摘要
循环流化床锅炉中二次风主要提供燃烧所需氧气并控制NOx生成,但是随着炉膛的大型化发展二次风作用减弱.采用Fluent6.2计算软件数值研究300MW循环流化床锅炉炉膛中二次风速度和风向对炉内颗粒速度和固体浓度的影响,分析炉内不同位置的颗粒速度和浓度的分布以及二次风穿透性规律.模拟结果表明,裤衩型循环流化床内中间的颗粒存在向下流动性,颗粒浓度在Z向截面上呈现不均匀分布,其形状类似是多个环核结构模型的结合.二次风显著提高炉膛上部颗粒浓度,能够优化炉内气体和颗粒流场分布,外侧二次风的穿透性好于内侧二次风的穿透性.模拟结果可以为大型循环流化床锅炉的设计和运行提供理论参考.
Secondary air plays very important role in combustion for oxygen supplement and NOx control in a circulation fluidized bed （CFB） furnace.However the distribution of secondary air in the furnace becomes worse as the furnace is enlarged.Numerical simulation was performed to study the impacts of secondary air in the furnace of a pant-leg 300 MW CFB boiler.The flow fields of solids velocity and concentration were computed at different secondary air injecting velocity and direction using Fluent6.2.The distributions of solids velocity and concentration were given and analyzed at different location and cross-section in the furnace.The penetrability of secondary air was also analyzed.The simulation shows that the solids flow goes down in the middle of the furnace,and the distribution of solids concentration in the Z cross-section is uneven,which is similar to a combination of several core-annular flows.The solids concentration in the top of furnace is higher with the one.The secondary air can optimize the gas and solids flow fields in the furnace.The penetration of outboard secondary air injection is better than that of the inboard one.The simulation results can be referenced in the design and operation for a large CFB boiler.
出处
《浙江大学学报（工学版）》
EI
CAS
CSCD
北大核心
2010年第4期743-749,共7页
Journal of Zhejiang University：Engineering Science
基金
国家科技支撑计划子课题资助项目(2006BAA03B02-08)
关键词
循环流化床锅炉
二次风
穿透性
circulation fluidized bed boiler
secondary air
penetrability
