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02419 Distributed activation energy model of heterogeneous coal ignition
16 Fuel science and technology (fundamental science, analysis, instrumentation) Dimensioning nomograms for the design of fixed97102418 bed solid-gas thermochemical reactors with various geometrical configurations Stitou, D. and Crozat, G. Chemical Engineering and Procrssing, Feb. 1997, 36, (1) 45-58. Simulation models which allow the dimensioning of fixed-bed solid-gas reactors are essential to the development of solid-gas thermochemical transformers. All of the models developed so far are based on a dynamic modelling of the process describing the temporal evolution of the principal elements of which the machine consists. However, the dimensioning of the machine becomes a very complex and time-consuming operation. In this paper dimensioning nomograms have been developed in order to enable a designer to quickly produce dimensioning of a fixed-bed solid-gas reactor, thus making decision making at the early stages of a project feasible. These nomograms have been set up from a simplified analytical model which considers the average functional characteristics of a thermochemical reactor over a given time step. Finally, several applied examples are given to demonstrate the various possibilities, as well as the simple usage of these dimensioning nomograms.
Distributed geneous coal ignition
97102419
activation
energy model of hetero-
Chen, J. C. Comhus~. Flame, 1996, 107, (3). 291-298. A simulation model for the conventional tube-furnace experiment used for ignition studies is presented. The Distributed Activation Energy Model for Ignition accounts for particle-to-particle variations in reactivity by having a single pre-exponential factor and a Gaussian distribution of activation energies among the particles. The article also shows that adjustments to the model parameters permit a good correlation with experimental data.
Exergy analysis of solid-oxide
97102420
fuel-cell (SOFC)
systems Bedringis, K. W. er al. Energv, April 1997, 22, (4). 403-412. This study made use of the exergy concept in order to analyse two methanefueled SOFC systems. The systems include preheating of fuel and air, reforming of methane to hydrogen, and combustion of the remaining fuel in an afterburner. A newly developed iterative computer program using a sequential-modular approach was used for the analyses.
Experimental confirmation of the theoretical prediction of the gas hold up and circulation velocity in Internal loop alr lift reactor and the possibilities of scale up
97102421
Langfelder, G. E. G. et al. Per. Coal, 1996, 38, (2) 47-51. Measurements of gas hold up and liquid circulation rates in an internal loop air lift reactor were performed with air-water mixtures, under different pressures with the aim to check the validity of the theoretical model, proposed by E. Garcia Calvo et al. (1991). Reasonable agreement was found for the experimental results, with exception of the high gas flow rates, when the deviation from the model becomes significant. These deviations are caused by the gas recirculation through the down-comer, the effect of which is not included in the model.
Experimental plan for the assessment of air toxic emissions from a pilot-scale combustion unit
97102422
Pm-. Annu. Int. Pirtshurgh Coal Co@., Hargis, R. A. and Pennline, H. W. 1995, 12, 997-1002. In this experiment; the operation of a 500-lb-per-hour pilot-scale combustion unit was characterized in terms of the formation, distribution, and fate of toxic substances. A description of the pilot unit and expected operating conditions during the air toxics testing is provided, along with a summary of the test plan. This test plan is designed to obtain the necessary data on the concentration of trace elements associated with the vapour phase, particulate phase, and particulate size fraction enabling a comparison of these results from the pilot unit and the full-scale utility. Based on the results of this air toxics characterization effort, an assessment is made of the value of the pilot unit as a facility for the evaluation of sampling and analysis improvements, development of continuous emissions monitors, and future control systems evaluations.
97102423 Experimental study of the kinetics of gasificationmetric carbon transformation in fly ash of pulverized coal-fired thermal power plants Tarasevich, V. N. Prom. Teplofekh., 1995, 17, (6), M-69. (In Russian) The gasification-metric transformation of carbon contained in the fly ash of the largest thermal power plants in Ukraine and Russia, operating on pulverized coal fuel from different coal basins is presented as a kinetic study. The author reports the relationships between the output signal of gasification-metrical transducer of mechanical incomplete burning and the temperature of gasification reaction.
Fischer-Tropsch synthesis doped) ETS-10 titanium silicate catalysts
97102424
on Co and Co(Ru-
Caral. Left., 1996, 41. (1,2), 79-82. Bianchi, C. L. et al. The authors found titanium silicate ETS-10 to be a suitable support for metal catalysts because of its high surface area, high-ion-exchange capability and no acidic functions. In this paper, the M-ETS-10 commercial form (where M stands for Na and K) was first exchanged with Co and thus tested in CO hydrogenation (Fischer-Tropsch synthesis). Moreover, the
192
Fuel
end
Energy
Abstracts
May 1997
sample was also doped with small amounts of ruthenium to improve the Co reducibility. The successive catalytic tests revealed a strong increase in the CO conversion and a modification in the selectivity of the hydrocarbon fractions.
97102425 Fundamentals of thermodynamics, and fluid mechanics
heat transfer,
Hassani, V. and Hauser, S. CRC Handb. Energy Effic., 1997, 19-99. Edited by Kreith, F, and West, R. E. CRC, Boca Raton, FL. The authors review the principles of thermodynamic. heat transfer, and fluid mechanics that an engineer needs to know in order to analyse or design an energy conversion system.
Gas-potentiometric method with solid electrolyte oxygen sensors for the investigation of combustion
97102426
J. Anal. Chem., 1996, 356, (3-4) 215-220. Lorenz, H. et al. Fresenius' Using stabilized zirconia as oxide-ion-conducting solid electrolytes, potentiometric gas analysis was used to determine specific parameters of gas and fuel oil flames (e.g. flame contour, degree of burn-out, and mixing). It was also applied to obtain information about flame turbulence and reaction density from the temporal resolution of the sensor signal, Measurements carried out with solid-electrolyte 02 sensors in a fluidized bed showed that combustion processes of solid fuels could also be analysed. These analyses resulted in fuel-specific burn-out curves, finally leading to burn-out times, to macrokinetics parameters of the combustion, and to some suggestions about the burn-out mechanism. From the resulting constants of the effective reaction rate, a reactivity relative to bituminous coal coke can be given for any solid fuel.
Identification and characterization of macerals by digital image processing
97102427
Scharfenberg, R. and Hesse, D. Glueckauf-Forschrrngrh. 1996, 57, (2), 7% 82. (In German) Digital image processing formed the basis for a new method for the determination of vitrinite maturity in coal. The magnified part of the sample was transferred from the microscope to the computer with the help of a computer connected with a CCD-camera and a light-microscope (magnification 1:500). The macerals representing parts of the image were characterized by high grey-scale gradients at the borders of the macerals. The mean grey value of the macerals as a function of the vitrinite reflection grade was obtained.
97102428 Improvement in the measurement of diffusion coefficients in a restricted diffusion cell: case of binary electrolytes Mathurin Nzikou, J. et ul. Chemical Engineering and Processing, Apr. 1997, 36, (2). 161-165. The paper deals with measuring the diffusion coefficient of an electrolyte by the restricted diffusion method. A new design for the cell was proposed together with a more accurate solution of Fick’s law for the boundary conditions considered. The initial concentration gradient between the dilute and the more concentrated solutions was taken into account and the numerical solution obtained described the total transient phenomenon. Using a conductimetric technique the new arrangement has been tested for the case of binary diffusion of potassium chloride and sulfuric acid at 25°C.
97102429 flotation
Initial testing of a dynamic column for fine coal
Lai, R. W. et al. Proc. Anmr. In/. Pittsburgh Coal Conf., 1995, 12, 851-857. The design and initial performance of a dynamic column for fine coal column flotation is detailed in this paper. This dynamic column has the potential advantage of higher throughput and better product recovery as well as improved product quality.
97102430 Integrated automated control system for a coke plant based on personal computer Gerbali, S. N. er al. Koks Khim., 1995, (4), 26-29. (In Russian) The paper describes the development of an integrated automated control system for coking plant, with subsystems of modular structure. The system is open for further development. The subsystems can function as selfreacting devices.
97102431 An investigation of pyrite depression flotation by electrochemical pyrite surface control
in coal
Zhu, H. et al. Proc. Annu. Int. Pittsburgh Coal Conf.. 1995, 12, X64-X69. The natural hydrophobicity of pyrite depends on the oxidation-reduction potential of the slurry, as shown by experimental results, The pyrite flotation is generally suppressed under low potentials of the slurry. The sulfur removal in the flotation of high sulfur coal can be improved by the slurry redox potential control. The mechanism and products of electrochemical reactions on the pyrite surface under various conditions are also discussed.
Distributed geneous coal ignition
97102419
activation
energy model of hetero-
Chen, J. C. Comhus~. Flame, 1996, 107, (3). 291-298. A simulation model for the conventional tube-furnace experiment used for ignition studies is presented. The Distributed Activation Energy Model for Ignition accounts for particle-to-particle variations in reactivity by having a single pre-exponential factor and a Gaussian distribution of activation energies among the particles. The article also shows that adjustments to the model parameters permit a good correlation with experimental data.
Exergy analysis of solid-oxide
97102420
fuel-cell (SOFC)
systems Bedringis, K. W. er al. Energv, April 1997, 22, (4). 403-412. This study made use of the exergy concept in order to analyse two methanefueled SOFC systems. The systems include preheating of fuel and air, reforming of methane to hydrogen, and combustion of the remaining fuel in an afterburner. A newly developed iterative computer program using a sequential-modular approach was used for the analyses.
Experimental confirmation of the theoretical prediction of the gas hold up and circulation velocity in Internal loop alr lift reactor and the possibilities of scale up
97102421
Langfelder, G. E. G. et al. Per. Coal, 1996, 38, (2) 47-51. Measurements of gas hold up and liquid circulation rates in an internal loop air lift reactor were performed with air-water mixtures, under different pressures with the aim to check the validity of the theoretical model, proposed by E. Garcia Calvo et al. (1991). Reasonable agreement was found for the experimental results, with exception of the high gas flow rates, when the deviation from the model becomes significant. These deviations are caused by the gas recirculation through the down-comer, the effect of which is not included in the model.
Experimental plan for the assessment of air toxic emissions from a pilot-scale combustion unit
97102422
Pm-. Annu. Int. Pirtshurgh Coal Co@., Hargis, R. A. and Pennline, H. W. 1995, 12, 997-1002. In this experiment; the operation of a 500-lb-per-hour pilot-scale combustion unit was characterized in terms of the formation, distribution, and fate of toxic substances. A description of the pilot unit and expected operating conditions during the air toxics testing is provided, along with a summary of the test plan. This test plan is designed to obtain the necessary data on the concentration of trace elements associated with the vapour phase, particulate phase, and particulate size fraction enabling a comparison of these results from the pilot unit and the full-scale utility. Based on the results of this air toxics characterization effort, an assessment is made of the value of the pilot unit as a facility for the evaluation of sampling and analysis improvements, development of continuous emissions monitors, and future control systems evaluations.
97102423 Experimental study of the kinetics of gasificationmetric carbon transformation in fly ash of pulverized coal-fired thermal power plants Tarasevich, V. N. Prom. Teplofekh., 1995, 17, (6), M-69. (In Russian) The gasification-metric transformation of carbon contained in the fly ash of the largest thermal power plants in Ukraine and Russia, operating on pulverized coal fuel from different coal basins is presented as a kinetic study. The author reports the relationships between the output signal of gasification-metrical transducer of mechanical incomplete burning and the temperature of gasification reaction.
Fischer-Tropsch synthesis doped) ETS-10 titanium silicate catalysts
97102424
on Co and Co(Ru-
Caral. Left., 1996, 41. (1,2), 79-82. Bianchi, C. L. et al. The authors found titanium silicate ETS-10 to be a suitable support for metal catalysts because of its high surface area, high-ion-exchange capability and no acidic functions. In this paper, the M-ETS-10 commercial form (where M stands for Na and K) was first exchanged with Co and thus tested in CO hydrogenation (Fischer-Tropsch synthesis). Moreover, the
192
Fuel
end
Energy
Abstracts
May 1997
sample was also doped with small amounts of ruthenium to improve the Co reducibility. The successive catalytic tests revealed a strong increase in the CO conversion and a modification in the selectivity of the hydrocarbon fractions.
97102425 Fundamentals of thermodynamics, and fluid mechanics
heat transfer,
Hassani, V. and Hauser, S. CRC Handb. Energy Effic., 1997, 19-99. Edited by Kreith, F, and West, R. E. CRC, Boca Raton, FL. The authors review the principles of thermodynamic. heat transfer, and fluid mechanics that an engineer needs to know in order to analyse or design an energy conversion system.
Gas-potentiometric method with solid electrolyte oxygen sensors for the investigation of combustion
97102426
J. Anal. Chem., 1996, 356, (3-4) 215-220. Lorenz, H. et al. Fresenius' Using stabilized zirconia as oxide-ion-conducting solid electrolytes, potentiometric gas analysis was used to determine specific parameters of gas and fuel oil flames (e.g. flame contour, degree of burn-out, and mixing). It was also applied to obtain information about flame turbulence and reaction density from the temporal resolution of the sensor signal, Measurements carried out with solid-electrolyte 02 sensors in a fluidized bed showed that combustion processes of solid fuels could also be analysed. These analyses resulted in fuel-specific burn-out curves, finally leading to burn-out times, to macrokinetics parameters of the combustion, and to some suggestions about the burn-out mechanism. From the resulting constants of the effective reaction rate, a reactivity relative to bituminous coal coke can be given for any solid fuel.
Identification and characterization of macerals by digital image processing
97102427
Scharfenberg, R. and Hesse, D. Glueckauf-Forschrrngrh. 1996, 57, (2), 7% 82. (In German) Digital image processing formed the basis for a new method for the determination of vitrinite maturity in coal. The magnified part of the sample was transferred from the microscope to the computer with the help of a computer connected with a CCD-camera and a light-microscope (magnification 1:500). The macerals representing parts of the image were characterized by high grey-scale gradients at the borders of the macerals. The mean grey value of the macerals as a function of the vitrinite reflection grade was obtained.
97102428 Improvement in the measurement of diffusion coefficients in a restricted diffusion cell: case of binary electrolytes Mathurin Nzikou, J. et ul. Chemical Engineering and Processing, Apr. 1997, 36, (2). 161-165. The paper deals with measuring the diffusion coefficient of an electrolyte by the restricted diffusion method. A new design for the cell was proposed together with a more accurate solution of Fick’s law for the boundary conditions considered. The initial concentration gradient between the dilute and the more concentrated solutions was taken into account and the numerical solution obtained described the total transient phenomenon. Using a conductimetric technique the new arrangement has been tested for the case of binary diffusion of potassium chloride and sulfuric acid at 25°C.
97102429 flotation
Initial testing of a dynamic column for fine coal
Lai, R. W. et al. Proc. Anmr. In/. Pittsburgh Coal Conf., 1995, 12, 851-857. The design and initial performance of a dynamic column for fine coal column flotation is detailed in this paper. This dynamic column has the potential advantage of higher throughput and better product recovery as well as improved product quality.
97102430 Integrated automated control system for a coke plant based on personal computer Gerbali, S. N. er al. Koks Khim., 1995, (4), 26-29. (In Russian) The paper describes the development of an integrated automated control system for coking plant, with subsystems of modular structure. The system is open for further development. The subsystems can function as selfreacting devices.
97102431 An investigation of pyrite depression flotation by electrochemical pyrite surface control
in coal
Zhu, H. et al. Proc. Annu. Int. Pittsburgh Coal Conf.. 1995, 12, X64-X69. The natural hydrophobicity of pyrite depends on the oxidation-reduction potential of the slurry, as shown by experimental results, The pyrite flotation is generally suppressed under low potentials of the slurry. The sulfur removal in the flotation of high sulfur coal can be improved by the slurry redox potential control. The mechanism and products of electrochemical reactions on the pyrite surface under various conditions are also discussed.