SEDL / STP / STP728-EB / STP28062S

Use of Zirconium Heat Exchangers in the Viscose Rayon Process

Bowen, LB
Engineering manager, Avtex Fibers, Inc., Front Royal, Va.

Pages: 7    Published: Jan 1981

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Abstract

Zirconium tubed heat transfer equipment has been used successfully in the viscose rayon process since 1970. Heating coils are used to heat sulfuric acid solutions to 373 K, shell-and-tube and bayonet heat exchangers to heat spinning baths to 343 K, and thermosiphon evaporators to remove water from spent spinning bath solutions. Energy usage and heat exchanger maintenance costs have been reduced as a result of converting to zirconium tubed heat exchangers. High concentrations of sulfuric acid were found above plugged tubes in three evaporators. This acid, which is corrosive to zirconium, destroyed one heat exchanger. By increasing the liquid level height to flood the top tube sheet, the plugging rate was reduced, thus eliminating the corrosion.