KR20010055348A - Prevention device from drooping lance for injection of pulverized coal - Google Patents

Abstract

PURPOSE: An apparatus for preventing a sag of a lance comprising a girder for supporting a lance and one or more supporting legs of the hydrodynamically designed girder is provided, which can prevent unexpected damage of a tuyere by maintaining the fast velocity of a moving fluid in the tuyere without changing to the tuyere having a small diameter. CONSTITUTION: The titled apparatus comprises a girder for supporting a lance and one or more supporting legs of the hydrodynamically designed girder, wherein the girder and the leg are made of a mixture of SiC-C and Fe-Si-N. The apparatus has an effect on preventing a sag of a lance even in a state where the lance is not cooled using the girder.

Description

Deflection device of lance for blowing pulverized coal of blast furnace {PREVENTION DEVICE FROM DROOPING LANCE FOR INJECTION OF PULVERIZED COAL}

The present invention relates to a device for preventing sagging of pulverized coal blown lances installed in the blast furnace blast furnace, and more particularly, by preventing the sagging of the lance by using the girder supporting the lance and the legs of the hydrodynamically designed girders. The present invention relates to a device for preventing sagging of pulverized coal injection for increasing the flow velocity at the tuyere to prevent damage to the tuyere.

During blast furnace operation, molten iron and slag are generated from the charges, which are accumulated in the lower part of the furnace, and the melt accumulated in the lower part of the furnace is continuously discharged through the exit port. In the case of large blast furnaces, there are usually four exits, of which two alternate exits in diagonal directions are used to discharge the melt accumulated in the lower part of the furnace.

6 is a longitudinal sectional view of the blast furnace showing the phenomenon in the furnace during blast furnace operation. As shown in FIG. 6, iron ore and coke are introduced through the upper part of the blast furnace 21, and are generated from the blower 23 through the plurality of wind holes 22 in the lower part of the blast furnace 21 to pass through the hot stove. While the wind is raised by the blower tube 24 is introduced at a speed of about 220 m / sec.

In general, the main fuel used in the blast furnace is coke, but in order to reduce costs and prevent air pollution, the pulverized coal is blown through the pulverized coal blowing lance installed in the pit. The lance for blowing pulverized coal is partially exposed to high temperature wind, so the lance deteriorates and sags downward. When the pulverized coal blowing lance sags downward, the ammonia mixed in the pulverized coal reacts with the tuyere made of copper (Cu) to erode the tuyere. Therefore, it is necessary to prevent sagging of the lance in order to secure operational stability. have.

In order to prevent sagging of the lance, conventionally, a double tube is introduced to blow pulverized coal into the inner tube and oxygen or cooling air to the outer tube. However, since the cooling air has no cooling effect, pure oxygen is blown to cool the lance. In order for the pure oxygen to exert the effect of cooling the lance, a certain amount of blown air must be secured. However, there is a problem that the lance deflection phenomenon often occurs because the amount of intake of oxygen is not secured in a situation in which the manufacturer does not monitor, such as a failure of the manufacturing facilities of the oxygen or clogged blowing line.

On the other hand, the interior of the blast furnace is divided into several areas by the wind introduced through the wind hole. As illustrated in FIG. 6, a soft fusion zone 25 is formed at the point where iron ore and coke descending from the upper part of the furnace are burned and the wind rising from the lower tuyere 22 crosses each other. At the tip of the tuyere 22, a cavity is formed by high-speed wind, and a combustion zone 26 in which coke and pulverized coal is burned is formed inside the cavity.

Flow velocity in the tuyere affects the shape of the combustion zone. If the flow velocity in the tuyere is slow, the length of the combustion zone is shortened. However, since about 70% of the melt produced in the blast furnace drops downward through the end of the combustion zone, when the length of the combustion zone becomes short, a considerable amount of the falling melt approaches the air vent. The longer the melt stays close to the tuyere, the more the tuyere's cooling capacity reaches its limit and the tuyere is melted, resulting in a fatal result of flooding the coolant with a large amount of coolant. In order to prevent this, it is necessary to keep the flow velocity in the tuyere fast.

Conventionally, a method of reducing the diameter of the tuyere is used to maintain a fast flow rate at the tuyere. However, since the average life of the tuyere is about 400 days, it is impossible to control the flow rate flexibly by reducing the diameter of the tuyere from time to time. It was.

The present invention solves the problems described above, the object is that the lance does not sag even when the lance is not sufficiently cooled, and by maintaining a high flow rate in the tuyere without replacing the tuyere with a small diameter, the sudden break of the tuyere The present invention provides a device for preventing sagging of pulverized coal blowing lances in a blast furnace, which prevents damage in a small manner and minimizes an opportunity loss of production.

1 is a cross-sectional view of a tuyere equipped with a blower pipe and a pulverized coal blowing lance in a typical blast furnace.

Figure 2 is a perspective view showing a deflection prevention device of the lance for blowing pulverized coal in accordance with the present invention.

3 is a cross-sectional view of the tuyere provided with a deflection prevention device of the lance for blowing pulverized coal in accordance with the present invention.

4 is a cross-sectional view of the combustion zone showing the flow of fluid in the combustion zone and the deposit shape of pulverized coal.

5 is a cross-sectional view showing the shape of the combustion zone is changed due to the sag prevention device of the pulverized coal blowing lance of the blast furnace according to the present invention.

6 is a longitudinal sectional view of the blast furnace showing the phenomenon of the furnace in a typical blast furnace operation.

In order to achieve the object as described above, the sagging prevention device of the pulverized coal blowing lance according to the present invention is composed of a girder holding the lance and a support leg of a hydrodynamically designed girder, wherein the girder and the leg is usually made of a ceramic material Is made of.

At least one leg is preferably four, and the surface of the leg is round and the other side is curved, having a pointed streamline in cross section, thereby increasing the speed of the wind passing through the leg. It is preferable to form a bridge such that the imaginary line connecting the mother and the sharp mother is a spiral with respect to the central axis of the leg so that the wind passing through the leg has rotational force.

Hereinafter, with reference to the accompanying drawings for the sag prevention device of the pulverized coal injection lance of the blast furnace according to the present invention will be described in detail.

As mentioned above, wind is introduced through the blast furnace blast furnace, and the process will be described with reference to FIG. 1 as follows. FIG. 1 is a cross-sectional view of a tuyere provided with a blower pipe and a lance for blowing pulverized coal. As shown in FIG. 1, wind generated from the blower is guided to the tuyere 2 by the blower pipe 1 and the tuyere 2 is It passes through and flows into the blast furnace. The size of the combustion zone (3) formed by the introduced wind is determined by balancing the load of iron ore and coke introduced into the furnace with the wind introduced through the tuyere, and according to the shape of the combustion zone (3) The melt dropping behavior is different.

In addition, the pulverized coal blowing lance 5 connected to the pulverized coal transport pipe 4 is provided at the end of the blower pipe 1, and the tip of the lance 5 is inside the tuyere 2. The amount of wind passing through the tuyere (2) is 180 Nm ³ per minute and the temperature is about 1200 ℃, a large heat load is applied to the pulverized coal blowing lance (5) exposed to the high flow rate and high temperature atmosphere inside the tuyere (2). Since 30 minutes or more pass in the state which is not fully cooled, the lance 5 will deform | transform and sag down.

When the pulverized coal blowing lance 5 sags to the bottom, the ammonia mixed in the pulverized coal reacts with the tuyere made of copper (Cu) and erodes the tuyere 2. It is necessary to prevent sag.

Accordingly, in the present invention, an artificial pedestal girder that supports the lance is installed in the inside of the tuyere so that the pulverized coal blowing lance does not sag downward even in the uncooled state.

Figure 2 is a perspective view showing a deflection prevention device of the pulverized coal injection lance according to the present invention, Figure 3 is a cross-sectional view of the tuyere is installed such a deflection prevention device of the lance. As shown in FIGS. 2 and 3, a girder 6 supporting the lance 5 is installed inside the tuyeres 2 so that the lance 5 does not sag, and the girder 6 has one or more, preferably Is supported by four legs (7).

Since the girder 6 and the leg 7 supporting it are installed inside the tuyere 2, they have to be excellent in heat resistance and abrasion resistance. Therefore, the material of the girder and the leg has a volume expansion between cold and hot to absorb thermal shock. The main material is SiC-C, which is almost no ceramic material, and the Fe-Si-N material having excellent abrasion resistance is mixed in consideration of high speed of 20m / sec.

The bridge 7 supporting the girder 6 is a structure designed by applying Bernoulli's theory, and is configured to increase the speed of the wind passing through the bridge 7 and add rotational force. According to Bernoulli's theory, the velocity of the fluid passing through the long section increases, so that the wind after the bridge passes before the bridge, with one round and one pointed streamline on one side. To speed up. In addition, if the imaginary line connecting the streamlined round hair and the pointed hair is spiral with respect to the center axis of the leg so as to generate a strong rotational force, the rotation force is applied to the wind passing through the leg. This strongly mixes the pulverized coal flowing through the lance with oxygen in the wind so that the carbon in the pulverized coal can be burned well.

On the other hand, when the flow velocity in the tuyere increases, the length of the combustion zone becomes longer. First, with reference to the accompanying drawings for the combustion zone in a general blast furnace as follows. 4 is a cross-sectional view of the combustion zone showing the flow of fluid in the combustion zone and the deposit shape of pulverized coal.

As shown in FIG. 4, the main stream of fluid 8 in the combustion zone 3 first flows through the central section and then bisected to form a detailed vortex 9. In this process, the coke is burned and differentiated at the same time as it rides on the detailed vortex, and the pulverized coal blown through the lance is also burned in the combustion table. Differentiated coke and unburned pulverized coal gather on the edge of the combustion zone to form a dense zone, which is called a frost permeable layer (10) and is called a bird's nest because it is shaped like a bird's nest.

As the opaque layer 10 becomes thicker, an abnormal phenomenon in which the wind from the tuyere 2 is not transmitted to the center of the blast furnace is transmitted to the lower part of the furnace body. In order to improve this, the force of the wind passing through the tuyere (2) can be sufficiently broken so that the wind penetrates the impermeable layer 10 and is smoothly transmitted to the center of the blast furnace so that the thermal balance inside the furnace is properly maintained. .

The shape of the combustion zone is changed when the flow rate in the tuyere increases due to the device for preventing the deflection of the lance according to the present invention and the effect thereof is shown in FIG. As shown in FIG. 5, when the speed of the wind passing through the tuyere 2 is increased by installing the deflection prevention device of the lance according to the present invention, the combustion zone is short and long in the bulging form (the combustion zone 3 shown in dashed lines). It is changed to a slim shape (combustion zone 3 'shown by a solid line) and has a stronger heat transfer capability to the central axis of the blast furnace.

That is, in the general case where the lance deflection prevention device according to the present invention is not installed, since the flow velocity in the tuyere is slower than when the lance deflection prevention device is installed, the dropping point of the melt is shown by the thick arrow 11 indicated by the dotted line in FIG. ) And the melt dwelling in the lower part of the combustion zone is indicated by the thin arrow (12). On the other hand, when the lance deflection prevention device according to the present invention is installed, since the flow velocity in the tuyere is fast, the dropping point of the melt is part of the thick arrow 11 'indicated by the solid line in FIG. 5 and the retention phenomenon of the melt is solid. Is indicated by a thin arrow 12 '.

This means that if the flow velocity in the tuyere is slow, the melt stays in the vicinity of the tuyere, so there is a risk of erosion of the tuyere. Also, about 70% of the melt produced at the top of the furnace falls down through the tip of the furnace. However, the shorter the length of the combustion zone, the more the melt falls to the tuyere, indicating the risk of damaging the tuyere.

On the other hand, when the flow rate in the tuyere is increased by using the lance deflection prevention device according to the present invention, the length of the combustion zone increases toward the central axis of the blast furnace, so that the melt retention in the lower portion of the combustion zone can also be moved to the central axis. Melt falling from the top can also move towards the central axis of the blast furnace, significantly reducing the risk of tuft damage. In addition, there is an advantage in that the temperature distribution in the radial direction of the blast furnace can be uniformly adjusted compared to the case where the combustion zone is short.

As described above, in the present invention, the girder holding the lance has an effect of preventing the lance from sagging even in an uncooled state.

In addition, by designing the structure of the bridge supporting the girder hydrodynamically, not only increases the speed of the wind passing through it, but also gives a strong rotational force to increase the contact opportunities of the pulverized coal and oxygen injected, thereby greatly improving the combustibility. have.

Therefore, the length of the combustion zone is increased toward the central axis of the blast furnace, thereby moving the melt passing through the tip of the combustion zone toward the central axis of the blast furnace, thereby minimizing the amount of melt remaining near the tuyere, thereby preventing damage to the tuyere. It is effective in maintaining stable operation by preventing accidents caused by damage and reducing the loss of opportunity of production.

Claims (4)

In the blast furnace equipped with pulverized coal injection lance, A device for preventing sagging of the pulverized coal blowing lance of a blast furnace, comprising a girder supporting a lance and a leg supporting the girder in the tuyere. The apparatus of claim 1, wherein the girder and the leg are made of a ceramic material. 2. The apparatus of claim 1, wherein the girder and the leg are made of a material in which Fe-Si-N is mixed with SiC-C, which is a main raw material. The wind speed according to any one of claims 1 to 3, wherein the legs are four, and the surface of the legs is rounded on one side and rounded on the other, and has a pointed streamline in cross section. Increased and forming a bridge so that the imaginary line connecting the streamlined round hair and the pointed hair becomes a spiral with respect to the central axis of the bridge, so that the wind passing through the bridge has a rotational force to prevent sagging of the pulverized coal lance for blowing.