Abstract

The principal goal of this research was to explore a new avenue of utilizing crude glycerin in potential electricity generation via gasification process integrated with Stirling engine generator. Glycerin (C₃H₈O₃) is a byproduct of vegetable oil or animal fat transesterification process for biodiesel production. An externally heated fixed bed gasification unit was installed to achieve thermal decomposition of glycerin. Glycerin was gasified in the externally heated gasifier. The effects of bed temperature (650, 700, and 750°C) and water to glycerin ratio (0%, 15%, and 30%) on the products yield (gas, liquid, and particulates), gas composition and heating value were investigated. The gas production rate reached 53.4% of the product weight during gasification of crude glycerin. Glycerin gasification produces gas with a relatively medium heating value of 13.14 MJ/m³. The maximum hydrogen mole fraction of 43.6% was obtained under the bed temperature of 750°C. A scenario of integrating crude glycerin gasification system and Stirling engine generators was created for potential electricity generation. An economic analysis model was developed to determine the cost of electricity generation. Using a 5 Mg/day fluidized bed gasifier integrated with four Stirling engine generators, electricity could be potentially generated with the cost of $0.142/kWh.

Keywords: Glycerin; Gasification; Stirling engine; Electricity generation