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@BOOK{Melchior:136285,
      author       = {Melchior, Tobias},
      title        = {{U}ntersuchungen zur {O}berfächenspannung von
                      {K}ohleschlacken unter {V}ergasungsbedingungen},
      volume       = {96},
      school       = {RWTH Aachen},
      type         = {Dr.},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {PreJuSER-136285},
      isbn         = {978-3-89336-690-3},
      series       = {Schriften des Forschungszentrums Jülich. Reihe Energie und
                      Umwelt / Energy und Environment},
      pages        = {XVII, 270 S.},
      year         = {2011},
      note         = {Record converted from JUWEL: 18.07.2013; RWTH Aachen,
                      Diss., 2011},
      abstract     = {In the context of CO$_{2}$-emission-induced global warming,
                      greenhouse gases resulting from the production of
                      electricity in coal-fired power plants gain increasing
                      attention. One possible way to reduce such emissions is to
                      gasify coal instead of burning it. The corresponding process
                      is referred to as Integrated Gasification Combined Cycle and
                      allows for the separation of CO$_{2}$ before converting a
                      synthesis gas into electrical energy. However, further
                      improvements in efficiency and availability of this plant
                      technology are needed to render the alternative generation
                      of electricity sensible from an economic point of view. One
                      corresponding approach introduces hot gas cleaning
                      facilities to the gasification plant which guarantee a
                      removal of slag particles from the synthesis gas at high
                      temperatures. The development of such filters depends on the
                      availability of data on the material properties of the coal
                      ash slags to be withdrawn. In this respect, the surface
                      tension is a relevant characteristic. Currently, the surface
                      tension of real coal ash slags as well as of synthetic model
                      systems was measured successfully by means of the sessile
                      drop and the maximum bubble pressure method. With regard to
                      the sessile drop technique, those experiments were conducted
                      in a gasification-like atmosphere at temperatures of up to
                      1500 ◦C. Furthermore, the pressure inside the experimental
                      vessel was raised to 10 bar in order to allow for deriving
                      the influence of this variable on the surface tension. In
                      contrast, maximum bubble pressure trials were realised at
                      atmospheric pressure while the gas atmosphere assured inert
                      conditions. For performing sessile drop measurements, a
                      corresponding apparatus was set up and is described in
                      detail in this thesis. Three computer algorithms were
                      employed to calculate surface tensions out of the photos of
                      sessile drops and their individual peformance was evaluated.
                      A very good agreement between two of the codes was found
                      while the third one produces heavily scattering output. The
                      measurement arrangement was run in an almost fully automated
                      fashion which resulted in an immense amount of obtained
                      surface tension data. Maximum bubble pressure experiments
                      were conducted at the University of Osaka, Japan, on
                      selected real ash samples. Due to a far longer time required
                      for determining bubble pressures in comparison to taking
                      drop pictures, only a small number of temperatures could be
                      studied abroad. The results show the surface tension to be
                      in the range from 200 mN/m to 500 mN/m which is in
                      accordance with data taken from the literature. While three
                      discrete temperature intervals of particular slag behaviour
                      could be identified in sessile drop experiments, results of
                      maximum bubble pressure trials suggest the surface tension
                      to be lower under inert conditions compared to a reducing
                      atmosphere. The outcomes generated in Japan additionally
                      show a better agreement to surface tensions forecasted by
                      model calculations. Fe$_{2}$O$_{3}$ being considered to have
                      a pronounced influence on slag characteristics is made
                      responsible for such observations. As soon as pressure is
                      applied, the surface tension is found to decrease
                      significantly. In order to visualise the data obtained by
                      means of the sessile drop technique, regression functions
                      were employed that can be implemented into future design
                      calculations on hot gas cleaning facilities.},
      cin          = {IEK-2},
      ddc          = {500},
      cid          = {I:(DE-Juel1)IEK-2-20101013},
      typ          = {PUB:(DE-HGF)3},
      url          = {https://juser.fz-juelich.de/record/136285},
}