(583dk) Chemical-Looping With Oxygen Uncoupling of Coal in a Spouted Bed

Authors: 
Zhou, Z., University of Connecticut
Du, S., University of Connecticut
Fischer, A., University of Connecticut
Han, L., University of Connecticut
Bollas, G. M., University of Connecticut



The objective of this study is to explore the potential of
chemical-looping with oxygen uncoupling (CLOU) for coal. Theoretical models for
chemical-looping combustion and unique experimental facilities are utilized for
this proof-of-concept study.  Chemical-looping refers to indirect
combustion and reforming processes for power generation and/or hydrogen
production taking place in two reactors (a Reducer and an Oxidizer) with
inherent CO2 separation. Combustion is accomplished in the Reducer reactor
using an oxygen carrier (metal oxide) instead of air in traditional combustion.
The exhaust stream of the Reducer consists mainly of CO2 and H2O;
therefore, upon condensation of steam, CO2 is captured without
requiring an expensive CO2 separation unit. The metal oxides are
re-oxidized with air in the Oxidizer reactor. Of particular interest to the
combustion of solid fuels is chemical-looping with oxygen uncoupling, which
enables O2 to be dissociated from Cu oxides, thereby overcoming the
slow solid-solid reduction reactions in chemical-looping combustion. To achieve
excellent mixing of coal with oxygen carrier and subsequent fly ash/oxygen
carrier separation via entrainment, a conical spouted-bed (Figure 1) reactor is
explored. The experimental setup includes a bench-scale spouted bed reactor
connected to a Flourier transform infrared (FTIR) spectrometer and an Agilent
5975C mass selective detector for gas product composition analysis in real
time. The hydrodynamics of the spouted-bed are modeled following the basic
principles of the Kunii and Levenspiel [1,2] 3-phase model modified for application to spouted-beds.

The focus of this poster is to provide a proof-of-concept of coal chemical-looping,
accomplished by optimal design of a spouted-bed reactor, and simulate and
analyze the experimental results of chemical-looping reduction in spouted-bed
reactors.  The potential of in-situ ash separation via entrainment is
explored and showcased in the bench-scale setup.

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

Acknowledgement:
This material is based upon work supported by the National Science Foundation
under Grant No. 1054718.

[1]     
D. Kunii, O. Levenspiel, Bubbling bed model: model
for the flow of gas through a fluidized bed, I & EC Fundamentals. 7 (1968)
446¨C452.

[2]     
D. Kunii, O. Levenspiel, Bubbling bed model for
kinetic processes in fluidized beds: Gas-Solid Mass and Heat Transfer and
Catalytic Reactions, I & EC Process Design and Development. 7 (1968)
481¨C492.

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