JPH0424403B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for estimating the particle size of a charge during charging into a blast furnace, and more particularly, the present invention relates to a method for estimating the particle size of a charge in a top bunker of a bellless blast furnace. This invention relates to a method for measuring the distribution and estimating the change in particle size of the charge being charged from the top bunker into the blast furnace based on the measured value.

In blast furnaces, instead of the method of charging materials into the blast furnace by opening and closing a large bell and a small bell, in recent years, the method of distributing and charging material through a rotating and tiltable distribution chute without using a large bell or a small bell has been replaced. Bell-less type furnace top charging devices have come into widespread use.

As shown in FIG. 1, this bell-less furnace top charging device transfers raw materials, or charges, to a blast furnace belt conveyor 1, a switching chute 2, an upper gate valve 3,
The charge is temporarily stored in the top bunker 5 through the upper seal valve 4, and when the charge in the blast furnace 10 is unloaded and reaches the level of a predetermined stock line 6 to be replenished, the charge is released. The lower gate valve 7 and the lower seal valve 8 for quantity adjustment are opened to supply the charge in the top bunker 5 to the distribution chute 9, and the rotation speed and tilting angle of the distribution chute 9 are adjusted to complete loading. The materials are sequentially and continuously distributed and charged into the furnace from a distribution chute 9.

However, when charging materials into a blast furnace using such a bellless furnace top charging device, there are the following problems. That is, the charge (coke or ore) with a certain particle size composition is placed in the top bunker 5.
Inside the furnace, the grain size is deposited with grain size segregation in the radial direction, and the grain size of the charge charged into the furnace via the distribution chute 9 changes over time. Therefore, even if the charging conditions such as charging pattern and stock line charging amount are constant, if the grain size of the burden changes over time during charging into the furnace, the grain size of the burden in the radial direction inside the furnace will change. Since the diameter distribution changes, the air permeability distribution changes and the gas flow distribution changes. As a result, the furnace conditions become unstable, causing slips (unstable descent of the charge), fluctuations in furnace heat, fluctuations in hot metal composition, etc.

The present invention was created in view of this problem, and its purpose is to measure in advance the particle size distribution in the radial direction and circumferential direction of the charge charged into the furnace top bunker. The object of the present invention is to obtain a method for estimating the change in grain size of the charge during charging into a blast furnace.

The present invention provides an imaging device such as a television camera in the top bunker of a bellless blast furnace, and the grain size of the charge placed in the top bunker in at least one of the radial direction and the circumferential direction by the imaging device. and is configured to measure the particle size distribution and estimate a change in particle size of the charge being charged from the top bunker into the blast furnace based on the particle size distribution and a charge flow model in the top bunker. There is.

Next, before going into description of embodiments of the present invention, the principle of the present invention will be explained with reference to FIGS. 2 and 3.

When charges are charged into the furnace top bunker 5, the charges with small particle sizes gather near the point where the charges fall, and the particle sizes increase as they move away from there.
Therefore, if the falling point is approximately at the center of the furnace top bunker (hereinafter simply referred to as the bunker), the charge will rise to a mountain-like height at the center of the bunker, as shown in Fig. The particle size of the charge is small, and tends to become lower and larger in the radial direction as it approaches the outer periphery of the bunker.

When discharging the charges charged in this way from the bunker, assuming a funnel flow in which the raw material at the top of the discharge port is first discharged and then discharged from the upper layer to the lower layer, the flow will be as follows: As shown in Fig. 3, the inner part of the conical surface 11 indicated by the discharge angle θ' at the upper part of the discharge port is discharged from the bottom in the order of ~, and based on the discharge, the central part of the charge is depressed. Then, the outer peripheral part of the conical surface flows into the depressed part in the order of ~ from the top and is discharged (FIG. 3B, C), and finally the part marked ○10 is discharged.

Therefore, if you measure the grain size in the area from 〇10 shown in Figure 3 in advance, you can use the measurement results and the above flow model of the charge in the bunker (hereinafter referred to as the bunker model) to calculate the particle size. , it is possible to estimate the change in grain size of the charge from the beginning to the end of the flow when the charge is charged into the blast furnace from one bunker.

Therefore, in the upper part of the bunker 5, as shown in FIG.
Alternatively, the flow diameter distribution in the circumferential direction is measured in advance using an image.

From this measurement result and the bunker model, the change in particle size is estimated as described above.

Next, referring to FIG. 5, an embodiment of the present invention carried out using an actual large-scale model experimental device will be described.

The top bunker 5' of the model experiment equipment has a diameter of 6 m.
The outlet diameter is 1.7m and the volume is ^95m3 . When 148 tons of sintered ore corresponding to one charge was charged into this bunker 5', the distribution of grain size in the diametrical direction of the charge in the bunker was measured by a TV camera installed at the top of the bunker. As a result of measurement using image analysis performed by photographing with a camera (not shown) and sampling inside the furnace, the values were as shown in FIG. 6. As is clear from the graph in Figure 6, the results measured by image analysis using a television camera (indicated by the broken line in the figure) and the results of sampling inside the furnace (indicated by the black dots in the figure)
It can be seen that there is good agreement.

Next, when the charge is discharged from the discharge port at the bottom of the bunker 5' and charged into the furnace 10', the particle size change of the charge is calculated using the bunker model using the above particle size distribution measurement results as input. The result was as shown by the solid line in Figure 7. In addition, in the bunker model calculation, the loading position P inside the bunker uses the actual measured value, the charging material accumulation angle θ is 30 degrees, the discharge angle θ' at the top of the discharge port is 90 degrees, and the angle θ'' at which the material is discharged sequentially from the upper layer is 70 degrees. Calculated in °.

Further, during charging from the bunker into the furnace, samples were taken below the distribution chute 9' to measure changes in particle size, as shown by black dots in FIG. As is clear from the graph of FIG. 7, the bunker model calculated values and the actual measured values agree well, proving the effectiveness of the bunker model.

Next, a method of utilizing the particle size deposition method according to the present invention in blast furnace operation will be explained.

For example, if the particle size composition of the charge changes and the grain size segregation in the bunker increases, the change in particle size of the charge during charging into the blast furnace will increase, and the charge will be charged sequentially from the furnace wall through the distribution chute. It is expected that particle size segregation in the blast furnace will also increase due to the charging process. When grain size segregation in the blast furnace increases, the ventilation resistance of the furnace wall increases, gas flows more easily through the center of the furnace, and the gas flow distribution changes.

In this case, if you take into account the change in grain size calculated using the bunker model and change the charging pattern to either charge more coke on the furnace wall or charge more ore in the center of the furnace, the gas flow will increase. The distribution can be kept constant.

As described above, according to the method of the present invention, when charging material into a blast furnace using a bellless furnace top charging device, changes in grain size over time from the start to the end of charging can be monitored. This makes it possible to estimate values close to the actual values, which can greatly contribute to the stable operation of blast furnaces.

[Brief explanation of drawings]

Figure 1 is a schematic explanatory diagram of a bell-less furnace top charging device, Figure 2 is a diagram showing the state of charge accumulation in the furnace top bunker, Figure 3 is an explanatory diagram of the bunker model, and Figure 4 is a diagram of the bunker. Figure 5 is a schematic diagram of the actual large-scale model test equipment, and Figure 6 shows the radial particle size distribution of the charge inside the bunker. The graph shown in FIG. 7 is a graph showing changes in the particle size of the charge discharged from the bunker, and is a graph showing a comparison between the results estimated by the present invention and the results actually measured by sampling.

Claims (1)

[Claims] 1. A photographing device such as a television camera is installed in the top bunker of a bellless blast furnace, and the grain size distribution of the charge placed in the top bunker is measured in at least one of the radial and circumferential directions using the photographing device. Blast furnace charging characterized in that the change in particle size of the charge being charged from the top bunker into the blast furnace is estimated based on the particle size distribution and the charge flow model in the top bunker. Method for estimating the particle size of the charge inside.