According to the structural character of an ultra-supercritical 1 000 MW unit boiler with high frequency and broad regulation load

the water system can be equivalent to a network system consisting of flow circuits

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

momentum conservation equation and energy conservation equation

the hydrodynamic calculation model of water wall of the ultra-supercritical vertical tube coils boiler is established. By using the Newton's chord cutting method

the nonlinear model is solved

and the mass flux distribution

outlet vapor temperatures and metal temperatures at BMCR

75%THA and 30%THA load are obtained. The results show that

the temperature of the wall and fin is within the allowable range of materials and the water wall of the ultra-supercritical vertical tube coils boiler is safe and reliable in hydrodynamic aspect. The water wall will not flow instability at 30% THA load.