The increasing production and release of synthetic organic chemicals,including pharmaceuticals,into our envi-ronment has allowed these substances to accumulate in our surface water systems.Current purification technol...The increasing production and release of synthetic organic chemicals,including pharmaceuticals,into our envi-ronment has allowed these substances to accumulate in our surface water systems.Current purification technolo-gies have been unable to eliminate these pollutants,resulting in their ongoing release into aquatic ecosystems.This study focuses on cloperastine(CPS),a cough suppressant and antihistamine medication.The environmental impact of CPS usage has become a concern,mainly due to its increased detection during the COVID-19 pandemic.CPS has been found in wastewater treatment facilities,effluents from senior living residences,river waters,and sewage sludge.However,the photosensitivity of CPS and its photodegradation profile remain largely unknown.This study investigates the photodegradation process of CPS under simulated tertiary treatment conditions using UV photolysis,a method commonly applied in some wastewater treatment plants.Several transformation prod-ucts were identified,evaluating their kinetic profiles using chemometric approaches(i.e.,curve fitting and the hard-soft multivariate curve resolution-alternating least squares(HS-MCR-ALS)algorithm)and calculating the reaction quantum yield.As a result,three different transformation products have been detected and correctly identified.In addition,a comprehensive description of the kinetic pathway involved in the photodegradation process of the CPS drug has been provided,including observed kinetic rate constants.展开更多
Hydrocarbon generation kinetics are influenced by complex factors,including temperature,reaction time,pressure,and molecular structure,which render simple modeling approaches inadequate for accurately simulating metha...Hydrocarbon generation kinetics are influenced by complex factors,including temperature,reaction time,pressure,and molecular structure,which render simple modeling approaches inadequate for accurately simulating methane generation.The closed-system pyrolysis experiment,a common method to study hydrocarbon generation,poses challenges for kinetic parameter regression due to limited data points.This limitation necessitates the application of sophisticated data analysis techniques to extract meaningful insights from sparse experimental data.This paper establishes a quantitative relationship between methane production and the thermal process through closed system pyrolysis experiments.A nonlinear regression model using multiple algorithms is established based on this quantitative relationship.Accordingly,a method that can quantitatively invert the methane generation kinetic parameters corresponding to the samples based on the experimental data is provided.Based on this theoretical model,a computer program capable of processing experimental data is designed and implemented.Practical analyses are performed using the method above for three samples:a coal sample from the Yulong,Guizhou;a solid bitumen sample from Guangyuan,Sichuan;and a marlstone sample containing type Ⅰ kerogen from Luquan,Yunnan.The results obtained agree with the qualitative estimates based on hydrocarbon generation kinetic theory using the previous method.Thus,the validity of the new data processing method,the new mathematical model,and the data processing procedures are verified.展开更多
Continuous casting of high-titanium steels face significant challenges due to steel-flux reactions,which will cause rapid compositional deviations and impair operational stability.A kinetic model to predict real-time ...Continuous casting of high-titanium steels face significant challenges due to steel-flux reactions,which will cause rapid compositional deviations and impair operational stability.A kinetic model to predict real-time mold flux composition evolution by integrating multicomponent mixed-transport-control theory with thermodynamics computing platform was developed in the current study.The model employed a cyclic time-step algorithm to compute thermodynamic equilibrium in reaction layer,mass transfer flux between reaction and bulk layers,and composition updates in reaction and bulk layers.The accuracy of the model was validated by plant trial data.The effect of casting parameters and initial compositions on the evolution of mold flux composition were investigated.The TiO_(2)accumulation and SiO_(2)consumption in mold flux under varying casting parameters was predicted.It was found that higher casting speeds accelerated compositional equilibrium,while the increase of mold flux consumption rates reduced TiO_(2)accumulation.The increase of pool depth resulted in slower consumption and accumulation rates of components like SiO_(2)and TiO_(2),prolonging the time to reach equilibrium.Additionally,the CaO-Al_(2)O_(3)-based flux suppressed the Ti-SiO_(2)reaction for the high-titanium steel continuous casting.However,the CaO-Al_(2)O_(3)-based flux should limited contents of Na_(2)O,MnO,and FeO to prevent additional TiO_(2)accumulation due to Ti-Na_(2)O,Ti-MnO,and Ti-FeO reactions.The model provided a reliable tool for understanding and optimizing the continuous casting process of high-titanium steels.展开更多
Hydrocracking is one of the most important petroleum refining processes that converts heavy oils into gases,naphtha,diesel,and other products through cracking reactions.Multi-objective optimization algorithms can help...Hydrocracking is one of the most important petroleum refining processes that converts heavy oils into gases,naphtha,diesel,and other products through cracking reactions.Multi-objective optimization algorithms can help refining enterprises determine the optimal operating parameters to maximize product quality while ensuring product yield,or to increase product yield while reducing energy consumption.This paper presents a multi-objective optimization scheme for hydrocracking based on an improved SPEA2-PE algorithm,which combines path evolution operator and adaptive step strategy to accelerate the convergence speed and improve the computational accuracy of the algorithm.The reactor model used in this article is simulated based on a twenty-five lumped kinetic model.Through model and test function verification,the proposed optimization scheme exhibits significant advantages in the multiobjective optimization process of hydrocracking.展开更多
The continuous growth behavior of austenite grain in 20Cr peritectic steel was analyzed by experiment and theoretical modeling.The peculiar casting experiment with different cooling rates was achieved by multigradient...The continuous growth behavior of austenite grain in 20Cr peritectic steel was analyzed by experiment and theoretical modeling.The peculiar casting experiment with different cooling rates was achieved by multigradient operation scheme,and different morphologies in austenite grain were observed at the target location.The increase in austenite grain size with increasing cooling rate was firstly revealed in steels.The anomalous grain growth theoretically results from the mechanism of peritectic transformation transiting from the diffusional to massive type,and the additional energy storage stimulates the grain boundary migration.A new kinetic model to predict the growth behavior of austenite grain during continuous cooling process was developed,and the energy storage induced by massive type peritectic transformation was novelly taken into account.The parameters in the model were fitted by multiphase field modeling and experimental results.The kinetic model was finally verified by austenite grain size in laboratory test as well as the trial data at different locations in continuously cast bloom.The coarsening behavior of austenite grain during continuous casting was predicted based on the simulated temperature history.It is found that the grain coarsening occurs generally in the mold zone at high temperature for 20Cr steel and then almost levels off in the following process.The austenite finish transformation temperature Tγand primary cooling intensity show great influence on the grain coarsening.As Tγdecreases by 1℃,the austenite grain size decreases by 4μm linearly.However,the variation of Tγagainst heat flux is in a nonlinear relationship,suggesting that low cooling rate is much more harmful for austenite grain coarsening in continuous casting.展开更多
1.Colors of chemical reaction engineering models Kinetic models of chemical reactions are a crucial asset for understanding and optimizing chemical processes[1].These models are critical for reactor design,process opt...1.Colors of chemical reaction engineering models Kinetic models of chemical reactions are a crucial asset for understanding and optimizing chemical processes[1].These models are critical for reactor design,process optimization,catalyst design,scale-up,and process control,making them indispensable in the chemical industry.Kinetic models predict the change in temperature and concentration of the relevant species,given an actual concentration and temperature.Reaction predictions are made by integrating the kinetic model with a reactor model,which accounts for external constraints,such as flow,inlet concentration。展开更多
The cold-rolled quenching and partitioning(Q&P)steel with an initial microstructure of deformed ferrite and pearlite was studied.The microstructural evolution under various heating rates of 1.78,50,and 300℃/s was...The cold-rolled quenching and partitioning(Q&P)steel with an initial microstructure of deformed ferrite and pearlite was studied.The microstructural evolution under various heating rates of 1.78,50,and 300℃/s was investigated using microstructural characterization and theoretical modeling.At the same time,the characteristics of recrystallization and austenite formation kinetics were decoupled by examining recrystallized ferrite and deformed ferrite as initial conditions.The findings revealed that the austenite formation during continuous heating can be simplified into two stages:(i)the early nucleation-dominated formation stage and(ii)the later grain growth-dominated stage,resulting in the development of a modified two-stage model based on Johnson-Mehl-Avrami-Kolmogorov.Further experiments confirmed that when the austenite volume fraction exceeded approximately 5% at a heating rate of 1.78℃/s,ferrite recrystallization was suppressed.In consequence,a mixed model including recrystallization kinetics was employed to couple the austenite formation occurring in deformed ferrite and recrystallized ferrite,thereby describing the austenite formation kinetics affected by recrystallization.Precise predictions of non-isothermal austenite formation kinetics in cold-rolled Q&P steel were achieved during slow and ultrafast heating processes by integrating the suppression effect into the model for austenite formation.展开更多
Industrial ebullated-bed is an important device for promoting the cleaning and upgrading of oil products. The lumped kinetic model is a powerful tool for predicting the product yield of the ebullated-bed residue hydro...Industrial ebullated-bed is an important device for promoting the cleaning and upgrading of oil products. The lumped kinetic model is a powerful tool for predicting the product yield of the ebullated-bed residue hydrogenation (EBRH) unit, However, during the long-term operation of the device, there are phenomena such as low frequency of material property analysis leading to limited operating data and diverse operating modes at the same time scale, which poses a huge challenge to building an accurate product yield prediction model. To address these challenges, a data augmentation-based eleven lumped reaction kinetics mechanism model was constructed. This model combines generative adversarial networks, outlier elimination, and L2 norm data filtering to expand the dataset and utilizes kernel principal component analysis-fuzzy C-means for operating condition partitioning. Based on the hydrogenation reaction mechanism, a single and sub operating condition eleven lumped reaction kinetics model of an ebullated-bed residue hydrogenation unit, comprising 55 reaction paths and 110 parameters, was constructed before and after data augmentation. Compared to the single model before data enhancement, the average absolute error of the sub-models under data enhancement division was reduced by 23%. Thus, these findings can help guide the operation and optimization of the production process.展开更多
A kinetic moment-closed model(KMCM), derived from the Vlasov–Fokker–Planck(VFP) equation with spherically symmetric velocity space, is introduced as a general relaxation model for homogeneous plasmas. The closed for...A kinetic moment-closed model(KMCM), derived from the Vlasov–Fokker–Planck(VFP) equation with spherically symmetric velocity space, is introduced as a general relaxation model for homogeneous plasmas. The closed form of this model is presented by introducing a set of new functions called R function and R integration. This nonlinear model, based on the finitely distinguishable independent features(FDIF) hypothesis, enables the capture of the nature of the equilibrium state and non-equilibrium state. From this relaxation model, a general temperature relaxation model is derived when the velocity space exhibits spherical symmetry, and the general characteristic frequency of temperature relaxation is presented.展开更多
Pyrolysis of benzene at 30 Torr was studied from 1360 K to 1820 K in this work. Synchrotron vacuum ultraviolet photoionization mass spectrometry was employed to detect the pyroly- sis products such as radicals, isomer...Pyrolysis of benzene at 30 Torr was studied from 1360 K to 1820 K in this work. Synchrotron vacuum ultraviolet photoionization mass spectrometry was employed to detect the pyroly- sis products such as radicals, isomers and polycyclic aromatic hydrocarbons, and measure their mole fraction profiles versus temperature. A low-pressure pyrolysis model of benzene was developed and validated by the experimental results. Rate of production analysis was performed to reveal the major reaction networks in both fuel decomposition and aromatic growth processes. It is concluded that benzene is mainly decomposed via H-abstraction reaction to produce phenyl and partly decomposed via unimolecular decomposition reac- tions to produce propargyl or phenyl. The decomposition process stops at the formation of acetylene and polyyne species like diacetylene and 1,3,5-hexatriyne due to their high thermal stabilities. Besides, the aromatic growth process in the low-pressure pyrolysis of benzene is concluded to initiate from benzene and phenyl, and is controlled by the even carbon growth mechanism due to the inhibited formation of C5 and C7 species which play important roles in the odd carbon growth mechanism.展开更多
The static recrystallization behavior of low-alloy steel Q345B during double-pass hot compression deformation tests was investigated in the temperature range of 900-1000 ℃,the true strain range of 0.15-0.25 and the i...The static recrystallization behavior of low-alloy steel Q345B during double-pass hot compression deformation tests was investigated in the temperature range of 900-1000 ℃,the true strain range of 0.15-0.25 and the interpass time range of 0.5-50 s on Gleeble-3500 thermo-simulation machine.The results show that static recrystallization during the interpass time is observed.As the deformation temperature and strain increase,softening caused by static recrystallization is obvious.According to the analysis and calculation of thermo-simulation data,the static recrystallization activation energy was obtained and static recrystallization kinetics model was built.Finally,the error analysis of static recrystallization kinetics model proved that the model had good accuracy.Therefore,this model provides a theoretical basis for static recrystallization（SRX）and will contribute to the development of multipass hot rolling process,in order to control the rolling process more accurately.展开更多
A new 18-lump kinetic model for naphtha catalytic reforming reactions is discussed. By developing this model as a user module, a whole industrial continuous catalytic reforming process is simulated on Aspen plus plat-...A new 18-lump kinetic model for naphtha catalytic reforming reactions is discussed. By developing this model as a user module, a whole industrial continuous catalytic reforming process is simulated on Aspen plus plat-form. The technique utilizes the strong databases, complete sets of modules, and flexible simulation tools of the Aspen plus system and retains the characteristics of the proposed kinetic model. The calculated results are in fair agreement with the actual operating data. Based on the model of the whole reforming process, the process is opti-mized and the optimization results are tested in the actual industrial unit for about two months. The test shows that the process profit increases about 1000yuan·h-1 averagely, which is close to the calculated result.展开更多
This work presents a study for chemical leaching of sphalerite concentrate under various constant Fe3+ concentrations and redox potential conditions. The effects of Fe3+ concentration and redox potential on chemical l...This work presents a study for chemical leaching of sphalerite concentrate under various constant Fe3+ concentrations and redox potential conditions. The effects of Fe3+ concentration and redox potential on chemical leaching of sphalerite were investigated. The shrinking core model was applied to analyze the experimental results. It was found that both the Fe3+ concentration and the redox potential controlled the chemical leaching rate of sphalerite. A new kinetic model was developed, in which the chemical leaching rate of sphalerite was proportional to Fe3+ concentration and Fe3+ /Fe2+ ratio. All the model parameters were evaluated from the experimental data. The model predictions fit well with the experimental observed values.展开更多
A three phase fluidized bed reactor was used to investigate the combined effect of adsorption and oxidation for phenolic wastewater treatment.Aqueous solutions containing 10 mg·L 1of phenol and ozone were continu...A three phase fluidized bed reactor was used to investigate the combined effect of adsorption and oxidation for phenolic wastewater treatment.Aqueous solutions containing 10 mg·L 1of phenol and ozone were continuously fed co-currently as upward flow into the reactor at constant flow rate of 2 and 1 L·min 1,respectively.The phenolic treatment results in seven cases were compared：（a）O3 only,（b）fresh granular activated carbon（GAC）,（c） 1st reused GAC,（d）2nd reused GAC,（e）fresh GAC enhanced with O3,（f）1st reused GAC enhanced with O3,and （g）2nd reused GAC enhanced with O3.The phenolic wastewater was re-circulated through the reactor and its concentration was measured with respect to time.The experimental results revealed that the phenolic degradation using GAC enhanced with O3 provided the best result.The effect of adsorption by activated carbon was stronger than the effect of oxidation by ozone.Fresh GAC could adsorb phenol better than reused GAC.All cases of adsorption on GAC followed the Langmuir isotherm and displayed pseudo second order adsorption kinetics.Finally,a differential equation for the fluidized bed reactor model was used to describe the phenol concentration with respect to time for GAC enhanced with O3.The calculated results agree reasonably well with the experimental results.展开更多
This study was performed in two phases of work.In the first stage,four conventional first-order flotation kinetics models were fitted to the measured recoveries data and the best model were selected.In the second stag...This study was performed in two phases of work.In the first stage,four conventional first-order flotation kinetics models were fitted to the measured recoveries data and the best model were selected.In the second stage,influence of pH,solid concentration,water chemistry and the amount of collector dosage were investigated on kinetics parameters including flotation rate constant and ultimate recovery.The results indicated that that perfectly mixed reactor model and Kelsall model gave the best and the weakest fit to the experimental data,respectively.It was observed that flotation rate constant and ultimate recovery were strongly affected by chemical factors investigated especially water quality.The flotation rate constant decreased with increasing the solids content,while ultimate recovery increased to certain value and thereafter reduced.It was also found that the most values of flotation rate constant and ultimate recovery obtained in dosage of collector are 30 and 40 g/t,respectively.展开更多
This article investigates the dynamic characteristics of deflectable nose missiles with rotary single-channel control. After introduction of effective attack and sideslip angles as well as quasi-body coordinates based...This article investigates the dynamic characteristics of deflectable nose missiles with rotary single-channel control. After introduction of effective attack and sideslip angles as well as quasi-body coordinates based on the spin characteristics of the missile＇s body, an integrated rigid kinetic model of missile with deflectable nose control is set up in the quasi-body coordinates considering the interaction between the missile＇s nose and body by using rootless multi-rigid-body system dynamics and is linearized. Then an analysis with simulation is conducted to investigate the coupling characteristics between the channels, the influences of nose deflection on the body and the dynamic characteristics of missile＇s body. The results indicate that various channels of missiles with deflectable nose control are coupled cross-linked; the nose deflection tends to make the body move in the opposite direction and, finally, evidences the correctness and reasonability of the kinetic model proposed by this article.展开更多
This study investigated the isothermal gasification reactivity of biomass char （BC） and coal char （CC） blended at mass ratios of 1：3, 1：1, and 3：1 via isothermal thermogravimelric analysis （TGA） at 900, 950, ...This study investigated the isothermal gasification reactivity of biomass char （BC） and coal char （CC） blended at mass ratios of 1：3, 1：1, and 3：1 via isothermal thermogravimelric analysis （TGA） at 900, 950, and 1000℃ under CO2. With an increase in BC blending ra- tio, there were an increase in gasification rate and a shortening of gasification time. This could be attributed to the high specific surface area of BC and the high uniformity of carbon structures in CC when compared to those in BC. Three representative gas-solid kinetic models, namely, the volumetric model （VM）, grain model （GM）, and random pore model （RPM）, were applied to describe the reaction behavior of the char. Among them, the RPM model was considered the best model to describe the reactivity of the char gasification reaction. The activa- tion energy of BC and CC isothermal gasification as determined using the RPM model was found to be 126.7 kJ/mol and 210.2 kJ/mol, re- spectively. The activation energy was minimum （123.1 kJ/mol） for the BC blending ratio of 75%. Synergistic effect manifested at all mass ratios of the blended char, which increased with the gasification temperature.展开更多
An experimental study of thermal DeNOx process with different additives was performed in an electricityheated tubular flow reactor,showing that CO is less effective to lower the optimum temperature than H2 and CH4. Th...An experimental study of thermal DeNOx process with different additives was performed in an electricityheated tubular flow reactor,showing that CO is less effective to lower the optimum temperature than H2 and CH4. The maximum NO reduction is lowered with H2 added,while it is hardly affected by CO or CH4.The temperature window is widened appreciably with CH4 added,while it is narrowed slightly by H2 or CO.The disadvantage of CH4 is that it causes CO emission due to its incomplete oxidation,and the maximum conversion of CH4 to CO is more than 50%.In general,the calculation using a detailed chemical kinetic model predicts most of the process features reasonably well.The analysis on reaction mechanism shows that the effects of these additives on NO reduction are achieved principally by promoting the production of·OH radical.展开更多
To improve the understanding of coupling effect between dynamic recrystallization(DRX)behaviors and flow behaviors of as-cast AlCu4 SiMg, a finite element(FE) simulation equipped with the models of DRX evolution was i...To improve the understanding of coupling effect between dynamic recrystallization(DRX)behaviors and flow behaviors of as-cast AlCu4 SiMg, a finite element(FE) simulation equipped with the models of DRX evolution was implemented. A series of isothermal compression tests were performed primarily on a Gleeble-3500 thermo-mechanical simulator in a temperature range of 648-748 K and a strain rate range of 0.01-10 s-1.According to the measured true stress-strain data,the strain hardening rate curves(dσ/dε versus σ) were plotted to identify the critical strains for DRX initiation(εc). By further derivation of the related material constants, the DRX volume fraction equation and the strain for 50% DRX(ε0.5) equation were solved. Accordingly, the aforementioned DRX equations were implanted into the FE model to conduct a series of simulations for the isothermal compression tests. The results show that during the evolution of DRX volume fraction at a fixed strain rate, the strain required for the same amount of DRX volume fraction increases with decreasing temperature. In contrast, at a fixed temperature, it increases with increasing strain rate. Ultimately, the DRX kinetics model of AlCu4 SiMg alloy and the consequence of the FE analysis were validated by microstructure observations.展开更多
A semi-empirical adsorption kinetic model was proposed with the time compensation method to describe the chemisorption of SO2 in flue gas by carbon adsorbents for flue gas purification.The change in adsorption capacit...A semi-empirical adsorption kinetic model was proposed with the time compensation method to describe the chemisorption of SO2 in flue gas by carbon adsorbents for flue gas purification.The change in adsorption capacity and adsorption rate with time at different water vapor concentrations and different SO2 concentrations was studied.The model was in good agreement with experimental data.The surface reaction was probably the rate controlling step in the early stage for SO2 adsorption by ZL50 activated carbon.The parameters m and n in the nth order adsorption kinetic model were related to the magnitude of the time compensation and adsorption driving force,respectively.The change of parameter n with water vapor concentrations and sulfur dioxide concentrations was studied and some physical implications were given.The sum of square errors was less than 1.0 and the average absolute percentage deviations ranged from 0.5 to 3.2.The kinetic model was compared with other models in the literature.展开更多
基金supported by the grants PID2020-113371RA-C22 and TED2021-130845A-C32,funded by MCIN/AEI/10.13039/501100011033.M.Marín-García,R.González-OlmosC.Gómez-Canela are members of the GESPA group(Grup d’Enginyeria i Simulacióde Processos Ambientals)at IQS-URL,which has been acknowledged as a Consolidated Research Group by the Government of Catalonia(No.2021-SGR-00321)+1 种基金In addition,M.Marín-García has been awarded a public grant for the Investigo Programme,aimed at hiring young job seekers to undertake research and innovation projects under the Recovery,Transformation,and Resilience Plan(PRTR),European Union Next Generation,for the year 2022,through the Government of Catalonia and the Spanish Ministry for Work and Social Economy(No.100045ID16)Ana Belén Cuenca for her support and expertise,which helped to confirm the proposed reaction mechanism involved in the UV photolysis of cloperastine.
文摘The increasing production and release of synthetic organic chemicals,including pharmaceuticals,into our envi-ronment has allowed these substances to accumulate in our surface water systems.Current purification technolo-gies have been unable to eliminate these pollutants,resulting in their ongoing release into aquatic ecosystems.This study focuses on cloperastine(CPS),a cough suppressant and antihistamine medication.The environmental impact of CPS usage has become a concern,mainly due to its increased detection during the COVID-19 pandemic.CPS has been found in wastewater treatment facilities,effluents from senior living residences,river waters,and sewage sludge.However,the photosensitivity of CPS and its photodegradation profile remain largely unknown.This study investigates the photodegradation process of CPS under simulated tertiary treatment conditions using UV photolysis,a method commonly applied in some wastewater treatment plants.Several transformation prod-ucts were identified,evaluating their kinetic profiles using chemometric approaches(i.e.,curve fitting and the hard-soft multivariate curve resolution-alternating least squares(HS-MCR-ALS)algorithm)and calculating the reaction quantum yield.As a result,three different transformation products have been detected and correctly identified.In addition,a comprehensive description of the kinetic pathway involved in the photodegradation process of the CPS drug has been provided,including observed kinetic rate constants.
文摘Hydrocarbon generation kinetics are influenced by complex factors,including temperature,reaction time,pressure,and molecular structure,which render simple modeling approaches inadequate for accurately simulating methane generation.The closed-system pyrolysis experiment,a common method to study hydrocarbon generation,poses challenges for kinetic parameter regression due to limited data points.This limitation necessitates the application of sophisticated data analysis techniques to extract meaningful insights from sparse experimental data.This paper establishes a quantitative relationship between methane production and the thermal process through closed system pyrolysis experiments.A nonlinear regression model using multiple algorithms is established based on this quantitative relationship.Accordingly,a method that can quantitatively invert the methane generation kinetic parameters corresponding to the samples based on the experimental data is provided.Based on this theoretical model,a computer program capable of processing experimental data is designed and implemented.Practical analyses are performed using the method above for three samples:a coal sample from the Yulong,Guizhou;a solid bitumen sample from Guangyuan,Sichuan;and a marlstone sample containing type Ⅰ kerogen from Luquan,Yunnan.The results obtained agree with the qualitative estimates based on hydrocarbon generation kinetic theory using the previous method.Thus,the validity of the new data processing method,the new mathematical model,and the data processing procedures are verified.
基金support from the National Key R&D Program(Grant No.2023YFB3709900)the National Natural Science Foundation of China(Grant No.U22A20171)+1 种基金China Baowu Low Carbon Metallurgy Innovation Foundation(Grant No.BWLCF202315)the High Steel Center(HSC)at North China University of Technology and University of Science and Technology Beijing,China.
文摘Continuous casting of high-titanium steels face significant challenges due to steel-flux reactions,which will cause rapid compositional deviations and impair operational stability.A kinetic model to predict real-time mold flux composition evolution by integrating multicomponent mixed-transport-control theory with thermodynamics computing platform was developed in the current study.The model employed a cyclic time-step algorithm to compute thermodynamic equilibrium in reaction layer,mass transfer flux between reaction and bulk layers,and composition updates in reaction and bulk layers.The accuracy of the model was validated by plant trial data.The effect of casting parameters and initial compositions on the evolution of mold flux composition were investigated.The TiO_(2)accumulation and SiO_(2)consumption in mold flux under varying casting parameters was predicted.It was found that higher casting speeds accelerated compositional equilibrium,while the increase of mold flux consumption rates reduced TiO_(2)accumulation.The increase of pool depth resulted in slower consumption and accumulation rates of components like SiO_(2)and TiO_(2),prolonging the time to reach equilibrium.Additionally,the CaO-Al_(2)O_(3)-based flux suppressed the Ti-SiO_(2)reaction for the high-titanium steel continuous casting.However,the CaO-Al_(2)O_(3)-based flux should limited contents of Na_(2)O,MnO,and FeO to prevent additional TiO_(2)accumulation due to Ti-Na_(2)O,Ti-MnO,and Ti-FeO reactions.The model provided a reliable tool for understanding and optimizing the continuous casting process of high-titanium steels.
基金supported by National Key Research and Development Program of China (2023YFB3307800)National Natural Science Foundation of China (Key Program: 62136003, 62373155)+1 种基金Major Science and Technology Project of Xinjiang (No. 2022A01006-4)the Fundamental Research Funds for the Central Universities。
文摘Hydrocracking is one of the most important petroleum refining processes that converts heavy oils into gases,naphtha,diesel,and other products through cracking reactions.Multi-objective optimization algorithms can help refining enterprises determine the optimal operating parameters to maximize product quality while ensuring product yield,or to increase product yield while reducing energy consumption.This paper presents a multi-objective optimization scheme for hydrocracking based on an improved SPEA2-PE algorithm,which combines path evolution operator and adaptive step strategy to accelerate the convergence speed and improve the computational accuracy of the algorithm.The reactor model used in this article is simulated based on a twenty-five lumped kinetic model.Through model and test function verification,the proposed optimization scheme exhibits significant advantages in the multiobjective optimization process of hydrocracking.
基金supported by the Fundamental Research Funds for the Central Universities(No.FRF-TP-19-017A3)National Natural Science Foundation of China(No.51874026).
文摘The continuous growth behavior of austenite grain in 20Cr peritectic steel was analyzed by experiment and theoretical modeling.The peculiar casting experiment with different cooling rates was achieved by multigradient operation scheme,and different morphologies in austenite grain were observed at the target location.The increase in austenite grain size with increasing cooling rate was firstly revealed in steels.The anomalous grain growth theoretically results from the mechanism of peritectic transformation transiting from the diffusional to massive type,and the additional energy storage stimulates the grain boundary migration.A new kinetic model to predict the growth behavior of austenite grain during continuous cooling process was developed,and the energy storage induced by massive type peritectic transformation was novelly taken into account.The parameters in the model were fitted by multiphase field modeling and experimental results.The kinetic model was finally verified by austenite grain size in laboratory test as well as the trial data at different locations in continuously cast bloom.The coarsening behavior of austenite grain during continuous casting was predicted based on the simulated temperature history.It is found that the grain coarsening occurs generally in the mold zone at high temperature for 20Cr steel and then almost levels off in the following process.The austenite finish transformation temperature Tγand primary cooling intensity show great influence on the grain coarsening.As Tγdecreases by 1℃,the austenite grain size decreases by 4μm linearly.However,the variation of Tγagainst heat flux is in a nonlinear relationship,suggesting that low cooling rate is much more harmful for austenite grain coarsening in continuous casting.
基金Yannick Ureel and Maarten Dobbelaere acknowledge financial support from the Fund for Scientific Research Flanders(FWO Flanders)respectively through doctoral fellowship grants(1185822N and 1S45522N)The authors acknowledge funding from the European Research Council under the European Union’s Horizon 2020 research and innovation programme/ERC(818607).
文摘1.Colors of chemical reaction engineering models Kinetic models of chemical reactions are a crucial asset for understanding and optimizing chemical processes[1].These models are critical for reactor design,process optimization,catalyst design,scale-up,and process control,making them indispensable in the chemical industry.Kinetic models predict the change in temperature and concentration of the relevant species,given an actual concentration and temperature.Reaction predictions are made by integrating the kinetic model with a reactor model,which accounts for external constraints,such as flow,inlet concentration。
基金funded by the National Key R&D Program of China(No.2021YFB3702404)the National Natural Science Foundation of China(Nos.52201101 and 52274372)+1 种基金the Major Program Funding of Cisri(No.21T62450ZD)the Fundamental Research Funds for the Central Universities(Nos.FRF-TP-22-013A1 and FRF-TP-22-015A1).
文摘The cold-rolled quenching and partitioning(Q&P)steel with an initial microstructure of deformed ferrite and pearlite was studied.The microstructural evolution under various heating rates of 1.78,50,and 300℃/s was investigated using microstructural characterization and theoretical modeling.At the same time,the characteristics of recrystallization and austenite formation kinetics were decoupled by examining recrystallized ferrite and deformed ferrite as initial conditions.The findings revealed that the austenite formation during continuous heating can be simplified into two stages:(i)the early nucleation-dominated formation stage and(ii)the later grain growth-dominated stage,resulting in the development of a modified two-stage model based on Johnson-Mehl-Avrami-Kolmogorov.Further experiments confirmed that when the austenite volume fraction exceeded approximately 5% at a heating rate of 1.78℃/s,ferrite recrystallization was suppressed.In consequence,a mixed model including recrystallization kinetics was employed to couple the austenite formation occurring in deformed ferrite and recrystallized ferrite,thereby describing the austenite formation kinetics affected by recrystallization.Precise predictions of non-isothermal austenite formation kinetics in cold-rolled Q&P steel were achieved during slow and ultrafast heating processes by integrating the suppression effect into the model for austenite formation.
基金supported by National Natural Science Foundation of China(Basic Science Center Program:61988101)National Natural Science Foundation of China(62394345,62373155,62173147)the Major Science and Technology Project of Xinjiang(No.2022A01006-4).
文摘Industrial ebullated-bed is an important device for promoting the cleaning and upgrading of oil products. The lumped kinetic model is a powerful tool for predicting the product yield of the ebullated-bed residue hydrogenation (EBRH) unit, However, during the long-term operation of the device, there are phenomena such as low frequency of material property analysis leading to limited operating data and diverse operating modes at the same time scale, which poses a huge challenge to building an accurate product yield prediction model. To address these challenges, a data augmentation-based eleven lumped reaction kinetics mechanism model was constructed. This model combines generative adversarial networks, outlier elimination, and L2 norm data filtering to expand the dataset and utilizes kernel principal component analysis-fuzzy C-means for operating condition partitioning. Based on the hydrogenation reaction mechanism, a single and sub operating condition eleven lumped reaction kinetics model of an ebullated-bed residue hydrogenation unit, comprising 55 reaction paths and 110 parameters, was constructed before and after data augmentation. Compared to the single model before data enhancement, the average absolute error of the sub-models under data enhancement division was reduced by 23%. Thus, these findings can help guide the operation and optimization of the production process.
基金supported by the Shuangchuang Ph.D Award (from World Prestigious Universities) (Grant No. JSSCBS20211303)Lianyungang Postdoctoral Science Foundation (Grant No. LYG20220014)the National Natural Science Foundation of China (Grant No.120051410)。
文摘A kinetic moment-closed model(KMCM), derived from the Vlasov–Fokker–Planck(VFP) equation with spherically symmetric velocity space, is introduced as a general relaxation model for homogeneous plasmas. The closed form of this model is presented by introducing a set of new functions called R function and R integration. This nonlinear model, based on the finitely distinguishable independent features(FDIF) hypothesis, enables the capture of the nature of the equilibrium state and non-equilibrium state. From this relaxation model, a general temperature relaxation model is derived when the velocity space exhibits spherical symmetry, and the general characteristic frequency of temperature relaxation is presented.
基金This work is supported by the National Natu- ral Science Foundation of China （No.51106146 and No.51036007）, China Postdoctoral Science Foundation （No.20100480047 and No.201104326）, Chinese Univer- sities Scientific Fund （No.WK2310000010）, and Chinese Academy of Sciences.
文摘Pyrolysis of benzene at 30 Torr was studied from 1360 K to 1820 K in this work. Synchrotron vacuum ultraviolet photoionization mass spectrometry was employed to detect the pyroly- sis products such as radicals, isomers and polycyclic aromatic hydrocarbons, and measure their mole fraction profiles versus temperature. A low-pressure pyrolysis model of benzene was developed and validated by the experimental results. Rate of production analysis was performed to reveal the major reaction networks in both fuel decomposition and aromatic growth processes. It is concluded that benzene is mainly decomposed via H-abstraction reaction to produce phenyl and partly decomposed via unimolecular decomposition reac- tions to produce propargyl or phenyl. The decomposition process stops at the formation of acetylene and polyyne species like diacetylene and 1,3,5-hexatriyne due to their high thermal stabilities. Besides, the aromatic growth process in the low-pressure pyrolysis of benzene is concluded to initiate from benzene and phenyl, and is controlled by the even carbon growth mechanism due to the inhibited formation of C5 and C7 species which play important roles in the odd carbon growth mechanism.
基金Item Sponsored by Fok Ying Tung Education Foundation(101048)Natural Science Foundation of Hebei Province of China(E2008000835)
文摘The static recrystallization behavior of low-alloy steel Q345B during double-pass hot compression deformation tests was investigated in the temperature range of 900-1000 ℃,the true strain range of 0.15-0.25 and the interpass time range of 0.5-50 s on Gleeble-3500 thermo-simulation machine.The results show that static recrystallization during the interpass time is observed.As the deformation temperature and strain increase,softening caused by static recrystallization is obvious.According to the analysis and calculation of thermo-simulation data,the static recrystallization activation energy was obtained and static recrystallization kinetics model was built.Finally,the error analysis of static recrystallization kinetics model proved that the model had good accuracy.Therefore,this model provides a theoretical basis for static recrystallization（SRX）and will contribute to the development of multipass hot rolling process,in order to control the rolling process more accurately.
基金Supported by the National Natural Science Foundation of China (No.60421002).
文摘A new 18-lump kinetic model for naphtha catalytic reforming reactions is discussed. By developing this model as a user module, a whole industrial continuous catalytic reforming process is simulated on Aspen plus plat-form. The technique utilizes the strong databases, complete sets of modules, and flexible simulation tools of the Aspen plus system and retains the characteristics of the proposed kinetic model. The calculated results are in fair agreement with the actual operating data. Based on the model of the whole reforming process, the process is opti-mized and the optimization results are tested in the actual industrial unit for about two months. The test shows that the process profit increases about 1000yuan·h-1 averagely, which is close to the calculated result.
基金Supported by the National Basic Research Program （2010CB630902, 2004CB619202） the National Natural Science Foundation of China （31070034, 30800011, 31260396）+1 种基金 the Knowledge Innovation Program of CAS （2AKSCX2-YW-JS401） the Reward Fund for Young Scientists of Shandong Province （2007BS08002） of China
文摘This work presents a study for chemical leaching of sphalerite concentrate under various constant Fe3+ concentrations and redox potential conditions. The effects of Fe3+ concentration and redox potential on chemical leaching of sphalerite were investigated. The shrinking core model was applied to analyze the experimental results. It was found that both the Fe3+ concentration and the redox potential controlled the chemical leaching rate of sphalerite. A new kinetic model was developed, in which the chemical leaching rate of sphalerite was proportional to Fe3+ concentration and Fe3+ /Fe2+ ratio. All the model parameters were evaluated from the experimental data. The model predictions fit well with the experimental observed values.
基金Supported by the National Nanotechnology Center(NANOTEC)(601003)the National Science and Technology Development Agency(NSTDA)
文摘A three phase fluidized bed reactor was used to investigate the combined effect of adsorption and oxidation for phenolic wastewater treatment.Aqueous solutions containing 10 mg·L 1of phenol and ozone were continuously fed co-currently as upward flow into the reactor at constant flow rate of 2 and 1 L·min 1,respectively.The phenolic treatment results in seven cases were compared：（a）O3 only,（b）fresh granular activated carbon（GAC）,（c） 1st reused GAC,（d）2nd reused GAC,（e）fresh GAC enhanced with O3,（f）1st reused GAC enhanced with O3,and （g）2nd reused GAC enhanced with O3.The phenolic wastewater was re-circulated through the reactor and its concentration was measured with respect to time.The experimental results revealed that the phenolic degradation using GAC enhanced with O3 provided the best result.The effect of adsorption by activated carbon was stronger than the effect of oxidation by ozone.Fresh GAC could adsorb phenol better than reused GAC.All cases of adsorption on GAC followed the Langmuir isotherm and displayed pseudo second order adsorption kinetics.Finally,a differential equation for the fluidized bed reactor model was used to describe the phenol concentration with respect to time for GAC enhanced with O3.The calculated results agree reasonably well with the experimental results.
文摘This study was performed in two phases of work.In the first stage,four conventional first-order flotation kinetics models were fitted to the measured recoveries data and the best model were selected.In the second stage,influence of pH,solid concentration,water chemistry and the amount of collector dosage were investigated on kinetics parameters including flotation rate constant and ultimate recovery.The results indicated that that perfectly mixed reactor model and Kelsall model gave the best and the weakest fit to the experimental data,respectively.It was observed that flotation rate constant and ultimate recovery were strongly affected by chemical factors investigated especially water quality.The flotation rate constant decreased with increasing the solids content,while ultimate recovery increased to certain value and thereafter reduced.It was also found that the most values of flotation rate constant and ultimate recovery obtained in dosage of collector are 30 and 40 g/t,respectively.
基金Weapons Preliminary Research Key Foundation of China (9140A01010106HK0307)
文摘This article investigates the dynamic characteristics of deflectable nose missiles with rotary single-channel control. After introduction of effective attack and sideslip angles as well as quasi-body coordinates based on the spin characteristics of the missile＇s body, an integrated rigid kinetic model of missile with deflectable nose control is set up in the quasi-body coordinates considering the interaction between the missile＇s nose and body by using rootless multi-rigid-body system dynamics and is linearized. Then an analysis with simulation is conducted to investigate the coupling characteristics between the channels, the influences of nose deflection on the body and the dynamic characteristics of missile＇s body. The results indicate that various channels of missiles with deflectable nose control are coupled cross-linked; the nose deflection tends to make the body move in the opposite direction and, finally, evidences the correctness and reasonability of the kinetic model proposed by this article.
基金financially supported by the National Natural Science Foundation of China (No. 51104014)
文摘This study investigated the isothermal gasification reactivity of biomass char （BC） and coal char （CC） blended at mass ratios of 1：3, 1：1, and 3：1 via isothermal thermogravimelric analysis （TGA） at 900, 950, and 1000℃ under CO2. With an increase in BC blending ra- tio, there were an increase in gasification rate and a shortening of gasification time. This could be attributed to the high specific surface area of BC and the high uniformity of carbon structures in CC when compared to those in BC. Three representative gas-solid kinetic models, namely, the volumetric model （VM）, grain model （GM）, and random pore model （RPM）, were applied to describe the reaction behavior of the char. Among them, the RPM model was considered the best model to describe the reactivity of the char gasification reaction. The activa- tion energy of BC and CC isothermal gasification as determined using the RPM model was found to be 126.7 kJ/mol and 210.2 kJ/mol, re- spectively. The activation energy was minimum （123.1 kJ/mol） for the BC blending ratio of 75%. Synergistic effect manifested at all mass ratios of the blended char, which increased with the gasification temperature.
基金Supported by the State Key Development Program for Basic Research of China（2006CB200303） the National Natural Science Foundation of China （50706011） the National High Technology Research and Development Program of China（2007AA05Z337）
文摘An experimental study of thermal DeNOx process with different additives was performed in an electricityheated tubular flow reactor,showing that CO is less effective to lower the optimum temperature than H2 and CH4. The maximum NO reduction is lowered with H2 added,while it is hardly affected by CO or CH4.The temperature window is widened appreciably with CH4 added,while it is narrowed slightly by H2 or CO.The disadvantage of CH4 is that it causes CO emission due to its incomplete oxidation,and the maximum conversion of CH4 to CO is more than 50%.In general,the calculation using a detailed chemical kinetic model predicts most of the process features reasonably well.The analysis on reaction mechanism shows that the effects of these additives on NO reduction are achieved principally by promoting the production of·OH radical.
基金Project(cstc2016jcyjA0335)supported by Chongqing Foundation and Frontier Research,ChinaProject(P2017-020)supported by Open Fund Project of State Key Laboratory of Materials Processing and Die&Mould Technology,China
文摘To improve the understanding of coupling effect between dynamic recrystallization(DRX)behaviors and flow behaviors of as-cast AlCu4 SiMg, a finite element(FE) simulation equipped with the models of DRX evolution was implemented. A series of isothermal compression tests were performed primarily on a Gleeble-3500 thermo-mechanical simulator in a temperature range of 648-748 K and a strain rate range of 0.01-10 s-1.According to the measured true stress-strain data,the strain hardening rate curves(dσ/dε versus σ) were plotted to identify the critical strains for DRX initiation(εc). By further derivation of the related material constants, the DRX volume fraction equation and the strain for 50% DRX(ε0.5) equation were solved. Accordingly, the aforementioned DRX equations were implanted into the FE model to conduct a series of simulations for the isothermal compression tests. The results show that during the evolution of DRX volume fraction at a fixed strain rate, the strain required for the same amount of DRX volume fraction increases with decreasing temperature. In contrast, at a fixed temperature, it increases with increasing strain rate. Ultimately, the DRX kinetics model of AlCu4 SiMg alloy and the consequence of the FE analysis were validated by microstructure observations.
文摘A semi-empirical adsorption kinetic model was proposed with the time compensation method to describe the chemisorption of SO2 in flue gas by carbon adsorbents for flue gas purification.The change in adsorption capacity and adsorption rate with time at different water vapor concentrations and different SO2 concentrations was studied.The model was in good agreement with experimental data.The surface reaction was probably the rate controlling step in the early stage for SO2 adsorption by ZL50 activated carbon.The parameters m and n in the nth order adsorption kinetic model were related to the magnitude of the time compensation and adsorption driving force,respectively.The change of parameter n with water vapor concentrations and sulfur dioxide concentrations was studied and some physical implications were given.The sum of square errors was less than 1.0 and the average absolute percentage deviations ranged from 0.5 to 3.2.The kinetic model was compared with other models in the literature.
