Numerical modeling of electrostatic precipitation: Effect of Gas temperature

A Computational Fluid Dynamics model is presented to calculate the particle collection efficiency in electrostatic precipitators in terms of the interactions among gas-particle flow, dust resistivity and electric field. Various material properties and operation parameters are included to extend the model capability for process optimization. The current paper focuses on the effect of gas temperature for a cold-side precipitator. It is found that, as temperature increases in the range 90-120. °C considered, the operation voltage drops significantly, due to increased dust resistivity. Behaviors of fine particles in the range from 0.05 to 25. μm in diameter are simulated in a circular wire-plate configuration. A minimum efficiency is predicted for particle size around 0.5. μm. Below this critical size, the increased collection efficiency results from relatively large surface charge density due to diffusion charging, and reduced inter-phase drag. For moist gas, temperature has significant non-linear effect on the fly ash resistivity. It is demonstrated that a same change in temperature from 120. °C to 90. °C is more effective than from 150. °C to 120. °C, as far as the collection efficiency is concerned.