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Computational Modelling of Biomass Gasification for Hydrogen Production in a Large Circulating Fluidized Bed Reactor
Kordi, Feras
Kordi, Feras
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Description
A Master of Science thesis in Chemical Engineering by Feras Kordi entitled, “Computational Modelling of Biomass Gasification for Hydrogen Production in a Large Circulating Fluidized Bed Reactor”, submitted in May 2023. Thesis advisor is Dr. Yassir Makkawi. Soft copy is available (Thesis, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).
Abstract
The worldwide date palm waste production is estimated to be around 1.8-4.2 million tons per year, out of this 70%−90% is produced in the Middle East and North Africa. Approximately, only 10% of this waste is recycled, while the rest is sent to landfills. In contribution to the development of bioenergy technology and reducing the negative impact associated with landfill disposal, this study presents a computational model and predictions of date palm waste steam gasification in a large-scale Circulating Fluidized Bed (CFB) (475,000 tons/year), with the capability of in-situ CO₂ capture by using calcium oxide as a sorbent material. The pyrolysis was implemented using a single-step devolatilization reaction with the kinetics derived experimentally using TGA data. The gasification reactions and kinetics implemented were obtained from the open literature. The base case results suggest that date palm waste steam gasification is of high potential to produce hydrogen-rich gas (up to 46.4 mol% H₂) of high calorific value (HHV > 21.62 MJ/m³) and low tar content (<22.6 g/Nm³). The quality of the product gas was found to be greatly enhanced by thermal cracking of tar, homogeneous methane steam reforming, and water-gas shift reactions. The calcium oxide sorption, implemented in the model as a first-order reaction with a rate constant defined by an Arrhenius law, has been found to be highly effective in carbon dioxide capture, reaching nearly 90-95 % elimination of CO₂ at the optimized operating condition. The proposed process is expected to play a major role in energy diversity in the Gulf and MENA regions as well as in minimizing waste going into landfills.