Mixing Tank Research Articles

Assessing of drinking water quality in Al-karak province in central Jordan; based on water saturation indices

Jordan is renowned for having limited water resources. The demand for water will increasing rapidly as the country's population grows and the number of refugees increases. In order to maintain the highest water quality for consumers, the Ministry of Water and Irrigation and other governmental agencies are striving to manage Jordan's water resources through continuous monitoring. The main objective was to evaluate the drinking water quality at storage mixing tanks at Al-Karak province, besides, assessing its suitability for safe consumption. The investigation scheme was to monitor Al-Karak's drinking water system for three successive months. The fourteen principal storage tanks for the water distribution system in the area of investigation were sampled. The pH, electrical conductivity (EC), major cations, major anions, total dissolved solids (TDS), total hardness (TH), turbidity, total alkalinity (TA), and heavy metals were measured. The scaling and originality of the dissolved salt elements in the collected water samples and geochemical processes were examined using Piper and Durov diagrams. The indices used in all samples over the period of investigation, are Langelier Saturation Index (LSI), Ryznar Stability Index (RSI), Aggressive Index (AI), Puckorius Scaling Index (PSI), and Water Quality Index (WQI). The results showed that scale development is high in all storage tanks, as the water is calcium carbonate supersaturated, evident from LSI values that ranges 0.5–2. According to the range of RSI values (5.91–6.6), all water tanks are resistant to corrosion. Throughout the period of study (October–December), the estimated WQIs of all samples upon average were found to be less than 50, indicating excellent water quality. Finally, the collected water samples are analyzed and found to be within the acceptable levels of Jordan's drinking water standards.

Tank Jet Mixer Design, Arrangement & Applications

Side entry mixers or jet mixers are commonly used to achieve mixing in storage tanks and reactors. Impellers are other conventional devices used for mixing in industry, but they are expensive for large storage tanks and underground tanks. Jet mixers have been a better alternative to impellers in the process industry. Compared with Mechanically agitated mixers, these mixers use jet technique to create high turbulence, high shear rates and vortex motion offer several advantages in achieving rapid mixing over a short period of time without any moving parts. Jet mixing has become an alternative to conventional impeller mixing for various applications in process industries. To ensure optimal mixing performance, it is important to understand the basis of jet mixer design & also impact of different parameters in jet mixer design & preferred installation of mixers.

ТЕХНОЛОГИЯ ПРИГОТОВЛЕНИЯ И ПОДАЧИ КОМПЛЕКСНОГО ТОПЛИВА ДЛЯ УЛУЧШЕНИЯ ЭКСПЛУАТАЦИОННО-ТЕХНИЧЕСКИХ ХАРАКТЕРИСТИК ДИЗЕЛЬНЫХ ДВИГАТЕЛЕЙ АВТОТРАКТОРНОЙ ТЕХНИКИ

The technology of preparation and supply of complex fuel is proposed to improve the operational and technical characteristics of diesel engines of automotive equipment, as well as technical means for its implementation. The analysis of the work of the ATT samples showed that its operation occurs with low speeds in the field and heavy loads on the internal combustion engine (ICE), while its thermal tension increases and the combustion process worsens in the combustion chamber, leading to the formation of carbon deposits. To solve this problem, a method and technical means are proposed for cleaning engine parts from the formed carbon deposits without parsing it during daily operation in order to improve the operational and technical characteristics of equipment, on which the readiness of samples of the machine and tractor fleet will directly depend. The developed method is based on direct mixing of fuel with water, dispersion of the resulting mixture and feeding into the combustion chamber of the internal combustion engine when the fuel temperature exceeds a given value, and depending on the temperature, as well as the number of revolutions of the internal combustion engine and from different levels of the mixing tank. The versatility of the developed devices for the implementation of the proposed method is that they can be used not only in stationary conditions, but also on board the equipment during its operation. The implementation of the developed method and technical devices will ensure effective removal of carbon deposits due to the interaction of red-hot carbon particles with water droplets (steam), which will lead to an increase in the resource of diesel internal combustion engines, restoration of operational and technical characteristics of especially worn-out diesel internal combustion engines and ultimately increase the readiness of individual samples of ATT and, in general, the technical readiness of the machine and tractor fleet.

Intensification of power efficiency by grooves in flanged impellers

The effect of grooved blade impellers and leading-edge flanged impellers on mixing in agitated tanks has been studied separately in an already published study. It was found that both configurations reduced impeller power consumption. The most significant reduction of power consumption, compared to the classical Pitched Blade Turbine (PBT), was achieved using flanges. Based on these results, in this work, the blades of the classical PBT were modified with the combination of both previous, flange and groove structures to evaluate their performance. It was found that such a combination produces a synergistic effect that reduces flow separation caused not only by flow impinging on the leading-edge of the blade but also by suction flow leaving the lateral edge of the blade tip. The combination of flanges with curved structures results in a reduction in power of 29.6 % compared to PBT, and more than twice that modified impeller with only leading-edge flanges. Also, the pumping efficiency is increased with the combination of both modifications as it resulted in 40.6 % higher than the PBT. Experimental and Computational Fluid Dynamics (CFD) measurements were performed with different patterns of grooves, modifying angles, and curvature. Different parameters such as power number, pumping number, and mixing efficiency, among other important parameters for bioreactors such as the Kolmogorov length scale (k), and hydrodynamic stresses were evaluated experimentally and by CFD.

Effect of Contact Time on The Adsorption Process of Activated Carbon from Banana Peel in Reducing Heavy Metal Cd and Dyes Using a Stirring Tub (Pilot Scale)

One of the most successful processes for extracting, recovering, and recycling metals from wastewater is adsorption utilizing natural activated carbon, such as banana peel waste. This is advantageous for a wastewater treatment sector since natural activated carbon is less expensive than conventional activated carbon. The aim of this research is to determine the optimum contact time at removing heavy metals and colour using a stirrer tub (pilot scale). Physically, banana peels would be burned at a high temperature of 300°C, and chemically, they would be activated with a 20% sulfuric acid (H2SO4) solution. A mixing tank with a volume of 30 L and a stirring machine spinning at 200 rpm was employed as a contact point between wastewater and activated carbon. Time variations of 15, 30, 60, 75, and 90 minutes were explored to find the best contact time. The ideal circumstances for 75 minutes obtained a Cd metal removal effectiveness of 98.63% with an adsorption capacity of 0.38 mg/g, according to the findings. At the optimum time of 90 minutes, the kepok banana peel was 97.38% successful in absorbing the color using a stirrer.

Improving mixing and renewal in drinking water storage tanks: lessons learnt and practical measures

ABSTRACT This paper investigates the effect of different types of structural and operational measures on water mixing and renewal time in circular and rectangular cross-section water storage tanks, aiming at a better understanding of the flow dynamics to find practicable solutions to improve their design, rehabilitation and operation. An experimental programme, including traditional tracer and dye tracer tests, was carried out in small-scale tanks for different configurations and operating conditions. Two tanks were tested with and without interior structures, with the inlet/outlet pipes at different locations and for constant and variable water level. The main findings are that: i) the most effective measure is operating with fill-and-draw cycles, however, for tanks operated nearly full structural measures are recommendable; ii) reducing the inlet pipe diameter and installing nozzles near the tank bottom improve the mixing conditions; iii) the use of baffles is recommendable when the inlet and outlet pipes are very close.

An analogous scale model for laboratory mixing studies

This technical note illustrates application of a model gypsum scale system purposely developed to investigate the effect of flow condition on scale growth in mixing tanks. Photos of non-uniform scale growth distribution in laboratory mixing tanks are presented. The laboratory results are found to match qualitatively to that observed in the full-scale plant. Due to its low cost and simplicity in application, this method can be applied in mixing pilot testing so that scale mitigation can be included in the agitator and tank design optimisation.

Of the temperature to render fat down affecting the biodiesel yield from cow fat by the transesterification reaction method

Animal fats are high in saturated fatty acids, so they are useful in the part of soap making, including biodiesel oils. Its advantage is high heating and low cost. The aim of this research was to study the temperatures to render fat down from cow fat at 150 °C, 200 °C, 250 °C, 300 °C, and 350 °C, ±2 °C affecting the biodiesel oil yield. The transesterification reaction biodiesel production by using the base catalyst including Methanol (CH3OH) and Sodium hydroxide (NaOH). The reaction temperature was controlled at 50 °C. The experiment is carried out with a biodiesel reactor consisting of the rendered set, catalyst mixing tank, and heating set to get rid of water from biodiesel. The trend toward the increased temperature to render fat down also affected the higher FFA and a temperature of 350 °C, this resulted in a higher range of 2.53% of the FFA. The result was found that the optimum temperature for rendering fat down was 250 °C and the biodiesel oil yield was 75.50% by volume, the HHV had a maximum of 41.17 MJ kg–1, and viscosity of 4.60 cSt. Furthermore, it illustrated that the temperature to render fat down that is too high will affect to decrease the biodiesel yield but increase glycerin content.

Development of Mixing and Pressing Processes of Split-Gill Mushroom Spawn Blocks

This study aims to develop the mixing and pressing processes of split-gill mushroom spawn blocks through the development and construction of a semi-automatic mushroom spawn mixing. The developed machine uses a 0.5 hp motor to drive the mixing tank and the press cylinder, which are connected to a 1:60 reduction gear. The results show that the semi-automatic mushroom spawns mixing and pressing machine developed in this study are within the standard ranges, that the split-gill mushroom spawn blocks with an average weight of 598 g, an average height of 10.2 cm, and an average density of 0.33 g/cm3. As for production capacity, manual pressing produced 40 mushroom spawn blocks per hour while the developed machine produced 112 mushroom spawn blocks per hour, which is 2.8 times faster.

Minimising Butadiene Level in Liquefied Petroleum Gas (LPG) via Non-Stirred Blending with Numerical Approach

LPG has variable commercial grades due to its varying LPG composition will yield different properties. Because their properties depend on the composition, the LPG quality will differ based on the source of its production extracted either from refinery streams or natural gas. The composition of propane and butane, which are the two major components in LPG composition, play an important role in reflecting the properties of LPG, as the mixtures influence the boiling points and also meet product specification requirements. Butadiene is also present in LPG, albeit in trace amounts. Although butadiene is a minor component, it must be kept minimised of the total weight fraction due to regulatory limits. Butadiene is a hazardous chemical that, when inhaled, can cause cancer and genetic defects. LPG used for commercial purposes that contain of any carcinogenic substance such as butadiene must also be classified as carcinogenic. The LPG plant operator is facing the problem that imported LPG composition from outside sources contain levels of butadiene that exceed the regulatory limit of 0.5% of weight fraction. LPG composition, containing butadiene levels that exceed 0.5% of weight fraction is considered as off-specification, while butadiene levels less than 0.5% of weight fraction are considered as on-specification the LPG products. To reduce the levels of butadiene that exceed 0.5% of the weight fraction in off-specification LPG products, the blending of on-specification LPG products with off-specification was introduced and provided the most economical method inside the plant. The jet mixing approach was selected to predict the homogeneous blending time for each different off-specification LPG composition because it is the best approximation for natural mixing behaviour. Four empirical mixing time correlations of jet mixing were applied for the prediction of homogeneous blending time; the correlations were derived by Lane and Rice (1982), Maruyama, Ban and Mizushina (1982), Grenville and Tilton (1997) and Hiby and Modigell (1978). The homogeneous blending time predicted by these four mixing time correlations decreased as the quantity of on-specification LPG required increased, which is in good agreement with both simulation results of 95% and 99% mixing. Therefore, due to the development of individual jet mixer correlation, these four mixing time correlation results in different homogeneous blending times was going through the different measurement techniques and monitoring methods in jet mixed tanks.

Influence of Impeller and Mixing Tank Shapes on the Solid–Liquid Mixing Characteristics of Vanadium-Bearing Shale Based on the DEM-VOF Method

The mixing tank is important equipment for industrial applications in the wet vanadium extraction process, but in practice, there are problems, such as uneven mixing of minerals. In this study, the effect of different types of impellers and different mixing tank structures on the suspended mass of particles was simulated using the discrete element method and volume of fluid method (DEM-VOF). The simulation results show that the round-bottomed tank performed mixing better than the flat-bottomed tank at different particle densities, and the flat-bottomed tank was prone to particle stratification and other phenomena. The round-bottomed mixing tank could better improve the solid–liquid suspension effect. In this study, the coefficient of variation σ was introduced to characterize the suspended mass of particles. By monitoring the σ value, it was found that the blade pitch angle 45 (BPA45) had the best mixing uniformity in the inclined pitched blade turbine (PBT). As the PBT impeller pitch angle increased, the particle suspension increased. When comparing different types of impellers, the Rushton exhibited a 45% improvement in mixing uniformity relative to the BPA45. Second, the width and height of the trough bottom projection were optimized and their σ values were calculated separately for different parameter conditions. The width of 0.05 m and height T/4 (T being the diameter of the tank) were finally determined to be the optimum parameters for the optimal design of the vanadium shale leaching mixing trough.

Testing the Greenhouse Emission Model (GEM) for Pesticides Applied via Drip Irrigation to Stone Wool Mats Growing Sweet Pepper in a Recirculation System

Pesticide emissions to surface water from greenhouses with crops grown on substrates in open or closed systems may be significant. It is important, therefore, to test models such as the Greenhouse Emission Model (GEM), which was developed to assess these emissions as part of the Dutch authorization procedure for use of plant protection products in greenhouses. GEM was tested using an experiment in which imidacloprid and pymetrozine were applied via drip irrigation to stone wool mats growing sweet pepper. The irrigation system in such greenhouses consists of a mixing tank to prepare the nutrient solution and a series of tanks to treat and recirculate the drain water back to the mixing tank. Emissions may occur because (part of) this recirculation water may be discharged or leached to the surface water. GEM assumes that all tanks are perfectly mixed. GEM further assumes that the water in these mats is perfectly mixed and that the pesticide behavior can be simulated by assuming one perfectly mixed reservoir. The model predicted breakthrough of both pesticides out of the mats earlier than measured, and the measured maximum concentrations were approximately two times lower than predicted. We considered a series of possible causes, including a smaller water volume in the mats, a higher plant uptake factor, and sorption to the stone wool. The model performance improved by representing the mats as a sequence of two equally large tanks with plant uptake restricted to the first tank. We recommend to study the solute transport process and the distribution of plant roots in the mats in more detail to further underpin the hypothesis used and improve the model. After this first validation, the GEM model might also be used in other countries to forecast emissions of PPPs to surface water.

Taylor vortex-based protein crystal nucleation enhancement and growth evaluation in batchwise and slug flow crystallizers

The utilisation of nucleation seeds, coupling nucleation and growth during crystallization and realistic continuum are currently relatively robust, reliable and scalable methods for protein crystallization optimization. Here, we design a segmented crystallization method, in which combines the characteristics of the Taylor vortex enhanced lysozyme nucleation stage. Different crystallizer are used for the growth segment so that the nucleation segment and the growth segment are organically combined during lysozyme crystallization. During the crystal growth stage, the crystallization properties of the Couette-Taylor (CT) crystallizer, mixing Tank (MT) crystallizer and tubular crystallizer were evaluated. The experimental results emphasize the importance of shear rate, temperature, and fluid velocity in the design of segment crystallization methods to obtain products with complete crystal morphology and uniform size distribution. This strategy successfully expanded the lysozyme crystallization from the original 10 mL scale to 200 mL, realized the continuous process, and providing a promising strategy for the design and operation of continuous SFC to produce high value protein crystals in the future.

Water mixing in rectangular storage tanks: small-scale versus field tests

ABSTRACT Mixing and renewal processes are crucial for maintaining adequate drinking water quality in storage tanks. This paper studies the influence of baffle structures and of fill-and-draw cycles on water mixing and renewal in rectangular cross-section tanks through laboratory tracer tests carried out in two small-scale tanks (with and without baffles) and compares with results from a full-scale test. This study shows that the use of baffles inhibits water mixing and keeps older water pockets in small recirculation zones, though baffles allow faster water renewal than in open tanks for lower flow rates. High water volume variation in fill-and-draw cycles (between 50% to 80%) promotes water renewal, independently of the tank configuration (i.e. cross-section and the existence of baffles). Despite the existing baffle structure in the full-scale rectangular tank with 20% water volume variation, the high flow rates allowed a rapid renewal of the stored water.

Dual-Mode Based Sliding Mode Control Approach for Nonlinear Chemical Processes.

This paper synthesizes a new sliding mode controller (SMC) approach to enhance tracking and regulation tasks by following dual-mode concepts. The new control law consists of two distinct types of operation, using the combination of higher gain to large error signals (transient) and lower gain to small error signals (the region around the set point). The design is presented from a dual-mode (PD-PID) sliding surface operating in concert, fulfilling desired control objectives to ensure stability and performance. Therefore, a new controller was established, and we called it a dual-mode based SMC. The proposed controller is tested by computer simulations applied to two nonlinear processes, a continuous stirred-tank reactor (CSTR) and a mixing tank with a variable dead time. The results are compared with two different alternatives of SMC. In addition, the merits and drawbacks of the control schemes are analyzed using radial graphs, comparing the control methods with various performance measures for set points and disturbances changes. The ITSE (integral of time multiplied by the squared error), TVu (total variation of control effort) indices, Mp (maximum overshoot), and ts (settling time) were the indices used for performance analysis and comparisons.

Integrating mechanical mixing, headspace, and rheology in a computational model for a fermentation process

AbstractAlthough computational fluid dynamics (CFD) modelling has been applied to study bioprocesses where mechanical mixing and aerations are key, the effect of having a free surface has usually been ignored. This work studies a mixing tank for bioprocess applications to analyze the impact that the assumption of a flat liquid level has upon the modelling results, with and without aeration. The methodology takes an experimental and modelling approach. A dual impeller mixer with a speed of 400 rpm is used for batch systems with both non‐Newtonian and Newtonian fluids to characterize the axis torque and surface vortex formation. Several multi‐phase CFD models are applied to study the modelling and numerical effects of the headspace on the results. Regarding modelling accuracy, the CFD models are shown to be able to capture the effect of the free surface on the fluid dynamics of the stirred tank for different fluid rheologies. Therefore, the simplification of the liquid level as a flat and fixed surface should not be applied, especially for a process with aeration or when unaerated conditions can lead to a surface vortex. Regarding the numerical accuracy, it is concluded that the mixture model does not predict the interface shape as well as the Eulerian model. However, only the mixture model shows to be numerically stable. Overall, this work provides validated CFD configurations able to predict the effect of a free surface on the mixing mechanisms in stirred reactors.

Stabilizer-Free PdCu Nanoparticles Dispersed on Carbon Using Taylor Vortex Flow as Catalysts for Electrochemical Oxidation of Formic Acid

Stabilizers play a critical role in synthesizing small and well-dispersed nanoparticles with large catalytic surface areas. Simultaneously, they strongly bind to the surface of the nanoparticles and interfere with the catalytic reaction. In this study, we report that the effects of stabilizers can be replaced by the periodic and uniform fluid shear of Taylor vortex flow (TVF). Small PdCu alloy nanoparticles well-dispersed on carbon were synthesized in the Couette–Taylor reactor using TVF without the stabilizer. TVF could provide effective micromixing for a fast reaction and uniform fluid shear to prevent aggregation in nanoparticle synthesis, thus forming small and well-dispersed nanoparticles. In contrast, turbulent eddy flow generated by impeller agitation in a mixing tank reactor could only synthesize aggregates of nanoparticles seriously, indicating the importance of the periodic uniform flow. The synthesized stabilizer-free PdCu nanoparticles (Pd41Cu59/C) showed 1.4 times and 3 times higher mass activity than PdCu/C covered with a stabilizer (polyvinylpyrrolidone) and commercial Pd/C toward electrochemical formic acid oxidation, respectively.

전산유체해석을 활용한 일체형 침전부상조 미세기포수 및 최종처리수 유공관의 설계인자 검증 연구

In this research, the feasibility of the design parameters for microbubble distribution and perforated drainpipes in the integrated sedimentation and dissolved air flotation (SeDAF) process for an advanced wastewater treatment plant was verified using computational fluid dynamics (CFD) analysis. The flow rates for the raw water and the microbubble distribution stage were 100 and 15㎥/d respectively. In the simulation, the raw water was first introduced into the mixing tank and then passed on to the coagulation, sedimentation, and flotation stages in sequence. The flow velocity for each stage increased at the narrowed cross-sectional points. It was observed that some of the coagulated water flowing into the inclined plate module in the sedimentation stage spilled out. As a result of the CFD analysis, the average flow rate for the four perforated distribution pipes was 0.014 kg/s. The standard deviation (SD) for the simulations of original and alternative model was 0.00050 and 0.00062, respectively, which indicated that the simulations were successful and reliable. The SD for the average flow rate for the four perforated pipes was 0.00706, 0.00779, 0.00833, and 0.00938, respectively. The aver age flow rates for each pipe were decreased by 0.0003, 0.0000, 0.0002, and 0.0002 kg/s, respectively compared to the original model. This simulation of characterization of microbubble distribution and perforated drainpipe demonstrated that the design parameters for the distribution pipes were set so that the microbubbles were distributed evenly and that the perforated drainpipes successfully withdrew the treated water within the integrated SeDAF process.

Studying particle attrition in a solid-liquid agitated vessel using focused beam reflectance measurement (FBRM)

Over-processing particles during mixing in the mineral and chemical processing industries can lead to particle damage and diminished product quality. Therefore, the mixing tank design needs to be optimized to keep particles suspended while minimizing energy consumption and particle attrition. This study investigates particle attrition in a mechanically agitated vessel using focused beam reflectance measurement (FBRM). The effects of three different impeller types were studied under baffled and unbaffled conditions using solids concentrations from 5 to 30 wt%. Increasing solids concentration increased the particle count up to three times due to increased levels of particle attrition. The increase in particle counts due to attrition was lower under unbaffled conditions for 25 and 30 wt% solids for all impellers, indicating process intensification possibilities with lower particle attrition for these solids concentrations. Compared to a pitched blade or Ruston turbine, an A310 impeller minimized particle attrition close to zero under unbaffled conditions.

Design of a hospital laundry effluent clarification system

Approximately 20% of the mineral coal ash (MCA) generated worldwide, during the combustion of this fossil fuel, has been used to produce Portland cement. Other applications include soil improvement, ceramic industry, catalysis, and an application with special interest for this work which is the synthesis of zeolites. A hospital effluent clarification system was developed using MCA as an adsorbent for substances responsible for the color of the effluent generated by the laundry. A perfect mix tank promotes intimate contact between MCA and the effluent. At the exit of the mixing tank, a pH sensor correlated the value of this variable with the concentration of MCA in the mixture inside the tank. The information about the pH of the mixture was then sent to a programmable logical controller (PLC), which regulated the motor speed of a screw conveyor, with the aid of a frequency inverter. A color removal efficiency of the order of 99.8% was achieved. The proposed clarification system can operate both in batch and continuous. In the first case, the ideal operating conditions can be set. The strategy for adjusting operating conditions is to obtain an adequate nominal capacity for the system by reducing or increasing the number of cyclones per battery or the number of cyclone batteries.