HYBRID AIR FILTERS: A REVIEW OF THE MAIN EQUIPMENT CONFIGURATIONS AND RESULTS

ABSTRACT Electrostatic precipitators and bag filters are traditionally used to separate particulate matter from gas streams. The combination of these two technologies originated the hybrid filters. Several configurations of hybrid filters were developed in the last three decades, mainly for application in the treatment of flue gas from coal-fired power plants. Two of them stood out for the amount of applications and works that intended to study them: the Compact Hybrid Particulate Collector (COHPAC) and the Advanced Hybrid Particulate Collector (AHPC). This paper aimed to present the characteristics of these two constructions and to review the main results of hybrid filtration performance obtained in laboratory tests and industrial applications. The two configurations proved to be efficient both for the collection of particulate matter, particularly of submicron particles, and for the removal of mercury and heavy metals. In general, the pressure drop in hybrid filters is lower than in conventional bag filters, while the cycle length and the lifespan of the bags are longer. However, in some cases, the formation of dense cakes on the surface of the bags may suppress the advantages of using hybrid devices.