Emission of trace compounds from catalytic cracking regenerators

Catalytic cracking units (CCUs) are a potential emissions source for a number of compounds listed as Hazardous Air Pollutants (HAPs) in the 1990 Clean Air Act Amendments. In some cases, these compounds are formed in the catalyst regeneration process, and in others they are present in coke, converted to oxides in the regenerator, and then emitted, In this analysis, both average and median emission factors for these HAPs were developed based upon more than 1,400 field test data points covering over 60 compounds. For some of these compounds, there are large differences between the average and median emission factors due to significant scatter in the raw data. Comparisons to published emission factors from several sources indicate that, for formaldehyde, the median emission factor is more likely to be representative of actual CCU emissions.