Assessment of Trace Organic Emissions Test Results from the Montgomery Count South MWC in Dayton, Ohio

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removed by the spray, a rough approximation can be made the proportion of surface area removed. Based on these assumptions it is estimated that less than 20% of the surface area is removed by the water quench spray. Since the CDD/CDF reduction was typically greater than 90%, it seems unlikely that a surface area phenomenon is the proper rationalization for the observed reduction across the conditioning chamber. A third possible explanation is that the CDD/CDF at the furnace exit is physically associated with the large diameter particulate which can be effectively removed by the quench water spray. If CDD/CDF is associated predominantly with large particulate and the estimates of particulate mass loading of 6900 ng/dscm are correct, then the reduction of PM mass by 60 to 80% is in closer agreement with the observed quench chamber removal of CDD/CDF. If these analyses are correct then it is reasonable to assume that a major portion of the CDD/CDF leaving the combustor is associated with large particles. Fonnation in ESP The second region of formation is between the ESP inlet and the stack. It is believed that most of the formation in the region is within the ESP. As shown by the data illustrated in Figure 2 a substantial increase in CDD/CDF concentration occurs as the flue gases pass through the ESP. The CDD/CDF stack concentration increased for every test run including those at 300°F (150°C) ESP inlet temperature with duct injection of hydrated lime. Outlet concentrations ranged from 22,470 ng/dscm during one run at high temperature operation (test condition 1), to 14 ng/dscm corrected to 7% 02 during a duct injection run (test condition 5). The increase across the ESP ranged from a minimum of 200% to a maximum of 18,700%. Trace organic emissions data from waterwall MWCs with ESPs typically show a net increase of CDD/CDF concentration when the ESP is operated above approximately 450°F (232°C) and net reduction in CDD/CDF below that temperature." The unprecedented percent increase observed at Montgomery County may be attributed to many factors. One explanation is directly related to the previous discussion concer­ning CDD/CDF from the furnace being associated with large diameter particulate. At Montgom­ery County the ESP is not credited with removal of that portion of the entrained particulate and its associated CDD/CDF since it was removed in the water quench. In traditional waterwall systems the ESP is responsible for all post furnace particulate removal and will be credited with removal of CDD/CDF associated with large particles. At Montgomery County the reduction in CDD/CDF 11