• Energy Research

Abstract The paper presents experimental results of the investigation of agglomeration of PM2.5 fly ash particles with larger particles in an electrostatic agglomerator. SEM micrographs of the obtained agglomerates shown that a single particle of the size of 10-20 μm can collect more than 20-50 PM2.5 particles in this type of agglomerator. The experiments were carried out in a semi-industrial scale channel of a cross section of about 600 mm height and 1100 mm width. The agglomerator can be used as a particle precharger in a hybrid system or as the first stage in a two-stage electrostatic precipitator, in order to increase their total collection efficiency.

Abstract In this paper, lab and commercial constructions of electrostatic precipitators used for the removal of fly ash particles from small residential boilers have been reviewed. The presented solutions were evaluated in terms of removal efficiency, exploitation conditions or expected maintenance costs. Boilers used for household heating are the main sources of air contamination by particulate matter during winter seasons in many countries. The collection efficiency of such devices should be higher than 95% to comply with the ECODESIGN emission limit, and the emission level for biomass

Abstract The paper presents results of the tests of a novel type, semi-industrial scale hybrid electrostatic filtration system, called HYBRYDA+. The hybrid system comprised of conventional electrostatic precipitator, kinematic electrostatic agglomerator and bag filter. In this system, the bag filter, can remove not only microparticles but also submicron and nanoparticles attached to larger particles in the process of agglomeration. The system was installed at a by-pass of an exhaust gas conveying duct downstream of a 225 MWe power plant unit with coal-fired boiler, in a power plant South Poland. HT ELPI®+ impactor was used for the measurement particle size distribution. The collection efficiency of this system for PM2.5 particles was increased by the reduced pressure drop across the filter. The frequency of bag filter regeneration was reduced by about 82%. The rate of increase of the pressure drop across bag filter was about five times lower than for the same bag filter operating without electrostatic precipitator and electrostatic agglomerator, and the regeneration period of the filter increased from about 7 min to 35 min. The energy consumption required for filter regeneration can be reduced and the lifetime of bags can be longer in this system.

Abstract Semi industrial-scale, two-stage electrostatic precipitation system comprised of unipolar electrostatic agglomerator and electrostatic precipitator was investigated in this paper. In this type of agglomerator, the process of particle charging and their agglomeration is accomplished in the same device. The particles are charged by ion current in alternating electric field, and agglomerated due to their oscillatory motion in this field, perpendicular to the gas flow. The charged and agglomerated particles are collected in the next stage, which is a conventional electrostatic precipitator with spiked wire discharge electrodes and collection electrodes of the sigma type. Collection efficiency of this system was measured for different gas temperatures, different fly ash concentrations and for various magnitudes of AC voltage applied to the agglomerator. Two-stage electrostatic precipitator allows obtaining higher fractional collection efficiency for PM1 and PM2.5 particles than a one-stage electrostatic precipitator. In this type of two-stage electrostatic precipitator with an agglomerator, the number collection efficiency for fly ash particles in PM10, PM2.5 and PM1 size ranges was about 96%, 96% and 94%, respectively, and mass collection efficiency in same size ranges was 98%, 97% and 95%, respectively.