秸秆炭化烟气两级除尘装置设计及数值模拟

Design and numerical simulation of two-stage device for dust removal from flue gas of straw carbonization

为提高秸秆炭化烟气的除尘效率,在典型旋风分离器基础上,在排气管中增设回转拨指轮,构成两级除尘。利用SolidWorks和ANSYS ICEM软件对其建模和网格划分,在数值模拟软件FLUENT中采用RNG k-ε模型和RSM模型相结合的方法进行流场模拟,建立了流场理论模型。采用DPM模型对颗粒的分离效率进行模拟,测试在同一烟气进口速度(20 m/s)条件下,典型旋风分离器及不同回转转速(0、900、1 450、2 900r/min)下两级式除尘装置内部烟气流场的静压、切向速度、径向速度、轴向速度分布及不同粒径颗粒的分离效率。结果表明,与传统旋风除尘器相比,回转拨指轮对除尘器内的静压有较大的影响,且静压随转速的增大而增大;回转拨指轮转速对流场切向速度亦有较大的影响,随转速提高,切向速度增大,但对径向速度和轴向速度的影响较小;两级除尘及内部回转拨指轮转速对1μm颗粒收集无较大影响,但对于10μm以上的颗粒,可显著提高分离效率,且随转速增大分离效率有所提高,但不同转速对分离效率的影响差异不显著。

A two-stage dust removing system was designed by setting a finger roller in the exhaust cylinder of typical cyclone to improve the dedusting efficiency from flue gas of straw carbonization.The model of the system was established in SolidWorks and meshed with ANSYS ICEM.The flow field of the system was setup through simulation of the system with combination of RNG k-εmodel and RSM model.The particle separation efficiency was simulated with DPM model coupled of gas-solid two phase flow based on the Euler-Lagrange equation.The static pressure,tangential velocity,radial velocity,axial velocity distribution and the separation efficiency of different size particles of typical cyclone and the 2-stage dust removal system were obtained at inlet velocity of 20 m/s and finger roller rotation speed of 0 r/min,900 r/min,1 450 r/min and 2 900 r/min.The results showed that the rotation speed of the finger roller had a significant effect on static pressure of the dust collector and the static pressure increased with the increase of rotation speed compared with typical cyclone.The rotation speed of the finger roller had a significant influence on tangential velocity of the flow field.The tangential velocity increases with increase of the rotation speed with little effect on the radial velocity and axial velocity.Compared with typical cyclone,the 2-stage dust removing system and its rotation speed had little influence on separation of dust particles of diameter less than 1μm.However,they had significant effects on separating dust particles of diameter larger than 10μm,and the separating efficiency increased with the increase of rotation speed of the roller.The difference of separation efficiency of different rotation speed was not significant.It will provide reference for designing and optimizing the structure of dust removal device with high efficiency.