Modeling and analysis of flow instability of the water wall in a 600 MW supercritical W-shaped boiler

In order to further expand the study on flow instability of supercritical boiler, a general model was developed applying time-domain method. To improve the generality of this model, non-uniform heat flux distribution and a variety of geometric structures and tube types were considered. Calculation results were compared with numerical and experimental result respectively. According to the comparisons, the model is proved to be reasonable and accurate for practical engineering application. Based on the validated model, flow instability of the water wall in a 600 MW supercritical W-shaped boiler at subcritical and supercritical pressures was numerically analyzed. Pressure drop versus mass flow rate characteristic curves were obtained. Effects of parameters, including inlet pressure, inlet mass flow rate, inlet and outlet pressure drop coefficient, on dynamic instability were analyzed. Results show that no Ledinegg instability occurs at the operating conditions. Parametric effects on dynamic instability at supercritical pressure behave the same compared to that at subcritical pressure. With an increase of inlet mass flow rate and inlet pressure, stability of the boiler is enhanced. With decreasing inlet pressure drop coefficient and increasing outlet pressure drop coefficient, stability of the boiler is reduced.