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In our CDU we have been observing very high SOx values. This is coupled with high chlorides and low pH. What are the possible sources of SOx (SO4) and causes?
26/03/2020 A: sam lordo, Becht Engineering, salordo@comcast.net
The SOX is from O2 incursion, either at a pump suction, or from a vac tower ovhd leak, especially if the desalter wash water make up is from the vac tower ovhd.

With respect to the desalter, your wash water may be contaminated with O2, like above, from vac tower ovhd make up or external water sources, like fire water, fresh domestic water, etc.. Look for a O2 source.. the O2 then reacts with H2S to form SO4

Use of a NO2 scavenger is helpful in addressing this problem.