Correlation of sieve plate efficiency as a function of operating variables
Date
1958
Authors
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Publisher
University of Delaware
Abstract
The effects of three operating variables; liquid rate, outlet weir height, and gas rate, on overall plate efficiency on a sieve plat have been studied, using the system ammonia-air-water. Ammonia was absorbed from air into water, using a single 24-in. diameter tray which had a perforated area of 0.2150 square feet. The perforations consisted of 2,534 1/8-in. diameter holes on 3/8-in equilateral triangular centers and provided a free area equal to 7.69% of the superficial tower free area. The superficial tower free area (2.795 ft. sq.) is defined as the tower internal area less the area of the segmental inlet water down-comer. Liquid rates ranged from 1,740 to 10,700 lbs. per (hr.)(ft. sq.); gas rates ranged from 860 to 1810 lbs. per (hr.)(ft. sq.); and weir heights ranged from zero to 4.70 inches. The gas and liquid rates reported in this thesis are calculated on the same basis as the plate free area calculation, i.e., using the superficial tower free area as defined above in the calculation of column free area. ☐ Murphree plate efficiencies from 60.0% to 94.0% were observed. From these data and analysis of the statistical program, a general correlation has been computed to define the relationship of Murphree plate efficiency to the three operating variables. ☐ The data and statistically derived expression show that plate efficiency can be increased by increasing the liquid rate and/or by increasing the outlet weir height. Increasing weir height proved to have the greatest effect on efficiency up to about 3.7 inches; at the highest height, 4.7 inches, it was noted that efficiency did not increase as one would predict from the derived efficiency equation. This run points to the limit of use of the equation to regions of stable plate operation.
Description
Keywords
Distillation towers