提升管高度对循环流化床内气固流动及燃烧特性影响的CPFD模拟研究  

CPFD Simulation on Effect of Riser Height on Gas-solid Flow and Combustion Characteristics in a CFB

作　　者：韩诚良 张扬[1] 杨海瑞[1] 张海[1] HAN Chengliang;ZHANG Yang;YANG Hairui;ZHANG Hai(Key Laboratory for Thermal Science and Power Engineering of Ministry of Education,Department of Energy and Power Engineering,Tsinghua University,Beijing 100084,China)

机构地区：[1]清华大学能源与动力工程系,热科学与动力工程教育部重点实验室,北京100084

出　　处：《工程热物理学报》2024年第7期2033-2039,共7页Journal of Engineering Thermophysics

基　　金：国家自然科学基金委联合基金项目(No.U1710251);国家重点研发项目(No.2020YFB0606303)。

摘　　要：本文利用计算颗粒流体力学(CPFD)方法建立提升管高度(H_(riser))为10 m、20 m、30 m的循环流化床(CFB)模型,在低固体循环流率(Gs)条件下开展H_(riser)对床内气固流动及燃烧特性的影响作用研究。结果表明,H_(riser)对颗粒浓度及气体分布具有直接影响。随着轴向床高的增加,颗粒浓度逐渐降低。H_(riser)较大时,轴向床高超过15 m后,颗粒浓度和气体组分浓度基本保持稳定,说明超过15 m的提升管为燃料提供充足的停留时间,保证燃料燃尽。模拟也发现H_(riser)越高,床内下部床温与上部床温更加趋于一致,温度分布更加均匀,但是轴向床高达到15 m之后H_(riser)对于炉膛温度均匀性作用影响较少。在20 m和30 m提升管内气体组分浓度整体分布趋势接近。综合而言,设计CFB燃烧试验系统时,提升管最低高度应保持在15 m以上,以保证实验台中的燃烧与实际锅炉的相一致。In this paper,the effect of height of the riser,H_(riser),on gas-solid flow and combustion characteristics in the coal-fired circulating fluidized bed(CFB)was numerically studied by using computational particle fluid dynamics(CPFD),with H_(riser)of 10 m,20 m and 30 m respectively and under low solid circulation rates(G_(s)).The results show that H_(riser)directly impacts the axial particle and gas concentration distributions.As the axial bed height increases,the particle concentration gradually decreases.When H_(riser)is larger,the particle density and the concentrations of various gas species remain nearly unchanged after the axial bed height exceeds 15 m,indicating that H_(riser)of 15 m can provide sufficient residence time for the fuel to burn out.It was also found that as H_(riser)increases,the temperature of the lower bed is closer to that in the upper bed,and the entire temperature distribution is more uniform.However,after the axial bed height exceeds 15 m,H_(riser)barely influences the temperature uniformity.When the height exceeds 15 m,the concentrations of various gas species remain basically stable,indicating that the riser of more than 15 m.The overall distribution trends of the concentrations of various gas species in the 20 m and 30 m risers are close,Based on the simulation results,when designing CFB combustion test system,H_(riser)should be kept above 15 m to ensure the consistence between combustion in experimental system with that in a practical CFB boiler.

关 键 词：循环流化床 提升管高度 流动特性 燃烧特性 

分 类 号：TK16[动力工程及工程热物理—热能工程]