System 500 Forehearth cooling
Cooling air is introduced through vented mantle blocks at the entry to each cooling sub-zone and passed longitudinally under the central section of the forehearth roof, exhausting through the central exhaust flue. The cooling air cools the underside of the central portion of roof block, enabling the glass to radiate heat to the cooler refractory surface.
The cooling air also maintains the internal pressure inside the forehearth, ensuring that the products of combustion are exhausted through the side exhaust flues.
The cooling air flow is regulated automatically by a control valve in the cooling air supply and by the simultaneous positioning of the side and central exhaust dampers.
At 100% cooling the side and centre dampers are fully open and the cooling air supply is at maximum.
At zero cooling the cooling air is at minimum, the side dampers closed, and the exhaust gases exit through the open central flue, heating the entire forehearth width.
In normal operation the system will modulate the cooling rate automatically between these two positions according to the cooling requirements of the forehearth.