For the chemical reactor systems using phase transfer catalyst (PTC), the third liquid phase that is insoluble in both aqueous solution and organic solvent is separated by regulating concentrations of salt and catalyst. Previously, our research group has demonstrated that application of alternate current (AC) voltage in formation of a layer of the third phase could increase a yield of the product for the phase-separable reactor using polyethylene glycol (PEG) as PTC. The AC application is considered to change the property of the third phase, which influences acceleration of mass transfer of product between two phases. In order to intensify the phase-separable reactor with third phase, it is necessary to optimize flow characteristics in the organic phase and the third phase to maximize the mass flux stably.
In the present study, influence of flow characteristics in the third liquid phase to dynamic behavior of batch-type phase-separable reactor is investigated for synthesis of phenyl benzoate by using PEG. Time variation of conversion of benzoyl chloride and apparent selectivity of benzoyl chloride to phenyl benzoate is analyzed by the rate based model. When experiments were carried out by using different types of impeller, higher value of the apparent selectivity was seen in a case of using the six-blade flat paddle impeller (6FPI). A clear characteristic of vertical circulation flow in the third phase was also observed by the flow visualization experiments, especially when 6FPI and two types of reverse pitched blade impeller were used. Hence, it is made clear experimentally and numerically that the vertical circulation flow in the third phase is an influencing factor to enhance the overall reaction efficiency and that it could be controlled by type of impeller, its rotational speed and concentration of potassium hydroxide for preparation of the third phase.
Pure, isomorphic, round, and free-flowing dimethyl fumarate granules in a size range of 250–2000 μm were successfully produced directly from esterification through the three-in-one intensified process of three distinctive steps of reaction, crystallization, and spherical agglomeration (SA) in a 0.5 L sized jacketed glass stirred tank. Dimethyl fumarate was prepared by sulfuric acid catalyzed esterification of fumaric acid with methanol. The reaction temperature was below the maximum allowable limit of 65 °C as determined by reaction kinetics to avoid the runaway situation. The dissolution rate of primary crystals of dimethyl fumarate was inversely proportional to the particle size which was strongly affected by the antisolvent addition and temperature cooling schemes during crystallization. However, the dissolution rate of the round granules was mainly dependent on the exterior dimension of the granules and not so much on the primary crystal size inside the granules. The mechanical properties such as density, porosity Carr's index, friability, and fracture force of round dimethyl fumarate granules generated in (1) three-in-one processes with the final temperatures at either 5 or 25 °C (Three-in-one I and II) and (2) SA of dimethyl fumarate, which was done separately and disconnected from the train of reaction and crystallization process at either 5 or 25 °C (SA I and II), were thoroughly studied and compared. The concept of scale-up for Three-in-one I and II was also verified in a 10 L sized jacketed glass stirred tank. Powder manufacturability such as flowability, blend uniformity, and compressibility had been substantially enhanced by spherical agglomeration. The added values of free-flowing and easy-to-pack properties to dimethyl fumarate in addition to its original intrinsic slip planes in the crystal lattice would make direct compaction into tablets feasible.
The Natuna gas field, located in the Natuna Sea, was discovered in 1973, is one of the largest natural gas reserves in Indonesia with estimated natural gas reserves of 222 TCF. However, until now, the use of Natuna gas is still hampered because of the very high CO2 content reaching 71%, while the methane content is around 28%. The dry reforming of methane (DRM) process is one of the potential ways to be applied in solving these problems to convert CH4 and CO2 become a synthesis gas containing CO and H2 as a raw material that can be applied to manufacture as intermediate products or end products in the petrochemical industry such as acetic acid.
The conversion of carbon dioxide and methane to acetic acid is carried out in three stages. In the first step, carbon dioxide and methane are reformed to produce the synthesis gas at temperature of 800 °C and pressure of 1 bar. In the second step, the synthesis gas is converted to produce methanol at temperature of 150 °C and high pressure of 50 bar. In the third step, the acetic acid is produced by reacting methanol and CO in the methanol carbonylation process. The modeling and simulation of the acetic acid production were conducted by using Aspen Hysys v.10, considering mass and heat balances. The cubic equation of state was applied for reforming and methanol processes. In order to produce 71 MTPD of the acetic acid, the feed flow rates of CH4 and CO2 are 190 MTPD and 520 MTPD, respectively. The total energy required is 46.3 MMBtu per ton of acetic acid. The acetic acid has a purity of 99.4% with a concentration of 500 ppm methanol, and moisture content of 5,700 ppm.
Keywords: Dry reforming of methane, Modelling, Simulation, Acetic Acid
The solid particles or liquid droplets entrained by multi-phase flow in process plants can cause erosion, which may result in leakage of piping system or equipment. Hence, it is essential to evaluate erosion rate for determining design margin and taking counter-measures. To date, many models have been proposed for prediction of erosion induced by particles and droplets, but there is large difference in their prediction accuracy. The present study aims to validate CFD-based prediction accuracy of major erosion models using the published experimental data, for engineering applications.
Among many erosion models proposed to predict particle-induced erosion rate, the models of Finnie, Tabakoff & Grant, E/CRC, Oka and DNV are usually applied for evaluating erosion. Experimental data in literature were used to investigate CFD prediction accuracy of the five erosion models. CFD simulations were conducted for different flow velocities and piping geometries containing elbows and reducer. CFD results show that Finnie model under-estimates the erosion rates significantly, and other four models over-predict the erosion rates for all the cases. Among them, the erosion rates predicted by Tabakoff & Grant model are closest to the experimental results with moderate and acceptable conservativeness. Therefore, Tabakoff & Grant model is applicable to predict particle-induced erosion rate in engineering applications.
Also, CFD simulations were performed to validate CFD prediction of liquid droplet induced erosion rate, using the data of water impingement experiments conducted by Isomoto et al.. The investigated erosion models include the models of Haugen, Isomoto and DNV. CFD results show that all the three models over-predict the erosion rates. Among them, the erosion rates predicted by Haugen model for all the water impingement velocities are closest to the experimental results with moderate and acceptable conservativeness. Hence, Haugen model is applicable to predict droplet-induced erosion rate in engineering applications.
Mathematical model is powerful conceptual framework to elucidate underlying biological mechanisms and guide further experiments. Researchers usually use equation – based model which is deterministic and assumes a homogeneous population, therefore, is not appropriate for systems characterized by a high degree of localization, distribution and dominated by discrete decisions. In this study, we developed a cell – based model that is more suitable for understanding the heterogeneity of stem cell population which is a challenge in bioprocessing for application in regenerative medicine.
Previously, different positions of region with cells deviated from the undifferentiated state of hiPSCs in cultures with SNL and MEF feeder cells were observed (Kim et al., 2014). In culture with SNL feeder cells, the deviation from the undifferentiated state occurred at the central region of the colony. In contrast, in culture with MEF feeder cells, the deviation from the undifferentiated state occurred at the peripheral region of the colony. Later, it was suggested that anomalous low and high migration rate at the central and peripheral region, respectively, led to deviation from the undifferentiated state in hiPSC colonies (Shuzui et al., 2019). Based on this hypothesis, we have developed a model in order to understand more deeply about these phenomena.
Our model described several cell behaviors including cell division, contact inhibition, cell migration, cell – cell interaction, cell – substrate interaction, and cell deviation. Using the model to understand the spatial heterogeneity of cell movement rate in colony, we explored that cell division was main factor that led to higher movement rate at the peripheral region than that at the central region of colony. The simulation results indicated that the model was able to reproduce the deviation from the undifferentiated state similar to the in vitro observation. The result also partially confirmed the in vitro hypothesis that stated anomalous cell migration triggered the deviation from the undifferentiated state.