Application of a thermal model to a power plant reheater with irregular tube temperatures

A three-dimensional thermal model for the reheater of a utility boiler is applied to a 350 MWe power plant. The model permits the consideration of non-uniform steam flow inside the tubes, which can lead to excessive temperature and hence thermal stress in a part of these. Parametric calculations are performed to examine the influence of various empirical coefficients included in the model. Experimental on-line and off-line data will be obtained and will be introduced as boundary conditions or used to validate the model. The steam flow distribution inside the tubes will be considered uniform or non-uniform depending on the tube serpentine of the reheater. The results predicted by the model of the temperature of the tubes at the reheater outlet and the outlet steam temperature are satisfactorily compared with the experimental measurements. Moreover, the results predicted for the temperature of the gases in an intermediate section of the reheater are analysed and compared with the experimental results from off-line measurements.