JPS60262909A - Operating method of blast furnace - Google Patents

Abstract

PURPOSE:To keep the Si concn. in the tapped molten iron and the temp. of the molten iron within specified limits by regulating the amt. of iron oxide, fuel, etc. to be blown in accordance with the difference in Si concn. between desired concn. and the Si concn. in molten iron in the dripping zone and the Si concn. in molten iron at every tapping hole. CONSTITUTION:In the operation of a blast furnace 1 wherein iron oxide in a tank 2 is blown in from a blast tuyere 5, the Si concn. in molten iron in a dripping zone above the tuyere 5 level is measured by sampling probes 20 provided at the abdominal part of the blast furnace 1 at every tapping hole 19 in the circumferential direction. The Si concn. in molten iron at every tapping hole 19 is also measured, and the measured value is inputted to arithmeric units 11 and 12 wherein said concn. is compared with a desired Si concn. to obtain the difference. The amt. of iron oxide to be blown in from each blast tuyere 5 is changed at every direction of each tapping hole 19 in accordance with said difference through flow-rate regulating valves 3, 7, and 9 and flowmeters 4, 8, and 10, and the amt. of fuel and steam to be blown in the direction of the corresponding tapping hole is regulated in accordance with said blown-in amt. Consequently, the Si concn. in molten iron tapped from the blast furnace 1 and the temp. of molten iron are kept within specified limits, and the descending of the load is stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a blast furnace operation method in which iron oxide is injected into a blast furnace from a blast tuyere to control the Sl concentration in hot metal. The present invention also relates to a blast furnace operating method that accurately controls hot metal temperature and stabilizes unloading.

Prior art and its problems 51 migration into hot metal in a blast furnace is mediated by SiO gas rather than the sulfur metal reaction in the hearth steaming area, but the molten metal A/reaction plays a major role.

The transfer of 81 into hot metal via SiO gas can be roughly divided into the following two processes (iron and steel vol. 1.5F 3.19
72219 pages).

That is, ①Sin whose main source is ash in the coke in the high temperature, low oxygen partial pressure region near the raceway.

The generation process of SIO gas by the reaction between the solid carbon in the coke and the reaction between the SlO gas contained in the ascending gas flow below the softening cohesive zone and the carbon in the dripping hot metal. This is a transition process, and the reaction equations for both processes are as follows.

■(Sin, ) + C= 5io(y)+00(
f)■5lO(f) + C=di+oo (p) Here, () is the conventional notation to indicate that the compound is present in the slag, and F- in the element name indicates that the component is present in the hot metal. This is a common notation that indicates the existence of . Furthermore, <y) is a common notation indicating that the compound is a gas.

Therefore, methods for controlling the Sl concentration in hot metal include controlling the SiO gas generation reaction and controlling the 81 transfer reaction into the hot metal.

In actual blast furnace operation, the former control means include controlling the ash content in the coke to bring Sin in before the tuyere, controlling the amount, and controlling the SiO gas generation rate by controlling the tuyere 1ff/M degrees. There is. The latter control means include cohesive zone level management by coke ratio control based on charge distribution control and calcination 4ii! There is control of the cohesive zone level by controlling the reducibility and softening trend properties of I ore (pig and steel v
o/, 68 1982 A129 page).

As a method of controlling the SI concentration in hot metal, in addition to the above-mentioned control method based on a separate transfer mechanism into the hot metal in the blast furnace, iron oxide is blown into the furnace from the blast tuyeres, and the following reaction A so-called in-furnace desiliconization means for oxidizing Sl in hot metal has been developed (JP-A-53-87908, JP-A-56-29601, JP-A-58-77508).

■SI + 2FeO = (SIO,) + 2Fe In the case of this control means, if the above reaction is properly controlled, it is possible to control the Si degree immediately before tapping, and the sig degree in the hot metal can be easily managed. .

However, conventional SI in hot metal by injection of iron oxide
The concentration control method had the following drawbacks.

First of all, iron oxide is injected into the furnace using a method that maintains the flow rate per unit time at a constant value, but in actual operation, there are unpredictable changes in the physical and chemical properties of the charge. Due to disturbance factors such as an abnormality in the fall of the burden in the furnace, the white-skinned gas flow distribution and the temperature distribution of gas and solids change and the cohesive zone level fluctuates.
Although the lk degree changes, the amount of SI in the hot metal oxidized by the iron oxide that is evenly injected into each tuyere is almost constant, so the SI concentration in the hot metal discharged from the blast furnace fluctuates. .

The second problem is that the amount of iron oxide blown into the furnace is not managed at each blowing tuyere, but is managed based on the total amount blown into the furnace. In other words, in normal iron oxide injection operations, in the case of sudden injection, iron oxide is injected at an equal amount from the tuyeres divided into equal parts in the circumferential direction, and in the case of large-volume injection, iron oxide is injected into all the tuyeres. However, the piping is designed so that the amount of air injected from each tuyere is the same, and the total flow rate is controlled using the iron oxide injection flow Ik company collective piping. do not have. However, with this method, the refractory wears unevenly in the circumferential direction at the end of the life of the blast furnace, deposits are formed unevenly in the circumferential direction, or the charging If the material is eccentrically charged into the furnace or if the rate of descent of the charge is uneven in the circumferential direction of the trench, the 5ifi degree in the hot metal dripping onto the hearth may be The disadvantage is that it varies depending on the direction.

In addition, as a method for alleviating the variation in Si concentration by tap day when iron oxide is not injected, a method has been proposed in which the amount of fuel injected from the taphole direction is adjusted (Japanese Patent Application Laid-Open No. 58-117805).

Regarding iron oxide injection, as mentioned above, under the circumstances where the Sl concentration in the hot metal dripping into the hearth varies in the circumferential direction, iron oxide injection was carried out evenly in the circumferential direction as in the past. This causes variations in the Si concentration in the hot metal discharged from each outlet.

Furthermore, if iron oxide injection is carried out in the circumferential direction, there is a problem in that the heat puff and material balance in the circumferential direction of the lower part of the furnace will be disturbed. In other words, the iron oxide injected from the tuyere is
This reaction oxidizes Sl in the hot metal, which is the so-called in-furnace desiliconization action, and at the same time, a portion of the sulfur is directly reduced by the solid carbon in the coke in the coke zone at the tip of the raceway through the reaction (2) below.

■FeO+ C= Fe + Co(f) The above reaction is an endothermic reaction, and especially when the deviation in the amount of iron oxide injected in the circumferential direction is increased, the heat puff in the circumferential direction in the lower part of the furnace will be destroyed. As the dispersion of hot metal temperature increases, it also affects unloading conditions in the circumferential direction through the heat flow ratio (solid heat capacity flow rate/gas heat capacity flow rate), causing deterioration of furnace conditions such as slipping and tuyere breakage. There is a risk of triggering.

Purpose of the Invention This invention was made to solve the above-mentioned problems of the prior art, and utilizes the fact that iron oxide can be injected separately for each direction of the taphole to reduce the sl concentration in the hot metal discharged from the blast furnace. The purpose of this paper is to propose a method for operating a blast furnace that maintains the temperature within a predetermined range, reduces variations in hot metal temperature, and stabilizes unloading.

Structure and operation of the invention The method of operating a blast furnace according to the present invention includes: controlling the concentration of Sl in the hot metal in the dripping zone in the furnace above the level of the tuyere in each circumferential direction of the exit port;
The Sl concentration in the hot metal is actually measured for each tap date, and the oxidation from the blast tuyere is By changing the iron injection amount for each gun outlet direction and further adjusting the fuel injection amount or steam injection amount for the relevant gun outlet direction according to the iron oxide injection amount, iron is tapped from the blast furnace. It is characterized by maintaining the concentration of 51 in the hot metal and the temperature of the hot metal within a certain range.

That is, in the current blast furnace operation, fluctuations in the condition inside the furnace due to disturbance factors and non-uniformity in the condition inside the furnace in the circumferential direction inevitably occur. Collect and analyze the dripping hot metal above the tuyere level for each exit direction.
desiliconization oxygen efficiency (injected iron oxide At the same time, the sl concentration in the hot metal is controlled by feedback control of the amount of iron oxide injected from the blowing surface in the taphole direction based on the ratio of the amount of oxygen in the hot metal and the amount of oxygen used for desiliconization. This is a method of suppressing the variation in hot metal temperature depending on the tapping date by adjusting the fuel injection amount or steam injection amount in the circumferential direction as thermal compensation according to the iron oxide injection amount. .

The method of this invention will be explained below based on the drawings.

Figure 1 shows the equipment configuration for carrying out the method of the present invention. Iron oxide is injected into the blast furnace (1) from an iron oxide storage tank (2) through a flow control valve (3) and a flow meter (4). ) and is blown into the furnace from a separate air outlet (5). On the other hand, the auxiliary fuel storage tank (6) K is also equipped with a flow control valve (7) and a flow meter (8), and the main flow control valve (
9) A flow meter OG is installed. Although not shown, the flow control valve +31 (71 (9) and the flow meter (4)
) f8) αQ is installed at each ventilation outlet. A plurality of iron oxide storage tanks (2) are installed in each direction of the taphole, corresponding to the number of tapholes or more than the number of tuyeres.

The Sl concentration in the hot metal on each tapping day is determined by sampling and analyzing the hot metal slag several times from each tap at each tap hole O1. In addition, the Sl concentration in the hot metal in the dripping zone above the tuyere level can be determined by inserting a hot metal slag sampling probe ■ into the furnace from the furnace belly or morning glory section at each exit direction. The hot metal slag at 1'v) was sampled at several points in the radial direction and analyzed. Note that the latter measurement of draw concentration is carried out semi-continuously, regardless of the tapping timing in the direction. A rapid analysis method such as emission spectrometry is used to measure the 81 concentration in hot metal.

Then, the St concentration in the hot metal above the tuyere level and at the taphole obtained by this pressure and the current iron oxide injection amount in the relevant direction are input to the calculator αB, and the current desiliconization oxygen efficiency is calculated. Based on this value, the amount of iron oxide injected required for each exit direction is determined according to the difference between the Sl concentration measurement value at the hot metal slag sampling probe, which is input semi-continuously, and the target 5IIs degrees. is calculated, and the opening degree of the flow rate control valve (3) is adjusted with reference to the actual measured value of the current injection amount.

At the same time, the adjustment of the fuel injection amount or steam injection amount necessary for heat compensation corresponding to the iron oxide injection trap is performed using the calculator @, which calculates the heat balance at the tuyere level based on the above iron oxide injection amount. - Calculates the amount of fuel or steam injected necessary for heat compensation by calculating the material balance, and controls the opening of the flow rate control valve (7) or (9) in the relevant direction.

The target S1 concentration can be manually input via the input data setting device (11), or calculated based on the blast furnace exhaust gas data (to), charge data (0), ventilation data (to), and tapping data ae. Mathematical simulation V model IV built into the container (2) (e.g. Tetsu to Hagane VO/, 68 1982 A1
(page 29) and can be automatically input continuously.

Next, we will explain how to understand the desiliconization and oxygen efficiency by injecting iron monoxide into K.

The desiliconization oxygen efficiency is expressed as the ratio of the amount of oxygen in the iron oxide that contributed to the desiliconization reaction (1) to the oxygen in the iron oxide blown into the furnace, and its value is defined by the following equation 0.

Wp -ore -y ji(jz-riqi 虻ii1*中l
U: Desilication oxygen efficiency Wplg: Amount of pig iron tapped from the relevant taphole Wp - 岨1 Amount of iron oxide injected from the tuyere in the relevant taphole direction Xf: 2 SI concentration in hot metal at the relevant taphole y: Oxidation Oxygen fraction mo in Chichichi: Molecular weight of oxygen m, I: Molecular weight of silicon tap Then, the desiliconization and oxygen efficiency U is calculated by taking the average value of each measured value.

The computer calculates the desiliconization oxygen efficiency and the iron oxide injection adjustment amount according to the flowchart shown in FIG. 2. That is, the sl concentration in the hot metal of the nearest tap measured as described above for each taphole and the 81/! 1
Input the degree and calculate the silicon removal oxygen efficiency using the above formula 0.

Next, based on the silicon removal efficiency of this core, the amount of iron oxide injected is calculated according to the difference between the 81 concentration in the hot metal and the 4Si concentration in the hot metal above the tuyere level, which is measured semi-continuously, The adjusted amount of iron oxide injection is calculated based on the current amount of iron oxide injection.

On the other hand, the required fuel injection amount or steam injection amount is calculated at the one-tuyere level based on the desiliconization oxygen efficiency and the iron oxide injection amount calculated from the formula 0. It is calculated by calculating the heat balance and material balance of , and calculating the required amount of heat compensation.

Figure 3 shows that during period a (50 days) of blast furnace A (inner volume 270M), the amount of iron oxide injected was controlled by the above-mentioned method of the invention, and as a corresponding heat compensation, the amount of steam injected was This shows the change in hot metal temperature when adjusting . Note that calculations can be made in the same way when the amount of fuel injection is adjusted as a heat compensation means accompanying the injection of iron oxide. The relationship illustrated in Fig. 3 is built into the calculator@, and when the iron oxide injection amount calculated from the calculator and the desiliconization oxygen efficiency at that time are input, the thermal compensation is determined by K. The necessary adjustment amount of fuel injection amount or steam injection amount is calculated, and the opening degree of the flow rate adjustment valve (7) or (9) in the relevant taphole direction is controlled.

Example A The results of implementing this invention in a blast furnace (inner volume 2700 rIe) are shown in FIG. 4 and Table 1. FIG. 4 shows changes in the temperature and concentration of hot metal discharged from the N&2 taphole of the blast furnace for each tap.

That is, in the period before the application of the method of this invention (without iron oxide injection), the St concentration in the melt gun was high, and the puffiness (σ duck was also large at 0.16%) at each tap.
In order to lower the average 51 concentration level of all the tap holes (NLI~\3) to 0.10% and reduce the drawn concentration deviation by tap date, the average SI concentration level at the relevant tap hole was set to A10.
．． In order to reduce the temperature to 10%, the injection of iron oxide from the blast tuyere was started, and at the same time, according to the method of this invention, the dripping hot metal was collected at the level of the siding 11 [) at each outlet direction,
The St concentration in the hot metal is quickly analyzed by optical emission spectrometry, and the 5lfi degree in the hot metal discharged from each gun port is also quickly analyzed using a concentration battery, which is input into a calculator 1 to calculate the desiliconization and oxygen efficiency at that time. Based on this value, the fluctuation behavior of the 81 concentration in the dripping zone hot metal, which is semi-continuously measured and inputted at a level just above the 1 day level, can be quickly grasped, and the fluctuation behavior of the 81 concentration in the dripping zone hot metal can be determined according to the difference from the target 81 concentration. As a result of adjusting the amount of iron oxide injected from each siding and at the same time adjusting the amount of steam blown from each siding as heat compensation, we found that 51! The average Si concentration decreased by 0.09%, almost meeting the target value, and the St @ degree fluctuation range (#3i) was also suppressed to 0.08%, while the fluctuation in hot metal temperature - (at\)ig) was also suppressed. I didn't get stupid.

In addition, Table 1 shows the changes in the average level of St concentration in hot metal and the average hot metal temperature by tapping date during the period shown in Figure 4, and the bubbly table of 81 concentrations in hot metal between each tapping port.
Control of average concentration level at taphole and Sl/1
The effect of reducing the range of temperature fluctuations is also seen at Otori No. 1 and No. 13 tapholes, and as a result, the Sl in the hot metal between each taphole is
The density buffiness (T, H #st Di) could be reduced.

(The following is a blank space) Effects of the Invention As is clear from the above examples, according to the present invention, the Si concentration in hot metal can be calculated by tapping date! ! At the same time, a sampling probe is inserted from the blast furnace belly or morning glory part to analyze the SI concentration in the dripping zone hot metal above the tuyere level, and based on both SI concentration values and the target 81 concentration, Adjust the amount of iron oxide injected from the tuyere in the direction, and at the same time (adjust the amount of fuel or steam injected in the direction of the taphole in accordance with the iron oxide injection tK as thermal compensation). Since the temperature of hot metal tapped from the blast furnace under stable downflow can be controlled within a certain range, it has a great effect on stabilizing the furnace conditions.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of an apparatus for carrying out the method of this invention, Fig. 2 is a flowchart showing a control method for iron oxide injection in the method of this invention, and Fig. 3 is the amount of iron oxide blown in J:. Fig. 4 is a chart showing the relationship between the amount of steam injection and the adjusted amount of steam injection and the tapping temperature, and Fig. 4 is a chart showing the change transition of the St concentration in hot metal and the tapping temperature in an example of the present invention. 1...Blast furnace, 2...Iron oxide storage tank, 3,7
．． 9...Flow rate control valve, 4,8.10...Flow meter, 5...Blow tuyere, 6...Auxiliary fuel storage tank, 11.12...Calculator, 13... Exhaust gas data, 14... Charge data, 15... Air blowing data, 16... Tapping data, 18... Input data setting device, 19... Gun outlet, 20...Hot metal slag sampling probe. Fig. 1 14 Character data Fig. 2 Fig. 3 JP14 Fig. Period b ° Period C

Claims (1)

[Claims] In the blast furnace operation method in which iron oxide is blown into the blast furnace from the blast tuyere, the Sl concentration in the hot metal in the dripping zone above the tuyere Vbep in each circumferential direction of the gun exit direction, and the 5 lfi degree in the hot metal for each gun exit date. was actually measured, and the amount of iron oxide injected from the blast tuyeres was determined for each outlet direction according to the difference between the target Sl concentration and the S1 concentration in the hot metal above the grain level and the Si concentration in the hot metal by tapping date. By changing the amount of iron oxide injected and further adjusting the amount of fuel injected or the amount of steam injected in the taphole direction according to the amount of iron oxide injected, the Si concentration in the hot metal tapped from the blast furnace and the hot metal temperature can be kept within a certain range. A method of operating a blast furnace characterized by maintaining