dc.contributor.author	Li, Zhiwei
dc.date.accessioned	2022-09-14T08:36:14Z
dc.date.available	2022-09-14T08:36:14Z
dc.date.issued	2020
dc.description	A thesis submitted to the Faculty of Engineering and the Built Environment in fulfilment of the requirement for the degree Doctor of Philosophy (PhD) in Chemical Engineering, University of the Witwatersrand, Johannesburg, 2020	en_ZA
dc.description.abstract	Batch processing has been embraced by numerous chemical industries, such as the food, beverage, specialty chemical, and pharmaceutical industries because of its flexibility of accommodating changes in demand and responding effectively to uncertainties in market and supply chains. On the other hand, wastewater generated by batch processes depends on the specific tasks. Thus, the methods of wastewater minimization developed for continuous processes do not apply to batch processes. Few studies based on insight-based techniques have been reported to address wastewater recovery issues for flexible batch processes. The flexible batch process refers to that in which the durations of batch operations are treated as variables, not parameters. Therefore, a conceptual analysis was performed in this work to address the wastewater minimization in batch plants with flexible scheduling. A dynamic programming approach was first proposed to design a batch water network based on predefined scheduling. Insight from these results could assist the designer in rescheduling operations to maximize water recovery through direct water reuse. However, the extent of performance improvement is limited because the rescheduling process only involves a few operations, not all of the water operations. Thus, the dynamic programming method was extended to flexible batch processes in which only durations of batch operations are given. The difference is that in the former method, the stage is determined by the timings of water operations, while for the latter approach, the stages are identified based on the inlet concentration of water operations. Although dynamic programing approach, as an algebraic method, could provide a graphical representation of the targeting process, it is difficult to find the optimal solution when faced with complex problems. A match ranking matrix approach was proposed to prioritize matches between water sources and sinks. Batch water network could be synthesized by choosing optimal matches between water sources and sinks. Besides, a hybrid method of combing water pinch analysis and match ranking matrix method was presented to design batch water network, which takes advantages of graphical representation of pinch analysis and insight for the design of batch water network from match ranking matrix method. Finally, the main conclusions and future work are summarized. These conceptual methods in this work could be used to address the wastewater minimization in flexible batch plants.	en_ZA
dc.description.librarian	NG 2022	en_ZA
dc.faculty	Engineering and the Built Environment	en_ZA
dc.format.extent	Online resource (196 pages)
dc.identifier.citation	Li, Zhiwei (2020) A conceptual analysis for resource optimization in variable time multipurpose batch plants, University of the Witwatersrand, Johannesburg, <http://hdl.handle.net/10539/33178>
dc.identifier.uri	https://hdl.handle.net/10539/33178
dc.language.iso	en	en_ZA
dc.phd.title	Ph.D.	en_ZA
dc.school	School of Chemical and Metallurgical Engineering	en_ZA
dc.subject.lcsh	Factory and trade waste--Management
dc.subject.lcsh	Water purification chemicals industry
dc.subject.lcsh	Water-supply--Environmental aspects
dc.title	A conceptual analysis for resource optimization in variable time multipurpose batch plants	en_ZA

A conceptual analysis for resource optimization in variable time multipurpose batch plants

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