Conversion of municipals waste into syngas and methanol via steam gasification using CaO as sorbent: An Aspen Plus modelling

The conversion of wastes specially (plastic and food waste) for energy and value-added products through gasification is under investigation. This investigation configures an integrated simulation process model for steam gasification, syngas treatment, methanol production and purification for plastic waste ((Polyethylene(PE) + polyethylene terephthalate (PET)), food waste (vegetable and fruits) and their blend using a simulation tool Aspen Plus®. The impact of three process parameters such as temperature (650–900 °C), steam/feedstock ratio (1.0–2.0) and CaO/feedstock ratio (0.5–2.0), on syngas composition and downstream product methanol. H₂ and methanol yield increases with the increase of temperature in all cases. In the case of plastic, H₂ and methanol yield were increased from 75.68 to 92.77 kmol/h and 709.60 to 960.13 kg/h respectively with the injection of steam flowrate. A similar H₂ and methanol yield trend was obtained for food and mixture of plastic and food waste with a little variation. In the case of food waste, methanol has ascending order and maximum final methanol production 476.56 kg/h at 1800 kg/h steam flowrate. The gas composition profile which define the H₂-CO/CO + CO₂ ratio increase from 1.27 to 1.88 governing methanol production for plastic. CaO is added to capture the CO₂ to get the augmented syngas composition for methanol production. The general trend of H₂ production was ascending, whereas methanol is descending with an increase of temperature and CaO flowrate for most cases. Maximum 978 kg/h MeOH noticed at temperature of 700 °C, steam flowrate of 1000 kg/h and CaO flowrate of 500 kg/h for plastic. Although, its flowrate extensively affected the CO and CO₂ flowrates that need to be optimized for a desired composition to maintain a good H₂-CO/CO + CO₂ ratio for methanol production.