Problems like the combustion instability and poor burning property of pulverized coal occurred in practical operation of the Foster Wheeler(FW) down-fired boiler were investigated.Research showed that appropriate increase in the F layer secondary air tilting angle can significantly enhance the return of the high temperature gas and reduce the uplift of the secondary air to the primary air flame

which was favor for the undershoot of the primary air flame and can extend the pulverized coal residence time

therefore

the combustion stability and burnout performance of the down-fired boiler were significantly improved.Experimental study showed that

the full down-dip of F layer secondary air firstly improved the combustion stability

making it possible to increase the oxygen content and turn up the arch oiled gun wind

and on this basis

the unburned carbon content can be greatly reduced by adjustment