In a CDU overhead drum reflux, which are the advantages of a three phase separator versus a flooded one with a naphtha + gas outlet, a naphtha to reflux outlet and a water separation? And how can you estimate them? In both cases the reflux temperature is the same.
Ralph Ragsdale, Ragsdale Refining Courses, email@example.com
There will always be a gas product from this drum, unless there is a shortage of water. When virtually no water is available, the column is designed to operate at a pressure high enough to achieve condensing of the naphtha with air cooling alone. With that design, the gas will be in solution and flash out in downstream units.
At normal pressure in the CDU accumulator, your simulation software will calculate the quantities of gas, hydrocarbon liquid and water for you. Without the benefit of simulation software, the quantities are determined with a flash calculation.