ECCC-84异形坯连铸机的中间包水口更换设备的发展

Development of Twin Online Tundish Nozzle Changer for beam blank casting 2. Author(s) name(s) and affiliation(s)

Hiroaki Hayashi Flow Control Refractories Division, Krosaki Harima Corporation

1-1,Higashihama-machi, Yahatanishi-ku, Kitakyushu City, Fukuoka, 806-8586, Japan Shinjiro Saitoh Flow Control Refractories Division, Krosaki Harima Corporation, Japan

Kenji Tachibana Flow Control Refractories Division, Krosaki Harima Corporation, Japan

Shunji Sadano Flow Control Refractories Division, Krosaki Harima Corporation, Japan

Haruyuki Ohba Flow Control Refractories Division, Krosaki Harima Corporation, Japan

3. Contact data for questions

Hiroki Akiyama Overseas Sales Department, Krosaki Harima Corporation

1-1,Higashihama-machi, Yahatanishi-ku, Kitakyushu City, Fukuoka, 806-8586, Japan

Tel 81-93-622-7286

Fax 81-93-622-7287

E-mail: hiroki-akiyama@krosaki.co.jp

4. Key Words

flow Control, tundish, online, nozzle changer, beam blank

5. Abstract

The device, in which the tundish nozzle can be changed and extend the casting sequence, is getting popular and has been applied in billet caster in these days.

The same needs, that is, extending sequence is also required in beam blank caster but the limited room had disturbed to apply the device.

We (Krosaki Harima Corporation: KHC) have designed our new device and developed "Twin Online Tundish Nozzle Changer: Twin OTNC" to meet the needs under such limited room.

A new smaller nozzle and a compact mechanism to support the nozzle have been applied in the Twin OTNC which can be installed in 190mm pitch of beam blank caster.

We have supplied our Twin OTNC to a customer and could get very good results.

I would like to introduce how we achieve the compact design in Twin OTNC and the good results provided by the Twin OTNC, and so on.

6. Introduction (a brief overview of any preconditions, procedures and problems)

In Beam Blank caster, it requires to extend casting sequence by exchanging the two Shoot Nozzles during casting. However, the nozzle pitch is very short in some casters. We had to meet the nozzle pitch 190.5 mm in a customer. We tried the compact mechanism and the refractories as minimum as possible in order to put the necessary function into the limited room.7. Text, Tables and Figures

General benefit of Tundish Nozzle Change

The tundish nozzle whose material is ZrO2 performs pretty longer life, but it generally is shorter than the other refractories used in tundish, consequently, the whole refractories’ service life is limited by tundish nozzle. Therefore, the equipment, which enables tundish nozzle replacement, offers several benefits. (Figure 1)

Figure 1: Increasing Tundish Life

Longer sequence length leads to huge operational cost saving on tundish parting coat, energy for tundish preheating and total skull amount in tundish. Also, it’s saving tundish number.

The steelmaking operation sometimes requires the adjustment the melting time. The replacement of different size bore can satisfy this requirement. (Figure 2)

Figure 2: Changing Through-putMoreover, the “Blank plate” can stop the casting, this helps the safety operation. (Figure 3)

Feature of our OTNC is described below Appendix. (Table 1)

Figure 3: Secure Casting Stop

Outline of OTNC

The outline of OTNC is shown as below (Figure 4).

The refractory composes of “Well block”, “Fixed nozzle”, “Shoot nozzle” and “Packing (Joint material)” between Well block and Fixed nozzle (Figure 5). The “Shoot nozzle” is supported with appropriate and constant pressure during casting and replacing.

Figure 4:Mechanical Configuration "Main Parts"

Figure 5:Refractory Configuration

Background to design Twin OTNC with nozzle pitch 190.5 mm

Two streams are required in beam blank caster. When two standard OTNCs are parallel put, the minimum nozzle pitch Is 286 mm because of the mechanical size and refractory size, and this could not satisfy the customer’s nozzle pitch 190.5 mm. (Figure 6)

We have changed the refractory size and mechanical structure in order to satisfy the customer’s specification. The details are (Figure 7);

Compact refractory design from sq.120 to sq. 100 mm

Sharing and compact mechanism design, that is, suitable coil springs location.

Figure 6: Nozzle pitch for Beam blank caster, and parallel layout of two OTNCs

Figure 7: Layout a Twin OTNC

Twin OTNC specification

Weight: 150 kg (Including Base plate)

Size: 770 X 565 X 210 mm (Including Base plate and cover)

Bore size: Maximum diameter 25 mm

Number of nozzle: 2 for Beam blank caster

1 for Billet caster

Face pressure: 9.4 kN as designed

Cylinder stroke: 105 mm

Cylinder speed: 150 mm/s (recommendation)

Hydraulic pressure: 210 bar

10. Appendix (optional)

Function of OTNC Advantage of operation Reason of advantage

1) Outer setting

Upper Nozzle

a) Reusing of tundish in

hot condition

Reduction in cost of refractory due to reusing the tundish in hot condition (casting of different steel grade, night shift operation, etc.).

a) Accommodation to

electric furnace Operation in matching the electric furnace due to adjusting of casting speed.

b) Improvement of

operation ratio Non stop operation due to adjusting of the casting speed.

c) Improvement of

yield rate

Decrease the strand stop and restarting due to adjusting of the casting speed.

Liberate from restriction of the casting sequence

d) Improvement of casting

sequence

Reduction in cost of refractory for tundish. Movement of mold level is small due to the stability of stream.

2) Exchange of

Lower Nozzle

e) Improvement of quality

Not need to change the molten steel level in tundish.

a) Safety and reliable

stop of casting

Easy and safe operation of casting stop and operator will become free from disposing for removing metal on the launder.

b) Easy control of strand

Easy to the casting stop and start on the way of casting.

3) Exchange to

Blank Plate

c) Emergency casting stop

Minimize the damage in case of breakout and overflow.

Table 1: Feature of OTNC

Figure 9: Actual casting with Twin OTNC

Figure 10: View from tundish bottom