Electrocatalytic oxygen reduction reaction(ORR)is one of the most important reactions in electrochemical energy technologies such as fuel cells and metal–O2/air batteries,etc.However,the essential catalysts to overco...Electrocatalytic oxygen reduction reaction(ORR)is one of the most important reactions in electrochemical energy technologies such as fuel cells and metal–O2/air batteries,etc.However,the essential catalysts to overcome its slow reaction kinetic always undergo a complex dynamic evolution in the actual catalytic process,and the concomitant intermediates and catalytic products also occur continuous conversion and reconstruction.This makes them difficult to be accurately captured,making the identification of ORR active sites and the elucidation of ORR mechanisms difficult.Thus,it is necessary to use extensive in-situ characterization techniques to proceed the real-time monitoring of the catalyst structure and the evolution state of intermediates and products during ORR.This work reviews the major advances in the use of various in-situ techniques to characterize the catalytic processes of various catalysts.Specifically,the catalyst structure evolutions revealed directly by in-situ techniques are systematically summarized,such as phase,valence,electronic transfer,coordination,and spin states varies.In-situ revelation of intermediate adsorption/desorption behavior,and the real-time monitoring of the product nucleation,growth,and reconstruction evolution are equally emphasized in the discussion.Other interference factors,as well as in-situ signal assignment with the aid of theoretical calculations,are also covered.Finally,some major challenges and prospects of in-situ techniques for future catalysts research in the ORR process are proposed.展开更多
Nanosized tungsten carbide(WC)/carbon(C)catalyst was synthesized via a novel ultra-rapid confinement combustion synthesis method.The amount of activated carbon(AC)plays an important role in the morphology and structur...Nanosized tungsten carbide(WC)/carbon(C)catalyst was synthesized via a novel ultra-rapid confinement combustion synthesis method.The amount of activated carbon(AC)plays an important role in the morphology and structure,controlling both the precursor and final powder.The WC particles synthesized inside the pores of the AC had been 10-20 nm because of the confinement of the pore structure and the large specific surface area of AC.When used for oxygen reduction performance,the half-wave potential was−0.24 V,and the electron transfer number was 3.45,indicating the main reaction process was the transfer of four electrons.The detailed electrocatalytic performance and underlying mechanism were investigated in this work.Our study provides a novel approach for the design of catalysts with new compositions and new structures,which are significant for promoting the commercialization of fuel cells.展开更多
For capturing and recycling of CO_2 in the internal combustion engine, Rankle cycle engine can reduce the exhaust pollutants effectively under the condition of ensuring the engine thermal efficiency by using the techn...For capturing and recycling of CO_2 in the internal combustion engine, Rankle cycle engine can reduce the exhaust pollutants effectively under the condition of ensuring the engine thermal efficiency by using the techniques of spraying water in the cylinder and optimizing the ignition advance angle. However, due to the water spray nozzle need to be installed on the cylinder, which increases the cylinder head design difficulty and makes the combustion conditions become more complicated. In this paper, a new method is presented to carry out the closing inlet and exhaust system for internal combustion engines. The proposed new method uses liquid oxygen to solidify part of cooled CO_2 from exhaust system into dry ice and the liquid oxygen turns into gas oxygen which is sent to inlet system. The other part of CO_2 is sent to inlet system and mixed with oxygen, which can reduce the oxygen-enriched combustion detonation tendency and make combustion stable. Computing grid of the IP52 FMI single-cylinder four-stroke gasoline-engine is established according to the actual shape of the combustion chamber using KIVA-3V program. The effects of exhaust gas recirculation(EGR) rate are analyzed on the temperatures, the pressures and the instantaneous heat release rates when the EGR rate is more than 8%. The possibility of enclosing intake and exhaust system for engine is verified. The carbon dioxide trapping device is designed and the IP52 FMI engine is transformed and the CO_2 capture experiment is carried out. The experimental results show that when the EGR rate is 36% for the optimum EGR rate. When the liquid oxygen of 35.80–437.40 g is imported into the device and last 1–20 min, respectively, 21.50–701.30 g dry ice is obtained. This research proposes a new design method which can capture CO_2 for vehicular internal combustion engine.展开更多
Various physical parameters, including gas concentrations (O2, CO, CH4, and H2) and temperatures at dif- ferent air velocities, were determined for full scale wood fires in the Chongqing Coal Research Institute fire t...Various physical parameters, including gas concentrations (O2, CO, CH4, and H2) and temperatures at dif- ferent air velocities, were determined for full scale wood fires in the Chongqing Coal Research Institute fire test tunnel. Both experimental measurements and numerical simulations are discussed. The numer- ical analysis was performed with the computational fluid dynamics software package ''FLUENT''. The results show that the experimental data agree with the simulation results. The results verify that Roberts' theory of burning is correct. They also prove that the air velocity is the key factor that determines the type of combustion. Also, it is shown that secondary disasters are unlikely for oxygen rich combustion with a limited fire load.展开更多
Coal samples in the air for three months were characterized by Thermogravimetric Analysis (TGA). The effect of a PVA oxygen-insulating barrier on the spontaneous combustion of coal was examined. The moisture loss acti...Coal samples in the air for three months were characterized by Thermogravimetric Analysis (TGA). The effect of a PVA oxygen-insulating barrier on the spontaneous combustion of coal was examined. The moisture loss activation energy, oxidation activation energy and combustion activation energy were calculated by an integral method using the Coats-Redfen formula. The results show that the tendency for spontaneous combustion of three coal samples (judged by the activation energy) falls in the order: CYW>YJL>SW. The oxidation activation energy and combustion activation energy of coal protected by the PVA oxygen-insulating barrier increased. A significant increase in the combustion activation energy was noted, especially for the CYW coal where the in-crease was 28.53 kJ/mol. Hence, oxidation of the protected coal samples was more difficult. The PVA oxygen-insulating barrier helps to prevent spontaneous combustion of the coal.展开更多
To explore the reaction behavior of trace oxygen during the flash combustion process of falling FeSi75 powder in a nitrogen flow, a flash-combustion-synthesized Fe-Si_3N_4 sample was heat-treated to remove SiO_2. The ...To explore the reaction behavior of trace oxygen during the flash combustion process of falling FeSi75 powder in a nitrogen flow, a flash-combustion-synthesized Fe-Si_3N_4 sample was heat-treated to remove SiO_2. The samples before and after the treatment were investigated by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, and the formation mechanism of SiO_2 was investigated. The results show that SiO_2 in the Fe-Si_3N_4 is mainly located on the surface or around the Si_3N_4 particles in dense areas, existing in both crystalline and amorphous states; when the FeSi75 particles, which are less than 0.074 mm in size, fell in up-flowing hot N_2 stream, trace oxygen in the N_2 stream did not significantly hinder the nitridation of FeSi75 particles as it was consumed by the surface oxidation of the generated Si_3N_4 particles to form SiO_2. At the reaction zone, the oxidation of Si_3N_4 particles decreased the oxygen partial pressure in the N_2 stream and greatly reduced the opportunity for FeSi75 particles to be oxidized into SiO_2; by virtue of the SiO_2 film developed on the surface, the Si_3N_4 particles adhered to each other and formed dense areas in the material.展开更多
The cycle life of oxygen carrier(OC) is crucial to the practical applications of chemical looping combustion(CLC). Cycle performance of Cu/SiO_2 prepared with a mechanical mixing method was evaluated based on a CLC pr...The cycle life of oxygen carrier(OC) is crucial to the practical applications of chemical looping combustion(CLC). Cycle performance of Cu/SiO_2 prepared with a mechanical mixing method was evaluated based on a CLC process characterized with an added methane steam reforming step. The Cu/SiO_2 exhibited high redox reactivity in the initial cycles, while the performance degraded with cycle number. Through characterization of the degraded Cu/SiO_2, the performance degradation was mainly caused by the secondary particles' fragmentation and the fine particles' local agglomeration, which worsened the distribution and diffusion of the reactive gases in the packed bed. A regeneration method of the degraded OC based on re-granulation has been proposed, and its mechanism has been illustrated. With this method, the performance of the degraded OC through 420 redox cycles was recovered to a level close to the initial one.展开更多
Four different pulverized coals have been used to study the effects of oxygen concentration on combustion characteristics under different enriched-oxygen conditions by entrained flow reactor experiments. The results s...Four different pulverized coals have been used to study the effects of oxygen concentration on combustion characteristics under different enriched-oxygen conditions by entrained flow reactor experiments. The results show that: with the increase of oxygen concentration, the ignition temperature of four coals greatly decreases and the low volatile coals decrease faster; with the increase of oxygen concentration, the ignition mode of pulverized coal has an obviously transformation from homogeneous ignition to heterogeneous ignition, and the corresponding oxygen concentrations are about 40% and 50%-60% respectively for bituminous coal and lignite, and both about 30% for lean coal and anthracite; with the increase of oxygen concentration, the optimal pulverized coal concentrations of bituminous coal and lignite increase firstly and then decrease, but for lean coal and anthracite, the optimal pulverized coal concentrations decrease slowly with the increase of oxygen concentration.展开更多
Manganese-doped zinc silicate powder samples were prepared successfully by solution combustion process,and their photoluminescence were investigated in ultraviolet region. The single-phase of Zn2- x SiO4: x Mn （0≤ x...Manganese-doped zinc silicate powder samples were prepared successfully by solution combustion process,and their photoluminescence were investigated in ultraviolet region. The single-phase of Zn2- x SiO4: x Mn （0≤ x ≤0.10,willemite） was obtained by combustion synthesis at 600 ℃ for afew minutes,then heat treated at above 900 ℃ for 4 h. In the excitation spectra of Zn2- x SiO4: x Mn （0< x ≤0.10）,the strongest broad band at about 254 nm is observed and assigned to （（） 6A1）→（（） 4T1） transition of Mn （2+） monitoring at 525 nm emission. At about 525 nm,the intense broad band emission is observed under 254 nm excitation in Zn2- x SiO4: x Mn （0< x ≤0.10）. This broad band is attributed to （（） 4T1）→（（） 6A1） transition of Mn （2+）. The results indicate that photoluminescence efficiency,the location of the strongest excitation or emission band,and the optimum concentration of activator depend on starting materials,combustion temperatures,the dosage of fuels,and the size of powder samples etc..展开更多
An advanced cyclone MHD combustor possesses its own featuresin terms of the requirements of MHD power generation. In this paper,the au-thors try to sum up the advanced combustion techniques used in MHD com-bustors and...An advanced cyclone MHD combustor possesses its own featuresin terms of the requirements of MHD power generation. In this paper,the au-thors try to sum up the advanced combustion techniques used in MHD com-bustors and explain their functions by theoretica展开更多
There is still very little information on the sources of water absorbed by oil palm plant. This information is very important for water management system in oil palm plantation. Thus, this study was carried out to det...There is still very little information on the sources of water absorbed by oil palm plant. This information is very important for water management system in oil palm plantation. Thus, this study was carried out to determine current water sources absorbed by the oil palm roots using oxygen (δ18O) and deuterium isotopes (δD) techniques. Sketches of oxygen and deuterium isotope were total rainfall, throughfall, runoff, measurement at 5 soil depths (namely: 20 cm, 50 cm, 100 cm, 150 cm, and 200 cm), and oil palm stem. Results of this study showed huge variance in the values of oxygen and deuterium isotope. Based on Least Significant Difference (LSD) test, there was no significant value in the oxygen and deuterium isotope of stem water and others;however, a similar value was obtained at the depths of 0 - 20 cm and 20 - 50 cm with the stem water. This indicated that oil palm absorbed water from 0 - 50 cm depth. This result agreed with the oil palm rooting system, which has verified that the root quarter is the most active root of oil palm.展开更多
Based on a six-cylinder direct injection diesel engine, the engine operating condition was simulated by application AVL-FIRE software coupling the n-heptane reduced mechanism containing polycyclic aromatic hydrocarbon...Based on a six-cylinder direct injection diesel engine, the engine operating condition was simulated by application AVL-FIRE software coupling the n-heptane reduced mechanism containing polycyclic aromatic hydrocarbon (PAH) formation. The simulation and its verification test were both carried out under the maximum torque point. Then, the oxygen enriched combustion was simulated on the model, and the simulated condition was oxygen volume fraction from 21% to 30%. The simulation results show that, the oxygen enrichment (from 21% to 30%) increases the peak cylinder pressure of 3.32%, advances the start of combustion of 1.6 deg and rises the peak of average temperature in cylinder and wall heat flux. Among them, at the condition of 24% O2, the change of the results is the most significant. Benzene (A1) is one of the precursors of soot generated, the analysis of its impress-cuts of the mass distribution field in cylinder shows that, the increase of oxygen concentration can significantly inhibit the formation of benzene. But the oxygen enrichment makes the combustion more sufficient, cased a rise in the cylinder temperature, an extension in high temperature area, and an increment in the NOx emission.展开更多
The investigation shows that using internal combustion coal-oxygen burner for the intensification of melting in EAF is feasible.Internal combustion coal-oxygen burner is better than external combustion coal-oxygen bur...The investigation shows that using internal combustion coal-oxygen burner for the intensification of melting in EAF is feasible.Internal combustion coal-oxygen burner is better than external combustion coal-oxygen burner in the performance and energy saving of the process.Electrical consumption is decreased by 40 kW ? h/t,melting time is shortened by 18 min.The application of internal combustion coal-oxygen burner has a significant effect on decreasing EAF energy consumption.展开更多
Iron nitrate, nickel nitrate and cobalt nitrate were used as catalyst precursors to study their effects on carbon nanowires synthesized by ethanol catalytic combustion (ECC) process. The as-grown carbon nanowires were...Iron nitrate, nickel nitrate and cobalt nitrate were used as catalyst precursors to study their effects on carbon nanowires synthesized by ethanol catalytic combustion (ECC) process. The as-grown carbon nanowires were characterized by means of scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. The results show that relatively uniform nanowires will be formed when the catalyst precursor is iron nitrate; while helical structure or disordered structure will be formed when the catalyst precursor is nickel nitrate or cobalt nitrate.展开更多
Based on experiment results and theoretical analysis,pointed out that the method of coal susceptibility to spontaneous combustion determination with fluid oxygen adsorption can not present the essence of coal oxidatio...Based on experiment results and theoretical analysis,pointed out that the method of coal susceptibility to spontaneous combustion determination with fluid oxygen adsorption can not present the essence of coal oxidation process and oxidation reaction. The method is incorrect,paying attention at one aspect and ignoring the rest.The method is not reasonable for coal susceptibility to spontaneous combustion determination.Sus- ceptibility to spontaneous combustion of coal reflects chemical property of coal oxidation with oxygen absorption and heat release at low temperature.Coal's susceptibility to spon- taneous combustion is mainly decided by the number of molecules with reaction activation energy and activation molecule production rate at certain temperature.Therefore,index of susceptibility to spontaneous combustion should adopt accumulative value or trend of heat release or oxygen adsorption during oxidation process.展开更多
Bamboo-like carbon nanotubes were synthesized by ethanol catalytic combustion (ECC) technique with combustion method. Copper plate was employed as substrate, ethanol as carbon source, and iron chloride as catalyst pre...Bamboo-like carbon nanotubes were synthesized by ethanol catalytic combustion (ECC) technique with combustion method. Copper plate was employed as substrate, ethanol as carbon source, and iron chloride as catalyst precursor. The as-grown black powder was characterized by means of scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. The results show that the thinner bamboo-like carbon nanotubes have a relatively good structure that the compartment layers are more regular, while the thicker carbon nanotubes have a relatively irregular bamboo-like structure; the proposed method is simple to synthesize bamboo-like carbon nanotubes and has some advantages, such as flexible synthesis conditions, simple setup, and environment-friendly.展开更多
Through a lot of experiments, a new kind of stove using horizontal combustion tech-nique for bituminous coal briquet has been developed. Making use of this stove, studies have been made on burning process of bituminou...Through a lot of experiments, a new kind of stove using horizontal combustion tech-nique for bituminous coal briquet has been developed. Making use of this stove, studies have been made on burning process of bituminous coal briquet, distribution of temperature field in the stove, the regularities of evolution and combustion of volatile matter, the burning rate and edi-ciency of bituminous coal briquet, characteristics of fire-sealing and sulfur-retention. The results show that, with the technique, some achievements can be obtained in combustion of bituminous coal briquet, such as lower pollution that the flue gas black degree is below 0. 5R and dust con-centration is below 90 mg/m3. The stove’s combustion efficiency reaches 90%, sulfur fixing effi-ciency is 60%, and oO concentration is decreased by 40% compared with other traditional stoves. With so many advantages, the stove can be used extensively in civil stoves and smaller industrial boilers.展开更多
基金the National Natural Science Foundation of China(No.52072256)Shanxi Science and Technology Major Project(No.20201101016)+1 种基金Key R&D program of Shanxi Province(No.202102030201006)Research Project Supported by Shanxi Scholarship Council of China(HGKY2019031).
文摘Electrocatalytic oxygen reduction reaction(ORR)is one of the most important reactions in electrochemical energy technologies such as fuel cells and metal–O2/air batteries,etc.However,the essential catalysts to overcome its slow reaction kinetic always undergo a complex dynamic evolution in the actual catalytic process,and the concomitant intermediates and catalytic products also occur continuous conversion and reconstruction.This makes them difficult to be accurately captured,making the identification of ORR active sites and the elucidation of ORR mechanisms difficult.Thus,it is necessary to use extensive in-situ characterization techniques to proceed the real-time monitoring of the catalyst structure and the evolution state of intermediates and products during ORR.This work reviews the major advances in the use of various in-situ techniques to characterize the catalytic processes of various catalysts.Specifically,the catalyst structure evolutions revealed directly by in-situ techniques are systematically summarized,such as phase,valence,electronic transfer,coordination,and spin states varies.In-situ revelation of intermediate adsorption/desorption behavior,and the real-time monitoring of the product nucleation,growth,and reconstruction evolution are equally emphasized in the discussion.Other interference factors,as well as in-situ signal assignment with the aid of theoretical calculations,are also covered.Finally,some major challenges and prospects of in-situ techniques for future catalysts research in the ORR process are proposed.
基金This work was financially supported by the China Postdoctoral Science Foundation(No.2019M652169)the University Synergy Innovation Program of Anhui Province(No.GXXT-2019-016)+1 种基金the Natural Science Foundation of Anhui(No.JZ2018AKZR0063)the Fundamental Research Funds for the Central University,China(No.PA2019GDPK0044).
文摘Nanosized tungsten carbide(WC)/carbon(C)catalyst was synthesized via a novel ultra-rapid confinement combustion synthesis method.The amount of activated carbon(AC)plays an important role in the morphology and structure,controlling both the precursor and final powder.The WC particles synthesized inside the pores of the AC had been 10-20 nm because of the confinement of the pore structure and the large specific surface area of AC.When used for oxygen reduction performance,the half-wave potential was−0.24 V,and the electron transfer number was 3.45,indicating the main reaction process was the transfer of four electrons.The detailed electrocatalytic performance and underlying mechanism were investigated in this work.Our study provides a novel approach for the design of catalysts with new compositions and new structures,which are significant for promoting the commercialization of fuel cells.
基金Supported by the National Natural Science Foundation of China (No.50574046 and 50164002, )Natural Science Foun-dation of Yunnan Province (No. 2004E0012Q).
基金Supported by National Natural Science Foundation of China(Grant No.51176082)Importation and Development of High-Caliber Talents Project of Beijing Municipal Institutions of China(Grant No.CIT&TCD20140311)Beijing Municipal Natural Science Foundation of China(Grant No.SQKZ201510016004)
文摘For capturing and recycling of CO_2 in the internal combustion engine, Rankle cycle engine can reduce the exhaust pollutants effectively under the condition of ensuring the engine thermal efficiency by using the techniques of spraying water in the cylinder and optimizing the ignition advance angle. However, due to the water spray nozzle need to be installed on the cylinder, which increases the cylinder head design difficulty and makes the combustion conditions become more complicated. In this paper, a new method is presented to carry out the closing inlet and exhaust system for internal combustion engines. The proposed new method uses liquid oxygen to solidify part of cooled CO_2 from exhaust system into dry ice and the liquid oxygen turns into gas oxygen which is sent to inlet system. The other part of CO_2 is sent to inlet system and mixed with oxygen, which can reduce the oxygen-enriched combustion detonation tendency and make combustion stable. Computing grid of the IP52 FMI single-cylinder four-stroke gasoline-engine is established according to the actual shape of the combustion chamber using KIVA-3V program. The effects of exhaust gas recirculation(EGR) rate are analyzed on the temperatures, the pressures and the instantaneous heat release rates when the EGR rate is more than 8%. The possibility of enclosing intake and exhaust system for engine is verified. The carbon dioxide trapping device is designed and the IP52 FMI engine is transformed and the CO_2 capture experiment is carried out. The experimental results show that when the EGR rate is 36% for the optimum EGR rate. When the liquid oxygen of 35.80–437.40 g is imported into the device and last 1–20 min, respectively, 21.50–701.30 g dry ice is obtained. This research proposes a new design method which can capture CO_2 for vehicular internal combustion engine.
基金Financial support for this work provided by the National"Eleventh Five-Year" Key Scientific and Technological Support[Program (No. 2007BAK22B04)2008 independent task (No.SKLCRSM08B12)
文摘Various physical parameters, including gas concentrations (O2, CO, CH4, and H2) and temperatures at dif- ferent air velocities, were determined for full scale wood fires in the Chongqing Coal Research Institute fire test tunnel. Both experimental measurements and numerical simulations are discussed. The numer- ical analysis was performed with the computational fluid dynamics software package ''FLUENT''. The results show that the experimental data agree with the simulation results. The results verify that Roberts' theory of burning is correct. They also prove that the air velocity is the key factor that determines the type of combustion. Also, it is shown that secondary disasters are unlikely for oxygen rich combustion with a limited fire load.
基金support provided by the National Natural Science Foundation of China (No20807056)the Research Fund for the Doctoral Program of Higher Education of China (No20060290506)the Foundation of China University of Mining & Technology (Nos0H060097 and 0H080254)
文摘Coal samples in the air for three months were characterized by Thermogravimetric Analysis (TGA). The effect of a PVA oxygen-insulating barrier on the spontaneous combustion of coal was examined. The moisture loss activation energy, oxidation activation energy and combustion activation energy were calculated by an integral method using the Coats-Redfen formula. The results show that the tendency for spontaneous combustion of three coal samples (judged by the activation energy) falls in the order: CYW>YJL>SW. The oxidation activation energy and combustion activation energy of coal protected by the PVA oxygen-insulating barrier increased. A significant increase in the combustion activation energy was noted, especially for the CYW coal where the in-crease was 28.53 kJ/mol. Hence, oxidation of the protected coal samples was more difficult. The PVA oxygen-insulating barrier helps to prevent spontaneous combustion of the coal.
基金financially supported by the National Nature Science Foundation of China (No.51572019)
文摘To explore the reaction behavior of trace oxygen during the flash combustion process of falling FeSi75 powder in a nitrogen flow, a flash-combustion-synthesized Fe-Si_3N_4 sample was heat-treated to remove SiO_2. The samples before and after the treatment were investigated by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, and the formation mechanism of SiO_2 was investigated. The results show that SiO_2 in the Fe-Si_3N_4 is mainly located on the surface or around the Si_3N_4 particles in dense areas, existing in both crystalline and amorphous states; when the FeSi75 particles, which are less than 0.074 mm in size, fell in up-flowing hot N_2 stream, trace oxygen in the N_2 stream did not significantly hinder the nitridation of FeSi75 particles as it was consumed by the surface oxidation of the generated Si_3N_4 particles to form SiO_2. At the reaction zone, the oxidation of Si_3N_4 particles decreased the oxygen partial pressure in the N_2 stream and greatly reduced the opportunity for FeSi75 particles to be oxidized into SiO_2; by virtue of the SiO_2 film developed on the surface, the Si_3N_4 particles adhered to each other and formed dense areas in the material.
基金supported by the Beijing Science and Technology Program(Grant no.Z131100005613045)the National Natural Science Foundation of China(Grant no.51306015)the Fundamental Research Funds for the Central Universities(Grant no.FRF-SD-12-013A)
文摘The cycle life of oxygen carrier(OC) is crucial to the practical applications of chemical looping combustion(CLC). Cycle performance of Cu/SiO_2 prepared with a mechanical mixing method was evaluated based on a CLC process characterized with an added methane steam reforming step. The Cu/SiO_2 exhibited high redox reactivity in the initial cycles, while the performance degraded with cycle number. Through characterization of the degraded Cu/SiO_2, the performance degradation was mainly caused by the secondary particles' fragmentation and the fine particles' local agglomeration, which worsened the distribution and diffusion of the reactive gases in the packed bed. A regeneration method of the degraded OC based on re-granulation has been proposed, and its mechanism has been illustrated. With this method, the performance of the degraded OC through 420 redox cycles was recovered to a level close to the initial one.
文摘Four different pulverized coals have been used to study the effects of oxygen concentration on combustion characteristics under different enriched-oxygen conditions by entrained flow reactor experiments. The results show that: with the increase of oxygen concentration, the ignition temperature of four coals greatly decreases and the low volatile coals decrease faster; with the increase of oxygen concentration, the ignition mode of pulverized coal has an obviously transformation from homogeneous ignition to heterogeneous ignition, and the corresponding oxygen concentrations are about 40% and 50%-60% respectively for bituminous coal and lignite, and both about 30% for lean coal and anthracite; with the increase of oxygen concentration, the optimal pulverized coal concentrations of bituminous coal and lignite increase firstly and then decrease, but for lean coal and anthracite, the optimal pulverized coal concentrations decrease slowly with the increase of oxygen concentration.
文摘Manganese-doped zinc silicate powder samples were prepared successfully by solution combustion process,and their photoluminescence were investigated in ultraviolet region. The single-phase of Zn2- x SiO4: x Mn （0≤ x ≤0.10,willemite） was obtained by combustion synthesis at 600 ℃ for afew minutes,then heat treated at above 900 ℃ for 4 h. In the excitation spectra of Zn2- x SiO4: x Mn （0< x ≤0.10）,the strongest broad band at about 254 nm is observed and assigned to （（） 6A1）→（（） 4T1） transition of Mn （2+） monitoring at 525 nm emission. At about 525 nm,the intense broad band emission is observed under 254 nm excitation in Zn2- x SiO4: x Mn （0< x ≤0.10）. This broad band is attributed to （（） 4T1）→（（） 6A1） transition of Mn （2+）. The results indicate that photoluminescence efficiency,the location of the strongest excitation or emission band,and the optimum concentration of activator depend on starting materials,combustion temperatures,the dosage of fuels,and the size of powder samples etc..
文摘An advanced cyclone MHD combustor possesses its own featuresin terms of the requirements of MHD power generation. In this paper,the au-thors try to sum up the advanced combustion techniques used in MHD com-bustors and explain their functions by theoretica
文摘There is still very little information on the sources of water absorbed by oil palm plant. This information is very important for water management system in oil palm plantation. Thus, this study was carried out to determine current water sources absorbed by the oil palm roots using oxygen (δ18O) and deuterium isotopes (δD) techniques. Sketches of oxygen and deuterium isotope were total rainfall, throughfall, runoff, measurement at 5 soil depths (namely: 20 cm, 50 cm, 100 cm, 150 cm, and 200 cm), and oil palm stem. Results of this study showed huge variance in the values of oxygen and deuterium isotope. Based on Least Significant Difference (LSD) test, there was no significant value in the oxygen and deuterium isotope of stem water and others;however, a similar value was obtained at the depths of 0 - 20 cm and 20 - 50 cm with the stem water. This indicated that oil palm absorbed water from 0 - 50 cm depth. This result agreed with the oil palm rooting system, which has verified that the root quarter is the most active root of oil palm.
文摘Based on a six-cylinder direct injection diesel engine, the engine operating condition was simulated by application AVL-FIRE software coupling the n-heptane reduced mechanism containing polycyclic aromatic hydrocarbon (PAH) formation. The simulation and its verification test were both carried out under the maximum torque point. Then, the oxygen enriched combustion was simulated on the model, and the simulated condition was oxygen volume fraction from 21% to 30%. The simulation results show that, the oxygen enrichment (from 21% to 30%) increases the peak cylinder pressure of 3.32%, advances the start of combustion of 1.6 deg and rises the peak of average temperature in cylinder and wall heat flux. Among them, at the condition of 24% O2, the change of the results is the most significant. Benzene (A1) is one of the precursors of soot generated, the analysis of its impress-cuts of the mass distribution field in cylinder shows that, the increase of oxygen concentration can significantly inhibit the formation of benzene. But the oxygen enrichment makes the combustion more sufficient, cased a rise in the cylinder temperature, an extension in high temperature area, and an increment in the NOx emission.
文摘The investigation shows that using internal combustion coal-oxygen burner for the intensification of melting in EAF is feasible.Internal combustion coal-oxygen burner is better than external combustion coal-oxygen burner in the performance and energy saving of the process.Electrical consumption is decreased by 40 kW ? h/t,melting time is shortened by 18 min.The application of internal combustion coal-oxygen burner has a significant effect on decreasing EAF energy consumption.
基金Project (KM200510772013) supported by the Science and Technology Development Program of Education Committee of Beijing City Project(2005-2007) supported by Academic Innovative Team Program (Novel Sensor and Materials: Nanodevice and Nanomaterials) of Education Committee of Beijing City
文摘Iron nitrate, nickel nitrate and cobalt nitrate were used as catalyst precursors to study their effects on carbon nanowires synthesized by ethanol catalytic combustion (ECC) process. The as-grown carbon nanowires were characterized by means of scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. The results show that relatively uniform nanowires will be formed when the catalyst precursor is iron nitrate; while helical structure or disordered structure will be formed when the catalyst precursor is nickel nitrate or cobalt nitrate.
基金Innovative Team in Science and Technology of Arthui Province College and Universities(2006KJ005TD)Science of Fire,Nature Science Foundation of China(2001 CB409600)
文摘Based on experiment results and theoretical analysis,pointed out that the method of coal susceptibility to spontaneous combustion determination with fluid oxygen adsorption can not present the essence of coal oxidation process and oxidation reaction. The method is incorrect,paying attention at one aspect and ignoring the rest.The method is not reasonable for coal susceptibility to spontaneous combustion determination.Sus- ceptibility to spontaneous combustion of coal reflects chemical property of coal oxidation with oxygen absorption and heat release at low temperature.Coal's susceptibility to spon- taneous combustion is mainly decided by the number of molecules with reaction activation energy and activation molecule production rate at certain temperature.Therefore,index of susceptibility to spontaneous combustion should adopt accumulative value or trend of heat release or oxygen adsorption during oxidation process.
基金Project(KM200510772013) supported by the Science and Technology Development Program of Education Committee of Beijing City Project(2005-2007) supported by the Academic Innovative Team Porgram (Novel Sensor and Materials: Nanodevice and Nanomaterials) of Education Committee of Beijing City
文摘Bamboo-like carbon nanotubes were synthesized by ethanol catalytic combustion (ECC) technique with combustion method. Copper plate was employed as substrate, ethanol as carbon source, and iron chloride as catalyst precursor. The as-grown black powder was characterized by means of scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. The results show that the thinner bamboo-like carbon nanotubes have a relatively good structure that the compartment layers are more regular, while the thicker carbon nanotubes have a relatively irregular bamboo-like structure; the proposed method is simple to synthesize bamboo-like carbon nanotubes and has some advantages, such as flexible synthesis conditions, simple setup, and environment-friendly.
文摘Through a lot of experiments, a new kind of stove using horizontal combustion tech-nique for bituminous coal briquet has been developed. Making use of this stove, studies have been made on burning process of bituminous coal briquet, distribution of temperature field in the stove, the regularities of evolution and combustion of volatile matter, the burning rate and edi-ciency of bituminous coal briquet, characteristics of fire-sealing and sulfur-retention. The results show that, with the technique, some achievements can be obtained in combustion of bituminous coal briquet, such as lower pollution that the flue gas black degree is below 0. 5R and dust con-centration is below 90 mg/m3. The stove’s combustion efficiency reaches 90%, sulfur fixing effi-ciency is 60%, and oO concentration is decreased by 40% compared with other traditional stoves. With so many advantages, the stove can be used extensively in civil stoves and smaller industrial boilers.
