KR20030005779A - A pulverized solid fuel injecting apparatus - Google Patents

Abstract

The present invention relates to a solid fuel blowing device that blows fine powder of fine fuel in place of expensive coke in the blast furnace making process, and its purpose is to reduce the feed rate of solid fuel and to increase the injection width of solid fuel to improve combustibility. To provide a fine fuel injection device of fine powder that can improve the.

The present invention for achieving the above object,

An inner tube 142 and an outer tube 145 surrounding the inner tube 142, and a flow path of fine solid fuel is formed inside the inner tube 142, and the inner tube 142 and the outer tube In the device for forming a solid fuel flow path between the 145, the solid fuel is injected into the tuyere 120 of the blast furnace 112, the inner flow path of the inner tube 142,

(a) a conveying path 142a for conveying the finely divided solid fuel to be blown at a constant speed;

(b) a deceleration path 142b in which the inner diameter of the inner tube is expanded from the contact point with the conveying path to the tip of the inner tube, and the conveying speed of the solid fuel is reduced in the deceleration path and the dispersion width of the solid fuel is increased at the end. The technical gist of the apparatus for solid fuel injection of blast furnace fine powder comprising the improvement of combustibility is set.

Description

Solid fuel injector of fine powder in blast furnace {A PULVERIZED SOLID FUEL INJECTING APPARATUS}

The present invention relates to a solid fuel blowing device for injecting fine powder of fine fuel by replacing expensive coke in the blast furnace making process, and more particularly, to reduce the feed rate of solid fuel and to expand the injection width of solid fuel. It relates to a fine fuel injection device of fine powder that can improve the combustibility.

In the conventional blast furnace making process, as shown in FIG. 1, the iron ore 100, which is a raw material, and the coke 110, which is a fuel, are charged at an upper portion thereof, and hot hot air is blown through the tuyere 120 positioned below the blast furnace 112. By blowing the coke 110 in the combustion zone to produce the molten iron 130 and the slag 132. With the development of technology in the blast furnace making process, the solid fuel injection device 140 of pulverized coal and the like is used to replace the expensive coke 110 at the blower tube 136 of the tuyere 120. The method of blowing solid fuel is used.

In the operation of the blast furnace 112 by the pulverized coal injection method, the coke 110 can not be replaced infinitely with pulverized coal, and a certain amount of coke 110 is present in the furnace to serve as a gas passage. In addition, the pulverized coal that replaces the coke 110 has a total replacement ratio of the coke 110 and 1: 1 when it is completely burned.

However, in some cases, the unburned coal is passed between the layers of coke 110 in the blast furnace 112, and some are discharged to the outside of the furnace, and some are accumulated in the relatively low gas velocity in the layer of coke 110, It increases the size of these deposits, called bird nests. The unburned pulverized coal accumulated in the furnace center not only changes the gas flow, but also decreases the furnace center temperature and increases the ventilation resistance, thereby reducing the size of the combustion zone. The combustibility of the pulverized coal was intensified as the amount of pulverized coal blown increased, resulting in a problem of the increase of the molten iron cost.

As a general technique for reducing such a problem, there is a method of improving the combustibility of pulverized coal by simply incubating pure oxygen in the hot air used in the blast furnace 112. This method is to increase the oxygen concentration in the hot air and promote combustion of pulverized coal by hatching pure oxygen through the tuyere 120 of the blast furnace 112.

However, this method is insignificant, even if it hatches a lot of oxygen because the flow rate of the hot air is large, the oxygen concentration in the hot air is only a few percent increase, so the effect is negligible. In addition, it is expensive to increase the oxygen supply, and in the case of enriching the excess oxygen, it may adversely affect the operation of the blast furnace 112 due to the increase of the direct reduction. It has also been reported that the furnace temperature is unstable by changing the furnace temperature distribution.

One way to solve these problems is to use a double tube lance 140 to blow pure oxygen around the pulverized coal injection pipe. The pulverized coal injection device 140 using the various types of double pipes has been developed. One of them, as shown in Figure 2, the pulverized coal injection device 140 in the form of a double tube, the inner tube 142, the pulverized coal, the outer tube 145 to incubate pure oxygen to the local concentration in the pulverized coal flow path. To increase the combustibility. Such a pulverized coal blowing device is improved in combustibility compared to the conventional art of simply enriching oxygen in hot air, but external oxygen does not penetrate into the pulverized coal flow path, and has a disadvantage of burning only on the outside.

As another example, a spiral oxygen flow passage 148 and a lance 140 having a wide oxygen flow passage at a distal end are formed between the double tubes to form a vortex in the center of the pulverized coal flow passage 150. However, the installation of this spiral flow path 148, as is well known, is a matter of how to set the proper shape to the burner structure. In other words, if the angle of the helical flow path 148 is too deep, oxygen is directed to the outside rather than the inside of the pulverized coal, which results in inferior combustibility. On the other hand, if the angle is too shallow, it is no different from the normal double tube lance 140.

As another example, a single tube expanding lance 140 is known which sufficiently enlarges the diameter of a single tube to cause turbulence in the pulverized coal flow path 150 at the tip of the lance 140. However, this requires a major improvement of the auxiliary equipment, and if the enlarged lance 140 is installed in the tuyere 120, the cross-sectional area of the tuyere 120 is reduced to prevent the inflow of hot air into the blast furnace 112, thereby reducing productivity. Will cause other problems that cause

There is an attempt to increase the combustibility as the eccentric double lance 140 using two single tubes as a different structure. However, when the pulverized coal blown lance 140 is installed in a single tuyere 120 in a double manner, as in the previous case, by reducing the cross-sectional area in the tuyere 120 not only adversely affects the decrease in productivity and stabilization of yellowing, As the number of blown lances doubled, there is a problem that management is cumbersome.

In addition, a method of changing the input angle of oxygen in order to forcibly mix oxygen in the pulverized coal flow path 150 has been attempted. However, in this case, the combustibility is improved, but the flame width is increased, which causes damage to the surrounding air holes 120. The tip of the outer tube 145 protrudes slightly to give an angle is worn out due to the impact of pulverized coal. Has its drawbacks.

The present inventor has proposed in Utility Model Registration Application No. 98-15221 regarding the lance 140 having a groove on the surface of the inner tube 142 to solve this disadvantage (FIG. 3). The flow resistance of the pulverized coal and the flammable liquid are improved by the vortex generated at the tip of the pulverized coal blowing device. In addition, the inventors found that the mixing property varies depending on the shape of the groove formed in the inner tube 142, and the ratio (W / D) of the depth (D) of the groove and the width (W) of the groove is 0.5 to 4 A pulverized coal injection device consisting of the Korean Patent Application No. 99-29067 has been proposed. The present inventors have concentrated their research on ways to improve the combustibility and came to propose the present invention based on the results.

The present invention is to provide a fine fuel injection device of fine powder that can improve the combustibility by increasing the relative velocity of the soft fuel to the solid fuel and increase the dispersion width of the solid fuel.

1 is an explanatory diagram for explaining the general behavior of solids and gases in the blast furnace

2 is a view for explaining the oxygen blowing method according to the prior art,

Figure 2a is a side cross-sectional view of the double tube tip,

FIG. 2B is a cross-sectional view taken along the line A-A of FIG. 2A;

2C is a partial side cross-sectional view showing the configuration of the oxygen flow path formed in the double pipe

Figure 3 is an exemplary view showing in detail the fine fuel injection device of fine powder

Figure 4 is an example of a solid fuel blowing device of the present invention,

4A is a side cross-sectional view

Figure 4b is a functional diagram showing the behavior of pulverized coal in the blowing device

5 is a graph comparing the combustibility of pulverized coal.

Explanation of symbols on the main parts of the drawings

10 ..... Home 100 ..... Sintered Ore

110 .... coke 112 .....

120 .... Punggu 130 .....

132 .... slag 136 .......

140 .... solid fuel injection 142 ..... inner tube

142a .... transport 142b .... slow down

145 .... exterior 148 ..... flammable fluid flow path

150 .. Solid fuel euro

In order to achieve the above object, the fine powder fuel injection device of the present invention,

An inner tube and an outer tube surrounding the inner tube are provided, and a flow path of finely divided solid fuel is formed inside the inner tube, and a flow path of a flammable fluid is formed between the inner tube and the outer tube, so In the apparatus for blowing solid fuel,

The inner flow path of the inner tube is

(a) a conveying path for feeding the finely divided solid fuel to be blown at a constant speed;

(b) It consists of a deceleration path in which the inner diameter of the inner tube is expanded from the contact point with the transfer path to the tip of the inner tube, and the combustion speed is decreased in the deceleration path and the dispersion width of the solid fuel is increased at the tip to improve the combustibility. It is configured to include.

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

The present invention has an inner tube 142 and an outer tube 145 surrounding the inner tube 142, as shown in FIG. 2, and a flow path of finely divided solid fuel is formed inside the inner tube 142. It is intended to improve a fine fuel injection device for fine powder in which a flow path of a flammable fluid is formed between an inner tube and an outer tube. On the surface of this inner tube, it is also possible to form a helical, flammable fluid flow passage 148 as shown in FIG. 3, the groove 10 may be formed on the surface of the inner tube 142.

In general, in the case of injecting solid fuel into the blast furnace by the solid fuel blowing device, finely divided coal is usually used as the solid fuel, and oxygen is generally used as the softening fluid. Therefore, hereinafter, the solid fuel is referred to as pulverized coal and the supporting fluid as oxygen.

The present inventors focused on reducing the discharge rate of pulverized coal in the solid fuel blowing device to increase the relative rate of oxygen, thereby increasing the contact opportunities of pulverized coal and oxygen, thereby improving combustibility. To this end, increasing the diameter of the inner tube of the pulverized coal flow path or reducing the amount of pulverized coal transport air to reduce the discharge rate of the pulverized coal at the tip reduces the relative velocity of oxygen, but it is possible to explode because the flame flows back into the pulverized coal injection pipe due to the backfire phenomenon. There was this.

Therefore, while avoiding such a problem while increasing the relative speed of oxygen while studying the method of increasing the inner diameter at a certain point near the tip of the inner tube, that is, if the inner diameter is inclined as shown in Figure 4 without fear of backflow phenomenon It was noted that not only the discharge rate of pulverized coal is reduced but also the combustibility is improved by increasing the dispersion of pulverized coal.

That is, in the present invention, the flow path of the inner pulverized coal of the inner tube 142 is composed of a conveying path 142a having a constant size of the inner diameter from the blowing point of the pulverized coal to a predetermined point, and the inner tube at the contact with the conveying path. It consists of a deceleration path 142b in which the inner diameter of the inner tube is enlarged to the tip of the inner tube. In this mode, the inner diameter is gradually enlarged, so the feed rate of the solid fuel is reduced and the dispersion width of the solid fuel at the tip is increased. In fact, the pulverized coal injecting apparatus of the present invention is made of a deceleration path in a conventional inner tube.

Since the feed rate of pulverized coal becomes faster as the inner diameter of the inner pipe becomes smaller, the length of the deceleration path is also affected by the feed rate of pulverized coal. In other words, if the feed speed is high, the inner diameter of the inner tube is also reduced. At this time, the deceleration path should be lengthened to reduce the feed speed.

According to one embodiment of the present invention, when the feed rate of pulverized coal in the conveying path 142a is 20 m / sec or less, the length of the deceleration path 142b is preferably 30 cm or less. The reason is that when the length of the deceleration path is larger than 30 cm, the angle of dispersion at the lance tip is reduced, thereby reducing the mixing effect between pulverized coal and oxygen. In addition, when the feed speed of pulverized coal in the feed path 142a is 20 to 50 m / sec, the length of the deceleration path 142b is preferably 30 to 70 cm. The reason is that if the length of the deceleration path is smaller than 30cm, it will exit immediately without seeing the tube enlargement effect. Will decrease.

In addition, the inclination angle θ of the deceleration path is preferably set to 15 to 45 ° based on the center line c of the inner tube in FIG. 4 (a). When the inclination angle is less than 15 °, the injection width is small and not effective. Even if the inner diameter is larger than 45 °, the injection width is not obtained as much. When the length of deceleration road is less than 30cm, the optimal angle of inclination is 20 °.

In the present invention, since the thickness of the inner tube tip becomes thin, it is preferable to coat the heat-resistant material on the lower surface of the inner side of the deceleration path. An example of the heat resistant material is a ceramic material.

Hereinafter, the present invention will be described in detail through examples.

Example 1

In the pulverized coal injection device of FIG. 4, the peak temperature was measured at the tip of the pulverized coal injection device according to the change of the length of the deceleration path, and the results are shown in FIG. 5.

As can be seen in Figure 5, in the case of the present invention it can be seen that the combustion temperature of 50 ~ 300 ℃ or more compared with the conventional case.

As described above, according to the present invention, it is possible to increase the combustibility of pulverized coal, thereby reducing the fuel cost and preventing the accumulation of unburned powder due to the improvement of combustion characteristics, thereby having a useful effect of achieving yellowing stability.

Claims (6)

An inner tube 142 and an outer tube 145 surrounding the inner tube 142, and a flow path of fine solid fuel is formed inside the inner tube 142, and the inner tube 142 and the outer tube In the device for forming a solid fuel flow path between the 145, the flow of a flammable fluid is injected into the tuyere 120 of the blast furnace 112, The inner passage of the inner tube 142, (a) a conveying path 142a for conveying the finely divided solid fuel to be blown at a constant speed; (b) a deceleration path 142b in which the inner diameter of the inner tube is expanded from the contact point with the conveying path to the tip of the inner tube, and the conveying speed of the solid fuel is reduced in the deceleration path and the dispersion width of the solid fuel is increased at the end. A solid fuel injection device for pulverization in a blast furnace, characterized by comprising improved combustion. The solid fuel injection device of the blast furnace fine powder according to claim 1, wherein the length of the deceleration path is proportional to the conveying speed of the solid fuel in the conveying path. The length of the deceleration path is 30 cm or less when the conveying speed of the solid fuel in the conveying path is 20 m / sec or less, and the length of the deceleration path is 30 to 20 to 70 m / sec. Solid fuel injection device of fine powder in the blast furnace, characterized in that 70cm. 4. The solid fuel injector for pulverization according to claim 3, wherein the deceleration path has an inclination angle θ of 15 to 45 ° based on the center line c of the inner tube. 5. The solid fuel injector of blast furnace fine powder according to any one of claims 1, 2 and 4, wherein a heat-resistant material is coated on the lower side of the deceleration path side of the inner tube. 2. The solid fuel injector of blast furnace fine powder according to claim 1, wherein the relative speed of the supporting fluid with respect to the solid fuel is increased to secure a combustion temperature of 2050 ° C or more.