中文摘要：

低温烟气热能的高效梯级利用是火电厂节能减排的重要方向之一。本文结合某1000MW超临界机组，对常规低温省煤器烟气余热利用系统进行了热力学分析，发现该系统可使系统发电标准煤耗率降低2．50g·（kW·h）^-1，但熘分析发现，空气预热器拥耗散占输入堋的22．03％，多于锅炉排烟所携带的炯。为此，本文提出了集成SC02动力循环的火电厂低温烟气热能利用系统，旨在减少空气预热器中的炳耗散。对SC02动力循环参数进行了优化，在优化参数下该系统可以使发电标准煤耗率降低3．62g．（kW·h）^-1，进一步集成低温省煤器可使发电标准煤耗率降低达5．58g·（kW．h）^-1，最后采用炯分析结果解释了系统节能的本质原因。

英文摘要：

The efficient use of energy carried by low temperature flue-gas is a hot topic of energy saving in thermal power plant. The thermodynamic analyses on conventional low temperature economizer with a reference case of 1000 MW supercritical power plant were carried out. Results show that the standard coal consumption rate for power generation could be decreased by 2.50 g.（kW.h）^-1. However a big portion of exergy was destructed in air pre-heater, about 22.03% to the total exergy put into the air pre-heater, which is bigger than the exergy carried by the boiler exhaust. Therefore, a waste heat utilization system integrated with SCO2 power cycle was proposed in this paper, which is designed to decrease the exergy destruction in air pre-heater. Then parameters of SCO2 power cycle were optimized. The standard coal consumption rate for power generation could be decreased by 3.62 g-（kW-h）^-1 with optimal parameters. The standard coal consumption rate for power generation could be further decreased by 5.58 g.（kW.h）^-1 when low temperature economizer were also integrated. Finally the essential reason for the energy saving were revealed by exergy analysis.