Investigation of chemical looping combustion by solid fuels. 1. Process analysis
- Western Kentucky University, Bowling Green, KY (United States). Institute for Combustion Science and Environmental Technology
This paper is the first in a series of two, where we present the concept of a CLC process of solid fuels using a circulating fluidized bed with three loop seals. The riser of this circulating fluidized bed was used as the oxidizer of the oxygen carrier; one of the loop seals was used as the reducer of the oxygen carrier and the separator for ash and oxygen carrier, and the other two loop seals were used for pressure balance in the solid recycle process. Pressure profiles of recycled solids using this process are presented in detail. For the development of an oxygen carrier, we focused on the establishment of a theoretical frame of oxygen transfer capability, reaction enthalpy, a chemical equilibrium, and kinetics. Analysis results indicated that Cu-, Ni-, and Co-based oxygen carriers may be the optimum oxygen carriers for the CLC of solid fuels. Thermodynamic analysis indicated that CO{sub 2} can be concentrated and purified to at least 99% purity for the gas-solid reaction mode or even higher for the solid-solid reaction mode on the basis of the selected oxygen carriers. A Cu-based oxygen carrier is the choice that has the potential to make the reducer self-sustaining or autothermal because of its exothermic nature during reduction. This would be beneficial for simplifying the operation of the reducer. The tendency of the Cu-based oxygen carriers to agglomerate can be eliminated by decreasing the operating temperature in the CLC system. In the second part of the series, we will evaluate the reduction kinetics of selected Cu-based oxygen carriers by coal and other 'opportunity solid fuels' using a simultaneous differential scanning calorimetry-thermogravimetric analysis to simulate a microreactor, using an X-ray diffractometer and a scanning electron microscope to characterize the solid residues, and a thermogravimetric analysis coupled with mass spectra to characterize the evolved gas compositions. 46 refs., 5 figs., 2 tabs.
- OSTI ID:
- 20813307
- Journal Information:
- Energy and Fuels, Vol. 20, Issue 5; Other Information: wei-ping.pan@wku.edu; ISSN 0887-0624
- Country of Publication:
- United States
- Language:
- English
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