Analyse de l'impact des incertitudes du procédé de bio-séchage sur sa viabilité économique

Le secteur des pâtes et papiers nord-américain cherche des solutions pratiques pour la gestion des boues provenant du traitement des eaux usées. Le pouvoir calorifique supérieur des boues est similaire mais légèrement inférieur à celui du bois. Cependant, une grande différence réside dans leur siccité. Les boues ont une siccité entre 25% et 40% en sortant des procédés de déshydratation mécanique, alors que le bois a une siccité qui varie entre 40% et 60%. Une siccité de 40% représente un minimum pour que l‟énergie libérée [par quoi?] soit supérieure ou égale à l‟énergie nécessaire à l‟évaporation de l‟eau et au chauffage du combustible à son point d‟ignition. Le séchage de la boue est donc nécessaire pour s‟assurer que celle-ci contribue au bon fonctionnement de la chaudière. Un procédé de séchage proposé est le bio-séchage vertical en continu. Le bio-séchage est un procédé qui utilise l‟aération forcée ainsi que la chaleur dégagée par l‟activité biologique. Le procédé est similaire au compostage aérobic, mais les buts des deux procédés sont différents. L‟objectif du bio-séchage est d‟augmenter la valeur calorifique inférieure de la biomasse, en augmentant le niveau de siccité et en limitant la dégradation biologique. Dans le but d‟installer le bio-séchage dans des usines papetières de manière économiquement viable, la présente maîtrise cherche à effectuer une mise à l‟échelle industrielle d‟une usine pilote et à évaluer les implications de la combustion des boues séchées sur les conditions d‟opération d‟une chaudière à lit fluidisé. Un modèle économique indiquant les bénéfices majeurs pour les usines papetières utilisant le procédé de bio-séchage a été développé pour une boue mixte en considérant principalement l‟efficacité du lit fluidisé et la réduction de carburant fossile au niveau de la chaudière. Les données expérimentales obtenues à partir de l‟usine pilote ont permis d‟effectuer une conception préliminaire d‟un réacteur de bio-séchage vertical en continu et modulaire. Les caractéristiques principales sont présentées dans le tableau 1. vi Tableau 1 Caractéristiques principales du réacteur de bio-séchage à pleine échelle Hauteur (m) 5,0 Largeur (m) 3,0 Profondeur (m) 20,0 Volumes (m3) 300,0 Temps de séjour (jour) 3 Débit d‟air (m3 air /h /m3 réacteur) 28 Taux de recyclage (%m/m) 15% Système de décharge Planchers coulissants Contrôle des polluants gazeux Combustion dans la chaudière ou bio-filtre Le modèle technico-économique qui a été développé pour l‟unité de séchage et la chaudière a été appliqué à trois études de cas d‟usine papetière dans l‟Est du Canada. Ce modèle inclut les coûts en capital liés à l‟installation du bio-séchoir, les coûts d‟opération de la chaudière et du séchoir et les effets sur l‟efficacité de la chaudière de différents mélanges de carburants. Le bio-séchage a ensuite été comparé au séchoir rotatif, qui est une option de séchage populaire. L‟application du modèle aux études de cas a permis de montrer que dans le cas où la boue est actuellement brûlée, le bio-séchage a pour effet d‟augmenter l‟efficacité du lit fluidisé. Dans le cas où la boue est actuellement envoyée au dépotoir, son séchage et sa combustion ont pour effet de diminuer l‟efficacité du lit fluidisé, du fait que du combustible fossile est substitué par de la boue séchée. Le modèle technico-économique a aussi permis de déterminer les conditions favorables au bio-séchage: dans le cas où l‟usine envoie actuellement ses boues mixtes au dépotoir, et cela malgré la baisse d‟efficacité de la chaudière, et dans la situation où la vii consommation de carburant fossile peut être réduite. Cependant une comparaison avec le séchoir rotatif a montré que celui-ci est plus rentable, avec un délai de récupération de 0,85 an versus 1,5 an pour le bio-séchage. -------- North America‟s pulp and paper industry has been searching for better solutions regarding the management of waste water treatment sludge. The high heating value of sludge is slightly lower than that of wood. However, a big difference exists between their dryness levels. Sludge has dryness levels of between 25% and 40% after mechanical dewatering, whereas wood has dryness levels varying between 40% and 60%. A dryness of at least 40% is required to ensure that the generated energy is superior to the energy necessary to evaporate water and bring the fuel to its ignition point. Drying the sludge is pivotal to ensure the positive effect of its combustion in the boiler. The vertical continuous biodrying process is therefore proposed as a drying process. Biodrying is a drying process that uses forced aeration and biological heat. This process is very similar to aerated composting, but the goal of each process is different. Biodrying‟s objective is to improve the low heating value of biomass, by raising the sludge‟s dryness and limiting the biological degradation. With the goal to install biodrying in a multitude of P&P mills and in a viable economical manner, the following thesis looks into the scale-up of a pilot plant and identifies the effects of dryer sludge‟s combustion on the operating conditions of a fluidized bed boiler. An economic model identifying major benefits for P&P mills that implement biodrying in the form of a reduction of fossil fuel consumption from an increase in the sludge‟s low heating value and an increase in the efficiency of the boiler. Experimental data and order of magnitude analysis of the pilot plant have permitted the conception of a modular vertical continuous biodrying reactor presented in tableau 2. ix Tableau 2 Principal characteristics of the full scale vertical biodrying Height (m) 5,0 Depth (m) 3,0 Width (m) 20,0 Volume (m3) 300,0 Residence time (days) 3 Air flow (m3 air /h /m3 réacteur) 28 Recycling ratio (%m/m) 15% Discharge system Push floor Air pollution control Combustion in the boiler or bio-filter A techno-economic model for the dryer and the boiler was created and applied to three case study mills from Eastern Canada. The model determines the capital costs linked to the installation of the biodryer, the operating costs of the boiler and dryer and the effects on the efficiency of the fluidized bed boiler when utilizing different fuel combinations. The model was also used to compare the biodrying process with the rotary dryer, a popular drying option. The application of the model to the case studies has demonstrated that in the example of sludge that is burned in a boiler, drying the sludge leads to an increase in the efficiency of the fluidized bed boiler. If the sludge was sent to a landfill, the drying and combustion of the sludge leads to a decrease in fossil fuel consumption, but also a decrease of the fluidized bed‟s efficiency. This decrease in the fluidized bed efficiency is a result of high energy fuel being substituted for sludge, introducing more moisture to the boiler. The techno-economic model has made determining the conditions in which biodrying is most cost effective possible: if the mill sends mixed sludge to a landfill even with the boiler‟s efficiency decrease, and when fossil fuel x consumption can be reduced. However a comparison with the rotary dryer has demonstrated that the rotary dryer is more profitable, with a payback period of 0.85 years versus 1.5 years for biodrying

L'adaptation des minorités ethniques une étude réalisée au cégep de Saint-Laurent /

Résumé: p. i-iiÉgalement disponible en version papierTitre de l'écran-titre (visionné le 5 déc. 2009)Bibliogr.: p. 175-17

L'adaptation des minorités ethniques une étude réalisée au cégep de Saint-Laurent /

Résumé: p. i-iiÉgalement disponible en version papierTitre de l'écran-titre (visionné le 5 déc. 2009)Bibliogr.: p. 175-17

Autonomous rendezvous and docking: A commercial approach to on-orbit technology validation

The Space Automation and Robotics Center (SpARC), a NASA-sponsored Center for the Commercial Development of Space (CCDS), in conjunction with its corporate affiliates, is planning an on-orbit validation of autonomous rendezvous and docking (ARD) technology. The emphasis in this program is to utilize existing technology and commercially available components whenever possible. The primary subsystems that will be validated by this demonstration include GPS receivers for navigation, a video-based sensor for proximity operations, a fluid connector mechanism to demonstrate fluid resupply capability, and a compliant, single-point docking mechanism. The focus for this initial experiment will be expendable launch vehicle (ELV) based and will make use of two residual Commercial Experiment Transporter (COMET) service modules. The first COMET spacecraft will be launched in late 1992 and will serve as the target vehicle. The ARD demonstration will take place in late 1994, after the second COMET spacecraft has been launched. The service module from the second COMET will serve as the chase vehicle

The Feasibility of Quantitatively Characterizing the Vehicle Motion Environment (VME)

https://deepblue.lib.umich.edu/bitstream/2027.42/154108/1/ervin1990.pd

L'adaptation des minorités ethniques une étude réalisée au cégep de Saint-Laurent /

Résumé: p. i-iiÉgalement disponible en version papierTitre de l'écran-titre (visionné le 5 déc. 2009)Bibliogr.: p. 175-17

3D spheroid models for in vitro evaluation of nanoparticles for cancer therapy

Many different nanoparticle delivery systems have been reported as potential cancer therapeutics, however, the tumour penetration and uptake characteristics have been determined for very few systems. Animal models are effective for assessing tumour localisation of nanosystems, but difficult to use for studying penetration beyond the vasculature. In this work, defined HCT 116 colorectal cancer spheroids were used to study the effect of nanoparticle size and surface modifications on their penetration and uptake. Incubation of spheroids with Hoechst 33342 resulted in a dye gradient which facilitated discrimination between the populations of cells in the core and at the periphery of spheroids by flow cytometry based on the degree of Hoechst staining. This model was used to compare doxorubicin and Doxil, a range of model polystyrene nanoparticles in different sizes (30 nm, 50 nm, 100 nm) and with different surface chemistry (50 nm unmodified, carboxylated, aminated) and polyethylene glycol modified NPs prepared from a promising new functionalized biodegradable polymer (poly(glycerol-adipate), PGA). Unmodified polystyrene nanoparticles (30 nm/50 nm) were able to penetrate to the core of HCT 116 spheroids more efficiently than larger polystyrene nanoparticles (100 nm). Penetration was also dependent on surface charge. PGA NPs of 100 nm showed similar penetration into spheroids as 50 nm polystyrene nanoparticles, and PEG surface modification significantly improved penetration into the spheroid core. The new spheroid model with Hoechst staining is shown to be a useful model for assessing NPs penetration and demonstrates the importance of controlling physical properties when designing nanomedicine

Autonomous satellite docking system

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76348/1/AIAA-2001-4527-378.pd

Automatic spacecraft docking using computer vision-based guidance and control techniques

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76754/1/AIAA-21001-304.pd

Enhanced uptake in 2D- and 3D- lung cancer cell models of redox responsive PEGylated nanoparticles with sensitivity to reducing extra-and intracellular environments

In the treatment of lung cancer, there is an urgent need of innovative medicines to optimize pharmacological responses of conventional chemotherapeutics while attenuating side effects. Here, we have exploited some relatively unexplored subtle differences in reduction potential, associated with cancer cell microenvironments in addition to the well-known changes in intracellular redox environment. We report the synthesis and application of novel redox-responsive PLGA (poly(lactic-co-glycolic acid)) -PEG(polyethylene glycol) nanoparticles (RR-NPs) programmed to change surface properties when entering tumor microenvironments, thus enhance cell internalization of the particles and their drug cargo. The new co-polymers, in which PEG and PLGA were linked by ‘anchiomeric effector’ dithiylethanoate esters were synthesized by a combination of ring-opening polymerization and Michael addition reactions and employed to prepare NPs. Non redox-responsive nanoparticles (nRR-NPs) based on related PLGA-PEG copolymers were also prepared as comparators. Spherical NPs of around 120 nm diameter with a low polydispersity index and negative zeta potentials as well as good drug loading of docetaxel were obtained. The NPs showed prolonged stability in relevant simulated biological fluids and a high ability to penetrate an artificial mucus layer due to the presence of the external PEG coating. Stability, FRET and drug release studies in conditions simulating intracellular reductive environments demonstrated a fast disassembly of the external shell of the NPs, thus triggering on-demand drug release. FACS measurements and confocal microscopy showed increased and faster uptake of RR-NPs in both 2D- and 3D- cell culture models of lung cancer compared to nRR-NPs. In particular, the ‘designed-in’ reductive instability of RR-NPs in conditioned cell media, the fast PEG release in the extracellular compartment, as well as a diminution of uptake rate in control experiments where extracellular thiols were neutralized, suggested a partial extracellular release of the PEG fringe that promoted rapid internalization of the residual NPs into cells. Taken together, these results provide further evidence of the effectiveness of PEGylated reducible nanocarriers to permeate mucus layer barriers, and establish a new means to enhance cancer cell uptake of drug carriers by extra-and intra-cellular cleavage of protein-and cell-shielding hydrophilic blocks