شبیه سازی تاثیر تغییرات فشار محیط بر عملکرد جداکننده دو مرحله ای واسطه سنگین آزمایشگاهی

نوع مقاله: علمی-پژوهشی

نویسندگان

1 استادیار، دانشکده مهندسی معدن و متالورژی، دانشگاه یزد، یزد

2 دانشجوی دکترا، دانشکده مهندسی معدن و متالورژی، دانشگاه یزد، یزد

10.30479/jmre.2019.10142.1232

چکیده

از آنجا که در جداکننده دو مرحله‌ای واسطه سنگین، بار ورودی تحت فشار اتمسفر به دستگاه وارد می‌شود و اختلاف فشار سیال داخل دستگاه با محیط بیرون، از طریق تنظیم فشار معکوس در خروجی‌های غوطه‌ور و محصول میانی کنترل می‌شود، بررسی تاثیر فشار محیط بر عملکرد جداکننده اهمیت دارد. در این تحقیق، اثر فشار محیط بر الگوی جریان در این جداکننده با استفاده از دینامیک سیالات محاسباتی (CFD) مدلسازی شده است. بدین منظور، از مدل چندفازی حجم سیال (VOF) برای تعیین شکل اولیه و موقعیت هسته هوا در داخل جداکننده و از مدل فاز مجزا (DPM) برای توصیف جریان ذرات جامد استفاده شد. آشفتگی با استفاده از مدل تنش رینولدز (RSM) توصیف شده است. شبیه‌سازی در فشار 1 اتمسفر(در سطح آب‌های آزاد )، 86/0 اتمسفر (در ارتفاع 1250 متر از سطح دریا) و 64/0 اتمسفر (در ارتفاع 3500 متر از سطح دریا) انجام شد. بر اساس نتایج شبیه‌سازی، تغییر در فشار محیطی منجر به تغییراتی در میدان جریان، پارامترهای ماکروسکوپیک و عملکرد جداکننده می‌شود. اعتبار نتایج شبیه‌سازی با مقایسه و انطباق بر نتایج آزمایشگاهی حاصل از یک دستگاه جداکننده شفاف ساخته شده به همین منظور تائید شده است. نتایج تحقیق حاضر نشان داد که با کاهش فشار محیط، مقدار خطای احتمال (Ep) کاهش و بازیابی واسطه افزایش می‌یابد، اما مقادیر این تاثیرات کمتر از 2 % به دست آمد. لذا می‌توان از جداکننده واسطه سنگین گریز از مرکز دو مرحله‌ای در موقعیت‌های مکانی با ارتفاع مختلف از سطح دریا بدون این که خللی در عملکرد جداکننده ایجاد شود، استفاده نمود.

کلیدواژه‌ها


عنوان مقاله [English]

Simulation of the Effect of Atmospheric Pressure on the Performance of Laboratory Two-Stage Dense Medium Separator

نویسندگان [English]

  • R. Dehghan 1
  • M. Aghaei 2
1 Assistant Professor, Dept. of Mining and Metallurgical Engineering, Yazd University, Yazd, Iran
2 Ph.D Student, Dept. of Mining and Metallurgical Engineering, Yazd University, Yazd, Iran
چکیده [English]

The effects of atmospheric pressure of the site of installation of a centrifugal two-stage heavy medium separator is of crucial importance because the pressure difference between the medium input and the sink output streams is adjusted by the back pressure rings. However, contrary to the dense medium cyclone, the raw feed ore into this separator is sluiced without pumping.  In this research, the effect of atmospheric pressure on the flow pattern inside the Tri-Flo separator is investigated using the computaional fluid dynamic (CFD) simulation. Therefore, the volume of fluid (VOF) model and discrete phase model (DPM) were used for the calculation of the diameter of the air core and the behavior of solid particles, respectively. Reynols stress model (RSM) was used for turbulence modeling. Simulations were performed in three different atmospheric pressure including 1, 0.86 and 0.64 atm, representing the site of installation at sea level and heights of 1250 meters and 3500 meters above the sea level, respectively. The CFD simulation results showed that the change in atmospheric pressure has some effects on the flow fields, macroscopic parameters and the performance of the Tri-Flo separator. The results of simulation were validated against the experimental data achived using the transparent laboratort Tri-Flo separator. The fluid velocity in output streams and the size and the pattern of air core were used for validation. The decrease in Ecart propale error (Ep) of the separator and increase in the medium recovery were observed, when the atmospheric pressure was decreased. However, the effects were in the margin of 2%. According to the results of this research, the Tri-Flo separator can be used in different elevations from the sea level, without serious problem in the operation regime.

کلیدواژه‌ها [English]

  • CFD simulation
  • Atmospheric pressure
  • Discrete phase model (DPM)
  • Dense medium separation (DMS)
[1]     Aplan, F. F. (1985). “Gravity Concentration”. In SME Mineral Processing Handbook, Society of Mining Engineers of the American Institute of Mining, Metallurgical, and Petroleum Engineers, New York, 1: 1-52.

[2]     Babu, S. P., and Leonard, J. W. (1985). “Section 25: Coal”. In SME Mineral Processing Handbook, Society of Mining Engineers of the American Institute of Mining, Metallurgical, and Petroleum Engineers, New York, 2: 1-31.

[3]     Leonard, J. W., and Hardinge, B. C. (1991). “Coal Preparation”. 5th Edition, Maryland: Society for Mining, Metallurgy, and Exploration, Colorado, 383-403.

[4]     Burt, R., and Mills, C. (1984). “Gravity Concentration Technology (Developments in Mineral Processing)”. Elsevier Science Publishing Company, Amsterdam, Netherlands, 162-178.

[5]     Ferrara, G., Machiavelli, G., Bevilacqua, P., and Meloy, T. (1994). “Tri-Flo: a multistage high-sharpness DMS process with new applications”. Minerals & Metallurgical Processing, 11( 2): 63-73.

[6]     Parvaz, F. S., Hosseini, H., Elsayed, K., and Ahmadi, G. (2018). “Numerical investigation of effects of inner cone on flow field, performance and erosion rate of cyclone separators”. Separation and Purification Technology, 201: 223-237.

[7]     Luciano, R. D., Silva, B. L., Rosa, L. M., and Meier, H. F. (2018). “Multi-objective optimization of cyclone separators in series based on computational fluid dynamics”. Powder Technology, 325: 452-466.

[8]     Juengcharoensukying, J., Poochinda, K., and Chalermsinsuwan, B. (2017). “Effects of Cyclone Vortex Finder and Inlet Angle on Solid Separation Using CFD Simulation”. Energy Procedia,138: 1116-1121.

[9]     Wei, J., Zhang, H., Wang, Y., Wen, Z., Yao, B., and Dong, J. (2017). “The gas-solid flow characteristics of cyclones”. Powder Technology, 308: 178-192.

[10]  Hamdy, O., Bassily, M. A., El-Batsh, H. M., and Mekhail, T. A. (2017). “Numerical study of the effect of changing the cyclone cone length on the gas flow field”. Applied Mathematical Modelling,46: 81-97.

[11]  Kozołub, P., Klimanek, A., Białecki, R. A., and Adamczyk, W. P. (2017). “Numerical simulation of a dense solid particle flow inside a cyclone separator using the hybrid Euler–Lagrange approach”. Particuology, 31: 170-180.

[12]  Demir, S., Karadeniz, A., and Aksel, M. (2016) “Effects of cylindrical and conical heights on pressure and velocity fields in cyclones”. Powder Technology, 295: 209-217.

[13]  Elsayed, K., and Lacor, C. (2014). “Analysis and Optimisation of Cyclone Separators Geometry Using RANS and LES Methodologies”. In Turbulence and Interactions. Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 125: 65-74.

[14]  Elsayed, K. (2015). “Optimization of the cyclone separator geometry for minimum pressure”. Powder Technology, 269: 409-424.

[15]  Elsayed, K., and Lacor, C. (2010). “Optimization of the cyclone separator geometry for minimum pressure drop”. Chemical Engineering Science, 65: 6048-6058.

[16]  Brar, L. S., and Elsayed, K. (2018). “Analysis and optimization of cyclone separators with eccentric vortex finders using large eddy simulation and artificial neural network”. Separation and Purification Technology, 207: 269-283.

[17]  Vakamalla, T. R., Kumbhar, K. S., Gujjula, R., and Mangadoddy, N. (2014). “Computational and experimental study of the effect of inclination on hydrocyclone performance”. Separation and Purification Technology, 138: 104-117.

[18]  Elsayed, K., and Lacor, C. (2013). “The effect of cyclone vortex finder dimensions on the flow pattern and performance using LES”. Computers & Fluids, 71: 224-239.

[19]  Elsayed, K., and Lacor, C. (2011). “The effect of cyclone inlet dimensions on the flow pattern and performance”. Applied Mathematical Modelling, 35: 1952-1968.

[20]  Chuah, T. G., Gimbun, J., and Choong, T. S. Y. (2006). “A CFD study of the effect of cone dimensions on sampling aerocyclones performance and hydrodynamics”. Powder Technology, 162(2): 126-132.

[21]  Azadi, M., Azadi, M., and Mohebbi, A. (2010). “A CFD study of the effect of cyclone size on its performance parameters”. Journal of Hazardous Materials, 182: 835-841.

[22]  Raoufi, A., Shams, M., Farzaneh, M., and Ebrahimi, R. (2008). “Numerical simulation and optimization of fluid flow in cyclone vortex finder”. Chemical Engineering and Processing: Process Intensification, 47(1): 128-137.

[23]  Murthy, Y. R., and Bhaskar, K. U. (2012). “Parametric CFD studies on hydrocyclone”. Powder Technology, 230: 36-47.

[24]  Safikhani, H., Akhavan-Behabadi, M. A., Shams, M., and Rahimyan, M. H. (2010). “Numerical simulation of flow field in three types of standard cyclone separators”. Advanced Powder Technology, 21: 435-442.

[25]  Demir, S., Karadeniz, A., and Aksel, M. (2016). “Effects of cylindrical and conical heights on pressure and velocity fields in cyclones”. Powder Technology, 295: 209-217.

[26]  Kumar, A., and Brar, L. S. (2015). “CFD simulations of cyclone separators with different diameters: Analysis of gas cyclones with different cylinder diameters”. In 2015 International Conference on Futuristic Trends on Computational Analysis and Knowledge Management, Noida, 180-185.

[27]  Ghodrat, M., Kuang, S. B., Yu, A. B., Vince, A., Barnett, G. D., and Barnett, P. J. (2013). “Computational Study of the Multiphase Flow and Performance of Hydrocyclones: Effects of Cyclone Size and Spigot Diameter”. Industrial & Engineering Chemistry Research, 52(45): 16019-16031.

[28]  Xu, Y., Song, X., Sun, Z., Tang, B., Li, P., and Yu, J. (2013). “Numerical Investigation of the Effect of the Ratio of the Vortex-Finder Diameter to the Spigot Diameter on the Steady State of the Air Core in a Hydrocyclone”. Industrial & Engineering Chemistry Research, 52(15): 5470-5478.

[29]  Belardi, G., Bozano, P., Mencinger, J., Piller, M., and Schena, G. (2014). “Numerical simulation of water–air flow pattern in a tri-flo®cylindrical separator”. Proceedings of the XXVII International Mineral Processing Congress, Santigo, Chile, 1-9.

[30]  Sharma, A. (2017). “Introduction to Computational Fluid Dynamics: Development, Application and Analysis”. Chichester, West Sussex: John Wiley & Sons Ltd., 194-215.

[31]  Chu, K. W., Wang, B., Yu, A. B., and Vince, A. (2012). “Particle scale modelling of the multiphase flow in a dense medium cyclone: Effect of vortex finder outlet pressure”. Minerals Engineering, 31: 46-58.

[32]  Wang, B., Chu, K. W., Yu, A. B., and Vince, A. (2009). “Modeling the Multiphase Flow in a Dense Medium Cyclone”. Industrial & Engineering Chemistry Research, 48(7): 3628-3639.