提升管催化裂化反应过程数值模拟

在气固两相流体动力学模型的基础上.采用基于机理反应的FCC14集总模型.考虑了反应温度、局部固体浓度变化以及流动对反应的影响,建立了重油流化催化裂化流动一一反应耦合模型.模拟结果表明,重油裂化反应主要发生在喷嘴附近区域,在喷嘴附近已经有45%的重油转化为汽油和柴油.随着距离喷嘴位置的增加,汽油产率逐渐上升,但距离喷嘴位置12m以后,汽油产率基本保持不变.从汽油组成变化来看,在整个提升管内汽油中烯烃含量一直处于下降趋势,由喷嘴区域的60wt%降低到提升管出口位置的42wt%左右.汽油烷烃含量一直呈增加趋势,而汽油中环烷烃含量和芳烃含量变化较小.     

Simulation of UV photoreactor for water disinfection in Eulerian framework

A novel computational fluid dynamic (CFD) modeling procedure was developed in order to simulate ultraviolet (UV) photoreactors in the Eulerian framework. In this procedure, the governing equations of radiation distribution, mass conservation, momentum conservation, and species mass conservation are solved together in order to determine the radiant energy field, velocity field, and the concentration profile of microorganisms at steady state conditions. The general method presented can be employed to derive the volumetric inactivation rate and the theoretical efficiency of a UV photoreactor. The integrated CFD model of UV photoreactor performance was successfully evaluated with experimental biodosimetry results. The verified procedure can be applied to the simulation and design optimization of UV photoreactors with different geometries and operating conditions.     

Steady-state simulation of Fluid Catalytic Cracking riser reactors using a decoupled solution method with feedback of the cracking reactions on the flow

A method is proposed to simulate reactive flow, fully taking into account the effect of the reactions on the flow. Operator splitting is used to separate the computation of convection and reaction. A fast solver for mildly stiff ordinary differential equations and parallelization of the reaction term evaluation have been implemented to reduce the CPU time. The proposed method is applied to the steady-state, two-phase gas–solid simulation of a Fluid Catalytic Cracking riser reactor. A relatively simple kinetic model with four lumped components is used to demonstrate the feasibility of the method. The results show that the method is able to handle reactive flow with significant feedback of the reactions on the flow.     

Verbesserte Simulation der Temperaturentwicklung von HT‐PEM‐Brennstoffzellen zur Effizienzsteigerung

Identification and prevention of large temperature gradients can extend the lifespan of fuel cells. Estimating the temperature distribution during operation is difficult because of the complex processes in the cell. Therefore, even with large computational power only small and simple flow field geometries can be calculated yet. The integration of a new mathematical formulation in commercial simulation software allows calculation and assessment of complex geometries in order to increase their efficiency and lifespan.     

Transient three-dimensional simulations of a catalytic combustion monolith using detailed models for heterogeneous and homogeneous reactions and transport phenomena

The application of a newly developed computational tool, DETCHEM^MONOLITH, for the transient two- and three-dimensional simulation of catalytic combustion monoliths is presented. The simulation is based on the coupling of a transient 2D/3D heat balance of the solid monolith structure with steady-state calculations of the reactive flow in a representative number of channels. The two-dimensional single-channel model uses a boundary-layer approximation including detailed models for heterogeneous and homogeneous reactions as well as transport phenomena. As an example, the computational tool is applied to study the hydrogen-assisted catalytic combustion of methane in a platinum-coated honeycomb monolith.     

Katalysatoren des Leuna Werkes 1945 – 1991: Von der Empirie zur Wissenschaft. Teil II: Reformier‐ und Isomerisierungskatalysatoren

Subject of the first part of this publication series was the development and manufacturing of technical catalysts within the Leuna Werke company from 1921 – 1945. Part II as well as part III and IV will focus on this topic as well, looking at the years from 1945 to 1991. Within this timeframe, a high‐performing research and development as well as an efficient production line for new catalysts was implemented, facing a new and challenging macroeconomic environment. In recognition of the fact that the first newly developed catalyst after WW II was a reforming catalyst, this article will describe the development path of this group of catalysts as well as the closely related isomerization catalysts.     

甲烷化固定床反应器床层反应过程与场分布数值模拟

以甲烷化固定床反应器床层为研究对象,使用CFD软件编写CEL语言,将甲烷化反应以源项的形式添加到模拟过程中,对比多孔介质模型与填充球床模型模拟的准确性,选择填充球床模型进行模拟,获得了床层的速度场、组分浓度以及温度场分布。研究结果表明:与填充球床模型比较,由于多孔介质模型简化了内部的孔隙结构,使用其对固定床反应器进行模拟时存在较大误差,其中出口温度模拟值比实测值低13.6%;固定床的壁效应使近壁面处10%的圆环面积上通过20%的质量流量,进而显著影响床层内部场的分布;床层内部轴向温升显著,从250℃ 升高到 685℃,同时径向温度分布不均,变化范围在20～40℃内波动。