Numerical simulation on metal temperature and heat flux of the superheater in a coal-fired thermal power plant boiler

The superheater is a critical component in a coal-fired power plant because it sustains the highest tube wall (metal) temperature point in the boiler. The steam flowing in the superheater tubes is heated by thermal radiation and convection from the combustion gas in the radiant zone. To prevent melting and bursting of the tubes and to ensure normal plant operation and maintenance, accurately predicting complex heat transfer characteristics, estimating local temperature, and assessing the heat flux of the superheater are all essential. In this study, a computational fluid dynamics model of the boiler and superheater is developed using radiation and turbulence models. The local metal temperature and heat flux of the superheater are evaluated by calculating the heat exchanged between the combustion gas flow and steam flow in the tubes. The calculated values of the steam outlet temperature accurately reproduce the values measured using the equipment in the plant, and thermal radiation was confirmed to be dominant in the boiler. In addition, it was found that the heat flux of the outermost heat transfer tube, which receives the most thermal radiation, was more than 11-15% higher than those of the other inner tubes.