A simulation model has been developed using the Aspen Plus computer simulation code for predicting performance of small scale updraft moving bed gasifiers, attractive in mid term for reducing dependence on oil and gas and promoting the use of alternative fuels. The Aspen model schematizes the gasifier into several different zones: coal preheating and drying, devolatilization, gasification, combustion and oxidant preheating, assuming char gasification at thermodynamic equilibrium. The model can be used to evaluate the mass and energy balance in each zone and the main characteristics of the syngas produced by the gasification process (composition, mass flow, temperature, lower heating value, etc.), for given coal composition and coal, steam and oxidant (air or oxygen-enriched air) mass flows. Gasifier mass and energy balances and raw gas composition also influence downstream gas cleaning and treatment systems and they need to be preliminarily estimated for the design, analysis and performance evaluation of the overall system (gasification, gas cleaning, desulphurisation, CO-shift conversion, CO2 and hydrogen separation, etc.). Here the model is used to predict the performance of an updraft moving bed gasifier fed by low sulphur coal and high ash, high sulphur Sulcis coal from Sardinia. The gasifier is part of a pilot gasification and gas treatment plant for hydrogen production under construction at the Sotacarbo Research Centre in Sardinia. The results obtained with the Aspen model compare favourably with the expected performance specified by the gasifier manufacturer.
Process analysis and performance evaluation of updraft coal gasifiers
TOLA, VITTORIO;CAU, GIORGIO
2007-01-01
Abstract
A simulation model has been developed using the Aspen Plus computer simulation code for predicting performance of small scale updraft moving bed gasifiers, attractive in mid term for reducing dependence on oil and gas and promoting the use of alternative fuels. The Aspen model schematizes the gasifier into several different zones: coal preheating and drying, devolatilization, gasification, combustion and oxidant preheating, assuming char gasification at thermodynamic equilibrium. The model can be used to evaluate the mass and energy balance in each zone and the main characteristics of the syngas produced by the gasification process (composition, mass flow, temperature, lower heating value, etc.), for given coal composition and coal, steam and oxidant (air or oxygen-enriched air) mass flows. Gasifier mass and energy balances and raw gas composition also influence downstream gas cleaning and treatment systems and they need to be preliminarily estimated for the design, analysis and performance evaluation of the overall system (gasification, gas cleaning, desulphurisation, CO-shift conversion, CO2 and hydrogen separation, etc.). Here the model is used to predict the performance of an updraft moving bed gasifier fed by low sulphur coal and high ash, high sulphur Sulcis coal from Sardinia. The gasifier is part of a pilot gasification and gas treatment plant for hydrogen production under construction at the Sotacarbo Research Centre in Sardinia. The results obtained with the Aspen model compare favourably with the expected performance specified by the gasifier manufacturer.
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