Distillation

Dear Mr. Lieberman – Which is best tray for good turn-downs? Our depropanizer has to operate at very variable rates.

---Roja, Venezuela

Roja – I assume this is a new tower you’re designing. Bubble cap trays are best. Your tower I.D. will be about 10% bigger than if you used a modern grid tray or valve tray. Bubble caps will operate efficiently at a far larger range of vapor flow than any other sort of tray.

---Norm