石炭火力発電所ふく射ボイラにおける二次および三次過熱器の熱流束・温度評価に関する数値シミュレーション

抄録

Superheaters are essential components in a coal-fired power plant because they keep the highest tube wall temperature points in the radiant boiler. The pressurized steam flowing in the superheater tubes is heated via the thermal radiation and convection from the combustion gas. To prevent the bursting of superheater tubes caused by the thermal fatigue for stable and safe plant operation, precisely predicting complex heat transfer characteristics, and estimating the local temperature and heat flux of the superheater are necessary. In this study, a computational fluid dynamics model of the boiler and the second and third superheaters in a coal-fired power plant is developed using radiation model (DO model) and turbulence models (k-ε RNG model). In the second superheater installed near the burner, the influence of radiation from the combustion gas is strong, and the temperature and heat flux of the outermost tube are highest. In the third superheater, the tube wall temperature and heat flux becomes large in the upper and middle parts of the superheater, where the combustion gas flow velocity around the superheater is high, whereas those at the bottom of the superheater are significantly small due to the dead water region of the gas. Therefore, to consider the combustion gas flow is important for prediction of the heat transfer characteristics of the third superheater.