In recent years

the NO_x emission from industrial and municipal gas-fired boilers remains at a relatively high level

and these gas-fired boilers usually have small capacity and large numbers. Reducing the NO_x emission from gas-fired boilers has attracted much public attentions. In 2015

the Beijing government required that the NO_xemission from the gas-fired boilers should be lower than 30 mg/m3. Then

in Zhengzhou

Xi'an

Qingdao and Chengdu

the relevant policies(NO_x emission from gas-fired boilers should be below 30 mg/m3) have also been published. In order to meet the emission control requirements

low NO_x gas burners equipped with flue gas recirculation(FGR) technology are widely applied to lower the NO_x emission. However

this method has the problems of high NO_x and CO emissions

unstable combustion

flame surge and deflagration. To solve this problem

this paper modified the low NO_x gas burners for a 120 t/h gas-fired boiler based on the FGR technology. The results showed that the NO_x emission could remain below 30 mg/m3 and the problem of blow-off and deflagration did not occur. This successful transformation lays a solid foundation for application of the new low NO_x gas burner based on the FGR system.