Feed at Minimum Reflux Mode

The trajectory of the intermediate section in a three-section column connects the trajectories of the top and bottom sections, and should join them in the cross-sections of the top and the bottom feeds (i.e., at trays above and below these cross-sections, the material balance should be valid). In the mode of minimum reflux, only two of three sections adjacent to one of the feeds Xpi or Xp2, called control  

Because in the mode of minimum reflux the intermediate section should be infinite, its trajectory should pass though one of its stationary points Sm or A+. Therefore, the following cases are feasible in minimum reflux mode (1) point A+ coincides with the composition at the tray above or below the cross-section of control feed (2) composition point at the trays of the intermediate section in the cross-section of control feed lies on the separatrix line, surface, or hypersurface of point Sm (i.e., in separatrix min-reflux region of intermediate section Reg , filled of trajectory bundle Sm — A+). In both cases, composition point at the tray of the top or bottom section, adjacent to the control feed, should lie in the separatrix min-reflux region of this section Re (5 - A+). 

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