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CONVERSION OF Electrically Heated Bogie Hearth Furnace to LPG System |
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Reason for Conversion
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Since the electricity changes are
high, the company wanted to convert the system to a different fuel to reduce
energy costs. LPG was the natural since it is the only fuel which is eco
friendly and less contaminating. Further, heaters on continuous use needed
maintenance like welding. |
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B. |
What did we do :
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1. FURNACE : |
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In the Electrical
heating system working height can be fully utilized. But with the LPG
burners it requires extra height at the top for combustion, so that the
flame does not impinge on the jobs. Hence the working height of the furnace
was increased by bringing down the bogie. the furnace was relined with
bricks. The height of the door was also increased by welding extra plate at
the bottom and additional insulation was provided. |
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2. BURNERS : |
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2 Nos automatic LPG
monoblock burners were mounted at top position on the sides, one at left
hand side back and the other at right hand side front. An exhaust was
provided at the bottom on the back wall and connected to a chimney which was
led outside the building. LPG supply to the burners was sourced from a
manifolded cylinder bank through pressure regulator, pressure switch,
pressure gauge etc., |
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3. CONTROL PANEL
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Two nos. separate
control boxes each containing sequence controller and ignition transformer
were mounted near the burners, one for the either burner. The existing
control panel was re wired to suit the LPG system and also to select the
heating between electricity and LPG. |
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4. RESULTS : |
(I) |
The time of heating with LPG is
found to be shorter that with electricity. The Consumption of LPG was higher
during the first trial |
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and it was 7.56 Kg. / Hr. The heat
losses at the bottom were arrested by welding sheets at the bottom to close
the gaps and providing sand seal. Then the consumption was reduced to 5.366
Kg. / Hr. |
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(ii) |
Since the electrical heating is not
disturbed, the system can be operated either on electricity or on LPG. |
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(iii) |
Cycle time for heat treatment is
rreduced on LPG heating. |
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COMPARISION |
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S.NO |
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PARTICULARS |
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ELECTRICITY |
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LPG |
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Initial
Heating Time to reach |
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620
Deg.C. |
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45 mtes |
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32 mtes |
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720
Deg.C. |
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1 Hr |
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40 mtes |
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1000
Deg.C. |
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4 Hrs. |
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3 Hrs, 25 Mtes |
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Cycle
time for 1000 Deg. C. |
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Heating : 4 Hrs. |
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Heating
: 3 ½ Hrs. |
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Soaking : 1 Hrs. |
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Soaking
: 1 Hrs. |
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Total : 5 Hrs. |
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Total
: 4 ½ Hrs. |
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| 3.
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Fuel
Comsumption for the above |
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4 X 48 = 192 |
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1 X 38 = 38 |
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4.5
X 5.4 Kg. / Hr. |
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Total = 230 Volts |
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= 24.3
Kgs. |
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Rate
of Fuel |
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Rs. 5.00 / Unit. |
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(a) Rs.
36.40 / Kg. without |
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modvat |
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(b)
Rs.30.57 with modvat |
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Cost
of Fuel |
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230 X 5.00 = Rs. 1150.00 |
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(a)
without modvat |
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24.3 X 36.40 = Rs.884.52 |
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(b)
24.3 X 30.57 = Rs. 742.85 |
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| 6.
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Add
cost of electricity for |
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Rs.
10.00 |
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combustion
blower (1HP) |
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TOTAL |
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Rs.
1150.00 |
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(a)
without modvat = Rs.884.52 |
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(b)
with modvat = Rs.752.85 |
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Note :
Savings / Cycle ( for 1000 Deg . C.) |
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(i) Without
modvat = 1150.00 - 894.52 = Rs. 255.48 |
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(ii) With modvat = 1150.00 - 752.85 = Rs. 397.15 |