Polymer spiral film gas-liquid heat exchanger for waste heat recovery in exhaust gases

Antoine Breton
2012
Projet étudiant

Résumé

In this master thesis report the development of an innovative spiral heat exchanger based on polymer materials is described. Building prototypes, erection of a test bench and firsts tests of the heat exchanger are presented. The heat exchanger prototype survived all tests especially several days in contact with aggressive gases. A facility integrating a Diesel exhaust gases production has been developed to test this heat exchanger design. Performance results obtained during the tests are analysed. Measurement acquisition software developed with Labview was also used. Challenges have been overcome to run the facility in stable conditions in order to obtain reliable measurement. Heat load recovery achieved with the presented heat exchanger is in the range of 1.5 kW thermic but potential heat recovery about 3.5kW might be achievable. Overall heat transfer coefficient is improved compared to other polymer based heat exchanger design. Pressure drop on gas channel is in the range of several mbar and must be further improved and fouling must be minimized. Such a design based on polymer film technology provides better corrosion and chemical resistance compared to conventional metal heat exchangers. Due to the smooth surface of polymer film fouling is reduced. Series production and usage of such heat exchangers would allow operating low temperature waste heat recovery in gases at affordable costs. One promising application is heat recovery in soiled gases in combination with ORC power generation.

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https://infoscience.epfl.ch/record/182331?ln=fr

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Antoine Breton
2012
Projet étudiant

Résumé

Official source

https://infoscience.epfl.ch/record/182331?ln=fr

À propos de ce résultat

Concepts associés (18)

Concepts associés

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Publications associées (39)

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Chargement

Approche de conception et d’optimisation de centrale solaire intégrée à cycle combiné inspirée de la méthode du pincement (partie II: réseau d’échangeurs de chaleur)

Daniel Favrat, El Hadj Malick Kane

Steam production units (HRSG and HSSG) of ISCCS include several heat exchangers (economizers, evaporator, superheater, reheaters, etc.). The knowledge of the extended composites as a function of the solar input, allows the determination of the most critical zones for heat transfer but does not allow, in itself, the full knowledge of the real streams needed to be able to design an optimum heat exchanger network. The procedure proposed in this paper permits, from so called interaction factors which characterize the interdependancy between streams, the determination of the massflows in each stream. The choice of the best heat exchanger network must respect, for each operational conditions, the optimum evaporation levels (including pressures et temperatures) determined in part I, as well as the particular practical operational factors (independance or not between the various heat recovery units, etc.). The network design is done using the standard guidelines of pinch technology (respect of the minimum pinch DTmin for each heat exchanger close to the pinch temperature, separate design of the zone above and below the pinch temperature, etc.). The respect of the DTmin in the critical zones of heat transfer requires the use of stream splitting and the network includes heat exchanger tubes which are interlaced at the same level of the stack. One example of the best performing power plant designed on the basis of this approach is given.

1999

Chargement

Process Integration: From Continuous to Batch Processes.

Daniel Favrat, Pierre Krummenacher

Among the structure independent approaches of process integration, pinch technology has been shown for continuous processes to be extremely powerful to develop energy efficient processes and enhance synergic effects within and between processes. The earlier focus of the method has mainly been concerned with a minimization of the heat transfer exergy losses based on a given economic criterion. However, there is a need to increasingly consider environmental and other life cycle aspects as early as possible in the design phase. This trend has stimulated the need to extend the method including its handy graphical representations to also include the other major exergy losses (dissipation and equipment fabrication losses). A new approach proposed by Staine et al. (1995, 1996, 1999) provides a coherent framework for representing the overall exergy balance as well as the simultaneous representation of both heat and electricity balances of the process or plant being analyzed. Examples of application of this so-called extended pinch analysis method to a few continuous industrial processes will be shown. The second part of this presentation will deal with another challenging goal, which is the energy integration of batch processes. Batch processing is the preferred mode of operation whenever flexibility is a key issue. Although this mode of operation is mainly used for low volume, high value products, noticeable exceptions do exist, such as brewing which is an energy intensive, large volume process. Methodologically the analysis and design of the heat integration of batch processes is complex due to the time dimension and the large number of degrees of freedom or alternatives to be addressed (e.g. assignment of equipment to tasks, scheduling, modes of heat recovery, possible re-use of heat exchanger units). So-called "non-flowing streams" (e.g. in-vessel heating or cooling) add to the complexity, and many fine chemical processes feature time-temperature profiles making data extraction a difficult task. Particularities and practical constraints have to be taken into account in order for the solutions to make sense; fortunately, these constraints often rule out a number of alternatives, considerably restricting the solution space. Strategies based on mathematical programming have also been proposed; several of them provide with the advantage of simultaneously addressing the scheduling issue, but with the drawback of a restricted scope of application. These methods will however not be specifically addressed here. Batch processes often include in-vessel heat transfer tasks characterized by small heat transfer areas with large temperature degradations across the reactor wall (resulting from both a low heat transfer coefficient and the request for maximum heat rates to save valuable time & production capacity). Therefore one of the very first analysis step is to consider the feasibility of external pre-heating and cooling during loading/transfer between vessels.

2000

Chargement

The pulp and paper (P&P) industry in industrially mature countries is facing a long-term crisis. Large and modern manufacturing facilities in tropical regions emerge as new competitors. The constant increase of energy costs has also contributed to the financial difficulties encountered in the industry. To stay viable and sustainable, P&P mills need to elaborate new strategies to increase their revenues. In this context, converting a P&P mill into an integrated forest biorefinery could be the solution to restore the health of the industry and overcome the crisis. Diversifying the industry's product mix by producing bio-energy and bio-materials could be a way to penetrate new markets while maintaining its core production of pulp and paper. Producing bio-materials implies energy consumption and waste heat. The energy management cannot therefore be dissociate from the biorefinery integration in a P&P mill: both energy and mass integration must be considered. The objective of this work is to illustrate the trade-off between conversion of materials and of energy and shows the importance of considering simultaneously the heat recovery through heat exchangers and the combined heat and power production. Process integration techniques have been applied to study a bisulfite mill which produces pulp and three additional by-products: bioethanol, lignosulfonate and yeast. Particular attention was devoted to the integration of the chemical recycling loops which have a significant impact on the process energy balances and therefore influence the choice of biorefinery integration strategies. A key element of the process integration pathway was to consider the heat cascade as a model of the heat exchanger network by decoupling the installed heat exchangers network when analysing the potential effects of the recycling and production strategies at the plant level. Using this model, the optimal integration of a combined heat and power production unit was determined taking into account the simultaneous maximisation of process internal heat recovery. To facilitate the computational formulation of the problem, the overall process was subdivided into several production sub-systems with flow diagrams and flow rates dependant on the main product being manufactured in each sub-system. Mass balance constraints were introduced to model the flow distribution between sub-systems and the hot and cold streams were computed by means of a conventional flowsheeting software. The corresponding hot and cold streams were subsequently integrated at the mill scale level. The pulp production line and energy conversion equipment such as the sulphur boiler, lignin boiler and the biomass boilers were simultaneously optimized.

2009

Chargement

Process Integration: From Continuous to Batch Processes.

Daniel Favrat, Pierre Krummenacher

2000

2009