Mesh Packing Research Articles

Dispersion Behavior of a Droplet Impacting a Single Fiber.

The high-gravity reactor, known for its excellent mass transfer capability, plays a crucial role in the carbon capture process. The wire mesh packing serves as the core structure for enhancing mass transfer performance. Understanding the underlying dispersion mechanism requires a thorough exploration of the dynamics of droplet impact on a single fiber. This work aimed to numerically study the process of a droplet impacting a single fiber by applying the volume of fluid method. The effects of initial velocity (u0), initial diameter (D0), impact eccentric distance (e), and impact angle (θ) on the deformation evolution and dispersion characteristics of a droplet impacting a single fiber were systematically studied. Central or vertical impacts can be categorized into four main stages: splitting, merging, stretching, and breaking. Meanwhile, asynchronous breaking, sliding splitting, and oblique stages were observed during eccentric and nonvertical impacts. Subsequently, dimensionless time (t*) and the rate of increase of the gas-liquid interfacial area (η) were introduced to quantitatively analyze the dispersion characteristics postimpact. Increasing the initial velocity, reducing the droplet diameter, minimizing the impact eccentric distance, and maximizing the impact angle all contribute to enhanced dispersion performance. A correlation for the maximum increase rate of the gas-liquid interfacial area of the droplet was proposed, with errors less than ±15%. Finally, the deformation mechanism of droplet impact on a fiber was summarized by analyzing the influences of differential pressure inside and outside the liquid film, as well as gas vortices.

Sand control during gas production from marine hydrate reservoirs by using microbial-induced carbonate precipitation technology: A feasibility study

Sand production is one of the bottleneck problems restricting the safe and efficient production of marine hydrate reservoirs. Current research on this issue mainly focuses on the active sand control methods such as screen mesh and gravel packing, however, passive methods are rarely reported. In this study, a novel sand control strategy which uses microbial-induced carbonate precipitation (MICP) technology to reinforce hydrate reservoirs around the well is proposed. Based on the geological data of hydrate reservoirs in Japan, a reservoir-scale microbial reaction-migration model is established. The feasibility of MICP reinforcement to prevent sand production is demonstrated by the combinations of indoor triaxial testing, productivity prediction and microscopic sand production prediction. The results show that the MICP technology can effectively enhance reservoir strength, and has a negligible impact on the gas recovery. Although the calcium carbonate generated will slightly decrease the porosity and permeability, the cumulative gas production does not significantly decrease and the water extraction is also prevented. Most importantly, the amount of sand production can sharply reduce because of the cementation of calcium carbonate among sand particles. Additionally, the effectiveness and applicability can be improved by selecting appropriate bacteria fixation methods and grouting pressure at different stages.

Liquid dispersion behaviors in a rotating packed bed with different packing arrangements: A comparison study

Wire mesh packing is widely used in the rotating packed bed (RPB). Packing arrangements have been proven to influence the mass transfer of an RPB. However, the liquid dispersion behaviors including dispersion characteristics and mechanisms for packing with different arrangements require further study. In this work, the dispersion behaviors of wire mesh packing with coiled and concentric arrangements were compared. An in-situ Doppler optical probe method was firstly employed to obtain fundamental parameters of liquid dispersion characteristics, such as the Sauter mean diameter, size distribution, and velocity of liquid droplets. The obtained results showed that the coiled arrangement was conducive to generating droplets with large velocity and narrow size distribution owing to the capturing and spreading of liquid inside the packing, while the concentric arrangement was beneficial in decreasing droplet size due to the shearing and carrying actions of the packing. Based on the optimization of liquid dispersion, the max and average reductions of d32 were 34.8% and 19.0% for packing with concentric arrangement than a coiled one. Further comparison results of dispersion characteristics indicated that the optimized concentric arrangement with 3 layers could provide better liquid dispersion than that of a coiled one with around 20 layers.

Spatially-assembled binary carbon anode synergizing directional electron transfer and enriched microbe accommodation for wastewater treatment and energy conversion: From simulation to experiments

Bioelectrochemical systems (BESs) hold prospects in wastewater energy and resource recovery. Anode optimization is important for simultaneous enhancement of wastewater energy conversion and effluent quality in BESs. In this study, a multi-physics model coupling fluid flow, organic degradation and electrochemical process was constructed to guide the design and optimization of BES anodes. Based on the multi-physics simulation, spatially-assembled binary carbon anodes composed of three-dimensional carbon mesh skeleton and granular activated carbon were proposed and established. The granular activated carbon conducive to microbe accommodation played a vital role in improving effluent water quality, while the carbon mesh skeleton favoring electron collection and transfer could enhance the bioelectricity output. With an average chemical oxygen demand (COD) removal rate of 0.442 kg m−3 d−1, a maximum power density of 20.6 W m−3 was achieved in the optimized composite anode BES, which was 25% and 154% higher than carbon mesh skeleton BES and granular activated carbon BES. Electroactive bacteria were enriched in composite anodes and performed important functions related to microbial metabolism and energy production. The spatially-assembled binary carbon anode with low carbon mesh packing density was more cost-effective with a daily energy output per anode cost of 221 J d−1 RMB−1. This study not only provides a cost-efficient alternative anode to simultaneously improve organic degradation and power generation performance, but also demonstrates the potential of multi-physics simulation in offering theoretical support and prediction for BES configuration design as well as optimization.

CFD microscale modelling of flow behavior in different parts of a rotating packed bed

Process intensification (PI) is playing a key role in alleviating the challenge of reducing carbon footprint of many chemical processes and bringing down their development costs. Over the years, many PI technologies have been investigated with rotating packed bed (RPB) technology receiving much of the attention for its potential of significant intensification in terms of capital expenditure, operating costs, and hardware size. In this study, microscale CFD simulations of a rotating packed bed were conducted, and the results were validated with experimental data. The results show the strong relation between the reverse flow at the packing outer periphery and the gas maldistribution factor. The latter is mainly caused by the accelerating flow in the outer cavity. Inside the wire mesh packing, the gas flow is found to be almost fully uniform for nearly half of the total packing depth. Also, turbulent kinetic energy (TKE) levels at the packing outer edge are strongly linked to the slip tangential velocity component, while at its inner edge, they depend mainly on the radial packing velocity. The so-called gas end effect zone is detected by observing the TKE profiles near the packing outer edge. The latter accounts for less than 10% of the total packing depth. The validity of the widely used porous media model in RPBs’ packing for both radial and tangential directions is confirmed by the obtained results, but this excludes the packing inner and outer edges. In the inner cavity region, gas exhibits two distinctive behaviors and transits from free vortex flow to swirling flow as the flow becomes close to the vortex core. As a result of this transition, the increase in shear stress accelerates the decrease in the gas tangential velocity in the vortex core and help speed up the favorable pressure gradient and flow establishment beyond the vortex core.

Zastosowanie programowania nieliniowego dla konfiguracji systemu wymiany ciepła w aparatach kolumnowych przemysłu petrochemicznego przy minimalnych kosztach

For increasing the efficiency of heat transfer processes, the layer-by-layer concept of arrangement of various types of packings in column apparatuses is considered. The results of hydraulic tests of a dry and irrigated cell packing, as well as individual hydraulic tests of a mesh packing, are presented. Methods and algorithms for solving linear programming problems under “uncertainty” conditions were considered. However, in some areas of science it is often difficult or impossible to formalize the problem in an appropriate way and reduce it to a linear programming problem. In this paper, methods for solving non-linear programming problems with a vector objective function are considered. At present, the use of non-linear programming in the vast majority of real situations is reduced to linear approximation models. Along with this, at a significant non-linearity, due to its specificity or influence on the nature of the model, it is necessary to apply optimization methods that are much more complex than, for example, the simplex method. However, the importance of non-linear programming is constantly increasing. This is due to the rapidly growing knowledge of managers and specialists in the use of mathematical models designed to prepare solutions, as well as the increasing availability of computer programs for solving large-scale nonlinear problems. The analysis and studies of the hydrodynamics of a number of regular packings have shown that cell and mesh packings are promising for the implementation of the phase inversion mode. The proposed concept of intensifying heat transfer processes in column apparatuses is based on the use of layers of various packings arranged in the following order in the apparatus, type 1 – cell, type 2 – mesh. At the same time, their main geometric characteristics differ significantly from each other. However, the structure of the bulk packing is inhomogeneous, which makes it difficult to implement a stable mode of local phase inversion under these conditions. This is due to the structure of column apparatuses with bulk packing, in which there is an increased proportion of pores (porosity) near the walls of the apparatus. Porosity is very significant; it can reach up to 40%, and as a result, the local velocity near the walls exceeds the velocity in the centre of the apparatus by up to 70%. By contrast, the use of regular packing structures makes this potentially highly efficient mode technically possible.

A method for establishing a bearing residual life prediction model for process enhancement equipment based on rotor imbalance response analysis

A rotating packed bed is a typical chemical process enhancement equipment that can strengthen micromixing and mass transfer. During the operation of the rotating packed bed, the nonreactants and products irregularly adhere to the wire mesh packing in the rotor, thus resulting in an imbalance in the vibration of the rotor, which may cause serious damage to the bearing and material leakage. This study proposes a model prediction for estimating the bearing residual life of a rotating packed bed based on rotor imbalance response analysis. This method is used to determine the influence of the mass on the imbalance in the vibration of the rotor on bearing damage. The major influence on rotor vibration was found to be exerted by the imbalanced mass and its distribution radius, as revealed by the results of orthogonal experiments. Through implementing finite element analysis, the imbalance response curve for the rotating packed bed rotor was obtained, and a correlation among rotor imbalance mass, distribution radius of imbalance mass, and bearing residue life was established via data fitting. The predicted value of the bearing life can be used as the reference basis for an early safety warning of a rotating packed bed to effectively avoid accidents.

Improving the Performance of Unglazed Solar Air Heating Walls Using Mesh Packing and Nano-Enhanced Absorber Coating: An Energy–Exergy and Enviro-Economic Assessment

This study aims to upgrade the effectiveness of unglazed solar air heating walls (SWs) using mesh packing and nano-enhanced black paint. In this regard, two SW cases with 10 cm and 15 cm plenum thicknesses have been fabricated and tested simultaneously with different modifications. In other words, six different SW configurations have been designed and empirically investigated in this research. Unmodified SWs with two plenum thicknesses have been tested in the first experiment. Iron meshes have been utilized in both SWs in the second test. In the third experiment, the impact of the combined usage of mesh packing and Fe (iron) nanoparticle-enhanced black paint (absorber coating) at 2% w/w concentration on the performance has been evaluated. Experimental results exhibited that the combined usage of mesh packing and nano-doped paint in the SWs with 10 cm and 15 cm plenum thicknesses improved the average effective efficiency value by 29.54% and 31.20%, respectively, compared to the unmodified cases. Also, the average exergy efficiencies of the six tested SW configurations were attained in the range of 6.24–12.29%. Moreover, the findings of this study showed that reducing the plenum thickness and applying the combination of meshes and nano-coating improved the annual carbon dioxide savings by 44.72%.

Experimental investigation of a modified parallel stack for wet thermoacoustic engine to improve performance and suppress harmonics

When compared to the ‘classical’ thermoacoustic engines, the major drawbacks of Wet Thermoacoustic Engine (WTE) are their ambiguous mechanism of condensable liquid ingestion, cessation of continuous operation and the domination of higher harmonics. In this study, an approach to address these issues is presented via a novel design of stack. A closely packed mesh screen matrix is inserted between the two plates of ‘parallel stack’, which is intended to contain condensable liquid for WTE. This modified design is proposed to gain from the enhanced heat transfer area and the prevention of higher harmonics production. The effect of the different geometrical features and design parameters of the stack on the engine's performance is investigated experimentally for a standing wave WTE. Onset temperature difference, acoustic power, harmonics ratio and fundamental frequency are measured for the variations in plate spacing, mesh packing density, mesh number, and mesh packing length. An optimum design of the stack within the parametric space of the study is obtained and the underlying physics behind the observed behavior is reported. For the optimum configuration, the generation of higher harmonics is reduced to 58% and the maximum acoustic power is generated at a low onset of 13∘C.

Study on the Solid–Liquid Mass-Transfer Performance of Suspension in a Rotating Packed Bed

This work presents the study on solid–liquid mass-transfer performance of suspension in a rotating packed bed (RPB). The calculation model of solid–liquid mass-transfer coefficient (kS) is deduced on the basis of the mass conversation law. The kS in RPB is measured using the suspension of cation-exchange resin particle reaction with NaOH solution. The effects of different operating conditions such as the dispersion time (t) in a stirred tank reactor (STR), the rotating speed (N), the mesh packing thickness (w), the liquid volume flow rate (LT), and the solid loading (e) on the RPB are investigated. The results show that kS increases with the increase of N and w; it increases first and then tends to remain constant with the increase of t and LT. However, e has little influence on kS. A nondimensional equation for Sh is established, and the predicted and experimental values of Sh are in good agreement with a deviation within ±15%. Furthermore, the maximum value of Sh of 124 is obtained under the conditions, t = 0.5 h in STR, N = 2200 rpm, LT = 56 L/h, e = 15 g/L, and w = 24 mm, which is higher than those in the microreactor (MR) and STR. Here, RPB exhibits great application potential in the solid–liquid mass-transfer or reaction process.

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.

Carbon dioxide capture in a HiGee reactor with packing featuring controllable cross-sectional area

A rotating packed bed (RPB), as one of the typical HiGee reactors, has achieved extensive praise in CO2 capture fields. In this work, the novel mesh packings with controllable cross-sectional areas (CSAs) were applied to intensify the CO2 absorption process in an RPB, as well as combining with the blended aqueous amine solutions including diethylenetriamine (DETA) and piperazine (PZ). The gas pressure drop and CO2 absorption performance of various packings were investigated. Different operating conditions including rotational speed (400–2400 r/min), liquid flow rate (10–35 L/h), gas flow rate (900–2400 L/h), and CO2 molar fraction in gas inlet (2–12%) were considered. The results exhibited that the rise in gas pressure drop of concentric packing with constant CSA (CONC-9) relative to conventional coiled packing with increasing CSA (COII-9) was less than 10% on average. Meanwhile, the CO2 absorption efficiency of CONC-9 exceeded 17.1% on average than that of COII-9. For further comparison, the ratio of mass transfer coefficient to gas pressure drop in the wet RPB (KGa/△PW) was analyzed. The KGa/△PW of CONC-9 was 48.6% larger on average than that of COII-9. The average mass transfer coefficient and height of mass transfer unit of CONC-9 reached up to 16.7 kmol∙kPa−1∙m−3∙h−1 and 0.013 m, respectively. Overall, it is a viable way to adopt the packing with constant CSA to intensify the CO2 absorption in RPBs.

Liquid flow behavior in the concentric mesh packing with novel fiber cross-sectional shape in a rotating packed bed

Mesh packing has been widely exploited in rotating packed beds (RPBs). Fiber cross-sectional shape (CSS) of mesh has exhibited significant influence on liquid flow behavior. The concentric mesh packing outperforms conventional coiled mesh packing in mass transfer. However, in-depth insights into liquid flow characteristics in concentric mesh packing, especially with novel fiber CSS, which is indispensable for mass transfer modelling, are scarce. Herein, the liquid flow behavior in concentric mesh packing composed of vertical quadrangular fibers and horizontal elliptical fibers (VQHE) and the packing composed of circular fibers (VCHC) were investigated via high-speed photography technology in an RPB. Typical liquid flow patterns and their transition in packings were illuminated. The liquid film covered wider regions in VQHE than that in VCHC. The transition criteria for flow patterns has been proposed. The VQHE reduced the average droplet diameter by 19%, enhanced the uniformity of droplet size distribution, and decreased average droplet velocity by 15%, compared to VCHC. Furthermore, correlations to predict the average droplet diameter and velocity were developed with deviations of ±15% and ±20%, respectively.

Research and development of advanced structured packing in a rotating packed bed

As the core component of the rotating packing bed, packing is a place for efficient gas–liquid mixing and mass transfer. In this paper, a 3D structured packing composed of a mesh structure and a support structure was designed. The mesh structure is a ring-shaped mesh surrounded by triangular meshes, which is stable in structure and can achieve a high degree of dispersion and aggregation of the liquid phase. The support structure is composed of ring-shaped structural units arranged at a certain angle along the axial direction, which can enhance the turbulence of the airflow while constructing regular gas-phase channels. Circumferential steel meshes of different diameters and supporting structures are alternately combined to form 3D packing, which is loaded in a layered cross-flow rotating packing bed. The results show that under the same operating conditions, the mass transfer performance of 3D packing and wire mesh packing are equivalent, and both are better than pall ring packing. Moreover, the pressure drop of 3D packing is significantly lower than that of pall ring packing and wire mesh packing. The design and implementation of packing the development presented in this paper can be used to develop special structured packing for rotating bed, which can further improve the performance of rotating packed bed (RPB).

Liquid-phase mass-transfer processes in packings with a segregated flow model

Liquid back mixing behavior has significant influences on the liquid-side mass-transfer coefficient in packed columns and rotating packed beds(RPBs). And the liquid-side mass-transfer coefficient without the liquid back mixing behavior is called a liquid-side intrinsic mass-transfer coefficient. A ratio of the liquid-side mass-transfer coefficient to the liquid-side intrinsic mass-transfer coefficient is defined as a liquid-side mass-transfer coefficient factor. The lower coefficient factor means the bigger reduction in the liquid-side mass-transfer coefficient. A segregated flow model in packings is developed. From the model, the liquid back mixing effect is first separated from the liquid-side mass-transfer coefficient and is then involved in the coefficient factor, and equations of the liquid-side intrinsic mass-transfer coefficient and coefficient factor are derived. Values of the liquid-side intrinsic mass-transfer coefficient and coefficient factor of oxygen desorption from water in Flexipac 2 structure packing in a packed column were calculated. The values of the intrinsic mass-transfer coefficient were in good agreement of a deviation of 0.58 % with the predictions by theoretical mass-transfer model. Values of the coefficient factor of oxygen desorption from water in a RPB with wire mesh packing were also obtained. Values of the coefficient factor in the RPB rotor were much lower than those in the packed column due to a highly intensified mass-transfer and a higher liquid back mixing in the RPB rotor as compared with those in the packed column. The best method to increase the coefficient factor is to reduce the liquid back mixing and to increase the liquid flow rates in packed columns and RPBs.

A correlation for average droplet diameter in rotating packed beds

AbstractA rotating packed bed (RPB) is a novel process intensification technology that increases mass transfer rate using a strong centrifugal acceleration. Inside an RPB, the inlet jet of the liquid absorbent is broken into tiny droplets. It is reported that RPBs provide 11 times larger mass transfer area compared to equal‐sized packed beds and two to three orders of magnitude higher mass transfer compared to equal‐sized stirred tanks. The novelty of the technology and lack of research, however, undermines the adoption of RPBs where a low mass transfer rate is the main bottleneck. In this work, we study the effect of bed size on the average droplet diameter in RPBs and investigate scale‐up criteria to preserve the average droplet diameter at a large scale. Furthermore, we develop a correlation for the average droplet diameter using the experimental data and simulation results obtained using a volume of fluid (VOF) method. This correlation is obtained from dimensional analysis. The effects of rotating speed, absorbent flow rate, wire mesh packing diameter, bed diameter, absorbent viscosity, density, and surface tension are included in the dataset. Among these parameters, rotating speed, centrifugal force, and surface tension have the highest correlation coefficients (R2 = 0.88, 0.83, and 0.42, respectively) with the average droplet diameter.

Dispersion characteristics of liquid jet impacting on the rotating single-layer wire mesh with different surface wettabilities

Wire mesh packing is widely used in rotating packed bed reactor to intensify mass transfer of multiphase systems. As an essential parameter of wire mesh, surface wettability was expected to regulate liquid dispersion to influence the mass transfer performance. Hence, the effect of surface wettability on dispersion characteristics of liquid jet impacting on the rotating single-layer wire mesh was investigated via visualization and simulation methods. Three flow patterns, including linear-ligament, curved-ligament, and droplet, were observed. Results indicated that hydrophobic horizontal fiber not only promoted the radial dispersion, but also generated a large axial dispersion angle of liquid. Simulation results revealed that surface wettability influenced the velocity distribution and separation points of the impacting liquid, leading to different dispersion phenomena. Increasing the surface hydrophobicity, liquid initial velocity, and rotational speed could promote the liquid dispersion performance, thereby achieving larger liquid specific surface area (as). Furthermore, correlations to calculate as were proposed with deviations of ±20%.

Desulfurization performance in a HiGee reactor with packing containing different fiber cross-sectional shapes

HiGee reactors have been utilized for H2S removal from offshore natural gas by chelated iron solution, which exhibits great advantages due to their compact footprint. However, the blockage of packing in HiGee reactor caused by sulfur generation can lead to a decline of desulfurization efficiency. Herein, the fiber cross-sectional shape of mesh packing was optimized for alleviating blockage based on the understanding of liquid flow behavior with various single-layer meshes in our previous studies (Wen et al., Chem. Eng. Sci. 2022, 248, 117147). The novel packing with vertical quadrangular fibers and horizontal elliptical fibers (VQHE) as well as the conventional packing with circular fibers (VCHC) were designed and fabricated by three-dimensional printing technology. A rotating packed bed (RPB) reactor with mesh packing, as one of the typical HiGee reactors, was adopted for H2S removal. Results indicate that H2S removal efficiency of VQHE could reach up to 99.3%. The mass transfer coefficient of VQHE was 25.9% higher than that of VCHC. Meanwhile, the photograph displays that less sulfur solid was deposited on the surface of VQHE. The mass increase ratio of VQHE was smaller by 24.9% than that of VCHC. VQHE realized the integration of enhancing H2S removal efficiency and alleviating blockage in RPB reactor.

Modeling of gas–liquid flow in a rotating packed bed using an Eulerian multi‐fluid approach

AbstractRotating packed beds (RPBs) are ideal candidates for CO2 removal from offshore natural gas due to their good mass transfer performance and significant volume savings. This article proposes an Eulerian multi‐fluid approach to simulate the gas–liquid flow in RPBs. Three new multiphase drag force models are constructed based on single‐phase drag force models for wire mesh packings. Based on the Eulerian multi‐fluid approach, a new RPB simulation framework is developed. The predicted results using the new simulation framework with the new drag force models are compared with the experimental data. When using the Kołodziej model and the modified Kołodziej model, the predicted overall liquid holdup shows good agreement with the experimental data with errors less than 20%. In addition, the pressure drop predicted by these three models are reasonable compared with the experimental data. This work lays a foundation for RPB simulation of gas–liquid flow using Eulerian multi‐fluid approach.

Enhancement of devolatilization performance in a rotating packed bed with different packing structures

• The 3D-printed mesh packing with drop-shaped fibers (PMP-D) was manufactured. • The PMP-D was employed to enhance the devolatilization performance in RPB. • Compared with traditional SMP, the η and K L a of PMP-D was drastically improved. • Correlations to predict K L a were established with deviations less than ±20%. The devolatilization of volatile organic compounds (VOCs) from the viscous liquid like polymers was necessary but of great challenge caused by the high viscosity. In this work, different packing structures were manufactured in a rotating packed bed (RPB), including the stainless steel wire mesh packing (SMP), 3D-printed column packing (PCP), 3D-printed mesh packing with circular fibers (PMP-C), and 3D-printed mesh packing with drop-shaped fibers (PMP-D). The devolatilization performance of the RPB was investigated with the acetone-silicon oil working system. Results indicated that modifying the fiber shape of packing effectively intensified the devolatilization in the RPB. The removal efficiency ( η ) and volumetric mass transfer coefficient ( K L a ) of the PMP-D were dramatically larger than the other three packings. Compared the PMP-D with the traditional SMP, the maximum η was enhanced from 40% to 50%, and the increment of K L a was 50% on average. The correlations to predict K L a were established, and the deviations from the experimental results were less than ± 20%.