空气预热器旁路烟气余热利用系统热力特性数值模拟

Numerical simulation on thermodynamic characteristics of air preheater bypass flue gas waste heat utilization system

燃煤电站锅炉普遍存在排烟温度高、排烟热损失大的问题。本文根据能量梯级利用的原则,以某超临界600 MW机组为例,采用商业软件EBSILON建立了包含锅炉、汽轮机和发电机的完整系统模型,并在此模型基础上对常规低压省煤器系统和空气预热器旁路烟气余热利用系统进行了热力特性数值模拟。结果表明:空气预热器旁路烟气余热利用系统可提高烟气余热的利用能级,实现能量的梯级利用,其节能效果约为常规低压省煤器系统的2倍;空气预热器旁路烟气余热利用系统更适用于热一次风干燥能力较大的机组。

High exhaust temperature and large heat loss of flue gas are common problems occurred in utility boilers. Therefore, on the basis of energy cascade utilization principle, a complete system model including boiler, steam turbine and generator was established using the commercial software EBSILON, by taking a supercritica1600 MW unit as the example. On this basis, the thermodynamic characteristics of the normal low pressure economizer system and air preheater bypass flue gas waste heat utilization system were numerically simulated. The results show that, the air preheater bypass flue gas waste heat utilization system can increase the utilization level of flue gas waste heat, realize the cascade utilization of energy, of which the energy saving effect is about 2 times of that of the conventional low pressure economizer system. The air preheater bypass flue gas waste heat utilization system is more suitable for the units with larger hot primary air drying capacity.