The combustion process of one 1000-MW ultra-supercritical double-tangential-circle boiler was numerically studied and the three-dimensional full-size structure of the boiler was full considered. The influences of primary and over-fire air velocity as well as the jet structure on NOx generation characteristics were examined. In addition, the NOx generation characteristics of the improved burner structure were compared with those of the original one. Numerical results show that there exist two inverse elliptical flow fields and temperature fields. Moreover, the NOx generation and distribution characteristics are related to the temperature field to a certain extent. For different burner jet structures and arrangements, NOx distribution curves of the horizontal cross section are all W-shaped, but the NOx generation and distribution performance are correspondingly different, while the NOx emission changes are unobvious for different design schemes of the boiler burner. When we arrange one layer of auxiliary air from the burner undersurface, the flow area of the primary coal powder jet is enlarged by 100% and the coal feeding is increased by 20%. As a result, the temperature around the burner zone rises significantly. However, when two layers of auxiliary air are adopted, the combustion characteristic is promoted and NOx generation increases slightly. Based on the arrangement of the burner in the ultrasupercritical boiler, NOx generation does not vary obviously at different boiler loads. To achieve a better scheme, numerical and experimental studies are both performed in this study, and identical results are obtained. The current results may provide a theoretical basis for burner design improvement.

In order to study the evolution process and hydraulic characteristics of pressurizer insurge in CPR1000 pressurized water reactor (PWR), the computational fluid dynamics (CFD) of three-dimensional unsteady heat transfer was used to capture the temperature and velocity fluctuation intensity of the mixing of the hot and cold. The results show that Realizable k–ε Turbulence Model combined with VOF multiphase heat transfer model can effectively predict the development trend of pressurizer insurge process. The small diameter pressurizer surge line of CPR1000 enhances the intensity of velocity fluctuation. From the essence of flow and heat transfer, it is concluded that buoyancy force can increase the degree of fluctuation and make an accelerated effect on the influx cold fluid. The electric heater inside the pressurizer should be arranged as far as possible in z<-0.45m and z>0.45m; it is beneficial to improve its harsh operating environment. This research can provide reference for the structural design of pressurizer and the layout optimization of the electric heater.

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