JPS58145336A - Preheating method of tundish for horizontal and continuous casting - Google Patents

Abstract

PURPOSE:To preheat a tundish in such a way that the temps. in the inside wall of a crucible are made uniform in a short time by ejecting burner flames from the upper part toward the bottom part while maintaining the inside of the crucible of the tundish under negative pressure. CONSTITUTION:In a tundish for horizontal and continuous casting consisting of a crucible and a mold 8 joined in the lower part on the side face of the crucible, a tubular air ejector 1 having the length arriving at the bottom part of the crucible is inserted into the crucible so that the suction port 11 thereof opens near the bottom surface of the crucible and toward a nozzle 9. The high pressure air from a blower or compressor is ejected through the air nozzle 2 disposed in the ejector 1 to generate negative pressure beforehand in the crucible. The mold 8 is kept closed with a dummy bar 7 in this stage. In this state, long flames are ejected from a preheating burner 3 disposed in the upper part of the crucible toward the bottom part from the opening part in the upper part and are brought into contact uniformly with the respective parts on the inside wall of the crucible, whereby the inside wall is preheated.

Description

[Detailed description of the invention] Book! a@ is a method for preheating a tundish for horizontal continuous casting KWI4.

In horizontal continuous casting, which consists of a crucible and a mold that has been assembled, and in which slabs are cast in a chain by pulling the slabs horizontally from the mold,
-In IR, as Tanditshu, the crucible is -1&r-
In addition to those arranged, recently by the applicant 111
A Takaoka liquid induction furnace or a low j
The litIL induction furnace is overpriced. However, in the case of any of the tundishes, in order to increase the efficiency of induction heating for holding boiling water and further shorten the length of the nozzle part, it is possible to reduce the inner diameter of the crucible and reduce the heat. It's a comb.

Both tanditshu are attached wmvs lI/ and J
As shown in the figure, the ratio H/D between the depth of the crucible and the inner depth of 11 kQ) is very high.

Therefore, when preheating the tundish before starting operation, it is necessary to install a long flame burner and project the burner flame toward the bottom of the crucible. It is not possible to reach the bottom of the crucible with a trench and heat it to the desired preheating temperature. Moreover, due to the structure, it is not possible to provide a discharge port at the bottom of the crucible, and on top of that, the nozzle and mold are connected.
In order to eliminate damage to the mold caused by the burner frame, the mold entrance on the inner wall of the crucible must be closed and preheated.

For this reason, even if a long flame burner is installed at the top of the crucible and the crucible is preheated by this flame, combustion gas will accumulate at the bottom of the crucible, and its removal is difficult because the mold inlet is closed. Because of this, the burner flame cannot reach the parts of the crucible due to the pressure of the combustion gas, so it heats only the upper part of the crucible and cannot raise the temperature of the lower part.

As a result, the temperature difference between the top and bottom of the crucible becomes large. For example, the temperature at the top of the crucible is
Temperatures can reach 200°C or higher, which can cause severe wear and tear on the steel plates and heat-resistant bricks on the furnace ceiling, while on the other hand, it is difficult to raise the temperature at the lower side walls and bottom of the crucible, as well as at the nozzle.
Even if heated for a long time, the temperature will not rise above i,ooo°C. Therefore, at the start of continuous casting operation, the temperature of the molten steel injected into the crucible decreases, causing problems such as inability to cast.

In order to avoid this difficulty, preheating is performed by inverting the tundish with the crucible water inlet facing downward and the crucible urine facing upward, but the preheating efficiency is not good because the specific H/D is large. The bottom of the crucible is heated exclusively to the desired temperature.

The present invention aims to solve the above-mentioned problem 1 in the conventional preheating method of a tundish for horizontal continuous casting, thereby obtaining a uniformly efficient preheating machine. Ink.

In the present invention, in order to achieve this first objective, compressed air or an air ejector using an overcrowded air ejector is injected into the crucible toward the nozzle part, and the ejector is used to fill the crucible with air. A long frame is projected from a burner installed in the opening at the top of the crucible to the first part of the crucible under negative pressure.
This allows the burner frame to be placed above the crucible, @wall,
The mold that unfortunately heated up the nozzle part, its combustion gas became exhausted through the air intake inlet, and thus K.

The temperature of m*is in the crucible is 1, for example, /, eell'c
The above temperature is uniformly heated, the temperature value decreases, and it becomes possible to heat to a predetermined temperature within a predetermined time.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to FIGS.

Figures 1 and 2 show the procedure for carrying out the method of the present invention in the mounting section, slope, and tundish, respectively.
Each indicates the next member, etc.

l Air ejector De Dummy Perco Air nozzle t Mold J Preheating burner t Nozzle l Furnace wall 10 Coil S Furnace ceiling // @ Inlet 6 Blower available /J Discharge port or compressor H Crucible III D Inner diameter of crucible As can be seen from the figure, when preheating the tundish, a tubular air ejector with a length reaching the bottom of the crucible is placed in the crucible in advance, and the worker 1 is placed near the bottom of the crucible. From the blower or compressor 6, the air nozzle opens toward the outside of the tundish into the inside of the air ejector. E-air is discharged to generate a negative [Jt-] around the intake port of the air ejector. This situation 1
In step 1, when a long flame is projected from the preheating burner J installed at the opening at the top of the crucible, the burner flame cools the crucible by the negative pressure generated around 1 inlet/l of the air ejector l. Inside 11116c & was guided to the bottom of the volume and also heated the nozzle t part *.

Inlet port//Air ejector/p'if:@Ikome★re,
It is discharged from the crucible through the discharge port. 91 The inner arm of the crucible is uniformly heated by the flame from the preheating burner J, and is heated to a uniform preheating temperature.

Next, we will explain the diarrhea experiment conducted in order to compare the preheating using the method of the present invention with that using the method.

Comparative Example: To preheat a large red vertical or inclined crucible-type high-frequency induction heating tundish with a H/D ratio (crucible capacity≠oo noodles, crucible depth/, JOOwm, inside @soO■),
Preheating burner J (fuel propane gas, gas consumption 10N"/HR, gas pressure car! 0-Jo) with blower (air volume 4
111” / Win, wind pressure j j Ovml (*
Preheating was carried out using a supply of combustion air from O). As a result, the temperature of the upper part of the crucible rises to over 100°C, but on the contrary, it is difficult to raise the temperature of the lower part of the side wall and bottom of the crucible, as well as the nozzle part.
It did not rise above C.

On the other hand, in order to preheat this tundish, by using the above-mentioned preheating burner J and blower 6, the compressed air ejector/(BUS Jlolg, the yen price of the inlet l/ and the outlet 11 is 70 cm, Preheating was carried out using an air pressure of 4 (-). As a result, the temperature of the crucible bed and nozzle T remained at 1400 °C after hours a to 3, and the upper temperature at that time was /, /lic. .At this temperature/~
Holding time for J hours - Although the steel was injected, it was necessary to perform a stable continuous casting operation.

As mentioned above, our method is to preheat the tundish for horizontal continuous casting so that the temperature of the inner wall of the crucible is uniform. High school students! e to withdraw from a sexual relationship
I get to meet you.

In addition, according to the present invention, since preheating can be performed within a short period of time, an electrodynamic effect can be obtained in which it is possible to reduce the fuel consumption rate of the burner.

[Brief explanation of the drawing]

11/ and Jll, this lI@method can be judged as appropriate-&[
FIG. 3 is a cross-sectional view showing a wedge and inclined tundish together with an air ejector for carrying out the method. l...Air ejector Hti...Intake port; lJ...Exhaust port.

Claims (1)

[Scope of Claims] A tundish for horizontal continuous casting, which consists of a crucible and a slab with the crucible side lower than mKm, and continuously casts slabs by pulling out one piece from the crucible. In pre-1 fiber, the crucible is preheated by a burner, in this case, the burner is heated to the crucible S, and the burner frame is heated to By exclusively projecting τ, the burner flame uniformly melts the inside of the crucible to a pH of 41, thus preheating the inner wall of the crucible.
A method for preheating a tundish for horizontal continuous casting. 1 In the crucible holder, place a tubular air ejector with a mouth opening into the crucible to a depth of 1N4mm, and discharge high-pressure air from a blower, compressor, etc. from the air nozzle inside the air ejector. Scope of claim for a tatami permit that allows negative pressure to be generated in the crucible circle by
1/l [Preheat as stated. 1. The method described in Paragraph J of the Fireworks License Application, in which the inlet of the air ejector is made to fit into the nozzle part of the crucible.