高温超超临界二次再热机组中,经过二次再热削弱了热力系统回热的效果,同时增大了汽轮机抽汽过热度.本文采用回热汽轮机优化高温超超临界二次再热机组回热系统.以外置串联式蒸汽冷却器作对比,分别建立了外置串联式蒸汽冷却器和回热汽轮机的计算模型,实例计算了二者对常规超超临界机组及高温超超临界二次再热机组热力系统热经济性的影响.结果表明:应用回热汽轮机后汽轮机效率大于原热力系统的汽轮机效率;按照目前小汽轮机内效率90％为参考,当作为高温超超临界二次再热机组第5、6级加热器汽源时,可使发电厂标准煤耗降低0.633 g/(kW·h),当作为常规超超临界再热机组除氧器汽源时,可使汽轮机效率提高约0.25％,标准煤耗降低约0.689 g/(kW·h);相比于设置蒸汽冷却器,利用回热汽轮机能够更加合理、充分地利用抽汽过热度,能够更大程度地提高回热系统热经济性,节能潜力较大.%In the high temperature ultra supercritical double-reheat units, the heat recovery effect of the regenerative heat system is weakened after twice reheat, and the superheat degree of the extraction steam is also increased. To solve this problem, this paper applies heat recovery steam turbine to optimize the heat regenerative system of the high temperature ultra supercritical double-reheat unit. Moreover, by taking the externally arranged cascade steam cooler as the comparison, the calculation model for the externally arranged steam cooler and the heat recovery steam turbine were established respectively. The influence of the heat recovery steam turbine on thermal economy of the the conventional ultra supercritical units and high temperature ultra supercritical double-reheat units was studied. The results show that, applying the heat recovery steam turbine could improve the efficiency of the original steam turbine. According to the fact that the present inner efficiency of the heat recovery steam turbine is 90％, the standard coal consumption of the unit could be reduced by about 0.633 g/(kW·h) when using the heat recovery steam turbines's extraction and exhaust as the steam supply of the 5th and 6th heater. The efficiency of the original steam turbine could be enhanced by about 0.25％ and the standard coal consumption of the unit could be reduced byabout 0.689 g/(kW?h) when using the heat recovery steam turbine's extraction and exhaust as the steam supply of the deaerator. Compared with setting externally arranged steam cooler, applying the heat recovery steam turbine can make full use of the extraction steam's superheat and further improve the economy of the thermodynamic system, which has huge potential of energy conservation.
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