Abstract
The gasification process involves several reactions that occur simultaneously and are interrelated by several independent variables. Simulation tools can help us to understand the process behaviour and predict the efficiency and final composition of the products. In this work, two thermodynamic equilibrium models developed in Aspen Plus® software were assessed: a non-stoichiometric model based on the feedstock composition and on the most probable compounds expected from the results of the gasification process using minimisation of Gibbs free energy and a stoichiometric model based on a set of chemical reactions considered as the most relevant to describe the gasification process. Both models were validated with experimental data from a bubbling fluidised bed semi-pilot scale gasifier using pine kernel shells (PKS) as feedstock. The influence of temperature, stoichiometric ratio (SR) and steam to biomass ratio (SBR) were analysed. Overall, predictions of the gas composition and gasification efficiency parameters by the stoichiometric model showed better agreement to the experimental results. Our results point out the significance of an accurate description of the equilibrium composition of producer gas with the stoichiometric model for the gasification of biomass.
Highlights
The requirements to reduce greenhouse gas emissions entail the need to search for new eco-friendly alternatives [1]
Gasification experimental data obtained with pine kernel shells (PKS) in the bubbling fluidised bed reactor under different air–steam atmospheres were compared with simulation results to validate both models, stoichiometric and non-stoichiometric
The equilibrium models display similar trends to the experimental data and are in good agreement with the results reported in the literature [19,23]
Summary
The requirements to reduce greenhouse gas emissions entail the need to search for new eco-friendly alternatives [1]. Biomass is a renewable energy source and a carbon-neutral fuel; it brings benefits in terms of reduced NOx and SOx emissions and, it is considered one of the main alternatives to replace fossil fuels [2]. Biological and thermochemical, can be followed for the conversion of biomass into useful products [3]. Thermochemical routes have received more attention, the gasification technology [4]. The final composition depends on several factors such as biomass type, gasification technology or gasifying agent used The syngas is used to generate electricity, hydrogen, liquid fuels or chemical products
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