JPS6123708A - Method for operating powder blow to blast furnace and device therefor - Google Patents

Abstract

PURPOSE:To make possible the stable blowing of a large amt. of powder raw material by using a tuyere having a specific ratio of vertical and horizontal sizes as the tuyere to be used for blowing in the case of blowing powdery iron ore, steel making dust, etc. through the tuyere of a blast furnace into the blast furnace. CONSTITUTION:Iron raw material powders such as powdery iron ore and steel making dust are blown together with high-pressure hot wind through the tuyere 2 of the blast furnace 1 into the blast furnace by using a lance 3. The single tuyere 2 having the horizontally long elliptical or rectangular shape of 1:1- 1:20 the ratio between a vertical size and horizontal size or the tuyeres disposed with plural pieces of circular or square tuyeres in the horizontal direction are used for the tuyere 2. The blowing of a large amt. of the powder raw material is thus made possible without the unstability in the furnace condition that the melt 7 of the iron oxide powdery raw material blown into the furnace accumulates in the lower part of a tuyere raceway 4 and forms, together with coke 6, the mixed layer which is hardly flowable downward.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of operating a blast furnace and an apparatus thereof, and relates to powder injection from a tuyere.

[Conventional technology]

Iron ore flows from the blast furnace tuyere into the blast furnace through the blowing nozzle.
For example, Japanese Patent Publication No. 39-814 and Japanese Patent Application Laid-Open No. 53-87908 are known as operating methods for injecting powder containing iron oxide or iron hydroxide, such as ironmaking dust.

If the amount of powder to be blown is small, there is no problem with these methods, but for example, when powdered iron ore is
That is, approximately 100 k per unit of blown ore.
When using a large amount of g/t-p i g or more, there was a drawback that the operation became unstable or impossible9 For example, Fig. 2 shows the operational results in a blast furnace with an internal volume of 1380 m'. In Figure 2, the variation in slag components is typically expressed as C.
Although it is expressed as the variation of ao/5i02, the variation increases rapidly as the amount of fine ore injected increases, and eventually a phenomenon occurs in which molten material accumulates in the raceway in front of the tuyere (slag tabli), making it impossible to blow air. reached the state.

[Problem that the invention seeks to solve]

The present invention aims to overcome this situation, enable injection of a large amount of fine ore, and maintain stable blast furnace operation.

[Means for solving problems]

As a result of observing the movement of solid (coke) and molten material (melt material generated from injected powder) near the front raceway using a fiberscope, we found that if there was a large amount of molten material accumulating in the raceway, the operation was stopped. It turns out that it gets worse.

The present invention has been made based on this knowledge, and the method of operating a blast furnace is to use a single-hole tuyere whose horizontal diameter is larger than its vertical diameter, or to use a tuyere with a plurality of openings adjacent to each other in the horizontal direction. A blast furnace operating method characterized in that a high-speed gas flow whose horizontal diameter is larger than the vertical diameter is formed in the raceway space of the blast furnace using a 3-speed gas flow, and powder is mixed with this high-speed gas flow and blown into the raceway. The tuyere that can suitably carry out this method has a single hole or a plurality of adjacent ventilation tuyere openings, and the ratio of the effective vertical opening dimension to the effective horizontal opening dimension of the opening is Less than 1/1 to 1/20
It is characterized by:

When fine ore 5 is injected into the raceway space 4 through the injection lance 3 from the tuyere 2 provided in the blast furnace wall, the coke filling layer 6 around the raceway is poured into the lower surface of the raceway space. Mainly powder W4 stone melt 7 gathers. This melt melts while the fine ore is flying through the raceway space,
The melt is trapped by the wall of the coke packed bed at the tip of the raceway and formed in the packed bed on the lower surface of the raceway, forming a mixed layer of melt and coaster that is difficult to flow down.

For example, when iron oxide powder is injected, the molten iron oxide is reduced to molten iron by the reaction of equation (1), but the reaction endotherm is approximately 7k a, l per log of Fe2O3 injected. will occur.

Fe203 +3C-+2Fe+3CO'-=----(
I) The heat of reaction is 10g/Nrrf of Fe2O3 injected.
When the air blowing temperature is increased by about 20 degrees Celsius (blow air): This can be compensated for by increasing the blowing temperature by about 20℃ or increasing the cosk ratio by about 3 kg/l-pig, and when the amount of powder blown is small. There is no problem with that. However, as shown in Figure 2, when the amount of injection exceeds 70 gNm', the amount of melt that accumulates at the bottom of the sea urchin f increases. The rate at which the reaction heat of the formula can be supplied from the surroundings cannot keep up, and eventually the inside of the raceway is filled with melt. This is the so-called slag tabli phenomenon, and when this condition occurs, air can no longer be blown and the blast furnace cannot operate.

In order to avoid this phenomenon when a large amount of powder is injected, we conducted powder injection experiments using a small combustion model furnace and conducted various studies.As a result, in order to increase the amount of heat transfer L, we decided to It has been found that it is effective to increase the area: S (area of the raceway side boundary of the molten material storage section 7 in FIG. 1). This area is approximately the elliptical area (π/4)D depending on the raceway's depth length DH and width Dw.
It can be expressed as RlIDW.

On the other hand, the unit of consumption of blown powder in a blast furnace WP (kg/l-
pig) can be expressed by the following equation (2).

Wp= (W/V)Vp ・・・・・・・・・
...... (2) Here, W: Powder blowing speed (kg/mfn) V: Air blowing Jl
(Nrn'/min) VP: Air flow basic unit (Nm
2/t-p r g). According to the above formula (2), in order to increase the powder usage unit Wp, (a) Amount of powder added to the air blower Rp = W/V (kg/Nm
There are two possible methods: (b) increasing the unit air flow rate, or (b) increasing the unit air flow rate; however, method (b) has drawbacks such as lowering the productivity of the blast furnace and significantly increasing energy consumption. , undesirable.

When the relationship between the air flow rate and the maximum possible blowing rate was investigated using a model furnace with a tuyere diameter of 32 mm, the results shown in FIG. 3 were obtained. Maximum blowing addition amount (R
p) Wax increases slightly, but the effect is small. As shown in Figure 4, even if the air flow increases near the blast furnace standard conditions, the boundary area per unit landscape: Rs = S / V
This is because the increase in

Therefore, in order to increase the boundary area per unit air volume, we fabricated a tuyere having an elliptical shape with the same cross-sectional area and a large horizontal diameter, as shown in FIG. 5, and conducted an experiment. 8 The cross-sectional shape of the experimental tuyeres had a height and width ratio a/b of 1/2.1/4, respectively. As shown in Figure 6, the maximum possible injection amount is approximately 25% and 25% respectively at the blast furnace equivalent air volume.
62%.

Note that the cross-sectional shape of the tuyere opening is not limited to an ellipse, but may be a rectangle with long sides in the horizontal direction. Further, instead of having a single hole, it may have a plurality of openings as shown in FIG.

In the explanation below, an example of iron oxide was described, but when oxides other than iron, such as ores such as TiO2, 5i02, and MnO, are injected, the endothermic reaction due to solid C is similar to iron butyride. Therefore, the amount of injection can be increased using the same method.

The ratio a/b of the height and width of the tuyere opening cross section is less than 1/1, and the smaller the ratio, the greater the effect, but in order to control the tuyere wind speed to a constant value, it is necessary to keep the opening cross-sectional area constant. If this ratio is made extremely small, the following problems will occur.

(1) When a becomes small, the inner surface of the tuyere is often worn away by the powder discharged from the blowing nozzle, which may lead to breakage.

(2) The pressure loss of air at the tuyere increases as a/b decreases. Therefore, the blowing pressure becomes high, and when a/b becomes less than 1/20, it becomes approximately twice as high. Combining the above, when a/b becomes smaller than l/20, the disadvantages increase rapidly. Therefore, the preferred a/b is l
A suitable range is less than /1 to l/20.

〔Example〕

The results of injecting fine ore using a tuyere with a circular cross-section of 140 mmφ in a blast furnace with an internal volume of 1380 rrf are shown in FIG. On the other hand, Table 1 shows the results of operations using oval-shaped tuyeres with the same root opening shape and a tip opening of 70 mm in height and 280 mm in width. 3 powdered ore
00 kg/l-pig was blown into the reactor, but there were no problems and stable operation could be continued for a long period of time.

〔Effect of the invention〕

By the method of the present invention, it has become possible to inject several times the amount of fine ore through the tuyere compared to the conventional method. Furthermore, the tuyere of the present invention allows
The above method can be suitably implemented.

[Brief explanation of the drawing]

Figure 1 is a schematic cross-sectional view of the raceway area of a blast furnace, Figure 2 is a graph showing the relationship between the amount of fine ore injected in the blast furnace and operational results, Figure 3 is a graph showing the possible amount of powder injection, Figure 4 is a graph showing the relationship between raceway boundary area and air flow rate, Figure 5 is (a) front view and (b) back (7) A-A view of the tuyere shape used in the model experiment. (c) B-B
6 is a graph showing the expansion of the amount of powder that can be injected by the tuyere of the present invention, FIG. 7 is a perspective view of an embodiment of the porous tuyere, is a view taken along the line C-C in the figure (b). ■... Blast furnace wall, 2... Tuyere, 3... Powder injection lance, 4... Raceway space, 5... Powder, 6
... Coke packed bed, 7... Melt accumulated in the packed bed

Claims (1)

[Claims] 1. A high-speed gas flow whose horizontal diameter is larger than the vertical diameter is formed in the raceway space through a single hole or a plurality of adjacent openings, and powder is mixed with the gas flow to form the raceway. A blast furnace operating method characterized by blowing. 2. A blast furnace having a single hole or a plurality of adjacent blow tuyere openings, the ratio of the effective vertical opening size to the effective horizontal opening size of the opening being less than 1/1 to 1/20. Air tuyere.