Normal diffusion flame(NDF)of acid gas with a H_(2)S concentration below 50.0%(vol)generally exhibits a low flame temperature in a low-level oxygen enrichment atmosphere under Claus conditions,resulting in flame insta...Normal diffusion flame(NDF)of acid gas with a H_(2)S concentration below 50.0%(vol)generally exhibits a low flame temperature in a low-level oxygen enrichment atmosphere under Claus conditions,resulting in flame instability.This research proposed that inverse diffusion flame(IDF)was applied to acid gas combustion for enhancing flame temperature.IDF of acid gas was compared with fuel gas cocombustion(FGC),split flow of acid gas(SFAG)and high-level oxygen enrichment combustion(OEC).Additionally,the effect of CO_(2)addition on the IDF of H_(2)S was investigated.The results indicated that a stable flame could be observed in the IDF of acid gas,its peak flame temperature was about 801.0 K,which was higher than that in the OEC,FGC and SFAG with a value of about 591.0,684.0 and 734.0 K,respectively.IDF of acid gas was contributed to the formation of sulfur and H_(2),and mainly involved the oxidation zone and the chemical decomposition and oxidation zone in sequence.In the IDF,CO_(2)exhibited a better oxidation performance,and the peak flame temperature was decreased by about 21.0 K with an increase in CO_(2)addition from 50.8%to 59.5%(vol),whereas significantly enhanced the oxidation reaction rate of H_(2)S,and the peak volume fraction of SO_(2)was increased from 5.812%to 7.075%.The application of IDF to acid gas combustion achieved the objective for improving flame temperature in low-level oxygen enrichment atmosphere under Claus conditions,providing a new perspective in the sulfur recovery and hydrogen production from acid gas.展开更多
Dimethyl carbonate(DMC)is an environmentally oxygenated compound which can be used efficiently for soot reduction.This paper compared the soot reduction,soot nanostructure and oxidation reactivity from inverse diffusi...Dimethyl carbonate(DMC)is an environmentally oxygenated compound which can be used efficiently for soot reduction.This paper compared the soot reduction,soot nanostructure and oxidation reactivity from inverse diffusion flames(IDFs)of the hydrocarbon fuels,namely n-heptane and isooctane doped with DMC.Effects of DMC additions on soot reduction were discussed.DMC addition is more effective for the soot reduction of n-heptane/DMC IDF than isooctane/DMC IDF.The morphology and nanostructures of soot particles were investigated by Transmission Electron Microscopy(TEM)and High Resolution TEM(HRTEM),and the soot graphitization and oxidation reactivity were analyzed by X-ray Diflfraction(XRD)and Thermogravimetric Analyzer(TGA),respectively.The results of HRTEM images showed that many larger aggregates were observed for the structures of soot particles from IDFs with DMC additions.The soot particles exhibited more liquid-like material,more amorphous,higher disorganized layers,and less graphitic than that of IDFs without DMC additions.With increasing of DMC blending rate,soot particles changed younger to have shorter fringe length,higher tortuosity,and greater fringe separation.Based on the XRD and TGA results,the degree of the soot graphitization level decreased;the soot mass lost significantly faster,and the soot become more reactive.展开更多
The soot formation model based on inverse ethylene diffusion flames was performed to study the sensitivity of the soot formation process to the prediction results.The effects of efficiency parameters such as soot ince...The soot formation model based on inverse ethylene diffusion flames was performed to study the sensitivity of the soot formation process to the prediction results.The effects of efficiency parameters such as soot inception,surface growth and coagulation on the simulation results were studied by using the adjustable efficiency model.In addition,the reversible soot model and conjugate heat transfer(CHT)model were also introduced to explore their advantages.Results indicated that,among adjustable efficiency parameters,the nucleation efficiency had the greatest influence on the predicted soot and PAHs distributions,while the Habstraction-C2H2-addition(HACA)process and PAH adsorption surface growth efficiencies impacted little.The adjustable efficiency parameters had a significant effect on the concentration of soot gaseous precursors and soot particles,but their effects on temperature,gas phase molecules,and intermediate species were not obvious.When the nucleation efficiency increased from 2×10^(-6)to 1×10^(-4),the predicted value of the integrated soot was increased by nearly 50%,and the maximum primary particle number density and the number of aggregates were increased by an order of magnitude.The maximum concentration of BAPYR was doubled.However,the peak temperature along the axial direction increased by only 3.5 K.Using the reversible soot model,the approximation results of the adjustable efficiency parameters could be modified,which showed the feasibility of the model.The use of the CHT model promoted pyrolysis of the fuel below the outlet of the fuel tube,with high-temperature zones,soot zones,and PAHs zones moving towards higher flame heights.Besides,when using the reversible model and the CHT model,the maximum soot volume fraction decreased by 39%compared with the basic efficiency parameters,while the concentration of BAPYR increased by 162%,and the concentrations of gas phase species were decreased.展开更多
One way for reducing tar is oxidative and thermal cracking by partial combustion of the biomass producer gas in the gas reformer. Cracking and polymerization of the tar occur simultaneously at the proximity of inverse...One way for reducing tar is oxidative and thermal cracking by partial combustion of the biomass producer gas in the gas reformer. Cracking and polymerization of the tar occur simultaneously at the proximity of inverse diffusion flame. Experimental study has been performed to clarify the effect of hydrogen concentration on soot formation and the growth of polycyclic aromatic hydrocarbons. In the present study, hydrogen concentration is controlled by the small amount of hydrogen addition to the oxidizer. The main results are as follows. Soot formation is suppressed by the small amount of hydrogen addition. The suppression of soot formation is caused by higher concentration of hydrogen. Carbon yield increases by hydrogen addition since carbon content in the undetectable components by the integrated gas chromatograph decreases. In addition, the increase in carbon yield is caused mainly by the increase in carbon monoxide stemmed from reforming of high-boiling components.展开更多
Time-fractional diffusion equations are of great interest and importance on describing the power law decay for diffusion in porous media. In this paper, to identify the diffusion rate, i.e., the heterogeneity of mediu...Time-fractional diffusion equations are of great interest and importance on describing the power law decay for diffusion in porous media. In this paper, to identify the diffusion rate, i.e., the heterogeneity of medium, the authors consider an inverse coefficient problem utilizing finite measurements and obtain a local HSlder type conditional stability based upon two Carleman estimates for the corresponding differential equations of integer orders.展开更多
On the basis of the detailed field work, compositions and contents of plagioclase and K - feldspar,determination of ordering degree, statistical analysis of plagioclase elongation index, mass-balance calculation and m...On the basis of the detailed field work, compositions and contents of plagioclase and K - feldspar,determination of ordering degree, statistical analysis of plagioclase elongation index, mass-balance calculation and mineral spatial distribution and geochemistry, it is concluded that the migmatites in the Dabie complex are characterized by the presence of thermocenters. There are regular changes in mineral character in the migmatites from the centers outwards. The dominant genetic mechanism is anatexis and metasomatism, whose intensities decrease from the centers outwards. Finally, according to the simulated experiment on Liesegang' s rings and non-linear dynamics (dissipative structure theory), the dynamic mechanism of migmatization is profoundly expouded as consisting of the early-stage metasomatism induced by the thermal anomaly, the cardinal-stage anatexis induced by the early-stage matasomatism and finally the last-stage post-anatexis metasomatism.展开更多
基金supported by the National Natural Science Foundation of China(22178114,U23A20131)the social development science and technology tackling project of 2021"Scientific and Innovative Action Plan of Shanghai"(21DZ1209000)。
文摘Normal diffusion flame(NDF)of acid gas with a H_(2)S concentration below 50.0%(vol)generally exhibits a low flame temperature in a low-level oxygen enrichment atmosphere under Claus conditions,resulting in flame instability.This research proposed that inverse diffusion flame(IDF)was applied to acid gas combustion for enhancing flame temperature.IDF of acid gas was compared with fuel gas cocombustion(FGC),split flow of acid gas(SFAG)and high-level oxygen enrichment combustion(OEC).Additionally,the effect of CO_(2)addition on the IDF of H_(2)S was investigated.The results indicated that a stable flame could be observed in the IDF of acid gas,its peak flame temperature was about 801.0 K,which was higher than that in the OEC,FGC and SFAG with a value of about 591.0,684.0 and 734.0 K,respectively.IDF of acid gas was contributed to the formation of sulfur and H_(2),and mainly involved the oxidation zone and the chemical decomposition and oxidation zone in sequence.In the IDF,CO_(2)exhibited a better oxidation performance,and the peak flame temperature was decreased by about 21.0 K with an increase in CO_(2)addition from 50.8%to 59.5%(vol),whereas significantly enhanced the oxidation reaction rate of H_(2)S,and the peak volume fraction of SO_(2)was increased from 5.812%to 7.075%.The application of IDF to acid gas combustion achieved the objective for improving flame temperature in low-level oxygen enrichment atmosphere under Claus conditions,providing a new perspective in the sulfur recovery and hydrogen production from acid gas.
基金This work was supported by the National Natural Science Foundation of China(51706103,51822605,51776181)the Fundamental Research Funds for the Central Universities,China(CEPE2019010,30920031103)+1 种基金the Open Project of State Key Laboratory of Clean Energy Utilization,Zhejiang University,China(ZJUCEU2017011)Bo Jiang thanks the great support given by the China Scholarship Council(201906845024).
文摘Dimethyl carbonate(DMC)is an environmentally oxygenated compound which can be used efficiently for soot reduction.This paper compared the soot reduction,soot nanostructure and oxidation reactivity from inverse diffusion flames(IDFs)of the hydrocarbon fuels,namely n-heptane and isooctane doped with DMC.Effects of DMC additions on soot reduction were discussed.DMC addition is more effective for the soot reduction of n-heptane/DMC IDF than isooctane/DMC IDF.The morphology and nanostructures of soot particles were investigated by Transmission Electron Microscopy(TEM)and High Resolution TEM(HRTEM),and the soot graphitization and oxidation reactivity were analyzed by X-ray Diflfraction(XRD)and Thermogravimetric Analyzer(TGA),respectively.The results of HRTEM images showed that many larger aggregates were observed for the structures of soot particles from IDFs with DMC additions.The soot particles exhibited more liquid-like material,more amorphous,higher disorganized layers,and less graphitic than that of IDFs without DMC additions.With increasing of DMC blending rate,soot particles changed younger to have shorter fringe length,higher tortuosity,and greater fringe separation.Based on the XRD and TGA results,the degree of the soot graphitization level decreased;the soot mass lost significantly faster,and the soot become more reactive.
基金supported by the Jiangsu Provincial Natural Science Foundation of China(Grant No.BK20220955)the National Natural Science Foundation of China(Grant No.52076110)+1 种基金China Postdoctoral Science Foundation(Grant No.2021M701719)the Fundamental Research Funds for the Central Universities(Grant No.30922010409)。
文摘The soot formation model based on inverse ethylene diffusion flames was performed to study the sensitivity of the soot formation process to the prediction results.The effects of efficiency parameters such as soot inception,surface growth and coagulation on the simulation results were studied by using the adjustable efficiency model.In addition,the reversible soot model and conjugate heat transfer(CHT)model were also introduced to explore their advantages.Results indicated that,among adjustable efficiency parameters,the nucleation efficiency had the greatest influence on the predicted soot and PAHs distributions,while the Habstraction-C2H2-addition(HACA)process and PAH adsorption surface growth efficiencies impacted little.The adjustable efficiency parameters had a significant effect on the concentration of soot gaseous precursors and soot particles,but their effects on temperature,gas phase molecules,and intermediate species were not obvious.When the nucleation efficiency increased from 2×10^(-6)to 1×10^(-4),the predicted value of the integrated soot was increased by nearly 50%,and the maximum primary particle number density and the number of aggregates were increased by an order of magnitude.The maximum concentration of BAPYR was doubled.However,the peak temperature along the axial direction increased by only 3.5 K.Using the reversible soot model,the approximation results of the adjustable efficiency parameters could be modified,which showed the feasibility of the model.The use of the CHT model promoted pyrolysis of the fuel below the outlet of the fuel tube,with high-temperature zones,soot zones,and PAHs zones moving towards higher flame heights.Besides,when using the reversible model and the CHT model,the maximum soot volume fraction decreased by 39%compared with the basic efficiency parameters,while the concentration of BAPYR increased by 162%,and the concentrations of gas phase species were decreased.
文摘One way for reducing tar is oxidative and thermal cracking by partial combustion of the biomass producer gas in the gas reformer. Cracking and polymerization of the tar occur simultaneously at the proximity of inverse diffusion flame. Experimental study has been performed to clarify the effect of hydrogen concentration on soot formation and the growth of polycyclic aromatic hydrocarbons. In the present study, hydrogen concentration is controlled by the small amount of hydrogen addition to the oxidizer. The main results are as follows. Soot formation is suppressed by the small amount of hydrogen addition. The suppression of soot formation is caused by higher concentration of hydrogen. Carbon yield increases by hydrogen addition since carbon content in the undetectable components by the integrated gas chromatograph decreases. In addition, the increase in carbon yield is caused mainly by the increase in carbon monoxide stemmed from reforming of high-boiling components.
基金supported by the National Natural Science Foundation of China(No.11101093)Shanghai Science and Technology Commission(Nos.11ZR1402800,11PJ1400800)
文摘Time-fractional diffusion equations are of great interest and importance on describing the power law decay for diffusion in porous media. In this paper, to identify the diffusion rate, i.e., the heterogeneity of medium, the authors consider an inverse coefficient problem utilizing finite measurements and obtain a local HSlder type conditional stability based upon two Carleman estimates for the corresponding differential equations of integer orders.
基金A project supported by the China National Natural Science Foundation(No.49070079)
文摘On the basis of the detailed field work, compositions and contents of plagioclase and K - feldspar,determination of ordering degree, statistical analysis of plagioclase elongation index, mass-balance calculation and mineral spatial distribution and geochemistry, it is concluded that the migmatites in the Dabie complex are characterized by the presence of thermocenters. There are regular changes in mineral character in the migmatites from the centers outwards. The dominant genetic mechanism is anatexis and metasomatism, whose intensities decrease from the centers outwards. Finally, according to the simulated experiment on Liesegang' s rings and non-linear dynamics (dissipative structure theory), the dynamic mechanism of migmatization is profoundly expouded as consisting of the early-stage metasomatism induced by the thermal anomaly, the cardinal-stage anatexis induced by the early-stage matasomatism and finally the last-stage post-anatexis metasomatism.
