Heat transfer characteristics of a rotary regenerative combustion system (RRX)

Abstract

With a view to saving fuel, the use of regenerative burners as a heating source has been spreading in the field of industrial furnaces. By combining a burner with a regenerative air preheater, a second generation regenerative burner—the Rotary Regenerative Combustion System (RRX)—has been developed, which makes for lower emission of air pollutants and compactness, in addition to fuel savings. In this paper, heat transfer characteristics of RRX were deduced theoretically based on the heat transfer theory of a regenerative air preheater and investigated experimentally using two test rigs. A commercially operating fired heater was revamped in the summer of 1994 to install three sets of RRXs, and it has been successfully operated for one year. As a result, it was determined that the heat transfer rate in RRX can be predicted to within ±10%, by considering not only convective but also radiative heat transfer. Furthermore, it was confirmed both theoretically and experimentally that fuel efficiency exceeding 90% was stably attained in a commercial fired heater. Around 60 ppm of NOx emission (as dry, 6% O2) was also measured, although the preheated air temperature was calculated to be as high as 930 K. © 1999 Scripta Technica, Heat Trans Jpn Res, 27(8): 584–596, 1998