Taking decrease of NOx emission as the target

two boilers with front-wall burning designed by Foster Wheeler Inc.and equiped in Ligang Power Plant have been retrofitted.Through replacement and utilization of new type low-NOx burners

addition of over-fired air(OFA)

the NOx has been reduced by 60%

but the carbon content in fly ash from boilers has somewhat increased.In view of this

an optimized adjustment of the retrofitted combustion system has been carried out.Finally

under different oxygen density

different combination of coal pulverizers

and burning different coal sorts

results of reducing NOx emission density

decreasing deviation of temperature on tubulatue of reheater

curbing the increase of carbon content in fly ash

as well as proventing appearance of slag-staking have been obtained.