Presentation on Accretion removal in BF2 at JSW Salem.ppt

1
D. Ravichandar
Jayant Sathaye
N. Sai Rama Krishna
BF 2 Accretion removal
by
CO2 activation

2
CONTENTS
•BF # 2 at JSW Salem Works
•Introduction
•Operating parameters
•First visual inspection
•Accretion Analysis
•Possible reasons for Accretion formation
•Alkali & ZnO balance
•Actions initiated & Review
•Selection of Cardox method
•Working of Cardox system
•Execution methodology
•Post removal - Furnace Performance

3
BF # 2 AT JSW SALEM WORKS
 The Blast Furnace-2 of JSW
Salem works was
commissioned in July 2007
 It is a 550m3 furnace and the
design & technology supplied
by CERI, China.
 Raw material source
 Iron ore – Karnataka
(Bellary)
 Coke – Captive &
Purchased
BF 2 Main features
Working Volume 495 M3
Useful volume 550 M3
No. of tuyeres 16
Hearth dia 5900 mm
Tuyere dia 110 mm
HBP 2.10 Kg/cm2
TP 0.85 Kg/cm2
HBT 1075° C
Sinter 60%
Stoves Top combustion
GCP Dry type
Charging system BLT

4
INTRODUCTION
NORMAL PERFORMANCE
 Productivity - 2.6 to 2.8 MT/M3/Day.
 Average Coal injection rate 95 -100 Kg/THM in July & Aug-09.
DETERIORATED PERFORMANCE FROM SEP-09
 Blast acceptance was in decreasing trend.
 Furnace movement disturbed.
 Top temperatures were in increasing trend.
 Refractory lining temperatures were in dropping trend.
 Furnace got drifted towards unstable regime of operation.
 Primary reason - inferior quality sinter & coke.

5
OPERATING PARAMETERS
Production (MT)
45060
43178
36110
39770
34194
38577
34007
30000
34000
38000
42000
46000
Jul-09 Aug-09 Sep-09 Oct-09 Nov-09 Dec-09 Jan-10
Blast Volume (Nm3/Hr)
71200 70450
66007
67249
62121
67170 67020
58000
62000
66000
70000
74000

6
Fuel Rate
592 597
650 642 648
663
709
550
575
600
625
650
675
700
725
PCI (Kg/THM)
101 96
62
71
83 81
50
0
25
50
75
100
125

7
Top Gas Temp (Avg)
173
157
164
187 189
206
224
150
170
190
210
230
Refractory Temp (Avg)
311
296
286 283
253 249
286
230
250
270
290
310
330

8
FIRST VISUAL INSPECTION
• Shutdown was taken on 08.12.09 for visually inspecting the condition
inside the furnace.
• Stock level was brought down by 9 meters & shutdown was taken.
• The Furnace inspection holes at different elevations were opened.
• On inspection, huge accretion formation was noticed. The exact
location and thickness of accretion was estimated.
• The accretion build up started from 23-m elevation (Middle stack)
and extended downwards up to 20m elevation.
• It was spread between 180° to 360° with reference to tap hole at 0°.
• The accretion appeared to have blocked 25 – 30% of area.
• The size was in the order of 30 to 35 M3.

9
ACCRETION
BLAST FURNACE 2
Inspection Holes 4 X 60 mm dia
21 meter elevation
19 meter elevation
16 meter elevation

11
ACCRETION ANALYSIS
 High in ZnO & K2O.
 All the inputs like coke, ore,
sinter, mill scale etc and
outputs like flue dust and GCP
dust are normally subjected to
chemical analysis.
 Special analysis was carried
out to identify the Zn carrying
input.
Analysis
Near
the wall
Middle
portion
Away
from
the wall
Fe2O3 38.30 5.16 17.19
Al2O3 24.80 31.19 15.13
SiO2 18.10 13.63 21.75
MgO 0.65 0.92 4.55
CaO 2.30 3.34 18.43
K2O 2.36 16.50 12.22
TiO2 0.92 0.90 0.48
P2O5 0.15 0.12 0.51
Na2O 0.09 2.06 2.60
ZnO 10.76 14.93 1.83

12
POSSIBLE REASONS FOR ACCRETION FORMATION
EOF Sludge
Higher Zn
through
purchased
scrap
Accretion
formation
Alkali
accumulation
Low level
dumping
during
hanging /
slipping
Higher
Zn
input
Sinter
Higher Zn
through
purchased
Mill scale
Coke
Higher
Zn
through
coking
coal

13
ALKALI BALANCE
Alkali Input & Output (Kg/THM)
2.97
2.83 2.83 2.85 2.86
3.25
3.62
3.09
2.75
2.66
2.47
2.89 2.88
2.67
94
98
88
95 94 96
111
2.00
2.20
2.40
2.60
2.80
3.00
3.20
3.40
3.60
3.80
40
50
60
70
80
90
100
110
120
In put Out put Flushing %
Very low flushing

14
Input Percentage Kg/THM
Percentage of
Input
Coke 0.006 0.029 5.40
Sinter 0.045 0.450 94.1
Coal 0.002 0.002 0.50
Total input 0.525
Output Percentage Kg/THM
Percentage of
output
Flue dust 0.76 0.372 64
GCP dust 0.80 0.208 36
Total output 0.580
Flushing percentage 110
TYPICAL ZnO BALANCE

15
ACTIONS INITIATED
 Following operational practices were initiated:
 Peripheral working was intensified,
 Charging extra cokes,
 Clean up charges at regular intervals,
 Lower RAFT,
 Low basicity of 0.90 to 0.95
 Usage of BF2 flue dust in sinter plant stopped
 These actions showed some improvement but the trend of revival was
very marginal.

16
REVIEWING THE SITUATION
 On 10th Jan 2010 another
shutdown was taken.
 The stock level was brought
down by 10 meters.
 Visual inspection carried out.
REVIEW FINDINGS
 Not much change in the Accretion size.
 Conventional method could take much longer time to
normalize the furnace operation.

17
VARIOUS OPTIONS AVAILABLE FOR ACCRETION DISLODGING
Coke bunches charging along with Clean up charges
 Furnace has to run consistently.
 Higher silicon to be maintained.
 Difficult to dislodge the accretion if it is located in granular
zone.
 It may take much longer time for normailising the furnace.

18
Controlled Blasting
 Faster recovery compared to other methods.
 Holes to be drilled through shell & lining.
 Requires expert blasters.
 Blasting effect on lining unpredictable.
 Temperature where Explosive to be placed shall be maximum 40°C.
 Personal & equipment safety is a key factor.

19
Blowing down the furnace & manual breaking
 Furnace to be blown down up to tuyere level.
 Inside atmosphere shall be suitable for people to enter
inside the furnace.
 Personal safety is a key factor.
 Time consuming and startup will be slow.

20
SELECTION OF CARDOX METHOD FOR ACCRETION REMOVAL
Available options
Coke bunches
charging along with
Clean up charges
 Controlled Blasting
 Blowing down the
furnace & manual
breaking
Constraints
 Longer time for
normalising the
furnace
 More coke
consumption
 Personal risk
 Potential risk of
damage to
equipment /
refractory
 Expertise
requirement
Search
for
new
Methods
_____________
Cardox
method
(Liquid CO2
Activation)

21
THE WORKING OF CARDOX SYSTEM
 Cardox consists of a high strength reusable steel tube filled with liquid
carbon dioxide, a chemical heater and a rupture disc.
 When energised by the application of a small electrical charge, the
chemical heater instantly converts the liquid carbon dioxide to a gas.
 This conversion expands the CO2 volume and builds up pressure inside
the tube until it causes the rupture disc at the end of the tube to burst.
 This releases the CO2 - now 600 times the original volume - through a
special discharge nozzle to create a powerful heaving force, at pressures
up to 40,000 psi (3,000bar).
 This all takes place in milliseconds.

22
Before :
Socket welded in to
hole provided in the
shell
Cardox tube is
placed in the tube
holder, inserted and
then secured in the
socket. The tube is
then activated.
After: The tube is
removed and system
is ready for use

23
CARDOX TUBE

24
EXECUTION METHODOLOGY
• On 02.02.10, burden level was lowered by 10 meters and shut down
taken.
• Accretion was from 23 meter elevation (Middle stack) and extended
downwards up to 20 meter elevation.
• In four identified locations at 21 meter elevation, Shell plate was cut by
gas cutting
• In those locations, four holes of 75 mm dia were drilled by core drilling
machine
• Special stainless steel sockets with locking arrangement were welded
inside the holes.

25
Core drilling in the furnace shell Socket welding the hole

26
• Cardox tubes were filled with liquid CO2 from cryogenic cylinders
using Cryogenic pump .
• Actual quantity of CO2 filled was measured by weighing the tube
before and after filling.
• Cardox tubes were fixed in the sockets and locked.
• Liquid CO2 activation was initiated.

27
Cryogenic pump for filling Cardox tube fixed in
the socket
Safety locking system for
Cardox tube

28
LIQUID CO2 ACTIVATION
Activation
No. of
tubes
used
Liquid
CO2
Quantity
filled in
each tube
Location Observation
1st stage
activation
2 720 grams 21 mtrs elevation
at 236°, 245°
holes
Not much impact
2nd stage
activation
at 245° hole
Internal cracks
observed
3rd stage
activation
at 332°,245° holes
Accretion dislodged

29
Activity Time (minutes)
Shell plate cutting 120
Core drilling machine fixing 15
Core drilling -2 holes in 180 minutes 360
Socket welding (Liquid CO2 filling parallel activity) 120
Inserting the Cardox tubes in the socket 15
1st
stage Activation & Observation 20
2nd
stage activation & observation 20
Liquid CO2 filling in tubes 45
3rd
stage activation & observation 20
Sockets removal 45
Refractory fill up in the holes 25
Shell plate welding 220
Total time taken 1025
(17 hours)
LIQUID CO2 ACTIVATION – ACTIVITY CHART

30
FURNACE PARAMETERS - BEFORE & AFTER ACCRETION REMOVAL
Blast Volume (Before & after accretion removal)
Blast Volume Nm3/Hr
71200 70450
66007
67249
62121
67020
72400 72840
73778
75053
73814 73407
75122
67170
58000
62000
66000
70000
74000
Jul-09 Aug-09 Sep-09 Oct-09 Nov-09 Dec-09 Jan-10 5-Feb 6-Feb 7-Feb 8-Feb 9-Feb 10-Feb 11-Feb
After
Before

31
Fuel Rate (Before & after accretion removal)
Fuel Rate Kg/THM
592 597
650
642 648
615 616
607
600 602
592 591
663
550
575
600
625
650
675
700
After
Before

32
Productivity (Before & after accretion removal)
Productivity (on WV) MT/M3/Day
2.98
2.86
2.47
2.63
2.34
2.25
2.53
2.84
3.12
3.18
3.10 3.13 3.12
2.56
2.00
2.25
2.50
2.75
3.00
3.25
Before After

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