Liquid Loading Research Articles

On Liquid Flow Maldistribution through Investigation of Random Open-Structure Packings

The optimal design of packed columns for separation processes is strongly dependent on an accurate prediction of the fluid flows in the packing. Insufficient knowledge about the complex factors and mechanisms governing hydrodynamic effects is compensated for by empirical information. The present study fills the gap in experimental data about the liquid phase distribution in plastic Raschig Super-Ring (RSRP) packing and plastic Ralu–Flow (RF) packing. These belong to the family of widely used random packings with an open lattice structure characterized by high mass transfer efficiency and a low pressure drop. The study was performed using the liquid collection method with a device with concentric annular collection sections at the packing outlet. Large-scale liquid maldistribution in the central and peripheral zones of the packed bed were evaluated in comparison data on competing random and structured packings. The effects of the packing size and the liquid load on the radial distribution of the superficial liquid velocity, wall flow formation and the maldistribution factor were investigated and analyzed. The results contribute to deepening the knowledge about the phenomenon of large-scale liquid flow maldistribution in packed columns, as well as to design enhancement.

MMC-LES of spray combustion: Analysis of mixing timescales and flame structure

Large-eddy simulations (LES) of turbulent, pilot-stabilised, dilute acetone spray flames are performed using the sparse-Lagrangian multiple mapping conditioning approach (MMC-LES). The primary objective of this work is to assess the adaptability of the recently proposed dynamically evaluated molecular mixing timescale model for MMC-LES (Sharma et al., 2022, A fully dynamic mixing timescale model for the sparse Lagrangian multiple mapping conditioning approach, Combustion and Flame, 238, 111872), referred to as the dyn-aISO model, to the non-reacting and reacting two-phase flows. This work is the first application to perform a dynamic evaluation of the mixing timescale for turbulent spray combustion using the transported filtered density function (FDF) approach. A non-reacting case and four reacting flames with varying fuel mass loading are investigated, where the flame transitions from a diffusion flame to a premixed flame structure with a decrease in fuel loading. As is conventional for MMC-LES, a sparse resolution of one stochastic particle per six Eulerian finite-volume cells is used in this study, offering a much cheaper computing expense than the conventional transported FDF approach. The liquid evaporation is represented based on a non-equilibrium model at the droplet surface. The reaction chemistry is based on an augmented GRI 3.0 mechanism containing 39 species and 226 reactions to represent the oxidation of acetone. Predictions with the dyn-aISO model are compared with the constant coefficient anisotropic mixing time scale model and the isotropic C-K model. Thorough validation of liquid-phase statistics and gas-phase temperature is performed with available experimental data and popular studies from the literature. Analysis of the flame structure, with different timescale models, for both non-premixed and premixed type flames is also carried out. Quantification of the parameters affecting the timescale, such as model constants of the sub-Lagrangian-grid scale (slgs) mixture fraction variance (Cf) and its scalar dissipation rate (Scsgs−1Cν) is provided in comparison to their conventionally chosen static coefficient values. Predictions with the dyn-aISO model are quite good for the diffusion-type flames, while some discrepancies are noticed while predicting a premixed flame structure for lower liquid loading case having near stoichiometric jet-exit mixture composition.

Self-doped TiO2 nanotubes with surface modification by ionic liquids for enhanced photoreduction of CO2 to acetic acid

The photocatalytic reduction of CO2 to high-value hydrocarbons can both solve environmental problems and alleviate the energy crisis. As a room-temperature molten salt with designable anions and cations, ionic liquids are very popular in the field of CO2 capture. If combining ionic liquids with photocatalysts, simultaneous capture and conversion of CO2 are expected to be achieved. In this study, a [bmim][Tf2N] loaded self-doped TiO2 nanotubes (ILs-RTNTs) composite photocatalyst was developed for the photoreduction of CO2 to acetic acid. The acetic acid yield of ILs-RTNTs reached as high as 88.1 μmol gcat−1h−1, and there was no decrease after six cycles. Both the defects constructed by self-doping and the surface modification by ionic liquids strengthened the light utilization ability of the photocatalyst and enhanced the separation of photoinduced electron-hole pairs. Density-functional theory (DFT) calculations further revealed that the surface loading of ionic liquids introduced more active sites, strengthened the adsorption of CO2, changed the electronic structure, and lowered the energy barrier for electron transfer of the photocatalyst. This study will promote the versatile application of ionic liquids in the field of simultaneous capture and photoreduction of CO2.

Study on Optimization of Chilldown Process for A New Generation Launch Vehicle

Focused on chilldown procedure of liquid oxygen filling for second stage of a new generation launch vehicle, the method of chilldown through liquid oxygen pump has been put forward and compared with traditional method that of gas pressurization. The results showed that it could reduce total time, lower system state changes, and improve efficiency and reliability of liquid oxygen loading operations. Aimed at liquid oxygen flow of chilldown through the pump, the model of liquid oxygen pump operating has been established by considering variable frequency, regulating valve opening and liquid level of vehicle tank. It can provide scientific guidance and basis for flow control of chilldown through the pump and liquid oxygen tests.

Horizontal Stratified Air–Foam–Water Flows: Preliminary Modelling Attempts with OLGA

Water accumulation is a major problem in the flow assurance of gas pipelines. To limit liquid loading issues, deliquification by means of surfactant injection is a promising alternative to the consolidated mechanical methods. However, the macroscopic behavior of foam pipe flow in the presence of other phases has barely been explored. The goal of this work was to propose an approach to simulate air–water–foam flows in horizontal pipes using OLGA by Schlumberger, an industry standard tool for the transient simulation of multiphase flow. The simulation results were compared with experimental data for 60 mm and 30 mm ID (Inner Diameter) horizontal pipelines. Preliminary validation for two-phase air–water flow was carried out, which showed that correct flow pattern recognition is essential to accurately reproduce the experimental data. Then, stratified air–foam–water flows were investigated, assuming different models for the foam local velocity distribution. Foam rheology was considered through the Herschel–Bulkley model with the yield stress varying in time due to foam decay. The results showed good agreement for a uniform velocity profile and fresh foam properties in the case of the 60 mm ID pipeline, whereas for the 30 mm ID, which was characterized by significantly higher velocities, a linear velocity profile and 2000 s foam aging provided the best agreement. In both cases, the pressure gradient was overestimated, and the mean absolute prediction error ranged from about 5% to 30%.

Drainage Research of Different Tubing Depth in the Horizontal Gas Well Based on Laboratory Experimental Investigation and a New Liquid-Carrying Model

Since the structure of horizontal gas wells is more intricate than that of vertical wells, there is a lack of consistency in the form of liquid-carrying in different portions. Applying the commonly utilized liquid-carrying hypothesis of vertical gas wells into horizontal gas wells is therefore challenging. The maximum liquid volume that the gas flow could raise, the gas flow rate, and the maximum amount of energy that could be produced from a specific amount of gas flow should all be considered when determining the liquid volume that the gas flow could lift. This study is the first to integrate theoretical analysis with laboratory testing to analyze the gas–liquid flow law of drainage stability at varied tubing depths. The impact of gas drainage stability is then verified through the laboratory experiments. The novel model of various tubing depths, which is based on the energy of inflow and outflow from the horizontal well, is cleverly built. According to the study, the fluctuation is typically less when the tubing reaches the heel of the horizontal section than it is in the other sections, and the relative error of the new model, which is validated using laboratory tests, is typically less than 10%. The research showed that for horizontal gas wells with a normal structure, the gas flow and liquid discharge are most stable when the tubing reaches the heel of the horizontal section. Instead of depending exclusively on crucial liquid-carrying gas flow rates, the new model uses the combination of gas and liquid flow rates to make decisions concerning liquid loading and to quantify the liquid removal in real time, which is more realistic. The research illustrates how the study could provide a factual basis for assessing the capacity of horizontal gas wells to raise the liquid.

Application of Machine-Learning Algorithms for Better Understanding the Properties of Liquisolid Systems Prepared with Three Mesoporous Silica Based Carriers.

The processing of liquisolid systems (LSS), which are considered a promising approach to improving the oral bioavailability of poorly soluble drugs, has proven challenging due to the relatively high amount of liquid phase incorporated within them. The objective of this study was to apply machine-learning tools to better understand the effects of formulation factors and/or tableting process parameters on the flowability and compaction properties of LSS with silica-based mesoporous excipients as carriers. In addition, the results of the flowability testing and dynamic compaction analysis of liquisolid admixtures were used to build data sets and develop predictive multivariate models. In the regression analysis, six different algorithms were used to model the relationship between tensile strength (TS), the target variable, and eight other input variables. The AdaBoost algorithm provided the best-fit model for predicting TS (coefficient of determination = 0.94), with ejection stress (ES), compaction pressure, and carrier type being the parameters that influenced its performance the most. The same algorithm was best for classification (precision = 0.90), depending on the type of carrier used, with detachment stress, ES, and TS as variables affecting the performance of the model. Furthermore, the formulations with Neusilin® US2 were able to maintain good flowability and satisfactory values of TS despite having a higher liquid load compared to the other two carriers.

Study on Screening and Evaluation of Foam Drainage Agents for Gas Wells with High Temperature and High Pressure.

Foam drainage gas recovery technology is a chemical method to solve the serious bottom-hole liquid loading in the middle and late stages of gas well production, and the optimization of foam drainage agents (referred to as FDAs) is the key to the technology. According to the actual reservoir conditions, a high-temperature and high-pressure (HTHP) evaluation device for FDAs was set up in this study. The six key properties of FDAs, such as HTHP resistance, dynamic liquid carrying capacity, oil resistance, and salinity resistance, were evaluated systematically. Taking initial foaming volume, half-life, comprehensive index, and liquid carrying rate as evaluation indexes, the FDA with the best performance was selected and the concentration was optimized. In addition, the experimental results were verified by surface tension measurement and electron microscopy observation. The results showed that the sulfonate compound surfactant (UT-6) had good foamability, excellent foam stability, and better oil resistance at high temperature and high pressure. In addition, UT-6 had stronger liquid carrying capacity at a lower concentration, which could meet the production requirement when the salinity was 80 000 mg/L. Therefore, compared with the other five FDAs, UT-6 was more suitable for HTHP gas wells in block X of the Bohai Bay Basin, whose optimal concentration was 0.25 wt %. Interestingly, the UT-6 solution had the lowest surface tension at the same concentration, with the generated bubbles being closely arranged and uniform in size. Moreover, in the UT-6 foam system, the drainage speed at the plateau boundary was relatively slower with the smallest bubble. It is expected that UT-6 will become a promising candidate for foam drainage gas recovery technology in HTHP gas wells.

Spatially Resolved Tomographic Assessment of Axial Mixing in Structured and Random Packings

AbstractThe liquid axial dispersion inside modern structured packings (Sulzer Mellapak™ 500.Y, Raschig Super‐Pak 350Y) and one random packing of the 4th generation (Raschig Super‐Ring 0.3) was measured by means of computed tomography. As the gas velocity is known to have little effect on the liquid axial dispersion at low hydraulic load, all experiments were conducted without countercurrent gas flow at liquid loads of B = 10, 15, and 20 m3m−2h−1 in a column with an inner diameter of 100 mm. Injection of the X‐ray‐active tracer potassium iodide allows the identification of active and passive liquid accumulations inside the structured packing. Good agreement was found between the active liquid holdup from tomographic images and the total holdup calculated from the mean residence time for the structured packings.

Carbon materials derived from cyano-based IL@ZIF-8 composites for CO2 sorption separation systems

The sorption capacity and selectivity of pre- and post-carbonized cyano-based metal-organic framework (MOF) composite materials (cyano-based IL@ZIF-8) were investigated for the first time. The influence of the ionic liquid (IL) loading and number of cyano groups in the IL anion on a materials gas sorption separation performance was studied. Sorption-desorption equilibrium isotherms of CO2, CH4, and N2 were measured at 303 K in the ZIF-8, cyano-based IL@ZIF-8 composites and their derived carbon materials. The IL loading did not significantly affect the gas uptake of the carbon materials, while for the composites its main contribution was on the increase of the selectivity. The number of cyano groups in the anion played a key role in the sorption capacity and selectivity performance as it directly affects the N content and textural properties. The carbon material obtained from ZIF-8 (C_ZIF-8) precursor showed the best sorption capacity for all gases, just being surpassed by the C_15%[C6MIM][B(CN)4]@ZIF-8 carbon up to 1 bar. In terms of selectivity performance, carbons based on [C6MIM][B(CN)4]@ZIF-8 composites revealed to be equally or more selective than C_ZIF-8, increasing up to 65% between 0 and 1 bar depending on the mixture. The composites produced and their respective carbons demonstrated a promising application as sorbents for post-combustion CO2 separation systems.

Semianalytical Model for Monitoring Fracture Liquid-Loading in Vertical Fractured Gas Wells

Summary Liquid loading seriously affects gas wells production and even causes gas wells abandonment. Many researchers still focus on correcting a critical liquid-loading flow rate to alleviate these problems. However, they still cannot reasonably be explained. Gas flow rate is higher than the critical liquid-loading flow rate, but liquid loading can still occur. Therefore, until an accurate critical fluid-loading flow rate is discovered, we should monitor the fluid-loading phenomenon to prevent it from affecting production gas wells’ performance. In this work, a fracture liquid-loading monitoring (FLLM) model is proposed and solved for the timely monitoring of fracture liquid-loading (FLL) positions and volume. The Newman product and Green function methods are used to develop and solve the FLLM model. The fracture is discretized into 2nxnz grids to describe an FLL volume and position. The numerical simulation method is used to verify the accuracy of the FLLM model. As a result, four innovative flow regimes, including fracture cavity liquid-loading flow, fracture root liquid-loading flow, transitional flow considering fracture cavity liquid-loading flow, and transitional flow considering fracture root liquid-loading flow, are identified on the pressure response curves. The pressure response of the same gas well at different times is well matched by the model in this paper, and the obtained parameters are more reasonable. The FLLM model can correct for magnified permeability, shortened half-length, and magnified wellbore storage coefficient. In conclusion, the FLLM model is established to monitor FLL, and alert engineers to remove liquid loading on time to prevent water from suddenly rushing into a wellbore and causing gas wells abandonment.

Cooling tower performance and the ambiguity of the L/G ratio scheme in optimization: A single cell control volume approach

Present optimization schemes and innovative operation strategies of the cooling tower often encounter unexpected results, which may derail the effort for better efficiency. In some instances, the practice may even cause energy and water wastage. In this study, the single-cell approach is performed numerically, translating the full cooling tower fill into the smallest fundamental state of control volume to investigate the performance ambiguity attributed to the L/G ratio scheme. Two types of surface are proposed to investigate the surface effect. The actual fluid rate inside the fill varies by 20–50% between the two fill surfaces, which is relatively higher on the multi-faceted single cell. The Merkel number is integrated into the analysis by examining the liquid-gas interface for heat transfer assessment. The lower fluid rate on the circular single cell generates a higher Merkel number than the multi-faceted single cell. Even though the 32% increase in Merkel number is achieved under various liquid loads on the multi-faceted single cell, approximately half of the operating liquid load leads to decreasing Merkel number. Meanwhile, the reaction axis is introduced to characterize the surface fill under the effect of the liquid load. It is symmetrical on the circular single cell, indicating a positive linear effect to increasing liquid load. On the contrary, the reaction axis is asymmetrical on the multi-faceted single cell suggesting a negative linear effect which also leads to excess unproductive fluid rate.

Valorization of Hemp-Based Packaging Waste with One-Pot Ionic Liquid Technology.

The range of applications for industrial hemp has consistently increased in various sectors over the years. For example, hemp hurd can be used as a resource to produce biodegradable packaging materials when incorporated into a fungal mycelium composite, a process that has been commercialized. Although these packaging materials can be composted after usage, they may present an opportunity for valorization in a biorefinery setting. Here, we demonstrate the potential of using this type of discarded packaging composite as a feedstock for biofuel production. A one-pot ionic liquid-based biomass deconstruction and conversion process was implemented, and the results from the packaging material were compared with those obtained from untreated hemp hurd. At a 120 °C reaction temperature, 7.5% ionic liquid loading, and 2 h reaction time, the packaging materials showed a higher lignocellulosic sugar yield and sugar concentrations than hemp hurd. Hydrolysates prepared from packaging materials also promoted production of higher titers (1400 mg/L) of the jet-fuel precursor bisabolene when used to cultivate an engineered strain of the yeast Rhodosporidium toruloides. Box-Behnken experiments revealed that pretreatment parameters affected the hemp hurd and packaging materials differently, evidencing different degrees of recalcitrance. This study demonstrated that a hemp hurd-based packaging material can be valorized a second time once it reaches the end of its primary use by supplying it as a feedstock to produce biofuels.

Numerical Investigation of the Particle Dynamics in a Rotorgranulator Depending on the Properties of the Coating Liquid.

In the pharmaceutical industry, the coating of particles is a widely used technique to obtain desired surface modifications of the final product, e.g., controlled release of the active agents. The production of round, coated particles is particularly important, which is why fluidized bed rotor granulators (FBRG) are often used for this process. In this work, Computational Fluid Dynamics (CFD) coupled with the Discrete Element Method (DEM) is used to investigate the wet particle dynamics, depending on the properties of the coating liquid in a FBRG. The DEM contact model was extended by liquid bridge model to account for capillary and viscous forces during wet contact of particles. The influence of the relative contact velocity on the maximum length of the liquid bridge is also considered in the model. Five different cases were compared, in which the particles were initially wetted, and the liquid loading as well as the surface tension and viscosity of the liquid were changed. The results show that increasing viscosity leads to a denser particle bed and a significant decrease in particle rotational velocities and particle motion in the poloidal plane of the FBRG. Reducing the liquid loading and surface tension results in increased particle movement.

Deformation characteristics and inertial effect of complex aluminum alloy sheet part under impact hydroforming: experiments and numerical analysis

Impact hydroforming (IHF), as a novel sheet metal forming technology with the advantages of high strain rate forming and flexible liquid loading, is highly suitable for efficiently manufacturing aluminum complex-shaped sheet parts. In this paper, deformation characteristics of complex sheet parts under IHF are systematically investigated. The mechanical properties of 2024 aluminum alloy under a wide range of strain rates (10−3 s−1–3.3×103 s−1) were studied. It indicated that the elongation of 2024 aluminum alloy was improved by 116.01% under strain rates of 3.306 × 103 s−1, referring to 10−3 s−1. Further, a complex-shaped part with symmetrical and asymmetrical structures was selected. The deformation characteristics of sheet and role of inertial effect under IHF were investigated with well-developed solid–liquid coupling finite element (SLC-FE) model with high accuracy. Differentiating deformation tendency is found for symmetrical structure with notably prior deformation at central zone, showing a “bulging” profile at initial forming stage. Whereas, synchronous deformation is presented for asymmetrical structure with a “flat” profile. Additionally, distinctive inertial effect was observed at different positions change for both symmetrical and asymmetrical structures, in which lower values were resulted at their central regions. Meanwhile, the inertial effect evolved with the impacting speed. Specially, larger difference of inertial effect was observed with increasing impacting speed.

Cryopreservable Through-Hole Arrays for the High-Throughput Three-Dimensional Smartphone-Based Cell Colorimetric Assay.

In vitro assays are an important platform for cancer research as they allow high-throughput experimentation that is not possible using in vivo animals. Although various in vitro assays are developed to study cell viability or migration, many of these assays are often limited to two dimensions, involving complex procedures or relying specialized equipment, etc. Here, we designed a simple colorimetric assay that accommodates automatic liquid samples loading, high-throughput generation of chemical concentration gradient, three-dimensional (3D) cell culture establishment, and smartphone-based colorimetric readouts. This assay is based on through-hole arrays in the poly(methyl methacrylate) (PMMA) layers. Liquid samples can be automatically loaded into through-hole arrays in PMMA layers by capillary force. Different drug concentrations can be generated by aligning and stacking to mix the contents of the corresponding through-holes with different volumes. 3D culture of cancer cells can be established by the rapid absorption of cell suspensions into the macroporous gels. After exposing the 3D cultured cells to different drug concentrations, the number of viable cells and migrated cells was reflected by the color change of Alamar blue, which enable on-site readout by a smartphone. This assay can study cell viability as well as cell migration, the two main characteristics of cancer cells, using one device. Interestingly, HeLa cells remained with high viability after cryopreservation at -80 °C, which allows for storage and distribution using dry ice. The simple protocol, along with the cryopreservability at -80 °C facilitates its ease of use to study cell viability together with cell migration in common laboratories or clinical settings.

Evaluation of Liquid Loading in Gas Wells Using Machine Learning

The inevitable result that gas wells witness during their life production is the liquid loading problem. The liquids that come with gas block the production tubing if the gas velocity supplied by the reservoir pressure is not enough to carry them to surface. Researchers used different theories to solve the problem naming, droplet fallback theory, liquid film reversal theory, characteristic velocity, transient simulations, and others. While there is no definitive answer on what theory is the most valid or the one that performs the best in all cases. This paper comes to involve a different approach, a combination between physics-based modeling and statistical analysis of what is known as Machine Learning (ML). The authors used a refined ML algorithm named XGBoost (extreme gradient boosting) to develop a novel full procedure on how to diagnose the well with liquid loading issues and predict the critical gas velocity at which it starts to load if not loaded already. The novel procedure includes a combination of a classification problem where a well will be evaluated based on some completion and fluid properties (diameter, liquid density, gas density, liquid viscosity, gas viscosity, angle of inclination from horizontal (alpha), superficial liquid velocity, and the interfacial tension) as a “Liquid Loaded” or “Unloaded”. The second practice is to determine the critical gas velocity, and this is done by a regression method using the same inputs. Since the procedure is a data-driven approach, a considerable amount of data (247 well and lab measurements) collected from literatures has been used. Convenient ML technics have been applied from dividing the data to scaling, modeling and assessment. The results showed that a wellconstructed XGBoost model with an optimized hyperparameters is efficient in diagnosing the wells with the correct status and in predicting the onset of liquid loading by estimating the critical gas velocity. The assessment of the model was done relatively to existing correlations in literature. In the classification problem, the model showed a better performance with an F-1 score of 0.947 (correctly classified 46 cases from 50 used for testing). In contrast, the next best model was the one by Barnea with an F-1 score of 0.81 (correctly classified 37 from 50 cases). In the regression problem, the model showed an R2 of 0.959. In contrast, the second best model was the one by Shekhar with an R2 of 0.84. The results shown here prove that the model and the procedure developed give better results in diagnosing the well correctly if properly used by engineers.

Liquid Loading of Horizontal Gas Wells in Changbei Gas Field

The Changbei gas field, which initially exhibited high gas-production performance, is dominated by large-displacement horizontal wells. With the decrease in reservoir pressure, the liquid loading in the gas well is currently severe, and production has been rapidly decreasing. Thus, recognizing the gas-well liquid loading to maintain stable gas-well production is necessary. A method was established to identify the water source of the liquid loading in the Changbei gas field. First, formation water and condensate water were identified based on the mineralization of the recovered water and the mass concentration of Cl− and K+ + Na+, and then the condensate content of the water produced in the gas well was qualitatively evaluated. The water–gas ratio curve for the gas well was plotted to determine whether the produced water was edge-bottom water, pore water, or condensate. Then a method was established to distinguish the start time of liquid loading in the gas well using a curve depicting a decrease in production; the method was also used to estimate the depth of the gas well where liquid loading occurs, according to the bottomhole pressure. First, based on the available production data, the Arps decline model was applied to fit the production curve for the entire production phase; the resulting curve was compared with the actual production curve of the gas well, and the two curves diverged when fluid accumulation began in the gas well. Finally, the liquid-loading depth of the gas well was estimated based on the bottomhole pressure. This method can be used to determine the fluid accumulation and calculate the liquid-loading depth of gas wells with unconnected oil jackets. The analysis revealed that in the Changbei gas field, condensate was the type of water primarily produced in 35 gas wells, accounting for 62.5% of the total number of gas wells. Edge-bottom water was the type of water primarily produced in 16 gas wells, accounting for 28.6% of the total number of gas wells. In the remainder of the gas wells, pore water was the water primarily produced; the calculations of accumulation time and accumulation volume of typical gas wells in the block revealed that some gas wells started to accumulate liquid after 45–50 months, and the amount of accumulation could reach several tens of meters, while others were in good production condition. The method established in this paper could enhance our understanding of liquid loading in gas wells in the Changbei gas field and lay a foundation for the development of gas-well deliquification techniques.

Experimental investigation of film reversal evolution characteristics in gas–liquid annular flow

In natural gas wells, liquid loading is a severe problem threatening production safety. Published studies have verified that liquid loading is closely related to film reversal in gas–liquid annular flow, but the evolution of the film reversal is still unclear. This article reports on experiments conducted to reveal the film reversal evolution characteristics. Experiments were conducted in a 50-mm-diameter vertical pipe with superficial gas velocities ranging from 5.66 to 22.64 m/s and superficial liquid velocities ranging from 0.014 to 0.170 m/s. A camera and electrical resistance tomography were used to obtain qualitative and quantitative results, and an error analysis verified the experiments’ repeatability and reliability. The evolution process is divided objectively into three stages to clarify the film reversal: no film reversal (No-FR), the onset of film reversal (Onset-FR), and complete film reversal (Complete-FR). The three stages occur successively with decreasing gas velocity. The characteristics of the individual stages are elaborated, including the interfacial structures, morphological features, and motion trajectories. The void fractions are analyzed in both the time and frequency domains, where the statistical parameters of the probability density function, average value, and standard deviation are presented. The results show that the Onset-FR stage exhibits characteristics similar to both the No-FR and Complete-FR stages, indicating that it plays an intermediate role in the gradual evolutionary process. The current experimental results also achieve excellent agreement with published datasets and correlations.

Study of the Hydrodynamic Performance of a Compact and Intensified G/L Contactor: The RPB

Modern process equipment needed for safe and economically viable chemical and biological processes requires flexibility, compactness, and a great potential for enhancing mass transfer. Centrifugal process intensification equipment such as the rotating packed bed (RPB) satisfies the above mentioned requirements in addition to zero sensitivity to changes caused by gravity. The fundamental principles of RPBs are yet to be fully established due to difficulty in predicting their behavior which has necessitated the need for treating their design, modeling, and optimization on a case-to-case basis. This study focused on the hydrodynamics (pressure drops) of a pilot-scale RPB equipped with a stainless steel wire mesh packing. The effects of three operational parameters: average high gravity factor, integrated gas capacity factor, and liquid load, as well as a design parameter, the fluid distributor type were investigated. The maximum value of the average gravity factor used was 452. Also, a combined gas capacity factor of 2.6Pa0.5, and a liquid load of up to 20m3m-2h-1 were explored. Additionally, the influence of liquid distributor type on the pressure drop of RPBs was investigated.