Evaluation of an improved code for the performance of AFBCs

Selçuk, Nevin
Oymak, O
In a previously developed system model, bed and freeboard models were coupled for the continuous combustion of lignite particles of widely varied size distributions, burning in their own ash in a fluidised combustor. This was modified to incorporate a) a procedure for faster computation of particle-size distributions (PSDs) without any sacrifice of accuracy; b) an energy balance on char particles, for determining temperature variation with particle size; and c) assumption of plug flow for the interstitial gas. The improved computer code was evaluated by being applied to prediction of the behaviour of a pilot-scale fluidised-bed combustor, followed by comparison of its predictions with measurements and also with the results predicted by the previous code. The computer code replaces the conventional numerical integration of the analytical solution of population balance with direct integration in ODE form, by using a powerful integrator LSODE; this results in a reduction of CPU time by two orders of magnitude. For the prediction of physically expected variation of char hold-up with excess air, an energy balance on char particles must be incorporated into the system model. Comparison of the predicted and measured temperature and concentration profiles shows that the present code produces better agreement than the previous one in bed-concentration profiles.


Analysis of material collected on particles exposed to volatile matter of bituminous coal in a fluidized bed
Vural, H (1997-05-01)
The activity of fluidized bed particles towards the volatile matter of a bituminous coal was analysed by measurement of tar yield and the direct measurement of CO2 concentration in the exhaust gas from the devolatilization of bituminous coal particles in a laboratory-scale fluidized bed reactor. In a third approach, thermogravimetric analysis (t.g.a.) of the fluidizing particles was performed, indicating that calcium-containing particles exhibited the largest weight loss. In a fourth approach, a mass spectr...
Assessment of a model with char attrition for a bubbling atmospheric fluidized-bed combustor
Gogebakan, Y; Selçuk, Nevin (2004-05-01)
A comprehensive model, previously developed and tested for prediction of behavior of continuous fluidized-bed combustors, is extended to incorporate char attrition and is applied to the simulation of a 0.3 MegaWatt (MW) atmospheric bubbling fluidized-bed combustor burning lignites with high Volatile Matter/Fixed Carbon (VM/FC) ratios in their own ashes. The effect of this incorporation is assessed by comparing the predictions of the model with and without attrition with measurements. Favorable comparisons o...
Mathematical Modeling of a Bubbling Fluidized Bed Combustor Cofired with Lignite and Biomass
Külah, Görkem; Selçuk, Nevin (2010-01-01)
A comprehensive system model of fluidized bed combustor, previously developed and tested for the prediction of combustion behavior of fluidized bed combustors fired with lignite was extended for the modeling of cofiring of lignite with biomass by incorporating volatile release, char combustion, and population balance for biomass. The model predictions were validated against measurements taken on a Middle East Technical University 0.3 MWt Atmospheric Bubbling Fluidized Bed Combustor fired with lignite only, ...
Modeling of a bubbling AFBC with volatiles release
Selçuk, Nevin; Gogebakan, Y (2003-03-01)
comprehensive model for continuous combustion of lignite with wide size distribution burning in its own ash in an atmospheric bubbling fluidized bed combustor (ABFBC) has been presented and used to correlate the data from a 0.3 MW ABFBC test rig. The model consists of submodels for hydrodynamics, volatiles release and combustion, char combustion, particle size distribution, entrainment and elutriation and is based on conservation equations for energy and chemical species. The volatiles release model is base...
Assessment of improved banded model for spectral thermal radiation in presence of non-gray particles in fluidized bed combustors
Yaşar, Mehmet Soner; Ozen, Guzide; Selçuk, Nevin; Külah, Görkem (2020-07-01)
In this study, Bordbar's banded model is coupled with a 3-D radiation model based on method of lines (MOL) solution of discrete ordinates method (DOM) for modeling of radiative heat transfer in freeboard of METU 0.3 MWt ABFBC test rig where a typical Turkish lignite is fired with and without fly ash recycling. The accuracy and the computational efficiency of the model were assessed by benchmarking its predictions against banded SLW model. Furthermore, in order to show the effect of gas composition on predic...
Citation Formats
N. Selçuk and O. Oymak, “Evaluation of an improved code for the performance of AFBCs,” JOURNAL OF THE INSTITUTE OF ENERGY, pp. 31–50, 1997, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/53304.