Investigating potential co-firing of corn cobs with lignite for energy production. Thermal analysis and behavior of ashes

ABSTRACT Thermal analysis technique was used to study the combustion characteristics of lignite, corn cob biomass, and their mixtures. Ignition, reactivity, peak and burnout temperatures, combustion time, and interactions between blend components were determined. Ashes were characterized by chemical, mineralogical, and fusibility analyses in order to assess their environmental impact, as well as slagging and fouling propensities. Combustion of corn cobs occurred between 220°C and 500°C, while that of lignite between 220°C and 730°C. When corn cobs were blended with lignite at percentages up to 30%, mutual interactions were less favored and the two fuels ignited and burned independently, presenting a high degree of additivity. Although corn cob ash was rich in K and P, ash melting of the mixture occurred 25°C lower as compared to lignite; however, the fouling rate was also lower. The similarity in burning characteristics of the fuels and the improved reactivity of the blends provide advantages for their co-firing in existing lignite infrastructures.