摘要
以超低热值煤泥为主要燃料的循环流化床锅炉燃烧时,会产生大量飞灰,不合理的U型惯性分离器结构和气动力学参数选择或造成分离后的粗灰集聚于U型惯性分离器底部,使得返料通道堵灰以及结焦问题高频发生;或导致该分离器分离效果低下,增加后级旋风分离器的负担,造成锅炉除尘效率降低。为了提高U型分离器的分离效果,采用计算流体力学FLUENT软件,建立对应的气固两ENREF 1相流模型,颗粒相采用拉格朗日方法,选择相间耦合随机轨道模型,气相湍流模型选择κ-ε模型,模拟了不同挡板深度以及不同质量流量对U型分离器分离效果的影响,并计算出不同挡板深度和不同质量流量时U型分离器的分离效率。计算结果表明,所用方法较好的模拟了U型分离器内固体颗粒的运动状态,颗粒的分离效率并不是随挡板深度或质量流量的增加而增加,而是在一定范围内变化。研究结果在一定程度上对U型分离器的结构优化提供了依据。
When the ultra-low calorific value coal sludge is used as the main fuel in CFB boiler,a large amount of fly ash will be produced undoubtedly. and the unreasonable U-shaped inertial separator structure and aerodynamic parameters will cause the coarse ash to be concentrated at the bottom of the U-shaped inertial separator,which will cause the ash blocking and coking problems in the return channel to occur frequently. The separation efficiency of the separator is low,and the burden of the latter stage cyclone is increased,resulting in the reduction of the dust removal efficiency of the boiler. In order to investigate the paths to improve the separation effect of U-shaped separator,the computational fluid dynamics of FLUENT software is used with corresponding air-solid two phase flow model being set up as the Lagrange method being used particle phase,the k-ε turbulent model being chosen for air phase,The effects of different baffle depth and mass flow rate on the separation efficiency of U separator were simulated. The separation efficiency of U separator is calculated when different baffle depth and mass flow rate are calculated. The results show that the method can simulate the movement of solid particles in U-shaped separator well. The separation efficiency of particles does not increase with the increase of baffle depth or mass flow rate,but changes within a certain range. The research results provide a basis for optimizing the structure of U separator to a certain extent.
引文
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