Improving efficiency of a gas cyclone in high-temperature operating conditions by using appropriate geometry of vortex finder
Subject Areas : Industrial pollutionAkbar Jafarnezhad 1 , Hesamoddin SALARIAN 2 * , Saeid Kheradmand 3 , Jahanfar Khaleghinia 4
1 - Department of Mechanical Engineering, Nour Branch, Islamic Azad University, Nour, Iran.
2 - Department of Mechanical Engineering, Nour Branch, Islamic Azad University, Nour, Iran. * (Corresponding Author)
3 - Department of Mechanical and Aerospace Engineering, Malek-Ashtar University of Technology, Shahin-shahr, Isfahan, Iran.
4 - Department of Mechanical Engineering, Nour Branch, Islamic Azad University, Nour, Iran.
Keywords: Gas cyclone, Vortex finder, Separation efficiency, High-temperature, Computational Fluid Dynamics (CFD).,
Abstract :
Background and Objective: Cyclones are widely used in air pollution control to separate particulate gas mixtures and are used in industry. The advantages of this device in different industries are its relative simplicity of construction, low operating cost and reliable under extreme working conditions. Today, cyclone separators have become one of the most important particle removal devices in the fields of science and engineering. Due to the wide application of cyclones in industrial processes, especially thermal power plants, the study of the performance of cyclones at high temperatures is of particular importance. In the present study, two-phase flow simulation within a cyclone will be performed in three different dimensions using the Eulerian-Lagrangian approach in order to study the cyclone performance in a wide range of temperatures, and finally the problem of its lower performance will be substantially resolved by using appropriate geometry of vortex finder. Material and Methodology: In this study, the effect of inlet temperature on the flow field and the separation performance of a cyclone has been comprehensively investigated using CFD simulation. The Euler-Lagrangian approach has been used to simulate airflow and particle dynamics in cyclones. In addition, four proposed vortex finder geometries were considered and compared with the basic geometry in order to evaluate how the vortex finder affects the cyclone performance under a wide temperature range (293 K-700 K). The validity of the numerical model is confirmed by comparing the predicted pressure drop with the experimental data and numerical results in which there is a good agreement was achieved. Findings: The results demonstrated that increasing of inlet temperature significantly reduced the tangential velocity and led to a sharp decrease in the cyclone separation efficiency. All of the proposed vortex finders affected the flow pattern within the cyclone at all inlet temperatures. The simulation results showed that the highest tangential velocity observed in the cyclone was with CVF 1, which also had a positive effect on the relevant separation efficiency. Also, it is proved that the proposed cyclone with CVF 1 was able to collect finer particles (2 μm) at high inlet temperature (T = 700 K). Discussion and Conclusion: In the present study, while examining the performance of cyclone using the Eulerian-Lagrangian approach in three dimensions over a wide temperature range, a suitable solution to improve efficiency and solve the problem of efficiency drop at high temperatures was presented. By properly changing the dimensions and geometry of the vortex finder, the flow in the pre-separation zone can be well controlled to improve particle separation efficiency.
1. R, Xiang., S, Park., K.W, Lee., 2001. Effects of cone dimension on cyclone performance. Journal of Aerosol Science, vol. 32, pp. 549-561.
2. Y, Zhu., K.W, Lee., 1999. Experimental study on small cyclones operating at high flow rates. Journal of Aerosol Science, vol. 30, pp. 1303-1315.
3. J, Jiao., Y, Zheng., J, Wang, G, Sun., 2008. Experimental and numerical investigations of a dynamic cyclone with a rotary impeller. Chemical Engineering and Processing: Process Intensification, vol. 47, pp. 1861-1866.
4. S, Bernardo., M, Mori., A.P, Peres., R.P, Dionisio., 2006. 3-D computational fluid dynamics for gas and gas-particle flow in a cyclone with different inlet section angles. Powder Technology, vol. 162, pp. 190-200.
5. G, Wan., G, Sun., X, Xue., M, Shi., 2008. Solids concentration simulation of different size particles in a cyclone separator. Powder Technology, vol. 183, pp. 94-104.
6. H, Fatahian., E, Fatahian., E., M.E, Nimvari., 2018. Improving efficiency of conventional and square cyclones using different configurations of the laminarizer. Powder Technology, vol. 339, pp. 232-243.
7. M, Shin., H.S, Kim., D, Jang., J.D, Chung., M, Bohnet., 2005. A numerical and experimental study on a high efficiency cyclone dust separator for high temperature and pressurized environments. Applied Thermal Engineering, vol. 25, pp. 1821-1835.
8. M, Siadaty., S, Kheradmand., F, Ghadiri., 2017. Study of inlet temperature effect on single and double inlets cyclone performance. Advanced Powder Technology, vol. 28, pp. 1459-1473.
9. M, Wasilewski., 2016. Analysis of the effects of temperature and the share of solid and gas phases on the process of separation in a cyclone suspension preheater. Separation and Purification Technology, vol. 168, pp. 114-123.
10. B, Zhao., H, Shen., Y, Kang., 2004. Development of a symmetrical spiral inlet to improve cyclone separator performance. Powder Technology, vol. 145, pp. 47-50.
11. H, Safikhani., M, Akhavan-Behabadi., M, Shams., M., M, Rahimyan., 2010. Numerical simulation of flow field in three types of standard cyclone separators. Advanced Powder Technology, vol. 21, pp. 435-442.
12. F, Kaya., I, Karagoz., A, Avci., 2011. Effects of surface roughness on the performance of tangential inlet cyclone separators. Aerosol science and technology, 45(8), 988-995.
13. T, Chuah., J, Gimbun, T.S, Choong., 2006. A CFD study of the effect of cone dimensions on sampling aerocyclones performance and hydrodynamics. Powder technology, vol. 162, pp. 126-132.
14. K, Elsayed., C, Lacor., 2010. Optimization of the cyclone separator geometry for minimum pressure drop using mathematical models and CFD simulations. Chemical Engineering Science, vol. 65, pp. 6048-6058.
15. H, Fatahian., E, Fatahian., M.E, Nimvari., G, Ahmadi., 2020. Novel designs for square cyclone using rounded corner and double-inverted cones shapes. Powder Technology, vol. 380, pp. 67-79.
16. H, Fatahian., E, Fatahian., 2020. Improving efficiency of a square cyclone separator using a dipleg – a CFD-based analysis." Iranian Journal of Chemistry and Chemical Engineering (IJCCE), 10.30492/ijcce.2020.127666.4129.
17. B.E, Launder., G, Reece., W, Rodi., 1975. Progress in the development of a Reynolds-stress turbulence closure. Journal of Fluid Mechanics, vol. 68, pp. 537-566.
18. S, Wang., M, Fang., Z, Luo., X, Li., M, Ni., K, Cen., 1999. Instantaneous separation model of a square cyclone. Powder Technology, vol. 102, pp. 65-70.
19. A.J, Hoekstra., J.J, Derksen., H.E, Van Den Akker, 1999. An experimental and numerical study of turbulent swirling flow in gas cyclones. Chemical Engineering Science, vol. 54, pp. 2055-2065.
20. K, Jang., G, Lee., K, Huh., 2018. Evaluation of the turbulence models for gas flow and particle transport in URANS and LES of a cyclone separator. Computers & Fluids, vol, 172, pp. 274-283.
21. M, Azadi., M, Azadi., A, Mohebbi., 2010. A CFD study of the effect of cyclone size on its performance parameters. Journal of hazardous materials, vol, 182, pp. 835-841.
22. S.A, Morsi., A.J, Alexander., 1972. An investigation of particle trajectories in two-phase flow systems. Journal of Fluid mechanics, vol. 55, pp. 193-208.
23. H, Fatahian., E, Hosseini., E, Fatahian., 2020. CFD simulation of a novel design of square cyclone with dual-inverse cone. Advanced Powder Technology, vol. 31, pp. 1748-1758.
24. B, Zhao., Y, Su., J, Zhang., 2006. Simulation of gas flow pattern and separation efficiency in cyclone with conventional single and spiral double inlet configuration. Chemical engineering research and design, vol. 84, pp. 1158-1165.
25. M, Wasilewski., L.S, Brar., Effect of the inlet duct angle on the performance of cyclone separators. Separation and Purification Technology vol. 213, pp. 19-33.
26. E, Fatahian., H, Fatahian., E, Hosseini., E., G, Ahmadi., 2021. A low-cost solution for the collection of fine particles in square cyclone: A numerical analysis. Powder Technology, vol. 387, pp. 454-465.
27. H, Fatahian., E, Fatahian, M.E, Nimvari., G, Ahmadi., 2021. Novel designs for square cyclone using rounded corner and double-inverted cones shapes. Powder Technology, vol. 380, pp. 67-79.
28. T.L, Bergman., F.P, Incropera., D.P, DeWitt., A.S, Lavine., 2011. Fundamentals of heat and mass transfer. John Wiley & Sons.
29. M, Siadaty., S, Kheradmand., F, Ghadiri., 2018. Research on the effects of operating conditions and inlet channel configuration on exergy loss, heat transfer and irreversibility of the fluid flow in single and double inlet cyclones. Applied Thermal Engineering, vol. 137, pp. 329-340.
30. H.I, Erol, O, Turgut., R, Unal., 2019. Experimental and numerical study of Stairmand cyclone separators: a comparison of the results of small-scale and large-scale cyclones. Heat and Mass Transfer, vol. 55, pp. 2341-2354.
31. S, Wang., H, Li., R, Wang., X, Wang., R, Tian., Q, Sun., 2019. Effect of the inlet angle on the performance of a cyclone separator using CFD-DEM. Advanced Powder Technology, vol. 30, pp. 227-239.