Optimisation of biofuel production from municipal green waste (MGW) pyrolysis using ASPEN plus simulation model

Biofuel generation from municipal green waste through pyrolysis can reduce emissions and contribute to energy security. The purpose of this paper is to develop a simulation model of biofuel production from municipal green waste (MGW) using ASPEN plus simulation software and optimise production as a function of operating variables. A sample of MGW was pyrolysed in a short sealed rotary furnace with attached off gas condenser to produce charcoal and condensate products. Then the condensate was further pyrolysed to produce bio-oil and syngas products. A four-stage steady state simulation model has been developed for process simulation. It was found from the experiment that about 20% bio-oil, 40.8% biochar and 29.8% syn-gas can be achieved from MGW. In the first stage moisture content of green waste feed was reduced. In the second stage biomass was decomposed according to its elemental decompositions. In the third stage, condensate material was separated. Finally the pyrolysis reactions have been modelled using gibbs-free energy minimisation approach. Feedstock’s ultimate and proximate analyses data were used in ASPEN plus simulation as input parameters. The model has been validated with experimentally measured data. The results show a good agreement between simulation and experimental results The validated model was used to optimize the biofuel production as a function of operating variables such as moisture content, particle size, temperature and process heat air-fuel ratio. The optimisation results have been presented, analysed and discussed in this paper.