Search

In this paper, the catalyst tube lifetime of a practical steam methane reformer is analyzed numerically. The effect of burner operating mode on the flow development, hydrogen yield, and catalyst tube lifetime is discussed, with the aim of improving the reformer performance. The results of this study reveal that using the periodic boundary conditions, the temperatures and hydrogen yields obtained are much lower than the experimental values and the pressures are much lower than those using the real model. This results in overestimating the catalyst tube lifetime and underestimating the reformer operation risk. The catalyst tubes in the downstream area have longer lifetimes, while those in the upstream area have shorter lifetimes. Turning the upstream burners off is more efficient to the catalyst tube lifetime, while turning off the central groups of burners is less efficient. The main drawback of turning off burners is the decrease of hydrogen yield. [ABSTRACT FROM AUTHOR]

This paper presents results of experimental investigation on elimination of combustion oscillations caused by new low pollution burner which was integrated in a gas heater. The method is known as a passive method, based on introducing the air in the combustion chamber. Since efficiency of the passive method is highly dependent of the way the air is injected, several different methods were investigated and compared. The paper also presents effects on pollution characteristics during its operation in the unstable regime. [ABSTRACT FROM AUTHOR]

The paper presents results of experimental and numerical investigation addressing combustion of baled agricultural biomass in a 50 kW experimental furnace equipped with cigar burners. Experiments performed included measurements of all parameters deemed important for mass and energy balance, as well as parameters defining quality of the combustion process. Experimental results were compared with results of numerical simulations performed with previously developed CFD model. The model takes into account complex thermo mechanical combustion processes occurring in a porous layer of biomass bales and the surrounding fluid. The combustion process and the corresponding model were deemed stationary. Comparison of experimental and numerical results obtained through research presented in this paper showed satisfactory correspondence, leading to the conclusion that the model developed could be used for analysis of different effects associated with variations in process parameters and/or structural modifications in industrial biomass facilities. Mathematical model developed was also utilized to examine the impact of flue gas re-circulation on maximum temperatures in the combustion chamber. Gas re-circulation was found to have positive effect on the reduction of maximum temperature in the combustion chamber, as well as on the reduction of maximum temperature zone in the chamber. The conclusions made provided valuable inputs towards prevention of biomass ash sintering, which occurs at higher temperatures and negatively affects biomass combustion process. [ABSTRACT FROM AUTHOR]

The Energy Policy and Planning Office, Ministry of Energy, Royal Thai Government reported from 2007 to 2015, the using of fuel increase every year. In addition, price of fuel increases continuously. The way of most efficiently of energy using is important. This paper aimed to study about thermal efficiency of infrared gas stove by varies with parameters which were diameters of pot (220, 240 and 260 mm), distances between burner (20, 25 and 30 mm) and pot and diameter of burner head (135, 145 and 155 mm) in 9 cases by simulation method. The numerical model was validated with results from experiment in 220, 240 and 260 mm of diameter of pot, average errors are 10.85011%, 6.754703% and 2.13054%, respectively. The results of this study showed with three sizes of pot, huger distances between burner and pot decrease thermal efficiency. The highest thermal efficiency was in 260 mm of diameter of pot. All of 9 cases by vary parameters, the highest thermal efficiency was 260 mm of diameter of pot, 20 mm of distance between burner and pot and 145 mm of diameter of burner head condition and the lowest thermal efficiency was 220 mm of diameter of pot, 20 mm of distance between burner and pot and 145 mm of diameter of burner head condition. The obtained results provide useful for development of heating process by infrared burner technologies and to guide the development of effective infrared burner too lead the way in energy-saving way and reduce environmental impacts. [ABSTRACT FROM AUTHOR]

Furnaces are the devices, providing heat to industrial operations such as chemical reactions, extraction of metals, production of ceramic, etc. The main challenge of furnaces is the emission of massive air pollutants. However, the porous burners produce less pollutants, compared to the rest of them. In this paper, the finite volume method is used to investigate the effects of porosity on the production of pollutants in the porous burner. The simulation results show that temperature distribution in the low porosity burner is more uniform than in the high porosity one. In addition, increasing the porosity the maximum temperature of the flame increases, and thus reduces the conversion of fuel to carbon monoxide and increases production of nitrogen oxides. Therefore, the average porosity leads to reduction of the total emission of pollutants. The simulation results are in good agreement with experimental data. [ABSTRACT FROM AUTHOR]

Power generation usually requires removal of thermal energy from the system. In this paper, we evaluate the impact of the heat removal on the dynamics of a premixed flame in the case of a simple, but representative, counter-current microburner. In this configuration, two opposed streams of fresh gases with the same equivalence ratio ϕ are introduced, at the same velocity UF, in the burner through narrow, infinitely long channels. The channels are separated by the common wall from which the heat used for power generation is removed. A flame-sheet chemistry model and a realistic, specifically developed, one-step Arrhenius kinetics are used and compared in order to explore the importance of finite-rate chemistry effects. Finite-rate is found to play a significant role especially near the extinction limit (low velocities) and at high temperatures (high velocities) where distributed reaction can lead to autoignition. The changes in the flame stabilization position and operation limits of the burner are analyzed. Significant variations in combustor operation were found when energy is extracted from the system. Power generation efficiency is also studied, to conclude that an optimum level of energy extraction exists for each equivalence ratio and also that an optimum equivalence ratio exists. [ABSTRACT FROM AUTHOR]

Current swirl combustion technology with faulty coal lacks flexibility for peak shaving without aids, necessitating a novel low–load stable combustion technology. This paper presented such a technology, developed from gas–particle experiments, that did not require major modifications to the burner secondary air structure. The new technology was applied to a low NO x axial swirl burner (LNASB) in a 350 MW boiler and a vortex swirl burner (VSB) in a 700 MW boiler. Comparative analysis at 20 % boiler load showed both prototypes lacked recirculation zones, characterized by high primary air axial velocities and low turbulence intensity. After modification, LNASB became stable combustion LNASB (SLNSB), and VSB became stable combustion VSB (SVSB). SLNASB had a central recirculation zone, while SVSB had a large annular recirculation zone. The relative length and diameter of SLNASB's recirculation zone were 0.7 and 0.472, while for SVSB, they were 1.5 and 0.477. LNASB had a diffusion angle of 4.7° and a swirl number of 0.511; SLNASB had 29.7° and 0.695; VSB had 11.4° and 0.445; SVSB had 33.3° and 0.784. The turbulence intensity of SLNASB and SVSB were notably higher than their prototypes. High–concentration particles accumulated at the center of SLNASB and SVSB, then entered the recirculation zone. • A universal low–load stable combustion technology has been developed. • New technology significantly reduces both modification and operational costs. • Combining swirling primary air with blunt body is not ideal for low–load. • Post–modification, new burner can operate stably at a 20 % boiler load. [ABSTRACT FROM AUTHOR]

The correct operation of clinker furnaces also involves understanding and mastering the appearance of their defects. This requires tracking the operation of these machines for as long as possible and recording the good operating times and stationary due to defects. In the present case, the follow-up was done daily for nine months. Good running times determine the level of reliability, and stops for restoration, maintainability. Only reliability is studied in this paper. It is important to determine the mathematical law of the proper functioning of the burner, ie reliability. Reliability analysis shows how maintenance has been done prior to the study and in which moment of life is the burner being studied. The information obtained allows a critical analysis of the decisions that need to be taken to improve reliability. Increasing the reliability of burners reduces the demand for corrective maintenance and consequently increases the production of cement. [ABSTRACT FROM AUTHOR]

The paper presents basic technical solutions for the firing system and design of the burners of boilers PK-39-IIM and BKZ-420-140-5 when firing Ekibastuz coal. The developed low-NOx firing systems ensure low nitrogen oxide emissions both at low cross-section heat release rates and high furnace cross-section heat release rates. Technical solutions developed for the firing systems are based on the simulation of coal combustion in furnaces of the mentioned boilers using ANSYS Fluent software. [ABSTRACT FROM AUTHOR]

The W-shaped regenerative technology-based radiant tube, a commonly adopted indirect-heating equipment item, has been well geared into various industries. This paper effectively amplifies our previous research and experimentally presents the research object, the W-shaped regenerative radiant tube (RRT), with 100 Kw rated power capacity and the performance tuned. Accordingly, four configuration schemes with the geometrically modified regenerative radiant tube burner (RRTB) are proposed in contrast to the previous one, to ascertain how the configuration of secondary stage air vent influences the performances of W-shaped RRT. Furthermore, how the switching time as an important operational parameter affects the performances of W-shaped RRT is meantime researched. As the results bespeak, in contrast to the previous one, the RRTB proposed in the experiment outstrips the previous one in the gained familiar M-shaped axial tube wall temperature profile while higher heating capacity, better tube wall temperature uniformity and lower NOX emission with this novel RRTB. The switching time increase from 30 s to 60 s lowers the overall tube wall temperature and NOX emission, whereas the maximum tube wall temperature approaches to the RRTB when the switching time exceeds 60 s. The attained experimental results lay the theoretical foundation for guiding industrial production of such heating equipment item. [ABSTRACT FROM AUTHOR]

Heat Oxy-Combustion (HeatOx) is one of the innovative technologies that aim to enhance combustion efficiency and reduce the environmental impact caused by glass-melting processes. It reduces CO2 through fuel savings, while significantly reducing NOx and dust emissions. The main principle of HeatOx is to use the sensible energy in the flue gas to preheat the combustion reactants, mainly oxygen and natural gas (NG), providing a 10% or higher energy consumption reduction compared to conventional oxyfuel combustion without preheating. HeatOx is proven technology, but as a new technology, it is being rapidly improved in terms of efficiency gain and competitive equipment cost. In this context, Air Liquide has developed a bi-fuel HeatOx burner for the countries where fuel price is volatile. This burner combines the advantages of HeatOx technology - oxygen preheating - and fuel flexibility so that operational costs can be optimized by switching back and forth between NG and Heavy oil fuel (HFO). This burner, based on Air Liquide patented ALGLASS FC technology and patented Trident oil injector, generates a flat flame for both NG and HFO configurations, thereby ensuring a good coverage over glass bath. This paper presents 1000 kW burner test results with HFO, which showed its capability to be operated over 500 kW to 1500 kW range with oxygen temperatures from 15°C to 600°C or higher without any coking inside the lance or at the burner nozzle. HFO temperature was maintained below flash point (~140°C), at any given oxygen temperature. Flame shape and NOx emissions will also be reported. [ABSTRACT FROM AUTHOR]

We have developed and built a small porous-plug burner based on the original McKenna burner design. The new burner generates a laminar premixed flat flame for use in studies of combustion chemistry and soot formation. The size is particularly relevant for space-constrained, synchrotronbased X-ray diagnostics. In this paper, we present details of the design, construction, operation, and supporting infrastructure for this burner, including engineering attributes that enable its small size. We also present data for charactering the flames produced by this burner. These data include temperature profiles for three premixed sooting ethylene/air flames (equivalence ratios of 1.5, 1.8, and 2.1); temperatures were recorded using direct one-dimensional coherent Raman imaging. We include calculated temperature profiles, and, for one of these ethylene/air flames, we show the carbon and hydrogen content of heavy hydrocarbon species measured using an aerosol mass spectrometer coupled with vacuum ultraviolet photoionization (VUV-AMS) and soot-volume-fraction measurements obtained using laser-induced incandescence. In addition, we provide calculated mole-fraction profiles of selected gas-phase species and characteristic profiles for seven mass peaks from AMS measurements. Using these experimental and calculated results, we discuss the differences between standard McKenna burners and the new miniature porous-plug burner introduced here. [ABSTRACT FROM AUTHOR]

This paper aims at elaborating alternative methods to determine the fuel consumption for a gas burner, detailing the method both from the theoretical aspect and the experimental aspect. Indirect determination of the fuel consumption for a gas burner is necessary both when there is no gas flow meter installed and when a group of burners is coupled at a single gas flow meter, and there is the need of determining the consumption of a single or more burners. [ABSTRACT FROM AUTHOR]

This paper presents the design of a cost effective energy system for National Centre for Hydropower Research and Development (NACHRED) building to supply its daily energy requirements. The daily hourly load demand of the building was measured with FLUKE 434 Series II Energy Analyzer. The measurement was grouped into two namely: category 1 and category 2. In category 1, the essential electrical load demand excluding air conditioner system was measured for 3 consecutive days while in category 2 the total daily load demand including air conditioner system was also measured for three consecutive days. HOMER pro3.2 was used to size and simulate photovoltaic system required for the two categories. The system in category 1 with the load of an average consumption of 36.34kWh/d, is considered as a cost effective system for the building, as compared to one in category 2 with the load of an average consumption of 198.1kWh/d. [ABSTRACT FROM AUTHOR]

The ignition behavior of a non-premixed multiple-burner annular combustion chamber was investigated numerically, focusing on the stochasticity and average speed of the light-round mechanism ensuring flame propagation from burner to burner that have been observed experimentally. During the propagation sequence, the flame expansion process is tracked by a previously developed stochastic low-order ignition model adapted to full combustor ignition. A stochastic model based on the probability that a flame fragment coming from an ignited burner leads to successful ignition of the next un-ignited one is developed in order to explain and quantify the global ignition behavior of the combustor. The stochastic behavior of the rig, highlighted through the experimentally observed variability of the burner-to-burner propagation times during the ignition sequence, was clarified and quantified. The lean light-round ignition limiting conditions and the mean light-round speed measured experimentally are explained and reasonably accurately predicted, demonstrating the validity of the use of the probabilistic model together with the low-order ignition model for the combustor considered. The results presented in this paper can be used to predict the ignition envelope of annular gas turbines combustors at the design stage. [ABSTRACT FROM AUTHOR]

This paper describes the development of an infrared laser absorption tomography system for the 3D volumetric imaging of chemical species and temperature in reacting flows. The system is based on high-resolution near-infrared tunable diode laser absorption spectroscopy (TDLAS) for the measurement of water vapour above twin, mixed fuel gas burners arranged with an asymmetrical output. Four parallel laser beams pass through the sample region and are rotated rapidly in a plane to produce a wide range of projection angles. A rotation of 180° with 0.5° sampling was achieved in 3.6 s. The effects of changes to the burner fuel flow were monitored in real time for the 2D distributions. The monitoring plane was then moved vertically relative to the burners enabling a stack of 2D images to be produced which were then interpolated to form a 3D volumetric image of the temperature and water concentrations above the burners. The optical transmission of each beam was rapidly scanned around 1392 nm and the spectrum was fitted to find the integrated absorbance of the water transitions and although several are probed in each scan, two of these transitions possess opposite temperature dependencies. The projections of the integrated absorbances at each angle form the sinogram from which the 2D image of integrated absorbance of each line can be reconstructed by the direct Fourier reconstruction based on the Fourier slice theorem. The ratio of the integrated absorbances of the two lines can then be related to temperature alone in a method termed, two-line thermometry. The 2D temperature distribution obtained was validated for pattern and accuracy by thermocouple measurements. With the reconstructed temperature distribution, the temperature-dependent line strengths could be determined and subsequently the concentration distribution of water across the 2D plane whilst variations in burner condition were carried out. These results show that the measurement system based on TDLAS can be used for 2D temporal or 3D volume imaging of temperature and chemical species concentration in reacting flows. [ABSTRACT FROM AUTHOR]

Oxy-fuel coal combustion, together with carbon capture and storage or utilization, is a set of technologies allowing to burn coal without emitting globe warming CO2. As it is expected that oxy-fuel combustion may be used for a retrofit of existing boilers, development of a novel oxy-burners is very important step. It is expected that these burners will be able to sustain stable flame in oxy-fuel conditions, but also, for start-up and emergency reasons, in conventional, air conditions. The most cost effective way of achieving dual-mode boilers is to introduce dual-mode burners. Numerical simulations allow investigation of new designs and technologies at a relatively low cost, but for the results to be trustworthy they need to be validated. This paper proposes a workflow for design, modeling, and validation of dual-mode burners by combining experimental investigation and numerical simulations. Experiments are performed with semi-industrial scale burners in 0.5 MWt test facility for flame investigation. Novel CFD model based on ANSYS FLUENT solver, with special consideration of coal combustion process, especially regarding devolatilization, ignition, gaseous and surface reactions, NOx formation, and radiation was suggested. The main model feature is its ability to simulate pulverized coal combustion under different combusting atmospheres, and thus is suitable for both air and oxy-fuel combustion simulations. Using the proposed methodology two designs of pulverized coal burners have been investigated both experimentally and numerically giving consistent results. The improved burner design proved to be a more flexible device, achieving stable ignition and combustion during both combustion regimes: conventional in air and oxy-fuel in a mixture of O2 and CO2 (representing dry recycled flue gas with high CO2 content). The proposed framework is expected to be of use for further improvement of multi-mode pulverized fuel swirl burners but can be also used for independent designs evaluation. [ABSTRACT FROM AUTHOR]

This paper presents some results of Volumetric V3V 3D3C velocity measurements on a turbulent flow from a swirl burner. The flow out from the burner used is highly three-dimensional. The study aims at using a system of instantaneous 3D velocity measurements in order to characterize the turbulent swirling flow. The burner used consists of two coaxial tubes with a swirler placed in an annular part supplying the oxidant flow. The central pipe delivers the fuel radially (in the case of reacting flow) through eight holes symmetrically distributed on the periphery of the tube. The burner is placed at the bottom of a combustion chamber and the flow develops vertically along the confinement. The Volumetric 3-component Velocimetry V3V® technique commercialized by TSI is used for 3D velocity measurements in a non reacting flow. The measurement volume above the burner is located at 1.3D b (=49.4 mm) and is 50×50×22 mm 3 . The operating conditions considered in this study are 4.67 m/s of bulk velocity, Re=7531 of Reynolds number and Sn=1.4 of swirl number. There are very limited works on the application V3V technique on fluid flows. This paper presents the first results concerning an isothermal non-reacting gas flow. Instantaneous and mean velocity 3D3C volumes are measured and shown. Streamlines and velocity iso-surfaces are also analyzed together with different velocity profiles. The results are compared to previous SPIV (Stereoscopic Particle Image Velocimetry) measurements performed by the authors. A good agreement is found between the results of both techniques; the discrepancy did not exceed 10%. V3V results allowed a fine description of 3D aspects of the flow including the recirculation zone and the annular zone with swirling jet effects. The swirling part of the flow and the central recirculation zone are clearly identified by 3D fields of velocities and streamlines. Velocity volume indicates the presence of a central zone with a negative longitudinal velocity, which can reach −1 m/s at the burner center. Under the swirl effect, the tangential velocity is relatively high, particularly in the annular zone of the burner. Indeed, this velocity is varied between 3 and −3 m/s for a bulk velocity of 4.7 m/s. [ABSTRACT FROM AUTHOR]

This paper presents the study of oxygen-enriched combustion of natural gas and its impact on nitrogen oxides emission. The research were performed on two experimental stands, i.e. combustion chambers with an industrial swirl burner of maximum power equal to 90 kW and 10 kW. The investigation includes the influenced of oxygen enhanced within the range between 21% and 30%. Furthermore, the role of temperature during the oxygen enrichment was analysed. The results of the research showed that with the rise in oxygen concentration in the air the concentration of nitrogen oxides also increases what is directly related to the rise in flame temperature as well as the addition of oxygen. [ABSTRACT FROM AUTHOR]

This paper reports experimental and numerical study of stability and combustion characteristics of premixed oxy-methane flames with hydrogen-enrichment (CH 4 –H 2 /O 2 –CO 2 flames) in a model multi-hole burner for clean energy production in gas turbines. The combustor lean blow-out (LBO) limit was presented on an equivalence ratio (Ø) - hydrogen fraction (HF: volumetric fraction of H 2 in a mixture of H 2 +CH 4) map spanning over Ø-values of 0.1–1 and HF-values of 0–70% at fixed hole jet velocity and oxygen fraction (OF: volumetric fraction of O 2 in a mixture of O 2 +CO 2) of 5.2 m/s and 30%, respectively. The condition of the combustion chamber is assumed to be depicted by the corrugated premixed flame regime. The premixed turbulent flame was modeled using the reaction progress variable flame front topology approach with the Large Eddy Simulation (LES) technique. The recorded combustor stability maps showed great resistance of the micromixer burner technology to flashback, recommending its use for stable gas turbine operation. The results show that H 2 -enrichment widens the combustor operability limits (higher turndown ratio) by extending the LBO from Ø = 0.45 at HF = 0% down to Ø = 0.15 at HF = 70% with a slight reduction in the heat release factor by 0.1. The high reactivity and higher flame speed of H 2 ensures the sustenance of flame at lower equivalence ratios. At high equivalence ratios, H 2 addition enhances the reaction rates and makes both the primary and secondary reaction zones shorter and more intense. Increasing HF leads to increase in the Damköhler number (Da) and decrease in both the Karlovitz number (Ka) and flame thickness. The CO emission at the combustor outlet reduced significantly from 241 ppm at HF = 0% to 33.1 ppm at HF = 10%, then it increased back to 364 ppm at HF = 50%. [Display omitted] • Operability limits are widened with hydrogen addition at the expense of heat release factor. • The micromixer burner showed great resistance to flame flashback. • Results strongly support using micromixer burner in gas turbines for higher turndown ratio. • The reactions in the cases studied are controlled by the laminar burning rate. • CO emission increases with hydrogen addition due to the enhanced reactivity. [ABSTRACT FROM AUTHOR]

This paper presents an optimization formulation and a computational fluid dynamic study for a new proposal of a rustic oven that uses natural gas instead of highly polluting fuels currently used, addressing in this way a real environmental problem in the Mexican state of Guanajuato. In this study, first, a mixed integer linear programming problem was implemented to determine the optimal location of the burner in the rustic oven, and then the combustion process in the oven is modeled. The results show that the temperature is not homogeneously distributed inside the oven and similarly the reactive chemical species involved in the combustion process for all the possible positions of the burner in the oven. On the basis of these results, it was possible to propose an optimal location of the burner providing the best temperature profile to improve the process in the burning of bricks with a best combustion process and reducing the polluting emissions, and it can be stated that on the basis of the results and the advantages mainly related to the environmental issues, the proposed oven can be scaled to an industrial scale and may replace the currently operating ovens. [ABSTRACT FROM AUTHOR]

The last decades have emphasized the requirement for alternative energy sources, particularly in the transport sector, where combustible liquid fuels are expected to dominate in the foreseeable future. In such applications, the fuel must be efficiently atomized, evaporated, and mixed with the combustion air before it reaches the flame front, in order to meet the latest pollutant emission standards. Hence, this paper investigates the utilization of nine different fossil and renewable liquid fuels. The domain of the analysis is a lean premixed prevaporized burner equipped with an air blast atomizer and a mixing tube. Analytical calculations are performed to determine the evaporation process after the atomization; then the evaporation time is compared to the residence time of the droplets in the mixing tube. The effect of preheating both the fuel and the combustion air is also examined to determine proper combustion conditions even for the low volatile crude vegetable oils. [ABSTRACT FROM AUTHOR]

Swirl combustion, whether of gaseous fuels or sprays, forms the basis of many thermal power generation systems and to effective design and optimisation of these complex systems has benefited from the development of reliable computational design tools which employ advanced modelling guided by measurements. Laboratory-scale burners which reduce the scale of the investigative challenge but retain the underlying fundamental behaviours associated with full- or pilot-scale set-ups play a key role in these advances. Such laboratory-scale burner platforms must embody essential phenomena present in full-scale systems such as the formation of primary and secondary recirculation zones. They must also span a dynamic operating envelope which allows the initiation of multi-modal (time varying) instabilities over a range of flame stabilization regimes. This paper presents a fixed-scope overview of experimental works on laboratory-scale swirl flame burners where significant reporting of results or data bases exists. The study focuses on selected gaseous fuel burners that span premixed, partially premixed and non-premixed combustion over unconfined and confined conditions. Whilst this is by no-means a comprehensive (topical) review into swirl combustion, it is aimed at guiding interested researchers in navigating a way through the vast literature published on laboratory-based swirl burners. These configurations typically encompass highly resolved flow- and/or compositional-fields derived from non-intrusive laser diagnostics. In addition to time-averaged flow-fields, measured data also typically includes flame stability/structure characteristics (flame shape/blow- or lift-off) as well as combustion instabilities. The paper draws upon a wide body of knowledge to summarise the current understanding of the effects of swirl and confinement on flow behaviour, emission characteristics, flame stabilization, and flow instability in laboratory-scale swirl burners. [ABSTRACT FROM AUTHOR]

The alarming rate at which the available fossil fuel-based resources are depleting has raised grave concerns among all stakeholders about the future of the world. These limited energy resources play a very significant role in conventional energy generation techniques and processes. Traditional energy consumption devices must be made more efficient to prolong the availability of fossil fuels. Along with achieving a substantial increase in the efficiency of these devices, it is the need of the hour to focus on minimizing the hazardous emissions resulting from improper combustion and inefficient design, leading to the ever-growing issue of climate change. Porous burners are one of the few energy consumption devices that are known to facilitate efficient combustion along with low emissions of detrimental combustion products. In the porous burner technology, ceramic-based porous media deliver better performance due to their superior physical, chemical, and thermal characteristics compared to metal-based media. The present paper, therefore, provides an overview of the application of different ceramic-based porous media in burner technology. Advancements, particularly over the last twenty years, in the development and use of novel ceramic composites for porous burner applications, have also been discussed. [ABSTRACT FROM AUTHOR]

A plenty of studies on the utilization of biomass alcohol fuels have been conducted, but combustion efficiency and stability of this fuels still need to be improved. Based on biomass alcohol fuels (bio-methanol and bio-ethanol), this paper studied auto-adaptive air distribution characteristics and optimum structure parameters of an ejector burner by numerical simulation method. Also, an experiment was conducted to verify the numerical results. The results show that the mole air entrainment ratio (MAER) keeps almost constant when the ejector fuel nozzle exit locates at the segment between the ejector throat and the suction chamber entrance, but a bigger ratio α would lead to a higher MAER till the α is bigger than 8.5 for bio-methanol and 11.5 for bio-ethanol. The bio-ethanol fuel is more beneficial for air carrying role because of its big molecular weight. Operation pressure (Pw) has a little impact on MAER of the two fuels, but the rise of back pressure (Pb) would lead to rapid decrease of MAER for the two fuels. For the optimum structure burners, the MAER can be maintained at the value of theoretical complete combustion. Its changing rate is less than 2.3% for bio-methanol and 2.5% for bio-ethanol when the burner load changes from 30% to 120%, which is highly consistent with the experimental results. The optimum burner can distribute air supply automatically with the changing of burner load. [ABSTRACT FROM AUTHOR]

Flame flatness is one of the most critical factors in evaluating the performance of a flat-flame burner. In this paper, the flame flatness of a flat-flame burner is validated using a resolution-doubled one-dimensional wavelength modulation spectroscopy tomography (1D-WMST) technique that only uses one view of multiple parallel laser beams. When the interval of two neighboring parallel laser beams is Δ r, a designed novel geometry of the parallel laser beams realizes a doubled tomographic resolution of Δ r/2. Using the proposed technique, the distributions of temperature and HO mole fraction in an axisymmetric premixed flame are simultaneously reconstructed and hence the flame flatness of a flat-flame burner can be validated. The flatness factor is quantitatively described by the similarity between the reconstructed and expected distributions of HO mole fraction. For flat and non-flat flames, the experimental results agree well with the CFD simulation results, denoting that the resolution-doubled 1D-WMST technique provides a noninvasive, reliable and low cost way to validate the flame flatness of the flat-flame burner. [ABSTRACT FROM AUTHOR]

In this paper, a radiant metal porous burner which is formed from wire mesh layers is studied. Surface temperature of the burner is measured in different equivalence ratios and firing rates and radiation efficiency is calculated for each case. The experiments are performed for different thicknesses of the porous medium. The results show that the surface temperature increases with increasing firing rate and maximum surface temperature occurs in a lean mixture. Comparing the results for different thicknesses shows that maximum surface temperature is obtained in a medium with three-layer of wire mesh. The radiation efficiency of the burner decreases with increasing firing rate. The maximum radiation efficiency is about 30 percent which is obtained in three-layer of wire mesh in the minimum firing rate. Comparison of the results with the other works shows a good agreement between them. [ABSTRACT FROM AUTHOR]

In the present paper, the flames imitating Moderate and Intense Low Oxygen Dilution (MILD) combustion are studied using the Probability Density Function (PDF) modeling approach. Two burners which imitate MILD combustion are considered for the current study: one is Adelaide Jet-in-Hot-Coflow (JHC) burner and the other one is Delft-Jet-In-Hot-Coflow (DJHC) burner. 2D RANS simulations have been carried out using Multi-environment Eulerian Probability Density Function (MEPDF) approach along with the Interaction-by-Exchange-with-Mean (IEM) micro-mixing model. A quantitative comparison is made to assess the accuracy and predictive capability of the MEPDF model in the MILD combustion regime. The computations are performed for two different jet speeds corresponding to Reynolds numbers of Re = 4100 and Re = 8800 for DJHC burner, while Re = 10000 is considered for the Adelaide burner. In the case of DJHC burner, for Re = 4100, it has been observed that the mean axial velocity profiles and the turbulent kinetic energy profiles are in good agreement with the experimental database while the temperature profiles are slightly over-predicted in the downstream region. For the higher Reynolds number case (Re = 8800), the accuracy of the predictions is found to be reduced. Whereas in the case of Adelaide burner, the computed profiles of temperature and the mass fraction of major species (CH4, H2, N2, O2) are found to be in excellent agreement with the measurements while the discrepancies are observed in the mass fraction profiles of CO2 and H2O. In addition, the effects of differential diffusion are observed due to the presence of H2 in the fuel mixture. [ABSTRACT FROM AUTHOR]

Fuel for high-energy solid fuel combustion systems must meet abundant availability, affordability, and environmental friendliness criteria, particularly having low greenhouse gas emissions. One type of fuel that meets these criteria is bio-coal. Gasification burners employ staged combustion techniques that enhance combustion efficiency and reduce the formation of harmful substances, making them more environmentally friendly. This article discusses the performance testing of gasification burners using bio-coal as fuel, with variable primary air flow rates of 25, 30, 35, 40, and 50 m3/hour and biomass percentages in the bio-coal of 25%, 50%, and 75% by weight. The parameters observed are burner capacity, temperature, and CO2 gas emission factor. The experimental results show that increasing the air flow rate from 25 to 35 m3/hour significantly increases burner capacity and temperature, while further increasing the primary air flow rate to 50 m3/hour results in a gradual increase in burner capacity. The experiments also indicate that increasing the biomass percentage in the bio-coal slightly increases burner capacity and temperature due to the similar calorific values of palm pellet and coal used. The gasification burner technology developed by BBP Tekmira has proven to operate effectively within a capacity range of 8 to 20 kg/hour for bio-coal fuel with biomass percentages ranging from 25% to 75% by weight, producing burner temperatures between 805 and 933 degrees Celsius. Using bio-coal for gasification burners has also been shown to reduce greenhouse gas emissions when the biomass percentage in biocoal exceeds 64%. [ABSTRACT FROM AUTHOR]

As the need to minimize environmental impacts continues to rise, it is essential to incorporate, advance, and adopt renewable energy sources and materials to attain climate neutrality in industrial operations. It is established that economic growth is built upon infrastructure, where the cement industry plays a crucial role. However, it is also known that this industry is actively looking for ways to transition toward low-carbon practices to encourage sustainable and environmentally conscious practices. To this end, the use of refuse-derived fuels to substitute fossil fuels is very appealing, as these have the potential to lower clinker production costs and CO2 emissions. Bearing this in mind, the primary objective of this work is to gain insights into the combustion behavior in an industrial rotary kiln by studying real-life scenarios and to assess the potential of substituting alternative fuels for fossil fuels to reduce CO2 emissions. A 3D CFD turbulent combustion model was formulated in Ansys® considering a Pillard NOVAFLAM® burner, where refuse-derived and petcoke fuels were used, and different secondary air mass flows were considered. From the obtained results, it was possible to conclude that the outcome of the combustion process is greatly influenced by the fuel-to-air ratio. Increasing the secondary air mass flow promotes the occurrence of a complete and efficient combustion process, leading to enhanced fuel conversion and the decreased formation of pollutants such as CO, soot, and unburned hydrocarbons. An increase in combustion efficiency from 93% to 96% was observed, coupled with a slight decrease in the pollutant mass fraction in the flue gas. [ABSTRACT FROM AUTHOR]

This article describes an experimental study on solid olive residue (olive cake) combustion in form of pulverized jet. This is a contribution to the valorization of olive residue as a source of renewable energy available in the majority of mediterranean countries. A sample of olive cake from Tunisian origin is prepared for the experiment; this sample is crushed, dried and sifted in order to obtain the desired particles form. A new burner made up of a coaxial cylindrical tube is especially designed and fabricated. In order to start the combustion of olive cake and maintain the main flame, two types of pilot flame were used: a central premixed flame of methane/oxygen and an annular diffusion flame of methane. This paper shows the conditions for an efficient olive cake burner operation in free air. The effects of particle size and pilot flame position have been discussed. The olive cake combustion is possible only with particles at a size below 200 μm. Moreover, the combustion maintained by the annular pilot flame ensures better burning conditions than the central pilot flame. Finally, the inserted preheating system has improved the olive cake combustion. [ABSTRACT FROM AUTHOR]

The conical tunnel burner is an improvement of the cylindrical tunnel burner because, by maintaining all its advantages by means of burning intensification, it may also insure the flame stabilization in a wide range of regulation with considerable diminished pressure losses. Technical applications for the conical furnace burner can vary due to the limited dimensions required by the system, as well as the important thermal loads, and also because of the burning stability characteristic that spreads over an important range of regulation. The low costs required by the burner, generated mainly by its simple construction, also raise the interest for this technical solution. A physical model is proposed for the ignition and flame front stabilization. The flame front stabilization contains different steps from the ignition moment to final flame front stabilization, with specific flame front geometries and specific locations along the burner axis. The installation realised by the authors allowed the experimental study of the burning process in conical furnaces, in order to determine the temperature fields and the flame profiles. The physical model developed for this new type of application and the experimental data sets obtained (along with their interpretation) make the subject of this paper. [ABSTRACT FROM AUTHOR]

Copyright of Archives of Metallurgy & Materials is the property of Polish Academy of Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents the results of 3D numerical flow simulation in the ventilation mill (VM) and air mixture channel (AMC) of Kostolac B power plant, where a centrifugal separator with adjustable blade angle is used. Numerical simulations of multiphase flow were performed using the Euler-Euler and the Euler-Lagrange approach of the ANSYS FLUENT software package. The geometry of the numerical model was almost identical to the VM and AMC of Kostolac B, except for the smallest details. An unstructured tetrahedral grid, consisted of almost three million cells, was generated. The main contribution of this paper is the original analysis of the influence of centrifugal separator (CFS) geometry modification on the coal powder distribution at the horizontal burners. The modification of the blade angle, blade shape, and vertical position of the separator and its effect on the coal powder distribution at the burners were analyzed and are published for the first time. Results of the numerical simulations were compared with the measurements and can be used in modifying the separator geometry and position to obtain optimal distribution of the pulverized coal at the burners. Application of these results, obtained by numerical methods, ensures significant savings in time and money, in the process of finding the optimal geometry of CFS. [ABSTRACT FROM AUTHOR]

This paper represents a synthesis of the legislation, of the Romanian and foreign scholarly literature related to the selection of hot water boilers, as well as of their respective burners. This paper is among the first tries of this type from Romania. The conclusions of this paper are useful both for the designers as well as for the beneficiaries, in order for them to choose hot water boilers, and their respective burners. The proposed method has a practical use in case of feasibility studies, master degree theses, as well as of Ph.D. theses. [ABSTRACT FROM AUTHOR]

This paper presents a model for thermo-acoustic effects in a gas turbine combustor. A quarter-wavelength burner with rectangular cross-section has been built and studied from an experimental and theoretical perspective. It has a premixed methane-air flame, which is held by a bluff body, and spans the width of the burner. The flame is compact, i.e. its length is much smaller than that of the burner. The fundamental mode of the burner is unstable; its frequency and pressure distribution have been measured. The complex pressure reflection coefficients at the upstream and downstream end of the burner were also measured. For the theoretical considerations, we divide the burner into three regions (the cold pre-combustion chamber, the flame region and the hot outlet region), and assume one-dimensional acoustic wave propagation in each region. The acoustic pressure and velocity are assumed continuous across the interface between the precombustion chamber and flame region, and across the interface between the flame region and outlet region. The burner ends are modelled by the measured pressure reflection coefficients. The mean temperature is assumed to have the following profile: uniformly cold and uniformly hot in the pre-combustion chamber and outlet region, respectively, and rising continuously from cold to hot in the flame region. For comparison, a discontinuous temperature profile, jumping directly from cold to hot, is also considered. The eigenfrequencies are calculated, and the pressure distribution of the fundamental mode is predicted. There is excellent agreement with the experimental results. The exact profile of the mean temperature in the flame region is found to be unimportant. This study gives us an experimentally validated Green's function, which is a very useful tool for further theoretical studies. [ABSTRACT FROM AUTHOR]

The solution for dynamic modeling of reheating furnaces requires a burner model, which is simultaneously accurate and fast. Based on the fact that radiative heat transfer is the most dominant heat transfer mode in high-temperature processes, the present study develops a simplified flame representation model that can be used for dynamic simulation of heat transfer in reheating furnaces. The first part of the paper investigates, experimen-tally and computationally, gas combustion in an industrial burner. Experiments aim at establishing an experimental database of the burner characteristics. This database is compared with numerical simulations in order to establish a numerical model for the burner. The numerical burner model was solved using a commercial computational fluid dynamics (CFD) software (FLUENT 6.3.26). A selection of results is presented, highlighting the usefulness of CFD as a modeling tool for industrial scale burners. In the second part of the paper, a new approach called the "emissive volume approach" is established. This approach consists of replacing the burner flame by a number of emissive volumes that replicates the radiative effect of the flame. Comparisons with CFD results show a difference smaller than 1% is achieved with the emissive volume approach, while computational time is divided by 40. [ABSTRACT FROM AUTHOR]

The development of environmental technologies and its diffusion across countries are of key importance for international environmental policy. This paper considers technologies in the area of glass-melting furnaces and glass burners, which are major contributors of NO emissions. Using patents as an indicator of innovations and patent citations as a proxy for knowledge flows, the inducement of new environmental and non-environmental technologies and their diffusion within and across countries, patent applicant types and patent firm types are analyzed in relation to NO-related environmental policy. We find that most environmental patents originate from the USA and Germany and are filed by a broad range of firms. Most knowledge flows take place within countries. Regarding cross-country flows, most environmental knowledge diffuses from US patents, which is likely to be a result of early strict environmental legislation in some areas of the USA. [ABSTRACT FROM AUTHOR]

Combustion in inert porous burners has been focused in numerous research works which have been demonstrated the advantages of this technique. In this paper, a 3-D cubic model is used to derive the governing equations for porous medium and gas phase to obtain heat transfer characteristics of porous radiant burners (PRBs). Non-local thermal equilibrium between the gas and solid phases is accounted for by separate energy equations for two phases. The porous medium is assumed to be homogenous and in addition to convective heat exchange with the gas, may absorb, emit and scatter thermal radiation, while the gas phase is considered transparent to radiation and heat transfer occurs only by conduction and convection. In order to determine the thermal characteristics of the porous radiant burner, the coupled energy equations and radiative transfer equation (RTE) in steady condition are solved using a numerical iterative procedure. Furthermore, the radiative part of the energy equation is solved using the discrete ordinates method (DOM). Finally, the effects of the various factors on the performance and thermal behavior of porous radiant burner are determined. [ABSTRACT FROM AUTHOR]