燃煤电站两种烟气余热利用方式的对比分析

Comparative Study on Two Utilization Methods of Flue Gas Waste Heat in Coal-fired Power Plants

介绍了燃煤电站常规低温省煤器系统与原煤烟气预干燥系统2种烟气余热利用系统,并以国内某600 MW超临界机组为例,对2种余热利用方式下机组的热力学性能进行了计算分析;在此基础上,进一步从系统能量分布及能量品位的角度探究2种系统的节能机理,并对其应用后机组的经济性进行了对比分析。结果表明:以案例机组为例,锅炉排烟温度由130℃降低至95℃,常规低温省煤器系统可使机组供电煤耗降低1.4 g/(kW·h),而原煤预干燥系统由于可置换出更高品位的燃料化学能,可使机组供电煤耗降低3.7 g/(kW·h),具有更优的节能效果与经济效益。

Two methods of flue gas waste heat utilization systems in coal-fired power plants were introduced,including conventional low-temperature economizer system and raw coal pre-drying system.Taking a 600 MW supercritical unit as an example,the thermodynamic performance of the unit under two waste heat utilization modes was calculated and analyzed.On this basis,the energy saving mechanism of the two systems was further explored from the perspective of energy distribution and energy grade,and the economic efficiency of the units after applying the flue gas waste heat utilizations was compared and analyzed.Results show that,when the boiler exhaust temperature reduces from 130°C to 95°C,the power supply coal consumption rate of the unit can be reduced by 1.4 g/(kW·h)with the using of conventional low-temperature economizer system.For the raw coal pre-drying system can replace higher-grade fuel chemical energy,the coal consumption rate of power supply can be reduced by 3.7 g/(kW·h),which has a better energy-saving effect and economic benefit.