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
Landfill gas(LFG)utilization which means a synergy between environmental protection and bioenergy recovery was investigated in this study.Pressure swing adsorption technology was used in LFG purification,and laborator...Landfill gas(LFG)utilization which means a synergy between environmental protection and bioenergy recovery was investigated in this study.Pressure swing adsorption technology was used in LFG purification,and laboratory experiment,pilot-scale test,and on-site demonstration were carried out in Shenzhen,China.In the laboratory experiment,A-type carbon molecular sieve was selected as the adsorbent by comparison of several other adsorbents.The optimal adsorption pressure and adsorption time were 0.25 MPa and 2 min,respectively,under which the product generation rate was 4.5 m^(3)/h and the methane concentration was above 90%.The process and optimization of the pilot-scale test were also reported in the paper.The product gas was of high quality compared with the National Standard of Compressed Natural Gas as Vehicle Fuel(GB18047-2000),when the air concentration in feed gas was under 10.96%.The demonstration project was composed of a collection system,production system,and utilization system.The drive performance,environmental protection performance,and economic feasibility of the product gas—as alternative fuel in passenger car,truck,and bulldozer—were tested,showing the feasibility technology for LFG utilization.展开更多
Food waste(FW)is a major component of municipal solid waste(MSW)in developing countries such as China.Anaerobic digestion(AD)is a widely-applied FW biological treatment method following MSW classification.With FW dive...Food waste(FW)is a major component of municipal solid waste(MSW)in developing countries such as China.Anaerobic digestion(AD)is a widely-applied FW biological treatment method following MSW classification.With FW diversion from conventional incineration plants,the environmental risk caused by trace toxic pollutants,such as polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs),should be reevaluated.This study investigated a full-scale FW-AD plant in Shenzhen,China,and addressed two important underexplored issues:the distribution patterns of PCDD/Fs during the FW-AD process and PCDD/F emission characteristics of the biogas utilization exhaust gas.Mass balance demonstrated a negative balance of 2.48μg I-TEQ/t of raw FW(RFW),thus indicating that AD produced moderate PCDD/F emissions.The detailed findings were as follows:1)PCDD/F toxic equivalents(TEQs)in pure FW(RFW without impurities)were lower than in RFW,indicating that MSW source separation is crucial for decreasing the PCDD/F input into the AD system;2)PCDD/F contents(6.20–8.27 pg I-TEQ/g dry weight)in solid digestate were near the screening value of development land in China’s national standard(GB36600-2018),thus indicating that the potential environmental risk from the land application of solid digestate should be considered;and 3)PCDD/F TEQs(0.001–0.022 ng I-TEQ/Nm^(3))in biogas utilization exhaust gas were roughly equivalent to those produced by MSW incinerators in Shenzhen.This study indicated that compared with co-incineration with other waste,FW-AD will reduce PCDD/F emissions(air)from MSW incineration plants by 12.5%–21.3%at the national level under an FW separation scenario.展开更多
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.
文摘Landfill gas(LFG)utilization which means a synergy between environmental protection and bioenergy recovery was investigated in this study.Pressure swing adsorption technology was used in LFG purification,and laboratory experiment,pilot-scale test,and on-site demonstration were carried out in Shenzhen,China.In the laboratory experiment,A-type carbon molecular sieve was selected as the adsorbent by comparison of several other adsorbents.The optimal adsorption pressure and adsorption time were 0.25 MPa and 2 min,respectively,under which the product generation rate was 4.5 m^(3)/h and the methane concentration was above 90%.The process and optimization of the pilot-scale test were also reported in the paper.The product gas was of high quality compared with the National Standard of Compressed Natural Gas as Vehicle Fuel(GB18047-2000),when the air concentration in feed gas was under 10.96%.The demonstration project was composed of a collection system,production system,and utilization system.The drive performance,environmental protection performance,and economic feasibility of the product gas—as alternative fuel in passenger car,truck,and bulldozer—were tested,showing the feasibility technology for LFG utilization.
基金supported by the National Key Research and Development Program of China(No.2018YFC1902904)the Shenzhen Science and Technology Program(No.WDZC20200817144218001)。
文摘Food waste(FW)is a major component of municipal solid waste(MSW)in developing countries such as China.Anaerobic digestion(AD)is a widely-applied FW biological treatment method following MSW classification.With FW diversion from conventional incineration plants,the environmental risk caused by trace toxic pollutants,such as polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs),should be reevaluated.This study investigated a full-scale FW-AD plant in Shenzhen,China,and addressed two important underexplored issues:the distribution patterns of PCDD/Fs during the FW-AD process and PCDD/F emission characteristics of the biogas utilization exhaust gas.Mass balance demonstrated a negative balance of 2.48μg I-TEQ/t of raw FW(RFW),thus indicating that AD produced moderate PCDD/F emissions.The detailed findings were as follows:1)PCDD/F toxic equivalents(TEQs)in pure FW(RFW without impurities)were lower than in RFW,indicating that MSW source separation is crucial for decreasing the PCDD/F input into the AD system;2)PCDD/F contents(6.20–8.27 pg I-TEQ/g dry weight)in solid digestate were near the screening value of development land in China’s national standard(GB36600-2018),thus indicating that the potential environmental risk from the land application of solid digestate should be considered;and 3)PCDD/F TEQs(0.001–0.022 ng I-TEQ/Nm^(3))in biogas utilization exhaust gas were roughly equivalent to those produced by MSW incinerators in Shenzhen.This study indicated that compared with co-incineration with other waste,FW-AD will reduce PCDD/F emissions(air)from MSW incineration plants by 12.5%–21.3%at the national level under an FW separation scenario.
