伴有平衡反应的分离过程的数学模拟——(Ⅱ)催化精馏塔的模拟计算

提出了平衡反应的非均相催化反应精馏过程的微分数学模型。应用多目标打靶法和 Newtor-Raphson 迭代对模型方程进行了求解。本算法应用于非理想系统,反应动力学未知的快速可逆反应过程。可求得沿塔最大转化率和平衡浓度分布。应用本算法对 MTBE 的催化反应过程进行了模拟计算,能快速稳定收敛。计算结果与文献数据进行比较,表现出良好的一致性。     

Kinetic modelling of the catalytic conversion of synthesis gas

A kinetic study for the one-step conversion of synthesis gas to gasoline on a ZnO–Cr₂O₃–ZSM-5 catalyst is described. On this catalyst, three reactions are involved in the overall transformation of synthesis gas: the methanol synthesis, the conversion of methanol to hydrocarbons and the water–gas shift reaction. Under the operating conditions selected for the study, it was found that the water–gas shift was at equilibrium and the methanol was completely converted to hydrocarbons. Consequently, it was postulated that the kinetics of the limiting reaction step, the methanol synthesis on the ZnO–Cr₂O₃ component, was the one that controls the overall reaction rate. Three kinetic model equations describing the rate of synthesis gas conversion on the bifunctional catalyst, were considered to fit the data of the experimental runs performed in a Berty well-mixed reactor. Those equations were derived under very special conditions where the methanol decomposition term could be neglected. It was also observed that in the kinetic equations a term involving the fugacity of CO₂ was required to predict the rate properly. The catalyst deactivation was also taken into account in the analysis.     

Reaction kinetics study of asymmetric polymer-polymer interface

In this study, the reaction kinetics of asymmetric polymer-polymer interface was experimentally and theoretically studied. A new rheological method correlating the change of rheological property of reactive system with the conversion of the in situ formed copolymers was applied to study the reaction kinetics of PBT/epoxy reactive system. Then, the new method was proved to be useful by comparing its results with that obtained from the conventional endgroup determination method. Moreover, the conversion of PBT/epoxy reactive system from rheological method could be well fitted by the numerical analysis, from which the kinetic constant and the diffusion constant of epoxy in PBT could be determined simultaneously.     

氧化铝上吸附平衡与动力学的分形特性

在实验测定氧化铝吸附氮气的平衡和动力学过程的基础上 ,由平衡数据得到分形维数 ,对动力学结果分别用欧氏几何和分形几何的动力学模型进行处理 ,比较两种方法得到的扩散系数之间的差别。结果表明 :粉状氧化铝的分形维数为 2 .12 ;采用分形动力学模型得到的扩散系数同欧氏几何扩散模型的结果不一样 ,扩散系数不随浓度的变化而改变 ;而欧氏几何扩散模型中的扩散系数随浓度变化发生改变 ,且变化符合Darken关系     

Kinetics of and catalyst decay accompanying the gas phase rearrangement of cyclohexanone-oxime over a hy ultrastable zeolite

The kinetics of the rearrangement of cyclohexanone-oxime has been studied in a fixed bed, glass tubular reactor at atmospheric pressure and temperatures of 240, 270, 300 and 335°C, using ultrastable HY zeolite catalyst. Several kinetic models, including the Langmuir-Hinshelwood type, have been derived and the best statistical fit has been obtained with a pseudo-first order kinetic equation. The rate constants and activation energies for the formation of the products caprolactam, cyclohexanone and 5-cyanopent-l-ene have been calculated. Based on the evolution of the selectivity with temperature, and the I.R. spectra of the poisoned catalyst, different decay models have been deduced and discussed.     

大冶硫酸四系列干吸塔结构特点

以干燥塔为例，介绍大冶公司硫酸四系列干吸塔的结构特点。除捕沫层简体及出气管为316L不锈钢外，其余塔体均为碳钢内衬瓷砖结构。塔底为球形底，中心排酸。采用槽管式分酸器，分酸点密度为43个/m^2，设可调闸板以保证各槽酸量均匀；闸板外设置带孔板的分布板，以消除进口酸的冲击，保证槽内酸液面平稳。比较了该塔与常规塔的不同之处，强调了设备节点的优化设计。     

棉籽油间歇式酯交换反应动力学的研究

生物柴油(棉籽油甲酯)可以由棉籽油与甲醇在催化剂KOH存在下通过酯交换反应制得。故对棉籽油间歇式酯交换反应动力学进行了研究,并考察了反应温度和催化剂浓度对产物棉籽油甲酯浓度的影响。用液相色谱法分析棉籽油的组成;用气相色谱法分析产物中棉籽油甲酯的含量。由实验数据绘制的动力学曲线得到酯交换反应在开始阶段为准二级反应,以后紧接转为一级反应和零级反应,与文献报导的棕榈油酯交换反应动力学结果一致。由实验数据求出酯交换反应在开始阶段的动力学参数,35℃、45℃时的反应速率常数分别为0.9179Lmol-1min-1和1.049Lmol-1min-1,酯交换反应的活化能为10.88kJmol-1。根据实验结果得到棉籽油酯交换反应的最佳反应温度为45℃,最佳催化剂为1.1%KOH。     

抗氧剂3114合成反应热力学和动力学的研究

研究了常温溶剂法合成抗氧剂3114反应热力学和动力学过程。控制温度在117±2℃,研究结果表明,反应是零级反应,反应速率常数k=1.91×10-3/min,反应的平衡常数K=138.4(mol/L)-6,反应活化能Ea=1366.2J/mol。     

Combustion of single char particles in a turbulent fluidized bed

The combustion of single bituminous char particles (4-12 mm diameter) was studied in a turbulent fluidized bed operated at 1098 K using air as the fluidising medium. Results indicated that particles burn with constant density following a shrinking sphere model. Burning rates are much higher than those observed in a bubbling fluidized bed. The rate of transfer of oxygen to the particle surface is also higher than that observed in bubbling beds. A model is proposed to calculate the Sherwood numbers of the burning carbon particles. Experimental values of the Sherwood numbers agree well with those predicted from the model.     

Agglomeration kinetics of coking coal particles during the softening phase

Agglomeration kinetics under thermal conditions describe the structure and formation of larger bodies, termed agglomerates from coal particles, as a preliminary phase of semi-coke formation. Knowledge on particle adhesion characteristics are of particular importance for determining the strength as well as the structure of the agglomerates. Several adhesive forces acting during the adhesion mechanism may be roughly subdivided into bonding with and bonding without material bridges. The purpose of the present work was to investigate the adhesion mechanism; the formation and growth in time of the bonding neck between two particles, as well as the change of functional correlation with other parameters, i.e. temperature and coal quality. Experimental investigation of the kinetics of agglomeration was carried out using apparatus in which a coal layer was heated by radiation in an atmosphere of flowing nitrogen. Camera recordings allowed quantitative assessment of the growth of the bonding neck with time, and additionally the dependence of the parameters on temperature and coal quality could be determined. The evaluation of the tests yielded clear indications supporting the assumption that increased adhesion of two viscous spheres under the effect of surface tension can be used as a physico-chemical model for the agglomeration of two coal particles under thermal conditions.