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Littérature scientifique sur le sujet « Boiler efficiency characterization »
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Articles de revues sur le sujet "Boiler efficiency characterization"
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Barcelos, Sheyla Thays Vieira, Ismael Plácido Tomielis, Marli Da Silva Garcia et Marney Pascoli Cereda. « Characterization of boiler ashes from sugarcane mill ». Revista Ibero-Americana de Ciências Ambientais 10, no 3 (17 juillet 2019) : 179–90. http://dx.doi.org/10.6008/cbpc2179-6858.2019.003.0016.
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Sugarcane mills produce sugar and ethanol and have always used bagasse as fuel to generate energy for self-consumption. Recently some mills have been also producing surplus electricity to sell in the market a third product from sugarcane. Although any boiler can be efficient, the sale of electricity has stimulated the improvement of the burning process. However, the investment in high-pressure boilers, much more expensive than any common boiler, is essential for the exportation of electricity. Among the 22 sugarcane mills from Mato Grosso do Sul, Brazil, only 12 power plants sell electricity to the grid. The power generation efficiency depends on the pyrolysis in boilers, which results in ashes that match the unburned mineral fraction of the fuel as oxide. Both the bagasse and the straw are composed predominantly of lignin, hemicellulose and cellulose with calorific power near to the wood at the same moisture content. However the bagasse leaves the mill with about 50% of moisture while the straw reaches the industry with about 15% of humidity. This paper characterize the ashes samples from burned bagasse from seven sugarcane mills at Mato Grosso do Sul Brazilian state, to compare the methodology available for use to measure the efficiency of the pyrolysis system. Among these sugarcane mills only two are highlighted by their higher burning efficiency, both of them selling electricity, while the others showed unburned portions characterizing an inefficient system. For these industries the ash content in the ashes showed values compatible with the Superior Calorific Value as an efficiency index for the combustion degree in boilers.
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Mameri, Fateh, Eric Delacourt, Céline Morin et Jesse Schiffler. « 0D Dynamic Modeling and Experimental Characterization of a Biomass Boiler with Mass and Energy Balance ». Entropy 24, no 2 (28 janvier 2022) : 202. http://dx.doi.org/10.3390/e24020202.
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The paper presents an experimental study and a 0D dynamic modeling of a biomass boiler based on the Bond Graph formalism from mass and energy balance. The biomass boiler investigated in this study is an automatic pellet boiler with a nominal power of 30 kW with a fixed bed. The balances allow to model as time function the flue gas enthalpy flux variation and the thermal transfers between the flue gas and the walls of the boiler subsystems. The main objective is to build a model to represent the dynamic thermal behavior of the boiler. Indeed, small domestic boilers have discontinuous operating phases when the set temperature is reached. The global thermal transfer coefficients for the boiler subsystems are obtained according to an iterative calculation by inverse method. The boiler has an average efficiency of 67.5% under our operating conditions and the radiation is the dominant thermal transfer by reaching 97.6% of the total thermal transfers inside the combustion chamber. The understanding of the dynamic behavior of the boiler during the operating phases allows to evaluate its energy performances. The proposed model is both stimulated and validated using experimental results carried out on the boiler.
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Chandrasekaran, Sriraam R., Philip K. Hopke, Michael Newtown et Arthur Hurlbut. « Residential-Scale Biomass Boiler Emissions and Efficiency Characterization for Several Fuels ». Energy & ; Fuels 27, no 8 (6 août 2013) : 4840–49. http://dx.doi.org/10.1021/ef400891r.
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Li, Jin Ping, Jin Hua Gan et Ying Ming Chen. « Preparation of a Sulfate-Based Complex Coagulant from Boiler Slag and its Application in Domestic Sewage Treatment ». Advanced Materials Research 148-149 (octobre 2010) : 259–66. http://dx.doi.org/10.4028/www.scientific.net/amr.148-149.259.
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This paper presents a new way of recycling aluminum and iron in boiler slag derived from coal combustion plants for the production of a sulfate-based complex coagulant containing ferric sulfate and aluminum sulfate. The boiler slag sample was determined for more complete characterization by means of scanning electron microscopy(SEM), X-ray diffraction(XRD), X-ray fluorescence(XRF) and other techniques. An analysis for the boiler slag sample collected from Baotou Steel Plant located in Inner Mongolia, PR China showed that the quantity of iron and aluminum oxides, in general, accounted for about 35% of the boiler slag. XRD analysis indicates that predominate minerals such as kaolinite, quartz, calcium silicide, hematate and metakoalin exist in this boiler slag. This boiler salg was evaluated to determine the efficiency of converting the iron and aluminum components of the material into a sulfate-based complex coagulant when heated with sulfuric acid at different temperatures and reaction times. The maximum concentrations of Fe3+ and Al3+ in the complex coagulant prepared from the boiler slag were obtained at 130 and after 3 h of reaction time. These concentrations were 0.04 M Fe3+ and 0.46 M Al3+, respectively. The corresponding conversion efficiencies of aluminum and iron were 66.2 and 95.0% in the boiler slag, respectively. Finally, the prepared sulfate-based complex coagulant proved to be an effective agent for reducing the turbidity and chemical oxygen demand(COD) of a typical domestic sewage sample.
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Peta, Sandile, Chris du Toit, Reshendren Naidoo, Walter Schmitz et Louis Jestin. « Investigations of operation problems at a 200 MWe PF boiler ». Chemical and Process Engineering 36, no 3 (1 septembre 2015) : 305–20. http://dx.doi.org/10.1515/cpe-2015-0021.
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Abstract To minimize oxides of nitrogen (NOx) emission, maximize boiler combustion efficiency, achieve safe and reliable burner combustion, it is crucial to master global boiler and at-the-burner control of fuel and air flows. Non-uniform pulverized fuel (PF) and air flows to burners reduce flame stability and pose risk to boiler safety by risk of reverse flue gas and fuel flow into burners. This paper presents integrated techniques implemented at pilot ESKOM power plants for the determination of global boiler air/flue gas distribution, wind-box air distribution and measures for making uniform the flow being delivered to burners within a wind-box system. This is achieved by Process Flow Modelling, at-the-burner static pressure measurements and CFD characterization. Global boiler mass and energy balances combined with validated site measurements are used in an integrated approach to calculate the total (stoichiometric + excess) air mass flow rate required to burn the coal quality being fired, determine the actual quantity of air that flows through the burners and the furnace ingress air. CFD analysis and use of at-the-burner static, total pressure and temperature measurements are utilized in a 2-pronged approach to determine root-causes for burner fires and to evaluate secondary air distribution between burners.
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Hansted, Ana Larissa Santiago, Felipe Augusto Santiago Hansted, João Otávio Poletto Tomeleri, Thiago Aguiar Cacuro, Carlos Roberto Sette Jr., Fábio Minoru Yamaji et Vladimir Eliodoro Costa. « Biomass in an industrial boiler : characterizing and reducing waste from the burning process ». Research, Society and Development 11, no 9 (15 juillet 2022) : e45511931948. http://dx.doi.org/10.33448/rsd-v11i9.31948.
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Ashes constitute a waste produced in the heat generation process from bioenergy. This study aimed to improve the biomass energy efficiency used in an industrial boiler. The physicochemical analysis was used to perform improvement in the quality of the biomass for solid fuel. Four biomass types (eucalyptus bark, wood chips, sawdust, and recycled wood waste) were analyzed. The material (ash) was collected every two months over one year. All samples were characterized regarding proximate analysis, chemical composition (macro and micronutrients), morphological characterization (via scanning electron microscopy [SEM] coupled with dispersive energy spectroscopy [EDS]), and particle size distribution. The four biomass types presented significant differences in moisture content and proximate analysis. The bark showed a high percentage of impurities with an ash content of 26.99%. It was possible to reduce the ash content of the biomass inserted into the boiler in half, by separating the bark in the granulometric strata and excluding the smallest particle size (<0.84 mm). The results regarding the ashes showed that chemical composition and physical attributes were similar in all samples over the year. The chemical components were the same, although they varied in quantity. It is possible to improve the biomass energetic performance by excluding the smallest particles prior to the boiler insertion.
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A. M., Kola. « EVALUATION OF WASTE MANAGEMENT SYSTEMS IN A KENYAN TEA FACTORY : A CASE STUDY OF MARAMBA TEA FACTORY IN KIAMBU COUNTY ». Journal of Engineering in Agriculture and the Environment 6, no 1 (30 juin 2020) : 31. http://dx.doi.org/10.37017/jeae.v6i1.65.
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This paper evaluates the effectiveness of waste management systems in Maramba Tea Factory in Kiambu County, Kenya. Performance of the already existing systems is therefore critical in sustaining our environment. Tea processing generates different types of wastes. A waste management system design should at least begin from a clear characterization of these wastes, the quantities and qualities of the wastes and identification of sources. This study attempted to bring these challenges to the fore. It evaluated the waste management systems for Maramba Tea factory in Kiambu County, Kenya. Primary data and secondary data, Purposively and Convenience sampling techniques, Benchmarking evaluation technique were utilised. The types of wastes identified were organic solid wastes, inorganic solid wastes, Liquid wastes and Thermal wastes. The quantities of wastes were determined by weighing. The Organic solid wastes from tea processing stages was 486.47 kilograms per month and inorganic solid wastes (sacks and polythene bags) was 15.38 kilograms per month. The amount of liquid wastes generated for the study period were estimated. The highest with major cleaning done weekly averaged of 139.4m3 and least with minor cleaning done daily averaged at 52.8m3. The thermal wastes generated was due to heat loss from the wood fuel used as a source of energy. The total amount of heat loss was 1145.51kcal/kg representing 37.45%. of the Gross Calorific Value (GCV) of wood fuel. The highest heat loss was due to dry flue gas with a 22.09% of GCV of wood fuel representing 675.85kcal/kg and the least due to moisture present in the combustion air at 24.78kcal/kg representing 0.810 % of the total GCV of wood fuel. The qualities of wastewater were achieved through analysing the BOD5, COD, pH and Electrical conductivity and comparing the values to the standards recommended by National Environment Management Authority (NEMA). The BOD5 at 83.7mg/L and COD at 106.63mg/L exceeded the NEMA limits of 30mg/L and 50mg/L respectively. The thermal waste systems were evaluated by determining the boiler efficiency. Boiler efficiency at Maramba Tea Factory was 62.55%. The boiler efficiency of 62.55% is lower compared to the set values of 75.01% and 75%. The analysis with ANOVA showed significant differences in the water parameter values from source through the lagoon to the river. The coefficient of determination (R2) for most of the parameter analysed were above 97%. It was concluded that the waste management systems are only partially effective at Maramba Tea Factory. More targeted studies need to be carried out in other food industries to make a general conclusion on the state of waste management systems in Kenya.
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Pavan, A. H. V., R. Ravibharath et Kulvir Singh. « Creep-Rupture Behavior of SUS 304H – IN 617 Dissimilar Metal Welds for AUSC Boiler Applications ». Materials Science Forum 830-831 (septembre 2015) : 199–202. http://dx.doi.org/10.4028/www.scientific.net/msf.830-831.199.
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Advanced Ultra Super-Critical (AUSC) power plants are envisaged for achieving higher thermodynamic efficiency by operating at temperatures and pressures of 710/720 °C and 310 ata, respectively which are significantly higher than sub-critical (conventional) and supercritical power plants. This has led to tremendous research in selection of new and advanced materials to meet high temperature requirements. Ni-base superalloys having known to have excellent creep-rupture behavior were selected for high temperature sections of boiler while austenitic stainless steels were selected for moderately high temperature sections considering the economical feasibility. Since both these materials have to be fabricated for application in boiler tubes, dissimilar metal welding is inevitable. This work discusses creep-rupture evaluation of one such case of dissimilar welds, i.e., between Inconel 617 (IN 617) and SUS 304H. IN 617 is a Ni-base superalloy while SUS 304H is a Cu-precipitated austenitic stainless steel. Welding was carried out using IN 617 filler material for producing defect free welds. Creep-rupture samples were prepared incorporating the complete cross-weldment for understanding mechanical behavior as a result of prolonged exposure to elevated temperature and stresses. Creep-rupture testing was carried out at 600, 650 and 700°C at suitable stresses to obtain rupture times in the excess of 3000 hours in a few test conditions. Detailed characterization studies when carried out on ruptured samples revealed the weakest zone to be heat affected zone towards SUS 304H which led to failure. This work also provides insight into the possible creep-mechanisms that operate in various zones of weldments. Phases formed as a result of exposure to stress and temperature for a prolonged duration are also discussed. Comparison of the data obtained with data available in literature was carried out and performance of weldments was analyzed and reported.
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Lv, Qiang, Chang’an Wang, Yang He, Ming Cai et Defu Che. « Elemental Mercury Removal over CeO2/TiO2 Catalyst Prepared by Sol–Gel Method ». Applied Sciences 10, no 8 (14 avril 2020) : 2706. http://dx.doi.org/10.3390/app10082706.
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Elemental mercury (Hg0) emitted from a coal-fired boiler is a serious menace and challenge to humans. Using high-efficiency CeO2/TiO2 catalysts to enhance the conversion from elemental mercury to oxidized mercury is a promising approach to reducing Hg0 emission. However, most of the CeO2/TiO2 catalysts were prepared by impregnation method or coprecipitation method while little attention has been paid to sol–gel method, which has many advantages in material production. In this study, a series of catalysts were synthesized through the sol–gel method to remove the gaseous Hg0 from simulated flue gas. The effect of vanadium (V) on Hg0 removal efficiency and the simultaneous removal of Hg0 and NO were also investigated. The results showed the optimal temperature for Hg0 removal over the CeO2/TiO2 catalysts was 350 °C. The oxidation of Hg0 could be promoted by O2, HCl, and NO, but inhibited by NH3 and SO2. The addition of vanadium could enhance the Hg0 removal performance and the resistance to NH3 and SO2. A synergetic effect was found during the simultaneous removal of Hg0 and NO. The high redox reaction reactivity of Ce4+/Ce3+ and V5+/V4+ should take the credit for the oxidation of Hg0 and the removal of NO. Based upon the performance tests and the characterization experiments of the samples, the detailed mechanisms of the Hg0 and NO removal over the catalysts were proposed.
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Chandrasekaran, Sriraam R., James R. Laing, Thomas M. Holsen, Suresh Raja et Philip K. Hopke. « Emission Characterization and Efficiency Measurements of High-Efficiency Wood Boilers ». Energy & ; Fuels 25, no 11 (17 novembre 2011) : 5015–21. http://dx.doi.org/10.1021/ef2012563.
Texte intégralThèses sur le sujet "Boiler efficiency characterization"
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Mauro, Antongiulio. « Experimental and numerical characterization of heating domestic appliances for energetic efficiency improvement ». Doctoral thesis, Universita degli studi di Salerno, 2014. http://hdl.handle.net/10556/1984.
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2013 - 2014Every year 5 million of boilers for domestic heating are sold in the European Union (EU). Because heating contributes to more than 20% to the whole energy use in the EU strategies for energy saving are of great interest. Currently in the European Union, efficiency requirements on boilers are becoming more and more stringent: following the common target of the energy reduction, European directives 2005/32/EC on the eco-design of energy-using products and 2009/125/EC on the energy-related products, oblige the labeling of boilers and water heaters in performance categories. Furthermore, EU policy is to phase out appliances with low performance, by no longer giving the right to be sold on the European market. The regulation on the Energy related products (Erp) which enters into force from 26th of September 2015 sets efficiency bans so that low efficiency boilers are going to be excluded from EU market. As a consequence, boilers manufacturers should face significant investments in terms of efficiency oriented product-development. Furthermore, robust measurements become necessary to establish correct performance categories and not generate conflicts with surveillance bodies. In the present PhD thesis work, carried out at Ariston Thermo Group in Osimo R&D center, experimental and modeling activities have been performed and reported concerning domestic heating appliances. A comprehensive analysis of energy fluxes has been carried out on domestic methane supplied gas boilers, different methods for efficiency estimation have been compared with related measurement uncertainties. The boiler energy balance closing problem has been undertaken through a novel statistical approach, subsequently, an uncertainty related risk analysis has been performed on space heating efficiency and water heating efficiency according to Erp regulation. Afterward, appliances insulation testing methods have been set-up and compared, in particular an automated test rig has been constructed and thermal camera measurements have been performed. Using such methods, boilers and tank losses have been characterized... [edited by Author]
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Actes de conférences sur le sujet "Boiler efficiency characterization"
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Tillman, David A. « Petroleum Coke as a Supplementary Fuel for Cyclone Boilers : Characteristics and Test Results ». Dans 2002 International Joint Power Generation Conference. ASMEDC, 2002. http://dx.doi.org/10.1115/ijpgc2002-26157.
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Petroleum coke is periodically tested and used as a supplementary fuel for cyclone boilers. Its high heat content and low cost make it an attractive fuel for power generation. In cyclone boiler firing, it also has environmental advantages. While it is high in sulfur content, it can be used to reduce NOx emissions along with such trace metal emissions as mercury and arsenic. Successful firing of petroleum coke in cyclone boilers, however, requires considerable attention to fuel properties of the coal and the opportunity fuel including fuel structure and reactivity, and ash chemistries. This paper reviews selected properties of petroleum coke including traditional analyses plus structural characterization using 13Carbon Nuclear Magnetic Resonance (NMR), drop tube reactor (DTR) characterization for kinetics and volatility evaluation, and thermogravimetric analysis (TGA) for char oxidation kinetics. The paper then summarizes results of petroleum coke firing at the Paradise Fossil Plant of TVA, and Bailly Generating Station of Northern Indiana Public Service Company (NIPSCO). Results presented include impacts of cofiring on boiler efficiency, NOx emissions, and the fate of selected trace metals including arsenic, mercury, nickel, and vanadium. It documents the overall benefits and issues associated with cofiring petroleum coke with coal in cyclone boilers as a significant opportunity fuel.
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Antunes, Pedro, Manuel Eduardo Ferreira, Maria Cândida Vilarinho et José Carlos Teixeira. « Energy Analysis and Waste Valorization in a Kraft Paper Plant ». Dans ASME 2020 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/imece2020-24002.
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Abstract Paper production is an energy intensive industry but due to the wastes of its process (black liquor, waste biomass, sludge) has the capacity to generate most of its energy internally. Central to this balance are cogeneration units that guarantee the internal production of heat and electricity. These are sized for the company’s thermal load, with excess electricity injected into the grid. The efficient use of endogenous resources is a major route for improving the energy and environmental efficiency of the plant. Some of the waste materials include biomass wastes, sludges and other industrial wastes such as plastics. The present work aims to identify the opportunity of introducing a waste biomass gasification plant and the use of the produced synthesis gas, replacing the natural gas currently used in the turbine included in the company’s cogeneration unit. In this scenario, one of the cogeneration units in its current configuration has two steam boilers (one biomass; one black liquor) and a gas turbine whose waste heat feeds a recovery boiler to produce steam. The work involved several steps: the energy balance of the unit, the characterization of biomass residues (mixing bark, pine bark, eucalyptus bark, and refuse fibers), the test experimental analysis of residual biomass gasification and the characterization of the synthesis gas produced. In the electric and thermal energy producing units, gas turbines have a working efficiency above 35% while the steam turbines is considerably lower (15%). The efficiency of the chemical recovery boiler (79.5%) is lower than that of the biomass boiler (89.5%). From the experimental analysis of biomass it was found that most of them have a carbon and hydrogen content higher than 48 % and 5 %, respectively. In terms of higher calorific value (HHV), for the biomass where it was possible to determine it, the value is between 19.3 and 23.6 MJ/kg. These properties reveal that the selected biomasses from within the company, have potential as fuels. The limitation on its use may be due to the ash content, which tends to exceed 10 %. A gasification test (90 % eucalyptus biomass and 10 % mixture biomass) was also carried out to produce syngas and further characterization. The calorific value of the gas produced was 18 MJ/kg, with an absolute density of 1.17 kg/m3. It can thus be seen that for a gas turbine with a 35.8 % efficiency with a workload of 29.9 MWe 4.6 kg/s of syngas is required.
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Alvarado, Jorge L., et Hyungseok Nam. « Experimental Investigation of Microexplosion Phenomena in Emulsified Vegetable Oil-Methanol Blends ». Dans ASME 2012 Heat Transfer Summer Conference collocated with the ASME 2012 Fluids Engineering Division Summer Meeting and the ASME 2012 10th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/ht2012-58311.
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Secondary atomization is one of the most attractive and misunderstood effects in the combustion of microemulsified fuel blends. The occurrence of secondary atomization has been studied to determine its effects on improved combustion efficiency especially when low vapor pressure fuels are used. Several methods to detect microexplosion as alternative to secondary atomization have been considered including acoustic signal processing. As part of the physical characterization of an emulsified vegetable oil-methanol blend, microexplosion behavior of fuel blend droplets has been observed to take place under certain environmental conditions. Droplets microexplode as methanol surrounded by vegetable oil molecules flashes or microexplodes under intense temperature and intense droplet pressure. The droplets of emulsified methanol-in-oil break up forming tiny droplets with greater surface-to-volume ratio in the process. To understand the effects of emulsification on microexplosion, characterization of secondary atomization has been performed using a temperature probe, a high-speed camera and an acoustic sound signal processor. Experiments have been conducted at temperatures similar to those encountered in liquid fuel boilers. The acoustic signal data were analyzed using Fast Fourier Transform (FFT) to define and understand the overall microexplosion process. Also, the effect of temperature, droplet sizes and the percentage of methanol in the vegetable oil blend have been studied to understand what leads to a higher probability of microexplosion occurrence. A correlation between the analyzed acoustic signal data and high speed images were used to differentiate between the different microexplosion events. The results of the study can be useful in predicting the occurrence of microxplosion in liquid fuel boiler which should result in more complete combustion processes, reducing contaminant levels significantly.
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Thapa, S., J. Fang, D. Wood et L. Weiss. « Investigation of Microboiler for Discarded Thermal Scavenging ». Dans ASME 2013 Heat Transfer Summer Conference collocated with the ASME 2013 7th International Conference on Energy Sustainability and the ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/ht2013-17069.
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This paper presents detailed fabrication and operational characterization of a MEMS based microboiler designed to scavenge waste thermal energy from sources like transportation or industry. Microboiler operation is based on capillary action that drives the working fluid from surrounding reservoirs to the surface that is heated by the waste thermal energy. As a result of phase change from liquid to vapor, pressure is created inside the enclosed central steamdome. This pressurized vapor can be made available to another MEMS device (PZT membranes, thermoelectric, etc.) to produce useful power output. In contrast to previous work, the new miniature microboiler design has undergone several modifications that improve operating efficiency. Capillary channels that were designed in linear fashion have been upgraded to a radial layout. This modification facilitated boiler enhancements in capillary flow, operating pressure, and rate of mass transfer. Capillary channels are formed from the silicon substrate with 50 μm widths and 100 μm depths. Power inputs of 2W, 3W and 4W are utilized to characterize performance. Maximum energy absorption via phase change of working fluid was 1.6 mW given a source temperature of 128 °C. The maximum steady state operating pressure achieved during testing was 3.65 kPa.
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Yan, Rong, David Tee Liang, Leslie Tsen, Kaiwen Yao et Joo Hwa Tay. « Case Studies : Problems Solving in Fluidized Bed Waste Fuel Incineration ». Dans 17th International Conference on Fluidized Bed Combustion. ASMEDC, 2003. http://dx.doi.org/10.1115/fbc2003-020.
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Fluidized bed combustion technology has been widely used as the new, flexible, multi-fuel boiler for waste combustion and energy recovery from low-grade fuels. However, problems such as low thermal efficiency, high emissions and bed agglomeration etc., are still encountered in operation of fluidized beds. Valuable experiences were gained from the two case studies recently conducted regarding wastes combustion in industrial-scale fluidized beds. In the first case, the performance of a fluidized bed combustor for energy recovery from oil sludge was evaluated during the commercial trials. Apart from the sludge characterization and bed material analysis, the combustion efficiency, solid flow balance, on-stack emission of CO, SOx, NOx were addressed, as well as the fluidization quality. Although the system was operated with good combustion efficiency (>99.9%), sulfur dioxide emission (>1,000ppm) was found to be substantially higher than the allowable discharge limit. It was recommended to increase limestone feed rate in order to meet the SO2 emission standard and subsequently, installation of a cyclone is suggested to remove the potential significant increase in ash and fine particles. The second case study focused on the bed agglomeration observed in a fluidized bed incinerator where burning blend of three wastes (i.e., carbon soot, biosludge and fuel oil) are involved. To understand the mechanisms and chemistry related, several analytical approaches are employed to identify the bed materials (fresh sand and degrader sand) and clinkers formed from full-scale incinerator tests. The formation of clinker is believed to follow the mechanism of partial melting and/or reactive liquid sintering. The effects of temperature and blending ratio are tested in a muffle furnace. Carbon soot is believed to be more susceptible than the other two fuels. Thermodynamic multi-Phase multi-Component Equilibrium (TPCE) calculations predict that the main low melting point species are predominant under oxidizing condition, suggesting that reducing conditions might be favorable to restrain the bed agglomeration. This study provides valuable information for the better understanding of the chemistry related to clinker formation; it also helps in developing methods for the control and possible elimination of the bed agglomeration problem for the design fuels.
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Chai, Guocai, Johan Hernblom, Keith Hottle, Urban Forsberg et Timo Peltola. « Long Term Performance of Newly Developed Austenitic Heat Resistant Stainless Steel Grade UNS S31035 ». Dans ASME 2014 Symposium on Elevated Temperature Application of Materials for Fossil, Nuclear, and Petrochemical Industries. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/etam2014-1004.
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UNS S31035 austenitic stainless steel grade is a newly developed advanced heat resistant material for use in coal fired boilers at material temperatures up to 700°C. This new grade that has recently obtained two AMSE code cases shows good resistance to steam oxidation and flue gas corrosion and higher creep rupture strength than other austenitic stainless steels available today. This paper will mainly focus on the characterization of long term structure stability and performances such as the creep behaviors at different temperatures for up to 86 000 hours and low cycle fatigue behaviors at high temperatures. The creep and fatigue damage mechanisms were studied using electron transmission microscopy and electron channeling contrast image analysis. The testing results were discussed combining with the safety and structure reliability of the material in 700°C power plants. The material is an excellent alternative for superheaters and reheaters in future high-efficient coal fired boilers. Paper published with permission.
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Girezzi, Gabriele, Damaso Checcacci, Lorenzo Cosi, Andrea Maggi, Alessandro Sani et Andrea Achilli. « Test Bench for Characterization and Design Against Steam Turbine Fouling ». Dans ASME Turbo Expo 2021 : Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/gt2021-59685.
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Abstract The fouling phenomenon addressed in this paper is related to the deposition within steam turbines of steam impurities and to the presence of solid debris, coming from upstream plant sections, that can create solid build-ups in stationary and moving parts inside the turbine. As a consequence, fouling causes unit efficiency decline but, in severe cases, it may also lead to sticking of moving components, such as valves, that may be critical in machine control and/or safety. Despite well-studied and well-considered in design and operation of large power utility plants, where steam quality is of primary importance for boilers, super-heaters, turbines and condensers, this subject is often overlooked in small power generation or industrial applications, where efficiency may be less critical but turbine availability is of paramount importance for plant operation (e.g. LNG plants). The steam fouling is a subject that, despite widely studied in the past, has been quite neglected in more recent years. This paper, with the aim of underlining the importance of fouling in the operation of turbines for industrial applications, starts with examples of field evidences of severe fouling. Then the design of a test bench for the experimental characterization of fouling rates and validation of turbine components, exposed to fouling conditions, is presented along with the description of the deposition models that were developed on the basis of the physical phenomena involved in the fouling process. This study addresses the main deposition physical principles and their implications in the thermodynamic design of the test bench, on the basis of the specific physical properties of the impurities of interest. To better match plant real cases, the contaminants tested included those which have been usually identified within the units during maintenance activities and for which specific limits are prescribed by OEMs. In the following section, details relevant to the main deposition mechanisms due to different geometries and flow-fields are discussed. The results obtained are qualitatively in line with literature and internal practices, yet, through the test activities, it has been possible to establish a quantitative relationship between the concentrations of each contaminant at inlet section and the different thermodynamic conditions along the test bench, so capturing the impact of solubility changes along with the steam expansion.
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Xu, Steven X., Darrell R. Lee, Douglas A. Scarth et Russell C. Cipolla. « Closed-Form Relations for Stress Intensity Factor Influence Coefficients for Axial ID Surface Flaws in Cylinders for Appendix A of ASME Section XI ». Dans ASME 2014 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/pvp2014-28222.
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Analytical evaluation procedures for determining the acceptability of flaws detected during in-service inspection of nuclear power plant components are provided in Section XI of the ASME Boiler and Pressure Vessel Code. Linear elastic fracture mechanics based evaluation procedures in ASME Section XI require calculation of the stress intensity factor. In Article A-3000 of Appendix A of the 2013 Edition of ASME Section XI, the calculation of stress intensity factor for a surface crack is based on characterization of stress field with a cubic equation and use of stress intensity factor influence coefficients. The influence coefficients are only provided for a flat plate geometry. The ASME Section XI Working Group on Flaw Evaluation is in the process of rewriting Article A-3000 of Appendix A. Major updates include the implementation of an alternate method for calculation of the stress intensity factor for a surface flaw that makes explicit use of the Universal Weight Function Method and does not require a polynomial fit to the actual stress distribution, and the inclusion of stress intensity factor influence coefficients for the cylinder geometry. Tabular data of influence coefficients for the cylinder geometry are available in API 579-1/ASME FFS-1 2007. Effort has been made to develop closed-form relations for the stress intensity factor influence coefficients for the cylinder geometry based on API data. With the inclusion of the explicit weight function approach and the closed-form relations for influence coefficients, the procedures of Appendix A for the calculation of stress intensity factors can be used more efficiently. The development of closed-form relations for stress intensity factor influence coefficients for axial ID surface flaws in cylinders is described in this paper.