Thesis (Ph. D.)--Lehigh University, 2003. / Includes vita. Includes bibliographical references (leaves 156-160).

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Thesis (Ph. D.)--Lehigh University, 2004. / Includes vita. Includes bibliographical references (leaves 196-208).

M.Tech. (Chemical Engineering) / The work presented here constitutes an account of the optimization of a chemical reaction process with special reference to the methodology of reagent addition in the case of fast reactions. The chemical reaction process for manufacture of the Formaldehyde Acetaldehyde condensation product Pentaerythritol (Penta) as it is conducted at the plant of National Chemical Products, a division of Sentrachem, was studied in detail. The industrial scale reactor design was critically examined, 'with emphasis on the evaluation of mixing and reagent dispersion efficacy and its effect on chemical reactor performance. Batches of Pentaerythritol products were prepared in a laboratory bench scale reactor. Reagent concentrations and proportions were controlled at various values and the reaction temperature profiles were controlled so as to be similar for all the tests. Moreover the mode and intensity of liquid agitation and reagent admixture was varied in a controlled manner between the various tests. The reaction liquors from the various batches were sampled and the samples subjected to chemical analysis. The results were then compared in order to show the effect of agitation and reagent dispersion intensity on the reaction process and products. The results indicate conclusively that liquid flow or agitation intensity and reagent admixture or sparging variation has an effect on the type and relative amounts of chemical species produced in the laboratory apparatus. This effect is especially significant with respect to the side products Di-pentaerythritol and Bis Penta Mono-formal (B.P.M.F.). The effect is also demonstrated for the gamut of various side products collectively and arbitrarily designated as the so-called "unknowns". Furthermore the formation of coloured products in the reaction is distinctly influenced by the same variation. High intensity agitation and reagent sparging enhances Dipenta formation and inhibits formation of the Formal B.P.M.F, "unknowns" and colour. At very low agitation and sparging intensity Di-penta production is diminished while B.P.M.F., "unknowns" and colour formation is favoured. The work includes a proposal for the manufacture and installation of improved reagent sparging systems in the NCP Transvaal commercial scale Penta Reactor.A tentative method for the design of a continuous reactor for penta production using optimised Tee mixers for high velocity in-line reagent sparging is also developed.

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A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Science in Engineering. Johannesburg, 2016 / Traditional work in batch processes has focused mainly on the optimisation of batch reactors and the scheduling of batch processes. Recent development in the application of attainable region (AR) theory has allowed for its entry into this landscape. As time is a crucial consideration in the study of these systems, furthering the application of AR theory to batch reactors required the incorporation of time into the ARs. This was previously done in terms of residence time for continuous systems. With its use in batch systems this work sought to investigate how the time component differs within ARs between batch and continuous systems. It demonstrated that while residence time could be undergo linear mixing, the time in batch systems could not due to its nature. Therefore the ARs generated in concentration-residence time and concentrationtime space would differ slightly. A way to circumnavigate this was proposed in that the AR be plotted in terms of concentration and residence time following which the continuous reactor structure is obtained. From this the batch structure can be determined by substituting the equivalent reactor types. Production rates were also introduced as a method of interpreting an AR plotted in concentration-residence time space. By minimising the time taken to reach a particular point in the AR, one may effectively increase the rate at which the desired product can be produced. The developed concepts were applied to two example systems with the aim of obtaining the batch reactor structure for the most productive point that satisfied a given objective. Success was achieved for 2D single reaction system as well as a more complex 3D two biological reaction system. The more complex system led to the development of non-conventional attainable regions in terms of another process variable; in this case pH was used to demonstrate the concept although other variables such as temperature and pressure may be used in a similar fashion. Such plots may be used to further optimise the reaction system or identify a particular region in which to operate. Further development of AR theory to batch reactors has indeed allowed its use in conjunction with optimisation and scheduling of batch processes. Most notably, scheduling may utilise the obtained batch structure as part of the process to be scheduled or use the indicated reaction time. / MT2016

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