| 摘要 |
PURPOSE:To preheat steel strip while always maintaining its surface property satisfactorily, by heat exchanging combustion waste gas with air to prevent direct contact of steel strip surface with combustion waste gas. CONSTITUTION:High temp. waste gas exhausted from a radiant tube 6 in an indirect type heating furnace 2 is introduced to a heat exchanger 7 by a waste gas duct 23 and heat exchanged, cooled to <=heat resisting temp. of a waste gas flue 22 and an intake blower 8, then released from a chimney 9. As cooling medium for cooling high temp. waste gas, air in a preheating furnace 12 is introduced into the exchanger 7, to raise the temp. by heat exchange with high temp. waste gas, then the pressure is raised by a hot wind circulation fan 14, and the air is supplied to a plenum chamber 18 provided in the furnace 12. High temp. air is blasted to a steel strip 1 passing in the furnace 12 from the chamber 18 to preheat it.
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