The temperature dependence on the reaction of desulfurization reagent CaCO3 and SO2 in O2/CO2 coal combustion was investigated by thcrmogravimetric analysis, X-ray diffraction measurement and pore structure analysis. ...The temperature dependence on the reaction of desulfurization reagent CaCO3 and SO2 in O2/CO2 coal combustion was investigated by thcrmogravimetric analysis, X-ray diffraction measurement and pore structure analysis. The results show that the conversion of the reaction of CaCO3 and SO2 in air is higher at 500-1 100 ℃ and lower at 1 200 ℃ compared with that in O2/CO2 atmosphere. The conversion can be increased by increasing the concentration of SO2, which causes the inhibition of CaSO4 decomposition and shifting of the reaction equilibrium toward the products. XRD analysis of the product shows that the reaction mechanism of CaCO3 and SO2 differs with temperature in O2/CO2 atmosphere, i.e. CaCO3 directly reacts with SO2 at 500 ℃ and CaO from CaCO3 decomposition reacts with SO2 at 1 000 ℃. The pore analysis of the products indicates that the maximum specific surface area of the products accounts for the highest conversion at 1 100 ℃ in O2/CO2 atmosphere. The results reveal that the effect of the atmosphere on the conversion is temperature dependence.展开更多
The thermogravimetric analyzer and horizontal tube furnace are used to study the effects of operation parameters such as temperature, fuel type, and oxygen concentration on the combustion and NO emission characteristi...The thermogravimetric analyzer and horizontal tube furnace are used to study the effects of operation parameters such as temperature, fuel type, and oxygen concentration on the combustion and NO emission characteristics of the rice husk, rice straw, and peanut shell in the O2/CO2 atmosphere. The results show that the combustion performances of volatile matter and fixed carbon of the three biomasses increase with the increase in the 02 content. The mean NO emission increases sharply when the reaction temperature increases from 700 to 800℃. However, it increases slightly when the temperature exceeds 800 ℃. Meanwhile, the mean NO emission and nitrogen conversion decrease with the increase in the nitrogen content in biomass. The mean NO emission changes little with different oxygen concentrations, and the NO emissions of the three biomasses are all lower than the requirement for the minimum NO emission. Increasing the oxygen concentration favors the biomass combustion in the O2/CO2 atmosphere, and oxygen concentration has little effect on the NO emission.展开更多
Chemical looping combustion （CLC） of coal has gained increasing attention as a novel combustion technology for its advantages in CO2 capture. Sulfur evolution from coal causes great harm from either the CLC operatio...Chemical looping combustion （CLC） of coal has gained increasing attention as a novel combustion technology for its advantages in CO2 capture. Sulfur evolution from coal causes great harm from either the CLC operational or environmental perspective. In this research, a combined MnFe2O4 oxygen carrier （OC） was synthesized and its reaction with a typical Chinese high sulfur coal, Liuzhi （LZ） bituminous coal, was performed in a thermogravimetric analyzer （TGA）-Fourier transform infrared （FT-IR） spectrometer. Evolution of sulfur species during reaction of LZ coal with MnFeaO40C was systematically investigated through experimental means combined with thermodynamic simulation. TGA-FTIR analysis of the LZ reaction with MnFe2O4 indicated MnFe2O4 exhibited the desired superior reactivity compared to the single reference oxides Mn304 or Fe203, and SO2 produced was mainly related to oxidization of H2S by MnFe2O4. Experimental analysis of the LZ coal reaction with MnFe2O4, including X-ray diffraction and X-ray photoelectron spectroscopy analysis, verified that the main reduced counterparts of MnFe2O4 were Fe304 and MnO, in good agreement with the related thermodynamic simulation. The obtained MnO was beneficial to stabilize the reduced MnFe2O4 and avoid serious sintering, although the oxygen in MnO was not fully utilized. Meanwhile, most sulfur present in LZ coal was converted to solid MnS during LZ reaction with MnFe2O4, which was further oxidized to MnSO4. Finally, the formation of both MnS and such manganese silicates as Mn2SiO4 and MnSiO3 should be addressed to ensure the full regeneration of the reduced MnFe2O4.展开更多
With focus on investigating the effect of combustor scale on the conversion of fuel-N to NOx and N20, experiments are carried out in three combustors, including single coal particle combustion test rig, laboratory sca...With focus on investigating the effect of combustor scale on the conversion of fuel-N to NOx and N20, experiments are carried out in three combustors, including single coal particle combustion test rig, laboratory scale circulating fluidized-bed boiler （CFB） and full scale CFB in this work. For single coal particle combustion, the majority of f-uel-N （65%-82%） is released as NOx, while only a little （less than 8%） fuel-N yields N20. But in labora- tory scale CFB, the conversion of fuel-N to N20 is increases, but the conversion of fuel-N to NOx is quite less than that of single coal particle combustion. This is because much char in CFB can promote the NOx reduction by in- creasing N20 formation. In full scale CFB, both of the conversion of fuel-N to NOx and the conversion of fuel-N to N20 are smaller than laboratory scale CFB.展开更多
A simplified model for SO_(2) generation during spontaneous combustion of coal gangue was put forward and validated using the measured data.Using the proposed model,the effects of initial temperature inside the gangue...A simplified model for SO_(2) generation during spontaneous combustion of coal gangue was put forward and validated using the measured data.Using the proposed model,the effects of initial temperature inside the gangue and fresh air supply on SO_(2) generation were discussed.The results showed that,higher initial temperature inside the gangue could accelerate the oxidation rate of FeS_(2) and increase the maximum concentration of SO_(2).If initial temperature inside the gangue increased by about 37%,the total SO_(2) generation increased by 166%.Fresh air supply had less significant effect on the oxidation rate of FeS_(2).However,the higher the fresh air supply was,the more FeS_(2) could be oxidized,which ultimately produced more SO_(2).Although the computed results and the measured data concerning the inner locations inside the gangue had a certain degree of error,the proposed model can provide a relatively precise total release of SO_(2) within acceptable accuracy.Besides,this method provides a useful prototype to predict the generation of hazardous materials,such as CO,NO_(x),and chlorine during the spontaneous combustion of coal gangue.展开更多
Oxy-steam combustion is a promising next-generation combustion technology.Conversions of fuel-N,volatile-N,and char-N to NO and N2O during combustion of a single coal particle in O2/N2and O2/H2O were studied in a tube...Oxy-steam combustion is a promising next-generation combustion technology.Conversions of fuel-N,volatile-N,and char-N to NO and N2O during combustion of a single coal particle in O2/N2and O2/H2O were studied in a tube reactor at low temperature.In O2/N2,NO reaches the maximum value in the devolatilization stage and N2O reaches the maximum value in the char combustion stage.In O2/H2O,both NO and N2O reach the maximum values in the char combustion stage.The total conversion ratios of fuel-N to NO and N2O in O2/N2are obviously higher than those in O2/H2O,due to the reduction of H2O on NO and N2O.Temperature changes the trade-off between NO and N2O.In O2/N2and O2/H2O,the conversion ratios of fuel-N,volatile-N,and char-N to NO increase with increasing temperature,and those to N2O show the opposite trends.The conversion ratios of fuel-N,volatile-N,and char-N to NO reach the maximum values at 〈O2〉=30 vol%in O2/N2.In O2/H2O,the conversion ratios of fuel-N and char-N to NO reach the maximum values at 〈O2〉=30 vol%,and the conversion ratio of volatile-N to NO shows a slightly increasing trend with increasing oxygen concentration.The conversion ratios of fuel-N,volatile-N,and char-N to N2O decrease with increasing oxygen concentration in both atmospheres.A higher coal rank has higher conversion ratios of fuel-N to NO and N2O.Anthracite coal exhibits the highest conversion ratios of fuel-N,volatile-N,and char-N to NO and N2O in both atmospheres.This work is to develop efficient ways to understand and control NO and N2O emissions for a clean and sustainable atmosphere.展开更多
La2O3 is a combustion improver suitable for burning pulverized coal in blast furnace. La2O3 forms the active species La3＋（CO-）3 that weakens the bridge adhesion of carbon structural units and alters the lattice str...La2O3 is a combustion improver suitable for burning pulverized coal in blast furnace. La2O3 forms the active species La3＋（CO-）3 that weakens the bridge adhesion of carbon structural units and alters the lattice structures, thus reducing the activation energy of the pulverized coal and accelerating the burning process. Research shows that La2O3 can form the active species La3＋（CO-）3, which weakens the bridge adhesion of carbon structural units and alters the lattice structures of the fixed carbon, hence decreasing the activation energy of the pulverized coal and accelerating the burning process.展开更多
Supercritical carbon dioxide(S-CO_(2))Brayton power cycle power generation technology,has attracted more and more scholars'attention in recent years because of its advantages of high efficiency and flexibility.Com...Supercritical carbon dioxide(S-CO_(2))Brayton power cycle power generation technology,has attracted more and more scholars'attention in recent years because of its advantages of high efficiency and flexibility.Compared with conventional steam boilers,S-CO_(2) has different heat transfer characteristics,it is easy to cause the temperature of the cooling wall of the boiler to rise,which leads to higher combustion gas temperature in the furnace,higher NOX generation concentration.The adoption of flue gas recirculation has a significance impact on the combustion process of pulverized coal in the boiler,and it is the most effective ways to reduce the emission of NOX and the combustion temperature in the boiler.This paper takes 1000MW S-CO_(2) T-type coal-fired boiler as the research target to investigate the combustion and NOX generation characteristics of S-CO_(2) coal-fired boilers under flue gas recirculation condition,the influence of recirculated flue gas distribution along the furnace height on the characteristics of NOX formation and the combustion of pulverized coal.The results show that the recirculated flue gas distribution has the great impact on the concentration of NOX at the boiler outlet.When the bottom recirculation flue gas rate is gradually increased,the average temperature of the lower boiler decreases and the average temperature of the upper boiler increases slightly;The concentration of NOx at the furnace outlet increases.展开更多
基金Project(50525619) supported by the National Natural Science Foundation of ChinaProject(306012) supported by the Key Foundation of Ministry of Education of China
文摘The temperature dependence on the reaction of desulfurization reagent CaCO3 and SO2 in O2/CO2 coal combustion was investigated by thcrmogravimetric analysis, X-ray diffraction measurement and pore structure analysis. The results show that the conversion of the reaction of CaCO3 and SO2 in air is higher at 500-1 100 ℃ and lower at 1 200 ℃ compared with that in O2/CO2 atmosphere. The conversion can be increased by increasing the concentration of SO2, which causes the inhibition of CaSO4 decomposition and shifting of the reaction equilibrium toward the products. XRD analysis of the product shows that the reaction mechanism of CaCO3 and SO2 differs with temperature in O2/CO2 atmosphere, i.e. CaCO3 directly reacts with SO2 at 500 ℃ and CaO from CaCO3 decomposition reacts with SO2 at 1 000 ℃. The pore analysis of the products indicates that the maximum specific surface area of the products accounts for the highest conversion at 1 100 ℃ in O2/CO2 atmosphere. The results reveal that the effect of the atmosphere on the conversion is temperature dependence.
基金The Natural Science Foundation of Anhui Province(No.1508085ME73)the Open Foundation of Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education(No.201406)
文摘The thermogravimetric analyzer and horizontal tube furnace are used to study the effects of operation parameters such as temperature, fuel type, and oxygen concentration on the combustion and NO emission characteristics of the rice husk, rice straw, and peanut shell in the O2/CO2 atmosphere. The results show that the combustion performances of volatile matter and fixed carbon of the three biomasses increase with the increase in the 02 content. The mean NO emission increases sharply when the reaction temperature increases from 700 to 800℃. However, it increases slightly when the temperature exceeds 800 ℃. Meanwhile, the mean NO emission and nitrogen conversion decrease with the increase in the nitrogen content in biomass. The mean NO emission changes little with different oxygen concentrations, and the NO emissions of the three biomasses are all lower than the requirement for the minimum NO emission. Increasing the oxygen concentration favors the biomass combustion in the O2/CO2 atmosphere, and oxygen concentration has little effect on the NO emission.
基金supported by the National Natural Science Foundation of China(No.51276210,50906030,50936001)the financial grant of North China University of Water Conservancy and Electric Power(No.201012)the National Basic Research Program(973)of China(No.2011CB707301)
文摘Chemical looping combustion （CLC） of coal has gained increasing attention as a novel combustion technology for its advantages in CO2 capture. Sulfur evolution from coal causes great harm from either the CLC operational or environmental perspective. In this research, a combined MnFe2O4 oxygen carrier （OC） was synthesized and its reaction with a typical Chinese high sulfur coal, Liuzhi （LZ） bituminous coal, was performed in a thermogravimetric analyzer （TGA）-Fourier transform infrared （FT-IR） spectrometer. Evolution of sulfur species during reaction of LZ coal with MnFeaO40C was systematically investigated through experimental means combined with thermodynamic simulation. TGA-FTIR analysis of the LZ reaction with MnFe2O4 indicated MnFe2O4 exhibited the desired superior reactivity compared to the single reference oxides Mn304 or Fe203, and SO2 produced was mainly related to oxidization of H2S by MnFe2O4. Experimental analysis of the LZ coal reaction with MnFe2O4, including X-ray diffraction and X-ray photoelectron spectroscopy analysis, verified that the main reduced counterparts of MnFe2O4 were Fe304 and MnO, in good agreement with the related thermodynamic simulation. The obtained MnO was beneficial to stabilize the reduced MnFe2O4 and avoid serious sintering, although the oxygen in MnO was not fully utilized. Meanwhile, most sulfur present in LZ coal was converted to solid MnS during LZ reaction with MnFe2O4, which was further oxidized to MnSO4. Finally, the formation of both MnS and such manganese silicates as Mn2SiO4 and MnSiO3 should be addressed to ensure the full regeneration of the reduced MnFe2O4.
基金Supported by the National Basic Research Program of China(2009CB219802)
文摘With focus on investigating the effect of combustor scale on the conversion of fuel-N to NOx and N20, experiments are carried out in three combustors, including single coal particle combustion test rig, laboratory scale circulating fluidized-bed boiler （CFB） and full scale CFB in this work. For single coal particle combustion, the majority of f-uel-N （65%-82%） is released as NOx, while only a little （less than 8%） fuel-N yields N20. But in labora- tory scale CFB, the conversion of fuel-N to N20 is increases, but the conversion of fuel-N to NOx is quite less than that of single coal particle combustion. This is because much char in CFB can promote the NOx reduction by in- creasing N20 formation. In full scale CFB, both of the conversion of fuel-N to NOx and the conversion of fuel-N to N20 are smaller than laboratory scale CFB.
基金the financial support provided by the Major Science and Technology Projects of Inner Mongolia Autonomous Region under Grant No.RZ190001148Fund of Education Department of Inner Mongolia Autonomous Region under Grant No.NJZY21480.
文摘A simplified model for SO_(2) generation during spontaneous combustion of coal gangue was put forward and validated using the measured data.Using the proposed model,the effects of initial temperature inside the gangue and fresh air supply on SO_(2) generation were discussed.The results showed that,higher initial temperature inside the gangue could accelerate the oxidation rate of FeS_(2) and increase the maximum concentration of SO_(2).If initial temperature inside the gangue increased by about 37%,the total SO_(2) generation increased by 166%.Fresh air supply had less significant effect on the oxidation rate of FeS_(2).However,the higher the fresh air supply was,the more FeS_(2) could be oxidized,which ultimately produced more SO_(2).Although the computed results and the measured data concerning the inner locations inside the gangue had a certain degree of error,the proposed model can provide a relatively precise total release of SO_(2) within acceptable accuracy.Besides,this method provides a useful prototype to predict the generation of hazardous materials,such as CO,NO_(x),and chlorine during the spontaneous combustion of coal gangue.
基金Supported by the National Basic Research Program of China(2015CB251501)the Innovative Research Groups of the National Natural Science Foundation of China(51621005)
文摘Oxy-steam combustion is a promising next-generation combustion technology.Conversions of fuel-N,volatile-N,and char-N to NO and N2O during combustion of a single coal particle in O2/N2and O2/H2O were studied in a tube reactor at low temperature.In O2/N2,NO reaches the maximum value in the devolatilization stage and N2O reaches the maximum value in the char combustion stage.In O2/H2O,both NO and N2O reach the maximum values in the char combustion stage.The total conversion ratios of fuel-N to NO and N2O in O2/N2are obviously higher than those in O2/H2O,due to the reduction of H2O on NO and N2O.Temperature changes the trade-off between NO and N2O.In O2/N2and O2/H2O,the conversion ratios of fuel-N,volatile-N,and char-N to NO increase with increasing temperature,and those to N2O show the opposite trends.The conversion ratios of fuel-N,volatile-N,and char-N to NO reach the maximum values at 〈O2〉=30 vol%in O2/N2.In O2/H2O,the conversion ratios of fuel-N and char-N to NO reach the maximum values at 〈O2〉=30 vol%,and the conversion ratio of volatile-N to NO shows a slightly increasing trend with increasing oxygen concentration.The conversion ratios of fuel-N,volatile-N,and char-N to N2O decrease with increasing oxygen concentration in both atmospheres.A higher coal rank has higher conversion ratios of fuel-N to NO and N2O.Anthracite coal exhibits the highest conversion ratios of fuel-N,volatile-N,and char-N to NO and N2O in both atmospheres.This work is to develop efficient ways to understand and control NO and N2O emissions for a clean and sustainable atmosphere.
基金the National Key Laboratory in University of Science and Technology Beijing of China （KFI3-02） and the Natural Science Foundation of Hebei province （E2013209339）.
文摘La2O3 is a combustion improver suitable for burning pulverized coal in blast furnace. La2O3 forms the active species La3＋（CO-）3 that weakens the bridge adhesion of carbon structural units and alters the lattice structures, thus reducing the activation energy of the pulverized coal and accelerating the burning process. Research shows that La2O3 can form the active species La3＋（CO-）3, which weakens the bridge adhesion of carbon structural units and alters the lattice structures of the fixed carbon, hence decreasing the activation energy of the pulverized coal and accelerating the burning process.
基金This paper is supported by the National Key R&D Program of China(2017YFB0601805).
文摘Supercritical carbon dioxide(S-CO_(2))Brayton power cycle power generation technology,has attracted more and more scholars'attention in recent years because of its advantages of high efficiency and flexibility.Compared with conventional steam boilers,S-CO_(2) has different heat transfer characteristics,it is easy to cause the temperature of the cooling wall of the boiler to rise,which leads to higher combustion gas temperature in the furnace,higher NOX generation concentration.The adoption of flue gas recirculation has a significance impact on the combustion process of pulverized coal in the boiler,and it is the most effective ways to reduce the emission of NOX and the combustion temperature in the boiler.This paper takes 1000MW S-CO_(2) T-type coal-fired boiler as the research target to investigate the combustion and NOX generation characteristics of S-CO_(2) coal-fired boilers under flue gas recirculation condition,the influence of recirculated flue gas distribution along the furnace height on the characteristics of NOX formation and the combustion of pulverized coal.The results show that the recirculated flue gas distribution has the great impact on the concentration of NOX at the boiler outlet.When the bottom recirculation flue gas rate is gradually increased,the average temperature of the lower boiler decreases and the average temperature of the upper boiler increases slightly;The concentration of NOx at the furnace outlet increases.
