Virtual sensing technology is crucial for high product quality and productivity in any industry. This review aims to clarify the trend of research and application of virtual sensing technology in process industries. After a brief survey, practical issues are clarified by introducing recent questionnaire survey results: 1) changes in process characteristics and operating conditions, 2) individual difference of equipment, and 3) reliability of soft-sensors. Since input variable selection is crucial for high estimation performance, conventional methods and new group-wise variable selection methods are introduced, and the usefulness of the group-wise variable selection methods is demonstrated through industrial case studies. Just-in-time (JIT) modeling is dealt with as a promising virtual sensing technology that can cope with changes in process characteristics as well as nonlinearity. Recent developments leading to successful industrial applications are introduced: correlation-based JIT (CoJIT) modeling and locally weighted regression (LWR), especially LW-PLS, with modified similarity measures. Manufacturing processes in different industries are quite different in appearance, but they have very similar problems from the viewpoint of quality issue. There remain practical issues requiring further research efforts to realize high-performance, maintenance-free virtual sensing technology.

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This article provides an overview of polymers reinforced with impermeable flakes that have long been used in the chemical process industry for protecting metal and concrete structures against corrosion. Reviewing the function of impermeable flakes in the anticorrosion performance of polymer composite coatings and linings could serve as a guiding perspective for future studies and extended applications of current polymer-layered silicate nanocomposites in this field. This brief article describes the theory behind barrier improvement in polymers by flake reinforcement, describes ways of evaluating the anticorrosive properties of flake filled polymers reported in recent studies, and reviews some existing applications of flake filled polymers for corrosion protection in the field of chemical processing.

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The present study experimentally investigates gas–liquid two-phase flow in a Taylor vortex flow device with a ribbed rotor. In this device, a pair of counter-rotating vortices appears between two ribs. This device immobilizes and stabilizes vortices even in gas–liquid two-phase flow. Mean residence time of gas obtained from gas hold-up largely increased when the ribbed rotor was employed. It is found that more bubbles were captured when wider ribs were employed. Furthermore, an increase in rib width can intense the downward flow generated under the ribs owing to the high centrifugal force. The mean diameter of bubbles also increases with rotational speed of rotor. It is, therefore, found that the interfacial area between gas and liquid has a peak value against the rotational number.

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Escapable gas holdups and volumetric oxygen transfer coefficients were measured at several concentrations of xanthan aqueous solutions in four standard bubble columns in which a slug bubble flow was observed. The experimental escapable gas holdups were well estimated by the semi-theoretical Nicklin’s equation modified for non-Newtonian xanthan aqueous solutions having yield stress. Although the escapable gas holdups increased with decreasing column diameter and increasing superficial gas velocity, it was hardly influenced by the concentration or apparent viscosity of the xanthan aqueous solutions. The volumetric oxygen transfer coefficient increased with decreasing yield stress of the liquid, increasing diffusion coefficient, decreasing column diameter, and increasing gas holdup. By correlating all experimental results, an empirical equation was proposed. To design a more efficient bioreactor, the partitioning perforated plate which is used in columns larger than those used by Terasaka and Shibata, was inserted in the standard bubble columns. The gas holdup and volumetric oxygen transfer coefficient in the partitioned bubble columns were measured and were compared with those in the standard bubble columns. The volumetric oxygen transfer coefficients in the partitioned bubble columns became larger than those in the standard bubble columns at a fixed superficial gas velocity, even for large column diameters. Therefore, in this study, partitioned-bubble column-bioreactors were developed for more suitable production of xanthan gum.

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A mechanism is proposed to explain the generation of convection in vibrating powder beds based on powder mechanics. Convection induced in the vibrating powder beds was observed and the influences of the vibration amplitude and frequency on the convection were investigated experimentally. The flow behavior of the vibrating powder beds was simulated using the discrete element method (DEM) to obtain the state variables of convection, such as bulk density and velocity. A mechanical model of convection is proposed based on the microscopic observation of the flow behavior of particles and formation of convection cells in the bed by DEM simulation. Triangular and V-shaped compressed particle zones of particles were formed in alternating fashion in the vibrating powder bed, and the generation of these compressed zones repeated every two vibration cycles leads to particle convection in the bed. The number of convective rolls in the vibrating powder bed increases with an increase in the centrifugal effect. The number of isosceles-triangle-shaped compressed zones formed at the bottom of the container increased with an increase in the centrifugal effect, leading to an increase in the number of convective rolls in the vibrating powder bed.

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Mongolian natural zeolites, whose base components were clinoptilolite, mordenite, and chabazite, were characterized in terms of parameters such as their elemental contents, cation exchange capacities, among others. Since the molar ratios of aluminum to silicon for the Mongolian natural zeolites used in this study were lower than those of pure zeolites, it was surmised that the natural zeolite samples contained substantial amounts of impurities. The cation exchange capacities of the natural zeolite samples were dependent on their aluminum content and were greater for the zeolites with higher aluminum contents. Batch equilibrium adsorptions of heavy metals such as copper, zinc, and manganese from model wastewater using the Mongolian natural zeolites were also carried out. The natural zeolites could adsorb and remove the heavy metals from the aqueous model solutions and also helped to adjust pH of the solutions to appropriate levels. The precipitation of the heavy metals in the form of their hydroxides owing to the addition of natural zeolite also aided the removal of the metals. The amounts of the heavy metals adsorbed at saturation as estimated by the Langmuir equation were almost the same for all the metals. In addition, these amounts increased with the pH of the feed solutions as well as with cation exchange capacities of the natural zeolites. Finally, it was found that the adsorption coefficient in the Langmuir equation was correlated with the hydrated ionic radii of the heavy metals being investigated for removal.

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A crystallization process has been under development for the recovery of U as uranyl nitrate hexahydrate (UNH) crystals. Two experiments, solubility of Cs₂Pu(NO₃)₆ and U crystallization, were performed to evaluate the influence of HNO₃ concentration in solution on the precipitation behavior of Cs₂Pu(NO₃)₆. The solubility of Cs₂Pu(NO₃)₆ in a uranyl nitrate solution has been found to decrease with increasing HNO₃ concentration in the solution. These experimental results imply that Cs₂Pu(NO₃)₆ is readily formed in high HNO₃ concentration solutions. Based on the solubility of Cs₂Pu(NO₃)₆ in uranyl nitrate solutions, U crystallization experiments were performed with a range of HNO₃ concentrations in the feed solution. At an HNO₃ concentration of 4.5 mol/dm³ in the feed solution, the HNO₃ concentration of the mother liquor was 6.5 mol/dm³. The decontamination factor (DF) of Cs for the UNH crystals was 8.61 after crystal washing. In this case, Cs₂Pu(NO₃)₆ precipitated upon cooling of the feed solution and was not separated from the UNH crystals after crystal washing. On the other hand, the DF of Cs was 174 after the UNH crystals were washed when the HNO₃ concentration in the feed solution was 3.2 mol/dm³. With a lower HNO₃ concentration in the feed solution, nearly all Cs remained in the mother liquor during the U crystallization process. Therefore, to suppress Cs₂Pu(NO₃)₆ precipitation, a lower HNO₃ concentration must be maintained in the feed solution.

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This study is to evaluate the radiation properties of coal char and ash particles. Char in coal-firing and gasification processes exists in the form of heterogeneous composite particles consisting of nano-order fine particles made mainly of soot and micron-order particles of carbon and ash components. The radiation properties are discussed in terms of apparent extinction efficiency determined from spectra of transmissivity of a particle-liquid paraffin wax dispersion film as an independent parameter of particle dispersion density. Extinction efficiency measured directly from the original char gives an unacceptably great magnitude. However, if the original char was classified into a narrow particle size distribution by pretreatment with a wet method, the extinction efficiency of each particle showed a reasonable magnitude and successfully deduced an extinction coefficient of the original char dispersion with a certain content from combining that of each particle accounting for the fraction. The effect of carbon content in char particle excluding soot on extinction efficiency could also be correlated empirically by a simple function using the properties of carbon-free ash burnt out and ash-free carbon treated by hydrofluoric acid. Additionally, the value of apparent extinction efficiency measured from transmissivity of ash dispersion was compared with the properties estimated by applying the known refractive index into Mie’s theory, and noted to be closer to rather absorption efficiency than the extinction efficiency analyzed theoretically, although scattering albedo was as large as over 0.9. This fact may result in that a strong forward scattering pointed out in a previous work was reasonable and the ash particle cloud can be assumed as an absorbing-emitting medium having the properties obtained here, ignoring the effect of scattering at least.

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In this paper, we suggest a clean power generation process that integrates molten carbonate fuel cells (MCFC) and coal-based synthetic natural gas (SNG) production. The integrated approach achieves an increase in overall process efficiency due to recycling of the exhaust gas from the fuel cell as well as carbon dioxide generated from the SNG production process. It also reduces environmental impact of coal-based power generation, delivering zero NO_x, SO_x, and CO₂ emissions. An evident economic advantage of the proposed process is that, compared to natural gas, SNG is a less expensive and more stable source of methane for MCFCs. Moreover, it should be noted that many countries create renewable energy support policies for fuel cells owing to their high efficiency and environmental friendliness. The techno-economic and environmental competencies of the proposed process are more significant in comparison with other advanced coal-based power generation processes, i.e., integrated gasification combined cycle (IGCC) and pulverized coal (PC) process. This work will significantly contribute to the advancement of the power generation process.

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This work aims to deposit ZrO₂ thin films on type 316L-stainless steel substrates by DC unbalanced magnetron sputtering under various sputtering powers in the range of 120–300 W. The target-to-substrate distance was adjusted to 100 mm and the deposition time was 120 min. The XRD results demonstrate that the sputtered ZrO₂ is a monoclinic phase. The AFM analysis reveals that the grain size, root mean square surface roughness and thickness of ZrO₂ films increase with increasing sputtering power. The deposited substrates were soaked in a simulated body fluid (SBF) with ion concentrations near human blood plasma to examine the biocompatibility properties on the surface though in vitro study. The XRD, FT-IR, and SEM results show correspondingly that all ZrO₂ surfaces were covered with apatite after 7 d of immersion in SBF. The conditions of preparing films at low sputtering power with smaller grain size and larger number of grain boundaries per unit length are considered to be the favorable conditions for apatite growth on ZrO₂ films owing to the large specific area.

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In this paper, an exergy analysis and a calculation method for a self-heat recuperative thermal process are described. Self-heat recuperation technology has recently been developed and has the characteristics whereby total process heat can be recirculated within the process, leading to a marked reduction in energy consumption. Although this technology can achieve perfect heat circulation in the process, the minimum energy required for the thermal process has not previously been described. According to both the theoretical and graphical analyses in this paper, self-heat recuperative thermal processes can achieve energy requirements close to the energy required for heat transfer from an exergy point of view. In addition, the simple calculation method for the minimum energy required for heat transfer was derived to be fixed as a target value of heat recovery technology. Thus, this technology supports process intensification and is promising for industry to examine the energy saving potential when designing a thermal process.

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