The amounts of soil nonexchangeable K extracted with 0.01 mL/ L oxalic acid and citric acid solutions and that with boiling 1 mL/ L HNO3 for ten minutes were remarkably significantly correlated with each other, and th...The amounts of soil nonexchangeable K extracted with 0.01 mL/ L oxalic acid and citric acid solutions and that with boiling 1 mL/ L HNO3 for ten minutes were remarkably significantly correlated with each other, and the amount extracted with the oxalic acid solution was higher than that with the citric acid solution. The soil nonexchangeable K release was comprised of two first-order kinetic processes. The faster one was ascribed to the interlayer K in outer sphere, while the slower one to that in inner sphere. The rate constants of the soil nonexchageable K were significantly correlated with the amounts of nonexchangeable K extracted with boiling ImL/ L HNO3 for ten minutes. Study on the fitness of different kinetic equations indicated that the first-order, parabolic diffusion and zero-order equations could all describe the release of soil nonexchangeable K. well, but Elovich equation was not suitable to describe it.展开更多
The controlling step and the extraction reaction rate equation of zinc extraction from Zn（II）-NH3 solution by using a newly synthesized organic compound, 2-acetyl-3-oxo-dithiobutyric acid-myristyl ester as the zinc ...The controlling step and the extraction reaction rate equation of zinc extraction from Zn（II）-NH3 solution by using a newly synthesized organic compound, 2-acetyl-3-oxo-dithiobutyric acid-myristyl ester as the zinc extractant, were clarified. The effects of agitation speed, specific interfacial area, temperature, extractant concentration and Zn ion concentration on the extraction rate are studied in constant interfacial area cell. The results show that the extraction rate depends on interfacial chemical reaction and diffusion by using this new extraetant to extract zinc, and the apparent activation energy of this extraction reaction is measured as 28.2 kJ/mol, which demonstrates that the extraction reaction is controlled by the mixed-controlled reaction rate. The apparent reaction orders a and b are measured as 1 and 0.38, and the constant k0 is 138.70. So, when extraction conditions are controlled as [HR]=20%-50%, T=0-30℃, N=120-177 r/min and S=72.6-127.5 m-1, the solvent extraction reaction rate can be depicted as v/（mol . m-2 . s-1 ） = 138.7. exp（ - 28 206/8.314T ）. [Zn 2＋ ]r ·[HR ]o0.38.展开更多
Composition estimation plays very important role in plant operation and control.Extended Kalman filter(EKF) is one of the most common estimators,which has been used in composition estimation of reactive batch distilla...Composition estimation plays very important role in plant operation and control.Extended Kalman filter(EKF) is one of the most common estimators,which has been used in composition estimation of reactive batch distillation,but its performance is heavily dependent on the thermodynamic modeling of vapor-liquid equilibrium,which is difficult to initialize and tune.In this paper an inferential state estimation scheme based on adaptive neuro-fuzzy inference system(ANFIS) ,which is a model base estimator,is employed for composition estimation by using temperature measurements in multicomponent reactive batch distillation.The state estimator is supported by data from a complete dynamic model that includes component and energy balance equations accompanied with thermodynamic relations and reaction kinetics.The mathematical model is verified by pilot plant data.The simulation results show that the ANFIS estimator provides reliable and accurate estimation for component concentrations in reactive batch distillation.The estimated states form a basis for improving the performance of reactive batch distillation either through decision making of an operator or through an automatic closed-loop control scheme.展开更多
In this study, the kinetics of isopropyl palmitate synthesis including the reaction mechanism was studied based on the two-step noncatalytic method. The liquid-phase diffusion effect on the reaction process was elimin...In this study, the kinetics of isopropyl palmitate synthesis including the reaction mechanism was studied based on the two-step noncatalytic method. The liquid-phase diffusion effect on the reaction process was eliminated by adjusting the stirring rate. The results showed that the two-step reaction followed a tetrahedral mechanism and conformed to second-order reaction kinetics. Nucleophilic attack on the carbonyl carbon afforded an intermediate, containing a tetrahedral carbon center. The intermediate ultimately decomposed by elimination of the leaving group, affording isopropyl palmitate. The experimental data were analyzed at different temperatures by the integral method. The kinetic equations of the each step were deduced, and the activation energy and frequency factor were obtained. Experiments were performed to verify the feasibility of kinetic equations, and the result showed that the kinetic equations were reliable. This study could be very signi ficant to both industrial application and determining the continuous production of isopropyl palmitate.展开更多
Synthesis and kinetics of dichloro-methoxybenzenes were studied from 1,2,4-trichlorobenzene and sodium methoxide in a temperature range of 353--383 K. Effects of molar ratio of reactants, solvent and reaction temperat...Synthesis and kinetics of dichloro-methoxybenzenes were studied from 1,2,4-trichlorobenzene and sodium methoxide in a temperature range of 353--383 K. Effects of molar ratio of reactants, solvent and reaction temperature were investigated. Reaction products include three isomers. The order of selectivity for the three isomers was 1,4-dichloro-2-methoxybenzene〉〉2,4-dichoro-1-methoxybenzene〉,2-dichoro-4-methoxybenzene. Kinetic equations for the parallel liquid-solid interface reaction between 1,2,4-trichlorobenzene and sodium methoxide were established in the absence of catalyst. Kinetic parameters such as the pre-exponential factors and the activation energy were deter- mined with the Arrhenius equation.展开更多
By coupling the heat transfer equation with semi-global chemical reaction kinetic equations, a onedimensional, unsteady mathematical model is developed to describe the pyrolysis of single biomass pellet in the pyrolys...By coupling the heat transfer equation with semi-global chemical reaction kinetic equations, a onedimensional, unsteady mathematical model is developed to describe the pyrolysis of single biomass pellet in the pyrolysis zone of downdraft gasifier. The simulation results in inert atmosphere and pyrolysis zone agree well with the published experimental results. The pyrolysis of biomass pellets in pyrolysis zone is investigated, and the results show that the estimated convective heat transfer coefficient and emissivity coefficient are suitable. The mean pyrolysis time is 15.22%, shorter than that in inert atmosphere, and the pellet pyrolysis process in pyrolysis zone belongs to fast pyrolysis. Among the pyrolysis products, tar yield is the most, gas the second, and char the least. During pyrolysis, the temperature change near the center is contrary to that near the surface. Pyrolysis gradually moves inwards layer by layer. With the increase of pyrolysis temperature and pellet diameter, the total pyrolysis time, tar yield, char yield and gas yield change in different ways. The height of pyrolysis zone is calculated to be 1.51—3.51 times of the characteristic pellet diameter.展开更多
Different extensions, such as Transition State theory of Eyring-Polanyi-Evans model of the original Born-Kramers-Slater Model for the Velocity of Chemical Reactions are discussed based on Smoluchowski and Fokker-Plank...Different extensions, such as Transition State theory of Eyring-Polanyi-Evans model of the original Born-Kramers-Slater Model for the Velocity of Chemical Reactions are discussed based on Smoluchowski and Fokker-Plank equations with various properties of Brownian motion and including 1-, 2-, 3-, and multi- dimensional models with applications in Neuroscience.展开更多
The sugars potential ofPaulownia tomentosa is estimated by dilute acid pretreatment and cellulase hydrolysis. The kinetics of dilute （1%） sulfuric acid hydrolysis is studied at temperatures of 100 ℃, 120 ℃ and 130...The sugars potential ofPaulownia tomentosa is estimated by dilute acid pretreatment and cellulase hydrolysis. The kinetics of dilute （1%） sulfuric acid hydrolysis is studied at temperatures of 100 ℃, 120 ℃ and 130 ℃, while the kinetics of the subsequent enzyme hydrolysis is examined at a temperature of 50 ℃ and reaction time varied from 60 to 300 min using cellulase complex NS 50013 and β-glucosidase N S 50010. The reducing sugars formation is modeled as a pseudo-homogeneous first order reaction in view of the kinetics of dilute sulfuric acid hydrolysis. The results obtained indicate that the reaction proceeds in an energetically homogeneous system （E = const） providing identical accessibility of the reagent to the hydrolyzing sites （A = const）. The enzyme hydrolysis kinetics follows heterogeneous catalytic mechanism. The process is described by an exponential kinetic equation, which is well recognised in case of processes on uniformly inhomogeneous surfaces. The current rate decreases significantly probably because of exhaustion of the available active sites on the surface and steric hindrances due to the presence of lignin. This investigation provides information of importance for the fermentation step of the bio-ethanol production process.展开更多
This paper presents the results of an application of a first-order conditional moment closure （CMC） approach coupled with a semi-empirical soot model to investigate the effect of various detailed combustion chemistr...This paper presents the results of an application of a first-order conditional moment closure （CMC） approach coupled with a semi-empirical soot model to investigate the effect of various detailed combustion chemistry schemes on soot formation and destruction in turbulent non-premixed flames. A two-equation soot model repre- senting soot particle nucleation, growth, coagulation and oxidation, was incorporated into the CMC model. The turbulent flow-field of both flames is described using the Favre-averaged fluid-flow equations, applying a stan- dard k-c turbulence model. A number of five reaction kinetic mechanisms having 50 - 100 species and 200 - 1000 elementary reactions called ABF, Miller-Bowman, GRI-Mech3.0, Warnatz, and Qin were employed to study the effect of combustion chemistry schemes on soot predictions. The results showed that of various kinetic schemes being studied, each yields similar accuracy in temperature prediction when compared with experimental data. With respect to soot prediction, the kinetic scheme containing benzene elementary reactions tends to result in a better prediction on soot concentrations in comparison to those contain no benzene elementary reactions. Among five kinetic mechanisms being studied, the Qin combustion scheme mechanism turned to yield the best prediction on both flame temperature and soot levels.展开更多
Coal gangue was calcinated under air, nitrogen, carbon dioxide, air-hydrogen, and hydrogen atmospheres. The effects of different calcination temperatures and atmospheres on the mineral composition of activated coal ga...Coal gangue was calcinated under air, nitrogen, carbon dioxide, air-hydrogen, and hydrogen atmospheres. The effects of different calcination temperatures and atmospheres on the mineral composition of activated coal gangue were investigated by X-ray diffraction. Moreover, the acid leaching kinetics of aluminum oxide from coal gangue was investigated with sulfuric acid. It showed that the air atmosphere promoted kaolinite decomposition during coal gangue calcination. The hydrogen atmosphere promoted the activation and decomposition of kaolinite at reaction temperatures exceeding 650℃. The carbon dioxide atmosphere eliminated the influence of residual carbon on coal gangue. When the ratio of acid/coal gangue was 1.5 and reaction temperature was 650℃, the sulfuric acid leaching rate under air, air-hydrogen, carbon dioxide, hydrogen and nitrogen atmospheres were 93.66%, 90.90%, 84.06%, 81.91% and 77.54% respectively. The acid leaching reaction process conformed to unreacted shrinking core model of particle unchanged, and was controlled by the interracial chemical reaction. The reaction kinetic equation for the leaching process was 1-（1-x）1/3=kt with an apparent activation energy of 48.97 kJ/mol.展开更多
文摘The amounts of soil nonexchangeable K extracted with 0.01 mL/ L oxalic acid and citric acid solutions and that with boiling 1 mL/ L HNO3 for ten minutes were remarkably significantly correlated with each other, and the amount extracted with the oxalic acid solution was higher than that with the citric acid solution. The soil nonexchangeable K release was comprised of two first-order kinetic processes. The faster one was ascribed to the interlayer K in outer sphere, while the slower one to that in inner sphere. The rate constants of the soil nonexchageable K were significantly correlated with the amounts of nonexchangeable K extracted with boiling ImL/ L HNO3 for ten minutes. Study on the fitness of different kinetic equations indicated that the first-order, parabolic diffusion and zero-order equations could all describe the release of soil nonexchangeable K. well, but Elovich equation was not suitable to describe it.
基金Foundation item： Project（51174240） supported by the National Natural Science Foundation of China Project（2006BA02B04-4-2） supported by the National Eleventh Five-Year Research Program of China Project（20100908） supported by Scientific and Industrial Research Organisation of Guangdong Province, China
文摘The controlling step and the extraction reaction rate equation of zinc extraction from Zn（II）-NH3 solution by using a newly synthesized organic compound, 2-acetyl-3-oxo-dithiobutyric acid-myristyl ester as the zinc extractant, were clarified. The effects of agitation speed, specific interfacial area, temperature, extractant concentration and Zn ion concentration on the extraction rate are studied in constant interfacial area cell. The results show that the extraction rate depends on interfacial chemical reaction and diffusion by using this new extraetant to extract zinc, and the apparent activation energy of this extraction reaction is measured as 28.2 kJ/mol, which demonstrates that the extraction reaction is controlled by the mixed-controlled reaction rate. The apparent reaction orders a and b are measured as 1 and 0.38, and the constant k0 is 138.70. So, when extraction conditions are controlled as [HR]=20%-50%, T=0-30℃, N=120-177 r/min and S=72.6-127.5 m-1, the solvent extraction reaction rate can be depicted as v/（mol . m-2 . s-1 ） = 138.7. exp（ - 28 206/8.314T ）. [Zn 2＋ ]r ·[HR ]o0.38.
文摘Composition estimation plays very important role in plant operation and control.Extended Kalman filter(EKF) is one of the most common estimators,which has been used in composition estimation of reactive batch distillation,but its performance is heavily dependent on the thermodynamic modeling of vapor-liquid equilibrium,which is difficult to initialize and tune.In this paper an inferential state estimation scheme based on adaptive neuro-fuzzy inference system(ANFIS) ,which is a model base estimator,is employed for composition estimation by using temperature measurements in multicomponent reactive batch distillation.The state estimator is supported by data from a complete dynamic model that includes component and energy balance equations accompanied with thermodynamic relations and reaction kinetics.The mathematical model is verified by pilot plant data.The simulation results show that the ANFIS estimator provides reliable and accurate estimation for component concentrations in reactive batch distillation.The estimated states form a basis for improving the performance of reactive batch distillation either through decision making of an operator or through an automatic closed-loop control scheme.
文摘In this study, the kinetics of isopropyl palmitate synthesis including the reaction mechanism was studied based on the two-step noncatalytic method. The liquid-phase diffusion effect on the reaction process was eliminated by adjusting the stirring rate. The results showed that the two-step reaction followed a tetrahedral mechanism and conformed to second-order reaction kinetics. Nucleophilic attack on the carbonyl carbon afforded an intermediate, containing a tetrahedral carbon center. The intermediate ultimately decomposed by elimination of the leaving group, affording isopropyl palmitate. The experimental data were analyzed at different temperatures by the integral method. The kinetic equations of the each step were deduced, and the activation energy and frequency factor were obtained. Experiments were performed to verify the feasibility of kinetic equations, and the result showed that the kinetic equations were reliable. This study could be very signi ficant to both industrial application and determining the continuous production of isopropyl palmitate.
文摘Synthesis and kinetics of dichloro-methoxybenzenes were studied from 1,2,4-trichlorobenzene and sodium methoxide in a temperature range of 353--383 K. Effects of molar ratio of reactants, solvent and reaction temperature were investigated. Reaction products include three isomers. The order of selectivity for the three isomers was 1,4-dichloro-2-methoxybenzene〉〉2,4-dichoro-1-methoxybenzene〉,2-dichoro-4-methoxybenzene. Kinetic equations for the parallel liquid-solid interface reaction between 1,2,4-trichlorobenzene and sodium methoxide were established in the absence of catalyst. Kinetic parameters such as the pre-exponential factors and the activation energy were deter- mined with the Arrhenius equation.
文摘By coupling the heat transfer equation with semi-global chemical reaction kinetic equations, a onedimensional, unsteady mathematical model is developed to describe the pyrolysis of single biomass pellet in the pyrolysis zone of downdraft gasifier. The simulation results in inert atmosphere and pyrolysis zone agree well with the published experimental results. The pyrolysis of biomass pellets in pyrolysis zone is investigated, and the results show that the estimated convective heat transfer coefficient and emissivity coefficient are suitable. The mean pyrolysis time is 15.22%, shorter than that in inert atmosphere, and the pellet pyrolysis process in pyrolysis zone belongs to fast pyrolysis. Among the pyrolysis products, tar yield is the most, gas the second, and char the least. During pyrolysis, the temperature change near the center is contrary to that near the surface. Pyrolysis gradually moves inwards layer by layer. With the increase of pyrolysis temperature and pellet diameter, the total pyrolysis time, tar yield, char yield and gas yield change in different ways. The height of pyrolysis zone is calculated to be 1.51—3.51 times of the characteristic pellet diameter.
文摘Different extensions, such as Transition State theory of Eyring-Polanyi-Evans model of the original Born-Kramers-Slater Model for the Velocity of Chemical Reactions are discussed based on Smoluchowski and Fokker-Plank equations with various properties of Brownian motion and including 1-, 2-, 3-, and multi- dimensional models with applications in Neuroscience.
文摘The sugars potential ofPaulownia tomentosa is estimated by dilute acid pretreatment and cellulase hydrolysis. The kinetics of dilute （1%） sulfuric acid hydrolysis is studied at temperatures of 100 ℃, 120 ℃ and 130 ℃, while the kinetics of the subsequent enzyme hydrolysis is examined at a temperature of 50 ℃ and reaction time varied from 60 to 300 min using cellulase complex NS 50013 and β-glucosidase N S 50010. The reducing sugars formation is modeled as a pseudo-homogeneous first order reaction in view of the kinetics of dilute sulfuric acid hydrolysis. The results obtained indicate that the reaction proceeds in an energetically homogeneous system （E = const） providing identical accessibility of the reagent to the hydrolyzing sites （A = const）. The enzyme hydrolysis kinetics follows heterogeneous catalytic mechanism. The process is described by an exponential kinetic equation, which is well recognised in case of processes on uniformly inhomogeneous surfaces. The current rate decreases significantly probably because of exhaustion of the available active sites on the surface and steric hindrances due to the presence of lignin. This investigation provides information of importance for the fermentation step of the bio-ethanol production process.
基金Supported by Ministry of National Education,Republic of Indonesia No.433/SP2H/PP/DP2M/VI/2010
文摘This paper presents the results of an application of a first-order conditional moment closure （CMC） approach coupled with a semi-empirical soot model to investigate the effect of various detailed combustion chemistry schemes on soot formation and destruction in turbulent non-premixed flames. A two-equation soot model repre- senting soot particle nucleation, growth, coagulation and oxidation, was incorporated into the CMC model. The turbulent flow-field of both flames is described using the Favre-averaged fluid-flow equations, applying a stan- dard k-c turbulence model. A number of five reaction kinetic mechanisms having 50 - 100 species and 200 - 1000 elementary reactions called ABF, Miller-Bowman, GRI-Mech3.0, Warnatz, and Qin were employed to study the effect of combustion chemistry schemes on soot predictions. The results showed that of various kinetic schemes being studied, each yields similar accuracy in temperature prediction when compared with experimental data. With respect to soot prediction, the kinetic scheme containing benzene elementary reactions tends to result in a better prediction on soot concentrations in comparison to those contain no benzene elementary reactions. Among five kinetic mechanisms being studied, the Qin combustion scheme mechanism turned to yield the best prediction on both flame temperature and soot levels.
基金supported by National Natural Science Foundation of China(51074170)Shaanxi Key Technology R&D Program(2016GY-147)+1 种基金Key Laboratory of Coal Resources Exploration and Comprehensive UtilizationMinistry of Land and Resources Open Research Topic(KF2016-3)
文摘Coal gangue was calcinated under air, nitrogen, carbon dioxide, air-hydrogen, and hydrogen atmospheres. The effects of different calcination temperatures and atmospheres on the mineral composition of activated coal gangue were investigated by X-ray diffraction. Moreover, the acid leaching kinetics of aluminum oxide from coal gangue was investigated with sulfuric acid. It showed that the air atmosphere promoted kaolinite decomposition during coal gangue calcination. The hydrogen atmosphere promoted the activation and decomposition of kaolinite at reaction temperatures exceeding 650℃. The carbon dioxide atmosphere eliminated the influence of residual carbon on coal gangue. When the ratio of acid/coal gangue was 1.5 and reaction temperature was 650℃, the sulfuric acid leaching rate under air, air-hydrogen, carbon dioxide, hydrogen and nitrogen atmospheres were 93.66%, 90.90%, 84.06%, 81.91% and 77.54% respectively. The acid leaching reaction process conformed to unreacted shrinking core model of particle unchanged, and was controlled by the interracial chemical reaction. The reaction kinetic equation for the leaching process was 1-（1-x）1/3=kt with an apparent activation energy of 48.97 kJ/mol.
