Abstract
ABSTRACT The accurate monitoring of particulate emissions from medium-scale, decentralized biomass combustion units is a major challenge for the deployment of this technology in the frame of the current energy transition. More specifically, the experimental characterization of the size of the emitted particles, i.e. using impactors, is still subject to discussions about the impact of the methodology on the measurement results. To meet with these challenges, particulate emissions from a medium-scale biomass boiler (4.5 MWth) were measured with Electrical Low Pressure Impactors (ELPI+) using two different dilution systems to examine the effect of dilution and performance of the ELPI+. For both the two stage dilution systems and one stage dilution system, no statistically significant correlation was found between the dilution ratio (DR) and particle total number concentration Ntot or between DR and mass concentration mtot. However, with both dilution system, a significant positive correlation was observed between DR and particles with diameter Dp < 0.01 µm due to measurement artefacts. With the one stage dilution system dilution systems, condensation appears to be promoted with reduced DR. When the ELPI+ impactor is not overloaded, the number concentration of fractions N< 0.01 and N0.01-0.1 reduce over time due to prematurely measuring particles. When the impactor is overloaded, N< 0.01 is overestimated and N0.01-0.1 and N0.1-1 are underestimated due to a change in cut-off diameter.
Highlights
Biomass has been used for centuries around the world for generating energy due to its availability
The particulate matter (PM) emissions are characterized by their particle number size distribution which can be summarized by the quantities total number of particles Ntot and geometric mean particle diameter (GMD)
The two dilution systems are complementary since the DAD 100 operates with a dilution ratio (DR) between 4 and 10 while the PTD + ED operates with a DR between 10 and 51
Summary
Biomass has been used for centuries around the world for generating energy due to its availability. Biomass is gaining popularity due to being a viable alternative for fossil fuel but with a short-term carbon cycle, helping to reduce global warming (McKendry, 2002). Biomass combustion will avoid additional CO2 emissions, but medium-scale biomass combustion for district heating is often economically viable (Soltero et al, 2018). Biomass will be among the most important energy sources of the future (Dhillon and von Wuehlisch, 2013). A disadvantage of biomass combustion (in particular with solid fuels), beside NOx emission, is the emission of particles. PM resulting from biomass combustion can be divided into organic and inorganic pollutants. Organic PM consists of products from incomplete combustion (PIC) and can be reduced by improving the combustion efficiency, while
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