为提高现役的大量亚临界机组效率，加快煤电高质量发展，亟需开展对亚临界机组的提貭改造。根据热力学原理，提升蒸汽压力带来的效率收益明显低于提升蒸汽温度，为此，介绍一种亚临界机组600 ℃升温改造技术，在保持亚临界机组汽轮机进口蒸汽压力(16.7 MPa)不变的条件下，把汽轮机进口蒸汽汽温从537 ℃提升到600 ℃。具体改造实例为320 MW亚临界机组(纯凝无供热机组，背压4.9 kPa)在主、再热蒸汽温度升温至600 ℃后，其机组效率可达到现役超超临界机组水平，并大大提升了机组的(超)低负荷性能额定工况下供电煤耗低于290 g/(kW·h)。

In order to improve the efficiency of a large number of subcritical units in service and accelerate the high-quality development of coal-fired power plants, the retrofit technology of raising temperature to 600 ℃ for subcritical units was carried out. According to the thermodynamic principle, the efficiency benefit of increasing steam pressure is obviously lower than that of raising steam temperature. Therefore, the steam temperature at the inlet of steam turbine of subcritical unit is increased from 537 ℃ to 600 ℃ under the condition of keeping the steam pressure (16.7 MPa) at the inlet of subcritical unit unchanged. After the main and reheat steam temperature rises to 600 ℃, the unit efficiency of a 320 MW subcritical unit (pure condensing without heating unit, back pressure of 4.9 kPa) can reach the level of ultra supercritical unit in service, and greatly improve the (ultra) low load performance of the unit. Under the rated condition, the power supply coal consumption can reach below 290 g/(kW·h).