Alternative fuels

Many years of experience in production, handling, transportation and utilization are available in the field of fossil fuels, and there are established methods and procedures for their characterization, for the preparation of samples and for their analysis, whereas the development of methodology specifically for alternative fuels, for the description of their conveyance and fuel properties, remains in its infancy. For this reason, DI MATTEO Förderanlagen GmbH & Co. KG, of Beckum, Germany, in cooperation with the Fraunhofer Institute for Environmental, Safety and Energy Technology UMSICHT, held a workshop on the subject of “The use and characterization of alternative fuels” (Fig. 1). More than 60 experts accepted the invitation to the workshop in Oberhausen/Germany.

Following speeches of welcome by Dr. Luigi Di Matteo (Fig. 2), of the DI MATTEO group, and Dr. Thomas Marzi (Fig. 3), of Fraunhofer UMSICHT, Dr. Di Matteo opened the proceedings with an address on “The state-of-the-art in the use of alternative fuels”. At over 50  %, Germany is the global leader in the use of refuse-derived fuels (RDF) in the cement industry. It is, however, necessary to take into account the special physical properties of these fuels for their handling. This is true throughout the process chain, starting from reception of the fuels, via preparation, storage, transportation and metering, up to including input into the process. Prof. Dr. Sabine Flamme (Fig. 4), of the Gütegemeinschaft Sekundärbrennstoffe und Recyclingholz e.V. (Federal Quality Association for Derived Fuels and Wood Recycling), spoke on the topic of “Quality assurance in alternative fuels”, emphasizing the already strictly quality-controlled refuse-derived fuels of the high-calorific-value fraction, which can, for example, be used in alternative-fueled power generating plants. The revision of the relevant limits is currently under discussion, and they have to be defined on the basis of calorific value. She was followed by Julia Behling (Fig. 5), of Fraunhofer UMSICHT, who provided information on the “Analysis of biomasses in the two-stage pyrolysis furnace” (co-author: Philipp Danz, ­Fraunhofer UMSICHT). The volatiles are released in the first stage, and oxidized in the second, the aim being a more accurate and more comprehensive determination of combustion behaviour. The first series of papers was concluded by Burkhard Krüger (Fig. 6), of Fraunhofer UMSICHT, with deliberations on “Modelling of the pneumatic conveying and handling properties of alternative fuels”. He focused on the Zephyros project, in which the injection behaviour of alternative fuels is firstly to be experimentally investigated, and then depicted by means of models. He affirmed that only the inclusion of the various particle geometries will permit verification of the experimental results in the models. This project was conducted in cooperation with DI MATTEO and founded by the the German ­
Federation of Industrial Research Associations AiF (Arbeitsgemeinschaft industrieller Forschungsvereinigungen “Otto von ­Guericke” e. V.).

Following the short midday break, Ulrich Strotkamp (Fig. 7), of DI MATTEO Förderanlagen GmbH & Co. KG, continued with his paper on “Characterization of the physical properties of alternative fuels” (co-author: Dr. Günther Marotz, DI MATTEO Förderanlagen GmbH & Co. KG). He noted that only precise material characterization can make possible rational ­system and equipment design. Unnecessarily high safety margins, and thus system over-dimensioning, can then be avoided. Dr. ­Siegmar Wirtz (Fig. 8), LEAT, Ruhr-University Bochum, followed with a paper on “The combustion of alternative fuel particles”. He pointed out that the individual properties of the particles play a significant role in this context. Dr. Kai Keldenich (Fig. 9), of Evonik Energy Services GmbH, spoke on „Options for energy-route utilization of refuse and refuse-derived fuels in various system types“. He examined the combustion, fouling and corrosion behaviour of alternative fuels used in various types of power plants. The “Use of alternative fuels in the cement industry” was then examined by Dr. Karl Lampe (Fig. 10), of Polysius AG. Rising coal prices and the CO₂ emission trading system are boosting demand for alternative fuel concepts in many European countries. A large number of cement companies have already drafted their own alternative fuel strategies (including  Holcim, with its “Geocycle”, for example). Lampe drew attention to the fact that modified technologies (such as the Polflam burner, or combustion chambers such as the Prepol staged reactor, for example) are necessary for the successful use of alternative fuels. He was followed by Dr. Thomas Marzi, of Fraunhofer UMSICHT (co-author: Manfred Kühl, of ThyssenKrupp Xervon Energy GmbH), speaking on “Investigations of quality and aging behaviour of bottom ash”. Grate ash must firstly be aged, in order to permit complete reaction of the content substances prior to further use as, for example, a substrate for highway engineering. Investigations may demonstrate that grate ash from alternative-fueled power generating plants reacts similarly to that from waste-incineration facilities.

There was abundant opportunity to discuss aspects of the papers following their conclusion and during the breaks. The event provided, all in all, a good overview of current topics and research opportunities in the field of refuse-derived fuels. The excellent and positive response forms the basis for the planning of follow-up events – ZKG INTERNATIONAL will publish all details in good time!