% IMPORTANT: The following is UTF-8 encoded.  This means that in the presence
% of non-ASCII characters, it will not work with BibTeX 0.99 or older.
% Instead, you should use an up-to-date BibTeX implementation like “bibtex8” or
% “biber”.

@PHDTHESIS{Seebold:841492,
      author       = {Seebold, Sören},
      title        = {{E}influss der {K}ristallisation auf das {F}ließverhalten
                      oxidischer {S}chmelzen},
      volume       = {393},
      school       = {RWTH Aachen},
      type         = {Dissertation},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2017-08536},
      isbn         = {978-3-95806-268-9},
      series       = {Schriften des Forschungszentrums Jülich Reihe Energie $\&$
                      Umwelt / Energy $\&$ Environment},
      pages        = {168 S.},
      year         = {2017},
      note         = {RWTH Aachen, Diss., 2017},
      abstract     = {Numerous technical applications in the energy and
                      metallurgical industries demand a fundamental knowledge of
                      the flow of slags. In particular, the operation of an
                      entrained flow gasifier is challenging as the slag has to be
                      reliably discharged. The slag consists of unburned inorganic
                      matter, usually oxides. Crystallization in this oxide melt
                      influences the flow behavior of the slag because of the
                      occurring precipitates. In this study the mechanisms and
                      impact of crystallization on the flow of oxide slags were
                      investigated. For this purpose, isothermal viscosity
                      measurements were conducted on fossil and renewable solid
                      fuel slags in order to examine the rheological evolution
                      over time caused by the crystallization. It has been
                      demonstrated that the evolution of viscosity of a
                      sub-liquidus melt depends strongly on time, as well as on
                      temperature and composition. Using a rotational
                      high-temperature viscometer, it was found that the
                      crystallization during flow could be separated into three
                      time regimes: a lag-time, in which the undercooled melt
                      behaved as an Arrhenius-liquid; the kinetic-driven
                      crystallization accompanied by an increase of the viscosity;
                      and, finally, the rheological equilibrium that is
                      represented by a constant viscosity. Furthermore, an
                      increase of viscosity caused by crystallization was
                      accompanied by a shift from Newtonian to non-Newtonian flow;
                      here, shear thinning flow indicated the existence of
                      precipitates. SEM was used to examine the crystalline
                      precipitates. The evolution of flow was used to create
                      time-temperature-transformation diagrams. It was observed
                      that an increase of the degree of supercooling decreases the
                      incubation as well as the crystallization period. The
                      crystallization of the oxide melt follows the classical
                      theory of crystallization. Moreover, it was shown that the
                      change of viscosity might be used as morphological
                      information to describe kinetic parameters. The conclusions
                      from the experimental results regarding the influence of
                      crystallization on the flow of oxide melts were transferred
                      to an empirical model. The model considers the physical
                      influence of the crystals and the chemical change of the
                      bulk composition caused by the crystallization. Therefore,
                      the concept of the resulting relative viscosity was
                      introduced, in order to describe the physical and chemical
                      effects of crystallization. The evolution of viscosity from
                      the metastable to the equilibrium state was described by a
                      kinetic theory. The results of the model correlate well with
                      the experimental observations.},
      cin          = {IEK-2},
      cid          = {I:(DE-Juel1)IEK-2-20101013},
      pnm          = {111 - Efficient and Flexible Power Plants (POF3-111)},
      pid          = {G:(DE-HGF)POF3-111},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      url          = {https://juser.fz-juelich.de/record/841492},
}