Treatment of High Water-Content Solvents via Chemical Looping Combustion Process
| Autor: | Yi-Kang Wu, 吳翊康 |
|---|---|
| Rok vydání: | 2018 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 106 The chemical-looping combustion (CLC) is a novel combustion process with the high combustion efficiency and direct separation of carbon dioxide during combustion reaction. The reaction rate is affected by the design of the reaction system, the degree of fluidization of oxygen carrier, and the contact time between oxygen carrier and fuel gas significantly. In this study, two kinds of high-water-content organic waste, IPA and EKC, were selected as the fuel for chemical-looping combustion, which was carried out in the 1kWth and 100kWth interconnected fluidized bed with two kinds of oxygen carriers, Australian and Brazilian iron ore, respectively. The behavior of fluidization of the oxygen carrier and the distribution of the oxygen carrier in fuel and air reactors were affected by the gas flow rates of the fuel reactor, air reactor, and the loop seal. The pressure drop of air reactor was measured and applied to estimate the solids circulation rate. The composition of the exhaust gas for the chemical-looping combustion process was measured to determine the combustion efficiency and fuel conversion under different temperatures. In this system, the fuel reactor and loop seal were in the form of bubbling bed, and the air reactor was a fast fluidized bed. The oxygen carriers were transported stably between two reactors to achieve high CO2 selectivity and purity. In 1kWth interconnected fluidized bed, the experimental results showed that the optimal operation parameters were obtained at 5 L/min of air to AR, 3.5 L/min of nitrogen to LS and 4L/min of nitrogen with 1mL/min of solvent to FR. The maximum solvent feeding rate was 4 mL/min with 1L/min of nitrogen as carrier gas. It was achieved with over 70% of CO2 selectivity and purity. In 100kWth interconnected fluidized bed, the experimental results indicated that the optimal operation parameters were obtained at 80 L/min of air to AR, 40 L/min of nitrogen to LS, and 50 L/min of nitrogen with 23 mL/min of solvent to FR. The methane was the major product of exhaust as feeding 160 ml/min of solvent to FR. The vaporization rate of the solvent was the key step in this combustion process. The more complete vaporization of liquid fuel through the preheating device is, the more stable and smoother the degree of fluidization is. In conclusion, the complete vaporization of solvent was achieved with over 70% of CO2 selectivity. As the feeding rate of liquid fuel was too large, the oxygen-supply rate by oxygen carriers was insufficient, resulting in the generation of coke. The entire system thus played a role as thermal cracking system, and the molar fraction of methane and hydrogen was higher than 60%. The system could still be kept at a stable fluidization condition. The analysis results of physic characteristics for oxygen carriers indicated that the iron ore was suitable material for interconnected fluidized beds with a lifetime over 1000 h. The whole results showed the practicality of the chemical-looping combustion process for treatment of high-water-content organic waste. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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