JPH07207309A - Operation of blast furnace blowing in - Google Patents

Abstract

PURPOSE:To stably execute the startup operation of a blast furnace by specifying the shape of coke charged on wood and charging a gas permeation retardant in the inner surface at the furnace wall side in the case of igniting the layers laminated successibly with the wood, coke, and ore and coke on the furnace hearth at the starting time of the blast furnace operation. CONSTITUTION:In the case of starting the blast furnace operation, the wood 2 for ignition and the lumpy coke C are laminated on the furnace hearth, and the ore layer O and the coke layer C are alternately laminated thereon, then the wood 4 is ignited and successively the coke layer C is ignited to start the operation. In this case, the descending rates of the coke C and the ore O in the furnace are predicted at the plural positions in the radial direction of the furnace while the temp. of the furnace rises to the aimed temp. A reverse V shaped virtual fusion zone Y2 is estimated at the upper part by the predicted descending distance from the aimed position of the reverse V shaped fusion zone Y1 after stabilizing the furnace condition to laminate the coke C on the wood 2 and also, the gas permeation retardant is charged at the part D having good gas permeability on the furnace inner wall to start the operation. The ideal reverse V shaped fusion zone Y1 is easily formed and the starting operation of the blast furnace is stabilized at early time.

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 blast furnaces are filled with ore, coke and the like and then ignited.

[0002]

2. Description of the Related Art In the start-up operation at the time of firing a blast furnace,
It is important to quickly raise the temperature of the furnace body and the contents of the furnace interior to the normal operating level so as to obtain a stable furnace condition. Therefore, for example, as described in Japanese Patent Publication No. 61-6122, before burning, wood (sleepers) is stacked from the bottom of the furnace to just below the tuyere level, and coke is filled from the top to the belly of the furnace. There is a method of filling coke layers and ore layers alternately on top.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the method described in Japanese Patent Publication No. 22 (22), (1) the filling position of the ore layer is substantially at the same level in the furnace radial direction. (2)
There are no cohesive zones in the furnace at the beginning of start-up operation after firing of the blast furnace. From these (1) and (2), a large amount of in-furnace gas flows in the order of the furnace wall side, the furnace center side, and the furnace middle side.

For this reason, the temperature distribution in the furnace during the startup operation of the blast furnace becomes higher in the order of the furnace wall, the center of the furnace, and the middle of the furnace. Or it becomes V type. Then, as the operation progresses, it gradually becomes a horizontal I-type and further becomes an inverted V-type, and the furnace condition stabilizes.

Therefore, it takes a long time to form an inverted V-shaped cohesive zone in which the furnace condition is stable, and during this time, the ore is not melted in the core of the furnace or is not sufficiently reduced. As it continues to melt, the endothermic reaction in the lower part of the furnace significantly increases, leading to operational troubles such as poor temperature rise, resolidification of molten ore, abnormal load unloading, etc., and stable startup operation cannot be expected. there were. An object of the present invention is to form an inverted V-shaped cohesive zone in the furnace early after firing and without causing the above troubles, and to start up the blast furnace while maintaining a stable furnace state with high productivity. It is a thing.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and is characterized in that the coke has a predetermined layer thickness of coke on the wood stacked on the bottom of the blast furnace. In a blast furnace firing operation method in which ore and coke are filled in layers and fired in the coke, a target reverse V-shaped cohesive zone generated when the temperature in the furnace rises to a target temperature after blast furnace firing While determining its position, during the period after the blast furnace is fired until the temperature inside the furnace is raised to the target temperature, the descending distance at which the filling in the furnace descends is predicted at a plurality of positions in the furnace radial direction, and the fusion zone Inverse V-shaped virtual cohesive zone is estimated at a position above the target fall position by the predicted descending distance, and coke is filled in the reverse V-type between the upper surface of the wood and the virtual cohesive zone. Immediately below the fusion zone furnace wall side is filled with a breathability suppressing material, Serial is a method of filling forming ore layer and coke layer on the virtual cohesive zone alternately.

[0007]

As a result of various experiments conducted by the present inventors in order to solve the above-mentioned problems, as a result, the shape of the cohesive zone does not become W-shaped or V-shaped, and the cohesive zone is formed at a predetermined position (cohesive zone formation during normal operation). It was found that a stable furnace condition can be formed from the beginning if the position is set to be an inverted V shape.

In order to form the inverted V-shaped cohesive zone at this predetermined position, as described above, until the temperature in the furnace reaches a predetermined value and the inverted V-shaped cohesive zone is formed at the predetermined position. The virtual cohesive zone is estimated by the thicknesses of both layers of wood and coke that burn and disappear in the furnace, relative descent rate in the radial direction of the furnace, and the position and shape of the cohesive zone to be formed first after firing. However, since the lower side position of this virtual cohesive zone is at a position that will be the furnace core part at the stage when the cohesive zone is formed in the startup operation process, by filling only this portion with coke, Japanese Patent Publication 61-6
This avoids troubles such as mixing of unmelted ore into the furnace core and melting of unreduced ore, which are caused by the method described in Japanese Patent No. 122 publication.

However, until the cohesive zone is formed in the furnace, the amount of the in-furnace gas that rises in the vicinity of the furnace wall as described above is larger than that in other parts (the center of the furnace and the middle of the furnace). Therefore, in order to suppress this and direct the central flow in which the gas in the furnace largely flows in the central portion, the gas permeability suppressing material is filled just under the virtual fusion zone and on the furnace wall side. This air-permeability-suppressing material should be one that can impede the air permeability in the furnace without adversely affecting the inside of the furnace. For example, a mixture of blast furnace slag (blast furnace ballast) and limestone, coke with a fine grain size, However, the former is preferable. This is because the blast furnace slag is melted before the ore filled above the virtual cohesive zone forms the cohesive zone, and the viscosity of the molten blast furnace slag is improved by high melting point limestone, By not allowing the slag to drip but staying at that position, the air permeability of this portion is suppressed, and a large amount of in-furnace gas flows in the order of the furnace center side, the furnace middle side, and the furnace wall side. Furthermore, in addition to this, since the ore and coke are packed in layers on the upper side of the virtual cohesive zone, the shape of the cohesive zone first formed in the furnace after firing is reversed V
A type of start-up operation becomes possible, and a stable furnace condition can be created early.

[0010]

An embodiment of the present invention will be described below with reference to the drawings. This embodiment has an inner volume of 5245 m ³ and 40 tuyere 1 around the furnace, and the temperature of the hot air blown from the tuyere 1 is 1
This is an example applied to a bell-type blast furnace having a flow rate of 250 ° C. and an air volume of 8000 m ³ / min. As shown in FIG. 1, after burning, the cohesive zone Y ₁ to be formed first has a generatrix angle θ ₁ : 60 degrees, a distance H ₃ between the root 3 and tuyere 1 thereof: 2 m, a root 3 and a central portion 4 Height H ₁ :
The shape was a cone-like shape (inverted V shape) of 14 m. Further, a known model formula, for example, “Iron and Steel” No. 15 (Publisher: Iron and Steel Institute of Japan, Issued Date: November 1, 1982)
(Sun) Using the model formulas described on pages 2334 to 2335, the relative lowering rate V (when the middle part of the furnace is 1) of each packing in the furnace from the furnace wall to the center of the furnace was calculated. The result is shown in FIG.

Further, when the temperature in the furnace reaches a normal operating temperature level (1400 ° C.) after firing, the heat quantity required until the above-mentioned cohesive zone Y ₁ is formed is calculated, and this heat quantity is calculated. Sleepers 2 and coke C that burn and disappear to gain
The volume V ₀ of V is calculated. When the sleeper / coke volume V ₀ disappears, the descent distance α ₀ of the filling at the furnace wall portion is obtained by the following equation (1). (At this time, the filling descending speed in the furnace radial direction was the same below the Bosch portion BH.)

[0012]

[Equation 1]

Further, according to the distance α ₀ of the filling material in the furnace wall and the relative descending velocity V in the furnace radial direction obtained by the above equation,
Find the distance of fall of the packing in the furnace radial direction. The cohesive zone Y ₁ is assumed virtual cohesive zone Y ₂ from the position which is formed upwards by drop distance above. At this time, the shape of the virtual cohesive zone Y _{2 is} a generatrix angle θ ₂ : 30 degrees and a height H.
_2: become a thing of the inverted V-shaped 45m. As a result, first, the sleepers 2 as wood are stacked for about 5 m. Next, a coke C having a particle diameter of 75 mm to 25 mm is inserted between the sleeper 2 and the root portion 5 of the virtual cohesive zone Y ₂ up to the same level.

Next, only coke is charged in a region below the virtual melting zone Y ₂ (inside the furnace), and the virtual melting zone Y ₂ is charged.
Immediately below (between the virtual fusion zone Y ₂ and 0.8α), the vicinity of the furnace wall is filled with about 450 t of the air permeability suppressing material D mainly composed of a mixture of blast furnace slowly cooled slag and limestone in substantially equal amounts. A layer of coke and ore is layered above the virtual melting zone Y ₂ (outside the furnace), and an armor plate (not shown) is provided so that the ratio (O / C) of the ore and coke is 2.2. Charge while adjusting.

In this way, the sleepers 2 are stacked in the furnace, and the coke is further filled from above to the virtual melting zone Y ₂ , and the air permeability suppressing material D is filled on the furnace wall side of the upper surface of the coke. , And an ore layer O and a coke layer C on top of it
Were alternately charged in layers and then fired to start up. As a result, it was possible to form a substantially targeted inverted V-shaped cohesive zone, and it was possible to successively increase the gun discharge amount as shown in FIG. 3, and the furnace conditions were stable.

[0016]

As described above, according to the present invention, after the firing, the inside of the furnace reaches a predetermined temperature, and the formation of the cohesive zone that can be initially formed can be made into the inverted V type, and the stable start-up can be achieved. Operation is now possible. Further, this brings about a great effect that a prescribed amount of gun discharge can be obtained at an early stage.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a state of ore / coke filling in a furnace before firing.

FIG. 2 is a diagram showing the in-furnace descent rate in the radial direction of the furnace.

FIG. 3 is a diagram showing a transition of blast furnace production after firing.

[Explanation of symbols]

1 bird port 2 sleepers 3 roots of the central portion 5 Y ₂ of the root portion 4 Y ₁ of Y ₁ Y wants to form _one first cohesive zone Y ₂ virtual cohesive zone B hearth brick top C Coke (layers) D breathable Suppression material BH Bosch O O ore (layer)

Claims (1)

[Claims] 1. A blast-furnace firing operation method in which a predetermined layer of coke is filled on wood stacked on the bottom of a furnace in a blast furnace, and the ore and the coke are layered and fired in the blast-furnace firing operation method. The target inverse V-shaped cohesive zone and its position, which are generated when the temperature inside the furnace is raised to the target temperature, are determined, and the temperature inside the furnace is raised after the blast furnace is turned on until the temperature inside the furnace is raised to the target temperature. The descending distance that the filler descends is predicted at a plurality of positions in the radial direction of the furnace, and an inverted V-shaped virtual cohesive zone is estimated at a position above the target position of the cohesive zone by the predicted descending distance. To the virtual cohesive zone, coke is filled in an inverted V shape, and a gas permeability suppressing material is filled in a portion directly below the virtual cohesive zone furnace wall side to form an ore layer on the virtual cohesive zone. A blast furnace firing operation method characterized in that coke layers are alternately filled and formed.