Question on Splitter Diagram 1

[JD P.E.]

I am working on gaining a better understanding of the operation of towers and am reading through "A Working Guide to Process Equipment".

My question is on the attached photo:

Feed flow rate of 10,000 lb/hr of 90% Water and 10% Alcohol
Heavy flow rate of 9,000 lb/hr of water
Light flow rate of 1,000 lb/hr of alcohol
Reflux flow rate of 10,000 lb/hr

My misunderstanding happens with the feed rate being 10,000 lb/hr and the reflux rate being 10,000 lb/hr. I have limited knowledge of the operation of towers, so this may be a dumb question.

How is the feed rate 10,000 lb/hr and the flow rate leaving the system a combined 20,000 lb/hr?

 

[LittleInch]

Badly drawn / incorrect diagram?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[JD P.E.]

That's what I'm leaning towards now.

 

[Latexman]

The reflux is not leaving the system. Draw a boundary around the column and only three streams cross the boundary, the feed, lights, and heavies. At SS, In = Out. 10,0000 = 9,000 + 1,000. I see no problems with the diagram.


Good Luck,
Latexman

 

[georgeverghese]

What type of alcohol - ethanol, methanol or propanol or some other?

 

[pierreick]

Hi,
If you and others want to learn about Distillation, consider these links:

http://www.separationprocesses.com/Mainmenu.htm

https://escholarship.org/uc/item/1b96n0xv#page-489

Pierre

 

[DominicLee]

In a distillation column, the feed is separated into its components based on their differing boiling points. The vaporized components rise up the column, while the condensed liquid flows downward.

 

[MortenA]

@JD,

Latexman is correct (i dont think the other read your post thoroughly ;-) So the reflux is internal and can (in theory) be any fraction of the inlet flow. Reflux is needed for improved separation of the components in the feed. The overhead is vapour (high energy) - energy is removed in the condenser - and by reintroducing this cooled stream back into the top of the column you take away some of the energy (added from the feed and from the reboiler). By cooling the light fraction you will improve separation because the heavy component(s) are more inclined to condense than the light.

Downside - increased energy consumption for cooling and heating.

--- Best regards, Morten Andersen

 

[pierreick]

hi,
On a safety point of view i'm not comfortable with PCV on diaphragm pump,better to add a second dedicated pump.
my view
Pierre