Dissertação(mestrado) - Universidade Federal do Rio Grande, Programa de Pós-Graduação em Engenharia e Ciência de Alimentos, Escola de Química e Alimentos, 2008. / Submitted by Caroline Silva (krol_bilhar@hotmail.com) on 2012-09-24T18:12:59Z No. of bitstreams: 1 dissertao ana priscila centeno da rosa.pdf: 832074 bytes, checksum: f714a15c9e2b09a517b32f01fb11ef36 (MD5) / Approved for entry into archive by Bruna Vieira(bruninha_vieira@ibest.com.br) on 2012-12-01T01:10:48Z (GMT) No. of bitstreams: 1 dissertao ana priscila centeno da rosa.pdf: 832074 bytes, checksum: f714a15c9e2b09a517b32f01fb11ef36 (MD5) / Made available in DSpace on 2012-12-01T01:10:48Z (GMT). No. of bitstreams: 1 dissertao ana priscila centeno da rosa.pdf: 832074 bytes, checksum: f714a15c9e2b09a517b32f01fb11ef36 (MD5) Previous issue date: 2008 / Spirulina (Arthrospira) é uma microalga fotossintética, encontrada em ambientes alcalinos e é uma das mais produzidas no mundo. Sua biomassa possui alto valor nutricional e agregado. Apresenta alto teor protéico e é rica em compostos bioativos, como aminoácidos essenciais, ácidos graxos, pigmentos e vitaminas. Um sistema de produção de biomassa microalgal depende de muitos fatores, entre eles, o desenvolvimento de um meio de cultivo economicamente viável. O objetivo do presente trabalho foi estudar a influência da concentração de nutrientes no meio de cultivo para a produção da microalga Arthrospira em biorreatores tipo “raceway” e modo semicontínuo. Para os cultivos foi utilizado meio Zarrouk que teve as fontes de carbono, nitrogênio e fósforo mantidas nas concentrações padrões e os demais nutrientes (solução B) foram variados em 25% (Z-B25), 50% (Z-B50), 75% (Z-B75) e 100% (Z-100). Foram realizados ensaios com diferentes volumes do meio de cultura, 5L e 2 500 L. Nos ensaios realizados em biorreatores com volume de meio de 5 L a velocidade específica máxima de crescimento e a produtividade foram reduzidas com o consumo dos nutrientes pela microalga. Os máximos valores de velocidade específica de crescimento (0,184 d-1) e produtividade (48,03 mg.L-1.d-1) foram observados no ensaio Z-B50. Os ensaios Z-B50 e Z-B75 apresentaram velocidade específica máxima de crescimento e produtividade sem diferença significativa (p>0,15) a partir do terceiro ciclo de crescimento. No inicio do terceiro ciclo as concentrações de nitrogênio e fósforo apresentaram reduções de 21,2 e 15,7% (Z-B50) e 29,9 e 12,9% (Z-B75), respectivamente. Para cada ensaio foram realizadas análises de composição química da biomassa a cada ciclo de crescimento do cultivo. O maior teor protéico (48,8±4,1%) foi encontrado na biomassa de Arthrospira no ensaio Z-100. O ensaio ZB50 apresentou biomassa contendo 46,10±2,59% de proteína por um período de, aproximadamente, 50 d. Os cultivos em biorreatores com volume de meio de 2 500 L foram realizados em condições ambientais não controlas e foi utilizado água da Lagoa Mangueira para diluição do meio Zarrouk. A temperatura e a iluminância variaram de 16 a 42ºC e 26,3 a 105,2 klux, respectivamente. As máximas velocidades específicas de crescimento e produtividades, respectivamente, 0,276 d-1 e 148,36 mg.L-1.d-1 (ZB50) e 0,368 d-1 e 95,60 mg.L-1.d-1 (Z-100), foram encontradas no período com maior média de temperatura,. Para estes ensaios, a concentração de proteína na biomassa não apresentou diferença significativa (p>0,05). A concentração de lipídios na biomassa, ao final dos ensaios, apresentou redução em relação a concentração inicial de 22 e 52% para os ensaios Z-B50 e Z-100, respectivamente. / Spirulina (Arthrospira) is a photosynthetic microalgae found in alkaline environmental and it is one of the most produced in the world. The chemical composition of Spirulina’s biomass indicates that it has high nutritional value due its composed of a wide range of biologically active compounds, such as vitamins, pigments, fatty acids and essential amino acids. A production system of microalgae biomass depends on several factors, such as, the development of economic culture medium. The objective of this work was studied the influence of nutrients concentration on culture medium for the production Arthrospira microalgae in open raceway ponds and semicontinuous process. For the experiments, was used Zarrouk’s medium, where carbon, nitrogen and phosphorous sources were used at standard concentration and the concentration of the others nutrients (B-solution) were varied to 25% (Z-B25), 50% (Z-B50), 75% (Z-B75) and 100% (Z-100). Two experiments were performed with different culture medium volume, 5 L and 2 500 L. In an experiment performed with medium volume of 5 L, was observed a reduction on maximum specific growth rate and productivity according the nutrients consumed by microalgae. The maximum values of specific growth rate (0.184 d-1) and productivity (48.03 mg.L-1.d-1) were observed an experiment Z-B50. After the third growth cycle, the maximum specific growth rate and productivity didn’t show significant difference (p>0.15) for experiments Z-B50 and Z-B75. In the beginning of the third cycle, nitrogen and phosphorous concentrations showed a reduction of 21.1 and 15.7% for Z-B50 medium, 29.9 and 12.9% for Z-B75, respectively. For each cycle growth, analyses of chemical composition were performed from the biomass of each experiment. The highest protein content (48.8±4.1%) was found out in the Arthrospira biomass at Z-100 test. In the essay Z-B50, the biomass protein content was 46.10±2.59% for a period of 50 days, approximately. The process on bioreactor that used 2 500 L of medium volume, was carried out in environmental conditions and was utilized Mangueira Lagoon water for dilution Zarrouk’s medium. The temperature and illumination were varied between 16 to 42ºC and 26.3 to 105.2 klux, respectively. The maximum specific growth rate and productivity were, 0.276 d-1 and 148.36 mg.L-1.d-1 (ZB50) and 0.368 d-1 and 95.60 mg.L-1.d-1 (Z-100), respectively, found out in a period that presented the highest average temperature. For these experiments, the protein concentration of biomass did not show significant difference (p>0.05), already, the lipid concentration showed a reduction when compared an initial concentration of 22 and 52% for Z-B50 and Z-100 experiments, respectively.

The concepts of continuity for set-valued mappings were introduced by G. Bouligand and K. Kuratowski. There are two ways defining differentiability of set-valued mapping. One is defined by classical differentiability theorem and another is defined by normal cone which was introduced by B.S. Mordukhovich. In this thesis, we survey various definitions of continuity and differentiability for set-valued mapping.

Dissertação(mestrado)- Universidade Federal do Rio Grande, Programa de Pós-Graduação em Engenharia e Ciência de Alimentos, Escola de Química e Alimentos, 2010. / Submitted by Caroline Silva (krol_bilhar@hotmail.com) on 2012-08-30T16:18:53Z No. of bitstreams: 1 dissertao adriano arruda henrard.pdf: 1485086 bytes, checksum: f5665b2804865ca150fc4f99a546ffe6 (MD5) / Approved for entry into archive by Bruna Vieira(bruninha_vieira@ibest.com.br) on 2012-09-03T19:18:51Z (GMT) No. of bitstreams: 1 dissertao adriano arruda henrard.pdf: 1485086 bytes, checksum: f5665b2804865ca150fc4f99a546ffe6 (MD5) / Made available in DSpace on 2012-09-03T19:18:51Z (GMT). No. of bitstreams: 1 dissertao adriano arruda henrard.pdf: 1485086 bytes, checksum: f5665b2804865ca150fc4f99a546ffe6 (MD5) Previous issue date: 2009 / As microalgas se destacam por apresentarem diversas potencialidades, como fonte de alimento, obtenção de bioprodutos, produção de biocombustíveis e também podem contribuir na redução do efeito estufa, fixando CO2. As microalgas apresentam em sua composição alto teor de proteínas, ácidos graxos, minerais e pigmentos e, além disso, a microalga Chlorella possui certificado GRAS (Generally Recognized As Safe), podendo ser utilizada como alimento sem oferecer risco à saúde humana. Industrialmente, o cultivo semicontínuo de microalgas é muito empregado, pois com esse tipo de cultivo é possível a manutenção da cultura em crescimento por períodos mais prolongados, procedendo-se apenas a alimentação periódica do meio novo. O objetivo deste trabalho foi estudar o crescimento das microalgas Cyanobium sp. e Chlorella sp. cultivadas em modo semicontínuo e diferentes condições nutricionais e de processo. Assim, este trabalho foi dividido em 3 etapas: na primeira, objetivou-se estudar os cultivos das microalgas Cyanobium sp. e Chlorella sp. em diferentes condições nutricionais e de processo; na segunda etapa, avaliou-se o cultivo semicontínuo da microalga Cyanobium sp. em fotobiorreator tubular vertical de 2 L e na terceira, estudou-se o cultivo da microalga Chlorella sp. em modo semicontínuo em fotobiorreator aberto tipo raceway de 6 L. Para avaliar o melhor meio nutriente e agitação, os cultivos foram realizados em fotobiorreatores tipo erlenmeyer e raceway de 0,5 L e 6 L, respectivamente. Os cultivos foram realizados em condições controladas, estufa climatizada a 30ºC, 3200 Lux e fotoperíodo 12 h claro/escuro. O melhor meio de cultivo para as microalgas Cyanobium sp. e Chlorella sp. foi o meio BG11 com adição de bicarbonato de sódio, onde foram obtidas as maiores concentrações celulares (0,56 e 0,66 g.L-1), velocidades específicas de crescimento (0,303 e 0,166 d-1) e produtividades (0,120 e 0,089 g.L-1.d-1), respectivamente. Quando cultivadas sob diferentes agitações, as melhores respostas foram obtidas nos ensaios realizados com agitação por 2 bombas submersas, com concentrações máximas de biomassa 1,21 e 0,93 g.L-1 para Cyanobium sp. e Chlorella sp, respectivamente. Para o cultivo em modo semicontínuo da microalga Cyanobium sp., a máxima velocidade específica de crescimento foi 0,127 d-1 quando o cultivo foi realizado com concentração de corte 1,0 g.L-1, taxa de renovação 50% e concentração de bicarbonato de sódio 1,0 g L-1. Os máximos valores de produtividade (0,071 g.L-1.d-1) e número de ciclo (10) foram observados em concentração de corte 1,0 g.L-1, taxa de renovação 30% e concentração de bicarbonato 1,0 g.L-1. No cultivo semicontínuo com Chlorella sp., a maior velocidade específica de crescimento (0,149 d-1) foi obtida quando cultivada com 1,6 g.L-1 de bicarbonato de sódio e concentração de corte 0,6 g.L-1. A maior produtividade (0,091 g.L-1.d-1) foi obtida quando utilizado no cultivo concentração de corte 0,8 g.L-1, taxa de renovação de meio 40% e concentração de bicarbonato de sódio 1,6 g.L-1. Os resultados mostraram que o cultivo em modo semicontínuo é uma alternativa para maximizar a produção de microalgas, além disso, o sistema de cultivo deve ser escolhido não apenas pela maior produtividade, mas também de acordo com as características desejadas do produto. / Microalgae had gain attention for presenting diverse potentialities, as source of food, attainment of bioproducts, produce biofuels and also can contribute in the greenhouse effect reduction, fixing CO2. Microalgae presents in its composition high contents of protein, fatty acids, minerals and pigments, moreover, microalgae Chlorella possess the GRAS (Generally Recognized As Safe) certificate, being able to be used as food without offering any risk to the human health. The semicontinuous microalgae cultivation is very used, because of the long period cells maintenance, being necessary the periodic feeding of new cultivation medium. The objective of this work was to study the growth of the microalgae Cyanobium sp. and Chlorella sp. cultivated in semicontinuous mode and different nutritional and process conditions. This work was divided in three stages: in the first, the aim was to study the cultivation of the microalgae Cyanobium sp. and Chlorella sp. in different nutritional and process conditions; in the second stage, the semicontinuous cultivation of the microalgae Cyanobium sp. in vertical tubular photobioreactor of 2 L was evaluated; in the third, the culture of the microalgae Chlorella sp. was studied in semicontinuous mode in open photobioreactor type raceway of 6 L. To evaluate the best medium nutrient and agitation conditions, cultures were carried out under in photobioreactors type erlenmeyer and raceway of 0,5 L and 6 L, respectively. Cultures were carried out under controlled conditions, climatized greenhouse at 30ºC, 3200 Lux and 12 h photoperiod light/dark. The best culture medium for the microalgae Cyanobium sp. and Chlorella sp. was the BG11 medium with sodium bicarbonate addition, where were obtained the highest cell concentrations (0,56 and 0,66 g.L-1), specific growth rate (0,303 and 0,166 d-1) and productivity (0,120 and 0,089 g.L- 1.d-1), respectively. When cultivated under different agitation conditions, the best answers were obtained with agitation given by 2 submerged pumps, with maximum biomass concentrations 1,21 g.L-1 for Cyanobium sp. and 0,93 g.L-1 for Chlorella sp. For the culture in semicontinuous mode of the microalga Cyanobium sp., the maximum specific growth rate was 0,127 d-1 in the culture with cell concentration 1,0 g.L-1, renewal rate 50% and sodium bicarbonate concentration 1,0 g.L-1. The maximum productivity values (0.071 g.L-1.d-1) and cycle number (10) had been observed in cell concentration 1,0 g.L-1, renewal rate 30% and 1,0 g.L-1 bicarbonate concentration. In the semicontinuous culture with Chlorella sp., the highest specific growth rate (0,149 d-1) was gotten when cultivated with 1,6 g.L-1.d-1 of sodium bicarbonate and cell concentration 0,6 g.L-1). The highest productivity (0,091 g.L-1.d-1) was gotten when cell concentration 0,8 g.L-1, medium renewal rate 40% and sodium bicarbonate concentration 1,6 g.L-1 were used in the culture. Results had shown that semicontinuous mode culture is an alternative to maximize the microalgae production, moreover, the culture system must not only be chosen by the highest productivity, but also in accordance with the desired characteristics of the product.

<p>Environmental concerns about greenhouse gas emissions and energy security are the main drivers for the production of alternative fuels from bio-based feedstock. Dimethyl ether has attracted interest of many researches and is touted as “A fuel for the 21^st century” due to its versatility. However, the production of DME from biomass is dependent on the overall economics of its production.</p> <p>This thesis considers the application of semicontinuous distillation to improve the economics of the separation section in a biomass-to-DME facility. Semicontinuous distillation systems operate in a forced cycle to effect multiple separations using a single distillation column integrated with a middle vessel. The control system plays an integral role in the driving the forced cycle behaviour of the process in which no steady state exists.</p> <p>The separation section consists of a series of flash drums followed by a distillation train consisting of three (3) columns. In the first phase of this work, a semicontinuous system was developed to achieve the separation of the second and third distillation columns in the separation section. Rigorous models were used to simulate the semicontinuous system in which several control configurations were evaluated. The final control structure based on classic PI control was shown to achieve the specification objectives of the system and handle disturbances while avoiding weeping and flooding conditions. Optimization followed by an economic analysis showed that the semicontinuous system was economically preferable to the traditional continuous process for a range of DME production rates.</p> <p>Next, a semicontinuous system was developed to achieve the separation of the first and second distillation columns in the separation section. In this phase the application of semicontinuous distillation was extended to partial condenser configurations and the separation of biphasic mixtures. The control structure developed was effective in handling disturbance, attaining specification objectives while remaining with operational limits. An economic analysis, however, showed the traditional continuous configuration to be more economical for all DME production rates. Findings show that the operating cost is highly depending on the middle vessel purity so while uneconomical for this process it could result in favourable economics for less stringent purity specifications.</p> / Master of Applied Science (MASc)

Distillation technology has been evolving for many decades for a variety of reasons, with the most important ones being energy efficiency and cost. As a part of the evolution, semicontinuous distillation was conceived, which has the advantages of both batch and continuous distillation. The economic benefits of this intensified process compared to batch and continuous distillation were expounded in many of the previous studies. Semicontinuous distillation of ternary mixtures, which is the main focus of this thesis, is carried out in a single distillation column with a tightly integrated external middle vessel and the operation is driven by a control system. The system operation does not include any start-up or shut-down phases of the column and has three periodically repeating operating modes. In the status quo design procedure, called the ‘sequential design methodology,’ an imaginary continuous distillation system design was used to design the semicontinuous distillation system. In this methodology, dynamic simulations of the process were used to find the values of the controller tuning parameters based on the design of the continuous system. Afterwards, black-box optimization was used to find better controller tuning parameter values that minimized cost. However, after analyzing the dynamics of the system for different cases, it was found that the heuristics used in this design methodology yielded suboptimal designs. Therefore, the primary goal of the thesis is to improve these heuristics by incorporating more knowledge of the system and thereby develop a better design methodology. Firstly, the setpoint trajectories generated by the ideal side draw recovery arrangement for side stream flowrate control, which was standard in most semicontinuous distillation studies, was modified. In this thesis, the performance of the status quo as compared to the modified version, based on the criteria, cycle time and cost for different case studies, was presented. Results showed that the modified-ideal side draw recovery arrangement for side stream flowrate control performed better with a 10-20% lower separating cost while maintaining product purities. Furthermore, to reap more cost benefits, dynamic optimization was used to seek the flow rate trajectory that minimized cost. However, it was found that the additional cost savings, which is in addition to the benefits gained by using the modified version, were at the most 2% from different case studies. Subsequently, the impact of changing the imaginary continuous distillation system design on the nature of the semicontinuous distillation limit cycle, specifically, its period was studied. Results revealed the necessity for a new design procedure, and thus the back-stepping design methodology was proposed. This design methodology was used to find better limit cycles of zeotropic ternary semicontinuous distillation using the aspenONE Engineering suite. The proposed methodology was applied to three different case studies using feed mixtures with different chemical components. A comparison with the sequential design methodology for the two case studies indicates that the new method outperforms the state-of-the-art by finding limit cycles that were 4% to 57% lower in terms of cost. Furthermore, the designs obtained from this procedure were guaranteed to have feasible column operation with stable periodic steady-state behaviour. Semicontinuous distillation design using the design methodology with heuristic components involves guessing, checking and then using black-box optimization to find the values of the design variables to meet some performance criteria. Furthermore, mathematical guarantees of either local or global optimality of the designs obtained from the design procedure do not exist. Therefore, to address these issues, in this thesis, the application of using the shooting method for designing the semicontinuous distillation process was demonstrated using two case studies, which involve the separation of hexane, heptane and octane. This method has the potential to be combined with gradient-based optimization algorithms for optimization of the process design in the future. / Thesis / Doctor of Philosophy (PhD)

Orientadores: Miriam Dupas Hubinger, Rosiane Lopes da Cunha / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-04T15:44:33Z (GMT). No. of bitstreams: 1 SanjinezArgandona_ElianaJanet_D.pdf: 1300468 bytes, checksum: c20ca032f56d49e321e696c01f4057ad (MD5) Previous issue date: 2005 / Doutorado / Doutor em Engenharia de Alimentos

The separation of four or more components traditionally requires the use of three or more distillation columns. Due to the associated high costs, process intensification techniques have been studied. Semicontinuous separation is one method that allows multiple separations using one column integrated with middle vessels. This thesis aims to develop a new semicontinuous separation process that can separate a mixture with four or more components into high purity products with one column and two or more middle vessels. It is an extension of the conventional ternary semicontinuous process, which has been repeatedly shown to be profitable at intermediate throughputs when compared to continuous systems. The semicontinuous process operates in a forced cycle, with three operating modes that ensure separation objectives are met. The performance of the proposed quaternary semicontinuous separation is analyzed through rigorous dynamic simulations over a range of production capacities. To determine the feasibility, operability, and applicability to non-ideal mixtures, three case studies were considered: 1. Equimolar mixture of alkanes (n-hexane; n-heptane; n-octane; n-nonane). 2. Equimolar mixture of aromatics (benzene; toluene; ethyl-benzene; and o-xylene). 3. Non-ideal mixture of mixed-alcohols (methanol, ethanol, and water; propanol; isobutanol; pentanol and hexanol) The extendibility of the quaternary semicontinuous separation process, referred to as quintenary semicontinuous separation, is then evaluated on a five-component alkane mixture (n-hexane; n-heptane; n-octane; n-nonane; n-decane), via three case studies: 1. Equimolar mixture 2. Non-equimolar mixture, rich in light and heavy components. 3. Non-equimolar mixture, rich in intermediate components. The results for both the quaternary and quintenary semicontinuous processes indicate that this new technique is successful at achieving separation objectives while staying within safe operating limits. Comparison of both equimolar mixtures of alkanes for quaternary and quintenary semicontinuous processes with continuous systems indicates that the proposed system is profitable for intermediate flow rates. / Thesis / Master of Applied Science (MASc) / Traditionally, several large distillation columns (that can be hundreds of feet tall) are required to split a mixture of liquid chemicals into its individual components. Distillation is the separation of mixtures due to differences in boiling points. When the mixture is heated, the vapour phase will contain the components with lower boiling points, which can be separated once the vapour phase is cooled and condensed. The main goal of this research is to create a new system that can carry out the same separation, but using complex techniques that require only one column and a few extra storage tanks that are much cheaper and smaller than a distillation column. Different liquid mixtures were used to show how well the new process is able to separate the liquid into its individual components, while remaining in safe operating limits.

Due to the remote and dispersed nature of Alberta’s oil wells, it is not economical for the energy industry to capture all of the solution gas produced and as a result, the gas is being flared and vented in significant amounts. The objective of this research is to aid in the conversion of solution gas into dimethyl ether (DME) in a remote location by designing a distillation column that purifies DME and its reaction by-products, carbon dioxide, methanol and water. In order to develop an implementable solution, the distillation equipment must fit inside of a 40-foot shipping container to be transported to remote locations. Given the size constraint of the system, process intensification is the best strategy to efficiently separate the mixture. Several process intensification distillation techniques are explored, including semicontinuous distillation, the dividing wall column (DWC) and a novel semicontinuous dividing wall column (S-DWC). The traditional semicontinuous distillation column purifies DME to fuel grade purity, however the other components are not separated to a high enough grade given the height constrain of the system. The DWC and S-DWC both purify DME to its desired purity along with producing high purity waste streams. The S-DWC purifies the reaction intermediate methanol to a grade slightly higher than the DWC and is pure enough to recycle back to the reactor. An economic comparison is made between the three systems. While the DWC is a cheaper method of producing DME, the trade-off is the purity of the methanol produced. Overall, this research shows that it is possible to purify DME and its reaction by-products in a 40-foot distillation column at a cost that is competitive with Diesel. / Thesis / Master of Applied Science (MASc)

Data-driven model predictive control framework of semicontinuous distillation process / Distillation technology is one of the most sought-after operations in the chemical process industries. Countless research has been done in the past to reduce the cost associated with distillation technology. As a result of process intensification, a semicontinuous distillation system is proposed as an alternative for purifying the n-component mixture (n>=3) which has the advantage over both batch and continuous process for low to medium production rates. A traditional distillation setup requires n-1 columns to separate the components to the desired purity. However, a semicontinuous system performs the same task by integrating a distillation column with n-2 middle vessel (storage tank). Consequently, with lower capital cost, the total annualized cost (TAC) per tonne of feed processed is less for a semicontinuous system compared to a traditional setup for low to medium throughput. Yet, the operating cost of a semicontinuous system exceed those of the conventional continuous setup. Semicontinuous system exhibits a non-linear dynamic behavior with a cyclic steady state and has three modes of operation. The main goal of this thesis is to reduce the operating cost per tonne of feed processed which leads to lower TAC per tonne of feed processed using a model predictive control (MPC) scheme compared to the existing PI configuration This work proposes a novel multi-model technique using subspace identification to identify a linear model for each mode of operation without attaining discontinuity. Subsequently, the developed multi-model framework was implemented in a shrinking horizon MPC architecture to reduce the TAC/tonne of feed processed while maintaining the desired product purities at the end of each cycle. The work uses Aspen Plus Dynamics simulation as a test bed to simulate the semicontinuous system and the shrinking horizon MPC scheme is formulated in MATLAB. VBA is used to communicate the inputs from MPC in MATLAB to the process in Aspen Plus Dynamics. / Thesis / Master of Science in Chemical Engineering (MSChE)

Nous étudions la minimisation du périmètre et de l'énergie de Willmore en présence de contraintes ainsi que le flot, défini par les mouvements minimisants, de l'énergie de Willmore. Les problèmes d'optimisation géométriques et les flots que nous considérons reposent sur une propriété de semi-continuité inférieure que nous pouvons assurer en prenant l'enveloppe semi-continue inférieurement des énergies incluant les contraintes.Dans la première partie de la thèse, nous étudions trois problèmes d'optimisation. Le premier concerne le périmètre avec une contrainte de connexité. Le second est un problème de reconstruction de domaine à partir de sections planaires. Cette reconstruction est basée sur la minimisation du périmètre ou de l'énergie de Willmore avec des contraintes d'inclusion-exclusion. Nous développons un modèle de champ de phase pour implémenter numériquement la reconstruction en 2D et 3D à partir de contraintes d'inclusion-exclusion variées. Le troisième problème est l'étude des propriétés des courbes fermées, confinées dans un ouvert borné du plan, minimisant l'énergie élastique (Willmore).La deuxième partie étudie le flot de l'énergie de Willmore par les mouvements minimisants. Le flot pour une surface régulière est difficile à analyser, entre autre car il peut développer des singularités en temps fini. L'enveloppe semi-continue inférieurement et les mouvements minimisants permettent de définir un flot en temps long pour des surfaces moins régulières. Ce flot est étudié dans deux situations : pour la somme de l'énergie de Willmore et du périmètre dans le plan et pour l'énergie de Willmore des fonctions radiales à profil décroissant en toute dimension / We study the minimisation with constraints of the perimeter and of the Willmore energie and the flow of the Willmore energie, defined by minimising movements. The geometric optimisation problems and flows we handle rely on a lower semicontinuous property that we enforce by taking the lower semicontinuous envelop of the energies including the constraints.In the first part of the thesis, we consider three optimisation problems. The first one deals with the perimeter and connectedness constraints in the plan. The second one is a reconstruction problem of a volumetric domain from planar slices. This reconstruction is based on the minimisation of the perimeter or of the Willmore energy with inclusion-exclusion constraints. A phase field numerical approach and experiments are implemented. The third problem is the study of closed curves confined in an open bounded subset of the plane that minimise the bending energy (or Willmore energy). The second part of the thesis studies the Willmore flow defined by minimising movements. The flow of a regular surface is complex to analyse and may develop singularities in finite time. We use the lower semicontinuous envelop of the Willmore energy and the minimising movement to define a long time flow for surfaces with less regularity. This flow is studied within two contexts: for the sum of the Willmore energy and the perimeter in the plane and for the Willmore energy of radial functions with a non-increasing profile in any dimension