摘要
良好的一次风布风均匀性是保证循环流化床(CFB)锅炉床内流化质量的关键。针对某在役135MW CFB锅炉在运行中出现布风均匀性不佳而导致床内流化质量变差的问题,以该锅炉一次风布风系统为例对其布风不均产生原因和改造措施进行了数值模拟研究。结果表明:在梯形风室内形成了强烈的纵向涡流是造成布风不均的主要原因,而且由传统方法设计的均匀送风管中各支管风量不均加剧了纵向涡流对均匀布风的不利影响。由此提出了在风室内靠近进风口处装设导流锥使风室内纵向涡流转为横向涡流,同时在风量较大送风支管内装设节流圈,使各支管风量分配均匀,从而达到改造的目的。模拟结果表明:该方案可通过优化风室内气流组织,使锅炉一次风系统布风均匀性得到明显改善,而且简便易行,不明显增大一次风系统阻力。对CFB锅炉改善一次风布风均匀性从而提高床内流化质量具有借鉴意义。
A uniform air distribution in primary air system is the prerequisite of a favorable fluidization in the bed of circulating fluidized bed (CFB)boilers.In this paper,based on an in-service 135MW CFB boiler that is disturbed in operation by the nonuniform primary air distribution,the distributing uniformity of the primary air flux in air caps was studied with numerical method to clarify the reason and troubleshooting for such disturbance.The results indicate that the uneven air distribution is mainly caused by the intense swirling flow occurred in the longitudinal cross-section of the trapezoidal primary chamber.Meanwhile,the unequal flux distribution among the branch pipes for inflow air intensifies the nonuniform flux distribution in air caps because it gives rise to a stronger longitudinal swirling flow. Accordingly,a retrofit scheme is proposed for improving the uniformity of air distribution, which includes installing triangular pyramid distributor in the primary chamber near the air inlets to deflect the swirling flow in chambers from longitudinal direction to transversal one, and placing throttle orifice in the inlet pipes to balance the air flux in each branch pipe.The numerical simulation results show that the proposed scheme can better the uniform air distribution of the primary air system obviously through the optimization of the flow in the primary chamber.Meanwhile,the retrofit scheme is convenient to apply in an in-service CFB boiler,and the increase of the flow resistance of primary air is neglectable.It provides a useful guidance for those CFB boilers encountering the disturbance of an unacceptable fluidization quality in beds.
作者
马有福
王凡
袁益超
吕俊复
王子睿
MA Youfu;WANG Fan;YUAN Yichao;LYU Junfu;WANG Zirui(School of Energy and Power Engineering,University of Shanghai for Science and Technology, Shanghai 200093,China;Key Laboratory for Thermal Science and Power Engineering of Ministry of Education,Tsinghua University,Beijing 100084,China)
出处
《锅炉技术》
北大核心
2018年第6期35-41,共7页
Boiler Technology
基金
国家重点研发计划项目(2016YFB0600203)
关键词
循环流化床锅炉
布风均匀性
一次风室
流场优化
Circulating Fluidized Bed boiler
uniform air distribution
primary chamber
flow optimization
