JPH01268808A - Method for operating lowered stock level in blast furnace - Google Patents

Abstract

PURPOSE:To surely execute melting of falled-down stuck material in the furnace and raw ore and to avoid extension of lowered stock level operation time by control ling blasting rate so as to come to uniform blasting condition at each tuyere position and/or raising combustion temp. before the tuyere. CONSTITUTION:In each branch pipe 4 branched from circular pipe 3 to the tuyere 2, a blasting control valve 7 and a flow meter 14 are arranged. When the blasting rate and the temp. at one or more tuyere 2 positions in each flow meter 14 are extreme ly dropped to lower than these of the other positions, it is assumed that the fall-down of the above stuck material M or level-down of the raw ore R is developed at these tuyere 2 positions. In this case, one means or both paralleled are executed whether the objective tuyere 2 is controlled so that the blasting condition comes to uniform at each tuyere 2 position by making opening degree of the blasting control valve 7 large, etc., and/or the combustion temp. before the tuyere 2 is raised by enriching oxygen in the branch pipe 4 under bad blasting condition through an oxygen supplying pipe 9. By this method, the melting of the above stuck material M or the raw ore R is promoted to be possible to make the same blasting condition as that of the other position and the extension of the lowered stock level operation time can be avoided.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for reducing the size of a blast furnace.

[Conventional technology]

As is well known, the scale reduction operation is a method that replaces all of the contents in the furnace with coke and gradually reduces the scale to almost the tuyere level during blast furnace renovation or intermediate repair.

In such scale reduction operations, it is important to equalize the air blowing from each panel until the end of scale reduction.

However, in actual operations, local shedding or falling of furnace wall deposits or raw ore may disrupt the air blowing conditions in that area, eventually causing a drop in temperature, blocking of the hot metal slag flow path, etc. Hot metal slag flows back into the tuyere, clogging the tuyere and eventually making it impossible to blow air. As a result, it became impossible to consume the coke in the furnace and melt the iron ore, etc. in the above-mentioned area, and the unloading of raw materials was stopped, making it impossible to reduce the size, and eventually the contents, including semi-molten iron ore, Causes local residue.

Leaving a large amount of residue in the furnace in this way becomes a major hindrance to the subsequent work of scraping out the residue in the furnace, and becomes a major bottleneck especially during intermediate repairs where the work must be completed in a short period of time.

In order to avoid the above situation, the first method is to clean the inside of the furnace in advance to remove deposits on the furnace wall. A second possible method would be to temporarily stop the reduced scale operation when tuyere blockage occurs, then charge more coke, prepare the blast nozzle and tuyere, and then start blowing again. .

[Problem to be solved by the invention]

However, in the first method described above, even if preliminary cleaning is performed, its implementation effect is low, and implementation requires a great deal of effort and cost. Furthermore, in the second method, the reduction operation time is extended by the amount associated with its implementation, and there is a risk that the problem will reoccur later.

Therefore, the main purpose of the present invention is to prevent troubles such as tuyere clogging during scale reduction operations, and to enable uniform gas flow and reduction in the circumferential direction, as well as to avoid problems seen in conventional examples. It is an object of the present invention to provide a scale reduction operation method that can avoid an extension of the scale reduction operation time and an increase in costs associated with cleaning.

[Means to solve the problem]

The above problem is to understand the ventilation condition for each tuyere position based on at least the current flow rate of the air flow rate passing through each ventilation branch pipe and the temperature in front of each tuyere, and to determine whether this ventilation condition is at each tuyere position. During reduced-scale operation, control the flow rate of air from each tuyere so that it is uniform, and/or enrich the air branch pipes with poor ventilation with oxygen to increase the combustion temperature before the tuyere. This can be solved.

[For production]

According to the present invention, if the air flow rate in each air blowing branch pipe is known, air blowing conditions may deteriorate if deposits in the furnace fall off before the tuyeres or raw ore falls, so conversely, it is possible to It is possible to detect the falling off of deposits inside the furnace and the falling of raw ore. If the air flow rate drops extremely at a certain point in the circumferential direction, it can be determined that this phenomenon has occurred.

However, based on this judgment result, if the air flow rate is increased and/or oxygen enrichment is performed when the phenomenon is estimated to be occurring, the deposits or raw ore that have fallen off inside the furnace will be removed. The dissolution of the material can be promoted, and the ventilation conditions can eventually be made uniform in the circumferential direction. Therefore, by implementing this measure in conjunction with other scale reduction operation control elements, it is possible to reliably prevent deposits in the furnace, raw ore remaining in the furnace, clogging of the siding, etc.

On the other hand, according to the findings of the present inventors, increasing the amount of hot air alone may have little effect; therefore, increasing the combustion temperature before the tuyere,
For example, when oxygen enrichment is used in combination, it is possible to more reliably melt deposits in the dropping furnace and raw ore.

[Specific structure of the invention]

The present invention will be explained in more detail below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a blast furnace, of which 28 tuyeres 2 are formed, for example, as shown in FIG. ．．
4... are in a row. Reference numeral 5 denotes a hot blast furnace, which heats air supplied by a blower 6 and sends hot air to the annular blast pipe 3 through a main blast pipe 6. In addition, each blower branch pipe 4.4... has a blower control valve 7, 7 whose opening degree is variable.
... are provided for each.

Although the above-mentioned equipment is basically known, in the present invention, the oxygen supply pipe 9 is connected to the blower branch pipe 4 as shown in FIG.
, 4.... The oxygen supply pipe 9 is used to send oxygen from an oxygen holder 11 using a blower 12, and a flow rate regulating valve 13 is provided in the middle of the pipe. 14 is a flow meter provided in each blower branch pipe.

On the other hand, a radiation thermometer 15 is provided at the rear end of the linear portion of each blower branch pipe 4, and is adapted to measure the temperature of the contents in the furnace based on the brightness. Further, if necessary, furnace wall thermometers 16 are provided on the tuyere 2 in the circumferential direction, for example, in the same number as the number of tuyeres.

The following scale reduction operations are carried out under the above equipment. In other words, as shown in Fig. 1, the level of the contents in the furnace initially increased;
, and when reducing the scale, the level L2 is
In the process of reducing the size to
Detected by 5. If the air flow rate at one or more tuyeres of each flow meter 14 is extremely lower than other locations, the fall of deposits M in the furnace and the unloading of raw ore R at that tuyere are It is estimated that there was. Furthermore, the same estimation is performed even when the temperature in a certain part of the lining is extremely lower than in other parts.

In this case, for the corresponding tuyere 2, the opening degree of the blow control valve 7 is increased, or the opening degree of the corresponding tuyere remains the same but the other tuyere opening degrees are decreased, or oxygen is supplied via the oxygen supply pipe 9. The addition may be carried out by one of the means or in parallel. This promotes the dissolution of deposits M in the falling furnace and raw ore R, and eventually the same ventilation conditions as other parts can be achieved.

In the above example, the temperature signal from the furnace wall thermometer 16 may be used as information for determining whether or not the in-furnace deposits M have fallen off.

Also, since there is originally a viewing window at the position of the radiation thermometer 15,
An operator may look through it and judge the falling ring of the matter M attached to the furnace wall.

〔Example〕

Next, examples will be shown.

Reduced scale operation in a blast furnace with a capacity of 2100m" with a total air flow of 1
20 ONm"/min, as shown in Figure 5, the air flow rate of the tuyere of patient 5 decreased, so
~ When the flow control valve of patient 6's ventilation branch pipe was left fully open and the opening of other valves was reduced from 100% to 60%, N115 was detected.
The amount of air blown at the tuyere gradually increased, and it was assumed that the melting of the deposits inside the furnace was completed. At the time of completion, the opening degrees of the valves other than Kan 4 to 6 were set to 70%, and then all the valves were fully opened, and the ventilation conditions became almost uniform.

Later, as shown in Figure 6, raw ore descent occurred near the 3 affected tuyeres, so oxygen enrichment was carried out to increase the amount of oxygen by 1% at the 2nd to 4th affected tuyeres, and the 3 affected tuyere The temperature in front of his mouth gradually increased.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to prevent troubles such as tuyere clogging during scale reduction operation, to ensure uniform gas flow in each part in the circumferential direction, and to increase the time of scale reduction operation. This provides advantages such as extending the time period and avoiding the need for cleaning.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of the equipment for carrying out the method of the present invention, Figure 2
The figure is a detailed cross-sectional view of the tuyere part, Figure 3 is a vertical cross-sectional view of the formation of deposits in the furnace, Figure 4 is a horizontal cross-sectional view, and Figures 5 and 6 are examples of operation in the example. It is a graph. 1... Blast furnace, 2... Tuyere, 3... Air blowing annular pipe, 4
...Blower branch pipe, 5...Hot stove, 7...Flow rate adjustment valve, 9...Oxygen supply pipe, 11...Oxygen holder, 13
...Flow rate adjustment valve, 14...Flow meter, 15...Radiation thermometer. Patent applicant: Sumitomo Metal Industries, Ltd. Figure 1 Figure 2

Claims (1)

[Claims] (1) Understand the ventilation condition for each tuyere position based on at least the current flow rate of the air flow rate passing through each ventilation branch pipe and the temperature in front of each tuyere, and ensure that this ventilation condition is uniform at each tuyere position. Control the flow rate of air from each tuyere so that
and/or a method for reducing the size of a blast furnace, characterized in that during the reduced size operation, enriching the blower branch pipes with poor ventilation conditions with oxygen to increase the combustion temperature before the tuyere.