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Nowadays, the high share of electricity production from renewables drives coal-fired power plants to adopt a more flexible operation scheme and, at the same time, maintain flue gas emissions within respective standards. A 500 kWth pulverized coal furnace was used to study pre-dried lignite combustion or co-combustion as an available option for these plants. Bituminous coal from Czech Republic and pre-dried lignite from Greece were blended for the experiments. Particle emissions measurements with a heated Electrical Low Pressure Impactor (ELPI+) and Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS) analyses were performed. The effect of the pre-dried lignite proportions in the fuel feed and the combustion conditions regarding the combustion air staging were the two parameters selected for this study. Skeletal density values were measured from the cyclone prior to the impactor. Results are depicted with respect to the aerodynamic and Stokes diameter for impactor stages. The presence of pre-dried lignite in the fuel blend lowers the particle matter (PM) PM2.5, PM1 and PM0.1 emissions, thus having a positive impact on ESP’s fractional and overall efficiency. The staged combustion air feed reduces the particle emissions in all cases. Sulfur content follows a pattern of higher concentration values for finer particles.

Refuse-derived fuels (RDF) are a category of alternative fuels produced as byproducts from the process of waste management plants. RDF can be utilized for heat and power production, contributing to the waste hierarchy set by European Union. However, the need for standardization of RDF becomes gradually important in SouthEastern Europe, where the market for waste recovered fuels is under development. The application of certification and quality management schemes in the waste treatment and fuel production processes, along with the use of a new terminology, solid recovered fuels may enhance public acceptance and promote the thermal utilization of this resource in industrial facilities. In the present work, a sampling and analysis campaign of RDF produced at a mechanical and biological treatment facility in Athens, Greece, took place. The sampling and analysis were carried out according to the standards of CEN/TC 343. The sampling period lasted 1 year, resulting in 20 samples. Proximate, ultimate analysis, chlorine and heavy metals' content were carried out. Furthermore, a technical and economic assessment was carried out, in order to propose realistic solutions for the improvement of the produced RDF quality and the plants' viability. Two sets of scenarios are assessed with techno-economic criteria referring to different technical solutions. At the end of the study, a step-by-step approach is proposed, which may guarantee the economic feasibility of the proposed plant retrofitting project and a pay-back period adjusted to the extent of the retrofitting measures to be decided.

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