Modeling of syngas composition obtained from fluidized bed gasifiers using Kuhn–Tucker multipliers

Abstract

This work aims to develop a modified chemical equilibrium model to accurately determine the syngas (synthesis gas) composition obtained from fluidized bed gasifiers. In order to do so, an optimization method was applied to determine the correction factors which modify the chemical equilibrium constants, the carbon conversion efficiency and the enthalpy of reaction. The gasification agents considered for this study were: air, steam, airesteam, and airesteameoxygen. The optimization method used the KuhneTucker multipliers to obtain small RMS errors. A total of 76 experimental compositions of syngas were selected. Among these data 60 were used to obtain correlations for the correction factor, the carbon conversion efficiency and the enthalpy of reaction. Then, a modified chemical equilibrium model was formulated by a taking advantage of these correlations. The modified chemical equilibrium model was validated showing very good accuracy for the determination of the syngas composition, the RMS error were found to be between 0.94 and 4.84.

Characterization of syngas produced from biomass gasification

“…The produced gas contains primarily CO, CO2, H2, CH4 and N2 if air is used as a gasification medium [7]. Besides these, the gas also contains other components, mainly undesirables such as dust, tars, alkali, sulphur and nitrogen compounds, hydrogen chloride, hydrofluoride etc [8]. The greater content of volatile inflammable matter gives rise to the greater amount of hydrocarbons in a form of permanent gases such as ethylene, acetylene, benzene, toluene and xylene.…”

Empirical and chemical equilibrium modelling for prediction of biomass gasification products in bubbling fluidized beds

“…present in the producer gas. The lack of accuracy of CEMs for the prediction of the producer gas composition under certain operating conditions has also been recognized in other works [7,10,11,25], nonetheless, chemical equilibrium modelling is still the most commonly used approach for determining producer gas composition in biomass gasification [4,13], and has been intensively used for fluidized beds in recent years [10,13,24,[34][35][36]72]. Therefore, these results also indicate that the focus of modelling studies should be shifted from black-box chemical equilibrium modelling to other modelling approaches, such as approaches that integrate experimental knowledge.…”

Effect of Pyrolysis Reactions on Coal and Biomass Gasification Process

“…They also do not allow to use them reliably for other applications or reactor scales, primarily due to the accumulation of errors in underestimated reactions in equivalent pseudo-equilibrium constants or kinetic parameters. Models described in the literature are usually based on a one-stage approach, i.e., consider only a classical set of gasification reactions [7][8][9][10][11]. These models are used primarily for gasification carried out at temperatures much higher than 1000 • C, where the equilibrium conditions may be applied with a relatively good approximation.…”