Showing papers in "Chemical Engineering & Technology in 2008"

Succinic Acid: A New Platform Chemical for Biobased Polymers from Renewable Resources

Abstract: Succinic acid is predicted to be one of the future platform chemicals that can be derived from renewable resources. The improvements in biotechnological succinic acid production are presented. Chemical conversion pathways to γ-butyrolactone, tetrahydrofuran, 1,4-butanediole, and pyrrolidones are reviewed. An overview of possible new biopolymers (e. g. polyesters, polyamides, and poly(ester amide)s) based on succinic acid and its derivatives is given. Nevertheless, industrial processes using purified succinic acid from fermentation broths are not state of the art yet. Further improvements are needed until succinic acid-based chemical production will be economically favorable.

Phenols from Lignin

Abstract: Lignin accounts for approximately 25–35 % of the organic matrix of wood and lignocellulosic biomass in itself is the most abundant renewable material on the planet. It has long been recognized as a potential feedstock for producing chemicals, fuels, and materials. Despite this excellent availabilty of lignin it is a low value compound and has so far mainly been used as energy source in combustion applications. Less than 5 % are being processed for other purposes. This article discusses the potential for an increased use of lignin as a renewable raw material, possible conversion routes towards monomeric phenolic compounds, and applications for these products. A brief overview about present state-of-the-art is given and a high-yielding, one-step approach of producing alkylated phenolic compounds from lignin is presented.

Fischer‐Tropsch Catalysts for the Biomass‐to‐Liquid (BTL)‐Process

Abstract: The Fischer-Tropsch synthesis is at the heart of the Biomass-to-Liquids (BTL) process. Feasibility studies published in open literature typically consider cobalt-based catalysts for the Fischer-Tropsch synthesis. Here, we present an overview on the history and development up until the present for both cobalt- and iron-based Fischer-Tropsch catalysts. The role of the support material and various other additives to the catalyst formulation are discussed in detail with regard to activity, catalyst deactivation, and selectivity. Tentative explanations for e.g. the observed size dependency in cobalt-based catalysts and phase transformations in iron-based Fischer-Tropsch catalysts are offered. The productivity of cobalt-based catalysts at high conversion level is currently higher than that of iron-based catalysts. Nevertheless, it is argued that iron-based catalysts may be an attractive option for the BTL-process, since it is much cheaper, impacting on the cost of the process due to inevitable process set-ups in industrial operation. Improvement of current iron-based catalysts is however desired.

Direct Liquefaction of Biomass

Abstract: Reserves of fossil primary energy carriers are limited. Consequently liquid secondary energy carriers especially for mobile applications made from fossil reserves will not carry on forever but need to be replaced in a not-to-far future. Two substitution strategies are currently under investigation – the use of oil from plant seeds either directly or after chemical modification (biodiesel) or the gasification of complete plants, use of the product gases (mainly CO and H2) in a Fischer-Tropsch process with subsequent refining. A third possible pathway would be the so-called direct liquefaction, i.e., the conversion of complete plants into liquid fuels without gasification. This process is discussed and various technical implementations are critically evaluated in the present paper.

The IBUS Process – Lignocellulosic Bioethanol Close to a Commercial Reality

Abstract: Integrated Biomass Utilization System (IBUS) is a new process for converting lignocellulosic waste biomass to bioethanol. Inbicon A/S has developed the IBUS process in a large-scale process development unit. This plant features new continuous and energy-efficient technology developed for pretreatment and liquefaction of lignocellulosic biomass and has now been operated and optimized for four years with promising results. In the IBUS process, biomass is converted using steam and enzymes only. The process is energy efficient due to very high dry matter content in all process steps and by integration with a power plant. Cellulose is converted to bioethanol and lignin to a high-quality solid biofuel which supply the process energy as well as a surplus of heat and power. Hemicellulose is used as feed molasses but in the future it could also be used for additional ethanol production or other valuable products. Feasibility studies of the IBUS process show that the production price for lignocellulosic bioethanol is close to the world market price for fuel ethanol. There is still room for optimization – and lignocellulosic bioethanol is most likely a commercial alternative to fossil transport fuels before 2012.

Microfluidic‐Assisted Synthesis of Polymer Particles

Abstract: Microfluidic devices have recently emerged as promising tools for the synthesis of polymer particles. Over conventional processes, microfluidic-assisted processes allow the production of polymer particles with an improved control over their sizes, size distributions, morphologies, and compositions. In this paper, the most common microfluidic devices are reviewed. Both projection photolithography and emulsification processes are reported for the continuous flow synthesis of polymer particles from a stream of polymerizable liquids. For the latter process, two distinct categories of microfluidic devices have been identified: microchannel-based and capillary-based microsystems. For each category, the existing geometries are described and the different emulsification methods including the co-flowing, cross-flowing, or flow-focusing of the continuous and dispersed phases are commented upon. Finally, for each microsystem the various polymer particles achieved in such devices including, but not restricted to, janus, core-shell, or porous particles and capsules are reported.

Reactors for Fischer‐Tropsch Synthesis

Abstract: The Fischer-Tropsch synthesis was discovered in Germany in the 1920s and has since been developed to industrial scale within a relatively short period of time. In the 21st century, the process is undergoing a renaissance, because an increasing fraction of liquid fuels will have to be produced from alternative raw materials like natural gas, coal or biomass in the future. On industrial scale, multitubular and bubble column reactors are used for this highly exothermic reaction. Due to several disadvantages of both reactor systems, new concepts are presently investigated. For intensification of mass transfer properties of multiphase reactors, alternative catalyst geometries like honeycombs, structured packings or foams are discussed. High catalyst utilization and isothermal operating conditions can be achieved in microstructured reactors. Furthermore, several membrane reactor concepts are under investigation. After an introduction to historical development and state of the art of Fischer-Tropsch reactors, chances and challenges of new reactor technologies will be discussed.

New Developments in Simulated Moving Bed Chromatography

Abstract: Chromatographic separation processes are widely used to isolate and purify value added products. Most frequently, such separation processes are performed exploiting the principles of injecting samples of the feed mixture in a repetitive periodic manner and collecting the target products batchwise. In the early 1960s, an alternative operation principle based on using several columns connected in series and exploiting a continuous countercurrent movement between the mobile and stationary phases initiated significant improvements in performing specific separation processes in the petrochemical and sugar industries. In the last decade, the so-called simulated moving bed (SMB) chromatography has rapidly entered the pharmaceutical industry. In particular enantioseparations using chiral stationary phases have become a strong driving force to develop more sophisticated concepts of continuous chromatography. Currently, the growing interest in efficient methods for the downstream processing of biomolecules enhances interest in SMB processes. This paper gives a brief overview of the new suggestions and trends.

Catalytic Processes for the Technical Use of Natural Fats and Oils

Abstract: Vegetable fats such as rapeseed oil, sunflower oil, palm oil or coconut oil consisting of triglycerides offer different carbon chain distributions. The use of these raw materials for the production of industrial chemicals as well as for fuel (biodiesel), which is finally a substitution for mineral oil, is a political discussion with various facets. The basic products such as fatty acids, fatty alcohols, and esters have different physical properties and lead to various areas of application depending on the carbon chain distribution. While the chain length range of C12 represents important raw materials for detergents, chain lengths of C18 are used mainly in industrial applications, e.g. as lubricants. Natural fatty alcohols are produced by the heterogeneous catalyzed high-pressure hydrogenation of methyl esters or fatty acids. The unsaturated fats and oils can be derivatized catalytically by functionalization, oligomerization, oxidation or metathesis. Thereby, new functional groups are introduced into the oleochemical substrate. The carbon chain length can be increased or reduced respectively, or a branching in the fatty chain is introduced. Products with completely new properties and areas of applications are available due to these catalytic variations of fats and oils.

Char and Coke Formation as Unwanted Side Reaction of the Hydrothermal Biomass Gasification

Abstract: The hydrothermal biomass gasification is a promising technology to produce hydrogen and/or methane from wet biomass with a water content of ≥ 80 % (g/g). In the process, the coke formation usually is very low, but already low amounts may cause problems like, e.g., fouling in the heat exchanger. To learn more about the product formation, the results of the hydrothermal treatment (at 400, 500, 600 °C and 1 h) of different biomass feedstocks (artichoke stalk, pinecone, sawdust, and cellulose as model biomass) in a microreactor are compared. The gas composition and the total organic carbon content of the aqueous phase were determined after reaction. The gas formation rises with increasing temperature. The formation of carbon deposits and their characterization has been investigated by scanning electron microscopy (SEM). The variation of the solid morphology during the hydrothermal conversion is discussed based on chemical pathways occurring during hydrothermal biomass degradation.

Extraction and Purification of Bioproducts and Nanoparticles using Aqueous Two‐Phase Systems Strategies

Abstract: Aqueous Two-Phase Systems (ATPS) is a primary recovery technique that has shown great potential for the efficient extraction and purification of high value biological compounds. The main advantages of this technique include scaling up feasibility, process integration capability and biocompatibility. In this review, the efficient use of ATPS for the extraction of proteins, genetic material, low molecular weight compounds, bioparticles, nanoparticles and cells is highlighted. The important role of ATPS in process integration, i.e., extractive conversion, extractive fermentation, cell disruption integrated with product recovery, and extractive purification, is discussed. A novel approach to protein molecular characterization combining ATPS and 2-dimension electrophoresis (2-DE) is introduced as a first step in the process development. Novel approaches for downstream processing using ATPS and dielectrophoresis are presented. Finally, trends concerning the application of ATPS strategies to address the future challenges of bioseparation are discussed.

High Throughput Screening for the Design and Optimization of Chromatographic Processes - Miniaturization, Automation and Parallelization of Breakthrough and Elution Studies

Abstract: This study evaluates the applicability of the liquid handling workstation Tecan Evo Freedom 200 and 200 μL Media Scout RoboColumns to dynamic chromatographic operations such as frontal analysis (breakthrough) and elution experiments in a high throughput screening mode. Breakthrough experiments were conducted using BSA as a model protein and the stationary phases Poros 50 D, Q Ceramic HyperD and DEAE Sepharose FF. The obtained dynamic capacities at 10 and 50 % breakthrough matched well with reference data. Elution experiments were performed applying three protein mixtures: a) lipolase and BSA, b) human growth hormone and a process-related impurity, and c) an insulin analogue and a process-related impurity. The resins used resembled a variety of different ion exchange resins. In all cases, the resulting elution curves matched well with reference measurements performed on an AKTA explorer system at 1 mL or 2 mL scale.

Modification of Nafion Membranes by Impregnation with Ionic Liquids

Abstract: Nafion 117 membranes were impregnated with various imidazolium (1-hexyl-3-methyl-imidazolium/HMI, 1-butyl-3-methyl-imidazolium/BMI) and pyrrolidinium (1-butyl-1-methyl-pyrrolidinium/BMPyr) based ionic liquids bearing hydrophobic (tris(pentafluoroethyl)trifluorophosphate/FAP, bis(trifluoromethylsulfonyl)imide/BTSI, hexafluorophosphate/PF6) and more hydrophilic (tetrafluoroborate/BF4) anions. The modified membranes were characterized in terms of uptake behavior, washing out of the ionic liquids by water, swelling in humidified environment, thermal stability, mechanical properties, ion exchange capacity and ion conductivity. Upon this treatment, the ionic liquids' cations partially replace the protons of the sulfonic acid groups in Nafion. While the ionic liquids act as potent plasticizers in the polymer matrix, thermal stability of these systems remains unchanged and swelling by water of the dried ionomer membranes is reduced. Ion conductivities at 120 °C under dry conditions have been found to be up to 100 times higher than for dry Nafion 117. In particular, modification of Nafion by ionic liquids bearing the bulky hydrophobic FAP anion seems promising.

CO2 Capture Using CaO Modified with Ethanol/Water Solution during Cyclic Calcination/Carbonation

Abstract: The calcium-based sorbent cyclic calcination/carbonation reaction is an effective technique for capturing CO 2 from combustion processes. The CO 2 capture capacity for CaO modified with ethanol/water solution was investigated over long-term calcination/carbonation cycles. In addition, the SEM micrographs and pore structure for the calcined sorbents were analyzed. The carbonation conversion for CaO modified with ethanol/water solution is greater than that for CaO hydrated with distilled water and is much higher than that for calcined limestone. Modified CaO achieves the highest conversion for carbonation at the range of 650-700 °C. Higher values of ethanol concentration in solution result in higher carbonation conversion for modified CaO, and lead to better anti-sintering performance. After calcination, the specific surface area and pore volume for modified CaO are higher than those for hydrated CaO, and are much greater than those for calcined limestone. The ethanol molecule enhances H 2 O molecule affinity and penetrability to CaO in the hydration reaction so that the pores in CaO modified are obviously expanded after calcination. CaO modified with ethanol/ water solution can act as a new and promising type of calcium-based regenerable CO 2 sorbent for industrial applications.

Phase Transformation of Iron Oxide Nanoparticles by Varying the Molar Ratio of Fe2+:Fe3+

Abstract: Co-precipitation from a solution of ferrous/ferric mixed salt with the ratio of Fe2+:Fe3+ = 1:2 in air atmosphere is not a reliable method to synthesize magnetite (Fe3O4) nanoparticles because of the fact that Fe2+ oxidizes to Fe3+ and the molar ratio of Fe2+:Fe3+ changes Therefore, the phase composition changes from magnetite to maghemite (γ-Fe2O3) The influence of the initial molar ratio of Fe2+:Fe3+ on the phase composition of nanoparticles, their crystallinity and magnetic properties was studied Experimental data from XRD, FTIR, SEM, and VSM reveal that the appropriate method to synthesize magnetite nanoparticles is reverse precipitation from only ferrous salt It is found that by decreasing the synthesis temperature and by increasing the concentration of alkaline solution and the ratio of Fe2+:Fe3+ the crystallinity and the specific saturation magnetization (σs) are increased

Microstructured Devices for Preparing Controlled Multiple Emulsions

Abstract: The preparation of multiple emulsions with controlled droplet sizes and internal structures has been a challenge for a long time. However, in recent years, a major breakthrough has been achieved in the preparation of monodisperse single emulsions by small-scale fluid processing, which has enabled the formation of multiple emulsions with the desired droplet sizes, structures, and compositions. This review deals with the preparation of controlled multiple emulsions in various microstructured devices. The four preparation pathways are discussed individually. They are (a) membrane emulsification, (b) microchannel emulsification, (c) the use of a two-dimensional microfluidic device, and (d) the use of a three-dimensional coaxial microcapillary device. The applications of the prepared multiple emulsions to a novel class of materials are also discussed.

A review of the thermodynamics of protein association to ligands, protein adsorption, and adsorption isotherms

Abstract: The application of thermodynamic models in the development of chromatographic separation processes is discussed. The paper analyses the thermodynamic principles of protein adsorption. It can be modeled either as a reversible association between the adsorbate and the ligands or as a steady-state process where the rate of adsorption is equal to the rate of desorption. The analysis includes the competitive Langmuir isotherm and the exponentially modified Langmuir isotherm. If the adsorbate binds to one ligand only, the different approaches become identical. When the adsorbate acts as a ligand, dimerization takes place and will give rise to a sigmoid isotherm. A model that accounts for dimerization is discussed and a sample calculation shows the behavior of this isotherm. Insulin is known to have a concave isotherm at low concentrations. The calculation of the standard Gibbs energy change of adsorption is discussed. Hydrophobic and reversed phase chromatography are useful techniques for measuring solute activity coefficients at infinite dilution.

Dividing Wall Distillation Columns: Optimization and Control Properties

Abstract: The optimal design of dividing wall columns is a non-linear and multivariable problem, and the objective function used as optimization criterion is generally non-convex with several local optimums. Considering this fact, in this paper, we studied the design of dividing wall columns using as a design tool, a multi-objective genetic algorithm with restrictions, written in MatlabTM and using the process simulator Aspen PlusTM for the evaluation of the objective function. Numerical performance of this method has been tested in the design of columns with one or two dividing walls and with several mixtures to test the effect of the relative volatilities of the feed mixtures on energy consumption, second law efficiency, total annual cost, and theoretical control properties. In general, the numerical performance shows that this method appears to be robust and suitable for the design of sequences with dividing walls.

Vegetal Refining and Agrochemistry

Abstract: The industrial process developed by CIMV is a world first for the manufacture of whitened paper pulp, sulfur free linear lignin and xylose syrup from annual fiber crops and hardwood. This new technology allows the separation without degradation of the three main components, i.e., cellulose, hemicelluloses and lignins, isolated from the vegetable matter. The CIMV process is a biorefinery functioning on a model resembling an oil refinery. The lignins have a linear structure that permits high reactivity with different monomers producing new polymers and new formaldehyde-free adhesive formulations. The C-5 sugar syrup can be used to produce additives for animal feeding and chemicals. The pilot plant in operation since 2006, near Reims, has given fully satisfactory results. The CIMV chemical engineering approach, proceeds by the use of classical industrial equipment. This should allow the scale up of the original CIMV concept to result in production at industrial levels in 2009.

Liquid Extraction of Vanillin in Rectangular Microreactors

Abstract: In this paper, the extraction of vanillin dissolved in water with a suitable organic phase using microstructured devices made of PDMS is discussed. Two flow patterns, segmented and stratified flow, were compared. LIF and μ-PIV measurements showed a laminar profile for stratified flow; whereas for segmented flow, vortices in the slug end were detected. Additionally, for the stratified flow regime, the influence of the channel width and therefore the surface-to-volume ratio was investigated. A decrease of the channel cross-sectional area results in a significant enhancement of mass transfer for the stratified flow regime. A further increase in mass transfer was obtained using segmented flow instead of stratified flow. However, stratified flow may be favored due to the ease of implementation of phase separation on the chip.

Effect of Ultrasonic Waves on the Saccharification Processes of Lignocellulose

Abstract: The pretreatment and saccharification process of lignocellulose are subjected to ultrasonic waves to enhance the saccharification rate. The morphology, structure and crystal performance of the original and treated ligno-cellulose samples are characterized. The mechanism of the effect of ultrasonic waves on the enzymatic catalysis process is discussed.

Biofuels – Economic Aspects

Abstract: Assuming an oil price of US$60 per barrel, both biodiesel and bioethanol produced from wheat are not profitable in Europe. The producers' high margins are only due to the current mineral oil tax concessions. At present, biomass-to-liquid (BTL) fuel also cannot be produced competitively. At the assumed oil price, only bioethanol and biobutanol produced on a large scale from lignocellulose-containing raw materials have the potential to be produced competitively. Analyses of the technologies used in this field show that in Europe there are interesting new technological developments for the hydrolysis, fermentation and purification step.

Development of an Industrial Multi‐Injection Microreactor for Fast and Exothermic Reactions – Part II

Abstract: A Grignard reaction performed in a microreactor is presented. The reaction is of type A (highly exothermic and very rapid) and has a low yield which is attributed to a hot spot formed in the mixing zone of the reactor. The reaction yield could be significantly increased by applying the multi-injection principle, leading to better thermal control in the microreactor. Nevertheless, the microreactor plays a major role in reducing the magnitude of the hot spot. Knowing this, it was possible to design and construct an industrial microreactor with significant advantages such as modularity, high flow rate operation, and low investment expenditure (pumps and flow controller minimization).

Raw Material Changes in the Chemical Industry

Abstract: Until the 19th century, renewable raw materials were the major source of energy generation and material use. With the Industrial Revolution, the use of coal increased sharply and coal quickly developed into a key raw material in the chemical industry, mainly in the production of dyes. In the past century, there has been a consistent changeover in fossil fuel sources from coal to crude oil and natural gas due to lower prices, simpler logistics and the versatility in usage of oil and gas. In view of the limited availability and increasing price of crude oil and natural gas, the question now arises as to how the raw material base will develop in the future?

Multiphase CFD Modeling for a Chemical Looping Combustion Process (Fuel Reactor)

Abstract: There are growing concerns about increasing emissions of greenhouse gases and a looming global warming crisis. CO2 is a greenhouse gas that affects the climate of the earth. Fossil fuel consumption is the major source of anthropogenic CO2 emissions. Chemical looping combustion (CLC) has been suggested as an energy-efficient method for the capture of carbon dioxide from combustion. A chemical-looping combustion system consists of a fuel reactor and an air reactor. The air reactor consists of a conventional circulating fluidized bed and the fuel reactor is a bubbling fluidized bed. The basic principle involves avoiding direct contact of air and fuel during the combustion. The oxygen is transferred by the oxygen carrier from the air to the fuel. The water in combustion products can be easily removed by condensation and pure carbon dioxide is obtained without any loss of energy for separation. With the improvement of numerical methods and more advanced hardware technology, the time required to run CFD (computational fluid dynamic) codes is decreasing. Hence, multiphase CFD-based models for dealing with complex gas-solid hydrodynamics and chemical reactions are becoming more accessible. To date, there are no reports in the literature concerning mathematical modeling of chemical-looping combustion using FLUENT. In this work, the reaction kinetics models of the (CaSO4 + H2) fuel reactor is developed by means of the commercial code FLUENT. The effects of particle diameter, gas flow rate and bed temperature on chemical looping combustion performance are also studied. The results show that the high bed temperature, low gas flow rate and small particle size could enhance the CLC performance.

Intensification of Nicotinic Acid Separation using Organophosphorous Solvating Extractants by Reactive Extraction

Abstract: Nicotinic acid (3-pyridine carboxylic acid) is widely used in food, pharmaceutical, and biochemical industries. Compared to chemical methods, enzymatic conversion of 3-cyanopyridine is an advantageous alternative for the production of nicotinic acid. This study is aimed to intensify the recovery of nicotinic acid using reactive extraction with organophosphorus solvating extractants such as tri-n-octyl phosphine oxide (TOPO) and tri-n-butyl phosphate (TBP). The distribution of nicotinic acid between water and phosphorus-based solvents dissolved in various diluents and the comparison of extraction efficiency with pure diluents are studied at isothermal conditions. Pure diluents are not found to be good extracting agents and the maximum distribution coefficient (K D ) obtained with 1-octanol is 0.31. Experimental studies are carried out to investigate the effect of diluent, initial acid concentration, extractant type, and extractant composition on the degree of extraction. The maximum recovery of nicotinic acid is obtained by dissolving TOPO in MIBK at an initial nicotinic acid concentration of 0.10 kmol/m 3 . Solvation numbers and extraction equilibrium are also estimated with both TBP and TOPO.

Continuous Multi‐Injection Reactor for Multipurpose Production – Part I

Abstract: The paper presents an analysis of chemical production requirements in an exclusive synthesis market environment and describes how this analysis guided the development of a modular multi-injection reactor. Detailed engineering of a reactor in the light of the requirements of an organometallic reaction, as well as characterization of the reactor is reported. This reactor has provided the target chemistry result at Lonza Ltd. as detailed in a companion paper.

Kinetic and Statistical Studies of Adsorptive Desulfurization of Diesel Fuel on Commercial Activated Carbons

Abstract: Diesel fuel desulfurization by different commercial activated carbons was studied in a batch adsorber. Experiments, carried out to determine the sulfur adsorption dependency on time, were used to perform kinetic characterization and to screen the best performing activated carbon. The equilibrium characterization of the adsorption process was also performed. The statistical study of the process was undertaken by way of a two-level one-half fractional factorial experimental design with five process parameters. Individual parameters and their interaction effects on sulfur adsorption were determined and a statistical model of the process was developed. Chemviron Carbon SOLCARBTM C3 was found to be the most efficient adsorbent. The kinetic pseudo-second order model and Freundlich isotherm are shown to exhibit the best fits of experimental data. The lowest achieved sulfur concentration in treated diesel fuel was 9.1 mg/kg.

Millisecond methane steam reforming via process and catalyst intensification

Abstract: The steam reforming of methane on a rhodium/alumina based multifunctional microreactor is simulated using fundamental chemical kinetics in a pseudo-two-dimensional microreactor model. The microreactor consists of parallel catalytic plates, whereby catalytic combustion and reforming take place on opposite sides of a wall. Heat exchange happens through the wall. It is shown that reforming can happen in millisecond or lower contact times and proper balancing of flow rates can give high conversions, reasonably high temperatures, and high yield to syngas. It is found that tuning catalyst surface area and internal and external mass and heat transfer through reactor sizing can lead to further process intensification.

Measuring Mixing Time in the Agitation of Non‐Newtonian Fluids through Electrical Resistance Tomography

Abstract: Electrical resistance tomography (ERT), which is a non-invasive and robust measurement technique, was employed to visualize, in three dimensions, the concentration field inside a cylindrical mixing vessel equipped with a radial-flow Scaba 6SRGT impeller. The ability of ERT to work in opaque fluids makes this technique very attractive from an industrial perspective. An ERT system with a 4-plane assembly of peripheral sensing rings, each containing 16 electrodes, was used to measure the mixing time in agitation of xanthan gum solution which is a pseudoplastic fluid with yield stress. An image reconstruction algorithm was used to generate images of the tracer distribution within the sensing zone. In this study, the effect of impeller speed, fluid rheology, power consumption, and Reynolds number on the mixing time was investigated.