Abstract

Bottom ash samples were collected during four seasons from the largest lignite-fired power plant of Greece, named Agios Dimitrios. Dry sieving and particle size analysis were performed for all samples. Coarse fractions were initially examined by a stereo-microscope. Four fractions (>1.25, 0.63–1.25, 0.18–0.63, <0.18 mm) of each sample were created after homogenization and ground for analytical purposes. Thermogravimetry (TG/DTG), X-Ray Diffraction (XRD) and Energy Dispersive System (EDS) methods and proximate analysis were applied, along with the determination of Loss on Ignition (LOI) and calorific values. The mineral composition included mainly amorphous matter, quartz, plagioclase, calcite, gehlenite and micas and minor amounts of gypsum, anhydrite, portlandite, hematite, larnite, lime etc. The chemical analysis showed Si, Ca, and Al as major and Mg, Fe, S and K as minor chemical elements, indicating medium slagging and high fouling potential within the thermal chambers. Based on the analytical results, a potential utilization in concrete manufacturing is discussed. High amounts of unburnt carbon were determined in the coarse fractions (>1.25 mm) of all samples, indicating a problematic combustion within the chambers and a potential of reburning these coarse material in a waste to energy application.

中文翻译：

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希腊褐煤底灰样品的成分和热特性的时间变化

摘要

在四个季节中，从希腊最大的褐煤发电厂Agios Dimitrios收集了底灰样品。对所有样品进行干筛和粒度分析。最初通过立体显微镜检查粗级分。均质后将每个样品分成四个部分（> 1.25、0.63-1.25、0.18-0.63，<0.18 mm）并研磨以用于分析。应用了热重分析（TG / DTG），X射线衍射（XRD）和能量分散系统（EDS）的方法并进行了分析，并测定了灼烧减量（LOI）和发热量。矿物成分主要包括非晶质，石英，斜长石，方解石，方铅矿和云母以及少量的石膏，硬石膏，硅酸盐，赤铁矿，闪锌矿，石灰等。化学分析表明，Si，Ca，Al为主要元素，Mg，Fe，S和K为次要化学元素，表明热室内有中等结渣和高结垢的可能性。基于分析结果，讨论了在混凝土制造中的潜在利用。在所有样品的粗馏分（> 1.25 mm）中确定了大量未燃烧的碳，这表明室内的燃烧有问题，并且有可能将这些粗材料重新燃烧成废物用于能源。