$17.$ The $\_\_$ correlation provides a way to estimate the between the actual and minimum number of stages required for a given ratio in distillation columns, helping in the $\_\_$ design.

$18.$ Determining the $\_\_$ reflux ratio is crucial for economic operation, as it represents a balance between and costs, impacting the and $\_\_\_\_$ of the distillation operation.

$19.\_\_$ and equations are essential for calculating the conditions necessary for achieving a desired separation, particularly in determining the reflux ratio and the $\_\_\_\_$ flow rates in the column.

$20.$ The concept of $\_\_$ in a distillation column refers to operating at a condition where no is produced, allowing for the calculation of the number of stages and $\_\_$ analysis of the separation process...