ENHANCING THE PREHEATING TEMPERATURE OF TAPPING LADLES AT STEEL MELTING SHOP-1 OF BHILAI STEEL PLANT KAMALENDU DAS, GM (SMS-1), K RAMA KRISHNA, DGM (SMS-1) D LALITHANANDA KUMAR, AGM (SMS-1) BHILAI STEEL PLANT SAIL-BHILAI STEEL PLANT 1

Bhilai Steel Plant Eleven - times winner of Prime Minister's Trophy for best Integrated Steel Plant in the country. Among the long list of national awards it has won, Bhilai has bagged the CII-ITC Sustainability award for three consecutive years. Certification of IMS (ISO:9001,ISO:14001,ISO:18001 and SA:8000) SAIL-BHILAI STEEL PLANT 2

Steel Melting Shop-1  Initially SMS-1 was planned to produce 1 MT steel annually from 6 Open-hearth furnaces of 250 T capacity each.  First tapping was done on 12th October  The capacity of the shop was increased from 1.0 MT to 2.5 MT by installing 4 more open hearth furnaces of 500 T capacity and converting OH no. 6 from 250 T to 500 T capacity which was completed on 14th April  The Open Hearth Furnaces were converted into Twin Hearth Furnaces from  At present the shop is having 4 TWIN HEARTH FURNACES (3 Running and 1 in repair) SAIL-BHILAI STEEL PLANT 3

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Tapping Ladle SAIL-BHILAI STEEL PLANT 5

Ladle Cycle SAIL-BHILAI STEEL PLANT 6 Tapping Teeming (Casting) Nozzle Cleaning Ladle Inspection OK Not OK Mech.Repair / Patching Ladle heating Ladle Preparation for Next tapping

Ladle Life SAIL-BHILAI STEEL PLANT 7

Ladle pre-heating system The ladles are to be preheated after relining before placement for tapping. the re-circulation of ladles occur where preheating could be done only once either after new relining or repair in mid- campaign. Initially the heaters provided for the purpose were raising the temperature of ladles to o C. Modified designs were obtained but they could raise the temperature of the lining to around o C only SAIL-BHILAI STEEL PLANT 8

Ingot Rejection  Double Pouring  Insufficient metal Temperature  Nozzle chocking  Less temperature of teeming ladle, especially in the 1 heat of ladle life or after repair SAIL-BHILAI STEEL PLANT 9

LADLE HEATING SYSTEM SAIL-BHILAI STEEL PLANT 10

Ladle Heating Burner 11 SAIL-BHILAI STEEL PLANT

Gas Compressed Air 2.5 atm Mixer Atmospheric Air 12 Working of Existing Ladle Heating Burner SAIL-BHILAI STEEL PLANT

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Premixed flame of a simple gas burner SAIL-BHILAI STEEL PLANT 17 L f = L i +  + L s For a laminar premixed flame,  = 0 and L f = L i + L s

Simple laminar diffusion flame SAIL-BHILAI STEEL PLANT 18 (a) Over-ventilate (b) Under-ventilated

Progressive change in flame type with increase in jet velocity SAIL-BHILAI STEEL PLANT 19

Laminar Flame SAIL-BHILAI STEEL PLANT 20

Turbulent Flame SAIL-BHILAI STEEL PLANT 21

Operation characteristics of an aerated gas burner SAIL-BHILAI STEEL PLANT 22 Stable burner operation is possible in the middle region confined by the curves 1, 2, 3 and 4.

10 45 Compressed Air 4 atm 23 Modification P1V1v1P1V1v1 P2V2v2P2V2v2 vgvg vrvr SAIL-BHILAI STEEL PLANT

Modified burner (without funnel) SAIL-BHILAI STEEL PLANT 24

Increased flame length with modified burner SAIL-BHILAI STEEL PLANT 25

RESULTS & DISCUSSION SAIL-BHILAI STEEL PLANT 26

Flame temperature Flame temperature with old burner Flame temperature with new burner SAIL-BHILAI STEEL PLANT 27

Temperatures with the old burner Max. Temp. In deg cMax. Temp. In deg c SAIL-BHILAI STEEL PLANT 28 Max. Temp. In Deg C

Temperatures with the New burner Max. Temp. In Deg Max. Temp. In Deg C SAIL-BHILAI STEEL PLANT 29 Max. Temp. In Deg C

TEEMING LADLE EXISTINGTRIAL Compressed air 4 atm MODIFIED 30 Compressed air 2.5 atm SAIL-BHILAI STEEL PLANT

Ladle heating performance SAIL-BHILAI STEEL PLANT 31

Ladle Refr. temp. SAIL-BHILAI STEEL PLANT 32

Rejection due to Double pouring ingots (%) SAIL-BHILAI STEEL PLANT 33

Specific Aluminium Consump. SAIL-BHILAI STEEL PLANT 34

Ladle Life SAIL-BHILAI STEEL PLANT 35

Cost Benefits With the application of modified burners we expect to save approximately Rs. 2.7 Crore per annum. In addition to this Gas Energy of 6 hours is saved per every new ladle heated up. SAIL-BHILAI STEEL PLANT 36

Advantages The challenging task was taken up and executed with the available infrastructure facilities and in-house modifications. The temperatures could be raised to around C. This helped in avoiding high tapping temperatures in the first heats, the high erosion of refractories and also taking care of ladles with bottom jam formation. This has helped in increasing the ladle life and also facilitated in reclaiming the problematic ladles. Gas of 6 hrs heating is saved per every new ladle heated. SAIL-BHILAI STEEL PLANT 37

Safety At various turn down ratios of gas and air burner found to be functioning satisfactorily and burner body was not getting heated up. SAIL-BHILAI STEEL PLANT 38

THANK YOU SAIL-BHILAI STEEL PLANT 39