Spent Caustic Scrubber

[padovano]

We use caustic soda to eliminate H2S present in LPG. The present solution has a PH reading of 12.5 and a conductivity of 6.3. We have never done these measurements before so we don't have any reference on when the solution will be saturated. I would like to know if there are MINIMUM VALUES OF PH AND CONDUCTIVITY that will indicate that the solution is saturated and should be changed. For now we are depending on a positive Doctor test.

 

[ash9144]

pH above 9.0 and your good.
I don't think conductivity tells you anything.

 

[mbeychok]

padovan:

I great many years ago, when I worked in a refinery, we sampled the caustic once a shift and the laboratory ran a test called "Percent spent caustic" which involved titration to the Methyl Orange endpoint. We found that was the best way to determine when the caustic needed changing.

Milton Beychok
(Visit me at www.air-dispersion.com)
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