Öz
Karıştırmalı tanklarda en önemli tasarım parametrelerinden bir tanesi güç tüketimidir. Tasarım, sürecin amacı ve güç tüketiminin birlikte değerlendirilmesi sonucu, en iyi sonucun en düşük güç tüketiminde elde edildiği sistem düzenlemesine göre yapılır. Karıştırmalı tanklarda genel olarak tam engel kullanılmaktadır. Ancak bazı durumlarda daha kısa ve yüzeye yakın veya tankın tabanından belli bir mesafe uzaktan başlayan engellerin kullanılması sürecin amaçları açısından daha uygun olmaktadır. Bazı durumlarda ise hiç engel kullanılmaz. Güç tüketiminin hesaplanması için karıştırıcıya özel güç sayısının bilinmesi gerekmektedir. Literatürde tam engel kullanıldığı zaman karıştırıcıların güç sayıları yaygın olarak verilmiştir. Ancak, farklı tür engeller kullanıldığındaki güç sayıları bilinmemekte ve bu sebeple bu sistemlerin güç tüketimleri tasarım aşamasında hesaplanamamaktadır. Bu çalışmada karıştırmalı bir tankta engel uzunluğunun karıştırıcı güç sayısına etkisi araştırılmıştır. Tam engel, tabandan boşluklu engel, yüzey engeli, yarım engel ve engelsiz tank düzenlerinde eğimli bıçaklı karıştırıcının tork değerleri geniş bir Reynolds sayısı aralığında ölçülmüş ve güç sayıları hesaplanmıştır. En küçük güç sayılarına engelsiz düzende ve sonrasında yüzey engeli ile ulaşılmıştır.
Anahtar Kelimeler
Destekleyen Kurum
Tübitak
Proje Numarası
117M158
Teşekkür
Yazarlar TÜBİTAK’a (Proje no:117M158) destekleri için teşekkür ederler.
Kaynakça
- 1. Hemrajani, R.R. and Tatterson, G.B., 2004. Mechanically stirred vessels in Handbook of Industrial Mixing: Science and Practice, John Wiley&Sons, New Jersey.
- 2. Ayranci, I., Machado, M.B., Madej, A.M., Derksen, J.J., Nobes, D.S. and Kresta, S.M., 2012. Effect of geometry on the mechanisms for off-bottom solids suspension in a stirred tank, Chemical Engineering Science, 79: 163–176.
- 3. Assirelli, M., Bujalski, W., Eaglesham, A., Nienow, A.W., 2008. Macro- and micromixing studies in an unbaffled vessel agitated by a Rushton turbine, Chemical Engineering Science, 63: 35-46.
- 4. Myers, K.J. and Fasano, J.B., 2002. The influence of baffle off-bottom clearance on the solids suspension performance of pitched blade and high-efficiency impellers, Canadian Journal of Chemical Engineering, 70: 596-599.
- 5. Khazam, O. and Kresta, S.M., 2009. A novel geometry for solids drawdown in stirred tanks, Chemical Engineering Research & Design, 87(3A): 280-290.
- 6. Bates, R.L., Fondy P.L. and Corpstein, R.R., 1963. An examination of some geometric parameters of impeller power, Industrial & Engineering Chemistry Research, 2(4): 310–314.
- 7. Yianneskis, M., Popiolek, Z., Whitelaw, J.H., 1987. An experimental study of the steady and unsteady-flow characteristics of stirred reactors, Journal of Fluid Mechanics, 175: 537–555.
- 8. Ibrahim, S. and Nienow, A.W., 1995. Power curves and flow patterns for a range of impellers in Newtonian fluids: 40<Re<5x105, Chemical Engineering Research&Design, 73(A5): 485–491.
- 9. Armenante, P.M., Mazzarotta B. and Chang, G.M., 1999. Power consumption in stirred tanks provided with multiple pitched-blade turbines, Industrial & Engineering Chemistry Research, 38(7): 2809–2816.
- 10. Rutherford, K., Mahmoudi, S.M.S., Lee, K.C. and Yianneskis, M., 1996. The influence of Rushton impeller blade and disk thickness on the mixing characteristics of stirred vessels. Transactions of the Institution of Chemical Engineers, 74(A3): 369–378.
- 11. Rushton, J.H., Costich, E.W. and Everett, H.J., 1950. Power characteristics of mixing impellers, Chemical Engineering Progress, 46(8): 395–476.
- 12. S. Nagata, 1975. Mixing: Principles and Applications, John Wiley & Sons, New York.
- 13. Chapple, D., Kresta, S.M., Wall, A. and Afacan, A., 2002. The effect of impeller and tank geometry on power number for a pitched blade türbine, Transactions of the Institution of Chemical Engineers, 80(A): 364-372.
- 14. Machado, M.B., Bittorf, K.J., Vesselina T.R. and Kresta, S.M., 2013. Transition from turbulent to transitional flow in the top half of a stirred tank, Chemical Engineering Science, 98: 218-230.
Öz
One of the most important design parameters for stirred tanks is the power consumption. Design is based on a simultaneous evaluation of process mixing objective and power consumption. The configuration that gives the best process results at minimum power consumption gives the final design. In stirred tanks, often fully baffled tanks are used. In some processes, however, it was shown that shorter, closer to surface, or off-bottom baffles are more suitable in terms of process objectives. Unbaffled tanks are also sometimes used. Impeller specific power number needs to be known in order to calculate power consumption. The power number of various impellers are given in literature for baffled tanks. For different types of baffles, however, no power number information is available in the literature. This means that the power consumption cannot be calculated while designing these tanks. In this study, the effect of length of the baffle on the power number was investigated. Full baffles, off-bottom baffles, half baffles, surface baffles and no baffles configurations were used. The torque values of a pitched blade turbine impeller were measured over a wide range of Reynolds numbers, and power numbers were calculated. The minimum power number was observed for the unbaffled tank. This was followed by surface baffles.
Anahtar Kelimeler
Proje Numarası
117M158
Kaynakça
- 1. Hemrajani, R.R. and Tatterson, G.B., 2004. Mechanically stirred vessels in Handbook of Industrial Mixing: Science and Practice, John Wiley&Sons, New Jersey.
- 2. Ayranci, I., Machado, M.B., Madej, A.M., Derksen, J.J., Nobes, D.S. and Kresta, S.M., 2012. Effect of geometry on the mechanisms for off-bottom solids suspension in a stirred tank, Chemical Engineering Science, 79: 163–176.
- 3. Assirelli, M., Bujalski, W., Eaglesham, A., Nienow, A.W., 2008. Macro- and micromixing studies in an unbaffled vessel agitated by a Rushton turbine, Chemical Engineering Science, 63: 35-46.
- 4. Myers, K.J. and Fasano, J.B., 2002. The influence of baffle off-bottom clearance on the solids suspension performance of pitched blade and high-efficiency impellers, Canadian Journal of Chemical Engineering, 70: 596-599.
- 5. Khazam, O. and Kresta, S.M., 2009. A novel geometry for solids drawdown in stirred tanks, Chemical Engineering Research & Design, 87(3A): 280-290.
- 6. Bates, R.L., Fondy P.L. and Corpstein, R.R., 1963. An examination of some geometric parameters of impeller power, Industrial & Engineering Chemistry Research, 2(4): 310–314.
- 7. Yianneskis, M., Popiolek, Z., Whitelaw, J.H., 1987. An experimental study of the steady and unsteady-flow characteristics of stirred reactors, Journal of Fluid Mechanics, 175: 537–555.
- 8. Ibrahim, S. and Nienow, A.W., 1995. Power curves and flow patterns for a range of impellers in Newtonian fluids: 40<Re<5x105, Chemical Engineering Research&Design, 73(A5): 485–491.
- 9. Armenante, P.M., Mazzarotta B. and Chang, G.M., 1999. Power consumption in stirred tanks provided with multiple pitched-blade turbines, Industrial & Engineering Chemistry Research, 38(7): 2809–2816.
- 10. Rutherford, K., Mahmoudi, S.M.S., Lee, K.C. and Yianneskis, M., 1996. The influence of Rushton impeller blade and disk thickness on the mixing characteristics of stirred vessels. Transactions of the Institution of Chemical Engineers, 74(A3): 369–378.
- 11. Rushton, J.H., Costich, E.W. and Everett, H.J., 1950. Power characteristics of mixing impellers, Chemical Engineering Progress, 46(8): 395–476.
- 12. S. Nagata, 1975. Mixing: Principles and Applications, John Wiley & Sons, New York.
- 13. Chapple, D., Kresta, S.M., Wall, A. and Afacan, A., 2002. The effect of impeller and tank geometry on power number for a pitched blade türbine, Transactions of the Institution of Chemical Engineers, 80(A): 364-372.
- 14. Machado, M.B., Bittorf, K.J., Vesselina T.R. and Kresta, S.M., 2013. Transition from turbulent to transitional flow in the top half of a stirred tank, Chemical Engineering Science, 98: 218-230.
Ayrıntılar
| Birincil Dil | Türkçe |
|---|---|
| Konular | Mühendislik |
| Bölüm | Araştırma Makalesi |
| Yazarlar | |
| Proje Numarası | 117M158 |
| Yayımlanma Tarihi | 25 Aralık 2020 |
| Gönderilme Tarihi | 28 Kasım 2019 |
| Kabul Tarihi | 7 Ekim 2020 |
| Yayımlandığı Sayı | Yıl 2020 Cilt: 9 Sayı: 4 |
