Numerical Simulation of the Erosion Characteristics and Structure Optimization of Elbows Connection for Gas-solid Flow

In pulverized coal power plants, the flow in flue ducts and pulverized coal piping is gas-solid flow with high Reynolds number. The flow and erosion characteristics in the pipelines influence the performance of flue and pulverized coal system. Continuous layout of elbows is often necessary due to the restriction of outer space. And connection length between elbows is short at this point. The interaction between two elbows can influence the flow field and erosion pattern in elbows connection structure. In present paper, discrete phase model (DPM) model and Tulsa Erosion/ Corrosion Research Center (E/CRC) erosion model were adopted to simulate the flow and erosion characteristics in two kinds of elbows connection. The flow field, erosion distribution and the most eroded position in these two elbows connection were obtained. Moreover, the influence of connection length on erosion rate was also analyzed. Structure optimization was conducted based on the erosion pattern of pipe wall. Results suggest that for Z-type elbows connection, L/D=2 can yield small erosion rate. But for II-type elbows connection, direct connection (L/D=0) is most recommended.