二次再热超超临界机组分析

Exergy Analysis on Ultra Supercritical Power Unit with Double Reheat

二次再热是超超临界燃煤发电机组节能减排重要方向。以我国首台二次再热机组为对象,依据热力学分析法,建立了热力系统分析的数学模型,研究了该超超临界机组及主要部件的效率和损失,讨论了负荷变化的影响。结果表明:二次再热机组TMCR工况下效率为45.9%,高于同等级的一次再热机组,其中锅炉效率为55.3%,汽轮机效率为88.1%。在机组损失分布中,锅炉损率最大,占机组的84.1%,其中以燃烧损失和传热损失为主。对于回热系统,高压加热器效率高于低压加热器。变负荷时,随着负荷的增加,锅炉和回热系统效率有所提高,同时锅炉损率有所降低,汽轮机损率有所升高。

Ultra Supercritical Power Unit with Double Reheat is an important direction of energy saving and emission reduction.Based on the thermodynamics of exergy analysis method,the mathematical model for exergy analysis of thermal power system on domestic Ultra Supercritical Power Unit with Double Reheat was established,and exergy efficiencies and exergy losses of the main components of the power unit were calculated by this model.The results indicate that the exergy efficiency of the power cycle is 45.9%,which is above the same level of the unit with single reheat,under the condition of TMCR.Exergy efficiency of the boiler is about 55.3%,which accounts for 84.1% of the whole exergy losses,mainly consisting of the losses of combustion and heat transfer losses,and exergy efficiency of the steam turbine is 88.1%.In addition,for the heat recovery system,exergy efficiencies of low pressure heaters are lower than those of high pressure heaters.When the loads are increasing,exergy efficiency of the boiler,exergy efficiencies of regenerative heaters and the exergy loss ratio of the steam turbine are increasing,however the exergy loss ratio of the boiler is decreasing.