring the amount of change in the surface height of the packed bed of the raw material and deeming that a slip has occurred when the amount exceeds a threshold value. Note that, in a case where there is a plurality of measurement directions of the surface height of the packed bed of the raw material, similar evaluation may be performed for each of the measurement directions, and the influence may be proportionally obtained depending on the ratio of the measurement direction in which the slip has occurred, or the slip may be evaluated using the average value of the measurement directions. As a result, the process of step S3 is completed, and the flow proceeds to the process of step S5.
Here, Cj denotes the specific heat (MJ/kg/° C.) of a raw material j (coke, pig iron, and slag), Rj denotes an intensity (kg/t-p) of the raw material j, T1 denotes the raw material temperature (° C.) at the lower end of the cohesive zone, Tbase denotes the reference temperature (° C.), and β denotes an influence coefficient modified depending on the blast furnace 2. These values can be acquired from, for example, the host computer 3.
In the process of step S4, the furnace heat controlling device 1 estimates the quantity of heat (coke holding heat quantity) Q9 held in the deadman coke present in the lower portion of the blast furnace 2. Specifically, the coke holding heat quantity Q9 (MJ/t-p) can be obtained by multiplying a value obtained by subtracting a combustion consumption amount and a carbon amount discharged as dust from the coke intensity per ton of molten iron by a difference between a reference temperature and a theoretical combustion temperature and the specific heat Ccoke of coke and is expressed by the following Equation (4). As a result, the process of step S4 is completed, and the flow proceeds to the process of step S5.
Incidentally, Coke denotes the specific heat of coke (MJ/kg/° C.), TFT denotes the theoretical combustion temperature (° C.), Tbase denotes the reference temperature (° C.), CR denotes a coke ratio (kg/t-p), CRburn denotes a combustion carbon ratio in front of the tuyere (amount of oxygen consumed in front of the tuyere by blown oxygen and humidification) (kg/t-p), PCR denotes a pulverized coal ratio (kg/t-p), Cinpc denotes a carbon ratio in pulverized coal, Csol denotes a solution loss carbon ratio (kg/t-p), Dust denotes a dust ratio (kg/t-p), Cindust denotes a carbon ratio in dust, and γ and δ denote influence coefficients modified depending on the blast furnace 2. These values can be acquired from, for example, the host computer 3.
In the process of step S5, the furnace heat controlling device 1 estimates the quantity of heat supplied to the pig iron in the blast furnace 2 using the supply heat quantity Q0 estimated in the process of step S1, the gas-carried-out sensible heat Q7 estimated in the processes of steps S2 to S4, the material-carried-in sensible heat Q8, and the coke holding heat quantity Q9. Specifically, the furnace heat controlling device 1 calculates a furnace heat index TQ (MJ/t-p) corresponding to the quantity of heat supplied to the pig iron in the blast furnace 2 by substituting the supply heat quantity Q0 estimated in step S1, the gas-carried-out sensible heat Q7 estimated in the process of steps S2 to S4, the material-carried-in sensible heat Q8, and the coke holding heat quantity Q9 into the following Equation (5). As a result, the process of step S5 is completed, and the flow proceeds to the process of step S6.
Incidentally, Q0 denotes the quantity of heat supplied into the blast furnace by the reaction heat balance (exothermic reaction heat and endothermic reaction heat), the blast sensible heat, the heat loss (e.g. the quantity of heat removed from the furnace body), and others in the blast furnace, and an estimation method adopted in many cases in the supply heat quantity estimation of the related art can be applied. As a preferable approach, Equation (6) is conceivable.
Incidentally, Q1 denotes the combustion heat (MJ/t-p) of coke at the tip of the tuyere. The combustion heat Q1 can be calculated by dividing a calorific value due to combustion of coke calculated from the amount of oxygen blown from the tuyere to the blast furnace per unit time by the amount of molten pig iron produced in the unit time.
Meanwhile, Q2 denotes blast sensible heat (MJ/t-p) supplied to the blast furnace by the blast from the tuyere. The blast sensible heat Q2 can be calculated by obtaining the quantity of heat input to the blast furnace by blast per unit time from the blast volume per unit time and a measured value of the blast temperature and dividing this value by the amount of molten pig iron produced in the unit time.
In addition, Q3 denotes solution loss reaction heat (MJ/t-p). For this value, for example, as described in Patent Literature 1, the reaction heat can be calculated by obtaining the solution loss carbon amount from component values of the furnace top gas. The solution loss reaction heat Q3 can be calculated by dividing the solution loss reaction heat by the amount of molten pig iron produced in the unit time.
Meanwhile, Q4 denotes heat of decomposition (MJ/t-p) of moisture contained mainly in the blast. The heat of decomposition Q4 can be calculated by dividing the heat of decomposition obtained from a measurement value of the blown moisture by the amount of molten pig iron produced in the unit time.
In addition, Q5 denotes a heat loss (for example, the quantity of heat removed by cooling water) from the furnace body (MJ/t-p). In a case where the quantity of heat removed by cooling water is calculated as the heat loss, the quantity of heat removed Q5 can be calculated by calculating the quantity of heat removed by the cooling water per unit time from the amount of the cooling water and a temperature difference between an inlet side and an outlet side of the cooling water of the blast furnace body and dividing the calculated amount of heat removed by the amount of molten pig iron produced in the unit time.
Q6 denotes the heat of decomposition (MJ/t-p) of a reducing material blown from the tuyere per unit time. The heat of decomposition Q6 can be calculated by dividing the heat of decomposition by the amount of molten pig iron produced in the unit time.
In the process of step S6, the furnace heat controlling device 1 controls the quantity of heat supplied from the tuyere into the blast furnace 2 based on the quantity of heat supplied to the pig iron in the blast furnace 2 estimated in the process of step S5, thereby maintaining the quantity of heat supplied to the pig iron in the blast furnace 2 at an appropriate amount and controlling the molten iron temperature within a predetermined range. As a result, the process of step S6 is completed, and a series of furnace heat controlling process ends.
As is apparent from the above description, in the furnace heat controlling process according to the embodiment of the present invention, the furnace heat controlling device 1 estimates a change in carried-out sensible heat to the upper portion of the blast furnace by the in-furnace passing gas and a change in carried-in sensible heat supplied to the lower portion of the blast furnace by the raw material preheated by the in-furnace passing gas and estimates the quantity of heat supplied to the pig iron in the blast furnace in consideration of the estimated changes in the carried-out sensible heat and carried-in sensible heat. In addition, the furnace heat controlling device 1 estimates the carried-out sensible heat in consideration of the quantity of heat released to the outside of the blast furnace by the slip, estimates the change in the carried-in sensible heat in consideration of the change in the surface height of the raw material by the slip, estimates the quantity of heat held in the deadman coke present in the blast furnace, and estimates the quantity of heat supplied to the pig iron in the blast furnace in consideration of the estimated amount of heat held in the deadman coke. This makes it possible to accurately estimate the quantity of heat supplied to the pig iron in the blast furnace even when the rate of operation such as the blast volume to the blast furnace greatly changes and, especially, when a slip occurs. In addition, this makes it possible to maintain the quantity of heat supplied to the pig iron in the blast furnace to an appropriate amount and to accurately control the molten iron temperature within a predetermined range even when the rate of operation greatly changes and, especially, when a slip occurs.
Illustrated in
Although the embodiments applied with the invention made by the present inventors have been described above, the present invention is not limited by the description and the drawings included as a part of the disclosure of the present invention according to the embodiments. That is, other embodiments, examples, operation technology, and the like implemented by those skilled in the art based on the present embodiments are all included in the scope of the invention.
According to the present invention, it is possible to provide a supply heat quantity estimating method, a supply heat quantity estimating device, and a supply heat quantity estimating program capable of accurately estimating the quantity of heat supplied to pig iron in a blast furnace even when the rate of operation greatly changes and, especially, when a slip occurs.
Another object of the present invention is to provide a blast furnace operating method capable of accurately controlling the molten iron temperature within a predetermined range while maintaining the quantity of heat supplied to the pig iron in the blast furnace to an appropriate amount even when the rate of operation greatly changes and, especially, when a slip occurs.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-106363 | Jun 2021 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2022/014446 | 3/25/2022 | WO |
