Here’s a calculator that can be used to determine approximate energy requirements for specific amounts of ethanol recovery. This is the ideal/perfect situation setup, actual heat recovery rates will be lower so long as you’re obeying the laws of thermodynamics… which everyone should do.
https://drive.google.com/open?id=1IOTKDyLu3lmWqnNgrOjpZUZNUFqjIwSQ