Comprehensive Optimization of Air Preheater for Boiler Flue Gas Heat Recovery

To break through the inlet temperature limitation of low-temperature economizer in boiler waste heat recovery system,the tail heating surfaces of boiler were comprehensively optimized,by dividing the air preheater into two stages,and installing a low-temperature economizer between them.To make the low-temperature economizer lie in appropriate flue gas temperature range,the outlet temperature of stage II air preheater was altered,so as to obtain optimal thermodynamic working conditions.Based on techniceconomic analysis,a comprehensive optimization result was finally achieved according to requirements of actual engineering practices.Results show that the standard coal consumption for power supply can be reduced by 6.7g/(kW·h),on the basis of two-stage air preheater design and reasonable setting of key operation parameters,with the optimum thermodynamic scheme.For an average annual running time of 5 500h,the net income may reach 21million RMB/year according to the technic-economic analysis,indicating obvious economic benefits.