KR20030053750A - Method for controlling particle size distribution of burden in blast furnace - Google Patents

Abstract

PURPOSE: A method for controlling particle size distribution of burden in blast furnace is provided to activate the furnace wall part and improve average gas use ratio by equalizing time series particle size deviation of charging materials discharged from furnace top bunker, thereby increasing average particle size of the intermediate part on the furnace wall part. CONSTITUTION: The method is characterized in that time series particle size deviation from the initial stage of discharging of charging materials discharged from furnace top bunker to the finishing stage thereof is equalized by maintaining a ratio (D2/D1) of cone diameter (D2) at a boundary portion where upper and lower inclination angles of two-step inclination cone are transferred to diameter (D1) of discharge port of the lower part of the furnace top bunker to 1.3 or more when charging the charging materials through furnace top bunker to the inner part of which two-step inclination cone having different upper and lower inclination angles is adhered, thereby generating mass flow of the charging materials inside the two-step inclination cone and in the front part of the furnace top bunker, wherein the ratio of D2/D1 is 1.4 or more.

Description

Method for Controlling Particle Size Distribution of Burden in Blast Furnace}

The present invention relates to a method for charging a charge into a blast furnace in a blast furnace top bunker, and more specifically to the funnel flow by attaching a two-stage inclined cone inside the blast furnace top bunker. The present invention relates to a method for controlling the particle size distribution in a blast furnace by using a bunker bunker that can be completely changed into a mass flow form.

The blast furnace is a reactor filled with a large part of the furnace volume, with solids flowing downward and gas flowing upwards with a solid stream and a gas cloud.

The efficiency of the reduction reaction and phase transition of the granule packing depends on how well the gas flowing between the granules passes smoothly without being subjected to aeration resistance.

Therefore, the gas used in the blast furnace as the heat medium and the main reduction reaction gas is a gas flow distribution control is the only way to control the situation in the furnace.

This gas flow distribution is theoretically determined by the layer thickness ratio and particle size distribution of the coke and the ore layer.

The double layer thickness ratio distribution is used as an effective gas flow distribution control means by controlling the operation method of the charging device, that is, controlling the inclination angle or the rotation speed of the charging chute and the like at any time.

However, the particle size distribution is generally fixed to the charging device has not been effectively used as a yellowing control means.

An example of a control means of gas flow distribution through particle size distribution control is given in Japanese Patent Application Laid-Open No. 5-98327, where extra storage is used for installing a plurality of storage bins of cocos and sintered ores and for controlling dual particle size. A method of controlling the average particle size of raw materials charged into a furnace by installing sieves of different sizes in the lower part of the bin is proposed.

In addition, Japanese Patent Laid-Open No. 5-96242 discloses a method for changing the average particle size from time to time according to the purpose of aging management by installing a sieve whose size can be arbitrarily changed by a mechanical device under a storage bin.

However, these methods reduce the sinter recovery rate by removing sieves larger than the sieve size by installing a sieve under the storage bin, and even after adjusting the average particle size in the storage bin, the surge hopper and the top installed in the rear stage are installed. The funnel flow discharge from the bunker has the fundamental problem that the shape of the particle size distribution in the furnace cannot be changed.

In addition, Korean Patent Application No. 2000-80092 discloses that the storage bin of the transportation system installed in the blast furnace plant is used to store the contents by the particle size while maintaining the existing form, and the surge hopper and the bunker bunker are Blast furnace operation to expand gas flow control range and reduce fuel cost by changing the particle size distribution in the blast furnace arbitrarily by changing the structure from the bunker type to the preloaded mass flow bunker after the channel. The method is presented.

However, this method can be effectively used when establishing a blast furnace plant because all hoppers in the charging series need to be replaced. However, this method cannot be used when a problem is found in the storage hopper of the blast furnace in operation and a partial replacement of the device is needed. I have a problem.

All the storage hoppers used in the blast furnace operation have the shape of channel after the channel, especially the channel of the top bunker is designed to promote sedimentation of the contents of the charges in the furnace through the charging chute to suppress the gas flow in the furnace wall. The cause of the furnace wall inactivation is provided.

The present invention attaches a two-stage inclined cone to the top of the top of the top of the top bunker bunker to provide the contents of the charge discharged from the top bunker bunker bunker front in the blast furnace process. The purpose of the present invention is to provide a method of controlling the particle size distribution in a blast furnace that can increase the average particle size of the middle part in the furnace wall part and thereby improve the average gas utilization rate by leveling the time series particle size deviation.

1 is a schematic view showing a conventional blast furnace bunker

2 is a schematic view showing an example of a blast furnace top bunker preferably applied to the present invention.

3 is a graph showing the change of the area height h / bunker height H after mass according to the change of the bunker outlet diameter D2 / cone inclination-angle transition part diameter D1.

Figure 4 is a graph showing the time-series particle size change of the ore discharged from the bunker in the case of applying the conventional method and the present invention method

Figure 5 is a graph showing the particle size distribution in the furnace before and after applying the method of the present invention

6 is a graph showing gas utilization variation before and after applying the method of the present invention.

7 is a graph showing fluctuations in the bottom wall temperature before and after applying the method of the present invention.

Explanation of symbols on the main parts of the drawings

6, 60. . . Trip bunker 10. . . 2 step inclined cone

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated.

According to the present invention, at the boundary where the diameter D1 of the top bunker bottom discharge port and the top and bottom inclination angles of the two-stage inclined cone transition when the charges are charged through a top bunker having a two-stage inclined cone having different inclination angles in the upper and lower portions therein. The ratio (D2 / D1) of the cone diameter (D2) of is greater than 1.3 to generate a mass flow of the charges in the inside of the two-stage inclined cone and the top bunker, so that the charges discharged from the top bunker are discharged from the beginning to the end. The present invention relates to a method for controlling the particle size distribution in an blast furnace to uniformize the time series particle size variation up to.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The formula for calculating the pressure loss in the packed bed height direction when gas flows through the packed bed made of particles is generally represented by the following relations (1), (2) and (3) [Ergun equation].

[Relationship 1]

f _v = A ΔP / L = k ₁ + k ₂ .N _re / (1-ε)

[Relationship 2]

A = D _p ² ε ³ / (μU (1-ε) ² )

[Relationship 3]

N _re = D _p U / μ ------- (3)

Where f _v : air resistance index

k ₁ , k ₂ : ventilation resistance coefficient

ε: Porosity (-)

N _re : Reynolds number (-)

D _p : Average particle size (cm)

U: Gas tower speed (cm / sec)

μ: gas viscosity (cp)]

The contents of the blast furnace are piled with alternating ore layers and coke layers having a constant average thickness, and the in-house pressure loss according to Equation (1) is generally calculated by combining one coke layer and one ore layer as one unit layer. do.

However, since the pressure loss distribution in the horizontal direction is generally ignored, the pressure loss per unit bed at each measurement point in the furnace is assumed to be the same.

In this case, if ΔP / L = 1 for one unit layer, Lc / (Lo + Lc) is represented by the coke ventilation resistance index given by Equation (1), and Lo / (Lo + Lc) is defined by the ore resistance index of the ore. Multiply by one, the left side becomes 1 and the right side becomes the quadratic equation for the gas flow rate, so one quadratic equation for the gas flow rate is obtained.

The independent variables governing the gas flow rate are coke and ore layer thicknesses Lo (ore), Lc (coke) and average particle diameters D _p (ore) and D _p (coke).

Therefore, the gas velocity in the furnace of the blast furnace packed layer is determined by the post-layer distribution and the particle size distribution, and the uniformity of the post-layer distribution and the degree of segregation in the furnace determine the stability of the gas flow and the distribution of the radial gas flow.

In the present invention, by changing the internal shape of the top bunker to minimize the homogeneity of the post-layer distribution that is directly connected to the stability of the gas flow, and to minimize the time-series particle size variation of the charges discharged from the top bunker to uniform the particle size distribution in the furnace to increase the furnace wall gas flow Therefore, it provided a method for controlling the particle size distribution in the blast furnace to activate the furnace wall.

1 is smaller than the critical angle of 70 ^o in the prior exposed bunker bunker inclined surface (1) and the horizontal plane and the angles (2) size is 50 ~ 60 ^o by mass since the ore and coke and hwonel since the as to correspond to the bunker after hwonel discharge The speed is uneven and the time series particle size deviation of the discharged charges is large.

In addition, when opening the lower mass control valve 5 with the small particles 3 in the center of the bunker and the large particles 4 in the periphery, the characteristics of I-> II-> III-> IV after the channel are opened. Emissions occur in sequence, resulting in time-series particle size variations.

Figure 2 shows an example of a top bunker with a two-stage inclined cone in accordance with the present invention.

As shown in Fig. 2, the top bunker 60 according to the present invention is equipped with two-stage inclined cones 10 having different upper and lower inclination angles.

The upper portion 11 of the two-stage inclined cone 10 has a conventional bunker inclination angle, and the lower portion 12 is inclined in two stages to a critical angle of 70 ^° or more after mass of ore and coke.

Conventional bunker inclination angle is about 50 ~ 60 ^o , the inclination angle of the top 11 of the two-stage inclined cone 10 in Figure 2 is 55 ^{o .}

The inclination angle of the lower part of the second inclined cone 10 may be set to a critical angle of 70 ^° or more after the mass, but since the cone is mounted on an existing bunker, the angle of the bunker may be equal to or slightly less than the critical angle after the mass. It is preferable to set large.

That is, the lower inclination angle of the two-stage inclined cone in the top bunker of the present invention is greater than or equal to the critical angle of 70 ^o after mass, so that the maximum reduction of the top bunker contents by the attachment of the two-stage inclined cone does not exceed two-thirds of the top bunker clearance. It is preferable to set.

In general, since the contents of the top bunker have a margin of about 15% with respect to the volume of the charge charged once, it is desirable that the reduction of the top bunker contents by the inclination of the two-stage inclined cone 10 does not exceed 10%. Do.

FIG. 3 illustrates a change in the area where the mass flow occurs inside the bunker according to the ratio of the bunker lower outlet diameter D1 and the diameter D2 of the inclined angle change portion of the two-stage inclined cone.

As shown in FIG. 3, when D2 / D1 is 1.3 or less on the basis of D2 / D1 1.3 to 1.4, bass flow is generated only in an area corresponding to the steep slope of the two-stage inclined cone, and the time-series particle size change of the charges discharged from the bunker is generated. However, when D2 / D1 is 1.4 or higher, mass drift occurs in the whole bunker area, and it can be seen that the time-series particle size change can be drastically corrected.

As in the present invention, when the charge is charged into the blast furnace using a top bunker with a two-stage inclined cone, a mass flow of the charge is generated inside the two-stage inclined cone and the front bunker, so that The time-series particle size variation from discharge to discharge is uniform, and the increase in sample particle size just before discharge is suppressed, making the particle size distribution from the furnace wall part to the middle part larger than that of the conventional bunker. By increasing the gas flow in the middle portion of the wall portion, it is possible to eliminate the furnace wall deactivation.

Hereinafter, the effects of the present invention through the examples will be described in more detail.

(Example)

In order to realize the effects of the present invention, the contents of the contents are discharged in the case of using the conventional bunker through the 1/5 scale bunker model device of 2600m ³ blast furnace and the case of using the bunker with the two-stage inclined cone of the present invention. Velocity and time-series particle size deviations were investigated and the results are shown in FIG. 4.

In the case of using the conventional bunker and are attached two-stage inclined cone bunker of the present invention in the internal volume 2600m ³ blast furnace 1 / 13.6 sized blast furnace model of the apparatus having the same type of exposed bunker examine the furnace size distribution of the coke with respect The results are shown in FIG. 5.

Table 1 below is a discharge rate test condition considering the particle size range of coke commonly used in blast furnace operation.

Experiment number Coke amount (kg / ch) Mass control valve opening Angle of inclination angle Cone diameter / Bunker outlet diameter One 100 41.6 1.2 2 100 41.6 1.25 3 100 41.6 1.3 4 100 41.6 1.35 5 100 41.6 1.4 6 100 41.6 1.45 7 100 41.6 1.5

As shown in FIG. 4, when using a conventional bunker, the particle size increased from the beginning to the end of the discharge after a slight decrease in particle size at the beginning of discharge, while the particle size was almost uniform from the beginning to the end of the discharge after the two-stage cone was attached. It can be seen that there is a slight increase in particle size just before the end of the discharge.

As shown in FIG. 5, in the case of using a conventional bunker, it can be seen that the particle size from the radial furnace wall portion to the middle portion is small and the particle size rapidly increases from the middle portion toward the center portion. The gas flow can be secured, but the furnace wall gas flow is weak, which provides the cause of the inferior furnace wall inactivation.

However, after the two-stage inclined cone of the present invention, it can be seen that the particle size variation in the radial direction is considerably solved, so that the particle size distribution that can increase the gas flow in the furnace wall portion and the middle portion can be obtained relatively more than in the case of using a conventional bunker. .

The gas utilization distribution change was calculated using the radial gas composition measured by the shaft sonde before and after the application of the present invention, and the results are shown in FIG. 6.

As shown in Figure 6, before the application of the method of the present invention, the gas utilization rate in the center is very low and the furnace wall portion and the middle portion gas utilization rate are high, so that the average gas utilization rate is only 49%.

On the contrary, after the method of the present invention, the gas utilization rate of the furnace wall and the middle portion decreased slightly, but the average gas utilization rate increased to 50% due to the significant increase in the central gas utilization rate.

The change of (Bosch part temperature + valley part temperature) / 2 which shows the degree of activation of the furnace part furnace wall part before and after application of this invention was investigated, and the result is shown in FIG.

As shown in FIG. 7, before the method of the present invention, the furnace wall gas flow was small and the furnace wall temperature was low, causing the furnace wall inactivation. However, after the method of the present invention, the furnace furnace wall temperature was greatly increased. It can be seen that the furnace wall is activated.

As described above, in the case of using the top bunker with the two-stage inclined cone of the present invention, the furnace wall fire caused by the relative small granularity of the center portion of the barrier layer from the furnace wall portion to the middle portion due to the channel of the channel in the existing bunker. It is possible to improve the particle size distribution, which can eliminate the activation, and to expand the operation control range of the blast furnace in the gas flow distribution that determines productivity and fuel cost, thereby increasing energy efficiency and reducing the opportunity loss due to gas instability. have.

Claims (2)

Cone at the boundary where the diameter (D1) of the lower bunker outlet and the upper and lower inclination angles of the two-stage inclined cone transitions when the charge is charged through the two-stage inclined cone having different inclination angles of the upper and lower parts therein. From the beginning to the end of the discharge of the charges discharged from the top bunker by generating a mass flow of the charges in the inside of the two-stage inclined cone and in the top bunker bunker so that the ratio D2 / D1 of the diameter D2 is 1.3 or more. Particle size distribution control method in a blast furnace characterized by uniformizing the time series particle size deviation The method of controlling the particle size distribution in a blast furnace according to claim 1, wherein the ratio of D2 / D1 is set to 1.4 or more.