Design of burner and study of combustion characteristics of pyrolysis oil from biomass

Abstract

Conversion of biomass to fuel provides a positive contribution for fossil fuel replacements. In addressing challenges associated with the combustion of pyrolysis oil (bio-oil), this research aimed at developing a burner system that would handle the atomization and combustion of biooil. This research started by conducting a spray study in order to explore the potential for bio-oil combustion in industrial furnaces. Spray experiments were conducted by using different sizes of externally mixed nozzles with bio-oil and ethanol blends. Results revealed that it is possible to spray bio-oil/ethanol mixtures containing as high as 40% bio-oil that has a low water content (12.6%). The design of the furnace for the combustion of bio-oil followed, this was done based on the industrial standard methods. The furnace was modelled in a computer aided design (CAD) software, the design analysis and engineering drawings were prepared followed by the fabrication and instrumentation. The furnace was then tested with bio-oil and diesel fuel prior to full scale combustion study. Building on the spray study, the comparative study of bio-oil and diesel combustion at different equivalence ratio values were conducted. It was revealed that it is possible to burn neat bio-oil in a tunnel-like furnace with a self sustaining flame. Bio-oil combustion recorded higher, carbon monoxide (CO), nitrogen oxides (NOx) and hydrocarbon (HxCy) emissions when compared to those of diesel. A follow-up combustion study with oxygen enriched atomization revealed that it was possible to fire neat bio-oil with a significant reduction of pollutants emissions. ii Based on the results from this research, it can be concluded that it is possible to burn 100% biooil in an industrial sized burner. On the other hand, oxygen enriched combustion help in reducing emissions levels in the exhaust. Therefore, the use of bio-oil as fuel in an industrial scaled furnace is now possible.