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Synthesis and design of optimal biorefinery
Full text linkSektorer vedrørende kemikaliefremstilling, brændstofproduktion og kraftværker m.fl. er stærkt afhængige af fossile ressourcer. For at understøtte en vedvarende økonomisk vækst er flere fossile ressourcer nødvendige, hvilket, uundgåeligt, leder til alvorlige virkninger på det globale miljø. Disse udfordringer motiverer udviklingen af bæredygtige teknologier til bearbejdning af vedvarende råvarer til produktion af brændstoffer, kemikalier og materialer, i det der almindeligvis betragtes som et bioraffinaderi. Bioraffinaderikonceptet dækker over de en eller flere processer, der producerer forskellige produkter fra biobaseret råmateriale. Da der er flere biobaserede råvarer, giver dette anledning til udvikling af forskellige konverteringskoncepter til at producere forskellige ønskede produkter. Dette resulterer i en række udfordringer til syntese og design af det optimale bioraffinaderikoncept i det tidlige stadie af procesudvikling: (i) Kombinatorisk udfordring: et stort antal potentielle behandlingsveje som følge af en kombination af mange potentielle råmaterialer, mange konverteringsteknologier og produkter; (ii) Dataindsamlingsudfordring: data, der typisk anvendes til tidlig procesgennemføreligheds-analyse er af tværfaglig karakter og ofte begrænset og usikker; (iii) Kompleksitetsudfordring: dette problem er komplekst, som kræver adskillige evalueringskriterier (teknisk, økonomisk, bæredygtighed). Dette ph.d.-projekt har til formål at udvikle et beslutningsværktøj til at til at identificere optimale bioraffinaderikoncepter i den tidlige produkt/procesudviklingsfase. Til dette formål er en systematisk ramme blevet udviklet, der inkluderer en superstrukturbaseret optimeringstilgang, en omfattende database af bearbejdnings- og omdannelsesteknologier, og modelbiblioteker til at tillade generering og sammenligning af et stort antal alternativer for i sidste ende at identificere optimale løsninger. Resultatet er identificering af den optimale råvare, produktportefølje (enkelt eller adskillige) og de tilsvarende procesteknologivalg for et givet markedsscenario. Den økonomiske investeringsrisiko som følge af markedets usikkerhed er yderligere analyseret for at give anledning til risikobevidst beslutningstagning. Anvendelsen af den udviklede analyse og beslutningsværktøjskasse er fremhævet gennem relevante bioraffinaderi case studier: bioethanol, biobenzin eller biodieselproduktion; algebioraffinaderi; og bioethanolopgraderingskoncepter er præsenteret. Denne udvikling og analyse giver en robust vejledning til at støtte udviklingen af bæredygtige og fremtidige bioraffinaderier.Chemical manufacturing, transportation fuels production and power plants among other sectors have strongly depended on fossil-based resources. To support sustained economic growth, additional fossil-based resources are required, but, inevitably, this also has a major impact on the global environment. These challenges motivate thedevelopment of sustainable technologies for processing renewable feedstock for the production of fuels, chemicals and materials in what is commonly known as a biorefinery. The biorefinery concept is a term to describe one or more processes whichproduce various products from bio-based feedstock. Since there are several bio-basedfeedstock sources, this has motivated development of different conversion concepts producing various desired products. This results in a number of challenges for the synthesis and design of the optimal biorefinery concept at the early-stage of process development: (i) Combinatorial challenge: a large number of potential processing paths resulting from the combination of many potential feedstocks, and many available conversion technologies to produce a number of desired products; (ii) Data challenge: the data typically used for early stage process feasibility analysis is of a multidisciplinary nature, often limited and uncertain; (iii) Complexity challenge: this problem is complex requiring multi-criteria evaluation (technical, economic,sustainability).This PhD project aims to develop a decision support tool for identifying optimal biorefinery concepts at the early-stage of product-process development. To this end, asystematic framework has been developed, including a superstructure-based optimization approach, a comprehensive database of processing and conversion technologies, and model libraries to allow generation and comparison of a large numberof alternatives at their optimality. The result is the identification of the optimal rawmaterial, the product (single vs multi) portfolio and the corresponding process technology selection for a given market scenario. The economic risk of investment due to market uncertainties is further analysed to enable risk-aware decision making. Theapplication of the developed analysis and decision support toolbox is highlightedthrough relevant biorefinery case studies: bioethanol, biogasoline or biodiesel production; algal biorefinery; and bioethanol-upgrading concepts are presented. This development and analysis provides a robust guidance to support the development ofsustainable and future biorefineries
Synthesis and Design of Biorefinery Processing Networks with Uncertainty and Sustainability analysis
No full textChemical industries usually rely on fossil based feedstock, which is a limited resource. In view of increasing energy demands and the negativeenvironmental and climate effects related to the use of fossil based fuels, this motivates the development of new and more sustainable technologiesfor processing renewable feedstocks, with the aim of bridging the gap for fuel, chemical and material production. This project is focusing on biorefinerynetwork design, in particular for early stage design and development studies.Optimal biorefinery design is a challenging problem. It is a multi-objective decision-making problem not only with respect to technical and economicfeasibility but also with respect to environmental impacts, sustainability constraints and limited availability & uncertainties of input data at the earlydesign stage. It is therefore useful to develop a systematic methodology to support the evaluation of processes and the generation of sustainablealternatives for identifying the optimal processing routes. One particular challenge here is to include proactively sustainability analysis as part of thesynthesis of biorefinery networks. Another challenge is the handling of several sources of uncertainties such as availability and composition ofrenewable feedstock, the technical performance of alternative processing technologies and the availability of future markets for biorefinery products,among others.As part of earlier work in our research group, a systematic methodology to identify/generate optimal biorefineries was developed using thesuperstructure-based approach, and was implemented in a computer-aided framework. The methodology consists of tools and methods includingdatabases, models, superstructure, and solution strategies to represent, describe and evaluate various combinations of processing networks. Theoptimization of the network is formulated as a mixed integer nonlinear programming type of problem and solved in GAMS. The methodology wasapplied for designing optimal biorefinery networks considering biochemical routes. Furthermore, the methodology has also been applied to soybean oilprocessing networks and industrial wastewater treatment networks. In the work presented here, the methodology for designing optimal biorefinerynetworks was expanded with inclusion of thermochemical routes, which means the scope and the size of the biorefinery network problem wasextended at the level of the database, the models and the superstructure relevant for thermo-chemical conversion routes (the conversion of biomassfeedstocks (corn stover, poplar wood) to fuels and chemicals (FT-gasoline, FT-diesel, bioethanol and higher alcohols) via thermal decompositionprocesses like pyrolysis and gasification).,In this study, we extend the methodology, models and database by incorporating uncertainty and sustainability analysis as well. Appropriate ranges foruncertain parameters are identified with their correlation/covariance structure and latin hypercube sampling (LHS) is used to sample parameters fromtheir respective domain of uncertainty. The parameter samples are then used as input for solving a deterministic and stochastic optimization problem.The sustainability analysis was performed in two ways: First, it was performed retrospectively to the optimal biorefinery network solution obtained afterthe MINLP by using an in-house software (SustainPRO) that employs ICHEME sustainability metrics. Secondly, the sustainability analysis wasincluded proactively as part of the MINLP optimization problem that is performed to find the optimal processing path with respect to multi-criteriaassessment including technical, economics and sustainability.The expanded database and superstructure with uncertainty and sustainability analysis form a powerful process synthesis toolbox to be used indesign of future biorefineries with multi-criteria evaluation (technical and economic feasibility, environmental impact and sustainability)
Synthesis and Design of Thermochemical and Biochemical Biomass Processing Networks under Uncertainty
Full text linkToward a Computer-Aided Synthesis and Design of Biorefinery Networks: Data Collection and Management Using a Generic Modeling Approach
Full text linkRecent research into biorefineries resulted in many competing concepts and technologies for conversion of renewable biobased feedstock into an array of promising products including fuels, chemicals, materials, etc. The topic of this study is collection and management of the complex biorefinery data that are needed among others to support the superstructure-based optimization studies. To this end, we first formulate an integrated thermochemical and biochemical biorefinery superstructure and then use a generic modeling approach to represent each processing technology in the superstructure. The generic model parameters includes reaction yield, utility consumption, and separation efficiency among others, which are identified on the basis of input−output data (generated from rigorous models) collected from detailed biorefinery case studies reported in the open literature. The outcome is a verified database for the extended biorefinery networks combining thermochemical and biochemical platforms that represents 2882 potential biorefinery routes. The validated biorefinery database is made public and can be used to cross-validate and benchmark new biorefinery technologies and concepts as well as in superstructure-based optimization studies
A computer-aided support tool for synthesis and design of biorefinery networks under uncertainty
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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