Caustic tower fouling in ethylene plants

[Leoner]

I´m searching about fouling in caustic towers.

Acid gases, like CO2 and H2S are removed from the cracked gas in an olefin plant by countercurrent contact and scrubbing with recirculating caustic solutions.

Fouling, emulsification anf foaming are the 3 major problems encountered in the caustic system.

Caustic tower fouling is thought of as a function of acetaldehyde concentration and an aldol condensation reaction. In the presence of caustic, carbonyl compounds can undergo conensation to form heavy materials. The product of this reaction has characteristically yellow color. It is called "yellow oil".

I need more information about this phenomena and about caustic tower operation.

I´m looking for a paper or another article that could help me.

 

[TD2K]

Interesting. We had a two stage circulating caustic tower in our ethylene plant (feedstock was ethane) after the cracked gas compressor. Upper loop strength was about 10% or so caustic I believe, lower loop design was supposed to be 0.5% but it ran higher due to problems in too much CO2 in the scrubbed gas.

As far as I recall, we never had any foaming or fouling problems. Haven't seen any papers on this that I could direct you to.