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Review: Step by Step Towards Alternative Fuels – part one

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World Cement,

Some 80 participants from more than 20 countries joined together in Vienna on 6 – 8 May for the Loesche Seminar, hosted by A TEC and co-sponsored by Scheuch. The topic of the seminar was ‘Step by step towards alternative fuels’ and over the course of two days representatives from A TEC, Aixergee, A TEC Greco, Scheuch, MVW Lechtenberg and Holcim Eastern Europe presented papers on cement industry solutions to increase the use of alternative fuels and reduce the impact on process quality and emissions.

Day one

After a warm welcome from Dr Thomas Loesche, Matthias Mersmann, who is both Executive Technical Director for Loesche and Managing Director of Aixergee, the company he founded and which was bought by Loesche in 2013, took the podium to introduce the logical steps to increase alternative fuels use. Mr Mersmann noted that there is no homogenous solution to the use of waste fuels because waste is heterogenous. He pointed to so-called fluff – i.e. dried, preprocessed municipal solid waste-derived fuel from high calorific fraction – as being the most standardised waste-derived fuel available. In Europe, this is the preferred form of alternative fuel and for the most part high quality fluff was the focus of the seminar.

Mr Mersmann took the audience through the steps of introducing alternative fuels to the cement pyroprocess: where it can be injected, the thermal substitution rate (TSR) that can be achieved, and the necessary plant modifications at the various stages, all the way up to 99% TSR, at which point fossil fuels would be used for startup only. This presentation introduced delegates to many of the special equipments and processes that would be highlighted during the seminar and plant tours, including the Rocket Mill, the ReduDust, and the FlexiFlame EcoPro kiln burner. He also highlighted the value of an experienced partner in achieving a successful result with alternative fuel usage.

Dr Stefan Kern, A TEC Production & Services GmbH (also a Loesche company), then took to the stage to outline A TEC’s solution to reduce NOX below 200 mg/Nm3. Dr Kern pointed out that NOX is closely related to discussions of alternative fuels because both fuel composition and plant configuration impact NOX formation. NOX can be reduced by bringing down the temperature of combustion and reducing the amount of air in the combustion zone. He suggested that low-NOX burners are less effective in the cement industry than in other industries, due to their potential impact on production quality. He suggested instead that staged combustion in an inline precalciner can produce the required atmosphere to reduce NOX, and furthermore that the greater the content of volatile matter in the fuel, the better the staged combustion process performs. A TEC recommends staged combustion plus SNCR combined with CFD optimisation to achieve NOX reduction below 200 mg/Nm3.

Next up to speak were Dr Ernst-Michael Sipple from Holcim Eastern Europe and Johannes Müllner, A TEC Production & Services GmbH, who gave a joint presentation on the ReduDust concept, which converts bypass dust to a saleable product (salt), and moreover leaves a chlorine free bypass dust that can be completely utilised in the cement production process. This leads to a waste-free bypass system.

Article continues in part two. This article is taken from the June issue of World Cement. Subscribers can download the full issue by logging in here. Written by

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