Modeling of heterogeneous dustcake effect on particle migration of coal fly ash and PAC in a cylindrical ESP
Eric Monsu Lee1, *, Herek L. Clack2
* The author to whom correspondence should be addressed.
1 Northern Illinois University, 104 Eng. Bldg., 590 Garden Road, DeKalb, IL 60115, USA
2 University of Michigan, 169 EWRE Bldg., 1351 Beal Avenue, Ann Arbor, MI 48109, USA
Abstract
The application of droplets has been extensively discussed and explored for decades. The cleaning effect, which is based Powdered activated carbon (PAC) injection upstream of an electrostatic precipitator (ESP) has been the most mature mercury control technology at coal-red power plants (CFPPs). However, the application of PAC injection showed increasingly darkened particulate matter (PM) samples collected from the stack emissions as the sorbent injection rate was increased. From our previous experimental study, the simultaneous precipitation of coal fly ash and PAC led to the formation of heterogeneous dustcake, with powder resistivity varying along the collection electrode. To study the mechanisms leading to the potential of particle penetration through ESPs during PAC injection, the present study aims to model the effect of heterogeneous dustcake in a cylindrical electrostatic precipitator (ESP) by developing a 2-D Euler- Lagrange numerical model. By prescribing a 2-D oscillatory boundary condition on the collection electrode, the results show that the presence of a heterogeneous dustcake can alter the electric field, ion density, and electrohydrodynamic (EHD) ow, characterized as a wave-like flow field, which is then shown to influence the particle trajectory length, particle charging rate, initial particle contact velocity, and particle collection efficiency.Keywords - Coal-fired power plants, mercury sorbent injection, electrostatic precipitator model, heterogeneous dustcake resistivity, wave-like EHD flow field.