Soak Zone and Discharge Dropout Losses

Soak Zone and Discharge (Dropout) Losses (see also sec. 4.6.2., add this heat requirement to the available heat required in 2.1) 

The required available heat for the soak zone will be the sum of (a) the remaining heat needed into the loads to heat them to good quality (b) heat losses to and from refractory, hearth materials, openings, and water-cooled devices and (c) heat absorbed by infiltrated air in warming to zone temperature. 

Temperature profile In the soal zone when no product heating. 

To prevent the resultant increase in fuel required per unit weight of load is to limit the volume of infiltrated air moving through the discharge opening 

by holding the furnace pressure at the knuckle as high as reasonable, for example, 0.06 to 0.1 wc (0.149 to 0.249 kPa) so that all of the discharge slots have positive pressure for outleaking poc, not inleaking cold air 

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