Cyclone Separator Research Articles

Hybrid copper-polyelectrolyte nanoaggregates obtained with smart block copolymers based on 4-[(hydroxyimino)aldehyde]butyl methacrylate (HIABMA) in water and acetonitrile

The AB multi-stimuli-responsive block copolymer pTEGMA-b-pHIABMA (TEGMA: tetra(ethyleneglycol) methyl ether methacrylate; HIABMA: 4-[(hydroxyimino)aldehyde]butyl methacrylate) comprises a hydrophilic and thermoresponsive PTEGMA block linked to the hydrophobic PHIABMA chain. The latter is endowed with slightly acidic oxime groups that potentially form complexes with metal ions. Here we investigate the formation of hybrid Cu(II)-polymer nanoaggregates both in water and in acetonitrile. Cu(II) ions are quantitatively and rapidly incorporated, in the presence of a base, into pre-formed polymeric core-shell micelles (30 nm diameter by DLS) in water up to 1:2 metal-to-ligand stoichiometry. The pKa of the polymer is decreased from ≅11.2 to 4.65 due to interaction with Cu(II) and the complex is shown to involve oximate ions. The thermoresponsivity of the polymeric micelles remains unchanged with Cu(II) complexation and allows an easy separation by flocculation of the hybrid complex. Moreover, nanoaggregates (D = 20 nm) form in acetonitrile from the fully solubilized copolymer interacting with Cu(OAc)2. The 1:2 Cu(II)/ligand stoichiometry is confirmed with the Job graphical method. Characterization of the hybrid micelles was carried out by UV–Vis spectrometry, DLS, TEM, STEM and SAXS. Quantitative release of Cu(II) in acidic conditions is demonstrated both in water and in acetonitrile. Full recovery of the free metal ions and of intact polymeric micelles is achieved through centrifugal filtration of the aqueous preparation, as a proof-of-concept for a recyclable system for metal uptake and release. Furthermore, Cu0 nanoparticles of 5–10 nm are obtained through reduction of Cu(II) within the micelles with ascorbic acid in aqueous solution.

Effect of concave‐wall jets with circumferential multi‐inlet on liquid–solid separation

AbstractThis study combined numerical simulation and experiment to explore the influence of the concave‐wall jets with uniformly distributed tangential inlets in the cyclone separator on the liquid–solid separation characteristics and equipment. The results show that as the number of tangential inlets increases, the superposition effect of particle trajectories and flow fields becomes more significant. The superimposed flow field enhances the circumferential flow velocity of the fluid, causing the distribution of the jet along the radial and spanwise directions to shrink, greatly improving the uniformity of particle distribution and turbulent kinetic energy along the circumference, and effectively reducing the impact of particles on local areas near the jet inlet. Since the superposition of circumferential multi‐inlet jets enhances the swirling flow, the local disturbance and wall erosion effects near the jet inlet were reduced. Compared with double inlets, the flow rates of three inlets and four inlets were increased by 50% and 100%, respectively, the maximum turbulent kinetic energy increased by 14.5% and 56.2%, and the maximum escape time of particles was shortened by 3.2 and 3.3 s, respectively, the maximum erosion rates were reduced by 38.4% and 23.6%, respectively, and the separation efficiency and material handling capacity were significantly improved. This study supplemented the theory of concave‐wall jets' superposition characteristics and provided a theoretical basis for applying circumferential multi‐inlet devices in liquid–solid separation equipment.

Determination of an axial gas cyclone separator cut-off point by CFD numerical modeling

Determination of an axial gas cyclone separator cut-off point by CFD numerical modeling

Production of High-Yield Adeno Associated Vector Batches Using HEK293 Suspension Cells.

Adeno-associated viral vectors (AAVs) are a remarkable tool for investigating the central nervous system (CNS). Innovative capsids, such as AAV.PHP.eB, demonstrate extensive transduction of the CNS by intravenous injection in mice. To achieve comparable transduction, a 100-fold higher titer (minimally 1 x 1011 genome copies/mouse) is needed compared to direct injection in the CNS parenchyma. In our group, AAV production, including AAV.PHP.eB relies on adherent HEK293T cells and the triple transfection method. Achieving high yields of AAV with adherent cells entails a labor- and material-intensive process. This constraint prompted the development of a protocol for suspension-based cell culture in conical tubes. AAVs generated in adherent cells were compared to the suspension production method. Culture in suspension using transfection reagents Polyethylenimine or TransIt were compared. AAV vectors were purified by iodixanol gradient ultracentrifugation followed by buffer exchange and concentration using a centrifugal filter. With the adherent method, we achieved an average of 2.6 x 1012 genome copies (GC) total, whereas the suspension method and Polyethylenimine yielded 7.7 x 1012 GC in total, and TransIt yielded 2.4 x 1013 GC in total. There is no difference in in vivo transduction efficiency between vectors produced with adherent compared to the suspension cell system. In summary, a suspension HEK293 cell based AAV production protocol is introduced, resulting in a reduced amount of time and labor needed for vector production while achieving 3 to 9 times higher yields using components available from commercial vendors for research purposes.

Performance and techno-economic evaluation of a high-efficiency electrospray cyclone

"Nowadays, because of the global air pollution issue caused by fine dust, fine dust collection and removal technologies are crucial for enhancing living environments and human health. This research proposes a new pilot-scale electrospray cyclone (ESC) designed for the collection of submicron dust particles. The experimental apparatuses comprised a cyclone dust collector and an insulating tank. Initially, laboratory-scale single-nozzle visualization tests were conducted to investigate the droplets’ number and size under various operating conditions. Subsequently, based on the visualization research outcomes, electrospray module was inserted to the industrial cyclone, which was designated by ESC. Performance assessments of the pilot-scale ESC were conducted under diverse water flowrates, applied voltages and nozzle sizes. The capture efficiencies for PM10, PM2.5, and PM1.0 were measured up to 98.2%, 95.4%, and 90.3%, respectively. Both the environmental and economic viabilities of the newly-proposed ESC in this study were evaluated based on three aspects: 1) capacitive particle collection efficiency; 2) capacitive installation cost; and 3) rated power and operational cost. This evaluation method has been defined as the Levelized Cost of Precipitator (LCOP), and it is intended to assess the environmental and economic performance of 5-convenstional dust collectors. In these results, the ESC shows relatively high performance in terms of the environmental and economic aspects. Based on these indices, we assess that the ESC has one of the promising alternatives of commercial precipitators."

Drone-Assisted Particulate Matter Measurement in Air Monitoring: A Patent Review

Air pollution is caused by the presence of polluting elements. Ozone (O3), carbon monoxide (CO), carbon dioxide (CO2), nitrogen dioxide (NO2), sulfur dioxide (SO2), and particulate matter (PM) are the most controlled gasses because they can be released into the atmosphere naturally or as a result of human activity, which affects air quality and causes disease and premature death in exposed people. Depending on the substance being measured, ambient air monitors have different types of air quality sensors. In recent years, there has been a growing interest in designing drones as mobile sensors for monitoring air pollution. Therefore, the objective of this paper is to provide a comprehensive patent review to gain insight into the proprietary technologies currently used in drones used to monitor outdoor air pollution. Patent searches were conducted using three different patent search engines: Google Patents, WIPO’s Patentscope, and the United States Patent and Trademark Office (USPTO). The analysis of each patent consists of extracting data that supply information regarding the type of drone, sensor, or equipment for measuring PM, the lack or presence of a cyclone separator, and the ability to process the turbulence generated by the drone’s propellers. A total of 1473 patent documents were retrieved using the search engine. However, only 13 met the inclusion criteria, including patent documents reporting drone designs for outdoor air pollution monitoring. Therefore, was found that most patents fall under class G01N (measurement; testing) according to the International Patents Classification, where the most common sensors and devices are infrared or visible light cameras, cleaning devices, and GPS tracking devices. The most common tasks performed by drones are air pollution monitoring, assessment, and control. These categories cover different aspects of the air pollution management cycle and are essential to effectively address this environmental problem.

Effect of Different Outlet Structure of Axial Flow Cyclone Separator in Drying Tower

The axial flow cyclone separator used in drying tower is characterized by the diameter of the dust outlet at the tail is larger than that of the cylinder, and the dust removal efficiency is increased by a series dust outlet. The numerical analysis of its separation characteristics is carried out by using the RSM model of CFD. The results show that the separation efficiency can be increased by appropriately increasing the diameter of the dust outlet, and the separation efficiency will not change when the diameter of the dust outlet increases to a certain value. When the insertion depth of the air outlet is reduced from 150mm to 100mm, the average separation efficiency of particles with a diameter of 15-30um is reduced by 4.5%. When the insertion depth of the air outlet is greater than the width of the dust outlet, the insertion depth has no effect on the dust removal efficiency. The tandem dust outlet and parallel dust outlet have the same separation effect on small particles, and the gas flow rate is equivalent to twice the gas flow rate of a single dust outlet. The average particle separation efficiency of 1 - 30um is increased by 16.5% compared with that of a single dust outlet. The flow velocity of the tandem dust outlet is higher than that of the parallel dust outlet.

Designing Centrifugal Membrane Filters with uniform-pressure for UF/NF/RO separations

A novel Ortho-Centrifugal Membrane Filter (O-CMF) was designed and assessed to tackle common issues in conventional laboratory centrifugal membrane filters, e.g. non-uniform transmembrane pressure and concentration polarization, and to ease membrane replacement. The O-CMF, manufactured by additive 3D printing in acrylonitrile butadiene styrene, with membrane area of 0.95 cm2, was designed to process a maximum liquid sample of 9 mL. It was tested with nanofiltration of aqueous solutions of NaCl, MgSO4, and lactose (concentrations of 1–20 g/L) at transmembrane pressures of 6–24 bar. Complementary Computational Fluid Dynamics (CFD) simulations, employing a custom solver from the open-source OpenFOAM-2306 c++ toolbox, were also run to seek insight of the O-CMF main features.The permeation experiments displayed minimal impact of concentration polarization. CFD simulations showed that concentration polarization is nearly uniform and that concentrate chamber is homogenized by centrifugal convection. The CFD permeate flux predictions, based on the osmotic pressure model, closely matched experimental data, and a correlation for predicting concentration polarization was also developed.The O-CMF device represents a substantial breakthrough in the technology of centrifugal membrane filters, consistently maintaining uniform transmembrane pressure and effectively minimizing concentration polarization. The device was evaluated using nanofiltration, but its pressure range is versatile enough to cover conditions suitable for both ultrafiltration and reverse osmosis operations. This adaptability extends its application across a variety of laboratory experiments, including sample concentration, hydraulic permeability tests, and membrane screening.

Experimental and numerical investigation of the elliptical cyclone separator manufactured by 3D printing

Whether the cyclone separators have a high-efficient body shape is a problem that has been ignored for a long time. A series of cyclones with elliptical bodies were designed and manufactured by SLA 3D-printing. The separation performance and flow field of the cyclones were investigated using the experimental and CFD methods, respectively. The detailed flow features, such as streamlines, pressure and velocity profile distribution, and special flow phenomena of the circumferential acceleration/deceleration of the swirling gas, are analyzed. The experimental results reveal that the elliptical cyclones with a/b = 1.2 and 0.83 have about 2% increment of separation efficiency and 43% reduction of pressure drop, as well as satisfactory robustness to the particle properties and operating conditions. The circumferential acceleration/deceleration of the swirling gas creates an additional inertial force for the particles, thereby improving the elliptical cyclones' performance. The results provide innovation ideas for designing and manufacturing the better-performance cyclones.

A study on the characteristics and geometric optimization of a cyclone filter

Cyclone separator without filter is a common device used for separating solid–liquid/gas–solid/gas–liquid mixtures, which is widely used in chemical and household appliance industries. It has the advantages of high separation efficiency and low susceptibility to clogging. However, its separation efficiency cannot reach 100%, and some particles that enter the separator are not separated and will cause secondary pollution to downstream fluids. Combining the cyclone separator with a mesh filter to form a cyclone filter can achieve the complementary advantages of both, namely, high filtration efficiency and low susceptibility to clogging. For cyclone filters, particle shape has a significant impact on filter clogging, but there are few reports on this issue in the literature. In this paper, a new type of cyclone filter is proposed, and experimental and simulation methods are used to study its resistance characteristics. It is found that compared with the case of no filter, the flow resistance of the cyclone filter is significantly reduced, and the reason for the reduction in resistance is analyzed based on flow field analysis. The movement trajectory of flat and spherical particles in the cyclone filter and the problem of particle clogging on the filter are then studied. It is found that flat particles are more likely to cause clogging on the filter, and the reason for the clogging of the filter in the inlet area of the cyclone filter and the mechanism by which flat particles are more likely to clog the filter in the inlet area are analyzed based on the flow field and particle force in the separator. Finally, the inlet profile of the cyclone filter is optimized, and the changes in the inlet flow field and particle movement trajectory before and after optimization are compared. The problem of flat particle clogging on the filter is ultimately solved.

Design and development of a continuous harvesting system using solid-liquid cyclone separator for harvesting of Dunaliella salina for mass production of biomass: Part-1: Performance in single-stage

Microalgae is a viable alternative to depleting conventional fuel sources, a solution to the industrial requirement of organic consumables, and an option for a green and sustainable economy for biofuels, pigments, and nutrient production. Dunaliella salina is an efficient choice among various species due to its high lipid/carotenoid content and growth in extreme saline conditions. Existing batch-production harvesting methods, such as centrifugation and flocculation, are neither inexpensive nor environmentally benign. This paper presents the experimental studies on three different Rietema-type solid-liquid cyclone separators (RSLCS) for continuous harvesting of microalgae as a concentrated trap for mass biomass production to achieve an economy for biofuels and other desirable by-products if required. Two of these RSLCS were modified and had two inlets (orthogonal RSLCS and parallel RSLCS) when compared with conventional RSLCS. The experiments were performed to calculate the growth of microalgae culture on different days (Day-7, 14, 21, and 28), and concentrations of outflows on day-28 were used as feed for all the RSLCS. The recorded separation efficiency for conventional, orthogonal, and parallel RSLCS are 61.66 %, 67.95 %, and 60.14 % respectively. CFD simulations were also done to validate the results, and CellProfiler was used to measure the size of Dunaliella salina for hydrodynamic analysis. The CFD simulations showed separation efficiency of 60.72 %, 67.04 %, and 59.52 % for conventional, orthogonal, and parallel RSLCS. Thus, the use of orthogonal RSLCS is proposed as a simple, cheap, and eco-friendly solution to the industry-level requirement of continuous harvesting for microalgae in replacement of existing batch-production techniques.

Numerical Study of the Gas–Solid Separation Performance of Axial Flow Cyclone Separators

Cyclone separators, which have a high separation performance, play a crucial role in mitigating the occurrence of dust explosion incidents. This study aims to improve the performance of an axial cyclone separator using the results of simulations employing the RNG k-ε model together with a user-defined function to simulate the wall collision process. The effectiveness of various structural modifications to the vortex tube has been addressed. Specifically, we found that increasing the number of blades, reducing the blade exit angle, and adopting L-shaped blades increase separation efficiency. Additionally, enlarging the guide vane and exhaust pipe diameters, as well as increasing the exhaust pipe inclination angle, contribute to an improved separation performance due to the developed tangential velocity and vortex cores. However, it also increases the pressure drop losses due to the increase in the turbulence pulsation entropy and the wall entropy, while the time-averaged entropy is found to be less significant. As a result, our study sheds light on the flow characteristics, the gas–solid separation process, and the energy loss mechanism in the cyclone separator.

Abstract 3207: Chemical fabrication and characterization of a novel nanoparticle of the histone deacetylase (HDACi) romidepsin

Abstract Introduction: Histone Deacetylase inhibitors (HDACi) are important drugs for the treatment of patients with PTCL (peripheral T-cell lymphoma). Romidepsin (R), a potent Class I HDACi, is given intravenously, weekly for three to four consecutive weeks. R has a half-life of three hours and is extensively protein bound. The indication for R in PTCL was recently withdrawn due to a failed Phase 4 study. Given the need for new drugs in PTCL, and the importance of epigenetically targeted drugs for the disease, we developed a first-in-class nanoparticle of R (NR) deploying a proprietary nanochemistry platform. Methods: We modified the bulk nanoprecipitation method with FDA approved and Generally Recognized as Safe (GRAS) materials, specifically including PEGylated amphiphilic diblock copolymers, to develop NR combinatorially. By combining a drug and polymer solution with an anti-solvent, we produced core-shell structured NR particles with “stealth” properties. To achieve high R loading, stability, purity, scalability, and reproducibility, we devised a multi-pronged optimization system by modulating parameter sets in tandem. We determined the optimal parameters for the "lockdown" formulation. We purified NR by using centrifugal filters and determined stability by storing at 4°C. We used Cryo-electron microscopy (cryo-EM), Dynamic Light Scattering (DLS), and Liquid Chromatography-Mass Spectrometry (LC-MS) to determine the morphology, size, PDI, and drug concentration of NR. We developed fluorescent-NR with DiO dye to test bioavailability. We tested NR in T-cell lymphoma cell lines for histone acetylation and apoptosis induction. Furthermore, we investigated the in vivo pharmacokinetics and toxicity of NR in PTCL xenograft mouse model and quantified the drug by LC-MS. Results: The physiochemical analysis of NR demonstrated that the particles were spherical, with a hydrodynamic diameter of 46 ±5 nm and PDI of 0.15 - 0.2. NR had a negative zeta potential and an exceptional drug encapsulation efficiency of over 50% (>500 µg/mL). NR exhibited high stability with respect to size, PDI and drug concentration for over two years. Flow cytometry and western blot analyses indicate NR induces apoptosis and histone acetylation in a time and dose-dependent manner, equivalent to or better than that observed for R. NR’s AUC increased 25-fold when administered intravenously. NR had superior tolerability, and DiO-NR confirmed superior biodistribution in tumor in a PTCL xenograft mouse model. Conclusion: We developed a cutting-edge approach with minimum excipients, which enabled NR scale up with batch-to-batch reproducibility and high quality co-packaging of fluorescent dye and drug. NR improved R’s pharmacokinetic profile and efficacy in pre-clinical xenograft mice models. Our versatile technology enables Chemistry Materials and Controls products, an essential step in clinical product development. Citation Format: Samir Zuberi, Deepthi P. Damera, Ipsita Pal, Susan Walker, Ramesh Katla, Colin Haws, Akhil Gajjala, Andrea Joyner, Kallesh D. Jayappa, David J. Feith, Todd E. Fox, Thomas P. Loughran, Owen A. O'Connor, Anuradha Illendula. Chemical fabrication and characterization of a novel nanoparticle of the histone deacetylase (HDACi) romidepsin [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3207.

Enhanced coarse coal slime separation in a gravity–flotation coupled separator with up-flow feeding and dual-concentrate

ABSTRACT A gravity – flotation coupled separator with up-flow feeding and dual-concentrate was developed to improve the recovery and selectivity in coarse coal slime separation. The separator combines flotation, cyclone separation, and gravity sedimentation. The optimal separation performance was achieved under the following conditions: slurry concentration = 100 g/L, feed flow rate = 4.411 m3/h, circulating rate = 3.125 m3/h, fifigfeeding air flow rate = 2 m3/h, frother dosage = 150 g/t and collector dosage = 1500 g/t. Two concentrates were obtained with ash contents of 7.48% and 11.56%. The partition coefficients of the 0.75–1 and 0.5–0.75 mm fractions were 88.42% and 95.92%, respectively, indicating the satisfactory recovery of coarse particles. The ash content in the tailings was 66.08%, indicating good selectivity. The diverging flow under the froth layer produced a coarse concentrate, which improved the recovery of the concentrate and reduced the flotation concentrate ash content. The total recovery of the concentrate blended with the + 0.25 mm fraction of diverging flow was 84.00%. Both up-flow and cyclone separation are beneficial for coarse particle recovery. The static separation cone is instrumental in improving the separation effect. Therefore, this wide-sized coal-slime separator facilitates the effective separation of both coarse and fine particles.

Enhancing the sub-micrometer performance of a uniflow cyclone separator using a built-in stainless steel mesh filter

Although the uniflow cyclone separator has low pressure drop and high collection efficiency compared to other existing cyclone separators, it still has room to improve its collection efficiency of submicron particles. For this reason, we present a new uniflow cyclone separator with an installed mesh filter called the MFUC. The MFUC cyclone body is not made of a solid wall but a stainless steel mesh with porosity. Our research newly revealed that the pressure gradient in the radial direction at the front region of the mesh filter is reversed in the rear region, which can help to remove sub-micrometer particles which are difficult to collect using a basic cyclone separator. The measured MFUC performance showed the synergetic effect of filtration and inertial separation for the removal of fine particles. As the inlet flow rate increases, the inertial separation becomes more effective than filtration. In addition, the cut-off diameter of the MFUC was 0.83 μm at 500 lpm, which is 56.6 % smaller than that of the basic cyclone separator.

Performance evaluation of cyclone separators with elliptical cross-section using large-eddy simulation

In the present study, cyclone separators with elliptical cross-sections have been studied numerically. Five cyclone models are considered here with the normalized (semi-) major axis (a) and minor axis (b) as: (a/D, b/D) = (0.51, 0.49), (0.52, 0.48), (0.53, 0.47), (0.54, 0.46), and (0.55, 0.45), referred to as the models A, B, C, D, and E, respectively. The standard model is of circular cross-section with a body diameter, D = 0.205 m, and is the reference model for performance comparison. It has been ensured that all the cyclones bear a similar hydraulic diameter, and hence, a nearly similar volume. Apart from the pressure drop and collection efficiency, we also evaluate the periodicity associated with the precessing vortex core around the cyclone axis by performing a fast Fourier transformation to the temporal velocity signal. Conclusive results indicate that both the pressure losses as well as collection efficiencies reduce with increasing the major axis (and reducing the minor axis) values. The mean velocity components undergo significant changes than the velocity fluctuations with stretching of the elliptical cross-section. The models with the largest major axis (or smaller minor axis) may be used as pre-separators to remove larger particles at the lowest pressure drop values.

On fluid-saturated poro-hyperelastic rotating cylinder: A centrifugal filtration

One of the applications of porous materials is centrifugal filtration. This study develops the Lagrangian equations that govern a steady-state, fluid-saturated, poro-hyperelastic, axisymmetric rotating cylinder. The formulation assumes incompressible solid and Newtonian fluid constituents to address the filtration process. The differential scheme takes into account the impact of porosity on the reduction of the drained shear and bulk moduli of the solid skeleton. Additionally, the normalized Kozeny-Carman formula considers the effect of porosity changes due to deformation on permeability. The Standard Galerkin Finite Element Method solves the derived equations using FlexPDE. ANSYS is unable to solve the current problem due to the lack of centrifugal and Coriolis accelerations in Darcy's law and its inability to account for changes in initial permeability and porosity resulting from the deformation of the solid skeleton. Therefore, the validation of the governing equations and the applied solution is investigated in three limited cases.It is shown that a rise in the angular velocity causes the expansion in the Von-Mises stress of solid constituent, radial displacement, negative pore pressure, and radial filtration velocity because of the increase in the centrifugal force. Also, the permeability and radial displacement grow with the initial porosity rise. The radial filtration velocity rises with the increased permeability resulting from the deformation. Moreover, drained shear and bulk moduli of the solid skeleton fall with increased porosity, resulting in a rise in the radial displacement. Besides, the radial displacement and filtration velocity expand with the increase of solid and fluid densities.

CFD Simulation of an Industrial Dust Cyclone Separator: A Comparison with Empirical Models: The Influence of the Inlet Velocity and the Particle Size on Performance Factors in Situation of High Concentration of Particles

The present work is dedicated to the study of multiphase turbulent and three-dimensional rotational flow in dust cyclones, a contribution to air pollution control. Cyclones are widely used devices for the separation of constituents from solid-gas mixtures in industry. In order to improve the filtration efficiency of cyclones, and to reduce the pressure drop, parametric numerical simulation studies using the Fluent code have been conducted to characterise the effects of the parameters affecting the operation of these devices through their performance indicators. In this work, the effect of inlet velocity and the particle size on the turbulent flow air in the cyclone is presented. Numerical simulation of the flow by Fluent code using three numerical models: the first based on the dissipation of kinetic energy by viscosity (RNG) K-epsilon and standard K-epsilon as well as the last based on the solution of Reynolds stress equations (RSM), combined with the multiphase mixing model, gave interesting results in terms of the pressure and flow field in the separator, the variation of inlet velocity, and the variation of particle size. Validation with experimental and empirical results showed the advantage of the Reynolds stress turbulence model (RSM) over the standard K-epsilon and RNG K-epsilon. The RSM model better captures physical phenomena in an intense vortex flow in the presence of walls. But it is characterised by a very long calculation time and requires large machine resources. An alternative to this model is RNG K-epsilon model, which offers a reasonable calculation time with acceptable results (maximum deviation of 5 %) for speed values below 10 m/s. In the absence of numerical resources, certain empirical models such as those of First (for the evaluation of pressure drop) and Iozia and Leith (for evaluation of efficiency) may well be useful for the dimensioning of the cyclone.

Study on the flow and collision characteristics of catalyst particles in FCC reactor

Fluid Catalytic Cracking (FCC), a typical fluidization technology, faces serious issues of catalyst particle attrition and loss. Attrition is an important cause of catalyst loss. Due to the small particle size and complex flow process inside the reactor，it is difficult to conduct experimental research on it. The flow, collision and attrition characteristics of catalyst in the reactor are still unclear. This study established a geometric model of a catalytic cracking unit and used CFD-DEM bidirectional coupling numerical simulation method to study the flow and collision characteristics of catalyst particles in the catalytic cracking unit. The result indicate that particles collide with the wall most frequently， with an average collision frequency of 141,501.89 Hz. The particle wall collision frequencies above the nozzle, at the top of the riser, and in the cyclone separator are the highest, with an average collision frequency of 244.90 Hz, 1441.2 Hz, and 3571.15 Hz, respectively. Strong single collisions and slight continuous collisions of large size particles often occurred in the device. For small particles, the difference in strength between each collision within the device is not significant.

Solid-liquid distribution of SARS-CoV-2 in primary effluent of a wastewater treatment plant

Distributions of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and fecal viral biomarkers between solid and liquid phases of wastewater are largely unknown. Herein, distributions of SARS-CoV-2, Pepper Mild Mottle Virus (PMMoV), and F-RNA bacteriophage group II (FRNAPH-II) were determined by viral RNA RT-qPCR. Comparison of viral recovery using three conventional fractionation methods included membrane filtration, a combination of mid-speed centrifugation and membrane filtration, and high-speed centrifugation. SARS-CoV-2 partitioned to the solids fraction in greater abundance compared to liquid fractions in a combination of mid-speed centrifugation and membrane filtration and high-speed centrifugation, but not in membrane filtration method in a particular assay, while fecal biomarkers (PMMoV and FRNAPH-II) exhibited the reciprocal relationship. The wastewater fractionation method had minimal effects on the solids-liquids distribution for all viral and phage markers tested; however, viral RNA load was significantly greater in solid–liquid fractions viral RNA loads compared with the than whole-wastewater PEG precipitation. A RNeasy PowerWater Kit with PCR inhibitor removal resulted in greater viral RNA loads and lesser PCR inhibition compared to a QIAamp Viral RNA Mini Kit without PCR inhibitor removal. These results support the development of improved methods and interpretation of WBE of SARS-CoV-2.•Distribution of SARS-CoV-2 to liquid and solid portions was addressed.•Addressing PCR inhibition is important in wastewater-based epidemiology.•Fraction methods have minimal effect.