A sieve-tray column with 15 plates is used to prepare 99 percent methanol from a feed containing 40 percent methanol and 60 percent water (mole percent). The plates have 8 percent open area, ¹/₄-in. holes, and 2-in. weirs with segmental downcomers. 

(a) If the column is operated at atmospheric pressure, estimate the flooding limit based on conditions at the top of the column. What are the F factor and the pressure drop per plate at this limit? 

(b) For the flow rate calculated in part (a), determine the F factor and the pressure drop per plate near the bottom of the column. Which section of the column will flood first as the vapor rate is increased?