Energy Conservation Analysis and System Optimization of Extended Air Preheater

摘要

Steam air heater is one of the most effective ways to avoid the corrosion and ash deposition of air preheater, but it increases the temperature of exhaust gas from the boiler and as a result, reduces cycle efficiency of the power plants. The current paper investigates the economic performance of a pre-fixed type of extend air preheater(EAPH). Based on the quantitative analysis of energy conservation and equivalent enthalpy method, the results indicate that the economic performance of the new preheater is not good when no air is required to be heated. In such case, an optimized system is proposed and the economic performance of the system is analyzed when applied in a 320 MW unit. The results show that the incremental ratio of the plant efficiency employing the optimized system increases from 0.11% (for EAPH) to 0.51% when no air is required to be heated. The saved value of annual-average standard coal consumption rate is 1.50 g/(kWh) compared to EAPH of 0.54 g/ (kW-h).