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Eric Jon Moskala - One of the best experts on this subject based on the ideXlab platform.
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a fracture mechanics approach to environmental stress cracking in poly ethyleneterephthalate
Polymer, 1998Co-Authors: Eric Jon MoskalaAbstract:Environmental stress cracking of amorphous poly(ethylene terephthalate) in aqueous sodium hydroxide was studied by using a fracture mechanics approach. Compact tension specimens were machined from injection-molded plaques and used to determine creep crack growth rate as a function of applied stress intensity factor. The effects of Caustic Concentration and polymer molecular weight on creep crack growth behaviour were determined. Fractographic analysis of the fracture surfaces showed that crack growth proceeded by the formation of novel discontinuous growth bands. The structure and mechanism of formation of these bands are discussed.
Çelikel Bekir - One of the best experts on this subject based on the ideXlab platform.
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Optimization of energy consumption steps in alumina production
Necmettin Erbakan Üniversitesi Fen Bilimleri Enstitüsü, 2017Co-Authors: Çelikel BekirAbstract:Günümüzde enerji her alanda kullanılan bir kaynaktır ve özellikle sanayide üretim maliyetleri içerisinde önemli bir yer tutmaktadır ve enerjiye olan talep her geçen yıl daha da artmaktadır. Dünya genelinde enerji ihtiyacının büyük bir bölümünü karşılamakta olan fosil yakıtların rezervleri hızla azalmaktadır. Bir yandan tükenen fosil yakıtların yerine alternatif enerji kaynakları aranırken diğer yandan da mevcut kaynakların etkin ve verimli biçimde kullanılması önemli hale gelmektedir. Alümina endüstrisinde, her bir proses sadece hammadde tüketmemekte aynı zamanda elektrik, doğal gaz ve buhar gibi çeşitli enerji türleri de tüketilmektedir. Enerji maliyetleri en önemli maliyet girdileri arasındadır ve dünya piyasasında rekabetçi olarak aynı yerde kalabilmek veya daha da ileri gidebilmek için alümina endüstrisi her zaman enerji tüketiminin azaltılması çalışmalarını gözden geçirmek zorundadır. Bayer Prosesinin çözünürleştirme ve buharlaştırma bölümlerinde kullanılan enerji çoğunlukla buhar enerjisidir. Seydişehir de bulunan Eti Alüminyum Fabrikası enerji tüketim maliyetlerinin azaltılması ve fabrikanın enerji verimliliğinin iyileştirilmesi için çalışmalarını sürdürmektedir. Bu çalışmalar; proses dizayn parametrelerinin gözden geçirilmesi, ekipman verimliliği ve atık ısı kazanımları şeklinde gruplandırılabilir. Bu çalışmada, öncelikle alümina fabrikasının enerji tüketimleri incelenmiş ve daha sonra enerji tüketimi verimliliği açısından en çok enerjinin tüketildiği çözünürlük ve buharlaştırma bölümlerinin proses dizayn parametrelerinin optimizasyonu araştırılmıştır. Bu çalışmanın sonucuna göre Seydişehir Eti Alüminyum tesislerinde, çözünürleştirme modülünün düşürülmesi, seyreltme kostik konsantrasyonunun ve buharlaştırılan çözeltinin kostik konsantrasyonun yükseltilmesi ile buhar tüketimi azaltılıp, enerji verimliliğinin artırılabileceği görülmüştür.Today, energy is a resource that is used in all areas and is especially an important place in production costs in the industry. Today, the demand for energy is growing more every year. Reserve of fossil fuels to meet the energy requirements of a large part of the world is decreasing rapidly. On the one hand the effective and efficient use of fossil exhausted the available resources while searching for alternative sources of energy instead of fossil fuels on the other hand are becoming important. In the alumina industry, each process consumes not only raw material but also different types of energy such as electrical, natural gas and steam. Energy costs are a key component of the manufacturing costs and the alumina industry need to review energy consumption reduction in processing in order to maintain or improve their place in the world market. Energy is used in the Bayer Process mostly as steam in the digestion and evaporation operations. The ETI alumina refinery in Seydişehir has been examining ways to reduce energy consumption and improve the overall energy efficiency of the refinery: this has included measures such as evaluating the process design parameters, equipment efficiency and waste heat recovery. In this study, firstly, understanding of the energy usage in the refinery was reviewed and, then the operating efficiency in terms of energy consumption of ETI alumina refinery was evaluated by addressing, in particular, the digestion and evaporation sections which are major energy consuming areas. It is shown that the energy efficiency of the ETI alumina plant can be improved by lowering the digestion molar ratio level, increasing the dilution and strong evaporated liquor Caustic Concentration
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Optimization of energy consumption steps in alumina production
Necmettin Erbakan Üniversitesi Fen Bilimleri Enstitüsü, 2017Co-Authors: Çelikel BekirAbstract:Yüksek Lisans TeziGünümüzde enerji her alanda kullanılan bir kaynaktır ve özellikle sanayide üretim maliyetleri içerisinde önemli bir yer tutmaktadır ve enerjiye olan talep her geçen yıl daha da artmaktadır. Dünya genelinde enerji ihtiyacının büyük bir bölümünü karşılamakta olan fosil yakıtların rezervleri hızla azalmaktadır. Bir yandan tükenen fosil yakıtların yerine alternatif enerji kaynakları aranırken diğer yandan da mevcut kaynakların etkin ve verimli biçimde kullanılması önemli hale gelmektedir. Alümina endüstrisinde, her bir proses sadece hammadde tüketmemekte aynı zamanda elektrik, doğal gaz ve buhar gibi çeşitli enerji türleri de tüketilmektedir. Enerji maliyetleri en önemli maliyet girdileri arasındadır ve dünya piyasasında rekabetçi olarak aynı yerde kalabilmek veya daha da ileri gidebilmek için alümina endüstrisi her zaman enerji tüketiminin azaltılması çalışmalarını gözden geçirmek zorundadır. Bayer Prosesinin çözünürleştirme ve buharlaştırma bölümlerinde kullanılan enerji çoğunlukla buhar enerjisidir. Seydişehir de bulunan Eti Alüminyum Fabrikası enerji tüketim maliyetlerinin azaltılması ve fabrikanın enerji verimliliğinin iyileştirilmesi için çalışmalarını sürdürmektedir. Bu çalışmalar; proses dizayn parametrelerinin gözden geçirilmesi, ekipman verimliliği ve atık ısı kazanımları şeklinde gruplandırılabilir. Bu çalışmada, öncelikle alümina fabrikasının enerji tüketimleri incelenmiş ve daha sonra enerji tüketimi verimliliği açısından en çok enerjinin tüketildiği çözünürlük ve buharlaştırma bölümlerinin proses dizayn parametrelerinin optimizasyonu araştırılmıştır. Bu çalışmanın sonucuna göre Seydişehir Eti Alüminyum tesislerinde, çözünürleştirme modülünün düşürülmesi, seyreltme kostik konsantrasyonunun ve buharlaştırılan çözeltinin kostik konsantrasyonun yükseltilmesi ile buhar tüketimi azaltılıp, enerji verimliliğinin artırılabileceği görülmüştür.Today, energy is a resource that is used in all areas and is especially an important place in production costs in the industry. Today, the demand for energy is growing more every year. Reserve of fossil fuels to meet the energy requirements of a large part of the world is decreasing rapidly. On the one hand the effective and efficient use of fossil exhausted the available resources while searching for alternative sources of energy instead of fossil fuels on the other hand are becoming important. In the alumina industry, each process consumes not only raw material but also different types of energy such as electrical, natural gas and steam. Energy costs are a key component of the manufacturing costs and the alumina industry need to review energy consumption reduction in processing in order to maintain or improve their place in the world market. Energy is used in the Bayer Process mostly as steam in the digestion and evaporation operations. The ETI alumina refinery in Seydişehir has been examining ways to reduce energy consumption and improve the overall energy efficiency of the refinery: this has included measures such as evaluating the process design parameters, equipment efficiency and waste heat recovery. In this study, firstly, understanding of the energy usage in the refinery was reviewed and, then the operating efficiency in terms of energy consumption of ETI alumina refinery was evaluated by addressing, in particular, the digestion and evaporation sections which are major energy consuming areas. It is shown that the energy efficiency of the ETI alumina plant can be improved by lowering the digestion molar ratio level, increasing the dilution and strong evaporated liquor Caustic Concentration
Pal Sarevsh - One of the best experts on this subject based on the ideXlab platform.
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Role of microstructure and environment in stress corrosion cracking susceptibility
2010Co-Authors: Pal SarevshAbstract:In this study, problems in determining threshold stress intensity factor (KISCC) in corrosive environment for thin narrow sections have been identified and a novel technique circumferential notch tensile (CNT) has been successfully used to determine KISCC of thin sections. Although a narrow zone of steel weld was successfully tested by CNT technique, the KISCC data were not very reliable because of poor weld quality. Specimens with simulated microstructure of heat affected zone were used for determination of KISCC of heat affected zone and base metal, using CNT technique. Stress corrosion crack growth in Caustic solution (30% NaOH) at elevated temperatures (100 oC) has been determined using this technique. CNT technique has also been successfully used to study the effect of sensitization on KISCC and crack growth rate of thin sections of solution annealed and sensitized stainless steel in 42% MgCl2 environment. Stress corrosion crack growth was found to be faster in sensitized stainless steel than solution annealed. In this study, effect of Caustic solution chemistry on stress corrosion cracking susceptibility of carbon steel has been studied. Constant load tests with fatigue pre-cracked specimens were conducted in 10, 20, 30 and 40% Caustic Concentration at different temperatures varying from 45-100 oC. Caustic cracking susceptibility diagram has been verified using CNT technique. Stress corrosion crack initiation in blunt notch has also been studied in Bayer solution and plain Caustic solution. Addition of impurities has significant effect on stress corrosion cracking susceptibility. Hence, constant load tests were conducted in real plant Bayer solution. Concentration of Bayer solution was altered to 10, 20, 30 and 40% free Caustic Concentrations by adding NaOH. Tests temperatures were decided in such a way that they lie in definite cracking, potential cracking and no cracking regions of the susceptibility diagram, 30% free Caustic Concentration Bayer solution was highly susceptible for Caustic cracking even at lower temperatures (55 oC). A few tests have been carried out to develop mechanistic understanding of the role of imposed electrochemical potential in Caustic cracking susceptibility
Debabrata Chakraborty - One of the best experts on this subject based on the ideXlab platform.
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the effect of alkalization and fiber loading on the mechanical properties of bamboo fiber composites part 1 polyester resin matrix
Journal of Applied Polymer Science, 2009Co-Authors: Mahuya Das, Debabrata ChakrabortyAbstract:Bamboo strips [10 cm × 1.5 cm × (1−1.5) mm] were treated with Caustic solutions for 1 h at different Concentrations e.g., 0, 10, 15, 20, and 25%. Bamboo strips reinforced polyester resin composites were fabricated by hand-lay-up technique using both alkali-treated and untreated bamboo strips, using a room temperature curing system for the polyester resin. This study aims at the evaluation of the influence of Caustic Concentration on the mechanical properties of bamboo strips reinforced polyester resin composites at a constant 50% loading of reinforcement. Maximum improvement in property was achieved possibly with 20% of Caustic treated strip reinforcements. Beyond 20%, there was degradation in all the strength properties because of failure in mechanical properties of the reinforcements itself. The effect of fiber loading variation upon mechanical properties was also studied. It was observed that superior mechanical properties were obtained with 60% filler loading. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
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effects of alkalization and fiber loading on the mechanical properties and morphology of bamboo fiber composites ii resol matrix
Journal of Applied Polymer Science, 2009Co-Authors: Mahuya Das, Debabrata ChakrabortyAbstract:Resol resin composites reinforced with alkali-treated bamboo strips were fabricated with a hand-lay-up technique. This study was aimed at the evaluation of the influence of the Caustic Concentration on the mechanical properties of bamboo-strip-reinforced resol composites with a constant 50% loading of the reinforcement. The treatment of bamboo fiber in a solution of sodium hydroxide with increasing Concentration percentages resulted in more and more rigid composites; as a result, the strength and modulus values exhibited improvements. The maximum improvement in the properties was possibly achieved with 20% Caustic treated reinforcements. An infrared study indicated the formation of aryl alkyl ether with OH groups of cellulose and methylol groups of resol. Beyond 20%, there was degradation in all the strength properties due to the failure of the mechanical properties of the reinforcement itself. A correlation was found to exist between the mechanical properties and the morphology that developed. Another set of composites with variable loadings of 20% alkali treated fiber (40, 50, and 60%) was fabricated, and a 60% fiber loading showed the best mechanical properties. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Christopher A. Pickles - One of the best experts on this subject based on the ideXlab platform.
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Microwave Caustic leaching of electric arc furnace dust
Minerals Engineering, 2000Co-Authors: Christopher A. PicklesAbstract:Electric arc furnace (EAF) dust is a waste product which is generated when steel scrap is melted in an electric arc furnace. It contains high Concentrations of iron, zinc and lead. Numerous pyrometallurgical and hydrometallurgical processes have been developed to treat this material. Only a limited number of these have reached commercialization and the majority have been pyrometallurgical. However, the hydrometallurgical processes, such as Caustic leaching, offer some potential advantages. In the present research, the application of microwave radiation at 2.45 GHz was employed, as the energy source, in the hydrometallurgical Caustic leaching process for EAF dust treatment. The variables which were investigated were: leaching time, microwave power, Caustic Concentration and the solid to liquid ratio. The experimental results showed that the zinc recovery from the dust increased with a decrease in the solid to liquid ratio and an increase in the microwave power. The optimum Caustic Concentration for the maximum zinc recovery was 8 M. The rates of zinc recovery were significantly higher under microwave conditions as compared to those observed with conventional leaching. Some possible mechanisms to explain this behaviour are discussed.