| Summary: | 碩士 === 國立臺灣科技大學 === 化學工程系 === 104 === In a chemical-looping combustion (CLC) process, the solid circulation rate (GS) is a key parameter that is affected by the whole system design and operating conditions of oxygen carries. In this study, a 1 kWth cold flow model of interconnected fluidized bed for CLC system was established to investigate the transferring phenomena of gas and solid. The reactor type of air and fuel reactor are fluidized bed and bubbling bed, respectively. The oxygen carriers were prepared from the iron ore of Brazil. The effects of operation parameters, such as bed inventory, gas flow of air reactor and loop-seal, on the solid circulation rate were investigated. The gas flow rate to air reactor was kept at 20 L/min with variant major and secondary gas flow rates. The pressure distribution in each part of this system was monitored and the solid circulation rate was calculated from the pressure drop of raising tube. The optimal operation parameters was obtained via this experiment. The gas distribution ratio and seal effect of this designed loop-seal were further examined. The result indicated it exhibits the effective separating function for air and furl reactors. However, the trace gas was found in the exit of cyclone, indicating the sealing property of dipleg of cyclone was not sufficient. The attrition rate of oxygen carrier in this CLC system is measured. After 5 h of operation, 0.14 wt% of oxygen carrier was blown away, indicating the lifetime was 3571 h.
A 1 kWth hot prototype of CLC system was further established with using iron ore of Australia as oxygen carrier. The effect of secondary air flow in the air reactor on solid circulation rate was studied at 950oC. The data showed that the increase in secondary air flow rate will decrease the solid circulation rate. The data from hot prototype and cold model were not well consistent with each other. A partial ore was not circulated smoothly in the hot prototype, resulting in the generation of FeO phase. The shape of CLC reactors was obvious changed under the hot condition and it retarded the solid circulation. The design of hot prototype should be further improved for long-term operation.
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