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Selected AbstractsMaterials Selection for Optimal Design of a Porous Radiant Burner for Environmentally Driven Requirements,ADVANCED ENGINEERING MATERIALS, Issue 12 2009Jaona Randrianalisoa Combustion supports which optimize a porous radiant burner are identified using a material selection approach. The optimization requirements account for the environmental aspect such as lower pollution. It was shown that high porosity metallic materials such as FeCrAlY foam, is always preferable in terms of pollution. From the viewpoint of thermal efficiency, metallic foams are better at high in-flux while Mullite foam takes over at low in-flux. [source] Planar Droplet Sizing for the Characterization of Droplet Clusters in an Industrial Gun-Type BurnerPARTICLE & PARTICLE SYSTEMS CHARACTERIZATION, Issue 3 2003Laurent Zimmer Abstract An important problem in spray combustion deals with the existence of dense regions of droplets, called clusters. To understand their formation mechanism, the droplet dynamics and fuel concentration profile are investigated by means of planar laser techniques in an industrial gun-type burner. The simultaneous measurement of elastic Mie scattering and Laser Induced Fluorescence (LIF) allows the instantaneous measurement of the Sauter Mean Diameter (SMD), after proper calibration. Using two different CCDs to get the two signals requires a detailed calibration of the CCD response before getting absolute diameters. Pixels are binned 6 by 6 to obtain the final SMD map, this is a compromise between spatial accuracy and noise. Velocity field is measured on both sets of images using standard Particle Image Velocimetry (PIV) algorithms. The comparison of cross-correlation technique with PDA results shows that the velocity measured on the LIF images are close to the velocity based on D30, whereas the Mie scattering results are similar to D20. On Mie scattering images, regions of high interfacial area forming clusters can be detected. A special tracking scheme is used to characterize their dynamics in terms of velocity and diameters by ensuring that the same volume of fluid is tracked. It is shown that the clusters have a velocity similar to the velocity of droplets with the same diameter as the mean SMD of the cluster. It is also shown that an increase of pressure tends to trigger the appearance of such a group of droplets, due to a smaller diameter of the droplets caused by the increase of pressure discharge. Uncertainties for the different techniques used are discussed. [source] Investigation and Application of "Bluff-body in Cavity" Burner for Pulverized Coal CombustionASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3-4 2001Gang Chen Abstract The flow and combustion process of a new type of pulverized coal burner, the "bluff-body in cavity", is studied in this paper. This is an improvement on the basic principle of the ordinary bluff-body burner. Mean and fluctuating velocity components and turbulence characteristics of the flow in the outlet of the "bluff-body in cavity" burner were measured using a three-dimensional laser particle dynamics anemometer (3D-PDA). Combustion tests showed that this burner is better than an ordinary burner with only a bluff-body regarding the ignition and flame stability. Application of this new burner in several power plant boilers (65-670 t/h) showed that the temperature in the flame zone is high, the combustion process is very stable, and the boiler efficiency is increased. These improvements indicate a promising future for the burner. [source] Experimental and Numerical Studies of Fe2O3 Particle Formation Processes in a Flat Flame BurnerCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 6 2007M. Beck Abstract Particle formation processes are of interest for many industrial applications. This work focuses on investigating Fe2O3 particle formation. The particles form during thermal decomposition of an iron chloride solution in so-called spray roasting reactors. To analyze the reaction process, a laboratory reactor was designed which reproduces the conditions required for a systematic study of the particle formation process. Furthermore, a simplified particle conversion model was developed to simulate the realistic geometries and particle numbers on an industrial scale by CFD codes. [source] Materials Selection for Optimal Design of a Porous Radiant Burner for Environmentally Driven Requirements,ADVANCED ENGINEERING MATERIALS, Issue 12 2009Jaona Randrianalisoa Combustion supports which optimize a porous radiant burner are identified using a material selection approach. The optimization requirements account for the environmental aspect such as lower pollution. It was shown that high porosity metallic materials such as FeCrAlY foam, is always preferable in terms of pollution. From the viewpoint of thermal efficiency, metallic foams are better at high in-flux while Mullite foam takes over at low in-flux. [source] Screening of plenum cables using a small-scale fire test protocolFIRE AND MATERIALS, Issue 1 2006Mohammed M. Khan Abstract The extent of flame propagation of electric cables in the FM Global intermediate-scale parallel panel test (PPT) using a 60 kW sand burner has been correlated with a dimensional fire propagation index (FPI,)[(m/s1/2)/(kW/m)2/3] derived from ignition and vertical propagation tests in small-scale ASTM E-2058 Fire Propagation Apparatus (FPA). Two distinct types of fire behavior were observed in the PPT. The cables that did not propagate beyond the vicinity of the ignition burner flames have a FPI equal to or less than 7 [(m/s1/2)/(kW/m)2/3], whereas cables that propagated to the top of the 4.9 m parallel panels had a FPI equal to or greater than 14 [(m/s1/2)/(kW/m)2/3]. All the plenum rated (Ul-910 or NFPA 262 tested) cables tested in this study did not exhibit flame propagation in the PPT, had FPI values of 7 [(m/s1/2)/(kW/m)2/3] or less and generated considerably lower smoke than those cables that propagated in the PPT. Based on this study, it is suggested that FPI measured in ASTM E-2058 FPA may be used for screening cables for UL-910 or NFPA262 tests, thus requiring substantially less cable to be supplied for testing. Copyright © 2005 John Wiley & Sons, Ltd. [source] FLOX® Steam Reforming for PEM Fuel Cell Systems,FUEL CELLS, Issue 4 2004H.-P. Schmid Abstract Primary energy savings and CO2 reduction is one of the key motivations for the use of fuel cell systems in the energy sector. A benchmark of domestic cogeneration by PEMFC with existing large scale power production systems such as combined steam-gas turbine cycle, clearly reveals that only fuel cell systems optimising overall energy efficiency (>,85%) and electrical efficiencies (>,35%) show significant primary energy savings, about 10%, compared with the best competing technology. In this context, fuel processing technology plays a dominant role. A comparison of autothermal and steam reforming concepts in a PEMFC system shows inherent advantages in terms of efficiency at low complexity for the latter. The main reason for this is that steam reforming allows for the straightforward and effective use of the anode-off gas energy in the reformer burner. Consequently, practical electrical system efficiencies over 40% seem to be achievable, most likely by steam reformers. FLOX®-steam reforming technology has reached a high state of maturity, offering diverse advantages including: compact design, stable anode off-gas usage, high efficiency, as well as simple control behaviour. Scaling of the concept is straightforward and offers an opportunity for efficient adaptation to smaller (1,kW) and larger (50,kW) units. [source] Improved Stirling engine performance through displacer surface treatmentINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 3 2010Halit Karabulut Abstract This study intended to improve the performance of the beta-type Stirling engine, being developed by the authors for solar energy and low-grade heat sources, by means of displacer surface treatments. Three different displacers were manufactured and tested where one of them was without any surface treatment, other was zirconium coated with 0.15,mm thickness, and the other was helically knurled with 0.30,mm track depth. Because of good thermo-physical properties, helium was used as the working fluid. The heat was supplied by an LPG burner. Tests were conducted at 360±10°C hot end temperature. The highest engine power was obtained with knurled displacer as 250,W at 545,rpm speed and corresponding to this power 4.38,Nm torque was obtained. This was followed by coated and smooth displacers. Power increments provided by the knurled displacer are 40 and 60% compared with the zirconium-coated and untreated displacers. Increments of knurled displacer's torque compared with that of coated and untreated displacers are 13 and 30%, respectively. Copyright © 2009 John Wiley & Sons, Ltd. [source] A dimensionless factor characterizing the ignition of pulverized coal flow: Analytical model, experimental verification, and applicationINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 3 2009Qulan Zhou Abstract An analytical model describing the ignition process of pulverized coal is proposed, and a dimensionless condition number (Ncom) is obtained to describe the comprehensive effect of factors governing the ignition of pulverized coal flow, such as the initial temperature of flow, the sectional heat load of the furnace, and the flux of primary air, secondary air and recirculation flue gas. An optimized concentration of pulverized coal flow is derived explicitly, upon which the earliest ignition of pulverized coal flow is possible. The model is verified in a hot furnace experiment, where it is shown that the derived criterion (Ncom) can be used for different kinds of coal and different types of burner. For given coal and sectional heat load of furnace, when the value of Ncom increases, the condition of ignition is improved and both unburned carbon and NOx emission are reduced. The employment of Ncom in the optimization of burner operating conditions is demonstrated through two applications. In practice, the criterion Ncom can be used to guide the selection of the concentration and type of pulverized coal, as well as the choice of burner and desired aerodynamic field, so as to achieve an optimized performance. Copyright © 2008 John Wiley & Sons, Ltd. [source] Thermodynamic optimization of a solar system for cogeneration of water heating and absorption coolingINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 13 2008R. Hovsapian Abstract This paper presents a contribution to understanding the behavior of solar-powered air conditioning and refrigeration systems with a view to determining the manner in which refrigeration rate, mass flows, heat transfer areas, and internal architecture are related. A cogeneration system consisting of a solar concentrator, a cavity-type receiver, a gas burner, and a thermal storage reservoir is devised to simultaneously produce heat (hot water) and cooling (absorption refrigerator system). A simplified mathematical model, which combines fundamental and empirical correlations, and principles of classical thermodynamics, mass and heat transfer, is developed. The proposed model is then utilized to simulate numerically the system transient and steady-state response under different operating and design conditions. A system global optimization for maximum performance (or minimum exergy destruction) in the search for minimum pull-down and pull-up times, and maximum system second law efficiency is performed with low computational time. Appropriate dimensionless groups are identified and the results are presented in normalized charts for general application. The numerical results show that the three-way maximized system second law efficiency, ,II,max,max,max, occurs when three system characteristic mass flow rates are optimally selected in general terms as dimensionless heat capacity rates, i.e. (,ss, ,wxwx, ,Hs)opt=(0.335, 0.28, 0.2). The minimum pull-down and pull-up times, and maximum second law efficiencies found with respect to the optimized operating parameters are sharp and, therefore, important to be considered in actual design. As a result, the model is expected to be a useful tool for simulation, design, and optimization of solar energy systems in the context of distributed power generation. Copyright © 2008 John Wiley & Sons, Ltd. [source] Energy consideration for designing supercharged ram jet enginesINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 2 2008Amro M. Al-QutubArticle first published online: 20 JUN 200 Abstract The present work investigates the energy considerations and performance characteristics of a newly proposed supercharged ram jet engine. Thermodynamics and fluid mechanics analyses were developed to predict specific thrust, thrust-specific fuel consumption (TSFC), overall efficiency, and thrust-to-weight ratio of the engine. Compressor pressure ratio and efficiency, combustor temperature, and pressure losses in the burner and nozzle are considered as primary variables in the engine performance analysis. Performance characteristics are calculated to illustrate the effect of each parameter independently at different flight speeds. This is done while maintaining other parameters at given typical operating values. A computer program was developed to perform the iterative calculations. Results indicate that the compressor pressure ratio and the combustion product temperature are the most critical parameters in determining the performance of the engine. At compressor pressure ratio of 1.15,1.2, the typical static thrust-to-weight ratio is at maximum. Increasing combustion product temperature increases the thrust-to-weight ratio as well as TSFC. Finally, newly developed high power-to-weight ratio IC engine makes it possible for the supercharged ram jet engine to achieve high performance, in terms of thrust-to-weight ratio and TSFC. Copyright © 2007 John Wiley & Sons, Ltd. [source] Hydrogen as burner fuel: modelling of hydrogen,hydrocarbon composite fuel combustion and NOx formation in a small burnerINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 11 2005Mustafa Ilbas Abstract The objective of this work is to investigate numerically the turbulent non-premixed hydrogen (H2) and hydrogen,hydrocarbon flames in a small burner. Numerical studies using Fluent code were carried out for air-staged and non-staged cases. The effects of fuel composition from pure hydrogen to natural gas (100%H2, 70%H2+30%CH4, 10%H2+90%CH4, and 100%CH4) were also investigated. The predictions are validated and compared against the experimental results previously obtained and results from the literature. Turbulent diffusion flames are investigated numerically using a finite volume method for the solution of the conservation equations and reaction equations governing the problem. Although, three different turbulence models were tested, the standard k,, model was used for the modelling of the turbulence phenomena in the burner. The temperature and major pollutant concentrations (CO and NOx) distributions are in good agreement with the existing experimental results. Air staging causes rich and lean combustion regions thus lower NOx emissions through the combustor exit. Blending hydrogen with methane causes considerable reduction in temperature levels and thus NO emissions. Increasing the mixture ratio from stoichiometric to leaner mixtures also decreases the temperature and thus NO emissions. Hydrogen may be considered a good alternative fuel for burners, as its use reduces the emission of pollutants, and as it is a renewable synthetic fuel. Copyright © 2005 John Wiley & Sons, Ltd. [source] On the effect of the local turbulence scales on the mixing rate of diffusion flames: assessment of two different combustion modelsINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 10 2002Jose Lopes Abstract A mathematical model for the prediction of the turbulent flow, diffusion combustion process, heat transfer including thermal radiation and pollutants formation inside combustion chambers is described. In order to validate the model the results are compared herein against experimental data available in the open literature. The model comprises differential transport equations governing the above-mentioned phenomena, resulting from the mathematical and physical modelling, which are solved by the control volume formulation technique. The results yielded by the two different turbulent-mixing physical models used for combustion, the simple chemical reacting system (SCRS) and the eddy break-up (EBU), are analysed so that the need to make recourse to local turbulent scales to evaluate the reactants' mixing rate is assessed. Predictions are performed for a gaseous-fuelled combustor fired with two different burners that induce different aerodynamic conditions inside the combustion chamber. One of the burners has a typical geometry of that used in gaseous fired boilers,fuel firing in the centre surrounded by concentric oxidant firing,while the other burner introduces the air into the combustor through two different swirling concentric streams. Generally, the results exhibit a good agreement with the experimental values. Also, NO predictions are performed by a prompt-NO formation model used as a post-processor together with a thermal-NO formation model, the results being generally in good agreement with the experimental values. The predictions revealed that the mixture between the reactants occurred very close to the burner and almost instantaneously, that is, immediately after the fuel-containing eddies came into contact with the oxidant-containing eddies. As a result, away from the burner, the SCRS model, that assumes an infinitely fast mixing rate, appeared to be as accurate as the EBU model for the present predictions. Closer to the burner, the EBU model, that establishes the reactants mixing rate as a function of the local turbulent scales, yielded slightly slower rates of mixture, the fuel and oxidant concentrations which are slightly higher than those obtained with the SCRS model. As a consequence, the NO concentration predictions with the EBU combustion model are generally higher than those obtained with the SCRS model. This is due to the existence of higher concentrations of fuel and oxygen closer to the burner when predictions were performed taking into account the local turbulent scales in the mixing process of the reactants. The SCRS, being faster and as accurate as the EBU model in the predictions of combustion properties appears to be more appropriate. However, should NO be a variable that is predicted, then the EBU model becomes more appropriate. This is due to the better results of oxygen concentration yielded by that model, since it solves a transport equation for the oxidant concentration, which plays a dominant role in the prompt-NO formation rate. Copyright © 2002 John Wiley & Sons, Ltd. [source] A fibre-mat catalytic burner for the heating system of PVC tilesINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 10 2002Yong Seog Seo Abstract This study aims to develop the low-temperature catalytic burner using Al2O3 fibre and Pt catalyst as a substrate and an active material, respectively, and then to apply it to the heating system of PVC tiles. Three types of fibre-mat catalytic burners,natural diffusion catalytic burner, forced diffusion catalytic burner and premixed catalytic burner,were tested. For the natural diffusion catalytic burner, the combustion efficiency was significantly affected by the installation method. Its combustion efficiency was above 99.5% when it was placed vertically and upward, whereas the combustion efficiency rapidly deteriorated to less than 80% when it was installed in downward position. When the forced diffusion combustion mode was employed, the combustion efficiency of the fibre-mat catalytic burner was successively improved over 99.5%. The optimal operation condition of the premixed fibre-mat catalytic burner was obtained when the excess air ratio is 4.3 and the heat load is 3.0 kcal h,1 cm,2. The heat load of the premixed catalytic burner was found to be twice as much as those of the natural and forced diffusion catalytic burner, meaning that the size of the catalytic burner can be reduced to its half if the premixed catalytic burner is used. We also performed the field test of the fibre-mat catalytic burner in the heating system of the PVC tiles. The combustion efficiency of the catalytic burners appeared to be satisfactory, above 99.5%, and the energy saving by replacing the existing electrical heaters with the fibre-mat catalytic burners were shown to be 27.7%. Copyright © 2002 John Wiley & Sons, Ltd. [source] Steady-state multiplicity, flashback, and control issues in CH4 radiant burnersAICHE JOURNAL, Issue 9 2004M. Bizzi Abstract Methane is widely employed as a source of energy in combustion systems. Among the currently available technologies, radiant heaters offer high thermal efficiency and low environmental impact in comparison with atmospheric burners. The present work deals with the modeling of methane combustion in a noncatalytic metal fiber burner, represented by means of one-dimensional transient equations. The model accounts for a detailed reaction mechanism, radiation within the porous medium, longitudinal heat and mass transfer. After its validation, the model was employed to analyze a typical stability problem that affects these systems: under given operating conditions (low specific power inputs and excess of air) the occurrence of flashback may in fact preclude the safe operation of the system. As a consequence of energy radiation in the upstream direction, the burner upstream surface and the plenum chamber might become hot enough to heat in turn the gas feedstock, thus eventually determining flashback. In this paper, the mechanism of flashback is numerically investigated as a function of the burner structure and operating conditions by means of a model analysis so as to single out regions of flashback occurrence and a criterion for safe operation. Finally, some guidelines are outlined for a cheap and effective control of the system, paving the way for possible improvement of currently adopted control systems. © 2004 American Institute of Chemical Engineers AIChE J, 50: 2276,2286, 2004 [source] Millisecond catalytic wall reactors: I. Radiant burnerAICHE JOURNAL, Issue 5 2001J. M. Redenius Short-contact-time reactors have potential for high throughput in reactors much smaller than their traditional counterparts. While they operate adiabatically, heat can be exchanged at short contact time by integrating heat exchange into the reactor. Hot effluent of exothermic reaction systems can be redirected over feed gases to recuperate a portion of the sensible heat. Placing catalyst directly on reactor walls eliminates the resistance to heat transfer in the thermal boundary layer so that heat released by combustion can be effectively coupled to an emitter, such as in a radiant burner. A radiant heater was constructed, operated, and simulated incorporating short contact time, energy recuperation, and a catalytic wall. This burner operated stably for many hours at a firing rate from ,50 to > 160 kW/m2 at a radiant temperature of 950 to 1,150 K at a radiant efficiency of ,60% with a residence time in the reacting zone of ,10 ms. This reactor was modeled using 2-D Navier-Stokes equations including detailed models for chemistry and heat transport. Temperature and compositions predicted agreed well with experimental measurements. [source] Quantitative diagnostics of a methane/air mini-flame by Raman spectroscopy,JOURNAL OF RAMAN SPECTROSCOPY, Issue 1-3 2006J. M. Fernández Abstract We present a quantitative investigation by linear Raman spectroscopy of a methane/air premixed flame from a commercial burner. Rotational temperatures and absolute densities of the major species, N2, O2, CH4, CO2, and H2O have been measured in a grid of points across the flame section. Axial and radial profiles of temperature and densities are reported, and mass balances along the flame axis are discussed. We show the capabilities of this technique for combustion studies by using currently available standard detectors and spectrometers. Copyright © 2006 John Wiley & Sons, Ltd. [source] Preparation of Aluminum Oxynitride and Nitride Spherical Powders Via Flame Synthesis Assisted by DC Arc PlasmaJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2008Yasumasa Takao Spherical powders of aluminum oxynitride/nitride are directly prepared by flame synthesis in which oxygen serves as an indispensable reactant. Nonoxide powders are commonly nonspherical, and the particle sizes of these powders are less than submicrometers. The major limiting factors for the synthesis are the free energy, reaction temperature, and reaction rate. The innovative issue related to this flame technology that is assisted by plasma is the ambivalence of the reducing gas atmosphere over 1500 K. The chemical equilibrium calculated indicates that the plasma heating compensates for the lack of reaction temperature under a low-oxygen condition. This burner realizes a high-speed reaction with the help of the reactive species in the arcs. [source] Service conditions and their influence on oxide scale formation on metallic high temperature alloys for application in innovative combustion processesMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 2 2006G. Teneva-Kosseva Abstract The present paper focuses on two aspects: the service conditions of a flame tube in a low-NOx recirculation burner (maximum temperature experienced by the material: 1000 °C) and the interrelationship between service conditions and both the structure and growth of the oxide scale. The flame tube is exposed to extreme thermal and atmospheric conditions during service. Due to the short burner operation time followed by a pause, rapid changes of the temperature and gaseous environment occur. Three Ni-based alloys (alloy 602 CA, alloy 603 XL and alloy 693) were investigated in cyclic oxidation tests under typical conditions for the combustion of fuel oil. Flame tube temperature measurements in both the axial and the tangential directions are presented together with results concerning the influence of the fuel quality, duration of the air ventilation after burner shut down and temperature on the thickness and composition of the oxide scale. [source] Planar Droplet Sizing for the Characterization of Droplet Clusters in an Industrial Gun-Type BurnerPARTICLE & PARTICLE SYSTEMS CHARACTERIZATION, Issue 3 2003Laurent Zimmer Abstract An important problem in spray combustion deals with the existence of dense regions of droplets, called clusters. To understand their formation mechanism, the droplet dynamics and fuel concentration profile are investigated by means of planar laser techniques in an industrial gun-type burner. The simultaneous measurement of elastic Mie scattering and Laser Induced Fluorescence (LIF) allows the instantaneous measurement of the Sauter Mean Diameter (SMD), after proper calibration. Using two different CCDs to get the two signals requires a detailed calibration of the CCD response before getting absolute diameters. Pixels are binned 6 by 6 to obtain the final SMD map, this is a compromise between spatial accuracy and noise. Velocity field is measured on both sets of images using standard Particle Image Velocimetry (PIV) algorithms. The comparison of cross-correlation technique with PDA results shows that the velocity measured on the LIF images are close to the velocity based on D30, whereas the Mie scattering results are similar to D20. On Mie scattering images, regions of high interfacial area forming clusters can be detected. A special tracking scheme is used to characterize their dynamics in terms of velocity and diameters by ensuring that the same volume of fluid is tracked. It is shown that the clusters have a velocity similar to the velocity of droplets with the same diameter as the mean SMD of the cluster. It is also shown that an increase of pressure tends to trigger the appearance of such a group of droplets, due to a smaller diameter of the droplets caused by the increase of pressure discharge. Uncertainties for the different techniques used are discussed. [source] Determination of Soot Particle Size in a Premixed Flame: a Static and Dynamic Light Scattering StudyPARTICLE & PARTICLE SYSTEMS CHARACTERIZATION, Issue 2 2003Gert Kroner Abstract In this contribution we report upon our static and dynamic light scattering experiments to characterize soot particles in flames. We studied sooting laminar premixed flame with acetylene as fuel mixed with air as oxidizer. The air equivalence ratio of the combustion was larger than one. We used a Kaskan type burner with circular geometry and a stabilizing flow of nitrogen around the flame. We focused on the determination of the size of the soot particles in the center of the flame as a function of height above burner. In addition we investigated the influence of the mixing ratio of the gases on the size of the particles. Our results show that static light scattering is better suited than dynamic light scattering for a fast and reliable characterization of soot particles in flames. The latter needs detailed a priori information about the flame to allow the unique determination of sizes from the diffusion measurements. The soot particles grow monotonously with height above burner and with decreasing air equivalence ratio. The aggregates have a fractal dimension lower than two. [source] Flare pilot system safety,PROCESS SAFETY PROGRESS, Issue 1 2007John Bellovich Abstract One of the worst nightmares a plant manager can experience is a complete flare system outage. The flare system is the last line of defense for many refining and petrochemical facilities and, when out of commission, can cause the shutdown of the entire facility. Flare ignition failure may lead to unburned venting of dangerous gases, and may develop into an explosive hazard leading to the loss of property and equipment, or worse, injury to personnel or loss of life. The safety and effectiveness of flaring are dependent upon one or more continuously burning pilots for immediate and sustained ignition of gases exiting a flare burner. Because pilot failure can compromise safety and effectiveness, it should be detected quickly and accurately to allow prompt automatic and/or operator response. Proper disposal of process and waste gases during routine and/or emergency conditions is crucial to help operating facilities protect plant employees and the surrounding community, and to avoid hundreds of thousands of dollars in fines. These reasons alone make the pilot monitoring and ignition system the most important component of any flare system. The advanced flare pilot systems explained in this article offer increased protection from harsh environmental conditions and rapid notice of pilot flame failure. Recently published industry standards for flare pilot design and performance are also discussed. © 2006 American Institute of Chemical Engineers Process Saf Prog, 2007 [source] Numerical modelling and simulation of pulverized solid-fuel combustion in swirl burnersTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2009H. Ettouati Abstract A finite-volume numerical model for computer simulation of pulverized solid-fuel combustion in furnaces with axisymmetric-geometry swirl burner is presented. The simulation model is based on the k,,,, single phase turbulence model, considering the presence of the dispersed solid phase via additional source terms in the gas phase equations. The dispersed phase is treated by the particle source in cell (PSIC) method. Solid fuel particle devolatilization, homogenous and heterogeneous chemical reaction processes are modelled via a global combustion model. The radiative heat transfer equation is also resolved using the finite volume method. The numerical simulation code is validated by comparing computational and experimental results of pulverized coal in an experimental furnace equipped with a swirl burner. It is shown that the developed numerical code can successfully predict the flow field and flame structure including swirl effects and can therefore be used for the design and optimization of pulverized solid-fuel swirl burners. On présente un modèle numérique de volumes finis pour la simulation par ordinateur de la combustion de combustibles solides pulvérisés dans des fours munis de brûleur à tourbillon axisymétrique. Le modèle de simulation repose sur le modèle de turbulence monophasique k,,,,, et décrit la présence de la phase solide dispersée par le biais de termes-sources additionnels dans les équations de la phase gazeuse. La phase dispersée est traitée par la méthode PSIC. La dévolatilisation des particules combustibles solides et les procédés de réaction chimique homogène et hétérogène sont modélisés à l'aide d'un modèle de combustion global. L'équation de transfert de chaleur radiatif est également résolue par la méthode des volumes finis. Le code de simulation numérique a été validé en comparant les résultats des calculs par ordinateur avec des expériences pour du charbon pulvérisé dans un four expérimental équipé d'un brûleur à tourbillon. On montre que le code numérique peut prédire avec succès le champ d'écoulement et la structure de flamme y compris les effets tourbillonnaires et qu'il peut donc servir à la conception et à l'optimisation des brûleurs à tourbillons pour les combustibles solides pulvérisés. [source] Chihr de l'encens (Yémen)ARABIAN ARCHAEOLOGY AND EPIGRAPHY, Issue 1 2010Claire Hardy-Guilbert Frankincense burners found in al-Shihr's excavations in Yemen, a frankincense harbour during the Islamic period, represent a rare corpus of this type, which is an indication of both specific use and goods from South Arabia. Although associated with the pre-Islamic South Arabian kingdoms, the frankincense burner evolved throughout the Islamic period. This is proved by the long chronological sequence of the al-Shihr site (780,1996). Texts quoting the presence of frankincense, its use and its trade in al-Shihr are cited in this article to support the reputation of this harbour-town, which is part of the maritime trade networks of medieval Islam. The aim of this article is to create a renewal of interest in future archaeological research about this object, which is so often neglected in spite of its importance as a testimony of the customs and exchanges that are deeply rooted in Arabian civilisation. [source] Investigation and Application of "Bluff-body in Cavity" Burner for Pulverized Coal CombustionASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3-4 2001Gang Chen Abstract The flow and combustion process of a new type of pulverized coal burner, the "bluff-body in cavity", is studied in this paper. This is an improvement on the basic principle of the ordinary bluff-body burner. Mean and fluctuating velocity components and turbulence characteristics of the flow in the outlet of the "bluff-body in cavity" burner were measured using a three-dimensional laser particle dynamics anemometer (3D-PDA). Combustion tests showed that this burner is better than an ordinary burner with only a bluff-body regarding the ignition and flame stability. Application of this new burner in several power plant boilers (65-670 t/h) showed that the temperature in the flame zone is high, the combustion process is very stable, and the boiler efficiency is increased. These improvements indicate a promising future for the burner. [source] Trial by fire: are the crystals macromolecules?ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 5 2010Kannan Raghunathan Protein crystallization screens frequently yield salt crystals as well as protein crystals. A simple method for determining whether a crystal is composed of salt or macromolecules is suggested. A drop containing one or more crystals is transferred to a glass cover slip and the cover slip is then passed through the flame of a Bunsen burner. Macromolecule crystals are destroyed by this treatment, while salt crystals generally remain. The test can be performed after other commonly used tests such as crushing and staining. [source] Clenbuterol marketed as dietary supplementBIOMEDICAL CHROMATOGRAPHY, Issue 3 2008Maria K. Parr Abstract In several studies it has been demonstrated that products containing pharmaceutically active ingredients are marketed as dietary supplements. Most of these products contain anabolic steroids. Recently products for weight loss containing active drugs have also appeared on the market. In the present case a healthy male ordered the product ,Anabolic burner' via the Internet. The product was received from a German dispatcher and paid by bank transfer to a German bank account. After ingesting one tablet he reported tremor and delivered a urine sample. This urine was found to contain 2 ng/mL of clenbuterol utilizing LC-MS/MS analysis. Additionally the product itself was analyzed with GC-MS for clenbuterol, yielding a content of about 30 µg per tablet. The beta-2 agonist clenbuterol is only legally available on prescription and is classified as prohibited doping substance in sports. The present case for the first time confirms the presence of clenbuterol in a dietary supplement. It again demonstrates the common problem with products on the supplement market, where non-licensed pharmaceuticals and doping substances are easily available. The ingestion of these products containing additions of therapeutic drugs can lead to side effects and/or interactions with conventional medicines. Copyright © 2007 John Wiley & Sons, Ltd. [source] Flame height correlation and upward flame spread modellingFIRE AND MATERIALS, Issue 6 2002Kuang- Chung Tsai Previous work has demonstrated that flame height is one of the two most important parameters determining the rate of vertical flame spread on a wall. Flame spread models rely on empirical flame height correlations of the form Xf=KQ,,n, but there have been no carefully controlled experiments designed to establish the validity of such correlations and there are no data for values of Q,,< c.25 kW/m. Two new sets of data are presented here, one based on experiments with 6 mm thick PMMA slabs (heights 25,250 mm, width 50,150 mm) as the fire source, measuring Q,, and Xf simultaneously. This set relates to the early stages of a wall fire when Q,,< 30 kW/m. The other set of data was obtained with a vertical gas-fired panel which consisted of an array of 14 independent burners arranged to allow the aspect ratio of the burning surface to be varied. The data confirm that the flame height correlates with Q,,, but reveal (inter alia) that there are two regions, for values of Q,, greater than and less than c. 20 kW/m. An existing upward flame spread model was modified to allow these two correlations to be incorporated to predict the development of a small fire on a vertical surface for these two regions, which would provide more realistic modelling information. Copyright © 2002 John Wiley & Sons, Ltd. [source] Transient thermal modelling of heat recovery steam generators in combined cycle power plantsINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 11 2007Sepehr Sanaye Abstract Heat recovery steam generator (HRSG) is a major component of a combined cycle power plant (CCPP). This equipment is particularly subject to severe thermal stress especially during cold start-up period. Hence, it is important to predict the operational parameters of HRSGs such as temperature of steam, water, hot gas and tube metal of heating elements as well as pressure change in drums during transient and steady-state operation. These parameters may be used for estimating thermal and mechanical stresses which are important in HRSG design and operation. In this paper, the results of a developed thermal model for predicting the working conditions of HRSG elements during transient and steady-state operations are reported. The model is capable of analysing arbitrary number of pressure levels and any number of elements such as superheater, evaporator, economizer, deaerator, desuperheater, reheater, as well as duct burners. To assess the correct performance of the developed model two kinds of data verification were performed. In the first kind of data verification, the program output was compared with the measured data collected from a cold start-up of an HRSG at Tehran CCPP. The variations of gas, water/steam and metal temperatures at various sections of HRSG, and pressure in drums were among the studied parameters. Mean differences of about 3.8% for temperature and about 9.2% for pressure were observed in this data comparison. In the second kind of data verification, the steady-state numerical output of the model was checked with the output of the well-known commercial software. An average difference of about 1.5% was found between the two latter groups of data. Copyright © 2007 John Wiley & Sons, Ltd. [source] Hydrogen utilization as a fuel: hydrogen-blending effects in flame structure and NO emission behaviour of CH4,air flameINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 5 2007Jeong Park Abstract Hydrogen-blending effects in flame structure and NO emission behaviour are numerically studied with detailed chemistry in methane,air counterflow diffusion flames. The composition of fuel is systematically changed from pure methane to the blending fuel of methane,hydrogen through H2 molar addition up to 30%. Flame structure, which can be described representatively as a fuel consumption layer and a H2,CO consumption layer, is shown to be changed considerably in hydrogen-blending methane flames, compared to pure methane flames. The differences are displayed through maximum flame temperature, the overlap of fuel and oxygen, and the behaviours of the production rates of major species. Hydrogen-blending into hydrocarbon fuel can be a promising technology to reduce both the CO and CO2 emissions supposing that NOx emission should be reduced through some technologies in industrial burners. These drastic changes of flame structure affect NO emission behaviour considerably. The changes of thermal NO and prompt NO are also provided according to hydrogen-blending. Importantly contributing reaction steps to prompt NO are addressed in pure methane and hydrogen-blending methane flames. Copyright © 2006 John Wiley & Sons, Ltd. [source] | ||||||||||||||||