A rate-based model for reactive separation columns with sandwich packings

For the safety analysis of deep underground structures (power station or hydropower station), the dynamic response of reactive powder concrete (RPC)-filled steel tubular (FST) column (RPC-FST column) subjected to blast loading is investigated by using LS-DYNA. The numerical model of RPC-FST column is developed in LS-DYNA, with appropriate boundary conditions being applied. The material model ‘*MAT_CONCRETE_DAMAGE_REL3 (K&C model)’ has been employed to simulate the dynamic responses of RPC, and the material model ‘*MAT_PLASTIC_KINEMATIC (kinematic plastic model)’ has been adopted for the modelling of steel tube. Experimental data from a blasting experiment has been applied to validate the numerical simulations. Numerical results show that, overall deformation of the RPC-FST column is small, and its plastic strain mainly concentrated near the support and the mid-span. The modelling maximum displacements are in good agreement with experimental results, while the residual displacements are slightly larger than experimental data. This discrepancy is reasonable and acceptable in engineering practices. The modelling results presented in this study would be used as a reference for anti-blasting engineering practice for deep underground projects.

Development of a dynamic nonequilibrium cell model for reactive distillation tray columns

To obtain the seismic behavior of glass fiber reinforced polymer (GFRP) tube reactive powder concrete composite columns with encased steel (GRS), a total of 17 full-scale GRS columns were designed in this paper. The parametric studies were conducted to explore the influence of factors such as the diameter of GFRP tube (D), thickness of GFRP tube (t), number of fiber winding layers (n), fiber winding angle (θ), axial compression ratio (λ), compressive strength of reactive powder concrete (fc), the area of encased steel (As) and strength of encased steel (fsy) on the seismic behavior of the composite columns. The finite element models of this kind of columns were established by ABAQUS finite element software, and the seismic behavior analysis for GRS composite columns was carried out. The results show that all the specimens exhibit good ductility and strong deformation ability. The stiffness degradation of specimens significantly slow down with increasing of D, fsy and λ. The energy dissipation capacity of specimens can be improved by increasing of D and λ, while the increasing of As and fsy leads to the decreasing of the energy dissipation capacity. By observing the failure mode of such composite columns, local bulging occurs in the foot area of the columns. Based on the statistical analysis of the calculated results, the restoring force models for GRS composite columns are proposed, which agree well with the simulated results. The restoring force models can provide reference for the elastic-plastic seismic response analysis of this kind of composite columns.

To obtain the seismic behavior of glass fiber reinforced polymer (GFRP) tube reactive powder concrete composite columns with encased steel (GRS), a total of 17 full-scale GRS columns were designed in this paper. The parametric studies were conducted to explore the influence of factors such as the diameter of GFRP tube (D), thickness of GFRP tube (t), number of fiber winding layers (n), fiber winding angle (θ), axial compression ratio (λ), compressive strength of reactive powder concrete (fc), the area of encased steel (As) and strength of encased steel (fsy) on the seismic behavior of the composite columns. The finite element models of this kind of columns were established by ABAQUS finite element software, and the seismic behavior analysis for GRS composite columns was carried out. The results show that all the specimens exhibit good ductility and strong deformation ability. The stiffness degradation of specimens significantly slow down with increasing of D, fsy and λ. The energy dissipation capacity of specimens can be improved by increasing of D and λ, while the increasing of As and fsy leads to the decreasing of the energy dissipation capacity. By observing the failure mode of such composite columns, local bulging occurs in the foot area of the columns. Based on the statistical analysis of the calculated results, the restoring force models for GRS composite columns are proposed, which agree well with the simulated results. The restoring force models can provide reference for the elastic-plastic seismic response analysis of this kind of composite columns.

Nitrogen oxides emitted from power plants and the chemical industry are poisonous to humans and animals, contribute to ozone depletion, and cause acid rain. More than 90% of nitrogen oxides (NOx) consist of nitric oxide (NO), which is insoluble in water. Among the various available techniques of NOx abatement, ozone injection is a promising method in which NO is oxidized to higher-order nitrogen oxides (NO3, N2O3, N2O4, and N2O5), which can easily be absorbed in a wet scrubber. In this article, the ozone injection process integrated with an absorber column is numerically modeled and simulated at various operating conditions. The predicted results of NOx oxidation with ozone injection and absorption in water agree with the published experimental results. The ozone injection process is modeled using a plug flow reactor, while the wet absorption is based on a rigorous rate-based RateFrac model. Detailed kinetic mechanisms of O3-NOx oxidation and absorption of nitrogen oxides in water are incorporated in the model to simultaneously predict the performance efficiency of the ozone reactor and absorber column. Thermodynamic properties of the components are estimated using an Electrolyte NRTL model. The influence of performance parameters (such as feed gas flow rate, inlet gas temperature, reactor configurations, ozone concentration, and NO/NO2 molar ratio) on the oxidation efficiency of NOx in the reactor and absorber column is investigated to predict the optimal operating conditions.

Extended rate-based model validation for polyester synthesis by reactive distillation

Isotope separation columns are complex plants, with numerous input and output variables. Accurate but still simple mathematical models are necessary both in analysis and synthesis. The present paper deals with the mathematical model of the 18O separation column based on isotopic exchange between nitric oxides-nitric acid, operated at total reflux. The simulation results proves good accuracy.

The development of purification processes for protein biopharmaceuticals is challenging due to compressed development timelines, long experimental times, and the need to survey a large parameter space. Typical methods for development of a chromatography step evaluate several dozen chromatographic column runs to optimize the conditions. An efficient batch-binding method of screening chromatographic purification conditions in a 96-well format with a robotic liquid-handling system is described and evaluated. The system dispenses slurries of chromatographic resins into filter plates, which are then equilibrated, loaded with protein, washed and eluted. This paper evaluates factors influencing the performance of this high-throughput screening technique, including the reproducibility of the aliquotted resin volume, the contact time of the solution and resin during mixing, and the volume of liquid carried over in the resin bed after centrifugal evacuation. These factors led to the optimization of a batch-binding technique utilizing either 50 or 100 microL of resin in each well, the selection of an industrially relevant incubation time of 20 min, and the quantitation of the hold-up volume, which was as much as one quarter of the total volume added to each well. The results from the batch-binding method compared favorably to chromatographic column separation steps for a cGMP protein purification process utilizing both hydrophobic interaction and anion-exchange steps. These high-throughput screening tools can be combined with additional studies on the kinetics and thermodynamics of protein-resin interactions to provide fundamental information which is useful for defining and optimizing chromatographic separations steps.

Circulation in bubble columns, such as those used in fischer-tropsch synthesis, detracts from their performance in that gas is carried on average more rapidly through the column, and the residence time distribution of the gas in the column is widened. Both of these factors influence mass-transfer operations in bubble columns. Circulation prediction and measurement has been undertaken using probes, one-dimensional models, laser Doppler velocimetry, and numerical modeling. Local void fraction was measured using resistance probes and a newly developed approach to determining air/water threshold voltage for the probe. A tall column of eight inch diameter was constructed of Plexiglas and the distributor plate was manufactured to distribute air evenly through the base of the column. Data were gathered throughout the volume at three different gas throughputs. Bubble velocities proved difficult to measure using twin probes with cross-correlation because of radial bubble movement. A series of three-dimensional mean and RMS bubble and liquid velocity measurements were also obtained for a turbulent flow in a laboratory model of a bubble column. These measurements have been made using a three-component laser Doppler velocimeter (LDV), to determine velocity distributions non-intrusively. Finally, the gas-liquid flow inside a vertically situated circular isothermal column reactor was simulated numerically. 74 refs., 170 figs., 5 tabs.

Multicompartment hydrodynamic model for slurry bubble columns

Catalytic Distillation for TAME Synthesis with Structured Catalytic Packings

The use of mobile control action allows the improvement of technical-economical characteristics of the rectification process and allows for operation regimes that can’t be achieved with traditional control approaches. Mobility lies in the ability to choose the movement law of compound source and energy in the spatial region of apparatus. Mobile control over the rectification process can be realized by changing the column feed point. An optimal number of feed trays must be determined with consideration of cost and output performance, and also the quality of the target product. The work aimed to develop a method for calculating optimal control action, including mobile ones, on the rectification process with additional account for the criterion of maximizing quality of target product, and also, comparison of static column profiles that are optimal by different criteria. Mathematical modeling of the rectification column for separation of water-methanol mixture revealed that increasing quality requirements to target products decreases the number of the optimal feed tray. A method was described for process optimization by the normalized criterion that accounts for separation quality and power consumption. The method was used to determine optimal values of traditional (flows of heat into the column's cube and phlegm) and mobile (feed tray number) control actions that provide the best technical-economical parameters of the rectification column. A proof is presented for the existence and uniqueness of solutions for this optimization problem and the effectiveness of using mobile actions for different requirements to target. The optimal temperature profile of the culms was studied and their characteristic features that correspond to different specific and normalized optimization criteria were found

Ion exchange recovery of rhenium from industrially relevant sulfate solutions: Single column separations and modeling

Reactive and hybrid separations of chemicals and bioactive substances: Modeling and optimization

Experimental and modeling of reactive separation of protocatechuic acid