Kabarcıklı kolonlarda yüksek basınçta kabarcık hidrodinamiği

Abstract

ÖZET Doktora Tezi KABARCIKLI KOLONLARDA YÜKSEK BASINÇTA KABARCIK HİDRODİNAMİĞİ Ertuğrul ERKOÇ Atatürk Üniversitesi Fen Bilimleri Enstitüsü Kimya Mühendisliği Anabilim Dalı Danışman: Prof. Dr. Sinan YAPICI Kabarcıklı reaktörler kimyasal ve biyokimyasal endüstrilerde yaygın bir şekilde kullanılmaktadır. Bu endüstrilerdeki birçok uygulama yüksek basınç şartlan gerektirmektedir. Bu şartlarda kabarcıklı kolonların hidrodinamiği oldukça karmaşıktır ve yapılan birçok çalışmaya rağmen halen tam anlaşılabilmiş değildir. Kabarcıklı kolonlarda gerçekleşen olayları iyi anlayıp modelleyebilmek için bu şartlarda kaliteli deneysel verilere ihtiyaç vardır. Bu çalışmada, 16,15 cm çapındaki paslanmaz çelik kolonda, 1 MPa basınçta dört noktalı optik prob kullanarak kabarcık boyut ve hız dağılımı elde edilmiştir. Kolon yüksekliğinin kolon çapına oranının 5 ve daha büyük olduğu durumlarda bu oranın gaz holdupa etkisinin olmadığı, belli bir gaz besleme hızına kadar gaz hızı ile kabarcık boyutunun büyüdüğü ve bu değerden sonra ortalama kabarcık boyutunun küçüldüğü görülmüştür. Yine yükselen gaz besleme hızı ile kabarcık hızının arttığı tespit edilmiştir. Sistemde bulunan en büyük kabarcık boyutu, kolonun merkezinde ve en yüksek gaz besleme hızında 0,8 cm kiriş uzunluğu olarak ölçülmüştür. Düşük gaz besleme hızlarında kabarcık boyut dağılımı daha uniform iken, hız arttıkça kabarcık boyut dağılımdaki pikin genişlediği ve daha farklı değerdeki kabarcık boyutlarının aynı anda bir arada var olduğu tespit edilmiştir. 2005, 97 sayfa Anahtar Kelimeler: Kabarcık boyutu, kabarcık yükselme hızı, dört noktalı optik prob,kabarcıkh kolonABSTRACT PhD Thesis BUBBLE HYDRODYNAMICS IN HIGH PRESSURE BUBBLE COLUMN REACTORS Ertuğrul ERKOÇ Atatürk University Graduate School of Natural and Applied Sciences Department of Chemical Engineering Supervisor: Prof. Dr. Sinan YAPICI Bubble column reactors are widely used in the chemical and biochemical industries. Most of the current applications of bubble column reactors in the chemical process industry require operation at high-pressure conditions. The fundamental description of bubble column hydrodynamics under these conditions is very complex and complete understanding has not yet been established in spite of concerted research efforts. In order to improve our ability to quantify phenomena in bubble columns, it is essential that precise and quality experimental information is available to advance the state of the art in bubble column design and operation. In this study in a 16.15 cm stainless steel column, under 1 MPa pressure, bubble dimension and rise velocity experiments were performed using four point optical probe. It was shown that for the given conditions, i.e. aspect ratio is equal or greater than 5, the aspect ratio has no significant effect on gas holdup. Further, till a specific value of gas superficial velocity, the bubble dimensions increased with gas superficial velocity. Above this velocity, it was observed that the bubble dimensions decrease with increasing gas velocity. The bubble rise velocity increased with increasing gas superficial velocity. The biggest bubble dimension in the column was observed in the center of the column in the highest superficial gas velocity used and recorded as 0.8 cm in terms of chord length. While the distribution in the low gas velocities is more uniform, in higher gas velocities the distribution shifted towards higher bubble dimensions and small and big bubbles coexisted at the same time. 2005, 97 pages Keywords: Bubble dimensions, bubble rise velocity, four point optical probe,bubble column

ABSTRACT PhD Thesis BUBBLE HYDRODYNAMICS IN HIGH PRESSURE BUBBLE COLUMN REACTORS Ertuğrul ERKOÇ Atatürk University Graduate School of Natural and Applied Sciences Department of Chemical Engineering Supervisor: Prof. Dr. Sinan YAPICI Bubble column reactors are widely used in the chemical and biochemical industries. Most of the current applications of bubble column reactors in the chemical process industry require operation at high-pressure conditions. The fundamental description of bubble column hydrodynamics under these conditions is very complex and complete understanding has not yet been established in spite of concerted research efforts. In order to improve our ability to quantify phenomena in bubble columns, it is essential that precise and quality experimental information is available to advance the state of the art in bubble column design and operation. In this study in a 16.15 cm stainless steel column, under 1 MPa pressure, bubble dimension and rise velocity experiments were performed using four point optical probe. It was shown that for the given conditions, i.e. aspect ratio is equal or greater than 5, the aspect ratio has no significant effect on gas holdup. Further, till a specific value of gas superficial velocity, the bubble dimensions increased with gas superficial velocity. Above this velocity, it was observed that the bubble dimensions decrease with increasing gas velocity. The bubble rise velocity increased with increasing gas superficial velocity. The biggest bubble dimension in the column was observed in the center of the column in the highest superficial gas velocity used and recorded as 0.8 cm in terms of chord length. While the distribution in the low gas velocities is more uniform, in higher gas velocities the distribution shifted towards higher bubble dimensions and small and big bubbles coexisted at the same time. 2005, 97 pages Keywords: Bubble dimensions, bubble rise velocity, four point optical probe,bubble column