KR20000039471A - Method of controlling distribution of charging material into blast furnace - Google Patents

Abstract

PURPOSE: A method of controlling the distribution of a charging material into a blast furnace is provided to produce a new earthquake-proof index of a charging material by considering rotational frequency of a charging shoot and weight ratio between elementary and large sintered ore. CONSTITUTION: A charging ore is composed of elementary and large sintered ores and uses the weight ratio of the elementary sintered ore as weighted value. The temperature of a wall for a converter is measured with the earthquake-proof index and a vertical Sonde and proper management is performed to activate the wall portion of the converter with the temperature.

Description

Blast furnace loading distribution control method

The present invention relates to a blast furnace charge distribution control method, and in particular, in the blast furnace having a belly stop charging device to stabilize the blast furnace operation during charging operation to fill the ore and coke mixed with sintered ore with different particle sizes It relates to a method of controlling the distribution of the contents of the charge.

The charges used in the blast furnace are roughly divided into coke and ore, and the ore is usually divided into small sintered ores of 5 to 10 mm and alleles of about 10 to 50 mm, and the charging sequence is mainly coke → allele of sintered ore sintered ore. It is charged in the order of, in some cases, coke → small sintered or allele sintered.

These charges are filled from the top of the blast furnace with ore and coke mixed with sintered ores of different particle sizes in each blast furnace.

The layer thickening (ratio of layer thickness) in the radial direction of the filled ore and coke acts as the biggest factor in the distribution of gas flow in the blast furnace. When disturbance factors such as a poor loading condition or a poor loading drop occur and fluctuate in the layer thickness of the ore and coke, an area in which the ventilation resistance of the gas in the radial or circumferential direction increases is generated. Abnormal gas flow appears. When such an abnormal gas flow occurs, the amount of blowing is reduced due to the increase in the blowing pressure, and thus the production is reduced, and the fuel cost is increased because proper reduction or heat transfer is not performed.

Since the blast furnace is close to a cylindrical container, the volume of the charge close to the furnace wall portion occupies a large portion of the total contents. In fact, since the contents of the contents within a radius of 20% from the furnace wall portion account for about one third of the total contents, if an abnormality occurs in the layer of the charge near the furnace wall portion, it spreads to the whole blast furnace area. Therefore, in the blast furnace operation, the furnace wall part is managed as an important area in the after-layer management for the control of the gas flow distribution in the blast furnace, and the charge distribution which can effectively perform the after-layer management of ore and coke in all the radial areas including the furnace wall part. Control methods are very important in blast furnace operations.

In other words, in order to control the gas flow distribution in the blast furnace, the method of adjusting the layer ratio of coke and ore in the furnace radius direction is used as the most important means, and this filling ratio adjustment operation is generally called charging mode change. Changing the charging mode in the belly stop blast furnace consists of selectively using the inclination angle of the charging chute divided into 10 to 15 steps according to the blast furnace contents, wherein the inclination angle of the charging chute is called charging notch. In a typical blast furnace operation, regardless of the blast furnace content, coke uses about 5 to 7 charging notches, 4 to 6 allele sintering or 2 to 4 small notching sintering is used. In this way, in order to control the gas flow distribution through the charging of coke and ore using multiple charging notches, a plurality of charging notches constituting a single charge of coke and ore are indexed into one, and this index and gas flow distribution are used. The charge distribution control method is generally used to set the direction of the charging mode change by tracking the correlation with.

This conventional method has used a seismic index calculated as in Equation 1 below.

Load Seismic Index = (N _i * n) / N

here, N _i Is the charging notch number, n Is the number of rotations of the charging chute at each charging notch, N Indicates the total number of turns of the charging chute used for one charge.

However, even if the ore and coke fall from the charging chute of the same charging notch, the drop trajectory is different due to the difference in the friction coefficient between the density and the charging chute. However, the load seismic index calculated by Equation 1 has a problem that can not distinguish such a difference.

According to Japanese Patent Laid-Open No. 2-182815, an artificial intelligence is used to determine the distribution of gas in the blast furnace, and the calculation of the charge distribution prediction model based on real-time data at that time is performed under various conditions to select an optimal charging mode from the calculation results. A method is provided. However, this method is based on unstable calculations when the gas flow is classified into the furnace wall, middle part, and center part, and the method of measuring the interface between coke and ore due to coke collapse phenomenon when loading the ore has not been developed yet. Therefore, there is a problem that can not actually be utilized by the blast furnace manufacturers.

The Japanese Laid-Open Patent Publication No. 9-111321 method is a method for solving the problems of the method of Japanese Laid-Open Patent Publication No. 2-182815 and the load seismic index of Equation 1 below. A method of collecting and storing the correlation between the radial sediment ratio in the radial direction using the seismic index of the ore) and the measured value of the profile meter for a long time is provided. In this method, the load seismic index is calculated by Equation 2 below. However, this method also has a problem in the reliability of the post-layer distribution in the radial direction because the profile meter cannot measure fluctuations in the interface between coke and ore due to coke decay at the time of ore loading.

Load Seismic Index = [(X _i / R) * n] / N

here, X _i Is the distance between the fall trajectory of the charge and the intersection of the charge baseline and the furnace wall at each notch, R Silver furnace radius, n Is the number of rotations of the charging chute at each charging notch, N Indicates the total number of turns of the charging chute used for one charge.

On the other hand, the method of the Republic of Korea Patent Application 95-68442 provides a method to complement the problem of the method of calculating the seismic index of the charge of the method of Japanese Patent Laid-Open No. 9-111321. The load seismic index calculated by Equation 2 uses the intersection point of the drop trajectory at the charging baseline. However, at the time of actual loading, the upper deposition surface of the load differs considerably from the charging baseline, and this height change occurs from time to time, which is inconsistent with the actual situation. Therefore, a method of calculating the load seismic index based on the intersection point of the deposit surface and the drop trajectory during charging is proposed.

However, the methods of calculating the seismic index of the contents of Japanese Patent Application Laid-Open No. 9-11321 and Korean Patent Application 95-68442 are as follows for small sintered ore (small sintered ore) and allele sintered ore (large sintered ore). There are decisive problems that do not consider charging characteristics. In normal blast furnace operation, small sintered ore is concentrated in the furnace wall, and the weight ratio of small sintered ore in the ore is in the range of 10 to 25%, but the number of rotation of the small sintered ore is 30 Since it takes up to 40%, when considering only the rotational speed of the charging chute as in Equation 1, it becomes smaller than the actual ore seismic index considering the weight. This difference becomes larger when the mixing chute speed of the small sintered ore is kept constant while the mixing ratio of the small sintered ore in the ore is smaller or larger than the reference value by simply adjusting the mass control valve to change the discharge rate. For this reason, when the charging mode is operated or when the change is made, the post-layer distribution is adjusted in a different direction than the intended one, so that the amount of the ore portion of the furnace wall is excessively increased, causing the furnace wall to be inactivated, or the amount of coke amount of the furnace wall is charged too much, thereby increasing the heat loss of the furnace wall portion. It will lead to an aging relief.

On the other hand, according to Japanese Patent Laid-Open No. 9-310109, while maintaining the heat flow ratio and gas utilization rate of the furnace wall portion constantly, the ore granularity of the furnace wall portion and the layer thickness of the ore and coke layer of the furnace wall are controlled to suppress the lack of furnace wall flow or excessive growth of the furnace wall attachment. A method is provided to reduce the pressure loss and reduce the frequency of the gusts. However, this method suggests changing the charging order only by changing the order of the ore from the small sintered to the small sintered ore, from the small sintered to the small sintered ore as a method of increasing the particle size of the furnace wall. However, since most of the blast furnaces adopt the latter charging order, it is not possible to call the new charge distribution control method, and no clear means are provided for the method of managing the floor thickness in the vicinity of the furnace wall.

In the case of poor management of the radial laminar distribution of the blast furnace by the load seismic index substituted for the load index, the furnace wall inactivation or excessive reduction differentiation may occur due to inappropriate reduction reaction due to excessive ore loading near the furnace wall part. This causes the yellowing relief caused by the deterioration of breathability near the furnace wall due to the generation of powder.

Fig. 1 shows a schematic view of the reduction crater 8 of the furnace wall ore being wide in the blast furnace height direction when the post-layer distribution control is wrong. Distance between the falling trajectory 2 and the furnace wall 9 at the reference charging line 3 of the coke 4, the allele sintered light 5, and the small sintered ore 6, which are charged into the blast furnace through the charging chute 1 In order to know how much of the reduced charging zone has been determined by determining the charging mode, the vertical zone (7) is lowered from the hearth with the charge to the furnace wall, and the temperature distribution of the furnace wall is measured.

The present invention is to solve the above problems, and to provide a new charge seismic index in the actual situation in consideration of both the weight of the chute chute and small sintered or allele sintered light.

1-Schematic diagram of blast furnace charge sedimentary layer

2-Comparative graph of the conventional method and the load seismic index according to the present invention

Figure 3-Graph showing the characteristics of the load seismic index proposed in the present invention

4-Graph showing the results of reduction differentiation experiment

5-Graph showing the results of reduction differentiation experiments by particle size

Fig. 6-Graph showing the vertical Zonde measurement results

7 is a graph showing the proper charge distribution control range proposed in the present invention.

8A to 8C-Graph showing the results of operation by the charge distribution control method of the present invention

According to the present invention for achieving the above object, there is provided a new ore seismic index utilizing the weight ratio of the small sintered ore among the charged ore composed of small sintered and allelic sintered in the blast furnace having a belly stop charging device.

In addition, there is provided a post-layer management method capable of performing proper post-layer management for the activation of the furnace wall part by using the furnace wall temperature measured using the new seismic index and the vertical zone.

The load seismic index according to the present invention is obtained from Equation 3 below.

here, ol , os Are sintered or small sintered ores, respectively. W (ol) , W (os) Are the weight fractions of allelic and small sintered ores, respectively, X _i Is the distance between the fall trajectory of the charge and the intersection of the charge baseline and the furnace wall at each notch, R Silver furnace radius, n Is the number of rotations of the charging chute at each charging notch, N Indicates the total number of turns of the charging chute used for one charge.

1 is a charge seismic index of the conventional method determined by the ratio of coke seismic index and ore seismic index calculated by Equation 1 of the one-time charging mode consisting of coke → allele sintered light → small sintered ore (= ore seismic index / The coke seismic index) is equivalent to the charged seismic index calculated by the method of the present invention represented by the equation (3). It can be seen that the smaller the seismic index is, the larger the difference between the absolute value of the conventional method and the method of the present invention is as the seismic index of the charge calculated by the method of the present invention becomes larger. This is because the value of the load seismic index of the ore calculated by the conventional method is calculated to be smaller than the actual value.

Figure 2 shows the seismic index of the ore when the charging chute rotation speed of the allele and small sintered ore is changed by the method of changing the mixing ratio of the allele and the small sintered ore in a constant state. In the conventional method, since the loading speed acts as a major independent variable, the seismic index of the ore shows a constant value even if the rotational speed is not changed, even if the mixing ratio of allele and small sintered minerals is different, In the method of, it can be seen that the seismic index fluctuates according to the mixing ratio of both. In practical operation, small sintered ore uses charge notches in the range of 1 to 4, while allele sintered ore uses charge notches in the range of 4 to 9, so that the sintered and small sintered ores are operated at a constant charging chute speed. If the weight-based mixing ratio is different, the thickness distribution of the ore layer in the blast furnace radius direction is different. Therefore, it is very important in the control of the furnace radial layer distribution according to which load seismic index reflects the actual situation better. The method of this invention is shown to be more efficient than the conventional method. At this time, the change of layer thickness distribution in the blast furnace radius direction according to the load seismic index is based on the load distribution equation model and the method of correcting the boundary line variation of the coke and ore layers due to coke collapse by slope stability theory of soil mechanics. After calculating the ore and coke layer thickness in the blast furnace radius direction, the layer thickness of the furnace wall was divided by the layer thickness of the core.

Figure 4 is a reduction differentiation carried out to determine the temperature range in which reduction differentiation is maximized in order to implement the yellowing stabilization through the reinforcement of the furnace wall portion by controlling the size of the furnace wall reduction eruption zone using the load seismic index proposed in the present invention The results of the experiment are shown. In the reduction differentiation experiment, 500 g of a sintered ore having a particle size of 15 to 20 mm was reduced with a reducing gas of 70% N2 + 30% CO for 2 hours, and then a 900 minute rotation of the reducing sample was carried out. Method was used. As can be seen from the test results of FIG. 4, the reduction differentiation was the largest at 550 ° C., and at this time, the reduction differentiation reached a maximum when the reduction time reached about 90 minutes, but at 700 ° C. or more, the reduction differentiation rate was almost changed over time. It appeared to be irrelevant. Therefore, in this example, the temperature range where reduction differentiation is concentrated was determined to be 400 to 650 占 폚.

FIG. 5 is a sample of 7 mm, 9 mm corresponding to small sintered or 13 mm, 18 mm, and 23.5 mm corresponding to allele sintered ore to reduce the size of particles affecting reduction differentiation. After reducing for 30 minutes at 550 ℃ under conditions, the average particle size of the sample was investigated. Regardless of the size of the initial sample, the size of the final particles after the end of the reduction was found to be almost similar. From these facts, it was confirmed that the size of the furnace wall reduction zone was driven by both small and alleles.

From the above facts, the correlation between the size of the reduced sedimentation zone by the temperature distribution measurement of the furnace wall seismic index using the vertical zone was proposed by the method of the present invention which weighted the weight ratio of allele and small sintered ores. It was confirmed that the ventilation of the blast furnace could be improved by improving the air permeability of the wall.

In order to confirm the effect of the present invention, a test operation was carried out under the conditions shown in Table 1 in a blast furnace having a bellows-loading device having an internal volume of 2600 m ³ . The ore and coke seismic index was used in the method of the present invention represented by Equation 3, and the ore seismic index / coke seismic index is represented as a load seismic index in order to substitute this as a charging index. At this time, the relative ratio between the floor wall ratio of the furnace wall portion and the center layer thickness ratio is calculated by the mathematical model.

Exam number Charge Seismic Index Charging mode Charge amount (ton / time) Furnace Wall Layer Pick ------------ Center Layer Floor Pick cokes ore Ore / coke Coke (C) Allelic sintering (ol) Small Sintered Ore (os) cokes Sintered ore Small sintered ore One 0.4407 0.3705 0.8406 56789 1012222 2 5678922222 234121 18.5 51.2 12.8 5.385 2 0.4407 0.3310 0.9906 456789122222 5678922222 234121 18.5 51.2 12.8 2.027 3 0.2702 0.3149 1.1653 234567122223 4567822222 234121 18.5 53.8 10.2 1.041 4 0.2852 0.3396 1.1908 3456722233 456789122222 234121 18.5 49.9 14.1 0.742 5 0.2852 0.3239 1.2567 234567122223 456789122222 234121 18.5 52.5 11.5 0.389

Here, the floor pick Ore layer thickness / coke layer thickness being.

Figure 6 shows the length of the temperature range in the range of 400 ~ 650 ℃ measured by dropping the vertical zone as a charge to the place 1m away from the furnace wall of the roadbed in the test operation of Table 1. The transit time through the temperature section in the range of 400 to 650 ° C was calculated by dividing the length of the temperature section by 10 cm / min. As can be seen in FIG. 6, the temperature range of 400 to 650 ° C. is increased up to 1.15 and the seismic index of the present invention tends to decrease again. At this time, the time passing through the temperature range of 400 ~ 650 ℃ varied greatly from minimum 15 minutes to maximum 65 minutes.

Figure 7 shows the upper air flow resistance index and the change in the layer thickness ratio showed the same change as the overall air flow resistance index during the test operation of Table 1. The airflow resistance index continues to increase until the load seismic index 1.15, which is consistent with the temperature section length increase range of 400 to 650 ° C in FIG. It was confirmed that it is caused. On the other hand, the post-layer distribution of the furnace wall to the center decreased as the load seismic index increased. When the earthquake resistance index is less than 0.9, the reduction reaction is weak due to the excessive loading of the ore in the furnace wall, so that the amount of dust generated is low, and the airflow resistance index is lowered. Increasing the amount of ore at the furnace wall decreased, increasing the ore reduction capacity of the reducing gas, increasing the amount of reduced ore reduction and increasing the upper airflow resistance index. Therefore, the area where avoiding deactivation due to excessive stagnant layer generation due to excessive ore loading into the furnace wall part and avoiding deterioration of air permeability due to increased dust generation amount due to reduction differentiation is 0.95, and the furnace wall part with respect to the center layer thickness It confirmed that the relative ratio of layer thickness was 3.0 or less. At this time, the ventilation resistance index was calculated from Equation 4 generally used in the blast furnace operation as follows.

Aeration Resistance Index = (P 1 ² -P 2 ² ) / VBG ^1.7

here, P 1 Is the pressure at the lower part of the furnace, P 2 Is the pressure at the top of the furnace, VBG Indicates the amount of bosh gas.

8a to 8c show the operation using the charging mode corresponding to the charge seismic index 1.21 calculated by the method of the present invention and the furnace seismic index 0.97, which is the optimum charging condition of the furnace wall part, according to the method of the present invention. The results of the operation in the relative ratio 2.8 of the wall layer ratio are shown. In operation, the blowing pressure and the ventilation resistance index were all improved, and the fuel consumption was reduced through the improvement of the yellowing.

As can be seen above, the present invention utilizes the ore seismic index calculated by using the respective charging notches of the small sintered and allele sintered ores, the rotational speed and the weight ratio of the charging chutes for each notch. By adjusting the charging mode using the water seismic index (= ore seismic index / coke seismic index) and the relative ratio of the furnace wall layer ratio to the core layer ratio, it is possible to improve furnace wall ventilation by minimizing the reduction and differentiation of the furnace wall area. This aims to stabilize the blast furnace operation by reducing the blowing pressure and ventilation resistance index and reducing fuel costs.

Claims (1)

In the blast furnace having a belly stop charging device, the method of controlling the distribution of the charged material in the blast furnace, The weight ratio of small sintered ore among the charged ores composed of small and sintered ore is used as weight. By calculating the load seismic index using the following equation, A blast furnace loading distribution control method characterized in that the appropriate after-layer management for the activation of the furnace wall portion is performed by using the obtained furnace wall temperature measured using the seismic index and the vertical sonde. here, ol , os Are sintered or small sintered ores, respectively. W (ol) , W (os) Are the weight fractions of allelic and small sintered ores, respectively, X _i Is the distance between the fall trajectory of the charge and the intersection of the charge baseline and the furnace wall at each notch, R Silver furnace radius, n Is the number of rotations of the charging chute at each charging notch, N Indicates the total number of turns of the charging chute used for one charge.