CFB 锅炉炉内的物料平衡可以影响CFB 锅炉安全稳定高效运行,研究炉内的物料平衡有助于指导实际锅炉的运行。根据清华大学提出的成灰磨耗实验方法,获得了660 MW 超超临界CFB 锅炉燃用的3 种煤种的本征成灰特性数据。对该660 MW 超超临界CFB 锅炉的结构进行一定的简化,仅保留炉膛、分离器与回料阀等部分,利用一维小室模型,考虑颗粒磨耗、退档、颗粒分层等条件,对该CFB 锅炉回路的物料平衡进行了数值模拟。实验结果表明,3 种不同性质的煤样按一定比例掺烧有着较好的效果,可以满足CFB 锅炉物料平衡的要求;当炉内床压为5 000 ~7 000 Pa时,提高床压降可以增加物料在炉内的停留时间,对于中间粒径档(0.125 ~3.200 mm) 的颗粒,停留时间的增加效果较为明显;仅提高床压降对于增加炉膛上部稀相区颗粒密度的影响比较有限;在维持5 000 Pa 较低床压降下,优化煤样粒径分布对颗粒在炉内的停留时间影响较小,但对提高炉膛上部颗粒密度有着明显的提高作用。在优化给煤粒径分布后,该660 MW 超超临界CFB 锅炉的优化床压降为5 000 Pa,在较低的床压下也有着较好的运行效果,这可以降低实际电厂的风机电耗,让电厂更加节能。

The material balance in a CFB boiler can affect the safe,stable,and efficient operation of a CFB boiler.Studying the material balance in a furnace can guide the actual boiler operation.Based on the ash formation and attrition experimental method proposed by Tsinghua University,this paper obtained the intrinsic ash formation characteristics data of three coal types used in a 660 MW ultrasupercritical CFB boiler.The structure of this 660 MW ultra supercritical CFB boiler was simplified to some extent.Only the furnace,separator and recycling valve were retained.Considering the conditions of particle attrition,size reduction,and particle segregation,the material balance of the boiler circuit was numerically simulated with the one dimensional chamber model.The experimental results showed that blending three kinds of coal samples with different properties had a good effect and could meet the requirements of CFB boiler material balance.When the bed pressure was in the range of 5 000-7 000 Pa,increasing the bed pressure drop can increase the residence time of bed material,and the effect was more obvious especially when the particles were in the intermediate particle size range (0.125-3.2 mm).Increasing the bed pressure drop had a limited effect on increasing the particle concentration in the dilute phase of the upper furnace.With a low bed pressure drop of 5 000 Pa,optimizing the particle size distribution of the coal sample had a small effect on the residence time of the particles in the furnace,but it had a significant effect on increasing the particle concentration in the upper part of the furnace.After optimizing the particle size distribution of the coal,the optimized bed pressure drop of the 660 MW ultra supercritical CFB boiler was 5 000 Pa.The CFB boiler also had a good operation at 5 000 Pa bed pressure,which could reduce the power consumption of fans in actual power plant and make power plant become more energy saving

1 一维小室模型计算

    1.1 研究对象

    1.2 一维小室灰平衡

    1.3 分层模型

    1.4 磨耗与退档

    1.5 计算条件

2 结果与讨论

    2.1 成灰磨耗结果

    2.2 模型计算结果与讨论

    2.3 不同床压降下对物料平衡的影响

    2.4 不同给煤粒径分布对物料平衡的影响

3 结论