Upgraded.............
'G' BLAST
FURNACE
‘G’
Blast Furnace was commissioned in 1992 with
an installed capacity of 1 million tonne per annum (MTPA) hot metal production. Over the
years with various improvement measures, the production capacity of the furnace was
brought upto 1.2 MTPA. It was blown down on 3rd December 2004 for massive upgradation
work. During its 12 years of operation, the furnace produced 14 million tonnes hot metal.
The upgradation work was undertaken to enhance the capacity of the furnace to 1.8 MTPA
with an expected life of minimum 15 years with state-of-the-art technology including:
copper and cast iron staves, high top pressure, automated stag granulation crane, furnace
cooling with demineralised water, enhanced coal injection facilities, etc.
Upgraded 'G' Blast Furnace
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Besides capacity enhancement, the
upgraded ‘G’ Furnace has been equipped with a sophisticated monitoring and
control system and an up-to-date automation system to enable the furnace to produce high
quality hot metal at the lowest cost.
For achieving cost-effective upgradation,
a critical study of the existing and proposed new facilities was made. A judicious balance
between the old and new facilities was struck.
Upgraded 'G' Blast
Furnace model
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To minimise the shutdown period, a
project monitoring system comparable with the world’s best practices was put in
place. Substantial quantity of work was completed during the pre-shutdown period while the
furnace was in operation. A highly dedicated, experienced and motivated work force from
Projects, Works, Contractors and Consultants was engaged to fulfil this objective. Areas
of concern were : safety hazards of BF gas, space constraint, working at heights, etc. The
existing ‘G’ Furnace also did not have any provision for salamander tapping. A
rigorous exercise was undertaken with the help of European and Russian experts to assess
the salamander volume, deciding on the salamander tapping location and making provision
for salamander tapping while the furnace was in operation. For this purpose, a mock trial
was conducted to facilitate the equipment selection, etc. Certain exercises were
undertaken before hand to gain confidence on successful salamander tapping.
New BF shell erection |
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For the first time in Tata Steel, the
salamander was tapped with the wind on to reduce the tapping time and the residual amount
of hot metal. The repair of the blast furnace stove burners was successfully performed in
all the three stoves while keeping the stoves in hot condition. This was also the first
such feat in India. An elaborate procedure for furnace blowing down was also established
in consultation with all experts from SMS Demag and the operating personnel.
For the first time in Tata Steel, the
burden level was lowered to the tuyere level before salamander tapping to accelerate the
evacuation of the furnace after blowing down.
'G' Blast Furnace upgradation
activities
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After having gained experience during the
‘F’ Blast Furnace upgradation work, the knowledge of dismantling sequence for
the furnace shell and erection was firmed up using a movable trolley for shifting of the
shell assembly. Strand jacks at two different levels of supports were provided for the
purpose, after ascertaining the adequacy of the existing tower structure.
This furnace with copper and cast iron
staves, as well as well designed carbon hearth is the first of its kind in India and is
poised to scale newer heights of excellence in the days to come.
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Main features of the
upgraded “G” BF |
| Target |
: |
1,800,000 HM t/year (+36%) |
| Daily average |
: |
5150 HM t/day |
| Working volume |
: |
2300 m3 (+46%) |
| Hearth diameter |
: |
11,05m |
| No. of tuyeres |
: |
30 |
| No. of tapholes |
: |
2 |
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Project data |
| Concrete, cum |
- |
19000 |
| Structural steel, tonnes |
- |
5500 |
| Shell, tonnes |
- |
650 |
| Refractory work, tonnes |
- |
7300 |
| Equipment, tonnes |
- |
4600 |
| Cable laying, km |
- |
950 |
| Piping work, km |
- |
75 |
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Major
milestones |
|
Improvements brought
about |
| Placement of order for main package |
10 Apr ’03 |
|
Parameters |
Before (1992-2004) |
After (2005) |
| Commencement of pre-shutdown
work |
1 Sep ’03 |
|
Furnace capacity, Mtpa |
1.2 |
1.8 |
| Delivery of imported equipment |
April ’04 |
|
Working volume, cum |
1581 |
2308 |
| Delivery of BF shell from TGS |
Mar ’04 - May ’04 |
|
Furnace campaign life, years |
13 |
15 at least |
| Pre-assembly of BF shell by
L&T |
Apr ’04-Aug ’04 |
|
High top pressure, bar g |
1.25 |
1.5 |
| Furnace blow out |
3Dec ’04 |
|
Tuyere, nos |
22 |
30 |
| Salamander tapping |
3Dec ’04 |
|
No. of cast house |
1 |
2 |
| Furnace shell dismantling |
6Dec ’04 - 3 Jan ’05 |
|
Taphole angle, deg. |
72 |
132 |
| Erection of BF shell |
5Jan ’05 - 18 Jan ’05 |
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| Refractory work |
23 Jan ’05 - 6 Mar ’05 |
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| Cold and sequential trials |
7Mar ’05 - 22Mar ’05 |
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| Furnace filling |
22 Mar ’05 |
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| Blow-in |
6th April ’05 |
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| Main
changes Extension of cooled wall
area
- Replacement of existing cooling boxes with cast iron
staves to have thinner walls and avoid dome shell replacement
- Provision of entirely cooled shaft up to throat armour
area to better sustain the increased heat loads resulting from higher PCI operation
- Tuyere zone stave cooling+carbon block lining
Installation of copper staves in the critical
area
- Hot rolled copper staves (SMS Demag design)
- Largely tested equipment as a key component to ensure long
campaigns
Hearth geometry/materials quality upgrade
- Super-micropore carbon blocks in the elephant foot and
taphole area
- Micropore carbon blocks in the lateral walls
- Minimisation of the number of joints by large blocks
installation.
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