Mass transfer efficiency structured packing performance

Structured packings have replaced trays and random packings as their cost has decreased and more is known of their performance behavior. Initially thought to be appropriate only for high vacuum distillations, they are now used for absorbers, strippers, and pressure distillations. Because of their open structure (over 90% voids) and large specific surface areas, their mass transfer efficiency is high when proper distribution of liquid and gas over the cross section can be maintained. Table 13.15 shows a comparison of features of several commercial makes of structured packings. 

GPC separations require an interaction-free phase system. The separation efficiency in GPC is proportional to the pore volume, which limits the decrease in column dimensions. In many cases, GPC analyses are performed on serial combinations of columns. In most applications, silica and surface-modified silica columns do not meet the requirements for GPC columns and polymeric packings are preferred. Important characteristics for GPC column packings are the inertness of the sorbent material (chemistry), the accessibility of the pore structure, a high pore volume, and fast diffusion (optimal mass transfer) [la). 

---