大庆常渣催化裂解反应动力学模型

An 8-lump kinetic model was proposed to predict the yields of propylene,ethylene and gasoline in the catalytic pyrolysis process of Daqing atmospheric residue.The model contains 21 kinetic parameters and one for catalyst deactivation.A series of experiments were carried out in a riser reactor over catalyst named LTB-2.The kinetic parameters were estimated by using sub-model method,and apparent activation energies were calculated according to the Arrhenius equation.The predicted yields coincided well with the experimental values.It shows that the kinetic parameters estimated by using the sub-model method were reliable.     

Determination of metastable zone and induction time of analgin for cooling crystallization

The solubility, metastable zone width, and induction time of analgin for unseeded batch cooling crystallization in ethanol–aqueous system were experimentally determined. The solubility data could be well described by the van't Hoff equation model. The metastable zone width at various cooling rates was measured, and some parameters of nucleation kinetic were calculated using the Ny'vlt theory. Furthermore, the induction period of various temperatures and supersaturation ratios was also measured. According to classical nucleation theory, some nucleation parameters and interfacial energy was calculated through the induction time(t_(ind)) data. Homogeneous nucleation tended to occur when the supersaturation is high, whereas heterogeneous nucleation was more likely to occur when the supersaturation is low.     

Degradation Kinetics of Xylose and Glucose in Hydrolysate Containing Dilute Sulfuric Acid

In preparation of fuel alcohol from biomass as feedstock, hydrolysis with dilute acid as catalyst is one way to produce fermentable saccharide, xylose and glucose. However, the acid is also the catalyst in degradation of xylose and glucose and the yield of sacchride is dependent on the kinetic behaviors of saccharide. The degradation kinetics of xylose and glucose in the hydrolysate was investigated under the conventional process conditions of hydrogen ion concentration from 0.05 to 0.2 mol/L and temperature from 150 to 200℃. With a numerical calculation method, the kinetic parameters were estimated, and the activation energy of xylose and glucose in the degradation reaction was obtained. The kinetic equations correlating the effect of hydrogen ion concentration on the rate constants of degradation reaction were established. Comparison between the calculated results from the equations and experimental ones proved that the established kinetic model could satisfactorily predict the degradation behavior of xylose and glucose in the acidic hydrolysate.     

ZL50活性炭吸附脱除二氧化硫的吸附动力学模型(英文)

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.     

Unseeded Induction Period and Primary Nucleation of Lithium Carbonate

A set of laser apparatus was used to study induction period and primary nucleation of lithium carbonate in reactive crystallization. The results show that induction period increases with the decrease of supersaturation degree and temperature. Magnetic field has nearly no impact on it, while the use of ultrasound reduces it obviously. The impacts of some impurities and additives on primary nucleation were investigated. It is found that the presence of Na2SO4, NH4Cl, (NH4)2SO4 and EDTA disodium prolongs induction period, whereas KCl, NaCl, NaBr and CH4N2O can decrease it. Many important parameters of primary nucleation are also obtained, as temperature goes up from 283 to 313 K, interfacial tension decreases from 44.8 to 41.5 mJ/m2, contact angle varies from 82.9o to 88.7o, nucleation order is between 5.0 and 5.4, surface entropy factors are all above 5, suggesting that the growth mechanism is a spiral growth. Besides, both the homogeneous and heterogeneous primary nucleations were monitored with on-line focused beam reflectance measurement.     

褐煤活性炭吸附苯酚的研究

The feasibility and adsorption effect of lignite activated carbon for phenol removal from aqueous solutions were evaluated and investigated. A series of tests were performed to look into the influence of various experimental parameters such as contact time, initial phenol concentration, temperature, and pH value on the adsorption of phenol by lignite activated carbon. The experimental data were fitted well with the pseudo-second-order kinetic model. The adsorption is an endothermic process and conforms to Freundlich thermodynamic model. The results indicate that the lignite activated carbon is suitable to be used as an adsorbent material for adsorption of phenol from aqueous solutions.     

惰性粒子喷动床中制备超细碳酸钙的实验与建模

A novel reaction-drying process was carried out in a spouted bed reactor with inert particles and used to prepare ultrafine CaCO3 particles. Effects of concentrations of CO2 and Ca(OH)2, and reaction temperature on Ca(OH)2 conversion were experimentally investigated. The particle sizes and composition of CaCO3 produced were characterized with transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results indicated that ultrafine CaCO3 particles with mean size of 80 nm could be obtained with this novel process.By modifying the Arrhenius Equation and considering the Ca(OH)2 state, a kinetic model was established to describe the process in the spouted bed. The model parameters estimated from the reaction-drying experiments were found to fit well the experimental data, indicating the applicability of the proposed kinetic model.     

三段式谷氨酸棒杆菌发酵生产生物絮凝剂的过程及动力学模拟(英文)

Fermentation of bioflocculant with Corynebacterium glutamicum was studied by way of kinetic modeling. Lorentzian modified Logistic model, time-corrected Luedeking–Piret and Luedeking–Piret type models were pro-posed and applied to describe the cell growth, bioflocculant synthesis and consumption of substrates, with the correlation of initial biomass concentration and initial glucose concentration, respectively. The results showed that these models could well characterize the batch culture process of C. glutamicum at various initial glucose con-centrations from 10.0 to 17.5 g·L?1. The initial biomass concentration could shorten the lag time of cel growth, while the maximum biomass concentration was achieved only at the optimal initial glucose concentration of 16.22 g·L?1. A novel three-stage fed-batch strategy for bioflocculant production was developed based on the model prediction, in which the lag phase, quick biomass growth and bioflocculant production stages were sequentially proceeded with the adjustment of glucose concentration and dissolved oxygen. Biomass of 2.23 g·L?1 was obtained and bioflocculant concentration was enhanced to 176.32 mg·L?1, 18.62% and 403.63%higher than those in the batch process, respectively, indicating an efficient fed-batch culture strategy for bioflocculant production.     

Physicochemical properties of aqueous solutions of sodium glycinate in the non-precipitation regime from 298.15 to 343.15 K

The physicochemical properties, including the density, viscosity, and refractive index of aqueous solutions of sodium glycinate as a solvent for CO2 absorption in the non-precipitation regime were measured under the wide temperature range of 298.15 to 343.15 K. The concentration of the sodium glycinate in an aqueous form in the non-precipitation regime was identified up to 2.0 mol·L?1. The coefficients of thermal expansion values were estimated from measured density data. It was found that, the densities, viscosities and refractive indices of the aqueous sodium glycinate decrease with an increase in temperature, whereas with increasing sodium glycinate concentration in the solution, all three properties increase. Thermal expansion coefficients slightly increase with rising temperature and concentration. The measured values of density, viscosity and refractive index were correlated as a function of temperature by using the least squares method. The predicted data obtained from correlation equations for all measured properties were in fairly good agreement with the experimental data.     

纤维蛋白原在微胶囊表面的吸附行为

Alginate-chitosan-alginate (ACA) microcapsules have been widely studied as devices for the immuno-isolation and transplantation of living cells.However, long-term survival of the micro-encapsulated cell grafts and thus their potential clinical applications are hampered by the pericapsular fibrotic overgrowth induced by adsorbed protein.In this study, the adsorption behavior of plasma fibrinogen (Fgn) onto ACA microcapsules was studied by using the batch technique.The results showed that the equilibrium time for the adsorption was 24 h.The adsorption of Fgn onto ACA microcapsules fitted very well with Freundlich isotherm, which was indicative of multilayer adsorption.The kinetic experimental data correlated well with the second-order kinetic model,indicating that chemical sorption was the rate-limiting step.The effects of pH and ionic strength on the adsorption were also studied to interpret the mechanism of adsorption.It was found that the amount of adsorbed Fgn decreased with increasing pH in the range of 4.9—7.4.At pH 7.4, the amount of adsorbed Fgn increased with increasing NaCl concentration, and then decreased with further increase in NaCl concentration.At pH 6.0, the amount of adsorbed Fgn decreased with increasing NaCl concentration, indicating that electrostatic interaction was one of the main interactions between Fgn and ACA microcapsules and the positively charged chitosans which was not sufficiently neutralized on the surface of microcapsules induced the adsorption.     

GROWTH AND NUCLEATION KINETICS IN BATCH CRYSTALLIZATION OF TRICLOSAN

Batch crystallization of triclosan, a broad spectrum antibacterial agent, was carried out under isothermal conditions (at 10°C) with n-hexane as the solvent. Supersaturation was generated by cooling a seeded solution. Samples were collected at periodic intervals. Triclosan concentration in solution was determined by UV-spectrophotometry and particle size distribution by optical microscopy. Growth and nucleation kinetic parameters were obtained. The data indicated size independent growth. Growth kinetic parameters based on triclosan concentration in solution were in reasonable agreement with growth kinetic parameters obtained from cumulative size distribution data. Growth and nucleation kinetic orders were comparable to those reported in the literature.     

GROWTH AND NUCLEATION KINETICS IN BATCH CRYSTALLIZATION OF TRICLOSAN

Batch crystallization of triclosan, a broad spectrum antibacterial agent, was carried out under isothermal conditions (at 10°C) with n-hexane as the solvent. Supersaturation was generated by cooling a seeded solution. Samples were collected at periodic intervals. Triclosan concentration in solution was determined by UV-spectrophotometry and particle size distribution by optical microscopy. Growth and nucleation kinetic parameters were obtained. The data indicated size independent growth. Growth kinetic parameters based on triclosan concentration in solution were in reasonable agreement with growth kinetic parameters obtained from cumulative size distribution data. Growth and nucleation kinetic orders were comparable to those reported in the literature.     

添加晶种的间歇结晶器数学模型

动力学参数是设计结晶器和优化过程操作的主要依据。针对添加晶种的二次成核结晶过程，采用经验方程将反映结晶固相信息的透光率数据与CSD的二阶矩量进行关联，建立了包含透光率、液相浓度和相对过饱和度的动力学模型。并以KNO3-H2O为对象，运用该模型求取了结晶成核和生长动力学参数，结果与文献值相近。     

Modeling and Bayesian parameter estimation for semibatch pH‐shift reactive crystallization of l‐glutamic acid

A mathematical model for semibatch pH‐shift reactive crystallization of l ‐glutamic acid is developed that takes into account the effects of protonation and deprotonation in the species balance of glutamic acid, crystal size distribution, polymorphic crystallization, and nonideal solution properties. The crystallization mechanisms of  α‐ and β‐forms of glutamic acid are addressed by considering primary and secondary nucleation, size‐dependent growth rate, and mixing effects on nucleation. The kinetic parameters are estimated by Bayesian inference from batch experimental data collected from literature. Probability distributions of the estimated parameters in addition to their point estimates are obtained by Markov Chain Monte Carlo simulation. The first‐principles model is observed in good agreement with the experimental data and can be further used for model predictions in robust control strategies. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2828–2838, 2014     

KNO3-H2O溶液间歇结晶动力学

基于ΔL定律推导了晶体线性生长速率的数学表达式,利用已建立的溶液间歇结晶动力学实验研究手段实现了溶液透光率和浓度的在线测量.利用经验模型关联线性生长速率和相对过饱和度求取了生长动力学参数,并与文献值进行了比较.结果发现：对于自发成核结晶过程,综合动态透光率、过饱和度和经验模型可对成核和生长阶段进行定性识别.     

KNO3-H2O溶液间歇结晶动力学

基于ΔL定律推导了晶体线性生长速率的数学表达式，利用已建立的溶液间歇结晶动力学实验研究手段实现了溶液透光率和浓度的在线测量.利用经验模型关联线性生长速率和相对过饱和度求取了生长动力学参数，并与文献值进行了比较.结果发现：对于自发成核结晶过程，综合动态透光率、过饱和度和经验模型可对成核和生长阶段进行定性识别.     

Modeling batch crystallization processes: Assumption verification and improvement of the parameter estimation quality through empirical experiment design

In this work, experimental data of different batches was used for estimation of the kinetic parameters for the secondary nucleation framework of Gahn and Mersmann [Gahn, C. and Mersmann, A., 1999. Brittle fracture in crystallization processes. Chem. Eng. Sci. 54, 1273–1292].An empirical experiment design procedure was used to design an informative batch experiment through optimization of the seed quality, size and mass and process conditions at seeding. The parameters estimated using the data of the designed experiment showed smaller magnitudes of the confidence ellipsoids and standard deviations as compared to those obtained by using the data of conventional (un)seeded batch experiments. It was shown that the designed experiment allowed reducing uncertainty in the initial conditions, namely, the mass and crystal size distribution of the initial population of crystals and the initial supersaturation.It was also demonstrated that the main reason for the model/process mismatch was the origin of nuclei. Dynamic experimental data could be described better if the state of the crystals forming the crystallization system corresponded to the assumptions of the used kinetic model. Differences in the crystal surface properties, shape, and strain content could be responsible for a divergent nucleation and growth behavior in batches that were initiated either by primary nucleation, seeding with small ground seeds or seeding with coarse crystals from the product of the previous batch.     

Iterative parameter estimation for extraction of crystallization kinetics of potassium chloride from batch experiments

Extraction of crystallization kinetics, the fundamental information which governs the performance of a crystallization process, is characterized by experimental difficulties in MSMPR and mathematical difficulties in batch crystallization. Here, a rigorous approach is taken to estimate kinetic parameters from a batch crystallizer. The two step LaxWendorff technique is adapted for the solution of the population balance in a batch crystallizer and an iterative self-correcting least squares algorithm is implemented for the estimation of the kinetic parameters. The need for multi-response estimation as opposed to single-response from terminal CSD is demonstrated. The kinetics extracted are average ones, representing primary and secondary nucleation kinetics. It is found that the kinetic parameters estimated by multi-response technique have a superior predictive capability as opposed to those obtained using the terminal CSD only. An advantage of the proposed algorithm is that the measurement of course of supersaturation, which is difficult to perform, is not required.     

甲烷水合物在纯水中的生成动力学

引言一些低分子量气体,如石油和天然气中C_1～C_4轻烃、氮气、硫化氢、二氧化碳和惰性气体等,在一定压力和温度的条件下可与水形成一类笼形结构的冰状晶体,即所谓的气体水合物．气体水合物是一类较为特殊的包络化合物：主体水分子通过氢键相互结合形成一种内含空隙的笼形框架,客体分子则被笼罩于这些空隙中．主、客体分子之间的作用力为vanderWaals力．水合物晶体最为常见的两种结构分别称为结构I（体心立方构型）和结构Ⅱ（金刚石构型）．甲烷和水形成结构I水合物．文献阐述了开展水合物生成动力学研究的重要意义．但由于水合物生成…