Caustic scrubbing 2

[AndreChE]

Hello all

I would like to understand a little bit more the caustic scrubbing technology in ethylene plants.

Does anyone know papers or websites related?

Thanks
AndreChE

 

[jalvarez]

Hi AndreChe
Caustic scrubbing is very common in ethylene crackers, but there exist many alternatives. We use a caustic scrubber in an ethane cracker. I was involved in some jobs there.
If you can be more specific, I would try to help.
Open literature on this subject is difficult to find. In the mentioned plant the technical people sent a paper to the HP magazine, (and it was publicized) more than 20 years ago, but it was very specific for our conditions, foam problems, efficiency, etc.
Are you trying to design or evaluate problems?
Have a safe day.
J. Alvarez

 

[AndreChE]

Hi jalvarez

I am trying to evaluate. Sometimes we have flooding problems. I am insterested in efficiencies, foam, flooding - troubleshooting and evaluation.

I have a paper from HP, May 1978 - Optimize caustic scrubbing systems, Marcello Picciotti. very good one!


Thank you
AndreChE

 

[jalvarez]

AndreChE:
Marcelo Picciotti was one excellent advisor/consultant by the times we started up our plant, he used to work for Technipetrol.
The paper we wrote was about our experience, and actually it was publicized in the Oil and Gas Journal Magazine, maybe 1982/83's, not in the HP. I was confused due to the paper from Marcelo you've found. I remember it very well.
Our scrubber has two stacked stages in one scrubber/column.
We were cracking ethane, and due to different contaminants we experienced some foaming problems in the scrubber. This caused problems with the levels in the tower, obviously. Sometimes we needed to add a liquid antifoam, a dimethyl polisiloxane from Dow Corning. Later on, we changed, because the antifoam agent was difficult to use, and sometimes, dosing a little excess of the chemical, the results were opposite to what you expected! But I don't remember the supplier. If you have this problem, maybe you need to request the help from Coastal or Oakite, among others.
As the cracked gas from the scrubber feeds the last stage of the cracked gas compressor, we had some caustic carry over and damage in its laberinthyc seals, made in aluminum. We simply change them to stainless steel.
For removal of caustic the scrubber had a wire mesh in the top (outlet of cracked gas) sprayed with demin water, very low flow to avoid the dilution of the caustic (20% at the top).
We were lucky that the ethane we fed was very low in CO2 concentration, as the scrubber was undersized by our techonogist. Nowadays, I think that other methods are preferrable to caustic scrubbing.
It's all I can remember -not to much, maybe- I will revise my papers and, if I found something of interest, I will rewrite...
Good luck.
J. Alvarez

 

[AndreChE]

Ok thank you.

I will look for that paper next week.

Our problem is more related with fouling, pressure drop and flooding.

The scrubber is located before the last compressor stage, between the 4th and the 5th.

Please let me know more information. For me, I will do the same.

Thanks
AndreChE