Implementing NOx control: Research to application

Research in NOx formation and control has advanced significantly since Zeldovich first postulated the thermal NO formation mechanism in 1943. This paper reviews the history of NOx control implementation over this time period, with an emphasis on the role that research has played on NOx control technology, development and implementation. The discussions are divided by decades, to facilitate comprehension of the progress made. Key representative research during each decade is reviewed, covering topics from fundamental combustion studies to the effect of chemical additives on selective non-catalytic NOx reduction performance. NOx control regulations that drove (and continue to drive) the technology are also discussed. The primary focus is on Southern California and Federal regulations. Southern California was chosen because it has always had the strictest NOx emissions limits in the U.S.A., while other states and the federal government have followed at a somewhat slower pace. Federal regulations are reviewed since they represent the minimum control requirements nationwide. The application of NOx controls discussed ranges from the simple combustion modifications, implemented in the late 1950s and early 1960s, through the development of ultralow NOx burners and the retrofit of advanced selective catalytic reduction systems of today. (C) 1997 Elsevier Science Ltd.