Vertical Centrifugation Research Articles

Effect of Splitter Blade on Suction Performance of Vertical Multi-stage Centrifugal Pump

Effect of Splitter Blade on Suction Performance of Vertical Multi-stage Centrifugal Pump

The Oil:Water Ratio in the Vertical Centrifuge Separator and Its Influence in Phenolic Compounds in the Virgin Olive Oil and the Olive Mill Wastewater (Alpechín)

The use of the vertical centrifuge in the olive oil production process is generally assumed to be habitual and necessary for the elimination of both the vegetation water and the small olive pulp particles that are not eliminated during solid–liquid separation (horizontal centrifugation). Trials were carried out with different oil:water ratios to study the influence of this variable on both the quality parameters of the olive oils obtained and the loss of oil with the olive wastewater. The trials were carried out at the industrial mill level with oil:water ratios between 0.6 and 5.5. While no differences were observed in the quality parameters of the oils obtained, correct adjustment of the oil:water flow rates reduced the loss of phenols present in the oils by around 30%. In addition, the results show a direct relationship between the soluble effluent and the conductivity of the olive mill wastewater (alpechín) with the loss of oil in the effluent. This work proves that both oil quality and the competitiveness of the olive oil value chain can be increased with energy savings, water consumption reduction, and environmental sustainability.

CFD simulation of unstable fluid flows in the rotor of a high-speed precipitation centrifuge

The results of a numerical study of unstable fluid flows in the rotor of a high-speed vertical precipitation centrifuge are presented. It is shown that during the operation of a high-speed precipitation centrifuge, a qualitative change in the hydrodynamic regime is possible from conditionally laminar to conditionally turbulent, characterized by large-scale axial and radial pulsations of the liquid phase, accompanied by a significant decrease in sedimentation efficiency. It has been established that the flow pulsations are not random in nature, but the amplitude of these pulsations first increases with increasing rotation rate of the centrifuge rotor, and after passing a certain “critical” rotation rate it begins to decrease. Thus, the “critical” rotor rotation rate can be considered as a resonant rate, at which the frequency of turbulent flow pulsations (natural oscillation frequency) coincides with the rotor rotation frequency (forced oscillation frequency). The dependences of the pitch, frequency, and amplitude of liquid flow pulsations on the edge of the centrifuge overflow disk on the rotor rotation rate were obtained. It has been established that in the “subcritical” and “supercritical” operating modes, the amplitude and step of liquid pulsations on the overflow disk of the centrifuge are increasing and decreasing respectively.

Research on Vertical SEC Centrifugal Pump Multi-Fault Diagnosis Based on WPT–SVM

To diagnose common failures in vertical Essential Service Water Pumps (SEC), a method combining the wavelet packet transform (WPT) and the support vector machine (SVM) was adopted. This allowed us to construct a diagnostic model capable of classifying multiple states, including the six types of faults and normal conditions in SEC pumps. The diagnostic model utilized the wavelet packet coefficients to capture sub-bands with a higher energy share and reconstruct the signals. The model inputs the 12 frequency features into the support vector machine to analyze the vibration signals gathered from the SEC pump benchmark. The study illustrates that the proposed method can accurately differentiate between various fault conditions when compared to the WPT method, combined with the artificial neural network (ANN) approach. It attains a superior overall precision of up to 94%, and it displays excellent generalization and strong adaptability.

Irrigation Salinity Affects Water Infiltration and Hydraulic Parameters of Red Soil

Unconventional water resources (e.g., saline water, etc.) for irrigation as a promising supplementary water source can alleviate the freshwater shortage in the agriculture of red soil areas in Southern China. It should be noted that the presence of soluble salt in this water source may have detrimental influences on soil water infiltration and crop growth. Understanding the effect of unconventional water irrigation (UWI) on water infiltration in red soil is important. Previous studies have shown that the salinity of UWI can alter soil hydraulic properties to change soil water movement in saline soils. However, the underlying mechanism and factors of water infiltration in red soil under UWI with different salinity levels remain limited. Therefore, a laboratory experiment (one-dimensional vertical infiltration experiment and centrifuge method) was conducted to evaluate the effect of UWI with different salinity levels [0 (the distilled water, CK), 1 (S1), 2 (S2), 3 (S3), 5 (S5), and 10 (S10) g L−1] on the soil water infiltration process, soil water characteristic curve (SWCC), soil water constants estimated using the SWCC, saturated and unsaturated hydraulic conductivity (KS and K) as well as the soil chemistry of soil profile [pH, electrical conductivity (EC), and Na+ and Cl− contents]. The primary factors of soil water infiltration were identified using stepwise regression and path analysis methods. The results showed that UWI salinity decreased water infiltration by 1.53–7.99% at the end of infiltration in red soil, following the order of CK > S1 > S5 > S2 > S3 > S10. Moreover, UWI could enhance soil water availability with an increase of 8.55–12.68% in available water capacity. In contrast, lower KS and K were observed in S1–S10, and there was a negative linear relationship between irrigation salinity and KS. UWI also produced the EC, Na+, and Cl− accumulations in the soil profile. As the salinity level of UWI increased, the accumulations aggravated. Soil acidification was found in S1–S5, while soil alkalization was observed in S10. Additionally, α, PWP, and KS were the primary factors influencing the water infiltration of red soil. This study can help optimize the soil infiltration model under UWI and establish a foundation for unconventional water management in the red soil regions of Southern China and other similar regions. In addition, the undisturbed red soil under agricultural unconventional water irrigation and the long-term effect of unconventional water application should be considered.

Microstructure and Mechanical Properties of the Interface of Aluminum-Brass Bimetals Produced via Vertical Centrifugal Casting (VCC)

Microstructure and Mechanical Properties of the Interface of Aluminum-Brass Bimetals Produced via Vertical Centrifugal Casting (VCC)

Monitoring and Analysis of the Operation Performance of Vertical Centrifugal Variable Frequency Pump in Water Supply System

The stable operation of a variable frequency pump is of great importance to the management of a water supply project. Analyzing the operation performance based on monitoring data is necessary for maintaining the stable operation of a variable frequency pump. Several sensors are installed at six monitoring points on the pump to collect signals including vibration velocity, vibration acceleration and vibration displacement. Monitoring signals are preprocessed by smoothing, adjusting waveform trend and filtering on the basis of Fast Fourier Transform (FFT). Then, the vibration features are extracted by power spectrum analysis and cepstrum analysis methods. According to the extracted features, the vibration law and actual operation performance of a variable frequency pump under different operating conditions are analyzed. Results indicate that the vibration amplitude of the pump varies sharply under the operating conditions of [15 Hz, 20 Hz] and [30 Hz, 35 Hz]. The operating condition of [0 Hz, 15 Hz] is the restricted operating area of the pump. The vibration and noise continue increasing under the operating conditions of [35 Hz, 50 Hz] and reach the maximum values at 50 Hz. Therefore, the optimal operating is within the range of [20 Hz, 30 Hz]. Finally, by analyzing the critical values of the operating conditions, the fault diagnosis and the evaluation of the operating status are conducted.

Numerical Simulation and Analysis of a Vertical Centrifuge

In order to solve the separation efficiency problem of the vertical centrifuge. First, understand the working principle and dynamic theory of the centrifuge, preliminarily design the technical parameters from the experience and experimental data of the prototype, solid works model, specify the overall structure scheme, and complete the virtual assembly. Secondly, the work performance is verified. The production capacity is calculated with power to meet the design requirements. Then, to verify the design strength and deformation meet the design requirements. Then, the finite element numerical analysis of the internal flow field. The FLUENT software is used to analyze the internal flow field velocity distribution and the turbulent kinetic energy of the centrifuge. Finally, a solid phase distribution rule analysis was performed to investigate the effect of particle diameter size on the separation performance at a suitable particle volume fraction.

Research on Multi-Fault Identification of Marine Vertical Centrifugal Pump Based on Multi-Domain Characteristic Parameters

The marine vertical centrifugal pump is an important piece of auxiliary equipment for ships. Due to the complex operating conditions of marine equipment and the frequent swaying of the hull, typical pump failures such as rotor misalignment, rotor unbalance and mechanical loosening occur frequently, which seriously affect the service life of the marine vertical centrifugal pump. Based on multi-domain characteristic parameters, a fault identification method combining weighted kernel principal component analysis (WKPCA) and particle swarm optimization support vector machine (PSO-SVM) is proposed in this paper. It can effectively solve the problem of multi-fault classification of the centrifugal pump and provide reference for efficient maintenance of equipment. Firstly, a vertical centrifugal pump test bench is set up to simulate typical faults. The collected original fault data are denoised by Kalman filtering. Then, a multi-domain feature set composed of 20 feature parameters was constructed. However, due to high dimension, data redundancy and calculation time were increased. After dimensionality reduction, a fault feature set with 9 feature indexes was established by combining with the WKPCA method. Finally, the PSO-SVM model is used to realize multi-fault identification, and the recognition results of the traditional support vector machine and the genetic algorithm support vector machine (GA-SVM) are compared to verify the diagnosis results and classification performance of PSO-SVM. The results show that the accuracy of WKPCA and PSO-SVM fault recognition methods based on multi-domain characteristic parameters is 1, and it has good convergence.

Systematic review of platelet-rich fibrin (PRF) centrifugation protocols in oral and maxillofacial surgery and the introduction of AR2T3: an easy to remember acronym to correctly report vertical and horizontal PRF centrifugation

Systematic review of platelet-rich fibrin (PRF) centrifugation protocols in oral and maxillofacial surgery and the introduction of AR 2 T 3 : an easy to remember acronym to correctly report vertical and horizontal PRF centrifugation

Assessment of the prediction of ground motion parameters in 1D ground response analysis using data from seismic arrays and centrifuge experiments

Peak ground acceleration (PGA), peak ground velocity (PGV), and spectral acceleration are among the most widely used metrics to represent seismic hazard characteristics in practice. Several simplified seismic design procedures to evaluate liquefaction triggering, slope stability, or structural response have also proposed other ground motion parameters (GMPs) to represent a ground motion’s intensity, duration, and frequency content. To account for soil effects, these parameters can be obtained from the results of one-dimensional (1D) ground response analyses. Few studies have systematically evaluated the prediction of these additional parameters from the results of ground response analyses. This study presents an exhaustive review of the accuracy and precision of the prediction of 19 common GMPs from the results of 1D ground response analyses using vertical seismic arrays and centrifuge tests. Total stress nonlinear analyses are conducted using the software DEEPSOIL along with equivalent-linear analysis. A reference dataset composed of 10 sites and 306 ground motion recordings representing varying conditions of seismic excitation is employed. The findings of this study showed that while the models produced a reasonable approximation of spectral accelerations, a general tendency toward the over-prediction of most parameters was revealed. The results identified that the mean period ( Tm) yielded the lowest bias, and other parameters, such as the predominant spectral period ( To), PGA, and PGV, also offered some improvements over the other parameters included in this study.

Study on Wear Mechanism of Bell-shaped cover of Vertical Scraper Centrifuge

Based on the basic structure and working principle of vertical scraper discharge centrifuge and combined with the actual use, this paper puts forward the main influencing factors of bell-shaped cover wear, studies the wear characteristics of materials on bell-shaped cover, analyzes its wear mechanism, and determines the easily worn parts. Taking the bell-shaped bell-shaped cover of the LLL1200 vertical scraper discharge centrifuge as the research object, the speed and angle of materials eroding the bell-shaped cover at each position are calculated through the analysis of the movement track and force of solid materials in the centrifuge. The erosion and wear speed of materials on the outer end of the rib plate side is the maximum, 23.06 m/s, the speed on the inner wall of the coal retaining ring is slightly lower, 13.87 m/s, and the speed on the upper surface of the rib plate is the minimum, 0.53~ 0.69 m/s. In addition, two methods to prolong the service life of the bell-shaped cover are proposed. The industrial application shows that inlaying alumina wear-resistant ceramics on the bell-shaped cover is the most effective and simple method.

Comparative Analysis of Horizontal Vibrating Centrifuge and Vertical Scraper Centrifuge

Horizontal vibrating centrifuge and vertical scraper centrifuge are the main equipment for the dehydration of the final coal in the coal preparation plant. They are widely used. There are many misunderstandings in the actual selection of centrifuges, which brings unnecessary problems to the later use. In view of how to reasonably select the two kinds of equipment and improve the actual use effect of the centrifuges, the structural composition, working principle and later maintenance cost of the two centrifuges are compared and analyzed, to provide reference and guidance for the effective utilization, cost saving and use effect improvement of centrifuges, so as to improve economic and social benefits.

Effect of centrifugal force (G) on stability of natural emulsions (water/oil) present in fresh virgin olive oils

Fresh virgin olive oils (VOOs) just obtained has a cloudy appearance, due to the presence of emulsified water and solid dispersed particles. The stability of these emulsions mainly depends on the water droplet size distribution and the presence of natural emulsifying agents in the oils. In this work, the effect of centrifugation force and time on fresh unfiltered VOOs from the horizontal decanter centrifuge (HDC) and vertical centrifuge separator (VCS) has been studied. The turbidity, moisture, insoluble impurities and phenol content of the oils were analyzed. The increasing of centrifugation force and time decrease the parameters studied of the unfiltered VOOs studied. The VCS oils showed a higher stability of the emulsion, since presented slightly higher values of the parameters studied after application the different centrifugation treatments. Fresh VOOs obtained in the mills can be considered metastable natural emulsions difficult to break with the current centrifugation systems of the olive extraction process.

Investigation of the Effectiveness of a Vertical Centrifugation System Coupled with an Inert Gas Dosing Device to Produce Extra Virgin Olive Oil

Recent decades have seen the development of many effective and innovative technologies for extra virgin olive oil (EVOO) extraction. Various solutions have been proposed to remove dissolved oxygen from the oil. Given these issues, we have designed and developed a system that can be added to the centrifuges that are already used in the olive oil industry. The system reduces the oxidative impact through the release of a technical gas inside the separator, and consequently delays the onset of defects related to oxidation. The experiment tested different N2 flow rates, directly into the vertical centrifuge, and four levels of N2 were tested–a control level (no N2 injection); low (20 L/min), medium (40 L/min), and maximum (80 L/min)–in order to evaluate the effectiveness of this new technique on EVOO quality. This experiment demonstrates that the objectives have been achieved. The EVOO produced using our system had lower dissolved oxygen content with N2 injection, along with an enriched volatile fraction, and higher biophenol concentrations. The chemical analyses were confirmed by a sensory analysis, with an increase in fruity intensity and bitter taste.

Optimization design and unsteady flow analysis of stall characteristics in a vertical centrifugal pump

Abstract In this paper, an optimization design of the vertical centrifugal pump with vaned diffuser was accomplished, and analyzed the internal flow pattern of the model before and after optimization under stall conditions to explore the relationship between design parameters and the stall characteristics. The reasons for the improvement of efficiency and hump characteristics curve after optimization were revealed combined with streamline distributions, entropy production theory and pressure fluctuation. The results show that the error between the external characteristic result calculated by Computational Fluid Dynamics (CFD) and the experimental value is less than 5%, which proves the reliability of the numerical simulation method adopted in this paper. The hydraulic efficiency under multiple operating conditions and stall characteristics of the optimized model have been significantly improved. After optimization, the entropy production rate in the vaned diffuser is greatly reduced, and the improvement of the internal flow pattern in the vaned diffuser is the main reason for slowing down the hump characteristic curve. The hydraulic performance and the stall characteristics of the vertical centrifugal pump can be significantly improved by properly increasing the radial distance of the vaneless region. The matching relationship between the vaned diffuser and the impeller is one of the important factors that affect the stall characteristics. The large-scale vortices in the vaned diffuser is the main reason for the low-frequency pressure fluctuation signal when operating in the hump region. The low-frequency signal in the vaned diffuser of the optimized model is obviously weakened.

Water Addition During Oil Extraction Affects on Virgin Olive Oil Ethanol Content, Quality and Composition

AbstractEthanol is the alcoholic precursor of fatty acid ethyl esters (FAEEs) in virgin olive oil (VOO). Because of its miscibility, water addition during oil extraction may affect oil ethanol content and then, the FAEEs synthesis during oil storage. In this work, the effect of water addition on VOO ethanol content and composition is studied. Water addition at two extraction systems (two and three phases) is compared and for vertical centrifuge, water addition at different temperatures is assayed. Ethanol content, quality parameters, and healthy components are determined in the oils. Results indicate three phase system gives oils with a 25% lower ethanol content than two phases. Ethanol reduction because of water addition is more important for three phases system (≈14%). For vertical centrifugation, ethanol is lowered as water dose and temperature increase. In general, water addition for any of the extraction steps analyzed reduces the oil ethanol concentration but other aspects such as fruity intensity and phenol content are also lowered.Practical applications: Virgin olive oil final ethanol content, and then its FAEEs concentration, does not only depend on the health and conservation status of olives, but also on the extraction system used and the amount of water added to the extraction process. The knowledge of the impact on ethanol content of water addition during oil extraction can be useful for olive oil legislators in order to keep the approved limits of FAEEs or to modify them. For oil producers, results can help to reduce the oil ethanol content and then FAEEs synthesis during virgin olive oil storage.

Pumping Contribution to Dissolved Oxygen in Virgin Olive Oil During Processing

The overall quality of extra virgin olive oil (EVOO) strictly relates to the evolution of its oxidative state, which in turn depends on the amount of the oxygen availability during the product life, starting with the olive fruit milling. The issue of oil oxygenation during processing has been poorly studied. The few available literature assesses the relative contribution of three main processing steps (paste malaxation, decanter centrifugation, and vertical centrifugation) to the final dissolved oxygen concentration and the consequences on the oil quality decay during storage. Nevertheless, until now information about the contribution of the devices used to moves materials during processing, i.e. screw conveyor and pumps to move olive, olive paste and oil, to the amount of dissolved oxygen and in broader terms on the oil quality, are lacking. It can be reasonably assumed that the intact drupes handling during leaf-removal and washing before crushing, had a negligible effect on the final oil dissolved oxygen content, whereas from crusher to the decanter centrifuge by the malaxer, where olive paste handling occurs, a noticeable effect on the future oil characteristics could occur. The standard and widespread device used to move olive paste during processing, essentially from the crusher to the malaxer and from the malaxer to the decanter centrifuge, is the progressive cavity pump, commonly named mono-pump. Notices of other pumping devices used or proved in EVOO mills are missing. In the present work a peristaltic pump (roller pump) has been tested in comparison to the conventional mono-pump in a continuous centrifugal extraction plant. Specifically, the two pumps were alternatively used to feed the decanter centrifuge by empting the malaxation chambers. The oxygenation effect was assessed in terms of dissolved oxygen amount (DOA) in the produced EVOO, which were also compared for the main qualitative traits such as commercial parameters, phenolic and volatile profiles and phthalates occurrence being the peristaltic pump equipped with a phthalates-free tube. Basically, the qualitative effect of the two pumps significantly differs for the DOA with about 10% saving for the peristaltic pump. The latter also gives significantly (p

Effects of Lean Mode of Blade Trailing Edge on Pressure Fluctuation Characteristics of a Vertical Centrifugal Pump With Vaned Diffuser

Abstract A vertical centrifugal pump with a vaned diffuser is very attractive in the field of long-distance water supply. Excessive pressure fluctuations in the vaneless region due to rotor–stator interaction (RSI) need careful evaluation. In the present investigation, the hydraulic performance and pressure fluctuation characteristics of a vertical centrifugal pump with three different lean modes of the blade trailing edge were quantitatively analyzed by comparison experiments, using the same test rig. Results showed that the pressure fluctuation level was the highest in the vaneless region, closest to the volute tongue, and increased as the flow rate deviated from the design flow rate. The lean mode of the blade trailing edge was found to have a slight influence on hydraulic performance, and the relative deviation of experimental specific speeds with three different lean modes was within 6%. The influence of the lean mode of the blade trailing edge on the pressure fluctuation level was experimentally verified for the first time. In particular, the flow rate-averaged peak-to-peak value of pressure fluctuation with the positive lean mode (PLM) was 62% of the corresponding value with the zero lean mode (ZLM), while no significant improvement was observed for the negative lean mode (NLM). The flow mechanism behind this may be explained as a weakening of the jet-wake flow pattern with PLM.

Processing factors that affect the balance of alcohols and alkyl esters during ‘Arbequina’ olive oil production: Separation and clarification steps

The aim of this study was to assess how different conditions used on the centrifugation step during olive oil extraction affect its quality by considering the balance of fatty acid alkyl esters (FAAEs) and their precursor alcohols. All the experiments were carried out under real working conditions in a two-phase decanter followed by a vertical centrifuge (VC) and different water injection doses and paste injection rates were tested. The fruits used were from ‘Arbequina’ variety at two different maturity stages and the balances of alcohols and FAAEs were measured at the outlets of both, decanter and VC, with respect to the system inlet.Results show that the paste injection rate affects the content of alcohols and FAAEs in the final oil, which tend to increase when working closer to the maximum capacity of the decanter. Different behaviors have been detected when dealing with unripe or ripe fruits. Similarly, the water addition doses have different effects on the FAAEs and alcohols formation depending on the maturity status. Therefore, both the decanter and the step decanter to vertical centrifuge are key points that, when properly controlled, allow minimizing FAAEs formation, which is essential for obtaining quality oils.