JPH06271907A - Method for furnace raw material in bell-less blast furnace - Google Patents

Abstract

PURPOSE:To control the distribution of raw material charged into a bell-less blast furnace in the radial direction of the furnace. CONSTITUTION:At the time of charging the raw material 1 discharged from a flow rate adjusting gate 22 arranged at the lower part of a furnace top hopper 20 into the furnace while turning a turning chute variable in a tilting angle thetaby a fixed turning velocity omega, the raw material charged quantity per unit length of dropping point locus Wd=WO/LO is obtd. from the total length (LO) of the dropping point locus in a plane when the raw material 1 charged from the turning chute 24 collides against the upper surface of the charged material in the furnace and the total charged wt. (WO) of the raw material in this batch. The opening degree of the flow rate adjusting gate 22 is controlled so that this Wd becomes the constant to balance the distribution in the radial direction of the furnace. By this method, the thickness of an ore layer at the center part in the blast furnace is reduced and the furnace core part is activated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention optimizes the distribution in the radial direction of a raw material charged into a furnace through a swirling chute having a variable swirling radius, which is arranged below a bellless type raw material charging device. The present invention relates to a raw material charging method in a bellless blast furnace that can be controlled.

[0002]

2. Description of the Related Art The amount of tapped metal in a blast furnace has significantly increased due to the increase in size of the blast furnace, but it is important to stabilize the operation of the blast furnace in order to take advantage of the size increase. Especially in a large blast furnace, the amount of tapped iron is significantly reduced due to the deterioration of the furnace condition, which has a great influence on the next process. For this reason, it is necessary to control various operating conditions when operating the blast furnace, and in particular, various factors are intricately entangled in controlling the distribution of ore and coke at the top of the blast furnace.
The main factors are as follows. (1) Physical properties of raw materials (ore, coke) -density, particle size, internal friction coefficient, etc. (2) Feed rate of raw materials (3) Charging conditions-layer thickness ratio of ore and coke, stock line level ( 4) Tilt angle of swirling chute (5) Charging sequence (6) Gas flow in furnace When ore and coke distribution is determined when the raw material is charged through swirling chute in bellless blast furnace, reduction of fuel ratio and operation What is important for the above stabilization is the radial distribution of the ore layer and coke layer of the raw material in the furnace. In other words, the idea of feedstock distribution control in blast furnace operation has been concerned with the optimization of the radial distribution of the ratio of ore to coke (Ore / Coke).

In order to efficiently heat and reduce the ore charged in the blast furnace by the high-temperature reducing gas rising in the furnace, it is necessary to uniformly supply the reducing gas to the ore. It is difficult to make them uniform because the characteristics, deposition characteristics, etc. affect it, and the material distribution is likely to be disturbed due to physical and chemical fluctuations of the material, abnormal conditions of the furnace, and the like. If the balance of the reducing gas that rises due to the disturbance of the raw material distribution is disrupted, local uneven flow occurs, and hangings and slips frequently occur, deteriorating the furnace condition.

For this reason, it is becoming more common to concentrate a part of the reducing gas flow in the center of the furnace rather than evenly distributing the gas in the furnace. For example, in Japanese Examined Patent Publication No. 64-9373, the charging of coke in each charge is divided into at least two series over time, and 92 to 98.5% by weight of the total charging amount of coke in the charge is added to the ore layer of the previous charging. Charge so that all of them are covered, and in the final charging sequence, 8 to 1.5% by weight of the total coke charging amount of the charge is intensively charged into the central part of the furnace, so that (Ore / Coke ) Ratio is disclosed to be substantially smaller than the (Ore / Coke) ratio outside the furnace center.

Generally, in a raw material charging method in a blast furnace having a bellless type raw material charging device, the amount (volume) of the raw material discharged from a flow rate adjusting gate arranged at the bottom of the furnace top hopper is made constant. The discharge speed constant control is performed so that the turning speed of the turning chute is constant and the charging is completed within the set number of turns.

[0006]

As described above, in the method such as the constant discharge rate control for making the amount of the raw material discharged per unit time constant, for example, the raw material is fed from the furnace wall portion to the central portion of the blast furnace by a swirling chute. When a raw material charging pattern that charges raw materials is selected, and when the raw material is charged into the furnace wall and the center of the blast furnace, the length of the portion where the raw material is directly charged is proportional to the radius. It gets smaller.

Nevertheless, since the swirling speed of the raw material charging chute is always constant, the amount of raw material charged per unit length is necessarily larger in the central portion of the blast furnace than in the furnace wall portion. The layer thickness becomes thicker in the central part. In particular, when ore is charged, the ore spread on the wall of the furnace collapses the coke layer due to the falling energy and flows into the central part, so that the ore layer in the central part of the blast furnace becomes thicker.

Therefore, there is a problem that the (Ore / Coke) ratio in the center of the furnace is not reduced as desired and the air permeability and liquid permeability of the center of the furnace are deteriorated, which hinders the activation of the center of the blast furnace. It was The present invention provides a bellless blast furnace which solves the above-mentioned problems of the prior art and can optimally control the distribution in the furnace radial direction of the raw material charged into the furnace via a swirling chute with a variable swirling radius. It is intended to provide a raw material charging method.

[0009]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides a swirling chute capable of varying a swirling radius of a raw material discharged from a flow rate adjusting gate arranged in a lower portion of a furnace top hopper. In the raw material charging method in a bellless blast furnace, which is charged into the furnace via the above, the total length (L ₀ ) of the locus of raw material dropping points per batch, which is charged by swirling the swirling chute at a constant swirling speed, The raw material charging amount per unit length of the falling point locus W _d = (W ₀ / L ₀ ) is calculated from the determined total raw material charging amount (W ₀ ), and the raw material charging amount per unit length is obtained. While controlling the discharge rate of the raw material discharged from the flow rate adjusting gate so that (W _d ) becomes constant, the raw material is charged according to the total length (L ₀ ) of the raw material drop point trajectory from the turning chute. Characteristic raw material for bellless blast furnace It is an input method.

[0010]

According to the present invention, the total length (L ₀ ) of the locus of the raw material dropping point per raw material charging batch which is directly charged into the furnace by rotating the swirling chute and changing the swirling radius.
After determining the total amount of raw materials charged (W ₀ ), the amount of raw materials charged per unit length (W _d = W ₀ / L ₀ ) was set at the lower part of the bunker on the top of the furnace. The rate of discharging the raw material discharged from the flow rate adjusting gate is controlled.

Therefore, especially when ores are charged from the furnace wall of the blast furnace to the center of the furnace, the ore layer thickness at the center becomes smaller than in the conventional case where such control is not performed. As a result, it is possible to prevent the inactivation of the core portion due to the thickening of the ore layer in the central portion of the blast furnace. FIG. 2 is a diagram showing in plan view an example of the locus of the raw material dropping point on the upper surface of the raw material in the blast furnace when the batch radius of the swirling chute is made variable and a batch of raw material is charged at a constant swirling speed (angular velocity ω). Is.

In FIG. 2, the upper surface of the raw material in the blast furnace is
The trajectories of the material falling points are mainly radius 3r₀And radius 2r₀
And radius r₀And three circles. This 3
In the trajectory of the raw material falling point when each one circle makes one turn
And L_SIs the starting point of raw material charging by the turning chute
L_eIs the charging end point. Also L_aIs radius 3r₀of
Radius 2r from circle locus₀The length of the locus when moving to the circular locus of
Yes, L_bIs radius 2r ₀From the circle locus of radius r₀Circle trajectory
It is the length of the locus when moving to. Furthermore L₁Is radius 3r
₀Is the circumference of₂Is radius 2r₀Circumference of the circle locus of
And L₃Is the radius r₀Is the circumference of the circle locus.

In FIG. 2, the circumference lengths L ₁ , L ₂ and L
Each of ₃ can be expressed by the following equation. L ₁ = 3 × 2πr ₀ (1) L ₂ = 2 × 2πr ₀ (2) L ₃ = 2πr ₀ (3) Therefore, the total length L ₀ of the raw material drop point locus on the upper surface of the raw material in the blast furnace is It can be represented by a formula.

L ₀ = L ₁ + L ₂ + L ₃ + L _a + L _b Here, the lengths of L _a and L _{b in} the circumferential direction are extremely short. Therefore, if this is ignored, the total length of the falling point locus is Can be expressed as L ₀ ≈L ₁ + L ₂ + L ₃ = 12πr ₀ (4) As is apparent from the above equations (1) to (3), the circumferential length L ₁
And the circumference length L ₂ indicate the case of charging the raw material by the locus of the dropping point such that the circumference length L ₃ is 3 times and the circumference length L ₃ is 2 times, respectively.

In this case, if the total charging amount of the raw material by the three circles is W ₀ , the raw material charging amount W _d per unit length of the falling point locus can be calculated by the following equation. _{W d = W 0 / L 0} = L 1 + L 2 + L 3 = W 0 / (3 × 2πr 0 + 2 × 2πr 0 + 2πr 0) ... (5) The turning speed (angular velocity ω) is turned from a certain turning chute The raw material peripheral velocity V ₁ at radii 3r ₀ , 2r ₀ and r ₀ on the verge of collision of the raw material
V ₂ and V ₃ can be expressed by the following equations.

V ₁ = 3r ₀ × ω (6) V ₂ = 2r ₀ × ω (7) V ₃ = r ₀ × ω (8) Formula (1), (2) and (3) circumferential length L _1, L ₂ and each raw material charging amount W ₁ to L _3, W ₂ and W ₃ using the raw material charging amount W _d per unit length of the drop point trajectory which is obtained by the formula (5) Can be expressed by the following equations.

W ₁ = L ₁ × W _d (9) W ₂ = L ₂ × W _d (10) W ₃ = L ₃ × W _d (11) Here, the transition length from the locus to the locus. Since the raw material charging amount per unit length into L _a and L _b is ignored, W ₀ ≈
W ₁ + W ₂ + W ₃ become although locus transition length L _a, it is also possible to incorporate material in the calculations is charged here seeking circumferential length corresponding to L _b.

As described above, the angular velocity ω of the turning chute is equal to
Raw material has a circumference L₁, L ₂And L₃Along
The required time t to make one turn is the same,
The time is calculated by the following formula. That is, equations (1), (2),
From equation (3) and equations (6), (7), and (8), t = L₁/ V₁= L₂/ V₂= L₃/ V₃= 2π / ω (12) Therefore, the total required time T = 3t = 6π / ω.

At the required time t expressed by the equation (12), the circumference length L ₁ ,
Equations (9), (10) charged along L ₂ and L ₃
The charging amount of each raw material charging amount W ₁ , W ₂ and W ₃ obtained in (11), that is, the raw material discharging speeds Wg ₁ , Wg ₂ and Wg ₃ from the flow rate adjusting gate are given by the formulas (9), ( Ten),
(11) and equation (12) and equations (1), (2),
Using (3), it can be expressed by the following equation.

Wg ₁ = W ₁ / t = (L ₁ × W _d ) / (2π / ω) = 3r ₀ ωW _d (13) Wg ₂ = W ₂ / t = (L ₂ × W _d ) / ( 2π / ω) = 2r ₀ ωW _d (14) Wg ₃ = W ₃ / t = (L ₃ × W _d ) / (2π / ω) = r ₀ ωW _d (15) Conventional swing chute When the swirl speed is constant and the discharge rate of the raw material from the flow rate adjusting gate is constant, the raw material falls as the raw material is charged from the swing chute of the blast furnace from the furnace wall to the core, that is, the radius r of the raw material drop point becomes smaller. The peripheral speed of the point becomes smaller. For this reason, the charging amount per unit length of the locus of the raw material dropping point increased toward the core of the blast furnace.

On the other hand, according to the present invention, the raw material charging amount W ₀ per unit length of the locus of the dropping point is obtained, and the raw material is dropped in the batch charging process while the turning chute is turned and the turning radius is changed. Per unit length on the locus of points, for example, as shown in FIG.
The circumferential lengths L ₁ , L ₂ and L ₃ of the raw material discharge speeds Wg ₁ , W
The opening of the flow rate adjusting gate is controlled so that g ₂ and Wg ₃ become 3W _d , 2W _d , and W _d obtained from the equations (13), (14), and (15), respectively. This achieves optimization of the raw material distribution in the furnace radial direction.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a bellless-type raw material charging apparatus for a blast furnace according to the present invention. As shown in FIG. 1, the furnace top hopper 20 stores the raw material 1 to be charged into the blast furnace 10.
The flow rate adjusting gate 22 supplies the raw material to the turning chute 24 by listening to the opening according to the discharge speed Wg for a predetermined time. The swirling chute 24 is capable of varying the inclination angle θ while swirling at a constant angular velocity ω, so that the raw material can be applied to both the circumference of the upper surface of the raw material 1 in the blast furnace 10 on the furnace wall side and the core. It can be charged.

The level meter 26 measures the distance l ₂ between the upper surface of the raw material 1 in the blast furnace 10 and the swirl chute 24 by using, for example, a microwave length measuring sensor, and measures the measured length l ₂ by the swirl chute. Output to the control calculator 50. Further, the tilt control device 30 positions the servo motor 31 in accordance with the tilt angle command from the turning chute control calculator 50, whereby
The tilt chute 24 is set to a commanded tilt angle θ via the tilt drive mechanism 32.

The turning control device 35 controls the speed of the induction motor 37 in accordance with a command from the turning chute control calculator 50, and thereby turns the turning chute 24 at a constant angular velocity ω via the turning drive mechanism 39. .
The turning radius r of the raw material falling point is the turning radius r ₁ of the turning chute 24 at the inclination angle θ, and the raw material 1 from the turning chute is
Let r _{2 be} the fall distance of L, the length of the swirl chute 24 be l _1, and the distance from the upper surface of the raw material 1 in the blast furnace 10 to the swivel chute 24, which is obtained by the level meter 26, be l ₂ be able to.

R ₁ = l ₁ sin θ r ₂ = √ {4P (l ₂ −l ₁ cos θ)} r = r ₁ −r ₂ l ₁ sin θ−√ {4P (l ₂ −l ₁ cos θ) } (16) In the equation (16), the coefficient P is used.
The discharge speed Wg of the raw material falling from the turning chute 24, the tilt angle θ of the turning chute 24, the grain size of the raw material 1 to be charged,
This is because, for example, even if the distance l ₂ between the upper surface of the raw material 1 in the blast furnace 10 and the swirling chute 24 and the tilt angle θ of the swirling chute 24 are the same, the above-mentioned drop distances are different due to the difference in properties and the like. .

The coefficient P is stored in the turning chute control calculator 50 as a map for each factor that affects the fall distance r ₂ . In the present invention, first the formula (1
6) is used, the locus of the raw material dropping point from the raw material charging start point L _S as shown in FIG. 2 on the upper surface of the raw material 1 in the blast furnace 10 has a radius of 3
The angular velocity ω and the tilt angle θ of the swirling chute 24 are obtained by three circles of r _o , medium diameter 2 r _o and radius r _o and end at the charging end point L _E.
From the calculator 52 of the schedule of the turning shoot control calculator 50
To enter.

In the turning chute control calculator 50 (1),
Radius 3r using (2) and (3)_O2r_O, R_OTo
Three circumference lengths L of the material falling trajectory₁, L₂, L₃Seeking
And the total length of the locus of the raw material falling point using equation (4)
L_OTo calculate. On the other hand, turning chute control from the setting device 52
The total charging amount W of the batch in the computing unit 50_OEnter.
Inside the turning chute control calculator 50, the input trajectory
Total length L_OAnd raw material total charge W_OFrom the above equation (5)
The raw material charging amount W per unit length of the falling trajectory _d= W
_O/ L_OAsk for.

Next, in the turning chute control calculator 50, the setting is made.
One turn with a constant angular velocity ω input from the device 52
Required time t = 2πr_OWith a turning chute
Raw material radius 3r_O2r_OAnd r_ORaw material drop in
Lower track peripheral velocity V₁, V ₂And V₃Where the above formula
While using (6), (7), and (8) to obtain,
Circumference L₁, L₂, L₃And charging of raw material per unit length
Quantity W_dFrom equation (9), (10), (11)
₁, L₂, L₃Raw material charging along the top
Quantity W₁, W₂And W₃Ask for.

Inside the turning chute control calculator 50, the raw material charging amounts W ₁ , W ₂ and W ₃ charged on the circumferential lengths L ₁ , L ₂ and L ₃ , respectively, are given by the equations (9), ( Ten),
Calculate using (11). Further, in the computing unit 50, the time t = 2π / ω for one turn of the turning chute 24 is set, so that the raw material loading per unit time loaded along the circumferential lengths L ₁ , L ₂ and L ₃ of the raw material falling trajectory. Input volume, in other words, flow rate adjustment gate
The raw material discharge speeds Wg ₁ , Wg ₂ and Wg ₃ from 22 are calculated by the above formula (1
Calculate using 3), (14), and (15).

In the present invention, as described above, the locus of the raw material dropping point per batch of the raw material 1 introduced into the blast furnace 10 by swirling the swirling chute 24 having a variable tilt angle θ at a constant swiveling angular velocity ω is shown. the charging from the charging start point L _S of the material 1 into the furnace starts as shown in FIG. 2, the radius 3r _O, 2r _O and r
_It is made by three circles of _O , and the charging is finished at the charging end point L _E.

In this case, first, the locus of the raw material falling point has a radius of 3r.
_OAnd circumference L₁When charging along the
From 22 to raw material discharge speed Wg₁= 3r_OωW_dDischarge as
It Then radius 2r_OAnd circumference L₂When charging along
The raw material discharge speed Wg₂= 2r _OωW_dIs discharged as
Radius r_OAnd circumference L₃When charging along
Charge discharge speed Wg₃= R_OωW_dIt is charged in.

By carrying out such raw material charging, the charging with the constant raw material charging amount W _d per unit length of the falling trajectory is achieved, and the raw material layer thickness in the core portion becomes more extreme than that in the furnace wall portion. It is possible to prevent the thickness from increasing. FIG. 3 shows the result of carrying out the present invention. The ore layer thickness ratio (L _O / (L _O
+ L _C )). The solid line shows the control before the control according to the present invention, and the broken line shows the control after the control. Both were carried out with the same charging amount and charging pattern, but after the control was carried out, L _O / (L _O + L _C ) in the central part of the blast furnace was smaller than that before the control was carried out. As a result, after the control was implemented, it became possible to prevent the inactivation of the core due to the increase of the ore layer thickness in the central part.

That is, as shown in FIG. 4, the inactivation of the core portion due to the decrease in the temperature of the bottom of the furnace is eliminated after the execution of the present invention as compared with the case before the present invention, and the temperature of the bottom of the furnace can be maintained in a preferable range. It was possible to activate the core.

[0034]

INDUSTRIAL APPLICABILITY According to the present invention, in a blast furnace having a bell-less type raw material charging device, when the raw material is charged, the amount of the raw material charged per unit length is constant at any part. Since the charging is carried out, there is no imbalance in the raw material charging amount between the furnace wall portion and the central portion of the blast furnace, and the layer thickness at the central portion can be reduced. As a result, activation of the core can be achieved due to the decrease in the ore layer thickness in the central part of the blast furnace.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a raw material charging device into a blast furnace in which the present invention is implemented.

FIG. 2 is a diagram showing an example of a locus of a raw material dropping point on the upper surface of the raw material in the blast furnace when the raw material is charged with a variable turning radius.

FIG. 3 is a diagram showing a distribution of L _O / (L _O + L _C ) in the furnace radial direction in comparison between before and after implementation of the present invention.

FIG. 4 is a diagram showing the transition of the furnace bottom temperature in comparison between before the implementation of the present invention and after the implementation of the control.

[Explanation of symbols]

 1 Raw material 10 Blast furnace 20 Top hopper 22 Flow rate adjustment gate 30 Tilt control device 31 Servo motor 32 Tilt drive mechanism 35 Swing control device 37 Induction motor 39 Swivel drive mechanism 50 Swiveling chute control calculator 52 Setting device

Claims (1)

[Claims] 1. A method for charging a raw material in a bellless blast furnace, in which a raw material discharged from a flow rate adjusting gate arranged in a lower portion of a furnace top hopper is charged into the furnace through a swirling chute capable of varying a swirling radius. , The total length (L ₀ ) of the locus of raw material dropping points per batch, which is swung at a constant swirling speed and is introduced, and the total amount of raw material charging (W ₀ ) determined in advance The raw material charging amount W _d = (W ₀ / L ₀ ) per unit length of the locus is obtained, and the raw material charging amount W _d per unit length is discharged from the flow rate adjusting gate so as to be constant. While controlling the raw material discharge rate,
A raw material charging method in a bellless blast furnace, characterized in that the raw material is charged according to a total length (L ₀ ) of a raw material drop point trajectory from the swirling chute.