I had opportunity to work with different type ovens in biscuit factory . They have direct fired ovens and indirect fired ovens . Basically Oven types are selected with following parameters .
Type of Product Speed Capacity
Both direct and indirect ovens have few disadvantages and advantages as far as biscuit production is concerned .Direct ovens are generally used with cracker variety As greater heating is required during baking stage . It has got numerous burners at bottom and top of the oven band .Direct fired operates generally on gas . Controls are less in direct oven .Less energy is consumed in direct oven .
Indirect ovens uses circulating fans to heat pipes or plenum in different zones . Used generally for moulding variety of biscuit as gradual heating is preferred for such type of oven . Control are more in indirect ovens . Energy is consumed more in Indirect oven .
20-30% ( direct ) to 70%-80% ( indirect ) 20-30% ( direct ) to 70%-80% ( indirect )