床压降对循环床锅炉燃烧特性影响的建模研究

"低床压降"是第二代节能型循环流化床锅炉的核心理念。以75 t/h循环流化床锅炉为研究对象,建立其静态数学模型,模型在"三区环核"的基础上以二次风穿透深度为界进一步将核心区分为贫氧区和富氧区;给出了在给定粒度分布下各区物料浓度随床压降和运行风速两个主导因素变化的函数,该函数由试验数据整理拟合得出。通过数值计算,分析了床压降对贫氧区体积、炉内温度、燃烧效率和燃烧份额分布的影响。模型计算结果与现场收集的数据有较好的吻合,为低床压降循环流化床锅炉的性能预测提供理论支持。

Modeling of Influence of Pressure Drop on Combustion Behaviors of CFB Boiler

‘Low bed-pressure-drop’ is the core theory of the second-generation energy-saving CFB boiler.A static mathematical model is established by taking a 75t/h CFB boiler as its object.Based on ‘Three zones core-annular structure’,the core area is divided into oxygen-poor region and oxygen-rich region according to the secondary air penetration depth in this model.Under a given particle size distribution in bed,the solid suspension density of each zone in furnace is a function of both bed pressure drop and fluidized velocity,and this function is obtained by fitting experimental data.Through numerical calculation,the influence of bed pressure drop on the volume of oxygen-poor region,furnace temperature,combustion fraction distribution and combustion efficiency is analyzed.The results agree well with the actual data,it can provide some theoretical support for the performance prediction of low bed pressure drop CFB boiler.