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Furnaces and their applications in high temperature industries:
Furnaces are used for wide variety of processing of raw materials to finished products in several industries. Broadly they are used either for physical processing or for chemical processing of raw materials. In the physical processing the state of the reactants remains unchanged, whereas in the chemical processing state of the reactants changes either to liquid of gas. In the table given below some applications of furnaces for physical and chemical processing are given ( the reader may go through detailed description in order to appreciate the requirement of the design of thermal enclosure, i.e. furnace):
PHYSICAL PROCESSING
Unit process |
Purpose |
Energy source |
Temperature in oC
|
Type of furnace |
Carbonization |
Conversion of coal to coke |
Indirect heating by burning fuel |
≈ 1000 to 1200 |
Coke oven |
Calcination |
Removal of CO2 from CaCO3 for cement production
Production of anhydrous alumina for electrolysis |
Fossil fuel
Fossil fuel |
≈ 1200
≈ 1300
|
Rotary kiln
Rotary kiln
|
Roasting |
To convert sulphide into oxide partially or completely |
Chemical + Fossil fuel |
≈ 900 |
Multiple hearth furnace,
Fluid bed roaster, etc |
Heating |
To eliminate segregation
To perform hot working
To perform heat treatment |
Mostly oil and gas fired |
Below the melting points of materials |
Batch type or continuous type |
Sintering |
To produce compacts of particles |
Fossil or electric |
Below the melting point |
Sintering furnaces |
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