Furnace blower with external gas recycling for the reduction of NOx

摘要

A furnace system is provided with exhaust gas recirculation via a recirculation tube having an inlet mounted downstream of the furnace firing area and an inlet disposed in juxtaposition to the blower fan wheel of the furnace blower. The recirculated gases can enter the tube from either the stack or the firebox. The inlet penetrates the air intake plenum either axially thereof or at an angle thereto through a sidewall. The furnace includes both an air intake throttle and an air intake butterfly control valve. An exhaust gas recirculation control valve can be linked to the air intake control butterfly valve for their operation in concert. The air intake throttle is either a rigid baffle or a pivotable flap.