JPH0693320A - Operation of blast furnace - Google Patents

Abstract

PURPOSE:To restore a furnace core part to the stationary condition at each starting of the blasting by measuring the condition of the furnace core part at each scheduled stopping of the blasting. CONSTITUTION:At the time of measuring the characteristic in the furnace core part 7 in a blast furnace to decide the condition in the furnace core part and supplying the hot blast by arranging a blasting hole in the furnace core part 7 to heat the furnace core part, by using probes 1 having 50-200mm of the outer diameter through the prescribed plural tuyere parts 5 at each periodical scheduled stopping of the blasting, the characteristic of the furnace core part 7 is measured to decide the condition of the furnace core part and also, the hole formed at the time of measuring the characteristic is used to the blasting hole at the time of starting the blasting. In parallel to the maintenance work of the tuyere part at the time of scheduled stopping of the blasting, it is desirable to measure the characteristic of the furnace core part through four or more of the tuyeres.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of operating a blast furnace in which the state of the core of a furnace is measured for each scheduled blast and the core of the blast furnace is restored to a steady state each time the blast is started.

[0002]

2. Description of the Related Art A blast furnace for iron making can produce a large amount of pig iron and has a high thermal efficiency of 90%. Therefore, the mainstream of pig iron production is still maintained. However, since the blast furnace is a huge countercurrent moving bed, it has a weak point that the controllability of productivity, production elasticity, etc. is not necessarily good, and further improvement of controllability is ensured in order to secure stable production amount and hot metal quality. Is desired. Operation under unfavorable conditions in the blast furnace operation process, for example, when raw materials such as high-moisture sintered ore and coke are charged, and when low-grade raw materials such as lump ore that are easily pulverized are charged, Alternatively, when the coke strength decreases, or when the pulverized coal ratio is high, for example, the coke ratio is 300 k.
In the case of high O / C operation with a low coke ratio of g / t or less and an O / C (ore / coke) of 5 or more, it becomes difficult to secure the air permeability and liquid permeability of the furnace core. Even in such a case, establishment of a control technique capable of stable operation is desired.

A conventional furnace condition recovery control method when it becomes difficult to secure the air permeability and liquid permeability of the furnace core is disclosed in, for example, JP-A-63-210208. As described above, insert a sonde inside the blast furnace, judge the activity of the core from the detected information, and change the charge distribution, coke ratio, furnace heat action, etc. when the value exceeds the control standard. That is, a method in which the blast temperature and the fuel ratio are increased to operate the operation is known as a general method.

Although the purpose is different from the above-mentioned air permeability recovery operation of the furnace core part, as a method for correcting the deviation of the furnace core part, heat generation of pulverized coal, coke powder, ferrosilicon powder, etc. from the blast furnace tuyere Japanese Patent Application Laid-Open No. 60-43410 discloses a method of blowing a conductive powder and melting the furnace core portion facing the raceway.

Further, in Japanese Patent Laid-Open No. 3-260004, when the blast furnace condition deteriorates or when long-term blast is performed, a heating excavation lance is inserted from the tuyere of the blast furnace to open a vent hole in the core before the start of air blowing. Then, a furnace core heating method has been proposed in which hot air is introduced into the furnace core through the ventilation holes.

[0006]

It is estimated that the charge in the blast furnace passes through the furnace within a few hours, whereas the lump coke in the furnace core is replaced in a few days. There is no problem because the furnace core is in the active state while the high-temperature furnace gas is sufficiently flowing in the furnace core, but as mentioned above, the air permeability of the furnace core deteriorates due to the increase in the coke powder ratio in the furnace core. When the gas stops flowing, the core of the furnace cools. The factors that deteriorate the air permeability and liquid permeability of the furnace core part are that the coke particle size in a certain zone of the furnace core part becomes abnormally small, the ash content in the coke is retained, and further it is blown from the tuyere. It is considered that unburned char or ash generated from pulverized coal is accumulated on the surface layer of the core.

In the above-mentioned state, the above-mentioned Japanese Unexamined Patent Publication No.
By adopting the method of 3-210208 or Japanese Patent Laid-Open No. 60-43410, the surface of the furnace core surface can be kept at a high temperature by raising the temperature of the blown air or blowing the heat-generating powder, but the hot air is stabilized in the furnace core. There is a problem that the temperature inside the furnace core does not rise unless it can be supplied, and it takes a long time for the furnace core to be replaced and the furnace condition to recover.

In the case of carrying out the above-mentioned Japanese Patent Laid-Open No. 3-260004, in which the inertness of the furnace core is restored to the steady-state breathability and liquid permeability in a shorter time than the above-mentioned external heating method, a plurality of positions of the furnace core are required. It takes a considerable amount of time to measure the characteristics of 1. or to perform the operation of forming a plurality of ventilation holes. Further, the driving force for the insertion operation of the various probes requires a stronger driving force as the activity of the furnace core part decreases, and the insertion operation of the various probes is a safety target blast furnace. There is a problem that the productivity of the blast furnace decreases during this period.

As is well known, the blast furnace facility performs a scheduled scheduled downtime, for example, every 30 days or every 45 days. This regular scheduled downtime is more than a dozen hours or 2 for maintenance of the blast furnace main body and incidental equipment or production adjustment.
It takes about 4 hours of rest. Examples of maintenance work during this planned downtime include maintenance of charging equipment, furnace body, tuyere, maintenance of peripheral machines such as mud guns and opening machines, and maintenance of auxiliary equipment such as dust collectors and hot air stoves. It is hoped that these maintenance works will be carried out as planned and that the downtime will be minimized to increase production efficiency.

On the other hand, the above-mentioned modulation of the furnace core does not occur suddenly, but causes the above-mentioned causes to be accumulated in order to cause a gradual modulation. It is desired to understand and eliminate it at the stage of signs of reactor condition modulation. As a result of intensive development by the inventors of the present invention in order to solve the above problems, a similar work time for blast furnace facility maintenance work and probe insertion-related operation is performed for each scheduled scheduled blast set for each blast furnace. By canceling the extension of planned downtime by understanding the situation of the furnace core,
It is intended to provide a method for attaining a transition from a start-up of blown air to a normal operation state in a short period of time in a short time.

[0011]

Means for Solving the Problems That is, according to the present invention, the characteristics of the blast furnace core are measured to determine the state of the core, and ventilation holes are provided in the core to supply hot air to heat the blast furnace. 50 to 20 through a predetermined plurality of tuyere parts for each planned scheduled wind break
A blast furnace characterized by measuring the characteristics of the furnace core using a probe having an outer diameter of 0 mm to determine the condition of the furnace core, and at the same time, the holes formed during the measurement are raised to serve as ventilation holes during ventilation. Is the operating method.

Further, the present invention is characterized in that the characteristics of the furnace core are measured through four or more tuyere in parallel with the above-mentioned tuyere maintenance work at the time of scheduled downtime.

[0013]

The present invention is directed to the scheduled scheduled downtime for each blast furnace,
For example, since the characteristics of the core of the furnace are measured through a plurality of predetermined tuyere at every scheduled blast set at intervals of every 30 days, every 45 days, or every 60 days, it may occur in the core. It is possible to grasp the current core state by comparing long-term characteristic values with no signs of modulation. In addition, since the characteristics of the furnace core portion are measured through the plurality of tuyere with a probe having an outer diameter of 50 to 200 mm, for example, temperature measurement or sampling of the core constituents, the characteristic value of the furnace core portion is measured. Can be grasped and 50-
The 200 mm diameter hole is kept in a state close to its original shape for a long time in a resting state, so that it can function as a ventilation hole for blowing air at the time of starting blowing air thereafter.

Further, when inserting the above-mentioned characteristic value into the tuyere of the measurement probe, the blow pipe provided on the downstream side of the blower branch pipe needs to be removed, and depending on the outer diameter of the measurement probe to be used. Need to remove the tuyere, but by sharing the work of removing the blow pipe and tuyere at the time of maintenance work of the tuyere during the scheduled downtime described above, the preparation work for inserting the probe for measuring the characteristic value is omitted. As a result, the planned downtime cannot be extended by the characteristic value measurement operation. Also, since the characteristics of the furnace core are measured through four or more tuyere, the characteristics can be grasped as the distribution on the measurement surface, and moreover, it is necessary as a ventilation hole for internal heating of the furnace core when the air blow is started. The number can be secured.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on the embodiments shown in the drawings. The present invention measures the characteristics of a plurality of locations of the core of the furnace for each scheduled outage preset for each blast furnace, for example, for every 30 days, every 45 days, or every 60 days. A shorter interval between scheduled downdrafts is preferable because it accumulates a lot of long-term data, but the downwind itself is a cause of reducing the production efficiency of the blast furnace, and based on the production plan and the preventive maintenance plan for the blast furnace equipment. The optimum interval can be set for a specific blast furnace.

As a method for measuring the characteristics of the furnace core, the method shown in FIG.
It is possible to apply publicly known means having a mode as shown in the sectional view of the lower part of the blast furnace, for example, by inserting the measurement probe 1 having a thermocouple installed therein into the furnace core part 7 directly through the tuyere part 5. Method of measuring temperature, the measuring probe 1 constituted by a hollow steel pipe is inserted into the furnace core portion 7 in the same manner as described above to collect the furnace core coke, and the history temperature and powder rate of the coke (for example, each measurement site). When the ratio of 3mm or less coke is 10% or more in the method breathability in the furnace core section measures a worsening) directly or composition of the slag taken as above coke sampling, for example, Al ₂ O ₃ / C
Value of aO and average slag composition charged into blast furnace Al ₂ O ₃
/ CaO to determine the activation level of the furnace core indirectly, or to determine the activation level of the core from the insertion resistance when inserting the measurement probe 1 from the tuyere A measuring means such as a method can be adopted.

In FIG. 1, 1 is a measuring probe and 2 is a measuring probe.
Is a pushing device of the measurement probe 1, 3 is an annular pipe for supplying hot air to the tuyere, 4 is a blower tributary, 5 is a tuyere, and a line between the blower tributary pipe 4 and the tuyere 5 is shown by a dotted line. As described above, the blow pipe 6 is arranged, and is removed when the measurement probe 1 is inserted into the furnace core 7. When using a large-diameter measurement probe 1,
The tuyere 5 is also to be removed.

It takes 20 to 30 minutes to remove and install one tuyere at the time of measuring the characteristics of the above-mentioned furnace core portion. During work, the blow pipe 6 of the tuyere to be maintained
The blow pipe 6 of the tuyere which is not the maintenance object but the measurement object is removed, and the insertion of the measurement probe 1 and the measurement operation are performed before assembling each tuyere. As a result, it takes about 5 minutes to complete one tuyere. Moreover, when two pushing devices 2 are used, measurement from four tuyere portions can be performed in about 20 minutes including about 10 minutes required for moving and installing the pushing devices 2.

The present invention uses a probe having an outer diameter of 50 to 200 mm as a measuring probe used for measuring the above-mentioned various characteristic values. The smaller the outer diameter of the probe is, the smaller the insertion resistance from the viewpoint of ease of insertion, but to make the hole formed in the furnace core part by the measurement operation function as a vent hole for hot air after the start of blowing air. The outer diameter is 50 mm or more. Also, the larger the outer diameter of the probe, the more effectively it functions as a ventilation hole. However, the larger the probe diameter, the greater the resistance to insertion into the furnace core. is there.

As a mode of inserting the measuring probe into the furnace core portion, for example, a temperature measuring probe having a diameter of 50 mm is pushed into the furnace core portion with a steel cap provided at its tip and inserted to a predetermined position. After that, the probe is slightly retracted to remove the steel cap, the temperature is measured at that position, and then the temperature is measured at a position retracted for a certain distance, or for example, a hollow steel pipe having a diameter of 200 mm is subjected to a predetermined pressing force. While inserting to the position, the furnace core constituent is taken into the hollow pipe, and the furnace core constituent at the insertion portion is extracted by the hollow pipe to form a sampling hole, and immediately after that, a thermocouple is installed, for example, a diameter of 30 mm. Insert a temperature measuring probe into the hole to quickly measure temperature at multiple positions in the hole, or attach a small diameter temperature measuring pipe to one outer surface of the large diameter hollow pipe. After inserting to a predetermined position by pushing in the furnace core section in state, can such a method of sampling a deadman arrangement is employed with to temperature measurement while retracted.

The measuring probes are inserted into the furnace core at four or more positions at substantially equal intervals on the horizontal cross section of the tuyere, and the measured values are compared to determine the horizontal cross section of the tuyere. The characteristics, such as temperature, can be grasped as a distribution. As the number of insertion points of this measurement probe increases, the distribution of the above characteristics becomes more precise, and since it effectively functions as a ventilation hole for hot air after the start of air blowing, it is possible to quickly return to a normal operating state. Is. However, according to the present invention, the characteristic measurement operation is performed in parallel with the tuyere maintenance work at the time of scheduled downtime, that is, the blow pipe and the tuyere arranged downstream of the blast branch pipe for the tuyere maintenance. By performing the measurement probe insertion operation to the furnace core between the removal work and the tuyere and blow pipe installation work, the blow pipe and the tuyere removal, which are the preparatory work for the measurement operation of the furnace core characteristics, Since a considerable part of the installation work is omitted, it is desirable to decide it based on the set scheduled downtime and the number of tuyere maintenance.

FIG. 2 shows an outer diameter 60 from the four directions of the tuyere of the blast furnace.
When a temperature probe of mm is inserted and the temperature of the furnace core is measured, (a) shows measurement points and (b) shows measurement results. The temperature at the position of 1.5 m to 3 m at the tip of the tuyere was set as the measurement range, and this time, the temperature at the position of 2.5 m (dotted line A in the figure in (b)) was used for evaluation. FIG. 3 is a graph showing the relationship between the core temperature and the slag viscosity based on the blast furnace dismantling result. From the above temperature measurement results, for example, when the temperature measurement value is 1400 ° C. or less, the estimated viscosity of the molten slag is 10 poises or more. Therefore, it can be determined that the liquid permeability in the furnace core has deteriorated. Further, the range of the inactive region can be estimated by comparing the temperature measurement values of the respective parts.

No abnormalities were found in the process of starting up the blast after the scheduled blast and performing normal operation, and the result of the same measurement for the same tuyere at the scheduled blast after one month was shown in FIG.
As shown by the solid line B in (b), the core temperature corresponding to each tuyere was low. 2 tuyere (Fig. 2 (a)) is 1400
No. It can be said that the holes formed by inserting the temperature measuring probes at the two tuyere contributed as ventilation holes when the air was blown up after the planned downtime.

[0024]

According to the present invention, the characteristics of the core at a plurality of locations are measured for each planned outage in the blast furnace operation, the condition of the core is grasped from the measurement results, and the core is formed by the measurement. Since the holes are used as hot air vents when the air is blown up after resting, it is possible to quickly activate the blast furnace core by raising the core temperature or decreasing the coke powder ratio in the core. Become.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a measurement mode of characteristics of a furnace core portion of the present invention.

FIG. 2 (a) is a diagram showing a plurality of core temperature measurement points in the circumferential direction of the blast furnace, and FIG. 2 (b) is a graph showing the measurement results.

FIG. 3 is a graph showing the relationship between core temperature and slag viscosity.

[Explanation of symbols]

 1 Measuring probe 2 Pushing device 3 Annular tube 4 Blower branch pipe 5 Tuyere 6 Blow pipe 7 Core part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Morimasa Ichida 20-1 Shintomi, Futtsu City, Chiba Shin Nippon Steel Co., Ltd. Technology Development Division

Claims (2)

[Claims] 1. When the characteristics of the blast furnace core are measured to determine the state of the core and ventilation holes are provided in the core to supply hot air to heat the blast furnace, a predetermined interval is set for each scheduled blast. The characteristics of the furnace core portion are measured through a plurality of tuyere portions with a probe having an outer diameter of 50 to 200 mm to determine the state of the furnace core portion. A method for operating a blast furnace, which is characterized by using ventilation holes. 2. The operation of the blast furnace according to claim 1, wherein the characteristics of the core of the blast furnace are measured through four or more tuyeres in parallel with the tuyere maintenance work during planned downtime. Method.