In order to explore the technical paths to improve the flexibility of fire engine group and enhance consumptive capacity of wind energy and other new energies

water cycle safety calculation and analysis was carried out for natural circulation boiler of Huaneng Dandong Power Plant

under deep peak load regulation. According to the structural characteristics of water wall

the water wall system can be regarded as a network system consisting of circuits

pressure grids and connecting tubes. On the basis of the mass

momentum and energy conservations and some supplementary equations

the mathematical model for predicting the profile of water wall flow rate and temperature in a complex flow network system was established. Through directly solving the nonlinear flow balance equations and pressure drop balance equations

the hydrodynamic parameters of the subcritical pressure natural circulation boiler under deep peak load regulation condition were obtained. The results show that

under deep peak load regulation condition with 25%THA load

the circulation ratio is larger than the limit circulation ratio

which satisfies the requirements for boiler safety operation and has enough safety margin. The mass flux distribution and circulation flow rate in the boiler water wall are reasonable

the flow distribution in water loops of four walls is uniform

and the metal temperature meets the demands of material strength and antioxidation. On this basis

flow instability and stagnation will not occur at 25%THA load.