Columns Of Different Diameters Research Articles

PlasmaCap EBA: An innovative method of isolating plasma proteins from human plasma.

The growing demand for immunoglobulin (IG) requires development of improved plasma fractionation methods to provide higher yields in a cost effective, scalable manner without compromising product purity and efficacy. A novel protein extraction method, utilizing expanded bed adsorption (EBA) chromatography, has been developed. PlasmaCap IG (10% liquid formulation intravenous IG [IVIG]) is the first plasma-derived product manufactured using PlasmaCap EBA technology. The PlasmaCap EBA platform consists of a series of consecutive columns which bind a target protein, or group of proteins, in their native state directly from cryo-poor plasma. EBA chromatography includes five key steps: (1) expand, (2) sanitize and equilibrate, (3) load, (4) wash and (5) elute. These steps are made possible using high-density tungsten-carbide agarose beads, suspended by upward flow. The PlasmaCap EBA process was evaluated during Evolve's clinical campaign for scalability, product quality and yield. PlasmaCap EBA technology can be predictably scaled by maintaining the minimum residence time and residence time distribution for EBA columns of different diameters. Scalability of the manufacturing process was demonstrated by the 50-fold volumetric increase from laboratory-scale lots to clinical-scale lots. The process is also associated with enhanced product purity, such as lower aggregates. The PlasmaCap EBA process is expected to have the same or better yield and purity at commercial scale production compared to the clinical campaign. The PlasmaCap EBA platform was used to successfully develop PlasmaCap IG (10% liquid formulation IVIG) with proven scalability, product quality and yield.

Efficient Shortcut Method for Determining the Process Window in Stirred‐Pulsed Extraction Columns

AbstractRecent studies showed the superior separation performance of stirred‐pulsed columns of different diameters in liquid‐liquid extraction processes. Here, an efficient shortcut method will be presented, which is time and resource‐efficient as well as cost‐effective to determine the operational window of these columns for industrial separation tasks. Savings in time of less experiments and costs of materials consumption can be estimated with up to 30 %. The presented method is particularly suitable before the application of new chemical systems, which are particularly cost‐intensive and scarce in material supply.

Study on the effect of temperature on the gas–liquid mass transfer rate of volatile liquid

Abstract The high volatility liquids in industrial production are easily vaporized and diffuses into the workplace, posing a hazard. The volatility liquid gas–liquid mass transfer rate is calculated based on the mass loss measured in experiments. In this paper, the relation between the gas–liquid mass transfer rate and the liquid temperature and air flow rate above the liquid is analysed. Based on the gas–liquid mass transfer rate model proposed by Donald Mackay, combined with Maxwell’s rate distribution law, a new temperature correction term was proposed to correct Mackay’s gas–liquid mass transfer theory. The results show that the higher the liquid temperature of n -pentane is, the higher the air flow rate above the liquid surface and the higher the gas–liquid mass transfer rate are. According to the experimental results, the temperature correction term coefficient is 0.560, and the variance is 0.011. A corrected gas–liquid mass transfer rate calculation model is obtained. Vertical flow liquid column gas–liquid transfer experiments are conducted, and the temperature and temperature change before and after the experiments are obtained for liquid columns of different diameters. The difference between the new model calculation results and the experimental values is no more than 4.20%. The model error of the gas–liquid mass transfer rate calculation model after temperature correction is small. Graphic abstract The mass loss of the n -pentane liquid pool in the air passage was measured by experiment, and the gas–liquid mass transfer rate was obtained. The influence of temperature on mass transfer rate is proposed. Combined with Mackay’s gas–liquid mass transfer theory, a new gas–liquid mass transfer rate calculation method is obtained, and its correctness is verified by experiments.

Hydraulic and mass transfer performances of a commercial hybrid packing: The RSP200X — Key modelling parameters for gas treatment applications

The RSP200X, as one of the latest generation of Raschig’s structured packings (Raschig Super-Pak, RSP), has been investigated for use in scrubbing columns operating at high liquid loads where it could be particularly well adapted. These RSP packings offer a good potential for increasing capacity while maintaining mass transfer efficiencies at high levels. IFPEN has measured hydraulic and mass transfer performances in two columns of different diameters (146mm and 1000mm). Flooding limits were in agreement with literature, however at high liquid loads and for the tested X-Style RSP they were 30–40% lower than those calculated with the Winsorp Software delivered by Raschig. With the support of the present results a modified version of Winsorp has been elaborated for high liquid loads and X-Style RSP. In terms of mass transfer, the CO2/MDEA system was used to measure kLae while the classic CO2/NaOH and SO2/NaOH systems were used for ae and kGae measurements. The RSP200X was found to develop a high interfacial area compared to its geometric area. While for standard packings the gas flow rate is often considered to have only a small effect on effective area when operating below the loading point, its effect measured on RSP200X is significant and of the same order as for liquid load. Measurements of kLa and kGa further confirm these trends.

A probabilistic heat transfer model for turbulent fluidized beds

A probabilistic heat transfer model was developed that allows for the gradual evolution of bed-to-surface heat transfer coefficients with increasing superficial gas velocity when bubbling and turbulent flow structures co-exist. The model is based on the packet renewal theory and the probability of particle packets for the specific hydrodynamic regime adjacent to the heat transfer surface. Assuming distinctive two-phase flow, dense packets at minimum fluidization voidage and voids almost free of particles, causes the heat transfer coefficients to be underestimated in the turbulent flow regime. By allowing for contributions of structures of intermediate voidage that reflect typical behavior in the turbulent flow regime of fluidization, heat transfer predictions are improved significantly. The resulting model is shown to give good agreement with experimental heat transfer data for fluidized beds of FCC and Alumina particles, changing smoothly from one flow regime to another in columns of different diameters and from the core of the bed to the wall.

Multiscale modeling of fixed-bed reactors with porous (open-cell foam) non-spherical particles: Hydrodynamics

An accurate numerical model is proposed to simulate flow through cylindrical fixed-bed reactors with randomly packed porous non-spherical particles. The length scale for flow outside the porous particles (made of open-cell foam) is O(102) higher than the size of the internal micro-pores of the particles. To capture the flow at these two different length scales, a multiscale modeling approach, derived using volume averaging theory (VAT), is developed. The flow through and around the porous particles is computed as a single hydrodynamic field in a Cartesian computational domain. The flow within the inter-particle space is fully resolved, whereas, flow at the scale of the intra-particle micro-pores is not resolved and instead represented by closure terms. Random packings of cubic and cuboid particles in cylindrical columns of different diameter are generated using a glued-sphere Discrete Element Method (DEM) approach. The packing structures for different particle-column combinations are analysed. The effects of particle size/shape, column diameter and internal porosity of the particles on the overall pressure drop and flow distribution are investigated. The macroscopic Reynolds number (based on the particle equivalent diameter and the superficial velocity of the bed) is varied from 0.1 to 400. The effect of Reynolds number on pressure drop is analyzed, as well as the reduction in pressure drop due to the presence of the intra-particle pores. In addition, our numerical simulations have helped to elucidate the detailed fluid-solid interaction in complex bi-disperse, dual porosity porous media.

Treatment of Soil Swelling Using Geogrid Reinforced Columns

In this paper, a method of treatment of swelling of expansive soil is presented. The method is simply based on the embedment of a geogrid (or a geomesh) in the soil. The geogrid is extended continuously inside the volume of soil where the swell is required to be controlled and orientated in the direction of swell. Soils with different swelling potentials are employed; bentonite “which is mainly composed of montmorillonite” base-Na and bentonite base-Ca in addition to kaolinite mixed with bentonite. To investigate the swell, swell-partial shrinkage and other phenomena for untreated soils in comparison with their counterparts treated soils, small scale tests were carried out in ASTM CBR (California Bearing-Ratio) mould. Each soil sample was compacted at dry side of the compaction curve using static compaction test. Swelling and consolidation tests were carried out on each sample. Geogrid columns of different diameters; 20, 30 and 50 mm were inserted through the swelling soil and filled either with the same clay or with sand. A considerable effect of geogrid was observed on the restriction of swelling in the soil. The dependence of swell on reinforcement stiffness substantiates the anticipation that soil-reinforcement bond would be so strong that the clay cannot expand unless the reinforcement is extended. Swell increases with the column diameter. The gradual increase in the diameter of geogrid reinforced column provides the cylinder with the largest surface area that supports the increase of the interlocking interface with the soil. Using sand as a fill material in the geogrid reinforced columns is more effective than using the same treated soil since sand is more permeable and less compressible than clays.

Micro scale self-interaction chromatography of proteins: A mAb case-study

Self-interaction chromatography is known to be a fast, automated and promising experimental technique for determination of B22, but with the primary disadvantage of needing a significant amount of protein (>50mg). This requirement compromises its usage as a technique for the early screening of new biotherapeutic candidates. A new scaled down SIC method has been evaluated here using a number of micro LC columns of different diameters and lengths, using typically 10 times less stationary phase than traditional SIC. Scale-down was successfully accomplished using these micro-columns, where the SIC results for a range of differing columns sizes were in agreement, as reflected by k′, B22 and column volumes data. The results reported here demonstrate that a scaled down version of SIC can be easily implemented using conventional liquid chromatography system where the final amount of mAbs used was 10 times less than required by conventional SIC methodologies.

Porous structure of the monolithic sorbent and separation properties of monolithic capillary columns in gas and liquid chromatography

Macroporous polymer based on polydivinylbenzene was used for the preparation of monolithic capillary columns with the diameter from 0.01 to 0.53 mm for separations by gas and liquid chromatography. The separation properties of the columns were studied by analysis of model systems of aromatic (in liquid chromatography) and light (in gas chromatography) hydrocarbons. The permeability was determined and the C parameter of the Van-Deemter equation was found for each column. The permeability of the majority of columns determined by gas chromatography is independent of the column diameter. The permeability of the same columns in liquid chromatography is also almost constant for the columns 0.53–0.1 mm in diameter; however, the permeability decreases sharply on going to columns of smaller diameter. In gas chromatography the value of the C parameter reflecting the effect of the mass transfer of the sorbate between the mobile and stationary phases on the smearing of a chromatographic peak in the column approximately the same for all columns. In liquid chromatography the value of the C coefficient in the Van-Deemter equation for the same capillary columns changes with a change in the column diameter and reaches a minimum for the columns 0.1 mm in diameter. The differences observed for the characteristics of the columns in gas and liquid chromatography are due to different structures of the macroporous monolith formed in columns of different diameter and to the effect of solvation of the monolith by the mobile phase under the conditions of liquid chromatography.

Three‐dimensional simulation of bubble column flows with bubble coalescence and breakup

AbstractThree‐dimensional (3‐D) Euler/Euler simulations of two‐phase (gas/liquid) transient flow were performed using a multiphase flow algorithm based on the finite‐volume method. These numerical simulations cover laboratory‐scale bubble columns of different diameters, operated over a range of superficial gas velocities in the churn‐turbulent regime (8 to 30 cm/s) and at different operating pressures (up to 1 MPa). The bubble population balance equation (BPBE) is implemented in the two‐fluid model (TFM) and algebraic slip mixture model (ASMM). Simulated time‐averaged axial liquid velocity, turbulence stress, and gas holdup are compared with experimental data of Chen et al., Ong, and Shaikh et al. Moreover, to ensure the experimentally observed lack of dependency of holdup radial profiles on column height in the fully developed region, coalescence rates in the computations had to be enhanced consistently compared to model‐predicted values. Quantitative agreement is then obtained between the experimental data and simulations for the time‐averaged gas holdup and axial liquid velocity profiles. However, the simulations significantly underestimate the turbulent stress because the velocity field cannot be fully resolved. Simulated bubble size distributions indicate that the volume fraction of small bubbles is uniform in a cross section, whereas that of the large bubbles peaks in the center of the column. The simulation correctly captures the high‐pressure effect, which at fixed gas superficial velocity pushes the bubble column flow toward bubbly flow. The simulation also predicts that, although the small bubble volume fraction may not change with superficial gas velocity in the churn‐turbulent flow regime, the bubble size distribution still remains single modal but is wider and contains larger bubble sizes when superficial gas velocity is increased. © 2005 American Institute of Chemical Engineers AIChE J, 51: 696–712, 2005

The effects of operating conditions on the pressure variation at the bottom of a 16.6 cm i.d. reciprocating plate column

The effects of the intensity of vibration, superficial gas velocity, content of solid particles and rheology of the liquid phase on the total and time-averaged pressure variation at the bottom of a 16.6 cm i.d. reciprocating plate column were studied. The total and time-averaged pressure variation at the column bottom were found to increase with increasing vibration intensity, liquid viscosity and content of solid particles, but to decrease with increasing superficial gas velocity. The pressure variation at the column bottom was greater in the column filled with CMC solutions than in the one with distilled water. The pressure variation at the column bottom was correlated with the vibration intensity and the liquid phase hold-up. The pressure variations at the bottom of columns of different diameter were also compared. The orifice coefficient for plates of approximately the same free fraction area was found to decrease with increasing column diameter.

Numerical simulation of bubble columns flows: effect of different breakup and coalescence closures

Two-dimensional axisymmetric Eulerian/Eulerian simulations of two-phase (gas/liquid) transient flow were performed using a multiphase flow algorithm based on the finite-volume method. These numerical simulations cover laboratory scale bubble columns of different diameters, operated over a range of superficial gas velocities ranging from the bubbly to the churn turbulent regime. The bubble population balance equation (BPBE) is implemented in the two-fluid model that accounts for the drag force and employs the modified k – ε turbulence model in the liquid phase. Several available bubble breakup and coalescence closures are tested. Quantitative agreements between the experimental data and simulations are obtained for the time-averaged axial liquid velocity profiles, as well as for the kinetic energy profiles, only when model predicted breakup rate is increased by a factor of ten to match the coalescence rate. The calculated time-averaged gas holdup profiles deviate in shape from the measured ones and suggest that full three-dimensional simulation is needed. Implementation of BPBE leads to better agreement with data, especially in the churn-turbulent flow regime, compared to the simulation based on an estimated constant mean bubble diameter. Differences in the predicted interfacial area density, with and without BPBE implementation, are significant. The choice of bubble breakup and coalescence closure does not have a significant impact on the simulated results as long as the magnitude of breakup is increased tenfold.

Prediction of gas chromatographic retention times of capillary columns of different inside diameters

AbstractThe retention times (t R) of n‐alkanes (C16–C22) eluted from capillary columns of different diameters are accurately predicted by using the equation proposed by Krisnangkura et al. (J. Chromatogr. Sci. 1997, 35, 329–332). The numerical values of four thermodynamically related constants (a, b, c, and d) of the BP‐1 (100% dimethylpolysiloxane) capillary column (0.32 mm ID×25 m, film thickness, 0.25 μm) are –6.169, –0.512, 226.98, and 410.30, respectively. For columns of the same stationary phase but of different inside diameters and film thickness, accurate tR values can be predicted by using the same numerical values of the last three constants but the first constant (a) is changed by the difference in the natural logarithm of the column phase ratios (β). All the derived numerical values of each column were tested with FAMEs and with n‐alkanes in temperature‐programmed GC (TPGC). All the predicted tR values agree well with the experimental values. About 77% of the TPGC data have errors lower than 0.5% and the largest value is –1.04%.

Generalized dynamic modeling of local heat transfer in bubble columns

Instantaneous local heat transfer rates were measured by using a hot-wire probe in three bubble columns of different diameters of 200, 400 and 800 mm. The time series of heat transfer rates were analyzed by means of rescaled range ( R/ S) and deterministic chaos analyses. Due to the influence of highly chaotic bubble motions, the instantaneous local heat transfer exhibits low-dimensional chaotic features. The dependences of Hurst exponents and Kolmogorov entropy on the column scale consistently suggest different nonlinear hydrodynamic behaviors exist in bubble columns of different scales. Based on the measurement of instantaneous heat transfer rates, an artificial neural network (ANN) was applied to correlate instantaneous local heat transfer with dynamic motions of bubble and liquid. The ANN was optimized and trained by only using the experimental data measured at one location of 200 mm column. The trained ANN model shows good performance for the generalized use to predict the dynamic heat transfer rate in three columns over whole experimental conditions studied, indicating the ANN is capable of capturing the universal relation between instantaneous heat transfer and local bubble dynamics.

Generalized dynamic modeling of local heat transfer in bubble columns

Instantaneous local heat transfer rates were measured by using a hot-wire probe in three bubble columns of different diameters of 200, 400 and 800 mm. The time series of heat transfer rates were analyzed by means of rescaled range (R/S) and deterministic chaos analyses. Due to the influence of highly chaotic bubble motions, the instantaneous local heat transfer exhibits low-dimensional chaotic features. The dependences of Hurst exponents and Kolmogorov entropy on the column scale consistently suggest different nonlinear hydrodynamic behaviors exist in bubble columns of different scales. Based on the measurement of instantaneous heat transfer rates, an artificial neural network (ANN) was applied to correlate instantaneous local heat transfer with dynamic motions of bubble and liquid. The ANN was optimized and trained by only using the experimental data measured at one location of 200 mm column. The trained ANN model shows good performance for the generalized use to predict the dynamic heat transfer rate in three columns over whole experimental conditions studied, indicating the ANN is capable of capturing the universal relation between instantaneous heat transfer and local bubble dynamics.

Butyl acrylate porous polymer monoliths in fused-silica capillaries for use in capillary electrochromatography

Capillary electrochromatography incorporates features of both capillary electrophoresis and liquid chromatography. Butyl acrylate polymers, cast in-situ with heat initiated polymerization and no retaining frits have been made. Van Deemter plots of chrysene have been examined at a variety of operating temperatures to examine column behavior. H min moves to faster flow-rates and increases slightly in magnitude as temperature is increased. The longevity and reproducibility of the columns have been examined with a homologous series. Performance is very reproducible between two different columns of different diameters, operated on different systems and prepared from the same polymeriation batch. The relative standard deviation of retention factors is a maximum of 3.1% with most values calculated at less than 1%. The uniformity of the polymers as a function of length has also been studied with a series of polycyclic aromatic hydrocarbons, and the columns have proved to be very uniform across their length as measured by the consistency of retention factors with a maximum relative standard deviation of 3.4% and most values calculated between 1 and 2%. Plate numbers of between 65 000 and 80 000 plates/m have been attained for compounds with retention factors of 3 to 12. These columns have proved easy to make, are quite reproducible, and long lived.

Effect of a new high porosity packing on hydrodynamics of bubble columns

The purpose of this work was to study the effect of a new high porosity packing (solid fraction corresponds to 0.5%) on the hydrodynamics of two bubble columns of different diameters (15 and 20 cm) operating with co-current up-flow of gas and liquid. This specific packing is a stainless steel welded grid with a mesh size of 12.5 mm. Two types of gas sparger were used. Gas hold up, gas hold up profiles bubble size, slip velocity and liquid axial dispersion coefficients were determined with and without packing. The results obtained show that this type of packing has a considerable effect: it delays regime transition and can maintain a homogeneous regime over a large range of superficial gas velocities. Liquid axial mixing was also greatly affected by the presence of this packing, tending toward plug flow.

Design and scale-up methodology for multi-phase reactors based on non-linear dynamics

Multi-phase reactors exhibit chaotic behaviors due to the highly turbulent motions of bubbles and phase interactions, leading to the formation of a complex spatio-temporal flow structure. The instantaneous motions of bubbles and wakes were studied by local measurements of bubble and particle-velocity fluctuations, bubble–wake structure, bubble shape and orientation. The chaotic dynamics of bubble and particle motions in multi-phase reactors were characterized in terms of the correlation dimension obtained by the deterministic chaos analysis for the series of time intervals between successive bubbles or particles by means of the embedding method. Three different methods, the deterministic chaos analysis, the short-term predictability analysis and the rescaled range (R/S) analysis, were applied to the non-linear dynamics of multi-phase reactors. The scale-up effect in the dynamic behavior of multi-phase reactors was investigated by using columns of different diameters. In addition, the non-linear hydrodynamic motions of bubbles and particles in multi-phase reactors have been modeled by means of an ANN (Artificial Neural Network) trained with time series data of voidage fluctuations for gas and solid phases. By successively adapting its output to input, the ANN can generate time-series data for any superficial gas velocity. The bifurcation diagrams of both bubble and particle motions generated by the trained ANN demonstrated that the ANN is capable of predicting and modeling the chaotic dynamics of multi-phase reactors.

Counterflow Isotachophoresis−Capillary Zone Electrophoresis on Directly Coupled Columns of Different Diameters

Counterflow isotachophoresis−capillary zone electrophoresis (ITP−CZE) on directly coupled columns of different diameters was explored to increase the injection volume and lower the detection limits in CZE. A solution of neostigmine bromide and propantheline bromide was used to evaluate the system; the relative standard deviations for four injections of 3.3 μL of 0.1 μM neostigmine bromide and propantheline bromide were 1.4 and 4.0%, respectively. The correlation coefficients for volumetric calibration curves over the range of 1.7−8.3 μL of the neostigmine bromide and propantheline bromide solution were 0.9979 and 0.9975, respectively, and a 2.5 nM solution could be detected easily from 8.3 μL of sample. Approximately 40 min was required for focusing.

A study of the bubble-to-slug transition in vertical gas-liquid flow in columns of different diameter

The aim of this study is to investigate the structure of upwards air-water flow and its variation as the bubble-to-slug transition is approached, with a view to understanding the mechanism of the transition. The development of bubble size with column height is measured with a double needle resistivity probe, and of void fraction waves with an Impedance Void Fraction Meter (IVFM) with quadrant electrodes in a 150 mm diameter column. The results are compared with some experimental data gathered in a 28.9 mm column. Traditional slug flow does not exist in the 150 mm diameter column; instead there is a gradual transition to churn flow. Possible instabilities of void fraction waves are detected during the transition from bubble to churn at constant liquid rate, but not at constant gas rate. In the 28.9 mm column at constant liquid rate, an abrupt transition from bubble-to-slug flow occurs, with strong indications of associated void fraction wave instabilities.