×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Caustic Soda Scrubber

thread483-407616

Caustic Soda Scrubber

Caustic Soda Scrubber

(OP)
Hello All, I have a caustic soda scrubber (NaOH) to eliminate mercaptanes from butane. It is a batch. The concentration of NaOH at the begining of run is 30%. The solution usually gets spent when the concentration is around 10%. Recently, we discovered that, the NaOH solution gets spent when the concentration is still at above 20%. this has happened twice already.

I would like to know if any body has witness this phenomenon and how it was resolved.
Replies continue below

Recommended for you

RE: Caustic Soda Scrubber

Criterion for spent NaOH is when mercaptans in exit sweet butane exceeds a certain limit?

If that is the case, then something has changed in the C4 sweetening contactor...

RE: Caustic Soda Scrubber

(OP)
We carry out "Doctor Test" on butane at the exit of contactor. The test was positive. The problem is, the test use to be positive when the concentration of NaOH is around 11%. But presently the test is positive when the concentration is above 20%. The quality and flow rate of butane is the same.

RE: Caustic Soda Scrubber

Have you examined the internals? You may not be getting good flow distribution and poor scrubbing effectiveness.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: Caustic Soda Scrubber

Presume this is a once through loop from the NaOH side - ie no regeneration of caustic.

What about the H2S and RSH loading in the feed C4 ? Is there some residual water in the feed C4 which may be H2S saturated ?

RE: Caustic Soda Scrubber

(OP)
we isolated the scrubber and discovered that it was filled with different crystal blocks. This created preferential passages in the drum. we washed the scrubber and it`s now back in service.

RE: Caustic Soda Scrubber

That is good to hear. These crystals may be from residual water in the feed C4 that is reacting with caustic in this scrubber - if there is there a coalescer unit upstream of this scrubber to remove trace water from this C4 stream, check if this unit is working well.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


News
Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close