Controlling the operation of roller hearth tunnel kilns - using air preheated during cooling of the baked ceramic prods.

摘要

The kilns ae used to bake ceramics or refractories and include a forced cooling zone near the outlet end of the kiln and fed by a blower with atmos air. Downstream from the blower is a suction fan extracting the cooling air mixed with combustion gases and recycling the mixt. partly to the kiln and partly to a blower. Blower is also fed with atmos. air, and supplies air for combustion to burners located along the tunnel kiln. Another suction fan is pref. used at the inlet end of the kiln to create a counter-current of burnt gas, i.e. travelling in the opposite direction to the workpieces; the gas includes gas and vapour arising from organic impurities in the workpieces. Zone pref. has air inlet pipes on each side of the kiln, and the angle of the air streams from these pipes can be varied. Provides accurate kiln control, e.g. in baking tiles or bricks.