Binary mixtures of tetrahydrofuran and methanol have an azeotropic point around 0.5 for the mol fraction of tetrahydrofuran at 100 kPa. In this work, process simulation of extractive distillation was performed for the separation of binary mixtures of tetrahydrofuran and methanol, using ethylene glycol as an extracting agent. Prior to the simulation, vapor liquid equilibria for the binary systems containing ethylene glycol were measured and modeled. According to the simulation results, the azeotropic mixture of tetrahydrofuran and methanol was separated with the extractive distillation process using ethylene glycol as the extracting agent.
Solubilities and physicochemical properties including refractive index, density, and pH of the ternary system (CaCl2+CaB6O10+H2O) at 308.15, 323.15 K and 0.1 MPa were determined experimentally with the method of isothermal dissolution equilibrium. Based on the experimental data, the phase diagrams and the diagrams of physicochemical properties versus the composition of CaCl2 in the system at 308.15 and 323.15 K were plotted. The phase diagrams of the ternary system at two temperatures are all consisted with one invariant co-saturation point, two univariant curves and two crystallization regions corresponding to calcium chloride tetrahydrate (CaCl2·4H2O) and gowerite (CaB6O10·5H2O) at 308.15 K and siniarite (CaCl2·2H2O) and gowerite (CaB6O10·5H2O) at 323.15 K, respectively. The hydrates in this system at both temperatures belong to a hydrate type I, and neither double salts nor solid solution were formed. A comparison of the phase diagrams at both temperatures shows that the areas of the crystallized regions of calcium chloride and calcium borate are decreased obviously, and those results indicate the solubilities of calcium chloride and calcium borate increased with the increasing of temperature correspondingly. The physicochemical properties (density, refractive index and pH) in the ternary system at both temperatures changed regularly with the mass fraction of calcium chloride in the solution. With the increasing of calcium chloride composition, the density and refractive index are increased significantly to reach the maximum values at the invariant points, and then decreased obviously. On the contrary, pH values in the system at two temperatures are similarly decreased firstly, and then increased, and gain the minimum values at the invariant points.
A novel high-speed disperser equipped with a rotor of simple structure is proposed to intensify the process of polymer devolatilization, which is almost indispensable in polymer manufacturing. Experiments on the rate of acetone removal from highly viscous acetone–syrup solution were conducted under different operating conditions. The results indicated that, as the absolute pressure decreased, the acetone removal rate increased gradually and the removal of acetone was derived successively from diffusion and foam devolatilization. Meanwhile, the acetone removal rate increased with increasing rotor rotational speed and initial acetone concentration, but decreased with increasing inlet flow rate. Besides, based on our previous work on the dimension and flow characteristics of highly viscous liquid filaments, a semi-empirical model of devolatilization was established to describe the process of diffusion devolatilization. A comparison between the experimental data and modeling results showed that the semi-empirical model was able to provide reasonable estimates of the acetone removal rate in diffusion devolatilization.
Numerical simulations of methane seepage at the Joetsu Basin, the Japan Sea, were carried out, and the rising and drifting behavior of methane at a water depth of 940 m was investigated. The seeping methane bubbles and hydrates were numerically tracked by a Lagrangian method. The numerical model of tracking methane gas considered the phase change of methane due to thermophysical conditions. The amount of seeping methane from the seabed and the initial bubble diameter distribution were given based on a field observation, and the ambient flow conditions were given with the JCOPET reanalysis data of the JAMSTEC. Three ambient flow conditions were used to assess the dependency of the numerical algorithm because the JCOPET reanalysis data included an uncertainty in the flow velocity components. The comparison of the numerical results obtained using three different ambient flow conditions showed that the plume structure formed by dispersed methane gas/hydrate strongly depended on the horizontal current flow. For the flow conditions close to those of actual sea current conditions, seeping methane gas changed to hydrate after a few meter rising from the seabed, and it returned to the gas phase at a water depth of about 300 m, corresponding to the limit of hydrate stability. The numerically predicted transition of methane gas in deep water agreed with the field observation at the Joetsu Basin. We then concluded that the present numerical model is useful for predicting the methane seepage phenomena in deep water.
The motions of particles injected from two different sprayers were investigated. The present investigation deals with automotive paint sprayers, a high-speed rotary bell-cup atomizer and a powder spray gun. The liquid droplets and powder coatings in each paint system were modeled as undeformable spherical particles, and the two-phase flow was numerically computed with the Euler–Lagrange approach. The Reynolds averaged Navier–Stokes equation was solved with the standard k–ε model. As a result, despite the difference in spray system, the spread of spray near the nozzle, so called ghost, was observed in both sprayers. When electric voltage was applied, the bell-cup atomizer had relatively strong tendencies of the motion behavior of paint particles compared with powder spray gun: (a) large particles in ghost propagated radially outward and missed the target, and (b) the transfer efficiency was sensible to Sauter mean diameter. On the other hand, when zero electric voltage was applied, an opposite trend was observed. Thus, in the case of the industrial spray process using bell-cup atomizers with high voltage, the control technique of the particle diameter might be of great significance in order to improve transfer efficiency.
The present study measured free surface profiles of doctor-bladed fluids on engraved roll surface in order to quantify the volumes of fluid retained in tri-helical grooves. The fluid overfilled the grooves to cover the entire surface of the roll at low roll speeds; whereas, it exhibits a concave surface profile in each groove at high speeds, i.e. a starved configuration with a partial filling of the groove. The overfill-to-starve transition was observed with decreasing the static liquid pressure and the depth-to-width aspect ratio of grooves, or increasing the blade thickness and the fluid viscosity. The dimensionless volumes of residue on the roll obeyed a master curve with respect to a balance between the pressure-driven and viscous drag flows. An empirical equation was newly derived based on the one-dimensional lubrication approximation, which allowed us to predict an optimum condition in stable gravure coating operations.
A novel photocatalytic microreactor is developed, which comprises two stacked channels divided by a TiO2/Ti bi-layered plate. Under ultraviolet (UV) light irradiation to the TiO2 channel (oxidation channel), the photo-induced holes cause oxidation in the irradiated channel, and residual electrons are transferred through a Ti plate to the other channel (reduction channel) and used for the reduction. The feasibility of this microreactor was studied by combining the oxidation of citric acid in the oxidation channel and the reducing Fe3+ ions in the reduction channel. Fe3+ was reduced to Fe2+ in the reduction channel. The conversion was drastically enhanced by increasing the pH of the citric acid solution in the oxidation channel.
This paper presents a novel Teaching-Learning-Self-Study-Optimization (TLSO) algorithm which is not only fast converging according to the number of iterations, but also relatively consistent in converging with high accuracy to the global minimum in comparison with some other algorithms. The original Teaching-Learning-Based Optimization (TLBO) gives uniformly distributed and randomly selected weight to the amount of knowledge to a learner at each phase, i.e., teacher phase and learner phase. This uniformly distributed and randomly selected weight causes the algorithm to converge the average cost of learners in a moderate number of iterations. Li and his coworkers intensified the teacher and learner phases by introducing weight-parameters in order to improve the convergence speed in terms of iterations in 2013 and called it Ameliorated Teaching-Learning-Based Optimization (ATLBO). The criterion of a good evolutionary optimization algorithm is to be consistent in converging the cost of the objective function. For this, it should include intensification for local search as well as diversification for global search in order to reduce the chances of trapping in a local minimum. Some students naturally tend to study by themselves by the means of a library and internet academic resources in order to enhance their knowledge. This phenomenon is termed as self-study and is introduced in the proposed TLSO’s learner phase as a diversification factor (DF). Various other evolutionary algorithms such as ACO, PSO, TLBO, ATLBO and two variants of TLSO are also developed and compared with TLSO in terms of consistency to converge to the global minimum. Results reveal that the TLSO was found to be consistent not only for a higher number of functions among 20 benchmark functions, but also for NOx prediction application. Results also show that the predicted NOx emissions through LSSVM tuned with TLSO are comparable with the other algorithms considered in this work.
The dissolution kinetics of sparingly soluble electrolyte have great significance in solving the engineering problems such as salt refining, pipe fouling and mineral exploitation. The present study focuses on the dissolution kinetics of CaSO4, CaCO3, MgCO3, Ca(OH)2, and Mg(OH)2. The conductance method was used to measure the relationship between concentration and time. Two models of dissolution kinetics were developed according to the shrinking core model. The experimental data were successfully correlated using the developed model. The correlation results show that the average relative error of the two developed models were 0.7% and 0.78%, respectively. Meanwhile, compared to conventional models, the new models are more valuable in practical application.
Selective fermentation of reducing sugars in mixed saccharides is an emerging key technology for productivity enhancement utilizing high-yielding sugarcane cultivars in cane sugar mills coproducing sugar, ethanol and electricity. In this paper, a sophisticated analysis on the heat exchanger networks for inlet and outlet of selective fermentation is performed. As a key constraining parameter, the effect of availability of hot/cold heats at cane sugar mills on energy use, investment efficiency and process complexity were examined. The results demonstrated that no additional fuels are needed for implementing selective fermentation into cane sugar mills by utilizing bagasse as fuel. The heat exchanging between process streams should be incorporated to save main steam and initial cost for temperature control for selective fermentation. Cold heat acquisition has a high impact on the final decision in the choice of precooling and heating units.
Semi-batch and batch-wise reactive crystallization of Li2CO3 was carried out in the presence of magnesium chloride. Magnesium impurity restrained crystal growth, and modified the crystal shape as well as crystal size distribution. However, the added magnesium impurity was usually contained in the product crystals. There was an optimal range for the amount of magnesium impurity. In this study, the influence of temperature was also investigated. In general, the solubility of lithium carbonate decreases with temperature, and it is higher than other sparingly soluble compounds such as CaCO3 and BaSO4. In this study, higher temperatures (70°C and above) were better for obtaining homogeneous crystals because higher supersaturation was possible.
Independent controlling of micro- (<2 nm), meso- (2–50 nm) and macropore (>50 nm) structures in monolithic carbon gels (CGs) was achieved by simply adjusting three independent synthetic parameters. Monolithic composites of resorcinol–formaldehyde (RF) gel and poly(methylmethacrylate) (PMMA) particles were prepared and subsequently carbonized yielding carbonized monoliths. Macropores were successfully introduced as traces of the PMMA particles without hardly affecting the structures of the micro- and mesopores of CGs. The size of the macropores can be controlled in the range of 0.05–1.0 µm by adjusting the size of the PMMA particles. The size of the mesopores can also be controlled in the range of a few to a few tens of nanometers by adjusting the concentration of the catalyst in the starting RF solution. Micropores can be efficiently developed by activating the CG monoliths with CO2 gas yielding monoliths having extremely high BET surface areas up to ∼3000 m2 g−1.
For producing chemically stable slag from municipal solid wastes melting, the present work is concerned with a kinetic study on the dissolution of CaO into molten slag. Experiments for the dissolution of CaO were performed using a lab-scale electric furnace at the temperatures of 1,723 to 1,773 K under N2 flow, where CaO particles of 0.3–0.355, 0.5–1.0, 2.0–2.36, 3.35–4.0 mm were allowed to melt in CaO–SiO2–Al2O3 molten slag, which were prepared by mixing CaCO3, SiO2 and Al2O3 reagent powders at different weight fractions. Results showed that the amount of CaO dissolved in the molten slag increased with increasing melting time, and its rate increased with a decrease in the amount of CaO in the slag. The dissolution rate of CaO was faster with CaO particle of smaller size at higher melting temperatures. The rate expression for the dissolution of CaO particles into the molten slag was derived on the assumption that the dissolution rate of a CaO particle is controlled by the mass transfer of CaO through a boundary layer of 2CaO·SiO2 which is produced around the surface of the CaO particle. Then, the rate of dissolution of CaO into the molten slag was evaluated by the apparent rate constant for CaO obtained. The apparent rate constant of the dissolution of CaO, k, was almost constant for the molten slag employed, of which the average k-value was 1.80×10−6 m/s for CaO particle sizes in the range of 0.3–0.355, 0.5–1.0, 2.0–2.36, and 3.35–4.0 mm. The time change in the ratio of CaO dissolved into the molten slag was estimated by calculation using the k-value thus obtained. As a result, the measured data were reasonably reproduced by the calculations in terms of the rate of CaO dissolution.
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