Cyclone Performance Research Articles

Optimization prediction and experimental verification of cyclone performance based on BP neural network

As a kind of centrifugal separation equipment, hydrocyclone has developed rapidly with the advantages of high economic benefits, good compactness, high processing efficiency, simple process and so on. Hydrocyclone has broad practical significance and application prospects in chemical, light industry, oil mining and refining, environmental protection, medicine, food processing, ship transportation and surface oil spill treatment. BP neural networks are mainly used in the following four aspects: function approximation, pattern recognition, classification, and data compression. In this paper, we introduce the principle of BP neural network, establish an analytical model, apply BP neural network to predict the performance of hydrocyclone, and conduct experimental verification to optimize the hydrocyclone under different working conditions according to the experimental results.

Influences of magnetic field on the removal of submicron particles in electrostatic cyclone at different temperatures

Aiming at improving the capture performance of inner vortex electrostatic cyclone (ESC), which is widely used in the field of flue gas purification, magnetic field is introduced to remove submicron particles. The theoretical and physical models of electromagnetic dust removal were established, and the dust-removal efficiency of submicron particles under different temperatures and magnetic fields was numerically simulated by FLUENT. The results show that a rise in temperature leads to a reduction in the grade efficiency of submicron particles of ESC, a decrease in the number of escaped particles at lower temperature, and the differences of the rising amplitude in overall efficiency corresponding to the traditional cyclone, which were 36.7%, 34.8%, 33.8%, and 31.9% at four temperatures. The contribution of temperature to the capture of submicron particles decreases continuously with the increasing temperature, but that of magnetic field progressively increases at this time. The magnetic field environment is conducive to the capture of submicron particles, the removal effect is more obvious with the increase of magnetic flux density, but the ascended ranges of magnetic field and temperature both decrease when it reaches 0.5 T. These results can provide a theoretical basis and a technical reference for the design of ESC.

Double-Eccentric Design for the Vortex Finder of a Cyclone Separator

In the present study, a double-eccentric design for the vortex finder of a cyclone separator was proposed to enhance the cyclone performance. Using the numerical approaches, the flow field inside the cyclone was simulated and the cyclone performance was evaluated. The orthogonal method was adopted to obtain the optimal structure of the double-eccentric vortex finder. The range analysis of the five key geometric factors in the double-eccentric design was also conducted. It was found that cyclone performance is more sensitive to the eccentricity of the vortex finder than the other factors. The best eccentric angle of the inlet of the vortex finder is 270°, which markedly improves the separation efficiency and slightly increases the pressure drop. The simulated flow field depicted that the double-eccentric vortex finder results in the strongest swirling flow in the middle and lower parts of the cyclone compared with the vortex finders of the original, non-eccentric, and single-eccentric designs. The results also reflected that off-centering the vortex finder has the most significant impact on the flow patterns. Moreover, an industrial test was carried out in a circulating fluidized bed boiler for this novel vortex finder. The fly ash of the double-eccentric vortex finder becomes finer and contains less carbon content than that of the original one, which indicates that the double-eccentric vortex finder successfully enhances the separation performance.

Multi-objective optimization of a novel vortex finder for performance improvement of cyclone separator

This study proposed a multi-objective optimization of novel vortex finder, called Slotted Vortex Finder (SVF), applied in the Stairmand cyclone separator, to obtain a most appropriate geometric configuration for performance improvement as the Stairmand cyclone separator had been widely used in industry for dust removal since last century. The Optimal Latin Hypercube Sampling (OLHS) method was utilized to conduct design of experiment for four significant design variables, including slot number (Ls), slot length (N), span angle (α) and inclination angle (β). Computational Fluid Dynamics (CFD) and Response Surface Model (RSM) were adopted to get precise output response and construct accurate fitness functions between design variables and objectives. Multi-objective Genetic algorithm was employed to find out the best solution with maximum collection efficiency and minimum Euler number based on the well-constructed fitness functions. The finally selected optimal model provided Euler number reduction of 34.51%, collection efficiency increasing of 4.32% and cut off size reduction of 5.53%, compared with original model. The obtained optimal geometry shape of novel vortex finder could be used as an effective reference for industrial factories to gain enough considerable cyclone performance improvement and high economic benefits by making only small modifications on the in-using cyclone separator. • A novel and efficient structure of slotted vortex finder was demonstrated and discussed. • Surrogate model was utilized to evaluate the effect of geometric design variables. • Multi-objective optimization of slotted vortex finder was conducted. • The optimal solution of slotted vortex finder is meaningful and promising for industrial application.

Siklon Ayırıcılarda Dalma Boru Çapının Siklon Performansına Etkisinin Deneysel Olarak İncelenmesi

Cyclone separators are used in the process of separating the solid from the gas by forming a vortex with the gas stream. Cyclones are located in facilities such as iron and steel, cement, construction. According to their entry shape, cyclones are tangential, axial and snail shaped, and the ones with the most use are tangential entry cyclones. Cyclones have a tangential inlet to form vortexes, an axial clean gas outlet and a conical structure for particle evacuation. The fact that cyclones have a simple structure that can withstand high temperature and high pressure is seen as an economic advantage. According to the parameters affecting cyclone performance, dust collection efficiency and pressure loss have an important place. Factors affecting pressure loss according to these parameters; cyclone entry cross-section, plunge pipe diameter and friction in the inner wall. In addition, the size of solid particles in the gas is less than 5μm, which adversely affects the dust retention efficiency. In this study, dust retention efficiency and pressure loss were examined by changing the plunge pipe diameter of the cyclone. According to the design modeling of the cyclone, 3 different plunge pipe diameters were selected and the dimensions of the subduction pipe diameter; Ø88.9 mm, Ø114,3 and Ø139.7mm. According to the data obtained, three different flow analyzes were performed in the Solidworks Flow Simulation program. In addition, experimental studies were conducted and the results were compared. As a result of the experimental study, Ø114.3 mm provided the best dust collection efficiency according to three different plunge pipe diameters.

Effects of the inlet duct length on the performance of a dense medium cyclone: An experimental and numerical study

The effects of the inlet duct length on the performance of the dense medium cyclones were investigated in this study. The pressure drops and separation efficiencies of the dense medium cyclones with different inlet duct lengths were measured in a cold test rig. A numerical simulation using the four-way coupling method was also conducted to estimate the flow field inside the dense medium cyclone. The experimental results show that a longer inlet duct length results in a lower static pressure drop. The overall separation efficiency first increases and then keeps almost unchanged as the inlet duct becomes longer. The simulated results show that the energy loss decreases as the inlet duct length increases. The changing trends of the static and total pressure drops with the inlet duct length are similar. According to the simulated flow fields, lengthening the inlet gas reduces tangential velocity near the vortex finder and therefore reduces the gas swirling loss. The inlet duct length affects the separation performance mainly by affecting the swirling particle roof. A longer inlet duct leads to fewer particles moving in the swirling particle roof in the dense medium cyclone, which accounts for a better separation efficiency. It was also found that the conventional one-way coupling method fails to qualitatively analyze the effects of inlet duct length on the separation performance of the dense medium cyclone.

Effect of inlet volute wrap angle on the flow field and performance of double inlet gas cyclones

In response to the divergent understanding of double inlet cyclone performance in the literature, the effect of inlet volute wrap angle on the performance and flow field of double inlet cyclone separator was studied by Computational Fluid Dynamic (CFD) method. The results showed that the inlet volute wrap angle can affect the comparison results of the single and double inlet gas cyclones with the same total inlet cross-sectional area and velocity. 0° and 90° volute double inlet improved the efficiency mainly by separating particles below 10 μm, while 180° volute double inlet had no separation advantage for any particles, so the symmetrical double inlet does not always improve the efficiency, and the appropriate inlet volute wrap angle should be selected according to the actual situation, otherwise, the expected performance requirements of the symmetrical double inlet cyclone cannot be achieved. Compared with the flow field, it is found that the inlet volute wrap angle changed the tangential velocity of the symmetrical double inlet cyclone separator, thus changing the performance.

On the performance of cyclone separators with different shapes of the conical section using CFD

The present work evaluates the effect of various geometrical shapes of the conical segment on cyclone performance. For this, five different shapes of the cone walls viz. a straight profile, concave profile, convex profile, followed by hybrid concave-convex as well as convex-concave profiles, are analysed. The performance of all the models is predicted using the Reynolds stress model considering two pressure-strain options viz. the linear pressure-strain and the stress-omega models – the latter very well captures the mean velocity field, coherent fluctuations, and the precessing frequency of the vortex core. The different profiles of the conical segment were found to affect pressure drop more than the collection efficiency. Conclusive results indicate that the performance of the convex variant – particularly at high flow rates – outperforms the baseline model and other variants and could be preferred over the conventional design. The concave variant experiences the highest pressure drop with enhanced collection efficiency.

CFD Investigations of Cyclone Separators with Different Cone Heights and Shapes

Due to the great achievements in the field of optimization of the design of cyclone separators, non-standard solutions are sought to increase their performance. Therefore, in this study, we consider the impact of different cone and cylinder height variants on the performance of cyclone separators. Additionally, we propose non-standard shapes for these sections. Three different heights: H/D = 0.5, 1.0, and 1.5, with D (the main cyclone body diameter), are analyzed. Since the cone is one of the most important geometrical entities, three different shapes viz. a straight (conventional) profile, a concave profile as well as a convex profile are also taken into account. Cyclone performance is rated at three different inlet velocities viz. Uin = 10 m/s, 15 m/s, and 20 m/s. Hence, a total of 27 simulations have been performed using the Reynolds stress model. It becomes apparent from the present study that the pressure loss is lowest in the convex variant, whereas the separation efficiency is better in the conventional design. Furthermore, an increase in the length of the cylindrical section reduces pressure drop with a mild decrease in the collection efficiency in all variants.

Studies on the cyclone dipleg flow characteristics in a CFB for designing 3 MWth scale chemical looping combustor

3 MWth scale chemical looping combustion (CLC) system using circulating fluidized bed (CFB) is being developed as a liquidized natural gas power generation technology to reduce CO2 emissions. Dipleg, considered a blood vessel of CFB, conveys solids captured by cyclone to the fluidized bed while preventing gas mixing. This vertical passage plays key role in solids circulation and cyclone performance in thousands of CFB systems, yet only a limited information is available on its design and operation. This study experimentally investigated the flow characteristics in dipleg to verify design and operating conditions for smooth solid flow while predicting the amount of gas mixing. When solid circulation rate increased, both upward and downward gas flowrates in dipleg increased. It was found that the sum of two flowrates were equal to the volumetric flowrate of solids in the dipleg. Unstable operation occurred when 1) the gas-solid relative velocity in the dipleg became higher than the minimum slugging velocity, and 2) bubble diameter in bubbling bed became larger than the dipleg diameter. Finally, models for operation range and the amount of gas mixing in dipleg were proposed, and the design and operation range of the dipleg in 3 MWth scale CLC was suggested.

Vortex characteristics of a gas cyclone determined with different vortex identification methods

This paper characterizes the vortex flow field in a gas cyclone based on different vortex identification methods, including vorticity method, Q criterion, λ2 criterion, Ω method and Liutex method. Analysis and comparison of isosurfaces of different vortex identification methods indicate that except vorticity method, the vortex core, the eddy flow and the short-circuit flow can be identified directly by other methods. But the small scale vortices, such as top ash ring, can only be fully recognized by Liutex method. The contours demonstrate that the magnitude of five vortex parameters is the largest in the vortex core, followed by the short-circuit flow, and the eddy flow is the smallest. But only Liutex method can predict the vortex core center and identify the most severe vortex eccentricity is in the bottom of vortex finder, the lower part of the cone and the hopper. The work not only improves the understanding of the vortex structure in a gas cyclone, which can critically affects cyclone performance, but also reveals the differences in the commonly used vortex characterization methods.

Multi-objective optimization of cyclone separators using mathematical modelling and large-eddy simulation for a fixed total height condition

The present study aims at enhancing the cyclone performance by optimizing its geometry while keeping the total height constant. We consider three different cases of optimization with five geometrical entities as common to all cases viz. main body of cyclone, vortex finder diameter and its insertion length, the height of conical segment and cone tip diameter. The way the inlet area is treated classifies the present study in three cases – in the first case (referred to as Case A) the inlet dimensions are not subjected to optimization; in the second case (referred to as Case B), the inlet dimensions are subjected to optimization while retaining the original area magnitude; and in the third case (referred to as Case C), the inlet is subjected to optimization without restrictions on area magnitude. Owing to several geometrical parameters considered for optimization, we use the Muschelknautz method of modelling (MM) – a popular mathematical model – as a metamodel to genetic algorithms (GAs) for optimization. Few selected Pareto front points have been numerically investigated and the performance comparison elucidates a significant improvement over the baseline model. Conclusive results indicate more than a 40% reduction in the pressure drop values over the standard model followed by an improvement in the collection efficiency. Hence, the optimized datasets would provide the new guidelines to designers and would facilitate making selections based upon the relevance.

Performance characteristics of a small scale cyclone separator operated in different flow regimes

The flow pattern, cyclone pressure drop and particle penetration through a sampling cyclone have been studied at a wide range of flow rate 0.22–7.54 LPM using the LES simulations that have been validated based on experimental penetration data. The cyclone performance has been described by three dimensionless characteristics, the Euler number Euoutstat, cut-size ψ50 and slope of the transformed penetration curve κ1. Three main flow regimes and four sub-regimes have been revealed. The effects of the flow rate (Reynolds number) on the dimensionless cyclone performance characteristics have been described and a one-term power series model has been proposed. Additionally, the effect of the aspiration efficiency on the cyclone cut-size has been determined.

Innovation of vortex finder geometry (tapered in-cylinder out) and additional cooling of body cyclone on velocity flow field, performance, and heat transfer of cyclone separator

This paper studies numerical analysis about the effect of the vortex finder (Tapered in-Cylinder out) geometric innovation in a cyclone separator. Four variations of the length of the vortex finder 0.5 Dc, 0.75 Dc, Dc, and 1.25 Dc will be simulated under cooling and without cooling conditions on the velocity flow field, cyclone performance, temperature distribution, and heat transfer. The RSM turbulence model is used to simulate fluid flow. The Eulerian-Lagrangian approach was chosen to predict the phase movement of the particles. The trajectories of particles in the flow are tracked individually using the DPM method. The cooling model is applied assuming a constant temperature on the surface of the cyclone body. The simulation results show similar trends both with experimental studies and numerical simulations. The application of additional cooling to the cyclone, reduced the pressure drop up to 13%. The cyclone collection efficiency showed a non-significant increase but most of the particles collected were drier due to the increasing heat transfer 15–25% in any cases of variation.

Coarse-grain DEM-CFD modelling of dense particle flow in Gas–Solid cyclone

Design, scale-up and operation of cyclone gas–solid separators are mostly based on simplified models and experience. Previous single-phase or one-way coupled simulations are not applicable to cyclones operating with relatively big particles and under high loadings, as used for example in circulating fluidized beds for the polymer and energy industry. Simulations based on the DEM-CFD allow for four-way coupled dense flow, including dissipation, friction, and rotational particle motions. However, the computational cost becomes easily prohibitive. Coarse-graining methods based on lumping smaller particles into parcels or grains have been recently proposed to reduce the number of elements and increase the time-step. Yet, much remains to be characterized in terms of accuracy vs. speed-up. In the present work, a coarse-grain DEM-CFD approach to simulate the two-phase flow in a Stairmand high-efficiency cyclone at gas velocities in the range 10–20 m/s and solid loading in the range 0.1% to 0.5%vol is investigated. In particular, the focus is on the effect that the coarse graining degree (up to 64 particles per coarse grain) exerts on the replicability of the results compared to pure DEM-CFD simulations. It is shown that the macroscopic quantities characterizing the cyclone performances, such as pressure drop, inner vortex length and collection efficiency, are generally maintained even with coarse graining degree up to 64, with an approximation that improves with the increase in the solids loading. However, detailed features of the gas and solids flow (e.g. strand formation) appear significantly affected by the coarse graining degree, already at coarse graining degree 8 and 27.

The effect of height variations on cyclone performance under fluctuating boundary conditions

This study has been investigated the effect of the height variation of the cyclone components under the non-uniform flow. Oscillating flow is an approach to consider the real flow condition in the use of cyclones as an inlet air filter for the internal combustion engine. Accordingly, an oscillating flow with an inlet velocity of 15 (m/s) along with a range of pressure based on the motor inlet is applied to the cyclone’s dirty and clean outlets. Seven cyclone models including a base model, and models with height change in vortex finder, cylinder, and cone have been created and gridded. The numerical solution has been run using the Large Eddy Simulation and the Eulerian–Lagrangian model. Having validated, the flow field and cyclone performance have been considered. The results indicate that under the non-uniform flow, a decrease in the vortex finder height and an increase in the height of the cyclone’s cylinder and cone minimize the pressure drop. Applying oscillations along with the 30% change in the vortex finder height increases vortices power in the cone, cylinder, and vortex finder zones by 4.23, 8.99, and 21.42 percent, respectively. Additionally, the efficiency dependence on the change in length of cyclone components under the uniform flow is much higher than that of under the non-uniform flow.

Experimental Research of Gaseous Emissions Impact on the Performance of New-Design Cylindrical Multi-Channel Cyclone with Adjustable Half-Rings

Cyclones are widely used for separating particles from gas in energy production objects. The efficiency of conventional centrifugal air cleaning devices ranges from 85 to 90%, but the weakness of many cyclones is the low collection efficiency of particles less than 10 μm in diameter. The novelty of this work is the research of the channel-type treatment device, with few levels adapted for precipitation of fine particulate matter, acting by a centrifugal and filtration principle. Many factors have an impact on cyclone efficiency—humidity, temperature, gas (air) composition, airflow velocity and etc. Many scientists evaluated only the effect of origin and size of PM on cyclone efficiency. The effect of gas (air) composition and temperature, and humidity on the multi-channel cyclone-separator efficiency still demands contributions. Complex theoretical and experimental research on air flow parameters and the efficiency of a cylindrical eight-channel system with adjustable half-rings for removing fine-dispersive particles (<20 μm) was carried out. The impact of air humidity and temperature on air flow, and gaseous smoke components on the removal of wood ashes was analyzed. The dusty gas flow was regulated. During the experiment, the average velocity of the cyclone was 16 m/s, and the temperature was 20–50 °C. The current paper presents experimental research results of wood ash removal in an eight-channel cyclone and theoretical methodology for the calculation of airflow parameters and cyclone effectiveness.

Comparative performance analysis between conventional and square cyclones for solid Particle-Gas Separation: A review

Conventional cylindrical-body cyclone separators have been in use in the industry for a long time due to their many benefits, including simple design and construction, low running costs, no moving parts, and significant particle collection efficiency. Many studies have been done on this cyclone type because of its utility in areas like mining and agriculture. A cyclone with a square body, rather than a cylindrical one, was introduced in the previous three decades. Square cyclones are not well-known in the industrial world yet. Still, they have several advantages over conventional cyclones, including faster construction, quicker integration with boilers, and improved thermal efficiency when used with fluidized bed circulation-type boilers. This research compares the performance of square and conventional cyclones in terms of collecting efficiency and pressure drop. Factors including solid loading ratio, gas entry velocity, gas viscosity, and cyclone shape affect pressure drop and separation efficiency. According to data from published papers, conventional cyclones outperform square cyclones in terms of collection efficiency. However, simulation studies have shown that the pressure drop in a square cyclone is less than that in a cylindrical cyclone. Given that square cyclones are more straightforward to fabricate than conventional cyclones, the findings of this paper open up a lot of room for more research into developing square cyclones that can equal the performance of conventional cyclones.

Development of an Axial Cyclone for High-performance: Application of Cycloid Curve and Multi Objective Optimization

Reducing particulate emission is a key factor in improving the air quality as particulate matter cause respiratory diseases. In this study, an axial cyclone was selected from several existing technologies to reduce particulate emissions owing to its outstanding separation performance and low-pressure drop. To enhance the axial cyclone, the fastest descending curve among the lines that pass through two points was selected; it induces faster momentum changes from the axial to the tangential direction. Therefore, the selected cycloid curve was applied to the vanes and body of the axial cyclone. The particle trajectory was simulated using a discrete phase model (DPM) in ANSYS Fluent ver. 2020 R2. Furthermore, the external structure of the axial cyclone was optimized via multi-objective optimization based on response surface methodology. Additionally, experiments were conducted to evaluate the proposed cyclone performance. Without applying the cycloid curve, the separation efficiency and the pressure drop were 73.6% and 1013.3 Pa, respectively. In the case of the cycloid-applied axial cyclone, however, the separation efficiency and pressure drop were 91.6% and 1109.6 Pa, respectively. Thus, the application of the cycloid curve improved the cyclone performance by approximately 24.5%.

A Comprehensive CFD Assessment of Wheat Flow in Wheat Conveying Cyclone Validation and Performance Analysis by Experimental Data

Cyclone is often used in the Industry due to its low maintenance costs, simple design, and ease of operation. This work presents both experimental and simulation evaluation on the effect of inlet velocity and mass flow rate on the performance of a wheat conveying cyclone. According to the great importance of the pressure drop and separation efficiency on the separation phenomenon in the cyclone, a comprehensive study has been conducted in this regard. A computational fluid dynamics (CFD) simulation was realized using a Reynolds stress turbulence model, and particle-air interactions were modeled using a discrete phase model. The result showed a good agreement between the measured value and CFD simulation on the pressure drop and tangential velocity with a maximum deviation of 6.8%. It was found that the separation efficiency increased with inlet velocity up to 16 m s−1 but decreased slightly at a velocity of 20 m s−1. The pressure drop increased proportionally with inlet velocity. However, optimum performance with the highest separation efficiency (99%) and acceptable pressure drop (416 Pa) was achieved at the inlet velocity of 16 m s−1 and mass flow rate of 0.01 kg s−1.