Example $6\mathrm{.}6$ Back$-$Calculation of Tray Efficiency for a Refinery Absorber

The following table provides performance data for a trayed absorber in a Texas petroleum refinery, as

reported by Drickamer and Bradford $[6].$ Based on these data, back$-$calculate the overall stage efficiency

for $n-$butane and compare the result with the Drickamer$-$Bradford correlation $(6-42).$ Lean oil and rich

gas enter the tower, and rich oil and lean gas leave the tower.