(178e) Feasibility of Integration of Chemical Looping Combustion (CLC) in IGCC Systems: High Pressure Clc Experiments with CH4 and Syngas

            The
effect of elevated pressure on chemical looping combustion using nickel and
copper oxygen carriers was studied in order to evaluate the feasibility of
integration of CLC into IGGC systems. Increasing the operating pressure of an
IGCC + CLC system increases the thermal efficiency of the process, while
decreasing the compression energy demand for high pressure CO₂ recovery.^[1]
Methane and syngas combustion experiments were conducted in a high-pressure
fixed bed reactor, sketched in Figure 1, at system pressures up to 10 bar.
Consistent data were achieved over multiple cycles of chemical looping for both
oxygen carriers, indicating successive cycle regenerablity. The effect of
pressure on the oxidation and reduction kinetics was studied for both oxygen
carriers in order to propose reaction kinetics, based on the experimental data.
Characterization of the oxygen carriers after successive cycles was performed
via SEM, XRD, BET and XPS, indicating significant structural changes as the
result of the high pressure. Figures 2 and 3 show experimental results of the
reduction step of both oxygen carriers at different system pressures and
temperature of 800 ºC. A
significant increase in CO₂ selectivity is observed at the
high-pressure experiments, which is especially clear for the experiments with
Cu oxygen carrier. In the case of the Ni-based oxygen carrier carbon formation
during reduction is reduced indicating a significant change in the carbon
formation and consumption kinetics. These observations were analyzed using a
fixed-bed reactor model indicating promising applicability of CLC for
industrial CO₂ separation.

Table
1: Experimental Conditions

Figure
1: Fixed-bed chemical-looping
setup used in this work.

Figure 2: Reduction of  NiO/Al₂O₃ and
CH₄/Ar in a fixed-bed reactor at 800 °C at 1, 5 and 10 bar including
the solid carbon deposition.

Figure 3: Reduction of  NiO/Al₂O₃ and
CH₄/Ar in a fixed-bed reactor at 800 °C at 1, 5, and 10 bar .

Acknowledgement: This material is
based upon work supported by the National Science Foundation

under Grant No. 1054718.

References:

[1]
IPCC Special
Report on Carbon Dioxide Capture and Storage; Cambridge University Press: New York, 2005;
available on the web athttp://www.ipcc.ch.