Heater operation is initiated each working day morning at 3:00 by a time clock. By 5:30 A.M. the salt bath has reached 300 ° F., then operation is automatically placed under the control of a thermostat which has been preset the night before to a maximum of 700 ° F. Thermostatic control is in two stages: on temperature drop from preset temperature six of the 15 heaters are energized; drop to 21° below set temperature brings on remaining nine heaters. On temperature rise action is reversed. This arrangement provides more uniform temperature control and better performance with broader load distribution.
High-temperature open flame was causing 1. Great discomfort for workers, particularly in immediate vicinity of the tank, and 2. Burnouts of the tank bottom which necessitated tank replacements at $400 each and replacement of fire brick lining of combustion chamber at $1,000, each approximately every two years.
Fifteen over-the-side, L-shaped Chromalox stainless steel sheathed immersion heaters, Type TBL-6001A, 480 volts, 6 kw., equally spaced over the length of the tank. Tank is 13 feet long, inside width is 23 inches and salt depth is 17 inches. Tank contains about 3,000 lbs. of salt. Parts are poured continuously on the conveyor.
- It improved working comfort by permitting the utilization of all btus in the salt -no more are used than are actually needed to obtain the right operating temperature -heat losses are confined to surface losses only.
- It does not attack the steel tank - temperature on the steel is the actual heat of the molten salt, not in excess of 700 ° F.
- It gave these advantages at approximately the same operating cost as natural gas.