Refuse Derived Fuel (RDF) production and gasification in a pilot plant integrated with an Otto cycle ICE through Aspen plus™ modelling: Thermodynamic and economic viability

This work deals with the development of a Refuse Derived Fuel (RDF) gasification pilot plant using air as a gasification agent. A downdraft fixed bed reactor is integrated with an Otto cycle Internal Combustion Engine (ICE). Modelling was carried out using the Aspen Plus™ software to predict the ideal operational conditions for maximum efficiency. Thermodynamics package used in the simulation comprised the Non-Random Two-Liquid (NRTL) model and the Hayden-O'Connell (HOC) equation of state. As expected, the results indicated that the Equivalence Ratio (ER) has a direct influence over the gasification temperature and the composition of the Raw Produced Gas (RPG), and effects of ER over the Lower Heating Value (LHV) and Cold Gasification Efficiency (CGE) of the RPG are also discussed. A maximum CGE efficiency of 57-60% was reached for ER values between 0.25 and 0.3, also an average reactor temperature values in the range of 680-700 °C, with a peak LHV of 5.8 MJ/Nm3. RPG was burned in an ICE, reaching an electrical power of 50 kWel. The economic assessment of the pilot plant implementation was also performed, showing the project is feasible, with power above 120 kWel with an initial investment of approximately US$ 300,000.