Michalis Agraniotis

Advantages and Possibilities of Solid Recovered Fuel Cocombustion in the European Energy Sector

The 1999/31 Elemental Carbon Directive sets strict rules on the disposal of untreated municipal solid waste in the European Union countries and forces a reduction of the biodegradable quantities disposed off to landfills up to 35% of the amount produced in 1995 in the coming decade. More environmentally friendly waste management options shall be promoted under the framework of the Community Waste Strategy ([96] 399 Final). In this context, the production and thermal use of solid recovered fuels (SRFs), derived from nonhazardous bioresidues and mixed- and mono-waste streams, could be a key element in a future waste management system. Within the scope of the European Demonstration Project, RECOFUEL, SRF cocombustion was demonstrated in two large-scale lignite-fired coal boilers at RWE power station in Weisweiler, Germany. As a consequence of the high biogenic share of the cocombusted material, this approach can be considered beneficial following European Directive 2001/77/EC on electricity from renewable energy sources (directive). During the experimental campaign, the share of SRF in the overall thermal input was adjusted to approximately 2%, resulting into a feeding rate of approximately 25 t/hr. The measurement campaign included boiler measurements in different locations, fuel and ash sampling, and its characterization. The corrosion rates were monitored by dedicated corrosion probes. The overall results showed no significant influence of SRF cocombustion on boiler operation, emissions behavior, and residues quality for the thermal shares applied. Also, no effect of the increased chlorine concentration of the recovered fuel was observed in the flue gas path after the desulfurization unit.

Efficient CHP-Plant Configuration for District Heating Systems Utilizing Low-Rank Coals

AbstractThe present study assesses different lignite-fired plant configurations for combined heat and power (CHP) production for use in district heating (DH) networks, in terms of environmental, te...

Co-firing Solid Recovered Fuels (SRFs) with brown coal in large-scale pulverised fuel power plants – a simulation approach

The results of the numerical simulations performed in a pulverised fuel boiler co-firing coal and Solid Recovered Fuels (SRFs) are presented. SRFs are initially modelled as a mixture of two different fractions (biogenic and plastic) and further simplifications are proposed to save computational expenses. The SRF submodels are validated with available data obtained from a laboratory-scale combustion facility. The furnace of a 600 MWe brown coal plant is further simulated. The respective boundary conditions are obtained from a performed large-scale measurement campaign during an SRF co-firing demonstration in the specific boiler. The results of the baseline case are in good agreement with the available experimental data for the large-scale boiler. A number of fuel and process-related combustion parameters is further examined, including the co-firing thermal share, injection locations and the Particle Size Distribution (PSD) of SRF particles. Computational Fluid Dynamics (CFD) modelling in large-scale boilers can be a reliable and efficient tool towards predicting specific changes of the combustion behaviour. It is particularly valuable when the intended investigations cannot be easily realised on a large scale, such as increasing the co-firing thermal share or modifying the injection locations of alternative fuels.