Double Cyclone Research Articles

The effect of inlet velocity, gas temperature and particle size on the performance of double cyclone separator

In this present study, the effect of inlet velocity, gas temperature on pressure drop and the effect of particle size on the collection efficiency under different operating conditions are demonstrated for a double cyclone separator, which mainly consists of a 2D2D and 1D3D cyclone in series arrangement. The experiment of pressure drop measurement for different inlet gas velocities in the range of 11–23 m/sec are conducted and it is observed that the pressure drop increase with an increase in gas velocity, which is also validated with CFD results using RSM model and well-established theoretical models. The numerical simulation is also performed for different gas temperature in the range of 300–1100 K. The prediction shows that the pressure drop decrease gradually with increasing the gas temperature, which also gives a better agreement with empirical correlations. The collection efficiency has been estimated for different particle size in the range of 1–10μmat u = 23 m/sec, by CFD approach. It is noted that the efficiency of single cyclone is very poor for fine particles (<5μm) but adding a 1D3D cyclone in series with a 2D2D cyclone separator, the pressure drop is reduced more and the overall separation efficiency is improved in a comprehensive way.

Experimental and numerical studies on a new double-stage tandem nesting cyclone

This paper proposes a new type of gas cyclone separator, which nests an inner cyclone with a double-spiral inlet in an outer cyclone. Experiments were conducted to compare the separation performance of the new cyclone to that of the traditional Lapple cyclone. In addition, the flow fields and the particle collection in the two cyclones were simulated by the computational fluid dynamics (CFD) and compared. Compared with the traditional Lapple cyclone, the new double cyclone can present significantly improved collection efficiency, resulting from the two-stage separation and better symmetry of the flow field. On the other hand, the pressure drop of the new cyclone was only slightly elevated because of the low velocity in the outer cyclone. Moreover, this new double-stage cyclone separator can be further developed for particle classification, as the particles collected in the three outlets of the cyclone are in different size ranges.

A Seasonally Recurrent Annular Cyclone in Mars Northern Latitudes and Observations of a Companion Vortex

AbstractWe study a seasonally recurrent cyclone and related cloud phenomena observed on Mars at Ls ~120°, latitude ~60°N, and longitude 90°W from images obtained with cameras in different spacecraft between 1995 and 2018. A remarkable double cyclone formed in 2012 and we present a detailed study of its dynamics using images from Mars Express and Mars Reconnaissance Orbiter obtained between 6 June and 9 July. A double cyclone was also observed in 2006 and 2008. In other Martian years the primary cyclone showed an annular cloud morphology with a large water ice cloud observed eastward of it. The cyclones have a size of ~600–800 km with a cloud‐free core of a radius ~100–300 km. Tangential velocities measured from cloud tracking in 2012 images are ~5–20 m/s−1 at 10‐km altitude and double cyclone moved eastward with a velocity of 4 m/s−1 during its lifetime of one month. The vortices grow in the morning hours, but with the increasing insolation as the sol progresses, a part of the clouds evaporate, the winds weaken, and the vortices lose coherence. This phenomenon forms under high‐temperature gradients in a region with a large north‐south topographic slope and has been recurrent each Martian year between 1995 and 2018. We argue the interest of studying its changing properties each Martian year in order to explore their possible relationship to the state of the Martian atmosphere at Ls ~120°.

Computational investigation of flow parameters and efficiency of single and double inlet cyclone separators

ABSTRACTCyclone separators are one of the device used in power plant for long time; so many developments have been made in geometry, orientation and entry angle. In the present work an attempt is made with replacement of single inlet with double inlet. Computational analysis is done with Fluent 6.3.26 with Gambit 2.4.6 mesh generation using Cooper meshing facility. Eulerian–Lagrangian approach is adopted in the simulation with air as a working fluid and assumed to have continuous properties (Continuum). The collection efficiency of single and double inlet separator is studied using Lapple model, and it is found that there is an increase of 13.2% in collection efficiency for cyclone separator with double inlet. It is also found that higher inlet velocities are possible with double inlet separator without wall erosion when compared to single inlet separator.

二つ玉低気圧通過に伴う降水の気候学的研究

「二つ玉低気圧型」は日本で有名な気圧配置の一つで，全国各地に大雨や強風をもたらしやすいと言われている．本研究では二つ玉低気圧を並進タイプ，日本海低気圧メインタイプ，南岸低気圧メインタイプの三つに分類し，降水量や降水の強さ，降雪の深さについて気候学的解析を行った．また，比較のために一般的な日本海低気圧と南岸低気圧についても同様の解析を行った．並進タイプは全国に降水をもたらし，日本の南岸で降水量が多い．日本海低気圧メインタイプでは全国的に降水量が少ないが，本州の日本海側で冬季にふぶきとなりやすい特徴があった．南岸低気圧メインタイプは日本の南岸と北陸地方で特に多くの降水をもたらし，冬季には比較的広い範囲に降雪をもたらす．二つ玉低気圧3タイプで降水分布に生じる違いは，前線の有無に依存する．さらに，二つ玉低気圧が強雨をもたらすときは，南側の低気圧が日本列島により近いコースをとることがわかった．

Double Inlet Cyclone Separators for Natural Gas Dehydration

The fluid flow in the double cyclone separator is numerical simulated, using the Navier-Stokes equations with the Reynolds stress model (RSM). The basic parameters of gas flow are obtained as functions of radius such as the tangential velocity, the axial velocity and the static pressure. The numerical results show that in the cyclones water liquids are centrifuged onto the walls and removed from the natural gas due to the strong centrifugal field, while the natural gas stays in the central region and moves out from the up-outlet. The water can be well removed from the natural gas.

Comparative performances of conventional cyclones and a double cyclone with and without an electric field

Two conventional cyclones with different vortex finder diameters and a double cyclone were used to evaluate and compare their collection efficiencies and the effects of varying the vortex finder lengths and flow rates. In addition, a series of experiments were conducted to investigate the characteristics of the collection efficiencies of the cyclones when different voltages were applied to the vortex finder. The collection efficiency of the conventional cyclone with a smaller vortex finder diameter was higher, and that with a smaller vortex finder length was also higher when no voltage was applied. However, the collection efficiency properties were reversed when a voltage was applied and electric field was formed. The collection efficiency of the double cyclone increased greatly with increases in the applied voltage and decreases in the flow rate, and was the highest of all the cyclones when the same voltage and flow rates were applied. However, the collection efficiency of the double cyclone, with no applied voltage, was lower than that of the conventional cyclone with the 7-mm vortex finder diameter.

Noise characteristics and analytical precision of a direct injection high efficiency and micro concentric nebuliser for sample introduction in inductively coupled plasma mass spectrometry

Noise power spectra and analytical precision data were generated and compared for a direct injection high efficiency nebuliser, DIHEN, and a micro concentric nebuliser, MCN, combined with a double pass or cyclone spray chamber for sample introduction in inductively coupled plasma mass spectrometry, ICP-MS. The different systems were compared using liquid flow rates of 85 or 100 µL min−1. Steady-state signals for 115In+ and steady-state isotope ratio measurements for 107Ag+/109Ag+ were chosen for the investigation. For background and shot noise limited precision the DIHEN was found to give better precision than the double pass spray chamber system due to higher sensitivity. For flicker noise limited precision it was found that white noise and pump interference noise were higher, and 1/f noise and mains power interference noise were lower, for the DIHEN compared to the spray chamber systems. As a result of this, for 115In+ measurements, the DIHEN gave 2–9 times higher relative standard deviation, RSD, at measurement frequencies above 1 Hz but slightly lower RSD (not statistically significant) at frequencies below 0.1 Hz compared to the conventional systems. For the isotope ratio measurements, due to the high white noise level, the DIHEN generally gave poorer precision compared to the double pass spray chamber system. To convincingly explain the rationale for the observed flicker noise limited precision data, the effect of different noise components on analytical precision was evaluated. This study made obvious the relationship between precision and different noise components visualised in noise power spectra. Such information is useful for rational optimisation of operating conditions and technical developments of instrumentation. The mathematical simulation procedure used for this study was also applied to experimental data to predict analytical precision at typical measurement frequencies.

Exploratory Study on Cyclones of Modified Designs

This paper introduces a new design of cyclone, named triple cyclone, created by adding two more cylinders to the conventional cyclone. The performance of the triple cyclone was evaluated systematically together with the previously reported double cyclone. The tests showed that the collection efficiencies of double and triple cyclones were lower than those of the conventional cyclone with the same body diameter and identical gas inlet and outlet size. Of the three designs, the collection efficiency of the triple cyclone was the lowest. Accordingly, the highest pressure drop was observed for the conventional cyclone, and the pressure drop for the triple cyclone was the lowest. These results are probably attributed to the relatively weak vortices formed within triple and double cyclones.

Design and Performance Evaluation of a Novel Double Cyclone

A novel cyclone design, named double cyclone, adds an extra cylinder wall into a conventional reversed e ow cyclone. The physical performance of the double cyclone has been experimentally compared to a widely used conventional cyclone by measuring the particle concentrations both upstream and downstream of each cyclone with an Aerosizer. Tests with monodisperse polystyrene latex (PSL) particles with diameters ranging from 0.60 πm to 8.8 πm have shown that the double cyclone provides higher collection efe ciency than the conventional cyclone for a tested e ow rate range of 10‐40 L/min. In addition, the collection efe ciency difference between the double cyclone and the conventional cyclone becomes even larger as the aire ow rate increases. Sharper particle-size separation characteristics were also observed for the double cyclone. Furthermore, it was found that the double cyclone operates at a lower pressure drop than the conventional cyclone at the same normalized cut size.

Coarse ash particle characteristics in a pulp and paper industry chemical recovery boiler

To understand recovery boiler ash deposit formation, it is necessary to have detailed information on the ash particle properties in the flue gas. Since coarse particle deposition is orders of magnitude more efficient than fine particle deposition, the coarse particles were studied in detail. In an industrial recovery boiler, ash particles were extracted directly from the flue gases with a settling probe, a double cyclone–filter system and a thermophoretic sampler in the superheater area. The particles were analysed for their bulk chemical composition with ion chromatography. The individual particles were studied for their morphology and elemental composition with a high-resolution scanning electron microscope connected to an energy dispersive X-ray analyser. Measured coarse particle mass fraction of the total particle concentration was about 40%, which is significantly larger than proposed earlier. Five coarse particle types were observed at the superheater area: (i) partially sintered large agglomerates formed from fine fume particles that had entrained from the heat exchanger surfaces, (ii) extensively sintered irregular particles that had entrained from the surfaces by soot blowing, (iii) spherical particles that appeared highly porous inside, (iv) dense spherical particles, and (v) intermediate irregular particles of non-process mineral matter. At the boiler exit, the coarse particles were mainly partially sintered large agglomerates.

Design and Performance Evaluation of a Novel Double Cyclone

A novel cyclone design, named double cyclone, adds an extra cylinder wall into a conventional reversed e ow cyclone. The physical performance of the double cyclone has been experimentally compared to a widely used conventional cyclone by measuring the particle concentrations both upstream and downstream of each cyclone with an Aerosizer. Tests with monodisperse polystyrene latex (PSL) particles with diameters ranging from 0.60 πm to 8.8 πm have shown that the double cyclone provides higher collection efe ciency than the conventional cyclone for a tested e ow rate range of 10‐40 L/min. In addition, the collection efe ciency difference between the double cyclone and the conventional cyclone becomes even larger as the aire ow rate increases. Sharper particle-size separation characteristics were also observed for the double cyclone. Furthermore, it was found that the double cyclone operates at a lower pressure drop than the conventional cyclone at the same normalized cut size.