7 Design variables
Tray design engineers have many decisions to make. The following design variables
have already been described briefly: number of flow passes, outlet weir height, percentage
bubbling area, and percentage downcomer area. Most importantly, the column’s
diameter needs to be determined. Liquid and vapor superficial velocities must
not be excessive, nor must they be too low. Large-diameter columns are, of course,
more expensive than small-diameter columns. As a column’s diameter is increased,
so is the shell’s thickness.