388202 Feasibility of Integration of Chemical Looping Combustion (CLC) in IGCC Systems: High Pressure Clc Experiments with CH4 and Syngas

Monday, November 17, 2014: 4:55 PM
M102 (Marriott Marquis Atlanta)
Oscar Nordness, Zhiquan Zhou and George M. Bollas, Department of Chemical & Biomolecular Engineering, University of Connecticut, Storrs, CT

ááááááááááá 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]á 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 ║C. 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

Oxygen Carrier

20% NiO/Al2O3, 36% CuO/SiO2

Load

2.2 grams

Reactor Dimensions

I.D. 9.6 mm, height 482 mm

Total Flow

100 sccm

Temperature

1073 K

Pressure

1, 5, 7.5, 10 bar

Oxidation

8 min, 10% O2/Argon

Reduction (CH4)

2-3 min, 10% CH4/Argon

Reduction (syngas)

3 min, 5% CO, 5% H2 /Argon

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

Figure 2: Reduction of áNiO/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 áNiO/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]á IPCC Special Report on Carbon Dioxide Capture and Storage; Cambridge University Press: New York, 2005; available on the web athttp://www.ipcc.ch.

 


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