JPH05148519A - Method for detecting activating condition in furnace core in blast furnace operation - Google Patents

Abstract

PURPOSE:To recover a furnace condition for short peried and to stabilize the blast furnace operation by detecting a tendency deteriorating the activating condition in the furnace core at early time. CONSTITUTION:A detecting material 31 containing Co, Ni, Cu, Cr, etc., is inserted in the furnace core 22 from a tuyere 11 in the blast furnace during the operation. The detecting material 31 is dropped clown into a basin part 24 together with the liquid drips 21 of molten iron, molten slag, etc., after melting and then, discharged from an iron tapping hole 12 together with the molten iron. By analyzing the components in the molten iron, the time which the detecting material 31 inserted in the furnace core 22 is stayed in the furnace, is decided, and from the length of the staying time, the activating condition in the furnace core 22 is detected. When the tendency of tengthening of the staying time is observed, the operational condition activating the furnace core is adopted. As the activating condition in the furnace core can precisely and periodically be detected, the tendency deteriorating the liquid penetration can be found at the initial stage and the recovering treatment of the furnace condition can be applied at the early time. Therefore, the blast furnace can be operated in the high operating efficiency without lowering the productivity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting an active state of a core required for operating a blast furnace while maintaining good ventilation and liquid permeability in the core.

[0002]

2. Description of the Related Art When the air permeability / liquid permeability of a furnace core existing in a blast furnace is deteriorated, the air permeability in the furnace is deteriorated and the tap ratio is lowered. Furthermore, if the phenomenon progresses, serious troubles such as cooling will occur. Therefore, maintaining the ventilation and liquid permeability of the furnace core is essential for stable blast furnace operation. In particular, in blast furnace operation that emphasizes high tap ratio, it is important to maintain ventilation and liquid permeability.

The air permeability and liquid permeability of the furnace core depend on the amount of powder coke accumulated in the core coke layer. For example, as the amount of coke powder increases, the air permeability and liquid permeability of the furnace core deteriorate. Therefore, in order to maintain good ventilation and liquid permeability, it is necessary to keep the amount of powdered coke accumulated low. Therefore, when recovering the deteriorated ventilation and liquid permeability, operating conditions such as increase of coke ratio, change of insert distribution, increase of blast moisture content are adjusted.

For example, there are a method of selectively inserting coke into the center of the blast furnace, a method of increasing the moisture content of the air blown from the tuyere, and the like. However, these methods have the drawback of increasing the coke ratio, and therefore cannot be carried out continuously. Moreover, it takes a long period of several months to return the liquid permeability to a healthy level.

Therefore, it is conceivable to perform selective charging of coke or blowing of high-humidity air at an early stage when signs of deterioration of air permeability and liquid permeability of the furnace core are observed. However, the core is present inside the furnace, and it was difficult to predict the precursor of deterioration of air permeability and liquid permeability of the core by sensors provided on the side wall of the furnace body.

As a means for grasping the core condition, there is a tuyere coke sampler, a core sonde, or the like. The coke in the furnace core can be sampled with a tuyere coke sampler, and the amount of powder coke accumulated can be measured. In addition, the core SONDE is used to directly observe the core of the operating blast furnace. When using a coresonde, a small amount of core contents is obtained along with information such as raceway and core temperature, gas composition and pressure.

[0007]

However, the tuyere coke sampler can be used when the blast furnace is blown off, and is not suitable for observing the core condition during operation.

On the other hand, it is impossible to accurately grasp the condition of the furnace core by the measurement using the furnace core sonde. For example, the temperature inside the core may decrease at the stage when the air permeability and liquid permeability of the core have deteriorated. In addition, the temperature inside the furnace core may decrease due to the endothermic reaction of unreduced FeO dropping and its reduction reaction despite the fact that the furnace core is in an active state with good ventilation and liquid permeability. Furthermore, it is not possible to judge the air permeability / liquid permeability in the furnace core from the amount of the contents in the furnace and the gas composition in the blast furnace in operation.

As described above, there is no known method for properly determining the air permeability / liquid permeability of the furnace core. For this reason, the activity of the core is estimated from experience or data accumulated in the past, and the blast furnace is operated according to the estimated activity.

The present invention has been devised to solve such a problem. By directly grasping the active state of the furnace core, the tendency can be detected at an early stage when a tendency of deterioration is observed. The purpose is to operate the blast furnace in a stable furnace condition.

[0011]

In order to achieve the object, the method for detecting the activated state of the furnace core of the present invention has an object to achieve the object from elements such as Co, Ni, Cu and Cr from the tuyere of the blast furnace during operation to the inside of the furnace core. It is characterized in that the time until the element is discharged after the detection material containing is inserted is measured, and the fluctuation of the activity of the furnace core is determined based on the length of the measured time.

[0012]

The present invention will be described in detail below with reference to the drawings together with the operation. The present invention is carried out by using, for example, a blast furnace having an equipment configuration schematically shown in FIG. A tuyere 11 is provided on the bottom side wall of the blast furnace 10, and a taphole 12 is provided below the tuyere 11. Hot air such as high-temperature oxygen-enriched air is blown from the blower branch pipe 13 attached to the tuyere 11.

Inside the blast furnace 10, ore raw materials, auxiliary raw materials, etc. charged from the furnace top are sequentially subjected to a reduction reaction and descend in the furnace as droplets 21 of molten slag, hot metal, etc. To reach. A raceway 23 is formed around the furnace core 22 by the hot air blown from the tuyere 11.

The tuyere sonde 30 is inserted into the blast furnace 10 from the rear end side of the blower branch pipe 13 until the furnace core 22 is reached.
At the tip of the tuyere sonde 30, a detection material 31 containing elements such as Co, Ni, Cu, Cr is attached. The detection material 31 remains inside the furnace core 22 when the tuyere sonde 30 whose tip has reached the furnace core 22 is pulled out of the furnace, and is melted by the heat in the furnace. The melt generated by melting the detection body 31 is
Droplets 21 such as molten pig iron and molten slag are dropped into a pool 24 and discharged from the tap hole 12 to the outside of the furnace.

As the detecting material 31, Co, Ni, Cu,
Metal lumps containing elements such as Cr, ferroalloys, mineral powders, compounds, etc. are used. A material containing one or more elements of Co, Ni, Cu, Cr and the like can be used as the detection material 31.

Metal elements such as Co, Ni and Cu are originally
Almost not contained in hot metal. Therefore, when a ferroalloy, an ore, a compound or the like containing these metal elements is inserted into the furnace as the detection material 31, it is melted after a certain period of time, and the concentrations of Co, Ni, Cu and the like in the hot metal increase.
This increase in concentration can be known by analyzing the components of the hot metal discharged from the tap hole 12. Therefore, by measuring the change over time in the concentration, it is possible to determine the residence time in the furnace after the detection material is inserted, and then melted and dropped, and then discharged.

Further, even for elements such as Cr, which are usually contained in the hot metal, the fact that the concentration in the hot metal that has been tapped out is higher than the steady value can be used within the range that does not adversely affect the furnace conditions. It can also be used as a detection material.

The relationship between the core active state and the Co residence time will be described by taking the case of using Co as an effective element of the detecting material as an example. The residence time of Co in the furnace when the activity of the furnace core is high is a relatively short time as shown in FIG. 2 (a). Further, the Co concentration in the tapped hot metal also fluctuates in a short cycle. That is, the inserted C
Almost all of o is discharged in a short time.

On the other hand, when the furnace core is in an inactive state, the residence time until the inserted Co is discharged is long as shown in FIG. 2 (b). Moreover, the Co concentration of the discharged hot metal fluctuates over a long period of time.
It does not follow the sharp variation curve shown in (a).
This indicates that the residence time becomes longer as the liquid permeability in the furnace core deteriorates. In particular, when the liquid permeability inside the furnace core is extremely reduced as the air permeability inside the furnace is deteriorated, the residence time becomes abnormally long. Moreover, only a small amount of Co charged is discharged to the outside of the furnace.

That is, Co contained in the discharged hot metal
The fluctuation of the concentration is data that accurately represents the activated state of the furnace core. Therefore, the retention time of Co is regularly measured, and when the retention time tends to be long, the initial stage in which the liquid permeability of the furnace core tends to deteriorate can be known. If operating conditions for liquid permeability recovery are adopted at this point, liquid permeability will be restored in a short time, and blast furnace operation under stable furnace conditions will be possible.

[0021]

[Example] The internal volume of the furnace is 21 at a tap ratio of 2.3 tons / m ³ · day
When operating a 50m ³ blast furnace, the Co content is 50%
40 kg of the metal lump of No. 2 was inserted into the core every 7 days using a tuyere sonde. Changes in the operating specifications and the residence time of Co at this time are shown in FIG.

Initially, the residence time of Co was 40 minutes. When the blast furnace operation exceeds 21 days, the residence time of Co tends to be long. And the number of operating days is 2
At 8 days, the residence time of Co increased to 58 minutes. At that point, when the coke ratio was increased by 20 kg / THM, the residence time of Co decreased to 40 minutes after 7 days. Therefore, the coke ratio was set to the original level of 400 Kg / TH.
Returned to M and continued operation. The PC ratio was maintained at a constant value of 100 Kg / THM throughout the entire period.

Throughout the entire operation period, no deterioration of air permeability was observed, and the tap ratio could be maintained at 2.3 T / m ³ · day. As is clear from this, since the tendency of deterioration of liquid permeability can be known at an extremely early stage, it is possible to operate the blast furnace with a high tap ratio without requiring a long period of time to recover the furnace condition.

[0024]

As described above, in the method of the present invention, the active state of the core is accurately and regularly detected based on the time until the detection material inserted into the core is discharged. is doing. As a result, it is possible to accurately grasp the initial stage when the furnace core begins to be inactivated, and it is possible to take operating conditions necessary for the recovery of the furnace condition at an early stage. As a result, it is possible to operate the blast furnace with high productivity without requiring a long period of time to recover the furnace condition.

[Brief description of drawings]

FIG. 1 is a schematic view showing a main part of a blast furnace in which the present invention is implemented.

FIG. 2 is a graph showing the effect of the active state of the furnace core on the residence time of Co.

FIG. 3 is a graph showing the relationship between operating specifications and the residence time of Co in the example of the present invention.

[Explanation of symbols]

10 Blast Furnace 11 Tuyere 12 Taphole 22 Furnace Core 30 Tuyere Sonde 31 Detection Material

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Okusu 11-1 Showa-cho, Kure City, Hiroshima Prefecture Nisshin Steel Co., Ltd. Steel Research Laboratories (72) Toshio Yanagawa 11-11 Showa-cho, Kure City, Hiroshima Prefecture New Steel Co., Ltd. Steel Research Laboratory

Claims (1)

[Claims] 1. Co, N from the blast furnace tuyere during operation to the core
After inserting a detection material containing an element such as i, Cu, or Cr, the time until the element is discharged is measured, and the fluctuation of the activity of the furnace core is determined based on the length of the measured time. A method for detecting a core active state in a blast furnace operation, which is characterized by the above.