Article about Induction Furnace

INDUCTION FURNACE – THE ENVIRONMENT FRIENDLY MELTING EQUIPMENT

Today preserving the Environment is the primary duty of all word citizens. Nature has supported all human development activities over the year. However man’s greed  for more and more has tilted the balance to such an extent that survival of making on the planet has. Become a big question mark.

Extraction of metals from primary sources (ores) is a very energy intensive activity and thus recycling of metals has gained great importance considering the above fact. Even here use of Coal and other hydrocarbons cause energy sources cause immense environmental pollution and it is in this context.        

What is an Induction Furnace?

A water cooled Copper coil carrying High Frequency Current, produces eddy current in the charge / metal inside the coil. This phenomenon hearts up the shared metal and melts it. The machine working on such a principle is known as an INDUCTION FURNACE.

The main components of an Induction Furnace:

Medium frequency furnaces operate at frequencies ranging form 150 to 10,000 HZ. Such furnaces prove concentrated High Power in small volumes with a definitely higher melt rate. Today the Coreless Medium Frequency Induction Furnace is more widely used than its Channel type counterpart.

In an Induction Furnace, Electrical Energy is transformed into Magnetic Energy and again back to Electrical Energy which is converted into Heat by the Joule Effect

Crucible:

Structurally it consists of three independent but interdependent sections:

1. Base Frame
2. Tilting Frame
3. Interchangeable Inductor comprising a coal made from specially shaped copper section featuring high strength and very high conductivity.

The melting basin positioned inside the inductor (coil) is isolated by a thick refractory lining in between.
A special hydraulic system ensures easy emptying, smooth and complete pouring.
That the Induction Furnace assumes great importance for its eco friendliness and energy efficiency.

ADVANTAGE OF THE INDUCTION FURNACE

• Faster Startup
• Flexibility
• Natural stirring
• Clean melting
• Simple Operation
• Higher Yield
• Low refractory cost
• Better working environment

A Typical installation includes

1. Crucible
2. Solid state power converter
3. Power factor compensation capacitor bank
4. Auxiliary equipments

Solid State Power Converter:

Converts the line / mains frequency into a medium frequency essential for efficient operation.

1. Conversion from AC to DC
2. Rectifying & filtering DC current
3. Converting DC into AC (Medium Frequency)
4. Electrical safety, Protection, Regulation and Control circuits Closed loop water – to – water heat exchange using De mineralized water.

THEORETICAL ENERGY CONSUMPTION OF DIFFERENT METALS @ POURING TEMPERATURE:

LOSSES IN AN INDUCTION FURNACE

The theoretical energy require to melt one Ton of steel is 383 KWH/Ton.
However in actual practice, the specific energy consumption is remarkably higher to 550 KWH/ to 950 KWH/ ton

THE POWER LOSSES IN AN INDUCTION FURNACE SYSTEM
MF generator 3% to 4%
Capacitor Bank 1.5% to 3%
Crucible 20% to 25%
ADDITIONAL LOSSES.
Radiation loss 7% to 9%
Conduction loss 4% to 8%

Above figures may very, depending on

1. Furnace Design parameters      2. Size of the furnace      3. Scrap quality      4.  Plant operating parameters

ESTIMATION OF ACTUAL FINISH TIME OF MELTING OPERATION:
1 METRIC TON OF STEEL @ 1650 C using a 350 KW/1000 HZ FURNACE

Energy To Melt Steel Scrap 383 kwh + Induction System Losses 105 kwh + Additional Losses 35 kwh = Total Energy For melting 523 kwh
Total Energy For Melting 523 kwh + Applied Rate of Energy 350 kwh Time Taken = 1 hr 30 mins +
Plant Specific Issues Plus Time Taken For Charging / samples Testing Etc Approx. 15 mins

Total Time 1 hrs 45 min

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