Continuous Emission Monitoring System and Dust Shuttling Resolve Mercury Emission Riddle in Florida

摘要

The 2006 EPA portland cement maximum achievable control technology (PC-MACT) regulation imposed mercury (Hg) limits for new cement kilns, some of which were already under construction. Upon startup one operator measured near zero emissions for an in stack test conducted when the raw mill is on representing 92 percent (%) of the operational time and very high emissions when the raw mill is off representing 8% of the time. The operator demonstrated the utility of a Hg continuous emission monitoring system (Hg-CEMS) for the purpose of diagnosing the emission characteristics with respect to time and operating mode as well as the efficacy of dust shuttling to reduce short-term Hg concentrations and long term Hg mass emissions. The operator demonstrated that its new kiln comply with both the 2006 PC-MACT and the updated 2010 version that will apply in 2013. The findings basically have rewritten the book of knowledge about the behavior of Hg in dry process preheater/calciner cement kilns and also served as a model for cooperative efforts towards finding timely solutions for such previously misunderstood emission phenomena.