Hydrocarbon testing & emissions in cement plants

The total hydrocarbon emissions from cement kilns have come under regulation over the past several years. The EPA's National Emission Standards for Hazardous Air Pollutants (NESHAP) has put a cap of 24 ppmvdc (parts per million on a volumetric basic, dry gas, and corrected to standard conditions) on total hydrocarbon (THC) emissions. THCs are easy to measure and are felt to be an indicator of combustion efficiency, by the EPA. However, unlike other industries, THC emissions in cement plants can come from both combustion and raw materials. This paper documents common sources of THC emissions in cement manufacture. The paper uses experiences from different cement plants to document testing procedures and results that assist in understanding THC emissions. Understanding the sources of THC emissions is the first step in developing a mitigation and compliance strategy. The paper also reviews some of the more common THC emission control technologies that can be used. Some of the advantages and disadvantages of these technologies are provided. The result is a road map that can be followed by other cement plants in diagnosing and resolving THC emissions issues and maintaining compliance with air regulations on a continuous basis.