Study on High-Temperature Chemical-Looping Combustion with CO and H2 Using Fe2O3/SiO2

• Main Authors: Zhen-YingWu, 吳貞瑩
• Other Authors: Hsin Chu
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/01609328612360373822

碩士 === 國立成功大學 === 環境工程學系碩博士班 === 98 === The proposed Taiwan strategy to meet the challenge of future energy supply is based, among others like e.g. renewable, on fossil fuel conversion and subsequent capture and sequestration of the greenhouse gas CO2. The idea is to deposit concentrated CO2 in save geological storages like gas fields instead of uncontrolled emission in the atmosphere. Chemical looping combustion (CLC) is such a new, indirect combustion process with inherent separation of CO2. The technology was found to be one of the absolute best in the cost evaluation. The process features 100% CO2 capture, a highly concentrated stream of CO2 ready for sequestration, no NOX emission, and no costs or energy penalties for gas separation. In the present work, a best homemade metal oxide sorbent, Fe2O3/SiO2 and NiO/SiO2, will be chosen to react with CO/H2 in an oven. The objectives can be classified into seven major parts: 1. Investigation of metal oxygen carriers react with CO and H2 alone and simultaneously under the high temperature. From the TGA reduction test, Fe2O3 react with CO and H2 more stable reducing effective than NiO after several regeneration. 2. To known the effects of operating factors, we tests in a fixed bed reactor to determine CO and H2 gas concentrations obtained at the outlet during the reduction reaction. During reduction with increasing CO concentration of the Fe2O3, this carrier showed well utilization and high reduction reactivities. However, enhance the concentration of H2 to 20%, the utilization will reach as high as 100%. 3. Under reduction condition, the H2 and CO total concentration is the same that demonstrates the addition of H2 make the oxygen carrier performance getting better. Hence, the H2 cause the reducing rate of oxygen carrier is more rapidly than CO. 4. Several instruments will be used for observing the structure change, elemental composition and crystal transformation. From the XRD pattern, it can be found that the Si-Fe compounds are produced by the reduced oxygen carriers. However, the oxygen carriers of fresh and oxidation don’t observe the compounds. 5. After several regenerations, the pore volume decrease with increasing pore diameter. Hence, oxygen carrier pore volume will be transformed from mesoporous to macroporous, reducing specific surface area and result the oxygen carrier activation declined. 6. Under reduction condition, Fe2O3 react with H2S will be reduced to FeS. The FeS will foul the interfacial active site of oxygen carrier and lower the utilization. 7. The kinetic model for the reaction of Fe2O3 oxygen carrier with CO and H2 of the experimental results.