超临界670MW机组供热优化与再热器改造技术研究OA

In response to the national"dual carbon"goals and the policy requirements of"triple-reform linkage"for coal-fired power plants,aimed at the problems existing in the 67MW supercritical unit,such as insufficient heating capacity,poor operational economy and the peeling of oxide scale in the boiler reheater,this paper makes a systematic analysis focusing on heating optimization and boiler reheater retrofitting.In terms of heating optimization,four heating schemes,namely furnace-side cold reheat extraction,furnace-side hot reheat extraction,steam-to-steam heat exchange,and high backpressure small turbine driving,are comparatively analyzed,and the furnace-side cold reheat extraction scheme is finally determined as the optimal implementation scheme.This scheme enables stable operation at 47.7%-100%rated load,with adjustable high-pressure heating output of 50-340 t/h and medium-pressure heating output of 0-340 t/h.After retrofitting,the weighted average coal-saving rate reaches 20.28 g/kWh.As for reheater retrofitting,the technical route of"flexible heating surface,material upgrading and structural optimization"is adopted.The seamless switching between pure condensation and heating conditions is achieved by adding a low-temperature reheater,and the tubes of the final-stage reheater are upgraded with reduced diameters,which effectively solves the problem of the oxide scale shedding and simultaneously meets the requirement of 340 t/h high-pressure extraction steam.The heating capacity of the unit is significantly enhanced after the renovation,and the safety and economy of boiler operation are improved.The research results can provide technical references for heating retrofitting and reheater optimization of similar coal-fired power units.