Performance evaluation of industrial large-scale cyclone separator with novel vortex finder

This paper presents an experimental and numerical study on an industrial large-scale tangential-inlet cyclone separator with a novel and easy-to-implement vortex finder. The vortex finder was designed with slots on the side wall to improve cyclone performance. The collection efficiency, pressure drop, and interior flow field were analyzed. The proposed device provides an effective gas flow pathway and a coupled swirl-inertia separation mechanism, which eliminates short circuit flows under the bottom inlet of the slotted vortex finder to reduce the swirling intensity and minimize the flow instability in the separator. The pressure drop was reduced up to 27.9% compared to the conventional separator and the maximal increase in collection efficiency was 5.45%. The results presented here may provide a workable reference regarding the effects of vortex finders on improving flow fields and corresponding performance in industrial large-scale cyclone separators.     

Effects of helical fins on the performance of a cyclone separator: A numerical study

This study aimed to investigate the separation performance of a cyclone separator after reshaping its cylindrical body by installing the helical triangular fins. A numerical simulation based on Fluent was adopted to perform an orthogonal test to optimise the structure of the cyclone separator with helical triangular fins. Three structural parameters of the helical triangular fins were selected as optimisation variables: base width, fin size, and fin pitch, and their influences on the evaluation indices of the cut-off diameter were investigated. The optimal combination scheme was determined by range analysis, and the cyclone separator performances before and after optimisation were compared and analysed. The significant influence of the structural parameters on the cut-off diameter was in descending order as the fin pitch, fin size, and base width. For particles with diameter of 0.1, 0.5, 1, 2, and 3 μm, the separation efficiency of the cyclone separator with optimized helical triangular fins increased by 7.4 %, 15.9 %, 20.1 %, 10.9 % and 14.8 % respectively. Moreover, the cut-off diameter of the finned cyclone separator is reduced by 30.7 %, while the pressure drop is only increased by 6.6 %. The short circuit flow and back-mixing were alleviated, thereby considerably enhancing the stability of the flow field. Therefore, the finned cyclone separator was found to play a critical role in increasing the separation of fine particulate matter.     

The effect of particle humidity on separation efficiency for an axial cyclone separator

The objective of this study is to investigate the effects of particle humidity on the inlet particle size distribution, overall efficiency, grade efficiency and cut size diameter for an axial cyclone separator with inner diameter of 150?mm. The collection and grade efficiencies of the cyclone separator were measured by on-line method for inlet velocities, particle concentration and particle humidity in the ranges of 12–18?m/s, 30–500?mg/m³ and 8–30‰, respectively. By employing a set of fixed parameters for inlet velocity and particle concentration, the effect of particle humidity on separation efficiency was investigated. The experimental results show that the volume ratio of larger particle increases with the increasing of particle humidity due to particle agglomeration. When the inlet velocity and particle humidity remain constant, the collection and grade efficiencies improve greatly as the increasing of the particle concentration because of the particle aggregation. However, it was noticed that the grade efficiencies did not always increased with the increasing of particle humidity under the same conditions of inlet velocity and particle concentration. The trends of grade efficiency curves for different particle humidity change at the particle diameter of approximately 10?μm. The grade efficiency improves with the increasing of particle humidity when the particle diameter is larger than 10?μm, while a contrary tendency is observed when the particle diameter is smaller than 10?μm.     

Study of inlet temperature effect on single and double inlets cyclone performance

In this paper, a comprehensive study is performed in order to demonstrate the effect of the flow and particle temperature on cyclone performance. Three main characteristics of the low-mass-loading gas-solid cyclone separators, including: pressure drop, particle separation efficiency and natural vortex length are investigated. Eulerian-Lagrangian approach is employed to solve the unsteady Navier-Stokes and energy equations to model the flow of particles. Because of the strong swirling flow in cyclone, Reynolds stress transport model (RSTM) is used to calculate the Reynolds stresses. Numerical simulation is accomplished at a temperature range of 293–700 K and four inlet velocities. Also, a comparison is conducted between two Stairmand high efficiency cyclones with the same dimensions, one with single inlet and the other with double inlets to declare the effect of the second inlet on cyclone performance. The analysis of results shows that the swirling flow becomes weaker for higher temperature cases and thus, flow pressure drop and particle separation efficiency is noticeably decreased. Increasing in temperature causes decrease in natural vortex length. Also, study of natural vortex length is performed for the studied range of temperature.     

Gas-solid separation performance and structure optimization in 3D printed guide vane cyclone separator

Low separation efficiency and large pressure drop are two common problems of cyclones. In this paper, a 3D printed guide vane cyclone separator was designed to study the separation efficiency, turbulent kinetic energy, and particle movement of particle group by experiment and simulation. The results shown that the tangential velocity was the major influence of separating. The bottom of the exhaust pipe was the main region of gas–solid separation and pressure drop. The separation efficiency and pressure drop were positively correlated with the inlet velocity and the particle radius of the fluid. The distribution of turbulent kinetic energy that leaded to the pressure drop loss was concentrated on the inlet of the exhaust pipe. The swirl has external and internal two directions. The optimized cyclone has a longer and narrower blade flow path to obtain higher separation efficiency, especially at low inlet velocity.     

顶灰环对旋风分离器分离特性的影响

针对旋风分离器顶部灰环逃逸现象,采取在升气管根部开孔直接导出顶灰环中颗粒的方法,以探究顸部灰环在环形空间的分布形态及粒径分布特性。实验在升气管圆周的8个位置分别开孔并试验,通过粗粉收率的变化判断顶灰环中颗粒的逃逸量,并分析了细粉中的粒径分布。发现顶灰环中颗粒逃逸的量是由于顶灰环在空间分布不均造成的,而且在空间的粒径含量和分布是一个动态平衡过程。实验数据袁明相对于升气管开孔前的收率下降了0．37％-5．5％,压降下降了20．1％-40％。最大效率可达97．47％,最低压降可达176．4Pa。     

Development and application of a novel swirl cyclone scrubber (2) Theoretical

The swirl cyclone scrubber analyzed in this paper is a novel aerosol filtering device in which a uniflow cyclone and a scrubber are combined. Systematic experiments showed that the swirl scrubber is a promising device that has minimal installation, operational, and maintenance costs. In this article, theoretical analyses are developed for the swirl cyclone scrubber. The dependency of particle collection efficiency on the design and operating parameters observed by experiments is explained using a theoretical parameterization to provide guidelines for optimal design and operation of the device. Discussion on possible variations of the swirl cyclone scrubber is also presented based on the theoretical parameterization developed.     

Influence of inlet angle on flow pattern and performance of gas-liquid cylindrical cyclone separator

Gas-liquid cylindrical cyclone (GLCC) separator is widely used in the petroleum industry with potential field applications. Its performance is strongly influenced by the inlet configuration. The 27° optimal inclined inlet angle has been experimentally observed for GLCC with the same diameter of body and inlet. For other GLCCs, the effect of inlet angle on flow pattern and their performances have not been investigated. The main target of the current study is to deeply understand the changes of flow pattern with respect to different inclined angles and flow conditions. Twelve GLCCs with different inclined angles were numerically investigated by using the Reynold stress turbulence model to predict the flow pattern with GLCC. The distribution of radial, axial, and tangential velocity profiles and their maximum magnitudes with respect to the change of inlet angle were carefully considered in this study.     

Development of a miniature cyclone separator operating at low Reynolds numbers as a pre-separator for portable black carbon monitors

In this study, a cyclone separator that can be used as a sampling inlet for portable black carbon (BC) monitors operating at a flow rate of less than 200 mL/min was developed. A prototype was fabricated to evaluate its performance by experiments, and the cut-off size of the cyclone separator was predicted through numerical analysis by applying various turbulence models. The RNG k–ε model was found to be suitable for the analysis of the cyclone separator operating at Reynolds numbers of less than 1000. Cyclone separators were designed through simulation and fabricated for each operating flow rate (50, 100, 150, and 200 mL/min) of a BC monitor, and their performances were experimentally verified. Meanwhile, when the non-dimensional analysis method of the previous study conducted at Reynolds numbers of 1000 or higher was used, the cyclone separator operating at Reynolds numbers of less than 1000 also exhibited a similar linear tendency.     

Experimental investigation of processes in acoustic cyclone separator

This paper presents air flow velocity profiles obtained in conventional and acoustic cyclone separators. It is shown that vortex air flow is created in acoustical cyclone separator in presence of secondary countercurrent air flow. It is obtained that in acoustic cyclone separator air pressure pulses occur at frequency of 8 kHz and pressure amplitude reaches a value of 170 dB. Separation efficiency of acoustic cyclone separator was established experimentally.     

The effect of magnetic field on the performance of new design cyclone separators

In this paper it is attempted to improve the performance of the gas–solid new design cyclones with imposing magnetic fields. First, Eulerian-Lagrangian method is used to model the flow and to track the solid particles within the new design cyclones. The Reynolds averaged Navier–Stokes equations with Reynolds stress turbulence model (RSM) are solved by use of the finite volume method based on the SIMPLE pressure correction algorithm in the computational domain. The velocity fluctuations are simulated using the Discrete Random Walk (DRW). Then, to investigate the possible influence of the magnetic field, horizontal and vertical distances of the magnetic source from the coordinate origin as influential parameters are investigated. Solid particles with three different diameters and with different materials including polystyrene, ferrous and nickel are used. Results show that applying a magnetic field can improve the collection efficiency for all different particles’ materials. Analysis of results proves that there is a strong correlation between cyclone performances. It is observed that the collection efficiency is very sensitive to vertical distance of the magnetic source from the origin. Moreover, providing higher efficiency without imposing pressure drop is the advantage of implication of a magnetic field.     

Effect of the inlet angle on the performance of a cyclone separator using CFD-DEM

Hydrodynamic characteristics in a cyclone separator are simulated by means of DEM-CFD. Reynolds stress turbulence model (RSM) is used to capture gas turbulence. By changing the inlet angle, the distributions of pressure drop, tangential and axial velocity of gas phase are obtained within the cyclone. Simulated results indicate that the flow pattern consists of two regions: loss-free vortex region and forced vortex region. The negative inlet angle brings about a larger pressure drop comparing to positive inlet angle. The separation efficiency and trajectory of particles from simulation are obtained. The effects of inlet angle and particle size on separation efficiency are quantified. The separation efficiency is increased with an increase of particle size, while the separation efficiency firstly increases and then declined as inlet angle changes from negative to positive. An agreement between the numerical simulation and experimental results has been achieved in a cyclone separator.     

Performance evaluation of a new micro gas cyclone using simulation and experimental studies to capture indoor fine particles

The aim of this study was evaluating a micro gas cyclone performance with a body diameter of 10?mm to collect indoor fine particles. The design of a cyclone requires minimizing the pressure drop and maximizing the separation efficiency. Overall and grade efficiencies, pressure drops, and cut sizes have been investigated through a theoretical model, simulation, and experimental studies. The experimental part was conducted using an Electrical Low-Pressure Impactor (ELPI) device to measure particle concentration for flow rates of 10–13.3 (l/min). In order to study the pressure drop and velocity behavior for different flow rates, COMSOL software was utilized. The obtained results from experimental work have met the theoretical and simulation outcomes adequately. It has been confirmed by all the obtained results that by increasing the flow rate and subsequently inlet velocity, the particle collection efficiency and pressure drop increase while the cut size decreases.     

Numerical study on the performance of swirl tube based on orthogonal design

Here, an axial flow cyclone separator is design is proposed. The effects of varying the structural parameters and operating conditions on pressure drops and separation efficiency were investigated via a numerical simulation approach. The results show that of the three structural parameters considered, the distance between the diffuser and blade is the most significant factor impacting separation performance compared to the blade pitch and blade shaft diameter. Increasing the distance between conical outlet and blade can decrease its pressure drops and increase separation efficiency; while increasing the shaft diameter can increase pressure drops, and the increasing blade pitch can decrease both the pressure drop and the separation efficiency. The pressure drop of the optimized swirl tube was 102.1 Pa, with a corresponding separation efficiency of 95.04% for 100 μm particles at an extraction ratio of 10%. Further, the cut-off particle size can reach 3 μm, demonstrating that the swirl tube offers good separation performance and has the potential to be widely applied in industrial gas–solid separation applications.     

Influences of inlet height and velocity on main performances in the cyclone separator

Aiming at improving collection efficiency in the cyclone separator, the effects of inlet height and velocity on tangential velocity, static pressure and collection efficiency were studied. A three-dimensional model including gas-flow, and particle-dynamics fields was built by the Reynolds stress turbulence model, and the numerical simulation was achieved using the FLUENT software. The static pressure distribution, tangential velocity distribution, and particle trajectory of the cyclone were obtained, and the variation law of the collection efficiency with inlet height and velocity as well as particle diameter was analyzed. Numerical results indicate that both the static pressure and the tangential velocity in the cyclone basically present the axial symmetrical distribution, the static pressure shows a nonlinear increasing trend in the radius direction and the distribution of the tangential velocity is in the shape of a “hump.” The increase of inlet height in a certain range reduces the rotation numbers of particles in the cyclone and shortens the residence time, which results in the improvement of trapping performance. Furthermore, the appropriately increasing inlet velocity in a reasonable range can make the collection efficiency increased.     

Experimental and CFD study on a cyclonic classifier with new flow pattern

Physical principle of conventional top-inlet classifier (CTC) with reverse-flow pattern leads to the heavily fine particles entrainment in coarse fraction. Present work concentrates on the flow-field design for less downward airflow at near-wall region of the classifier. A new middle-inlet classifier (NMC) is proposed and analyzed using computational fluid dynamics (CFD) method and powder classification experiments. The results showed that new flow pattern characterized by a pair of vortexes was created in the new classifier. The upper vortex with 80% of the total air volume moves upward and forms the washing effect at near-wall region, which effectively reduces the fine particles entrainment in coarse fraction. The downer vortex with reverse-flow pattern discharges the coarse particles timely. The radial centrifugal sedimentation combined with the axial counter-current washing effect dominates the particle classification in the NMC. Compared to the CTC, classification accuracy index of the NMC with double-vortex averagely increases by 27% with a pressure drop reduction of more than 38%. This work offers a new principle for high-efficiency particle classification and new strategy for improving the classification performance of turbo air classifiers and hydrocyclones.     

Experimental study on the thermal hydraulic performance of plate-fin heat exchangers for cryogenic applications

Efficient and compact plate-fin heat exchangers are critical for large-scale helium liquefaction/refrigeration systems as they constitute major part in the cold box. This study experimentally explores the heat transfer and pressure drop behaviors of helium gas at low temperature in four types of plate-fin channels, namely offset-strip and perforated fins, with different geometrical parameters. A series of cryogenic experiments at approximately liquid nitrogen temperature are carried out to measure the Colburn j factors and Fanning friction f factors with a wide range of Reynolds number. Besides, to reveal the performance variations under different operating temperatures, comparative experiments respectively conducted at room temperature and liquid nitrogen temperature are implemented. The results show that in comparison with the performance data at room temperature, most of j factors are relatively smaller perhaps because the lower aluminum thermal conductivity and higher Prandtl Number at low temperature. Meanwhile, the f factors corresponding to cryogenic conditions exhibit slightly larger even though the core pressure drops show considerable reductions. In contrast to the calculated results from the frequently-used performance curves (Chen and Shen, 1993), the Root Mean Squared Errors of j and f values are correlated within 8.38% and 6.97% for one perforated fin core, 41.29% and 34.97% for three OSF cores, respectively. For OSFs, further comparisons with the previous empirical correlations from literatures are conducted to verify the accuracy of each correlation. Generally, most of the calculated results predict acceptably within the deviations of ±25% for the j factors, while the predicted results express relatively large deviations for the f factors. Therefore, it may be revealed that most of the existing correlations were not able to accurately predict the experimental data in consideration of the performance differences under realistic cryogenic operating conditions, which could have significant influences during the design process of cryogenic heat exchangers.     

Modification of the cyclone separator geometry for improving the performance using Taguchi and CFD approach

ABSTRACT

The cyclone separator performance has been affected by its high-pressure drop. The main geometric ratios such as outlet diameter, inlet width and inlet height and total height have been preferred to reduce the pressure drop and improve the performance of cyclone separator. These standard geometric values have been altered with the aid of design of experiment technique by Taguchi method for reducing the pressure drop. This changed new design produce low-pressure drop compared with the standard cyclone separator. Moreover, the collection efficiency of the new design is high when compared with standard cyclone separator. The pressure drop, Euler number, cut-off diameter and efficiency of the standard and new cyclone separator have been compared with the results of mathematical and computational fluid dynamics technique (CFD). The Reynolds stress turbulence model and discrete phase model have been used for simulating the cyclone separator in CFD. An acceptable agreement has been obtained between these results.     

Experimental study of fluidization characteristics of Geldart-D particles in pressurized bubbling fluidized bed

The pressurized bubbling fluidized bed shows great advantage in retreating municipal solid waste because it could effectively capture CO₂ and enhance the reaction rate of the process of combustion and gasification. In the present work, fluidization characteristics of Geldart-D particles at elevated pressure were experimentally investigated, such as flow pattern, pressure drop, minimum fluidization gas velocity. At the same fluidization gas velocity, as elevating operating pressure, the fluidization of Geldart-D particles became more intense, the bubbles got larger, the standard deviation and the power density of dominant frequency of the pressure drop signal increased. While, under the same fluidization number, as increasing operating pressure, the fluidization of Geldart-D particles became smoother, the bubble size decreased, both the standard deviation and the power density of dominant frequency of the pressure drop signal decreased. It seems that, under elevated pressure, the fluidization behavior of Geldart-D particles would transition to that of Geldart-B particles. Finally, the minimum fluidization velocity of the Geldart-D particles was found decreased with the increase of the operating pressure. A new correlation for the prediction of the minimum fluidization velocity of Geldart-D particles at elevated pressure was also formulated based on the present experimental results.     

A numerical study on pressure drop and separation efficiency of a new swirl tube cleaner

In this paper, a new design of Swirl Tube Cleaner (STC) was introduced. The performance of an STC in terms of the separation efficiency and pressure drop was numerically investigated for different vane angles, vane lengths, and inlet velocities. The Reynolds stress turbulence model was used to detect the main flow structures of the highly swirling flow inside the STC. The discrete phase model that employs the Lagrangian frame of reference was utilized for particle tracking. The results are in good agreement with experimental data available in the literature. For all cases under investigation, the main flow characteristics of the STC consist of a hub vortex flow downstream of the back cone and tip vortices in the wake flow of the vanes. Around the initiation point of the vortex flow, the centrifugal accelerations are one order of magnitude higher than that of the upstream flow around vanes. The results show that the overall separation efficiency with the specified particle size distribution can reach 88% at a pressure drop lower than 250 [Pa] for the highest flow rate. Compared to traditional STCs, the new STC decreases the pressure drop by about 50% while enhancing overall separation efficiency by approximately 2%, considering the numerical accuracy.