文丘里引射反应器的喷嘴优化及压降分析

为解决黄磷脱砷系统中搅拌反应器反应不充分的问题,根据其工艺需求,研制出一种新型反应器--文丘里引射反应器,并将其用于贵州某黄磷厂的中试实验中.利用CFD数值模拟软件FLUENT的Realizable k-ε湍流模型和欧拉两相流模型,在经验公式范围内,对4种不同喷嘴出口直径(分别为6、8、10和12 mm)条件下的压降变化进行了研究和考察.结果显示,利用中试装置得到的相关实验数据与数值模拟结果基本吻合,说明数值模拟的结果是可靠的;随着喷嘴出口直径的增大,面积比减小,反应器所形成的压力比越大,驱动能力越强,同时工作效率也越高;喷嘴直径越小,产生的压力降越大,局部能量损失也越大,分散混合效果越好.根据模拟结果,为黄磷脱砷系统中文丘里引射反应器的工业放大设计提供了参考依据.     

硅油光-热老化气升式反应器数值模拟

为进行液浸聚光光伏系统中液浸液体即二甲基硅油在光热条件下的老化实验研究,设计制作了气升式外环流光催化反应器。采用Fluent软件欧拉多相流模型和RNG k-ε湍流模型对反应器进行了三维全尺寸数值模拟。分析了结构参数、操作参数和硅油物性参数对反应器中气液两相流动的影响,得到反应器内循环液速和气含率等参数的分布。模拟结果与实验结果有较好的一致性。模拟结果表明:硅油黏度越小,循环液速越大,气含率越小;反应器适宜操作气速不应大于0.02 m/s;反应器最适宜高径比和环隙面积比分别为47.6和0.31~0.41。     

管式固定床反应器柱状颗粒床层流体流动模拟与实验研究

针对管式固定床反应器内管束数量多、规模大等特点,选取单个管束作为特征结构。对装填不同直径柱状颗粒的管束,采用程序坐标定位的方法,建立柱状颗粒床层的物理模型。采用DEM与CFD联合数值仿真方法,探究反应管内径与柱状颗粒的等比表面积球当量直径之比(管径比Di/dp)对柱状颗粒床层流体流动的影响,并建立单管固定床反应器试验台,采用差压测试方法进行实验研究。结果表明,当Di/dp由5.37增至12.75时,床层空隙率和流体分布均匀性均得到改善,壁面效应的影响由床层中心减弱到管壁。基于数值模拟及实验结果对Di/dp=12.75的柱状颗粒床层进行床层压降Ergun公式常系数修正,CFD模拟计算的结果与拟合公式吻合较好。研究结果能为固定床反应器压降预测提供参考。     

Simulation of pervaporation process for ethanol dehydration by using pilot test results

This paper focuses on providing a pervaporation simulation method for ethanol dehydration from a practical point of view. The simulation procedure is performed by setting up simulation equations which describe the pervaporation process, obtaining the necessary data from pervaporation batch mode pilot tests, verifying the simulation tool through simulations of continuous mode pilot tests, and comparing the simulation results with the real pilot test results. We considered the mass and energy balances that describe separating an ethanol/water mixture by a pervaporation membrane. The simulation equations were mathematically expressed into simultaneous non-linear differential equations based on these balances. The necessary data for simulation consist of the thermophysical properties for the ethanol-water mixture and the characteristic data of a PVA composite membrane. The membrane characteristic data are permeation flux and membrane selectivity, which are functions of feed composition and operating conditions. These data were experimentally determined by a batch mode pilot test. The continuous mode pilot tests were simulated and the simulation results were compared to the real test results. The resulte were fairly good.     

A general simulation model of batch chemical reactors for thermal control investigations

This paper describes the development of a dynamic simulation model for stirred tank batch or semi-batch chemical reactors fitted with an alternative heating-cooling system. Heat and mass balances are established for the reactor and its jacket. Since the general purpose of our research is the thermal control of these reactors, special attention is devoted to the behaviour of the heating-cooling system. In this article, we are particularly concerned with an alternative system, i.e. different fluids at a constant temperature can be alternatively delivered to the jacket. The computer simulation programme is flexible, enabling simulation of a batch or semi-batch reaction vessel, ranging from a laboratory pilot plant to a full-scale production plant. A control algorithm is included which allows reactor operation with open or closed-loop temperature control. To demonstrate the good performance of the simulation model, experimental results are presented for both a pilot plant and an industrial reactor.     

气升式环流反应器实验及三维模拟

利用Fluent软件对气升式环流反应器进行三雏全尺寸的数值模拟,采用欧拉多相流模型和标准k-ε模型模拟反应器内气液两相流动,得到了反应器内流场的详细分布.在此基础上还结合FLOW 3D软件模拟物理流动现象,得到了直观的真实清晰动画,而传统的实验很难测得相关具体的数据.两种数值模拟结果与文献实验值吻合较好,说明了数值模拟的可靠性.     

面向环境保护和低品位资源利用的人为非定态反应技术

本文报道在固定床气固反应器内,采用流向变换非定态操作方式,实现低浓度反应物高转化率放热反应的一系列研究,包括实验室、中试和模型化研究成果。结果表明,这一技术在大气污染治理和低品位资源利用方面具有广阔的应用前景。     

CSFB applied to fluidized-bed gasification of special fuels

The new version of a comprehensive simulation program of moving and fluidized-beds (CSFB or CSFMB) has been tested against data generated from a gasification unit at the University of California at Davis (UCD), Department of Biological and Agricultural Engineering. The pilot operated at atmospheric pressure under bubbling fluidized-bed and consumed various biomasses as well residues. Air was used as gasifying agent and electrical resistances around the reactor helped heating the reactor during start-up and were kept under low energy discharge during experiments. CSFMB was adapted to allow simulation of such cases as well to several other possibilities of additional heating systems to reactors. The present paper presents the results from cases of almond shells and walnut pruning gasification. Good to reasonable agreement between simulation and operational data have been obtained.     

杜229块蒸汽驱扩大试验参数优化设计

鉴于杜229块蒸汽驱先导试验较好的开发效果,进行蒸汽驱的扩大试验,为该块规模汽驱作准备。方案设计中在分析先导试验效果的基础上,利用数值模拟方法优化扩大试验的主要注采参数,最大限度地提高蒸汽驱的开发效果和经济效益。     

选择性催化还原蜂窝状催化剂内流动特性的多尺度模拟

为提高选择性催化还原(SCR)脱硝反应器内催化剂的脱硝效率和使用寿命,从细观和宏观两个角度对SCR脱硝反应器的流动特性多尺度数值进行研究。在细观层面研究了不同高度的催化剂层产生的阻力随进口速度的变化,并计算得到阻力关系式。宏观层面,基于阻力关系式,计算出催化剂宏观结构数值模拟所需的粘性阻力系数和惯性阻力系数,对反应器内的流动特性进行数值模拟,并将其结果与实验数据对比,最大误差为8.6%。将关系式应用于具有不同结构(蜂窝状和斜板状)催化剂的脱硝反应器中,计算结果与文献值趋势基本一致,最大误差为12.9%。     

SIMULATION AND EXPERIMENTAL IMPLEMENTATION OF A NEURAL-NETWORK-BASED INTERNAL-MODEL CONTROL STRATEGY ON A REACTOR SYSTEM

The use of inverse-model-based control strategy for nonlinear system has been increasing lately. However it is hampered by the difficulty in obtaining the inverse of nonlinear systems analytically. Since neural networks has the ability to model such inverses, it has become a viable alternative. Although many simulations using neural network inverse models For controls have been reported recently, no actual experimental application has been reported on a reactor system. In this paper we describe a novel experimental application of a neural network inverse-model based control method on a partially simulated pilot plant reactor, exhibiting steady state parametric sensitivity and designed to test the use of such nonlinear algorithms. The implementation involved the control of the reactor temperature under set point changes, disturbance rejection and set point regulation with plant/model mismatches. Simulation tests on the model of the system were also carried out to enable better design of the neural network models and to highlight the differences between simulation and actual online results. The online implementation results obtained were sufficient to demonstrate the capability of applying these neural-network-based control methods in real systems.     

油浸式电抗器用阻尼橡胶材料压缩阻尼特性与本构模型

通过对油浸式电抗器器身-油箱间阻尼橡胶材料进行轴向压缩滞回性能试验,研究了其阻尼特性;依据实验数据并结合ABAQUS数值模拟结果,校正了适用于油浸式电抗器器身-油箱间阻尼橡胶材料的Mooney-Rivlin和Yeoh本构模型参数。结果表明,相比普通抗振橡胶试件,丁腈橡胶试件的轴向压缩刚度更大,滞回曲线更饱满,耗能能力更强;Mooney-Rivlin模型和Yeoh模型均适用于NBR试件的小变形和大变形行为,其中Mooney-Rivlin模型参数和Yeoh模型参数计算结果最大误差分别为-11.31%和-12.21%。     

分布孔大小对环流反应器内流动影响数值模拟

采用k-ε二方程模型和欧拉多相流模型,对一种气升式环流反应器内的湍流气液二相流进行了全尺寸的数值模拟研究,考察了采用具有不同大小分布孔气体分布器时反应器内气含率和流速分布的细节。模拟结果表明采用小分布孔的反应器内的平均气含率较高,气液二相接触效果较好,对于反应过程有利。计算所得的整体气含率与实测的整体气含率进行了对比,吻合较好。     

外循环喷雾式乙氧基化反应器的数学模型与模拟

对半间歇操作外循环喷雾式乙氧基化反应器的数学模型与模拟进行了研究,分析了反应器的特性,建立了同时考虑气液传质、动力学、汽液平衡、反应体积变化和惰性气氮气影响的反应器的数学模型和数值模拟算法。以合成聚乙二醇为例,模拟得到反应器中温度、压力、环氧乙烷浓度及乙氧基化产物随时间和空间位置的分布。模拟结果同工业操作数据进行了比较,结果表明了模型的可靠性。     

Modeling and scale-up simulation of U-tube ozone oxidation reactor for treating drinking water

In the present study, we developed a novel simulation model of the U-tube reactor for treating drinking water, which is composed of a coaxial inner tube serving as an efficient concurrent down-flow ozone dissolver and an outer column carrying out reactions between ozone and organic substances including odorous materials (2-methylisoborneol: 2-MIB) dissolved in the raw water. We assume that the U-tube is composed of a plug flow section (inner tube) followed by a tanks-in-series section (outer bubble column) and take into account the effect of the hydrostatic pressurization on the flow and absorption equilibrium for the gaseous components including ozone and other inactive species in developing the mass balance models. An algorithm is constructed of the differential multiple mass balance equations for the inner tube sections and multiple difference mass balance equations in the series tanks in the outer column section to enable the scale-up from a pilot plant to a full-scale plant. The gas holdup and gas-liquid mass transfer coefficient were measured in a model reactor and correlated for the use of the simulation calculation. Available literature data and correlations on the rates of reactions between ozone and organic substances including odorous material 2-MIB, gas-liquid equilibrium for active and inactive gases and axial fluid mixing properties are also incorporated in the simulation calculation. The simulation results well explained the available data of the ozone absorption efficiency and the removal efficiency of the odorous material in a pilot U-tube reactor. The simulation procedure was also successfully extended to verify the performance of a full-scale U-tube reactor. It is shown that the ozone absorption is practically a single function of the gas/liquid ratio while the removal efficiency of the odorous material is a single function of the ozone dose for a specified U-tube configuration.     

优化瓶片转产过渡时间的数学模型

通过对五釜聚酯流程中的浆料调配槽、第一酯化反应器、第二酯化反应器建立数学模型,可得出各反应釜出口IPA含量-时间变化关系,可理论推导出最优超调时间。在此基础上,运用EXCEL数学公式计算功能编制相关计算工具,通过设定超调时间反向计算IPA含量,进而方便快速寻找最优转产超调时间。     

Modeling of Multistage Bubble Column Reactors for Oxidation Reaction

In this work, a mathematical model based on axial dispersion has been suggested to simulate the behavior of a multistage bubble column reactor. A six‐stage pilot‐scale reactor with an inner diameter of 0.35 m and a height of 12 m was used for hydrogen peroxide production through the direct oxidation of isopropyl alcohol at isothermal condition. Steady‐state and dynamic simulations were performed to predict the concentration of all the reactants in gas and liquid phases. It was observed that for steady state‐conditions the simulation results were consistent with the experimental results. Dynamic models involving liquid back‐mixing can be used for the simulation of start‐up, shut‐down or transition operations in this kind of a rector.     

Simulation and Analysis of a Tubular Fixed‐Bed Fischer‐Tropsch Synthesis Reactor with Co‐Based Catalyst

A two‐dimensional pseudohomogeneous reactor model is proposed to simulate the performance of fixed‐bed Fischer‐Tropsch synthesis (FTS) reactors by lumped thought. A CO consumption kinetics equation and a carbon chain growth probability model were incorporated into the reactor model. The model equations discretized by a two‐dimensional orthogonal collocation method were solved by the Broyden method. Concentration and temperature profiles were obtained. The validity of the reactor model against the pilot plant test data was investigated. Satisfactory agreements between model prediction values and experiment results were obtained. Further simulations were carried out to investigate the effect of operating conditions on the reaction behavior of the fixed‐bed FTS reactor.     

钯催化剂2-乙基蒽醌加氢滴流床反应器模拟

引　言过氧化氢 (H2 O2 )是一种性能优良的氧化剂 ,因其以水为还原产物而备受绿色化学与化工研究领域广泛关注 .以过氧化氢为氧化剂的氧化过程具有反应条件温和、选择性高、无污染等优点 ,因此被广泛用于造纸、印染、化学合成、环境保护和半导体等工业领域 .其应用前景十分广阔     

Numerical simulation of horizontal jet penetration in a three-dimensional fluidized bed

The introduction of reactant gas as a jet into a fluidized bed chemical reactor is often encountered in various industrial applications. Understanding the hydrodynamics of the gas and solid flow resulting from the gas jet can have considerable significance in improving the reactor design and process optimization. In this work, a three-dimensional numerical simulation of a single horizontal gas jet into a cylindrical gas-solid fluidized bed of laboratory scale is conducted. A scaled drag model is proposed and implemented into the simulation of a fluidized bed of FCC particles. The gas and particles flow in the fluidized bed is investigated by analyzing the transient simulation results. The jet penetration lengths of different jet velocities have been obtained and compared with published experimental data as well as with predictions of empirical correlations. The predictions by several empirical correlations are discussed. A good agreement between the numerical simulation and experimental results has been achieved.