基于离散元方法的高碱煤灰沉积过程数值模拟研究

针对锅炉燃用高碱煤产生的受热面积灰问题，以流化床锅炉对流过热器为研究对象，采用离散元方法（discrete element method）建立黏性颗粒碰撞黏附模型，对过热器对流受热面的积灰过程进行数值模拟。分别研究了烟气流速、颗粒粒径、烟气温度以及壁面温度对积灰特性的影响规律。模拟结果表明：烟气流速增大、颗粒粒径减小会导致颗粒的碰撞率上升、捕集率下降；烟气温度和壁面温度提升时，颗粒表面能上升，导致颗粒捕集率上升，且壁面温度的影响更为显著；不同工况下最大积灰厚度、沉积物形状变化较小。

Numerical simulation research of high-alkali coal ash deposition process based on discrete element method

Burning high-alkali coal causes ash deposition on heat transfer surface. To visualize the deposit growth process, the numerical simulation of fouling process was carried out on fluidized-bed boiler convection super heater using sticky particle collision adhesion model based on discrete element method. The influences of gas velocity, particle diameter, gas temperature and wall temperature to ash deposition characteristics were studied and compared with existing research results. The simulation results indicated that the collision efficiency increased and capture efficiency decreased with the increase of gas velocity and the decrease of particle diameter. The increase of particle surface energy caused by the increase of gas and wall temperature led to the increase of capture efficiency while the influence of wall temperature was more obvious. The maximum deposition thickness and the shape of deposition under different working conditions have little change.