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How to keep the pH in neutralization pit neutra? Alkylation unit uses HF and in the neutralization pit we use KOH. The pH is very erratic ranging from 8-14.
 
Answers
09/05/2013 A: keith bowers, B and B Consulting, kebowers47@gmail.com
pH is, by nature HIGHLY non-linear. As an example, at pH=8.3, the H+ concentration is 0.000,000,03. Now most anything present at that concentration is insignificant. at ph=7.3, H+ is 0.000,000,3. Now how few molecules of KOH does it take to neutralize 0.000,000,27 molecules of acid?--just a pinch?
Perhaps this helps illustrate just how sensitive the pH is to even very minute additions of KOH in the range between say 4 to10.
If 'tighter control' of the pH is required, then going to a 2-stage neutralization process, the 2nd stage using diluted KOH greatly helps.
02/03/2012 A: Ralph Ragsdale, Ragsdale Refining Courses, ralph.ragsdale@att.net
Over time, collect the information and, by trial and error, develop your own table or plot of pH vs volume of KOH to dump in. As you train new operators, give him/her a copy of the table or plot for their use. Make necessary corrections to the table from time to time as necessary.