A direct gasoline pre-blending of bioalcohol mixtures as a means of decreasing separation energy losses

Abstract

Transport emissions account for around a quarter of all CO₂ emissions and so, automotive fuels are a key area of research for combating climate change. Widespread adoption of bio-ethanol fuel blends has been the first step in this direction. However, the economic and environmental viability of bio-ethanol usage is hampered by inefficiencies in its production, resulting in a need for significant improvements. The gasoline pre-blending method is a recent advancement that shows great promise in minimizing the separation energy required for bio-ethanol recovery by circumventing full purification and using gasoline’s phase equilibrium properties to eliminate water from a partially purified fermentation product. This paper models all possible gasoline pre-blending processes incorporating ethanol, butanol or both. It is found that butanol is highly suitable for gasoline pre-blending and that high recovery can be achieved even when starting with dilute concentrations. In addition, the presence of even small amounts of butanol is effective at drawing ethanol into the fuel phase, improving the overall alcohol recovery. Energy savings of up to 19% have been shown using a case study while a graphical methodology for preliminary design and synthesis of any gasoline pre-blending process has been developed, allowing for rapid flowsheet development and performance prediction.

Keywords:

• ethanol
• butanol
• pre-blending
• energy
• gasoline

Acknowledgements

The authors would like to thank the Institute for the Development of Energy for African Sustainability (IDEAS) and the National Research Foundation of South Africa for providing financial support for carrying out this work. Dr M.J. Fernandez-Torres thanks the visiting researcher programme, at the University of South Africa, for financial support.

Disclosure statement

No potential conflict of interest was reported by the authors.