Back-End Modifications of Portland Cement Plants to Reduce Emissions of Hazardous Air Pollutant

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Abstract 9613422 Sidhu This proposal focuses on the reduction of hazardous air pollutants (HAP) such as hydrocarbons, hydrochloric acid, and polychlorinated dibenzo-p-dioxins and polychlorinated furans (PCDD/F), produced in the production of Portland cement. Volatilization of organics from the feed stock during preheating and drying and conditions in the Air Pollution Control (APC) device and in the transfer ducting zones appear to be primarily responsible for the formation of these HAPs. Several process modifications such as the thermal pretreatment of feed stock, elimination of hydrocarbon recycle, temperature reduction in the preheat off-gas transfer duct, increased oxidation, and modification of preheater conditions may help reduce and/or prevent this HAP formation. An experimental program is proposed in order to determine which of these strategies is most effective and what precise process modifications are necessary to implement them. A high temperature flow reactor, operating in the range of 200 to 700 C will be used to study the speciation, partitioning, and reaction of raw meal hydrocarbons and chlorine in an environment containing cement kiln feed stock and NOx, O2, and water. This data should enable the design of specific process modifications to prevent the formation and emission of HAPs from Portland cement kilns without the addition of control devices.