Study on the safety of a magnetic strainer at the deaerator outlet under two-phase and large-scale flow fields

Abstract

Iron oxide corrosion exists in the deaerator, which causes serious damage to the water supply system. To absorb iron oxide impurities for the feed water quality, a magnetic strainer device has been designed at the deaerator outlet. In order to ensure the safe and stable operation of the deaerator, the computational fluid dynamics (CFD) method was used in this work to analyze the impact of complex outlet conditions on the gas-liquid two-phase flow field, pressure field, and structural safety within a deaerator. After the strainer is installed, turbulent kinetic energy (TKE) and turbulence intensity (TI) are not monotonically changing throughout strainer region and depend on the local flow state and geometry. TI relies more on turbulence disturbance and geometry. The overall flow near the strainer is accelerated, and the dimensionless velocity in the shear layer on both sides of the strainer center bracket increases by a maximum of 153.44%. Stable vortices and complex secondary vortices are formed near the strainer. The overall eddy is more fragmented, and eddy dissipation is prone to occur in the outlet region. However, this does not cause additional large turbulence losses. The impact of the strainer on the static pressure loss of the entire deaerator is very limited, and the reduction in static pressure difference does not exceed 0.04%. Finally, suggestions are made for the structural improvement and maintenance of the strainer based on the simulation results, which provide a reference for further safe and stable application of the deaerator magnetic strainer.