AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Modeling of Corona-Quenching in Tube-Wire Type Electrostatic Precipitators
CHRISTIAN LUEBBERT, Ulrich Riebel, FAU Erlangen-Nuremberg, Germany
Abstract Number: 567 Working Group: Aerosol Physics
Abstract The reduction of current uptake in electrostatic precipitators by particle attached space charge is known as corona-quenching. This effect occurs at the precipitator’s inlet section for high dust concentrations. As a typical consequence the current up-take is locally reduced to values of less than a percent of the clean gas current uptake under conditions of strong quenching. At the same time the sparking voltage decreases due to the distortion of the electric field. The required reduction of the applied voltage will not only prevent sparking but also the precipitation efficiency in the whole precipitator section. Hence for critical aerosols a fundamental understanding of the quenched state as well as of the kinetics of the transition from the quenched regime to the normal operation regime is inevitable for an adequate design of the electrostatic precipitator.
The focus of this work is on the theoretical description of the corona-quenching process in a wet tube-wire type electrostatic precipitator for sub micrometer sized aerosols. The basis of the analytical description is a balance of particle attached space charge, whereby models of different complexity are discussed. The presented models range from simple but well-reasoned calculation of the maximum current suppression time by particle attached space charge to 1D simulations, which are in almost perfect agreement with the measured current up-take behavior. The calculation approaches allow designing and optimizing electrostatic precipitators for concentrated aerosols. Furthermore, interpreting the theoretical results, it is found that there is a geometry dependent upper limit for the precipitation rate, which is achieved in the quenched state. Due to the very low current uptake precipitation of particles is highly energy efficient in this regime. However it follows different rules that have to be considered.