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Item Multizone model of a refused derived fuel gasification: A thermodynamic Semi-empirical approach(Elsevier, 2022-05) Sheth, Pratik N.Substitution of fossil fuels by sustainable energy sources has raised attention worldwide. Refuse derived fuel (RDF), which is the combustible fraction of Municipal solid waste (MSW), is used as an alternative fuel through combustion route. The gasification of RDF is gaining importance due to the operational issues of RDF combustion. The multizone RDF gasification model is developed to predict syngas composition in the present study. A stoichiometric approach is followed for modelling the pyrolysis and combustion zone. The reduction zone is modelled as a cylindrical fixed bed reactor with a uniform cross-sectional area. The developed set of differential equations is solved using MATLAB to predict the syngas properties. The novelty lies in the fact that the model can predict the output of each zone satisfactorily since the model assumptions are more realistic and cater to the heterogeneous nature of RDF. The impact of Equivalence ratio (ER), moisture content and reduction zone length on the performance of the gasifier are evaluated. The optimum values of lower heating value (LHV), gas yield, cold gas efficiency (CGE) and carbon conversion efficiency (CCE) for three different RDF at optimum ER is determined. Notably, 90% of the conversion is achieved within 60% length of reduction zone for all three types of RDF at all ERs. Predicting syngas properties can pave the way for the process integration of RDF gasification-based syngas in various industrial applications.Item Tar cracking enhancement by air sparger installation in the combustion zone of the downdraft gasifier(Elsevier, 2022-11) Sheth, Pratik N.In the present article, experimental studies are performed on Imbert downdraft gasifier using two different air distribution systems (two-nozzle and air-sparger) for the combustion zone. A novel air distribution system (air-sparger) is designed to supply uniform air across the combustion zone for achieving uniform temperature and enhancing the tar cracking. The effect of operating parameters (Equivalence ratio, temperature, air flow rate, and biomass consumption) on the tar cracking and producer gas compositions are investigated. Tar is measured in the producer gas before and after the gas cleaning units using a stack monitoring system. The experiments are performed by varying the airflow rate between 3 and 7 Nm3 h−1, and the equivalence ratio varies from 0.24 to 0.38. The operating parameters and air-sparger have significantly influenced the zone's temperature, producer gas composition, and the tar content in the producer gas. The maximum temperature of the combustion zone and reduction zone increases from 764 to 975 °C and 467 to 760 °C respectively with the air-sparger compared to the two-nozzle conventional air distribution system at the airflow rate of 7 Nm3 h−1. The lower heating value of the producer gas and the cold gas efficiency of the gasifier increased from 4.28 to 4.37 MJ Nm−3 and 48.55–55.05%, respectively, with the air-sparger. The incorporation of air-sparger reduces tar in producer gas from 23.95 to 0.97 g Nm−3 before gas cleaning unit at the airflow rate of 7 Nm3 h−1. Air-sparger has shown the adequate potential to enhance tar cracking and improve the overall gasifier performance.