JPH04214808A - Blast furnace tuyere powder injection method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applicable to blast furnace operations in which powder and granules are injected from the blast furnace tuyere by plug transport, and the powder and granules are dispersed from a discontinuous plug state to a uniform and continuous state immediately before the blowing nozzle. This invention relates to a method for blowing powder into a blast furnace tuyere, which makes it possible to stably blow a large amount of hot metal and control the components of hot metal.

0002

[Prior Art] Conventionally, blast furnace operation has been directed to liquid fuel injection operation in which a large amount of liquid fuel such as heavy oil or tar is injected through the tuyere to achieve a low coke ratio and high iron production ratio. .

However, due to the recent rise in crude oil prices, oil-less operations that do not use liquid fuel and all-coke operations are being carried out, but in such operations, the temperature in front of the tuyere rises and the operation is interrupted. tends to become unstable,
There are also disadvantages in terms of operation, such as the maximum pig iron production ratio being suppressed.

[0004] Therefore, in order to eliminate this disadvantage and reduce the amount of coke used, pulverized coal is injected as a fuel through the tuyeres. However, compared to liquid fuel injection operation, pulverized coal injection operation has a problem in that SiO2 derived from pulverized coal reacts with carbon near the raceway, generates SiO 2 gas, and causes an increase in the Si concentration in hot metal. Furthermore, compared to all-coke operation, during pulverized coal injection operation, S in the pulverized coal gasifies in the raceway, causing an increase in the S concentration in the hot metal. In addition, in order to cope with the increase in Si in the hot metal due to the injection of large amounts of pulverized coal, fine ore is also injected through the tuyeres.

[0005] During such powder blowing operations, the powder and granules are usually transported to the blast furnace tuyere by floating transportation, but especially for powders with high powder hardness such as fine ore, transportation is difficult. It has become a problem that piping wears out and stable, large-volume injection cannot be carried out for a long period of time.

[0006] As one of the measures against piping wear as described above,
As disclosed in Japanese Unexamined Patent Publication No. 2-66107, it has been devised to transport plugs at a low transport speed. Here, plug transport is a transport method that achieves low flow rate and high concentration transport, and the part where the particle group plugs the entire pipe cross section and the part where only the transport carrier gas is transported In this method, the plugs are placed in a line alternately in the piping, and the plugs are pushed and moved by the pressure of the carrier gas.

[0007]

[Problems to be Solved by the Invention] In plug transport, the mixing ratio of the transported powder (mass of powder/mass of transported carrier gas) is larger than in floating transport, and the powder and carrier gas are alternately mixed. Since this is a blowing method in which the blowing amount fluctuates extremely significantly over time,
There are the following problems.

[0008] In plug transportation, since the powder and granular material and the transport carrier gas are blown in alternately, the wind pressure fluctuation at the tuyere increases, which adversely affects the furnace condition. ■ Also,
Since the amount of powder and granular material blown at the peak time is extremely large, it causes wear on the inner surface of the blow pipe and the inner surface of the tuyere. ■ In pulverized coal injection, since the peak injection amount is large, mixing with oxygen is insufficient, and the pulverized coal is not completely combusted in the raceway, resulting in a large amount of unburned char, which may lead to poor furnace conditions. ■ Even when injecting iron oxide powder into the sintered ore sieve and fine ore, the peak injection amount is large, so the temperature in front of the tuyere decreases due to direct reduction reaction and solution loss reaction, and the smelting reduction of the fine ore does not progress sufficiently. . As a result, fluid permeability near the raceway deteriorates,
This may lead to wind pressure fluctuations and an increase in slip frequency, leading to sudden wind outages.

[0009] As described above, the method of intermittently blowing powder and granules in a plug state tends to cause abnormalities in the furnace condition and is not suitable for long-term, large-volume injection of powder and granules. In addition, when a large amount of pulverized coal is injected, an increase in Si and S in the hot metal also becomes a problem.

The present invention aims to solve the above-mentioned problems in an operation in which pulverized coal and/or iron oxide powder is injected from a blast furnace tuyere by plug transportation. By breaking the plug of
The purpose of this invention is to provide a method for blowing powder and granular material that can realize stable large-volume blowing operations.

[0011]

[Means for Solving the Problems] In order to achieve the above object, a method for blowing powder into a blast furnace tuyere according to the first invention includes the following steps:
In operations where granular materials such as pulverized coal and iron oxide powder are injected into the blast furnace by plug transportation, booster gas is introduced just before the blowing nozzle to break the plug and disperse the granular materials.
The gist is to blow into the blast furnace in a uniform and continuous state with little change over time in the injection amount, and to carry out stable large-volume injection.

[0012] Furthermore, the second method of blowing powder into a blast furnace tuyere according to the present invention includes introducing, in the first method, slag-forming agent powder containing a CaO source and/or an MgO source together with the booster gas; The main idea is to effectively crush the plug with a small amount of gas, and use the effect of the slag-forming agent to prevent deterioration of the hot metal components and prevent molten slag from adhering to the tuyeres, thereby achieving stable large-volume injection. It is said that

[0013] In the method of the present invention, the plug transporting part is made longer and the plug is broken at a position just before the blowing nozzle, which allows the plug to be transported with less piping wear even for powder particles with high powder hardness such as iron oxide powder. This is to take advantage of transportation. In addition, during floating transportation after the plug is broken, the flow rate of the powder is high, which causes a large amount of piping wear, so the purpose is to make that part as short as possible and make it a straight pipe part. Furthermore, the reason why the slag-forming agent powder is adopted as the powder introduced together with the booster gas in the second method of the present invention is to suppress the deterioration of the hot metal components (increase in Si and S) due to the injection of a large amount of pulverized coal.

[0014]

[Operation] The method of the present invention introduces booster gas just before the blowing nozzle, disperses the powder forming the plug, and blows it into the blast furnace in a uniform state with little change in blowing amount over time. Yes, the powder is in a dispersed state,
In other words, since the air is blown from the tuyere in a continuous state with small changes in the amount of air blown over time, fluctuations in wind pressure become small. Furthermore, since the peak injection amount is also reduced, most of the blown pulverized coal is consumed within the raceway, and the amount of unburned char generated is reduced.

Furthermore, in the second method of the present invention, since the slag-forming agent powder is introduced together with the booster gas, the slag-forming agent powder and the powder particles forming the plug collide, so that It is also possible to effectively break the plug with a small amount of gas, making it possible to suppress as much as possible the increase in the flow rate of the powder or granular material at the blowing nozzle. Even in fine ore,
Because the powder and granules are dispersed and blown in continuously, melting reduction progresses sufficiently and the temperature in front of the tuyere hardly decreases.
There is no adhesion of molten slag to the tuyeres, and stable, large-volume injection can be carried out.

[0016]

[Example] The results of applying the method of blowing powder into a blast furnace tuyere according to the present invention to a blast furnace A (inner volume 2700 m3) will be explained with reference to FIGS. 1 and 2.

FIG. 1 is a schematic diagram of the piping system used in the experiment of the first method of the present invention, and FIG. 2 is a schematic diagram of the piping system used in the experiment of the second method of the present invention. The iron oxide powder is put into a blowing tank 1 and transported through a transport pipe 2 to a booster gas introduction section 3 by plug transport. Further, in the case of FIG. 2, the slag-forming agent powder put into the tank 4 is also transported through the transportation pipe 5 and introduced into the booster gas introduction section 3. The booster gas is then introduced through the booster gas introduction section 3, changing the plug state to a dispersed state. In the case of FIG. 2, it is further mixed with slag forming agent powder. The dispersed powder is passed from the blow nozzle 6 to the blow pipe 7.
It is blown into the blast furnace 9 through the tuyere 8 together with the hot air inside.

FIG. 3 shows an example of the booster gas introduction section 3, which introduces booster gas into the transport pipe 2 through the gas introduction pipe 10. If necessary, the portion where the particles collide may be lined with a wear-resistant material such as ceramics 11.

Similarly to FIG. 3, in FIG. 4, booster gas is introduced into the transport pipe 2 via the gas introduction pipe 10, and the booster gas is introduced from the circumferential direction of the transport pipe 2.

In FIG. 5, a part of the transportation pipe 2 is enlarged to lengthen the residence time of the powder and granular material, and a booster gas is introduced through the gas introduction pipe 12 to break the plug, so that the gas is uniformly introduced. In order to do this, gas is introduced through the perforated plate 13. In this case as well, the transport pipe 2 may be lined with a wear-resistant material such as ceramics, if necessary.

In FIG. 6, a pressure sensor 15 is installed on the upstream side of the gas introduction pipe 14 installed in the transportation pipe 2, and the passage status of the plug (
plug length, passage speed, etc.), and adjusts the flow rate adjustment valve 17 via the calculation device 16 according to the flow characteristics investigated in advance, or in the case shown in FIG. By adjusting the solid/gas ratio of the blowing tank 4, the amount of booster gas and the dispersion state of the powder or granular material can be optimized. In the case shown in FIG. 2, by doing so, the amount of slag forming agent to be blown is limited and an increase in the slag ratio is also suppressed.

FIG. 7 shows the change in the blowing pressure in the conventional method, and the pressure greatly hunts as the plug passes, but in the method of the present invention shown in FIG. 8, there is no large change in the blowing pressure. I understand.

[0023] Table 1 summarizes the operational results of the example shown in Fig. 1 when fine ore was injected in blast furnace A. In the case of floating transportation as in Comparative Example 1, piping wear was remarkable. When blowing in the plug state as in Comparative Example 2, piping wear is reduced, but the inner surface of the tuyere wears out and the number of slips increases. On the other hand, in the first method of the present invention, the amount of fine ore injected is 200 kg/pt.
Stable operation continued with no wear on the transport piping or tuyeres.

[0024]

[Table 1]

Table 2 summarizes the operational results of the example shown in FIG. 2 when fine ore and pulverized coal are injected into blast furnace A. In the case of floating transportation as in Comparative Example 3, piping wear is reduced. The wind was so severe that a sudden shutdown was forced, making it impossible to continue stable operations. In addition, when blowing in the plug state as in Comparative Example 4, piping wear is reduced, but the inner surface of the tuyere wears out and the number of slips increases, resulting in sudden wind shutdowns and unstable operation. It was difficult to continue. On the other hand, in the second invention, stable operation was continued with no wear on the transport piping and tuyere until the injection amount of fine ore was 200 kg/pt, and the Si and S concentrations in the hot metal were also reduced.

[0026]

[Table 2]

[0027]

Effects of the Invention As described above, according to the present invention, in the method of injecting iron oxide and/or pulverized coal from the blast furnace tuyeres by transporting the plug, the plug is broken before blowing, thereby reducing changes in the amount of blowing over time. This reduces damage to the tuyere (abrasion, adhesion of slag, ash, etc.), prevents negative effects on the blast furnace such as fluctuations in blowing pressure, and generates a large amount of unburned powder, and reduces the amount of powder and granules produced. It has become possible to continue stable blowing operations for a long period of time. In addition, according to the second invention, since the slag-forming agent powder containing the CaO 2 source and/or the MgO 2 source is introduced together with the booster gas, Si in the hot metal,
S concentration can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an apparatus configuration in a first embodiment of the present invention in which powder and granules are blown into a tuyere of a steelmaking blast furnace by plug transportation.

FIG. 2 is a schematic diagram of an apparatus configuration in a second embodiment of the present invention, in which powder and granules are blown from the tuyere of a steelmaking blast furnace by plug transportation.

FIG. 3 is a first example of a booster gas introduction part for breaking a plug.

FIG. 4 is a second example of a booster gas introduction part for breaking a plug.

FIG. 5 is a third example of a booster gas introduction part for breaking a plug.

FIG. 6 is a fourth example of a booster gas introduction part for breaking a plug.

FIG. 7 is a diagram showing changes in air blowing pressure when powder and granular material is blown into the plug.

FIG. 8 is a diagram showing the change in air blowing pressure when the plug is broken and powder particles are dispersed and blown into the plug.

[Explanation of symbols]

1 Blow tank 2, 5 Transport piping 3 Booster gas introduction part 4 Tank 6 Blow nozzle 8 Tuyere 9 Blast furnace

Claims (2)

[Claims] Claim 1: In blast furnace operation in which pulverized coal and/or iron oxide powder is injected from the blast furnace tuyere by plug transportation, booster gas is introduced just before the blowing nozzle to break the plug and disperse the powder. A method for blowing powder into a blast furnace tuyere, which is characterized by blowing uniformly and continuously into a blast furnace. 2. The method for blowing powder into a blast furnace tuyere according to claim 1, characterized in that slag-forming agent powder containing a CaO 2 source and/or an MgO 2 source is introduced together with the booster gas.