An association model with a cubic equation of state was adopted to calculate the solubilities of alkali metal chlorides in water vapor under high temperatures and pressures. The solubilities of sodium chloride (NaCl) and potassium chloride (KCl) were correlated by optimized association numbers and equilibrium constants. The correlated results represented well the experimental results. The logarithm of equilibrium constants show linear functions of reciprocal of the absolute temperature.
Experiments on stabilized agitated dispersion of non-reacting styrene monomers were conducted at various dispersed phase hold-up fractions, impeller geometries, impeller speeds and agitation times. The experimental drop size distributions obtained were described best by the cumulative upper limit volume, upper limit number and the Nukiyama–Tanasawa ones. Plots of the maximum diameter and the mean diameter vs. the Sauter mean diameter gave straight lines with slopes 1.74 and 0.87, respectively.
The kneading process is widely used in various industries. When wet particles are mixed, the double-bladed kneader is one of the most useful instruments. We study the power consumption of a double-bladed kneader. The power is a very important factor in kneader designing and the examination of kneading conditions. In this paper, we propose an estimation method of the power consumption for double-bladed kneaders of various geometrical con-figurations based on the relation of the power number, NP, and the modified Reynolds number, Re′. The influences of the vessel type, blade shape, wet particle volume and blade thickness on the power index, β, and the equivalent yield stress, (τc/B) were investigated. The influence of the geometrical configuration of a kneader on β and (τc/B) was explained using the dimensionless wet particle volume, V/v, and the dimensionless effective shearing area, S/s, respectively. These relations were correlated as a power expression. The equations obtained could be used to estimate the values of β and (τc/B) with errors of ±5% and ±10%, respectively. The applicability of these equations was examined in experiments using wet CaCO3 particles and wet kaolin particles. Furthermore, in this study, the power consumption of various kneaders was estimated concretely. As a result, it was shown that the power consumption could be estimated with good accuracy.
The effect of pressure on the overall oxidation rate of glucose in an aqueous solution containing glucose oxidase and excess catalase was studied experimentally and theoretically in a bubble column under a pressurized condition. A bubble column with a diameter of 45 mm was used as the reactor under the pressure from 0.1 to 1.1 MPa. A model for the overall oxidation rate of glucose was presented on the basis of the film theory incorporating mass transfer of oxygen. The experimental values for the overall rate of glucose oxidation agreed approximately with the calculated values based on the present model using a previous experimental equation for the volumetric mass transfer coefficient obtained in the pressurized bubble column.
In this study, several new operating strategies are presented to enhance the separation performance of an SMB process. The basic principle of the new operating strategies is to add more outlet ports (raffinate or extract) to a conventional SMB system. The advantage of the SMB based on the new operating strategies over a conventional SMB is validated with a series of detailed simulations.
A 2-dimensional model for thermal cracking of ethane under laminar flow conditions has been established. Based on a molecular mechanistic model for ethane cracking, the model consists of eight mass balance equations along with energy balance and momentum balance equations. This set of coupled partial differential equations is solved numerically by using finite difference backward implicit scheme. The species concentration and temperature profiles in radial and axial directions are predicted with variation of properties with temperature and composition. The model predicts maxima in the concentrations of propylene and acetylene within the reactor. The simulations for the effect of operational parameters on product distribution and temperature are also carried out. The parameters—space time and wall temperature and their range of variations are considered. Wall temperature variation is taken from 950 to 1100°C and space time conditions are taken from 0.2 to 0.45 s. An increase in space time and/or wall temperature results in higher ethane conversion.
A temperature policy for the n-th-order reaction with the m-th-order deactivation of catalyst has been analysed on the basis of the variational calculus. For the process mentioned above, the optimum tf,opt and isothermal tf,isot times of the process and consequently their quotient have been calculated. On this basis, it was found that the higher was the quotient, the lower was the final activity of catalyst af and the higher was the quotient of activation energy E. An effect of deactivation order m is dependent on its value.
Integration of various decision making processes, such as planning, design, and operation, is necessary for dynamic and flexible batch production. The integration is not only achieved through sharing of information, but also through utilization of common models used for decision making processes. A batch system is a typical discrete event system. This paper aims at presenting a fault detection technique for batch processes and discussing the possibilities of integration of fault detection and controller synthesis based on discrete event system approaches.
In this paper, a modeling method of high dimensional piecewise affine models is proposed. Because the model is expressed by radial basis function networks, whose RBFs are located at the grid points of the orthogonal coordinate in the input space, the shape of the piecewise affine model becomes easily understood. The more the number of RBFs is, the higher the approximation capability of the model is. The algorithm to increase the number of RBFs was developed in focusing on the distribution of estimation errors. By approximating nonlinear processes with piecewise affine models, control theories using mixed logical dynamical systems can be applied.
The procedure followed in chemical processes can be expressed in simple terms such as the flow of events from the raw materials to the product. To obtain the best final product, chemical engineers have to consider many factors including environmental effects, stability, economic considerations, and so on. In particular, when considering the stability if the process and the purity of the product, it is very important to detect any faults in the chemical process immediately. In this paper, a hybrid fault diagnosis model based on the signed digraph (SDG) and support vector machine (SVM) is proposed. By means of the system decomposition based on SDG, the local models of each measured variable are constructed and more accurate and fast models are using an SVM, which has no loss of information and shows good performance, in order to obtain the estimated value of the variable, which is then compared with the measured value in order to diagnose the fault. To verify the performance of the proposed model, the Tennessee Eastman (TE) Process was studied and the proposed method was found to demonstrate a good diagnosis capability compared with previous statistical methods.
A heat integrated distillation column (HIDiC) is a new and highly energy-efficient distillation process. In the present work, dynamic simulation models for several types of HIDiCs were developed. The energy efficiency, dynamics, and controllability of HIDiCs were investigated by using the developed simulator, and these characteristics were compared with those of a conventional distillation column (CDiC). HIDiC has a more complex structure and slower dynamics than CDiC, but the control performance of HIDiC is comparable to that of CDiC as long as a suitable control system is designed. The distillate flow rate (D) is superior to the reflux flow rate (L) as a manipulated variable, because the dynamics of HIDiC becomes considerably faster by using D rather than L. To achieve high energy efficiency and controllability at the same time, it is recommended to adopt the structure in which the feed is preheated by distillate vapor (product), a condenser is used, and a reboiler is not used. In addition, the control performance of HIDiC becomes better as the heat transfer area decreases, and it becomes slightly better as the pressure difference between the stripping section and the rectifying section decreases.
A single nucleotide polymorphism (SNP) was detected by the use of affinity chromatography with a single-stranded DNA ligand and temperature gradient elution. Because of the difference in thermostability between the ligand and sample single-stranded DNAs with and without SNPs, they were eluted as a peak with a shoulder by the temperature gradient elution. The sample DNAs with SNPs were detected as low as 0.1 pmol, and the elution behavior of DNAs with and without SNPs in this chromatography was predicted by a numerical calculation method based on a thermodynamic mass transfer model.
This paper describes a very simple and rapid method for fabrication of microfluidic devices on the material polydimethylsiloxane (PDMS). The fabrication process is greatly simplified by using a micromachined polymethylmethacrylate (PMMA) master instead of using a silicon photoresist. A PDMS pre-polymer mixture was cast over the PMMA master and cured to produce positive relief structures in PDMS which then served as a mold. This PDMS mold was conveniently used for multiple production of PDMS replicas containing the desired microstructures similar to those on the surface of the original PMMA master. Because our procedure does not require a photoresist, it minimizes the requirement for special equipment and decreases the total fabrication time. Moreover, the method offers the advantage of a wide range of feature size, specifically deeper channels unobtainable with silicon photoresist. Examination of the sidewalls of the channels revealed high fidelity in reproducing the PMMA master via the hardened-PDMS mold. Our protocol enables the production of multiple PDMS-based microfluidic devices in a low-cost and efficient manner.
We report several findings about solitary wave trains in a liquid surface, which is produced by the Marangoni instability. The wave trains were induced by adsorption and absorption of the volatile species into another miscible liquid. Although the present system has been investigated focusing on the interfacial fluid dynamics in detail, our special interest in this paper is a mapping of the wave-mode on a certain diagram. First of all, we reported a kind of conservation law between the number of wave crests and the traveling speed. As the next, we mentioned that a liquid layer composed of a volatile species was formed on the less-volatile liquid. On the basis of these results, we successfully performed the mode-mapping on a diagram, the abscissa and ordinate of which represent the mass-transfer rate and the thickness of the layer, respectively. Both axes, respectively, corresponded to the strength of the driving force and the inertia against the movement.
A process for recovering phosphorus from wastewater in form of magnesium ammonium phosphate (MAP) crystals using a fluidized bed reactor was investigated. The phosphorus recovery ratio was found to be influenced by the particle size of the MAP crystals, as well as the reaction pH, inlet ammonium and phosphorus concentration. The optimum operation conditions for the fluidized bed reactor to achieve the maximum recovery rate of phosphorus were organized in terms of the supersaturation ratio and reaction pH. The best supersaturation ratio was found to be 3.7. The optimum reaction pH depended on the inlet phosphorus concentration and was found to be 7.9 when the inlet PO4-P was 230 mg·L–1. A continuous treatment of filtrate from digested sludge was performed based on these optimum operation conditions and using a newly proposed fluidized bed system. The fluidized bed system has a seeder, which allowed control of the particle size distribution inside the crystallization tower. A recovery ratio higher than 90% was achieved for a long period of the demonstration test in this new fluidized bed system.
We studied nitrate-nitrogen uptake by sterile Ulva sp. under various conditions including tropical ones. The Sterile Ulva sp., which was collected from Yokohama, Japan, removed nitrate-nitrogen in the culture medium. The algae took in nitrate-nitrogen even without light. The uptake rate of nitrate-nitrogen decreased with the increase of the nitrate-nitrogen content in algal cells. The ambient ammonia-nitrogen lowered the rate of nitrate-nitrogen uptake, whereas the ambient nitrate-nitrogen did not affect the ammonia-nitrogen uptake.
To improve the production of L-lactic acid by Streptococcus bovis using an original medium of fresh cassava roots (FCR) in tofu liquid waste (TLW), three nutrient supplements, skim milk (SM), the residue of the yeast extract waste (YEW) from beer manufacturer and concentrated maguro waste (CMW) from fish manufacturing were independently added to the original medium (FCR-TLW). Maximum fermentation properties (fermented L-lactic acid concentration, productivity of L-lactic acid and specific growth rate) were obtained at about 2% w/w crude protein concentration in the original medium for three nutrient supplements. The highest fermentation properties were shown by CMW supplement, and they were comparable with those in the standard medium. The medium supplemented with 2% w/w crude protein concentration of CMW in the original medium (FCR-TLW-CMW2) clearly gave the greatest effects on L-lactic acid production.