Download Validation of the FSCK radiation model for oxycoal combustion

Validation of the FSCK Radiation Model for Oxycoal Combustion
*A. G. Clements1, K. J. Hughes1, M. Pourkashanian1, M. E. de Tejada2, S. Grathwohl2,
J. Maier2, G. Sheffknecht2
Energy2050, University of Sheffield, Sheffield, United Kingdom, S10 2JT
Institute of Combustion and Power Plant Technology (IFK), University of Stuttgart, Pfaffenwaldring
23, 70569 Stuttgart, Germany
1
2
Abstract for oral presentation:
One of the key challenges in the deployment of oxyfuel and carbon capture
technologies is associated with the cost and efficiency penalty that these regimes will impose
over conventional processes. Modelling can provide a means to optimise the combustion
process, and appropriate use of modelling techniques will help in the design of economically
feasible carbon capture technology. Thermal radiation is the most significant mode of heat
transfer at combustion temperatures, however modelling the spectral variation in the
radiative properties of combustion gasses is challenging. The increased concentrations of
radiatively participating species under oxyfuel conditions, principally H2O and CO2, increases
the role of gas-phase absorption and emission of thermal radiation. The full-spectrum
correlated k (FSCK) model has been previously shown to achieve high accuracy evaluations
of radiative quantities within a time-frame suitable for CFD calculations.
Pilot scale facilities provide much needed validation data for modelling. This study
compares CFD predictions against experimental measurements carried out at IFK’s semi
industrial scale 500 kWth furnace, which was operated under air-fired and oxyfuel conditions.
The down fired test furnace is fitted with a flue gas recycle line so that the oxyfuel
combustion regime can be employed with a real flue gas recycle. In-flame species and
temperature profiles were measured for both firing conditions, alongside radiative heat
fluxes to the furnace wall.
The modelling approach to radiative transfer in this study combines the FSCK model
with Mie theory calculations of particle radiative properties. CFD calculations of air-fired and
oxyfuel combustion within the pilot-scale furnace are compared against the measurements of
radiative heat flux and in-flame temperature and species profiles. The results demonstrate
improved agreement with measured values for the radiative heat flux in both air-fired and
oxyfuel combustion when compared against the standard grey WSGG radiation model.
Keywords: oxyfuel combustion, radiation, CFD, FSCK
Acknowledgement: The research leading to these results has received funding from the
European Community's Seventh Framework Programme (FP7/2007-2013) under grant
agreement n° 268191.
* Corresponding author:
e-mail: [email protected]
Tel: +44 114 21 57277