JPH0199758A - Method for preventing clogging of nozzle by preheating blowing gas - Google Patents

Abstract

PURPOSE:To prevent lowering of the productivity caused by clogging of a tundish nozzle or a long nozzle by preheating gas blowing to molten steel dis charging device in continuous casting for the steel. CONSTITUTION:The blowing gas at first is introduced to piping 7 at lower part of a tundish cover 8 from the original piping 12. Then, the preheated blow ing gas is blown into refractory at once through a header 13. By this method, metal sticking and Al2O3 deposit developed in the long nozzle 6 or this tundish nozzle 1 can be restrained.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention was made to more thoroughly prevent clogging of tundish nozzles, long nozzles, etc. due to Af z O3, etc. in continuous steel casting. It is.

<Prior Art> In continuous casting of steel, as shown in FIG. 1, a stopper 2. Upper nozzle 3° Upper plate 4
Alternatively, gas is often injected from a refractory material such as tanditsch nozzle 1. For example, 634~ of Steel Handbook ■
On page 635, a technique for blowing ^r gas to prevent nozzle clogging is disclosed.

In the conventional method, gas at room temperature was injected into molten steel at a high temperature of 1,500°C or higher, so the molten steel was locally cooled in the tundish nozzle, causing the molten steel to solidify and adhere to base metal, and to reduce the temperature of the molten steel. Precipitation of V t Os occurs,
The tanditshu nozzle was often blocked.

In addition, for the purpose of nitriding molten steel, long nozzle 6 to N8
Gas may be blown into the nozzle, but like the tanditshu nozzle, there was often metal contamination inside the long nozzle.

<Problems to be Solved by the Invention> The present invention solves the problem of the Tandy 7 Schnozzle by the conventional method.
This was done to prevent nozzle clogging since long nozzles often had nozzle clogging.

Means for Solving Problems〉 As a result of extensive research into the phenomenon of metal deposition and Af x Os precipitation within the tundish nozzle and long nozzle, the inventor has developed a method for preheating the blown gas. We have found that this phenomenon can be prevented by A method for preventing nozzle blockage by preheating the blown gas, which is characterized by preheating the molten steel; ■A patent characterized by preheating the gas to be blown into the molten steel using a blown gas preheating piping provided on the tundish lid. A method for preventing nozzle clogging by preheating a blown gas according to claim 1.

Effects> The present invention is characterized by preheating the gas injected into molten steel in continuous casting to suppress the precipitation of bare metal and Af z Os generated in the long nozzle or tundish nozzle. However, as a method of preheating the blown gas at low cost, there is a method to preheat the blown gas by effectively utilizing the heat of the molten steel in the tundish. A preheating method is effective and will be described as an embodiment.

As shown in FIG. 2, a tundish lid 8 having a gas preheating pipe 7 on the lower surface is used. As shown in FIG. 1, the blown gas is first introduced from the source pipe 12 into the pipe at the bottom of the tundish lid. At this time, the blown gas is preheated by the sensible heat of the tundish lid itself and the heat of the molten steel inside the tundish.

The preheated blowing gas is passed through the header 13,
From here it is blown into each refractory. If necessary, it is also possible to install a flow meter, pressure gauge, etc. between each refractory and the tube to control the flow rate and pressure of the blown gas.

FIG. 3 shows the relationship between the calculated value and the actual value of the amount of molten steel passing through the tundish nozzle (t/5 inch). Note that the calculated value was determined from the inner diameter of the sliding nozzle plate and its opening degree, the height of the molten steel head in the tundish, and the amount of Ar gas blown. In the conventional method (without preheating of the blown gas) indicated by O, the actual value is lower than the calculated value of the passing tonnage, which indicates a tendency for the tundish nozzle to become clogged. On the other hand, in the method of the present invention (with preheating of the blown gas) indicated by the mark, the calculated value and the actual value almost match, that is, [0,9≦(actual value)/(
calculated value)≦1.1], and no clogging of the tundish nozzle was observed.

The preheating temperature of the blown gas is preferably 100 to 1000°C. Below 100°C, the molten steel will solidify, adhere to bare metal, and/or
This is because the effect of preventing the precipitation of zOs is not sufficient and the above-mentioned effect becomes saturated at temperatures above 1000°C, resulting in a decrease in preheating efficiency.

<Example> The inner container is a continuous casting tundish with a capacity of 65 tons.
When casting 6 charges of 230 tons of molten steel,
The blown Ar gas was preheated using a tundish lid equipped with a pipe for preheating the blown gas as shown in FIG. Ar gas is blown from the upper nozzle and upper plate, and the flow rate is 7. ONl/wn, and 4.4
It was N17m. In addition, the gas preheating temperature at this time is 80
It was 0°C.

6 The average tonnage of molten steel passing through the tundish nozzle during single-channel casting is (actual value)/(calculated value) 0.9
7, and the nozzle inner hole after casting is filled with bare metal or N80. Almost no precipitation was observed.

Although the above embodiment shows an example in which Ar gas is blown into the upper nozzle and the upper plate, the same effect can be obtained by blowing preheated Ar gas into the tundish nozzle, the stopper, and even the ladle nozzle.

Also, when blowing NZ gas into the nozzle for the purpose of nitriding molten steel, by preheating the molten steel in the same way, the temperature of the molten steel will not drop, and the nozzle inner hole will have bare metal, or JV
Needless to say, the precipitation of xOs is eliminated.

Furthermore, as a preheating method, an example in which the radiant heat of the tundish lid is used is shown here, but other preheating means may be used.

<Effects of the Invention> According to the present invention, it is possible to prevent a decrease in productivity due to blockage of the tundish nozzle/long nozzle.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a gas blowing method according to the present invention,
Fig. 2 is a perspective view of the tundish lid equipped with piping for preheating the blown gas, and Fig. 3 is a graph showing the relationship between the calculated value and the actual value of the amount of molten steel passing through the tundish nozzle (t/m). It is. 1... Tanditshu nozzle, 2... Stopper, 3... Upper nozzle, 4
...Top plate, 5...Bottom plate, 6
...Long nozzle, 7...Piping for blowing gas preheating, 8...Tundish lid, 9...Long nozzle hole, lO...Stopper hole, 11...Control valve, 1
2... Former plumbing, 13... Hengu. For patent applicant #Steel Co., Ltd.

Claims (1)

[Claims] 1. A method for preventing nozzle blockage by preheating blown gas in continuous steel casting, which comprises preheating the gas blown into the molten steel outflow path from a tundish or ladle. 2. The method for preventing nozzle clogging by preheating the blown gas according to claim 1, wherein the gas to be blown into the molten steel is preheated using a blown gas preheating pipe provided on the tundish lid.