Industrie alimentaire | EPFL Graph Search

Lindustrie alimentaire est une filière mondialisée et complexe de personnes et d'entreprises fournissant la plupart des aliments consommés par la population mondiale (de la fourche à la fourchette et en amont et en aval de ce vaste segment économique). Première industrie mondiale à la fin du , elle doit répondre à un besoin vital (manger). Elle le fait via des filières orientées vers la production, la distribution, la transformation, la préparation, la conservation, le transport, la certification et le conditionnement de denrées alimentaires. Depuis la révolution industrielle et l'apparition de la chaîne du froid, elle s'est fortement diversifiée (une myriade de petites activités familiales traditionnelles à forte intensité de main-d'œuvre est remplacée par de grands processus industriels à forte intensité de capital et de plus en plus mécanisés ou robotisés), généralement au profit de grandes multinationales et au détriment de l'indépendance des petits producteurs, artisans et

Web-based tools for energy management in large companies applied to food industry

Damien Muller

This thesis presents a methodology for energy management in large companies and its implementation through a web application and through a prototype of a simulation platform. By combining existing tools in an innovative manner and by making use of recent web technology developments, the methodology adopted provides engineers and managers with tools capable of guaranteeing an efficient and sustainable energy management. Although the methodology presented in this work is based on the experience acquired in the food industry, it can be easily applied in other industrial sectors. The methodology is based on two fundamental approaches commonly used to analyse energy consumption in industrial contexts: the top-down approach and the bottom-up approach. The top-down approach is used in the first place to identify the factories and the specific areas within the factories in which the largest improvement potentials can be achieved. In turn, the bottom-up approach builds on the results from the top-down approach to identify and quantify the energy saving potentials. The top-down approach is implemented through a web application in collaboration with an industrial partner. This application encompasses a modular factory model –accessible to engineers in factories through a user-friendly interface– which enables each factory to define its energy usage, allocate energy costs among the different energy consumers and compute key performance indicators. For a rational cost allocation in multi-service energy conversion units, an exergy-based methodology is presented. The efficiency of energy conversion units defined in the factory model, such as the boilerhouse or the air heaters, is assessed using thermodynamic models. The latter are simplified parametric models derived from accurate thermodynamic models developed in a general flow-sheeting and simulation software to comply with computation time and reliability requirements of the web application. The different factory models defined in the web application can be browsed as part of the proposed top-down approach: starting from a high level overview of the factory –targeted mainly at managers– users can then focus on a specific area of the factory. Strategies are developed to guide users in identifying factories or specific areas within the factories with the largest improvement potentials. They include the use of mechanism to rate the quality of a performance indicator as well as a benchmarking module that allows to compare performance indicators across factories worldwide. In sum, the modular and adaptive aspects of the web application guarantee its long-lasting use. In order to quantify energy saving potentials in the energy conversion units defined in a factory model, "what if?" scenarios are performed in a web-based simulation platform prototype developed in this thesis. This platform acts as a decision-support tool by providing graphical representations of profitability and risk analysis. The platform can be accessed by human users through a web browser while other applications, such as the web application described above, may use the simulation functions through a web service. Statistical tools that can help engineers in defining the factory model described above are also presented. They are used to correlate energy consumption with factors such as production volumes or the climate. Tests to validate the developed correlations are also described. The application of this technique in a factory shows that more than 50% of the energy consumption does not have a direct correlation with production factors and allows to identify improvement potentials. Finally, the concept of a bottom-up approach to identify and quantify energy saving potentials in the different production processes of a factory is presented. A triple representation of the requirements of a process is introduced and applied to process integration in a concrete example. The 80/20 rule is also applied to reduce the complexity of the problem. The optimal integration of cogeneration engines and heat pumps using multi-objective optimisation is also presented.

EPFL2007

Reclamation of low fertility soils using by-products and fast-growing trees

Marc Adami

The world population being increasing, a good energy production management is therefore necessary. Biomass production through short forest rotation by using fast-growing trees appears as a sensible way to limit fossil fuel uses. In Mediterranean regions of south-east Spain, soils present weakened ecosystem with low organic matter and nutrients content which are prone to irremediable degradation processes. The very low fertility of those soils usually makes them unfit to food production and so tree plantation with amendment addition seems to be a possible solution in order to use those soil and improve their qualities. In this study, a low fertility soil was exposed to the addition of two types of amendment (a compost of “Alperujo” and one of biosolid) and to the plantation of two different fast-growing trees (poplars and eucalyptus) during a time period of four months. The soil quality was determined by measuring different selected biochemical (β-glucosidase, phosphatase, dehydrogenase and urease activities), chemical (pH, electrical conductivity, organic matter, phosphate, potassium, water-soluble carbon, N-Kjeldahl, permanganate oxidizable carbon and metal extractible with CaCl2) and plants (nutrients, and trace elements) parameters. No significant differences between the different conditions were found. This was due to the very short time period, the too small doses of compost additions and the very high spatial variability due to the field conditions. It seems however that the composts had a positive effect on the chemical and biochemical parameters in the plots planted with poplars as the results presented systematically higher values for the amended plots than for the control plots (without amendment addition). This was attributed to the fact that all poplars were dead at the time of the study and so the soil was not confronted to any interference by the rhizosphere. Most of the parameters (chemical as well as biochemical) of the soil were improved in the eucalyptus plots compared to the poplar ones. This suggests the stimulation of the nutrient cycles by the tree roots, which improved the conditions for the microorganisms, increasing therefore their metabolic activities. The effect of composts in the eucalyptus plots were therefore clearly less obvious, probably due to the fact that the rhizosphere have had more time (tree planted in July 2011) to influence the soil properties than the compost (added in November 2011). Although both composts contained a non negligible quantity of micronutrients and trace elements, the extractible by CaCl2 0.01M quantities in soil (representing the available quantity for plants) did not present values too high to be toxic for plants and were all in normal ranges. The biomass development of the trees seems to have been improved by the compost of “Alperujo”, but presented a very high spatial variability. The compost of biosolids for its part did not show any difference as compared to the control. Next studies should reveal more significant differences between the plots, the soil having more time to react to the new conditions. It is however recommended to increase the addition doses of composts (double or more) in order to show better their effects

2012

Optimization of sample size and order size in an inventory model with quality inspection and return of defective items

Rafael Batista, Naoufel Cheikhrouhou

To ensure all products as perfect, inspection is essential, even though it is not possible to inspect all products after producing them like some special type products as plastic joint for the water pipe. In this direction, this paper develops an inventory model with lot inspection policy. With the help of lot inspection, all products need not to be verified still the retailer can decide the quality of products during inspection. If retailer founds products as imperfect quality, the products are sent back to supplier. As it is lot inspection, mis-clarification errors (Type-I error and Type-II error) are introduced to model the problem. Two possible cases are discussed for sending back products as defective lots are immediately withdrawn from the system and send back to supplier with retailer's payment and for second case, retailer sends defective products during receiving next lot from supplier with supplier's investment, like in food industry or in hygiene product industry. The model is solved analytically and results indicate that optimal order size and sample size are intrinsically linked and maximize the total profit. Numerical examples, graphical representations, and sensitivity analysis are given to illustrate the model. The results suggest that sending defective products maintaining the first case is the more profitable than the second case.

SPRINGER2018