660MW机组超临界直流锅炉稳压吹管技术

Application of stable-pressure steam purging technology in 660 MW supercritical once-through boiler

结合660MW机组超临界直流锅炉稳压吹管的工程实践,从参数选择、吹管前机组调试重点、锅炉参数控制和靶板检验等方面进行了分析。由于差压吹管系数与实际值存在较大误差,应对过热器入口的实际吹管系数进行校核,保证实际吹管系数大于1;吹管前给水和凝结水系统应冲洗合格,加装临时补水管道,补水能力应大于900t/h;为防止受热面超温,升温升压过程中给水流量应大于630t/h,调节煤水比控制分离器出口蒸汽过热度在15℃以内。同时采取燃烧器下摆、增大上部二次风量、提高给水温度等辅助措施;检验靶板时差压吹管系数应大于1.4,靶板吹扫时间为5～10min,可保证检验结果真实可靠。

Based on the engineering practice of stable-pressure steam purging in 660 MW supercritical once-through boiler, the application was analyzed in four aspects including parameter selection, main commissioning activities prior to steam purging, boiler operation and target acceptance criteria. Considering the deviation between the pressure drop and the actual disturbance factor, the actual disturbance factor at the inlet of superheater should be checked to be greater than 1.0 ; Feed water and condensate pipes must be cleaned to meet the requirement of water quality before steam purging and install a temporary make-up pipe to ensure the make-up capacity greater than 900 t/h ; To avoid overheating on heating surface, the flow rate of feed water must be greater than 630 t/h during pressure raising and the degree of superheat at the outlet of separators should be within 15 ℃ by adjusting the ratio of coal to water. Other measures include downward tilting of burners, more upper secondary air and higher feed water temperature ; The pressure drop disturbance factor was recommended to be above 1.4 and duration of 5-10 minutes to achieve an effective and reliable steam purging.