2011 Fiscal Year Final Research Report
Effects of Aeration on the Flow and Mixing States of Fluids Possessing Yield Stress in a Stirred Vessel when a Cavern Region Occurs
| Project/Area Number |
21560775
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Properties in chemical engineering process/Transfer operation/Unit operation
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| Research Institution | Yokohama National University |
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Principal Investigator |
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| Project Period (FY) |
2009 – 2011
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| Keywords | ミキシング / 通気操作 / 降伏応力流体 / カバーン / 撹拌槽 |
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| Research Abstract |
In this study, the effects of aeration and agitation conditions, such as aeration rate, Q[L/min], and impeller rotational speed, n[n^<-1>], on the mixing rate for slurry-like fluids possessing a yield stress were quantitatively investigated in a stirred vessel equipped with a concave impeller, when a Cavern region occurs. We defined the mixing rate constant, k_s[n^<-1>], based on the dynamic change of the ratio of the unmixed area to the whole vertical area of the vessel, using an image analysis method. It was found that regardless of the value of Q, ks increased drastically with an increase in n, when the rotational speed was above a certain value, and this was effective in improving the mixing state. It was also found that this improvement was attributable to the fact that the floating pattern of the bubbles due to the discharge flow from the impeller changed.
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