Equipment Scale-up and Modelling

Process scale microfiltration usually employs several membrane modules operating in parallel in order to achieve the desired permeate flow. Preliminary testing with a single module is undertaken easily and scale-up by means of proportioning the areas and flows may be sufhcient for process design. There are, however, important choices regarding the optimum method of operation  

2) Multiple pass with suspension thickening between batches 

During single-pass operation the membrane area required at each stage can be calculated firom the flux and feed rates via a mass balance. In muh le-pass thick iing mode, with continuous feed, the filtration loop can be considered as being a well mixed system and the following mass balance results  

During-muh le pass feed and bleed operation the flux rate is likely to remain constant, after an initial period of decay, and the concentration in the system is related to the permeate flux rate, membrane area, bleed rate and feed concentration only  

---

After the CFD analysis and scale model studies are complete, the SCR unit design is done. Scale up and fabrication of the unit follows. The SCR catalyst modules and other equipment are produced. SCR catalyst for an FCCU is delivered as modules to reduce the number of crane lifts to load the reactor. The individual catalyst cubes... 

With regard to equipment design, it is critically important to work closely with equipment vendors or others experienced in scale-up. Published models should be considered as tools for an initial engineering design only, and a not as a replacement for pilot testing and consulting with those experienced in extractor design. 

Rosen,A.M. and Krylov,V.S. "Theory of scaling-up and hydro-dynamic modeling of industrial mass transfer equipment". Chem. Engng.J. 71 (1974) 85. 

Macromixing is the process whereby parts of a fluid having different histories come into contact and mix-up on a macroscopic scale. It is thus a consequence of the macroscopic hydrodynamic pattern. The development of powerful computer codes make it possible now to determine the average velocity pattern in any kind of equipment, at least in single phase newtonian fluids. This probably won t eliminate methods based on the characterization of complex flow by internal age distributions and residence time distributions (RTD), which can be determined with tracers. Such methods have proven their efficiency for building up flow models well adapted to scale up and to calculation of chemical conversion -... 

Section 12-2 deals with liquid-liquid dispersion, while in Section 12-3 we discuss coalescence. Section 12-4 gives an introduction to the methods used for population balance models, along with references for further reading. In Section 12-5 we describe more concentrated dispersed phase systems, including phase inversion. Section 12-6 deals with other considerations, such as suspension, mass transfer, and other complexities. Section 12-7 with equipment used in liquid-liquid operations. Section 12-8 with scale-up, and Section 12-9 provides industrial examples. Nomenclature and references then follow. Although every attempt has been made to make this a stand-alone chapter, space limitations occasionally make it necessary to refer to other chapters in the book. 

Because of the relatively small number of experiments done on commercial-scale equipment before submission, and the often very narrow factor ranges (Hi/Lo might differ by only 5-10%), if conditions are not truly under control, high-level models (multi-variate regressions, principal components analysis, etc.) will pick up spurious signals due to noise and unrecognized drift. For example, Fig. 4.43 summarizes the yields achieved for... 

---