03428 Oxidative coupling of methane over alkaline earth oxides deposited on commercial support precoated with rare earth oxides

03428 Oxidative coupling of methane over alkaline earth oxides deposited on commercial support precoated with rare earth oxides

16 Fuel science and technology (fundamental science, analysis, instrumentation) 99lO3415 Ebara fluidired-bed gasification combustion system Takahas...

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Fuel science and technology (fundamental

science, analysis, instrumentation)

99lO3415 Ebara fluidired-bed gasification combustion system Takahashi, K. Kami Pa Gikyoshi, 1998, 52, (lo), 1348-1358. (In Japanese) A new environment-friendly waste treatment system has been designed combining the EBARA urban refuse incinerator and the sludge circular combustor technologies. The technology has a great potential amidst current moves from waste treatment toward waste recycling. 99103416 Fluidized bed coal gasification furnaces Yoshida, K. et al. Jpn. Kokai Tokkyo Koho JP 10 306,284 [98 306,284] (Cl. ClOJ3/46), 17 Nov 1998, Appl. 97/116,750,7 May 1997, 6 pp. (In Japanese) Included in the furnaces are a slag discharging opening at the bottom of a gasification chamber, a slag cooling chamber containing cooling water, a means monitoring the brightness distribution image of the slag falling on the water surface and an image processing the slag data from the monitoring means. Fluidired bed dry distillation furnaces 99103417 Kojima, K. Jpn. Kokai Tokkyo Koho JP 10 306,283 [98 306,283] (Cl. ClOB49/22), 17 Nov 1998, Appl. 97/117,898, 8 May 1997, 6 pp. (In Japanese) In order to generate a pyrolytic gas from a fuel mixed with a flowing material, the furnaces have a hearth tilted downward from below the fuel inlet of the furnace. Nozzles on the hearth blow a gas flow to bring the flowing material to the top part of the furnace and a cyclone at the top part of the furnace separates the flowing material from the pyrolytic gas. The separated material is recycled to the hearth. The furnaces can be used for treating coal, heavy oil and wastes. Gas and solids reducing slurry downcomer 99103418 W. C. and Mart, C. J. PCT Int. Appl. WO 98 50,494 (Cl. Behrmann, ClOG2/00), 12 Nov 1998, US Appl. 851,863, 6 May 1997, 22 pp. The remokal of particulate solids and gas from a three-phase hydrocarbon synthesis slurry of solid catalyst particles, gas and liquid is described. The slurry is passed successively from a slurry body through solids and gas disengaging zones in fluid communication, with the solids disengaging zone upstream of the gas disengaging zone. This is accomplished using a solids and gas disengaging downcomer immersed in the slurry wherein solids are disengaged in a quiescent zone adjacent the slurry body, from which the solids reduced slurry passes through an enclosed cup in which gas is disengaged and removed. The bottom of the cup terminates in a downwardly depending downcomer which hydraulically feeds the densified, solids and gas reduced slurry to the bottom of the reactor or to filtration. Global kinetic analysis of complex materials 99103419 Burnham, A. K. and Braun, R. L. Energy Fuels, 1999, 13, (I), l-22. First-order, nth-order, nucleation and sequential models are among a variety of global kinetic models reviewed here, as well as models having Gaussian, Weibull and discrete activation-energy distributions. The important characteristics of these various models are outlined, with guidance in how to select the correct model. Some of the models have similar characteristics and the parameter relationships among similar models are discussed. Additionally, a new method for deriving discrete activation-energy distribution parameters having In(A) = a + bE is presented. Data accuracy requirements are discussed briefly and kinetic analyses are given for a variety of materials. Hearth structure of coal gasification furnaces. 99103420 Murakami, K. and Morimoto, T. Jpn. Kokai Tokkyo Koho JP 10 306,285 (98 306,285] (Cl. ClOJ3/52), 17 Nov 1998, Appl. 97/116,733, 7 May 1997, 5 pp. (In Japanese) The hearth have taps for discharging melted slag to a slag cooling chamber and grooves guiding the slag to the taps, where the taps have cut off sections at areas connecting to the grooves.

shrinking core model was inadequate to describe the sulfation under the conditions studied. The expression of the product layer coefficient as an exponential function of the conversion led to a unreacted shrinking core model which described the sulfation more accurately.

reaction diffusion modified reaction

Hydroprocessing catalyst 99103423 Kresge, C. T. et al. US 5,837,639 (Cl. 502-64; BOlJ29/00), 17 Nov 1998, US Appl. 625,245, 10 Dee 1990, 22 pp. Comprising a metal hydrogenation-dehydrogenation component supported on a support material comprising an ultra-large pore crystallized material of high surface area and porosity, the catalytic composition is described. The crystallized material exhibits unusually large sorption capacity demonstrated by its benzene adsorption capacity of 215g benzene/lOOg at 50 torr and 25°C and has upiformly sized pores with a maximum perpendicular cross-section of 213A. 99103424 Investigative results of the research program ‘Auxiliary ventilation and monitoring’ Pollak, R. et al. Glueckauf-Forschungsh., 1998, 59, (4), 104-109. (In German) As part of the technology programme mining, DMT Gesellschaft fuer Forschune. und Pruefunr! mbH, Pro Tee Division, carried out an investigatl’re project entified Auxiliary ventilation and monitoring III between 1994 and 1996. Part-financed by the Ministry for Commerce and Trade in Germany, this project focused on auxiliary ventilation in roadway drivages in collieries and covered the following aspects: auxiliary ventilation in advanced headings, safe operation of combined fan systems in the presence of very high CH4 concentrations, flushing of CH4 accumulations after a shutdown of the auxiliary ventilation system and improved techniques and equipment for ventilation, monitoring and air conditioning in headings with auxiliary ventilation. The report presents a summary overview of the problems associated with each part of the project, the main results obtained and the level of technical development achieved. 99103425 Modeling laminar flames for domestic burners Brion, L. Gar d’aujourd’hui, 1999, 123, (3), 7-11. (In French) One research method for designing domestic natural gas burners is modelling; it involves complex chemical reactions inside laminar flames of a methane-air or natural gas-air mixture. This type of flame can be modelled using numeric tools which have been developed by Gaz de France’s Research and Development Division. This article shows the structure of a two-dimensional flame, calculated using the Phoenics algorithm and also improvements made to the physical model and the numerical method of the ESTET-CC algorithm. 99103426 A new method for adiabatic flame temperature estimations of hydrocarbon fuels Zhou, M. and Gauthier, J. E. D. Fuel, 1999, 78, (4), 471-478. The application of artificial neural networks to adiabatic flame temperature prediction of hydrocarbon fuels is presented here. The investigation was conducted over a wide range of operating conditions in terms of fuel composition, pressure and temperature of reactants, fuel-air equivalence ratio and fuel vapour fraction. Several neural network models for predicting the flame temperature for different applicable fuel ranges were built and examined. The proper preparation of network training data and the appropriate choice of network parameters for achieving better prediction accuracy are discussed. The neural network prediction results were compared with those calculated by a thermodynamic and chemical equilibrium-based computer code-the NASA program CET89. It was shown that trained neural network models can provide the adiabatic flame temperature prediction with a good level of accuracy over a wide range of operating conditions.

Heat transfer analysis in a coke oven chamber. 99103421 Aoki, H. Kagoku Kogaku, 1998, 62, (12), 726-729. (In Japanese) Heat transfer in a coke oven and related coke retorting phenomena, including the existence of coal, molten and coke layer, thermal expansion and shrinkage and occurrence of internal stress and cracks, form the subject of this review. Development of the next generation coke manufacturing technology, the SCOPE 21 (super coke oven for productivity and environment enhancement toward the 21st century), is also briefly discussed.

99193427 Oxidation of cyclohexene in liquid phase over hydrotalcite-like compounds containing transition metals Dinka, P. et al. Petroleum and Coal, 1999, 41, (l), 57-61. Tests were carried out on synthesized hydrotalcite-like compounds (HTLc) containing transition metals (cobalt, manganese, nickel, chromium, vanadium) incorporated in the hydrotalcite structure as catalysts for cyclohexene oxidation by oxygen in the liquid phase. The catalytic activity of these compounds was compared with corresponding transition metals in the form of organic salts. The main reaction products are 2-cyclohexene-lon and 2-cyclohexene-l-01.

High pressure thermogravimetric analysis of the 99103422 direct sulfation of Spanish calcium-based sorbents Alvarez, E. and Gonzalez, J. F. Fuel, 1999, 78, (3), 341-348. Typical pressurized fluidized bed combustion (PFBC) conditions thermodynamically inhibit the calcination reaction of limestones and causes the sorbent to react with SO1 by a direct mechanism. Direct sulfation reactivity of different Spanish sorbents was studied by high-pressure thermogravimetric analysis. The physical structure of the surface of the particles was found to influence the sulfation behaviour of the sorbents. Total pore volume and pore surface area correlated well with the reactivity of the sorbents. Temperatures between 800 and 925°C and pressures between 12 and 25 bar promoted an increase in reactivity. However, the gas composition had no effect when changed from 15% C02:3% Oz:O.5% SOz:balance Nz to 12% CO2:7% 02:0.5% SOz:balance Nz. The unreacted

99103428 Oxidative coupling of methane over alkaline earth oxides de osited on commercial support precoated with rare earth oxi 8 es Choudhary, V. R. er al. Fuel, 1999, 78, (4), 427437. Prepared by depositing alkaline earth oxides on a commercial support (SA5205) pre-coated with various rare earth oxides, a number of supported catalysts have been evaluated for their surface properties and activity/ selectivity in oxidative coupling of methane (OCM) at low contact time. The catalysts have been characterized for their basicity and acidity distributions by temperature programmed desorption (TPD) of COz and ammonia from 50°C to 95O”C, respectively and for their oxygen chemisorption sites by TPD of Oz. The OCM activity of the catalysts has been correlated with their basic sites measured in terms of the COz desorbed between 500°C and 950°C. The catalysts with LazOs and/or NdzOs, showing good OCM activity,

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Fuel science and technology (fundamental

have been compared for their performance in the OCM process at different temperatures and CH4/0* ratios in the feed. At 85O”C, the catalyst with SrO deposited on the support precoated with mixed La203-NdZ03 shows best performance in the OCM process. Particle triboelectrification and its use in the 99lQ3429 electrostatic separation process Kwetkus, B. A. Part. Sci. Technol., 1998, 16, (I), 55-68. Empirical experiments allow materials to be arranged in a so-called triboelectric series, but, in most cases, reproducibility is poor and the basic mechanisms of the charge transfer are still a subject of speculation. The difference between tribocharging of conductors and insulators is discussed in this paper and the basic equations for these effects are presented. Triboelectrification of solids has two aspects, one beneficial and one hazardous. The hazardous aspect manifests itself in electrostatic discharges (ESD), which can damage computer equipment, as well as causing fires and explosions during transport and storage of solids and liquids The beneficial aspect triboelectrification is widely used in many industrial applications, such as the Xerox copying technique, powder coating, precharging of fabric filters, electrostatically enhanced cyclone separators, oil mist filtration, aerosol particle collection and finally, the electrostatic separation of materials. The second part of this paper focuses on industrial electrostatic separation techniques using tribocharging of particles. The separation of potassium minerals, coal beneficiation and polymer separation for waste processing are presented. Safety interlock system of water coal paste 99m430 gasifying unit Zhao, K. Huagong Zidonghua A Yibiao, 1998, 25, (4), 16-20. (In Chinese) The operation and application of a safety interlock system for a water coal paste gasifying unit are described. Second-law analysis of aquifer thermal energy 99103431 storage systems Rosen, M. A. Energy, 1999, 24, (2), 167-182. The application of exergy (second-law) analysis to aquifer thermal energy storage (ATES) systems is investigated in order to facilitate proper assessments of overall system performances. An elementary ATES model is created and the corresponding expressions are developed for efficiencies and for the quantities of energy and exergy that are injected and recovered. It is demonstrated that ATES performance measures based on exergy often are more useful and meaningful than those based on energy. Exergy efficiencies account for the temperatures associated with energy transfers to and from an ATES, as well as the quantities of energy transferred and consequently provide a measure of how nearly ATES systems approach ideal thermodynamic performance. Energy efficiencies do not provide a measure of approach to ideal performance and, in fact, are often misleadingly high because some of the energy recovered can be at too low a temperature to be available for a useful purpose. Slurry discharging devices 99103432 Asakura, M. et al. Jpn. Kokai Tokkyo Koho JP 10 287,889 [98 287,889] (Cl. ClOL1/32), 27 Ott 1998, Appl. 97/111,881, 14 Apr 1997, 7 pp. (In Japanese) For the purpose of discharging a slurry from a high pressure container to a low pressure container, the device has a valve between the two containers and a pipe at the downstream side of the valve, containing a narrowed section to cause a pressure drop in the slurry flow. The devices are especially useful for coal liquefaction apparatus. Study on saving energy and desulfurization by 99103433 using cooling and alkaline wastewater Chen, G. Hunnjing Gongcheng, 1998, 16, (2), 41-43. (In Chinese) A study was undertaken on the flue gas desulfurization process comprising gas cooling to 60-80°C in heat exchangers and SO* adsorption by using slag wastewater from coal-burning boiler or industry alkali wastewater. SO2 in flue gas reacted with NaOH in wastewater and formed NazSOj, further, NaHSOx. The influences of flue gas temperature, pH and ratio of liquid to gas on desulfurization efficiency, energy recovery and equipment resistance were discussed. The experiment revealed 71.1% SO2 removal with desulfurization rate of 53.32 mol/h. A thermal analysis of a radiant floor heating system 99103434 using SERT-RES Chun, W. G. et al. Inr. 1. Enqy Res., 23, (4), 335-343. In Korea, both intermittent an1 continuotis heating are widely used for radiant floor heating systems. Intermittent heating circulates hot water according to a pre-defined schedule, while the continuous heating controls water flow using thermostat control units. Modification of the standard version of SERT-RES has been carried out for the numerical simulation of the problem, Relatively large temperature swings were found in the case of intermittent heating with solar availability, although it costs less to implement due to its simplicity in design. On the other hand, the case of continuous heating would avoid such undesirable temperature fluctuations. Experimental evaluations were used to verify the results.

science, analysis, instrumentation)

Thermodynamic calculation and analysis of new 99103435 type of coal moving bed gasifier with draft tube Liu, Y. et al. Huaxue Gongcheng, 1998, 26, (3), 55-57. (In Chinese) The results obtained from the thermodynamic calculation and analysis of a new type of coal moving bed gasifier with a draft tube were supported by hot model experiments and compared with other types of coal gasifier.

A universal expression for optimum specific work 99163436 of reciprocating heat engines having endoreversible Carnot efficiencies Bhattacharyya, S. and Blank, D. A. fnr. J. Energy Res., 23, (4), 327-334. In order to obtain the optimum thermodynamic specific work potential at maximum power for various practical reciprocating cycles having endoreversible Carnot efficiencies, irreversible heat transfer (finite time) analysis was employed. The theory of finite-time thermodynamics for reciprocating endoreversible cycles with heat transfer irreversibilities gives rise to an optimum efficiency at maximum power output, of 7 = 1 - (Td T”)‘.’ for Carnot-like cycles in contrast to the upper limit for Carnot-like cycles of 7 = 1 - (TdT”) obtained from infinite-time thermodynamics. It is shown here that, additionally, for this same general family of regenerative reciprocating cycles which includes the Stirling, the Ericsson and the reciprocating Carnot cycle, the finite-time optimum specific work output at maximum power is exactly half of that obtained for infinite-time reversible cycles operating between the same temperature limits. To accomplish this, the analysis makes use of time symmetry to minimize overall cycle time and to thus optimize net cycle power. Based on linear heat transfer laws, the expression for optimum specific work is shown to be independent of heat conductances. Moreover, this optimum specific work output is the same expression for all of the members of this family of cycles. This analysis makes use of the ideal gas model with constant specific heats, though the results are shown to be universal for the Carnot cycle for vapours and real gases. A sample calculation is given which shows that while operating under the same optimized conditions, the endoreversible Stirling engine will have the same thermal efficiency as the endoreversible Ericsson, but will have a higher optimum power output. The optimum power of the reciprocating endoreversible Carnot engine will be superior to both.

99103437 Ventilation aspects of the use of self-driven combustion-powered vehicles in coal mines Szlazak, N. er al. Gornictwo, 1997, 21, (4), 261-269. (In Polish) Toxic fumes, arising as a result of the use of combustion powered selfdriven vehicles in mining excavations, poses a threat to health. The amount of air necessary to support the work of self-driven vehicles has been determined in accordance with the character of the work and the methods of aeration. The evaluation of the viability of using the machinery in collieries is presented.

99103438 Viscosity measurements and empirical predictions for some model gasifier slags Hurst, H. J. et al. Fuel, 1999, 78, (4), 439-444. The increased interest in the integrated gasification-combined cycle (IGCC) power generation technology has led to a need to predict viscosities for coal ash and fluxed coal ash slags at the tapping temperatures of entrained flow gasifiers. Slags derived by fluxing Australian bituminous coal ashes with limestone have properties that may be approximated by the Si02-Al20~-CaO-FeO system. This note presents experimental determinations of the viscosity and the temperature of critical viscosity for artificial mixtures covering the anorthite region at the 5 and 10 wt% Fe0 levels of this quaternary system. The viscosity measurements were fitted empirically using a modified Urbain treatment. Contour plots of viscosities at 14Oo”C, 1450°C and 1500°C and of temperatures of critical viscosity at the 5 and 10 wt% Fe0 levels are presented as an aid for predicting slag behaviour in entrained flow gasifiers. The viscosity results also form a self consistent data base for future theoretical studies.

99/03439 Wear of economizers with pipes with welded spiralstrip fins due to ash Fomina, V. N. and Timofeeva, I. V. Energetik, 1998, (9), 22-25. (In Russian) An evaluation has been carried out to determine the maximum wear and maximum service life of coal-fired economizers with welded, spiral-strip finned, staggered-tube bundle. The evaluation is dependent on the economizer design, coal feeding zone and type of coal used. The maximum service life of the economizer is 115 years. The maximum permissible gas flow rate at the inlet of the economizer was determined. The advantages of unstaggered-tube bundle economizer over staggered-tube bundle economizer are discussed. The selection of staggered-tube or unstaggered-tube bundle economizer for coal ash-fired boilers must be done on the basis of technical and economic comparison taking into account operation and repair characteristics and intensity of wear due to ash.

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