Heat Transfer Characteristics of Superheater in the Kraft Recovery Boiler

Abstract

Accurate prediction of tube surface temperature is important for determining whether accelerated superheater corrosion will occur in kraft recovery boilers. A heat transfer model, which combines an iterative numerical solution scheme with a more realistic flue gas flow field obtained from the CFD code FLUENT, has been developed to predict the tube, steam and flue gas temperatures in the superheater region. Results of tests performed for a recovery boiler show that temperatures predicted using the model are in good agreement with actual temperatures measured using thermocouples. The presence of a large flue gas recirculation zone above the bullnose is shown to have an adverse effect on the heat transfer in the superheater region.