关键词: 计算流体力学, 数值模拟, 气液两相流, 除雾效率, 雾滴运动, 雾滴捕集特性

Abstract: In order to improve demisting efficiency of baffle demisters for different droplets and reduce droplet entrainment in the wet flue gas desulfurization (WFGD) system, the computational fluid dynamics (CFD) method was used to simulate numerically the two phase flow of gas and liquid in baffle demister in the WFGD system. By changing the structural parameters and operating parameters of the baffle demister, such as plate spacing, blade-shape and gas-velocity, demisting efficiency and droplets' separation efficiency of different sizes were investigated. The movement behavior and deposition of droplets with different sizes were obtained. The removal efficiency of droplets less than 10 μm would show irregular fluctuations if flow rate was increasing, but almost remained unchanged with increasing plate spacing. In that case removal efficiency was not affected by blade shape. The removal efficiency of droplets over 16.3 μm would increase with increasing flow rate, and decreased significantly with increasing plate spacing. The demisting efficiency of trapezoidal plates was greater than that of triangle plates with plate spacing of 38 mm, and the difference in demisting performance for these two plates was not significant in smaller plate spacing. Removal of the droplets less than 20 μm required higher airflow uniformity at lower gas flow rate. Increased airflow disturbance was in favor of small droplets' collision-coalescence when gas flow rate was less than 3 m·s^-1, and increased airflow disturbance was not conducive to small droplets' collision-coalescence when gas flow rate was over 3 m·s^-1.

Key words: CFD, numerical simulation, gas-liquid flow, demister efficiency, droplet motion, deposition