Process plants that produce chemical products through pre-designed processes are fundamental in the Chemical Engineering industry. The safety of hazardous processing plants is of paramount importance as an accident could cause major damage to property and/or injury to people. HAZID is a computer system that helps designers and operators of process plants to identify potential design and operation problems given a process plant design. However, there are issues that need to be addressed before such a system will be accepted for common use. This research project considers how to improve the usability and acceptability of such a system by developing tools to test the developed models in order for the users to gain confidence in HAZID s output as HAZID is a model based system with a library of equipment models. The research also investigates the development of computer-aided safety applications and how they can be integrated together to extend HAZID to support different kinds of safety-related reasoning tasks. Three computer-aided tools and one reasoning system have been developed from this project. The first is called Model Test Bed, which is to test the correctness of models that have been built. The second is called Safe Isolation Tool, which is to define isolation boundary and identify potential hazards for isolation work. The third is an Instrument Checker, which lists all the instruments and their connections with process items in a process plant for the engineers to consider whether the instrument and its loop provide safeguards to the equipment during the hazard identification procedure. The fourth is a cause-effect analysis system that can automatically generate cause-effect tables for the control engineers to consider the safety design of the control of a plant as the table shows process events and corresponding process responses designed by the control engineer. The thesis provides a full description of the above four tools and how they are integrated into the HAZID system to perform control safety analysis and hazard identification in process plants.

<div>As the global population approaches 10 billion by the mid-century, supplying all the needs of the human race from the Earth’s limited land area and resources with minimized greenhouse gas emission will be the essential challenge of sustainability. In a sustainable economy, all renewable energy, in combination with carbon sources and other elements from the nature, such as water, air and land, will be used synergistically to produce building blocks for human beings. These building blocks, including electricity, heat, fuels, hydrogen, etc., will enable the production of all the end uses for human beings. The challenge for chemical engineers is to come up with processes and synergistic strategies to enable such a sustainable future.</div><div><br></div><div>Shale gas can serve as both energy resource and chemical feedstock for the transition period towards a sustainable economy, and has the potential to be a carbon source for the long term. Natural gas liquids contained in shale gas provide abundant feedstock for chemical and fuel production and could bring extra value for remote shale gas basins. Unlike current shale gas processing where large scales are preferred, simple and intensified processes with least processing steps and least pieces of equipment are favored for remote shale plays. While conventional shale gas processing usually follows a four-section hierarchy of "gas treatment - NGL recovery - NGL fractionation - NGL activation", four innovative configurations are proposed for simpler and intensified process design, including NGL co-processing, integrated NGL recovery and activation, switched NGL recovery and activation, and eliminated NGL recovery. A two-step conversion of NGLs to liquid hydrocarbons via dehydrogenation followed by oligomerization is used as an example to show how these innovative process designs evolve. Simulation results show that the loss of ethane, the NGL component with the highest concentration, could be largely reduced by the innovative process configurations. At the same time, higher yield of liquid products, fewer processing steps, reduced pieces of equipment and elimination of energy and capital-intensive units can be achieved. The intensification of process here would benefit the modularization of shale gas plants, and make it possible for distributed production of liquid hydrocarbons onsite for remote shale locations. </div><div><br></div><div>While shale gas being the carbon source for a sustainable future, renewable energy, especially solar and wind energy, will become the dominant energy resources for a sustainable economy. However, both solar and wind energy are dilute resources and harvesting them requires vast tracts of land, which could potentially compete with agricultural production for food. As a bookend case study, we investigate the land requirement for a 100% solar economy. The contiguous United States is used as an example and our analysis takes into account several issues that are usually ignored, such as the intermittent solar availability, estimation of future energy demand, actual power production from solar farms and available land types. Results show that it will be difficult for currently available land to meet the energy needs using current solar park designs for the entire contiguous United States and for nearly half of the individual states, which include well over half of the total US population. Barring radical improvements in agricultural output that could greatly reduce the land devoted to agriculture, the competition for land between energy and food seems inevitable, posing a major challenge to a future solar economy. If we extend the study to Germany, the United Kingdom and China, we could see that the challenge exists for both developed and developing countries. </div><div><br></div><div>To resolve the issue, a concept of "Aglectric" farming is proposed, where agricultural land produces electricity without diminishing existing agricultural output. Both wind turbines and photovoltaic (PV) panels can be used to generate electricity on agricultural land. While the use of the current PV panels is known to have a negative impact on crop growth, we propose several innovative PV systems using existing and new materials, innovative installation paradigms and module designs. Through extensive modeling of PV shadows throughout a day, we show that some of our designed PV systems could mitigate the loss of solar radiation while still maintaining substantial power output. Thus, it should be possible to design and install these PV systems on agricultural land to have significant power output without potentially diminishing agricultural production. We also show that PV aglectric farms alone will have the potential of realizing a 100% solar economy without land constraint. Together with regular PV parks and wind aglectric farms, PV aglectric farms will serve as an important option for a renewable future.</div><div><br></div><div>With its high energy density and zero greenhouse gas emission, hydrogen is the key energy carrier in a sustainable future. We introduce a process design strategy for the production of hydrogen by high temperature water electrolysis using concentrated solar thermal energy. At the same time, co-production of hydrogen and electricity is investigated where hydrogen can be produced by both thermochemical cycles and high temperature electrolysis. The process design features the process integration between hydrogen production and power generation. Process simulation is performed in an integrated Matlab and Aspen Plus platform. Efficiencies are analyzed for various processes.</div><div><br></div><div>Synergy is the key feature of all the studies in the dissertation. Process intensification for shale gas conversion and process integration for solar hydrogen production are examples of synergy at the process level. Coproduction of hydrogen and electricity and coproduction of electricity and food are examples of synergy at the building block level. Potential synergistic use of solar, wind and shale resources is an example of synergy at the resource level. Synergy is the keyword of the sustainable future we are pursuing.</div>

La méthode de l’Analyse du Cycle de Vie (ACV) est devenue ces dernières années un outil d’aide à la décision « environnementale » pour évaluer l’impact des produits et des processus associés. La pratique de l’ACV est documentée comme un outil pour l’évaluation d’impacts, la comparaison et la prise de décisions « orientée produit ». L’exploitation d’une telle méthode pour les procédés de l’industrie bio-physico-chimique a gagné récemment en popularité. Il existe de nombreux faisceaux d’amélioration et d’expansion pour sa mise en oeuvre pour l’évaluation des procédés industriels. L’étude s’attache à la production de biocarburant à partir de la plante Jatropha curcas L. selon une approche « attributionelle ». Cette étude présente l’évaluation environnementale d’un agro-procédé et discute de l’opportunité de coupler les concepts, les méthodes et les outils de l’ACV et de l’IPAO (Ingénierie des Procédés Assistés par Ordinateur). Une première partie présente l’ACV appliquée à l’agrochimie. L’état de la littérature apporte des enseignements sur les diverses études qui mettent en évidence le rôle et l’importance de l’ACV pour les produits et les différents agro-procédés. La substitution des carburants classiques par les biocarburants est considérée comme une voie potentielle de substitution aux énergies fossiles. Leur processus se doit d’être évalué au regard de l’impact environnemental et du paradigme du développement durable, en complément des critères classiques, économiques et politiques. La deuxième partie aborde notre étude ACV de la production du biocarburant à partir de la plante Jatropha. Cette évaluation englobe la culture et la récolte en Afrique, l’extraction de l’huile et la phase de production de biocarburants, jusqu’à son utilisation par un moteur à explosion. À cet effet, les normes ISO 14040 et 14044 sont respectées. Basée sur une perspective « midpoint » avec les méthodes de calcul d’impacts, Impact 2002+ et CML, nous fournissons les premiers résultats de la phase d’interprétation (GES, appauvrissement des ressources, la couche d’ozone, l’eutrophisation et l’acidification). Cette étude démontre le potentiel de production de biocarburants de deuxième génération à réduire l’impact environnemental. Dans le même temps, elle révèle que l’unité de transesterification est le plus impactant. Nous identifions les limites de notre application selon une approche ACV « pure ». Dans la troisième partie, nous discutons des bénéfices attendus du couplage de l’ACV et des méthodes de modélisation et de simulation de l’ingénierie des procédés. Nous suggérons alors une amélioration de l’approche environnementale des systèmes de production. Nous fournissons un cadre de travail intégrant les différents points de vue, système, processus et procédé afin d’évaluer les performances environnementales du produit. Un outil logiciel, SimLCA, est développé sur la base de l’environnement Excel et est validé par l’utilisation de la solution ACV SimaPro et du simulateur de procédés Prosim Plus. SimLCA permet un couplage ACV-simulation pour l’évaluation environnementale du système complet de production de biocarburant. Cette intégration multi-niveaux permet une interaction dynamique des données, paramètres et résultats de simulation. Différentes configurations et scénarios sont discutés afin d’étudier l’influence de l’unité fonctionnelle et d’un paramètre de procédé. La quatrième partie établit la conclusion générale et trace les perspectives. / With the rise of global warming issues due to the increase of the greenhouse gas emission and more generally with growing importance granted to sustainable development, process system engineering (PSE) has turned to think more and more environmentally. Indeed, the chemical engineer has now taken into account not only the economic criteria of the process, but also its environmental and social performances. On the other hand LCA is a method used to evaluate the potential impacts on the environment of a product, process, or activity throughout its life cycle. The research here focused on coupling of PSE domain with the environmental analysis of agricultural and chemical activities and abatement strategies for agro-processes with the help of computer aided tools and models. Among many approaches, the coupling of PSE and LCA is investigated here because it is viewed as a good instrument to evaluate the environmental performance of different unitary processes and whole process. The coupling can be of different nature depending on the focus of the study. The main objective is to define an innovative LCA based on approach for a deep integration of product, process and system perspectives. We selected a PSE embedded LCA and proposed a framework that would lead to an improved eco-analysis, eco-design and eco-decision of business processes and resulted products for researchers and engineers. In the first place we evaluate biodiesel for environmental analysis with the help of field data, background data and impact methodologies. Through this environmental evaluation, we identify the hotspot in the whole production system. To complement the experimental data this hotspot (i.e. transesterification) is selected for further modeling and simulation. For results validation, we also implement LCA in a dedicated tool (SimaPro) and simulation in a PSE simulation tool (Prosim Plus). Finally we develop a tool (SimLCA) dedicated to the LCA by using PSE tools and methodologies. This development of SimLCA framework can serve as a step forward for determination of sustainability and eco-efficient designing.

Dans un contexte de prise en compte croissante des enjeux environnementaux, l'industrie de la chimie et des procédés se retrouve confrontée à des problématiques de substitution de molécules. Les méthodes de formulation inverse, qui consistent en la recherche assistée par ordinateur de molécules satisfaisant un ensemble de contraintes, répondent de manière efficace à ces problématiques. A partir de l'analyse systémique des usages et fonctionnalités nécessaires dans ce contexte, nous développons un outil logiciel de formulation inverse mettant en oeuvre un algorithme génétique. Celui-ci est capable d'explorer un espace de solutions plus vaste en considérant les mélanges et non les molécules seules. Par ailleurs, il propose une définition des problèmes très flexible qui permet la recherche efficiente de molécules issues de filières renouvelables. En s'appuyant sur l'ingénierie système et l'ingénierie d'entreprise, nous proposons un processus formel de prise de décision pour la substitution de produit dans un contexte industriel. Ce processus de décision multi-critères englobe les phases de définition des exigences, de génération de solutions alternatives, de sélection de la meilleure alternative et de mise en oeuvre du produit. Il utilise une approche dirigée par les modèles et des techniques de prises de décision qui garantissent un alignement opérationnel en complément de l'alignement stratégique. A travers un cas d'étude, nous montrons comment l'utilisation conjointe de notre outil de recherche par formulation inverse et de notre processus de décision permet une démarche environnementale de substitution de produit à la fois efficiente et conforme à la réalité de l'entreprise. / In a context where environmental issues are increasingly taken into account, the chemical related industry faces situations imposing a chemical product substitution. Computer aided molecular design methods, which consist in finding molecules satisfying a set of constraints, are well adapted to these situations. Using a systemic analysis of the needs and uses linked to this context, we develop a computer aided product design tool implementing a genetic algorithm. It is able to explore a wider solution space thanks to a flexible molecular framework. Besides, by allowing a very flexible setting of the problem to be solved, it enables the search of molecules sourced from renewable resources. Based on concepts from system and enterprise engineering, we formalize a decision making process dedicated to the product substitution in an industrial context. This multi-criteria decision process includes the phases of the requirements definition, of the generation of alternative solutions, of the selection of the best alternative and of the product application. It uses a model driven approach and decision making techniques that guaranty an operational alignment in addition to the strategic alignment across the chemical enterprise. Through a case study, we expose how the combination of our computer aided product design tool and our decision making process enables an environmentally compliant approach of product substitution which is both efficient and in adequacy with enterprise context.