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

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.