Cupola Furnace
Group No 1
Muhammad Zubair MME-12-29
M. Faisal Maqsood MME-12-20
Gulfam Hussain MME-12-30
Arif Ali MME-12-01
Muhammad Ahmad MME-12-14
What is Furnace???
Heating media or device.
Used for heating and melting.
For providing heat to chemical reactions for
processes like cracking.
The furnace may be heated by fuel as in many
furnaces coke is used as a fuel.
some are operated by electrical energy e.g. electric
arc furnace.
Cupola Furnace
Cupola was made by Rene-Antoine around 1720.
Cupola is a melting device.
Used in foundries for production of cast iron.
Used for making bronzes.
Its charge is Coke , Metal , Flux.
Scrap of blast furnace is re melted in cupola.
Large cupolas may produce up to 100 tons/hour of
hot iron.
Construction
Cupola is a cylindrical in shape and placed vertical.
Its shell is made of steel.
Its size is expressed in diameters and can range from 0.5 to
4.0 m.
It supported by four legs.
Internal walls are lined with refectory bricks.
Its lining is temporary.
Parts of Cupola
Spark arrester.
Charging door.
Air box.
Tuyeres.
Tap hole.
Slag hole.
Zones
Well
The space between the bottom of
the Tuyeres and the sand bed.
Molten metal collected in this
portion.
Combustion zone
Also known as oxidizing zone .
Combustion take place in this
zone.
It is located between well and
melting zone.
Height of this zone is normally
15cm to 30cm.
Zones
In this zone the temperature is
1540°C to 1870°C.
The exothermic reactions takes
place in this zone these are
following .
C + O2 → CO2 + Heat
Si + O2 → SiO2 + Heat
2Mn + O2 → 2MnO + Heat
Reducing zone
Locate between upper level of
combustion zone and upper
level of coke bed.
Zones
In this zone temperature is about
1200°C.
In this zone CO2 change in to CO.
CO2 + C (coke) → 2CO
Melting zone
In this zone the melting is done.
It is located between preheating
zone and combustion zone.
The following reaction take place
in this zone.
3Fe + 2CO → Fe3C + CO2 .
Zones
Preheating zone
This zone is starts from the upper
end of the melting zone and
continues up to the bottom level of
the charging door .
Objective of this zone is preheat the
charges from room temperature to
about 1090°C before entering the
metal charge to the melting zone.
Stack
The empty portion of cupola above
the preheating zone is called as
stack. It provides the passage to hot
gases to go to atmosphere from the
cupola furnace.
Charging of Cupola Furnace
Before the blower is started, the furnace is uniformly pre-
heated and the metal, flux and coke charges, lying in
alternate layers, are sufficiently heated up.
The cover plates are positioned suitably and the blower is
started.
The height of coke charge in the cupola in each layer
varies generally from 10 to 15 cm . The requirement of flux
to the metal charge depends upon the quality of the
charged metal and scarp, the composition of the coke and
the amount of ash content present in the coke.
Working of Cupola Furnace
Its charge consist of scrap,
coke and flux.
The charge is placed layer
by layer.
The first layer is coke,
second is flux and third
metal.
Air enter through the
bottom tuyeres.
This increases the energy
efficiency of the furnace.
Coke is consumed.
Working of Cupola Furnace
The hot exhaust gases rise up
through the charge, preheating it.
The charge is melted.
As the material is consumed,
additional charges can be added to
the furnace.
A continuous flow of iron emerges
from the bottom of the furnace.
The slag is removed from slag hole.
The molten metal achieved by tap
hole.
Operation of Cupola
Preparation of cupola.
Firing the cupola.
Soaking of iron.
Opening of air blast.
Pouring the molten metal.
Closing the cupola.
Preparation of cupola
Slag and metal adhere to the cupola lining from the
previous run is removed and lining of cupola is re
made.
The bottom plates are swung to closing position
supported by prob.
The sand bed is then prepared with molding sand
such that its slopes to towards the tap hole.
Firing the Cupola
The cupola is fired by kindling wood at the bottom.
This should be done 2.5 to 3 hours before the molten
metal is required.
On the top of the kindling wood a bed of coke is built.
The height of the coke bed is may be vary from 50cm
to 125cm according to the size of cupola.
Soaking of Iron
When the furnace is charged fully it is maintain for
about 45 minutes.
The charge is slowly heated.
During the stage the air blast is shut off and iron is
soaked.
Opening of blast air
At the end of the soaking period the air blast is
opened.
The taping hole is closed by a plug when the melting
proceeds and molten metal is collect at the bottom.
Pouring of molten metal
When the sufficient amount of metal has collected in
the hearth the slag hole is opened and the slag is
removed.
Then taping hole is opened and molten metal is flows
out in the table.
The same procedure is repeated until the charge is
melted and the operation is over.
Closing the cupola
When the operation is over the air blast is shut off .
The bottom of furnace is opened by removing the
prop.
Advantages
It is simple and economical to operate .
Cupolas can refine the metal charge, removing impurities
out of the slag.
High melt rates .
Ease of operation .
Adequate temperature control .
Chemical composition control .
Efficiency of cupola varies from 30 to 50%.
Less floor space requirements.
Disadvantages
Since molten iron and coke are in contact with each
other, certain elements like si , Mn are lost and
others like sulphur are picked up. This changes the
final analysis of molten metal.
Close temperature control is difficult to maintain
Any Question?????????
