Dioxin production is a worldwide concern because of its persistence and carcinogenic,teratogenic, and mutagenic effects. The pyrolysis-chemical looping combustion process of disposing solid waste is an alternative to ...Dioxin production is a worldwide concern because of its persistence and carcinogenic,teratogenic, and mutagenic effects. The pyrolysis-chemical looping combustion process of disposing solid waste is an alternative to traditional solid waste incineration developed to reduce the dioxin production. Based on the equilibrium composition of the Deacon reaction,pyrolysis gas oxidized by seven common oxygen carriers, namely, Cu O, Ni O, Ca SO4, Co O,Fe2O3, Mn3O4, and Fe Ti O3, is studied and compared with the pyrolysis gas directly combusted by air. The result shows that the activity of the Deacon reaction for oxygen carriers is lower than that for air. For four typical oxygen carriers（Cu O, Ni O, Fe2O3, and Fe Ti O3）, the influences of temperature, pressure, gas composition, and tar on the Deacon reaction are discussed in detail. According to these simulation results, the dioxin production in China, Europe, the United States, and Japan is predicted for solid waste disposal by the pyrolysis-chemical looping combustion process. Thermodynamic analysis results in this paper show that chemical looping combustion can reduce dioxin production in the disposal of solid waste.展开更多
Chemical looping combustion is a promising technology for energy conversion due to its low-carbon, high-efficiency, and environmental-friendly feature. A vital issue for CLC process is the development of oxygen carrie...Chemical looping combustion is a promising technology for energy conversion due to its low-carbon, high-efficiency, and environmental-friendly feature. A vital issue for CLC process is the development of oxygen carrier, since it must have sufficient reactivity. The mechanism and kinetics of CO reduction on iron-based oxygen carriers namely pure Fe2O3 and Fe2O3 supported by alumina （Fe2O3/Al2O3） were investigated using thermo-gravimetric analysis. Fe2O3/Al2O3 showed better reactivity over bare Fe2O3 toward CO reduction. This was well supported by the observed higher rate constant for FezO3/Al2O3 over pure Fe2O3 with respective activation energy of 41.1±2.0 and 33.3±0.8 kJ. mol^-1. The proposed models were compared via statistical approach comprising Akaike information criterion with correction coupled with F-test. The phase-boundary reaction and diffusion control models approximated to 95% confidence level along with scanning electron microscopy results; revealed the promis- ing reduction reactions of pure Fe203 and Fe2O3/Al2O3. The boosting recital of iron-based oxygen carrier support toward efficient chemical looping combustion could be explained accurately through the present study.展开更多
The chemical looping concept provided a novel way to achieve carbon separation during the production of energy or substances. In this work, hydrogen generation with inherent CO2 capture in single packed bed reactor vi...The chemical looping concept provided a novel way to achieve carbon separation during the production of energy or substances. In this work, hydrogen generation with inherent CO2 capture in single packed bed reactor via this concept was discussed. Two oxygen carriers, Fe203 60 wt.% and Fe2O3 55 wt.%/CuO 5 wt.% supported by Al2O3, were made by ball milling method. First, according to the characteristics of the reduction breakthrough curve, a strict fuel supply strategy was selected to achieve simultaneous CO2 capture and HE production. Then, in the long term tests using CO as fuel, it was proved that CuO addition improved hydrogen generation with the maximum intensity of 3700 μmol H2·g^-1 Fe2O3 compared with Fe-Al of 2300 μmol HE.g^-1 Fe2O3. The overall CO2 capture efficiency remained 98%- 98.8% over 100 cycles. Moreover, the reactivity of deactivated materials was recovered nearly like that of fresh ones by sintering treatment. Finally, two kinds of complex gases consist of CO, HE, CH4 and CO2 were utilized as fuels to test the feasibility. The results showed all components could be completely converted by Fe-Cu- Al in the reduction stage. The intensity of hydrogen production and the overall CO2 capture efficiency were in the range of 2000-2400 μnol H2^g^-1 Fe2O3 and 89%, 95%, respectively.展开更多
基金supported by the National Basic Research Program of China (973 Program) (No. 2011CB201502)the National Key Technology R&D Program of China (No. 2010BAC66B03)
文摘Dioxin production is a worldwide concern because of its persistence and carcinogenic,teratogenic, and mutagenic effects. The pyrolysis-chemical looping combustion process of disposing solid waste is an alternative to traditional solid waste incineration developed to reduce the dioxin production. Based on the equilibrium composition of the Deacon reaction,pyrolysis gas oxidized by seven common oxygen carriers, namely, Cu O, Ni O, Ca SO4, Co O,Fe2O3, Mn3O4, and Fe Ti O3, is studied and compared with the pyrolysis gas directly combusted by air. The result shows that the activity of the Deacon reaction for oxygen carriers is lower than that for air. For four typical oxygen carriers（Cu O, Ni O, Fe2O3, and Fe Ti O3）, the influences of temperature, pressure, gas composition, and tar on the Deacon reaction are discussed in detail. According to these simulation results, the dioxin production in China, Europe, the United States, and Japan is predicted for solid waste disposal by the pyrolysis-chemical looping combustion process. Thermodynamic analysis results in this paper show that chemical looping combustion can reduce dioxin production in the disposal of solid waste.
文摘Chemical looping combustion is a promising technology for energy conversion due to its low-carbon, high-efficiency, and environmental-friendly feature. A vital issue for CLC process is the development of oxygen carrier, since it must have sufficient reactivity. The mechanism and kinetics of CO reduction on iron-based oxygen carriers namely pure Fe2O3 and Fe2O3 supported by alumina （Fe2O3/Al2O3） were investigated using thermo-gravimetric analysis. Fe2O3/Al2O3 showed better reactivity over bare Fe2O3 toward CO reduction. This was well supported by the observed higher rate constant for FezO3/Al2O3 over pure Fe2O3 with respective activation energy of 41.1±2.0 and 33.3±0.8 kJ. mol^-1. The proposed models were compared via statistical approach comprising Akaike information criterion with correction coupled with F-test. The phase-boundary reaction and diffusion control models approximated to 95% confidence level along with scanning electron microscopy results; revealed the promis- ing reduction reactions of pure Fe203 and Fe2O3/Al2O3. The boosting recital of iron-based oxygen carrier support toward efficient chemical looping combustion could be explained accurately through the present study.
文摘The chemical looping concept provided a novel way to achieve carbon separation during the production of energy or substances. In this work, hydrogen generation with inherent CO2 capture in single packed bed reactor via this concept was discussed. Two oxygen carriers, Fe203 60 wt.% and Fe2O3 55 wt.%/CuO 5 wt.% supported by Al2O3, were made by ball milling method. First, according to the characteristics of the reduction breakthrough curve, a strict fuel supply strategy was selected to achieve simultaneous CO2 capture and HE production. Then, in the long term tests using CO as fuel, it was proved that CuO addition improved hydrogen generation with the maximum intensity of 3700 μmol H2·g^-1 Fe2O3 compared with Fe-Al of 2300 μmol HE.g^-1 Fe2O3. The overall CO2 capture efficiency remained 98%- 98.8% over 100 cycles. Moreover, the reactivity of deactivated materials was recovered nearly like that of fresh ones by sintering treatment. Finally, two kinds of complex gases consist of CO, HE, CH4 and CO2 were utilized as fuels to test the feasibility. The results showed all components could be completely converted by Fe-Cu- Al in the reduction stage. The intensity of hydrogen production and the overall CO2 capture efficiency were in the range of 2000-2400 μnol H2^g^-1 Fe2O3 and 89%, 95%, respectively.
