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1
Adinberg, Roman, Michael Epstein und Jacob Karni. „Solar Gasification of Biomass: A Molten Salt Pyrolysis Study“. Journal of Solar Energy Engineering 126, Nr. 3 (19.07.2004): 850–57. http://dx.doi.org/10.1115/1.1753577.
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A novel solar process and reactor for thermochemical conversion of biomass to synthesis gas is described. The concept is based on dispersion of biomass particles in a molten inorganic salt medium and, simultaneously, absorbing, storing and transferring solar energy needed to perform pyrolysis reactions in the high-temperature liquid phase. A lab-scale reactor filled with carbonates of potassium and sodium was set up to study the kinetics of fast pyrolysis and the characteristics of transient heat transfer for cellulose particles (few millimeters size) introduced into the molten salt medium. The operating conditions were reaction temperatures of 1073–1188 K and a particle peak-heating rate of 100 K/sec. The assessments performed for a commercial-scale solar reactor demonstrate that pyrolysis of biomass particles dispersed in a molten salt phase could be a feasible option for the continuous, round-the-clock production of syngas, using solar energy only.
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Xu, Yanke, Hongyan Yan, Zhenwei Jing, Xiwei Qi, Hui Li und Jinglong Liang. „Effect of Fe2O3 on Electro-Deoxidation in Fe2O3-Al2O3-NaCl-KCl System“. Crystals 11, Nr. 9 (26.08.2021): 1026. http://dx.doi.org/10.3390/cryst11091026.
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The reduction of Fe2O3-Al2O3 is one of the important reactions in the resource utilization of iron-containing oxide waste. Fe2O3-Al2O3 was electro-deoxidized in the NaCl-KCl system by molten salt electrolysis to prepare FeO/Al2O3. The effect of the Fe2O3 content on the electro-deoxidation reaction process was studied. The results show that under the conditions of 850 °C, 2.3 V, and electro-deoxidation for 4 h, FeO/Al2O3 could be obtained by controlling the content of Fe2O3. The deoxidation process was divided into three stages: electric double layer charging, Fe2O3 electro-deoxidation to Fe3O4, and Fe3O4 electro-deoxidation to FeO. With the increase in the Fe2O3 content, the deoxidation reaction rate increased, and the low-valence iron oxide particles obtained by electro-deoxidation became larger. The mechanism of the influence of Fe2O3 on the electro-deoxygenation process was determined by analyzing the experimental results. The increase in the Fe2O3 content increased the concentration of activated molecules in the system, while it reduced the resistance of electro-deoxidation. The migration of active particles in the cathode was smoother, which increased the percentage of deoxygenation of activated molecules, thereby shortening the process of the deoxidation reaction.
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Negri, O., und T. Abram. „INFLUENCE OF FUEL FLOW RATE VARIATION ON MOLTEN SALT REACTOR PERFORMANCE“. EPJ Web of Conferences 247 (2021): 01008. http://dx.doi.org/10.1051/epjconf/202124701008.
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Molten Salt Reactors are Gen-IV reactors that use liquid fuel. Fluid fuel allows continuous removal of fission gases as well as batch fuel reprocessing. With these control mechanisms the system can be sustained within the desired operating temperature range and required power output. These methods rely on the presence of a chemical processing plant on-site that adds complexity. This also creates a risk of processing plant unavailability due to faults, emergency downtime or maintenance. The work considers variation of fuel salt flow rate in Molten Salt Reactors as a means of controlling reactor operation without using reprocessing. The analysis is performed using the Molten Salt Fast Reactor as an example. An extended version of the SERPENT Monte-Carlo transport code coupled with OpenFOAM generic platform were used for capturing delayed neutron drift, decay heat, gaseous fission product removal, calculating fuel salt velocity vectors and the fuel temperature distribution. The two models were coupled via a script that accounted for reactivity insertion between time steps and the changes caused in the fission power. Results confirm that, while operating at constant power, the difference between fuel inlet and outlet temperatures increase as the flow rate decreases. Burnup analysis has shown that while the average fuel temperature continues to reduce with time, the difference between inlet and outlet temperatures can be controlled by varying the flow rate while maintaining constant power. Finally, the variation in the fuel flow rate has been shown to extend the reactor operating time with no insertion of additional fissile inventory.
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Chen, Si’an, Hai Feng Hu, Yu Di Zhang, Chang Rui Zhang und Guang De Li. „Low Temperature Preparation of ZrC Coatings on C/C Composite via Molten Salt Reaction“. Key Engineering Materials 531-532 (Dezember 2012): 79–83. http://dx.doi.org/10.4028/www.scientific.net/kem.531-532.79.
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Zirconium carbide (ZrC) coatings were prepared on C/C composite via molten salt reaction process at relatively low temperatures of 800-1000°C. During the reaction process, potassium fluorozirconate (K2ZrF6) played a role transporting zirconium from the molten salt to the C/C composite surface. Elevating reaction temperature increased the growth rate of coatings, simultaneously leaded to rougher coatings. The coatings growth rate increased with reaction time at first and then decreased gradually. The ZrC coatings prepared at 900°C for 5h was ~2m thickness. At the early stage, the low solubility of zirconium in the molten salt leaded to the low coatings growth rate. Secondly, the growth rate of the ZrC coatings was controlled by the chemical reaction between C/C composites and zirconium once zirconium was saturated in the molten salts. Thirdly, the control step of coatings formation turned into the diffusion of carbon through the formed ZrC coatings and which leaded to a gradual decrease of growth rate.
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Yasuda, K., K. Kondo, S. Kobayashi, T. Nohira und R. Hagiwara. „Selective Formation of Rare Earth-Nickel Alloys via Electrochemical Reactions in NaCl-KCl Molten Salt“. ECS Transactions 64, Nr. 4 (15.08.2014): 601–7. http://dx.doi.org/10.1149/06404.0601ecst.
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Yasuda, Kouji, Katsuya Kondo, Seitaro Kobayashi, Toshiyuki Nohira und Rika Hagiwara. „Selective Formation of Rare-Earth–Nickel Alloys via Electrochemical Reactions in NaCl–KCl Molten Salt“. Journal of The Electrochemical Society 163, Nr. 5 (2016): D140—D145. http://dx.doi.org/10.1149/2.0501605jes.
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7
van Erk, W. „Transport processes in metal halide gas discharge lamps“. Pure and Applied Chemistry 72, Nr. 11 (01.01.2000): 2159–66. http://dx.doi.org/10.1351/pac200072112159.
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An overview is given of transport reactions and corrosion phenomena in metal halide gas discharge lamps filled with a mixture of alkali halides with scandium or rare-earth iodides. The phenomena that are discussed are: (a) pressures of light-emitting species above the molten salt mixture, (b) interaction of the metal halides with the vessel wall, quartz glass as well as polycrystalline alumina, (c) transport processes along the vessel wall giving rise to wall corrosion, and (d) transport to and from the electrodes (i.e., electrode corrosion and wall blackening).
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Han, Yan Fang, Ti Chang Sun, Jie Li, Li Na Wang, Tian Yan Xue und Tao Qi. „Removing of Si in the NaOH Molten Salt Reaction of Titanium Slag to Produce TiO2“. Advanced Materials Research 418-420 (Dezember 2011): 387–92. http://dx.doi.org/10.4028/www.scientific.net/amr.418-420.387.
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NaOH solution was utilized in the molten salt reaction of titanium slag for investigating desiliconization effects. The thermodynamic behaviors of Si in the reaction system was examined to explore the impacts of molten salt reaction conditions on the conversion rates of the foreign substance Si and the target element Ti. On this basis, the influences of NaOH concentration, liquid-solid ratio, cleaning temperature and cleaning time on Si removing rate were discussed. The experimental results showed that, Si reacted with NaOH to produce sodium silicate was feasible in terms of thermodynamics within the temperature interval 400-1000K. 3Na2O•2SiO2, 2Na2O•SiO2 could stably exist under high reaction temperature. As the reaction time extended and temperature rose, the conversion rate of Si was increasing. In the process of Si removing by NaOH cleaning of molten salt reaction products, as NaOH concentration, liquid-solid ratio, cleaning temperature and cleaning time increased, Si removing rate became larger. The optimum alkali cleaning conditions were: NaOH concentration 150g/l, liquid-solid ratio 3:1, cleaning temperature 50°C and cleaning time 60min, then the desiliconization rate reached 61.16%.
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Ouyang, Zhen, Longgang Ye, Chaobo Tang und Yuntao Xin. „Reaction Behaviors of Associated Minerals in Molten Salt Smelting of Stibnite and Kilogram-Class Trials“. Metals 10, Nr. 1 (25.12.2019): 43. http://dx.doi.org/10.3390/met10010043.
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The molten salt metallurgy of Sb, which involves the smelting of stibnite in a binary NaCl-Na2CO3 salt with sulfur-fixing and the addition of a reductant, has been proposed as a clean method for Sb extraction. However, the reacting behaviors of the minerals associated with stibnite (Sb2S3) during the smelting are still unclear, and industrial tests have not been conducted. This study investigated the behaviors of PbS, FeS2, SiO2, and CaCO3, which are the main minerals associated with stibnite, during reducing smelting by using the NaCl-Na2CO3 molten salt. The results showed that PbS could react with Na2CO3 to generate metallic Pb at 950 °C. FeS2 and SiO2 formed stable NaFeS2 and Na2SiO3 with the molten salt at a high temperature, respectively. CaCO3 formed an unstable intermediate product of Na2Ca(CO3)2 at 675 °C and decomposed with increasing temperature. Kilogram-class trials were also performed using 50 kg of concentrate and more than 300 kg of mixture material, and the results showed that the direct recovery rate of Sb and Au reached maximum values of 93.22% and 92.06% at temperature 920 °C in eutectic Na2CO3-NaCl molten salt, respectively, while the total sulfur-fixing ratio reached 99.49%. Thus, the associated minerals consumed the molten salt, and the feasibility of molten salt smelting was verified by this kilogram-class pilot experiment.
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Lu, Ningning, und Donglai Xie. „Novel Membrane Reactor Concepts for Hydrogen Production from Hydrocarbons: A Review“. International Journal of Chemical Reactor Engineering 14, Nr. 1 (01.02.2016): 1–31. http://dx.doi.org/10.1515/ijcre-2015-0050.
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AbstractMembrane reactors are attracting increasing attention for ultrapure hydrogen production from fossil fuel, integrating catalytic reaction and separation processes into one single unit thus can realize the removal of hydrogen or introduction of reactant in situ, which removes the thermodynamic bottleneck and improves hydrogen yield and selectivity. In this review, the state-of-the-art concepts for hydrogen production through membrane reactors are introduced, mainly including fixed bed membrane reactors, fluidized bed membrane reactors, and micro-channel membrane reactors, referring higher hydrocarbons as feedstock, such as ethanol, propane, or heptane; novel heating methods, like solar energy realized through molten salt; new modular designs, including panel and tubular configurations; ultra-compact micro-channel designs; carbon dioxide capture with chemical looping; multifuel processors for liquid and/or solid hydrocarbons; etc. Recent developments and commercialization hurdles for each type of membrane reactor are summarized. Modeling the reactor is fundamental to explore complex hydrodynamics in reactor systems, meaningful to investigate the effects of some important operating factors on reactor performances. Researches for reactor modeling are also discussed. Reaction kinetics for hydrocarbons reforming and reactor hydrodynamics are summarized respectively. Cold model is introduced to investigate physical phenomena in reactors.
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Losa, Evžen, Michal Košťál, Tomáš Czakoj, Jan Šimon, Nicola Burianová, Vlastimil Juříček und Vojtěch Rypar. „NEUTRON FIELD MOCK-UP DEVELOPMENT FOR THE FLUORIDE SALT REACTORS NEUTRONIC RESEARCH“. EPJ Web of Conferences 247 (2021): 08013. http://dx.doi.org/10.1051/epjconf/202124708013.
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Experimental work at the LR-0 reactor was carried out to determine the possibility of the mock-up neutron field creation for the fluoride salt-based reactors. Previous calculations and experiments have shown that the fast part of the molten salt reactor (MSR) spectrum is shaped by fluorine and even the Teflon material is suitable for neutronics in that energy range. Properly selected spectrum indices can describe the neutron field of the MSR in fast thermal and intermediate parts of the spectrum. Current research has focused on a deeper study of the possibility of using the filtered thermal and intermediate neutron spectrum of the experimental light water reactor for the physics of fluoride salt-based reactor. LiF-BeF2 (FLIBE) capsule and teflon cylinders are used as a spectrum filters in the LR-0 reactor. Measured results show acceptable C/E-1 agreement in the reaction rates and satisfactory agreement for usage of the FLIBE filtered neutron spectrum determined by the 181Ta(n, γ) monitor as a mock-up in thermal to intermediate energy in the fluoride high-temperature reactor (FHR). Concerning MSR, intermediate spectrum can be reproduced to some extent but not as good as in the case of FHR.
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Li, Yun Gang, Kuai Zhang, Jie Li und Li Min Liu. „Electrochemical Behavior of Copper in the (NaCl-KCl-CuCl2) Molten Salt“. Applied Mechanics and Materials 217-219 (November 2012): 8–14. http://dx.doi.org/10.4028/www.scientific.net/amm.217-219.8.
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2system at 700°C. The results showed that so long as Cu appears or the electrodeposit process carries on, Cu++ can be reduced into Cu+; that the electrochemical reaction process of copper is a quasi-reversible process mix-controlled by ion copper diffusion rate and electron transport rate; that the electrochemical reaction mechanism is Cu++e-→Cu; that the electrocrystallization process of copper is an instantaneous hemispheroid three-dimensional nucleation process; that the Cu ion diffusion coefficient is 2.5×10-4cm2∙s-1at experimental conditions.
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Misso, Agatha Matos, Hermi F. Brito, Lucas C. V. Rodrigues, Vinicius R. Morais und Chieko Yamagata. „Synthesis and Characterization of CaMgSi2O6 Activated by Eu2+“. Materials Science Forum 881 (November 2016): 30–34. http://dx.doi.org/10.4028/www.scientific.net/msf.881.30.
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Rare earth silicate based MnMgSi2O5+n (M = Ca, Sr or Ba and n=1-2) phosphors, have attracted interest of researchers due to their high efficiency as a host, excellent thermal and chemical stability and high brightness adding to their low cost. These phosphors showed great potential in various applications such as fluorescent lamps, white light emitting diodes, and display components. High temperature solid-state reactions are usually employed to synthesize those compounds. This paper proposes an alternative method of obtaining nanophosphor host based on Eu-doped CaMgSi2O6 (CMS:Eu), persistent luminescence phosphor. Sol gel technique combined to a modified molten salt method was used. The resulted powder was calcined for 3h under an atmosphere of 5% H2 and 95% Ar2. Phase identification by XRD and the measurements of photoluminescence (PL) and photoluminescence excitation (PLE) were performed. Single phased CMS:Eu with persistent luminescence characteristics was prepared.
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Lu, Jun Que, Xiu Feng Wang und Hong Tao Jiang. „Synthesis of Pure Bi12SiO20 Powder by Molten Salt Method“. Applied Mechanics and Materials 182-183 (Juni 2012): 52–56. http://dx.doi.org/10.4028/www.scientific.net/amm.182-183.52.
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Pure Bi12SiO20powder was successfully prepared by a molten salt method using Bi2O3and SiO2as raw materials and using KCl-K2CO3as flux at 635°C with the heating rate of 5°Cmin-1. The phase composition and microstructure of these products were analyzed by X-ray diffraction and scanning electron microscopy, and the effects of the processing parameters, such as the ratio of Bi2O3/SiO2, calciniation temperature, isothermal time and relative amount of salt, on the composition and particle size were investigated. The results indicated that regardless of changing the ratio of Bi2O3/SiO2, calciniation temperature, isothermal time or relative amount of salt the reaction only yielded Bi12SiO20without Bi2SiO5and Bi4Si3O12. Henceforth, KCl-K2CO3molten salts may be considered as an ideal reaction medium to synthesize pure phase of Bi12SiO20. The particle size of Bi12SiO20phase can be determined by changing the temperature, isothermal time and relative amount of salt.
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Prakash, B. Shri, und K. B. R. Varma. „Molten Salt Synthesis of Nanocrystalline Phase of High Dielectric Constant Material CaCu3Ti4O12“. Journal of Nanoscience and Nanotechnology 8, Nr. 11 (01.11.2008): 5762–69. http://dx.doi.org/10.1166/jnn.2008.213.
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Nanocrystalline powders of giant dielectric constant material, CaCu3Ti4O12 (CCTO), have been prepared successfully by the molten salt synthesis (MSS) using KCl at 750 °C/10 h, which is significantly lower than the calcination temperature (∼1000 °C) that is employed to obtain phase pure CCTO in the conventional solid-state reaction route. The water washed molten salt synthesized powder, characterized by X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), and Transmission electron microscopy (TEM) confirmed to be a phase pure CCTO associated with ∼150 nm sized crystallites of nearly spherical shape. The decrease in the formation temperature/duration of CCTO in MSS method was attributed to an increase in the diffusion rate or a decrease in the diffusion length of reacting ions in the molten salt medium. As a consequence of liquid phase sintering, pellets of as-synthesized KCl containing CCTO powder exhibited higher sinterability and grain size than that of KCl free CCTO samples prepared by both MSS method and conventional solid-state reaction route. The grain size and the dielectric constant of KCl containing CCTO ceramics increased with increasing sintering temperature (900 °C–1050 °C). Indeed the dielectric constants of these ceramics were higher than that of KCl free CCTO samples prepared by both MSS method and those obtained via the solid-state reaction route and sintered at the same temperature. Internal barrier layer capacitance (IBLC) model was invoked to correlate the observed dielectric constant with the grain size in these samples.
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Li, Lan Jie, Shi Li Zheng, Dong Hui Chen, Shao Na Wang, Hao Du, Ming Lei Gao und Yi Zhang. „A Novel Method of Leaching Vanadium from Extracted Vanadium Residue Using Sodium Sub-Molten Salt Medium“. Advanced Materials Research 402 (November 2011): 253–60. http://dx.doi.org/10.4028/www.scientific.net/amr.402.253.
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Leaching of an extracted vanadium residue in sodium sub-molten salt medium was investigated. The significant effects of reaction temperature, particle size of residue, reaction time and NaOH-to-residue mass ratio on vanadium extraction were studied. By the orthogonal experiment study, it can be concluded that the impact order of factors is Tr> t>R according to the significance to the leaching process. Under conditions of reaction temperature 170°C, NaOH-to-residue 4:1, stirring speed 700 rpm, particle size -74 µm and reaction time around 180 min, leaching efficiency of vanadium obtained is higher than 90%. And, the leaching process of vanadium, with activation energy 27.69 kJ•mol-1, is controlled by the chemical reaction-controlled as the following rate equation. ln(1-x)=-kt
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Tawalbeh, Muhammad. „Kinetics Study of the Digestion of Magnesium Chloride Dihydrate in a Molten Salt Electrolyte“. Key Engineering Materials 865 (September 2020): 105–10. http://dx.doi.org/10.4028/www.scientific.net/kem.865.105.
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During the electrolytic reduction of magnesium, it is very important to understand the mechanism of the digestion of the magnesium chloride dihydrate granules in the molten electrolyte throughout the chlorination process. This work aimed to investigate the kinetics of this digestion process. The results showed that the granules digestion is happening in two stages. The first stage is very fast, hence, results in the formation of MgOHCl during the dehydration and the hydrolysis of magnesium chloride dihydrate in the interior of the granules. The kinetic results for the first stage was best modeled using shrinking core model where the surface reaction was the rate controlling step. The second stage was best modeled as a first-order homogenous reaction. The kinetic parameters for the two stages were determined along with the Arrhenius plots. The results of this kinetics study are essential for the mathematical modeling of the chlorination process of the magnesium chloride dihydrate granules.
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Zhang, Shu Yu, Bao Rang Li und Run Hao Liu. „The Influence of Oxide-Salt Ratio on Crystallization of Lu2Ti2O7 Phase from Molten Salt“. Applied Mechanics and Materials 275-277 (Januar 2013): 2321–24. http://dx.doi.org/10.4028/www.scientific.net/amm.275-277.2321.
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Lu2Ti2O7 powders have been prepared using TiO2 and Lu2O3 oxides as precursors based on molten salt technique and the effects of salt-oxide ratio on the phase transformation is studied. A significant influence of salt-oxide ratio on phase transformation has been observed and the salt-oxide molar ratio of 3:1 is preferred for improved synthesis reaction efficiency. Such an experimental trend is analyzed with the assistant of JMA equation and the possible correlations between salt amount and the nucleation rate is given. After confirming linearly increasing of the crystal size with time, which is an indicative of interface controlled crystal growth kinetics, the investigations on the curves resulting from the logarithm of phase transformation fraction (ln[-ln(1-α)]) plots versus both the annealing time (lnt) and calcinations temperatures ( ) under isothermal and non-isothermal conditions respectively suggest that the enhanced crystallization is derived from the modification of salt amount to the nucleation rate.
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Widiharto, Andang. „Study on the Ability of PCMSR to Produce Valuable Isotopes as a By Product of Energy Generation“. Indonesian Journal of Physics and Nuclear Applications 3, Nr. 1 (09.05.2018): 7–14. http://dx.doi.org/10.24246/ijpna.v3i1.7-14.
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PCMSR (Passive Compact Molten Salt Reactor) is a variant of MSR (Molten Salt Reactor) type reactors. The MSR is one type of the Advanced Nuclear Reactor types. PCMSR uses mixtures of fluoride salt if the liquid form is in a high temperature operation. The use of liquid salt fuel allows the application of on line fuel processing system. The on line fuel processing system allows extraction of several valuable fission product isotopes such as Mo-99, Cs-137, Sr-89 etc. The capability of MSR to produce several valuable isotopes has been studied. This study is based on a denaturized breeder MSR design with 920 MWth of thermal power and 500 MWe of electrical output power with the thermal efficiency of 55 %. The initial composition of fuel salt is 70 % of a mole of LiF, 24 % of a mole of 232ThF4, 6 % of a mole of UF4. The enrichment level of U is 20 % of a mole of U-235. The study is performed by a numerical calculation to solve a set of differential equations of fission product balance. This calculation calculates fission product generation due to fission reaction, precursor decay, and fission product annihilation due to decay, neutron absorption, and extraction. The calculation result shows that in quasi equilibrium conditions, the reactor can produce several valuable isotopes in substantially sufficient quantities, those are Sr-89 (0.3 kCi/MWth/day, Sr-90 (1,91 Ci/MWth/day), Mo-99 (1.7 kCi/MWth/day), I-131 (0.42 kCi/MWth/day), I-132 (0.782 kCi/MWth/day), I-133 (1.12 kCi/MWth/day), Xe-133 (11.8 Ci/MWth/day), Cs-134 (39.3 mCi/MWth/day), Cs-137 (2.32 Ci/MWth/day) and La-140 (1.05 kCi/MWth/day).
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Liu, Xuyang, Meilong Hu, Chenguang Bai und Xuewei Lv. „Direct Electro-deoxidation of Ilmenite Concentrate to Prepare FeTi Alloy in CaCl2 Molten Salt“. High Temperature Materials and Processes 33, Nr. 4 (01.08.2014): 377–83. http://dx.doi.org/10.1515/htmp-2013-0084.
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AbstractIn order to prepare FeTi alloy using ilmenite concentrate in molten salt by electrolytic method, the electrochemical deoxidation process was studied by cyclic voltammetry and AC impedance spectroscopy. The electrolytic experiments at different time verified the electrochemical behavior. It is shown that the electrodeoxidation process for ilmenite concentrate mainly consists of two steps. Fe is reduced firstly from the ilmenite concentrate. The second step is the reduction of titanium dioxide with an intermediate product perovskite. At low voltage, the speed of electro-deoxidation process is mainly dependent on the electrochemical reaction. As the potential increases, the diffusion of ion becomes the main rate-controlling step for the electro-deoxidation of ilmenite concentrate.
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Xu, Haitao, Shuzhong Wang, Mengmeng Ren, Jianqiao Yang, Chengchao Cui, Yanhui Li und Jie Zhang. „Review of Supercritical Hydrothermal Combustion“. E3S Web of Conferences 83 (2019): 01002. http://dx.doi.org/10.1051/e3sconf/20198301002.
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Two major points in supercritical hydrothermal combustion were reviewed:(1) The structure of semi-batch reactors or continuous reactors used in different institutes and colleges. These investigations can be used to guide the design of reactors for later scholars and lay the foundation for the industrialization of supercritical hydrothermal combustion. (2) The research status of characterization of hydrothermal flame processes by various scholars. These investigations can be used to guide the process parameters of industrialization of supercritical hydrothermal combustion. The continuous reactor designed in each organization is very sophisticated, which can avoid the two major problems of reaction in the supercritical state: salt precipitation and corrosion. The ignition temperature, extinction temperature, and other characteristics of supercritical hydrothermal combustion studied by scholars are summarized and the laws are basically similar. The removal rate of different organic matters was also summarized under supercritical hydrothermal combustion, and the removal rate of more than 99% was basically achieved.
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Fei, T., T. Hua, B. Feng, F. Heidet und R. Hu. „MSRE TRANSIENT BENCHMARKS USING SAM“. EPJ Web of Conferences 247 (2021): 07008. http://dx.doi.org/10.1051/epjconf/202124707008.
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In recent years, there has been renewed interest in Molten Salter Reactors (MSRs) for their potential advantages compared to reactors that rely on solid fuel. In response to such interest, the System Analysis Module (SAM) was enhanced to include MSR-specific modeling features including a delayed neutron precursor drift model and a modified point kinetics model. This paper discusses the validation of these features using the experiments conducted in the Molten Salt Reactor Experiment (MSRE). These experiments include the pump start-up and coast-down tests at zero power and a thermal convection test. For the zero power tests, the change in pump speeds induces flow rate changes in the core that impact the precursor concentrations. This introduces a neutron imbalance and requires the adjustment of the control rods to counter-balance this effect. SAM was used to evaluate the precursor concentration in the core as a function of time, and the resulting changes in reactivity were evaluated through the modified point kinetics equation. The results show good agreement with the experimental data. It should be noted that the pump performance curve used in this analysis was re-constructed based on the initial water test data of the fuel pump. The steady-state pump curve is assumed to be applicable to transient flow operations. The thermal convection test was conducted by shutting off the pumps, reducing the inlet core temperature for 360 minutes, and allowing the power to be adjusted by the inherent feedbacks of the system. The power level during this transient was evaluated by SAM as a function of time.
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He, Jianjun, Kaijun Yang, Gang Wang, Wei Li, Jiangyong Bao und Jian Chen. „Study on Tensile Creep Behavior of 12Cr1MoV Alloy Steel under High-Temperature Alkali Metal Salt Environment for Solar Thermal Power Generation“. International Journal of Photoenergy 2020 (13.03.2020): 1–9. http://dx.doi.org/10.1155/2020/7095872.
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The heat exchange tubes of solar thermal power generation work in molten salt environment with periodic temperature change. In order to reveal the tensile creep behavior of 12Cr1MoV pipeline steel under high-temperature alkali metal salt environment, the tensile creep behavior of 12Cr1MoV alloy under different applied load and reaction temperature in high-temperature alkali metal chloride salt environment was studied. The results show that the deformation of 12Cr1MoV alloy in 600°C, NaCl-35%KCl mixed salt environment is mainly controlled by diffusion creep; with the increase of stress, the creep life of 12Cr1MoV alloy decreases. The creep fracture mechanism of 12Cr1MoV alloy in 600°C, NaCl-35%KCl mixed salt environment is intergranular ductile fracture; the increase of temperature will enhance the activation and oxidation of the chlorine atoms, thereby accelerating the corrosion of the base metal and increasing the spheroidization speed of the pearlite matrix, and the creep deformation rate of the alloy increases with increasing temperature.
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Ahmed, Omar, Le Zhou, Nahid Mohajeri und Yong Ho Sohn. „Corrosion Behaviour of AISI 304 Stainless Steel with Solar Salt Heat Transfer Fluid“. Advanced Materials Research 922 (Mai 2014): 13–17. http://dx.doi.org/10.4028/www.scientific.net/amr.922.13.
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In an effort to understand the compatibility between the heat transfer medium and the structural materials used in concentrated solar power plants, the corrosion behavior of AISI 304 stainless steel (18 wt.% Cr, 8 wt.% Ni) in a molten solar salt mixture (53 wt. % KNO3, 40 wt. % NaNO2,7 wt. % NaNO3) has been investigated. The 304 stainless steel coupon samples were fully immersed and isothermally exposed to solar salt at 530°C for 250, 500, and 750 hours in air. X-ray diffraction and scanning electron microscopy with X-ray energy-dispersive spectroscopy were employed to examine the extent of corrosion and identify the corrosion products. Oxides of iron were found to be the primary corrosion products in the presence of the molten alkali nitrates-nitrite salt mixture because of the dissolution of the protective chromium oxide (Cr2O3) scale formed on 304 stainless steel coupons. The corrosion scale was uniform in thickness and chromium-iron oxide was found near the AISI 304. This indicates that the scale formed, particularly on the upper layer with presence of sodium-iron-oxide is protective, and forms an effective barrier against penetration of fused solar salt. By extrapolation, annual corrosion rate is estimated to reach 0.784 mils per year. Corrosion behavior of AISI 304 stainless steel is discussed in terms of thermodynamics and reaction paths.
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Li, Hui, Haotian Li, Jinglong Liang, Hongyan Yan und Zongying Cai. „Study on the Synergistic Extraction of Lithium from Spent Lithium Cobalt Oxide Batteries by Molten Salt Electrolysis and Two-Step Precipitation Method“. Crystals 11, Nr. 10 (24.09.2021): 1163. http://dx.doi.org/10.3390/cryst11101163.
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With the continuous development of society, the number of spent lithium-ion batteries has also increased, and the recovery of valuable metals such as Ni, Co, and Li has become the main research direction of many scholars. In this paper, the extraction process of lithium that enters the molten salt after LiCoO2 electrolysis is studied. Oxalic acid and phosphate are added to molten salt containing lithium ions to realize the two-part precipitation method to extract lithium. The influence of pH value, temperature, reaction time, and oxalic acid (or phosphate) addition on the process of oxalic acid calcium removal and phosphate lithium precipitation is analyzed. The results show that the calcium removal rate of oxalic acid has reached 99.72% (Initial conditions: PH = 7.0, T = 70 °C, t = 1.5 h, n(H2C2O4):n(Ca2+) = 1.2:1). The precipitation of Li3PO4 obtained in the phosphate extraction experiment of lithium is as high as 88.44% (Initial conditions: PH = 8.0, T = 70 °C, t = 1.5 h, n(actual dosage of Na3PO4):n(theoretical dosage of Na3PO4) = 1.2:1). The obtained lithium phosphate crystals show regular spherical particles, which can be seen by SEM.
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Kataev, A. A., O. Yu Tkacheva, N. G. Molchanova und Yu P. Zaikov. „Production of the Al–B master alloy by KBF4and B 2O3aluminothermic reduction in molten salt flux medium“. Izvestiya Vuzov Tsvetnaya Metallurgiya (Proceedings of Higher Schools Nonferrous Metallurgy, Nr. 3 (19.06.2019): 20–29. http://dx.doi.org/10.17073/0021-3438-2019-3-20-29.
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The study covers the process of obtaining the Al–B master alloy by the KBF4and B2O3aluminothermic reduction using KF–AlF3and KF–NaF–AlF3fluoride fluxes at 983 and 1123 К, respectively, and KCl–NaCl–KF chloride-fluoride fluxes at Т= 1173÷1223 К. All experiments were carried out under the same conditions: molten mixture stirring rate was 400 rpm, synthesis duration was 30min. The maximum amount of boron (1,5 %) in the Al–B alloy was obtained when using KBF4(3 % per B) as a boron-containing raw material in the KF–AlF3medium with a molar (cryolite) ratio (CR) of KF/AlF3equal to 1,3, atТ= 983 К, while boron recovery ratio did not exceed 75 %. Comparable results were obtained in experiments with KF–NaF–AlF3f lux (CR = 1,5) at Т= 1123 К. However, with the increased concentration of fed boron its recovery ratio decreased substantially. It is connected with the higher decomposition temperature of not only KBF4, but also less thermally stable NaBF4 formed as a result of exchange reaction in the melt. Therefore it is not recommended to use sodium salts as a f lux component. The Al–B master alloys obtained by KBF4reduction in fluoride fluxes were solid solutions of B in Al containing the AlB2intermetallic compound. The lowest amount of boron in aluminum with the minimum degree of extraction was obtained in experiments with the B2O3in molten KF–AlF3with CR = 1,5. Nevertheless, the results of scanning electron microscopy indicate a uniform distribution of B over the Al matrix and the absence of intermetallic compounds, while a large amount of Al2O3was found, which is the product of B2O3reactions with both liquid Al and KF–AlF3flux.
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Huang, Tao, und Peng Tian. „Determination of N-Heptyl Pyridine Tetrafluoroborate in Acetonitrile Using UV–Spectrum“. Applied Mechanics and Materials 707 (Dezember 2014): 12–15. http://dx.doi.org/10.4028/www.scientific.net/amm.707.12.
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Ionic Liquids is called also room temperature molten salt, its performance is mainly dependent on composition of cation and anion, and through molecular design the adjustment. And the traditional organic solvent, water, supercritical fluid and chemical reaction than solvent, ionic liquid in the following several aspects to show its prominent advantages. N-heptyl-pyridine tetrafluoroborate is prepared by the double decomposition reaction of HEPB and NaBF4. The ionic liquid at room temperature used in the experiment has a significant absorption determined by UV spectrum within the range of 200-400nm, the maximum absorption wavelength of HEP-BF4 ionic liquid in acetonitrile is 240nm. The standard working curve of HEP-BF4 ionic liquid is y=0.04518+0.03124X (R=0.99963). The linear range of HEP-BF4 ionic liquids in the acetonitrile is 1-75 mg/L. The recovery rate of HEP-BF4 ionic liquid which is between 95.9% and 102%, is measured by standard addition method in acetonitrile.
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Zhang, Cheng Cheng, Peng Tian und Qing Yang Chen. „Determination Content of N-Octyl Pyridine Tetrafluoroborate in Water Using UV-Spectrum“. Applied Mechanics and Materials 707 (Dezember 2014): 20–23. http://dx.doi.org/10.4028/www.scientific.net/amm.707.20.
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Ionic Liquids is called also room temperature molten salt, its performance is mainly dependent on composition of cation and anion, and through molecular design the adjustment. And the traditional organic solvent, water, supercritical fluid and chemical reaction than solvent, ionic liquid in the following several aspects to show its prominent advantages. OP-BF4 ionic liquid is prepared by the double decomposition reaction of OPB and NaBF4. The ionic liquid at room temperature used in the experiment has a significant absorption determined by UV spectrum within the range of 200-400nm, the maximum absorption wavelength of OP-BF4 ionic liquid is 255nm. The standard working curve of OP-BF4 ionic liquid is y=0.06476+0.00967X (0.99918). The recovery rate of OP-BF4 ionic liquid which is between 96.4% and 102%, is measured by standard addition method in water. The quantitative analysis of OP-BF4 ionic liquids in water using ultraviolet spectroscopy is simple, accurate and reliable.
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Ateia, Mohamed, Mahmoud Nasr, Chihiro Yoshimura und Manabu Fujii. „Organic matter removal from saline agricultural drainage wastewater using a moving bed biofilm reactor“. Water Science and Technology 72, Nr. 8 (07.07.2015): 1327–33. http://dx.doi.org/10.2166/wst.2015.347.
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We investigated the effect of salinity on the removal of organics and ammonium from agricultural drainage wastewater (ADW) using moving bed biofilm reactors (MBBRs). Under the typical salinity level of ADW (total dissolved solids (TDS) concentration up to 2.5 g·L−1), microorganisms were acclimated for 40 days on plastic carriers and a stable slime layer of attached biofilm was formed. Next, six batch mode MBBRs were set up and run under different salinity conditions (0.2–20 g-TDS·L−1). The removal efficiency of chemical oxygen demand (COD) and ammonium–nitrogen (NH4-N) in 6 hours decreased from 98 and 68% to 64 and 21% with increasing salt concentrations from 2.5 to 20 g-TDS·L−1, respectively. In addition, at decreasing salt levels of 0.2 g-TDS·L−1, both COD removal and nitrification were slightly lowered. Kinetic analysis indicated that the first-order reaction rate constant (k1) and specific substrate utilization rate (U) with respect to the COD removal remained relatively constant (10.9–11.0 d−1 and 13.1–16.1 g-COD-removed.g-biomass−1·d−1, respectively) at the salinity range of 2.5–5.0 g-TDS·L−1. In this study, the treated wastewater met the standard criteria of organic concentration for reuse in agricultural purposes, and the system performance remained relatively constant at the salinity range of typical ADW.
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Tan, B., S. Wu, L. J. Wang und K. C. Chou. „High efficiency extractions of V, Cr, Ti, Fe and Mn from vanadium slag by microwave heating“. Journal of Mining and Metallurgy, Section B: Metallurgy 57, Nr. 2 (2021): 271–77. http://dx.doi.org/10.2298/jmmb190827023t.
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The vanadium slag (V-slag) is generated from smelting vanadium titanomagnetite ore, which contains valuable elements, such as V, Ti, Cr, Fe, and Mn. The traditional methods were mainly focused on the extractions of V and Cr by oxidation or reduction processes. In the present work, chlorination method was adopted to keep the valence state of each element in original state. In order to speed up the diffusion of elements and reduce volatility of molten salt, microwave heating was examined in the current paper. The results indicated that it only took 30 min to chlorinate V-slag at 800 ?C, and the chlorination ratios of V, Cr, Mn, Fe, and Ti reached to 82.67%, 75.82%, 92.96%, 91.66%, and 63.14%, respectively. Compared with the results by conventional heating for 8 h, this extraction rate by microwave heating showed greater advantages. In addition, microwave heating effectively reduced volatilization of AlCl3 by shortening the reaction time. The volatilization ratio of AlCl3 in this microwave heating was 3.92% instead of 8.97% in conventional heating (1h). The mechanism of efficient chlorination can be summarized as the enhancement of ions diffusion process and enhanced chemical reaction due to local high temperature.
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Nikolić, Nebojša D., Vesna M. Maksimović und Ljiljana Avramović. „Correlation of Morphology and Crystal Structure of Metal Powders Produced by Electrolysis Processes“. Metals 11, Nr. 6 (24.05.2021): 859. http://dx.doi.org/10.3390/met11060859.
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In this review paper, morphologies of metal powders produced by the constant (potentiostatic and galvanostatic) regimes of electrolysis from aqueous electrolytes are correlated with their crystal structure at the semiquantitative level. The main parameters affecting the shape of powder particles are the exchange current density (rate of electrochemical process) and overpotential for hydrogen evolution reaction. Depending on them, various shapes of dendrites (the needles, the two-dimensional (2D) fern-like, and the three-dimensional (3D) pine-like dendrites), and the particles formed under vigorous hydrogen evolution (cauliflower-like and spongy-like particles) are produced by these regimes of electrolysis. By decreasing the exchange current density value, the crystal structure of the powder particles is changed from the strong (111) preferred orientation obtained for the needle-like (silver) and the 2D (lead) dendrites to the randomly orientated crystallites in particles with the spherical morphology (the 3D dendrites and the cauliflower-like and the spongy-like particles). The formation of metal powders by molten salt electrolysis and by electrolysis in deep eutectic solvents (DESs) and the crystallographic aspects of dendritic growth are also mentioned in this review.
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MASSON, Patrick, Cécile CLÉRY, Patrice GUERRA, Arnaud REDSLOB, Christine ALBARET und Pierre-Louis FORTIER. „Hydration change during the aging of phosphorylated human butyrylcholinesterase: importance of residues aspartate-70 and glutamate-197 in the water network as probed by hydrostatic and osmotic pressures“. Biochemical Journal 343, Nr. 2 (08.10.1999): 361–69. http://dx.doi.org/10.1042/bj3430361.
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Wild-type human butyrylcholinesterase (BuChE) and Glu-197 → Asp and Asp-70 → Gly mutants (E197D and D70G respectively) were inhibited by di-isopropyl phosphorofluoridate under standard conditions of pH, temperature and pressure. The effect of hydrostatic and osmotic pressures on the aging process (dealkylation of an isopropyl chain) of phosphorylated enzymes [di-isopropylated (DIP)-BuChE] was investigated. Hydrostatic pressure markedly increased the rate of aging of wild-type enzyme. The average activation volume (δV≠) for the dealkylation reaction was -170 ml/mol for DIP wild-type BuChE. On the other hand, hydrostatic pressure had little effect on the aging of the DIP mutants (δV≠ = -2.6 ml/mol for E197D and -2 ml/mol for D70G), suggesting that the transition state of the aging process was associated with an extended hydration and conformational change in wild-type BuChE, but not in the mutants. The rate of aging of wild-type and mutant enzymes decreased with osmotic pressure, allowing very large positive osmotic activation volumes (δV≠osm) to be estimated, thus probing the participation of water in the aging process. Molecular dynamics simulations performed on the active-site gorge of the wild-type DIP adduct showed that the isopropyl chain involved in aging was highly solvated, supporting the idea that water is important for stabilizing the transition state of the dealkylation reaction. Wild-type BuChE was inhibited by soman (pinacolyl methylphosphonofluoridate). Electrophoresis performed under high pressure [up to 2.5 kbar (1 bar = 105 Pa)] showed that the soman-aged enzyme did not pass through a pressure-induced, molten-globule transition, unlike the native wild-type enzyme. Likewise, this transition was not seen for the native E197D and D70G mutants, indicating that these mutants are resistant to the penetration of water into their structure. The stability energetics of native and soman-aged wild-type BuChE were determined by differential scanning calorimetry. The pH-dependence of the midpoint transition temperature of endotherms indicated that the high difference in stabilization energy between aged and native BuChE (δδG = 23.7 kJ/mol at pH 8.0) is mainly due to the salt bridge between protonated His-438 and PO-, with pKHis-438 = 8.3. A molecular dynamics simulation on the MIP adduct showed that there is no water molecule around the ion pair. The ‘hydrostatic versus osmotic pressure’ approach probed the importance of water in aging, and also revealed that Asp-70 and Glu-197 are the major residues controlling both the dynamics and the structural organization of the water/hydrogen-bond network in the active-site gorge of BuChE. In wild-type BuChE both residues function like valves, whereas in the mutant enzymes the water network is slack, and residues Gly-70 and Asp-197 function like check valves, i.e. forced penetration of water into the gorge is not easily achieved, thereby facilitating the release of water.
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Zou, B., C. S. McCool, D. W. Green und G. P. Willhite. „A Study of the Chemical Interactions Between Brine Solutions and Dolomite“. SPE Reservoir Evaluation & Engineering 3, Nr. 03 (01.06.2000): 209–15. http://dx.doi.org/10.2118/64536-pa.
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Summary Application of gelled polymer treatments to change the flow characteristics of a reservoir is a viable improved oil recovery technique. Many gel systems are affected by the solution pH in that gel time is pH dependent. The treatment of carbonate reservoir rock is of particular concern because (1) fluid-rock interaction can alter the pH of the injected solution from the design value and (2) dissolution of carbonate can increase the divalent ion concentration, which can also affect gelation behavior. In this study, the interaction between injected potassium chloride brine and dolomite was investigated through displacement experiments in dolomite cores and mathematical modeling based on equilibrium thermodynamics. Parameters varied were pH of the injected solution, flow rate, and the common ion effect through variation of the calcium and magnesium ion concentrations in the injected solution. Core effluent values of pH and concentrations were measured. Experiments at different flow rates established conditions in which equilibrium was achieved in the core. Equilibrium values of pH were almost constant at a value of 10 when the injected pH was varied between 4 and 10. Results indicate that equilibrium conditions exist for most field conditions. A geochemical model was used to predict equilibrium pH and concentrations, as well as the amount of dolomite dissolved. The model accurately predicted effluent pH of experimental displacement data for the conditions wherein equilibrium was achieved. All model parameters were obtained from literature equilibrium data and were not dependent on curve fitting of the experimental data. Introduction Systems utilizing Cr(III) as the polymer crosslinker are probably the most frequently studied and used gelled polymer systems for water conformance treatments. Both xanthan and partially hydrolyzed polyacylamide form gels with Cr(III). Both of these gel systems are affected by the pH of the solution in at least two ways. One is that the gelation time decreases significantly with increasing pH.1 The other is that Cr(III) is subject to precipitation in solutions with pH over 5.5, and the precipitation is aggravated with increasing pH.2 The treatment of carbonate reservoir rock is of particular concern because of the fluid-rock interaction, which can alter the pH of the injected solution. Previous studies3–5 show that change of pH of the injected solution inhibits the propagation of Cr(III) in carbonate cores or sandstone cores containing carbonate as the solution flows through porous rock. Seright3 studied the propagation of chromium acetate or chromium chloride through Indiana limestone cores. Cr(III) concentration in the effluent never reached the injected concentration after injecting about 10 pore volumes of chromium solution for any case studied. Chromium propagated more rapidly when the counterion was acetate as opposed to chloride. No chromium was detected in the effluent after injecting 10 pore volumes of chromium chloride solution through a limestone core. Stavland et al.4 studied the retention of chromium(III) in Brent and Berea sandstone cores (with about 2% carbonate content). The authors found precipitation was the most important reason for chromium retention in cores. Precipitation was caused by the dissolution of carbonate minerals that increased the pH of the injected solution. Their experiments also revealed that the retention rate of Cr(III) was lower with less carbonate present in the cores. McCool et al.5 studied the interaction between a dolomite core and a xanthan-Cr(III) gel system. Significant amounts of Cr(III) precipitated because the pH in the injected solution increased due to the dissolution of dolomite. Equilibrium relations and the dissolution kinetics in dolomite-carbonic acid-water systems have been studied for such purposes as soil science, the study of secondary changes in sedimentary deposits, the neutralization of acid mine drainage, and the acidizing of petroleum wells. 6 Most previous studies were conducted in agitated batch reactors, rotating disk, or fluidized bed reactor systems in the laboratory by using relatively pure dolomitic rock or synthetic dolomite. A few investigators have studied the dissolution reaction using flow through packed-bed reactors or consolidated rock cores.7,8 Many investigators recognize the complexity of the dissolution of dolomite. Most have attempted to simplify the modeling by delineating the rate-limiting steps. It is apparent that in making assumptions and interpretations of data most investigators have often been limited by the type of apparatus, the size and origin of dolomite used, and the experimental conditions. Consequently, the kinetic equations and mechanisms proposed by different investigators explain their experimental data, but they are not easily generalized. The rate equations derived by Plummer and Busenberg9 and those from Chou et al.10 are often used to predict the dolomite dissolution rates within a 2- to 100-fold difference, depending on the reaction conditions. It is believed that the dissolution rate is controlled by surface reaction, reactant or product diffusion, or a combination depending on reaction conditions. Also, the dissolution of dolomite reaches equilibrium much faster in a closed-to-atmosphere system than in an open system in which the transport of carbon dioxide from the atmosphere is involved in the reactions. The dissolution rate is affected by the rock lithology such as impurity content, crystal size, rock texture, and Ca/Mg ratio in the rock and the injected solution chemistry such as the pH and composition. The effect of the rock formation on dolomite dissolution was the dominant interest in many previous investigations. Rauch and White7 investigated the effect of lithology on carbonate dissolution rate. The authors found that the dissolution rate decreased as the percentage of dolomite and disseminated insolubles increased. The general chemistry of dolomite dissolution has been studied extensively, though some dissolution mechanisms are still under debate. As a salt of a weak acid, dolomite dissolves in strong acid, carbonated water, and water by different mechanisms. In water, the general chemistry is C a M g ( C O 3 ) 2 = C a 2 + + M g 2 + + 2 C O 3 2 − . ( 1 ) When carbon dioxide is present, the dissolution has the reaction C a M g ( C O 3 ) 2 + 2 H 2 C O 3 = C a 2 + + M g 2 + + 4 H C O 3 − . ( 2 ) When in strong acidic solution, the following reaction occurs:6 C a M g ( C O 3 ) 2 + 4 H + = C a 2 + + M g 2 + + 2 C O 2 ( a q ) + 2 H 2 O . ( 3 )
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Hombourger, Boris A., Jiří Křepel, Konstantin Mikityuk und Andreas Pautz. „Parametric Lattice Study of a Graphite-Moderated Molten Salt Reactor“. Journal of Nuclear Engineering and Radiation Science 1, Nr. 1 (01.01.2015). http://dx.doi.org/10.1115/1.4026401.
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Molten salt reactors (MSRs) are promising advanced nuclear reactors for closure of the fuel cycle. This paper discusses the core design of graphite-moderated MSRs, thanks to a parametric study of the fuel and moderator lattice. The study is conducted at equilibrium of the thorium-uranium fuel cycle for several fuel channel radius and moderator block size combinations. The equilibrium composition for each studied configuration is derived with the help of an in-house MATLAB code, EQL0D, which uses the Serpent 2 Monte Carlo neutronics code for the calculation of reaction rates. The results include excess reactivity at equilibrium, mirroring the breeding gain, and the actinide vector composition for each configuration. Moreover, the occurence of an optimum of the excess reactivity per percent uranium-233 was observed. The investigations showed that it is systematically seen at an interchannel distance equal to the neutron slowing-down length in graphite for each configuration and does not depend on the salt channel radius beyond a certain size, which is given by the thermal fission rate reaching the levels of the fast fission rate. In this way, an exotic energy and spatial distribution of the neutrons are attained. The investigations highlight the potential attractiveness, from a neutronics/fuel cycle point of view, of both large fuel channels and moderators with a shorter neutron slowing-down length.
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„The thermal decomposition of dehydrated d -lithium potassium tartrate monohydrate: molecular modification by a homogeneous melt mechanism“. Proceedings of the Royal Society of London. Series A: Mathematical and Physical Sciences 440, Nr. 1908 (08.01.1993): 77–93. http://dx.doi.org/10.1098/rspa.1993.0005.
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Lithium potassium tartrate decomposes between 485–540 K: n LiKC 4 H 4 O 6 → n LiKCO 3 + n H 2 O + n CO 2 + (C 2 H 2 ) n . Isothermal fractional reaction ( α )-time plots are sigmoid shaped and the kinetic data for single crystal reactants obey the Avrami–Erofe’ev equation { –ln (1— α )} 1/2 = kt , 0.04 < α < 0.96, usually accepted as evidence of a nucleation and growth process. Examination of the dark brown viscous residual product and microscopic observations of partly reacted salt gave evidence that reaction was accompanied by melting. The decomposition rate was increased only slightly by crushing the crystalline reactant hydrate, which underwent rapid initial dehydration before onset of the anion breakdown reaction. Kinetic characteristics of the evolutions of both CO 2 and H 2 O were identical and the activation energy for salt decomposition was relatively large, 220±20 kJ mol -1 . The study reported here was predominantly concerned with the d form of the tartrate anion but observations included the decompositions of some related reactants including LiK salts of dl and meso tartaric acids. The reaction mechanism proposed is anion decomposition within an advancing thin layer of molten material that is formally similar (in some respects) to the reaction interface developed during decompositions of solids. Reactant melts or dissolves at one side of the active liquid zone and residual products accumulate at the outer side. Anion breakdown then occurs relatively easily in the molten region after removal from the stabilizing influence of the crystal cohesive forces. Kinetic characteristics are similar to those often found for the reactions of solids except for crushed salt samples where an increase in rate after ca . 50% reaction is ascribed to the onset of more extensive melting. This pattern of kinetic behaviour is so closely similar to that for many reactions of solids that we suggest it to be appropriate to consider the possibility of local or temporary melting in formulating detailed reaction mechanisms for all such rate processes.
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„The kinetics and mechanism of water evolution from molten dl lithium potassium tartrate monohydrate“. Philosophical Transactions of the Royal Society of London. Series A: Physical and Engineering Sciences 341, Nr. 1662 (15.12.1992): 479–98. http://dx.doi.org/10.1098/rsta.1992.0112.
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A kinetic and microscopic investigation of the thermal dehydration of dl lithium potassium tartrate monohydrate is reported and the reaction mechanism discussed. This work forms part of a more comprehensive study concerned with the influence of reactant structure on the reactivity and the mechanism of chemical change. The other hydrated reactants with which this salt will be compared contain the d and meso forms of the tartrate anion and crystallize with different structures. dl lithium potassium tartrate monohydrate lost the single molecule of water of crystallization in one predominantly deceleratory process that was studied between 350-460 K. Reaction was accompanied by melting to yield a residual glassy anhydrous product that was amorphous to X-ray diffraction. An initial, relatively rapid release of water (6%) was followed by a deceleratory process that led to a zero-order reaction (that, in crystals, extended between 18% and 80% ) before completion by an approximately first-order stage. Dehydrations of crushed powder reactant samples differed from single crystals in being relatively more rapid (an eight-fold increase); the deceleratory process was long and the zero-order process shorter (50-85%). The activation energy for dehydrations of crystal and of powder was 330 + 30 kJ mol -1 . This pattern of kinetic behaviour was not in accordance with expectation for a homogeneous reaction, the rate was not directly related to reactant concentration terms. Alternative analyses of the obedience of data to rate expressions applicable to solid state reactions were equally unsuccessful. Our mechanistic interpretation of the rate data, therefore, considered a priori the factors expected to participate in the control of water evolution from the melt. It is concluded that the vitreous or molten phase is not homogeneous and, therefore, behaviour is different from reactions in an isotropic fluid or in a solid. Two models are proposed to explain our observations. In the two phase equilibrium mechanism it is assumed that the reactant particles are composed of two phases, zones of hydrate are embedded in dehydrated material that retains a constant but small proportion of water. (These phases participate in an equilibrium analogous to that of liquid/vapour.) The surface boundary layer model envisages the initial development of a peripheral barrier zone through which the constant rate of water diffusion is rate controlling. This class of reaction, proceeding in a fluid but the absence of added solvent, has received relatively little attention. The present discussion is intended to identify the characteristic behaviour and draw attention to the necessity to consider such mechanisms in discussions of reactions of solids where there is the possibility of melt participation.
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Liu, Xiaoyang, Arthur Ronne, Lin-Chieh Yu, Yang Liu, Mingyuan Ge, Cheng-Hung Lin, Bobby Layne et al. „Formation of three-dimensional bicontinuous structures via molten salt dealloying studied in real-time by in situ synchrotron X-ray nano-tomography“. Nature Communications 12, Nr. 1 (09.06.2021). http://dx.doi.org/10.1038/s41467-021-23598-8.
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AbstractThree-dimensional bicontinuous porous materials formed by dealloying contribute significantly to various applications including catalysis, sensor development and energy storage. This work studies a method of molten salt dealloying via real-time in situ synchrotron three-dimensional X-ray nano-tomography. Quantification of morphological parameters determined that long-range diffusion is the rate-determining step for the dealloying process. The subsequent coarsening rate was primarily surface diffusion controlled, with Rayleigh instability leading to ligament pinch-off and creating isolated bubbles in ligaments, while bulk diffusion leads to a slight densification. Chemical environments characterized by X-ray absorption near edge structure spectroscopic imaging show that molten salt dealloying prevents surface oxidation of the metal. In this work, gaining a fundamental mechanistic understanding of the molten salt dealloying process in forming porous structures provides a nontoxic, tunable dealloying technique and has important implications for molten salt corrosion processes, which is one of the major challenges in molten salt reactors and concentrated solar power plants.
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Ergul, Emre, Ishak Karakaya und Metehan Erdogan. „Reduction of Porous Silica Pellets by Electrodeoxidation in Molten Salts“. MRS Proceedings 1210 (2009). http://dx.doi.org/10.1557/proc-1210-q08-17.
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AbstractDirect electrochemical reduction of porous SiO2 pellets in molten CaCl2 salt and CaCl2-NaCl salt mixture were investigated by applying 2.8 V potential. The study focused on the effects of temperature, powder size and cathode contacting materials. Starting materials and electrolysis products were characterized by X-ray diffraction analysis and scanning electron microscopy. Due to reactive nature of silicon, different cathode contacting materials were used to test the extent of reactions between silicon produced at the cathode and the contacting materials. X-ray diffraction patterns showed that silicon produced at the cathode reacted with nickel, and iron in stainless steel to form Ni-Si and Fe-Si compounds respectively. Besides, studies revealed that higher temperature and smaller particle size had positive effects in increasing reduction rate. The results were interpreted from variation of current versus time graphs under different conditions, microstructures and compositions of the reduced pellets.
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„Selective Formation of Rare Earth-Nickel Alloys via Electrochemical Reactions in NaCl-KCl Molten Salt“. ECS Meeting Abstracts, 2014. http://dx.doi.org/10.1149/ma2014-02/25/1491.
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Chen, Lijie, Jiacong Xu, Xiaoqiang Yu, Lei Tian, Ruixiang Wang und Zhifeng Xu. „Thermodynamics and Kinetics of Sulfuric Acid Leaching Transformation of Rare Earth Fluoride Molten Salt Electrolysis Slag“. Frontiers in Chemistry 9 (02.03.2021). http://dx.doi.org/10.3389/fchem.2021.574722.
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Rare earth element recovery in molten salt electrolysis is approximately between 91 and 93%, whereof 8% is lost in waste molten salt slag. Presently, minimal research has been conducted on the technology for recycling waste rare earth molten salt slag, which is either discarded as industrial garbage or mixed with waste slag into qualified molten salt. The development of a new approach toward the effective treatment of rare earth fluoride molten salt electrolytic slag, which can recycle the remaining rare earth and improve the utilization rate, is essential. Herein, weak magnetic iron separation, sulfuric acid leaching transformation, water leaching, hydrogen fluoride water absorption, and cycle precipitation of rare earth are used to recover rare earth from their fluoride molten salt electrolytic slag, wherein the thermodynamic and kinetic processes of sulfuric acid leaching transformation are emphatically studied. Thermodynamic results show that temperature has a great influence on sulfuric acid leaching. With rising temperature, the equilibrium constant of the reaction gradually increases, and the stable interval of NdF3 decreases, while that of Nd3+ increases, indicating that high temperature is conducive to the sulfuric acid leaching process, whereof the kinetic results reveal that the activation energy E of Nd transformation is 41.57 kJ/mol, which indicates that the sulfuric acid leaching process is controlled by interfacial chemical reaction. According to the Nd transformation rate equation in the sulfuric acid leaching process of rare earth fluoride molten salt electrolytic slag under different particle size conditions, it is determinable that with the decrease of particle size, the reaction rate increases accordingly, while strengthening the leaching kinetic process. According to the equation of Nd transformation rate in the sulfuric acid leaching process under different sulfuric acid concentration conditions, the reaction series of sulfuric acid concentration K = 6.4, which is greater than 1, indicating that increasing sulfuric acid concentration can change the kinetic-control region and strengthen the kinetic process.
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Hathaway, Brandon J., Jane H. Davidson und David B. Kittelson. „Solar Gasification of Biomass: Kinetics of Pyrolysis and Steam Gasification in Molten Salt“. Journal of Solar Energy Engineering 133, Nr. 2 (08.04.2011). http://dx.doi.org/10.1115/1.4003680.
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The use of concentrated solar energy as a heat source for pyrolysis and gasification of biomass is an efficient means for production of hydrogen rich synthesis gas. Utilizing molten alkali carbonate salts as a reaction and heat transfer media promises enhanced stability to solar transients and faster reaction rates. The present study establishes and compares the reaction kinetics of pyrolysis and gasification of cellulose from 1124 K to 1235 K in an electric furnace. Data are presented in an inert environment and in a bath of a ternary eutectic blend of lithium, potassium, and sodium carbonate salts. Arrhenius rate expressions are derived from the data supported by a numerical model of heat and mass transfer. The molten salt increases the rate of pyrolysis by 74% and increases gasification rates by more than an order of magnitude while promoting a product gas composition nearer to thermodynamic equilibrium predictions. These results justify using molten carbonate salts as a combined catalyst and heat transfer media for solar gasification.
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Li, Youbing, Guoliang Ma, Hui Shao, Peng Xiao, Jun Lu, Jin Xu, Jinrong Hou et al. „Electrochemical Lithium Storage Performance of Molten Salt Derived V2SnC MAX Phase“. Nano-Micro Letters 13, Nr. 1 (22.07.2021). http://dx.doi.org/10.1007/s40820-021-00684-6.
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AbstractMAX phases are gaining attention as precursors of two-dimensional MXenes that are intensively pursued in applications for electrochemical energy storage. Here, we report the preparation of V2SnC MAX phase by the molten salt method. V2SnC is investigated as a lithium storage anode, showing a high gravimetric capacity of 490 mAh g−1 and volumetric capacity of 570 mAh cm−3 as well as superior rate performance of 95 mAh g−1 (110 mAh cm−3) at 50 C, surpassing the ever-reported performance of MAX phase anodes. Supported by operando X-ray diffraction and density functional theory, a charge storage mechanism with dual redox reaction is proposed with a Sn–Li (de)alloying reaction that occurs at the edge sites of V2SnC particles where Sn atoms are exposed to the electrolyte followed by a redox reaction that occurs at V2C layers with Li. This study offers promise of using MAX phases with M-site and A-site elements that are redox active as high-rate lithium storage materials.
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Munot, Samyak S., Ganesh V, Parimal P. Kulkarni und Arun K. Nayak. „Experimental Investigation of Melt Coolability and Ablation Behavior of Oxidic Sacrificial Material at Prototypic Conditions in Scaled Down Core Catcher“. Journal of Nuclear Engineering and Radiation Science 5, Nr. 4 (19.07.2019). http://dx.doi.org/10.1115/1.4043106.
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To minimize the potential risk of design extension conditions (DEC) with core meltdown, some advanced reactors employ ex-vessel core catchers which stabilize and cool the corium for prolonged period by strategically flooding it. This paper describes the coolability of the melt pool and ablation process in a scaled down ex-vessel core catcher employing sacrificial material which reduces the specific volumetric heat, temperature, and density of the melt pool. To understand these phenomena, a simulated experiment was carried out. The experiment was performed by melting about 500 kg of corium simulant using thermite reaction at about 2500 °C. The bricks of oxidic sacrificial material were arranged in the core catcher vessel which was surrounded by a tank filled with water up to a certain level. After the time required for melt inversion, water was introduced to flood the test section from the top. The melt pool temperatures were monitored at various locations using “K” and “C” type thermocouples to obtain ablation depth at different elevations with time. The results show that the coolability of the molten pool in the presence of water for the present geometry is achievable with outside vessel temperatures not exceeding 100 °C. A ceramic stable crust was observed at the top surface of the melt pool, which prevented water ingression into the molten corium. The ablation rate was found to be maximum at the lower corners of the brick arrangement with the maximum value being 0.75 mm/s. An average rate of about 0.18 mm/s was obtained in the brick matrix.
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Ajiriyanto, Maman Kartaman, Aslina Br Ginting, Supardjo Supardjo und Boybul Boybul. „PENGARUH TEMPERATUR DAN IRADIASI TERHADAP INTERDIFUSI PARTIKEL BAHAN BAKAR JENIS U−7Mo/Al“. Urania Jurnal Ilmiah Daur Bahan Bakar Nuklir 22, Nr. 1 (06.06.2016). http://dx.doi.org/10.17146/urania.2016.22.1.2740.
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PENGARUH TEMPERATUR DAN IRADIASI TERHADAP INTERDIFUSI PARTIKEL BAHAN BAKAR JENIS U−7Mo/Al. Paduan U−7Mo/Al memiliki potensi besar sebagai bahan bakar reaktor riset, tetapi bahan bakar ini memiliki beberapa kekurangan antara lain dapat membentuk interaction layer pada antarmuka pada saat proses fabrikasi maupun iradiasi di reaktor melalui mekaniame difusi. Penelitian ini dilakukan untuk mengetahui terjadinya interaction layer yang disebabkan oleh interdifusi atau diffusion couple paduan U−7Mo dengan pelat AlMg2 yang dipanaskan pada temperatur 500 °C dan 550 °C selama 24 jam dalam tungku arc furnace dan tungku DTA pada temperatur 30 °C hingga 1400 °C. Hasil pengamatan mikrostruktur menggunakan Scanning Electron Microscope (SEM) pada sampel diffusion couple hasil pemanasan pada temperatur 500 °C belum terlihat adanya interaction layeratau pembentukan fasa baru antara partikel U−Mo dan matriks Al. Sementara itu, pemanasan pada temperatur 550 °C telah terjadi interdifusi paduan U−7Mo dengan pelat AlMg2 menghasilkan senyawa (U,Mo)Alx pada antarmuka atau interface. Hal ini didukung oleh hasil analisis DTA menunjukkan bahwa paduan U−7Mo/Al pada 500 °C mempunyai kompatibilitas panas yang baik, tetapi diatas temperatur 550 °C telah terjadi perubahan fasa a + d menjadi a + g. Pemanasan hingga 679,14 °C terjadi fasa metastabil U(Al,Mo)x dan selanjutnya mengalami proses interdifusi dengan leburan uranium membentuk interaction layer berupa aglomerat senyawa UAlx (UAl4, UAl3 danUAl2). Aglomerat yang terbentuk dari proses pemanasan secara diffusion couple maupun dalam tungku DTA dibandingkan dengan aglomerat yang terbentuk akibat proses iradiasi. Bahan bakar paduan U−7Mo/Al yang diradiasi dengan burn up 58% mengalami interdifusi antara U−7Mo dengan matriks Al menghasilkan fasa metastabil U(Al,Mo)x yang berubah menjadi layer (U,Mo)Al7, presipitat UMo2Al20, (UMo)Al3−Al dan membentuk boundary atau aglomerat UAlx (UAl4, UAl3 danUAl2). Data ini didukung oleh analisis kekerasan mikro menggunakan Hardness Vickers dilakukan terhadap kelongsong AlMg dan paduan U−7Mo (sebelum dan sesudah pemanasan) serta sampel diffusion couple U−7Mo/Al dengan pelat AlMg2 hasil pemanasan pada temperatur 550 °C. Hasil analisis kerasan mikro yang diperoleh berturut−turut adalah 64,62 dan 340,45 HV (sebelum pemanasan) dan 52,34;303,16 dan 497,34 HV (setelah pemanasan). Dari ketiga sampel uji diperoleh kekerasan paling besar pada zona antarmuka sampel diffusion couple U−7Mo/Al dengan pelat AlMg2, bila dibandingkan dengan kelongsong AlMg2 dan juga paduan U−7Mo. Perbedaan kekerasan ini menunjukkan bahwa pada pengujian interdifusi menggunakan metode diffusion couple menghasilkan senyawa baru (U,Mo)Alx pada zona antarmuka yang memiliki karakter berbeda. Terbentuknya interaction layer tidak diharapkan dalam bahan bakar dispersi U−Mo/Al karena layer senyawa (U,Mo)Alx memiliki kekerasan mikro dan densitas lebih rendah dari pada densitas rata−rata paduan bahan bakar U−7Mo/Al.Kata kunci: U−7Mo/Al, diffusion couple, interaction layer, mikrostruktur, DTA dan kekerasan mikro. TEMPERATURE AND IRRADIATION EFFECTS TO INTERDIFUSSION OF FUEL MATERIAL U−7Mo/Al TYPE. U−7Mo/Al alloy had great potential as research reactor fuel, but it had several disadvantages, such as, it can formed a interaction layer at the interface during the process of fabrication and irradiation in a reactor. The research objective was determine the interaction layer that was caused by interdiffusion or diffusion couple of U−7Mo with AlMg2 alloy which was annealed at 500 °C and 550 °C for 24 hours. The observation of microstructure used a Scanning Electron Microscope (SEM) on diffusion couple sample which was heated at temperature of 500 °C had not seen the layer interaction or the formation of a new phase between particles of U−Mo and Al matrix, but heating treatment at 550 °C indicated that U−7Mo alloy had been interdiffusion with AlMg2 plate produced (U,Mo) Alx compound on the interfaces. It was evidenced by interdiffusion reaction analysis used DTA that showed that U−7Mo / Al alloy at 500 °C had good heat compactibility, but at temperatures upper than 550 °C it had been phase changed from a + d to a + g phase. The heating in DTA furnace up to 679.14 °C produced U(Al,Mo)x meta stable phase and then interdiffusion process with uranium molten formed layer interaction that formed UAlx compound agglomerates (UAl4, UAl3 and UAl2). Agglomerates was formed from the heating process which was similar to agglomerates that caused by irradiation. U−7Mo / Al Fuel alloy that had 58% burn up had been interdiffusion between U−7Mo with Al matrix produced U(Al,Mo)x metastable phase that turned into (U, Mo) Al7 layer, UMo2Al20 precipitates, (UMo)Al3−Al and formed a boundary or UAlx (UAl4, UAl3 and UAl2) agglomerates.The results of microstructure analysis used SEM and interdiffusion reactions used DTA was supported by the analysis of micro hardness used Vickers Hardness. The results of hardness analysis that was done to AlMg cladding and U−7Mo alloy (before and after heating) and diffusion couple of U−7Mo / Al samples with AlMg2 plate after heating at 550 °C were respectively 64.62 and 340.45 HV (before heating) and 52.34; 303.16 and 497.34 HV (after heating). Diffusion couple U−7Mo/Al with AlMg2 plate samples had the highest hardness value. This hardness difference showed that the interdiffusion test used diffusion couple produced a new compound (U, Mo) Alx in interface zone that had different character, but the formation of interaction layer is not expected in the fuel U−Mo / Al dispersion because micro hardness and density of (U, Mo) Alx compound’s layer was lower than the average density of U−7Mo/ Al alloy.Keywords: U−7Mo/Al, diffusion couple, interaction layer, microstructure, DTA and micro hardness.