Melter Bottom Thermocouples
The BASF line of Glass Melter and Refiner Thermocouple Assemblies represent the cumulative benefit of more than 50 years of dedicated design and assembly service to the glass industry. The care and attention to detail in material selection, processing, and assembling, have been developed and established with campaign life as a goal while maintaining EMF stability and reliable performance as a prerequisite.
Bottom melter thermocouples play an important role in the efficient operation of a glass tank. It has been shown that for each 1.3°C lowering of bottom temperature, a typical furnace will save approximately 1% energy. To control the melt process so that lower bottom temperatures can be achieved, while maintaining proper circulation and throat flow demands a high level of reliability in the sensor. In addition, throat flow monitoring, especially gradient temperature determination, is useful if the sensors are stable.
One innovation introduced by BASF that has resulted in more stable performance is Enclad. Enclad was first introduced by BASF to the glass industry in the early 1960s. It is now specified routinely by a number of quality glass producers and major engineering houses for use in bottom immersion applications. Enclad is a precisely controlled combination of thermocouple wires, crushable ceramic and metallic sheath that is assembled under clean conditions and consolidated to an integral product. The consolidation process sinks the metal sheath to the ceramic, pulverizing it to compact around the wires and densifies the composite to be void free.
Enclad thermocouples are not subject to failure due to airborne dust, dirt, or vapors as conventional thermocouples are. When Enclad is assembled with precious metal sheaths into otherwise conventionally designed thermocouples, campaign life experiences have been obtained with excellent retention of calibration. It has been successful in obtaining campaign life and solving problems in electric melt/boost applications. Its concept is now copied by a number of independent thermocouple assembly shops.