Improving the Operation of a Cyclone Coupled With an Ejector

2008 ◽  
Author(s):  
Wayne Strasser
Keyword(s):  
Collection Efficiency ◽  
Physical Space ◽  
Solid Particles ◽  
Transient Pressure ◽  
Strain Formulation ◽  
Particle Orbit ◽  
Polyethylene Production ◽  
Ejector System ◽  
Dense Vapor ◽  
Geometric Changes

The dynamics of a plant-scale cyclone/ejector system have been studied numerically. The purpose of said system is to separate and evacuate solid particles from a highly dense vapor stream involved in polyethylene production. Complexity arises from the fact that the transient pressure field within the Lappel cyclone governs the operation of the annular ejector, and vice versa. Specifically, the cyclone’s asymmetrically dancing vortex dips well into the ejector suction; therefore the two units cannot be computationally uncoupled. Compressible, time-dependent CFD results were surprisingly sensitive to the pressure discretization approach. Results had a mixed dependency on the slow pressure strain formulation in the differential Reynolds Stress calculations, while they were insensitive to the pressure-velocity coupling routine. Interesting results from earlier researchers regarding particle orbit radius, as well as particle bypassing were confirmed. Six geometric configurations for improving the system operation were evaluated. Pressure differential and solids collection efficiency were the two primary measures. Since said system is an integral part of a complex commercial operation, cost and physical space constraints severely limit the extent to which the geometry can be modified. Simple geometric changes were shown numerically to make operational improvements while only incrementally improving particle collection efficiency.

Extra Drag Force on a Circular Cylinder Due to the Presence of Solid Particles in Subsonic Compressible Flow

1991 ◽  
Author(s):  
Stanley B. Mellsen
Keyword(s):  
Compressible Flow ◽  
Incompressible Flow ◽  
Aerodynamic Drag ◽  
Collection Efficiency ◽  
Reynolds Numbers ◽  
Solid Particles ◽  
Circular Cylinders ◽  
Critical Mach Number ◽  
Wide Range ◽  
Inertia Parameters

Abstract The effect of particles, such as dust in air on aerodynamic drag of circular cylinders was calculated for compressible flow at critical Mach number and for incompressible flow. The effect of compressibility was found negligible for particles larger than about 10 μm, for which the air can be considered a continuum. Drag coefficient and collection efficiency are provided for a wide range of inertia parameters and Reynolds numbers for both compressible and incompressible flow.

CFD STUDY OF CYCLONE PERFORMANCE: EFFECT OF INLET SECTION ANGLE AND PARTICLE SIZE DISTRIBUTION

2016 ◽  
Vol 78 (6-4) ◽  
Author(s):  
Ratchanon Piemjaiswang ◽  
Kongpob Ratanathammapan ◽  
Prapan Kunchonthara ◽  
Pornpote Piumsomboon ◽  
Benjapon Chalermsinsuwan
Keyword(s):  
Pressure Drop ◽  
Gas Flow ◽  
Collection Efficiency ◽  
Solid Particles ◽  
Inlet Section ◽  
Two Phase ◽  
Performance Effect ◽  
Computational Fluid Dynamics Cfd ◽  
Inlet Angle ◽  
Numerical Simulation Technique

A numerical simulation technique was employed to model the two phase flow in cyclones using computational fluid dynamics (CFD). Three different inlet angles of cyclone, including 45, 0 and -45 degrees were compared to describe the efficiency of the conventional cyclone with the modified inlet angle ones. The results showed that the interaction between solid particles in dilute system could be neglected. The pressure drop was decreased when the inlet angle of the cyclone increased. The cyclone with 45 degrees inlet angle tended to have the lowest pressure drop. The collection efficiency was improved with 45 degrees inlet angle due to high swirling motion of gas flow. 

Filtration of Electrified Solid Particles in a Fibrous Filter

2010 ◽  
Vol 660-661 ◽  
pp. 1118-1123
Author(s):  
Marcos V. Rodrigues ◽  
Marcos A.S. Barrozo ◽  
José Renato Coury
Keyword(s):  
Pressure Drop ◽  
Gradual Increase ◽  
Collection Efficiency ◽  
Particle Diameter ◽  
Solid Particles ◽  
Fibrous Filter ◽  
Rock Powder ◽  
Particle Charging ◽  
Powder Density ◽  
A Charge

The aim of the present work is to verify experimentally the influence of the charge level on collection efficiency during the first stages of filtration. A charge classifier was used to measure the charge level of the aerosol as a function of particle diameter. The filter was made of polypropylene with diameter of 0.047 m and a thickness of 2.6 mm. The solid particles used as test dust were a phosphate rock powder (density 2940 kg/m3 and average Stokes diameter of 3.40 m). The aerosol was dispersed by a TSI Venturi type generator. The particle charging was achieved by a corona charger. In all the tests performed, a linear relation between the particles acquired charge and their diameter was observed. A gradual increase of the charge level was observed with an increase of the tension in the corona charger (0, -3, -6 kV). The filtration results indicated that the global collection efficiency of the filter was very sensitive to the variation of the charge level of the particles. Both efficiency and pressure drop increased when the charge level increased. During the tests, the small increase in pressure drop indicated that the cake had not yet been formed.

scholarly journals Application of ejectors for two-phase flows

2021 ◽  
Vol 263 ◽  
pp. 04023
Author(s):  
Liudmila Volgina ◽  
Anastasiia Romanova
Keyword(s):  
Practical Problem ◽  
High Reliability ◽  
Solid Particles ◽  
Hydraulic Structures ◽  
Modern World ◽  
Two Phase ◽  
Pipe Length ◽  
Energy Characteristics ◽  
Frequent Use ◽  
Ejector System

The article studies the work of a water jet pump (ejector), influence of the mixture characteristics and pipe length on the energy parameters of the ejector system. The relevance of the topic is associated with the active use of ejectors in the modern world in various areas, including in hydraulic structures. Frequent use of ejectors is ensured by high reliability, simplicity of design and maintenance. The purpose of this work is to study the operation of the ejector, the energy characteristics of the flow and the influence of the characteristics of the transported two-phase flow. The calculation of the real practical problem of selecting an ejector for lifting and transporting solid particles is given. The values of the density of the transported mixture and the length of the transport pipes are selected as variable indicators. The analysis of the calculation shows that taking into account the energy characteristics of the flow when selecting the components of the ejector system is very important, and the density of the transported mixture affects the efficiency of the system.

Performance Measurements of a Unique Louver Particle Separator for Gas Turbine Engines

2012 ◽  
Author(s):  
Grant O. Musgrove ◽  
Karen A. Thole ◽  
Eric Grover ◽  
Joseph Barker
Keyword(s):  
Secondary Flow ◽  
Gas Turbine ◽  
Pressure Loss ◽  
Collection Efficiency ◽  
Reynolds Numbers ◽  
Solid Particles ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Performance Measurements ◽  
Particle Separator

Solid particles, such as sand, ingested into gas turbine engines reduce the coolant flow in the turbine by blocking cooling channels in the secondary flow path. One method to remove solid particles from the secondary flow path is to use an inertial particle separator because of its ability to incur minimal pressure losses in high flow rate applications. In this paper, an inertial separator is presented that is made up of an array of louvers followed by a static collector. The performance of two inertial separator configurations was measured in a unique test facility. Performance measurements included pressure loss and collection efficiency for a range of Reynolds numbers and sand sizes. To complement the measurements, both two-dimensional and three-dimensional computational results are presented for comparison. Computational predictions of pressure loss agreed with measurements at high Reynolds numbers, whereas predictions of sand collection efficiency for a sand size range 0–200μm agreed within 10% of experimental measurements over the range of Reynolds numbers. Collection efficiency values were measured to be as high as 35%, and pressure loss measurements were equivalent to less than 1% pressure loss in an engine application.

Performance Measurements of a Unique Louver Particle Separator for Gas Turbine Engines

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
Grant O. Musgrove ◽  
Karen A. Thole ◽  
Eric Grover ◽  
Joseph Barker
Keyword(s):  
Secondary Flow ◽  
Gas Turbine ◽  
Pressure Loss ◽  
Collection Efficiency ◽  
Reynolds Numbers ◽  
Solid Particles ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Performance Measurements ◽  
Particle Separator

Solid particles, such as sand, ingested into gas turbine engines, reduce the coolant flow in the turbine by blocking cooling channels in the secondary flow path. One method to remove solid particles from the secondary flow path is to use an inertial particle separator because of its ability to incur minimal pressure losses in high flow rate applications. In this paper, an inertial separator is presented that is made up of an array of louvers followed by a static collector. The performance of two inertial separator configurations was measured in a unique test facility. Performance measurements included pressure loss and collection efficiency for a range of Reynolds numbers and sand sizes. To complement the measurements, both two-dimensional and three-dimensional computational results are presented for comparison. Computational predictions of pressure loss agreed with measurements at high Reynolds numbers, whereas predictions of sand collection efficiency for a sand size range 0–200μm agreed within 10% of experimental measurements over the range of Reynolds numbers. Collection efficiency values were measured to be as high as 35%, and pressure loss measurements were equivalent to less than 1% pressure loss in an engine application.

scholarly journals Numerical prediction of short-cut flows in gas-solid reverse flow cyclone separators

2017 ◽  
Vol 23 (4) ◽  
pp. 483-493 ◽  
Author(s):  
Ali Sakin ◽  
Irfan Karagoz
Keyword(s):  
Collection Efficiency ◽  
Reverse Flow ◽  
Reynolds Stress Model ◽  
Solid Particles ◽  
Phase Method ◽  
Geometrical Parameters ◽  
Pressure Drops ◽  
Discrete Phase Method ◽  
Discrete Phase ◽  
Vortex Finder

The effect of operational and geometrical parameters on the short-cut flow in cyclone separators has been investigated computationally using the Reynolds stress model (RSM). The motion of solid particles in the flow field was simulated using the Eulerian-Lagrangian approach with one way discrete phase method (DPM). Eleven cyclones with different cone tip diameters, vortex finder lengths and diameters were studied and the simulation results were analyzed in terms of velocity fields, pressure drops, cut-off diameters and short-cut flows. The numerical simulation was verified with the published experimental results. The results obtained demonstrate that all three parameters, particularly, vortex finder diameter, have significant effects on the cut-off diameter (collection efficiency), the short-cut flow and the pressure drop.

To What Extent are Inelastically Scattered Electrons Useful in the Stem?

1973 ◽  
Vol 31 ◽  
pp. 286-287 ◽  
Author(s):  
H. Rose
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Electron Correlation ◽  
Quantum Noise ◽  
Collection Efficiency ◽  
Scanning Transmission Electron Microscope ◽  
Electron Cloud ◽  
Scanning Time ◽  
Transmission Electron ◽  
Scanning Transmission

The scanning transmission electron microscope offers the possibility of utilizing inelastically scattered electrons. Use of these electrons in addition to the elastically scattered electrons should reduce the scanning time (dose) Which is necessary to keep the quantum noise below a certain level. Hence it should lower the radiation damage. For high resolution, Where the collection efficiency of elastically scattered electrons is small, the use of Inelastically scattered electrons should become more and more favorable because they can all be detected by means of a spectrometer. Unfortunately, the Inelastic scattering Is a non-localized interaction due to the electron-electron correlation, occurring predominantly at the circumference of the atomic electron cloud.

High energy resolution spectrometer for the dedicated STEM

1984 ◽  
Vol 42 ◽  
pp. 558-559 ◽  
Author(s):  
P.E. Batson
Keyword(s):  
Collection Efficiency ◽  
Core Loss ◽  
Beam Current ◽  
High Energy ◽  
High Energy Resolution ◽  
Acquisition Time ◽  
Good Definition ◽  
Loss Analysis ◽  
Definition Of ◽  
Acceleration Voltage

Use of the STEM to obtain precise electronic information has been hampered by the lack of energy loss analysis capable of a resolution and accuracy comparable to the 0.3eV energy width of the Field Emission Source. Recent work by Park, et. al. and earlier by Crewe, et. al. have promised magnetic sector devices that are capable of about 0.75eV resolution at collection angles (about 15mR) which are great enough to allow efficient use of the STEM probe current. These devices are also capable of 0.3eV resolution at smaller collection angles (4-5mR). The problem that arises, however, lies in the fact that, even with the collection efficiency approaching 1.0, several minutes of collection time are necessary for a good definition of a typical core loss or electronic transition. This is a result of the relatively small total beam current (1-10nA) that is available in the dedicated STEM. During this acquisition time, the STEM acceleration voltage may fluctuate by as much as 0.5-1.0V.

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