Assuming steady state, constant bed temperature and constant tube thermal conductivity, the three-dimensional heat conduction equations were numerically solved It was found that the temperature distribution can be expressed as dimensionless temperature in terms of Froude number, particle to furnace diameter ratio, and local to total furnace height ratio The models for predicting the dimensionless wall temperature distribution and dimensionless mean wall temperature were also developed in this work Finally, the limits of common tube materials used as water wall tubes based on maximum allowable stress and oxidation criteria were also investigated