This paper describes the mission of chemical engineering in Japan and our increasing role in global issues of a rapidly changing world. Attention is devoted to the philosophy of chemical engineering for meeting the needs of the 21st century world, and to the activities and plans of the Society of Chemical Engineers, Japan (SCEJ) including its cooperative contributions to government policy on science and technology. New initiatives in research and education being promoted by the Japan Chemical Innovation Institute (JCII) and the Japan Accreditation Board for Engineering Education (JABEE), respectively, are also discussed.
The present paper shows experimental results on physical methods for supercooling relaxation of erythritol as a phase change material. Solidification behavior of erythritol melt was observed under the experimental conditions using the following 3 energy loadings: 1) ultrasonic irradiation, 2) stirring with seeding, and 3) agitation by bubbling. The obtained results have shown that supercooling relaxation of erythritol during its solidification is possible using any of the 3 cases for choosing energy loading, and that ultrasonic irradiation is most effective among the 3 cases. The effectiveness of ultrasonic irradiation was found to be dependent on ultrasonic power and on the melt's temperature at which irradiation was initiated. In the case of stirring, the relaxation effect was improved with a small amount of crystals seeded at about its melting temperature. Effective relaxation was also obtained by agitating erythritol melt by bubbling of N2 gas at room temperature compared with pre-heated gas.
Flow mixing in the recirculation zone of a backward-facing step flow (free stream velocity, Uo = 10 m/s, and step height, H = 20 mm) with gas injection is visualized by laser sheet imaging, based on the Miescattering concept. Two types of imaging have been done. Instantaneous visualization was done by using an Nd-Yag pulse laser. The continuous visualization, on the other hand, was done by using argon ion laser and a high-speed video camera to discuss the continuous motion of mixing. The study focuses on the effects of the specific momentum ratio (I = 0.04, 0.1 and 0.3) and the location of injection of nitrogen gas from a two-dimensional slot port (lf/H = 2 and 4) on the dynamic nature of the injected gas trajectory and gas distribution in the recirculation zone. The result shows that with higher specific momentum ratio, in case of the injection at near step (lf/H = 2), the injected gas distributes more toward upstream since the fluid dynamics restriction is less due to a lower recirculating flow velocity. Meanwhile, in case of injection near the reattachment point (lf/H = 4), the injected jet, which penetrates the flow field deeply, is deflected by the free stream so that the gas distributes more toward the downstream region. In both cases, the mean normalized luminosity in the region where the gas distributes more is no less than 1.6 times that in the region where it distributes less. Mixing is more rapid and intense in case of injection near the reattachment point due to higher turbulence. Furthermore, two frequency modes in the motion of the injected gas jet can be observed. The lower frequency mode associated with the shortening-lengthening of the recirculation zone (flapping) is not affected, whilst the higher one associated with the interaction of vortical motion of the flow field and the injected jet flow is influenced by the specific momentum ratio of injection.
Prediction of the maximum packing volume fraction with non-spherical particles has been one of the important problems in powder technology. The sphericity depending on the particle diameter was measured by means of an image processing instrument. An algorithm to predict the maximum packing volume fraction with non-spherical particles is proposed. The maximum packing volume fraction was used to predict the slurry viscosity under well dispersed conditions. For this purpose, Simha's cell model was applied for concentrated slurry with wide particle size distribution. Also, Usui's model developed for aggregative slurries was applied to predict the non-Newtonian viscosity of dense fly ash-water slurry. It was certified that the maximum packing volume fraction for non-spherical particles can be successfully used to predict slurry viscosity, and this means indirectly the maximum packing volume fraction determined in this study is reasonable.
Experiments were performed in mechanically agitated contactors with 6 (flat) blade turbine impellers, to study the effect of various operating parameters on minimum/critical speed required for complete suspension in two-phase (liquid-solid) as well as three-phase (liquid-solid-gas) systems. Based on 1212 experimental measurements, a unified empirical correlation is proposed, for the estimation of minimum impeller speed for solid suspension in both two-phase and three-phase systems in terms of fundamental, operational and geometrical variables.
A continuous-flow method of chemical vapor deposition of tetramethoxysilane on γ-alumina was developed for industrial utilization of silica monolayer solid-acid catalyst. The flow method caused relatively heterogeneous coverage of silicon compared to the static method; higher coverage by silica was observed at the substrate bed near to the inlet of the reactor, especially in the low silicon concentration region. However, the difference in structure was small in the high silicon concentration region where the coverage reached almost 100%. The catalytic activity for double-bond isomerization of 1-butene and thermal stability obtained by the two methods were similar, showing that the continuous-flow method was sufficient to prepare the silica monolayer catalyst commercially.
To produce amphiphilic polymer particles which have 2-[p-(1,1,3,3-tetramethyl-butyl)phenoxy-polyethoxy] ethyl groups for immobilizing enzymes, amphiphilic methacrylic monomers having a 2-[p-(1,1,3,3-tetramethyl-butyl)phenoxy-polyethoxy]ethyl group were synthesized. Methacrylic acid and 2-[p-(1,1,3,3-tetramethyl-butyl)phenoxy-polyethoxy]ethanol were esterified using N, N'-dicyclohexylcarbodiimide as a dehydrating reagent in dichloromethane. Synthesized monomers were characterized using an NMR spectrometer and an IR spectrometer. From the 1H-NMR spectra of the partially purified products, the yields of the 2-[p-(1,1,3,3-tetramethyl-butyl)phenoxy-polyethoxy]ethyl methacrylates with various polyethoxy group chain lengths were all higher than 75%. Their radical polymerization behavior in chloroform at 60°C was also studied using the NMR spectrometer. The rate of MAX-n polymerization is proportional to the 1.23th power of the monomer concentration. This was because the increase in the number n of the ethylene oxide units increases considerably the viscosity of the reaction mixture and prevents the termination reaction.
Microchannels were fabricated on both sides of a (100) silicon wafer (10 mm × 40 mm) by wet chemical etching after pattern transfer using a negative photoresist. The walls of the reactor channel (upper width = 400 μm, lower width = 280 μm, depth = 100 μm, and length = 78 mm) were coated by sputtering with a Pt layer for use as a catalyst. A heating element was installed in the channel on the opposite surface of the reactor channel, and a thermocouple was installed in a channel adjacent to the reactor. The reactor channel, as well as the reverse-side heating channel, was sealed with a glass plate by an anodic bonding technique so as to be gas-tight. The self-heating microreactor was then used for hydrogenation of benzene as a model reaction, and relevant kinetic data were obtained.
Mesoporous titania with high specific surface area was prepared by the hydration and condensation of titanium tetraisopropoxide (TTIP) in presence of alkylamine, which was used as a ligand-assisted template. The peak in the lower angle region of XRD patterns for as-synthesized titania powder was observed. This pattern of XRD suggests that the powder has an ordered nanostructure. The preparing method to obtain the sharp XRD pattern of as-synthesized powder is as follows; The precipitates, which were obtained by adding the distilled water without pH control to the mixing solution of the 2:1 TTIP to alkylamine molar ratio, were aged for 7 days at 25°C. The d(100)-spacing value is linearly increased with the alkyl chain length of alkylamine. The slope of the correlation line is larger than that in MCM-41, which has a hexagonally packed array of noninterconnecting cylindrical pores. The d-spacing value of the ordered nanostructure in MCM-41 is greatly increased by the addition of mesitylene, but the d(100)-spacing of the prepared titania in this study is slightly increased with the mesitylene concentration. These results may be caused by the difference in the ordered structure. It is presumed that the ordered nanostructure of the titania is a lamellar structure, but the nanostructure can not be confirmed by the other measurements. The surfactants in titania were removed by calcination and solvent extraction methods. The ordered nanostructure was destroyed by the removing surfactants. The BET specific surface area of the titania powder, in which the surfactants was removed with solvent extraction, is much larger than that with calcination. The specific surface area and pore volume increase with the addition of mesitylene and the largest surface area is 688 m2/g.
Electrochemical surface treatment of PAN-based carbon fibers in acidic electrolyte has been studied in increasing the surface acidic functional groups on fibers for the improvement of composite interfacial adhesion. With a viewpoint of acid-base interaction chemistry, low current densities are need for the changing of morphological and mechanical properties. This study reveals that anodic treatment under weakly oxidizing conditions in phosphoric acid electrolyte for 10 sec leads to surface modification of the fibers, preferentially prismatic planes. According to acid value, XPS and interfacial mechanical property measurements, it is revealed that the oxygen functional groups on fibers are largely dominated in composite mechanical behavior, whereas the nitrogen functional groups are not affected in the system studied. Also, a good correlation between surface acidic functionality and mechanical properties is established, and it is found that 0.4 A·m-2 current density is the optimum conditions for this system.
Palm kernel contains 4-5% of a thin brown skin, 0.1-0.2 mm thick called testa. Testa removal prior to the extraction process is effected by treating the kernel with hydrochloric acid. Soaking time, the minimum time required to remove the testa effectively from the kernel decreases with acid concentration and temperature. Soaking time is shortened from 63 minutes to 10 minutes when acid concentrations of 6 M and 12 M at 60°C were used, respectively. The extraction of the dehulled and undehulled ground palm kernel using supercritical carbon dioxide (SC-CO2) as a solvent at a pressure range 20.7 to 48.3 MPa and temperatures between 40-80°C is studied. At 48.3 MPa and 80°C the solubility of the oil is about 20 g/100 g carbon dioxide. The difference in solubility of the oil from the dehulled and undehulled palm kernel is not significant. However, a better quality light colored palm kernel oil with a lower fatty acid content is produced in the extraction of dehulled palm kernel besides a more attractive low fiber content palm kernel meal.
Desorption properties of preadsorbed metal ions, whose valences are monovalent, divalent and trivalent, from sodium polyacrylate gel are investigated over the range of pH of buffer solutions. It is considered that in the gel which forms metal complexes, carboxyl groups combine with the metal ions according to their charge number stoichiometrically. From this fact, the desorption mechanism of the preadsorbed metal ions from the gel into aqueous phase is theoretically analyzed on the basis of dissociation equilibrium for polyacrylic acids and mass balance of the fixed carboxyl group species. Consequently, the model equations which allow quantitative consideration of the desorption mechanism in these systems, can be derived as a function of the hydrogen ion concentration, measured easily in the outer aqueous solution. The desorption equilibrium of monovalent, divalent and trivalent metal ions from the gel can be explained fairly well by the models.
Motion and trajectory of small particles in turbulent airflow are numerically studied to clarify a striped pattern deposition layer. In the simulation, the striped deposition layers are considered as obstacles on a flat wall, and the turbulent airflow fields in a rectangular channel are calculated by the k-ε model. The equation of particle motion includes drag force, gravitational force, and shear-induced lift force. To simulate the random motion of particles in turbulent flow, the Monte Carlo method is also applied, and the particle trajectories are calculated with the Lagrangian method. The effects of the shape and size of the obstacle on the particle trajectory and the deposition on channel wall are analyzed, and the frequency distribution of deposited particles are discussed in detail; namely, the non-deposition section behind the obstacle is equivalent to the interval between striped deposition layers, which increases with obstacle height, air velocity, and particle diameter.
The optimal operation problem of a reactive batch distillation column is solved for various types of models and also for different objective functions. As the base case a detailed model, including a dynamic energy balance, is developed for the process producing ethyl acetate. The reflux ratio and the heat duty are selected as the variables to be optimized and are assumed to be piecewise constant. First, the effect of the number of piecewise constant time periods on the value of the objective function is investigated. The result indicates that the performance is considerably improved with an increase in the number of time periods. The optimization results, evaluating the effect of the reaction on the trays, show that, compared with the case where the reaction occurs only in the reboiler, the reaction of the trays sometimes has a negative impact on the progress of the reaction. The results obtained from the models of different preciseness show that the assumptions of an algebraic energy balance sometimes overestimate the performance of the column. The effects of the holdup dynamics, the type of objective function, and the non-ideality of the VLE model are also discussed by comparing various optimization results.
This paper concerns the nonlinear observer-based control design, which is mainly based on Fliess' linearization and parametrized transformation for uncertain nonlinear processes. The proposed control scheme allows us to adjust the rate of tracking and the decay of observer error for regulating the system output. Through the valid selection of tuning parameters of the output feedback controller, the bounded output tracking is achieved and its tuning scheme is robust against model uncertainties. The effectiveness of our design method is demonstrated by a simulation example of the control of an exothermic CSTR with multiple steady states. Under significant observer-initialization errors and unstable operating conditions of designs, the satisfactory output regulation and disturbance rejection are obtained.
A new scheduling algorithm based on an optimal control theory is presented for large-scale industrial problems. The main feature of this idea lies in a two-level hierarchical structure consisting of a reference model and a rigorous model, respectively. As a fair compromise between the excess of decision detail and long-range planning inspiration, we address simplified or relaxed models to derive optimal trajectories. The optimal trajectory is then used as a reference trajectory to be tracked in real time by a feedback control system to cope with uncertainty and modeling errors. We apply this idea to operation scheduling of refinery processes that convert crude oil mix into a variety of marketable products through a number of refining processes. The optimal control formulation is shown to enhance solution performance compared with the traditional mixed-integer model.
The size of calcium alginate gel beads can be controlled by application of high voltage to an interface between an aqueous alginate solution and an organic phase containing a surfactant Span#83. With voltage application, the size of the alginate solution droplets is controlled. The droplets controlled in size are then contacted with CaCl2 solution to be converted into the gel beads. Control of the size of the gel beads is possible at Span#83 concentrations below 5 wt%, and the size changes from a few millimeters to a few hundred micrometers with an increase in the applied voltage. The gel beads are monodispersive when their average size is above 0.5 mm, and polydispersive below 0.5 mm. The technique is applied successfully to entrap Baker's yeast. The entrapped yeast cells remain alive.
Esterification by powdered lipase between benzyl alcohol and octanoic acid solubilized in organic solvent was carried out in a stirred tank. The effect of water activity, aw, in cyclohexane on the esterification rate is examined. The reaction rate reaches a maximum at an aw value of 0.8426. Among the kinetic constants obtained for aw = 1, 0.924, 0.8426, 0.7528 and 0.634, the maximum reaction rate, Vmax, is found to be affected by the water activity. These facts can be explained by the activity of water as a competitive substance in the organic media and the hydration state of the enzyme. The values of Michaelis constants for the acid and the alcohol are constant regardless of the water activity.
A chemical heat pump system using BaO/BaCO3 reversible reaction is proposed for high temperature heat storage and temperature upgrading above 1273 K, because the BaO/BaCO3 reaction can be controlled under moderate pressure, even above 1273 K. Thermogravimetric studies on carbonation of BaO at 973-1523 K and decarbonation of BaCO3 at 1073-1523 K were carried out under various CO2 pressures in order to characterize the heat generating and storing rates of the CHP. In both reactions, reaction rate and conversion increase with an increase in temperature. Compared to carbonation, decarbonation is more strongly influenced by reaction temperature as well as pressure of CO2. It is also found that the eutectic reaction between BaO and BaCO3 has a great influence on the reaction characteristics; i.e. for carbonation with pressures around Pe and for decarbonation with all pressures lower than Pe above 1303 K, the reaction rate drops after X = 0.4-0.6 due to diffusion resistance of CO2 caused by the eutectic reaction. A rate expression similar to that of the CaO/CaCO3 reaction is found to be applicable for the BaO/BaCO3 reaction in the initial phase-boundary controlled period. Assuming that conversions of carbonation and decarbonation have to reach over 0.6 within 30 and 60 min, the heat releasing step can be operated at 1273 K or higher above the equilibrium pressure, but the heat storing operation must be carried out above 1273 K, below a quarter of Pe.
Using a fuzzy neural network (FNN), we constructed a simulation model which estimates the effluent chemical oxygen demand (COD) value from daily routine measurements. Since the water quality of wastewater is changing day by day, an FNN model with a recursively renewing method of learning data (R-FNN) is proposed. With this R-FNN, learning data used to construct an FNN model are renewed with elapsed time so as to estimate the effluent COD value with good accuracy. The estimation results for 9 weeks data using R-FNN were compared with those using a conventional FNN. The average error using the R-FNN model was 0.36 mg/l, while that using the conventional FNN was 1.50 mg/l. Moreover, estimation of the effluent COD throughout one year was carried out, and the average error was only 0.40 mg/l. This result can show the usefulness of the R-FNN for the simulation model of the activated sludge process.
Commercially available crude oils and fats contain on average 0.5-3% free fatty acids. These free fatty acids are known to react with the alkaline catalyst and form saponified products during transesterification reactions for biodiesel fuel production in the conventional commercial process. Purification of the products therefore becomes necessary after the reaction. In addition, it causes a longer production process and increases the production costs. For this aspect, supercritical methanol method without using any catalyst is evaluated in this work for reaction of free fatty acids. As a result, complete conversion is achieved for saturated fatty acids to methyl esters at temperatures above 400°C, whereas for unsaturated fatty acids, lower temperature of 350°C is appropriate, and higher temperature resulted in a degradation of the products. Consequently, a conversion of free fatty acids to methyl esters is highest, over 95%, when treated at 350°C. Fortunately, this temperature treatment is also most appropriate for transesterification of triglycerides. Thus, the overall conversion process of rapeseed oil to methyl esters is concluded to be adequate at 350°C. This finding supports the superiority of supercritical methanol method on biodiesel fuel production, compared with the conventional method, in which the production process becomes much simpler and increases the total yield due to the methyl esters produced from free fatty acids.
Malodorous gases such as ammonia, methyl mercaptan, hydrogen sulfide, and trimethylamine give discomfort and harm. The removal of these odors has been studied using impregnated activated carbon fibers (ACFs), where chemicals were present on the surface of ACF to increase the adsorption capacity. From experimental results, cellulose-based ACF shows the best efficiency. In conjunction with the removal of acid odor, ACF impregnated with KI shows high performance, and the optimum impregnation concentration is 9 wt% of KI on the surface of ACF. In addition, H2SO4 demonstrates desirable properties in the removal of basic odor. Total regeneration is achieved by using a hot steam of 250°C, and no change of the adsorption capacity has been observed after regeneration. Various design techniques for adsorption towers have been exploited using pilot-scale apparatus, in which flow rate is 3 m3/min. The results show that removal efficiency is as high as that from a bench scale experiment. Moreover, the pilot-scale regeneration process also showed high performance.
The raw industrial wastewater from LSI photo-resist processing which contains 1,2-naphthoquinone-2-diazido-5-sulfonic acid sodium salt as a main component with high NaCl concentration (>20 kg/m3), is very difficult to treat. The establishment of an appropriate treatment, which is friendly to the earth's environment for raw industrial wastewater is an urgent matter to be solved. Total organic carbon (TOC) removal of the raw industrial wastewater, which contains TOC at 8000 g-TOC/m3, by using hydrogen peroxide and ultraviolet irradiation (H2O2/UV), has been carried out. Experiments were carried out in a batch reactor with a low pressure UV lamp (500 W) irradiating ultraviolet at 254 nm and at 185 nm (5%). The chemical compounds included in the raw industrial wastewater have been removed completely in the presence of initial concentration of hydrogen peroxide of two times the stoichiometric ratio.