2 replies to this topic

[alejovall]

Hello,

I need to design a sour water stripping tower for my undergraduate project (a tray-type column) to separate H2S and NH3 from water and I have some problems.

1) I don´t have reliable equilibrium data for the system H2S-NH3-water and I would need it in order to estimate relative volatilities. Where could I get it?? (according to Coulson & Richardson´s vol.6, there are some articles from Newmann which show diagrams about it but I cannot access them).

2) I have to design it on my own without the help of any simulation software. I am not sure about which would be the best method of design (not rigurous, approximate or shortcut). I have thought about the Fenske-Underwood-Gilliland method for multicomponent distillation and also the Edmister method. I don´t know which is most accurate of those or if there is any other better.

3) In case I want to design a pumparound cooler stream instead of the classic condenser at the top of the column, I don´t know how to implement that change into the method on design.

If you could help me, I would be very grateful.

Thanks in advance.

jrodrioro@gmail.com

[djack77494]

alejovall,
I think you've got a tough problem. This is not a simple three component equilibrium. You have a reacting system containing an acid (H2S) and a base (NH3). They form salts (NH4HS and [NH4]2S) that I suspect would remain behind as a solid if you performed a mild boiling of your solution. If you perform more violent/higher temperature boiling, you'd likely decompose the salt which would then recombine in your overhead system.
Good Luck,
Doug

[mbeychok]

Alejovall:

The first publication about the manual tray-by-tray design method of sour water strippers was published in 1967 in this book (starting on page 158):

--- M.R. Beychok, "Aqueous Wastes from Petroleum and Petrochemical Plants", John Wiley & Sons, New York and London, 1967

Shortly thereafter, the manual design method was also presented at a World Petroleum Congress:

--- M.R. Beychok, "Design of Sour Water Strippers", Seventh World Petroleum Congress, Mexico City, April 1967

Both of those publications were before we had any desktop computers and simulation programs. One or both of them might be available in your university library. The book is now out-of-print and you cannot purchase a copy even if you wanted to. If you find either of the publications, let me know, because there is one slight error which must be corrected.

If you cannot find a copy, I no longer have any and regret that I cannot help you any further,