Numerical Simulation on Steam-Water Separator Performance Based on Population Balance Model

The performance of the moisture separator is simulated and analyzed by the Euler two fluid model with population balance model (PBM), and compared with the traditional single drop size calculation method. The traditional Euler two fluid model based on single drop size was used to calculate the drop size effects on the separator performance, and the drop size range of significant effect on the separator was determined. The PBM model was used to calculate the separation performance in the case of multiple drop sizes, and the drop size was divided into five groups with different drop diameters. The percentage of each group was given at the separator inlet. The results show : (1) With increasing drop size, the pressure drop of the separator first increases and then decreases, and the separation efficiency gradually increases and when the drop size is larger than 150 μm, the separation efficiency is close to 100%, therefore, when the PBM model is used, its drop size range can be calculated by single drop size method; (2) With the drop size distribution moving to the direction of large diameter, the resistance coefficient decreases, the separation efficiency increases, the PBM model is consistent with the mass weighting performance from the single drop size method, but the separation efficiency and resistance coefficient are larger. (3) Steady-state PBM model can realize simultaneous calculation with different drop sizes, calculation cost is slightly larger than the single drop size method, but can quickly get the separator performance under a drop size distribution; (4) The unsteady PBM model can automatically obtain a drop size distribution before entering the separator rotating vane, and solve the problem of drop size setting at the inlet of the separator.