Perspectives for 700 °C ultra-supercritical power generation: Thermal safety of high-temperature heating surfaces

Abstract

The advanced 700 °C ultra-supercritical (A-USC) power generation is the most important developing direction of power generation due to the highest efficiency and great potential for energy conservation. The heating surfaces will be more sensitive to metal temperature due to the narrow safety temperature allowance at higher steam parameter. The tube wall temperature is depended on heat transfer characteristics between flue gas and working fluid in tube. However, the tube wall temperature was usually calculated with decoupled method for predicting the energy flux between flue gas and working fluid. The accuracy of tube wall temperature by using this method is sufficient for 600 °C USC boiler design based on huge experience data of power plants. While for A-USC boiler, the accuracy of that was not sufficient due to the more sensitive of tube wall temperature on boiler safety operating. To address those issues, some perspectives are given: some experimental apparatus which combined combustion and heat transfer surfaces at 700 °C level of working fluid is needed to conduct heat transfer characteristics; the coupled heat transfer simulation method is essential for A-USC boiler design and operating; long-term testing verification of candidate surfaces is imperative for commercialization of A-USC technology.