00535 Modeling of the Fischer-Tropsch synthesis in slurry bubble column reactors

16

Fuel science

and

technology

(fundamental

science,

analysis,

instrumentation)

interactions. This paper describes the development of a scientifically robust and practical physicochemical theory for describing shale deformation. The theory considers chemical and poroelastic processes and couples ion transfer in the mud/shale system to formation stresses and pore pressure. The field equations are derived within the framework of a linear, Biot-like isotropic poroelastic theory. These field equations are solved analytically for the problem of a wellbore in shale to yield the solute mass fraction, pore pressure, and the stress distributions around the borehole. The solution is developed using the generalized plane strain approach and is used to study the impact of solute transfer on stress and pore pressure fields. The analyses indicate that solute transfer causes the chemical-osmosis to become timedependent, As time increases, the transfer of ions leads to osmotic pressure dissipation and re-establishment of a pore pressure regime characteristic of hydraulic flow. Furthermore, it is observed that while the wellbore may be supported by a mud pressure of significant magnitude, the rock can experience a tensile effective radial stress due to the physicochemical interaction between the shale and the drilling mud. Hence, the contribution of the physicochemical processes can significantly impact the stress and pore pressure distributions around a borehole and should be considered when optimizing drilling mud properties. 04/00531 Losses of chemical energy in hard-coal energyutilization exothermic processes Mokrzycki, E. and Olkuski, T. Applied Energy, 2003, 23, (3-4), 289295. In the sequence of occurrence, these processes are the losses in coal production, processing losses, and the losses in electrical-energy generation. These losses are evaluated. 04/00532 Low cost catalytic sorbents for NO, reduction. 2. Tests with no reduction reactives Lazaro, M. J. et al. Fuel, 2003, 82, (7), 771-782. Coal, char and activated char doped with model vanadium compounds (VzOs and NH4V0s) and petroleum coke ash, PCA, (main metal components: V, Fe and Ni) have been tested as catalytic sorbents for NO reduction without the addition of a reduction reactive. The sorbents prepared have shown to be active for NO reduction at temperatures higher than 350°C. The most efficient sorbents are those obtained from unactivated chars and doping with model vanadium compounds or PCA does not upgrade significantly their behaviour. On the other hand, for the samples prepared from activated char, an improvement of the reduction efficiency is observed after impregnation with model vanadium compounds or PCA. SSA of the samples does not play a relevant role on the NO reduction efficiency while surface chemistry significantly affect the samples’ behaviour: higher the COz/ CO ratio determined by TPD, higher the NO reduction efficiency of the sample. Slightly higher NO conversions are observed for the samples loaded with pure compounds but PCA is perspective for producing catalyst doped activated carbons. 04/00533 Mechanical behaviour of macro-dispersed inert matrix fuels Neeft, E. A. C. et al. Journal of Nuclear Materials,2003, 317, (2-3), 217-225. Macro-dispersed inert matrix fuels were irradiated in the high flux reactor in Petten. These fuels consisted of U02 inclusions embedded in the inert matrices MgO, MgA1204, Y3A150t2, CeOzmx and YZ03. The uranium burn-up reached 17.1-19.8X FIMA after an irradiation period of 198.9 days. The sample temperature was about 700-1000 K. Room temperature indentation measurements were performed in the inert matrices before and after irradiation to determine the Vickers hardness and the fracture toughness. The volume swelling of the UOz inclusions has been determined. Pellets of UOz inclusions embedded in MgO, MgA1204 and Y3A150i2 show cracks in the matrix between these inclusions after neutron irradiation. A model is used to describe the fracture behaviour of these inert matrix fuels. 04/00534 Mineral oil residues on HVAC components: measuring methods Asikainen, V. et al. B&ding and Environment, 2003; 38, (8), 1057-1061. A method to determine the amount of oil residues on heating-, ventilatingand air-conditioning (HVAC)-component surfaces was developed and validated. The sampling was based on two swiping methods and a filter contact method. Infrared spectrometry was utilized in the analyses. For the tested mineral oil the filter contact method showed the best recovery of the sampling 91+2%. The oil concentration is quite high but unequally distributed (530-960 mg/m’) on the surface of the sheet metal treated with corrosion protection oil and low on the sheets treated with chromic acid (~2-29 mgim’). Oil concentration of studied HVAC components (14-196 mg/m’) was dependent on the technique used for manufacturing the component. 64

Fuel

and

Energy

Abstracts

January

2004

04/00535 Modeling of the Fischer-Tropsch synthesis in slurry bubble column reactors Rados, N. et al. Catalysis Today, 2003, 79-80, 211-21X. A multi-component one-dimensional dynamic mathematical model for the reacting slurry systems with a change in gas flow rate due to the chemical reaction is developed. A change in gas flow rate caused by the chemical reaction is modelled using the overall gas mass balance. Thus, all relevant chemical species are included in the model. Linear firstorder reaction kinetics is considered. The gas phase is modelled using the two-bubble class hydrodynamic model. The interaction between small and large bubbles is included as the cross-flow. Suspension of liquid and solids is assumed to form a pseudo slurry phase. Backmixing in all of the three considered phases, small bubbles, large bubbles and slurry, is accounted for using the axial dispersion model (ADM). Energy balance of the slurry phase is also included in the model. The developed general reacting slurry system model is used to simulate the performance of the Fischer-Tropsch slurry bubble column reactor. Performance of the developed ADM-based model is compared with the reactor scale models in which the reactor back-mixing is represented using some combination of the two limiting ideal reactor models of, complete stirred or plug flow. 04/00536 Modelling of the flow behavior of activated carbon cloths using a neural network approach Faur-Brasquet, C. and Le Cloirec, P. Chemical Engineering and Processing, 2003, 42, (8-9), 645-652. This work investigates the hydrodynamic and aerodynamic behaviours of recent adsorbents, activated carbon cloths. A first part presents their characteristics, a particular attention being given to the properties related to their woven structure. The influence of these characteristics on air and water pressure drops through ACC is shown by experimental measurements. It is established that a classic model set up for particular media, the Ergun model, does not enable a satisfying modelling of experimental data. An artificial neural network (ANN) is then used in order to include as explicative factors the cloths properties. The optimization of the ANN architecture is carried out, in terms of selection of the input neurons and number of hidden neurons. The generalization ability of the ANN is evaluated using a test dataset distinct from the training set. The influence of specific characteristics of cloths on their flow behaviour is confirmed by an analysis of inputs sensibility, and the determination of their predictive influence. 04/00537 Neural network approach to support modelling of chemical reactors: problems, resolutions, criteria of application Molga, E. J. Chemical Engineering and Processing, 2003, 42, (8-9), 675695. New aspects of neural modelling of chemical reactors have been investigated in this study. An universal method to create a family of neural models, useful for the reactor and reacting system of any type, has been elaborated and presented. Based on this method a detailed analysis of the neural models has been performed. The proposed methods of modelling as well as a comparative analysis of the obtained results have been illustrated with the data obtained for a complex, catalytic hydrogenation of 2,4-dinitrotoluene performed at non-steady state conditions in a multiphase stirred tank reactor. The methods of choosing the input-output signals, the net architecture, the learning method, the number and quality of learning data have been proposed and their influence on the accuracy of obtained predictions have extensively been discussed. A comparison of two types of neural models: a global neural model and a hybrid neural model to a conventional reactor modelling has been performed. General conclusions and useful criteria have been formulated. 04/00538 Non linear model of the gas introduction module for plasma density control at JET Piccolo, F. et al. Fusion Engineering and Design, 2003, 66-68, 741-747. The gas introduction module (GIM) is the basic system used in Joint European Torus (JET) to provide the vacuum vessel with the amount of gas necessary for a successful plasma discharge. The plasma density feedback system controls the GIM piezo-electric valve allowing the desired amount of gas to flow in the vacuum vessel. The unavailability of a flow measurement is the main reason for the development of an accurate flow model, able to predict and calculate the number of particles flowing within an acceptable error margin. This paper describes a GIM model that uses the control signal of the piezoelectric valve to compute the pressure evolution inside the GIM reservoir and, using the pressure estimation, obtains the particles flow considering also the dynamic heat exchange effect between the gas and the structure of the GIM. 04/00539 Novel catalyst design Centi, G. and Perathoner, S. Catalysis

for multiphase Today, 2003,

reactions 79-80, 3-13.