Direct reduction of high-phosphorus oolitic hematite ore based on biomass pyrolysis gases （CO, H2, and CH4 ）, tar, and char was conducted to investigate the effects of reduction temperature, iron ore-biomass mass ra...Direct reduction of high-phosphorus oolitic hematite ore based on biomass pyrolysis gases （CO, H2, and CH4 ）, tar, and char was conducted to investigate the effects of reduction temperature, iron ore-biomass mass ratio, and reduction time on the metallization rate. In addition, the effect of particle size on the dephosphorization and iron recovery rate was studied by magnetic separation. It was determined that the metallization rate of the hematite ore could reach 99.35 % at iron ore-biomass mass ratio of 1 ： 0.6, reduction temperature of 1100℃, and reduction time of 55 min. The metallization rate and the aggregation degree of iron particles increase with the increase of reduction temperature. The particle size of direct reduced iron （DRI） has a great influence on the quality of the iron concentrate during magnetic separation. The separation degree of slag and iron was improved by the addition of 15 mass% sodium carbonate. DRI with iron grade of 89.11%, iron recovery rate of 83.47%, and phosphorus content of 0.28% can be obtained when ore fines with particle size of -10μm account for 78.15%.展开更多
The magnetization reduction of hematite using biomass waste can effectively utilize waste and reduce CO_(2) emission to achieve the goals of carbon peaking and carbon neutrality.The effects of temperatures on suspensi...The magnetization reduction of hematite using biomass waste can effectively utilize waste and reduce CO_(2) emission to achieve the goals of carbon peaking and carbon neutrality.The effects of temperatures on suspension magnetization roasting of hematite using biomass waste for evolved gases have been investigated using TG-FTIR,Py-GC/MS and gas composition analyzer.The mixture reduction process is divided into four stages.In the temperature range of 200-450℃ for mixture,the release of CO_(2),acids,and ketones is dominated in gases products.The yield and concentration of small molecules reducing gases increase when the temperature increases from 450 to 900℃.At 700℃,the volume concentrations of CO,H_(2) and CH_(4) peak at 8.91%,8.90% and 4.91%,respectively.During the suspension magnetization roasting process,an optimal iron concentrate with an iron grade of 70.86%,a recovery of 98.66% and a magnetic conversion of 45.70% is obtained at 700℃.Therefore,the magnetization reduction could react greatly in the temperature range of 600 to 700℃ owing to the suitable reducing gases.This study shows a detail gaseous evolution of roasting temperature and provides a new insight for studying the reduction process of hematite using biomass waste.展开更多
Pyrolysis of biomass followed by combustion of pyrolytic vapors to replace fossil fuels is an economic low-carbon solution.However,the polycyclic aromatic hydrocarbons and N-containing species in biomass pyrolysis vap...Pyrolysis of biomass followed by combustion of pyrolytic vapors to replace fossil fuels is an economic low-carbon solution.However,the polycyclic aromatic hydrocarbons and N-containing species in biomass pyrolysis vapors result in the soot and NO emissions.The flue gas recirculation(FGR)technology,having the potential to reduce the soot and NO emissions,was introduced to the biomass pyrolysis-combustion system.In addition,it was numerically studied by simulating the biomass pyrolysis vapors based co-flow diffusion flames with CO_(2)addition.Both the experimental and simulated results showed that the FGR had significant suppression effects on the soot formation.When the FGR ratio(i.e.,CO_(2)addition ratio)increased from 0%to 15%,the experimental and simulated soot volume fraction respectively decreased by 32%and 21%,which verified the models used in this study.The decrease in OH concentration caused by the CO_(2)addition was responsible for the decrease in the decomposition rate of A2(A2+OH=A2–+H_(2)O).Hence,more benzo(ghi)fluoranthene(BGHIF)was generated through A1C_(2)H–+A2→BGHIF+H_(2)+H,leading to the increase in inception rate.The decrease in benzo(a)pyrene(BAPYR)concentration was the major factor in the decrease in soot condensation rate.Moreover,the decrease in the C_(2)H_(2) and OH concentrations was responsible for the decrease in the HACA surface growth rate.Furthermore,the simulated results showed that the NO concentration decreased by 0.4%when the content of CO_(2)was increased by 1 vol.%.The decrease in OH concentration suppressed the NO formation via decreasing reaction rates of N+OH=NO+H and HNO+OH=NO+H_(2)O and enhanced the NO consumption via increasing reaction rate of HO_(2)+NO=NO_(2)+OH.展开更多
The present work investigated the synergetic effect of pyrolysis-derived char,tar and gas(py-gas)on NO reduction,which may occur in circulating fluidized-bed decoupling combustion(CFBDC)system treating N-rich fuel.Exp...The present work investigated the synergetic effect of pyrolysis-derived char,tar and gas(py-gas)on NO reduction,which may occur in circulating fluidized-bed decoupling combustion(CFBDC)system treating N-rich fuel.Experiments were carried out in a lab-scale drop-tube reactor for NO reduction by some binary mixtures of reagents including char/py-gas,tar/py-gas and tar/char.At a specified total mass rate of0.15 g·min^-1 for NO-reduction reagent,the char/py-gas(binary reagent)enabled the best synergetic NO reduction in comparison with the others.There existed effective interactions between char and some species in py-gas(i.e.,H2,CxHy)during NO reduction by pyrolysis products,meanwhile the tar/py-gas or tar/char mixture only caused a positive effect when tar proportion was necessarily lowered to about 26%.On the other hand,the synergetic effects were not improved for all tested binary reagents by increasing the reaction temperature and residence time.展开更多
基金Sponsored by National Natural Science Foundation of China(51574024,51274042)China Postdoctoral Science Foundation(2015M580987,2016T90034)
文摘Direct reduction of high-phosphorus oolitic hematite ore based on biomass pyrolysis gases （CO, H2, and CH4 ）, tar, and char was conducted to investigate the effects of reduction temperature, iron ore-biomass mass ratio, and reduction time on the metallization rate. In addition, the effect of particle size on the dephosphorization and iron recovery rate was studied by magnetic separation. It was determined that the metallization rate of the hematite ore could reach 99.35 % at iron ore-biomass mass ratio of 1 ： 0.6, reduction temperature of 1100℃, and reduction time of 55 min. The metallization rate and the aggregation degree of iron particles increase with the increase of reduction temperature. The particle size of direct reduced iron （DRI） has a great influence on the quality of the iron concentrate during magnetic separation. The separation degree of slag and iron was improved by the addition of 15 mass% sodium carbonate. DRI with iron grade of 89.11%, iron recovery rate of 83.47%, and phosphorus content of 0.28% can be obtained when ore fines with particle size of -10μm account for 78.15%.
基金Project(52022019)supported by the National Natural Science Foundation of China。
文摘The magnetization reduction of hematite using biomass waste can effectively utilize waste and reduce CO_(2) emission to achieve the goals of carbon peaking and carbon neutrality.The effects of temperatures on suspension magnetization roasting of hematite using biomass waste for evolved gases have been investigated using TG-FTIR,Py-GC/MS and gas composition analyzer.The mixture reduction process is divided into four stages.In the temperature range of 200-450℃ for mixture,the release of CO_(2),acids,and ketones is dominated in gases products.The yield and concentration of small molecules reducing gases increase when the temperature increases from 450 to 900℃.At 700℃,the volume concentrations of CO,H_(2) and CH_(4) peak at 8.91%,8.90% and 4.91%,respectively.During the suspension magnetization roasting process,an optimal iron concentrate with an iron grade of 70.86%,a recovery of 98.66% and a magnetic conversion of 45.70% is obtained at 700℃.Therefore,the magnetization reduction could react greatly in the temperature range of 600 to 700℃ owing to the suitable reducing gases.This study shows a detail gaseous evolution of roasting temperature and provides a new insight for studying the reduction process of hematite using biomass waste.
基金supported by the National Natural Science Foundation of China(Grant Nos.52276185,52276189,and 51976057)the Science and Technology Innovation Program of Hunan Province(Grant No.2020RC5008)the Fundamental Research Funds for the Central Universities(Grant No.2020DF01)。
文摘Pyrolysis of biomass followed by combustion of pyrolytic vapors to replace fossil fuels is an economic low-carbon solution.However,the polycyclic aromatic hydrocarbons and N-containing species in biomass pyrolysis vapors result in the soot and NO emissions.The flue gas recirculation(FGR)technology,having the potential to reduce the soot and NO emissions,was introduced to the biomass pyrolysis-combustion system.In addition,it was numerically studied by simulating the biomass pyrolysis vapors based co-flow diffusion flames with CO_(2)addition.Both the experimental and simulated results showed that the FGR had significant suppression effects on the soot formation.When the FGR ratio(i.e.,CO_(2)addition ratio)increased from 0%to 15%,the experimental and simulated soot volume fraction respectively decreased by 32%and 21%,which verified the models used in this study.The decrease in OH concentration caused by the CO_(2)addition was responsible for the decrease in the decomposition rate of A2(A2+OH=A2–+H_(2)O).Hence,more benzo(ghi)fluoranthene(BGHIF)was generated through A1C_(2)H–+A2→BGHIF+H_(2)+H,leading to the increase in inception rate.The decrease in benzo(a)pyrene(BAPYR)concentration was the major factor in the decrease in soot condensation rate.Moreover,the decrease in the C_(2)H_(2) and OH concentrations was responsible for the decrease in the HACA surface growth rate.Furthermore,the simulated results showed that the NO concentration decreased by 0.4%when the content of CO_(2)was increased by 1 vol.%.The decrease in OH concentration suppressed the NO formation via decreasing reaction rates of N+OH=NO+H and HNO+OH=NO+H_(2)O and enhanced the NO consumption via increasing reaction rate of HO_(2)+NO=NO_(2)+OH.
基金Supported by the National Basic Research Program of China(2014BAC26B04,2014CB744303)the National Natural Science Foundation of China(U1302273)
文摘The present work investigated the synergetic effect of pyrolysis-derived char,tar and gas(py-gas)on NO reduction,which may occur in circulating fluidized-bed decoupling combustion(CFBDC)system treating N-rich fuel.Experiments were carried out in a lab-scale drop-tube reactor for NO reduction by some binary mixtures of reagents including char/py-gas,tar/py-gas and tar/char.At a specified total mass rate of0.15 g·min^-1 for NO-reduction reagent,the char/py-gas(binary reagent)enabled the best synergetic NO reduction in comparison with the others.There existed effective interactions between char and some species in py-gas(i.e.,H2,CxHy)during NO reduction by pyrolysis products,meanwhile the tar/py-gas or tar/char mixture only caused a positive effect when tar proportion was necessarily lowered to about 26%.On the other hand,the synergetic effects were not improved for all tested binary reagents by increasing the reaction temperature and residence time.
