2-氯-5-氯甲基吡啶在气升环流反应器中的合成研究

A new process for the direct chlorination of 2-chloro-5-methylpyridine to yield 2-chloro-5-chloro-methylpyridine in an airlift loop reactor (ALR) has been studied.Five main reaction conditions including TR,na/ns,cp,Qg and dD/dR were optimized.The average molar yield and purity of 2-chloro-5-chloromethylpyridine obtained were 79% and 98.5% respectively under the optimum operating conditions.Finally,the efficiency for the preparation of 2-chloro-50chloromethylpyridine with ALR and stirred tank reactor(STR) respectively was compared.     

T型撞击流反应器的微观混合性能研究(英文)

Confined impinging jet reactor (CIJR) offers advantages for chemical rapid processes and has become an important new reactor used in the chemical industry. The micromixing efficiency in a T-shaped CIJR for two tubes of inner diameter of 3 mm was studied by using a parallel competing iodide–iodate reaction as the working system. In this work, the effects of different operating conditions, such as impinging velocity and acid concentration, on segregation index were investigated. In addition, the effects of the inner nozzles diameter and the distance L between the jet axis and the top wal of the mixing chamber on the micromixing efficiency were also considered. It is concluded that the best range of L in this CIJR is 6.5–12.5 mm. Based on the incorporation model, the estimated minimum micromixing time tm of CIJR approximately equals to 2 × 10?4 s. These experimental results indicate clearly that CIJR possesses a much better micromixing performance compared with the conventional stirred tank (micromixing time of 2 × 10?3 to 2 × 10?2 s). Hence, it can be envisioned that CIJR has more promising applications in various industrial processes.     

Modeling-based optimization of a fixed-bed industrial reactor for oxidative dehydrogenation of propane

An industrial scale propylene production via oxidative dehydrogenation of propane(ODHP)in multi-tubular reactors was modeled.Multi-tubular fixed-bed reactor used for ODHP process,employing 10000 of small diameter tubes immersed in a shell through a proper coolant flows.Herein,a theory-based pseudo-homogeneous model to describe the operation of a fixed bed reactor for the ODHP to correspondence ole fin over V_2O_5/γ-Al_2O_3catalyst was presented.Steady state one dimensional model has been developed to identify the operation parameters and to describe the propane and oxygen conversions,gas process and coolant temperatures,as well as other parameters affecting the reactor performance such as pressure.Furthermore,the applied model showed that a double-bed multitubular reactor with intermediate air injection scheme was superior to a single-bed design due to the increasing of propylene selectivity while operating under lower oxygen partial pressures resulting in propane conversion of about 37.3%.The optimized length of the reactor needed to reach 100%conversion of the oxygen was theoretically determined.For the single-bed reactor the optimized length of 11.96 m including 0.5m of inert section at the entrance region and for the double-bed reactor design the optimized lengths of 5.72m for the first and 7.32 m for the second reactor were calculated.Ultimately,the use of a distributed oxygen feed with limited number of injection points indicated a signi ficant improvement on the reactor performance in terms of propane conversion and propylene selectivity.Besides,this concept could overcome the reactor runaway temperature problem and enabled operations at the wider range of conditions to obtain enhanced propylene production in an industrial scale reactor.     

Repeated-Batch and Continuous Production of L-Lactic Acid by Rhizopus oryzae Immobilized in Calcium Alginat Beads: Reactor Performance and Kinetic Model

Repeated-batch and continuous production of L-lactic acid by immobilized Rhizopusoryzae with calcium alginate entrapment method in a three-phase fluidized-bed bioreactor was stud-ied.The operation conditions were optimized.The productivity based on total reactor volume wasabout 3 times higher than that with free cells in a traditional stirred tank bioreactor.A mathemat-ical model was proposed and the model predictions were in good agreement with the experimentaldat.     

一种新的生产计划与催化裂化装置过程操作集成的闭环策略

Production planning models generated by common modeling systems do not involve constraints for process operations, and a solution optimized by these models is called a quasi-optimal plan. The quasi-optimal plan cannot be executed in practice some time for no corresponding operating conditions. In order to determine a practi- cally feasible optimal plan and corresponding operating conditions of fluidized catalytic cracking unit （FCCU）, a novel close-loop integrated strategy, including determination of a quasi-optimal plan, search of operating conditions of FCCU and revision of the production planning model, was proposed in this article. In the strategy, a generalized genetic algorithm （GA） coupled with a sequential process simulator of FCCU was applied to search operating conditions implementing the quasi-optimal plan of FCCU and output the optimal individual in the GA search as a final genetic individual. When no corresponding operating conditions were found, the final genetic individual based correction （FGIC） method was presented to revise the production planning model, and then a new quasi-optimal production plan was determined. The above steps were repeated until a practically feasible optimal plan and corresponding operating conditions of FCCU were obtained. The close-loop integrated strategy was validated by two cases, and it was indicated that the strategy was efficient in determining a practically executed optimal plan and corresponding operating conditions of FCCU.     

Detailed kinetics of methylphenyldichlorosilane synthesis from methyldichlorosilane and chlorobenzene by gas phase condensation

Methylphenyldichlorosilane (MPDS, CH3C6H5SiCl2) is an important silicone monomer for the synthesis of high-performance polymethylphenylsiloxane polymers. In this work, the mechanism of the synthesis of MPDS from methyldichlorosilane and chlorobenzene by gas phase condensation was studied, and a kinetic model with 35 species and 58 elementary reactions was established. Experiments were carried out in a tubular reactor under a wide range of reaction conditions. The calculated mole fractions of the reactants and products were in a good agreement with the experimental results. A mechanism of the insertion of chloromethylsilylene into the C-Cl bond of chlorobenzene was proposed, which was proved to be the main pathway of MPDS production. The established kinetic model can be used in design and optimization of the industrial reactor for MPDS synthesis.     

搅拌釜内固-液悬浮体系的CFD-DEM模拟(英文)

Computational fluid dynamics-discrete element method （CFD-DEM） coupled approach was employed to simulate the solid suspension behavior in a Rushton stirred tank with consideration of transitional and rotational motions of millions of particles with complex interactions with liquid and the rotating impeller. The simulations were satisfactorily validated with experimental data in literature in terms of measured particle velocities in the tank. Influences of operating conditions and physical properties of particles （i.e., particle diameter and density） on the two-phase flow field in the stirred tank involving particle distribution, particle velocity and vortex were studied. The wide distribution of particle angular velocity ranging from 0 to 105 r·min-1 is revealed. The Magnus force is comparable to the drag force during the particle movement in the tank. The strong particle rotation will generate extra shear force on the particles so that the particle morphology may be affected, especially in the bio-/polymer-product related processes. It can be concluded that the CFD-DEM coupled approach provides a theoretical way to under-stand the physics of particle movement in micro-to macro-scales in the solid suspension of a stirred tank.     

HYDRODYNAMIC MODEL FOR THE IMPELLER REGION IN AN AERATED AND STIRRED TANK

The radial and axial distribution of mean 1iquid velocity were measured by a.hot-filmanemometer at the impeller region in an aerated and stirred tank 0.287m in diameter.The tangentialjet model for impeller discharge flow used for single phase flow was modified to conform with thecharacteristics of gas-liquid flow.The radial and axial velocity profiles at the impeller region in thegas-liquid stirred tank were calculated by the model The results predicted by the model were in goodagreement with those obtained in experiment.     

低高径比外循环气升式生物反应器带渣发酵生产有效霉素

Fermentation experiments to produce validamycins from crude substrates by Streptoniyces hygroscopi-cus were carried out in an external-loop airlift bioreactor (0.0115 m3 ) with a low ratio of height to diameter of the riser of 2.9 and a ratio of riser to downcomer diameter of 6.6. The influences of gas flow rate and liquid volume on fermentation of validamycins were investigated. Comparisons of validamycin fermentation were made among the external-loop airlift bioreactor, a mechanically stirred tank bioreactor (0.010m3 ) and shaking flasks. Under the same operation conditions including fermentation medium composition, inoculum ratio and culture temperature, the fermentation time in the external-loop airlift bioreactor (45 h) was shorter than that in the shaking flasks (100 h) and the same as that in the mechanically stirred tank bioreactor. After a total fermentation time of 45 h under optimized operation conditions, average validamycin concentration obtained in the external-loop airlift bioreactor was     

多层翼形桨搅拌槽内混合过程的CFD模拟

The mixing process in a stirred tank of 0.476m diameter with single, dual and triple 3-narrow blade hydrofoil CBY impellers was numerically simulated by using computational fluid dynamics （CFD） package FLU-ENT6.1. The multi-reference frame （MRF） and standard k-ε turbulent model were used in the simulation. The shaft power and the mixing time predicted by CFD were in good agreement with the experiment. The effects of tracer feeding and detecting positions on mixing time were investigated. The results are of importance to the optimum design of industrial stirred tank/reactors.     

The Preparation of Imidacloprid in a Jet Loop Reactor

A new process for the direct combination of 2-chloro-5-chloromethylpyridine and 2-nitroiminoimidazolidine under benzyltriethylammonium chloride (BTEAC) as the catalyst and butanone as the solvent to yield imidacloprid in an 11.5 L jet loop reactor was developed. Five main reaction conditions including reaction temperature, molar ratio of BTEAC to 2-nitroiminoimidazolidine, concentration of 2-nitroiminoimidazolidine, jet liquid flow rate, and the ratio of the inside diameter of the draft tube to that of the reactor were investigated and optimized. The average molar yield and purity of imidacloprid increased to approximately 80% and 92% under the optimum operating conditions, respectively. Finally, a comparison of the efficiency for the preparation of imidacloprid between the jet loop reactor and the stirred tank reactor under the same operating conditions was conducted.     

The Preparation of Imidacloprid in a Jet Loop Reactor

A new process for the direct combination of 2-chloro-5-chloromethylpyridine and 2-nitroiminoimidazolidine under benzyltriethylammonium chloride (BTEAC) as the catalyst and butanone as the solvent to yield imidacloprid in an 11.5 L jet loop reactor was developed. Five main reaction conditions including reaction temperature, molar ratio of BTEAC to 2-nitroiminoimidazolidine, concentration of 2-nitroiminoimidazolidine, jet liquid flow rate, and the ratio of the inside diameter of the draft tube to that of the reactor were investigated and optimized. The average molar yield and purity of imidacloprid increased to approximately 80% and 92% under the optimum operating conditions, respectively. Finally, a comparison of the efficiency for the preparation of imidacloprid between the jet loop reactor and the stirred tank reactor under the same operating conditions was conducted.     

An approach to control of bioreactors. Application of the gain-scheduling method

A control system based on a combination of the gain-scheduling control method and an adaptive PID controller was designed for the production of xylose from hardwood hemicellulose using a stirring tank reactor. Different operating conditions have been considered for estimating the adjustable parameter (theta) to take into account the changes of energy of the system. The performance of the control system was studied first by numerical simulation, and after implementation in the stirred tank reactor where the controller actually works.     

Optimization of industrial CSTR for vinyl acetate polymerization using novel shuffled frog leaping based hybrid algorithms and dynamic modeling

Industrial scale continuous stirred tank reactor (CSTR) for production and grade transitions of poly vinyl acetate (PVAc) at the different reactor sizes was investigated. Such reactor is known to show oscillatory behavior and to have periodic limit points, particularly at high molecular weights. Four efficient novel hybrid optimization methods which use variable population size genetic algorithm (VPGA), bacterial optimization algorithm (BO) and shuffled frog leaping method (SFL) were introduced for this kind of reactors. These algorithms can reliably find dynamically stable points with desired conditions for PVAc production. The dynamic modeling combined with the new hybrid optimization methods were used to obtain the optimal operating conditions which increased the outlet flow rate by 17%.     

Experimental and theoretical investigation of parametric sensitivity and dynamics of a continuous stirred tank reactor for acid catalyzed hydrolysis of acetic anhydride

The continuous stirred tank reactor is a dynamic system exhibiting nonlinear behavior such as multiplicity and oscillations and, in certain range of operating conditions, may exhibit a parametric sensitivity where small changes in one or more of the input parameters lead to large changes in the output variable. In the present work, hydrolysis of acetic anhydride reaction system was used to demonstrate the existence of parametric sensitivity with respect to the input parameter, the cooling water flow rate. The applications of parametric sensitivity analysis were used for detection of parametric sensitivity in a continuous stirred tank reactor using catalyses hydrolysis of acetic anhydride reaction system. Also, theoretical investigation revealed that the effect of wall capacitance has definite influence on the dynamics of continuous stirred tank reactor. The continuous stirred tank reactor showed parametric sensitivity both in the regions of uniqueness and multiplicity, and a mathematical model was developed for the reactor. The numerically simulated results are in satisfactory agreement with the experimental data.     

叔丁醇体系中化学酶法催化α-蒎烯环氧化

采用叔丁醇作为α-蒎烯环氧化的反应溶剂,使过氧化氢水溶液和其他疏水性反应底物形成均相,构建单相体系以代替传统有机-水“双相”系统。首先在摇瓶中对单相体系进行优化,在α-蒎烯浓度为0.3mol/L时,乙酸乙酯的最适浓度为3.5mol/L,过氧化氢的最适浓度为0.5mol/L,束酸剂为柠檬酸三钠,在40℃下,反应90min,环氧化转化率为92%,收率为88%。此工艺条件下Novozym435重复使用6次后,仍保持64%的相对活力。然后以摇瓶实验为基础,构建了一种连续搅拌釜式反应器（CSTR）,探索反应器的最适运行条件,测试了其长期运行性能,结果表明：当Novozym435酶量为2.0g、过氧化氢浓度为0.5mol/L、停留时间为3h时,釜式反应器的运行效果最好,其转化率可达83%,收率可达79%,在此条件下反应器连续运行十天后依然可以保持70%以上的转化率和55%以上的收率。     

分子筛催化下苯与长直链烯烃的烷基化反应研究

在全混釜批式反应器（ＣＳＴＲ）中研究了Ｙ型分子筛催化剂作用下苯与长直链烯烃的烷基化反应，探讨了投料比对烯烃转化率以及温度对产物选择性的影响。在所设计的新型液固循环反应－再生流化床反应系统中，用工业原料验证了在分子筛催化剂作用下采用该反应系统连续合成长直链基苯的工业可行性     

Scale-up of continuous flow stirred tank reactors

A model of a continuous flow stirred tank reactor based on laboratory experiments successfully describes the behavior of a pilot plant reactor. This model simulates the pilot plant performance over the full range of operating conditions: at high impeller speeds where performance approaches that of a perfectly mixed reactor and at low impeller speeds where performance significantly differs from perfect mixing. The micro-mixed feed model divides the continuous flow stirred tank reactor into a small micro-mixed impeller zone and a large macro-mixer.     

Non-ideal flow in an annular photocatalytic reactor

This study deals with the modelling of non-ideal flow in a tubular photocatalytic reactor with thin layer of TiO₂ photocatalyst. The objective was to analyse different level of mixing in the photoreactor applying basic principles of chemical reaction engineering. For this purpose photocatalytic oxidation of toluene was used as the model reaction. Photocatalytic reactor was operated in two different flow modes: classic type of an annular reactor with basically ideal (plug) flow with some extent of dispersion and annular flow reactor acted as stirred tank reactor with mixing of reaction mixture accomplished by recirculation. A series of experiments with step input disturbance at the entrance of the reactor with different air flow was performed in order to achieve better understanding of the reactor hydrodynamics. Several reactor models are applied, such as one dimensional model of tubular reactor at the steady state conditions, axial dispersion model at non-stationary conditions and the model of the continuous non-stationary stirred tank reactor. Numerical methods necessary for solving model equations and parameter estimation were described.