In this study, solid–liquid equilibrium measurements in ternary system SrBr2–MgBr2–H2O at (298 and 323) K are conducted using the isothermal dissolution equilibrium method. The mass fraction of every component of the equilibrium liquid phase in the system is determined at (298 and 323) K. Based on the experimental results, the phase diagrams and density-composition diagrams are plotted. Results show that no double salt or solid solution is formed in the system SrBr2–MgBr2–H2O at (298 and 323) K. The ternary system SrBr2–MgBr2–H2O at (298 and 323) K has one invariant point, two univariant curves, and there are two solid–liquid two-phase areas that correspond to strontium bromide hexahydrate (SrBr2·6H2O) and magnesium bromide hexahydrate (MgBr2·6H2O).
The present study investigates electrochemical ozone dissolved water production (EOP) without O3 gas emission using a new EOP system and external gas–liquid mixers. The target gas–phase O3 formation rate was set to less than 0.01 mL/min. Regression analysis was performed using test matrix data obtained from EOP experiments. The regression analysis of the current efficiency of gas–phase O3 formation Φg [%] using the anolyte flow rate V [L/min], current density I [A/cm2], and cross term I/V gave a high determination coefficient of R2=0.9965. Ozone dissolved water with an O3 concentration higher than 2 mg/L was obtained without using external mixers at the rates of 2.2–2.7 L/min. The O3 concentration was doubled to 4 mg/L by the use of external mixers. The mixers can efficiently increase the ratio of dissolved ozone to total produced ozone in anolyte and decrease the O3 gas formation rate to one-tenth of that without mixers. The bypass operation experiment revealed that ozone dissolved water with an O3 concentration higher than 2 mg/L can be produced at a rate of 6 L/min. The concentration of O3 gas emitted into a closed space exceeded the regulation value of 0.1 mL/m3. However, that into an open space was lower than the regulation value when the dissolved O3 concentration was less than 2.7 mg/L.
Disodium-4-nitro-2-sulfobenzoate (NSBNa2) and 4-amino-2-sulfo-benzoic acid (ASB) are important intermediates in fine chemical industries. In this study, the solubilities of NSBNa2 and ASB in sulfuric acid aqueous solutions were measured to provide important data for their production and separation. The measurement was performed at temperatures from 277.1 to 347.9 K under atmospheric pressure by a dynamic method. The solubilities of NSBNa2 and ASB were found to be increased with temperature at fixed concentrations of sulfuric acid. While, their solubilities decreased with the concentration increasing of sulfuric acid. The experimental data were then correlated with the modified Apelblat model, and the root-mean-square deviations ranged from 0.77 to 1.26 K. The calculated results show good agreement with the experimental data. Based on the solubility data, improved separation processes for NSBNa2 and ASB were also proposed for higher recycle yields.
The velocity field in an opposed jet mixer was studied by using Phase Doppler Anemometry (PDA). In this study, the effect of operating conditions such as nozzle separations and inner nozzle diameters was investigated to study the changes in characteristic chaotic parameters (correlation dimension, Kolmogorov entropy, and largest Lyapunov exponent). The velocity field possessed chaotic characteristics, in which the value of the correlation dimension ranged from 2.34 to 7.52. The characteristic chaotic parameters increased and then decreased as the nozzle distance increased. This reflected the micro-mixing efficiency of the mixer. The efficiency of the mixer improved as the values of the chaotic characteristic parameters increased. Thus, the optimal conditions of microcosmic mixture were obtained. Therefore, a suitable nozzle distance, or decreasing nozzle diameter, is advantageous for the improvement of a mixer’s micro-mixing efficiency.
The effects of the location of the baffle on mixing pattern in laminar mixing is shown in this study. Decolorization experiments were conducted based on an oxidation-reduction reaction to investigate the mixing pattern. As a result, isolated mixing regions (IMR) like doughnut-rings were eliminated by setting the baffle at the optimum location, where the baffle and the IMR crossed each other. The velocity profile was measured by using particle image velocimetry under the baffle condition. The IMR was dissipated due to making unstable circulation flow when the baffle was placed with clearance between the baffle and the wall. It was shown that using conventional mixing equipment can eliminate the IMR easily by placing the baffle with clearance.
The fluid dynamic behavior of a drop during a freely rising process is investigated using the volume of fluid (VOF) method in conjunction with the continuum surface force (CSF) model. A two-dimensional computational fluid dynamic model is used to describe the mass and momentum transport. Measurements of the rise velocity and the aspect ratio for the toluene/water system without mass transfer for diameters ranging from 3–5 mm were obtained using a high-speed camera. The simulation results showed excellent agreement with the experimental data. The effects of the physical properties on the drop rising velocities, aspect ratios, and coalescence behavior of two coaxial drops are also simulated and analyzed. The simulation results show that the laws for the variation of the fluid dynamic behavior with the physical properties of a system provide important guidelines for the design and operation in a liquid–liquid column.
Profiles of local evaporation rate from a liquid surface formed in a cylindrical hole are numerically estimated using the finite element method. The droplet is so small that the evaporation can be considered as a steady-state process and the vapor concentration distribution above the droplet satisfies the diffusion equation. Generally, the local evaporation rate of a droplet is small at the center, but becomes stronger near the contact line on the flat substrate. In a cylindrical hole, the local evaporation rate near the contact line is prevented by the vertical sidewall especially for a high sidewall. The effect of bank height and the contact angle on the local evaporation rates and total evaporation rate are also discussed.
This study focuses on developing a nonlinear fault identification approach whose goal is to find the fault variables after a fault is detected. For nonlinear processes monitoring, it is a challenging problem to identify the fault variables since the monitoring statistics are usually an implicit function with respect to the process variables. In such a case, a traditional contribution plot-based fault identification approach that decomposes the monitoring statistics into the summation of variable contributions will be invalid. To solve the issue mentioned above, in this paper, a new nonlinear processes monitoring technique including fault detection and identification approaches is proposed based on kernel independent component analysis (KICA). On the basis of KICA, two monitoring statistics are defined for fault detection, and the contribution of each variable to the monitoring statistics is defined for fault variable identification. After a fault is detected, one can use the proposed fault variable identification method to judge which variable has the largest impact on the abnormal event and demonstrate identification. At last, the pulverized coal fired boiler process (PCFBP) is taken to evaluate the validity and effectiveness of the proposed approaches. Experiment results show that the proposed methods have satisfactory monitoring performance in the application to PCFBP.
In the present study, the influence of different particle aggregation models on the fly ash particle aggregation process of a turbulence aggregation device has been studied. The influence of an interparticle repulsive potential energy barrier, Umax, on the rate of aggregation was considered, and capture efficiency, f (α), was introduced to correct the ideal turbulence aggregation kernel. The simulation results of an ideal turbulence aggregation model and a corrected turbulence aggregation model were compared to the experimental results, and showed that the error between the ideal turbulence aggregation model and experimental results was approximately 8%; whereas, the error between the corrected turbulence aggregation model and experimental results was only 3%. Brownian aggregation cannot be ignored in the turbulence aggregation of the particles less than 2 µm in diameter. The coupled corrected turbulence aggregation and Brownian aggregation model coincided well with the experimental results.
Since there are many factors which influence the process of flocculation by polymer flocculant, the scientific understanding of the flocculation mechanism is still under discussion. We have proposed a simple bridging model which expresses flocculation under various additive manners of the flocculant and enables the understanding of qualitative trends of the flocculation system. In the present study, from the simulated results based on the model and experimental data, we obtained the following knowledge: 1) the intermittent addition of polymer flocculant gives better and reproducible turbidity removal; 2) the optimum dosage, which results in maximum turbidity removal in a given manner of addition, increases as the number of doses under the intermittent addition increases; 3) at a given amount of primary particles, the reproducibility at the optimum dosage of the 1-time dose is the worst among all results, irrespective of the additive manner. It could, therefore, be concluded that all these findings are originating from the difference of probability of bridging formation among particles under various additive manners.
On parallel computation based on the domain partitioning, the efficient method for communication between partitioned subdomains was investigated. In the method, the communication table was generated by dividing a communication process into multi-stage, limiting each core assigned with each subdomain to communicate once at each stage, and determining the core with more neighboring subdomains in priority to another to communicate until no more cores were available at each stage. The parallel computation of fluid flow based on the finite volume method was performed and it was found that the parallel computation with the proposed communication table could successfully reduce computational time for communication compared with that with the conventional one with an increase in the number of cores used.
In order to decompose trace amounts of nitrite in drinking water under mild conditions, a fixed-bed filtering system that used structural catalysts was employed to filter recycled aqueous nitrite. High performance and continuous mass processing are generally accepted as requirements to catalyze the decomposition of aqueous nitrite. However, the use of a fixed-bed operation when recycling aqueous nitrite with palladium catalyst systems could result in either negligible activity when using a carbon monolith impregnated with Pd, or could stop the flow by enhancing the pressure drop when using non-porous alumina spheres coated with Pd/C or structural catalysts consisting of a polyurethane sponge skeleton impregnated with Pd. In the present paper, a Si/SiC ceramic filter was employed as a structural support to prevent pressure drop. When palladium was loaded onto the surface of the filter via electroless plating, continuous flow suitably continued, and the conversion of nitrite was 45% after 60 min. In contrast, when palladium was loaded after the coating of the filter with alumina, complete decomposition was achieved after 60 min under conditions corresponding to those used for the former system. X-ray diffraction, an N2 adsorption-desorption measurement, scanning-electron microscopy, and energy-dispersive X-ray spectroscopy analyses revealed that a higher dispersion of palladium on the latter structural catalyst resulted in the greatest level of activity for the reductive decomposition of aqueous nitrite.
In this paper, a novel probabilistic kernel partial least squares (PKPLS) method and the corresponding process-monitoring method are proposed. The contributions are as follows: (1) PKPLS defines an appropriate probability model from a probabilistic viewpoint. The probabilistic characteristics and the relationship between input variables and output variables are analyzed using Gaussian latent variables. (2) PKPLS solves the nonlinear issue in process monitoring and addresses the problem of missing values, especially in big data processing. (3) Based on the data distribution structure, the monitoring model is established using PKPLS, which overcomes the limitation of the lack of a relevant probability density or generation model in traditional methods. (4) We qualitatively analyze the problem of parameter determination. A Bayesian rule and expectation–maximization algorithm are developed to estimate the parameters of the probabilistic model. The PKPLS algorithm is applied to process monitoring. Numerical examples and the Tennessee Eastman process are used to evaluate the performance of the PKPLS method. Extensive experimental results verify the satisfactory performance of the proposed new approach.
Improving boiler thermal efficiency plays a very important role in the economic development of power plants. In order to implement a real-time improvement in the boiler thermal efficiency, a precise and rapid online model of the thermal efficiency is required. The present paper presents an effective machine learning method called the Online Least Square Fast Learning Network (OLSFLN) to build a prediction model for 300 MW coal-fired boiler thermal efficiency. Experimental results demonstrate that the proposed OLSFLN could predict the boiler thermal efficiency with high accuracy and outperform in learning ability, generalization ability and repeatability under various boiler operating conditions than other state-of-the-art algorithms.
A simple and easy method for the simultaneous monitoring of colony shape and ammonia productivity of swarming bacteria such as Proteus mirabilis should become increasingly important for the characterization of the bacteria. A contactless mapping method of ammonia concentration produced by Proteus mirabilis colony is proposed using an array of pH indicator solution and a digital still camera, by using a PC display as a backlight. Brightness of the indicator solution was quantified from the captured image using image processing software. At the same time, fine structures in the colony were observed due to the diffraction of the display’s transmitted light pattern. In 5 min, the ammonia productivity difference from different concentric circles was identified. Bacteria cell density of different regions of the concentric colony pattern on the agar surface was measured, and the effect of the density on the ammonia productivity was discussed.
The crystallization mechanism of amino acid derivative t-butoxycarbonyl-L-asparagine (Boc-Asn) was investigated. NMR spectroscopy was used to observe the behavior of Boc-Asn molecules in under- and supersaturated solution. Nuclear Overhauser Effect (NOE) NMR measurements were performed to provide information concerning the intra- or intermolecular access of a particular hydrogen atom to other hydrogen atoms in solution. We compared the interactions identified by NOE measurements for under- and supersaturated solutions of Boc-Asn with those in the crystal, as determined by X-ray analysis. According to the X-ray analysis, intramolecular NOE should not be observed, but intermolecular NOE might be observed between the methyl protons of the t-butoxycarbonyl group and the protons belonging to other functional groups. The time course of the NOE intensity was followed for three solutions with different saturation ratios S (=concentration of solute/solubility). For undersaturated and nearly saturated conditions (S=0.8 and 1.12 at 0°C), the NOE intensity did not change for at least for 250 h. However, for the supersaturated solution (S=1.62 at 10°C), the NOE intensity increased suddenly and rapidly after about 120 h, and no crystals were observed during the NOE measurements. As the observed NOEs agreed with those expected from the arrangement of molecules in the crystal, it was suggested that Boc-Asn molecules aggregated after about 120 h with the same structure as that in the crystal. In addition to the behavior of the Boc-Asn solution before nucleation, we also investigated the effect of aggregation on the crystallization process. Solutions that were preincubated at 10°C for various periods were further cooled and crystallized at −30°C. It was found that when the solution was preincubated under the supersaturated condition for a long time before crystallization, nucleation was enhanced, and consequently, the crystal size distribution became homogeneous.
A series of experimental simulations were conducted to study the effects of supercritical CO2–water on the dissolution of illite under different burial depth conditions (1,000, 1,500, and 2,000 m). In addition, the mineral composition, crystalline structure, and fluid composition were analyzed. The results indicate that illite dissolution is controlled by solid–liquid diffusion and surface chemical reactions. The elements that undergo metathesis are more easily released than the original fixed elements in the crystal lattice, and the interlayer cations are released more easily than octahedral and tetrahedral ions. At deeper burial depths, the percentages of dissolved ions increase. After the reaction, the crystallinity of illite decreases, the proportion of amorphous material increases, and the morphology changes with damage to the lattice. Meanwhile, the dissolution of illite can contribute to the generation of diaspore and siderite.
Hydrogen permeable membranes composed of palladium-transition metal binary alloy were prepared. The palladium membrane alloyed with the transition metals of Group 3A that was able to dissolve more than 8 at% in palladium, silver and gold, showed higher hydrogen permeability compared to that of a pure palladium membrane. In particular, the hydrogen permeability of a palladium–holmium membrane was found to be the highest in this study, and two times higher than that of palladium–silver membrane.