JP5699849B2 - Pulverized coal injection lance for blast furnace - Google Patents

Description

  The present invention relates to a pulverized coal injection lance suitable for injecting pulverized coal as an alternative to a heat source into a blast furnace through a ventilation passage of a tuyere.

  In blast furnace operation, raw iron ore and coke are charged from the top of the blast furnace, and hot air reaching 1200 ° C. is blown from a part called a tuyere provided at the bottom of the blast furnace.

In front of the tuyere in the blast furnace, carbon monoxide gas is generated by the reaction between oxygen and coke in the hot air, and this carbon monoxide gas rises in the blast furnace, and from this carbon monoxide gas and the top of the furnace. The reduction, carburization, and melting processes proceed due to the alternating current reaction with the descending iron ore, and the molten metal accumulates at the bottom of the blast furnace furnace.

  Recently, in order to use pulverized coal that is cheaper than coke and substitutes for a heat source, a blowing lance is inserted and installed in the ventilation passage of the tuyere and the pulverized coal is passed through the blowing lance. Blast furnace operation that blows in is also being carried out.

  In blast furnace operation in which pulverized coal is blown through a blowing lance, it has been considered to be a particularly useful operation method because it can adjust the components of hot metal and slag in the furnace and effectively utilize the pulverized coal. However, the blowing lance is inevitably subject to thermal deformation because it is constantly exposed to high temperatures, which causes pulverized coal to contact the tuyere wall and cause wear. There is concern about causing troubles such as breakage.

  For this reason, measures have been taken to stop the injection of pulverized coal during the operation of the injection lance with a large amount of deformation, but the injection lance that stopped the injection of pulverized coal is partly around the blast furnace. If concentrated, the thermal circumferential balance around the blast furnace will be lost, which will also hinder blast furnace operation.

  As a prior art for improving the conventional problems as described above, the angle of the opening surface of the lance tip of the blowing lance is within a range of ± 30 ° with respect to the tuyere axis. For example, a blowing lance disclosed in Patent Document 1 is known, in which stable blowing of powder is continued without hindering blowing from the tuyere by providing a surface.

JP-A-62-74010

  By the way, in the conventional blowing lance as described above, when the deformation of the powder blowing port changes due to the influence of heat, the pulverized coal applied to the blowing contacts the wall of the tuyere. There is still a problem that the blowing of pulverized coal must be stopped.

  Accordingly, an object of the present invention is to provide a blow that has a relaxed deformation range in which pulverized coal does not come into contact with the wall of the tuyere at an early stage to cause wear even if some deformation occurs. It is in the place of proposing a lance.

The present invention is an injection lance that is arranged in a blow passage of a blast furnace tuyere and blows pulverized coal into the furnace, and the blow lance has an angle toward the blow passage of the blast furnace tuyeres. A lance body to be inserted and a blowing path connected to the lance body, and having a straight pipe portion having an axis parallel to the air passage and having an inclined end face at the opening end, and With the two pipes in which the most protruding parts are back-to-back with each other so as to sandwich the axis of the air passage, and pulverized coal is ejected linearly on the side of the straight pipe part closest to the wall surface of the tuyere It is a blast furnace pulverized coal injection lance characterized by a double lance .

In the blast furnace pulverized coal injection lance having the above structure,
(1) When the inclined end surface is based on a straight line orthogonal to the axis of the straight pipe portion, an angle formed with the reference is 10 ° or more and 15 ° or less. (2) As the angle, More preferably, it should be 12 ° ± 0.2,
Is preferable as a specific means for solving the problems of the present invention.

According to the blast furnace pulverized coal injection lance according to the present invention, the injection lance is inserted obliquely at a desired angle into the air passage of the blast furnace tuyere, and the injection path connected to the lance main body. the provided, constituted by a straight pipe section with parallel axis to the air passage, the opening end of the straight tube portion, due to the provision of the inclined end face directed towards the wall of the air passage, of the straight pipe portion On the side closest to the wall surface of the blast furnace tuyere, the pulverized coal that is blown in will be ejected along the wall surface of the blast furnace tuyere. Thereby, even if the deformation | transformation which changes the direction of the jet nozzle of a blowing lance somewhat is caused by heat influence etc., pulverized coal does not contact the wall surface of a tuyere early.

Further, according to the blast furnace pulverized coal injection lance of the present invention, the angle of the inclined end surface is 10 ° or more and 15 ° or less, more preferably, based on a straight line perpendicular to the axis of the straight pipe portion. Therefore, the blowing angle of the pulverized coal ejected from the most projecting portion side of the inclined end surface is increased, and the combustion efficiency of the pulverized coal is improved.

Furthermore, according to the blast furnace pulverized coal injection lance having the above-described configuration, a double lance is formed as a set of two, with the most protruding portions at the open end of the straight pipe portion spaced apart from each other. This makes it possible to efficiently blow pulverized coal.

It is the figure which showed typically the pulverized-coal blowing lance according to this invention about the plane. It is the figure which expanded and showed the straight pipe | tube part of the blowing lance shown in FIG. It is the figure which showed the blowing condition of the pulverized coal by the conventional blowing lance. It is the figure which showed and showed the change of the blowing rate of pulverized coal.

Hereinafter, the present invention will be described more specifically with reference to the drawings.
FIG. 1 is a diagram (plan view) schematically showing an embodiment of a pulverized coal blowing lance according to the present invention in a state where it is assembled to a blast furnace tuyere.

  In the figure, reference numeral 1 is a tuyere arranged at the lower part of the furnace body of the blast furnace, and 2 is a blow pipe connected to the rear end of the tuyere 1 to hold the tuyere 1. The blow pipe 2 and the tuyere 1 are provided at a plurality of locations around the blast furnace, and hot air can be blown into the blast furnace through the air passages M.

Reference numeral 3 denotes a pulverized coal blowing lance. The pulverized coal injection lance 3 is shown as a double lance arranged on the left and right with the shaft core 1a of the tuyere 1 interposed therebetween, and is inserted into the blast furnace tuyere air passage M with a desired angle. The main body 3a and the lance main body 3a are provided with a blowing path connected to the lance main body 3a. The straight pipe portion 3b has an axis L parallel to the air passage M of the tuyere 1.

Reference numeral 4 denotes an inclined end surface provided at the opening end of the straight pipe portion 3 b of the blowing lance 3. The inclined end face 4 has an angle directed to the wall surface of the air passage M.

In the blowing lance having the above-described configuration, the pulverized coal that has passed through the lance body 3a is blown in the state shown in FIG. 2 from the opening end (protruding end) of the straight pipe portion 3b. That is, since having an inclined end face 4 of the open end of the straight pipe portion 3b is directed to the wall of the air passage M, the side closest P ₁ on the wall of the tuyere of the straight pipe portion 3b, the lance body 3a for ejecting linearly from the straight tube portion 3b, while ejected substantially parallel pulverized coal along the wall surface of the tuyere 1, in the cutting edge side P ₂ of the protruding section is formed, the anti tuyere 1 It spouts so that a discharge angle may spread toward the wall surface side.

  For this reason, even if the lance itself is slightly deformed due to thermal influences, the pulverized coal applied to the blow does not easily come into contact with the wall surface of the tuyere 1, and the center of the air passage M In the area, the pulverized coal tends to be diffused, so that the combustion efficiency is improved.

In particular, the above-described effect becomes even more prominent by using a double lance that is a pair of _two that are back-to-back with each other on the cut end side P2 formed by the inclined end surface 4 . In addition, although the straight pipe part 3b has the axial core L parallel to the ventilation path M of the tuyere 1, since this axial core L is parallel to the ventilation path M, it does not inhibit blowing in hot air. In addition, pulverized coal can be injected.

For inclined end face 4, in the present invention, based on the straight line L ₁ perpendicular to the axis L of the straight tube portion 3b, and an angle θ with the reference L ₁ 10 ° or more, 15 ° or less, more preferably, 12 Although it is set in the range of ± 0.2, the straight pipe portion can be obtained by keeping the angle θ of the inclined end face 4 in the range of 10 ° to 15 °, more preferably 12 ° ± 0.2. The spray angle of the pulverized coal from 3b is most stable, the contact of the pulverized coal with the wall surface of the tuyere 1 is avoided, and the pulverized coal can be effectively blown.

  Since the blowing lance according to the present invention can further extend the period until it becomes difficult to blow pulverized coal due to thermal deformation, the number of blowing lances that stop pulverized coal blowing is reduced. In addition, the number of replacement blast lances can be significantly reduced.

  In addition, the heat balance around the blast furnace becomes good, leading to stable blast furnace operation.

  Inclination end face angle θ: 12 ° 20A, Sch80 (JIS G3459) blowing lances are arranged as shown in Fig. 1 under the conditions of blowing amount (90kg / t · hot metal, 120kg / t · hot metal). The period from when pulverized coal is blown into the blast furnace until it becomes difficult to blow pulverized coal (until the pulverized coal comes into contact with the tuyere wall due to thermal deformation of the blowing lance itself and causes wear. ).

  As a result, in the pulverized coal injection using the injection lance having a flat tip surface as shown in FIG. 3, the period until the replacement of the injection lance was 107 days on average. In the blowing with the blowing lance according to the present invention, the average was 194 days, and it was confirmed that the service life (life) of the blowing lance can be significantly extended.

  Along with this, the number of blowing lances used annually has been reduced by about 80.

  Regarding the blowing rate of pulverized coal (injectable tuyere / all tuyere), when the blowing lance according to the present invention is used in the situation shown in FIG. It was found that the pulverized coal injection rate was improved by an average of about 5% compared to the injection by the lance lance (comparative example).

  ADVANTAGE OF THE INVENTION According to this invention, a deformation | transformation tolerance range is expanded and the pulverized coal blowing lance for blast furnaces which can continue blowing pulverized coal over a long term can be provided.

1 tuyere 1a shaft core 2 blow pipe 3 pulverized coal blowing lance 3a lance body 3b straight pipe portion 4 inclined end face M air passage

Claims (3)

A blow lance that is arranged in the air passage of the blast furnace tuyere and blows pulverized coal into the furnace,
The blow lance includes a lance body inserted at an angle into the blow passage of the blast furnace tuyere and a blow passage connected to the lance body, and has an axial core parallel to the blow passage and an open end. The tuyere of the straight pipe part, which is composed of a straight pipe part provided with an inclined end face, with the most projecting part of the open end being back to face with each other so as to sandwich the axis of the air passage. A blast furnace pulverized coal injecting lance, characterized in that it is a double lance that forms a pair of pulverized coal in a straight line on the side closest to the wall of the blast furnace. 2. The angle according to claim 1, wherein the inclined end surface has an angle of 10 ° or more and 15 ° or less with respect to a straight line orthogonal to the axis of the straight pipe portion . Pulverized coal injection lance for blast furnace.   The blast furnace pulverized coal injection lance according to claim 2, wherein the angle is 12 ° ± 0.2.

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