Improving furnace and boiler cost-effectiveness and CO2 emission by adjusting excess air



Reducing the input excess air or airflow rate to a furnace or boiler will result in decreasing transmission rate of the thermal flow from the radiation zone to the convection heating surface zone in the furnace. Results of the plant-scale test presented in this article show that if the furnace is operated at 3.6 × 107 kcal/h of combustion capacity, decreasing the residual O2 concentration in the furnace flue gas from 4% to 2.5% will save 9.3 × 103 m3 of natural gas consumption, and 2.1 × 104 tons of CO2 emission annually. For the boiler tested in the study, 1.8 × 105 m3 of natural gas consumption and 3.9 × 105 tons of CO2 emission will be reduced annually if it is operated with 90 ton/h steam yield. Hence, controlling the input excess air (or oxygen) as an important operating alternative to enhance thermal efficiency, and alleviate environmental impact of a heater furnace and boiler has been confirmed in this research. © 2011 American Institute of Chemical Engineers Environ Prog, 2012