A Dissertation Submitted in Partial Fulfilment of the Requirements for the Degree of
Doctor of Philosophy in Sustainable Energy Science and Engineering of the Nelson
Mandela African Institution of Science and Technology
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.
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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.