Ash Behaviour during Combustion of Agropellets Produced by an Agro-Industry—Part 1: Blends Design and Experimental Tests Results

Abstract

Agropellets are presented as a suitable product to be produced in certain agro-industries which could become Integrated Biomass Logistic Centres (IBLC) by taking advantage of its current resources during those periods in which their facilities are underused. Wheat straw and maize stalk were selected to be blended with forestry wood in an agro-industry dedicated to animal feed production. The materials were characterized to assess the quality of the input material. Taking into account the former, different pellets (blends of woody and herbaceous biomass) were produced and tested in a fixed bed reactor in order to study their combustion behaviour. Additionally, several predictive indexes were also calculated to assess sintering and deposition occurrence probability. Ash sintering degree was found to be directly related to composition and highly dependent on Si content. Moreover, an increase of the wood content in the blend did not proportionally imply a higher quality of the final blend, as would be expected. Regarding deposition, due to the high number of factors involved in this phenomenon, it has not been possible to draw clear conclusions. To do this, it was necessary to delve into the deposition mechanisms, which is addressed in the second part of this paper. Thus, despite the appearance of sintering and deposition phenomena, the combustion behaviour was satisfactory in the test carried out. Additionally, it has been demonstrated that agro-industries can act as IBLCs, producing blended pellet for the energy market that aligns with the standard ISO 17225-6.

Keywords

• integrated biomass logistic centre
• agro-industry
• combustion
• agropellets
• fixed bed reactor
• bottom ash sintering