Multivariate analysis was applied to the polymerization data of a thermal expansion microcapsule to clarify the operating conditions affording the steadiest particle diameter control. As a result, among the factors controlling the particle diameter of a thermally expandable microcapsule, the amount of the dispersing agent, the stir power in the preliminary mixing tank and the curing tank, and the liquid physical properties prescribed for polymerization were incorporated into a statistical model. It was shown that, after a thermal expansion microcapsule is polymerized, the mean particle size can be reduced by increasing the amount of dispersing agent and the stir power of the preliminary mixing tank and the curing tank, which is a process factor. It was also shown that although the physical properties of the raw material influenced the liquid drop diameter immediately after passage through the geostationary type decentralization machine, the polymerization was controlled by the amount of dispersing agent and the stir power in the curing tank.
As sustainable development has become desirable in all process industries, biomass has attracted attention as a carbon-neutral energy source with a small environmental impact. The most common form of biomass energy in today's society is biodiesel fuel (BDF). BDF is made not only from virgin vegetable oil but also waste edible oil, which is troublesome to dispose of. BDF is also environmentally preferable to diesel fuel because of its lower discharge of sulfur oxides. Because of these merits, more widespread use of BDF is desirable. In Japan, several types of equipment for BDF production have been developed, and local governments, schools, nursing home and companies have purchased them to make BDF for use in their buses, trucks and official vehicles. However, the fact that these devices are not optimized based on mixing technology, not easy to operate and expensive has been a barrier to their more widespread adoption. In this work, experiments were conducted to develop equipment with higher performance in production of BDF than that on the market. The results showed that a rectangular vessel is more effective than the cylindrical one commonly used, allowing a marked decrease in mixing time, a reduction in equipment size and, thus, a reduction in equipment price. Based on these findings, novel equipment to produce BDF has been developed and placed on the market.
In applying backmixing model for liquid mixing characteristics of vertical stirred vessels with six multiple impellers and perforated-type partition plates, the effect of the opening ratio of the perforated-type partition plate and the stirring speed on the back flow rate and the exchange rate of liquid was experimentally investigated. The vessel diameter DT was 0.10 m and the impeller diameter Di was one-half of the vessel diameter DT. In the vertical stirred vessels with six multiple impellers, the relationship among the back flow rate f, the feed flow rate q and the exchange rate Q was established f=Q−q/2. The exchange rate Q increased in proportion to the stirring speed of impeller n and the opening ratio of a perforated-type partition plate Ar. When the agitated Reynolds number NRe is greater than 4×103, the value of the modified dimensionless exchange rate Q/(nDi3Ar) was almost constant at 0.20.
In the case of laminar mixing in stirred tank, the mixing pattern formed is determined by the streakline originating from the tip of the impeller, and with time its profile approximates the shape of the streakline. An accurate understanding of the configuration of the streakline is therefore important in analysis of the mixing mechanism. In chaotic flow field where global mixing occurs, the fluid trajectory tends to expand exponentially in a particular direction, and it is therefore difficult experimentally to visualize a streak as a “line” because the streak behaves as a “sheet” that has helical envelope. In the present study, we have developed a novel technique to visualize distinct streaklines in a three-dimensional flow field. In this technique, the expansion of streaks is suppressed by the surface tension of surfactant molecules in the tracer fluid, thus allowing the visualization of distinct streaklines generated from the tip of the impeller blade in a stirred tank. This streakline can exist stably and remain in the form of a line for a long time, and there is little leakage of colored component due to the effect of molecular diffusion.
Tubular hollow crystals of CaCO3were obtained by a novel synthesis process of dropping NaHCO3 solution into boiling CaCl2 solution under atmospheric pressure. Under the condition of [HCO3−]/[Ca2+]=2, the crystals had a simple aragonite structure. Tubular hollow crystals of BaCO3 were similarly obtained by using boiling BaCl2 solution. This novel process is expected to be widely applicable to synthesis of various tubular hollow crystals.
The optimal allocation of the internal heat exchange rate to the stages of an internally heat-integrated distillation column (HIDiC) was investigated as a fundamental study for developing a column of simpler structure. In the HIDiCs hitherto proposed, which consists of a double pipe or plate-fin type heat exchanger, the internal heat exchange rate at each column section is determined by the temperature difference profile between the rectifying section and the stripping section. The effect of internal heat integration on the reduction of reboiler heat load depends strongly on the location of heat exchange stages. To quantify this relationship, the heat exchange between a rectifying stage and a stripping stage is first considered fot the constant number of stages and constant compressor power, and the reduction of reboiler heat load by the heat integration was calculated. The result showed that there exists an optimal combination of the rectifying stage and the stripping stage that minimizes the reboiler heat load. Next, the optimal allocation of heat exchange rate among multiple stages was derived for a fixed total heat transfer area. The result showed that the reboiler load can drastically be reduced by assigning the heat exchange rate to a few stages based on the “energy-saving indices” obtained from the simulation results of single heat exchange between a rectifying stage and a stripping stage. Furthermore, the optimization results showed that the assignment of the heat exchange rate to the stages based on the “energy-saving indices” agreed closely with that obtained by rigorous optimization.
Moisture absorption by porous materials with mesopores and micropores is generally evaluated by measurement of the water adsorption isotherm and analysis of the pore distribution by the nitrogen adsorption method using completely dry samples. In practical use, however, the adsorbent contains some water depending on the environmental conditions. To evaluate the pore distribution accompanied by the water adsorption, the nitrogen adsorption method was modified by using a frozen sample, which was dipped into liquid nitrogen after the water adsorption had reached equilibrium. Water adsorption was found to proceed from the smaller to the larger pores as relative humidity increased. The pore distribution at the relative humidity above which pores were completely occupied by absorbed water was shown visually on a histogram.
Supercritical fluid extraction of template agents, CTAH (Cetylrimethylammonium hydroxide) and EPE (EO20–PO70–EO20) from mesoporous silica was carried out at 80°C, 8 to 14 MPa and extraction time of 1 to 7 h. The time evolution of templates showed that CTAH was removed after EPE. Among the three alcohols, including methanol, ethanol and 1-propanol as entrainers, methanol was the most efficient solvent that gave 95% recovery of CTAH. This seems to be caused by molecular size and polarity of entrainer. Supercritical carbon dioxide-entrainer method showed high recovery of template agents compared to organic solvent methods. Pore size of silica affected pressure dependence of template recovery, which indicated differences in interaction between pore wall and template. Optimization of extraction condition was achieved by selecting suitable pressure and entrainer for providing better balance of entrainer penetration and extraction power.
The concentration profiles in an inclined continuous thickener were theoretically analyzed by use of vertical and inclined solid flux curves, which were obtained from vertical and inclined batch settling experiments with different calcium carbonates slurries. The theoretical analysis was developed for inclined continuous thickener at a critical-loaded operation and in two typical underloaded operations. The concentration profiles predicted by this analysis agreed with experimental results obtained using the calcium carbonate slurries. Consequently, the settling in an inclined continuous thickener of angle of inclination θ and distance between inclined side plates B can be explained by the model proposed in this study, in which a wedge-shaped layer of clear liquid develops at the upper surface of the inclined plate. The concentration profiles for a thickener of any arbitrary vertical height can be determined graphically.
Ion exchange behavior of organic anions of differing sizes and structures, including carbonate ions and dodecyl sulfate ions, with Mg/Al layered double hydroxide (LDH) was quantitatively investigated. The effect of the type and amount of organic anions taken up on the structure and surface properties of the LDH was also examined. Ion exchange isotherms of the Langmuir type were obtained for the uptake of C6H5COO−, C2O42−, CH2(COO)22− and C6H4(COO)22− in the LDH. With these anions, uptake reached 71–88% of the theoretical ion exchange capacity of the LDH. The differences in uptake amount are thought to derive from differences in valency and ion size among them. The ion exchange isotherm of LDH for C12H25OSO3− was also of the Langmuir type, and the uptake amount almost equaled the theoretical ion exchange capacity. The interlayer distance of LDH was found to vary with uptake of organic anions, corresponding to the orientation of anions in the LDH structure. The contact angle of LDH containing dicarbonate ions with water was only slightly larger than that of NO3− type LDH, the starting material before anion exchange. This means that the LDH surface is hydrophilic after the uptake of dicarbonate ions. Conversely, C12H25OSO3− gave the largest contact angle, that is, the most hydrophobic surface among the organic anions used.
In the factory, OSHMS (Occupational Safety and Health Management System) is often introduced to eliminate incidents and accidents in routine human work. In this system, the people who carry out production identify hazards that accompany daily activity in the factory, assess the risks involved in human work and, from the results of risk assessment, try to reduce these risks. Nevertheless, incidents and accidents continue to occur, one reason being oversight in hazard identification. This paper proposes a method to reduce the oversight of hazards during risk assessment in the plant. Based on a description of operational procedure by experienced production workers, the following three-step method is followed. 1) Experienced production workers identify potential hazards in the operational procedure based on their own knowledge; 2) by contextual analysis of the description, the production workers examine the possibility of incident or accident and identify hazards in the process from operation to incident or accident; and 3) hazards are identified from accidents and incidents occurring real operations or the imaginary incident envisaged by the production workers.
Key performance indicators (KPIs) are widely used as evaluation indices of plant alarm systems in chemical industries. However, it has been pointed out that KPIs are not effective for evaluation of a system's qualitative characteristics. In this study, we propose a novel method for evaluating the alarm system performance from the viewpoints of relevance, uniqueness, and timeliness. This method does not depend on the knowledge and experience of engineers. First, similarities between all event pairs are first calculated by event correlation analysis of the plant operation log data. Then, the three characteristics are evaluated according to similarities and time lags between all combinations of alarm and operation events. The proposed method was applied to the plant operation log data of an azeotropic distillation column. The evaluation results were helpful for finding weak points in the objective plant alarm system. Using the proposed method, we can effectively improve the qualitative characteristics of alarm systems in chemical industries.
IgG–Fc binding peptide which functions as ligand for IgG purification was screened by peptide array. When sera from milk allergy patient were applied to the milk protein-explosive peptide array, some 16-mer binding peptides were found from both positive sera and negative sera. When cellulose membrane type peptide array was used for identification of binding peptide sequence, octamer peptide, LLRLKKYK, was found to strongly bind to mouse IgG. Since the octamer peptide weakly bound with IgA, it was suggested that the peptide is an IgG–Fc specific binding peptide. Furthermore, it was also suggested that the IgG-Fc binding peptide is available for purification of IgG–Fc.
3-Mercapto-1-propane sodium sulfonate (MPS), diaryl-dimethyl-ammonium-chloride (DDAC) and Cl2 were used as additives for copper foils electrodeposition. First, we made copper foils with several combinations of additives, and evaluated surface smoothness, surface morphology and crystallographic structure by laser microscopy, field emission scanning electron microscopy and X-ray diffraction measurement. We found that the copper foil prepared with a bath containing all kinds of additives has the smoothest surface, the finest size in the crystal grains and the strong (111) orientation. Second, we examined the behavior of the additives by the Quarts Crystal Microbalance (QCM) measurement and the electrochemical measurement. Due to the weight increase by the QCM with electrolytes containing MPS and DDAC. Inhibitation effect was also observed by the electrochemical measurements with electrolytes containing DDAC.
The detection of dioxins in municipal waste incineration fly ash in 1983 brought the problem of dioxins to the attention of Japanese society, but at the same time, the capacity of final disposal sites was becoming increasingly restricted. In 2002 and 2003, Musashino City conducted mixed incineration tests of plastic and other burnable refuse, and based on the measured dioxin emissions, it started to collect the plastic as burnable refuse for incineration from October 2003. Here, the change in dioxins concentrations since the start of mixed incineration is reported, together with data for the period from 1996 until the introduction of mixed incineration. Following the replacement of electric precipitators with bag-filters in 1999–2000, though the concentration of exhaust dioxins at the dust collector exit was drastically decreased, that at the stack remained higher than that at the dust collector exit. But it gradually decreased to 0.011 ng–TEQ/m3N (oxygen concentration 12% basis, average for three incinerators) in 2009, which is close to that at the dust collector exit and almost two orders of magnitude lower than the 0.97 ng–TEQ/m3N in 2000, when plastic was collected as incombustible refuse. These findings suggest that dioxins had earlier accumulated in high concentration in a stagnant zone in the flue gas duct from the dust collector exit to the stack and were gradually released after the start of mixed incineration.
Wastewater containing heavy metal ions and organic compounds from metal finishing process was treated by coagulation and filtration after pH adjustment. The treated water containing organic matter and salts was distilled under reduced pressure. The distilled water was deionized applying double-pass RO system after UF filtration. The permeated water of the first RO pass became the feed for second RO pass. The concentrated water of the second RO pass returned for UF filtered water tank. The permeated water was oxidized by ozone combined with ultraviolet (UV) radiation. The advantage of this combined process (RO treatment and ozone oxidation) is that there is no production of salts which should be removed before the treated water reused. The electric conductivity of the effluent from the UV-ozone process was less than 10 μS/cm. This purified water could be reused as cooling water in the cooling tower facilities. Based on these experiments, we devised a practical recycling system by which water in contaminated wastewater can be reused as purified water on an industrial scale at a chemical processing factory. These results suggest that this process does not cause any secondary pollution, and has high possibility of being practically applied for recycling water from metal finishing process.