水平管段高压超浓相煤粉输送特性的数值模拟

Numerical Simulation on Pneumatic Conveying of Dense Phase Pulverized Coal in Horizontal Pipe at High Pressure

在充分考虑气固两相相互作用的基础上,利用修正后的κ-ε湍流模型对以CO2为输送介质的高压超浓相煤粉气力输送进行了数值模拟.对于固相体积分数高达25%的高压超浓相煤粉气力输送,采用该模型模拟一体化管道(垂直管、弯管、水平管连接在一起),获得了水平管段中不同粒径的颗粒在截面上的速度分布、浓度分布,以及不同表观气速下水平管段中固相的径向浓度分布.模拟结果表明,在相同的输送条件下,大粒径煤粉的速度较低,更容易在水平管道沉积;煤粉粒径相同时,表观气速较大的颗粒在沉积区的浓度分布较小.将模拟结果与相同试验条件下的水平管电容层析成像(ECT)结果进行了对比,验证了本文模拟结果的正确性.

The numerical simulation on the pneumatic transmission of ultra-high-pressure dense phase pulverized coal with CO2 as the medium was performed by the modified κ-ε turbulence model.In the model,the turbulence interaction between gas and solid particle is considered for the pneumatic conveying of the pulverized coal whose particulate phase concentration is up to 25%.The model was applied to simulate the pneumatic transmission in an integration pipe including a vertical pipe,an elbow pipe,and a horizontal pipe.The velocity and concentration distributions of different size particles on cross sections in a horizontal pipe,and the radial concentration distribution of solid particles at different superficial gas velocities in a horizontal pipe were obtained.The simulation results show that the pulverized coal with larger particle size will deposit more easily in the horizontal pipe under the same transport conditions.The concentration distribution in the sedimentary area is smaller at the same size particle and the greater superficial gas velocity.The simulation results are in reasonably good agreement with the experimental data achieved by ECT imaging.