Chemical Looping Combustion
The discussion of CO2 output has risen to the forefront of many people’s minds in the world. Therefore, separation and sequestration of CO2 has become an important topic as well. Chemical-looping combustion is one viable solution to CO2 capture. By using a substance which has the ability to oxidize and reduce relatively efficiently oxygen may be inherently separated from air. The then oxidized carrier may be introduced to a fuel source. Once the carrier is reduced to its original state it may be looped back to the air reactor for reoxidation. Since the oxidizer is pure oxygen the product stream may be nearly pure CO2 and can be easily prepared for sequestration. The following diagram depicts a CLC process.
Figure 1: Diagram of a CLC reactor system. Reaction assumes a metal as an oxygen carrier and is depicted as Me. The fuel source is assumed to be a hydrocarbon.
The CLC system depicted above consists of two separate beds. The oxygen carrier is transported between the two reactors in either an oxidized or reduced form. Carrier transport may be facilitated by using a dual fluidized-bed system.
The ultimate objective of this research is to develop a new carbon-capture technology for fossil fuel through chemical-looping combustion and to transfer this technology to industry through a numerical simulation tool with quantified uncertainty bounds. The near-term research target for this project is to quantitatively identify reaction mechanisms and rates, explore operating options with a laboratory-scale bubbling bed reactor, develop process models and economics, and demonstrate and validate large-eddy simulation-direct quadrature method of moments (LES-DQMOM) simulation capabilities for a pilot-scale fluidized bed. Work is currently focused on two classes of oxygen carriers, one that merely undergoes a change in oxidation state, such as Fe3O4/Fe2O3 and one that is converted from its lower oxidation state by the by the release of oxygen on heating, i.e., CuO/Cu2O.