Applications of CFD Simulations on Chemical Processing Equipment Designs

The objective of this work is to achieve process intensification by seeking optimal equipment design with CFD investigations. In this work, two projects on chemical equipment design have been discussed. The first project is on design and optimization of fractal distributor in a novel ion-exchanger. Flow distributors are adopted extensively by chemical industry to distribute an incoming process stream uniformly to the downstream equipment. Currently, the performance of chemical equipment installed with conventional distributor is severely undermined due to poor flow distribution. For conventional distributors such as spray nozzle distributors, their design concept is based on maintaining very high pressure drop across the whole device with very little opening areas through orifices. Fractal distributors can achieve high outlet densities with low pressure drop due to their inherent self-similarity feature. To investigate the performance of fractal distributor, a novel ion-exchanger equipped with fractal distributor was proposed and manufactured. With comparison against conventional distributor, fractal distributor is proven to be able to offer much better flow distribution inside ion-exchanger by both CFD and experimental investigations. To seek optimal performance, the design space of fractal distributor has been explored with CFD studies. The influence of key design parameters such as channel aspect ratio was investigated and fractal distributor with “deep and narrow” channels were found to achieve superior performance. While conducting large scale design explorations, automation tools were developed to handle massive number of study cases. The second project focuses on design explorations of a novel oil-water separator. The flow pattern was investigated first with single phase studies. An improved design was proposed with draft tube diameter ratio of 0.6 and a larger twisting angle of impeller. The new impeller design was shown to have better separation efficiency from experiments. Later, the design has been studied with multiphase simulation with population balance model. With the challenge of lacking available kernels in low Reynolds number flow, a new coalesce kernel was proposed. The model offers as a comprehensive tool to understand flow pattern and phase separation process inside the device

Applications of CFD Simulations on Fractal Fluid Distributor

Since its emergence in 1970s, process intensification has been attracting extensive research interests from both academic and industrial societies over the years. One good example of process intensification in chemical industry is the optimization of flow distributors. In many chemical processes, the uniformity of flow distributions plays the key role in determining the overall efficiency. Conventional distributors rely on high pressure drop to achieve acceptable flow distribution. With scaling symmetry from fractal, fractal distributors can handle fluid distribution much better than conventional distributors. With the rapid development of computation power and numerical simulation algorithms, Computer Fluid Dynamics (CFD) provides us a better understanding of physics in chemical industries. This thesis is seeking to achieve process intensification by designing a novel ion-exchanger with fractal distributor. Residence time distribution test has been conducted to study the design of fractal distributor. CFD simulations help to gain insights on fluid flow inside the device and offers optimization on fractal distributor for flow distribution uniformity. Coefficient of Variation has been used to estimate distributor performance