Low NOx burner retrofits to an existing boiler

　　Low NOx burner retrofits to an existing boiler, dryer or incinerator aren’t as simple as pulling out the old burner and bolting in a new one.There is so much more that needs to be considered as part of the engineering and purchase decision process.　ijeBoiler Burner
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　　Many times, these can be interrelated, where addressing one issue causes problems in unrelated areas.ijeBoiler Burner

　　Examining the Dynamics Surrounding Existing Fan CapacityThe majority of current low emissions burners require relatively high air side pressure drops to achieve the desired fuel/air staging within the burner itself.Based on this design consideration, the pressure drop may be far higher than what the original burner was designed for.The dynamic of pressure drop is commonly referred to as “register draft loss” or RDL.The new RDL requirements necessitate reviewing the existing forced draft fan to assure that the fan is able to provide the static pressure to accommodate new burner systems.The onus should be placed on the burner supplier to review and confirm the capability of the existing FD fan based on both review of subject fan curves and review of boiler operating data showing system pressure drops or through the performance of static pressure testing of existing fans.ijeBoiler Burner

　　Many low NOx burners include added flue gas recirculation (FGR) that further mitigate and minimize NOx emissions.Often times, FGR rates can range from 5 percent to 30 percent of the total boiler flue gas flow.The FGR can be induced into the FD fan (commonly referred to as IFGR) and mixed with combustion air prior to entry into the burner/windbox.The incorporation of IFGR adds the mass flow requirement of the FD (and ID) fans, while at the same time increasing the furnace and system pressure drop.It is paramount to review the existing FD fan (and ID fan where applicable) to assure that the existing combustion air and flue gas systems are able to accommodate the new equipment and performance requirements.ijeBoiler Burner

　　In applications where the existing fans in operation are insufficient to meet and exceed the new performance metrics, it is desirable to investigate using larger fans and motors, utilize a separate FGR fan, or to reduce the maximum boiler capacity.Understanding the Implications of Furnace Dimensions and Burner SpacingijeBoiler Burner