What does CLCS stand for?
Chemical looping combustion (CLC) is a flameless combustion technology where there is no direct contact between air and fuel. The CLC process utilizes oxygen from metal oxide oxygen carrier for fuel combustion. The products of CLC are CO2 and H2O. Thus, once the steam is condensed, a relatively pure steam of CO2 is produced ready for sequestration. The many benefits of this combustion process are that it does not produce NOx , its production of a sequestration ready CO2 stream does not require additional separation units, and there is no energy penalty or reduc-tion in power plant efficiency.
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The combustion and re-oxidation properties of direct coal chemical-looping com-bustion (CLC) over CuO, Fe
2O3, Co3O4, NiO, and Mn2O3 were investigated by using thermogravimetric analysis (TGA) and bench-scale fixed-bed flow reactor studies. When coal/metal oxide was heated either in nitrogen or carbon dioxide (CO2), weight losses were observed due to partial pyrolysis and coal combustion by metal oxides. Among various metal oxides evaluated, CuO showed the best reaction properties: CuO can initiate the reduction reaction as low as 500 oC and complete the full com-bustion at 700 oC. In addition, the reduced copper can be fully re-oxidized by air at 700 oC. The combustion products formed during the CLC reaction of coal/metal oxide mixture are CO2 and water, while no carbon monoxide was observed. Multi-cycle TGA tests and bench-scale fixed-bed flow reactor tests strongly supported the feasibility of chemical-looping combustion of coal by using CuO as an oxygen carrier. The interactions of flyash with metal oxides were investigated by X-ray diffraction and thermodynamic analysis. Overall, the results indicated that it is feasible to develop chemical-looping combustion with coal by metal oxides as oxygen carriers. Reaction mechanism studies and measurement of rate parameters necessary for reactor design work have also been completed. Benefits
Chemical looping combustion can lead to increased power efficiency. CLC produces
The majority of the work performed to date on CLC has been performed using gaseous fuels. There are only limited studies with oxygen carriers used to combust solid fuels such as coal. Those few studies that have been performed using coal suggest that more experimental information is needed. Development of oxygen carriers that have stable performance during multiple cycles and understanding the reaction mechanism and other process parameters are critical for the success of the CLC process.