Multiphase CFD-based models for chemical looping combustion process: Fuel reactor modeling
- ANL
Chemical looping combustion (CLC) is a flameless two-step fuel combustion that produces a pure CO2 stream, ready for compression and sequestration. The process is composed of two interconnected fluidized bed reactors. The air reactor which is a conventional circulating fluidized bed and the fuel reactor which is a bubbling fluidized bed. The basic principle is to avoid the direct contact of air and fuel during the combustion by introducing a highly-reactive metal particle, referred to as oxygen carrier, to transport oxygen from the air to the fuel. In the process, the products from combustion are kept separated from the rest of the flue gases namely nitrogen and excess oxygen. This process eliminates the energy intensive step to separate the CO2 from nitrogen-rich flue gas that reduce the thermal efficiency. Fundamental knowledge of multiphase reactive fluid dynamic behavior of the gas–solid flow is essential for the optimization and operation of a chemical looping combustor. Our recent thorough literature review shows that multiphase CFD-based models have not been adapted to chemical looping combustion processes in the open literature. In this study, we have developed the reaction kinetics model of the fuel reactor and implemented the kinetic model into a multiphase hydrodynamic model, MFIX, developed earlier at the National Energy Technology Laboratory. Simulated fuel reactor flows revealed high weight fraction of unburned methane fuel in the flue gas along with CO2 and H2O. This behavior implies high fuel loss at the exit of the reactor and indicates the necessity to increase the residence time, say by decreasing the fuel flow rate, or to recirculate the unburned methane after condensing and removing CO2.
- Research Organization:
- National Energy Technology Laboratory (NETL), Pittsburgh, PA, Morgantown, WV, and Albany, OR
- Sponsoring Organization:
- USDOE - Office of Fossil Energy (FE)
- DOE Contract Number:
- None cited
- OSTI ID:
- 933146
- Report Number(s):
- DOE/NETL-IR-2008-123; NETL-TPR-1829; TRN: US200814%%863
- Journal Information:
- Powder Technology, Vol. 183, Issue 3; ISSN 0032-5910
- Publisher:
- Elsevier B.V.
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CIRCULATING SYSTEMS
COMBUSTION
COMPRESSION
FLOW RATE
FLUE GAS
FLUIDIZED BED REACTORS
FLUIDIZED BEDS
GASES
HYDRODYNAMIC MODEL
KINETICS
METHANE
NITROGEN
OPTIMIZATION
OXYGEN
REACTION KINETICS
THERMAL EFFICIENCY
TRANSPORT
CHEMISORPTION
PENTACENE
SILICON
SORPTIVE PROPERTIES
MORPHOLOGY
ADSORPTION HEAT
Chemical looping combustion
Multiphase hydrodynamics
CO2 capture
Circulating fluidized bed