循环流化床锅炉掺烧污泥的炉内燃烧数值模拟研究

A Numerical Simulation of Co-Combustion of Sludge on a Circulating Fluidized Bed Boiler

针对1台1 036 t/h的循环流化床锅炉,基于Fluent数值模拟软件,模拟不同种类污泥及不同掺混比例下煤粉、城市污泥、工业污泥在CFB锅炉中的燃烧过程。结果表明:城市污泥与工业污泥在相同掺混比例下温度分布、烟气中氧气和二氧化碳浓度差别较小,采用循环流化床锅炉焚烧不同种类的污泥时,锅炉运行参数变化较小,城市污泥与工业污泥的燃烧特性相近;随着污泥掺混比例的增加,炉膛平均温度及二氧化碳浓度减小,氧气浓度增大,同时炉膛温度均随炉膛高度的增加而降低,稀相区温度分布较为均匀;随着污泥掺混比例的增加炉膛内燃料颗粒运动轨迹越来越混乱,左侧回旋圆圈逐渐消失,颗粒逐渐向右侧偏移。因此小比例掺烧污泥时对锅炉性能影响较小,采用循环流化床锅炉焚烧污泥不存在技术问题,可以顺利实施,但应注意污泥掺烧比例问题,应尽量避免大比例掺烧污泥。

Taking a 1 036 t/hcirculating fluidized bed boiler for example, numerical simula- tions of the combustion process are carried out at different types of sludge and different blend ratio under the coal, municipal sludge, industrial sludge in CFB boiler. The simulation results show that the difference of the temperature distribution, oxygen and carbon dioxide concen- tration in the flue gas of municipal sludge and industrial sludge at the same blending ratio is small. When using circulating fluidized bed boiler burning different kinds of sludge, small changes in boiler operating parameters, and the combustion characteristics of municipal sew- age sludge and industrial sludge is similar. With the increase in the proportion of sludge blending furnace average temperature and carbon dioxide concentration decreased and oxygen concentration increases, while the furnace temperature decreased with the increase of furnace height, temperature distribution of dilute phase region more uniform. With the increase in the proportion of sludge blending , fuel particle trajectories in the furnace more confusion, the left circumflex circle disappearing, the particles gradually shift to the right. Therefore, when blended with a small proportion of sludge has little effect on the boiler performance, and using circulating fluidized bed boiler burning sludge there is no technical problem, can be successfully implemented, but it should be attention to sludge blending ratio, should try to avoid a large proportion of blended sludge.