Optimization of the fractional collection efficiencies for electrostatic precipitators used in biomass-fired boilers

Abstract

Electrostatic precipitators (ESPs) are commonly used for dust removal in flue gases from biomass-fired boilers. ESPs are able to precipitate the PM10 fraction (Nussbaumer, 2010) [1]. According to literature, ESPs have a reduced fractional collection efficiency (FCE) in the range of 0.2–2 μm with a minimum at about 0.7 μm (Kaltschmitt et al., 2016; Fritz and Kern, 1992; Lützke and Wilkes, 1981) [2–4]. In the research project “Optimization of the fractional collection efficiencies for electrostatic precipitators used in biomass-fired boilers (FRESBI)” the FCEs for three commercial available ESPs (OekoTube Inside – Co. Oekosolve, Filterbox S – Co. Schraeder, Filterbox 2K – Co. Schraeder) were examined. The particle size distributions in the flue gas were measured using a Scanning Mobility Particle Sizer (SMPS) and a 13 stage Dekati® Low Pressure Impactor (DLPI). The combination of both measuring methods was a successful setup with various symbiotic effects. Additionally a mathematic model for the prediction of the FCEs of tubular ESPs was developed und successfully validated. For two ESPs (OekoTube Inside and Filterbox S) optimization measures were implemented, tested and evaluated. The applied measures focused on the optimization of the electrical field strength, hence increasing the performance of the ESPs. For the Filterbox S an increased FCE was achieved.