What is the difference between an effluent cooler and a bottom cooler?

It’s explained in the parentheses after the first sentence: the effluent cooler is equivalent to the feed preheater; the difference might lie in whether there is a feed inlet and an outlet

Bottom cooler: Cooling device for discharge at the bottom of the tower? These names are somewhat related to the manufacturing process.

What is the meaning of \"duty\"? I couldn’t understand not a single one of the three sentences; please help

:P Effluent cooler (or feed preheater): 10 percent of the cooler’s capacity (or the preheater’s capacity), or 5 percent of the heat exchange capacity between feed and effluent, whichever is greater. Effluent cooler (or feed preheater): 10% of the cooling capacity (or preheating capacity), or 5% of the heat exchange volume between feed and effluent, with the higher value being used. * Reboiler: 5 percent of the heat transfer in the feed/bottom exchanger, or 10 percent of the reboiler’s heat input, whichever is greater. Reboiler: The greater of 5 percent of the heat transferred in the feed/bottom exchanger and 10 percent of the heat supplied to the reboiler. * Bottom cooler: 10 percent of the cooler’s capacity, or 5 percent of the heat transfer rate between the feed and the bottom exchanger, whichever is greater. Bottom cooler: 10% of the cooling capacity, or 5% of the heat transfer amount between the feed material and the bottom exchanger – the higher of these two values applies.

From a process perspective, in many cases the distillate cooler and the bottom reboiler are the same thing; it’s unclear why there are two different names for them