Steam temperature regulation characteristics in a flexible ultra-supercritical boiler with a double reheat cycle based on a cell model

Abstract A cell model of double reheat boilers that simplifies thermodynamic calculation was developed to predict the steam temperature characteristics of a flexible 660 MW ultra-supercritical double reheat tower-type boiler. By virtue of the model, the characteristics of steam temperatures under different loads were obtained and the effects of swinging burners, regulating gas dampers, and gas recirculation on the steam temperatures were analyzed based on the 660 MW double reheat boiler. The results showed that the main and reheat steam temperatures had radiation and convective characteristics, respectively. The main steam temperature was found to be more sensitive to flue gas recirculation, whereas reheat steam temperatures were more sensitive to gas damper regulation. The average regulation ranges of secondary reheat steam temperatures were ±32.7 °C and ±8.1 °C for the maximum ranges of dampers and gas recirculation, respectively. This study provided further insights into the steam temperature regulation characteristics of double reheat boilers.