JPH0533032A - Powder blowing lance - Google Patents

Abstract

(57) [Summary] [Purpose] Even when powder is blown into molten metal at high speed, splashing and metal overflow are prevented and stable operation is possible. A powder injection device into a molten metal having a combination of a powder supply system and a powder injection lance 1 having a powder discharge hole connected to the powder supply system. Two independent supply systems are provided, and the powder powder blowing lance 1 has four independent discharge holes 12, 12, 12, 12 connected to the powder supply system on the same horizontal plane. The above-mentioned discharge port has a powder discharge direction of 90
Cross each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder blowing lance which can be used for blowing powder into a molten metal.

[0002]

2. Description of the Related Art FIG. 4 shows an example of a conventional powder blowing apparatus into molten metal such as hot metal or molten steel during hot metal pretreatment or secondary refining of molten steel. As shown in the figure, conventionally, a powder 5 of a refining agent, such as a hot metal desulfurizing agent, housed in a dispenser 4 is transported by a gas 8 for transporting a powder such as N ₂ gas to a transport pipeline 3 It is conveyed to the powder blowing lance 1 via. That is, the powder 5 is transferred into the molten metal 7 by the powder-transporting gas 8 that is pressure-fed from the transport-gas pressure-feeding device (not shown) via the powder-supplying system including the dispenser 4 and the transport pipeline 3. It is transported to the immersed powder blowing lance 1. Then, at the tip of the powder injection lance 1, there are two discharge ports 12, 1 in a direction intersecting with each other by 180 °.
The powder discharge hole 2 having 2 is provided, and the powder 5 is blown into the molten metal 7 together with the powder carrying gas 8 through the two discharge ports 12, 12.

By the way, in recent years, there has been a demand for increasing the blowing speed of the powder 5 into the molten metal 7 in order to further improve the productivity. To meet this demand, In the above-mentioned conventional apparatus, the powder conveying gas 8
It was necessary to increase the gas flow rate of. However, in the conventional apparatus shown in FIG. 4, when the gas flow rate of the powder-conveying gas 8 is increased, splash and overflow of metal are generated, and stable operation cannot be performed.

Further, as shown in FIG. 5, four discharge ports (cross type) 12 whose discharge directions are orthogonal to each other and are connected,
There is also known a device in which a powder discharge hole 2 ^′ having 12, 12, 12 is provided at the tip of the powder injection lance 1 to increase the injection speed to suppress the occurrence of the splash or the overflow of metal. However, this device has a problem that one of the powder discharge holes 2 ^′ is closed by the insertion of the metal from the tip of the powder injection lance 1, and a countermeasure against it. As a result, even if the flow velocity of the powder carrying gas 8 is further increased, it will flow out from the remaining three discharge ports 12, 12, 12, and the discharge port 12 once closed cannot be opened.
It was not easy to blow the ink from the book outlets 12, 12, 12, 12 to perform stable operation.

Therefore, various techniques have been proposed in the past for stably blowing powder into molten metal.
For example, in Japanese Patent Laid-Open No. 51-117114, as shown in FIG. 6, the powder 5 is supplied into the molten metal 7 without using any powder carrying gas for carrying the powder 5. , By the compression delivery device 9,
The powder 5 cut out from the hopper and stored in the storage tank 10 is added to the molten metal 7, and the stirring gas 11 is blown into the molten metal 7 from the powder injection lance 1 formed integrally with the pipe 20. A technique for refining the added powder 5 and the molten metal 7 by sufficiently bringing them into contact with each other is disclosed in Japanese Patent Laid-Open No. 2-8315, as shown in FIG. A technique for suppressing the surface roughness of the molten metal by rotating the powder blowing lance 1 in the molten metal 7 when the powder is blown from the powder blowing lance 1 into the molten metal 7 has been proposed. ..

However, in the technique shown in FIG. 5, there is a problem such as blockage due to insertion of the metal from the tip of the powder blowing lance 1, which is difficult to implement.

Further, the prior art shown in FIG. 6 has a problem that the equipment cost is high and the stability and durability are lacking.
Its implementation is difficult.

[0008]

Therefore, the inventors of the present invention have previously proposed, by Japanese Patent Application No. 3-33029, a powder supply system (including a straight pipe) and a powder supply system installed in a powder injection lance. We have proposed a technique in which a plurality of discharge holes are installed independently and the powder is blown into the molten metal through the plurality of powder discharge holes.

According to this technique, the dispersibility of the powder in the molten metal is improved, the vibration of the molten metal bath is also reduced, and splash and overflow of metal can be reduced.

However, as a result of further studies by the present inventors, in this technique, when the powder injection lance is eccentric or when the lengths of a plurality of straight pipes provided are different (that is, all the discharge ports are provided). It has been found that it is difficult to stably discharge the powder from the plurality of powder discharge holes because the pressure loss values in the straight pipes of the powder supply system are different when the two are not on the same horizontal plane). ..

Further, the present inventors have also found that due to the eccentricity of the powder injection lance, the strength of the refractory material decreases in the straight pipe portion, especially in the vicinity of the nozzle, and damage easily occurs. ..

[0012] Here, the object of the present invention is Japanese Patent Application No. 3-3302.
By further improving the powder injection lance proposed by No. 9,
It is an object of the present invention to provide a powder blowing lance that can stably supply powder and does not cause problems such as breakage.

[0013]

As a result of various studies to solve the above-mentioned problems, the present inventors have found that in order to solve the above-mentioned problems, they are arranged inside the powder injection lance independently of each other. Equal distances from the upper ends of the plurality of straight pipes that are provided to convey powder to the powder discharge holes, that is, all discharge ports installed in the plurality of powder discharge holes are installed on the same horizontal plane. It was found that it was necessary.

The present inventors have completed the present invention as a result of further studies based on such findings.

Here, the gist of the present invention is that it is connected to a plurality of straight pipes, which are arranged in parallel independently of each other, and which conveys powder therein, and the respective tip portions of these straight pipes. A powder blowing lance with a powder discharge hole,
(i) The plurality of straight pipes have the same distance from the upper end to the powder discharge hole, and (ii) the powder discharge hole has a plurality of discharge ports. It's a combined lance.

In the present invention, the shape of the powder discharge holes respectively provided at the tips of a plurality of straight pipes, that is, the number of the powder discharge ports installed, the angle formed by each powder discharge port, and the powder discharge direction are the same. Is desirable.

[0017]

The operation of the present invention will be described in detail below. According to the present invention, the powder feeding gas, which is pressure-fed by the feeding gas feeding device connected to the powder feeding system, through the powder feeding system configured by the dispenser and the transport pipeline, When the body is blown into the molten metal from the powder discharge hole through the straight pipe incorporated in the powder blowing lance immersed in the molten metal, the powder supply system and the straight pipe are independently operated. In addition to providing a plurality of powder discharge holes, powder discharge holes respectively connected to the straight pipes are also provided independently of each other, and each powder discharge hole is provided with two or more discharge ports.

Therefore, when the powder blowing lance according to the present invention blows the powder into the molten metal at the same powder blowing speed as the conventional one, the number of discharge ports installed is two, compared to the conventional device. In the apparatus according to the present invention, since the number of discharge ports installed is increased to 4 or more, the dispersibility of the powder in the molten metal is improved, and the vibration of the molten metal bath is also reduced, resulting in splash or splash. The overflow of metal injection can be reduced.

Conventionally, there has been known a technique for discharging powder from four discharge ports provided at the tip of a powder blowing lance through one powder supply system, but this technique is used. Since there are not a plurality of straight pipe parts, there was a limit to increase the powder injection amount. Even if the powder blowing speed is increased, if one discharge port is clogged due to a metal insert, the other 3
The powder supply gas was pressure-fed from one discharge port, and the operation had to be stopped in order to remove the clogging, and it was difficult to perform stable operation. On the other hand, according to the present invention, by using a plurality of straight pipes, it is possible to independently control the powder injection speed of each powder supply system, so that the powder injection amount can be significantly increased. Can be increased,
It is possible to blow powder stably without splashing. In the present invention, when the powder discharge hole is clogged or is likely to be clogged, the flow velocity of the powder carrying gas of the powder supply system connected to the powder discharge hole is changed. It may be raised to remove or prevent clogging.

Further, in the present invention, since the distances from the upper ends of the plurality of straight pipes to the powder discharge holes are equal, the values of pressure loss in these straight pipes can be made the same. Move the powder discharge hole up and down the lance (vertical direction)
Can be installed at the same height, that is, a plurality of discharge ports can be arranged on the same horizontal plane.

By arranging the plurality of discharge ports so as to be on the same plane and symmetrical with each other, the powder can be uniformly blown into the molten metal, and the plurality of straight pipes can be used. Even if a large amount of powder is blown, splash and overflow of metal can be reduced, and since the strength of the refractory material in the nozzle portion can be increased, the life of the powder blowing lance can be extended.

In the present invention, the number of powder supply systems installed is
It may be two or more lines. Further, by providing two or more discharge ports in one powder discharge hole as shown in FIG. 4 described above, according to the present invention, the discharge port is 4 at the tip of the powder blowing lance. One or more are provided.

Further, in the powder blowing lance according to the present invention, it is preferable that the total number of the discharge ports is four or more and the discharge directions of the powder are arranged so as to intersect each other. It is desirable from the viewpoint of promoting dispersion in the metal. For example, if the total number of discharge ports installed is 4, the powder discharge directions intersect 90 ° each, and if the total number of discharge ports installed is 6, the powder discharge directions are 60 ° each. It is desirable to install powder discharge holes at the tip of the powder injection lance so that they cross each other.
(See Figure 3 below).

The powder conveyed in the present invention does not require any limitation. For example, a refining agent such as a hot metal desulfurizing agent (quick lime, soda ash) may be used. That is, the powder to be blown in practicing the present invention may be one kind or two or more kinds. Quicklime powder and soda ash powder at the time of desulfurization of the hot metal, by different powder supply system in the present invention,
By blowing into the molten metal, it is possible to reduce the number of steps for preliminarily mixing a plurality of powders, and this is preferable.

In the present invention, the powder feeding gas pressure-feeding device connected to the plurality of powder feeding systems may be installed either singly or two or more. That is, any structure may be used as long as the flow velocity of the powder carrying gas in each of the plurality of powder supply systems can be independently controlled by an appropriate structure. Hereinafter, the present invention will be described in detail with reference to the embodiments embodied by the accompanying drawings, but these are merely examples of the present invention and the present invention is not limited thereto.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a powder injection lance 1 according to the present invention.
FIG. 2 is a schematic explanatory view showing a configuration of an example of a powder blowing device into a molten metal using, and FIG. 2 is a schematic sectional view showing a configuration example of the powder blowing lance 1. Note that, in FIG. 2, schematic horizontal cross-sections on each of the AA plane and the BB plane are also shown. In the apparatus shown in FIG. 1, the powder 5 is fed together with the powder carrying gas to a powder blowing lance 1 by a powder carrying gas pressure feeding device (not shown), and the molten metal 7 is fed from the powder blowing lance 1. It is configured to be conveyed in.

Then, the powder 5 is added to the powder blowing lance 1.
In this embodiment, the powder supply system for pressure-feeding is
By providing 3b), there are two systems. The transport pipeline 3a and the transport pipeline 3b are independent of each other, and the powder 5
The powder carrying gas 8 is supplied by two powder carrying gas pressure feeding devices. Transport pipeline 3a and transport pipeline 3b
Are guided to the powder blowing lance 1 and, as shown in FIG. 2, two powder lances 1 each independently provided side by side are provided with a refractory coating layer on the outer surface thereof. It is connected to the straight pipe 6a and the straight pipe 6b, and the powder discharge hole 2
a and 2b are provided.

That is, in FIG. 2, on the respective lower ends of the two straight pipes 6a and 6b, the straight pipes 6a and 6b are branched into two discharge ports 12, 12. Discharge port 1
2, 12, 12, and 12 are installed in the same plane such that their discharge directions intersect each other by 90 °. The blowing direction of the powder 5 is
Discharge port 12, which is configured to have two different directions by 90 °
The powder discharge hole 2a and the powder discharge hole 2b having 12 are provided on the same plane such that their discharge directions intersect each other by 90 °.

FIG. 3 shows another modification, in which three straight pipes 30, 32 and 34 are provided. Other configurations are the same as those in FIGS. The powder blowing lance having such a structure is particularly useful for refining ultra-low sulfur steel. In addition, in FIG. 3, the CC cross section and the DD cross section are shown together.

In other words, in the present embodiment, the powder in the molten metal having the powder supply system and the powder injection lance having the powder discharge hole connected to the powder supply system in combination is used. In the blowing device, (i) each of the two powder supply systems is independently provided, and (ii) each of the powder injection lances is connected to the powder supply system. It has a total of four independent discharge ports, and (iii) the discharge ports are formed on the same plane so that the powder discharge directions intersect by 90 °.

In the apparatus shown in FIGS. 1 and 2, powder 5 such as desulfurizing agent is contained in the dispenser 4a and the dispenser 4b.
Are configured to be blown into the molten metal 7 through the powder discharge holes 2a and the powder discharge holes 2b provided in the powder injection lance 1, which are independent of each other. Using the apparatus shown in FIGS. 1 and 2, the content of S is 0.026% by weight.
50 tons of hot metal was desulfurized. In this example,
The powder 5 was desulfurized by using a desulfurizing agent consisting of 95% quicklime + 4% fluorspar + 1% soda ash, and the powder-conveying gas 8 was N ₂ gas.

The results are shown in Table 1 in comparison with the case where the same desulfurizing agent and the powder carrying gas were used to desulfurize the hot metal in the same manner as in the conventional apparatus shown in FIG. The desulfurization efficiency index is [(before desulfurization [S]) ^1/2 − (after desulfurization [S]) ^1/2 ] /
It was obtained from the ratio of the desulfurizing agent basic unit, and the blow-in overflow index was obtained from the weight ratio of hot metal dust in the blow-out sampling box located below the pan.

[0033]

[Table 1]

As is clear from Table 1, according to the present invention, although the blowing rate of the defluent is increased,
Both the desulfurization efficiency and the overflow are the same as before,
It can be seen that the desulfurization treatment time can be reduced by the amount by which the blowing rate of the desulfurization agent is increased. From the above, the effect of the present invention is clear.

[0035]

As described in detail above, according to the present invention, even if the powder is blown into the molten metal at a high speed, the splash and the overflow of the ingot are hardly generated, and the powder is uniformly blown into the molten metal. Can be injected, and the powder blowing refining can be performed more efficiently. The practical significance of the present invention having such effects is extremely remarkable.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing the configuration of an example of a powder blowing device into molten metal using a powder blowing lance according to the present invention.

FIG. 2 is a schematic sectional view showing a structural example of a powder injection lance according to the present invention.

FIG. 3 is a schematic explanatory view showing another configuration example of the powder blowing lance according to the present invention.

FIG. 4 is a schematic explanatory view showing an example of a conventional powder injection device into molten metal.

FIG. 5 is a schematic explanatory view showing still another example of the conventional powder injection device into molten metal.

FIG. 6 is a schematic explanatory view showing a technique proposed by JP-A-51-117114.

FIG. 7 is a schematic explanatory view showing a technique proposed by Japanese Patent Laid-Open No. 2-8315.

[Explanation of symbols]

1: Powder injection lance 2, 2 ', 2a, 2b: Powder discharge hole 3, 3a, 3b: Transport pipeline 4, 4a, 4b: Dispenser 5: Powder 6a, 6b, 30, 32, 34: Straight pipe 7: Molten metal 8: Gas for powder transportation 9: Compressing and delivering device 10: Storage tank 11: Agitation gas 12: Discharge port 20: Pipe

Claims (1)

Claim: What is claimed is: 1. A plurality of straight pipes, each of which is arranged independently of each other and which conveys powder therein, and powder discharge holes connected to the respective tip portions of these straight pipes. And (i) the plurality of straight pipes have the same distance from the upper end to the powder discharge hole, and (ii) the plurality of powder discharge holes are provided. A powder injection lance characterized by having a discharge port.