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A REVIEW FOR SELECTION

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MELTING PRACTICESTraditional Coke fired Crucible FurnaceTraditional Coke fired Cupola

Rotary FurnaceDivided Blast CupolaSmall Induction FurnaceHigh Powered Large Capacity Induction SystemsGas Fired Cupola in place of CC or DBCHigh Production with Induction Furnace, some withduplexing from cupolas

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IMPROVEMENTS IN

CONVENTIONAL CUPOLAS Various Technological Improvements have been doneall over the world. Hot blast, Side Charging, Oxygenenrichment, Divided Blast, High Melt Rate LongCampaign, Liningless Cupola and ComputerControlled Melting Process are some of these.Out of these only DBC has been found to be applicablein South Asia because of least cost and very good

reduction in coke ratePollution control device in small DBCs is very cheap Availability of better Coke and Pig Iron has helped theconventional cupolas to a large extent

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DIVIDED BLAST CUPOLAHistoryChanges in Design : Blowing known quantity of air in

two rows of tuyers from separate wind belts fed by airsplit into two from the blowerCoke Consumption reduced from 15% to 35%Reasons for Highly Improved Coke Rate

Efficient Combustion of carbon to CO2 to reduce CO inexhaust gas to negligibleStack height increased to accommodate minimum 6charges to pre heat the charge more effectively

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35%

40%

10%

13%

2%

Thermal Balance of ConventionalCupola

59%5%

15%

8%

2%

Thermal Balance of Divided BlastCupola

Metal Latent Heat of CO2

Slag Sensible Heat of Exhaust Gas

Heat Loss Through Walls

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ROTARY FURNACELow Capacity Batch Type FurnaceFurnace oil / LDO / Gas fired

High Fuel Consumption 6 Kg Liquid Metal per Kg oilPoor Fuel Effeciency (25%) Very Large Capacity fuel efficient gas furnaces are usedabroad for melting along with duplexing in channelholders

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SECTIONAL VIEW OF COKELESS CUPOLA

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COKELESS OR GAS FIRED CUPOLAHistoryConstruction and Operation

Gas Consumption Natural gas 85 m3 per ton

- LPG 60 m3 per tonHighest Fuel Effeciency due to direct contact of burntgases with charge and no or very little slag formation

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ENERGY EFFECIENCY AND CARBON FOOTPRINT

OF DIFFERENT MELTING METHODS

Importance of being environment friendly andreduction of global warming carbon footprint

Calculation of Energy efficiencyCarbon footprint related to Energy efficiencyCalculated Energy for melting cast iron of 370 KWHper ton is exactly the same as calculated by an

American Foundryman

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ENERGY EFFICIENCY

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CARBON FOOTPRINT

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PUBLISHED DATA FOR CARBON FOOTPRINT

OF CUPOLA AND INDUCTION FURNACE

Tons of Carbon dioxide produced per ton ofcasting shipment

Induction melting foundry producing more than two and a half timesCO2 than a cupola foundry for same production and dispatch.

GREY IRONCUPOLA

INDUCTION MELTINGFURNACE

Electricity 0.5 2.47Natural gas 0.19 0.35Coke 0.45 -Others 0.02 0.04TOTAL 1.16 2.86

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MELTING COST IN SOUTH ASIAN

FOUNDRIESCost Inputs in India and Pakistan are as follows

HARD COKE- Low ash , 12% Rs 30/- PKR 70/-HARD COKE- High ash 30-35% Rs 16/- ----NATURAL GAS (per nM3) Rs. 32/- PKR 13/-LPG (per Kg) Rs. 58/- PKR 28/-ELECTRIC POWER Rs. 5/- per kWH PKR 15/- per kWHREFRACTORY BALLS FOR COKELESS Rs. 37/- kg Assume PKRFURNACE OIL Rs. 30 PER KG PKR 70 PER KGDUPLEXING POWER 80 kwh/ ton, For cokeless cupola-2 kg of refractory balls/ton

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Rotary Furnace

InductionFurnace

CC high ashcoke

CC low ashcoke

DBC highash coke

DBC lowash coke

CokelessNG

CokelessLPG

DuplexingDBC low

ash

DuplexingNG

IndiaPak

MELTING OR CONVERSION COST

OF METAL IN INDIA AND PAKISTAN

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CONCLUSIONSIn India, Duplexing in DBC and/or Cokeless are themost Energy efficient, Environment friendly andEconomicalDirect Melting in Induction Furnace is most Energyinefficient, least Eco friendly and CostliestDuplexing from Cokeless is the best in Pakistani

conditions Very Low Power Channel Induction Furnaces are beingused abroad for Duplexing

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RECOMMENDATIONSSmall Conventional Foundries must modify / replace theircupolas to DBC and start duplexing in small InductionFurnaces

Medium and Large Scale Foundries must install requisitenumber of small cupolas and duplexing in normalinduction furnaces or channel holdersFor ductile iron and restricted power availability, cokeless isthe best choice, especially in PakistanSaving scarce electricity by above methods will make ourlife easierContribution to reduction in global warming by foundrytrade will help the future generations