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The purpose of Caustic injection in Crude is maximization of conversion of MgCl and CalCl into NaCl. Can anyone explain how this happens?
 
Answers
24/03/2010 A: Berthold Otzisk, Kurita Europe GmbH, Berthold.Otzisk@kurita.eu
Crude oil contains 80-95% MgCl2 and 10-15% CaCl2. The chlorides of these salts can enter the overhead system to cause significant corrosion.
A strong base like NaOH will react with a strong acid like HCl to give the very stable salt NaCl. This salt is heat stable and will stay with the atmospheric residue. Less corrosion will be observed in the overhead system.
NaOH injection is often limited because of Na contamination of downstream catalysts.
Kurita┬┤s ACF Technology can help to avoid contamination of the catalysts.
15/03/2010 A: AMIYA LAHIRI, AK Associate, lahiri04k@rediffmail.com
The formation of HCL is as a result of dissociation of Mg and Ca chlorides. Na-chloride is not dissociated and by adding caustic we convert these into Na-chloride by the reaction
MgCl2 + 2NaOH = MgO + 2NaCl + H2O
CaCl2 + 2NaOH = CaO + 2NaCl + H2O
14/03/2010 A: Ralph Ragsdale, Ragsdale Refining Courses, ralph.ragsdale@att.net
My understanding is that the caustic is being injected to react with HCL and to neutralize CO2. About one-half of refineries globally are injecting caustic.