醋酸甲酯水解动力学及催化剂包效率因子的测定

测定了用SK—1A离子交换树脂催化的醋酸甲酯水解的宏观动力学,设计了能反映流体在催化剂包中实际流动情况的循环式间歇恒温反应流程,测定了醋酸甲酯水解催化精馏中试塔所用催化剂捆扎包的效率因子,并得到效率因子与液体流量和进料水酯摩尔比的关联式．     

APPROXIMATE EFFECTIVENESS FACTOR ESTIMATION FOR WAVE SHELL CATALYST

The estimation of effectiveness factor for the case of wave shell catalyst is attempted through an approximated procedure developed by the authors for other kind of catalytic pellets. It is shown that the approximate scheme can be used even with this kind of important catalysts and that the results so obtained are very accurate. The analysis is only restricted to the case of single reaction although it can be used even for those cases where non-isothermal conditions could prevail. The estimation avoid the solution of the governing mass and heat balance differential equations by numerical procedures. Finally a set of algebraic equations must be solved through an iterative scheme which is illustrated for the case of isothermal systems.     

二级可逆反应等温催化剂有效因子的简化计算

将等效温度法的应用拓宽至二级可逆反应,推导出球型等温催化剂有效因子的近似解析解,采用一氧化碳变换反应宏观动力学结果加以验证,证明该法简便可靠。     

A LINEAR APPROXIMATION METHOD TO EVALUATE ISOTHERMAL EFFECTIVENESS FACTORS

A linear approximation method to estimate effectiveness factors for isothermal catalytic pellets has been developed. The method is based on the Taylor series expansion of the reaction rate expression above the surface particle concentration for the key component. The application of the method to reaction systems with nonlinear kinetics yields simple analytic expressions for the effectiveness factor equivalent to that found for first order irreversible reaction. The effectiveness factor expressions obtained depend of one parameter analogous to the Thiele modulus. In this work we report the results obtained for a Monod type kinetic equation. The effectiveness factors predicted are compared with those obtained from the numerical solution of the exact boundary value problem. The error is negligible at low Thiele moduli and as this parameter is increased the error grows, reaching an asymptotic value at high Thiele moduli. For the example presented, the error is below 10%. The available results indicate that nonlinear cases such as Langmuir-Hinshelwood type of equations can be treated successfully using the method developed.     

THE EFFECTIVENESS FACTORS FOR VARIOUS SIZE DISTRIBUTIONS OF CATALYST PARTICLES

In general, catalyst beds are made up of a size distribution of particles. Often the distribution of particle sizes can be well represented by either a rectangular or triangular size distribution. This paper shows that characteristic mean particle sizes can be defined for both the rectangular and triangular distributions such that the effectiveness factor based on this single particle size lies close to the effectiveness factor for the distribution. Thus, by using the correct mean particle size a quick and reasonably accurate evaluation of the effectiveness factor for the particle size distribution can be made.     

THE EFFECTIVENESS FACTORS FOR VARIOUS SIZE DISTRIBUTIONS OF CATALYST PARTICLES

In general, catalyst beds are made up of a size distribution of particles. Often the distribution of particle sizes can be well represented by either a rectangular or triangular size distribution. This paper shows that characteristic mean particle sizes can be defined for both the rectangular and triangular distributions such that the effectiveness factor based on this single particle size lies close to the effectiveness factor for the distribution. Thus, by using the correct mean particle size a quick and reasonably accurate evaluation of the effectiveness factor for the particle size distribution can be made.     

硫中毒状态下B108中变催化剂效率因子的研究

硫中毒状态下铁铬系变换催化剂效率因子的研究,迄今尚未见报道。本文根据水煤气变换反应的特点,以均匀中毒假设为前提,建立多组分扩散模型描述稳态情形下,500ppm 硫化氢气相浓度时各反应组分在等温原粒度催化剂中的浓度分布。所有6个实验条件下的效率因子计算机求解结果表明,模型与实验值符合良好。从浓度分布和死区两方面解释了相同条件下,宏观反应速率受硫化氢影响较本征速率小38.30%的原因。研究表明,采用的实验手段是可行的,所建立的模型可用于工业过程的分析。     

ANALYSIS OF THE PERFORMANCE OF NON-UNIFORMLY ACTIVE CATALYST PELLETS FOR A NON-ISOTHERMAL SERIES REACTION

An analysis of the influence of the non-uniform distribution of the active species in a catalyst pellet on the effectiveness factor and selectivity for the case of a series non-isothermal reaction is carried out. The case in which the desired reaction has a lower activation energy than the undesired reaction is considered. The effect of different reaction parameters on the selectivity for a single pellet is studied, and the optimum activity distribution is determined for high values of Thiele modulus. It is shown that temperature gradients within the pellet have a detrimental effect on local and overall selectivity and that these gradients are a strong function of the distribution of catalytically active material within the pellet.     

污水处理管锥形填充床特性研究与分析

填料是生物接触氧化反应器的核心部分,本文从传统填料的优缺点入手,分析了管锥形填料的结构和特性,并对管锥形填充床对污水的处理性能进行了试验验证。试验结果表明,针对模拟废水处理,负荷在2.3～8.0kgBOD5/m3.d范围内(比一般生物滤池负荷高10倍以上),都达到很高的处理效果;HRT为1h时,使污水的COD值由400mg/L降至37mg/L,去除率达92%;出水SS为3mg/L,大大降低二沉池的停留时间,节约投资。     

造粒系统对尼龙66树脂粒子形状的影响

介绍了尼龙66造粒过程中较为常见的几种异常粒子的形状,并对这些异常粒子形成的原因进行分析.发现动、定刀间隙,上、下牵伸辊间隙,切粒水温度、流量,出料压力,切刀与牵伸辊牵引速度配合等是影响粒子外观的主要因素.     

乙酸甲酯水解催化精馏过程催化剂包内的传质模型(Ⅱ)效率因子的测定与计算

建立了能较客观反映流体在催化剂包内流动状况的循环式间歇恒温反应装置 ,测定了不同催化剂包尺寸和不同液体喷淋密度下的乙酸甲酯水解宏观动力学和表观速率常数 ,估算了催化剂包内径向有效扩散系数约为 9× 10 ^-8m² ·s^-1。应用本文 (Ⅰ )报的传质模型计算了催化剂包效率因子 ,与实验结果吻合较好 ,其平均偏差为 3 2 % ,最大偏差为 13 7%。     

EFFECT OF PORE DIFFUSION ON DEACTIVATING RATES OF SECOND ORDER REACTION

The research and development of catalysts, the design and operation of catalytic reactors are complicated by the phenomenon of catalyst deactivation which is affected by various factors. In this paper, the effect of internal mass transfer resistance in the second order catalytic reaction system of uniform independent deactivation on both reaction and deactivation rates of straight cylindrical pore model has been discussed. In addition, the quantitative relations between effectiveness factor and Thiele modulus in second order reaction and first order deactivation system have been correlated     

煤粉碎过程中颗粒形状的分形特征

应用分形几何学的方法对煤粉碎过程中颗粒的不规则程度进行度量．研究结果表明,不同组成的颗粒其颗粒形状分维ＤＰ不同,矿物质组成的颗粒形状分维最大,其次是壳质组颗粒,四组分颗粒居第三,其它颗粒的形状分维大致相似．颗粒形状分维具有随时间不变性的特点,表现为相同组成的颗粒的形状分维基本不随粉碎时间发生变化．导致这一现象的根本原因是不同的煤显微组分的力学性质及微裂纹的分布不同,而对于同一组分来说,其微裂纹的分布又具有自相似性．     

C207甲醇合成铜基催化剂本征失活动力学

一、前言工业生产中广泛使用的甲醇合成铜基催化剂具有活性高、选择性好、起始活性温度低等优点。但铜基催化剂抗毒性能差,影响了它的使用寿命。铜基催化剂的主要毒物是原料气中所含的 H_2S。铜基催化剂 H_2S 中毒失活研究,国内未见报道,美国的 Wood 等和 Rdvodic 等作过一些研究。本文通过对国产 C207铜基催化剂硫化氢中毒失活动力学的研究,建立描述活性衰退过程的失活动力学方程,得到活性与硫化     

1D and 2D simulations of partially wetted catalyst particles: A focus on heat transfer limitations

Hydrodynamics and transport phenomena inside Trickle Bed Reactors are strongly modified when superficial liquid velocity is not sufficient to insure a perfect wetting of catalyst particles. For this reason, the impact of partial wetting on catalyst effectiveness has been widely studied in past, in case of isothermal reactions. Heat transfer limitations, inside or outside catalyst particles, have also been investigated, but only in case of total wetting.In the present study, the effect of partial wetting is quantified numerically for various kinetics, mass and heat transfer limitations. When possible, an analogy is proposed between 1D and 2D models of particles. Robust rules are proposed to take into account for partial wetting in 1D-radial models of particles.The case of partial evaporation inside catalyst pores is also studied. Evaporation phenomena is approximated following a simple approach. Performed calculations show that the effect of partial wetting can affect very strongly catalyst effectiveness factors, especially in case of evaporation in the pores. The use of 1D approximations gives a good prediction of the global catalyst efficiency, as far as boundary conditions are symmetric between heat and mass transfer. Otherwise, 1D models are not relevant anymore.     

用两个形状指数表征粉煤灰颗粒形貌的研究

引用两个形状指数表征颗粒形状的概念,即先将颗粒形状近似为椭圆,再将椭圆图像分离:以圆为基准的颗粒宏观形状指数δ;以光滑椭圆为基准的颗粒轮廓凹凸度,即微观形状指数ζ。分析和发展了近似椭圆模型。并运用图像分析仪对粉煤灰、水泥样品进行实验。结果表明,粉煤灰颗粒的两个形状指数δ和ζ都大于水泥颗粒。证明粉煤灰颗粒的球形度、表面光滑度优于水泥,而且,随着粒径增大,δ和ζ呈下降趋势,表明磨制颗粒越粗。(?)粒形状越不规则。文中还运用近似椭圆模型再现了颗粒的模拟图像。     

颗粒形貌对水泥性能的影响

以多组水泥样品为对象,在控制其颗粒级配、比表面积基本一致的条件下,利用扫描电镜等测试手段,研究水泥颗粒形貌改善对水泥性能及孔结构等的影响。结果表明：水泥颗粒形貌改善后,水泥胶砂流动度随水泥颗粒形貌的改善而不断增大。水泥凝结时间略有延长,水泥颗粒粉状物料堆积状况更趋密实。水泥胶砂试体中总孔隙率降低,中位孔径及平均孔径减小。在相同砂浆流动度下,颗粒形式改善后水泥的圆形系数由0．67提高至0．72,水灰比可减少8％,各龄期水泥抗压强度均提高20％以上。在相同水灰比下,圆形系数的平均值由0．65提高至0．73,水泥中后期抗压强度平均增长10％～12％。     

焦炭颗粒气化表面积变化结构因子的研究

孔结构及其变化对焦炭颗粒的气化行为有重要的影响,如颗粒的比表面积变化与反应速率有相同的变化趋势.推导得出了一个新的反映焦炭颗粒气化过程中表面积变化的结构因子表达式,该结构因子显示表面积的变化趋势与初始孔隙率有重要的关系.随着初始孔隙率的不同,比表面积或是随转化率减小,或是出现最大值.这一特征与随机孔模型很相象.与随机孔模型作了对比研究,发现所提出的该表达式模型除了形式简单外,还具有物理意义明确、精度好的特点.     

管内湍流的摩擦系数方程

本文提出了计算流体在水力学光滑管与粗糙管内湍流流动时摩擦系数的两个显式方程,并且将此两式与Colebrook式(4)、Churchill式(13)和其他人提出的式(11)、(12)、(14)、(16)、(15)进行比较,同时都以Murin's的实测数据进行检验,结果表明本文提出的两个公式简便易用,具有足够的准确度。