Hi THERE I am here again for your help to your high school, college assignments. Today we going to learn about the oldest furnace technology used in
Today we going to learn about the oldest furnace technology used in foundry.
- The most widely used furnace in the foundry for melting ferrous and non-ferrous metal and alloys. a cross section of a cupola is shown .
- A cupola is a shaft furnace of cylindrical shape erected on legs and columns . The cupola shell is made of steel plate 8 or 10mm thick.
- The interior is lined with refractory bricks to protect the shell from overheating.the charge consist of fuel(coke as anthracite) fluxes(limestone used for decontamination of charge) and material (pig iron,scrap etc.)
- Charging is mechanised by drop bottom buckets.
- Air for combustion deliver through blowers. and enter into a chamber called wired box.
- At the top of cupola there is there is a spark arrester to catch the incandescent dust and gases.
TUYERS are important part in cupola , they are the openings which extend through steel shells and refractory wall to the combustion zone.
- A tap hole is provided to take out the molten metal.
A VIDEO FOR BETTER UNDERSTANDING
DIMENSION OF CUPOLA
Cross section area of cupola is equal to:
A= π *d^2 /4 =Q/Q1
d=clear diameter of cupola
Q=designed cupola output (in tonnes per hour)
Q1= specific output of the cupola (in tonnes per sq-m per hour)
As a rule = Q1=6 to 8
The cupola height is 3-5 times the diameter.
Height affects the melting rate , fuel consumption, and quality of molten metal
if too much height then coal is crushed under self weight.
if too small then molten metal is not heated properly thus reducing the output also.
Common dimensions are
OUTER diameter : 900-2700mm
INSIDE diameter : 500-2100 mm
HEIGHT : 12 m
FOR various purpose design charts is shown
DESIGN SPECIFICATION OF CUPOLA
Various heat zone in cupola
- COMBUSTION zone : The highest temperature developed in cupola furnace is in this zone. 1600-1700*C the reaction is exothermic : C + O2 ———-> CO2 + HEAT
- REDUCING zone: it’s above combustion zone up to height of initial coke bed.
The CO2 flowing upward reacts with the hot coke and reaction is endothermic.
This zone application is to protect the metallic charge from oxidation due to its reducing
nature, CO2 + Coke —————> 2 CO(reducing agent) – heat.
- MELTING zone: This zone includes the first layer of iron above the coke bed.
In this zone the charge starts to melt.
Also iron carbide formation take place.
3Fe + 2 CO ————–> Fe3C + CO2
- PREHEATING ZONE: In this zone moisture,volatile materials are evaporated and the layers of charge are heated by outgoing gases and temperature here is about 1090*C.
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