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)

SAIL-BHILAI STEEL PLANT 1

ENHANCING

THE PREHEATING TEMPERATURE

OF TAPPING LADLES

AT STEEL MELTING SHOP-1 OF

BHILAI STEEL PLANTKAMALENDU DAS, GM (SMS-1), K RAMA KRISHNA, DGM (SMS-1)

D LALITHANANDA KUMAR, AGM (SMS-1)BHILAI STEEL PLANT


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)


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 1959.

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 1967.

The Open Hearth Furnaces were converted into Twin Hearth Furnaces from 1986-1998

At present the shop is having 4 TWIN HEARTH FURNACES (3 Running and 1 in repair)


FAD

FLOW-SHEET OF SMS-I

IRO

N O

RE

&LI

ME

STO

NE

SC

RA

P

MAGNETIC YARD BULK CHARGE YARD

HO

T M

ETA

L FR

OM

BLA

ST

FUR

NA

CES

HOTMETAL

HOTMETAL

OXY

GE

N F

RO

MO

P-1&

OP

2

MIXER-1 MIXER-2FURNACE SECTION

T H F -2

PIT SIDE

T H F -3 T H F -4 T H F -1

TEEMINGLADLE

MOULDS

CRUDESTEEL

TEEMING

MOULDS

HEATS FORSTRIPPING

ING

OTS

INGOT STORAGE YARD

MOULDS

MOULD YARD 2

INGOTS

STRIPPER YARD

HOT MOULDS

MOULDTRAINS

HOT MldsTO

MOULD YARDS

COLDINGOTS

THIMBLE

FLUSHINGSLAG

SLAG FORDISPOSAL

HO

T M

ETA

L FR

OM

BLA

ST

FUR

NA

CES

MOULDS

MOULD YARD 1

HOT INGOTSTO BBM

THIMBLE

COLD INGOTSTO BBM

FER

RO

M

AN

GA

NES

E

FAD

FLOW-SHEET OF SMS-I

IRO

N O

RE

&LI

ME

STO

NE

SC

RA

P

MAGNETIC YARD BULK CHARGE YARD

HO

T M

ETA

L FR

OM

BLA

ST

FUR

NA

CES

HOTMETAL

HOTMETAL

OXY

GE

N F

RO

MO

P-1&

OP

2

MIXER-1 MIXER-2FURNACE SECTION

T H F -2

PIT SIDE

T H F -3 T H F -4 T H F -1

TEEMINGLADLE

MOULDS

CRUDESTEEL

TEEMING

MOULDS

HEATS FORSTRIPPINGHEATS FORSTRIPPING

ING

OTS

ING

OT S

INGOT STORAGE YARD

MOULDS

MOULD YARD 2

INGOTS

STRIPPER YARD

HOT MOULDS

MOULDTRAINSMOULDTRAINS

HOT MldsTO

MOULD YARDS

COLDINGOTS

THIMBLE

FLUSHINGSLAG

SLAG FORDISPOSAL

HO

T M

ETA

L FR

OM

BLA

ST

FUR

NA

CES

MOULDS

MOULD YARD 1

HOT INGOTSTO BBM

HOT INGOTSTO BBM

THIMBLE

COLD INGOTSTO BBM

COLD INGOTSTO BBM

FER

RO

M

AN

GA

NES

E


Tapping Ladle

SAIL-BHILAI STEEL PLANT

Ladle Cycle

6

Tapping

Teeming (Casting)

Nozzle Cleaning

Ladle Inspection

OK

Not OKMech.Repair /

Patching

Ladle heating

Ladle Preparation for

Next tapping


Ladle Life

Apr-13 May-13 Jun-13 Jul-13 Aug-13 Sep-13 Oct-13 Nov-13 Dec-13 Jan-14 Feb-14 Mar-14 Apr-14 May-14 Jun-1430

32

34

36

38

40

42

44

46

48

50

43.97


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 250-300oC.

• Modified designs were obtained but they could raise the temperature of the lining to around400-450oC only


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


LADLE HEATING SYSTEM


1210

308

128

1065

55

190

350

260

10

15

Ladle Heating Burner


GasCompressed Air

2.5 atm

Mixer

Atmospheric Air

Atmospheric Air

Working of Existing Ladle Heating Burner






Premixed flame of a simple gas burner

Lf = Li + + Ls

For a laminar premixed flame, = 0 and

Lf = Li + Ls


Simple laminar diffusion flame

(a) Over-ventilate (b) Under-ventilated


Progressive change in flame type with increase in jet velocity


Laminar Flame

L = where,

L = flame lengthv = jet velocityV = volume flow-rate of jet.

For a given fuel and burner, r and D are constant.

The length of a laminar diffusion flame is directly proportional to its jet velocity.


Turbulent Flame

The length of turbulent diffusion flameL where, d= burner tube diameter = eddy diffusivity But, = 1' v‘ where l' = scale of turbulence v' = intensity of turbulence Experimental data show thatl' d and v' vTherefore, dvHence, L or L dor = constantSo in case of turbulent diffusion flame the length of flame is directly proportional to the nozzle diameter but independent of the gas velocity.


Operation characteristics of an aerated gas burner

Stable burner operation is possible in the middle region confined by the curves 1, 2, 3 and 4.


10

45

Compressed Air 4 atm

Modification

P1

V1

v1

P2

V2

v2

vg

vr


Modified burner (without funnel)


Increased flame length with modified burner


RESULTS & DISCUSSION


Flame temperature

Flame temperature with old burner Flame temperature with new burner


Temperatures with the old burner

Max. Temp. In deg. 115.00 c Max. Temp. In deg. 115.50 c

Max. Temp. In Deg. 120.00 C


Temperatures with the New burner

Max. Temp. In Deg. 349.00



SAIL-BHILAI STEEL PLANT

TEEMING LADLE TEEMING LADLETEEMING LADLE

EXISTING TRIAL

Compressed air 4 atm

MODIFIED

30

Compressed air 2.5 atm


Ladle heating performance


Ladle Refr. temp.

4 6 8 10 12 14 16 18 20 22 240

100

200

300

400

500

600

700

800Before After

Time (Hours)

Tem

pera

ture

oC


Rejection due to Double pouring ingots (%)

Apr-13

May-13

Jun-13Jul-1

3

Aug-13

Sep-13

Oct-13

Nov-13

Dec-13

Jan-14

Feb-14

Mar-1

4

Apr-14

May-14

Jun-14Jul-1

4

Aug-14

Sep-14

Oct-14

Nov-14

Dec-14

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

0.52

0.28


Specific Aluminium Consump.

JUN JUL AUG SEP OCT NOV DEC JAN0.000

0.050

0.100

0.150

0.200

0.250

0.300

0.350

0.400

0.450

0.500NORM ACTUAL

(2014-15)

( KG

/TCS

)


Ladle Life

Apr-13

May-1

3Jun-13

Jul-13

Aug-13

Sep-13

Oct-13

Nov-13

Dec-13

Jan-14

Feb-14

Mar-1

4

Apr-14

May-1

4Jun-14

Jul-14

Aug-14

Sep-14

Oct-14

Nov-14

Dec-14

30

32

34

36

38

40

42

44

46

48

50

43.97

45.71


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.


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 7000C.

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.


Safety

At various turn down ratios of gas and air

burner found to be functioning satisfactorily and

burner body was not getting heated up.


THANK YOU

Documents

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)