A Coupled Model for Predicting the Tube Temperature of Platen Superheater of Coal-fired Boiler

Overheating of boiler heating surface seriously affects the safe operation of power plant. The tube temperature of boiler heating surfaces is affected by both the gas side heat transfer and steam heat absorption. Thus, this paper presented a coupled heat transfer calculation model in which the combustion and heat transfer of gas flow was simulated by 3D CFD model; while the steam flow in the tubes was simulated by a 1D Flownex model. The two models were coupled by exchanging the data of boiler heating surface heat flux and the steam temperature in the tubes. This coupled heat transfer model integrated the simulation of gas flow in the furnace and the steam flow in the heat exchanger tubes, and thereby can accurately consider the impacts of the heat transfer and steam flow deviations on the tube temperature. This coupled heat transfer model was applied to a 600 MW supercritical boiler to predict the heat transfer and tube temperature distribution of its platen superheater. The results show that the predicted results of tube temperature at different boiler loads are in good agreement with the measurements.