A furnace is a device used to heat and melt metal ore to remove gangue in which heat is generated and transferred to materials with the object of bringing about physical and chemical changes. The basis of heat is usually burning of solid, liquid or gaseous fuel, or electrical energy applied through resistance heating or inductive heating.

Furnaces employing fire produce a hot gas that transfers heat to the material by radiation and convection. Solids are heated by direct, but fluids are heated indirectly, being carried inside pipes within the furnace.

An engineering industrial furnace or direct fired heater is an equipment used to supply heat for a process or can serve as a reactor that provides heats of reaction.Furnace design varies as to its function, heating duty, type of fuel and method of introducing burning air.

Furnace Fuels
The mixture of gaseous, liquid and solid fuels used in furnaces. calorific value includes the heat released by the condensation and cooling of combustion products and the burning air/fuel ratio.

The Advantages of a Furnace for Heating:

  1. Multiple use of ductwork
  2. Good energy efficiency
  3. Widely available
  4. Heats quickly