By Kevin Goohs, R&D Manager Thermo Fisher Scientific, Franklin, MA, USA
Particulate matter (PM) in flue gas can exhibit highly variable and dynamic characteristics depending on fuel type, combustion process and emission control parameters. The primary characteristics of PM are its mass concentration, size, and chemical composition. Its size influences emission transport and inhalation potential, while its chemistry largely defines its toxicity.
In recent years, the U.S. EPA has promulgated or proposed three major MACT rules — Portland Cement MACT, Industrial Boiler MACT and Utility MACT — requiring many plants in affected industries to continuously measure the emissions concentrations of particulate matter in the stack gas using a continuous emissions monitoring system (CEMS). This is a departure from previous regulations, which allowed opacity monitors to serve as a surrogate for PM emissions.