Importance

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Abstract

A furnace (10) has a preheater zone (12) into which exhaust gases from a combustion chamber (14) are recycled for preheating of articles passing through the furnace. The exhaust gases are supplied to the preheater zone (12) through jet pipes (18) which create a turbulent flow about the articles in the furnace (10). The exhaust gases are withdrawn by a fan (30) which is disposed in a duct (34) adjacent to the furnace entrance (13). To prevent the introduction of ambient air into the furnace (10), a pressure chamber (56), which is maintained at about atmospheric pressure, is provided within the preheater zone (12), with the chamber (56) pressurized by gases supplied by exhaust gases passing through a separate pipe (70) which has an adjustable valve (72) to adjust the pressure in the chamber (50). A sealing arrangement defined by the pressure chamber (56) and the articles passing through the furnace prevents the introduction of cool air through the preheater zone (12). In this way, the thermal efficiency of the fuel burned within the combustion chamber (14) is maximized while a pressure balance is maintained in the furnace.

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First Claim