The Effect of Recovery Furnace

A commercially available computational fluid dynamics code has been used to simulate temperature and flow profiles in the upper, convective heat transfer region of a recovery boiler for different bullnose designs. The convective heat transfer region of the furnace was simulated by examining a zone that begins below the bullnose and ends at the economizer. Superheater tubes and a boiler bank were included as internal wall boundaries in the problem description. A variety of inlet velocity profiles and temperature profiles were used to determine the sensitivity of the results to chosen inlet conditions. Results from this work show that predicted temperature profiles and velocity profiles at the boiler bank and superheater heat transfer surfaces were not affected significantly by these inlet conditions. Two turbulence models were used, the traditional k-e model and an algebraic stress model. Differences in predicted results between turbulence models were minor. General features of the simulated results agree well with field measurements. Recirculation zones were located above the protruding edge of the bullnose and in the uppermost corner of the upper furnace cavity. The degree to which the bullnose protruded into the furnace had a significant effect on the size of recirculation above the bullnose. A smaller bullnose results in a smaller recirculation zone which results in smoother superheater tube temperature profiles.