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

Abstract

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 K2SO4 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.

Aluminosilicate Clay Minerals: Kaolin, Bentonite, and Halloysite as Fuel Additives for Thermal Conversion of Biomass and Waste

“…Another important goal of aluminosilicates is the reduction of the formation and emission of particulate matter (PM) by bonding aerosol-forming elements, mostly K, Al, Cl, S, and Zn, in the bottom ash [40,83]. The addition of kaolin (1.5 wt.%) to the combustion of corn cob pellets resulted in approximately 48 wt.% reduction in the emission of total particulate matter by fixing the volatile alkali metals (K and Al) in high-temperature-stable silicates [84]. Moreover, ash examination revealed a lower sintering tendency.…”