JP2694590B2 - Method for diagnosing core active state and method for core activation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides means for promptly diagnosing the active state of the core, which is important for stable operation of the blast furnace, during operation, and for activating it when the core is diagnosed as inactive. The purpose is to provide.

[0002]

2. Description of the Related Art In blast furnace operation, it is very important to accurately grasp the reaction conditions in the furnace and control the operating conditions such as blast temperature, blast humidity, coke ratio, and distribution state of charging raw materials. In order to judge the reaction status in the furnace, a lot of data such as temperature of each part of the blast furnace, gas components, gas flow rate, and dropping condition of the charge are collected. In particular, the condition of the furnace core is very important, and attempts have been made to understand the condition.

The core of the furnace is formed by depositing coke, and its porosity is about 0.5 when the operation of the blast furnace is stable. As a result, the molten pig iron and molten slag that have been melted and dropped pass through the core of the furnace and accumulate at the bottom of the furnace. Further, the temperature of the furnace core can be maintained by the air blown from the tuyere reaching the center of the furnace. Therefore, it is important to secure the air permeability and liquid permeability of the core, that is, to keep the core active. The core serves as a heat buffer in the lower part of the furnace, and at the same time has a great influence on the heat transfer efficiency of the charge and gas in the lower part of the furnace. In particular, when the core temperature is low, the amount of slag / metal staying inside the core increases and the ventilation resistance inside the core increases, so the gas inflow into the core decreases and the core temperature further decreases. Is reduced.

In recent years, due to the increase in the proportion of the core in the lower part of the furnace due to the increase in size of the blast furnace, and the generation and accumulation of high O / C and unburned char due to the increase in the amount of fuel injected from the tuyere,
There is concern about the enlargement of the core and the decrease in core temperature.
When an unmelted fusion layer is laminated on the surface layer of the core, the core expands and the descent area of the charge in the lower part of the furnace decreases, so the residence time of the charge in the lower part of the furnace decreases. The temperature rise of the charge is delayed. In that case, there is a high possibility that the charge will flow into the raceway unmelted and the heat of the furnace will drop significantly, leading to a poor reactor condition.

From the above viewpoint, the core temperature is measured, but its method is limited due to the high temperature and the weight of most of the contents inside the furnace. That is, there is known a method in which the coke forming the furnace core is sampled from the tuyere to obtain the coke hysteresis temperature obtained from the measured value of the crystallinity, and in Japanese Patent Laid-Open No. 61-257405, the tuyere or A method is disclosed in which a probe having a water-cooled structure is inserted into the furnace core from the side wall of the lower part of the furnace and an optical thermometer is connected by a glass fiber to measure the temperature of the furnace core at a certain distance from the tip of the tuyere.

[0006]

Among the above-mentioned methods for measuring the temperature of the core, the method based on the history temperature of coke requires a long time for measurement and does not necessarily reflect the state of the core at that time. In this respect, the method disclosed in JP-A-61-257405 is excellent as a method for measuring the core temperature itself,
It was found that further investigation is needed to more directly grasp the active state of the core. That is, it is considered that the temperature of the furnace core itself becomes inactive when it becomes about 1400 ° C. or lower, but since it also changes depending on operating conditions such as low Si operation, the temperature of the furnace core alone may lack information.

That is, as described above, the activated state of the furnace core means a state in which the air permeability and liquid permeability of the furnace core are ensured, and the temperature of the furnace core portion decreases This is a result of the fact that the ventilation from the tuyere could not reach the central part of the furnace due to the reduced air permeability. Therefore, it can be said that it is important for stable operation of the blast furnace to grasp the active state of the core and take more effective action before the core temperature actually drops to the state where the core condition is poor. The present invention aims to solve this problem.

[0008]

Means for Solving the Problems The present invention is to solve the above problems, and when the blast furnace is in a blast, a lance inserted from the tuyere into the core of the blast furnace is used to provide hot air or oxygen-rich gas in the furnace. A method for diagnosing an active state of a furnace core is characterized in that the activated air is blown, and a judgment is made based on an amount of temperature rise in a certain time after a certain distance from the lance due to the blowing.

When the furnace core is diagnosed to be inactive by the method for diagnosing the core core activation state, heating means is supplied to the core core through the lance used for the diagnosis to heat the core core. Characteristic, or extracting the lance used for the above diagnosis, inserting a heating lance or a plasma torch in the relevant part, and supplying heating means into the core to heat the core, or Bosch of the blast furnace Inserting a heating lance or a plasma torch through the opening provided in the lower part of the furnace below the level, and supplying the heating means into the core during idle or blowing to heat the core. It is a method of conversion.

[0010]

As described above, the present inventors have paid attention to the fact that the air permeability / liquid permeability of the furnace core, that is, the activity is lowered first, which results in a decrease in the temperature of the furnace core. A method for diagnosing the activity of the core by a quick and simple method was found. That is, when the blast furnace is off, a lance is inserted into the core from the tuyere to blow hot air or oxygen-enriched air. In this case, the air or oxygen-enriched air is preheated to above 500 ° C. Then, since the ignition temperature of the coke has been reached, the temperature of the portion where the air or the like has reached rises due to the combustion of the coke. The higher the heating temperature, the higher the coke combustion temperature, which is effective, but technically 2000 ° C.
Place is the limit.

At this time, the powder ratio of the furnace core rises, for example, 3
If it exceeds 0%, the air permeability will be poor and the air blown into the core will not reach. Therefore, it was found that the activity of the furnace core can be accurately reflected by measuring the temperature rise in the portion a certain distance away from the tip of the lance, for example, the temperature rise 1 m ahead in a certain time. The amount of air blown in is 500 to 2000 Nm ³
/ H is good. If it is less than this, the measurement cannot be performed sufficiently, and if it is more than this, not only is it useless, but the determination of the activity of the core becomes inaccurate.

For the temperature measurement, a method of inserting a thermocouple at a measuring point, a method of inserting a glass fiber and connecting an optical pyrometer to the measuring point, and the like can be applied. It is most preferable to insert the temperature detection end into a predetermined site separately beforehand because the temperature rise due to blowing into the same site can be continuously observed.
However, in the normal operation, the purpose can be achieved even by inserting the lance and the temperature detecting end alternately.

FIG. 1 shows 500 ° C. from the lance inserted in the tuyere.
2 shows the progress of temperature rise at a position 1 m from the tip of the lance when the above air is blown into the furnace core at a speed of 1000 Nm ³ / h. This shows a time course of temperature in a typical core active state and core inactive state. Under these conditions, it can be judged from the results of the test shown in FIG. 2 that it is possible to diagnose that the core is active when the temperature rise amount after 120 minutes is 120 ° C. or higher and inactive when it is 60 ° C. or lower. That is, FIG. 2 shows the relationship between the amount of temperature increase after 30 minutes under the same conditions as in FIG. 1 and the powder rate of -3 mm powder coke in the furnace core. It can be seen that when the coke powder ratio exceeds about 30%, the temperature rise becomes extremely low.

The amount of temperature rise depends on the type of gas such as air and oxygen-enriched air and the preheating temperature. When the oxygen in the air is enriched, the combustion temperature of the coke becomes higher, so the temperature rises more. However, the combustion temperature is 2 even with air as it is.
Since the temperature is about 000 ° C., which is sufficiently higher than the temperature of the furnace core itself, there is no particular problem in measurement.

The present invention further defines a measure to be taken when the furnace core active state is diagnosed as inactive as a result of the diagnosis as described above. That is, in this case, the heating means is fed by pushing the lance or probe into the furnace core. For this, heating may be performed using the lance used for diagnosing the active state of the core as it is, or the lance used for diagnosis may be extracted and a heating lance or plasma torch may be inserted at that location. . In this case, in principle, the blast furnace heats up when there is no air flow, but it can be done even if the air is blown only at the tuyere with a lance inserted. Further, an opening may be provided in the lower part of the furnace below the Bosch level of the blast furnace, and a heating lance or a plasma torch may be inserted from there. In this case, a heating lance or the like can be inserted while being inclined toward a target position of the furnace core. This method is suitable for heating the core of the blast furnace not only when there is no air, but during blowing of the blast furnace. However, in any case, it is necessary to provide an appropriate gas seal when inserting a lance or the like into the blast furnace.

As a heating means, a method of blowing hot air, oxygen-enriched air, or the like can be used. The gas heating can be performed by a heat exchange device, but it is preferable to use a plasma generator because the temperature can be raised to 1000 ° C. or higher. Also, by mixing oxygen gas with the combustion high temperature gas, the same effect as that of heated air can be obtained. A means for heating the core of the furnace with sensible heat of the high temperature gas burned at the tip of the lance by supplying a combustion material such as liquid, gaseous fuel, powdered fuel and air or oxygen-containing gas from the lance, or developing this high temperature gas. A means for burning a part of the core coke while heating the core with heat and excess oxygen can also be used.

In order to efficiently perform the above heating on the core, it is preferable to actively excavate the core depending on the inertness of the core. That is, when the inertness of the furnace core is mild, it is possible to heat the fed heated air etc. by diffusing inside the furnace core, but it is possible to heat it by a mechanical method such as pushing in the lance when the porosity is significantly reduced, It is advisable to increase the temperature of the core of the furnace core by a method such as aggressively conducting excavation by burning coke with high-temperature gas. However, in the method for diagnosing the active state of the core of the present invention, it is significant to discover before the inactivity of the core becomes serious, so if this diagnostic method is applied appropriately, at least large-scale core excavation will be performed. The furnace core can be activated without

[0018]

【Example】

Example 1 The method for diagnosing the activated state of the core and the method for activating the core of the present invention were applied to a blast furnace having an internal volume of 3880 m ³ . FIG. 3 is a diagram showing a method for diagnosing the core active state and a method for activating the core. As shown in this figure, a water-cooled blower lance 1 having an outer diameter of 125 mm was inserted from the tuyere 3 by the insertion carriage 2 when the wind was resting. In FIG. 3, 10 is a blast furnace, 11 is a cohesive zone, and 1 is
Reference numeral 2 is a furnace core, 4 is a heat exchanger, 5 is a plasma heating device, and 6 is a compressor. As for the heating temperature of the gas, either the heat exchanger or the plasma heating device is operated, the valve 7,
It can be adjusted by changing the flow rate at 8. When taking in air directly, the compressor 6 is operated,
It is not necessary when supplying pressurized gas.

In this manner, the air heated to 500 ° C. was blown at 1000 Nm ³ / h with the tip of the blowing lance 1 positioned 1.6 m from the tip of the tuyere 3. As a result, the temperature rise amount after 30 minutes at a distance of 1 m from the tip of the blowing lance was 33 ° C., so it was determined that the furnace core was inactive. Then, 30% oxygen-enriched air heated to 600 ° C. was blown from the above lance at 5000 Nm ³ / h. One hour later, the lance was pulled out and the air flow was started to allow stable operation.

Example 2 When the activated state of the core was diagnosed by the same method as in Example 1, the temperature rise amount was 45 ° C. 30 minutes after 1 m from the tip of the blowing lance, so the core was inactive. I decided. Therefore, the lance is taken out, another non-water-cooled lance is inserted, and the air heated to 1800 ° C by plasma heating is heated to 2
It was blown in at 500 m ³ / h. One hour later, the lance was pulled out and the air flow was started to allow stable operation.

Example 3 When the activation state of the core was diagnosed by the same method as in Example 1, the temperature rise amount was 51 ° C. 30 minutes after 1 m from the tip of the blowing lance, so the core was inactive. I decided. Therefore, the lance was taken out, a lance having a non-water-cooled double tube structure was inserted, and coke oven gas was supplied from the inner tube and 30% oxygen-enriched air was supplied from the outer tube for combustion. After sending the coke oven gas at 500 Nm ³ / h and an air ratio of 1.3 for 1 hour, the blowing was restarted to allow stable operation.

Example 4 When the activated state of the furnace core was diagnosed by the same method as in Example 1, the temperature rise amount was 35 ° C. 30 minutes after 1 m from the tip of the blowing lance, so the furnace core was inactive. I decided. Therefore, the lance is pulled out, a water cooling lance is separately inserted into the furnace core through the opening on the tuyere, and a plasma heating device is used to
The air heated to 0 ° C. was blown into the air at 3000 Nm ³ / h.
Air blowing was started 30 minutes after the start of blowing, and blowing was continued during blowing, and blowing was performed for 1 hour and 30 minutes. During this period and thereafter, stable operation was possible.

[0023]

According to the method of diagnosing the active state of the core according to the present invention, the active state of the core can be promptly judged, and the active state of the core can be determined by carrying out the method of activating the core of the present invention. It is possible to take corresponding measures. This makes it possible to achieve stable operation under high O / C operation due to a large amount of pulverized coal blowing, and contribute to stable supply of high-quality hot metal and cost reduction.

[Brief description of the drawings]

FIG. 1 is a graph showing a time course of temperature rise when air at 500 ° C. is blown into a furnace core.

FIG. 2 is a graph showing the relationship between the coke powder ratio of the furnace core and the temperature rise when air at 500 ° C. is blown for 30 minutes.

FIG. 3 is a diagram showing a method for diagnosing a core active state and a method for activating the core.

Front page continued (72) Inventor Yozo Yozo 5-3 Tokai-cho, Tokai-shi, Aichi Pref. Nippon Steel Co., Ltd. Nagoya Works (72) Inventor Hisaro Kamiyama 5-3 Tokai-cho, Akai-ken Nippon Steel Nagoya Steel Works Co., Ltd.

Claims (4)

(57) [Claims] 1. When the blast furnace is in a blast, high-temperature air or oxygen-enriched air is blown into the furnace by using a lance inserted from the tuyere into the furnace core, and a constant distance ahead of the lance is maintained by blowing. A method for diagnosing an active state of a furnace core, which is characterized by judging from a temperature rise amount over time. 2. When the furnace core is diagnosed to be inactive by the method for diagnosing the core core active state according to claim 1, heating means is supplied into the furnace core via the lance used for the diagnosis. A furnace core activation method comprising heating a core. 3. When the furnace core is diagnosed to be inactive by the method for diagnosing the furnace core active state according to claim 1, the lance used for the diagnosis is extracted, and a heating lance or a plasma torch is inserted into the relevant portion. Then, the heating means is supplied into the core to heat the core to activate the core. 4. When the furnace core is diagnosed to be inactive by the method for diagnosing the core core active state according to claim 1, a heating lance or a plasma torch is opened from an opening provided in the lower part of the furnace below the Bosch level of the blast furnace. A method for activating a core, wherein the core is inserted and heating means is supplied into the core to heat the core when the air is blown or blown.