In order to evaluate the activities of granular catalysts, a microreactor having six channels was fabricated using silicon and glass plates by means of photolithography and wet etching. Using anodic bonding, the plates were configured so as to be gas tight. The dimensions of the channels were 1 mm in width, 0.3 mm in depth and 6 mm in length. Catalysts for the oxidation of carbon monoxide in hydrogen, as examples, were prepared by impregnating Pt, Rh, Ru, Co, Ni, Cu and Pd on γ-alumina support particles which were sieved to 150–210 μm, and 9-mg aliquots of the catalysts were packed in the channels. The experiments were carried out in the temperature range of 120–200°C, and the compositions in the products were determined by quadrupole mass spectrometry. The findings show that the microchannel reactor could be used for the efficient screening of granular catalysts.
The advantage of annular chromatography is the continuous separation of a feed mixture and the simultaneously regeneration of the medium. Therefore it is necessary to know the period, how long such a system can be operated in a continuous manner. In our case the long-term experiment could be performed without a change in performance for one week. Afterwards the peak has started to shift and the variance has increased. In further studies we have demonstrated that increasing the angular velocity has no influence on the resolution of two model compounds. The resolution and HETP (height equivalent to one theoretical plate) stayed constant keeping the loading factor constant. In annular chromatography there are three different dispersions that contribute to peak broadening, axial, radial, and circumferential. The experiments with the stationary annular column showed, that the circumferential dispersion in annular chromatography can be neglected.
The prediction of slurry viscosity for the suspensions with and without particle size distribution has become possible by using the suspension rheology model proposed in this study. The viscosity prediction model is based on Simha’s cell model, which is applicable to completely dispersed systems. It was certified experimentally that the Simha’s model was able to predict the slurry viscosity for the case of the suspensions with particle size distribution. The present suspension rheology model adopted the assumption that the effect of agglomeration appeared only for the cluster formation with the minimum sized particles, and the other larger particles were completely dispersed. Usui previously proposed the same type model, but the model is modified to give more accurate viscosity predictions. The present model makes the assumption that multi-breakup of inter-particle bonding occurs when a cluster breaks into two parts under a simple shear flow. It is demonstrated that the present model combined with the Simha’s cell model can be successfully used to predict the rheological behavior of slurries. 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 was proposed. The maximum packing volume fraction was used to predict the slurry viscosity with completely dispersed condition. For this purpose, Simha’s cell model was applied for the 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 calcium carbonate-water slurry and fly ash slurry. It was certified that the maximum packing volume fraction for non-spherical particles can be successfully used to predict the slurry viscosity, and this means indirectly the maximum packing volume fraction determined in this study may be reasonable.
In our previous report, a hollow granule model was proposed as a basis of spray drying granulation of slurry in case of fast and easy evaporation. In the present research, the compatibility of the model was examined by comparing the granule diameters obtained from the model with those from granulation experiments. The granules were prepared with slurry of 0.3 μm mono-dispersed silica particles without binder and dispersant by means of a spinning disk. As a result, it was confirmed that the calculated values from the model suited well with the experimental ones, and thus the granule diameter increases with lower rate of disk rotation and higher particle volume concentration of the slurry.
WC particle was coated with TiC and Al2O3 particles using Co binding one by means of high-speed rotational blending to enhance the degree of mixing. Then the sintered composite material of WC-Co/TiC-Al2O3 was prepared, and the hot hardness was measured up to 800°C to be compared with conventional WC-Co alloy. It was found that the addition of TiC and Al2O3 components in the WC-Co alloy has a strong influence on the hot hardness. The hardness increased with higher amount of TiC from 5 up to 30 by weight percentage, whereas increasing Al2O3 additions reduced the hardness. Particularly, Al2O3 was effective due to its higher chemical stability than TiC at elevated temperature. Then, the highest hardness was obtained with addition of 30TiC-5Al2O3 by weight. This suggests that these materials can further be utilized for high temperature applications.
The performance of a dynamic matrix control (DMC) algorithm was investigated for the control of a fluidized catalytic cracking (FCC) process operated under full and partial combustion modes. Several types of hierarchical control systems consisting of a supervisory controller and a basic regulatory controller were designed according to the control purpose and the combustion mode. Then, the designed control systems were applied for supervisory unconstrained and constrained control of the FCC process. The dynamic matrix controllers for the unconstrained control showed better performance than PI-controllers for tracking set-points and for rejecting disturbances under both the combustion modes. The supervisory constrained control using the dynamic matrix controllers also showed good performance.
Heat-integrated distillation has long been considered as one of the technologies to reduce energy consumption in distillation columns. Despite the economic advantage, it introduces great difficulties in process operation due to the nonlinear, multivariable, and interacting characteristics of an energy-integrated system. In this study, a high-purity heat-integrated distillation system with light split/reverse configuration is utilized as a test case to separate methanol from water. Controllability of this system using nonlinear control algorithms is addressed in this study. A modeling/control approach is studied in this paper to handle the complicated characteristics of the system. A representative low-order nonlinear model is established and utilized to construct nonlinear simplified decouplers, thereby diagonalizing the input-output mapping of the distillation model. Linearizing feedback transformations are then adopted to reduce process nonlinearity for the nearly diagonalized system. Finally, PI controllers are designed on the basis of this transformed linear system. Significant performance improvement in control tests of the utilized nonlinear control approach over linear control strategy is achieved.
This paper presents a method for robust optimal design of chemical processes under parameter uncertainty. The robust optimal design problem is considered as a multiobjective optimization problem in which the expected cost, the economic robustness and the technical robustness are the three objectives. The number of economic robust alternatives could be obtained from the robust design model with its solution algorithms. A decision-making method is proposed to reduce the number of design alternatives and to decide the best-preferred design based on the technical robustness. Two approaches are proposed, which are different from each other in considering the priority of technical robustness in comparison with other objectives. As an application design problem, the wastewater reuse network design of plating process is addressed under uncertain waste input compositions to the cleaning and rinsing system. The application to the wastewater reuse network of plating process illustrates the efficacy of the proposed method for designing robust processes in both economic and technical aspects.
This paper considers robust PID controller design for uncertain processes with gain and phase margin specifications. The problem is converted into an LMI problem which can be solved effectively using the interior point method. The simulations are given to demonstrate the proposed method.
In order to select adequate solvents for protein refolding, immobilized preparation of a given protein that is covalently fixed on the surface of support materials, has been employed. This method is greatly useful for selection of solvents appropriate to refolding itself of the protein molecule, excluding unfavorable intermolecular interactions such as aggregation and autoproteolysis that emerge concurrently during the refolding. The purpose of this work is to obtain the preparation that warrants the constant recovered activity in the same denaturation/renaturation procedure. Such immobilized preparation is necessary for quantitative estimation of ability of refolding solvents. The globular proteins employed were subtilisin BPN’, ribonuclease A and Streptomyces griseus trypsin. In the case of such a protein as subtilisin possessing no disulfide bond in the molecule, agarose beads which have been widely used exhibited high retained activity and the constant recovered activity in the repeated denaturation/renaturation procedures, and revealed to be excellent as a support material. However, agarose gels were not suitable in the case of the other enzymes possessing disulfide bonds. This is probably attributable to involvement of reduction and oxidation reactions in the procedure applied to the latter case. Investigation of various support materials other than agarose beads revealed that the stable immobilized preparation of disulfide-involving protein could be established by use of glass beads that are resistant against oxidation and reduction with relatively high retained activity.
The effect of O3 treatment and AOP (Advanced Oxidation Processes) treatment on the decomposition of endocrine disruptors were investigated by using continuous type pilot plant. Reaction kinetic evaluations of these processes were also carried out. In this study, the endocrine disruptors were classified into 2 groups: (1) DXNs: dioxins and (2) EDs: endocrine disruptors other than dioxins. For the case of DXNs decomposition, highly concentrated DXNs in a incinerator washwater were degraded by UV/O3 combined treatment. Influence of O3 dosage and forms of DXNs on the reaction rate constant were evaluated. The incinerator washwater was sampled from a scrubber, which was used for the flue gas treatment of a garbage incinerator facility. For the case of EDs decomposition, the effect of O3 dosage on the reaction rate constant were investigated during O3 treatment of secondary treated sewage. Also, a comparison was made on the degradability for the above 2 groups. The following results were obtained. (1) The DXNs contained in the incinerator washwater had different decomposition properties depending on the particle size of suspended solid. Above a particle size of 1.0 μm, the reaction rate constant was relatively small and the DXNs were relatively non-degradable. On the other hand, when suspended solid particle size was below 1.0 μm, the reaction rate constant was large and the DXNs were relatively degradable. (2) The amount of decomposed DXNs per consumed O3 increased with the increase of DXNs concentrations in the influent and higher DXNs decomposition efficiencies were obtained. (3) The reaction rate constant in the EDs decomposition was larger than that in the DXNs decomposition, and the EDs were found to be relatively easy to be decomposed. Once DXNs on the suspended solid particle size larger than 1.0 μm in the incinerator washwater were non-degradable, we found that they should be filtered and concentrated separately prior to the AOP treatment to ensure an efficient treatment.
In this study, a chemical heat pump using a calcium oxide/carbon dioxide reaction system was discussed. In order to establish the operational conditions of heat pump, heat storage and heat generation experiments were done under various reaction pressure and temperature conditions in a packed bed reactor. Decarbonation reactivity of CaCO3 was higher at higher temperature and lower pressure, and practical reaction rate was observed at reaction temperature about 1023 K under reaction pressure of 0.1 atm. Carbonation reactions of CaO proceeded almost at the equilibrium temperature of the reaction pressure. Carbonation at temperature of 1123 K was observed at reaction pressure of 1.0 atm. Then, an analytical model based on heat and mass transfer was proposed to explain the observed phenomena during carbonation in the packed bed. The analytical model enables us to clarify the detailed behavior in the bed during carbonation. The carbonation was controlled mainly by heat transfer in the packed bed. The influence of the gas flow on heat transfer was indispensable for the analytical model. The model represented well the phenomena in the experimental packed bed reactor.