Chemical-Looping Combustion with NiO and Fe2O3 in a Thermobalance and Circulating Fluidized Bed Reactor with Double Loops

详细信息    查看全文

• 作者：Sung Real Son and Sang Done Kim
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2006
• 出版时间：April 12, 2006
• 年：2006
• 卷：45
• 期：8
• 页码：2689 - 2696
• 全文大小：432K
• 年卷期：v.45,no.8(April 12, 2006)
• ISSN：1520-5045

文摘

For the chemical-looping combustion (CLC), readily available metal oxides (NiO, Fe₂O₃) for oxygen carriersand bentonite, TiO₂, and Al₂O₃ for the supports of the looping materials were selected. The reactivity of theoxygen carrier particles was determined in a thermobalance reactor under the reducing (CH₄) and oxidizing(O₂) conditions at 923-1223 K. The reactivity of NiO is higher than Fe₂O₃, and the particles supported onbentonite or Al₂O₃ produce higher reactivity than those on TiO₂. The reactivity of the metal oxide particlesincreases with increasing temperature and the amount of NiO. The obtained kinetic data of the NiO-Fe₂O₃/bentonite can be analyzed based on the modified volumetric and shrinking core models for the reduction andoxidation conditions, respectively. The CLC experiment was carried out in an annular shape circulating fluidizedbed (CFB) reactor with double loops. To determine the optimum fuel gas velocity, the mixture of NiO andFe₂O₃ (75:25) on a bentonite support was tested at 1123 K. The CH₄ conversion was higher at lower velocitiesthan that at higher ones, and the optimum CH₄ gas velocity for complete combustion was found to be around2-3 u_mf (minimum fluidizing velocity). Combustion efficiency increases with increasing temperature, andthe optimum reaction temperature was found to be around 1123 K. It was found that CO emission from thefuel reactor was negligibly small, and no H₂ emission was detected at the optimum conditions. From theoxidation reactor, NO_x emission was also negligibly small, and CO₂ emission was not detected.