The technical characteristics of double-reheat system are proposed and the key technologies for double-reheat boiler are analysed in this paper. The thermal efficiency of the unit could be improved by the applying of double-reheat system and CO2 emission could also be reduced. The Ferrite Alloy and Austenite Alloy which are mature now can meet the requirements for safety operation of double-reheat supercritical units well. Although the structure of boiler, turbine and thermodynamic system will be complicated, the double-reheat technology is a promising method to improve thermal efficiency before the nickel-based materials technology is maturely developed.% 本文指出典型二次再热系统的技术特点，并对二次再热锅炉的关键技术进行分析。二次再热技术可有效地提高火力发电机组的热效率并降低单位发电量CO2排放，且目前技术成熟的铁素体合金材料和奥氏体合金材料能够满足二次再热超临界机组的安全要求。虽然二次再热会使得锅炉、汽轮机和热力系统的结构变得复杂，但是，在我国700℃等级镍基材料解决之前，二次再热技术是提高火力发电机组热效率切实可行的有效手段。
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