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Experience with Low NOx Burners

Sponsored by ELKRAFT, the utility group covering the eastern part of Denmark
AUTHORS: Lotte Garner
DATE: November 1997

Many power plants have installed low NOx burners and overfire air (OFA), some successfully while others have dealt with a number of difficulties. However, as legislation becomes increasingly more stringent the success rate becomes more important. Newly built power plants have the advantage that the combustion system and furnace can be designed for minimum NOx emission, while physical boundaries in older power plants can limit the NOx reduction achievable.

Common problems arising after installation of low NOx burners and OFA include high unburned carbon in the fly ash, corrosion, burner damage and changes in the slagging and fouling pattern. In retrofit cases these issues are more profound. This study describes some of the solutions. Unburned carbon in the fly ash and corrosion are concerns directly linked to the operation of the low NOx combustion system which requires low excess air. The challenge is to generate solutions which do not jeopardise the NOx emission. Some suggested solutions include burner modifications, combustion optimisation and operational changes.