Search

Your search keyword '"Hartge, E.‐U."' showing total 40 results
Start Over Author "Hartge, E.‐U."
40 results on '"Hartge, E.‐U."'

7. The Role of Attrition and Solids Recovery in a Chemical Looping Combustion Process Effet de l’attrition et de la récupération des particules dans le procédé de combustion en boucle chimique

Author

Kramp M., Thon A., Hartge E.-U., Heinrich S., and Werther J.

Subjects
Chemical technology, TP1-1185, Energy industries. Energy policy. Fuel trade, HD9502-9502.5
Abstract

In the present work, the steady-state behavior of a Chemical Looping Combustion process of interconnected fluidized bed reactors is simulated. The simulations have been carried out in two different scales, 50 kWth and 100 MWth. Attrition model derived from small scale laboratory experiments has been employed for the prediction of the process behavior in terms of attrition and Oxygen Carrier loss. Information on Oxygen Carrier characteristics and reaction kinetics were taken from literature. Realistic circulation mass flows of Oxygen Carrier particles are obtained and Oxygen Carrier losses are quantified. The large scale process looses significantly more Oxygen Carrier than the small scale process based on the same amount of thermal energy produced. Incomplete conversion in the air reactor could be identified as a critical point. Another issue is the fuel gas bypassing the Oxygen Carrier particles through bubbles in the large scale process which leads to lowered fuel conversions. The simulations indicate that a similar performance of a pilot scale and a large scale process is not guaranteed due to the scale-up effect on fluid dynamics. Furthermore, the simulations allow an assessment of the influence of the quality of the solids recovery system on the Oxygen Carrier loss. The distribution of the losses between possible origins is investigated and different changes in the solids recovery system are discussed regarding their potential to decrease the Oxygen Carrier loss. For example, the addition of a second-stage cyclone after the air reactor of the large scale process reduces the Oxygen Carrier loss significantly. Le présent travail propose un modèle de simulation en continu du procédé de combustion en boucle chimique constitué de deux lits fluidisés interconnectés. Les simulations ont été conduites à deux échelles 50 kWth correspondant à une installation pilote et 100 MWth correspondant à une installation industrielle. Un modèle décrivant l’attrition, établi à partir d’expériences conduites à petite échelle au laboratoire, a été utilisé pour étudier l’évolution de la granulométrie et des pertes aux cyclones des particules transportant l’oxygène dans le procédé. Des débits de circulation de particules réalistes sont calculés par simulations et les pertes aux cyclones peuvent être quantifiées. Rapportées à la puissance de l’installation, les pertes en particules aux cyclones sont plus élevées à l’échelle industrielle qu’à l’échelle pilote. Il a également été observé qu’à l’échelle industrielle on obtient une conversion plus faible de la charge gazeuse dans le réacteur fioul à cause du by-pass induit par les bulles dans ce réacteur. Sur la base des simulations, il n’est donc pas garanti que les performances soient identiques à l’échelle pilote et à l’échelle industrielle à cause de l’hydrodynamique. Avec le simulateur, il est également possible d’étudier l’impact du système de récupération des particules dans les effluents gazeux sur les pertes. La répartition des pertes entre le réacteur air et le réacteur fioul est étudiée avec différentes configurations. Il est, par exemple, montré que l’ajout d’un deuxième étage de cyclone en sortie du réacteur air permet de réduire significativement les pertes en matériau transporteur d’oxygène.

Published
2011
Full Text
View/download PDF

16. Aufbau einer Vollverwertungskette für ligninhaltige Biomasse über Hochdruckverfahrenstechnik: Neue Produkte durch Extraktion, Hydrolyse, überkritische Trocknung und Extrusion

Author

Andersen, L., primary, Conrad, M., additional, Gil, J., additional, Hu, X., additional, Reynolds, W., additional, Schmidt, L. M., additional, Hartge, E. U., additional, Häring, H., additional, Kreft, C., additional, Meyer, R., additional, Zetzl, C., additional, Heinrich, S., additional, Kaltschmitt, M., additional, Lim, C., additional, and Smirnova, I., additional

Published
2018
Full Text
View/download PDF

21. Co-firing of biomass and other wastes in fluidised bed systems

Author

Gulyurtlu, I, Lopes, H, Boavida, D, Abelha, P, Werther, J, Hartge, E.-U., Wischnewski, R, Leckner, B, Åmand, L.-E., Davidsson, K, Salatino, P, Chirone, R, Scala, F, Urciuolo, M, Oliveira, J.F., Lapa, N, Morais, J., Heidenhof, N., Dugwell, D., Paterson, N., Kandiyoti, R., Schiavetti, M., Donatini, F., Yürüm, Yuda, and Dumanlı, Ahu Gümrah

Subjects
TP Chemical technology
Abstract

A project on co-firing in large-scale power plants burning coal is currently funded by the European Commission. It is called COPOWER. The project involves 10 organisations from 6 countries. The project involves combustion studies over the full spectrum of equipment size, ranging from small laboratory-scale reactors and pilot plants, to investigate fundamentals and operating parameters, to proving trials on a commercial power plant in Duisburg. The power plant uses a circulating fluidized bed boiler. The results to be obtained are to be compared as function of scale-up. There are two different coals, 3 types of biomass and 2 kinds of waste materials are to be used for blending with coal for co-firing tests. The baseline values are obtained during a campaign of one month at the power station and the results are used for comparison with those to be obtained in other units of various sizes. Future tests will be implemented with the objective to achieve improvement on baseline values. The fuels to be used are already characterized. There are ongoing studies to determine reactivities of fuels and chars produced from the fuels. Reactivities are determined not only for individual fuels but also for blends to be used. Presently pilot-scale combustion tests are also undertaken to study the effect of blending coal with different types of biomass and waste materials. The potential for synergy to improve combustion is investigated. Early results will be reported in the Conference. Simultaneously, studies to verify the availability of biomass and waste materials in Portugal, Turkey and Italy have been undertaken. Techno-economic barriers for the future use of biomass and other waste materials are identified. The potential of using these materials in coal fired power stations has been assessed. The conclusions will also be reported.

Published
2006

37. Modeling of Industrial Fluidized-Bed Reactors

Author

Werther, J. and Hartge, E.-U.

Abstract

A modeling approach is presented that is able to handle the most important aspects of industrial fluidized-bed reactors. A particular focus is to describe the relationship between catalyst attrition, solids recovery in the reactor system, and chemical performance of the fluidized-bed reactor. The competing influences of attrition of the catalyst particles and efficiency of the solids recovery lead to the etablishment of a catalyst particle size distribution in the bed inventory, which, in turn, influences via the hydrodynamic characteristics of the fluidized bed and, thereby, the performance of the chemical reactor. The usefulness of this approach is illustrated with model calculations for a fictituous first-order reaction in which the fluidized bed is equipped with different solids recovery systems including one single-stage cyclone, several cyclones in parallel, and two- and three-stage cyclone systems. Model calculations illustrate the importance of a high efficiency of solids recovery to keep the fines in the system which is decisive for a high performance of the reactor. The calculations reveal that it might take months until a quasi-steady state of the bed particle size distribution is obtained.

Published
2004

38. Simulation of 2-D Temperature Distributions in Fluidized Bed Reactors for Highly Exothermic Reactions

Author

Artlich, S., Hartge, E.-U., and Werther, J.

Abstract

Fluidized bed reactors are generally known for their temperature uniformity, but with highly exothermic reactions, significant temperature gradients may occur. The generation of temperature distributions inside the fluidized bed is the result of a competition between two mechanisms:  local feeding of reactants creates heat of reaction locally, and this heat must be dispersed inside the bed by solids mixing. The present work investigates these mechanisms for the case of coal combustion in pressurized bubbling fluidized beds. With a simple one-dimensional carbon mass balance, the governing parameters for the generation of temperature profiles are deduced. For the quantitative calculation of temperature, carbon and oxygen distributions, a two-dimensional model was formulated. In pressurized fluidized beds, the fuel is often fed as a coal-water slurry, so the drying of the fuel also has been considered in this model. The model has been validated with measurements made in the pressurized fluidized bed combustor (PFBC) pilot-scale test unit of Deutsche Babcock. The results are in good agreement with measurements for full-load as well as part-load conditions. Feeding the coal as a slurry is shown to be a means to flatten the temperature distribution because the slurry agglomerates are dispersed in the fluidized bed while drying. Further simulation results point at and quantify critical parameters that have to be considered in the scaleup of pressurized fluidized bed combustors.

Published
1998

Catalog

Books, media, physical & digital resources
See catalog results