Recent Progress in Refuse Derived Fuel (RDF) Co-processing in Cement Production: Direct Firing in Kiln/Calciner vs Process Integration of RDF Gasification

Abstract

Refuse-derived fuel (RDF) from municipal solid waste (MSW) is an alternative fuel (AF) partially replacing coal/petcoke in a calciner/kiln of cement plant. The maximum thermal substitution rate (TSR) achieved through RDF is 80–100% in the calciner, while it is limited to 50–60% in the kiln burner. Different AF pre-combustion technologies, advancements in multi-channel burners, and new satellite burners have supported high TSR. Extensive efforts in modelling kiln burner and calciner lead to enhance TSR. However, the cement industry faces operational issues such as incomplete combustion, increased specific heat consumption, reduced flame temperature, and kiln coating buildup. There is an interest in RDF gasification, a promising alternative to eliminate the operational issues of the cement industry, which needs to be integrated with the existing cement plant. The article reviews the integration of gasification in cement production and various experimental and modelling studies of the direct firing of AF/RDF in the kiln/calciner. The features and technology status of both approaches are compared. The different gasification integration technologies with varied configurations for cement plant calciner are highlighted. The article emphasizes the need to develop suitable calciner/kiln-gasifier models for predicting calciner output based on different RDFs.