Performance Evaluation of a Laboratory-Scale Single-Pass Shell-and-Tube Condense

Author : Gonzales, Elma Quiaonza
Major Adviser : Alcanzare, Edilberto A.
Committee Members : Movillon, Jovita L.; Arquiza, Apollo C.
Year : 1994
Month : April
Type : Thesis
Degree: BS
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The condenser designed for the distilling column for the production of a 70 mole percent ethanol vapor from a 10 mole percent ethanol feed solution was evaluated based on the capacity of the existing reboiler in the Chemical Engineering Laboratory of UPLB.

Due to constraints in using ethanol vapor, steam was used for the evaluation. Rates of steam equivalent to vapor to be produced by the distilling column, at total reflux, and reflux ratio equal to 0.73 (minimum reflux), 1, 2, and 4 were calculated. With these steam rates, required rates of cooling water were also determined.

For every reflux ratio, three trials were conducted. And for all runs done, at total reflux, an average of 97.78% of the theoretical Dass flowrates met the objectives of the study, which only means that mass rates of cooling water required condense all vapor are actually the theoretical mass flowrates. Since this is highly improbable because there is no insulation, three trials were again made for total reflux using the same volumetric flowrates of cooling water, to know the possible cause of errors.

The last three trials showed that an average of 77.10% of the theoretical Dass flowrates met the objectives of the study. On the other hand, when changed from total reflux to a particular reflux ratio, it was seen that the required cooling water for condensing the vapor is 30% – 40% less than the theoretical.

In using the existing condenser, it took around one hour before steady state was achieved at total reflux, and around half an hour when changed to the desired reflux ratio. This only means that two hours should be allotted just for the condenser during distillation.

Over-all heat transfer coefficients (U) were al so determined. Calculations show low heat transfer coefficient when compared to theoretical, that is, 6.1, 1.6, 1.9, 2.2 and 2.0 compared to 99.36, 79.77, 81.44, 83.81 and 83.72, respectively.

With the results obtained, although U decreased, it can be concluded that the condenser capacity is enough for part in distillation.

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