Ultra Low NOx Hot Water Supply Boiler Development

This paper describes the successful application of the AGA Research ultra-low NOx burner technology to a commercial hot water supply boiler. This work is a joint program between the AGAR and Raypak Incorporated. The AGAR low NOx burner is based on the concept of ultralean premixed combustion stabilized by a combination of swirling and bluff-body aerodynamics. A unique air/fuel mixer is used to produce an extremely homogeneous air/gas mixture, and a simple, low cost flameholder is used to provide excellent flame stability. This burner design is capable of producing a compact flame with 4: 1 turndown ratio. In this paper, the flexibility and Scalability of this burner technology is explained. The validity of the scaling parameters was demonstrated during the development of a new Raypak hot water boiler line. A 0.5 million Btu/hr model and a 1.5 million Btu/hr model have been developed during this project. The emissions produced by both models meet the most stringent regulations in the U.S. The 0.5 million Btu/hr unit has been successfully field tested, and the commercial product has been available since July, 1996. In addition to the boiler performance discussion, the feasibility of this low NOx burner technology for other applications is discussed.