KR101140891B1 - method for calculating stock profile of charge of blast furnace - Google Patents

Abstract

The present invention relates to a method for calculating a stacking profile of a blast furnace charge, comprising: a charging baseline setting step of setting a charging baseline; A lamination line generating step of generating a new lamination line according to the charging of the charge above the set charging reference line; And setting a observation point on the generated stacking line and dropping the stacking line on which the observation point is set to generate a new drop stacking line.
The stack profile of the whole blast furnace can be accurately known in consideration of the charge properties and the dropping phenomenon, so that it is possible to efficiently control the blast furnace load distribution.

Description

Method for calculating stock profile of charge of blast furnace}

The present invention relates to a method for calculating a stacking profile of blast furnace charges, and more particularly, to a method for calculating a stacking profile of blast furnace charges, which enables to more accurately grasp the distribution of loads in a blast furnace charge.

A blast furnace is a facility for melting molten iron ore to manufacture molten iron (pig iron).

Iron ore and coke are sequentially charged and stacked in the blast furnace, and the hot air is blown from the lower tuyere to combust the coke. .

The present invention is a state in which charges are sequentially loaded and stacked in the blast furnace, that is, the stacking profile of the charges can be more accurately known in consideration of the physical properties and the dropping phenomenon of the charges, so that the blast furnace operation efficiency and productivity through more efficient charge distribution control It is an object of the present invention to provide a method for calculating a stacking profile of a blast furnace charge, which can be improved.

The present invention for achieving the above object,

A charging baseline setting step of setting a charging baseline;

A lamination line generating step of generating a new lamination line according to the charging of the charge above the set charging reference line;

A drop stacking line generation step of setting a observation point on the generated stacking line and dropping the stacking line on which the observation point is set to generate a new drop stacking line;

It includes.

In addition, in the linear stacked line generated in the stacking line generation step, the linear region and the curved region are determined, and the positions of the upper and lower points of the curved region are determined, and then the stacked line and the curved line of the linear region. The method may further include a lamination line correction step of connecting the lamination line of the region to a curve including the upper point and the lower point.

The charging baseline setting step may include setting an initial charging baseline, charging a charge to generate a secondary charging baseline, lowering the secondary charging baseline, and setting it as a new initial charging baseline, to the new initial charging baseline. Stacking the charges to generate another new charging baseline, and resetting the another new charging baseline to the initial charging baseline.

In addition, the position of the lamination line generated later with respect to the lamination line first generated in the charging reference line setting step and the lamination line generation step,

It is characterized in that it is set by repeatedly calculating until the two volume values are the same by comparing the volume converted into the volume of the area between the first lamination line and the lamination line generated later and the volume of the actual charge.

In addition, the position of the lamination line generated later with respect to the lamination line generated first in the drop stacking line generation step,

Characterized in that it is set by iteratively calculating until the difference between the two volume values is set by comparing the volume converted into the volume of the area between the first and the second lamination line generated and the later generated lamination line in volume do.

In addition, when the charge baseline setting step and the stacking line forming step to stack the charges to form a new stacking line, it is characterized in that the generation of a mixed layer generated by mixing the coke and ore.

In addition, the present invention, the lamination line calculation step of calculating the lamination line of the charge;

A strong Harein calculation step of generating a strong Harein by lowering the stacked line calculated in the stacking line calculating step;

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According to the present invention as described above,

In consideration of the physical properties of the charge it is possible to more accurately and easily know the shape of the lamination line according to the charge.

In addition, it is possible to know the overall profile of the blast furnace charge by accurately knowing the falling stacking line of the charge in consideration of the charge drop phenomenon according to the operation of the blast furnace.

Therefore, there is an effect that can improve the blast furnace operation efficiency and productivity through more efficient charge distribution control.

In addition, as described above, the overall profile of the blast furnace load can be grasped, and thus it can be usefully used for ventilation control of the blast furnace.

1 is a block diagram showing the configuration of the present invention;
2 is an exemplary view of generating a charge stacking line for explaining a charging baseline setting step;
3 is a graph showing the change of the coke stacking line before and after loading ore as a result of the blast furnace reduction model,
4 is a graph showing the change of coke lamination line before and after loading ore as an EDEM simulation result;
5 is a graph showing the relative particle size of the ore and coke in the blast furnace radial direction,
6 is a schematic diagram for explaining a curve of a lamination line;
7 is a blast furnace reduction model and the lamination line comparison drawing according to the present invention,
8 is a view for explaining a drop line generation process;
9 is a graph showing the descent rate according to the charge drop;
10 is a graph showing the relative descent velocity distribution for each type of light,
11 is a comparison of the blast furnace scale model and the stacking profile according to the present invention.

Hereinafter, with reference to the accompanying drawings, the present invention will be described in detail.

As shown in FIG. 1, the present invention lowers a stacking line calculating step S1 for calculating a stacking line having a shape of an upper surface of a charge charged in a blast furnace, and the stacking line calculated in the stacking line calculating step S1. And a drop line calculation step S2 of generating a new stacked line dropped.

The stacking line calculating step (S1) includes a charging baseline setting step (S1-1), a charging step (S1-2), a stacking line generating step (S1-3), and a stacking line correction step (S1-4). It includes.

The stacking shape of the blast furnace is represented by a stacking line, and the stacking line can be calculated from the drop trajectory (loading position of the load and the left and right repose angle of the load deposit at that position).

In the initial stage of charging, since there is no charge in the blast furnace, the charging baseline setting step (S1-1) is performed to reduce an error due to the absence of the charge.

The charging baseline setting step (S1-1) is performed as follows. As shown in the upper graph of Fig. 2, the initial charging reference line SL1 is arbitrarily set, and 1 batch is charged on the upper part according to the charging mode.

The lamination line is produced by calculating the left and right angles of repose at the high density flow dropping positions present in the center of the charge drop flow.

The position of the newly created stacking line SL2 is converted into a volume of the area between the stacking line SL2 and the initial charging reference line SL1 and is set to a position where the volume and the actual loading volume coincide. The new stacking line SL2 is set as the secondary charging reference line SL2.

Thereafter, the secondary charging reference line SL2 is lowered by an appropriate height H and set as a new initial charging reference line SL3 as shown in the lower graph of FIG. 2.

Subsequently, 1 batch of charge is again applied to the upper portion of the charging reference line SL3, and a new lamination line SL4 is generated through the same method as above, and is set again as a new charging reference line.

By setting the initial charging baseline through the repetition of the above process, it is possible to reduce an error in the initial stacked line generation caused by the emptying of the initial charging blast furnace.

After the charging baseline is determined through the above process, the charging step (S1-2) is carried out to charge the charging item.

On the other hand, the physical properties of the charge (charge amount, particle size, density, shape coefficient, friction coefficient), the friction coefficient when the chute movement of the particles of the charge, the angle of repose during drop deposition, etc. are determined according to the type of charge to be charged. This is reflected in the lamination line generation.

Thereafter, a stacking line by charging is generated in the same manner as in the charging baseline setting step (S1-1).

That is, the area between the charging baseline and the lamination line formed thereon is converted into a volume, and the position of the newly formed lamination line is determined so that the converted volume matches the actual volume of the charged charge.

In setting the initial charging reference line as described above, and creating another lamination line thereon, the present invention allows a more realistic lamination shape to be realized in consideration of the mixed layer and the particle size distribution, the shape coefficient, and the porosity of the charge.

The mixed layer is generated by the collapse of the first coke layer charged by the falling energy of the ore, and the collapsed coke is moved to the center of the blast furnace and mixed with the charged ore.

The density of the mixed layer depends on the amount of ore and coke incorporation. The volume of coke in the mixed layer is distributed in the range of 25% to 75%.

3 is a graph showing the change in the coke stacking line before and after the loading of the ore as a result of the blast furnace reduction model experiment. (The radius 0 is the center of the blast furnace.) In the graph, after the ore is charged, It can be seen that the height of the side is increased and the height of the blast furnace wall is lowered. As a result, it is confirmed that coke on the blast furnace wall side moves toward the center of the blast furnace by charging the ore, and the coke thus moved is mixed with the ore to form the mixed layer.

Fig. 4 is a graph showing the results of the same experiment using EDEM, a particle behavior simulation tool. (In this case, the wall of the blast furnace is where the distance in the X direction is 0. Compared with Fig. 3, Fig. 4 is the left wall of the blast furnace. Part of the simulation results.)

In FIG. 4, the same behavior as that of the coke stacking line is lowered in the wall side and the furnace center side is increased by the ore loading than in the loading of the ore.

The volume ratio of ore and coke was calculated in the mixed layer formed during the EDEM simulation, and the values of ore 0.466 and coke 0.534 were obtained.

As described above, the present invention may consider the presence of the mixed layer when calculating the lamination line, and by calculating the volume ratio of the ore and the coke of the mixed layer, it is possible to more accurately grasp the distribution state of the charge.

On the other hand, the friction coefficient of the charge is different depending on the particle size, which is related to the moving distance on the slope when the charge is stacked, the particle size distribution along the radial direction of the light type is changed.

5 shows the relative particle size of ore and coke along the radial direction.

In the case of ore, it can be seen that the particle size is relatively large in the furnace center.

In the analytical model according to the present invention, the radial particle size distribution was considered based on the data shown in FIG. 5. (Particle size distribution based on the particle size of the opposing light 0.03m, the small particle light 0.01m, the coke 0.045m, and the center coke 0.07m. Was different.)

Also, the change of shape coefficient according to the particle size was considered as following equations (1) and (2).

Φ _coke = 0.390log (D _p ) +1.331 ------------------------ (1)

Φ _Ore = 0.328log (D _p ) +1.268 ------------------------- (2)

(Φ _coke : coke shape factor, Φ _Ore : ore shape factor, D _p : particle diameter)

In addition, the porosity distribution according to the particle size distribution is considered. The porosity of coke and ore is given by the following equations (13) to (20).

ε _C = (0.153 log D _p +0.418) (1-Δε) ------------------- (3)

Δε = 1.225 × 10 ^-2 × I _sp ^0.416 -------------------------- (4)

ε _O = (0.403logD _p ^0.14 ) (1-Δε) ----------------------- (5)

^Δε = 1.64 × 10 ^-3 × I _sp ^1.006 --------------------------- (6)

Ε _C and ε _O are porosities of coke and ore and are affected by particle size, I _s , and I _p . The I _s , I _p are as follows.

I _s = D _p ² Σwi (1 / di-1 / D _p ) ² ------------------------------ (7 )

I _p = (1 / D _p ) ² Σwi (di-D _p ) ² ------------------------------ (8 )

I _sp = 100 (I _s ? I _p ) ^0.5 ---------------------------------- (9)

D _p = 1 / Σ (wi / di) ------------------------------------ (10)

(wi: weight fraction by particle size, di: representative particle size by particle size)

After generating the lamination line in consideration of the physical properties of the charge as described above, the lamination line correction step (S1-4) is performed.

The stacking line correction step (S1-4) is to obtain curves closer to the actual stacking shape by 'curving' the stacking lines generated in a straight line shape.

Curve of the straight lamination line is made as shown in FIG.

As shown, the curved areas in the triangular linear stacked lines are the top of w1 and w2 and the bottom of w3 and w4. Here, the values of w1 to w4 are set using the scale model experimental data.

dD is the distance from the top vertex of the stacking line to the curve. As the dD value increases, the top of the stacking line becomes smoother.

The dD2 and dD3 values take into account the accumulation of particles sliding on the slope below the line. As the value increases, the dD2 and dD3 form a gentle curve.

The values of dD, dD2 and dD3 are also set after comparison with experimental data.

f1, f2, f3, f4 are exponential functions used to curve straight lines.

That is, in the stacking line correcting step S1-4, a straight line area and a curved area are first determined from the straight line stacking line generated in the stacking line generating step S1-3, and the top point and both sides of the curved area are determined. After setting the position of the lower point, the exponential function is used to smoothly connect the stacking line of the curved area to the straight stacking line of the straight area. At this time, the curve generated in the curved region passes through the upper and lower points.

,

로부터 알 수 있다.(V_t : 슈트출구속도, α_s : 주응력과 전단라인 사이의 각도, g : 중력가속도)The coordinate values (X, Y) of each point constituting the stacked line are stacked line mathematical models

,

(V _t : chute exit velocity, α _s : angle between main stress and shear line, g: gravitational acceleration)

7 is a comparison of the lamination line between the blast furnace scale model and the analysis model according to the present invention. On the other hand, in the lamination line of the analytical model, the mixed layer M generated by mixing the opposing light OL and the coke C can be confirmed. (In the case of the experiment, only the upper surface of the laminated part is measured by using a laser. The location is unknown.)

Meanwhile, the drop line calculation step S2 includes a stacking line observation point setting step S2-1, a charge dropping step S2-2, and a drop stacking line generating step S2-3.

The blast furnace charges are lowered due to egress, and the rate of descent depends on the location due to complex factors such as interparticle friction, friction with the blast furnace walls, differentiation, internal stresses and phase changes. In addition, the particles inside the blast furnace begins to change phase as it passes through the softening zone, and the solid phase and the liquid phase coexist. It is very difficult to consider all of the above, so the present invention assumes that the contents of the blast furnace are all solid, the shape of the core is constant, and there is no charge movement to the core.

The present invention expresses the load drop as the movement (fall) of the lamination line.

Referring to FIG. 8, the process of calculating the drop line of the stacked line SL4 calculated by the drop trajectory and the stacked model (that is, calculated through the stacked line calculating step S1) will be described.

First, the stacking line observation point setting step (S2-1) is performed.

Since the lamination line is composed of a plurality of points, a plurality of observation points are set on the lamination line SL4 at regular intervals. This is to simplify the calculation since it is virtually impossible to interpret the behavior of all the charge particles on the lamination line.

Subsequently, a charge dropping step (S2-2) of lowering the lamination line is performed.

When the stacking line is lowered, the movement amount of the observation points is composed of a vertical component Δy and a horizontal component Δx because the furnace diameter becomes larger as the blast furnace passes the shaft portion.

Thereafter, the drop stacking line generation step (S2-3) is performed.

It calculates the area between the pre-lowdown lamination line SL4 and the post-fall lamination line, converts it to volume and compares it with the actual charging volume, and repeats the calculation until the difference falls within a predetermined range, thereby laminating the post-fall lamination. To determine the location of the line.

The finally generated stacking line is determined as the falling stacking line SL5 of the stacking line SL4 through the calculation process.

9 shows the descent speed of the lamination line (when 19 observation points are set), it can be seen that the descent speed tends to increase from the furnace center to the wall. This is because the blast furnace shaft portion has a shape in which the radius increases downward.

Since it is practically impossible to consider all the factors affecting the dropping speed of the charged material such as the frictional force and the core shape of the actual particle and the wall surface, the present invention sets the dropping speed using the data obtained through the experiment.

FIG. 10 shows the relative drop velocity along the radial direction in the V-type laminated profile, although the drop velocity increases with the type of coke, ore (sinter), alumina ball, etc. It can be seen that the same tendency to. This is consistent with the scale model experiment.

In the present invention, the dropping speed of the particles was determined using the data in Table 1 (relative dropping speed of the furnace center and the furnace wall).

Furnace center
Furnace wall
cokes
0.87
1.07
Ore (sintered ore)
0.90
1.05
Alumina Ball
0.91
1.05
Average
0.89
1.06

11 is a view comparing the laminated shape in the analysis model and blast furnace reduction model experiment according to the present invention.

The results of the analytical model and the blast furnace reduction model show relatively similar laminations. In the case of the reduced model, since the core does not exist and the load drop is made in the horizontal plane, it can be seen that there is a difference in the stacked shape of the core coke and the analysis model that sets the core.

The lamination line is shown in more detail in the lower right of the drawing, and alleles (OL), small particles (OS), coke bases (C) and central coke (CC) exist, and a mixed layer (coke and alleles) is present. It can be seen that M) exists.

As described above, according to the present invention, the lamination line of the charges and the drop state thereof can be accurately known, and thus the stacking profile of the charges can be accurately understood.

In addition, region classification according to each type of light can be made in detail.

Therefore, it is possible to perform a more efficient charge distribution control by accurately grasping the distribution shape of the furnace charges, thereby improving the blast furnace operation efficiency and improving productivity and product quality.

C: Coke (Base) CC: Center Coke
OL: opposing light OS: small light
M: mixed layer

Claims (7)

A charging baseline setting step of setting a charging baseline;
A lamination line generating step of generating a new lamination line according to the charging of the charge above the set charging reference line;
A drop stacking line generation step of setting a observation point on the generated stacking line and dropping the stacking line on which the observation point is set to generate a new drop stacking line;
Laminated profile calculation method of the blast furnace charge containing a. The method according to claim 1,
In the linear stacked line generated in the stacking line generation step, the linear region and the curved region are determined, and the positions of the upper end point and the lower end point of the curved region are determined. The stacking profile calculation method further comprises a stacking line correction step of connecting the stacking line in a curve including the upper point and the lower point. The method according to claim 1,
In the charging baseline setting step, an initial charging baseline is set, a charge is charged to generate a secondary charging baseline, the second charging baseline is lowered, a new initial charging baseline is set, and a charge to the new initial charging baseline Stacking to generate another new charging baseline, and resetting the new charging baseline to the initial charging baseline. The method according to claim 1,
The position of the lamination line generated later with respect to the lamination line first generated in the charging reference line setting step and the lamination line generation step is
Blast furnace charging characterized in that it is set by repeatedly calculating until the two volume values are the same by comparing the volume converted into the volume between the area of the first laminated line and the later generated lamination line in volume Method of calculating the lamination profile of water. The method according to claim 1,
The position of the lamination line generated later with respect to the lamination line first generated in the drop stacking line generation step is
Characterized in that it is set by iteratively calculating until the difference between the two volume values is set by comparing the volume converted into the volume of the area between the first and the second lamination line generated and the later generated lamination line in volume Lamination profile calculation method of the blast furnace charge made. The method according to claim 1,
Stacking profile calculation method of the blast furnace charge, characterized in that the generation of the mixed layer generated by mixing the coke and ore when forming a new stacking line by stacking the charges in the charge baseline setting step and the stacking line forming step . A lamination line calculating step of calculating a lamination line of the charge;
A strong Harein calculation step of generating a strong Harein by lowering the stacked line calculated in the stacking line calculating step;
Laminated profile calculation method of the blast furnace charge containing a.

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