Temperature Control Above the Load s

With the advent of fuel-directed, ATP burners, two temperature locations can be held at the same temperature or a constant difference in temperature, a nearly flat temperature profile regardless of the load size or location. 

In addition to the two-point temperature control, other temperature measurements and control loops can be added in each zone to act as control monitors. When used with low-select devices on their output signals, these monitors can automatically take control of energy input to prevent overtemperature in the sensor locale. With sufficient monitors, overtemperatures at all potential hot spots of the load can be eliminated. 

With the previous type control system and burners, the temperature control above the loads can be excellent, provided sufficient zones are installed. For batch furnaces, the minimum number of zones should be three—one for each end wall and one for the main body of the furnace. If there are two side-by-side doors, five zones are desirable—one for each side wall, two for furnace body, and one behind the center doorjambs. 

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