Packed column design plates versus packing

The curves represent a plot of Log.(/V),(Reduced Plate height)against Log.(v), (Reduced Velocity). The lower the Log.(/7) curve versus the Log.(v) curve the better the column is packed. At low velocities the (B) term dominates and at high velocities the (C) term dominates as in the Van Deemter equation. The best column efficiency is achieved when the minimum is about 2 particle diameters and thus, Log (.ft) Is about 0.35. The minimum value for (H) as predicted by the Van Deemter equation has also been shown to be about two particle diameters. The optimum reduced velocity is in the range of 3 to 5 that is Log.(v ) takes values between 0.3 and 0.5. The Knox equation is a simple and effective method of examining the quality of a given column but, as stated before, is not nearly so useful In column design due to the empirical nature of the constants. 

Packed Columns versus Plate Columns Packed columns are usually specified when plate devices would not be feasible because of undesirable fluid charac teristics or some special design requirement. Conditions favoring packed columns are ... 

Fig. 7.3. Hffect of operating and design parameters on the column ID. (a) Linear velocity (A) and optimum r/p/L ( ) and plate count (c) versus column ID. (b) Loading (mg prtxluct/g packing) (A) and yield ( ) versus column ID. (c) Column length (A) and cycle time ( ) versus column ID. (d) Total cost ( /g) ( ) and production rate ( ) versus column ID.

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See also in sourсe #XX -- [ ]

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