4 replies to this topic

[surulo]

Hello
I am a student making a project about Stretford process. So long I have seen it is not an easy one. It deals with an absorption column with chemical reaction. The column absorbs H2S from a gas with a vanadium pentoxide solution with ADA, when the H2S is absorbed it is oxidized to S, and the vanadium reduces from valence 5 to valence 4. Then it is oxidized again with ADA and air. My question basically is, does someone know how to design the absorption column with the chemical reaction? I have consulted Perry, Kohl, Treybal, Coulson and Ludwig for the absorption columns with chemical reactions, though I have found these books don't deal with H2S nor vanadium. Does someone know any article, book or any sort of publication that would help me to deal this problem? If anyone does, I would be gratefull.

[Art Montemayor]

Surulo:

Since you don't tell us, I have to presume the following:

1. You are a student assigned by your professor to do a study on the Stretford Process as a formal assignment over which you will be graded for accuracy, and engineering definition.
2. You have been told to design the major equipment in the process using the parameters given in literature as basic data.
3. You are presently trying to find the background information on the process so that you can attempt to design the major equipment - especially the H₂S absorber.

Am I correct? If not, please clarify.

If I am correct, then I take this opportunity to once again state the obvious and pracitcal aspects of trying to cope with the design of licensed technology. And I specifically address this to Chemical Engineering professors who don't know any better or who are too lazy to gather the necessary basic data and design basis for their students who they assign to look into licensed processes: Licensed processes are just exactly that. They are licensed and held within certain engineering companies who have the basic know-how and who have invested the research and experience necessary to know the arcane and complex information to make the process work. That's why they market the design and also warrant the results. It is ludicrous for professors to think that engineering students are going to gain any profitable knowledge - other than frustration and failure - from trying to do what it takes years and years of experience and know-how to do. It is just not possible. If professors want to assign these type of problems to students, then they should also issue the design basis and the basic data (& available references) necessary to carry the task out. This is not only practical engineering, it is the only way it is done in industrial projects. I fully sponsor the idea of having engineering students learn how to research and search for information on their own. However, when it comes to licensed processes practically all the vital and important information is locked-in and in the hands of the licensor. And the licensor is not hardly going to give this information out - especially on a free basis.

I regret I can't offer you any other direct help but the above. I wish I had the basic data you require, but even if I did, it probably would belong to my employer and I would not be free to divulge it to others.

You need direct and specific information from your professor or instructor - and you should get it if he/she expects you to do the work. Tell him/her I told you so and I should know - after 46 years of being in this business. Good luck.

[djack77494]

Surulo:

Though I agree with everything Art says, you can nonetheless do an academic exercise of modelling this very interesting process. The results you get may be of interest to you and your professor, but will not yield anything of commercial interest. There are lots of "tricks of the trade" and proprietary knowledge that is not intuitive or easily obtained but is crucial for licensed process. That's why you pay the licensor to provide you with the design.

With that introduction, you can attempt to model the Stretford reaction. It's not really very difficult or uncommon. You have an adsorbtion of a minor component from your gaseous phase into a liquid phase sorbent solution. This is quite common - e.g. Cautic Scrubbers. Now that you have identified the type of problem you have, look into the literature for how this type of problem is solved.

Good luck,
Doug

[surulo]

Thank you Art and djack77494, I will follow your instructions and will post my results in order to have you informed.

[Zauberberg]

Hello,

and don't forget to tell your professor he's lazy, as Mr. Montemayor said:)
I am sure he'll be full of understanding; maybe you will become his favourite student.

Best regards.