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@PHDTHESIS{Krekel:681994,
      author       = {Krekel, Daniel},
      othercontributors = {Stolten, Detlef and Wagner, Hermann-Josef},
      title        = {{B}etriebsstrategien für {B}renngaserzeugungssysteme zur
                      {A}nwendung in {HT}-{PEFC}-{H}ilfsstromaggregaten},
      volume       = {356},
      school       = {RWTH Aachen University},
      type         = {Dissertation},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH, Zentralbibliothek},
      reportid     = {RWTH-2017-00553},
      isbn         = {978-3-95806-203-0},
      series       = {Schriften des Forschungszentrums Jülich. Reihe Energie
                      $\&$ Umwelt},
      pages        = {1 Online-Ressource (IX, 265 Seiten) : Illustrationen,
                      Diagramme},
      year         = {2017},
      note         = {Druckausgabe: 2017. - Onlineausgabe: 2017. - Auch
                      veröffentlicht auf dem Publikationsserver der RWTH Aachen
                      University; Dissertation, RWTH Aachen University, 2016},
      abstract     = {This work set out to develop an operating strategy for fuel
                      processing systems combined with high-temperature polymer
                      electrolyte fuel cells (HT-PEFC). The operating strategy’s
                      focus was to prevent the deactivation of the water-gas shift
                      reactor’s (WGS) noble metal catalyst. The methodical
                      approach undertaken included researching of the subject on
                      two levels. Emphasis was placed on experimental
                      investigation at the system and catalyst levels. This work
                      was supplemented by model calculations. The experimental
                      results identified high gas hourly space velocities of
                      45,000 1/h and above as a first reason for an accelerated
                      activity drop of the catalyst. Presumably, the degradation
                      was caused by a blockage of the active catalyst centers by
                      reformate components or reaction intermediates like
                      carbonates/ formates. The second reason for deactivation was
                      incomplete fuel conversion in the autothermal reformer
                      (ATR). Higher hydrocarbons caused side reactions on the WGS
                      catalyst and resulted in a higher CO-concentration, as well
                      as accelerated deactivation. The operating strategy
                      comprises new methods to improve the fuel conversion during
                      startup/ shutdown. With the original methods, several
                      thousand ppmv higher hydrocarbons were observed. The new
                      strategies reduced the concentrations up to a factor of 10
                      during startup and up to a factor of 400 during shutdown.
                      Furthermore, the original catalyst A was displaced by a
                      second catalyst B, which turned out to be much more active
                      and stable. As a third part of the new operating strategy,
                      regeneration methods were developed. A short-term purge
                      (≈5 min) of the WGS-reactor after system shutdown with 80
                      lN/h air at ≈200 °C was enough to completely regenerate
                      the catalyst activity. The new operating concept was
                      validated by daily load profiles with the fuel HC-kerosene
                      and the CO threshold value of the HT-PEFC of 1.2 $vol.-\%$
                      (dry) was met. With three additional diesel fuels,
                      validation was not possible all of the time. In future, the
                      catalyst volume of the high-temperature shift stage (HTS)
                      must be doubled in order to lower the gas hourly space
                      velocity and decelerate the degradation occurring. Apart
                      from that, catalyst B showed no indication of irreversible
                      deterioration, even after ≈500 h of system operation,
                      including 20 startup/ shutdown cycles, concentrations of
                      higher hydrocarbons up to 3200 ppmv, as well as numerous
                      temperature peaks of up to 763 °C. The integration of the
                      system’s fuel cell and catalytic burner modules into the
                      new operating strategy is unproblematic and can take place
                      without adjustment. Correspondingly, the model calculations
                      could reveal that the energetic utilization of the rejected
                      reactor heat after shutdown is reasonable. With the
                      catalytic burner, a hot water quantity of 10 kg/h can be
                      supplied for 150 minutes. The developed operating strategy
                      constitutes the foundation of long-term operation without a
                      loss of performance, and is an incentive for further work on
                      the fuel processing system.},
      cin          = {413010},
      ddc          = {620},
      cid          = {$I:(DE-82)413010_20140620$},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      doi          = {10.18154/RWTH-2017-00553},
      url          = {https://publications.rwth-aachen.de/record/681994},
}