Fuel Improvement Measures for Particulate Matter Emission Reduction during Corn Cob Combustion

Fuel-related measures and modernization of small-scale combustion units has become the focus of attention in the renewable heat generation sector, as a means to promote local biomass utilization and fuel-flexibility while meeting strict environmental legislative requirements. With the aim to mitigate total particulate matter emissions and ash-associated problems characteristic of crop residue combustion, (1) corn cob pellets (with and without kaolin and binder) as well as (2) fuel blends with wood pellets were combusted in a pellet oven under full load. Results show that additivation or fuel blending (e.g., 50 wt. % wood and 50 wt. % corn cob pellets) reduce total particulate and CO-emissions by 48 to 60 wt. % and 64 to 89 wt. %, respectively, in comparison to baseline emissions from non-additivized corn cob pellets. Kaolin prevented sintering of corn cob ash. However, considerable grate ash entrainment was observed. TPM consists of a “primary network”—polyhedral and spherical particles approximately 1 μm in diameter (mainly KCl), and a “secondary network” built on top of the primary network, consisting of square-prism-shaped particles of approximately 200 nm in diameter. KCl and K 2 SO 4 are main compounds in particles from corn cob and wood pellet combustion, respectively. Effective measures demonstrated within this study should be complemented with low-cost coarse ash removal systems.