STRUCTURE OPTIMIZATION OF A CIRCULATING MOVING BED REACTOR

A stress distribution model for a liquid-solid circulating moving bed reactor that consists of a bottom reaction chamber, a top regeneration chamber, a coupling standpipe, a particle transportation system, and a bottom standpipe is established based on the equations of continuity and momentum balance. Simulations show that the stress concentration regions are at the bottom of the regeneration chamber and the coupling standpipe. To reduce the maximal stress and increase the operation flexibility in a reactor for the 2000-ton-per-year production of linear alkylbenzene, the regeneration chamber should have a low height-to-radius ratio (about 9), a suitable half-conical angle between 28° and 35°, and standpipe radius of about 0.05 m.     

STRUCTURE OPTIMIZATION OF A CIRCULATING MOVING BED REACTOR

A stress distribution model for a liquid-solid circulating moving bed reactor that consists of a bottom reaction chamber, a top regeneration chamber, a coupling standpipe, a particle transportation system, and a bottom standpipe is established based on the equations of continuity and momentum balance. Simulations show that the stress concentration regions are at the bottom of the regeneration chamber and the coupling standpipe. To reduce the maximal stress and increase the operation flexibility in a reactor for the 2000-ton-per-year production of linear alkylbenzene, the regeneration chamber should have a low height-to-radius ratio (about 9), a suitable half-conical angle between 28° and 35°, and standpipe radius of about 0.05 m.     

气相法聚乙烯流化床反应器冷凝模式操作工艺

综述了气相法聚乙烯流化床反应器冷凝模式操作工艺方面的最新专利技术动态。阐明了流化床聚合反应器中气液导流器和喷雾器的设计原理和方法，详细分析了操作工艺条件与产品质量和产率之间的关系。还进一步指出茂金属催化剂与冷凝工艺的结合是一条最优的技术路线。     

用正交配置法优化氯乙烯合成固定床反应器操作

首先利用二维拟均相数学模型结合正交配置法对工业乙炔法生产氯乙烯的固定床反应器进行了模拟。然后在模拟的基础上对该反应器的操作状况进行了分析，指出了目前操作中所存在的问题。最后研究了操作参数对反应器热点温度和出口转化率的影响，得出了优化的操作条件。     

MODELING AND OPTIMIZATION OF LACTIC ACID SYNTHESIS BY THE ALKALINE DEGRADATION OF FRUCTOSE IN A BATCH REACTOR

The present work deals with the determination of the optimal operating conditions of lactic acid synthesis by the alkaline degradation of fructose. It is a complex transformation for which detailed knowledge is not available. It is carried out in a batch or semi-batch reactor. The “Tendency Modeling” approach, which consists of the development of an approximate stoichiometric and kinetic model, has been used. An experimental planning method has been utilized as the database for model development. The application of the experimental planning methodology allows comparison between the experimental and model response. The model is then used in an optimization procedure to compute the optimal process. The optimal control problem is converted into a nonlinear programming problem solved using the sequencial quadratic programming procedure coupled with the golden search method. The strategy developed allows simultaneously optimizing the different variables, which may be constrained. The validity of the methodology is illustrated by the determination of the optimal operating conditions of lactic acid production.     

MODELING AND OPTIMIZATION OF LACTIC ACID SYNTHESIS BY THE ALKALINE DEGRADATION OF FRUCTOSE IN A BATCH REACTOR

The present work deals with the determination of the optimal operating conditions of lactic acid synthesis by the alkaline degradation of fructose. It is a complex transformation for which detailed knowledge is not available. It is carried out in a batch or semi-batch reactor. The “Tendency Modeling” approach, which consists of the development of an approximate stoichiometric and kinetic model, has been used. An experimental planning method has been utilized as the database for model development. The application of the experimental planning methodology allows comparison between the experimental and model response. The model is then used in an optimization procedure to compute the optimal process. The optimal control problem is converted into a nonlinear programming problem solved using the sequencial quadratic programming procedure coupled with the golden search method. The strategy developed allows simultaneously optimizing the different variables, which may be constrained. The validity of the methodology is illustrated by the determination of the optimal operating conditions of lactic acid production.     

EXPERIMENTAL INVESTIGATION OF KINETIC AND TRANSPORT PARAMETERS IN A WALL－COOLED FIXED－BED REACTOR

ＥＸＰＥＲＩＭＥＮＴＡＬＩＮＶＥＳＴＩＧＡＴＩＯＮＯＦＫＩＮＥＴＩＣＡＮＤＴＲＡＮＳＰＯＲＴＰＡＲＡＭＥＴＥＲＳＩＮＡＷＡＬＬ－ＣＯＯＬＥＤＦＩＸＥＤ－ＢＥＤＲＥＡＣＴＯＲＺｈｅｎ－ＭｉｎＣＨＥＮＧａｎｄＷｅｉ－ＫａｎｇＹＵＡＮ（ＵＮＩＬＡＢＲｅｓｅ...     

气升式反应器中三相体系进行半连续操作的气含率和传质特性研究

就出现在细胞培养等气液固三相体系在气升式反应器(ALR)中气含率和传质系数同反应器结构参数、固含量及操作条件之间的关系作了理论推导,在不同结构形式的 ALR 中对空气/0.15NaCl 溶液(内含不同数量的固体颗粒)体系作了实验测定,估计了模型中的待定参数,求出气含率(■)和氧的传质系数(K_Lα):■由此可推算二氧化碳的传质系数,并讨论了反应器高度和气体分布器的影响。     

OPTIMAL DESIGN FOR THE RESIDUAL OIL HYDRODEMETALLATION IN A FIXED BED REACTOR

A restricted diffusion model was used to investigate the optimal design for the residual oil hydrodemetallation in a fixed bed reactor. Based on the total lifetime activity, the optimal catalyst pore sizes and their corresponding optimal division locations in the bed were determined. The results indicate that the total amount of demetallation could be significantly improved by using a multi-layers reactor and the nonuniform activity catalysts. In addition, the influence of the Thiele modulus on the optimal designs were illustrated.     

CONTROL OF A CONTINUOUS POLYMERIZATION REACTOR BY WIENER INPUT/OUTPUT DATA-BASED PREDICTIVE CONTROLLER WITH DIRECT INVERSE IDENTIFICATION

This article reports an experimental study for the identification and predictive control of a continuous methyl methacrylate (MMA) solution polymerization reactor. The Wiener model was introduced to identify the polymerization reactor in a more efficient manner than the conventional methods of Wiener model identification. In particular, the method of subspace identification was employed and the inverse of the nonlinear part was directly identified. The input variables in this work were the jacket inlet temperature and the feed flow rate, while the monomer conversion and the weight average molecular weight were selected as the output variables. On the basis of the identified model a Wiener-type input/output data-based predictive controller was designed and applied to the property control of polymer product in the continuous MMA polymerization reactor by conducting an on-line digital control experiment with online densitometer and viscometer. Despite the complex and nonlinear characteristics of the polymerization reactor, the proposed controller was found to perform satisfactorily for property control in the multiple-input multiple-output system with input constraints for both set-point tracking and disturbance rejection. This was also confirmed by simulation results.     

CONTROL OF A CONTINUOUS POLYMERIZATION REACTOR BY WIENER INPUT/OUTPUT DATA-BASED PREDICTIVE CONTROLLER WITH DIRECT INVERSE IDENTIFICATION

This article reports an experimental study for the identification and predictive control of a continuous methyl methacrylate (MMA) solution polymerization reactor. The Wiener model was introduced to identify the polymerization reactor in a more efficient manner than the conventional methods of Wiener model identification. In particular, the method of subspace identification was employed and the inverse of the nonlinear part was directly identified. The input variables in this work were the jacket inlet temperature and the feed flow rate, while the monomer conversion and the weight average molecular weight were selected as the output variables. On the basis of the identified model a Wiener-type input/output data-based predictive controller was designed and applied to the property control of polymer product in the continuous MMA polymerization reactor by conducting an on-line digital control experiment with online densitometer and viscometer. Despite the complex and nonlinear characteristics of the polymerization reactor, the proposed controller was found to perform satisfactorily for property control in the multiple-input multiple-output system with input constraints for both set-point tracking and disturbance rejection. This was also confirmed by simulation results.     

EFFECTS OF PARTICLE CHARACTERISTICS ON THE PERFORMANCE OF A FAST FLUIDIZED BED REACTOR

A heterogeneous model for the fast fluidized bed reactor which carries out a gas-solid non catalytic reaction is presented. The hydrodynamics of the fast fluidized bed is characterized by the model of Kwauk et al. (1985) which assumes the existence of two phases; a dense phase and a dilute pneumatic transport phase. For a given solid flowrate, the length of the reactor occupied by each phase depends on gas velocity, particle diameter and density and average voidage within the reactor. The gas-solid reaction is assumed to follow the shrinking core model. The solids are assumed to be completely backmixed in the dense phase and move in plug How in the dilute pneumatic transport phase. The gas phase is assumed to be in plug flow in both phases

For given gas and solid flowrates, the transition from the dense phase flow to the fast fluidized bed (containing two regions) as functions of particle size and density is determined using the model of Kwauk et al. (1985). The numerical solution of the governing mass balance equations show that for given solid and gas flowrates, (and average voidage) the gas phase conversion shows an unusual behavior with respect to particle diameter and density. Such behavior is resulted from the effects of particle diameter and density on the reactor volume occupied by each phase and the effect of particle diameter on the apparent reaction rate. The numerical results show that a fast fluidized bed gives the best conversion at large particle density and for the particle diameter which results the fast fluidized bed to be operated near the pure dense phase flow.     

CATALYTIC COMBUSTION OF NATURAL GAS IN A FIXED BED REACTOR WITH FLOW REVERSAL

A new application of the fixed bed catalytic reactor with flow reversal for combustion of natural gas is investigated by mathematical modeling and computer simulation. Comparison between the results obtained for this new reactor and those for a classic catalytic fixed bed is made. Inexpensive perovskite type catalysts containing no noble metals were used. It is shown that an appropriate choice of operating parameters (concentration and temperature of input gas mixture, superficial gas velocity, size and shape of catalyst and inert material, volumetric ratio between catalyst and inert material in the bed) allows for a methane combustion at must lower temperatures in the reactor with flow reversal than in a classic catalytic reactor. Under such a low temperature combustion, no nitrogen oxides are produced.     

日产千吨两段径向间接换热式氨合成塔系统的模拟及操作优化

从系统角度出发，运用系统观念对氨合成塔进行了模拟和优化。认为ＴｏｐｓΦｅＳ－２００型氨合成塔是由反应床和换热器组成的不可再分块，并针对实际生产操作时的特点，较为详细地考察了入塔温度、氢氮比和冷却气体分率对整个合成塔性态的影响，在此基础上对合成塔作了优化研究，为合成氨装置的操作提供依据。     

硅橡胶合成催化剂氢氧化四甲铵的制备新工艺

采用有效面积为4.5dm~2的全氟阳离子交换膜,在阳极室容积为500mL、阴极室容积为580mL的二室单膜电渗析槽内,以四甲基氯化铵为原料,制备了合成有机硅橡胶及其他有机硅产品聚合用催化剂氢氧化四甲铵(Me_4NOH)。阳极室四甲基氯化铵浓度为30％(质量),阴极室可得到纯度为 13％-15％、Cl~-<0.01％、Na~+<0.0001％和 K~+<0.000 5％的 Me_4NOH。产品经减压浓缩即得到 Me_4NOH·5H_2O晶体。     

A SIMPLE METHOD FOR STUDYING THE KINETICS OF GAS-SOLID REACTIONS IN A FLUIDIZED BED REACTOR

A methodology for studying the kinetics of gas-solid reactions in a fluidized bed reactor is presented. This procedure is based on the analysis of the response of the system (flue gases) when batches of solids of different weight are added to the reactor. The method has been applied to the study of limestone particle calcination. The calcination rate constants obtained are in good agreement with those found in the literature. The method offers the advantage of simplicity and avoids the use of model assumptions or empirical correlations.     

STEADY STATE SIMULATION OF A PACKED BED REACTOR FOR THE PARTIAL OXIDATION OF METHANOL TO FORMALDEHYDE. INFLUENCE OF DIFFUSIONAL PHENOMENA AND CATALYST ACTIVITY DISTRIBUTION WITHIN THE PELLETS

The scope of this work is to present a real case in which reactor performance predicted theoretically, avoiding the numerical integration within the particle, is compared with experimental findings. The influence of realistic catalytic activity distributions are also studied since minimum extra efforts are needed with the procedure presented in this contribution. The partial oxidation of methanol in a tubular catalytic reactor, studied by Windes et al. (1989), giving rise to formaldehyde and carbon monoxide as main reaction products, was used as example for the application of our procedure. Both, inter and intraparticle, diffusional limitations were taken into account. Experimental data and theoretical predictions along the reactor were compared in terms of outlet conversion and temperature profiles showing a fairly good agreement which gives support to the procedure developed in this contribution to predict reactor performance. Furthermore, the effect of different realistic activity distribution function was simulated and its influence on the reactor performance is shown. The obtained results are discussed and some interesting conclusions are withdrawn.     

NUMERICAL STUDY OF THE EFFECT OF THE WALL ON THE DISTRIBUTION OF ISOTHERMAL TWO-PHASE FLOW IN THE BED OF A HYDRODESULFURIZATION REACTOR

Numerical simulations of the isothermal two-phase flow distribution in the packed bed of a reactor used for fuel hydrodesulfurization using the commercial software Fluent are reported. As a first step, the heat and mass transfer as well as the chemical reactions are not taken into account. The reactor considered has, above the bed, a distribution tray equipped with chimneys. A Eulerian three-phase model that considers the catalyst particles as a granular static phase was used following the Holub single-slit model for particle fluid interaction to compute the liquid-solid and gas-solid drag coefficients. Physical properties of the fluids are assumed to be constant. In the present study, the tendency of the liquid to move towards the wall of the reactor was studied in a bed 11 m in depth. The simulations predict that there is no suction effect on the flow caused by the wall. As the two-phase flow moves downward through the bed, a slow radial liquid spreading takes place. However, flow distribution is not completely uniform, at least at a distance of 11 m from the inlet.