Equilibrium Model For Gasification Research Articles

Influence of Fuel Moisture Content and Reactor Temperature on the Calorific Value of Syngas Resulted from Gasification of Oil Palm Fronds

Biomass wastes produced from oil palm mills and plantations include empty fruit bunches (EFBs), shells, fibers, trunks, and oil palm fronds (OPF). EFBs and shells are partially utilized as boiler fuel while the rest of the biomass materials like OPF have not been utilized for energy generation. No previous study has been reported on gasification of oil palm fronds (OPF) biomass for the production of fuel gas. In this paper, the effect of moisture content of fuel and reactor temperature on downdraft gasification of OPF was experimentally investigated using a lab scale gasifier of capacity 50 kW. In addition, results obtained from equilibrium model of gasification that was developed for facilitating the prediction of syngas composition are compared with experimental data. Comparison of simulation results for predicting calorific value of syngas with the experimental results showed a satisfactory agreement with a mean error of 0.1 MJ/Nm3. For a biomass moisture content of 29%, the resulting calorific value for the syngas was found to be only 2.63 MJ/Nm3, as compared to nearly double (4.95 MJ/Nm3) for biomass moisture content of 22%. A calorific value as high as 5.57 MJ/Nm3 was recorded for higher oxidation zone temperature values.

The Gibbs Free Energy Gradient Method for RDF gasification modelling

Starting from an equilibrium model for gasification, this research group has devised a new mathematical model, the so called Gibbs Free Energy Gradient Method Model (GMM). This model permits to bypass the semi-qualitative view, typical of equilibrium models, which assume very restrictive hypotheses such as equilibrium state for all the reactions involved in gasification process, complete conversion of carbon matter, gasification products in gas phase only. GMM model overcomes these limitations providing a quantitative point of view, even though the hypothesis of no tar production affects both models.GMM model has been applied to RDF gasification, supplying reliable results in the gasification process analysis. Model computations in terms of gas yield, gas composition, low heating value and H2 yield, have been compared with literature results, showing that computed data are in good agreement with experimental ones.

Equilibrium modeling of gasification: Gibbs free energy minimization approach and its application to spouted bed and spout-fluid bed gasifiers

Spouted beds have been found in many applications, one of which is gasification. In this paper, the gasification processes of conventional and modified spouted bed gasifiers were considered. The conventional spouted bed is a central jet spouted bed, while the modified spouted beds are circular split spouted bed and spout-fluid bed. The Gibbs free energy minimization method was used to predict the composition of the producer gas. The major six components, CO, CO 2, CH 4, H 2O, H 2 and N 2, were determined in the mixture of the producer gas. The results showed that the carbon conversion in the gasification process plays an important role in the model. A modified model was developed by considering the carbon conversion in the constraint equations and in the energy balance calculation. The results from the modified model showed improvements. The higher heating values (HHV) were also calculated and compared with the ones from experiments. The agreements of the calculated and experimental values of HHV, especially in the case of the circular split spouted bed and the spout-fluid bed were observed.

Equilibrium modeling of gasification: a free energy minimization approach and its application to a circulating fluidized bed coal gasifier

Equilibrium modeling of gasification: a free energy minimization approach and its application to a circulating fluidized bed coal gasifier

Equilibrium modeling of gasification: a free energy minimization approach and its application to a circulating fluidized bed coal gasifier

A non-stoichiometric equilibrium model based on free energy minimization is developed to predict the performance of gasifiers. The model considers five elements and 44 species in both the gas and solid phases. The gas composition and heating values vary primarily with temperature and the relative abundance of key elements, especially carbon, hydrogen and oxygen. Pressure only influences the result significantly over a limited temperature range. The model predicts the onset of formation of solid carbon where the gas composition becomes insensitive to additional carbon. The carbon formation boundary is plotted in C–H–O ternary diagrams as a function of temperature and pressure. When the experimental carbon conversion is introduced, the kinetically modified equilibrium model gives good predictions of the gas composition from an air-blown pressurized circulating fluidized bed gasifier for two coals. The role of water, including both fuel moisture and steam injection, is examined based on a water balance on the feed and product gas to evaluate the steam demand.