| Summary: | 碩士 === 國立臺灣科技大學 === 化學工程系 === 103 === In this work, the feasibility of the application of rice husk ash as inert support for iron-base oxygen carrier for chemical looping combustion (CLC) process and the design of inter-connected fluidized bed were investigated, respectively. The purposes of application of husk ash are the reuse of agricultural waste and the decrease in manufacture cost of oxygen carrier. The iron-based oxygen carriers with particle size between 0.177-0.297 mm were obtained via mechanical mixing, pelleting, and crushing processes, respectively. The properties of ferrosilicon oxide during CLC reaction were characterized and the effects of metal additives of oxygen carrier on CLC activity were investigated. The redox activities of oxygen carrier were first evaluated in a thermo-gravimetric analysis (TGA) system, where 10 vol% of syngas and air were applied as reductant and oxidant, respectively. The ferrosilicon oxygen carrier was further tested in a fluidized bed at 900℃ for 11h continuously. The results indicated that this oxygen carrier exhibits good reactivity and thermal stability.
In part of CLC kinetic analysis, the experiment data in reduction stage indicated the reaction behavior is similar to a steady state of continuous stirred tank reactor in the beginning period. The design equation is thus used to fit the experimental data for the estimation of kinetic parameters. The results showed the reduction from Fe2O3 to Fe2O3 in CO atmosphere is a diffusion-controlled reaction. The reaction order of Fe2O3 is 2 and the reduction rate is majorly affected by the concentration of oxygen carrier.
The third part of this work was focused on the design of inter-connected fluidized bed for CLC system. A cold model of 1 kW system is designed and established completely, consisting fuel reactor (FR), loop-seal (LS), air reaction (AR), and cyclone. The effects of gas flow rate and solid content on circulation of oxygen carrier were studied by analyzing the pressure drop of each part. A stable circulation of oxygen carried can be reached with applying 10, 6, and 20 L/min in FR, SL, and AR, respectively.
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