Studies on Gas Holdup and Ethanol Stripping Process Using a Bubble Column Reactor

Author : Odiamar, Reynaldo Veneracion
Major Adviser : Chay, Pham Binh
Committee Members :
Year : 1989
Month : March
Type : Thesis
Degree: BS
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Gas holdup and ethanol stripping process in bubble column reactor were studied to process conditions of the ethanol stripping rate in the fermentation.

The gas holdup of distilled water in a (31.5 mm I.D., 1000 mm in length) bubble column reactor (BCR) at different process conditions; temperature (25, 30, 40 and 50°C), BCR liquid height (300, 600 and 900 mm) and volumetric flow rate (0.5, 0.75, 3, 6 and 9mm) was studied. The gas holdup of 5, 10 and 15% (w/v) and (v/v) of glucose and aqueous ethanol solutions, respectively was likewise determined. Gas holdup is a BCR liquid height and superficial liquid velocity (SLV) dependent variable. Increasing concentration of glucose and aqueous ethanol solutions also increases gas holdup. The optimum process conditions that affect the maximum gas holdup were used in the ethanol stripping process.

The ethanol stripping rate in an aqueous ethanol solution was studied at the given process conditions. The stripping rate is time and initial ethanol concentration dependent. On the other hand, the stripping rate decreases as the initial ethanol concentration increases. Also, there is linear relationship between time and ethanol stripping rate.

Simultaneous fermentation and ethanol stripping process was studied at process conditions similar to that of previously conducted experiment. Maximum ethanol conversion is obtained by using the stripping process as compared to the theoretical conversion of glucose ethanol. The residual glucose in the fermentation broth was below 3 g/l after 24 hr of fermentation with initial sugar concentration of 158 g/l. The ethanol concentration was 43.4 g/l after 37 hr. Therefore, substrate concentration could be increased in the fermentation because product inhibition is already eliminated. Consequently, ethanol production rate would increase.

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