JPS6229459Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a bottom blowing tuyere for a top-bottom blowing converter.

As is well known, in order to strengthen the stirring of the steel bath and reduce the amount of dust in the generated gas, oxygen is blown from the top blowing lance and stirring gas is blown from the bottom blowing tuyeres below the surface of the steel bath for refining. Top-bottom blowing converter operation has been actively adopted in recent years. As the stirring gas, carbon dioxide, an inert gas, a mixture thereof, or a mixture thereof with a small amount of oxygen gas is generally used, and the blowing amount is set so as to efficiently achieve the above purpose. It is appropriately set and controlled depending on the steel type and other refining conditions.

Incidentally, the bottom blowing tuyeres (hereinafter simply referred to as tuyeres) for blowing the agitated gas into the furnace are installed by making holes in the iron shell and lining brick wall of the bottom of the converter. The brick wall near the installation part is subjected to severe erosion and wear due to direct contact with the strong stirring flow of molten steel generated by gas injection. Therefore, it is extremely important to improve the durability of the tuyere and the brick wall in its vicinity against the above-mentioned erosion effect in order to operate the top-bottom blowing converter in a stable manner. is proposed. Figure 1 shows the tuyere that the present applicant previously invented and applied for. It has been confirmed that the stirring efficiency can be increased and its durability can also be improved. That is, the first
In the figure, 1 is the tuyere, and the tuyere 1 is MgO−
Composed of C-based or dolomite-based refractories,
A header 11 is built into the base, and stirring gas is blown into the furnace through a thin tube 12 communicating with the header 11. The tuyere 1 is attached to a sleeve brick 2 buried in a brick wall 3 at the hearth bottom,
It is fixed by a tuyere holding brick 4 and a base brick 5. Note that 6 is a gas supply pipe for supplying stirring gas to the header 11.

By the way, as the operating time of the tuyere 1 becomes longer, the melting loss progresses as shown by the broken line x. When the amount of erosion reaches a predetermined amount, the tuyere 1 is replaced. FIG. 2 shows the state after the tuyere has been replaced, and since the upper part of the sleeve brick 2 is still melted and damaged compared to the new tuyere 1, the tip of the tuyere 1 is in a protruding state. Therefore, when used in this state, the rate of erosion of the protruding portion of the tuyere 1 becomes extremely high. In order to prevent this, the applicant has developed a sleeve brick 2 as shown in FIG.
Attempts have been made to apply slag coating to the eroded portion 20 or to spray a dolomite-based spray agent to repair it, but a pine room 7 is formed above the tuyere 1.
Since the stirring gas is ejected into the repaired area as shown by the arrow y, it was confirmed that even the repair described above did not have a sufficient effect and was easily eroded. Figure 4 shows an example of the investigation results of the erosion rate of the tuyeres when the tuyere was replaced while applying the slag coating. It has been found that the erosion rate is extremely fast until the erosion loss level h of the brick 2 (see Fig. 3) is reached, and when the erosion loss of the tuyere 1 reaches the erosion loss level h, the erosion rate becomes slow and stable. It was done.

The present invention was devised based on the above knowledge, and its feature is that the central nozzle blowing tuyere is surrounded by a protective refractory tube having a thickness of 30 to 60% of the diameter of the tuyere. The tuyeres are constructed so that they can be replaced as one unit.

Hereinafter, the present invention will be explained in detail based on examples. Fifth
The figure is a cross-sectional structural diagram showing an embodiment based on the present invention. In this embodiment, the central nozzle blowing tuyere (hereinafter referred to as the central nozzle) 101 is connected to the first
The tuyere 100 is constructed by using the same structure as the tuyere 1 shown in the figure, and surrounding the central nozzle 101 with a protective refractory tube 102. The protective refractory tube 102 is made of, for example, the same material as the central nozzle 101 or MgO-C so that its inner side is in close contact with the central nozzle 101 and its outer side is evenly bonded to the inner surface of the sleeve brick 2.
It is constructed by firing system refractories. Tuyere 10
0 is attached to the sleeve brick 2 and fixed by the tuyere holding brick 4 and the base brick 5. Therefore, in order to replace the tuyere 100, the tuyere presser brick 4 and the base brick 5 are removed, and the central nozzle 101 and protective refractory tube 102 are replaced as one unit.

As described above, in the tuyere 100 of the present invention, the central nozzle 101 and the protective refractory tube 102 are always replaced with a new one when they are replaced, so that the tuyere 100 has sufficient durability even against the severe erosion action of molten steel. For example, the protective fireproof pipe 102
For those constructed with MgO-C refractories, tuyere 1
The erosion rate of 00 is extremely slow at 0.4 to 0.5 mm/ch.
It was confirmed that it was stable. Note that if the thickness of the protective refractory tube 102 becomes too thick, the tuyere 1
The weight of the 00 increases, deteriorating the workability of replacement and increasing the cost.On the other hand, if it becomes too thin, the durability against the erosion effect decreases and it becomes difficult to manufacture. In the experience of the inventors of the present invention, it has been effective to set the thickness of the protective refractory tube 102 to 30 to 60% of the diameter of the central nozzle 101 without causing the above-mentioned problems.

As described above, although the present invention has a simple configuration, it has great practical effects.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional structural diagram showing an example of a tuyere;
Figures 2 and 3 are cross-sectional structural diagrams showing the state after the tuyere has been replaced, Figure 4 is a chart showing the erosion rate of the tuyere in Figure 1, and Figure 5 is a tuyere based on the present invention. FIG. 2 is a cross-sectional structural diagram showing one embodiment of the present invention. 1... Tuyere, 11... Header, 12... Thin tube, 2... Sleeve brick, 20... Sleeve brick melted part, 3... Hearth brick, 4... Tuyere presser brick,
5... Base brick, 6... Gas supply pipe, 7... Pine room, 100... Tuyere of the present invention, 101
... Central nozzle blowing tuyere, 102 ... Protective refractory tube.

Claims (1)

[Scope of utility model registration request] A bottom blowing tuyere of a top-bottom blowing converter, wherein the central nozzle blowing tuyere is surrounded by a protective refractory tube having a thickness of 30 to 60% of the tuyere diameter, and the tuyere and the refractory tube are integrated. The converter bottom blowing tuyere is configured to be replaceable as a converter.