| Abstract |
Recent EPA regulations have mandated that refinery and other petro-chemical industries reduce NOx emissions. New Burners technologies have been developed to meet the more stringent emission requirements. Most of these new technologies use internal flue gas recirculation and fuel staging to reduce the NOx. The techniques used in Ultra Low NOx burners (ULNB) for reduction of NOx emission from process heaters can potentially affect key aspects of burner and heater performance. These burners are operating closer to their limits of flame stability and complete combustion. Ultra-low NOx burners are very prone to flame interaction in multi-burner heaters. The existing guidelines for burner specifications and fired heaters design are generally based on conventional and Low NOx burners. Ultra Low NOx burners behave differently, so a new set of guidelines are required to specify new burners in fired heaters. A better specification is the first and best opportunity to get the optimum heater performance and minimize operating and maintenance problems. ULNBs, along with fired heaters, need to be specified correctly to achieve optimal heater operation. The proper selection of a fuel gas supply system, number of burners, fired duty per burner, location of burners, fired heater design and operating parameters are very important for the optimum performance of a fired heater. Every design step in fired heater and burner design is critical. An oversight at any stage, from fuel gas supply to flue gas disposal, will adversely affect the burner as well as the fired heater performance. Many fired heater design and operating parameters may not be of significance with conventional burners, but they become important for ULNBs. This paper discuss and provide practical guidelines to correctly design a fired heater with ULNBs. This paper includes mechanisms of NOx formation, features of Ultra Low NOx Burners, Target & Purpose of these guidelines, Criteria for Selection of Burners, Design criteria for fired heaters with ULNBs, Operating parameters critical to fired heaters with ULNB, CFD verification for critical parameter peak heat flux for ULNB Burner arrangements. A critical analysis of all these parameters is very helpful in successful operation and longer run length of a process fired heaters. |
