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Show INTRODUCTION In 1984 the South Coast Air Quality Management District (SCAQMD), which oversees the Los Angeles air basin in southern California, enacted Rule 11 09 limiting the NOx emissions from furnaces and boilers in petroleum refineries and chemical plants. This rule provided that furnaces over 40 million Btu/hr (42.2 GJ/hr) were limited to 0.14 Ib of NOx per million Btu of heat input (0.06 g/MJ). The limit was given as a plant wide average and included existing as well as new furnaces. In order to comply, the plant owners retrofitted some of their furnaces with low NOx burners capable of producing less than 0.06 to 0.08 Ib of NOx per million Btu in order to produce the offsets needed to reduce the overall average emissions. In the Fall of 1988 Rule 1109 was revised and this limit was reduced to 0.03 Ib per million Btu(HHV) (0.013 g/MJ), which is a reduction of more than 75%. Rule 1146 was also enacted, limiting the emissions from furnaces and boilers with less than 40 MMBtu/hr (42.2 GJ/hr) heat input to 40 PPMV &dry, corr. to 3% 02). Both of these new limits, which are about 50 and 80 mg/NM , respectively, have presented significant challenges to burner designers and manufacturers. This paper describes the results of the development effort conducted by John Zink which has successfully met this challenge. One of the major difficulties facing the burner designers and the refineries and chemical plants is the nature of the fuels that they utilize. Typically, waste gases from several processes make up the greater portion of their fuel gas supply. They may be burned as is or they may be blended together with natural gas and distributed via a plant wide fuel gas system. These waste gases contain large volumes of hydrogen, ethane, propane and butane and, at times, significant quantities of ethylene, propene and butene. The composition of the main fuel gas system is constantly varying as more or less of the individual waste gases are available. For example, it would not be uncommon to see the heating value change from 650 Btu/set to 1300 Btu/set in as little as an hour. In some cases, when it is not practical to send a particular waste gas to the central fuel mix drum, it is necessary to burn varying quantities of two fuels in the same burner, such as a specific off gas along with the main fuel gas. This can also present burner design difficulties, if the fuels have significantly different characteristics. 1 |