Utilization of waste fuel in cement industry

Abstract

Utilization of Solid Recovered Fuels (SRF) in the clinker process of cement plants has become state of the art. In this paper, legal requirements, technical specifications as well as production, quality, quality assurance and utilization of Refuse Derived Fuels (RDF) in the cement industry are reported. When a multiple stage process is applied in a SRF processing plant, a premium quality SRF for the main burner at kiln outlet and a medium quality SRF for the secondary firing system at kiln inlet, can be produced. Before a RDF goes toco-incineration, in Austria two parallel regimes of legal limits have to be fulfilled, namely input limits forheavy metals in the unburnt waste fuel (laid down in the national Waste Incineration Ordinance (WIO) 2002) aswell as output limits for the emissions from the combustion process (laid down in the Best Available Techniques (BAT) guidelines for cement industry and EU wide and national regulations). Additional specifications,including well defined particle size (d95), heating value (LHV), water content [%], ash content [%], chlorine content [%], bulk density [kg m-3], etc. are usually requested by the receivingco-incineration plant, before a quality assured SRF is accepted as alternative fuel. As reported in this paper, the thermal substitution rate (of fossil fuel by RDF) in Austrian cement industry already has reached about75%. Even 100% substitution of fossil fuel seems to be basically possible, when an optimized feedstock mix isfed.