Chemical Looping Combustion (CLC) is a novel technology, which has the potential to significantly reduce costs associated with carbon capture. The CLC process produces a flue gas primarily consisting of CO_2 and H_2O. The CO_2 can be easily separated by condensing the H_2O, similar to an oxy-fuel process. However, unlike an oxy-fuel process, an air separation unit is not required. A solid "oxygen-carrier" is used to transport oxygen from the air to a separate fuel reactor thus eliminating the contact between air and fuel streams. Although the thermodynamics of the process look promising, the integration and control of the system needs to be demonstrated. At the US Department of Energy's (DOE) National Energy Technology Laboratory (NETL), a 50kWth chemical looping reactor (CLR) has been designed and fabricated. To support the operation and investigation of solids handling, a geometrically identical chemical looping reactor cold flow unit (CLR-CF) has also been constructed. These two units have been constructed to provide high quality data to aid in the continued development, model validation, and scale-up of chemical looping combustion systems. The general arrangement of the process consists of a 1) bubbling fluidized bed fuel reactor which drains into a 2) L-valve which transports the reduced solids to a 3) fluidized bed air reactor. Secondary air is injected into the air reactor to elutriate the oxidized solids into a 4) riser which transports the solids through the 5) crossover and into the 6) cyclone where the solids are separated from the air. The solids then travel through a 7) stand pipe into a 8) loop seal. Finally, the loop is completed when the solids overflow into another 8) stand pipe and re-enter the 1) fuel reactor. Both of the units have provided valuable information demonstrating the ability to control and determine key process performance indicators including solid circulation rates and fluidized bed heights. The CLR-CF unit has been used to collect a series of experiments at different operating conditions and with different materials, as well as provide validation data for L-valve modeling. The CLR has successfully demonstrated the ability to reach target temperatures of 1000°C and sufficient circulation rates. A technique for measuring the solid circulation rate has also been developed and applied successfully to both units. Chemical looping combustion has been demonstrated with natural gas as the fuel and an iron based oxygen carrier, hematite. Now that shakedown tests have been completed, the focus of research is turning towards the characterization of the performance of several metal oxide based oxygen carriers.
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