Academic literature on the topic 'Pre-oxidation. eng'
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Journal articles on the topic "Pre-oxidation. eng"
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Fisher, Ian. "Comment on the Paper “Assessment of ozone and UV pre-oxidation processes for mitigating microbiologically accelerated monochloramine decay” [J. Environ. Chem. Eng. 6 (2018) 41–55]." Journal of Environmental Chemical Engineering 6, no. 2 (2018): 1682. http://dx.doi.org/10.1016/j.jece.2018.02.002.
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Kasnejad, Mohammad Hasan, Ali Esfandiari, Tahereh Kaghazchi, and Neda Asasian. "Corrigendum to “Effect of pre-oxidation for introduction of nitrogen containing functional groups into the structure of activated carbons and its influence on Cu(II) adsorption” [J. Taiwan Inst. Chem. Eng. 43 (5) (2012) 736–740]." Journal of the Taiwan Institute of Chemical Engineers 44, no. 3 (2013): 515. http://dx.doi.org/10.1016/j.jtice.2013.03.002.
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Barre, Douglas Edward, and Kazimiera Amelia Mizier-Barre. "The polypharmacy reduction potential of cinnamic acids and some related compounds in pre- and post-onset management of type 2 diabetes mellitus." Endocrine Regulations 54, no. 2 (2020): 137–55. http://dx.doi.org/10.2478/enr-2020-0017.
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AbstractObjectives. This review assesses the polypharmacy reduction potential of cinnamic acids (CAs) and some related compounds in managing three or more of the cluster of seven, pre- and post-type 2 diabetes mellitus (T2DM)-related features (central obesity, hyperglycemia, hypertension, dyslipidemia, pro-thrombosis, oxidation, and inflammation).Methods. Google scholar and Pubmed were searched for cinnam*, chlorogenic acid, ferulic acid, and caffeic acid in conjunction with each of pre- and post-onset T2DM, central obesity, hyperglycemia, hypertension, dyslipidemia, pro-thrombosis, oxidation, and inflammation. The study was divided into an introduction followed by findings on the impacts of each of the CAs including trans-CA acid, the E isomer of a CA-based thiazolidinedione and a metabolite of that isomer, as well as p-methoxy CA, various cinnamic amides and some other CA-related compounds (chlorogenic acid, cinnamaldehyde, ferulic and caffeic acid).Results. Trans-CA has a potential to manage three, while each of chlorogenic acid, cinnamalde-hyde, caffeic acid and ferulic acid has a potential to manage all seven members of the cluster. Other CA-related compounds identified may manage only one or two of the cluster of seven.Conclusions. Much of the work has been done in animal models of pre- and post-onset T2DM and non-pre- or post-onset T2DM humans and animals, along with some cell culture and in vitro work. Very little work has been done with human pre- and post-onset T2DM. While there is potential for managing 3 or more members of the cluster with many of these compounds, a definitive answer awaits large pre- and post-T2DM onset clinical trials with humans.
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Yan, Sun, Wang, et al. "Enhanced Coagulation with Mn(III) Pre-Oxidation for Treatment of Micro-Polluted Raw Water." Water 11, no. 11 (2019): 2302. http://dx.doi.org/10.3390/w11112302.
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Mn(III) oxidation technology has attracted increasing interest in recent years because of its fast decontamination kinetics and second-pollution-free characteristic. Whether it can be used as a pre-oxidation step to enhance conventional coagulation process remains to be evaluated. Herein, an Fe-coagulation/sedimentation process combined with Mn(III) pre-oxidation (Mn(III)+C/S), hypochlorite pre-oxidation (Cl2+C/S), and permanganate pre-oxidation (PM+C/S) was applied to treat simulated micro-polluted raw water. The removal performance of routine water quality indices (turbidity, dissolved organic carbon, total nitrogen, nitrate-nitrogen, ammonia-nitrogen, Pb(II), and Cr(VI)) and the emerging pollutants (acesulfame, carbamazepine, bisphenol S, and nano-ZnO) created by these three processes were researched. The mechanism of how Mn(III) pre-oxidation influences C/S was explored by identifying the transformation products of Mn(III), measuring the timely variation of flocs’ zeta potential and size, and scanning flocs’ micromorphology. Compared to Cl2+C/S and PM+C/S, Mn(III)+C/S exhibited its superiority in removing dissolved organic carbon (72.9%), total nitrogen (31.74%), and emerging pollutants (21.78%–93.49%). The enhanced removal of these contaminants by Mn(III)+C/S found its explanation in the strong oxidation power of Mn(III) and the multiple roles of in-situ formed MnO2 (e.g., flocculation core, adsorption co-precipitant, and densification agent). The acute toxicity tests confirmed that water treated by Mn(III)+C/S did not show a significant change in the associated toxicity. The findings of the present study indicate that Mn(III) oxidation technology shows great potential as an alternative to pre-oxidation technology of waterworks.
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Rehman, Abdul, Mohammad Hassan Shirani Bidabadi, Liang Yang, et al. "Optimization of pre-oxidation time for corrosion resistance of cobalt based coating alloy in mixed sulphates." Anti-Corrosion Methods and Materials 68, no. 1 (2021): 29–35. http://dx.doi.org/10.1108/acmm-03-2020-2270.
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Purpose This study aims to optimise the effect of pre-oxidation on hot corrosion behaviour of Tribaloy T-900 at 900 °C in mixed Na2SO4 and K2SO4. Design/methodology/approach Prior to hot corrosion experiment, pre-oxidation treatments were carried in ambient air at 900 °C for 1, 5 and 10 h, respectively. The hot corrosion experiments were performed in a box type furnace at 900 °C. Both surfaces of specimens were brushed with saturated salt solution of 75 wt.% Na2SO4 + 25 wt.% K2SO4. After brushing, the salt-coated specimens were placed in electric stove to ensure drying of salt. After drying, presence of 3 mg/cm2 salt on specimen’s surface was ensured through weighting. Findings The 1-h pre-oxidation treatment prior to hot corrosion showed superior hot corrosion resistance against molten salt attack. An optimum pre-oxidation time of 1 h helped timely formation of protective Cr2O3 layer and inhibited the formation of less stable and porous surface oxides of Ni and Mo during hot corrosion. Originality/value Pre-oxidation effect on hot corrosion behaviour of refractory metal (such as Mo in investigated alloy) containing alloy has never been reported previously. Refractory metals oxide (e.g. MoO3) could transform the corrosion phenomena to catastrophic failure through acidic fluxing.
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Wei, L., and L. Yong-Mei. "Use of ferrate pre-oxidation in enhancing the treatment of NOM-rich lake waters." Water Supply 4, no. 4 (2004): 121–28. http://dx.doi.org/10.2166/ws.2004.0069.
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Natural organic materials (NOMs) have a very strong influence on the stability of inorganic particles through interactions (e.g. adsorption, coating, and so on), and thus make the surface water with high NOM content difficult to be coagulated. In this study, standard jar tests and a pilot study were conducted to evaluate the effectiveness of ferrate pre-oxidation in enhancing the coagulation of NOM-rich lake water. A substantial reduction of residual turbidity after sedimentation and filtration was obtained by ferrate pre-oxidation at low dosage (1–5 mg L‒1 as K2FeO4). It was suggested that in order to maintain an acceptable residual turbidity, ferrate pre-oxidation can substantially reduce the dosage of coagulant. The improvement of water quality, as indicated by the reduction of color, DOC, iron, manganese, total bacteria, was observed to be similar in nature to the enhancement of residual turbidity. Formation of additional coagulant (Fe (III)) after decomposition was believed to be an important role of ferrate in enhancing coagulation. Ferrate could be employed in drinking water treatment by simple addition of ferrate solution just before coagulation.
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Hatva, T. "Treatment of Groundwater with Slow Sand Filtration." Water Science and Technology 20, no. 3 (1988): 141–47. http://dx.doi.org/10.2166/wst.1988.0092.
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The purification process and techniques of the slow sand filtration method for treatment of groundwater was studied on the basis of pilot plant and full scale tests and studies of waterworks, to obtain guidelines for construction and maintenance. The purification process consists in general of two principal phases which are pre-treatment and slow sand filtration. Both are biological filters. The main purpose of the pre-treatment is to reduce the iron content of raw water, in order to slow down the clogging of the slow sand filters. Different types of biofilters have proved very effective in the pre-treatment phase, with reduction of total iron from 50 % to over 80 %. During the treatment, the oxidation reduction conditions gradually change becoming suitable for chemical and biological precipitation of iron, manganese and for oxidation of ammonium. Suitable environmental conditions are crucial in the oxidation of manganese and ammonium which, according to these studies, mainly occurs in slow sand filters, at the end of the process. Low water temperature in winter does not seem to prevent the biological activities connected with the removal of iron, manganese and ammonium, the chief properties necessitating treatment of groundwater in Finland.
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Singh, Hariraj, and Brijesh Kumar Mishra. "Degradation of cyanide, aniline and phenol in pre-treated coke oven wastewater by peroxide assisted electro-oxidation process." Water Science and Technology 78, no. 10 (2018): 2214–27. http://dx.doi.org/10.2166/wst.2018.503.
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Abstract The present study explored the feasibility of using graphite electrodes for the electrochemical oxidation of cyanide, thiocyanate, phenol and aniline with hydrogen peroxide. The dosing effects of hydrogen peroxide and current density were examined in the pre-treated coke oven wastewater. It was found that 0.025 M hydrogen peroxide and 13.63 mA/cm2 of current density were more favorable for the removal of 100%, 90%, 71% and 40% cyanide, thiocyanate, phenol and aniline respectively. The increased removal of phenol in the coke oven wastewater was attributed to the pre-treatment of wastewater. Initially, 28% phenol was converted to phenolate ion by air stripping process, which increased the removal rate of phenol by the electro-oxidation process as the removal of phenolate is quite easy compared to phenol. The advanced oxidation process degrades the more toxic cyanide into less toxic intermediate cyanate ions (CNO─), which further cut down into nontoxic end products such as N2, HCO3 and CO2. The experimental results show that the primary mechanisms in the oxidation of cyanide and phenol are mediated electro-oxidation by hydroxyl radicals and hypochlorite ions. The operating cost under the optimized conditions for the removal of 100% cyanide and 71% phenol was estimated to be 616.95 INR/m3.
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Enescu, Maria Cristiana, C. Marius Vlădulescu, Aurel Gaba, Vasile Bratu, Elena Valentina Stoian, and Ivona Camelia Petre. "Cold End Corrosion Avoiding by Using a New Type of Air Combustion Pre-Heater." Materials Science Forum 907 (September 2017): 157–63. http://dx.doi.org/10.4028/www.scientific.net/msf.907.157.
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This paper analyzes the possibility of reducing the cold end corrosion in boilers and furnaces by using a new type of air combustion pre-heater. Cold end corrosion appears due to catalytic oxidation of the sulfur dioxide to sulfur trioxide and then due to the sulfuric acid condensation at dew point. Calculating dew points of various acid gases and options for reducing cold end corrosion of heat recovery exchangers are presented. For avoiding the cold end corrosion we design a new type of air combustion pre-heater for boilers and furnaces. Also, the tube skin temperature of the first row of pipes of the actual air pre-heater was simulated with this computer program, in order to determine whether this temperature is lower than acid dew point of flue gas. With the simulation for this configuration of the actual combustion air pre-heater, the skin temperature for the first row (for the combustion air flow) of tubes from the upper bundle was TS = 134 °C. A way to reduce the cold end corrosion in the combustion air pre-heaters is raising the temperature of the combustion air at the air pre-heater entrance. This solution involves taking a quantity of preheated air, recirculation and then reintroducing it in the air pre-heater. In the same time, this solution avoiding to use the steam radiator, mounted after the fan, for pre-heating the combustion air from 1°C to 45°C. Thus, the furnaces equipped with the new combustion air pre-heater and modern low NOx burners made a fuel economy about 3%.
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Zakar, Mihály, Ildikó Kovács, Péter Muhi, Erika Hanczné Lakatos, Gábor Keszthelyi-Szabó, and Zsuzsanna László. "The Effect of Advanced Oxidation Pre-Treatment on the Membrane Filtration Parameters of Dairy Wastewater." Hungarian Journal of Industry and Chemistry 45, no. 2 (2017): 23–27. http://dx.doi.org/10.1515/hjic-2017-0016.
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Abstract The dairy industry generates wastewater characterised by high levels of biological and chemical oxygen demands representative of their high degree of organic content; mainly carbohydrates, proteins and fats that originate from milk. Several investigations have been conducted into the reuse of dairy wastewater, e.g. membrane processes are a promising method to treat such wastewater. Earlier works have proven that with membrane filtration an appropriate degree of retention can be achieved and the permeate can be reused. However, membrane fouling is a limiting factor in these processes. Advanced oxidation processes (AOPs) are widely used in the fields of water and wastewater treatments and are known for their capability to mineralise a wide range of organic compounds. AOPs also exhibit some other effects on the filtration process, e.g. the microflocculation effect of ozone may play a significant role in increasing the elimination efficiency and causing a decreased level of irreversible fouling. By comparing ozone and Fenton pre-treatment (FPT) processes it can be shown that the fouling propensity of pre-treated pollutants does not depend on the pre-treatment method, while FPT was proven to be more efficient in improving the level of flux.
Dissertations / Theses on the topic "Pre-oxidation. eng"
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Cesco, Décio Dias. "Avaliação em escala real da formação de THMs em águas de abastecimento /." Ilha Solteira : [s.n.], 2007. http://hdl.handle.net/11449/98102.
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Resumo: A cloração das águas na presença de precursores da formação de SPDs, oriundos da MON forma entre estes os THMs, cujos principais compostos são o clorofórmio, bromodiclorometano, dibromoclorometano e bromofórmio, potencialmente cancerígenos ao ser humano. No ano de 1974, os THMs foram detectados na água potável nos Estados Unidos e estudos da época apresentaram as primeiras indicações da existência de correlação entre água de abastecimento, THMs e câncer e, estudos posteriores, levaram à fixação de valores limites dos mesmos. No Brasil o valor máximo para os THMs está fixado em 100 g/L na água para consumo humano, de acordo com a Portaria nº. 518/04 (BRASIL, 2004), mas estes valores limites são variáveis em outros países. O presente estudo buscou identificar a formação de THMs, gerados a partir da reação do cloro com a MON, avaliando a formação com e sem a pré-oxidação com cloro na ETA da SABESP de Presidente Epitácio SP, em escala real, onde as concentrações da MON foram reduzidas pelas etapas do processo de tratamento (coagulação, floculação, decantação e filtração), com a mudança do coagulante de cloreto férrico para PAC e, avaliou-se a formação de THM na rede de distribuição. A quantificação de THM foi realizada pelas técnicas de cromatografia gasosa e da MON através da leitura da absorbância à radiação ultravioleta visível no comprimento de onda a 254 nm em espectrofotômetro UV254, parâmetro indireto com filtração da amostra. As análises da MON mostraram que o sistema de tratamento de água não removeu todos compostos orgânicos naturais, que na presença do cloro residual disponível na rede, mostrou tendência de aumentar a formação de THM durante o seu percurso.<br>Abstract: The chlorination of the water, when the presence of disinfections by-products are formed, resulting from Natural Organic Matter (NOM), forms among them the trihalomethanes (THMs), which is mainly composed by chloroform (CHCl3), bromodichloromethane (CHBrCl2), dibromochloromethane (CHBr2Cl) and bromoform (CHBr3), that are potentially cancerous to humans. In 1974, the THMs were detected in the drinking water in the USA and studies, at the time, showed the first indications of the drinking water correlation, THMs and cancer disease and, further studies brought to fixation of limits for them. In Brazil, the maximum value for the THMs is fixed in 100μg/l in the drinking water, according to government act nº 518/04 (BRASIL, 2004), however those limits varied from country to country. The present research identified the formation of THMs, generated from the reaction of the chlorine with NOM, evaluating the formation with or without the pre-oxidation with chlorine in the SABESP Water Treatment Plant at the Presidente Epitacio city (São Paulo State), in full scale, where the concentrations of the NOM were reduced by the different phases of the treatment process (coagulation, flocculation, decantation and filtration), with the change of the coagulant from iron chloride to Poli Aluminum Chloride (PAC) and, the formation of THM was found at the distribution net. The quantification of THM was made by the gas chromatography technique and NOM are reading in the 254 nm absorbance radiation wave length in an UV spectrophotometer, indirect sample with filtration. The analysis of the NOM showed that the water treatment system did not remove all the natural organic compounds, that in the presence of residual chlorine available in the net, showed increasing tendency to form THM.<br>Orientador: Tsunao Matsumoto<br>Coorientador: Edson Pereira Tangerino<br>Banca: Milton Dall'Aglio Sobrinho<br>Banca: Marcelo Libânio<br>Mestre
Conference papers on the topic "Pre-oxidation. eng"
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Rakowski, James M., Charles P. Stinner, Mark Lipschutz, and J. Preston Montague. "The Use and Performance of Oxidation and Creep-Resistant Stainless Steels in an Exhaust Gas Primary Surface Recuperator Application." In ASME Turbo Expo 2004: Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-53917.
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Recuperation increases the efficiency of a gas turbine engine by extracting heat from the exhaust gas stream and using it to pre-heat the compressor discharge air. Oxidation of the thin metal foil recuperator walls is a major concern, necessitating the use of heat-resistant alloys. Water vapor, present in the exhaust gas as a by-product of combustion, has been shown to be detrimental to the elevated temperature oxidation resistance of some ferrous alloys currently used for recuperators, e.g., Type 347 stainless steel. The walls of the primary surface recuperator are also subjected to a complex state of stress. Creep deformation can cause the compressor discharge air passages to expand, thus restricting exhaust gas flow and increasing the turbine backpressure. The material of construction must, therefore, be resistant to both oxidation and creep deformation. Long-term oxidation, stress-rupture, and creep test results and analysis will be presented for both commercially available and developmental austenitic stainless steel foil materials. A 20Cr-25Ni austenitic stainless steel containing a small addition of Nb was found to exhibit good creep strength when compared to current alloys of construction. This alloy also possesses excellent resistance to attack in environments containing high levels of water vapor. Oxide volatility and breakaway oxidation were not observed after 10,000 hours of exposure at temperatures as high as 760°C (1400°F).
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Nicol, David G., Philip C. Malte, Andrew J. Hamer, Richard J. Roby, and Robert C. Steele. "Development of a Five-Step Global Methane Oxidation–NO Formation Mechanism for Lean-Premixed Gas Turbine Combustion." In ASME 1998 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/98-gt-185.
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It is known that many of the previously published global methane oxidation mechanisms used in conjunction with computational fluid dynamics (CFD) codes do not accurately predict CH4 and CO concentrations under typical lean-premixed combustion turbine operating conditions. In an effort to improve the accuracy of the global oxidation mechanism under these conditions, an optimization method for selectively adjusting the reaction rate parameters of the global mechanisms (e.g., pre-exponential factor, activation temperature and species concentration exponents) using chemical reactor modeling is developed herein. Traditional global mechanisms involve only hydrocarbon oxidation; that is, they do not allow for the prediction of NO directly from the kinetic mechanism. In this work, a two-step global mechanism for NO formation is proposed to be used in combination with a three-step oxidation mechanism. The resulting five-step global mechanism can be used with CFD codes to predict CO, CO2, and NO emission directly. Results of the global mechanism optimization method are shown for a pressure of 1 atmosphere and for pressures of interest for gas turbine engines. CFD results showing predicted CO and NO emissions using the five-step global mechanism developed for elevated pressures are presented and compared to measured data.
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Buzanowski, Mark A., and Sean P. McMenamin. "Integrated Exhaust System for Simple Cycle Power Plants." In ASME 2010 Power Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/power2010-27310.
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Simple cycle power plants are frequently utilized as peaking power plants which generate electricity typically during a high demand. To comply with environmental standards simple cycle power plants are equipped with emission control catalysts reducing emissions of nitrogen oxides, carbon monoxide and other pollutants. In some applications ambient air (so called tempering air) is injected into the exhaust duct to control temperature of the flue gas prior to entering environmental catalysts. Such catalytic treatment of pollutants present in the flue gas requires exhaust systems with substantial footprints to accommodate the emission control catalysts and tempering air injection systems. This paper discusses a new compact exhaust system and efficient arrangement of the tempering air system for simple cycle power plants. The proposed system includes transitioning hot exhaust flue gas into pre-oxidation section of the exhaust system, passing hot exhaust gas through the oxidation catalyst for the CO emissions control, injecting tempering air stream into the post-oxidation section of the exhaust system, and passing cooled flue gas through the reduction catalyst for the NOx emissions control. The resultant benefit of this newly designed process is a more effective use of catalysts, a smaller exhaust footprint of equipment and a lower capital cost to the end user.
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Faravelli, Tiziano, Alessio Frassoldati, Eliseo Ranzi, Francesco Miccio, and Michele Miccio. "Modeling Homogeneous Combustion in Bubbling Beds Burning Liquid Fuels." In 17th International Conference on Fluidized Bed Combustion. ASMEDC, 2003. http://dx.doi.org/10.1115/fbc2003-133.
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This paper presents a first implementation of a model for the description of homogeneous combustion of different fuels in fluidized bed combustors (FBC) at temperatures lower than the classical value for solid fuels, i.e. 850°C. Model construction is based on a key feature of the bubbling fluidized bed: a fuel-rich (endogenous) bubble is generated at the fuel injection point, travels inside the bed at constant pressure and undergoes chemical conversion in presence of mass transfer with the emulsion phase and of coalescence with air (exogenous) bubbles formed at the distributor and, possibly, with other endogenous bubbles. The model couples a fluid-dynamic sub-model based on the two phases theory of fluidization with a sub-model of gas phase oxidation. To this end, model development takes full advantage of a detailed chemical kinetics scheme, which includes both the low and high temperature mechanisms of hydrocarbon oxidation and accounts for about 200 molecular and radical species involved in more than 5000 reactions. Simple hypotheses are made to set-up and close mass balances of the various species as well as enthalpy balances in the bed. First, conversion and oxidation of gaseous fuels (e.g. methane) have been calculated as a test case for the model; then, n-dodecane has been taken into consideration to simply represent a diesel fuel by means of a pure hydrocarbon. Model predictions qualitatively agree with some evidences coming from experimental data reported in the literature. The fate of hydrocarbon species is extremely sensitive to temperature changes and oxygen availability in the rising bubble. A preliminary model validation has been attempted against the results of experiments carried out on a pre-pilot, bubbling combustor fired with underbed injection of a diesel fuel. In particular, model results confirm the trends that the heat release either in the bed or in the freeboard experimentally shows as a function of bed temperature. At lower emulsion phase temperatures many combustible species leave unburned the bed, post-combustion occurs past the bed and freeboard temperature considerably increases; as it is well known, this is an undesirable feature from the viewpoints of practical application and emission control.
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Wielage, B., S. Steinhäuser, G. Reisel, I. Morgenthal, and R. Scholl. "Vacuum Plasma Spraying of Pre-reacted MoSi2 and SiC-Reinforced MoSi2 Produced by a New Kind of Powder Processing." In ITSC 2000, edited by Christopher C. Berndt. ASM International, 2000. http://dx.doi.org/10.31399/asm.cp.itsc2000p0865.
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Abstract Molybdenum silicides have the potential as protective coatings for high-temperature applications because of their high melting point and their high-temperature oxidation resistance. Reinforcing MoSi2 with SiC shows an improvement of its low toughness at room temperature and low creep resistance at temperatures above the brittle-ductile transition temperature of approximately 700-1000 °C. A new kind of powder processing was used to produce MoSi2 and MoSi2-SiC as a feedstock for thermal spraying. Mixtures of the elemental powders, molybdenum and silicon, were prepared by milling and subsequent heat treatment to get highly dispersed, pre-reacted powders. As high-energy milling equipment, a planetary ball mill was used to prepare the powders. In the case of reinforcement, SiC was mixed to the pre-reacted MoSi2 at the end of the milling process, that means before heat treatment. On these as-milled powders, X-ray diffraction characterization (XRD), scanning electron microscopy (SEM), electron probe micro analysis (EPMA) and determination of the oxygen level were carried out. Vacuum plasma spraying has been used to deposit the powders onto a carbon steel substrate. Evaluated coating characteristics were the microstructure (SEM), phases (XRD), EPMA, oxygen content, microhardness and surface roughness. Tests at high temperatures will be considered in future work.
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Zumpano, Petrônio, Genaro Zanon, Alexandre Galiani Garmbis, et al. "Challenges About Testing, Welding and NDT of CRA Pipelines in Brazilian Pre-Salt." In ASME 2012 31st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/omae2012-83461.
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Some new pre-salt fields at Santos Basin in Brazil are located in water depths as deep as 2200m and about 300 km away from the coast. There is variable level of contaminants in the produced fluid, mainly CO2 that affects the material selection of the infield flowlines and risers. Based on these constraints, Petrobras has selected UNS N06625 clad or lined steel linepipes to develop the first fields in Pre-Salt area and also the module 3 of Roncador a post-salt field in Campos Basin. Several challenges have arisen during design, construction and installation of these facilities related to pipeline welding procedures, NDT inspection and Engineering Critical Assessment (ECA). Firstly weld overmatching condition may not be fully achieved due to differences in mechanical properties between UNS 06625 and API X65, and concern increases when reel-lay installation method is chosen. Another welding issue is the maximum interpass temperature of nickel alloys (DNV and PETROBRAS standards limit that to 100°C) and this impacts pipeline installation productivity. Thirdly, back purging characteristics and number of passes protected with purging gases affects the possibility of root oxidation. Also, the inspection of the weld overlay in the pipe end of lined linepipes is other point of great concern. As defect sizing is mandatory for ECA, lined pipes have been designed with a weld overlay length which allows the inspection of the final girth weld by AUT. However, AUT solutions are normally more efficient in rolled or extruded materials than in weld overlaid ones. Additionally, the ECA methodology for both girth welds and weld overlay has complexities that are not usually addressed in a regular ECA for carbon steel pipelines (e.g. internal misalignment of girth welds in risers has stringent requirements because of its effects on fatigue performance and, consequently, the ECA girth weld criteria). Also CRA clad/lined pipelines and risers qualification program may include additional testing when compared with usual carbon steel welding qualification process (namely pitting and intergranular corrosion, full scale fatigue, spooling trials of lined linepipes, segment testing for ECA, and others). Finally, the contribution of clad/lined layer in pipeline design strength is also discussed. This work presents challenges PETROBRAS has faced at design and construction phases of on-going Guaré and Lula-NE pre-salt fields and Roncador field projects, as well as the solutions proposed by the project team in order to overcome the issues raised during project execution.
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Hyland, Patrick, Jungmin Lee, Chien Shung Lin, Jeongmin Ahn, and Paul D. Ronney. "Effect of Ammonia Treatment on Pt Catalyst Used for Low-Temperature Reaction." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-42040.
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Platinum based catalysts are well known as the most active ones among noble metals for oxidation of hydrocarbons as well as hydrogen. Microcombustion experiments using bare Pt foil catalyst have shown that hydrocarbon fuels (e.g. propane) can be oxidized at low-temperature (&lt; 60 °C) and ignited (&lt; 90 °C) by treating the catalyst surface by burning propane-air mixtures with ∼ 5% of the propane replaced by ammonia for half an hour. This NH3 pre-treatment etches the catalyst surface and creates surface structures on the scale of few μms, completely unlike those without NH3 treatment. This change in structure with NH3 treatment is noteworthy in that it increases the performance of the catalyst by a factor of 3, but only for low Re, corresponding to conditions with low maximum reaction temperatures characteristic of microcombustors. However, no similar such low-temperatures were found without NH3 pre-treatment, even for catalytic reactions. This is not merely a surface area effect, since increasing bulk catalyst area had almost no effect on combustion performance. Nevertheless, it may be possible to further extend reaction and ignition to even lower temperatures by examining alternative hydrocarbon fuels and catalysts. Self-starting fuels and catalysts are highly desirable, especially for the micro-combustors used for MEMS (Micro Electro-Mechanical Systems) power generators, because it would eliminate the need for glow plugs, supplemental battery, electronics, etc. associated with active ignition systems.
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Li, Hailin, and Ghazi A. Karim. "Modeling the Performance of a Turbo-Charged S.I. Natural Gas Engine With Cooled EGR." In ASME 2006 Internal Combustion Engine Division Spring Technical Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/ices2006-1377.
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A variety of gaseous fuels and wide range of cooled EGR could be used in turbocharged S.I. gas engines. This makes experimental investigation of knocking behavior both unwieldy and uneconomical. Accordingly, it would be attractive to develop suitable effective predictive model that can be used to improve understanding the role of various design and operating parameters and achieve a more optimized turbo-charged engine operation. A two-zone predictive model developed mainly for naturally aspirated S.I. engine applications of natural gas and validated earlier, was extended to consider applications employing turbochargers, after-coolers and cooled EGR. A suitably detailed kinetic scheme involving 155 reaction steps and 39 species for the oxidation of natural gas is employed to examine the pre-ignition reactions of the unburned natural gas-air mixtures that can lead to knock before being fully consumed by the propagating flame. The model predicts the onset of knock and its intensity once end gas auto-ignition occurs and considers the effects of turbo-charging and cooled EGR on the total energy to be released through auto-ignition and its effect on the intensity of the resulting knock. The consequences of changes in the effectiveness of after- and EGR-coolers when fitted, lean operation and reductions in the compression ratio on engine performance parameters, especially the incidence of knock were examined. The benefits, limitations and possible penalties of the application of fuel lean operation combined with cooled EGR are also examined and discussed.
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Ginger, Bradley. "Advanced Pollution Control for Gasification of Varied Opportunity Fuels." In 19th Annual North American Waste-to-Energy Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/nawtec19-5432.
Full textAbstract:
Advances in gasification technology have opened up a number of commercial opportunities to generate energy from a wide range of non-traditional feed stocks. Gasification technology platforms from a number of providers are in development with the goal of creating modular solutions for supplying the energy needs of local communities, often in solutions as small as 10 to 20 MW increments. Such technologies offer potential project developers the ability to explore local opportunities for fuel supply from a number of sources. These opportunity fuels cover a wide range of potential energy sources as far reaching as recovered plastic, recovered tires, poultry litter, and a wide variety of woody biomass. The syn-gas produced from the gasification of such varied opportunity fuels contains a number of undesired trace components. These components will need to either be removed via gas conditioning, or alternatively be combusted with the syn-gas in an oxidation step which will produce a flue gas requiring air pollution control. Gas conditioning requirements vary depending on the desired end use of the syn-gas whether as a utility quality fuel or as an intermediate to a further chemical pathway. Flue gas target levels are defined by current environmental legislation. The potential pollutants produced in the flue gas pathway include Particulate Matter, Hydrogen Chloride, Sulfur Dioxide, Sulfuric Acid Mist, and Oxides of Nitrogen. To ensure operational compliance of the system stack emissions both now and in the future, proper pollution control technology is paramount. This presentation will address an emerging air pollution control technology that embodies all of these removal steps in a single device specifically designed to meet current and expected future environmental needs. EISENMANN’s recently patented multi-pollutant control system, the Wet Electrostatic Precipitator Dual Field or WESP-2F, includes the use of a pre-scrubbing chamber for large PM, SO2, and water soluble NO2 removal. Following the quench and pre-scrubbing region, a specially tuned downflow wet ESP field is responsible for finer PM and Sulfuric Acid aerosol removal, as well as an important Ozone producing stage that oxidizes non-water soluble forms of NOx. As the gas continues to travel through the system, a secondary scrubbing chamber is used to further reduce NOx by scrubbing the newly formed NO2 that has been formed from the oxidation of other forms of NOx through the use of Ozone produced by the electrostatic precipitator. The final polishing stage of the system includes an upflow wet electrostatic precipitator field for the removal of newly oxidized material as well as any heavy metals present. Research and testing on the aforementioned system took place using a pilot sized unit operating a slipstream off a 20 MW commercial sized gasifier testing a number of opportunity fuels. Expected performance was validated proving high removal efficiencies for pollutants specifically addressed earlier. Results from a wide variety of opportunity fuels will be discussed. Current implementation of the technology in gasification projects following the flue gas pathway is underway and is currently viewed as an acceptable solution to the environmental regulations associated with the plant requirements.
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Del Giacco, Mattia, Alfons Weisenburger, and Georg Müller. "Fretting of Fuel Cladding Materials for Pb Cooled Fast Reactors: Long Term Prediction Using Fretting Maps." In 2013 21st International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icone21-16905.
Full textAbstract:
Fretting is a particular type of wear that is expected to occur in molten lead alloy cooled nuclear reactors due to flow induce vibrations and will mainly affect fuel claddings and heat exchanger tubes. A new facility (FRETHME) designed to investigate this specific type of wear was applied the first time for fretting test in liquid lead alloys at reactor relevant conditions. Numerous fretting tests at severe conditions (accelerated tests) were performed on candidate steels such as the f/m T91 steel, the austenitic 15-15 Ti steel and Al surface alloyed T91 (GESA-T91). The fretting damage increases with the increasing number of cycles/time and temperature. Fretting interacts with the corrosion mechanisms occurring in liquid Pb alloys (fretting corrosion) and destabilizes the corrosion barriers, favouring e.g. dissolution attacks. Due to the favourable wear and corrosion resistance properties of the surface alloyed layer, GESA-T91 steel showed the best fretting corrosion behaviour up to 550 °C. On the contrary, due to the high Ni content, the 15-15Ti steel is affected by dissolution enhanced fretting; while oxidation enhanced fretting characterizes T91 steel at temperatures higher than 500 °C. In most of the tests under accelerating conditions, 10% of fuel clad thickness was penetrated after quite short times already. To extrapolate the obtained results to conditions (load and amplitude) that allow long term use of the respective component in Pb cooled reactors, the concept of fretting maps was applied. Fretting maps were constructed using the obtained experimental data especially the fretting wear coefficient, which is a characteristic of a specific fretting regime. The obtained fretting maps were used to determine the tolerable amplitude and load up to which the tested materials can be used in a Pb cooled nuclear reactor. In addition, dedicated tests suggested that, besides the use of aluminized steels, possible countermeasures to mitigate the fretting impact are the use of pre-oxidized components and Ni-enriched liquid Pb.