Analysis of the Impact of Rdf Combustion on Cement Clinker Quality in a Superstoichio-Metric Oxy-Fuel Atmosphere by Cfd Simulations

ABSTRACT

Superstoichiometric oxygen combustion (i.e. the oxygen content during combustion is larger than required for the complete conversion of the fuel), also called pure-oxy-fuel, is a novel concept to reduce CO₂ emissions from the cement clinker production. In the current contribution, we examine in a simulation study the influence of superstoichiometric combustion in combination with the use of refuse-derived fuel (RDF) of different composition and particle size on process parameters and cement clinker quality in the rotary kiln. A comparison with a standard fuel, namely lignite, and a conventional air-fired kiln is presented. The specific models developed to determine the flight and combustion behavior of RDF particles, which are of complex shape and significantly larger than pulverized coal, are described. The simulations conducted show that some RDF fractions react only partially in the gas phase due to their relative large size. Unburnt RDF particles reach the clinker bed, where they continue to react. In addition, for RDF, gas-phase temperature and the clinker temperature are different along the kiln length compared to coal, influencing the local mineralogical reaction in the clinker bed. However, in summary, similar clinker qualities could be obtained also compared to a standard air-fired kiln.

KEYWORDS:

• Oxy-fuel
• superstoichiometric
• cement clinker quality
• refuse derived fuel
• CFD simulations

Acknowledgements

The authors thank the DFG (German Research Foundation) project number 215035359 TRR 129 for its support through CRC/Transregio 129 “Oxyflame: development of methods and models to describe solid fuel reactions within an oxy-fuel atmosphere”. Gefördert durch die Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 215035359 - TRR 129.

The authors report there are no competing interests to declare

Disclosure statement

No potential conflict of interest was reported by the author(s).