CFD Modelling of Chemical Reaction Systems in Jacketed Stirred Tank Reactors

夹套搅拌槽反应器（STRs）的建模通常假设反应器内的完美混合导致均匀的浓度/温度分布和传热流体通过夹套的均匀流动。我们之前在中试STR中对流体力学和夹套流体与反应器内容物之间的共轭传热进行的计算流体力学（CFD）研究表明，完美混合和均匀流动是不切实际的假设。该项目的主要目标是通过将反应动力学整合到cfd -传热模型中，为精细化工和制药行业的相关反应系统开发一个有机合成反应过程模型。有机化合物的化学合成通常是复杂的，涉及多个竞争反应和转化/选择性。产物分布严重依赖于反应器的流体动力学、混合和传热特性，特别是大型str。任何不均匀的瞬态水动力条件都会导致反应条件在空间和时间上的变化，从而产生不希望的副产物并降低产量。从实验室到中试工厂再到生产规模，这些变化因str的大小而有很大不同。最后，在许多情况下，活性成分通过结晶从反应器内容物中分离出来，副产物的存在会对晶体的质量产生不利影响。甚至结晶步骤也会受到容器内普遍存在的任何不均匀和瞬态流体动力条件以及副产品的存在的不利影响。因此，通过改进实验室、中试工厂和工业反应器的设计和有效操作，最大限度地减少副产品的形成是至关重要的。在反应器和结晶过程中发生的物理现象的第一性原理模型的应用可以促进这一点。除了建模之外，还将在实验室规模的str （0.5 - 5 L）中进行实验，以确定反应动力学并收集模型验证的过程数据。这种全面的模型将成为“建模设计”方法的一个极其强大的工具，它可以准确地预测反应产物分布，促进反应堆设计，扩大和优化运行条件，并通过探索导致热失控的过程条件来确定安全的运行包络。该模型还可以用于进行计算实验，以最大限度地减少大规模实际实验的数量，这些实验本质上是不安全的，昂贵的和耗时的。

Modelling of jacketed stirred tank reactors (STRs) generally assumes perfect mixing within the reactor leading to uniform concentration/temperature distributions and uniform flow of the heat transfer fluid through the jacket. Our previous computational fluid dynamics (CFD) study of hydrodynamics and conjugate heat transfer between the jacket fluid and the reactor contents in a pilot-scale STR revealed that perfect mixing and uniform flow are unrealistic assumptions. The main objective of this project is to develop an organic synthesis reaction process model for relevant reaction systems in the fine chemicals and pharmaceutical industries via integration of reaction kinetics into the CFD-heat transfer model. Chemical synthesis of organic compounds is often complex involving multiple competitive reactions and conversion/selectivity. The product distributions are critically dependent on the hydrodynamics, mixing and heat transfer characteristics of the reactor and particularly for large-scale STRs. Any inhomogeneous and transient hydrodynamic conditions prevailing will result in spatial and temporal variations in reaction conditions which can generate undesired by-products and reduce yield. These variations are quite different depending upon the size of the STRs from laboratory to pilot plant to manufacturing scales. Finally, in many instances, the active ingredients are isolated from the reactor contents via crystallisation and the presence of by-products can adversely affect the quality of crystals. Even the crystallisation steps can be influenced adversely by any inhomogeneous and transient hydrodynamic conditions prevailing within vessel and the presence of by-products. It is therefore of paramount importance to minimise by-products formation through improved design and efficient operation of laboratory, pilot plant and industrial reactors. Application of first principles models of the physical phenomena occurring in the reactor and during the crystallisation can facilitate this. In addition to the modelling, experiments will be carried out in laboratory scale STRs (0.5 - 5 L) to determine reaction kinetics and for collection of process data for model validation. This comprehensive model will be an extremely powerful tool for the "design by modelling" approach, which can predict accurately reaction product distributions and facilitate reactor design, scale up and optimision of operating conditions, and determining a safe operational envelope via exploring process conditions leading to thermal runaways. The model can also be used to conduct computational experiments to minimise the number of real experiments in large scale sizes which are inherently unsafe, costly and time consuming.