000885822 001__ 885822 000885822 005__ 20240711092250.0 000885822 0247_ $$2Handle$$a2128/26325 000885822 0247_ $$2URN$$aurn:nbn:de:0001-2020120102 000885822 0247_ $$2ISSN$$a1866-1793 000885822 020__ $$a978-3-95806-506-2 000885822 037__ $$aFZJ-2020-04113 000885822 041__ $$aEnglish 000885822 1001_ $$0P:(DE-Juel1)171689$$aSchupsky, Jan Peter$$b0$$eCorresponding author$$gmale$$ufzj 000885822 245__ $$aCrystallisation of Oxidic Gasifier Slags$$f- 2020-12-01 000885822 260__ $$aJülich$$bForschungszentrum Jülich GmbH Zentralbibliothek, Verlag$$c2020 000885822 300__ $$aIII, 127, XXII S. 000885822 3367_ $$2DataCite$$aOutput Types/Dissertation 000885822 3367_ $$0PUB:(DE-HGF)3$$2PUB:(DE-HGF)$$aBook$$mbook 000885822 3367_ $$2ORCID$$aDISSERTATION 000885822 3367_ $$2BibTeX$$aPHDTHESIS 000885822 3367_ $$02$$2EndNote$$aThesis 000885822 3367_ $$0PUB:(DE-HGF)11$$2PUB:(DE-HGF)$$aDissertation / PhD Thesis$$bphd$$mphd$$s1606831935_21209 000885822 3367_ $$2DRIVER$$adoctoralThesis 000885822 4900_ $$aSchriften des Forschungszentrums Jülich. Reihe Energie & Umwelt / Energy & Environment$$v514 000885822 502__ $$aRWTH Aachen, Diss., 2020$$bDissertation$$cRWTH Aachen$$d2020 000885822 520__ $$aGasification is a flexible technology that has the potential to support the transition from a fossil fuelled to decarbonised energy supply system. During gasification, an oxidic residue is produced thatis named as slag. Slag flow needs to be constant in a gasifier, but a high viscosity impairs the flow behaviour. The phenomenon of crystallisation has such effect, yet is only barely understood. Viscosity of slag can be modelled and therefore predicted. However, no sufficient model exists to calculate the viscosity of partly crystallised slags. A sufficient data source of crystal morphology data is required to enable the application of an improved viscosity model for partly crystallised slags. In this study, the crystallisation characteristics of four synthetic gasifier slags (ST-D-2, HKT, SOM-1,and HKR) have been investigated. Initially, the synthetic slag systems have been blended from high purity compounds. Their compositions are mostly based on real coal slags that have been investigated in previous studies. The slag systems were analysed on their melting and solidification behaviour and so, the temperature parameters for the following experiments were set. Equilibrium calculations were conducted with FactSage Equilib programme to predict solidus and liquidus temperatures, as well as the crystallised phases. As a first experiment, high temperature viscosimetry was performed on the four slag systems. ST-D-2 and HKT slags were identified as high viscous, HKR as a low viscous and SOM-1 as an intermediately viscous slag. Viscosity measurements revealed non-Newtonian behaviour and the presence of crystals in the slag. The evolution of crystallisation was analysed by quenching and CLSM (confocal laser scanning microscopy) experiments. The resulting slag samples were analysed via microscopy, X-ray diffraction and SEM (scanning electron microscopy). ST-D-2, HKT, and SOM-1 slag displayed significant growth of anorthite (CaAl$_{2}$Si$_{2}$O$_{8}$)crystals. Several more phases crystallised in these slags, such as cristobalite (SiO$_{2}$), clinopyroxene((Ca,Mg,Fe)(Si,Al)$_{2}$O$_{6}$), and olivine ((Ca,Mg,Fe)$_{2}$SiO$_{4}$). In the HKR slag, melilite (Ca$_{2}$(Al,Mg)(Si,Al)$_{2}$O$_{7}$)was the dominating crystal phase, followed by olivine and spinel ((Mg,Fe)AlO$_{4}$). For the high viscous slags, time-temperature-transformation (TTT) diagrams indicated an incubation time of single hours. SOM-1 slags incubation time varied between double digit minutes to single hours and lastly HKR slag displayed very rapid, partly instant crystallisation. The crystal morphologies of anorthite, spinel, olivine, and melilite could be defined based on the sample analysis of quenching and CLSM experiments. Anorthite was defined as a tetragonal prism with variation in the elongation, spinel formed idiomorphic octahedrons, olivine crystallised aselongated, equiaxed bipyramids and melilite formed large rectangular bipyramids. To gather relevant morphology data, the crystals were measured on their length and width to quantify their presence with respect to the applied temperature. In total, 1022 individual crystals were measured for the quantification. Generally, the crystals tend to grow larger at higher temperatures, which is in agreement with the crystallisation theory. The morphology was compared with crystallisation of real slag samples from PiTER reactor (TU Munich, HotVeGas project). Anorthite and spinel were found in PiTER slag with identical morphologies, as provided for the synthetic slag samples. This accordance is an application-related proof that the investigations on crystal morphologies performed in this study are reproducible and realistically display crystallisation processes in gasifiers. 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