引风机前后烟道气流扰动问题研究

Study on Flue Gas Disturbance in the Front and Back of Induced Draft Fan

燃煤机组烟道的结构和布置型式决定了气流的流场分布和烟道系统的阻力,烟道设计不合理会影响相关设备的运行。某660MW机组B侧引风机在高负荷下振动超标,气流产生异声,通过振动测试分析得出风机运行状况无异常,引风机振动是由入口烟道和出口烟道内存在气流扰动造成的。采用计算流体力学(Computational Fluid Dynamics,CFD)软件对电除尘器到引风机段烟道、引风机到脱硫入口段烟道进行模拟分析,得出引风机入口和出口气流扰动是引起引风机运行振动并产生异声的原因并提出优化方案。优化实施后,引风机振动值控制在安全运行范围内,异声消除,烟道阻力降低249 Pa。本次改造保证设备的正常运行,降低了运行能耗。

The structure and layout of flue of coal-fired units determine the distribution of airflow field and the resistance of flue system.The improper design of flue will affect the operation of related equipment.The vibration of B-side induced draft fan of a 660 MW unit exceeds the standard under high load and the airflow produces abnormal sound.Through vibration test and analysis,it is concluded that the fan is in good condition.The vibration of induced draft fan is caused by the disturbance of airflow in the inlet and outlet flues.Computational fluid dynamics software is used to simulate and analyze the flue ducts from electrostatic precipitation to induced draft fan section and from induced draft fan to desulfurization inlet section.It is concluded that the disturbance of air flow at the inlet and outlet of induced draft fan is the cause of vibration and abnormal sound.Relevant optimization scheme is proposed.After optimization,the vibration and abnormal sound problems are solved while the flue resistance is reduced by 249 Pa.The modification ensures the normal operation of the equipment and reduces the energy consumption.