Investigation Into Reactivity Of CaCu/FeCu Bi-component Oxygen Carrier In Chemical-looping Combustion

CO2 capture technologies, especially chemical-looping combustion(CLC) has drawn worldwide attention gradually when CO2 emission reduction is getting more and more important in the world. Study on chemical-looping combustion of solid fuels is particularly important to China which has rich coal resources. Solid fuel is directly mixed with oxygen carrier(OC), and thus realizes complete combustion by OC redox. The selection and improvement are very important in the study of the technology. In this thesis, CuO and inert materials were introduced to prepare CaCu OC and FeCu OC and the characteristic of the OCs was investigated in a fluidized bed. The main results are summarized as follows:(1) Calcium and copper compound oxygen carrierCalcium and copper compound OC were prepared with industrial grade materials natural anhydrite, bentonite and cupric nitrate, using mechanical mixing-prilling method. The calcium and copper compound OC didn't transmuted to inert material after the redox reaction, the active component was stable. The carbon conversion efficiency, the CO2 concentration and the combustion efficiency of coal were increased due to the addition of CuO. When the mass ratio of CaSO4 to CuO was 10:1.5, the OC CaCu1.5 exhibited higher reactivity at 850 oC, the carbon conversion efficiency and the average CO2 concentration increased to 91.27% and 89.34%. After ten times of cycle reactions with Shenmu coal, there was no sintering phenomenon, the average carbon conversion efficiency was above 93%, the average CO2 concentration was above 85% and the combustion efficiency of coal was above 86%. The ten redox tests demonstrated that the OC CaCu1.5 was featured by the high reactivity and excellent cycling stability.(2) Iron and copper compound oxygen carrierIron and copper compound OC were prepared with industrial grade materials attapulgite, ferric nitrate and cupric nitrate, using sol-gel method. The iron and copper compound OC didn't transmute into inert material after calcination and the reduction reaction. When the CuFe2O4/ATP OC reacted with Qujing coal, the carbon conversion rate and the reactivity was increased in pyrolysis reaction and combustion reaction. During the ten times cycle reactions between Qujing lignite and Cu Fe2O4/ATP OC, the CuFe2O4/ATP OC exhibited higher reactivity and excellent cycling stability at 850 oC while the carbon conversion efficiency and average concentrations of CO2 kept above 94% and 93%, respectively. OC particles exhibited superior abrasion resistance as OC particle size was more uniformed and had a lower wear rate during the cyclic reaction. The CuFe2O4/ATP OC has the advantage of widely flexibility and is more suitable for lignite, coffee grounds such kind of high-volatile fuel.