Distillation

Dear Norman – I attended your seminar in Toledo in 2008. Is it okay to have the outlet weir of a tray lower than the bottom edge of the downcomer from the tray above?

---Carl

Carl, if the crest height plus the weir height exceeds the downcomer clearance, this should be okay. It’s called a dynamic seal. To calculate the crest height in inches of clear liquid:

0.4 (GPM per inch of weir)^0.67

GPM is hot U.S. gallons per minute

---Norm