ISSN:
0001-1541
Keywords:
Chemistry
;
Chemical Engineering
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Process Engineering, Biotechnology, Nutrition Technology
Notes:
The performance of sieve trays in the rectification of the methanol-water system without entrainment or leakage from the perforations was studied in an 8-in.-diameter five-tray column. The trays had a 2-in. weir height and 4-in. length of liquid path. Three tray geometries were studied: 1/4-in. diameter holes on 3/4-in. triangular spacing, 1/8-in. holes on 3/8-in. triangular spacing, and 3/16-in. on 7/16-in. triangular spacing. The superficial vapor velocity was varied from 2.2 ft./sec. to the limit of stable operation, which for this apparatus was 4.4 ft./sec. The ratio LM/VM within the column was varied from 1 to 0.5. The Murphree plate efficiency varied greatly from 105% at low concentration to 82% at high concentrations of methanol. Variations of 10 or 12 efficiency % were noted owing to changing velocities and tray geometries. Measurements of concentration gradients, foam heights, and gas pressure drops are also reported. This paper proposes a method of calculating the point efficiency and the number of individual-phase mass transfer units independent of the actual concentration gradient on the tray.The method is applied to the methanol-water data, and calculated point efficiencies range from 50 to 65%. The value of 1/NL for the methanol-water system is found to be small. The values of NG and the effect of the velocity on NG are believed to be the first in the literature for a tray in distillation operation. The effect of velocity is shown to be in agreement with the theory proposed by Gerster and co-workers. It is shown that kG' aG decreases for increasing free area and increasing hole size. Finally variation in LM/VM is shown to have little effect on EMV.
Additional Material:
12 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/aic.690060307
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