抄録
Recent advancement in industrial furnaces brought by highly preheated air combustion is reviewed. Highly Preheated Air Combustion in regenerative furnaces has been paid much attention for its accomplishment in not only energy saving but also low nitric oxides emission. Characteristics of combustion with highly preheated air were studied to understand the change of combustion regime and the reason for the compatibility between high performance and low nitric oxides emission. It was found that combustion was sustained even in an extremely low concentration of oxygen if the temperature of oxidizer was higher than the auto-ignition temperature of the fuel. As an application of the principle, we can reduce nitric oxides emission by dilution of combustion air with plenty of recirculated burned gas in the furnace. Dilution makes the oxygen content of the oxidizer low, which decreases temperature fluctuations in flames as well as the mean temperature, hence low nitric oxides emission. Finally, the applicability of highly preheated air combustion to other fields than industrial furnaces has been discussed.
