Vortex Flow Reactor Research Articles

Abatement of Volatile Organic Compounds (VOCs) and Fluorine gases by a Microwave Plasma Torch (MPT)

The use of microwave plasma torch (MPT) in the abatement of potent greenhouse and fluorinated (F-gases) gases is crucial due to their high global warming potential. The purpose of this study was the abatement of volatile organic compounds (VOCs) and carbon tetrafluoride (CF4) using specifically designed reverse vortex flow reactor (RVR) and pillar of fire reactor (POF). The RVR has properties that are crucial for their synergistic effects with the MPT, and the POF configurations showed high-efficiency combustion due to plasma radicals and a large contact area with the MPT. The study used Aspen Plus and COMSOL software to analyse the mass balance involved in the thermal decomposition of isopropyl alcohol (C₃H₈O) and CF4 and to design the RVR and POF reactors. Using MPT without hydrocarbon fuel, low-concentration C₃H₈O and CF4 were successfully destroyed in high-flow streams. The experiment on C₃H₈O showed that using a plasma power of 2kW and 1 cubic meter per minute (CMM) of bulk gas, a destruction removal efficiency (DRE) of 95% was achieved for a polluted C₃H₈O of 410 ppm. In a second experiment, a DRE of 94% was achieved for a polluted C₃H₈O of 370 ppm. The first CF4 experiment achieved a DRE of 93.3% with a 7kW plasma power and 1 CMM bulk gas polluted at 285 ppm. In the second experiment, the presence of highly reactive hydroxyl radicals (OH⁎) in steam plasma improved the DRE to 99.8% at 7kW plasma power and 100 LPM bulk polluted at 180 ppm.

Process Intensification of the Continuous Synthesis of Bio-Derived Monomers for Sustainable Coatings Using a Taylor Vortex Flow Reactor.

We describe the optimization and scale-up of two consecutive reaction steps in the synthesis of bio-derived alkoxybutenolide monomers that have been reported as potential replacements for acrylate-based coatings (Sci. Adv.2020, 6, eabe0026). These monomers are synthesized by (i) oxidation of furfural with photogenerated singlet oxygen followed by (ii) thermal condensation of the desired 5-hydroxyfuranone intermediate product with an alcohol, a step which until now has involved a lengthy batch reaction. The two steps have been successfully telescoped into a single kilogram-scale process without any need to isolate the 5-hydroxyfuranone between the steps. Our process development involved FTIR reaction monitoring, FTIR data analysis via 2D visualization, and two different photoreactors: (i) a semicontinuous photoreactor based on a modified rotary evaporator, where FTIR and 2D correlation spectroscopy (2D-COS) revealed the loss of the methyl formate coproduct, and (ii) our fully continuous Taylor Vortex photoreactor, which enhanced the mass transfer and permitted the use of near-stoichiometric equivalents of O2. The use of in-line FTIR monitoring and modeling greatly accelerated process optimization in the Vortex reactor. This led to scale-up of the photo-oxidation in 85% yield with a projected productivity of 1.3 kg day-1 and a space-time yield of 0.06 mol day-1 mL-1. Higher productivities could be achieved while sacrificing yield (e.g., 4 kg day-1 at 40% yield). The use of superheated methanol at 200 °C in a pressurized thermal flow reactor accelerated the second step, the thermal condensation of 5-hydroxyfuranone, from a 20 h batch reflux reaction (0.5 L, 85 g) to a space time of <1 min in a reactor only 3 mL in volume operating with projected productivities of >700 g day-1. Proof of concept for telescoping the two steps was established with an overall two-step yield of 67%, producing a process with a projected productivity of 1.1 kg day-1 for the methoxybutenolide monomer without any purification of the 5-hydroxyfuranone intermediate.

Turbulence-assisted shear controllable synthesis of silicon oxide micro/nano particles using a counter axial-swirling impinging jet flow reactor

It has been recognised that turbulence shear can be used to effectively control and affect the synthesis of micro/nano particles. The present study focuses on turbulence-assisted shear controllable synthesis of silica (SiO2) micro/nano particles and investigates such shear controllable synthesis process using a counter axial-swirling impinging jet flow vortex flow reactor. Two counter swirling flow streams impinge in the reaction chamber to significantly intensify the local turbulence shear with the aid of ultrasound irradiation. The consequence of the turbulent shear leads to either the trapping of nano-particle nucleus into the turbulent eddies to form the aggregated micro/nana particles or the confinement of the growth of agglomerated micro/nano particles so as to form highly uniform and better morphological micro/nano particles. The experimental results have affirmed the postulation that the local turbulent shear generated by the turbulent eddies with the length scales down to the Kolmogorov length scale may directly interact with the aggregated SiO2 micro/nano particles, influencing the particle spherical morphology and size distribution. In addition, it has been found that synthesis performance can be further improved by intensifying the local turbulent shear through the ultrasound irradiation in the synthesis process. Both CFD simulation and experimental results clearly indicate the existence of the correlation in the synthesized SiO2 micro/nano particle characteristics with the local turbulence shear and mass transfer occurring in counter swirl impinge jet flow.

A hydroesterification reaction system to produce octyl esters using degummed soybean oil as substrate: Combining reusable free and immobilized lipases

This study shows the enzymatic synthesis of octyl alcohol-based biolubricants carried out in two catalytic steps: degummed soybean oil (DSO) hydrolysis and esterification of the produced and purified free fatty acids (FFA). Several lipases were evaluated as catalysts in the hydrolysis of DSO. Under optimal conditions, lipase from Pseudomonas fluorescens (PFL) yielded 97 % conversion after 23 h using 50 U/g oil and DSO:water mass ratio of 1:0.5. Sequential batch strategies have been developed for the recovery and reuse of free enzyme in further hydrolysis cycles. When hexane was used in the separation between the FFA-rich phase and the phase composed of water, enzyme and glycerol, there was better PFL recovery and FFA-conversion of 65 % was still achieved after five 24-hour hydrolytic cycles. In the esterification step, the potential of four lipases (commercial Lipozym-435, and lipase B from Candida antarctica (CALB), lipase from porcine pancreas (PPL) and Eversa® Transform 2.0 (EV) immobilized on Purolite Lifetech EC8806F) were evaluated in the production of octyl esters in a solvent-free medium (FFA/octanol molar ratio of 1:2.5) using screw-capped glass bottles as reactor. The immobilized EV gave the best ester yield (∼87 wt%). When EV-Purolite was used in a vortex flow reactor, a yield of around 94 wt% was reached after 3 h of reaction using a biocatalyst load of 1 % (w/v) and FFA/octanol molar ratio of 1:2.5. The immobilized lipase could be reused for five consecutive 3 h-batches of esterification, maintaining the octyl esters yield of the first batch.

Synthesis of Monodisperse Silica Nanospheres and Titania Beads from Rotating Cylinder System

Economic raw materials such as low-grade ethanol and Tetraethyl Ortosilicate (TEOS) were adopted as reactants for the synthesis of monodisperse silica nanospheres using a Taylor Vortex flow reactor with a rotating cylinder system. Factors affecting the mean diameter and size distribution of the silica grains were investigated by changing the rotating speed of the inner cylinder and the composition of reactants. In the case of titania beads, grain diameter size was adjusted by changing the amount of precursor (titanium (IV) isopropoxide, TIP), hexadecylamine (HDA) or Potassium Chloride (KCl) and reaction temperature as well as the rotation speed of the cylinder. As a demonstrative application, titania beads could be used for the removal of organic dye as a model contaminant dissolved in an aqueous medium using a photocatalytic decomposition system.

Application of Taylor Vortex Flow Reactor Enabling Precise Control of Nucleation in Reactive Crystallization

Application of Taylor Vortex Flow Reactor Enabling Precise Control of Nucleation in Reactive Crystallization

Reactive mixing performance for a nanoparticle precipitation in a swirling vortex flow reactor

Mixing performance for a consecutive competing reaction system has been investigated in a swirling vortex flow reactor (SVFR). The direct quadrature method of moments combined with the interaction by exchange with the mean (DQMOM-IEM) method was employed to model such reacting flows. This type of reactors is able to generate a strong swirling flow with a great shear gradient in the radial direction. Firstly, mixing at both macroscale and microscale was assessed by mean mixture fraction and its variance, respectively. It is found that macromixing can be rapidly achieved throughout the whole reactor chamber due to its swirling feature. However, micromixing estimated by Bachelor length scale is sensitive to turbulence. Moreover, the additional introduction of ultrasound irradiation can significantly improve the mixing uniformity, namely, free of any stagnant zone presented in the reactor chamber on a macroscale, and little variance deviating from the mean environment value can be observed on a microscale. Secondly, reaction progress variable and the reactant conversion serve as indicators for the occurrence of side reaction. It is found that strong turbulence and a relatively fast micromixing process compared to chemical reaction can greatly reduce the presence of by-product, which will then provide homogenous environment for particle precipitation. Moreover, due to the generation of cavitation bubbles and their subsequent collapse, ultrasound irradiation can further intensify turbulence, creating rather even environment for chemical reactions. Low conversion rate was observed and little by-products were generated consequently. Therefore, it is suggested that the SVFR especially intensified by ultrasound irradiation has the ability to provide efficient mixing performance for the fine-particle synthesis process.

Vortex flow reactor assessment for the purification of monoclonal antibodies from unclarified broths

The vortex flow reactor (VFR) can be used in many chemical engineering applications. This paper assesses its novel use in the purification of monoclonal antibodies from cell broth. To this end, the IgG2a antibody was purified from the unclarified fermentation broth of transgenic mouse 55/6 hybridoma cells. Visual experiments showed that the VFR worked in the laminar vortices flow regime and the vortices displaced slightly faster than the axial flow. The VFR has the advantage of creating two sorts of flows: axial flow to produce the expanded bed and an extra vortex flow to avoid channeling and stabilize the expanded bed, the hydrodynamic behavior of which is plug flow with an experimental Pèclet number higher than 20. The pH was adjusted in the untreated fermentation broth, which was directly introduced into the reactor thus reducing the number of stages. The IgG2a purification was carried out in a single device via two steps: antibody adsorption in the expanded bed and antibody elution in the settled bed using Streamline rProtein A. A thirty-fold increase in the high-purity antibody concentration was achieved at the top of the pH5 elution peak with a total recovery of 93.1% (w/w) between elution peaks pH 5 and 3.

Development of a Liquid‐Liquid Biphasic Reaction Using a Taylor Vortex Flow Reactor

AbstractThis paper describes a liquid‐liquid biphasic flow reaction system that is simple to control. In a liquid‐liquid biphasic flow reaction, the slug‐flow in the tube reactors generally improves the reaction rate. However, we show that larger tube diameters decreased the reaction rate and the formation of the slug‐flow was influenced by the tube diameter, the size of the mixer, and the pump mechanism. These results indicated that technical difficulties with the slug‐flow could be an obstacle to scale‐up. To resolve this problem, we suggest the use of a Taylor vortex flow reactor to achieve a higher reaction rate than with batch and slug‐flow systems.

Using a Couette–Taylor vortex flow reactor to prepare a uniform and highly stable Li[Ni0·80Co0·15Al0.05]O2 cathode material

This study mainly focuses on the preparation technique of Ni-rich NCA hydroxide by a Couette–Taylor flow reactor (CTFR), by systematically optimizing the preparation parameters, including cylinder rotation speed and calcination temperature to study its electrochemical performance. Because of the uniform mixing and constant fluid motion of the Taylor vortex, we obtained spherical and uniform Ni0·80Co0·15Al0·05(OH)2 particles. The rotation speed of the inner cylinder determined the degrees of particle agglomeration and growth. X-ray diffraction and Rietveld refinement revealed that the sample prepared at 600 rpm had relatively large particles and a high degree of crystallinity; when calcined to 750 °C, it featured much smaller primary particles, a comparatively lower degree of cation mixing, and better layer structure ordering. The Ni-rich LiNi0·80Co0·15Al0·05O2 prepared under the optimal conditions delivered a high discharge capacity of 190.6 mAh g−1 at 0.1C, on par with that of commercially available NCA powders; it also exhibited a remarkable improvement in rate capability, with a discharge capacity of 138 mAh g−1 at 10C (101 mAh g−1 for a commercial sample). In long cycle life tests, the prepared NCA sample retained a high capacity (87.4%) after 100 cycles at 1C, compared with 70.0% for the commercial sample. Furthermore, cyclic voltammetry and electrochemical impedance spectroscopy demonstrated the importance of the calcination temperature on the electrochemical performance and structural stability of our Ni-rich cathodes. Our as-prepared NCA cathode materials, obtained using a CTFR, appear to have great potential for application in Li-ion batteries.

Shear turbulence controllable synthesis of aggregated nano-particles using a swirling vortex flow reactor assisted by ultrasound irradiation

The mass transfer in the shear controllable synthesis process of nano-sized particles using a swirling vortex flow reactor is investigated. This type of a reactor is able to generate a strong ‘Rankine vortex-like’ flow with a great shear gradient in the radial direction, trapping the synthesised aggregated nano-particles into the vortex core to form aggregation. The aggregated particles are further agglomerated to form larger particles with high uniformity under the action of turbulent shear and subsequent mass transfer due to engulfment occurred in the turbulent eddies. The mass transfer is enhanced by engulfment between the slabs of the liquid streams tangentially entering into the reactor while the local shear in the turbulent eddies with the length scales down to the Kolmogorov scale shape the particles, yielding well spherical morphology and narrower size distribution. In addition, the mass transfer performance can be further improved by intensifying the local turbulent shear by applying the ultrasound to the synthesis process. The instantaneous collapse of cavitation bubbles in the vortex due to the introduction of ultrasound results in intensified micro-turbulent streaming. The particle characteristics, chemical reaction and mass transfer performance are found to be correlated with the local turbulence characteristics in the vortex. The mass transfer can be characterised using the film refresh model via the Sherwood number by considering the agglomerated particles response to the turbulent eddies. Both numerical simulation and experimental results clearly indicate the existence of the correlation in synthesis of aggregated nano-particles in swirling vortex reactor between the mass transfer and turbulence shear by using ultrasound irradiation.

Study on optimization of actinide oxalate precipitation process in a vortex flow reactor

ABSTRACTOxalate precipitation process is globally accepted and is the current choice for conversion of actinide nitrates to their oxides. A vortex flow reactor with magnetic stirrer is found to be a better option for a hassle-free operation of batch as well continuous actinide reconversion process. Utilization of magnetic stirrer as an alternate for the conventional mechanical stirrer eliminates corrosion-related issues as none of the metal parts are in contact with nitric acid as well as oxalic acid solution. Moreover, this alternative system ensures a maintenance-free process. Optimization of various process conditions in a vortex reactor was accomplished using cerium nitrate as a surrogate for actinide nitrate and the results obtained were compared with that of pitched blade mechanical stirrer. About 40 L of thorium nitrate solution was successfully precipitated by the optimized procedure in a vortex reactor.

A novel vortex flow reactor for the purification of B-phycoerythrin from Porphyridium cruentum

The purification of B-phycoerythrin from a concentrated extract of disrupted Porphyridium cruentum cells was carried out using a new vortex flow reactor design for protein purification. The reactor behaved as an expanded bed in the laminar vortices flow regime where the Streamline DEAE resin was expanded by the axial flow and stabilized by the vortex flow. After the broth culture was centrifuged and resuspended in the adsorption buffer, the concentrated extract of disrupted cells was directly loaded into the vortex flow reactor. The purification of B-phycoerythrin was carried out in two steps: adsorption in the expanded bed and elution from the settled bed. 142.0mg of B-phycoerythrin was eluted representing a total recovery yield of 86.6%. Prior to B-phycoerythrin purification, the protein adsorption of the vortex flow reactor was characterized through hydrodynamic studies and a dynamic capacity measurement using a standard protein.

Chemical patterns in translating vortices: Inter- and intra-cellular mixing effects

Stationary chemical patterns-flow distributed oscillations (FDOs)-are obtained when the Belousov-Zhabotinsky reaction is coupled with translating vortex flow in a Vortex Flow Reactor. For certain conditions, the FDOs are unstable with the observation of disappearing bands or complex patterns. The transitions between modes of pattern formation are reproduced in a modified Oregonator model consisting of two-zone cells connected in series. We show that increasing inter-cellular mixing of the outer zones results in a transition from FDO to absolute instabilities (AI) and increasing intra-cellular mixing between the core and outer zones can drive the reverse transition between modes (AI to FDO).

Optimization geometries of a vortex gliding-arc reactor for partial oxidation of methane

The effects of the geometry of gliding-arc reactor – such as distance between the electrodes, outlet diameter, and inlet position – on the reactor characteristics (methane conversion, hydrogen yield, and energy efficiency) have not been fully investigated. In this paper, AC gliding-arc reactors including the vortex flow configuration are designed to produce hydrogen from the methane by partial oxidation. The influence of vortex flow configuration on the reactor characteristics is also studied by varying the inlet position. When the inlet of the gliding-arc reactor is positioned close to the outlet, reverse vortex flow reactor (RVFR), the maximum energy efficiency reaches 50% and the yields of hydrogen and carbon monoxide are 40% and 65%, respectively. As the distance between electrodes increases from 5 mm to 15 mm, both hydrogen yield and energy efficiency increase approximately 10% for the RVFR. The energy efficiency and hydrogen yield are highest when the ratio of the outlet diameter to the inner diameter is 0.5 for the RVFR. Experimental results indicate that the flow field in the plasma reactor has an important influence on the reactor performance. Furthermore, hydrogen production increases as the number of feed gas flows in contact with the plasma zone increases.

Characterising stationary and translating vortex flow using magnetic resonance

We report magnetic resonance (MR) velocity and diffusion maps in three directions for stationary vortices (Taylor vortex flow —TVF) and velocity maps for translating vortices (vortex flow reactor —VFR) produced in a Couette cell. Motion artefacts in the translating vortex flow are removed by synchronising data acquisition with the translation period of the vortices. MR propagator experiments, which measure the conditional probability density for displacement, were performed to characterise molecular displacements in these systems. Simulations were performed using the experimental velocity and diffusion maps to aid interpretation of experimentally measured propagators and enable characterisation of the macro-mixing and transport properties within TVF and VFR systems. These simulations enabled molecular transport and mixing to be assessed over longer-time scales than are accessible experimentally, allowing plug flow, by-pass flow and inter-vortex mixing to be quantified.

Response to the comments made by Khalid M. Saqr on our paper titled “CFD analysis on the influence of helical carving in a vortex flow solar reactor”, Int. J. Hydrogen Energ. 2010: 35, 6248–6260.

In our paper titled “CFD analysis on the influence of helical carving in a vortex flow solar reactor”, we have presented a 3D CFD analysis of a turbulent and reactive flow for directly irradiated solar thermochemical reactor to characterize the influence of flow behavior on the heat transfer and solar cracking process. The heat transfer by radiation from carbon particles is considered by providing global absorption and scattering coefficients in the computational domain obtained from Mie code. The flow field is based on RNG k-3 model derived using renormalization group theory. We have validated our numerical procedure by comparing the outlet temperature and cavity temperaturemeasurements of Hirsch and Steinfeld (Solar hydrogen production by thermal decomposition of natural gas using a vortex-flow reactor. Int J Hydrogen Energy 2004; 29:47-55) for Run 1 Configuration 1. As it is seen in our paper, our numerical simulations predict the mixture (gas-particle) flowoutlet and cavitywall temperatures as 1240K and 1751.3K,which deviates from the experimentally

Dispersion of Floating Particles in a Taylor Vortex Flow Reactor

The present study investigated the dispersion of floating particles in a Taylor vortex flow reactor experimentally and numerically. The working fluid was glycerin solution and had a density (ρf) of 1210 kg·m-3 and a viscosity (μ) of 0.1 Pa·s. Floating particles of an acrylic resin had a density (ρp) of 1190 kg·m-3.Two groups of particles with mean diameters of 710 and 974μm were discerned. Although particles penetrated the Taylor vortex flow region in the axial direction at different rotational Reynolds numbers, particle segregation was observed. It was confirmed that the smaller particles penetrated deeper in the axial direction. Numerical simulations were also conducted to elucidate the mechanism of particle segregation. Numerical results of a particle-tracking method indicate that the small particles moved on the outermost orbit of a torus. Results of a distinct element method suggest that interparticle collision affected particle transference between vortices.

Studies on protein adsorption in a vortex flow reactor

The performance of a vortex flow reactor (VFR) with suspended particles for protein adsorption was studied under varying operating conditions, and resin volume fractions. The VFR behaved as an expanded bed in the regimen of laminar vortices flow. Streamline DEAE was used for bovine serum albumin (BSA) adsorption. Expanded bed VFR experiments were performed with varying geometric aspect ratios (14.6, 28.6 and 40.0) and axial superficial velocity (100–300 cm h −1) to investigate their influence on productivity and dynamic capacity. The results are compared with literature data on an expanded bed column (EBC). Adsorption breakthrough curves were fitting to a simple two-parameter model.

Enzymatic tailor‐made proteolysis of whey in a vortex flow reactor

AbstractEnzymatic hydrolysis of cheese whey proteins with immobilized enzymes, providing a tailor‐made pool of peptides, within narrow ranges of molecular weight, might be an advantageous alternative for this by‐product of the dairy industry. In this work, Alcalase® was immobilized in agarose–glyoxyl gel beads and the proteolysis reaction was run in a continuous Taylor–Couette–Poiseuille reactor [or vortex flow reactor (VFR)], which presented efficient stirring without damaging the fragile beads. VFR mass transfer parameters were estimated after residence time distribution assays. Artificial neural networks were used to predict reaction rates of five ranges of peptide molecular weights. Using this hybrid model, a detailed description of the system was achieved. A bench‐scale VFR (radius ratio η = 0.48 and aspect ratio Γ = 11.9) was used to validate the model. © 2004 American Institute of Chemical Engineers AIChE J, 21: 314–322, 2005