Дисертації з теми "Modelli processo carbonio"
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Coslovich, Davide. "Stima del sequestro potenziale di carbonio nei suoli agricoli del Veneto con il GEFSOC modellyng system." Doctoral thesis, Università degli studi di Trieste, 2011. http://hdl.handle.net/10077/4597.
Повний текст джерелаI suoli globalmente contengono circa 2500 Pg di C in forma minerale ed organica (ca 1550 Pg) ed il flusso annuo da e verso l’atmosfera – che attualmente contiene circa 760 Pg C – coinvolge circa 120 Pg di C. Questi scambi di carbonio sono clima-dipendenti; l’effetto del cambiamento climatico sui depositi di carbonio del suolo è perciò di importanza critica, in quanto anche piccole variazioni di un deposito di tale entità possono determinare importanti conseguenze sulla concentrazione di anidride carbonica in atmosfera, innescando meccanismi retroattivi positivi. Per fare delle previsioni sui cambiamenti dei depositi di carbonio per effetto dei cambiamenti climatici o di altre variabili è neccesario ricorrere a dei modelli; in particolare, per le stime a scala nazionale e regionale si impiegano dei modelli che operano a livello di ecosistema e che vengono abbinati a dei SIT. Vista la forte sinergia con la mitigazione e adattamento ai cambiamenti climatici, la ricerca è stata volta a stimare il potenziale di sequestro e accumulo di sostanza organica nei terreni agricoli del Veneto, con un occhio di riguardo per la gestione sostenibile. In secondo luogo, a fornire uno strumento per la contabilizzazione del sequestro di carbonio nei sistemi agricoli. Si è individuato nel GEFSOC Modelling Sistem uno strumento idoneo per il perseguimento di questi obiettivi; il GEFSOC MS integra due modelli meccanicistici ampiamente sperimentati – Century e RothC – ed il metodo empirico dell’IPCC e li interfaccia con un SOTER-DB e con un GIS. L’uso e la gestione del suolo ed i loro cambiamenti sono variabili fondamentali nel determinare il contenuto di carbonio nei depositi del terreno; poiché manifestano i loro effetti anche secoli dopo che si sono verificati, è necessario ricostruire la loro storia almeno negli ultimi 100 anni. Nel corso della ricerca è stato ideato e sperimentato per la prima volta in questo settore un approccio spazialmente esplicito alle transizioni di uso e gestione del suolo, utilizzando materiale cartografico di varia natura e completando la raccolta dati con statistiche agrarie e fonti storiche. Le simulazioni sono state fatte contemplando due diversi scenari di cambiamento climatico (PCM-B1 e Had3A1FI) spinti fino al 2100. L’analisi dei risultati prodotti evidenzia che i terreni più ricchi in carbonio sono maggiormente soggetti a perdite, mentre quelli poveri, anche se in misura modesta, incrementano il loro contenuto; la tendenza, quindi, è di avvicinarsi ad una maggiore omogeneità. Per quel che riguarda gli usi del suolo, seminativi ed aree agricole eterogenee sono le categorie che hanno manifestato tassi di incremento superiori. I tassi di variazione, comunque, sono tendenzialmente in calo e, per lo scenario di cambiamento climatico meno marcato, ad un certo punto (2070 ca) si portano su valori negativi: questo fatto si ripercuote sui depositi del terreno, che complessivamente mostrano un incremento nel lungo periodo, ma via via più contenuto, fino a raggiungere un massimo e quindi cominciare ad emettere negli ultimi decenni della simulazione. I depositi dei terreni sottoposti allo scenario di cambiamento più marcato, invece, non hanno subito flessioni ed hanno garantito, anche se in misura calante, il sequestro lungo tutto il periodo della simulazione. Questo dato può essere di qualche interesse nello studio degli effetti della temperatura sul rapporto produzione di biomassa-accumulo/decomposizione. L’analisi delle mappe dei depositi e dei tassi di variazione annua ad ettaro prodotte con la sperimentazione, ed il confronto delle stesse con carte del contenuto del carbonio nei terreni di doversa origine e natura, rivelano l’utilità dell’approccio spazialmente esplicito nella definizione delle transizioni dell’uso e gestione del suolo; è possibile infatti riconoscere, dalla zonizzazione, i tematismi che possono avere avuto un peso preponderante nel determinare peculiari situazioni; questo consente di indagarle, verificare la validità delle assunzioni fatte in fase di progettazione, modificare eventualmente la parametrizzazione e reindirizzare le simulazioni. Ad una livello di risoluzione comparabile a quello degli strati informativi di partenza. Alla luce della sperimentazione effettuata, si ritiene che il GEFSOC Modelling System meriti grande considerazione per quanto attiene la contabilizzazione del carbonio nei sistemi agricoli – problematica inevasa fino ad oggi in Italia; quale strumento a supporto del processo decisionale; per le possibili sinergie nella pianificazione di campionamenti e sperimentazioni attinenti; per l’approfondimento della ricerca nell’ambito delle relazioni tra clima e suolo.
XXIII Ciclo
1970
Nocerino, Vincenzo. "Attività preliminari allo sviluppo di un modello matematico per il processo di pellettizzazione e di essiccamento del nero di carbonio." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2022.
Знайти повний текст джерелаGuillemot, Joannès. "Productivity and carbon allocation in European forests : a process-based modelling approach." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112091/document.
Повний текст джерелаThe processes that underlie forest productivity and C allocation dynamics in trees are still poorly understood. Forest growth has for long been thought to be C limited, through a hypothesized causal link between C supply and growth (source control). This C-centric paradigm underlies most of the C allocation rules formalized in process-based models (PBMs). However, the source limitation of growth has been questioned by several authors, arguing that meristem activities are more sensitive than C assimilation to environmental stresses (e.g., water deficit and low temperatures). Moreover, the effect of management, which strongly affects forest functioning and wood growth, is not accounted for in most of the PBMs used to project the future terrestrial C sink. Our main objective in this thesis was to move forward into our understanding of the constraints that affect - or will affect - the wood productivity in European forests, from present to the end of the 21 st century. We addressed this objective through the improvement of the representation of the forest productivity and C allocation in the CASTANEA PBM, building on a detailed analysis of the key drivers of annual wood productivity in French forests over the last 30 years (the species studied are Fagus sylvatica, Quercus ilex, Quercus petraea, Quercus robur and Picea abies). Our results supported the premise that the annual wood growth of the studied species is under a complex control including both source and sink limitations. The inter-site variability in the fraction of C allocatedto stand wood growth was predominantly driven by an age-related decline. At the tree level, we showed that annual wood growth was well predicted by the individual size. The size-asymmetry of growth, i.e., the advantage of big trees in the competition for resources, increased consistently with the whole stand productivity at both inter-site and inter-annual scales. On the basis of our findings, we developed a new C allocation scheme in the CASTANEA PBM, which integrate a combined source-sink limitation of wood growth. The new calibrated model captured both the inter-annual and inter-site changes in stand wood growth that was observed across national environmental gradients. The model was also successfully evaluated against a meta-analysis of carbohydrate reserve pools in trees and satellite-derived leaf area index estimates. Our results indicated that the representation of the environmental control of sink activity does not affect the qualitative predictions of the future of the European forest productivity previously obtained from source-driven PBMs. However, the current, source-driven generation of PBMs probably underestimates the spatial heterogeneity of the effects of climate change on forest growth that arise from sink limitations.Further, we successfully used our findings regarding the dependences of annual wood growth at tree level (i.e., empirical rules of tree growth competition) to calibrate a module for the simulation of the individual growth of trees in the CASTANEA model. The coupled model was used to assess the potential effects of management on forest functioning and wood growth across France. We identified the areas where management efforts may be concentrated in order to mitigate near-future drought impact on national forest productivity. Around a quarter of the French temperate oak and beech forests are currently in zones of high vulnerability, where management could thus mitigate the influence of climate change on forest yield
Stachiw, Rosalvo. "Modelagem e simulação do processo de adsorção de compostos orgânicos em xisto, catalisador exaurido de FCC e carvão ativado em pó." Universidade Tecnológica Federal do Paraná, 2008. http://repositorio.utfpr.edu.br/jspui/handle/1/135.
Повний текст джерелаThe high cost of the activated carbon has motivated the search of low cost adsorbents such as industrial by-products. In this sense, the use of industrial by-products of oil shale: Oil Shale (XC), Pirolized Oil Shale (XR) and Pirolized Oil Shale with Tires (XRP), from PETROSIX/PETROBRAS, and the spent catalyst (CAT), from FCC (Fluid Catalytic Cracking) unit were characterized and used in this work in the adsorption of organics compounds of industrial liquid effluent. The main contribution of this thesis is to propose a mathematical model to the adsorption process of organic compounds in oil shale, spent catalyst of FCC and powdered activated carbon. This model is based on HSDM (Homogeneous Surface Diffusion Model) model and on the hydraulic behavior of the adsorbent system. Other contribution is the structural and chemical characterization of several samples of oil shale (oil shale, Pirolized oil shale and Pirolized oil shale with Tires) and of the spent catalyst of FCC. A computational model to simulate the adsorption process of these materials is also developed and can be considered an additional contribution of this work. Experimental and simulated results allow characterization of the oil shale adsorbent as basically macroporous and with superficial area about 0.51 to 3.36 m2.g-1. In addition, they present the same crystal structures and clay micrografies characteristics. The adsorbent CAT is composed basically by Faujasite, silica and alumina. They present spherical beads, irregular forms and micropores, with superficial area characteristics of zeolitic materials (148 and 155 m2.g-1). The adsorption tests realized in the synthetic and industrial effluents (Phenolic and Petrochemical) showed the potential of application of the industrial by-products of oil shale and CAT in the removal of organics compounds (dyes, Phenol and COT) of these effluents. In respect of environmental standards to effluents disposal (CONAMA resolution 357), simulations results, obtained with the proposed model, has demonstrated that the use of only oil shale or CAT is not viable, because the high quantity of adsorbents required. However, such adsorbents can be used in the reduction of organic loads in both effluents, when combined with other processes. Each adsorbent showed be used where it is produced because of transportation cost. The CAT is indicated for the treatment of Petrochemical effluent while the others adsorbents may be applied in the phenolic effluent treatment.
Ma, Yuxin. "Empirical and Mechanistic Modelling for Process Understanding in Digital Soil Mapping." Thesis, The University of Sydney, 2019. https://hdl.handle.net/2123/21413.
Повний текст джерелаErland, Samuel. "Characterisation of uncured carbon fibre composites." Thesis, University of Bath, 2017. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.715265.
Повний текст джерелаHidalgo, Durán Felipe Antonio. "Caracterización y cuantificación de los procesos de transporte-reacción que dominan la dinámica intradiaria de dióxido de carbono y oxígeno en el Salar del Huasco." Tesis, Universidad de Chile, 2017. http://repositorio.uchile.cl/handle/2250/150693.
Повний текст джерелаLos salares se ubican típicamente en la región altiplánica andina de Chile, Perú y Bolivia. Los sistemas acuáticos formados en ellos, corresponden usualmente a lagunas extremadamente someras, sometidas a condiciones ambientales desfavorables como bajo oxígeno atmosférico, alta oscilación térmica, alta radiación y fuertes vientos durante las horas del día. Estos ecosistemas están principalmente sustentados por la producción bentónica primaria, la que funciona como alimento para aves de la zona, como los flamencos, ave que se encuentra en estado vulnerable. Debido a lo anterior es que el trabajo de título realizado, consiste en la elaboración de un modelo hidrodinámico de la variación intradiaria de dióxido de carbono y oxígeno en el salar de Huasco, dinámicas que se ven afectadas por los flujos en la interfaz agua-sedimentos, los procesos biológicos de la columna de agua y los flujos en la interfaz aire-agua. El objetivo general es describir y cuantificar los procesos de transporte-reacción de dióxido de carbono y oxígeno en la zona, mediante la elaboración de un modelo hidrodinámico impermanente en 0D del salar, que permita obtener las evoluciones diarias para el oxígeno y el dióxido de carbono, para luego ser validado utilizando mediciones del terreno. El fin de la modelación es adquirir conocimiento acerca de estos fenómenos que pueden afectar considerablemente a los ecosistemas de la zona, únicos en el mundo, adaptados a condiciones climáticas extremas. Inicialmente se realizó un procesamiento de los datos obtenidos en dos campañas de terreno realizadas en los años 2015 y 2016, el que complementado con una revisión bibliográfica orientada a la hidro y biodinámica de sistemas someros, permitió plantear un modelo conceptual que simula las evoluciones intradiarias de dióxido de carbono y oxígeno. Luego se procedió a calibrar y validar el modelo con datos medidos, para finalmente realizar un análisis de sensibilidad que explique los procesos y parámetros más significativos del modelo. El principal resultado del trabajo, corresponde a un modelo que permite cuantificar las variaciones intradiarias de dióxido de carbono y oxígeno. Este modelo permite identificar que los procesos más importantes para el salar corresponden a la producción primaria, y a los flujos de masa en la interfaz aire-agua, tanto para el dióxido de carbono como para el oxígeno. En estos flujos se presentan inconsistencias entre lo que se sabe de la literatura y lo que se observa en el modelo, donde se presentan grandes diferencias entre las tasas de trasferencia en esta interfaz según el compuesto que se esté analizando.
Wu, Tao. "Tooling performance in micro milling : modelling, simulation and experimental study." Thesis, Brunel University, 2012. http://bura.brunel.ac.uk/handle/2438/7211.
Повний текст джерелаSouza, Anderson Gomes. "Modelagem e simulação do processo de absorção reativa de CO2 em modulos de membrana." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266198.
Повний текст джерелаDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
Made available in DSpace on 2018-08-12T00:32:27Z (GMT). No. of bitstreams: 1 Souza_AndersonGomes_M.pdf: 1513239 bytes, checksum: fd19ca410b3d800b0b215aa2175ae192 (MD5) Previous issue date: 2007
Resumo: A redução dos níveis de dióxido de carbono (CO2) é de suma importância, tanto para o combate à poluição atmosférica proveniente de atividades industriais, como no tratamento de correntes gasosas em processos químicos. O método clássico para captura de CO2 engloba sua absorção reativa em solução de aminas, conduzida em colunas de borbulhamento, spray ou recheio. Porém, desvantagens como a formação de espuma e dispersão de fase constituem problemas operacionais significativos desses processos. Alternativamente, módulos de membrana de fibras ocas seriam equipamentos mais adequados para esse fim, apresentando como vantagens uma grande área interfacial e flexibilidade operacional. Nesse sentido, o presente estudo buscou realizar a simulação do processo de absorção de CO2 em módulos de membrana, utilizando soluções aquosas de2-amino-2-metil-1-propanol (AMP), dietanolamina (DEA) e metildietanolamina (MDEA). A modelagem matemática do sistema utilizou expressões da taxa de reação e equações de balanço de massa diferenciais. A resolução numérico-computacional do modelo foi conduzida mediante aplicação dos métodos de colocação ortogonal e de Michelsen, tendo sido implementada em linguagem Fortran. O processo foi estudado em diversas condições operacionais para a análise de sensibilidade paramétrica e os resultados indicam, com base nas características dos diferentes sistemas, as melhores condições gerais de operação. Dentre as aminas consideradas como solventes reativos, as maiores taxas de absorção de CO2 foram previstas com o uso de AMP. Entretanto, sua concentração radial, à saída do módulo de membrana, apresentou forte incidência do fenômeno de depleção da solução absorvedora. Os principais parâmetros que incrementaram a taxa de absorção e, conseqüentemente, a eficiência do módulo de membrana, foram a velocidade de escoamento do líquido absorvente, as concentrações iniciais de CO2 e de amina, o raio interno e o comprimento das fibras.
Abstract: The decrease in the carbon dioxide (CO2) levels is extremely important to avoid atmospheric pollution, from industrial activities, and to the gaseous treatment in several chemical processes. The classical process to the CO2 sequestration involves its reactive absorption into amine solutions, which are carried on bubble, spray or fixed bed columns. However, some disadvantages, such as foam formation and phase dispersion, are serious operational problems to be avoided. Alternatively, membrane modules are supposed to be mode adequate equipments to that aim, which some advantages are great interfacial area and operational flexibility. Under this context, the present study intended to provide the simulation of the CO2 absorption process in hollow fiber membrane module, by using a-amino-2-methyl-1-propanol (AMP), diethanolamine (DEA) and methyldiethanoamine (MDEA) aqueous solutions. The mathematical modeling is based on the inherent rate expressions of the reactive system, besides the differential mass balance equations. The numerical and computational solution was developed by applying the orthogonal collocation and Michelsen methods, which were compiled in Fortran language. The idealized process was studied based on a given standard operational condition, besides a parametric sensibility analysis. The main results, to each sorption system, show the best general conditions to the process operation. Under the standard operation, among the alkanolamines considered as reactive solvents, the best CO2 absorption rate were calculated by using the AMP solution. Nevertheless, its radial concentration tends to suffer the incidence of depletion phenomena in their aqueous solution. The best performance credited to the AMP solution were also confirmed, where the main parameters that increased the absorption rate were the absorbent liquid flow velocity, the initial CO2 and amine concentration, the fibers inner radius and length.
Mestrado
Sistemas de Processos Quimicos e Informatica
Mestre em Engenharia Química
Bandera, Beatrice. "Implementazione di processi funzionali ad uno studio LCA applicato ad un servizio di pulizia in ottica di etichettatura ecologica." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/22061/.
Повний текст джерелаMagnone, Daniel. "Modelling the sources of organic material, processes and timescales leading to arsenic contamination of circum-Himalayan groundwaters." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/modelling-the-sources-of-organic-material-processes-and-timescales-leading-to-arsenic-contamination-of-circumhimalayan-groundwaters(852ae5a1-b09a-44fd-99b3-d8ae2dcc65c6).html.
Повний текст джерелаZaidiza, David Ricardo Albarracin. "Modelling of Hollow Fibre Membrane Contactors : Application to Post-combustion Carbon Dioxide Capture." Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0035/document.
Повний текст джерелаPost-combustion CO2 capture (PCC) is an important strategy in mitigating greenhouse effect. The reference process in PCC is the CO2 absorption into amine aqueous solutions, followed by the regeneration (or stripping) of the solvent. The robustness of packed columns makes it the standard technology for both absorption and stripping steps. However, the treatment of large quantities of flue gases requires itself equipment of a large size. Hollow fibre membrane contactors (HFMC) are considered as one of the most promising strategies for intensified CO2 absorption process, due to their significantly higher interfacial area than that of packed columns, allowing to reduce the equipment size. In addition, this would reduce the energy penalty of the process by reducing the required amount of stripping steam. However, despite the potential advantages of HFMC, very few investigations have studied implementing this technology for PCC within an industrial framework. To fill this lack, the performances of both absorption and stripping steps using HFMC under industrial conditions were estimated by modelling and simulation. To identify the optimal modelling strategy, transfer models with different levels of complexity were developed ranging from one-dimensional isothermal single-component to two-dimensional adiabatic multi-component. Simulation results of both absorption and stripping steps revealed that, compared to traditional packed columns, contactor volume reduction factors comprised between 4 and 10 might be achieved using HFMC. However, since the stripping operating conditions are very close to thermodynamic equilibrium, HFMC can hardly reduce the energy consumption of the process
Araujo, Leandro Goulart de. "Photo-oxidative degradation of bisphenol A by H2O2/UV: process study and kinetic modelling." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-17072018-111837/.
Повний текст джерелаO bisfenol A (BPA) é amplamente utilizado na fabricação de plásticos, resinas epóxi e policarbonatos. Trata-se de um composto tóxico e um desregulador endócrino. Diferentes estudos evidenciam a presença do BPA em diversos compartimentos ambientais em todo planeta, identificando-o como um poluente persistente e resistente à degradação biológica, que apresenta efeitos sinergéticos com outros poluentes. Nesse contexto, os processos oxidativos avançados (POA) têm recebido atenção devido a sua capacidade em degradar poluentes com tais características, transformando-os em compostos menos perigosos ou até mesmo mineralizando-os totalmente. Apesar de haver trabalhos na literatura acerca da utilização de POA para degradação de BPA, estudos sistemáticos dos efeitos de variáveis de processo junto com a interpretação estatística dos resultados são virtualmente inexistentes. Além disso, até onde se sabe um modelo cinético rigoroso ainda não foi proposto para a degradação desse poluente por meio do processo H2O2/UV. Este trabalho teve por objetivo avaliar a degradação do BPA pelo processo H2O2/UV, investigando os efeitos da concentração inicial de H2O2 e da taxa específica de emissão de fótons (EP,0) por meio de um projeto experimental Doehlert, combinado com a análise de superfície de resposta. Os experimentos foram realizados em um reator tubular fotoquímico equipado com uma lâmpada UV de 254 nm, para [H2O2]0 e EP,0 entre 1,6-9,6 mmol L-1 e 0,87 × 1018 - 3,6 × 1018 fótons L-1 s-1, respectivamente. Todos os experimentos sob H2O2/UV resultaram em total degradação do BPA após 60 min de irradiação. Nesse caso, as melhores condições foram [H2O2]0 = 7,6 mmol L-1 e EP,0 = 3,6 × 1018 fótons L-1 s-1, para as quais se obteve o melhor desempenho quanto à taxa de degradação de BPA e à remoção após 15 min, e a segunda maior remoção de COT após 180 min. Entretanto, na maioria dos experimentos menos de 75% de remoção de COT foram observados, com 95% de mineralização obtida apenas para os maiores [H2O2]0 e EP,0. Elaborou-se um modelo matemático que considera as características do reator utilizado e o campo de radiação, baseado no modelo de fonte linear de emissão em planos paralelos (LSPP), combinado à equação de transferência radiativa (RTE), aos balanços materiais e a um modelo cinético detalhado do processo H2O2/UV. Foi empregada a aproximação de estado estacionário para todas as espécies radicalares. Na estimativa das constantes cinéticas desconhecidas, utilizou-se o método de mínimos quadrados não linear. Esse modelo foi capaz de ajustar satisfatoriamente as concentrações experimentais de BPA e de H2O2 em função do tempo. Este trabalho mostra que o processo H2O2/UV constitui uma alternativa conveniente para a degradação de BPA em matrizes aquosas, com total degradação do composto alvo e porcentagem de mineralização adequada nas condições ótimas de operação. Tais condições podem servir como diretrizes iniciais de processamento em escalas piloto e industrial. Por sua vez, simulações empregando o modelo matemático proposto permitem gerar informações úteis para projeto e aumento de escala de processos de pré- ou pós-tratamento de efluentes contendo esse poluente.
Nightingale, Joanne M. "Modelling carbon dynamics within tropical rainforest environments using the 3-PG and 3-PGS ecosystem process models /." [St. Lucia, Qld.], 2004. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe18498.pdf.
Повний текст джерелаSvensson, Magnus. "Carbon dynamics in spruce forest ecosystems - modelling pools and trends for Swedish conditions." Doctoral thesis, Stockholm : Department of Real Estate and Construction Management, Royal Institute of Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4240.
Повний текст джерелаGiacomini, Mattia. "Pressure Swing Adsorption on Carbon Molecular Sieves for Nitrogen Production: Modelling and Simulation with Aspen Adsorption." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/9800/.
Повний текст джерелаPost, Joachim. "Integrated process-based simulation of soil carbon dynamics in river basins under present, recent past and future environmental conditions." Phd thesis, kostenfrei, 2006. http://opus.kobv.de/ubp/volltexte/2006/1150/.
Повний текст джерелаClavera-Gispert, Roger. "Forward numerical modelling of carbonate basins: an ecological approach." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2016. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-213603.
Повний текст джерелаArango, Munoz Paty. "Stripper Modification of a Standard MEA Process for Heat Integration with a Pulp Mill." Thesis, KTH, Kemiteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-289162.
Повний текст джерелаThe 20 largest pulp mills in Sweden emit around 20 million tonnes of CO2 per year. These emissions are considered carbon-neutral since they originate from biogenic sources. The pulp and paper industry is therefore a good candidate for the application of BECCS (Bioenergy with Carbon Capture and Storage) and has the potential to play a significant role for reaching the long-term mitigation target set by the Swedish government that Sweden should be climate-neutral by year 2045. In this thesis, a MEA-based chemical absorption and desorption process was rigorously modelled in Aspen Plus using the rate-based method. Validation of the absorber and stripper model was conducted before the standard process was modified to a configuration that enables heat integration of a significant amount of excess heat from the capture process in, for example, a Kraft pulp mill. CO2 removal rate and rich solvent loading were used as performance indicators to validate the absorber columns. The reboiler duty and lean solvent loading served as performance indicators in the stripper validation. The columns were dimensioned considering 90 wt% capture rate. Efficient use of the entire packing in the absorber and stripper columns was ensured by testing different solvent flow rates. Suitable temperature levels for heat integration, within and across the capture plant, were obtained through an assessment of different versions of a stripper overhead compression configuration. The evaluation of the modified MEA processes took into account the steam conservation potential and energy efficiency potential. The simulation results indicate that the modified stripper may lead to savings of up to 11% in steam consumption. Heat integration between the capture plant and a specific process in a reference Kraft pulp mill resulted in energy savings of the same order of magnitude. Thereby, making the BECCS concept a more attractive solution for the Swedish pulp and paper industry to mitigate climate change.
Chouikhi, Najib. "Production de biométhane à partir de biogaz par technologie de séparation par adsorption PSA : optimisation numérique par approche multi-échelle." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPAST043.
Повний текст джерелаAs global interest in renewable energy intensifies, biogas production continues to grow as a clean, renewable source. Pressure Swing Adsorption (PSA) is considered as one of the most interesting technologies for the valorization of biogas into biomethane. The great flexibility of the PSA process is linked in some way to its complexity with several design and operating parameters which control the performance of the separation unit. The identification of these parameters by an experimental approach is practically impossible. A numerical study stage is essential for sizing the unit, designing the pressure cycle and identifying the optimal operating conditions before any experimental test.The general objective of the thesis was focused on the development of simulation tools for a biomethane purification process using PSA technology.In a first stage, a simulation based on one-dimensional non-isothermal dynamic model, where the intragranular mass transfer kinetics was modelled using a double driving force (bi-LDF) approximation, was implemented. A carbon molecular sieve (CMS-3K) was selected. This adsorbent ensures a high kinetic selectivity of carbon dioxide with respect to methane (CH4). The optimized cycle, composed of five columns and fifteen steps including three equalization steps and a purge gas recycling allowed a CH4 recovery of 92% with a moderate specific energy consumption of 0.35 kWh/Nm3 , at the same time respecting the grid injection specifications (97% CH4 purity ). The performance obtained is thus compatible with industrial operation.The development of a multidimensional (3D) and multi-scale (column/grain/crystal) numerical model would serve to evaluate the limits of the assumptions and correlations used in usual simulators. The first step consists in simulating the gas flow in an adsorbent bed having a reaslistic stacking.. Thus, an inert packed bed was numerically generated by DEM calculation (discrete element modeling) for a column of laboratory size. The use of OpenFOAM (CFD software) allowed to calculate the three-dimensional tracer gas flow in the column. In parallel an experimental study of the breakthrough curves was carried out using a bed having the same dimensions and characteristics. The breakthrough times and the dispersion-diffusion coefficients calculated and measured were similar. However the simulation showed some divergences in the concentration of the tracer locally in the column, due to difficulties in meshing. The next step will consist in taking into account grain-fluid interactions by considering porous adsorbent grains
Panzone, Carlotta. "Etude et optimisation du procédé d’hydrogénation du dioxyde de carbone en hydrocarbures gazeux et liquides." Thesis, Lyon, 2021. https://tel.archives-ouvertes.fr/tel-03789618.
Повний текст джерелаThis thesis is focused on the study of the carbon dioxide hydrogenation reaction towards gaseous and liquid hydrocarbons over a supported K-Fe/Al2O3 catalyst. The subject is part of the framework of the Power-to-X technologies that aim at storing surplus electric power derived from renewable energy into the form of gaseous and liquid chemical compounds. In particular, the electricity is used to perform the water electrolysis to produce hydrogen, then the obtained hydrogen is used to convert carbon dioxide into hydrocarbons. These hydrocarbons can have applications as feedstock in the chemical industry or as fuels in the transport field. The carbon dioxide hydrogenation is a catalytic reaction, generally performed over Fe-based catalysts, consisting in two steps: first, carbon dioxide is converted into carbon monoxide via the reverse water-gas shift reaction (RWGS), and then it is further transformed into hydrocarbons via the Fischer-Tropsch synthesis (FT). One of the main constraints of this reaction is its low selectivity, as a variety of hydrocarbons can be obtained. For an eventual application of this process at the industrial scale, it is necessary to deeper understand and better describe the selectivity of the reaction to optimize the productivity of the desired products. In this work, we have carried out an experimental study of the reaction in a lab-scale fixed bed reactor and developed an analytic protocol that allows the quantification of all the products obtained. Moreover, we have developed a macro-kinetic model that describes with a semi-empirical approach the formation of all the products considered; and a micro-kinetic model, that contributes to give insights about the reaction mechanism. Finally, we have modelled a scaled-up reactor with a heterogeneous and a pseudo-homogeneous approach and we have simulated the global process to estimate its carbon and energy efficiencies
Klein, Christian. "Etude du procédé de densification par caléfaction de composites C/C, modélisation, optimatisation du contrôle et du bilan énergétique." Thesis, Bordeaux, 2015. http://www.theses.fr/2015BORD0231.
Повний текст джерелаThis work has been carried out in the frame of the study of an industrial process for the manufacturing of carbon/carbon (C/C) composite aircraft brake discs. A porous preform made of carbon fibres is immersed in a liquid precursor and is heated by Radio-Frequency electromagnetic induction. The boiling precursor enters the porous preform and yields a carbon deposit in the hottest zones; this deposit will be the carbon matrix of the composite. A physico-chemical process model is proposed in the aim of ensuring its control and optimisation. The work consisted in developing a numerical solver coupling electromagnetic induction heating with heat, mass and species balances accounting for boiling, diffusion and chemical deposition reactions. The model includes the complete electrical circuit of the heating device: it therefore allows real-time, non-destructive monitoring of the infiltration progress through the evolution of the electrical properties. An original formulation has been designed to simultaneously describe the liquid, the gas and the boiling zone; it has been implemented in a commercial Finite Element software package and validated physically with respect to experimental data, with a good agreement. Finally, the simulation software has been used to propose directions for process improvements, through alterations of the inductive heating device geometry or of the heating power supply program
PANTINI, SARA. "Analysis and modelling of leachate and gas generation at landfill sites focused on mechanically-biologically treated waste." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2013. http://hdl.handle.net/2108/203393.
Повний текст джерелаQuezada, Maxwell Josias. "Hydrogénation catalytique de CO₂ en méthanol en lit fixe sous chauffage conventionnel et sous plasma à DBD ZSM-5 surface modification by plasma for catalytic activity improvement in the gas phase methanol-to-dimethylether reaction." Thesis, Normandie, 2020. http://www.theses.fr/2020NORMIR12.
Повний текст джерелаThe objective of this thesis is to contribute to the optimisation of the production of methanol by hydrogenation of CO₂ by synthesising new catalysts in the form of extrudates for industrial use. In this regard, six Cu-ZnO based catalysts supported on alumina and ZSM-5 were prepared and tested. At 36 bar and under conventional heating, the CuZnO/Al₂O₃ showed the best methanol yield. An industrial process based on this catalyst has been proposed and optimised. The influence of extracting water and methanol from the reaction medium using two reactors in series instead of one was investigated and it was found to increase methanol yield considerably. Tests at atmospheric pressure and under DBD plasma showed that the Cu/Al₂O₃ gives better CO₂ conversions, while the CuZnO/ZSM-5 showed better methanol yields. This was attributed to the ionic conductivity and the dielectric constant of the catalysts