Throughout the process industry, the conservation and allocation of mass and energy resources plays a pivotal role in the site wide optimization of a plant. Typically, raw materials are transformed into products, byproducts and wastes through pathways involving heating/cooling, pressure changes, mixing, reactions and separations. These pathways often require the addition or removal of energy from the system. The optimal management of such a system therefore requires conserving resources through the appropriate allocation of materials and energy. In a typical plant, there are both mass and energy objectives that require optimization. This dissertation will focus on optimizing the mass and energy resources present in a utility system. This will entail developing a novel framework of techniques to: target and design steam cogeneration networks while minimizing fuel requirements, identifying and utilizing sources of waste heat and incorporating heat pipes to enhance heat exchange networks. Additionally, a specific case of waste recovery will be examined when properties are the primary concern.

This work is aimed at development of systematic approaches to the design of multiscale systems. Specifically four problems are addressed: environmental impact assessment (EIA) of new and retrofitted industrial processes, integration of process effluents with the macroscopic environmental systems, eco-industrial parks (EIP), and advanced life support (ALS) systems for planetary habitation. While design metrics and specific natures of each problem poses different challenges, there are common themes in the devised solution strategies: a. An integrated approach provides insights unseen by addressing the individual components of the system and, therefore, better understanding and superior results. b. Instead of dealing with multiple scales simultaneously, the design problem is addressed through interconnected stages without infringing upon the optimization degrees of freedom in each stage. This is possible through the concept of targeting. c. Mathematical programming techniques can be used effectively to systematize the integration concepts, the target identification, and the design of multi-scale systems. The dissertation also introduces the following specific contributions: i. For EIA, a new procedure is developed to overcome the limitations of conventional approaches. The introduced procedure is based on three concepts: process synthesis for systematic generation of alternatives and targeting for benchmarking environmental impact ahead of detailed design, integration of alternative with rest of the process, and reverse problem formulation for targeting. ii. For integrating process effluents with macroscopic environmental systems, focus is given to the impact of wastewater discharges on macroscopic watersheds and drainage systems. A reverse problem formulation is introduced to determine maximum allowable process discharges that will meet overall environmental requirements of the watershed. iii. For EIPs, a new design procedure is developed to allow multiple processes to share a common environmental infrastructure, exchange materials, and jointly utilize interception systems that treat waste materials and byproducts. A source-interception-sink representation is developed and modeled through an optimization formulation. Optimal interactions among the various processes and shared infrastructure to be installed are identified. iv. A computational metric is introduced to compare various alternatives in ALS and planetary habitation systems. A selection criterion identifies the alternative which contributes to the maximum reduction of the total ESM of the system.

Throughout the process industry, the conservation and allocation of mass and energy resources plays a pivotal role in the site wide optimization of a plant. Typically, raw materials are transformed into products, byproducts and wastes through pathways involving heating/cooling, pressure changes, mixing, reactions and separations. These pathways often require the addition or removal of energy from the system. The optimal management of such a system therefore requires conserving resources through the appropriate allocation of materials and energy. In a typical plant, there are both mass and energy objectives that require optimization. This dissertation will focus on optimizing the mass and energy resources present in a utility system. This will entail developing a novel framework of techniques to: target and design steam cogeneration networks while minimizing fuel requirements, identifying and utilizing sources of waste heat and incorporating heat pipes to enhance heat exchange networks. Additionally, a specific case of waste recovery will be examined when properties are the primary concern.

Abstract will not load on to DSpace

無 / The objective of this study is to establish a base for understanding inflexibility, with different kinds of integration problems being examined and explained. Studies of process integration have focused mostly on the design and management of efficient operation with information technology but very little on the difficulty in making changes with tightly linked processes. In order to eliminate risks of integration failure, there is a need for deep understanding of the types and causes of inflexibility with process integration. Based on the literature and industry experience of process integration and enterprise flexibility/inflexibility, this study proposes that inflexibility can be classified as either operational, organizational, or systems inflexibility. Sources of inflexibility have been investigated from views of business design, users’ willingness and capability, and systems designers’ designs. Cases studied shown that these three sources of inflexibility are interrelated and can reciprocally affect business performance. Companies applying process integration may eliminate the risk of integration downsides by carefully managing business design, user willingness and system design capability. Only with a broad and thorough view of the system, people and process interactions can a firm capitalize its investment in process integration.

This thesis study focuses on the development of model-based optimization strategies for the integration of process scheduling and dynamic optimization, and applications of the integrated approaches to industrial polymerization processes. The integrated decision making approaches seek to explore the synergy between production schedule design and process unit control to improve process performance. The integration problem has received much attention from both the academia and industry since the past decade. For scheduling, we adopt two formulation approaches based on the state equipment network and resource task network, respectively. For dynamic optimization, we rely on the simultaneous collocation strategy to discretize the differential-algebraic equations. Two integrated formulations are proposed that result in mixed discrete/dynamic models, and solution methods based on decomposition approaches are addressed. A class of ring-opening polymerization processes are used for our industrial case studies. We develop rigorous dynamic reactor models for both semi-batch homopolymerization and copolymerization operations. The reactor models are based on first-principles such as mass and heat balances, reaction kinetics and vapor-liquid equilibria. We derive reactor models with both the population balance method and method of moments. The obtained reactor models are validated using historical plant data. Polymerization recipes are optimized with dynamic optimization algorithms to reduce polymerization times by modifying operating conditions such as the reactor temperature and monomer feed rates over time. Next, we study scheduling methods that involve multiple process units and products. The resource task network scheduling model is reformulated to the state space form that offers a good platform for incorporating dynamic models. Lastly for the integration study, we investigate a process with two parallel polymerization reactors and downstream storage and purification units. The dynamic behaviors of the two reactors are coupled through shared cooling resources. We formulate the integration problem by combining the state space resource task network model with the moment reactor model. The case study results indicate promising improvements of process performances by applying dynamic optimization and scheduling optimization separately, and more importantly, the integration of the two.

Steam boilers are used to generate steam in order to meet cold process heat requirements. The most common heat exchanger network layout associated with the boiler is a completely parallel design. This observation suggests that the flowrate of steam needed for the system can be reduced, while maintaining the required duty, simply by changing the layout of the network. Phase change of saturated steam to saturated liquid plays a vital role in the targeting method as well as the design of the network layout. A hybrid graphical and mathematical technique for targeting and network synthesis is presented. The main objective of the technique is to reduce steam flowrate without compromising duty requirements of the process heat exchangers. In order to assess the advantage of a hybrid technique, a case study is used where steam savings of 29.6% is obtained. A complete mathematical technique to demonstrate the advantage of the graphical targeting concept in solution time improvement is further presented. / Dissertation (MEng)--University of Pretoria, 2008. / Chemical Engineering / unrestricted

This thesis describes the design optimization of two different types of vessels. They are LHA(R), a replacement for the US Navy amphibious assault ship and DDG51, a destroyer class vessel. The overall measure of effectiveness (OMOE) and the lead ship acquisition cost (LCA) are considered to be the objective functions. The evaluation of feasibility of the designs and various ship parameter calculations are performed using the US Navy ship design evaluation software ASSET. ASSET is integrated with the design optimization software DARWIN to obtain results representing the best designs over a range of LCA. Model Center software is used to integrate the processes ASSET and Darwin. The results generated will provide the owner with the best designs possible (designs with high OMOE) over a range of LCA. This thesis is mainly of academic interest. The results generated could help the owners to look at various design options available for the amount of money they are willing to spend. / Master of Science

Business Administration, Business Process & Supply Chain Management, Degree Project (Master), 30 higher education credits, 5FE02E, Spring 2012   Authors: Kateryna Zubova and Olga Arikainen   Tutor: Åsa Gustavsson Title: Procurement Process Integration in Swedish and Ukrainian Companies Producing Machinery and Equipment Background: Although the science of economics and logistics comprises a great amount of literature on supply chain integration, there is a lack of information on procurement process integration. Procurement process is one the supply chain processes and is one of the most important processes for manufacturing companies. Purpose: To describe the level of procurement process integration (PPI), tools of PPI and barriers to PPI from buyers’ perspective in Swedish and Ukrainian companies producing machinery and equipment, and then to test if there is a significant difference in them between respondents of two countries. Method: Web-based questionnaire was created and sent out to 500 companies producing machinery and equipment in Sweden and to 500 companies in Ukraine.  73 responses were received from Swedish companies and 49 responses from Ukrainian companies. T-test was performed in order to test the differences in procurement process integration between Swedish and Ukrainian companies in terms of levels of integration, tools of integration and barriers to integration. Results, conclusions: There is no significant difference in the level of integration between Swedish and Ukrainian companies. In both countries the average level of integration is medium that means long-term relationships which are reviewed periodically. However, significant differences were found in the tools and barriers to procurement process integration between Swedish and Ukrainian companies.

Continuous process improvement is a critical element in maintaining competitiveness of the process industries. An important category of process improvement is process debottlenecking which is associated with plants that have sold-out products while making a profit. In such cases, market conditions and the prospects for enhancing revenues and profits drive the process to increase production. To overcome the limitation of conventional sequential unit-by-unit debottlenecking approach, this work introduces a new approach. This new approach is simultaneous in nature and is based on posing the debottlenecking task as a process integration task which links all the design and operating degrees of freedom and exploits synergies among the units and streams to attain maximum debottlenecking. Additionally, this new approach considers heat integration of the process while simultaneously performing the debottlenecking. Because of the general nonconvexity of the process model, a rigorous interval-based bounding technique is used to determine the target for maximum extent of debottlenecking aside from the problem nonconvexity. Inclusion isotonicity using interval arithmetic is used to determine a global bound for the maximum extent of process debottlenecking. Focus is given to no/low cost debottlenecking such as modest changes in design and operating degrees of freedom. Two case studies are solved to illustrate the applicability of the new approach and its superior results compared to the conventional sequential approach. Intensification, to debottleneck a process and to improve process safety is also addressed in this work. A new definition and classification of intensification is introduced. This classification distinguishes between two types of intensification: single unit and whole process. Process integration and optimization techniques are used to develop a systematic procedure for process intensification. Focus is given to the interaction among the process units while enhancing the intensification of the process. A case study is solved to illustrate the usefulness of the developed approach.