Volume Of Mixer Research Articles

Numerical Simulation of Static Ammonia Mixer in Denox Unit of Flue Gas Purification Plant

The modeling of a mixer used for mixing ammonia and flue gasses is considered. Simulations were performed using Flow Vision 3.14 (TESIS LLC). As a result of the simulation, the distribution of concentrations along the mixer length was obtained at 50%, 65%, 85%, and full flue gas loading. It was found that operations at 100% and 85% gas loads are accompanied by an acceptable distribution of ammonia in the mixer volume (Cov = 0.05). The development and creation of an experimental model in real production was carried out according to the results of the numerical simulation. The simulation results were compared with experimental data on the speed and concentration of ammonia in the control section. The discrepancy, in general, did not exceed 15%. The developed mixer corresponds to modern developments in terms of mixing quality but is simpler in design and more compact.

PRODUCTION OF COMPOUND FEEDS IN THE CONDITIONS OF FARMS WITH LOADED RESERVATION OF DOSING AND MIXING

Two options for resource-saving technology of mechanized production of compound feeds and PVMS with flexible connections were developed and implemented in farm conditions with loaded backup of Tweighing batchers and mixers and with loaded backup of mixers. The studies have established that the dosing accuracy of 0.1 kg., the mixer shaft revolutions have an impact on the mixing quality indicator, so at 30 rpm. mixing quality is 95.18%, and at 46 rpm. – 96.1% and 1 min of mixing. Based on a multifactor experiment, polynomial linear and quadratic models were obtained for the mixing quality of compound feed ingredients due to the factors: rotation speed, number of blades and operating time with a mixer volume of 0.54 m3. The time spent on performing operations for the production of compound feed was determined and two versions of the cycle diagrams of the process of compound feed production of technological lines were constructed: with loaded redundancy of weighing batchers and mixers and with loaded redundancy of mixers. The time of the initial cycle of the process of compound feed production of technological lines was established: – with the redundancy of weighing batchers and mixers, the time of the initial cycle was 9.7 min. and the established cycle was 6.9 min. – with the redundancy of mixers, the time of the initial cycle of the process of compound feed production of technological lines with a capacity of 2 tons per hour was 9.7 min. and the established cycle was 5.9 min. It was established that the productivity of technological lines for the production of compound feed was: – using technology with flexible connections and loaded redundancy of two weighing batchers and two mixers – 1.974 t. – using technology with flexible connections and a weighing dispenser, which provides unloading of raw material components in two opposite directions and loaded redundancy of two mixers – 2.307 t.

Full-cycle study on developing a novel structured micromixer and evaluating the nanoparticle products as mRNA delivery carriers

Achieving precise control of nanoparticle size while maintaining consistency and high uniformity is of paramount importance for improving the efficacy of nanoparticle-based therapies and minimizing potential side effects. Although microfluidic technologies are widely used for reliable nanoparticle synthesis, they face challenges in meeting critical homogeneity requirements, mainly due to imperfect mixing efficiency. Furthermore, channel clogging during continuous operation presents a significant obstacle in terms of quality control, as it progressively impedes the mixing behavior necessary for consistent nanoparticle production for therapeutic delivery and complicates the scaling-up process. This study entailed the development of a 3D-printed novel micromixer embedded with hemispherical baffle microstructures, a dual vortex mixer (DVM), which integrates Dean vortices to generate two symmetrical counter-rotating intensified secondary flows. The DVM with a relatively large mixer volume showed rapid mixing characteristics even at a flow rate of several mL min−1 and produced highly uniform lipids, liposomes, and polymer nanoparticles in a size range (50–130 nm) and polydispersity index (PDI) values below 0.15. For the evaluation of products, SARS-CoV-2 Spike mRNA-loaded lipid nanoparticles were examined to verify protein expression in vitro and in vivo using firefly luciferase (FLuc) mRNA. This showed that the performance of the system is comparable to that of a commercial toroidal mixer. Moreover, the vigorous in-situ dispersion of nanoparticles by harnessing the power of vortex physically minimizes the occurrence of aggregation, ensuring consistent production performance without internal clogging of a half-day operation and facilitating quality control of the nanoparticles at desired scales.

Mass transfer and hydrodynamic studies in a 100 μm diameter microfluidic channel in a rotated helical configuration

A simple 3D rotated microfluidic mixer design is reported with evaluation of hydrodynamic and mass transfer performance. Proposed device had a minimalistic configuration of 3 turns, rotated in x, y, and z planes. The helical mixer volume was only 3.14 μL due to usage of 100 μm dia micro bore tubing. The proposed device was different from conventional CFI and its variants. The analysis for hydrodynamic performance indicated a massive specific interfacial area, much more than for the 50 mm centrifugal extractor with the same PUREX aqueous-organic pair. Higher volumetric amass transfer coefficients were reported for the proposed device as compared to conventional mixers (impellers and Taylor-Couette mixers). Energy dissipation values were also reported to be much higher than that of a contemporary annular centrifugal extractor. Mixing-time values (tm) were estimated at least two-order lower than residence time values (τ). Proposed design complied all the four directives of the concurrent PI paradigm.

A Flexible Kenics Mixer for Applications in Liquid Chromatography.

Miniaturization of liquid chromatography could help enhance sensitivity, reduce solvent usage, and detect small quantities of peptides. However, it demands better sample homogenization of the mobile phase. We here developed a mixer design based on the inline Kenics geometry, consisting of a periodic arrangement of twisted blades placed inside a cylindrical capillary that repeatedly cut and stack fluid elements to achieve rapid mixing in laminar flow regimes. The mixer design was optimized with respect to the twist angle and aspect ratio of the mixing units to achieve complete mixing at minimum pressure load cost. Results suggest that for optimal designs, for a mixer volume of ~70 μL, complete mixing is achieved within a distance smaller than 4 cm for a broad set of flow rate conditions ranging from 75 μL·min-1 to 7.5 mL·min-1. A salient feature that we introduce and test for the first time is the physical flexibility of the cylindrical capillary. The performance of the design remained robust when the mixing section was not rigid and bent in different topologies, as well as when changing the chemical composition of the mobile phase used.

Theoretical framework for mixer design for noise reduction and gradient fidelity

The mixing of two or more solvent streams to deliver a stable and accurate solvent composition is crucial to the performance, repeatability and reproducibility of a liquid chromatographic separation. We provide a theoretical treatment of axial mixing of a sequence of solvent packets with the framework of continuous stirred tank reactors (CSTRs) in series and investigate the tradeoffs presented between the primary goal of mixers (noise reduction) and it's necessary side-effects of gradient deformation and asymmetry. An experimental setup to mimic CSTR conditions was created using a stop-flow setup where the fluid flow was periodically paused and sonicated within pods of a certain volume. The effects of mixer volume relative to the volume of pump strokes and gradient volumes were investigated and discussed.A total mixer volume that is six-fold the pump stroke volume was found to be necessary to achieve sufficient (95%) noise reduction necessary for certain applications. A series of two or more CSTR elements was found to outperform a single CSTR element for larger mixer-to-pump stroke volume ratio in dampening baseline noise. For linear gradients, a gradient volume that is ten times larger than the mixer volume was found to sufficiently maintain gradient fidelity. For very small gradient volumes relative to the mixer volume, deformation of linear gradients was found to be significantly greater than predicted by the analytical solution. Furthermore, the nature of the solvent gradient deformation was asymmetric, with the latter half of the solvent gradient deforming significantly more than the first half.Combining analytically and numerically derived solutions for multiple CSTRs connected in series with experimental data, several suggestions can be made on mixer dimensions and design for a certain pump system and method transfer, given a pump stroke volume and gradient time.

Влияние характера движения потоков смеси в объеме смесителя на однородность приготавливаемой смеси

An analysis of turbulent transport patterns in mixers revealed specific features of the flow hydrodynamics of the mixed medium with regard to mixers either without internal devices or with internal devices of small cross-section. Despite the increasing popularity of mixers without internal devices, experimental studies were carried out mainly in mixers with baffles, since they provide a higher turbulence of the mixing process allowing effective preparation of foam concrete mixtures with evenly distributed components throughout the mixer volume. Experimental studies of the dependence of peripheral velocity on the characteristics of the internal devices of the mixer in the preparation of foam concrete mixtures showed a high degree of agreement between the experimental and calculated data. Calculations based on the equations provided in the article and measurement results indicate that, when fixed elements are attached to the mixer, the circumferential velocity is significantly reduced. It should be noted that the fixed devices installed in a mixer are affected by hydrodynamic forces. The results of the conducted experiments and comparisons demonstrated that, when preparing a foam concrete mixture in a turbulent mixer without internal reflective baffles, the effect of a cylindrical surface with a turbulent diffusion ratio equal to zero makes it impossible to evenly distribute the mixture components throughout the volume and pore the mortar mixture.

Optimization of Mixing Conditions on the Physical and Tribological Properties of Brake Pads

This study investigates the effects of mixing condition on hardness, porosity, specific gravity, wear, and friction characteristics of automotive brake materials. In the experiment, mixing raw materials with three different conditions of impeller speed (3000, 4500, and 6000 rpm), mixing duration (up to 8 min) and mixture loading based on a mixer volume (35, 50 and 65 vol% ) were determined using the formulated mixture composition. Homogeneity in terms of density values including hardness, porosity, and specific gravity of the finished brake pads were determined. The surfaces and the distribution of friction material were studied using scanning electron microscopy (SEM). The correlation between various mixing conditions and physical and tribological properties of brake pads were discussed and reported.

АНАЛИТИЧЕСКОЕ ОПИСАНИЕ ПОКАЗАТЕЛЕЙ РАБОТЫ СМЕСИТЕЛЯ СЫПУЧИХ МАТЕРИАЛОВ С ВИНТОВЫМИ ЛОПАСТЯМИ

The aim of the study is to reduce the energy consumption of the blade mixer for bulk materials in regard to its de-sign parameters. Preparation of feed mixtures is carried out mainly by mixers of various designs, as well as extrud-ers and other auger equipment. Widespread horizontal mixers with blades mounted on a rotating shaft are wide-spread and used. They are distinguished by the ability to achieve the necessary smooth mixture within short oper-ating time. The main purpose of the proposed mixer is the preparation of dry mixtures of bulk feed components. The intended use of the mixer is the preparation of concentrated animal feed n agricultural production. In Samara SAA, the design of the blade mixer with screw blades was developed based on the literature review and analysis of the technological process of mixers. The mixer consists of a body with a horizontal shaft with radial trapezoidal screw blades. The proposed blades allow to direct forces in such a way that the total (resulting) projection of the resistant force of the material along the shaft will tend to zero due to the changing angle of the profile and width of the blades. At the same time, an axial force will be created at the edge of the blade at a certain radius, which facili-tates to unload mixer through the discharge opening. The expressions of specific energy consumption for mixing, as well as the work duration of the mixer cycle are given. An expression allowing estimation of an average flow rate of bulk material from the discharge opening of the mixer is obtained. It is established that the position of the gate regulating the area of the discharge opening can affect the volume of the portion simultaneously processed by the mixer, filling volume of mixer and the quality of the mixture.

Pre-column dilution large volume injection ultra-high performance liquid chromatography-tandem mass spectrometry for the analysis of multi-class pesticides in cabbages

Pre-column dilution large volume injection (PD-LVI), a novel sample injection technique for reverse phase ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC–MS/MS), was developed in this study. The PD-LVI UHPLC–MS/MS system was designed by slightly modifying the commercial UHPLC–MS/MS equipment with a mixer chamber. During the procedure of PD-LVI, sample solution of 200μL was directly carried by the organic mobile phase to the mixer and diluted with the aqueous mobile phase. After the mixture was introduced to the UHPLC column in a mobile phase of acetonitrile-water (15/85, v/v), the target analytes were stacked on the head of the column until following separation. Using QuEChERS extraction, no additional steps such as solvent evaporation or residue redissolution were needed before injection. The features of PD-LVI UHPLC–MS/MS system were systematically investigated, including the injection volume, the mixer volume, the precondition time and the gradient elution. The efficiency of this approach was demonstrated by direct analysis of 24 pesticides in cabbages. Under the optimized conditions, low limits of detection (0.00074–0.8ng/kg) were obtained. The recoveries were in the range of 63.3–109% with relative standard deviations less than 8.1%. Compared with common UHPLC–MS/MS technique, PD-LVI UHPLC–MS/MS showed significant advantages such as excellent sensitivity and reliability. The mechanism of PD-LVI was demonstrated to be based on the column-head stacking effect with pre-column dilution. Based on the results, PD-LVI as a simple and effective sample injection technique of reverse phase UHPLC–MS/MS for the analysis of trace analytes in complex samples showed a great promising prospect.

Modeling and Practice of Ethanol-devolatilization of Silica-silane Rubber Compoundsin an Internal Mixer

Abstract During mixing of a rubber compound containing silica and silane, the mixer is not only used for the dispersion of the filler and other ingredients, but also for a chemical reaction. These two functionalities of the mixer result in opposite processing requirements: A good dispersion is reached by high shearing forces, increasing the compound temperature. The silanization is not dependent on high shearing forces; it is positively influenced by high temperatures, but with an increasing risk of scorch. Another drawback is the equilibrium between the ethanol concentration in the vapor phase in the void space of the mixing chamber and in the rubber phase, which is limiting the reaction rate of the silanization. Devolatilization of the compound is a crucial factor for the efficiency of the silanization reaction. In this article a model for devolatilization of a rubber compound in an internal mixer is developed, including a chemical reaction replenishing the volatile component during the devolatilization process. The model is based on the penetration theory, with the main contribution to the devolatilization being convective mass transfer. The main influencing factors, theoretically deducted and practically verified, are temperature, mixer volume, fill factor, rotor speed, reaction time and partial pressure of the volatile component in the void volume of the mixer.

QUANTIFICATION OF SOLID-LIQUID MIXING USING ELECTRICAL RESISTANCE AND POSITRON EMISSION TOMOGRAPHY

Tomographic measurement techniques offer new opportunities and challenges for quantifying the degree of mixing of particulate suspensions and other multiphase mixtures. This has implications for the design, operation and control of industrial mixers and batch reactors, including crystallizers. Various statistical methods for describing mixing phenomena are reviewed and selected methods are applied to electrical resistance and positron emission data. New and more robust methods of image reconstruction and interpretation are reported for electrical tomography based on discretizing the mixer volume into a small number of regions or cells. Realistic models can be proposed and reconstruction can then be performed by modification of existing (Newton- Raphson) methods or, if these become too complex, by the application of the Metropolis algorithm or Markov chain Monte Carlo methods. Reducing the number of parameters of the associated model can remove ambiguity and allow rapid reconstruction. Improvements to instrumentation hardware and the mounting of electrical resistance sensors on the impeller shaft greatly assists the analysis of regions of interest (such as the vicinity of down-comers). The resulting linked design and analysis of the entire measurement system with a Bayesian parametric-reconstruction approach is a significant advance in tomographic technology.

The effect of V-mixer scale-up on the mixing of magnesium stearate with direct compression microcrystalline cellulose

The effect of V-mixer size on the mixing of magnesium stearate with directly compressible microcrystalline cellulose is reported. The mixers used were geometrically similar with a seven-fold difference in the volumes of the smallest (320 cm 3) and biggest mixer (2250 cm 3). To evaluate the mixing process and compare the performance of the mixers, the extent of the decrease in tablet crushing strength was measured. The kinetics of the decrease in crushing strength were best described by the sum of two separate processes, one first-order and the other second-order. Overall, the faster second-order process dominated mixing because the first-order rate decreased, while the second-order rate increased, with an increase in mixer volume. Results show that the limiting crushing strength increased with an increase in mixer size and that there was a linear relationship between the limiting crushing strength and the logarithm of the volume of the mixer. A decrease in mixer load from 33 to 18% also led to an decrease in tablet strength. The results can be used to scale-up the lubricant mixing process in V-mixers.

Simulation of Flow in an Intermeshing Internal Mixer and Comparison of Rotor Designs

Abstract This paper describes a simulation of flow in various intermeshing rotor internal mixer designs. The rotor designs studied were obtained from the patent literature and presentations of the major intermeshing rotor machinery mixer manufactures. The results of the simulation are compared to those for rotors of commercial separated rotor mixers. We seek to compare intermeshing and separated rotor mixers by contrasting estimated rates of mixing per unit total mixing chamber volume. Intermeshing rotors are generally predicted to perform better. This indicates they will mix more material despite smaller available internal mixer volume.

Effect of a mixer on the course of gradient elution and methods for its elimination

The effect of a mixer in the gradient elution device on the variations in the concentration of eluents has been studied. The functions that characterize real concentration changes have been derived and compared with those describing programmed changes in concentration. On this basis the magnitudes of errors have been determined as a function of the mixer volume and the flow-rate. A method has been developed that permits one to correct the functions programming the operations of gradient elution devices containing mixers in such a manner as actually to obtain eluents of programmed composition. The correctness of the derived relationships has been verified experimentally.

Distribution of residence time of material being processed over the zones in type SN reactor-mixers

Previous equations given for calculating the mean residence time of material being processed in the mixing chamber of continuous reactor-mixers show the effect on residence time of the capacity and mean reactor-mixer filling factor, the filling factor of the worm conveyor, and the mixer volume. It is necessary to take into account that such reactors operate only with ''starvation'' of the feed zone with charge. In this case the injected composition of the initial components is not disturbed. The filling factor in the zones of the guard coils of the conveyor worm becomes equal to unity over the length of the worm equal to double the length of the guard coil zones with different pitches of the guard and conveying coils. Consequently, the time of residence is not distributed uniformly over the length of the mixer but in proportion to the number of zones and the number of guard coils in the zones which are characteristic also for the mean filling factor. Experiments have been conducted in a type SN-100 reactor-mixer with an open body. After stopping the unit the upper half of the casing was opened without destroying the distribution of the material over the zones and turns ofmore » the worm. The material was removed from each zone, and the quantities were used to calculate the filling fatrors. The experimental filling factors were used to calculate the residence times of the material in the zones, the distribution of the times over the zones, and the mean residence time of the material in the mixer. The results obtained differed by not more than 5% from calculated values.« less