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[Zauberberg]

When calculating CO2 equilibrium parameters (partial pressure and mole fractions in aqueous and liquid hydrocarbon phases) by using modified-empirical Henry's law and simulation software, I got the results indicating low pH: ranging from 3.9 to 4.6 for CO2 partial pressures being in the range og 0.07-2.80 bara. System pressures and temperatures are very moderate (below 150C and 8 bara). Somehow, I have a feeling that calculated pH value is extremely low; but I never had experiences with CO2 in my engineering past.

Since this is very critical issue regarding materials selection (including pipeline, phase separator, compressor loop etc.), any feedback related to this particular subject is highly appreciated.

Additional question is: how low it is feasible to go with pH without using exotic materials of construction? In refining days, I remember that 5.5 has been the lowest acceptable value for using CS (and this was accomplished by continuous injection of neutralizing chemicals and corrosion inhibitor). What factors should be addressed further in choosing appropriate design, apart from CO2 concentration and corresponding pH value?

Thanks in advance,