Caustic Scrubbers
Caustic Scrubbers
(OP)
I am to put in place a monitoring system on the NaOH solution been used in washing H2S from the LPG stream. I want to either check on the concentration of sulphur in the solution or analyse the pH of the solution. I would like to know which of the methods is best. I would really appreciate detail explanation of the chosen method.





RE: Caustic Scrubbers
Never seen on line sulfur analyzer.
So control your scrubber pH at 9-10 and you should have no issues.
RE: Caustic Scrubbers
RE: Caustic Scrubbers
RE: Caustic Scrubbers
JMW
www.ViscoAnalyser.com
RE: Caustic Scrubbers
The pH needs to be monitored on-line, at any rate. Best location is the scrubber sump. Be careful about electrode specification. some glass electrodes can be a problem at pH>9. I have seen too often electrodes becoming very slow-responding due to a thin layer building up on the glass. This renders process control unstable.
The S-- SH- concentration is needed because you want to control the overall load of your liquid loops. So I'd say you need both.
on-line pH electrode
Sulfides load done on a regular basis, in lab
This way you can properly adjust the bleed (blow-off) rate.
Just one thing: I do not like much the caustic scrubbers for H2S, bleach is much better. H2S --> NaOH mass transfer is not efficient.
RE: Caustic Scrubbers
RE: Caustic Scrubbers