JP2741140B2 - Blast furnace operation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for operating a blast furnace in which the state of a furnace core is measured at every scheduled outage, and if there is a sign of modulation, the furnace core is restored to a steady state every time the blast is started. It is.

[0002]

2. Description of the Related Art A blast furnace for steelmaking can produce a large amount of pig iron, and has a high thermal efficiency of 90%. For this reason, the mainstream of pig iron production is maintained even today. However, the blast furnace has the disadvantage that controllability such as productivity and production elasticity is not always good because it is a huge countercurrent moving bed, and further controllability is improved to ensure stable production and hot metal quality. Is desired. When operating under unfavorable conditions in the blast furnace operation process, for example, when raw materials such as high-moisture sinter or coke are charged, or when low-grade raw materials such as lump ore that are easily pulverized are charged, Alternatively, when the coke strength is reduced, or at a high pulverized coal ratio, for example, a coke ratio of 300 k
In the case of a low coke ratio of g / t or less and a high O / C operation in which the O / C (ore / coke) is 5 or more, it becomes difficult to secure the gas permeability and liquid permeability of the furnace core. Even in such a case, it is desired to establish a control technique that enables stable operation.

[0003] A conventional furnace condition recovery control method in the case where it becomes difficult to ensure the air permeability and liquid permeability of the furnace core is disclosed in, for example, Japanese Patent Application Laid-Open No. 63-210208. A method of inserting a sonde in the blast furnace, judging the activity of the furnace core from the detected information, and changing the charge distribution, coke ratio, furnace heat action, etc. when the value exceeds the control standard That is, a method of operating with an increased blast temperature or fuel ratio is known as a general method.

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

Japanese Patent Application Laid-Open No. 3-260004 discloses that when a blast furnace condition deteriorates and a long-term shutoff is performed, a heating excavation lance is inserted from the tuyere of a blast furnace before ventilating and ventilation holes are opened in the furnace core. Then, a furnace core heating method of introducing hot air into the furnace core through the vent hole has been proposed.

[0006]

It is estimated that the charge in the blast furnace passes through the furnace in several hours, while the coke in the core of the blast furnace changes over several days. There is no problem because the furnace core is in an active state while the high-temperature furnace gas is sufficiently flowing in the furnace core, but as described above, the permeability of the furnace core deteriorates due to an increase in the coke powder rate in the furnace core. When the gas stops flowing, the furnace core cools down. Factors that deteriorate the air permeability and liquid permeability of the furnace core part are abnormally small coke particle size in a certain zone of the furnace core part, ash in the coke stays, and furthermore, it is blown from the tuyere part. It is considered that unburned char and ash generated from pulverized coal are deposited on the surface of the furnace core.

[0007] Under the above conditions, the above-mentioned Japanese Patent Application Laid-Open
When the air blowing temperature is increased or exothermic powder is blown in, the surface of the furnace core can be maintained at a high temperature, but the hot air stably flows to the furnace core by employing the method described in Japanese Patent Application Laid-Open No. 3-210208 or Japanese Patent Application Laid-Open No. 60-43410. Unless it can be supplied, the temperature inside the furnace core does not rise, and there is a problem that it takes a long time for the furnace core to be replaced and the furnace condition to be recovered.

In the case of Japanese Patent Application Laid-Open No. 3-260004, in which the furnace core in the inactive state is restored to the gas permeability and liquid permeability in a steady state in a shorter time than the external heating method described above, a plurality of points in the furnace core are required. It takes a considerable amount of time to measure the characteristics of the above or to form a plurality of ventilation holes. In addition, the driving force for the operation of inserting the various probes requires a stronger driving force as the activity of the furnace core decreases, and the operation of inserting the various probes requires safety in the target blast furnace. And the productivity of the blast furnace decreases during this time.

As is well known, the blast furnace equipment performs a scheduled scheduled shutoff, for example, every 30 days or every 45 days. This regular scheduled outage may take more than 10 hours or 2 hours for maintenance of the blast furnace body and incidental equipment or production adjustment.
The wind is cut off for about 4 hours. Maintenance work during this scheduled outage includes, for example, maintenance of charging equipment, furnace body and tuyere, maintenance of peripheral equipment such as mud guns and opening machines, and maintenance of incidental equipment such as dust collectors and hot blast stoves. It is desired that these maintenance works be performed as planned, and that the production efficiency be improved by minimizing the downtime.

On the other hand, the above-mentioned modulation of the core does not occur rapidly, but the above-mentioned causes are accumulated one after another and the modulation gradually occurs. It is desired to grasp and to eliminate it at the stage of signs of furnace condition modulation. As a result of the intensive development of the present inventors in order to solve the above-mentioned problems, the time required for the blast furnace facility maintenance work and the probe insertion-related operation for each of the scheduled scheduled wind breaks set for each blast furnace. The extension of the scheduled outage time is eliminated by sharing the information, and the condition of the furnace core is grasped.If there are signs of modulation in the furnace core, a specific part of the furnace core is An object of the present invention is to provide a method for achieving a transition to a steady operation state in a short time by actively heating the inside.

[0011]

That is, the present invention measures the characteristics of a blast furnace core to determine the state of the furnace core, and provides a vent hole in the furnace core to supply hot air for heating. The furnace core state is determined by measuring the characteristics of the furnace core through a plurality of predetermined tuyeres for each scheduled scheduled outage, and the tuyere is provided with a plurality of ventilation holes. Scheduled maintenance work during cold weather
Or a method for operating a blast furnace, wherein a plurality of ventilation holes are provided in the vicinity of a required heating portion of the furnace core within a range of 10 to 1 hour before the start of air blowing after scheduled air conditioning operation at the time of wind break. .

[0012] The present invention also provides a scheduled maintenance during the scheduled outage.
In parallel with the tuyere maintenance work, one of the operations, the characteristics of the furnace core are measured through a plurality of predetermined tuyeres to determine the state of the furnace core, and a plurality of ventilation holes are formed. Set the tuyere,
Before completion of the tuyere maintenance work, a hollow pipe is inserted through the tuyere and extracted with some of the furnace core components to form a plurality of ventilation holes.

Further, according to the present invention, at each scheduled outage, two or more temperatures are measured in the radial direction of the furnace core through three or four specific tuyeres, and each temperature is measured. It is also characterized in that the core state is determined based on the temperature difference between the parts.

[0014]

According to the present invention, there is provided a scheduled scheduled air cutoff for each blast furnace,
For example, the characteristics of the furnace core are measured through a plurality of tuyeres at predetermined scheduled outages set at intervals of every 30 days, every 45 days, every 60 days, and may occur in the furnace core. With no signs of modulation, the current state of the core can be grasped based on a long-term comparison of characteristic values. In addition, if a method of measuring the temperature at two or more points in the radial direction of the furnace core via three or more specific tuyere parts as a measurement of the characteristics of the furnace core is adopted, the characteristics can be obtained as a temperature distribution on the measurement surface. From the relationship between the temperature and the viscosity of the melt, it can be grasped as the liquid permeability of the furnace core. That is, in order to measure the temperature distribution, three or more tuyere portions are required, and the tuyere portion is preferably high in accuracy. However, as described in the embodiment, the tuyere portion is measured at, for example, four places due to time constraints.

Further, since the tuyere where the vent is to be formed is set based on the grasp of the state of the furnace core, the operation of forming the vent can be performed during scheduled maintenance work when the air is shut off. Further, since the ventilation hole is formed independently of the measurement operation, a hole having a size suitable for ventilation can be formed. In addition, since the ventilation holes formed in the furnace core are kept in a state close to the original form for a long time in the state of the uncooled state, they can be preformed at any time within the scheduled uninterrupted time.

In the present invention, during scheduled maintenance work during a calm
Or 10-1 before the start of ventilation after scheduled air conditioning work at the time of rest
Within the range of time, duplicate
But is intended to provide a number of vent holes, idea to form a vent hole before exceeding the start of air blowing before 10 hours, if the vent hole is closed occurs by coke lumps falling by the pressure of the furnace core section easy. Although the wind is shut off, the portion from which the tuyere is removed is closed by other closing means. However, the inflow of air is inevitable due to the draft of the blast furnace shaft, and the furnace core is not cooled. If the time is less than one hour before the start of the air supply, the tuyere assembly after the perforation of the ventilation holes, that is, the so-called air supply start-up preparation work is insufficient, which is not appropriate. Therefore, in the present invention, the ventilation holes are formed in advance between scheduled maintenance operations within a range of 10 to 1 hour before the start of the ventilation.

The vent hole burns and heats the furnace core from the inside by the hot air supplied during the start-up operation of the blower after a scheduled outage. The larger the diameter of the vent hole, the more effective. However, it is preferable that the diameter of the probe having a large diameter be up to 200 mm because the resistance to insertion into the furnace core increases and there is a possibility of buckling at the time of insertion. The structure of the large-diameter vent hole forming probe is, for example, a steel hollow pipe in order to reduce the insertion resistance. When this hollow pipe is inserted into the furnace core, the coke lump that abuts on the leading end of the pipe is crushed, but most of the coke is contained in the hollow part of the pipe and is taken out of the furnace core by extracting the hollow pipe. , Good air holes are formed. Further, the core component such as coke taken out can be used as a supplementary sample for evaluating the characteristics of the core.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments shown in the drawings. According to the present invention, the characteristics of a plurality of portions of the core of the furnace are measured at scheduled outages that are preset for each blast furnace, for example, at scheduled outages every 30 days, 45 days, or 60 days. It is preferable to set a shorter interval between scheduled wind breaks because long-term data can be accumulated in large numbers.However, the wind break itself is a factor that reduces the production efficiency of the blast furnace, and is based on the production plan and the preventive maintenance plan for the blast furnace equipment. An optimum interval can be set for a specific blast furnace.

FIG. 1 shows a method of measuring the characteristics of the furnace core.
A known means having a mode as shown in the sectional view of the lower part of the blast furnace can be applied. For example, the measuring probe 1 having a thermocouple built therein is inserted directly into the furnace core 7 through the tuyere 5. A method for measuring the temperature, the probe 1 for measurement constituted by a hollow pipe made of steel is inserted into the furnace core 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) If the proportion of coke of 3 mm or less in the above becomes 10% or more, the air permeability in the furnace core deteriorates), or the composition of slag collected in the same manner as in the above coke sampling, for example, Al ₂ O ₃ / C
The value of aO and the average slag composition Al ₂ O ₃ charged into the blast furnace
A method of indirectly determining the degree of activation of the furnace core by comparing with / CaO, or determining the activity of the furnace core from the insertion resistance value when the measurement probe 1 is inserted from the tuyere. A measuring means such as a method can be adopted.

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

In measuring the characteristics of the furnace core, it takes 20 to 30 minutes to remove and attach one tuyere. However, as described above, the present invention provides a tuyere In the operation, the blow pipe 6 at the tuyere
, The blowpipe 6 of the tuyere, which is not a maintenance target but is a measurement target, is removed, and the measuring probe 1 is inserted and the measurement operation is performed until each tuyere is assembled. Therefore, the time required for one tuyere can be reduced to about 5 minutes. In addition, when two pushing devices 2 are used, measurement from four tuyere portions can be performed in about 20 minutes including the time required for moving and installing the devices 2 in about 10 minutes.

In the case of employing the temperature measurement method in the measurement of the characteristics of the tuyere, the tuyere to be measured is specified at three to four locations for each scheduled outage and the tuyere is measured each time. In addition, as a temperature measuring method, after inserting a measuring probe with a steel cap at the tip to a certain depth, retract the measuring probe to drop the tip cap, measure the temperature at that position, and then retreat a certain distance again. Measure the temperature at two or more points in the radial direction of the furnace core, that is, measure the temperature at the position where it was set, and grasp the temperature distribution by measuring the temperature at each point at each tuyere and Can be evaluated together with the transition tendency.

FIG. 2 shows an outer diameter of 60 from the four directions of the blast furnace tuyere.
(a) shows a measurement point and (b) shows a measurement result when a temperature measuring probe of mm is inserted to measure the temperature of the furnace core. The temperature at the position of 1.5 m to 3 m from the tuyere tip was taken as the measurement range, and the temperature at the position of 2 m and 2.5 m (dotted line A in (b)) was measured this time. In the above temperature measurement operation, first,
Blowpipe 6 of the target tuyere as maintenance work of the tuyere
(FIG. 1) and immediately after removing the blowpipe 6 at the tuyere of the temperature measurement target, the temperature measurement probe 1 using two pushing devices 2.
Was inserted into the furnace core and the temperature was measured. FIG. 3 is a graph showing the relationship between the core temperature and the slag viscosity based on the blast furnace dismantling results. From the above temperature measurement results, for example, a temperature measurement value of 1400 ° C.
Below this, the estimated viscosity of the slag becomes 10 poise or more, so that it can be determined that the liquid permeability at the furnace core is reduced. Further, the range of the inactive region can be estimated by comparing the temperature measurement values of the respective parts.

On the basis of the state of the furnace core, No. 1 and N
o. It is determined that a vent hole is to be formed in the core of the two tuyere portions (FIG. 2A). 1 and No. The tuyere of No. 2 was removed. No. during maintenance work break. 1, No. A steel hollow pipe having a diameter of 200 mm was inserted into the two tuyere portions with a diameter of 4 m in the furnace core using the pushing device 2.
A vent was formed by inserting and extracting the core component at the site. After 9 hours, the maintenance work was completed, the ventilation was started, and normal operation was performed. No abnormalities were observed, and the same tuyere was measured for the same tuyere at the scheduled shutoff one month later. As shown by the solid line B in (b),
The core temperature corresponding to each tuyere was improved to 1400 ° C. or higher, and it was determined that the core was in an active state.

[0025]

According to the present invention, in the blast furnace operation, the core characteristics at a plurality of locations are measured at each scheduled outage and the furnace core state is grasped based on the measurement results, and when a sign of modulation is predicted, Since ventilation holes of a size suitable for internal heating of the core are created in advance of scheduled maintenance work at the time of wind break, it can be implemented without substantially extending the wind down time for scheduled maintenance work,
Since the coke is burned from the inside of the furnace core by the hot air at the time of starting the blowing, the blast furnace core can be quickly activated. Therefore, if the method of the present invention is carried out, problems such as the conventional operation of increasing the fuel ratio over a long period of time and the problem of not being able to secure a sufficient amount of tapping for a long period of time because the furnace condition cannot be re-established at an early stage are as follows. It can be completely eliminated. In addition, high pulverized coal ratio operation (pulverized coal ratio 200kg /
Even in the case where it is difficult to ensure the air permeability and liquid permeability in the furnace core as in t), stable operation can be maintained.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of a mode of measuring the characteristics of a furnace core according to the present invention.

FIG. 2 (a) is a diagram showing core temperature measurement points at a plurality of locations in the circumferential direction of a 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]

 DESCRIPTION OF SYMBOLS 1 Measuring probe 2 Push-in device 3 Annular pipe 4 Ventilation branch pipe 5 Tuyere 6 Blow pipe 7 Furnace core

Claims (3)

(57) [Claims] 1. A furnace core state is determined by measuring characteristics of a blast furnace core part. When a vent hole is provided in the furnace core part and hot air is supplied to heat the furnace core part, a predetermined time is set for each scheduled scheduled outage. together determine the furnace core state by measuring the characteristics of the furnace core through a plurality of tuyere sets the tuyere drilling a plurality of vent holes, Kyufuji
A method for operating a blast furnace, wherein a plurality of ventilation holes are provided in the range of 10 to 1 hour before the start of air blowing during scheduled maintenance work or after scheduled air conditioning work after a scheduled wind break in the vicinity of the required heating portion of the furnace core. . 2. In parallel with the tuyere part maintenance operation, which is one of the scheduled maintenance operations during a scheduled outage, the characteristics of the furnace core are measured through a plurality of predetermined tuyeres. A tuyere for judging the state of the furnace core and setting a plurality of vent holes is set, and a hollow pipe is inserted through the tuyere before completion of the tuyere maintenance work to partially configure the core. The method for operating a blast furnace according to claim 1, wherein a plurality of ventilation holes are formed by extracting the ventilation holes together with the objects. 3. At each scheduled outage, two or more temperatures are measured in the furnace radial direction of the furnace core through three or more specific tuyere portions, and the temperature difference between the respective temperature measurement parts is measured. 3. The method for operating a blast furnace according to claim 1, wherein the state of the furnace core is determined based on the condition.