JP2838736B2 - Powder flow blowing nozzle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nozzle for blowing powder together with gas from the bottom of a furnace in a hot metal pretreatment furnace or a converter.

[0002]

2. Description of the Related Art In a hot metal pretreatment furnace and a converter, desulfurization,
For the purpose of dephosphorization and the like, powder such as sodium carbonate and quicklime is blown from the bottom of the furnace together with a gas such as nitrogen, argon and oxygen.

Conventionally used gas blowing nozzles are generally L-shaped as shown in FIG. 2, and are connected to a gas pipe to blow gas into hot metal or molten steel. That is, in FIG. 2, a gas in which powder is mixed in advance is introduced from the gas inlet 2 of the horizontal tube 1. Horizontal tube 1 is vertical tube 3
And the part of the tuyere tube 4 ahead penetrates through the bottom of the furnace body to blow gas into it. In this case, the inner diameter b of the tuyere tube 4 is usually narrowed as compared with the inner diameter a of the gas inlet 2 in order to secure a gas ejection speed that does not allow molten metal to be inserted into the nozzle. For example, in the example of FIG. 2, the inner diameter a of the gas inlet is 50 mm and the inner diameter b of the tuyere tube 4 is 26 mm.
And the cross-sectional area is 27% of the original.

In this case, the diameter of the nozzle is usually reduced at the lower portion 5 of the vertical tube 3 of the nozzle for convenience of use and production. That is, the tuyere tube 4 is a portion that penetrates the brick, and has a simple inner diameter with a simple structure in consideration of consumable replacement. On the other hand, the horizontal pipe 1 is a part to be connected to the supply pipe, and the same pipe as the original pipe is used for ease of work. Therefore, the diameter reduction is performed exclusively in the lower part 5 of the vertical pipe of the nozzle.

[0005]

When the powder is blown in using the nozzle, when the ratio of the powder to the gas, that is, the solid-gas ratio increases, the clogging of the powder occurs frequently. Can't be higher. If the operation is forcibly performed at a high solid-gas ratio, nozzle clogging frequently occurs due to frequent occurrence of nozzle clogging, resulting in the necessity of frequently performing nozzle opening work (drilling), which significantly reduces the work efficiency.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has an L-shaped nozzle for blowing a powder stream into a molten metal. , The inner diameter is reduced toward the tip, the taper ratio is 0.07 or less in any part, and the minimum diameter of the horizontal part is smaller than the maximum diameter of the vertical part. .

[0007]

According to the present invention, the taper of the sectional area of the nozzle is set to 0.07 or less. That is, in the conventional example of FIG. 2, the length d of the reduced inner diameter section is 150 mm, and the original diameter of the lower part of the vertical pipe, that is, the maximum diameter c of the vertical part is 50 m, which is the same as the inner diameter a of the pipe.
m, the inner diameter of the tuyere is 26 mm, and the taper ratio is (50-
26) /150=0.16.

On the other hand, in order to set the taper rate at the limit of the present invention to 0.07, the inner diameter reduction section d is set to 150 mm and the tuyere inner diameter b is set to 26 mm as in the above example (c).
−26) /150=0.07 and the maximum diameter c of the vertical portion is 3
Must be 7 mm.

However, if a pipe having an inner diameter of 50 mm is connected to a place where the root diameter of the vertical portion of the nozzle is 37 mm, the cross-sectional area is reduced at once, which causes nozzle clogging and no improvement. It is preferable that the root of the vertical portion is thicker than the diameter of the horizontal tube, and it should be at least equal in diameter. That is, the L-shape of the present invention
For nozzles, horizontal part (inlet side) and vertical part (outlet side)
Sodium carbonate that has a tapered part to make it soluble
To reduce solidification due to adhesion and compression of
Only by setting the compression zone by this taper
Is at a distance to the discharge port, and solidification increases by maintaining the compressed state
From this point of view, after the compressed part due to the taper,
By relaxing the pressure and dispersing the solidified powder
And found that powder clogging does not occur.
If the minimum inside diameter of the horizontal part is smaller than the maximum inside diameter of the vertical part
This specifies the condition.

Therefore, if the maximum diameter of the vertical portion is 50 mm, which is the same diameter as the horizontal pipe, and the inner diameter of the tip of the nozzle is 26 mm, the length of the diameter reduction section is required to achieve the limit of 0.07 in the range of the present invention. D is (50−26) / d = 0.
07, d = 343 mm is required. This is a numerical value at the limit of the range of the present invention, and it is necessary to set a longer value such as 500 mm in order to obtain a more preferable range.

In the case where the vertical pipe portion can be made extremely long on the equipment, the section d for reducing the inner diameter of the vertical pipe may be made long as described above. However, in many cases, the length of the vertical portion is often limited due to equipment layout. In this case, in the present invention, the horizontal portion of the L-shaped nozzle is also defined as an inner diameter reduction section, so that there is no diameter reduction at the transition from the horizontal portion to the vertical portion. And also in this case, the vertical part,
The taper ratio must be 0.07 or less in any of the horizontal portions. In other words, the inner diameter reduction section may be at least a part, not the entire length of the pipe, and the taper ratio in that part must satisfy the condition of 0.07 or less. In this specification, the horizontal part,
The vertical section is referred to for convenience only when it is attached to the bottom of the furnace in general use and does not necessarily mean that this section of the nozzle must be used horizontally or vertically.

[0012]

FIG. 1 shows an embodiment of a powder flow blowing nozzle according to the present invention. In order to maintain compatibility with the conventional nozzle shown in FIG. 2, the diameter b of the nozzle tip, the diameter a of the gas inlet, the entire length, and the like are the same.

In this example, the maximum diameter c of the vertical portion is 33 mm
And the diameter b of the nozzle tip is 26 mm, and the length d of the diameter reduction section
Is 150 mm, so the taper rate is (33-26) / 1.
50 = 0.047. In the area ratio, the tip is 60% of the root, which is much smaller than the 27% in FIG. The diameter e of the end of the horizontal portion, that is, the portion attached to the vertical portion is 30 mm, which satisfies the condition of the present invention that the maximum diameter of the vertical portion is 33 mm. The length of the horizontal pipe 1 is 400 mm, and during this time the diameter is reduced over the entire length (50-30).
/ 400) = 0.050.

(Application Example) In the hot metal pretreatment, sodium carbonate powder was blown into nitrogen gas at a solid-gas ratio (powder mass flow rate / gas mass flow rate) of 30 from the bottom of the hot metal ladle. The flow rate of the blown gas is 260 m / sec. When the nozzle is clogged, an opening operation (drilling) must be performed. However, in the conventional nozzle of FIG. 2, the opening state after 90 charge processing is 90%, and after 30 charge processing, 50%.
%, Ie, the clogging rate was half.

However, when the nozzle was replaced with the nozzle of the present invention shown in FIG.
0%, which is a remarkable improvement. Also, the pulsation of the gas flow of the blown gas was suppressed. This is considered to be a result of suppressing the generation of the irregular vortex due to the high-speed airflow of 260 m / sec by relaxing the reduction rate of the cross-sectional area.

[0016]

According to the present invention, since the taper rate for reducing the cross section of the powder blowing nozzle is reduced, clogging of the nozzle can be prevented. In addition, since the cross section of the L-shaped nozzle is divided into a horizontal portion and a vertical portion with continuity in both portions, the outer dimensions of the nozzle can be achieved without changing the external dimensions of the conventional product.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of the structure of a powder blowing nozzle of the present invention.

FIG. 2 is a diagram showing a structure of a conventional powder blowing nozzle.

[Explanation of symbols]

 Reference Signs List 1 horizontal pipe 2 vertical pipe a gas inlet inner diameter b inner diameter of tuyere pipe c maximum diameter of vertical part e minimum diameter of horizontal part

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Masaki Ina 5-3 Tokai-cho, Tokai-city, Aichi Prefecture Nippon Steel Corporation Nagoya Works (56) References JP-A-52-5604 (JP, A) 58-15199 (JP, U) 63-39240 (JP, Y2) (58) Fields investigated (Int. Cl. ⁶ , DB name) F27D 3/18 C21C 7/072

Claims (1)

(57) [Claims] 1. An L for blowing a powder stream into a molten metal.
In the character-shaped nozzle, the inner diameter of at least a part of each of the horizontal part and the vertical part is reduced toward the tip, the taper ratio is 0.07 or less in any part, and the minimum inner diameter of the horizontal part is A powder flow blowing nozzle characterized by being smaller than the maximum inner diameter of the vertical portion.