Numerical Modeling of Mercury Adsorption by Injection of Powdered Activated Carbon Inside An Electrostatic Precipitator

In response to the new US air quality rules and regulations an extensive number of research studies have invested on reducing and controlling the mercury emissions from coal fired power plants. Among the current mechanisms of mercury adsorption, particulate control in the presence electrostatic precipitation (ESP) is a well-established approach, particularly in the U.S. coal fired power plants. The present study illustrates the use of a commercial CFD package-Fluent- in modeling of mercury adsorption by the injected PAC particles inside an ESP. The adsorption model is adopted from Langmuir theory in which the net adsorption rate is proportional to sorbent capacity and sorbent utilization. The computational domain is comprised of a 2-D wire-plate ESP channel with designated inlets for air/PAC particles and air/mercury vapor mixtures. The governing equations include those covering continuous phase transport for air and mercury species, electric potential, air ionization, particle charging.  The particles are tracked using a Lagrangian Discrete Phase Model (DPM). The effect of particle characteristics (e.g. size, electric properties, etc.) on the mercury adsorption performance under various operating conditions (e.g. air flow, mercury inflow concentration, ESP applied voltage, etc.) is investigated.