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The uneven liquid distribution in the shell side of a spiral wound heat exchangers (SWHEs) significantly deteriorates heat transfer in liquefied natural gas (LNG) processes. In this study, an air and water mixture was employed as a substitute for the working fluid to simulate the two-phase flow conditions in practical LNG SWHEs. The experimental investigation focused on the impact of key factors, including gas fraction, flow rate, tube pitch, and layer pitch, on liquid distribution. The findings reveal that the liquid non-uniformity index initially decreases with an increase in gas fraction, reaching an optimal gas fraction of 0.4 for achieving better liquid distribution; the liquid distribution deteriorates at high flow rates under two-phase flow conditions; the liquid distribution improves with a sparser tube pitch under two-phase flow conditions; the liquid distribution deteriorates with a sparser tube pitch at low flow rate under two-phase flow conditions, while the difference diminishes at high flow rate. Recommendations include extending the intermediate vapor quality zone and maintaining lower flow rates for enhanced uniformity in liquid distribution across the shell side. Moreover, appropriately increasing the tube pitch or reducing the layer pitch can further optimize the uniformity of liquid distribution.

The aim of this paper is to study the changing law of filter media properties under high-pressure conditions, and for this purpose, an experimental setup was established to measure the properties of filter materials at a maximum pressure of 5 MPa. By observing the experimental phenomena produced under different pressures, combining the experimental data and experimental phenomena for qualitative and quantitative analyses, the filter media performance change pattern under different pressures was obtained. The experiments were carried out at a pressure of 1–5 MPa, and the detailed experiments were conducted on the pressure drop, saturation and the liquid distribution pattern of the first and last layers of the filter material. The experimental results show that the liquid film on the surface of the filter media becomes progressively thinner with increasing pressure, and the jump pressure drop becomes smaller while the saturation increases. The saturation of the first layer of the oleophilic filter media increased by 30% and the saturation of the last layer of the oleophobic filter media increased by 80% when the pressure was increased from 1 to 5 MPa. In addition, the results show that with increasing pressure, the surface tension of the droplets decreases and the surface tension of the DEHS decreases from 28.72 to 25.26 mN/m. The capillary force of filter media B was reduced from 0.20 to 0.13 mN, a 35% reduction in capillary force which changed the distribution of droplets on the fibres and enhanced the wettability of the filter material. This discovery is of great significance for understand ding the variation pattern of filter media performance under high-pressure conditions, and provides a basis for the design and manufacture of filter elements for high-pressure occasions. [ABSTRACT FROM AUTHOR]

This article introduces a technique to simulate the liquid flow inside different additively manufactured structured packings with enclosing column wall on laboratory scale using the software OpenFOAM. The physical problem is handled by means of a periodic setup and makes use of common numerical discretization techniques of the software. The periodic setup reduces the required computational resources while permitting simulations of the liquid distribution in a large part of the column even for complex packing structures. A novel post-processing tool is used for a systematic evaluation of the liquid distribution. When optimizing packing structures, these computational fluid dynamics simulations eliminate the necessity to manufacture every developed geometry. As a proof of concept, this work simulates the liquid flow inside two additively manufactured packing structures. The results are validated with experimental data and show, that an improved liquid distribution can be obtained inside laboratory-scale packing structures. [Display omitted] • CFD-simulation of the liquid flow in 3D-printed packings (D = 20 mm) with column wall. • Systematic evaluation of the resulting liquid distribution. • Validation of the simulation results using experimental data. • Development of a 3D-printed lab-scale packing with improved liquid distribution. [ABSTRACT FROM AUTHOR]

The bubble‐cap distributor is the most commonly used and critical internal for trickle bed reactors but holds the inherited disadvantage of liquid central aggregation when operating at a high gas–liquid ratio. A new bubble‐cap distributor with a streamlined downcomer was developed in this paper to counter back the liquid aggregation and improve its comprehensive performance. The effect of the streamline parameters of the new distributor on liquid distribution was systematically explored by the coupled Euler–Euler‐population balance equation (PBE) model. Compared with the classical and polyline converging–diverging structures, the results showed that the streamlined downcomer was a key to generating radial velocity of two‐phase flow and reducing the liquid central aggregation for the bubble‐cap distributor. The mechanism of well‐distribution was explored for the new distributor. Lower converging and diverging angles enhance the distribution performance. A downcomer with a small converging angle and a 30° diverging angle was recommended for dispersing the central aggregated liquid column and acquiring the high distribution uniformity and spray covering circle. These data would be helpful to the optimal design and scale‐up of the bubble‐cap distributor in further industrial applications. [ABSTRACT FROM AUTHOR]

In distillation, additive manufacturing can facilitate the design and fabrication of laboratory‐scale packed columns that overcome the existing miniaturization limits while maintaining scalability. Liquid distribution is one of the appraisal criteria for new packing structures. For this purpose, a flexible 3D‐printed laboratory test rig is presented. The setup offers a wide liquid load operation range from approx. 2.5 to 20 m3m−2h−1 for column diameters of 20–50 mm. First results regarding steady‐state development, initial liquid distribution effect and liquid load variation are shown using a 3D‐printed version of the Rombopak 9M in a 20‐mm diameter column. [ABSTRACT FROM AUTHOR]

A modular test rig is used to study the liquid distribution over the cross section at discrete locations along laboratory‐scale structured packings. Additively manufactured packing modules are stacked and connected with click joints. They are irrigated with a colored solvent, which leaves a colored flow path. The wetted cross‐section is optically evaluated in an automated process. The reversible connection of the modules allows the repetition of the experiments under identical test conditions. The simple and inexpensive setup provides an insight into the packings and quickly generates results that can be used to specifically improve packing structures with regard to their liquid distribution characteristics. [ABSTRACT FROM AUTHOR]

In this work, CFD-DEM simulations of two different fluidized bed granulator geometries were performed, aiming to provide an insight into how the injected liquid behaves within the particle bed and thus an overall better understanding of the granulation process itself. Simulation results were evaluated regarding the fate of sprayed droplets, e.g. deposition on a particle, elutriation from fluidized bed, or collision with apparatus walls. For the deposited droplets, the particle–droplet collisions were tracked in order to obtain a locally resolved deposition rate. Spray parameters as well as geometric specifications of the nozzle setup were varied, investigating a broad range of different process conditions. By optimizing apparatus design, especially the air inlet, an even distribution of the liquid droplets within the fluidized bed and overall higher deposition rate can be achieved and a stable steady state with a well-defined spray zone is reached within a broad range of varied spray parameters. [Display omitted] • A novel fluidized bed granulator geometry was investigated by means of CFD-DEM simulations. • Locally resolved droplet deposition rate as well as droplet fates were analyzed. • Reactor geometry significantly influences liquid distribution. • Detailed information of the deposition can help to detect local overwetting. [ABSTRACT FROM AUTHOR]

The article presents the results of modeling fluid distribution in mass transfer apparatuses with structured packing made of corrugated grid strips using the Poisson solution of the diffusion problem. Considering that the distribution of the fluid stops when the minimum flow rate of the liquid is reached, a numerical solution of the anisotropic diffusion model of the distribution of the liquid under multipoint spraying is obtained. The solutions of a diffusion model having unlimited distribution and one in which distribution ceases at achievement of minimum liquid flow rate coincide when the maximum flow rate exceeds the flow rate of the liquid at which the distribution stops by more than ten times. With an increase in the liquid distribution coefficients, other things being equal, the volume of the packing not wetted by the spray decreases. The simulation results are presented in the form of graphical dependencies that may be useful in the development of structured packing feeders, taking into account the anisotropy of their properties. [ABSTRACT FROM AUTHOR]

Experimental studies have revealed that liquid spreading in the layers of regular packings made of corrugated meshes depends on the macro- and microgeometry of the packings and obeys the anisotropic diffusion model. The implementation of corrugated strips with alternating triangular and trapezoidal corrugations increases the coefficients of liquid spreading both along and across the corrugated strips more than two-fold in comparison with the packing with only triangular corrugations. A method for calculating the coefficients of liquid spreading along and across the corrugated strips taking into account only the contact of corrugations has been developed. The calculated values are in satisfactory agreement with the experimental values of the liquid spreading across the corrugated strips, but there is a significant discrepancy with the experimental values of the liquid spreading along the corrugated strips, which is due to the effect of mesh micro-roughness and its capillary properties on the liquid spreading. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel distributor obtains better liquid distribution without pump pressure. • A CFD simulation was accurately validated by high-speed camera imaging. • The flow behavior of liquid jet impacting on the liquid distributor was studied. • The impacting angle between the liquid and the wire mesh packing was obtained. Rotating packed beds (RPBs) have been widely applied in multiphase systems. When handling some extreme operating condition systems, finding a suitable pump to provide pressure to force the feeding liquid to be evenly distributed by the distributor of the RPB is very costly. In this work, we designed new liquid distributors by using the kinetic energy of the rotating shaft as driving force to obtain uniform distribution. The performance of the liquid distribution has been investigated in terms of liquid flow behavior, liquid velocity, and impacting angle (α). Compared with bar and cantboard distributors, the radlamelle liquid distributor had the best distribution performance. By further optimization of the radlamelle structure, the left-hand wheel had better dispersion performance with α varying from 24.3 to 79.1°. This new liquid distributor without pump pressure expands the applications of the RPB in ultra-low or high temperature and high pressure operating conditions. [ABSTRACT FROM AUTHOR]

• Packing hydrodynamic performances as pressure drop and liquid holdup are investigated both experimentally and numerically. • 3D-printed packing replicas can be used as substitutes for CFD model validation, products defeaturing and lab experiments. • The research method in this manuscript can help optimise packing parameters and develop new products. Structured packings are widely used in oil & gas industries, as they can provide substantial surface area and high void fraction, thus enabling high mass transfer efficiency at a low pressure drop. This study investigates the hydrodynamic performance of two structured packings, namely, Mellapak 250Y and Montzpak B1−500. The pressure drop and liquid distribution are reported for a column of 200 mm diameter and 400 mm packing height. Wire-mesh sensor (WMS) is used to monitor the liquid distribution at the location of packing transitions. Packing replicas manufactured using a Fused Deposition Modelling (FDM) 3D printer is compared with commercial packings in terms of pressure drop and liquid distribution. A Computational Fluid Dynamics (CFD) model is initially validated using experimental data and then is used to investigate the effects of packing features, such as plate thickness, packing corrugation angles, holes, and packing transitions. The 3D-printed replicas show consistent performance compared to the commercial packings but can provide more information when measuring liquid distribution. The methodology and results discussed in this study can provide in-depth insights into the performance of structured packings, which is of critical importance when optimising packing parameters and testing new designs. [ABSTRACT FROM AUTHOR]

Liquid maldistribution is simulated with the TUM‐WelChem cell model for a Ø1,2 m packed column and compared with experimental data. The packing types Raflux ring 50‐5 metal, Hiflow® ring 50‐6 plastic and RVT metal saddle ring 50‐4 are investigated. Two calculation methods for lateral dispersion on each cell layer are used in the model: a sequential and a simultaneous method. A parity analysis and the interpretation of the relative deviation of the calculations from the experimental results provide insights into the assumptions and validity of the model. [ABSTRACT FROM AUTHOR]

• VOF model was established for typical structural unit in LiBr dehumidification tower. • The impact of fillers' structure and wettability on liquid distribution was studied. • The impact of operating parameters on liquid holdup was quantified. The uniform distribution of liquid phase on the packing surface is necessary for the dehumidification tower to maintain high dehumidification performance and efficiency. In this study, the effect of the packing properties and operating parameters on the liquid distribution of the packing surface is studied using a VOF method, the wetting ratio and liquid holdup of the packing were used as the evaluation indexes for the liquid distribution. The results show that the surface structure and wettability of corrugated packing have influence on the liquid distribution. The flow pattern of the liquid on the flat slat is mainly film flow. The lateral spreading of the liquid flow and the overall wettability on the fine corrugated slat are more effective than that on the flat slat due to the presence of granule ripples on the fine corrugated slat which increases the wettability of the packing , and the results in a gradual increase of the wetted area. However, even under ideal conditions, the liquid cannot wet the packing surface completely. As the inlet velocity of the gas increases(i.e., 0.617—1.85 m/s), the disturbance from the gas to the liquid phase increases and hinders the overall flow of the liquid which further increases the wetting ratio and liquid holdup. As the inlet velocity of the liquid increases (i.e., 0.057 m/s—0.11 m/s), the liquid film width of the filler surface gradually increases, the wetting ratio and liquid holdup increases significantly. The study provides guidance for the optimal design of the dehumidification tower and the design as well as selection of the packing in the tower. [ABSTRACT FROM AUTHOR]

Reliance on harmless and renewable resources to mitigate process environmental footprint has become increasingly important for the design and operation of sustainable processes. One challenge that is prevalent in marine water surface contamination concerns treatment and recovery from oil spills where efforts are needed to design emergency units adapted to marine conditions. Potential candidates are naturally-grown porous loofa (bio-foam) materials which can be integrated in floating units transportable to the contamination area. For this purpose, a hexapod platform motion simulator was employed to emulate sea-driven floating movements of a column packed with two loofa bio-foam packings (dense and open-cell samples) and operated in cocurrent gas-liquid upflow mode. The column hydrodynamic behaviour was monitored by means of capacitance wire mesh sensors and electrical capacitance tomography for various inclination and rolling parameters. In the case of dense bio-foam packing, the relatively even distribution of gas and liquid in the vertical bed tended to degrade as the bed tilted up to 15°. Column rolling prompted fluid displacements in bed crosswise planes inducing notable amplitude oscillations of the local liquid saturation. Kerosene exhibited a strong foaming behavior with promotion of earlier inception of pulsing flow as a function of column inclination as compared to water. [ABSTRACT FROM AUTHOR]

Shake flasks are still the most relevant experimental tool in the development of viscous fermentation processes. The phase number, which defines the onset of the unfavorable out‐of‐phase (OP) phenomenon in shake flasks, was previously defined via specific power input measurements. In the OP state, the bulk liquid no longer follows the orbital movement of the imposed centrifugal force, which is for example, detrimental to oxygen transfer. In this study, an optical fluorescence technique was used to measure the three‐dimensional liquid distribution in shake flasks. Four new optically derived evaluation criteria for the phase transition between the in‐phase and OP condition were established: (a) thickness of the liquid film left on the glass wall by the rotating bulk liquid, (b) relative slope of the leading edge of bulk liquid (LB) lines, (c) trend of the angular position of LB, and (d) very high angular position of the leading edge. In contrast to the previously applied power input measurements, the new optical evaluation criteria describe the phase transition in greater detailed. Instead of Ph = 1.26, a less conservative value of Ph = 0.91 is now suggested for the phase transfer, which implies a broader operating window for shake flask cultivations with higher viscosities. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Drainage layer significantly influenced the oil migration and distribution. • Oil film formed on the rear face of wettable fiber media but no on non-wettable media. • The interface was conducive to the oil drainage and distribution. • Separation performance was greatly affected by the liquid distribution uniformity. Abstract The effect of drainage layer on the pressure drop evolution, oil distribution and separation performance was investigated experimentally. The results showed that there existed obvious oil film on the rear face of wettable layer to cause a sharp jump in pressure drop. The interface between wettable coalescing media and non-wettable drainage layer could facilitate the drainage of coalesced oil and ameliorate the oil distribution density near the interface to improve the droplet capture probability. And because of the drainage function of the interface, the saturation of this kind of bed was lower. Oil distribution density in wettable drainage layer was relatively more uniform than that in the front coalescing layer, while in the bed only consisting of non-wettable media there existed a sparse zone of oil distribution in the lower half of the bed and this may be one reason for the low separation efficiency of non-wettable bed. A fiber bed with the arrangement of non-wettable drainage layer following behind wettable coalescing layer had the best overall separation performance. [ABSTRACT FROM AUTHOR]

In order to meet the requirements and well suit for in-situ process measurement of industrial scale gas-liquid mass transfer applications, such as natural gas processing and post-combustion carbon capture, electrical capacitance tomography (ECT) is used to analyse the distribution of a liquid phase across the packing of a counter current gas-liquid packed column and to quantify the liquid hold-up. The new method eliminates the requirement of a fully flooded reference calibration and only requires vacant and dry calibration steps. The calculation procedure is simplified by using a normal sensitivity matrix which does not include the packing information. The validity of the proposed method was confirmed through finite element method (FEM) analysis studies to certificate neither packing geometry nor orientation relative to the tomography probe nor had a significant impact on phase identification. An experiment is conducted on a counter current gas-liquid packed bed column with 190 mm diameter and polypropylene Sulzer Mellapak 250 Y as the packing. According to the experiment with various liquid load, the inclination angle of structured packing corrugation sheets has an impact on the radial distribution of liquid hold-up in the upper portions of packed beds and liquid hold-up fluctuations of ∼0.5% are observable below the flooding limit and even at no gas flow conditions which can meet the empirical correlations from literature. The experiment results show that the proposed method provides the confidence to use ECT in the industrial field service in gas-liquid packed column to provide the real-time liquid distribution and local liquid hold-up measurement. [ABSTRACT FROM AUTHOR]

Tray and packed columns are frequently used for the implementation of the unit operations rectification, absorption, and desorption. A maximized phase interface between gas and liquid in these devices is beneficial for mass transfer. Investigations on liquid maldistribution in random packings are conducted in a packed column at varying experimental and operating parameters in terms of type of packing, packing height, liquid distributor, liquid load, and gas load. Graphical presentations in form of distribution spectra and further evaluation by means of a maldistribution factor provide insight into the influence of different parameters on maldistribution. Liquid maldistribution in packed columns cannot be predicted adequately so far. Such maldistribution in random packing is experimentally investigated with varying experimental and operating parameters. Distribution spectra identify the maldistribution phenomena wall flow and liquid channeling. Evaluations by means of the maldistribution factor illustrate the degree of nonuniform distribution. [ABSTRACT FROM AUTHOR]

A 3-D computational fluid dynamics (CFD) model is presented to understand the influence of periodic operation in single phase packed bed reactors (PBRs). Unit cell approach is adopted to represent the packed bed with spherical particles having face centered cubic (FCC) and modified simple cubic (SC) packing arrangements. Three different on–off and min–max flow splits are analyzed and compared for single phase liquid flow operation. Comparison of results reveals the benefit of periodic mode in terms of homogeneous velocity distribution than that of the continuous mode operation. The effect is more pronounced at higher split ratios for FCC, and vice versa for modified SC arrangement. Moreover, on–off operation in both packing orientations exhibited a relatively better flow homogeneity as compared to min–max mode. Liquid distribution analysis indicates the improvement in flow homogeneity at the expense of a higher pressure drop in periodic operation. Single phase flow in packed beds finds several applications in heat transfer and reaction processes. This study essentially demonstrates the potential benefits of periodic operation to obtain homogeneous liquid distribution in packed beds with cubic close packing, which is of paramount importance in improving overall reactor performance. [ABSTRACT FROM AUTHOR]

In a 4-year ongoing research programme in the Netherlands, we focus to maximise spray deposition in pome fruit trees and minimise spray deposition underneath the trees on the ground and minimise spray drift. For a cross-flow fan orchard sprayer we therefore measured spray deposition in the tree as an effect of different air settings and nozzle types. Nozzle types chosen were the Albuz ATR lilac (as a reference) and the Albuz TVI8001, both sprayed at 7 bar spray pressure. The orchard sprayer was a Munckhof cross-flow fan sprayer with a 2.75 m high cross-flow construction on top of the axial fan, equipped with 8 nozzles on both sides. At a forward speed of 6.5 km/h the spray volume was 200 L/ha and 290 L/ha, for respectively the Albuz lilac and Albuz TVI8001 nozzles. Air settings were: High air setting - 540 rpm PTO; and Low air setting - 540 rpm, 400 rpm, and 300 rpm PTO. Liquid distributions were measured with an AAMS-Salvarani Vertical patternator with discs, and air distribution was measured with a self-constructed measuring device equipped with ultrasonic anemometers and a handheld vane-anemometer. Liquid distribution in the apple trees (cv. Elstar) was measured in the full leaf growing stage (following ISO 22522). First results show a good correlation between air distribution and liquid distribution. Vertical liquid distribution measured on the liquid measuring device correlates also very good with the liquid distribution at different heights in the tree. However, air distribution and especially air speed of the orchard sprayer showed that decreasing air assistance increased the spray deposition in the fruit trees. Showing that air assistance is an important parameter to be taken up in the advice to fruit growers. [ABSTRACT FROM AUTHOR]

The effect of 2 fat application sites (FAS) and 2 levels of fines on feed manufacturing parameters and broiler live performance from 16 to 42 d was studied. The FAS included mixeradded fat (MAF) and post-pellet liquid application (PPLA) of fat. While the MAF diets had all fat added to the diet prior to pelleting, the PPLA diets were pelleted with 0.5% MAF, and the remaining 3.5% fat was added subsequent to pellet cooling. The levels of fines included 0 and 30%. A total of 32 pens was placed with 8 males and 8 females (mixed-sex) in each pen. Broiler chicks were fed a common crumbled starter for approximately 16 d and then transitioned to one of the 4 dietary treatments. The PPLA pellets were more durable than were MAF pellets (P < 0.01), but required more energy to pellet (P < 0.01). When adding liquid fat post pellet to the diets with 30% fines, the fines absorbed more liquid fat and exhibited a greater gross energy when compared to pellets (P < 0.01). Male broilers consuming the PPLA diets were 50, 97, and 120 g heavier than male broilers consuming the MAF diets at 28, 35, and 42 d, respectively (P < 0.01). Female broilers consuming the PPLA diets with 30% fines were 71 and 90 g heavier than female broilers consuming the MAF diets with 30% fines at 28 and 35 d, respectively (P < 0.05). It was concluded that the females may have benefited from consuming high-energy-density fines present in the PPLA diets with 30% fines when compared to females consumingMAF diets with 30% fines because the additional fat that coated the fines offset the negative energy associated with prehension of the fines. [ABSTRACT FROM AUTHOR]

Rotating packed beds (RPBs) offer the possibility to intensify mass transfer processes by combining large throughputs with a compact design. To design and dimension RPBs, fundamental knowledge about the hydrodynamics and the operating limits is mandatory. In the present work, the results of experimentally determined upper operating limits for a pilot scale RPB are presented. The upper operating limits were identified visually by the entrainment of liquid towards the gas outlet of the RPB. Gas capacity factors of up to 3.4 Pa 0.5 and liquid loads of up to 51 m 3 m −2 h −1 were investigated. At these operating conditions a stable operation of the RPB was possible using a full jet nozzle. Changing the nozzle type to flat fan nozzle decreased the upper operating limit significantly. In addition two different packings, a knit mesh and metal foam, were investigated. The influence of the packing materials on the upper operating limit was found to be of minor importance. A comparison of the own experimental data with literature data indicates, that not all of the operating limits reported in the literature may reflect the maximum operating limits that are achievable in RPBs. [ABSTRACT FROM AUTHOR]

Investigations on liquid maldistribution in random packings are conducted in a Ø1.2 m packed column at varying experimental and operating parameters - type of packing, packing height, liquid distributor, liquid load, and gas load. Used types of packing are metal Raflux-Rings 35-5 and 50-5, RVT Metal Saddle Rings 70-5 and plastic Hiflow®-Rings 50-6. Graphical presentation in form of distribution spectra and further evaluation by means of a maldistribution factor provide insight into the influence of different parameters on maldistribution. [ABSTRACT FROM AUTHOR]

Liquid distribution in a pilot-scale packed column under offshore conditions was experimentally measured and investigated. An experimental column with an inner diameter of 0.4 m and a packed height of 4 m was built on a sloshing machine that can simulate offshore conditions. A method of electrical resistance tomography combined with electrical impedance and diffuse optical tomography reconstruction software (ERT-EIDORS) was proposed and used to simultaneously measure the liquid distribution at multiple axial positions in the packed column. Validation experiments for the reliability of the ERT-EIDORS method were conducted first. Then the effects of the liquid load, gas factor, and liquid properties on the liquid distribution were investigated under various offshore conditions using the proposed method. For offshore conditions, three permanent tilt angles and four roll motions were considered. The results are presented in terms of the maldistribution factor in most cases and also the 3D plot for selected demonstration cases. [ABSTRACT FROM AUTHOR]

Fluid Coking™ is a non-catalytic carbon rejection process that is utilized to convert petroleum residues into more valuable light and middle distillates. In this process, heavy oil is sprayed into a fluidized bed of hot coke particles; the liquid heats up and undergoes endothermic thermal cracking to vapors, non-condensable gas and solid coke. This study shows that liquid distribution on hot coke particles affects the products yields and the liquid product quality. The vapor residence time also affects the products yields and the liquid product quality. The Mechanically Fluidized Reactor has been successfully developed and implemented for Fluid Coking applications. Multiple vapor phase residence times can be investigated simultaneously while reducing intrinsic errors present in a complex system such as coking. The impact of applied bed mixing and vapor phase cracking on Fluid Coking yields, as well as on product oil quality can, thus, be accurately evaluated. Applying mechanical mixing to the bed of coke particles results in better liquid distribution on coke particles and reduces coke yields. It also increases the yield of low viscosity, low molecular weight liquid at short vapor residence times. At long vapor phase residence times, however, vapors crack to gas, resulting in a concentration of higher viscosity, higher-molecular weight compounds in the liquid phase. The additional vapors that are produced in the bed thanks to enhanced mixing are more reactive and easily crack to gas at long vapor residence times. Realizing the full benefit of enhanced liquid distribution therefore requires minimization of the vapor residence time. [ABSTRACT FROM AUTHOR]

Controlled drop application is a promising technology for plant protection. It can be realized only with rotary atomizer. Rotary atomization has the advantage that by altering the rotational speed and/or the feed rate, one can produce a predictable drop size, with a comparatively narrow drop spectrum. In the ISSAPP “N. Pushkarov” a hydraulic rotary atomizer was developed and investigated in two ways of mounting the spraying body, down and up. Spray volume distribution pattern across of the boom is determined in the various regime of the operation of sprayer. Software for simulation the interaction of adjacent atomizers at a different distance between them has been developed. In accordance with European quality standards, the possible deviation of the sprays on the working width of the machine is determined. The benefits of a rotary atomizer with an upward spraying body have been proven. [ABSTRACT FROM AUTHOR]

Nonwoven coalescence filter media are often used in real-world applications to separate droplet aerosols from a gas stream. While mechanisms like droplet deposition, liquid transport and the evolution of the pressure drop are well understood, information on separated liquid structures formed during filtration is scarce. However, this information is important to understand the initial state of the coalescence filtration process, more specifically, the transition from individual deposited droplets to larger oil structures and subsequently the effect of these oil structures on the separation efficiency. In this work, deposited oil structures in the micrometer region of an oleophilic filter medium of different oil loading stages (saturations) are presented for the first time by utilizing micro–computed tomography (μ -CT) and several post-processing steps. The local (determined via μ -CT) and global (determined gravimetrically) porosities as well as local and global saturations are compared and evaluated. While local ( Φ l o c a l = 0. 9575) and global ( Φ g l o b a l = 0. 9588) porosities are in good accordance, significant deviations in the saturation are observed. The local saturation fluctuates significantly at the highest investigated oil loading stage. Especially at high global saturations, local areas are completely saturated with oil. Other areas are weakly saturated, which are particularly relevant for the gas flow to pass through the filter media. Furthermore, a novel routine to distinguish between different coalesced oil objects (e.g. oil droplets or oil sails) is developed and presented. It is shown, that the majority of the deposited oil (> 80%) is stored in oil sails between adjacent fibers. Oil droplets surrounding fibers are found to be growing in size with increasing oil loading time. In addition, the volume fraction of the deposited oil in the direction of filter thickness shows, that most of the oil is deposited on the upstream side at the first 80% of the filter. • μ -CT analysis of oil loaded oleophilic mist filters of different saturations. • A novel routine to identify different deposited oil structures in the micro scale. • Concentrations and distributions of deposited oil droplets on filter fibers. • Spatial oil distribution of different saturations in the direction of air flow. [ABSTRACT FROM AUTHOR]

Flash x-ray radiography is used to capture quantitative, two-dimensional line-of-sight averaged, single-shot liquid distribution measurements in impinging jet sprays. The accuracy of utilizing broadband x-ray radiation from compact flash tube sources is investigated for a range of conditions by comparing the data with radiographic high-speed measurements from a narrowband, high-intensity synchrotron x-ray facility at the Advanced Photon Source (APS) of Argonne National Laboratory. The path length of the liquid jets is varied to evaluate the effects of energy dependent x-ray attenuation, also known as spectral beam hardening. The spatial liquid distributions from flash x-ray and synchrotron-based radiography are compared, along with spectral characteristics using Taylor's hypothesis. The results indicate that quantitative, single-shot imaging of liquid distributions can be achieved using broadband x-ray sources with nanosecond temporal resolution. Practical considerations for optimizing the imaging system performance are discussed, including the coupled effects of x-ray bandwidth, contrast, sensitivity, spatial resolution, temporal resolution, and spectral beam hardening. [ABSTRACT FROM AUTHOR]

A method of using laser induced fluorescence(LIF)technique was applied to two-dimensional measurement of the liquid concentration distribution in the 250Y structured packing sheet. The experimental structured packing sheet was made of perspex so that the laser could pass through it. The visualization of the distribution of the liquid concentration in the structured packing sheet was realized. The calibration of the thickness and liquid concentration was carried out firstly and the regression formula I= kcd was acquired, in which concentration c and the liquid film thickness d were both considered. Then the liquid feed of uniform tracer(rhodamine)concentration entered the perspex structured packing from the top under different spraying densities. The corresponding thickness of liquid film on the packing was calculated. Finally, tracer(rhodamine)with a high concentration was injected only at one fixed point of the structured packing under different spraying densities of the liquid. With the known liquid film thickness, the concentration distribution of the tracer can be calculated inside the structured packing sheet. [ABSTRACT FROM AUTHOR]

Radial and axial liquid distribution was measured in a packed column of 500 mm length and 100 mm inner diameter under various gas- and liquid superficial velocities to achieve trickle flow regime. Liquid maldistribution was determined using a liquid collector at the outlet consisting of 21 collection zones of equal area. In this work, as packings inside the column, periodic open cellular structures (POCS) were manufactured and applied. Such POCS can be used as structured catalyst support and/or liquid distributor. The hydrodynamic behavior of packings with Kelvin cell, Diamond cell and a hybrid combination of both unit cells was studied to identify unit cells with high potential for achieving homogeneous liquid distribution over the entire reactor cross-section. The liquid superficial velocity had a strong influence on the liquid distribution, while an increasing gas flow rate did not change the flow patterns. Kelvin cell packings tend to distribute the liquid towards the center whereas Diamond cell packings predominantly spread the fluid towards the rim. As a consequence of these observations, in this work a novel POCS structure is proposed: The combination of Kelvin and Diamond unit cells, called hybrid DiaKel unit cell. With POCS consisting of this unit cell type, a significantly improved liquid distribution can be achieved. Thus, this structure features high potential as liquid distributor and/or catalyst support in gas-liquid reaction systems. [ABSTRACT FROM AUTHOR]

Falling-film evaporators are widely used for the concentration of liquid foods, especially milk prior to spray drying. Given that an evaporator is a heat exchanger, it is often incorrectly assumed that fouling is similar in heat exchangers and evaporators. This paper describes a number of features of falling-film evaporators that have been studied in recent years, and hence it seeks to show that attention to design detail should lead to lower rates of fouling. Typically fouling is due to poor liquid distribution to the tubes, which leads to drying of the milk films, or causes increases in viscosity to the point where flow stops. The minimum flow rates required to ensure wetting of tubes and flow into the tubes have been established but distributor holes must be correctly sized and drilled to give equal flow to all evaporator tubes. Blockage of distributor holes during operation can be avoided by installation of filters. Vapour flows from flashing or from unequal evaporation in the multiple passes of the same effect can interfere with the liquid flow from distributor plates but this can be overcome by the installation of vapour tubes in distributor plates. When correctly designed and fabricated, it is likely that falling film evaporators can operate in excess of 20 h without excessive fouling or bacterial growth. [ABSTRACT FROM AUTHOR]

Numerical simulations of the isothermal two-phase flow distribution in the packed bed of a reactor used for fuel hydrodesulfurization using the commercial software Fluent are reported. As a first step, the heat and mass transfer as well as the chemical reactions are not taken into account. The reactor considered has, above the bed, a distribution tray equipped with chimneys. A Eulerian three-phase model that considers the catalyst particles as a granular static phase was used following the Holub single-slit model for particle fluid interaction to compute the liquid-solid and gas-solid drag coefficients. Physical properties of the fluids are assumed to be constant. In the present study, the tendency of the liquid to move towards the wall of the reactor was studied in a bed 11 m in depth. The simulations predict that there is no suction effect on the flow caused by the wall. As the two-phase flow moves downward through the bed, a slow radial liquid spreading takes place. However, flow distribution is not completely uniform, at least at a distance of 11 m from the inlet. [ABSTRACT FROM AUTHOR]

In this paper, the numerical simulations have been carried out to evaluate the two-phase pressure drop and liquid distribution in screw channel. The numerical models are validated against the present experimental data with statistical accuracy. The effects of pitch circle diameter (PCD), inlet velocity and inlet sectional liquid holdup on the pressure drop and liquid distribution characteristics in the screw channel are illustrated. It is found that decreasing the PCD and increasing the inlet sectional liquid holdup can increase the liquid holdup on the outer side in screw channel. The PCD and the inlet sectional liquid holdup need to be considered in evaluating the two-phase frictional pressure drop per unit length in the screw channel. The PCD has an effect on the development of the average pressure in the various cross sections, and the inlet sectional liquid holdup has no visible impact on the changing process of the pressure drop in the screw channel. The correlation developed predicts the two-phase frictional pressure drop in the screw channel with great statistical accuracy. [ABSTRACT FROM AUTHOR]

The application of twin screw granulation in the pharmaceutical industry has generated increasing interest due to its suitability for continuous processing. However, an understanding of the impact of formulation properties such as hydrophobicity on intermediate and finished product quality has not yet been established. Hence, the current work investigated the granulation behaviour of three formulations containing increasing amounts of hydrophobic components using a Consigma™-1 twin screw granulator. Process conditions including powder feed rate, liquid to solid ratio, granulation liquid composition and screw configuration were also evaluated. The size of the wet granules was measured in order to enable exploration of granulation behaviour in isolation without confounding effects from downstream processes such as drying. The experimental observations indicated that the granulation process was not sensitive to the powder feed rate. The hydrophobicity led to heterogeneous liquid distribution and hence a relatively large proportion of un-wetted particles. Increasing numbers of kneading elements led to high shear and prolonged residence time, which acted to enhance the distribution of liquid and feeding materials. The bimodal size distributions considered to be characteristic of twin screw granulation were primarily ascribed to the breakage of relatively large granules by the kneading elements. [ABSTRACT FROM AUTHOR]

Disposable orbitally shaken bioreactors are a promising alternative to stirred or wave agitated systems for mammalian and plant cell cultivation, because they provide a homogeneous and well-defined liquid distribution together with a simple and cost-efficient design. Cultivation conditions in the surface-aerated bioreactors are mainly affected by the size of the volumetric oxygen transfer area (a) and the volumetric power input ( P∕VL) that both result from the liquid distribution during shaking. Since Computational Fluid Dynamics (CFD)-commonly applied to simulate the liquid distribution in such bioreactors-needs high computing power, this technique is poorly suited to investigate the influence of many different operating conditions in various scales. Thus, the aim of this paper is to introduce a new mathematical model for calculating the values of a and P∕VL for liquids with water-like viscosities. The model equations were derived from the balance of centrifugal and gravitational forces exerted during shaking. A good agreement was found among calculated values for a and P∕VL, CFD simulation values and empirical results. The newly proposed model enables a time efficient way to calculate the oxygen transfer areas and power input for various shaking frequencies, filling volumes and shaking and reactor diameters. All these parameters can be calculated fast and with little computing power. © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 30:1441-1456, 2014 [ABSTRACT FROM AUTHOR]

For upgrading the liquid distribution in a trickle-bed reactor, the distributor is always the primary consideration. The vapour-lift tube device, most widely used in industry, still has disadvantages like mal-distribution to overcome. Therefore in this paper, two major modifications, that is increasing of slot numbers and opening side pores, were proposed to improve its liquid distribution performance. Cold-flow model tests were carried out with liquid distribution, and pressure drop was measured by liquid collectors and Omega pressure sensor, respectively. The results showed that as compared with proto type, the modified liquid distributor has a better liquid distribution performance and a lower pressure drop. Liquid distribution increases with the increasing of gas/liquid velocity ratio ϵ only when it is <200. The pressure drop of new distributor increases with increasing of inner tube gas velocity and ϵ. Finally, correlations for liquid distribution and pressure drop of a new distributor were derived, showing rather good agreements with experimental results. [ABSTRACT FROM AUTHOR]

• DNS of droplets impinging, wetting, spreading and distribution on multiple particles. • Correlation of liquid partition coefficient with Weber number and solid volume fraction. • A sub-grid model for CFD simulation of liquid-injected fluidized beds. Liquid partition coefficient, defined as the proportion of the liquid volume covered on particle surface to that in bulk phase, is a key parameter in the simulation of liquid-injected fluidized beds. To develop the sub-grid model for liquid partition coefficient as a function of local hydrodynamics, a two-dimensional Volume-of-Fluid (VOF) simulation was conducted to directly resolve droplets impinging, wetting and spreading on particles in a box. The model was first validated by the experiments in literature on the spreading diameter of a droplet impinging on a single particle. Then for a system of multiple droplets-particles impinging, we investigated the effects of Weber number, droplet-to-particle (DTP) ratio and particle volume fraction on several characteristic parameters, e.g., ratio of liquid area adhered to particles to the total liquid area, liquid film thickness, the percentage of wetted particle surface area and liquid holdup. All these parameters decrease with increasing Weber number when We = 10 ∼ 370, and then gradually stabilize. Higher particle volume fraction increases the collisional frequency of droplets and particles, and therefore the ratio of liquid area adhered to particles to the total liquid area. By contrast, DTP is not the dominant factor in liquid partition. Finally a correlation for liquid partition coefficient is proposed as a function of droplet Weber number and particle volume fraction. It may serve as a sub-grid model for CFD-DEM or multifluid models in simulation of large-scale liquid-injected fluidized beds. [ABSTRACT FROM AUTHOR]

To characterize the granulation rate processes in the kneading section of the twin screw granulator, separate experiments were conducted using exclusively conveying elements as the baseline in addition to different configurations of kneading elements. The configuration parameters examined were the length of the kneading section, the advance angle, and the angle direction. Granule size, shape and liquid distribution were measured. Two main rate processes were observed (1) breakage and layering, and (2) Shear elongation and layering. Breakage was dominant in the 90° configuration while shear elongation dominated in the 30° reverse configurations, with other configurations giving some combination of the two rate processes. The distinct three-dimensional (3-D) shape characteristics of granules obtained from each configuration were crucial in elucidating the dominant granulation rate process in each case. The proposed granulation mechanisms explain the events leading to particular granule attributes, but more importantly provide insight into future optimization of twin screw granulation process. © 2013 American Institute of Chemical Engineers AIChE J, 59: 4100-4115, 2013 [ABSTRACT FROM AUTHOR]

Abstract: In the recent few years, continuous processing has been considered as a promising process alternative to batch processing in pharmaceutical manufacturing. Via a novel population balance model framework, a multi-dimensional multi-component model for a continuous granulation process was developed, describing time evolutions of distributions with respect to granule size, liquid distribution and granule composition. A parametric study was performed to analyze the effects of various process and design parameters, including granulator size and configuration, liquid spray rate and particle velocity, on evolutions and distributions of key granule properties. Simulation results capture experimentally observed sensitivities and trends thus demonstrating the use of a model-based framework for granulation process design, control and optimization to enable QbD in drug product development. [Copyright &y& Elsevier]

Abstract: Injection of liquid into fluidized beds is widely applied in the petrochemical, chemical, food and pharmaceutical industries. The local bed hydrodynamics have a strong impact on the contact between the injected liquid and the bed solids. By adjusting the local bed hydrodynamics or locating the injection nozzle in the appropriate region of the bed, the contact between the injected liquid and the bed solids may be optimized to minimize agglomerate formation, which is detrimental to many industrial operations such as Fluid Coking. The effect of bed hydrodynamics on liquid distribution was investigated with a new, reliable and sensitive capacitance method. Results show that the fluidized bed hydrodynamics have a considerable impact on the contact efficiency between injected liquid and fluidized solids. [Copyright &y& Elsevier]

Convective drying of disordered glass bead packings has been investigated both experimentally and numerically. X-ray microtomography (XMT) and image analysis techniques have been used to determine the three-dimensional spatial distribution of the liquid and solid phases at the pore scale within the wet particle aggregates. The evolution of the liquid distribution in the aggregate has been tracked during the drying process. Particle center coordinates and radii have been extracted from the X-ray images using binarization and segmentation techniques. Based on this geometric data for a real aggregate, a pore network approximation of the pore space has been generated from a Voronoi tessellation about particle centers by designating Voronoi edges as interconnected cylindrical pores with radii computed from the distance between neighboring particles. This three-dimensional irregular pore network takes into account both the geometrical and topological characteristics (pore size distribution and connectivity) of the actual pore space. Drying simulations have been carried out for the pore networks obtained from the XMT and results are presented as phase distributions and moisture profiles. The simulated liquid phase distributions are in qualitative agreement with the experimental result, which indicates that pore network models are suited to describe the drying of dense particle aggregates at the pore scale. [ABSTRACT FROM PUBLISHER]

Abstract: Numerical simulations of the two-phase flow distribution in a trickle-bed reactor used for fuel hydrodesulfurization are reported. As a first step, the heat and mass transfer, as well as the chemical reactions, are not considered. The reactor has four packed-beds and a distribution tray above the catalytic beds equipped with cylindrical chimneys. The flow distribution at the outlet of the circular chimney predicted by the simulations is not axisymmetric because of the spatial distributions of the liquid and gas inlets in the chimney. This causes that the liquid entering the packed beds is distributed in three main streams. For the simulation of the two-phase flow in the packed beds, an Eulerian three-phase model that considers the particles of catalyst as a granular static phase has been used following the Holub single slit model for particle–fluid interaction to compute the liquid–solid and gas–solid drag coefficients. Numerical simulations of the dispersion of water–air flow in a column of glass beads using this model were initially carried out and results were found to be in reasonable agreement with numerical and experimental data available in the literature. The simulations consider the flow dispersion in the central region of the reactor bed as well as in the region close to the cylindrical lateral wall of the reactor. In both cases most of the liquid spreading takes place in the top part of the bed. The distributions of the liquid volume fraction do not change significatively as the depth of the bed is increased except in the third bed and at the interface of two beds with different porosity. [Copyright &y& Elsevier]

Abstract: The three-dimensional structure of a fibrous filter determines its behaviour during filtration, such as the obtained pressure drop, the fractional efficiency and the filter lifetime. Therefore, suitable parameters describing the inner structure (the local packing density) are key inputs for modelling filter performance accurately. The synchrotron X-ray holotomography, carried out at the European Synchrotron Radiation Facility, was performed in this study to provide information on the three-dimensional structure of a fibrous filter. Moreover, this non-invasive technique was used to determine the liquid distribution in a filter clogged with a liquid aerosol of di-ethyl-hexyl-sebacate. These samples were imaged at a voxel size of 0.7μm, which allows the quantification of the different phases within the filter (liquid, fibres and void space). The results complete the two-dimensional studies obtained by scanning electron microscopic and highlight the formation of liquid menisci not only on the filter surface but also in the filter depth. Image analyses of synchrotron X-ray holotomography radiographs also highlight a heterogeneous liquid distribution along the thickness of the clogged filter. [ABSTRACT FROM AUTHOR]

Abstract: The mixing of a wetted insoluble granular medium was experimentally investigated focusing on the variation of the specific intensity consumption of mixing with addition of liquid in the granular bulk. Preliminary results showed the influence of the particle average diameter of glass beads and calcites (CaCO3), on the intensity consumption which decreased with the increase of the particles size (for the capillary and funicular states). However, an exception was observed at the level of the funicular state of the calcite, for which there was no particle size influence on the intensity consumption (for particles sizes inferior to 150μm). The effect of an inhomogeneous liquid distribution was not clearly demonstrated. However, the funicular intensity consumption was linked with the compacity of the medium. By stopping the liquid flow at the end of the funicular state, and by continuing the mixing of a calcite, the funicular state intensity consumption and the measured granular compacities were increased. Moreover, this compacity measured during the funicular state, decreased with the particle size. [ABSTRACT FROM AUTHOR]

Abstract: The division of labor between the different worker castes of leaf-cutting ants may reflect in their capacity to exchange liquids by trophallaxis. The crop capacity of and trophallactic exchanges between different size classes of worker leaf-cutting ants of the sub-species Acromyrmex subterraneus subterraneus were investigated. Size classes were defined from head capsule widths and crop capacity of each class was determined following ad libitum feeding on dye solution. Experiments were carried out to investigate trophallactic exchanges between donor ants and recipient ants of each class size combination on a one to one basis. An experiment was also performed to investigate dye distribution within mini-colonies following introduction of three classes of donor ants. Worker ants were categorized into four size classes from their head capsule widths (C1=0.8–1.0mm; C2=1.2–1.5mm; C3=1.6–2.0mm; C4=2.1–2.4mm). C1 ants crop capacity was 0.13μL; C2: 0.21μL; C3: 0.52μL; C4: 1.03μL. Ants of each class previously fed on the dye solution (donors) were placed individually with an unfed ant of each class (recipients) and the presence of dye solution, passed from the donor to the recipient by oral trophallaxis was observed after 1h. Results showed that all classes of donor ants performed trophallactic exchanges with all recipient classes. However, statistically fewer exchanges were seen for C2 donor ants when placed with C3 recipient ants. Ten donor ants of each of three classes (C2, C3 and C4) were introduced into mini-colonies without queen ants. It was observed that C1 and C2 ants were poor recipients, whilst C3 and C4 received the highest percentages of dye. Within 10h of introducing the donor ants, 14 to 20% of their nest-mates had received dye solution, with 58 to 77% of dye passed to recipients. These studies show the altruistic nature of “food-laden” leaf-cutters and indicate that ants involved in garden maintenance activity are less likely to receive liquids from foraging workers. [Copyright &y& Elsevier]