660MW二次再热机组回热系统节能减排研究

Energy Conservation and Emission Reduction of Regenerative System of a 660MW Unit with Double Reheat

以某在建660MW超临界二次再热机组回热加热系统为对象,采用损分布矩阵方程和单耗理论分析了不同负荷下各加热器效率、损和附加煤耗的分布特征,依据《火电厂大气污染物排放标准》讨论了附加煤耗引起的污染物排放状况。研究表明:该二次再热机组高加侧总损和总附加煤耗均高于低加侧,3号高加引起的能耗和污染物排放量最大,2号和4号高加外置蒸汽冷却器效果明显使其经济性显著。总体上,二次再热机组高加侧的效率高于一次再热机组,而低加侧恰相反。受蒸汽参数不同和结构变化的影响,同负荷下两种机组的损和附加煤耗分布的差异较大。100%负荷下,二次再热机组回热系统的附加煤耗及其引起的CO2、SO2、NOx和碳粉尘排放量分别为3.35g/(k W·h)、38 041.35t/a、1 045.03t/a、579.89t/a、10 515.50t/a。

Based on the matrix model of exergy loss distribution and unit consumption analysis, exergy efficiency, exergy losses and additional coal consumption of the regenerative system in a 660MW supercritical power unit with double reheat were investigated, and the reasons for the distribution of several performance indicators were examined. According to Emission Standard of Air Pollutants for Thermal Power Plants, the discharging quantity of pollutants caused by additional coal consumption was explored. The results indicate that,for the unit with double reheat, total exergy losses and additional coal consumptions in HP heaters are higher than those in LP heaters, and No. 3 HP heater exhibits the largest energy consumption and emissions, whereas No. 2 and No. 4 heaters show significant energy saving potential by arranging out steam coolers. Exergy efficiencies of HP heaters in the unit with double reheat are generally higher than those in the unit with single reheat, and exergy efficiencies of LP heater have an adverse variation. The distributions of exergy losses and additional coal consumption under same load have distinct difference for the units with single and double reheat due to the effects of steam parameters and configuration of the regenerative system. Under rated load, the additional coal consumption of the regenerative system reaches 3.35g/（kW · h） ,and the emissions of CO2 ,SO2 ,NOx and Carbon Dust are 38 041.35 t/a, 1 045.03t/a,579.89t/a and 10 515.50t/a, respectively.