(409a) Advances in Autothermal Reformer Development

Advances in autothermal reformer development

At the Forschungszentrum Jülich, at the
Institute of Energy and Climate Research (IEK-3), intensive research and
development in the field of reactors for autothermal reforming (ATR) of diesel
fuel and kerosene was performed within the last 15 years. It is described in a
number of scientific papers. Most reactors have in common that they are
equipped with a pressure swirl nozzle for cold fuel injection. They all have a
fuel evaporation chamber, in which fuel is vaporized and mixed with steam, as
well as an air mixing area, in which air is injected and blended with steam and
evaporated fuel. The core component of any of Jülich’s
autothermal reforming reactors is the catalyst. In most cases, it is a
bimetallic RhPt species, which is coated on an Al₂O₃-CeO₂
washcoat, which in turn is deposited on a monolithic cordierite substrate. Steam
is generated in an internal device for heat exchange using the waste heat from
the product gas flow of the autothermal reforming reaction. Figure 1
illustrates these common characteristics of Jülich’s
ATRs.

Figure 1          Basic layout of Jülich’s
reactors for autothermal reforming of diesel fuel and                   kerosene

This contribution
deals with Jülich’s recent technical and scientific advance
in the field of reactors for autothermal reforming. This reactor generation is
denoted as ATR 12.

ATR 12 is
a consistent progression of ATR AH2, which was recently published in [1]. It is reported in this paper that the
improvements of ATR AH2 in comparison to former ATR reactor generations
from Jülich consisted of an additional pressure swirl
nozzle for the injection of cold water and a steam generation chamber. As a
result, no external process configuration for steam supply was necessary any
more. Additionally, the cross-sectional area of the steam generator in
ATR AH2, through which also a significant air flow is fed to the reformer,
was increased, while in parallel its length was reduced. Thereby, the pressure drop
of the steam generator drastically decreased. These modifications in the
autothermal reformer design are not decisive for the stand-alone operation of
the reformer, but very beneficial from the fuel cell system perspective since
they lower the parasitic losses caused by the compressor for air supply and make
the system layout simpler. For ATR 12, this way to consider important
technical requirements for the design and construction being imposed by the
fuel cell system was continued. For ATR 12, the technical execution of the
internal steam generator was substantially changed and further improved. The
coiled tubing for transferring the waste heat from the product gas flow of
autothermal reforming to the stream of saturated steam coming from the catalytic
burner of the fuel cell system was substituted by concentric shells, in which
turbulence inserts were placed to improve the heat exchange properties of the
new construction. This modification aims at an additional decrease in the
pressure drop in this part of the reactor and a homogenization of the media
streams, when they enter the fuel evaporation chamber. Apart from the above
mentioned turbulence inserts, the concentric shells also offer enough space for
the incorporation of an electric heating wire. This modification provides the
option of fast and autonomous start-up of the autothermal reformer. In this
respect, Figure 2 shows the specific design of Jülich’s
recent reactor type for autothermal reforming ATR 12.

Figure 2          Specific design of Jülich’s
recent reactor type for autothermal reforming                                     ATR 12

Three
different experimental procedures for fast heat up of ATR 12 and
additional steady-state experiments are presented in this contribution. Steady-state
experiments aimed at validating the concept for heat management of ATR 12.
Critical temperatures (internal steam, fuel evaporation chamber, air mixing
area, to water-gas shift reactor) and product gas concentrations (H₂,
CO, CO₂, CH₄, ethane, ethene, propene and benzene) of
ATR 12 are presented as a function of the reformer load and the mass
fraction of cold water to the nozzle on the top side of the reformer.

[1]          J. Pasel, R.C.
Samsun, A. Tschauder, R. Peters, D. Stolten, A novel reactor type for
autothermal reforming of diesel fuel and kerosene, Applied Energy 150 (2015)
176-184.