• Harris, David
• Hla, San

Abstract

An entrained-flow gasifier model has been developed by combining existing mechanistic reaction models with new knowledge of gasification reaction fundamentals.Features of this model are the simplified consideration of the complex flow fields in entrained flow gasifiers, and the integration of new knowledge and understandings of intrinsic char gasification kinetics and how they interact with char structure to dictate the rates of char gasification at high temperatures. This model has been validated using data from pilot-scale testing of a suite of four Australian coals in a 5 MWth entrained flow gasifier. Model calculations of gas phase concentrations under the different stoichiometry ranges for four coals agree well with the data obtained from the pilot scale tests. Due to some simplified assumptions made in this model, particularly in the consideration of fluid dynamics and heat-losses, it is important to perform a parametric sensitivity analysis investigating the effect of varying the values of those parameters on model performance in order to ascertain the validity of the approach.In this paper, an analysis was carried out to determine the sensitivity of this model to changes in four input parameter values. The results showed that model predictions of carbon conversion and cold gas efficiency are significantly affected by varying the recirculation ratio. The three key model parameters used in this simplified ‘ideal chemical reactors’ approach (namely length of the near burner zone, the recirculation ratio, and the jet expansion angle) and the inner wall temperature are shown to significantly affect the exit syngas temperatures. The sensitivity analysis provided a good understanding of the effects of model parameters on the performance of a reference gasifier used in this study.

Topics

• impedance spectroscopy
• Carbon
• gas phase
• gasification