Energies, Vol. 18, Pages 6046: Numerical Study on Thermal Deviation of High-Temperature Heating Surfaces in a Tangentially Fired Boiler Under Peak Load Regulation

Energies, Vol. 18, Pages 6046: Numerical Study on Thermal Deviation of High-Temperature Heating Surfaces in a Tangentially Fired Boiler Under Peak Load Regulation

Energies doi: 10.3390/en18226046

Authors:
Dianhong Yuan
Junfeng Kong
Bin Qin
Feng Pan
Weihao Duan
Jiahui Yang
Lei Deng

The inherent residual swirl at the furnace outlet of tangentially fired boilers induces severe thermal deviations on high-temperature heating surfaces. To reveal the evolutionary patterns of thermal deviation during peak regulation operation, this study employed a numerical method to analyze the thermal deviation characteristics of high-temperature heating surfaces in a 350 MW tangentially fired boiler under 12 operating conditions (covering 100%, 72%, 50%, and 28% loads). As the load decreases, the average absolute vorticity at the platen bottom plane also decreases. However, its decreasing rate is pretty slow compared with that of the load, indicating that the velocity deviation increases relatively. In addition, the flow field becomes more sensitive to the mill group operation mode. Correspondingly, the thermal deviations of the division platen superheater, rear platen superheater, finishing reheater, and finishing superheater all show an upward trend. When the load decreases from 100% to 28%, the average heat absorption deviations of the four heating surfaces increase to 3.48, 2.06, 1.27, and 1.99 times their original values, respectively. A comparison of the internal operating conditions under four loads shows that activating the lower-layer burners helps to reduce thermal deviation. This study proposes indicators for characterizing and analyzing the thermal deviation of high-temperature heating surfaces and provides general suggestions for the operation of tangentially fired boilers.