Thermoelectric Phenomana in High-Temperature and High-Pressure Electrostatic Precipitator and Performance Improvement

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Efficient removal of fly ash particles from high temperature flue gas is one of the most important technologies to be developed for realizing advanced high efficiency coal utilization systems such as an integrated coal gasification combined cycle (IGCC), and ceramics filtering systems have been considered for this purpose. On the other hand, high-temperature electrostatic precipitator systems also have a high possibility to be used for gas clean-up in IGCC.But in this case, high-pressure condition should be required to maintain corona discharge. The purpose of this study is to clarify separated effects of temperature and pressure on various electric and thermal phenomena in the high-temperature and high-pressure electrostatic precipitator and to obtain fundamental knowledges necessary to develop a highly efficient high-temperature and high-pressure electrostatic precipitator. For this purpose, one-dimensional cylindrical electrostatic precipitator with a thin wire electrode at the centerline has been constructed and effects of temperature and pressure on various electric and thermal phenomena have been derived separately and then coupled effect of them on precipitation performances have been clarified.Drastic decrease of collection efficiency at high temperature can be qualitatively explained by decrease of ion formation rate near the center electrode, decrease of particle charging rate and decrease of particle drift velocity with high kinematic viscosity and this result can be well explained by the dependency of mean free path on the temperature. The discharge mode should have changed from corona to glow mode. So, applying high pressure is definitely necessary to maintain high performance and low energy consumption in a high-temperature electrostatic precipitator.