600MW超临界机组锅炉轴流风机并列与过程控制技术

The Parallel and Process Control Technology of Axial Flow Fans in a 600MW Supercritical Boiler

通过开展600MW超临界机组锅炉风机并列试验,研究一次风机并列过程中失速原因,结合轴流风机"驼峰型"失速线与机组锅炉最低稳燃需求,在充分考虑风机并列过程中风压波动的基础上,采用失速裕度定量分析了风机失速风险,计算获得风机并列最佳工作点下风压上、下限值。同时根据联合风机、送风机、一次风机运行特点,阐述3种风机不同并列方法,重点研究一次风系统母管制设计方式对风机并列的影响。试验结果表明:风机工作点的风压与风量共同决定了风机失速裕度,风机失速裕度越大,抵抗系统干扰能力越强。结合机组负荷、入炉煤质以及一次风系统布置特点,选择合适的一次风压,准确计算一次风机动叶开度目标值以及预先隔离并入风机的系统,是一次风机并列操作的3个关键因素,可有效降低系统附加阻力及风压波动对风机并列的影响。此外针对一次风机风压直接作用于瞬时入炉燃料量,其并列过程显著影响炉内燃烧稳定性,通过多组试验总结并制定一次风机并列标准流程与步序,显著提高一次风机并列过程的成功率与安全性,最大限度缩短并风机的时间,同时减少对运行人员操作水平的依赖,降低因运行人员个体差异等因素造成的炉膛压力大幅波动甚至锅炉灭火的风险。

Through several groups of fan parallel operation tests in a 600 MW supercritical boiler,the stall reasons of axial primary air fan in parallel were studied.Based on the characte ri stic s of stall line of axial fl ow fa n and minimum steady combustion load,the application of the stall margin offered quantitative analysis to stall probability.The best working point of fan parallel and the upper and lower limits of air pressure were determined.According to the operation characteristics of induced draft fan(IDF),forced draft fan(FDF)and primary fan(PAF),three different parallel methods of fans were expounded.The results indicated that the stall margin of the fan was determined by the air pressure and air flow at the working point.The higher the stall margin,the stronger the ability to resist system interference had.Combined with the unit load,coal quality and layout characteristics of primary air system,there were three key factors for parallel operation of PAF,including the appropriate primary air pressure,the accurate target value of blade opening and the system isolation of the incorporated fan in advance.Due to the influence of PAF’s air pressure,the parallel process of PAF had great interference on combustion stability in furnace.Through several groups of tests,the parallel standard process and sequence of PAF were summarized,which significantly improved the success rate and safety,shortened the time of fan parallel,reduced the dependence on the operation of operators,decreased the large fluctuation of furnace pressure and the boiler outfire caused by individual differences in operation.