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Show INTRODUCTION The Clean Air Act Amendments of 1990 (CAAA) will have a profound impact on sources that emit air toxics found in the new law's list of hazardous air pollutants. Completely restructuring the existing law, Congress has granted the U.S. Environmental Protection Agency (EPA) the authority to regulate hazardous emissions by categories of industry rather than individual pollutants and to develop control standards based on "maximum achievable control technology" ( M A C T ) for each category. The geographic coverage of the control programs has also been greatly expanded. Using geographic designations, the new law attempts to regulate sources of nitrogen oxides (NO,), volatile organic compounds (VOC), carbon monoxide (CO), and particulate matter (PM) based on five discreet categories for areas that do not meet National Ambient Air Quality Standards ( N A A Q S ) for ozone (1). These provisions of the new law present a real dilemma for facilities that have hazardous air pollutants in ozone non-attainment areas. If thermal treatment is applied as M A C T , the result may actually be an increase in the level of NO,, which is at odds with other provisions of the law requiring reductions in N O , and C O emissions. Radian Corporation has developed and patented a control technology that combines thermal and catalytic treatment steps to provide maximum destruction of hazardous air pollutants with minimum formation of N O , and C O . The technology is referred to as a "Hybrid L o w N O , Process" and is especially suited for the control of hazardous air pollutants that contain bound nitrogen. The technology has been commercially demonstrated for stationary IC engine sources, and is now being applied to a process vent stream that contains hydrogen cyanide, NO,, and C O. This paper gives background information on the Hybrid Low NO, Process and summarizes the advantages of the technology over existing staged, thermal approaches to low NO, incineration of hazardous air pollutants. PROBLEM DESCRIPTION A chemical manufacturing corporation operates a staged, thermal incineration unit at their Gulf Coast facility. The system was installed in the early seventies, and is based on a patented process (2) which utilizes "staged" combustion to destroy air toxics from two process vent streams in the manufacturing plant. The system, however, has not achieved satisfactory destruction efficiencies for hazardous air pollutants and currently emits 250-450 ppmv NO,. This staged combustion concept (see Figure 1) utilizes a first stage that is operated with an excess of fuel relative to available oxygen (Qz) to create a high temperature reaction zone in which hazardous air pollutants are thermally dissociated and N O , is reduced by the excess "combustibles", primarily carbon monoxide (CO) and hydrogen (Hj). This is followed by a cooling step in which recycled flue gas from the 2 III |