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Ceramic Fiber Heaters Ease Dye Process Heating

Problem:

Large vats of heated caustic soda are used in making the blue indigo color dye for blue jeans. Maximum vat temperature is 900°F (480°C). Immersion heaters would not provide a good life in the caustic solution at these temperatures.

Tubular heating elements held against the outside of the tank were also tried and then rejected because of mounting complexity and multiple connections.

Solution:

Three large modular wall sections, each holding 18 ceramic fiber panels 24-inches high and 17-inches wide (61 X 43 cm), curved to a 98-inch (2.5 m) diameter. Total wall thickness of each module was 6-inches (15 cm). The system runs cooler and more efficiently than the previous 10-inch (25 cm) thick walls.

A total of 54 units were placed around each tank, and total input capability of 81 kW. Watt density per panel is under 5 W/in2 (0.8 W/cm2).