Fuel Staging and Its Implementation in a Novel Internally Staged Burner

摘要

A study to investigate the process parameters which influence coal reburning andto apply these principles in designing and testing a coal fired, fuel staged burner is presented. This burner was intended to be used on wall fired boilers with both coal and natural gas considered as reburn fuels. The study was conducted in three experimental parts: a reburn zone investigation into the influence of process parameters on NOx, HCN, and NH3 reduction in the reburn zone; a furnace investigation into the NOx emissions from a fuel staging furnace, operated with incomplete mixing of reburn fuel and primary combustion products; and an Internally Fuel Staged Burner (IFSB) based on the concept of injecting the coal or natural gas reburn fuel through the center of the burner and reducing primary NOx at the downstream end of the internal recirculation zone. It is believed that the IFSB merits further development. The NOx emissions from the IFSB were low compared to existing low NOx burners. Also, burner performance was not adversely affected by operating with low NOx emissions. The CO emission did not exceed 5 ppm and the flame was compact and stable for all tests. Additional tests are recommended to improve the design and to establish scaling criteria.