Redesign of Bell Mouth Nozzles Used in Converters in Acid Plant

The converters are the focal point of sulfuric acid production, in which contains series of catalytic beds which are used for the oxidation of sulfur dioxide to sulfur trioxide. The commonly used  converters consists of four or five catalyst beds filled with vanadium pentoxide catalyst and the beds are having separate inlets and outlets Due to the high temperature produced during oxidation of sulfur dioxide, which is an exothermic reaction, temperature increases to a maximum of 600oC.

Bell mouth nozzles are commonly used as the inlets and outlets of catalyst beds since it allows maximum amount of SO3 gas to be drawn into the duct and also provides a thorough distribution of SO2 gas over the catalyst beds. The converters and nozzle are commonly made of carbon steel. It has been identified most of the bell mouth nozzles used in converters of chemical industries undergoes regular failure.

This thesis mainly aims at redesigning the bell mouth nozzle for improved reliability. Transient thermal analysis of nozzle was done in ANSYS by changing the material and thickness of nozzle. The effect of various nozzle exit geometries (rectangular, circular and elliptical) on stress, deformation and fatigue life was found out using transient thermal analysis and an optimum geometry of nozzle of suitable material and thickness was found out and proposed.