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Home General Info Mock Expt CSTR Distillation Bubble PFR

 

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Bubble cap trays were developed to promote a high degree of contact between the downward flowing liquid and the upward flowing vapor within a distillation column. Bubble cap trays are not typically used any more when new distillation columns are designed and constructed, but we’ll ignore this fact here as there is still much you can learn from the study of bubble cap trays. In addition, there are many older columns in use that contain bubble cap trays. You can learn more about bubble cap trays by reading the references you will find in this brief introduction to the theory involved.

In this experiment you will investigate two important parameters associated with columns that use bubble cap trays. The first parameter is the pressure drop that the vapor experiences as it passes through a bubble cap tray. This is clearly important in designing a distillation column, in order to determine the overall pressure drop through the column. The second parameter is known as the hydraulic gradient. Effectively the hydraulic gradient is the difference in the depth of the liquid across the tray; it provides the driving force for liquid to flow across the tray. If the hydraulic gradient is too large, then the depth of liquid near where it enters the tray is large, and the gas can’t bubble through the liquid easily. This leads to poor vapor-liquid contact and an inefficient column. If the hydraulic gradient is too small, dry spots can form on the tray, again leading to an inefficient column.

last update: 01/25/00

Dr. Carl Lund
306 Furnas Hall
Office Hours: MWF 4-5 PM, anytime I'm free, or by appointment
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Mr. Chimin Sang, Teaching Assitant
322 Furnas Hall
Office Hours: 4-5 W, 3-4 F, or by appointment
Phone (with voice mail): 645-2911 x2226
E-Mail: csang@eng.buffalo.edu