JPS6013405B2 - Tuyeres for molten metal smelting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a refining furnace for molten metal such as molten steel, such as an AOD furnace, a Q
- Concerning 〇 such as BOP furnace, composite blowing mirror furnace, ladle refining furnace, etc.

In recent years, in the refining of molten metals such as molten steel, 02 gas, Ar gas, CO gas, C
AOD furnace, Q-BOP furnace, which blows iron by blowing refining gas such as 02 gas, N2 gas, hydrocarbons, or waste gas,
A compound blow sickle furnace, etc. is used.

By the way, the blades of this type of furnace are those with a single tube structure in which refining gas and fly gas are blown in alternately, and those with a tuyere structure in which oxygen gas is injected into the inner tube and tuyeres into the outer tube, as used in bottom-blown converters, etc. A double tube that allows cooling hydrocarbon gas or a mixed gas of oxygen and inert gas to flow through the inner tube and inert gas through the outer tube independently and in parallel, as used in AOD furnaces. There are various structures such as those with different structures, but when looking for any structure, although there are slight differences in the degree,
Not only does it cause localized erosion in the form of dovetails on the surrounding refractories, significantly shortening the life of the refractories, but it also causes instability in the refining action and reduces the refining effect.
There were inconveniences such as having to replace the surrounding wall early. The present inventor conducted an experiment using a water model regarding the damage phenomenon that occurs in the refractories surrounding the blade □ as described above, and found that the refining gas and the fly gas jet blown into the molten metal from the blade □ A so-called blowback phenomenon occurs in which the refractory is blown back toward the blade □ at a period of An extremely large temperature gradient is formed between a certain wing □ itself and the refractory surrounding the wing □, which is heated to a high temperature by the molten metal, and as a result, the refractory surrounding the wing □ is subjected to large thermal stress. Spalling occurs and the peeling and falling of the refractory is accelerated, and the feather □
Since the blade itself is in a cooling state, molten metal solidifies and adheres to the tip of the blade facing into the furnace in the form of a scab, which obstructs the injection of refining gas and condensed gas from the tuyere. , the blown refining gas, sandalwood gas, etc. are reflected from the scab-like solidified material onto the surrounding refractories, accelerating their wear and tear. It has been found that it is extremely effective to allow protective gas to pass through in the form of bubbles from around the inlet of the refining gas and fly frame gas in order to eliminate the thermal stress caused by the inlet. The present invention has been made based on this knowledge, and its purpose is to provide a pipe for blowing refining gas and/or frame gas into molten metal, a pipe disposed around the pipe, and a porous refractory for blowing a protective gas into the molten metal, and by providing a gap between the outer circumferential surface of the tube and the porous refractory to allow the protective gas to flow, the porous refractory can be removed from the porous refractory in the form of bubbles. The jet of refining gas, etc. is stabilized by the protective gas blown into the
In addition to suppressing the occurrence of the blowback phenomenon, it also prevents crust-like condensation from adhering to the blade □, and furthermore, by relatively reducing the amount of protective gas flowing inside the porous refractory, the blade □
To provide a tuyere for molten metal refining which can lower the temperature gradient with surrounding refractories and reduce thermal stress of the surrounding refractories.

The present invention will be specifically described below based on drawings showing embodiments thereof.

Fig. 1 is a partial sectional view of a composite blow sickle furnace showing the state in which the blade for smelting molten metal according to the present invention (hereinafter referred to as the product of the present invention) is used, and Fig. 2 is an enlarged view of the product of the present invention in a horizontal position. 3 is a sectional view taken along line mm in FIG. 2, and FIG. 4 is a sectional view taken along line W-W in FIG. The iron shell, F2, also indicates the furnace body refractory,
The product of the present invention is disposed upwardly through the bottom wall of the composite blowing sickle body F, and includes a supply pipe, a flexible tube T,
The refining gas supplied through the supply pipe 2 and the protective gas supplied through the flexible tube L are respectively blown into the composite blowing sickle furnace F from the bottom wall side thereof. The feather row of the present invention has a nozzle 2 and a header 3 attached to its base end as its main components.

The nozzle part 2 includes a pipe 21 that forms a refining gas flow path for blowing a refining gas such as oxygen gas (may be fly gas) into the molten metal, and is disposed around the outer periphery of this pipe 21.
A porous refractory 22 forming a protective gas flow passage into which a protective gas such as carbon dioxide is blown, and a protective gas flowing through the porous refractory 22 that is closely attached to the outer peripheral surface of the porous refractory 22. In addition, the tube 21 is provided with a cannula 23 for regulating the castle.
A gap 24 is provided between the outer peripheral surface of the porous refractory 22 and the porous refractory 22 to allow the protective gas to flow therethrough. The pipe 21 is formed of a metal pipe with a circular cross section, and is installed to pass through the steel skin F and the furnace body refractory F2 on the bottom wall of the composite blowing furnace F, and the tip end is inserted into the composite blowing furnace F. The opening is closed, and the base end is connected to the lid 3 of the header 3 via a male screw 21a formed on the outer peripheral surface thereof.
It is screwed and connected to a refining gas supply port 32a opened at the center of 2. The porous refractory 22 has a thick cylindrical shape made of a heat-resistant material that allows the flow of protective gas, such as porous brick, and is formed so that its length in the axial direction is slightly shorter than that of the tube 21. The inner diameter of the tube 21 is larger than the outer diameter of the tube 21, and the outer diameter gradually decreases from the proximal end to the distal end. A plurality of ribs 22a supporting the outer circumferential surface of the tube 21 are equally spaced in all directions around the entire axial length. This porous refractory 22 has its ribs 22 a in contact with the outer circumferential surface of the pipe 21 , with a slight gap 24 formed between the outer circumferential surface of the tube 21 and the inner circumferential surface of the porous refractory 22 . The tube 21 is laid out in the same shape as the tube 21, and in this state, it penetrates the steel skin F and the refractory F2 on the bottom wall of the composite blowing sickle furnace F, and the tip end of the tube is inserted into the composite blowing mirror body F. It opens in the same plane as the distal end of the header 21, and the proximal end is inserted and held in the cylindrical part 33a of the fitting 33 in the header 3. The cannula 23 is made of thin-walled metal, and its inner and outer diameters are formed with striped diameters from the proximal end to the distal end in accordance with the outer diameter of the porous refractory 22. The length is slightly shorter than that of the porous refractory 22. This cannula 24 is closely fitted with the porous refractory 22 with its distal end aligned with the distal end of the porous refractory 22, and its proximal end is inserted into the cylindrical portion 33a of the fitting 33 in the header 3 as required. It is welded to the cylindrical portion 33a in the dimensionally inserted state. The porous refractory 22 is not limited to porous bricks, etc., and can reduce the thermal WS force formed in the furnace refractory connected to the outer periphery to below the allowable value of the refractory. Any material may be used as long as it allows the protective gas to flow into the furnace in the form of bubbles, and any conventionally known material may be used as appropriate.

In addition, the gap 24 to be formed between the outer circumferential surface of the tube 21 and the inner circumferential wall of the porous refractory 22 allows a thin flow of protective gas sufficient to cool and maintain the tuyere hardware including the tube 21 below a certain temperature. The cross-sectional area is set to have the desired cross-sectional area. Porous refractory 22
The cross-sectional shape of the gap 24 is not particularly limited to the above-mentioned embodiments, but may be of any shape as long as it satisfies the above conditions. On the other hand, the header 3 is made up of a cylindrical casing part 31, a lid body 32 fixed to the opening at one end of the casing part 31, and a fitting 33 fixed to the closed end part of the casing part 31. Become. The casing part 31 is constructed by forming flanges 31b and 31c on the outer periphery of both ends of a short cylinder 31a, and interposing a seal ring 31d on the inner circumferential surface of the base end, and the inner diameter thereof is the same as the outside of the base end of the porous refractory 22. It is made approximately equal to the diameter. The lid body 32 is constructed by forming a refining gas supply port 32a in the center of a circular plate having approximately the same size as the diameter of the flange 31b of the casing portion 31, and a protective gas supply port 32b at a position off the center. It is removably fixed to the casing part 31 with bolts and nuts 34 in a state where the cylindrical part is closely overlapped with the flange 31b of the casing part 31. A female thread is formed on the inner peripheral surface of the supply port 32a in the lid body 32, and the base end of this female threaded tube 21 is connected to the male thread 21.
The supply port 32b has one end of an elbow 32c bent at an angle of 90° on the inner side.
The other end is welded with the other end oriented parallel to the connection direction of the inner circumferential surface of the casing portion 31, as shown by the blank mark in FIG. Each of the supply ports 32a and 3 is provided on the outer surface side of the lid body 32.
2b are integrally formed with cylindrical caps 32d and 32e concentrically, and a flexible tube T, which is connected to a refining gas supply pipe, and a protective gas supply pipe 2, are integrally formed with the caps 32d and 32e. Flexible tubes T2 are connected to each other. The fitting 33 is formed by providing a flange 33b on the outer periphery of one end of the cylinder 33a.
The inner diameter of the porous refractory 22 is equal to the outer diameter of the base end of the porous refractory 22 between the dimensions corresponding to the thickness of the flange 33b at the base end, and the other portions are porous as they go from the base end side to the tip side. The vertical diameter is set to match the outer vertical diameter ratio of the refractory 22. A seat 33c for inserting a seal ring 33e is formed on the inner peripheral surface of the proximal end of the cylindrical body 33a, and a seat 33d into which the sleeve 23 is inserted is formed on the inner peripheral surface of the distal end. The fitting 33 has a seal ring 33e interposed on the seat 33c, and the flange 33b is connected to the flange 31c on the casing 31.
It is integrally fixed to the steel skin F with bolts 35 in a state where it is supported by the steel shell F. Inside the header 3 is a casing part 31,
Lid body 32, fitting 33, porous refractory 22, pipe 2
1 is formed, and the protective gas from the elbow 32c is injected into the distribution chamber 37.
As shown by the missing marks in the figure, a portion of the refractory is supplied from the distribution chamber 37 into the gap 23 and a pond portion is supplied into the porous refractory 22 while being circulated. In the product of the present invention, the refining gas supplied through the supply pipe T, the flexible tube T, is introduced into the pipe 21 through the base 32d and the supply port 32a, and passes through the pipe 21 to form the composite blowing mirror. It is blown into the furnace F. On the other hand, the protective gas supplied through the flexible tube T2 is introduced from the elbow 32c into the distribution chamber 37 in the circumferential direction through the base 32e and the supply port 32b, and is then pumped from inside the distribution chamber 37 at the required pressure. A portion is introduced into the gap 23 formed between the pipe 21 and the porous refractory 22, and a pond portion is introduced into the base end side of the porous refractory 22.

The protective gas introduced into the gap 24 is guided by the ribs 22, cools the tube 21 along the outer peripheral surface of the tube 21, and moves toward the tip side, and is blown into the compound blower F from the tube 21. It is blown in such a manner that it surrounds the outer periphery of the refining gas. Further, the movement of the protective gas injected into the porous refractory 22 is restricted by the pipe 21 and the cannula 23, and moves toward the tip side, and the protective gas is blown into the composite blow sickle furnace F through the gap 23. The gas is further blown into bubbles so as to surround the outer periphery. Therefore, in the product of the present invention, the temperature of the tube 21, which is the metal fittings, can be cooled down to a predetermined temperature or less without causing melting damage, etc., by the protective gas flowing through the gap 23, and the protective gas can be cooled down to a predetermined temperature that does not cause melting damage. By flowing through the refractory 22, the flow rate of the protective gas is suppressed, and a steep temperature gradient is prevented from being formed in the furnace refractory F2 adjacent to the furnace body refractory F2 across the mantle 23. To eliminate the formation of thermal stress exceeding the allowable value in the refractory F2.

Furthermore, the protective gas that has passed through the porous refractory 22 is transferred to the composite blowing furnace F.
This stabilizes the jet of refining gas and/or waste gas that is blown into the complex blowing furnace F, suppresses the blowback phenomenon, and prevents the blowback phenomenon from occurring inside the furnace. It is possible to prevent molten metal from solidifying and adhering in a basket-shaped manner around the wing □ facing the front. In the embodiment described above, the tube 21 and the porous refractory 22 are placed concentrically, and the protective gas is allowed to flow between the outer circumferential surface of the tube 21 and the inner circumferential surface of the porous refractory 22. Ribs 2 are provided on the inner peripheral surface of the porous refractory 22 to form a gap 24 for
2a, but instead of forming ribs 22a on the inner circumferential surface of the porous refractory 22, as shown in FIG. It is also possible to form an arrangement.

6 is a longitudinal cross-sectional view showing another embodiment of the present invention, FIG. 7 is a cross-sectional view of the ball taken along the W-leg line in FIG. 6, and FIG. 8 is a cross-sectional view taken along the skin line in FIG. 6. FIG. 9 is a partially enlarged cross-sectional view of part A in FIG. 8, showing the tube 61, the porous refractory 62, and the gap 64 formed between the tube 61 and the porous refractory 62, which constitute the nozzle part 60. Except for this, this embodiment is the same as the embodiment shown in FIGS. 1 to 4, and corresponding parts are designated by the same numbers.

The tube 61 is formed flat so that the other portion of the distribution chamber 37 in the header 3 except for the proximal end located inside the casing portion 31 has a slit-like cross section.

The proximal end side of the tube 61 is located within the distribution chamber 37;
The base end side half has a circular cross section, and a male thread is formed on the outer periphery of the base end, and is threadedly connected to the refining gas supply port 32a in the header 3 via this male thread. When the tube is compressed, it is formed into a fan shape that widens toward the end when viewed from above, and is connected to the slit-shaped portion 61b. On the other hand, the porous refractory 62 has two half-split cylinder bodies 6.
2a and 62b, both half-split cylindrical body 62a
, 62b, the portions facing the slit-shaped portion 61b of the tube 61 have both half-split cylindrical bodies 62a, 62b.
When polymerized to form a cylinder, the slit-shaped portion 61
Recesses 62c and 62d facing both sides of b are formed, and inside each of the recesses 62c and 62d, a double halved cylindrical body 62 is formed.
A plurality of lips 62e and 62f that support both sides of the slit-like portion 61b when stacking a and 62b are placed in the recess 62, respectively.
c and 62d are equally spaced in the width direction. When the two halves of the cylindrical bodies 62a and 62b are stacked to form a cylinder with the slit-shaped portion 61b of the tube 61 sandwiched between them, each rib 62e and 62f touches the outer peripheral surface of the slit-shaped portion 61b and each recess. There is a rib 62e between the circumferential surfaces of 62c and 62d.
, 62f, a gap 64 is formed that forms a protective gas flow path divided in the circumferential direction. When the two halves of the cylindrical bodies 62a and 62b are overlapped to form a cylinder, the diameter thereof is gradually reduced from the base end to the distal end, and the base end is formed by the header 3. The pond portion is restrained and held by the cylindrical portion 33a of the fixture 33 constituting the holder, and the tubular portion 23. Note that the recesses 62c, 6
Instead of providing ribs 62e and 62f on the circumferential surface of tube 61
Of course, lips may be formed on the outer circumferential surface of the slit-like portion 61b at equal intervals in the circumferential direction over the entire length in the axial direction.

In the product of the present invention, the refining gas introduced into the base end of the tube 61 is blown into the composite blowing furnace F through the fan-shaped portion 61c and the slit-shaped portion 61b, and the refining gas is blown into the composite blowing furnace F. This makes it possible to further reduce the phenomenon of blowback to the edge of the tube, which closes inward. Further, a part of the protective gas introduced into the distribution chamber 37 through the elbow 32c is contained in the pipe 61.
The outer peripheral surface of the slit-shaped portion 61b and the porous refractory 62
and the other part is supplied into the porous refractory 62, in such a manner that the refining gas blown from the pipe 61 from the gap 63 is enclosed, while the porous refractory 6
Protective gas is blown into bubbles from 2 and 2, thereby preventing molten metal from solidifying and adhering to the tuyeres and reducing thermal stress on the refractories surrounding the tuyeres. Other effects are the above-mentioned 1-
This is substantially the same as the embodiment shown in FIG. 4, and the explanation will be omitted. Next, test results for the embodiment shown in FIGS. 1 to 4 (referred to as the first embodiment) and the embodiment shown in FIGS. 6 to 9 (referred to as the second embodiment) will be described.

Dimensional specifications of the first embodiment Inner diameter of the pipe 21 Diameter of the tip of the 6-skin porous refractory (porous brick) 22
Base end diameter of 48 side porous refractory (porous brick) 22
6. Porous refractory material (porous brick) 22
The width of the gap 24 between the rudder tube and the porous refractory having a length of 155 is 0.3 ribs. The slit-shaped portion 21 of the dimension specification tube of the second embodiment
b Cross-sectional dimension Thickness: 1.7 Slit-shaped portion 21b of willow pipe Cross-sectional dimension Width: 33.6 Gap between leg pipe and porous refractory 6
Dimension specifications of 4 width 0.2 rib comparison example (double pipe with circular cross section) Inner pipe inner diameter 6 side inner and outer pipe gap
In the 0.5 rib test, four blades each having the above dimensions were attached to the bottom of a 2.5 ton test operating furnace, and the experiment was conducted 10 times (10 charges) as a bottom blowing converter.

The experimental conditions were as follows. Hot metal amount 200
0k9'ch (charge, same below) scrap
200kg/ch quicklime (bottom blown powder) 120k9/ch fluorite (bottom blown powder) 10k9/ch Carbon content at end point
0.05% by weight end point temperature
The results of the 1-road pi○ test show that the length of the tuyere melting is 73 sides/1 ratio h in the first example, 57 ribs/1 ratio h in the second example, and 128 willow/1 ratio in the comparative example.
It was ratio h.

As is clear from these results, the erosion length in the examples of the present invention is significantly reduced compared to the comparative examples, and among the examples of the present invention, especially in the second example in which the inlet has a slit-shaped cross section, It can be seen that the melting loss length can be further reduced than in the first example in which the cross section is circular. As described above, in the product of the present invention, the occurrence of the blowback phenomenon of refining gas etc. blown into the molten metal is suppressed, and at the same time, thermal stress exceeding the allowable value is formed in the refractories surrounding the blade, or It is possible to prevent molten metal from solidifying and adhering to the tuyere in the form of a basket lid, significantly reducing the erosion of the refractories around the tuyere, greatly extending the life of the tuyere, and reducing the amount of refining gas etc. from the tuyere. The present invention has excellent effects, such as stabilizing the jet and preventing damage to the tuyere itself.

[Brief explanation of the drawing]

FIG. 1 is a vague diagram showing the mode of use of the embodiment of the present invention, and FIG.
The figure is an enlarged cross-sectional view showing the product of the present invention in a horizontal position, Figure 3 is an axial cross-sectional view taken along line m-m in Figure 2, and Figure 4 is a
5 is an explanatory diagram showing another example of the tube used in the product of the present invention; FIG. 6 is an enlarged sectional view showing another embodiment of the present invention; FIG. is an axial cross-sectional view taken along the skin-to-skin line in Figure 6, and Figure 8 is a cross-sectional view of the wisteria taken along the Kaze-to-dish line in Figure 6.
FIG. 9 is an enlarged view showing the section ■ in FIG. 8. 1...Tuyere, 2...Nozzle section, 3...Header, 21...
... Pipe, 22 ... Porous refractory, 23 ...
... Mantle, 24 ... Gap, 31 ... Casing part, 32 ... Lid, 33 ... Mounting part,
60...Nozzle part, 61...Pipe, 62...
...Porous refractory, 62a, 62b...Half cylindrical body, 62c, 62d...Recess, 62e, 62f.
...Reply, 64...Gap. Figure 2 Figure 1 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9

Claims (1)

[Claims] 1. A tuyere provided to inject gas for refining and/or stirring into molten metal, including a tube for injecting the gas into the molten metal, and a protective gas provided around the tube to inject the gas into the molten metal. and a porous refractory into which the porous refractory is blown, and a nozzle for blowing fluid provided with a gap through which a protective gas flows between the outer peripheral surface of the tube and the porous refractory. Tuyere for metal smelting.