03-09-2012, 03:39 PM
Furnaces and Refractories
Furnaces and refractories.ppt (Size: 1.09 MB / Downloads: 439)
Introduction
What is a Furnace?
Equipment to melt metals
Casting
Change shape
Change properties
Type of fuel important
Mostly liquid/gaseous fuel or electricity
Low efficiencies due to
High operating temperature
Emission of hot exhaust gases
What are Refractories:
Materials that
Withstand high temperatures and sudden changes
Withstand action of molten slag, glass, hot gases etc
Withstand load at service conditions
Withstand abrasive forces
Conserve heat
Have low coefficient of thermal expansion
Will not contaminate the load
Properties of Refractories
Thermal conductivity
Depends on composition and silica content
Increases with rising temperature
High thermal conductivity:
Heat transfer through brickwork required
E.g. recuperators, regenerators
Low thermal conductivity:
Heat conservation required (insulating refractories)
E.g. heat treatment furnaces
Type of Furnaces and Refractories
Type of Furnaces
Forging furnaces
Re-rolling mill furnaces
Continuous reheating furnaces
Type of Refractories
Type of Insulating Materials