Furnace Technology
Fuel economy in an industrial furnace operation can not be achieved by the use of

Stoichiometric combustion air
Combustion air not enriched with oxygen
Non-preheated combustion air
Recupterators

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Furnace Technology
Turn down ratio of a burner

Is the ratio of maximum to minimum permissible heat input rates
Is normally much more for a continuous furnace as compared to a batch furnace
Should be 1:1 for a batch type furnace.
Should be as low as possible i.e., 1 : 2

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