KR20020049913A - Method for preventing from big scab formation at the bosh and belly of all stave cooled blast furnace - Google Patents

Abstract

PURPOSE: A method for preventing from inactivation in the lower part of a blast furnace is provided to prevent the state that it is difficult to perform normal operation of the blast furnace since an adhesion material is excessively grown in the lower part of the furnace due to increase of cooling capability in an all stave cooled blast furnace. CONSTITUTION: The method for preventing from inactivation in the lower part of a blast furnace comprises the processes of performing iron ore non-classification charging(111) in which iron ore is uniformly distributed from the furnace wall part(30) to the central part in the state that iron ore consisted of large sized ore of 12 mm or more and small sized ore of 11 mm or less is not classified per grain sizes; performing coke distribution control in which a coke peak(112) is formed at a point that is 1.2 to 1.4 m distanced from the furnace wall(30) when charging coke from the furnace wall(30) to the central part of the furnace(24), and a peak type coke/iron ore charging in which an iron ore peak(113) is formed at a point that is 1.3 to 1.5 m distanced from the wall part by charging the iron ore from the point where the coke peak(112) is formed to the central part of the furnace(24); and charging middle sized coke(114) charged along with the iron ore so that the middle sized coke(114) is rested in a space that is within 1.5 m from the furnace wall part(30) into which the middle sized coke is first discharged from a furnace top hopper, thereby improving breathability by increasing porosity inside an iron ore layer of the furnace wall part so as to prevent an adhesion material from being excessively grown in the lower part of the furnace.

Description

METHOD FOR PREVENTING FROM BIG SCAB FORMATION AT THE BOSH AND BELLY OF ALL STAVE COOLED BLAST FURNACE

The present invention relates to a method for preventing the inactivation of the furnace bottom of the blast furnace, and more specifically, in the All Stave Cooled Blast Furnace, the attachment of the bottom of the furnace due to the increase of the cooling capacity is excessively grown, thereby preventing the normal operation of the blast furnace. The present invention relates to a method for preventing deactivation of a furnace bottom of a blast furnace for preventing a state that becomes difficult.

In general, the furnace bottom inactivation in the all-stave cooling blast furnace (1) means that as shown in FIG. 1, the inner surface of the stave (10) of the blast furnace 1, such as spectroscopy, powdered coke, slag, etc. Scab 12 composed of a coagulation compound grows inwardly in the Bosh and Valley portions 10a of the furnace to destabilize the furnace load drop, and also through the furnace bottom vents 15. This is a phenomenon that the amount of hot air injected into the furnace is lowered.

When such inferior portion deactivation occurs, first, the drop of the charge 20 becomes unstable, so that slip, drop, and drawing of the charge 20 repeatedly occurs. Done.

This charge drop instability increases the amount of iron ore slips into the furnace center 24 to block the passage of the gas in the furnace to the hearth, resulting in worse furnace breathability. In addition, the deterioration of the air permeability of the furnace lowers the amount of hot air blown into the blast furnace 1 through the tuyere 15, which induces the deactivation of the core coke bed 27 due to the poor iron ore reduction melting state failure in the furnace. do.

Problems related to this undercarriage inactivation are summarized in the diagram in FIG.

Conventional techniques for preventing such inferior portion deactivation are as shown in FIG. This is a condition that the classification charging by the sintered ore particle size, by locally reducing the iron ore / coke (Ore / Coke) ratio by increasing the coke loading amount and the iron ore (Ore) loading amount in the furnace wall portion 30, the furnace wall portion 30 It is a method of dissolving deposits by increasing the amount of gas flow to the side.

However, this method increases the amount of coke charged to the furnace wall 30 (outside) and increases the amount of iron ore charged to the hearth of the furnace (earthquake-resistant), which advantageously acts to activate the periphery 40 of the gas inside the blast furnace 1. (1) The iron ore seismic to the center causes the size of the coke tunnel 42 formed in the center of the furnace to reduce the size and serves to deteriorate the ventilation inside the blast furnace (1).

In addition, another method is to reduce the amount of small sintered ore of 12 mm or less charged in the furnace wall part 30 to dissolve the deposits by improving gas permeability of the furnace wall part 30 and activating the peripheral flow 40.

However, this method also reduces the use of small sintered ore having a particle size of 12 mm or less charged in the furnace wall part 30 partially due to lowering the melting temperature due to the high reduction of the small sintered ore. Since the small-size sintered ore preferentially proceeds with the dissolution reaction rather than the underside deposit 12, it takes a lot of time to dissolve the underside deposit 12.

Finally, a method of dissolving the bottom attachment 12 by improving the air permeability of the furnace wall 30 by increasing the amount of coke charged in the furnace through a decrease in the iron ore / coke ratio charged in the furnace 1. There is this.

However, this method is also intended to improve the air permeability through the drastic reduction of the iron ore / coke (Ore / Coke) in the furnace, this method of removing the bottom attachment (12) is to reduce the iron ore / coke (Ore / Coke). The productivity of the blast furnace 1 decreases by 10% or more, and raises the [Si] component in molten iron to a level of 1.0%, thereby reducing the molten iron quality.

The present invention has been made to solve the above-mentioned conventional problems, the object of which is a phenomenon in which the blast furnace operating conditions are deteriorated from the excessive growth of deposits mainly existing in the Bosch and Valley parts of the lower part of the blast furnace body. It is to provide a method for preventing the inactivation of the bottom of the furnace to prevent the instability of the furnace.

1 is a cross-sectional view showing a state in which the bottom inactivation deposits are formed in a general all-stave cooling blast furnace;

2 is an explanatory diagram showing a state in which a bottom portion deactivation prevention operation is carried out according to the conventional art;

3 is an explanatory diagram showing a state of implementing a method for preventing inactivation of a furnace bottom in accordance with the present invention;

4 is a graph showing the change in the furnace heat transfer index according to the change in gas density in the Bosch part of the blast furnace;

FIG. 5 is a graph illustrating changes in the thickness of Scab according to the difference between the stave T / C temperature and the coolant temperature of the blast furnace; FIG.

6 is a diagram showing the bottom inactivation forming factors and the development phenomenon in the all-stave cooling blast furnace.

Explanation of symbols on the main parts of the drawings

10 ..... stave 12 ..... attachment

10a .... Bosch and Valley

15 ..... Bunny 20 ..... Charges

24 ..... Old Core 27 ..... Coke Bed

30 ..... Furnace 40 ..... Peripherals

42 ..... Coke Tunnel 111 .... Iron Ore Unloaded

112 .... Coke Peaks 113 .... Iron Ore Peaks

114 .. crushed coke 115,116 .... coke-iron ore mixed layer

In order to achieve the above object, the present invention, AllStave Cooled Blast Furnace (AllStave Cooled Blast Furnace) in the furnace bottom inactivation method for preventing the growth of deposits in the bottom of the furnace according to the increase in cooling capacity In the present invention, iron ore unclassified charging is uniformly distributed from the furnace wall portion to the middle portion, without classifying the iron ore composed of the opposing sizes of 12 mm or more and the small particles of 11 mm or less; When the coke is charged from the furnace wall to the center of the furnace, coke distribution control is performed so that the coke peak is formed at 1.2 to 1.4m from the furnace wall. Peaked coke / iron ore charging to be formed at a point of 1.3 to 1.5 m from; In addition, the heavy lump coke charged with the iron ore is charged to be settled within 1.5m from the furnace wall which can be discharged first in the hopper to increase the porosity in the iron ore layer of the wall to improve the air permeability, so that the deposits grow excessively in the lower part. By providing a method for preventing the inactivation of the furnace bottom of the blast furnace, characterized in that to prevent.

In the present invention, the air flow rate is 6000 Nm 3 / min or more under the condition of maintaining the furnace combustion gas density of 8.0 Nm 3 / m 3 or more, and the oxygen ratio of oxygen / carbon in consideration of pulverized coal combustibility 2.1. By providing a method for preventing inactivation of the furnace bottom of the blast furnace, characterized in that it further comprises a high air volume low oxygen incubation operation of 1: 1.

In addition, the present invention manages the difference between the temperature of the stab thermocouple (Stave T / C) and the temperature of the stab cooling water to 20 ℃ or more to maintain the cooling capacity of the stave of the blast furnace excessively high By providing a method for preventing the inactivation of the furnace bottom of the blast furnace, characterized in that it further comprises preventing the excessive growth of the deposits of the furnace wall portion 30 is generated.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

In the present invention, as shown in FIG. 3 as a distribution control method of the charges in the roadbed in order to prevent the unstable instability, the sintered ore unclassified charging 111, peak type coke (coke-Ore) charging 112 and the lumped coke High air flow and low oxygen load operation is carried out through the concentrated charging of the wall part 114 and the management method of the blowing conditions. In addition, as a management method of the stave cooling condition, the temperature of the stave thermocouple and the difference of the coolant temperature are managed in a certain range.

First, the present invention, as shown in Figure 3 to improve the charge distribution control method, classify the iron ore particle size of 12mm or more and 11mm or less grains of iron ore in the furnace wall portion 30 of the blast furnace (1) It is charged to the middle part, and the iron ore of the granules is not classified by the iron ore particle size instead of the charging method by the particle size which is concentrated in the furnace wall part 30, and the iron ore unclassified charging is distributed evenly from the furnace wall part 30 to the middle part. 111).

This is because the unclassified iron ore with the increased iron ore grain size is uniformly charged into the wall part (111) in order to prevent the lowering of the air permeability in the ore layer generated when the iron ore is divided into opposing and small grains to concentrate the small particles into the wall. In the wall portion 30, the periphery is activated by improving the air permeability in the iron ore layer. In addition, since the reduction rate of the unclassified sintered ore of the furnace wall portion 30 is smaller than that of the classified small sintered ore, it contributes to smoothly dissolving the deposit 12 formed in the furnace wall portion 30.

At the same time, a peak-type coke charging 112 method of inducing air permeability improvement in the iron ore layer of the furnace wall portion 30 is implemented. In this case, when the coke is charged from the furnace wall part 30 to the furnace center part 24, the coke distribution control is performed so that the coke peak 112 is formed at a point of 1.2 to 1.4 m from the furnace wall part 30. A peak-type coke / iron ore charge is introduced to guide the iron ore peaks 113 to be formed at a point 1.3 to 1.5 m from the wall portion 30 by charging the core from the coke peak formation point.

The coke peaks 112 serves to secure the coke layer thickness at the point of collapse even when iron ore falls on the peak and collapses a large amount of coke to the center of the furnace and the furnace wall part 30 by the falling energy.

In addition, the coke collapsed from the coke peaks 112 forms iron ore and mixed layers 115 and 116 at the center portion 24 and the furnace wall portion 30 to improve the air permeability of the furnace wall portion 30 and the center portion 24. By activating the periphery without iron seismic seismic or coke outwards. This activated periphery thus prevents the formation of the bottom attachment 12.

In addition, the increase of coke mixed layer 116 at the center ensures the coke tunnel at the center without drastically reducing the iron ore / coke ratio, thereby improving the air permeability at the center and contributing to stably securing the central flow. have.

In addition, the intermediate coke 114 charged with the iron ore is distributed in the position that can be discharged first in the hopper (not shown) as shown in FIG. 3 to be seated within 1.5 m from the furnace wall portion 30 when loading the iron ore. Manage to be. The amount of the crushed coke 114 is increased from 2.5 tons to 3.5 tons per charge when the furnace is inactivated.

The charged lump coke 114 contributes to improving the air permeability by increasing the porosity in the iron ore layer of the wall portion 30. In particular, the concentrated concentration of the lump coke 114 in the furnace wall portion 30 serves to lower the iron ore / coke ratio of the furnace wall portion 30 to easily lower the furnace gas into the furnace wall portion 30. It will provide a passage through it.

On the other hand, in the blast furnace 1, the air flow conditions adjustment method is to maintain the furnace combustion gas density of 8.0 Nm3 / ㎥ or more, the air volume is secured to 6000 Nm3 / min or more for high air flow low oxygen incubation operation, oxygen In consideration of pulverized coal combustibility, oxygen / carbon ratio should be adjusted to satisfy 2.1: 1. When the combustion gas density is secured to 8.0 Nm 3 / m 3 or more in the lower part of the furnace, as shown in the graph of FIG. 4, the contact time of the hot combustion gas with the surface of the deposit 12 formed on the furnace wall 30 is increased. The heat transfer amount is increased to serve to smoothly dissolve the furnace wall attachment (12).

In particular, the high wind volume operation increases the density of the high-temperature combustion gas through the combustion of coke and pulverized coal from the bottom of the furnace from an increase in the amount of high-heat gas injected into the furnace. This high temperature gas contributes to dissolving and removing the deposit 12 by increasing the heat exchange and reaction time with the bottom attachment 12. In addition, the decrease in the amount of oxygen enrichment lowers the combustion rate of the coke in front of the tuyere, so that the charge of the hearth portion is sufficiently raised to lower the furnace portion, so that the amount of heat transfer to the attachment 12 of the furnace wall portion 30 can be increased. have.

In addition, in order to prevent excessive growth of deposits 12 of the furnace wall part 30 generated when the cooling capacity of the blast furnace 1 is excessively high, a stab thermocouple (Stave T / C) The difference between the temperature of and the temperature of the stave cooling water is managed above 20 ° C.

If the temperature difference is maintained within 20 ° C, as the thickness of the attachment 12 of the furnace wall portion 30 rapidly grows to 150 mm or more, it serves to reduce the inner diameter of the furnace bottom portion, thereby increasing the passage of gas to the hearth portion. In addition to the shrinkage, the passage of the charges falling to the lower part of the car is also reduced to cause a dropping phenomenon of the charges.

Thus, as shown in Figure 5 while maintaining the temperature difference 20 ℃ or more, by maintaining the thickness of the deposit 12 of the furnace wall portion 30 to 150mm or less, it is possible to achieve a stable load drop of the furnace part, The lower hot gas may be uniformly raised in the circumferential direction of the furnace wall part 30, thereby preventing excessive growth of the furnace wall attachment 12.

According to the present invention as described above, during the normal operation of the blast furnace (1) having an all-stave cooling device, in advance to detect the decrease in production and the quality of the molten iron from the long-term instability caused by the inactivation of the bottom of the furnace to take measures It is possible.

In the present invention, since the excessive growth of the deposit 12 in the furnace part is caused by the lowering of the peripheral flow in the furnace wall part 30 and the high reducing ability of the small sintered ore, the furnace gas of a high temperature furnace is used to solve this furnace part deactivation. Sintered ore unloaded charging is carried out so as to send a large amount to the wall portion 30 to dissolve the deposit 12, and the peak type coke and iron ore distribution control are carried out, and the furnace wall 30 of the lumped coke is concentrated charged.

In addition, the present invention manages the growth of the furnace wall attachment 12 by managing the difference between the stave thermocouple (Stave T / C) and the coolant temperature to 20 ° C or more as a means of early detection and prevention of the transition to the bottom inactivation during normal operation Is limited to within 150mm.

Operation of the blast furnace (1) is stabilized by preventing the overgrowth of the lower attachment (12) to prevent excessive growth of the lower attachment (12) due to the increased cooling capacity of the blast furnace (1) of the stave cooling method. It is possible to make it possible without lowering the Ore / Coke ratio, thereby contributing to the improvement of the productivity of the blast furnace 1 and the increase in the amount of pulverized coal injection.

Claims (3)

In the all-stave cooled blast furnace (1) (All Stave Cooled Blast Furnace) in the prevention method of the furnace bottom inactivation of the blast furnace (1) to prevent excessive growth of the attachment (12) in the bottom of the furnace as the cooling capacity increases , Performing iron ore unclassified charging 111 uniformly distributed from the furnace wall portion 30 to the middle portion without classifying the iron ore consisting of opposing sizes of 12 mm or more and small particles of 11 mm or less; When the coke is charged from the furnace wall part 30 to the furnace center part 24, the coke distribution control is performed so that the coke peaks 112 are formed at a point of 1.2 to 1.4 m from the furnace wall part 30, and the iron ore is also described above. A peak-type coke / iron ore charge is charged such that the iron ore peak 113 is formed at a point 1.3 to 1.5 m from the wall by charging from the coke peak 112 formation point to the center 24; And, The intermediate lump coke 114 charged with the iron ore is charged to be settled within 1.5 m from the furnace wall portion 30 which can be discharged first in the hopper to increase the porosity in the iron ore layer of the wall to improve air permeability. How to prevent inactivation of the furnace bottom of the blast furnace, characterized in that the attachment (12) to prevent excessive growth. The air flow rate is set to 6000 Nm 3 / min or more under the condition of maintaining the furnace combustion gas density of 8.0 Nm 3 / m 3 or more, and oxygen is the ratio of oxygen / carbon in consideration of pulverized coal combustibility. A method for preventing inactivation of the lower part of a blast furnace, characterized in that it further comprises a high air flow low oxygen hatching operation of 2.1: 1. 2. The cooling capacity of the stave of the blast furnace 1 is excessively controlled by controlling the difference between the temperature of the stave thermocouple (Stave T / C) and the temperature of the stave cooling water at 20 ° C or more. Preventing the inferior portion inactivation of the blast furnace, characterized in that it further comprises preventing the excessive growth phenomenon of the attachment (12) of the furnace wall portion 30 is generated when kept high.