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.
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