Vapor–liquid equilibria (VLE) of ETBE (Ethyl Tertiary Butyl Ether)+ethanol, ETBE+octane and ethanol+octane binary systems and ETBE+ethanol+octane ternary system were measured at atmospheric pressure by using an improved Othmer-type apparatus. VLE of the binary systems were found to be thermodynamically consistent. The Wilson equation widely adopted in engineering was successfully applied to correlate VLE of the binary systems. Further, VLE of the ternary system can be predicted by using the binary Wilson parameters of the constituent binary systems.
The pore structure of calcium oxide powder was modified by addition of small amounts of inorganic salts as impregnants to pulverized limestone, which was then calcined in a powder-particle fluidized bed (PPFB) at ambient pressure. The effects of type of fluidizing gas, temperature distribution along the vertical direction of the reactor and addition of inorganic impregnants on the physical properties and moisture absorptivity of the product powder were investigated. Dependence of specific surface area, pore volume and calcination conversion on the moisture absorptivity of the product powder under low dew point of 270–273 K was analyzed. Further calcination occurred in the freeboard region with higher temperature, giving a product powder with more porous structure. Nitrogen gas was superior to dry air for producing highly porous calcium oxide powder. Calcination with additive impregnation of 1% sodium carbonate and 1% calcium acetate expanded the size of pores, newly producing pores of larger than 10 nm. Disclosure tests under low dew point atmosphere revealed that the pore sizes of the product powder effective for moisture absorption lay in the range of 6–50 nm. Good correlation of moisture absorptivity was found in the initial stage with the specific surface area, and in the middle stage with the pore volume of the product powder.
A new simulation method using spherical particles with an equivalent rolling friction coefficient was proposed to efficiently incorporate the effect of particle shape on powder behavior into the distinct element method (DEM). It was shown that the coefficient of rolling friction depends on the coefficients related to particle shape and rotational angular velocity from analysis of the behavior of a polygonal pillar rolling on an inclined plate. Then the behavior of the polygonal pillar was represented by the DEM simulation using a cylinder model with the equivalent value of the rolling friction of the polygonal pillar. Next, the coefficient of rolling friction of irregular particles was obtained by the equivalent rolling friction coefficient predicted by using Profile Fourier coefficients of the irregular particles. The simulated flow behaviors of the irregular particles on the inclined plate using spherical model were in good agreement with the experimental ones, and the reliability of the proposed shape description of irregular particles and their equivalent rolling friction coefficient were confirmed.
A stripping column for residual vinyl chloride monomer (VCM) in poly(vinyl chloride) (PVC) slurry was developed in order to meet the most important environmental needs in PVC manufacturing. A stripping column consisting of a steam/PVC slurry counterflow system with sieve trays was chosen to achieve VCM environmental regulation, higher PVC productivity, and preservation of PVC quality (especially initial color of PVC) after VCM stripping. The stable running conditions and VCM stripping ability were evaluated for this column. Based on these results, the VCM stripping column was scaled up, and a high efficiency VCM stripping system with a stripping capacity of 35 t/h (as PVC) was designed.
The presence of impurities in the process of industrial crystallization influences crystal growth phenomena and often dominates production efficiency. The present work was therefore undertaken to study how the presence of impurities (admixture impurities) influences growth phenomena of single crystals and crystalline particles (suspended crystals) of inorganic phosphorus compounds, and how admixture impurities influence the quality of crystalline particles. We found that admixture impurities affect crystal growth rate but not crystal structure. In particular, Ca2+ had a greater influence on crystal growth rate than other metal ions, and the addition of Ca2+ at an ionic concentration of 10 ppm (solution mass ratio) caused a decrease of about 35% in the crystal growth rate. Furthermore, crystal growth rate could be recovered by the addition of a masking agent, EDTA, even in the presence of Ca2+. Thus, we found an indicator to improve production efficiency of crystalline particles in the presence of admixture impurities.
PVC polymerization technology was developed to reduce polymerization time without deforming the PVC characters (especially color appearance), by which the total batch cycle time was remarkably reduced. Perester and diacyl derivative initiators were concluded to be effective, and the polymerization time was reduced from 4 h to 3 h by use of these initiators and reactor cooling technologies. Simultaneously, the control of polymerization state and the conditions for emergency stop of polymerization by use of inhibitors were investigated for the sake of safety in short-time (high speed) polymerization, and a monitoring system was established for safer PVC polymerization. Applying these technologies to present commercial plants is expected to result in greatly increased productivity and reduced cost.
The gas-phase reaction NO–NH3–O2 was investigated in a tubular flow reactor at a pressure of 788 kPa and temperatures from 650 to 850°C. Injection of ammonia into a 2MWthPFBC combustor was also attempted, and it was found that 55% of NO was converted to N2 at 855°C with an NH3/NO molar ratio of 2 and residence time of 1.4 s. In the combustor, the nitric oxide concentration could be reduced to less than 70 ppm, and leakage of ammonia was kept below 5 ppm at the full load. During the load change operation in the combustor, nitric oxide was decreased as the load became higher when the ammonia injection was controlled by the prediction method.
A simulation-based approach is one of the most effective ways of solving design problems of production systems under uncertain conditions. However, a simulator generating system is indispensable to employ this approach. Also, such a generator is required to devise an appropriate operational rule set for each simulator. In this work, a design support system was developed using object-oriented technique, which composes simulators with various configurations of software components. Reinforcement learning was adopted in order to obtain a rule set for operating each of composed simulators. Verification and evaluation of effectiveness of the method was confirmed through a series of experiments (design of lanes and locations of machines, acquisition of proper control rules of vehicles) using an automated guarded vehicle system (AGVS) as a model system.
Industrial plant alarm systems form an essential part of the operator interfaces for automatically monitoring plant state deviations and for attracting the plant operator's attention to the changes that require his/her intervention. In this paper, we describe a new method for selecting alarm source signals using a cause-effect model. (A cause-effect model is an abnormality propagation diagram that shows the propagation process of abnormalities after a malfunction on the basis of the material and energy balances of the plant.) The derived sets of alarm source signals are theoretically guaranteed to be able to statistically identify all assumed malfunctions. To evaluate the sets of alarm source signals quantitatively, we developed a preference index using the reachability matrix of the cause-effect model. The index is confirmed by using the structured cause-effect model. The design method was applied to a simple reaction process for this case study, and the simulation results proved the usefulness of the proposed approach.
The LST-03 lipase from an organic solvent-tolerant Pseudomonas aeruginosa LST-03 has high stability and activity in the presence of various organic solvents. The LST-03 lipase requires a lipase-specific foldase for its activation, and the recombinant LST-03 lipase expressed by a heterogeneous host can be activated using a lipase-specific foldase in vitro. The activity of the activated recombinant LST-03 lipase was further enhanced by addition of calcium ions. This enhancement was suggested to be the result of the conformational transition of the lipase induced by the binding of a calcium ion to the lipase. On the other hand, the organic solvent-stability of the recombinant LST-03 lipase was greatly different from that of the LST-03 lipase prepared from the culture supernatant of a P. aeruginosa LST-03. When the recombinant LST-03 lipase was activated in vitro using the lipase-specific foldase, the foldase was tightly bound to the lipase and influenced the organic solvent-stability of the recombinant lipase.
Methane hydrate has recently attracted attention as a potential energy resource, which might be recovered from the deep seabed by means of a gas lift recovery system. This study examined the flow of seawater and behavior of hydrate particles around the bottom of the riser pipe by simulation and experiment in order to determine the optimal shape of the bottom of the pipe and the optimal operating conditions. The finite differential method and the discrete element method were combined to simulate the governing equations of sea water as a continuum and hydrate particles as discrete elements. The simulation results agreed reasonably well with the experimental results conducted for the laboratory-scale riser pipe with height of 1.5 m and diameter of 0.05 m. The simulations for the actual scale with diameter of 1 m showed that the optimal shape at the bottom of the rise pipe is umbrella-shaped with a 45°C degree slope and height of 0.4–0.6 m. The simulations also showed that the gas-lift method is sufficiently effective and economical if the hydrate layer at the seabed can be crushed into small pieces with diameter of 0.1 m